BOOK REVIEWS

Book Reviews

Optical and Electro-Optical Information ProcessingEdited by JAMES T. TIPPETT, DAVID A. BERKOWITZ, LEWISC. CLAPP, CHARLES J. KOESTER, and ALEXANDER VANDER-BURGH, JR. The MIT Press, Cambridge, Massachusetts, 1965.Pp. xv+780. Price $30.00.

This volume comprises the proceedings of the Symposium onOptical and Electro-Optical Information Processing Technologywhich was held in Boston, Massachusetts 9 and 10 November1964. There are 39 papers presented, including 25 describing de-vices and methods, both real and proposed, 8 dealing with coherentoptical processing (including holography) and 6 dealing with sys-tems. The subject matter ranges from a description of injectionlasers to abstract theory of optical data processing. The firstarticle, "An Optically Accessed Memory Using the LippmannProcess for Information Storage," by H. Fleisher et al., describesin detail both read-in and read-out techniques for storing infor-mation within a photographic emulsion. The fifth article, "Con-tribution of Diffraction Optics to Optical Information Tech-nology," by Guy Lansraux, discusses apodization techniques(amplitude filtering) for increasing the packing density of infor-mation storage. Unfortunately, he introduces as a raison d'etre ofhis work the statement ". . . most of the (photographic) emul-sions, available at the present time have either ultrafine grainwith a low gamma or a very high gamma with a coarse grain." Infact, just the opposite is true, so that apodization techniques do notrepresent the only means for increasing the packing density, asstated in the article. The work discussed is quite interesting, how-ever, and the technique should prove to be quite useful in datastorage.

Chapter 6, "Recent Developments in Coherent Optical Tech-nology," by Louis J. Cutrona, describes both the mathematics of,and the optical systems for, various operations on signals, such asauto- and cross-correlations, spectrum analysis, filtering, andothers including wavefront reconstruction. Chapter 7, "CharacterReading by Optical Spatial Filtering," by A. Vander Lugt et at..describes a character-recognition system using optical spatialfiltering, and includes a clear, concise mathematical description ofspatial filtering. Chapter 8 "Coherent Optical Systems for DataProcessing, Spatial Filtering, and Wavefront Reconstruction,"by Emmett N. Leith et al., discusses a spatial filtering experimentand wavefront reconstruction techniques. The portion dealingwith spatial filtering describes Leith's method for recording a com-

plex function by representing it as a suitable real function of twicethe bandwidth. This method makes complex spatial filtering apractical technique.

Chapter 15, "Some Laser Effects Potentially Useful in OpticalLogic Functions," by Charles J. Koester and C. Hermas Swope,describes some interesting properties of Nd glass-fiber lasers whichmay be useful for optical data processing.

Space does not permit mention of all of the papers in thisvolume, but the above-mentioned articles represent a nonrandomsampling of the contents.

Each paper contains a large list of references; the index (4 pages)is adequate. The book is recommended to workers in the field ofoptical data processing who are interested in what others in thefield are doing.

HowARD M. SnTuxResearch LaboratoriesEastman Kodak ComacpnyRochester, New York 14650

Propagation of Short Radio WavesEdited by DONALD E. KERR. Dover Publications, Inc., NewYork, 1965. Pp. xvii+728. Price $3.00.

This book is a republication of Volume 13 of the RadiationLaboratory Series originally published at the conclusion of WorldWar II. Like other volumes in the series, it is neither a textbooknor a handbook. Rather, it is a compilation of fundamental theoryand experiment associated with the propagation of short radiowaves between terminal points. The wavelength range treated isfrom 3 m to 1 mm but much of the theoretical material, derivedas it is from the scalar wave equation, is valid outside this region.The identity of many microwave transmission problems with well-known problems and solutions in optics is emphasized in the de-velopment of ray tracing formulas and in discussions of interfer-ence, refraction, and scattering phenomena. The effects of indexof refraction of the atmosphere, particularly its modification toaccount for earth curvature, vertical gradient, and distributionwith respect to temperature and moisture, receive considerableattention. For example, two chapters are devoted to meteorologicalvariables and the marked dependence of transmission phenomenaon them. Generally, a large ratio of wavelength to atmosphericparticle size is assumed so that few if any of the experimentalresults can be extrapolated to the optical region. Nevertheless,the student and experimenter in atmospheric physics and opticswill find much of interest in this volume.

L. L. BLACKMER

Research LaboratoriesEastman Kodak CompanyRochester, N. Y. 14650

Mach Bands: Quantitative Studies on Neural Net-works in the RetinaFLOYD RATLinF. Holden-Day, Inc., San Francisco, California,1965. Pp. 365+xii. Price $13.95.

The Mach phenomenon, which was discovered one hundredyears ago, has come under rather close scrutiny in the past fifteenyears or so. Dr. Floyd Ratliff of the Rockefeller University isgenerally recognized as one of the more distinguished of these in-vestigators and is, therefore, highly qualified to write the firstdetailed account of this important phenomenon and about theextraordinary man who first discovered and studied it, ErnstMach.

The impetus for this belated activity on Mach bands seems tobe due in large measure to a growing awareness that the underlyingcontrast perception mechanism manifests itself more significantly.

April 1966 529

BOOK REVIEWS

in this phenomenon than in any other. Certainly the newly de-veloping concepts of neural networks and the interplay of excita-tion and inhibition, to which major contributions have been madeby Hartline and Ratliff's studies on Limuthis, has given credenceto this view. Dr. Ratliff's penetrating account of these and otherrelevant studies in this book arouses the singular feeling that agiant step forward in our understanding of vision is in the making.

The volume consists of two parts. Part one is entitled: "OnNeural Networks in the Retina and the Problem of Objectivity,"and Part two, "Mach's Papers on the Interdependence of RetinalPoints." In the first chapter of Part one, the author delves intoMach the man, his views on science, and his theory of knowledge.This is a perceptive and entertaining vignette of the life and timeof this great scientist.

In Chapter two he discusses the Mach bands in detail-howthey are generated and what variables affect them-drawingheavily and quite thoroughly on the contributions of others. Animportant part of the book is contained in Chapter three, entitled"Mathematical Models of Neural Networks," in which Ratliffattempts to bring together and evaluate the various functionswhich have been advanced over the years to characterize themechanism of the visual process which transduces the stimulus tothe response. This characterization takes the form of a weightingfunction or spread function. He discusses six of these mathematicalmodels. A concise graphical and analytical representation of eachof them is shown on page 122 of the book. Ratliff then asks thequestion, "Six Models or One," and proceeds to show that allhave the form showving "excitatory influences opposed by sur-rounding inhibitory influences" which is necessary to predict thegross features of the Mach phenomenon. However, he points outthe deficiencies of those which require linearity and the variouslimitations of all of them in describing the more intricate relation-ships between stimulus and response in complex fields. It is clearthat the enlightening analysis that Ratliff goes through in evaluat-ing these six theories is made possible to a large extent by theconsiderable work done on Lintins.

It is somewhat unfortunate, I belive, that the author has seenfit to separate the mathematical treatment of the weighting func-tions in this chapter from the transfer functions and their attend-ant Fourier techniques which he discusses in Chapter four. Thereis a direct relationship between some of the six weighting functionsand the experimentally determined modulation transfer functionsdiscussed in Chapter four. For example, the Fourier transform ofMenzel's transfer function (Fig. 4.6, p. 151) and Lowry andDePalma's transfer function (Fig. 4.9, p. 153) yield Huggins andLicklider's as well as B&kdsy's weighting function. Furthermore,they have the same general meaning. It is difficult for the readerto recognize the parts of these two techniques which are identicaland those which are not; I think it is important to his understand-ing of the mathematical analysis that he be made aware of thisrelationship.

The mathematical treatment throughout the book is handledexcellently, in understandable terms with no sacrifice of rigor. Thederivation of the superposition integral (convolution), for example,which is one of the building blocks in two of the models for tracingthe stimulus function through the neural networks to obtain theresponse function, is skillfully done. Ratliff's discussions on linear-ity and nonlinearity are well presented and very pertinent. Inanother important section of the book the author deals with thedynamic behavior of the integrative action of the retina, tracingthrough the functions of (a) retinal motion, (b) the origin oftransient responses in the retina, (c) on-off responses, and (d)the organization of receptive fields.

The second part of the book is devoted to full translations ofthe Mach papers dealing with his experiments and theories. Thisis interesting and worthwhile reading concerning the origins ofthe phenomenon.

To anyone who reads this book it soon becomes evident that itwas written with great care and precision. The subject matterpresented has been well studied and objectively reported. Ratliff's

book is a valuable contribution to visual science as well as a fittingtribute to Ernst Mflach.

JAMES J. DEPALMA

Research LaboratoriesEastman Kodak CompanyRochester, New York 14650

Light: Physical and Biological ActionH. H. SELIGER and W. D. McELRoy. Academic Press, NewYork and London, 1965. Pp. 370. Price $12.00.

Those who deal in one way or another with the action of lighton different biological systems are more and more beginning torealize that they have much to learn from one another. Conse-quently, there is slowly evolving a discipline called photobiology-a science without any satisfactory textbook. The authors, a physi-cist and a biologist, have set out with this present volume toremedy that situation.

This small book contains only five chapters (and five ap-pendices). In the first two chapters, the authors have tried tosummarize the physical concepts and their practical applicationsthat the student of photobiology requires as background. Thefirst chapter on the measurement and characterization of light isa rather straightforward, albeit necessarily abbreviated, treatmentof that subject. Many biological students make an awful mess oftheir first attempts at radiometry or photometry. This chapterdoes not provide a recipe on how to do it right, but it will at leastget the student started in the right direction and lead him to theright places to find how to do it properly.

The second chapter on the excitation of molecules by light willprove the most formidable for the student whose chemistry andphysics are just ordinary. What comes through, of course, is thatall the processes which are initiated by light are quantum phe-nomena and must be treated as such. What would be helpful to usstudents is a little more attention to seeing that all the conceptsand symbols are clearly defined at the time they are introduced.

Chapters 3 and 4 are short and are devoted, respectively, tochemiluminescence and enzyme-catalyzed chemiluminescence(bioluminescence). The chapter on bioluminescence concludeswith a fascinating series of speculations on the evolutionary as-pects of bioluminescence. This section is typical of what is right(as well as what is wrong) with the book as a whole. Unlike almostanyone else, the authors have thought long and hard about (andmade contributions to) a great many of the variety of differentsubjects which make up the contents of the book. Since any oneof these itself can be (inexhaustively) treated by a volume twicethis size, they are immediately confronted with an overwhelmingtask of selection. Rather than ruthlessly pruning down to what ismost important and trying to get this through in a clear textbookstyle, they have elected to do something quite different. Theyhave written about what is of interest to them. Having made -thisdecision, they then go on to make another-they do not confinethemselves to discussing what is well established but offer ap-parently new and original ideas on a large variety of differenttopics.

Thus, in a discussion of less than forty pages on the whole sub-ject of vision, it seems quite ludicrous to devote five pages toHaidinger's brushes which, like all such entoptic effects, are trivialin what they have to tell us about how people (or animals) see.But Haidinger's brushes are intriguing, and the authors are notcontent just to describe the familiar facts. On the contrary, almosthalf of their discussion is devoted to what, insofar as I have beenable to determine, is a completely new and original explanation forthe observation of Shurcliff that circularly (as well as linearly)polarized light produces the brushes.

And so it goes throughout the book. The result is neither a goodgeneralized introduction to the present status of photobiology forthe student nor a good up-to-date reference for the research worker

530 Vol. 56

AN NOUN CEM EN TS

(the aims of the book stated on the jacket). Nonetheless, it is aninteresting, unusual, even fascinating book.

The last chapter (better than 40% of the whole) is on the bio-logical action of light. It includes discussions on the organizationof light-receptor systems, the control of metabolism by light,phototropism and phototaxis, direct stimulation, deleterious ef-fects, photoreactivation, and biological optical asymmetry, inaddition to the discussions on photosynthesis and vision. It ishere that the "specialist" spots the difficulty associated with tryingto make important contributions to all phases of photobiology atalmost one and the same time. To cite a few examples almost atrandom from things I know about: a rather antiquated discussionof the ERG; a much too provincial discussion of the direct effectof light on the isolated iris; the idea (p. 278) that ". . . in thehuman . . . pupil diameter varies inversely with the square rootof the light intensity," (IS09 is a much more reasonable descrip-tion, but even that greatly oversimplifies). On p. 298 the 1° rod-free area is given as a distance on the retina of about 0.13 mm inradius, but on p. 281 in a footnote, we were told that ". . . I'arc corresponds to a distance on the retina of approximately4.85 pu."

But all of this is being picayune. This is an extremely stimulatingbook. What it has to say is that fundamental contributions tovision, or to photosynthesis, or to bioluminescence, or to photo-tropism, or to photoreactivation can come from those who movefreely about in any one of these fields as distinct from those whoknow everything there is to know about the eye and vision (say)and nothing about anything else.

MATHEw ALPERNUniversity of MichiiganAnn Arbor, Michigan

Japanese Edition of Shurcliff's Polarized Light

Some of our Japanese readers may like to know that W. A.Shurcliff's Polarized Light: Production and Use, published in 1962by the Harvard University Press, and reviewed by R. C. Plumbin J. Opt. Soc. Am. 53, 881 (1963), has been translated intoJapanese by Dr. Takeo Fukutomi and, in September 1965, waspublished by the Japanese scientific publisher Kyoritsu Shuppan.Dr. Fukutomi is at the Division of Research and Development,San'yo Electric Works, Tokiwa, Kamitsuchii, Gifu, Japan.

Announcements

Bausch & Lomb Dedicates Grating Laboratoryto Richardson

Bausch & Lomb has dedicated its multi-million-dollar gratingand scale laboratory to David Richardson, Fellow and past-Director of the' Optical Society. In a ceremony attended by theB&L board of directors including Dean George Harrison, WilliamW. McQuilkin, president of B &L, unveiled a bronze plaque bearingthe inscription:

THE

DAVID RICHARDSONGRATING LABORATORY

DEDICATED FEBRUARY 15, 1966IN RECOGNITION OF HIS CONTRIBUTIONS

TO THE SCIENCE AND TECHNOLOGYOF DIFFRACTION GRATINGS

"In honoring David Richardson, Bausch & Lomb pays tributeto his devotion to the advancement of scientific knowledge whichserves as an inspiration to us all," McQuilkin said.

Richardson is an internationally recognized authority on diffrac-tion gratings and has lectured extensively both in the UnitedStates and overseas. He joined B &L in 1947 as physicist in charge

of research and development of gratings and other precision-ruledproducts as well as spectroscopic instruments. He received hisChemical Engineering degree from the University of Cincinnati in1930, studied medicine at Boston University for two years, andreceived his Masters Degree in Applied Physics in 1937 from MIT.In addition to the Optical Society, he is a member of the AmericanChemical Society, the American Association for the Advancementof Science, the Society for Applied Spectroscopy, and the CoblentzSociety.

In 1948, Bausch & Lomb reached the conclusion that gratingswere far superior to prisms for spectroscopic analysis. "Mr.Richardson was involved in that decision," McQuilkin pointedout, "and has devoted his energies to advancement of the state ofthe grating art ever since."

Diffraction gratings have been known since 1785, but it wasnot until 1882 that Henry A. Rowland, of Johns Hopkins Uni-versity, developed the first workable ruling engine for their pro-duction. Albert A. Michelson, of the University of Chicago (thefirst American scientist to win the Nobel Prize) built two enginesthere, but World War II disrupted the work, and the engineslanguished. Bausch & Lomb brought one of Michelson's enginesto Rochester in 1948 and, under Mr. Richardson's direction,ruled its first large commercial grating in 1950 for the NationalResearch Council in Ottawa, a grating which is still in use. Asecond engine has been completed since then and a third is nowunder construction. The company recently ruled its 1600th mastergrating.

The actual ruling of a master grating is a long, slow process re-quiring great skill and patience. Some gratings, depending on theirsize, take three or four days to rule, others as long as five weeks.It takes from one to ten days to "set-up" the engines for theactual ruling. When operating, a machine runs 24 hours a day.

April 1966 53i

CONTENTS

Almost unbelievable controls govern the ruling process. The en-gines are located in "cells" ten feet underground, resting onvibration-isolated, concrete blocks. A cement wall, eight feet inthickness, provides extra protection. In addition, the most rigidtemperature control must be maintained continuously while agrating is being ruled. Special inner walls of aluminum and airlocks are just two of the measures used to hold temperature con-stant to better than one-hundredth of a degree Centigrade. Noone can even approach the "cells," because body temperatureswill cause such a fluctuation as to render the ruling worthless.The B&L ruling engines thus have been characterized as "theengines which hate people."

Ruling master gratings, therefore, is a meticulous task. UnderMr. Richardson's guidance, a process of replicating (duplicating)has been developed. Basically, replicating can be compared tomaking a phonograph record. Another optical blank is attachedto the ruled surface of the master by means of special adhesives.Pressure is applied for a period of time, then the two are separ-ated; the extra blank carries away the adhesive, in which a replicaof the ruled surface has been formed. This process has not onlygreatly reduced the cost of gratings, but has helped speed the ex-pansion of spectroscopic analytical instruments to their presentpre-eminence in the scientific world, by making them moreavailable.

Bausch & Lomb invested over a million dollars in creating itsruling laboratory. This investment has since been doubled withthe development of a scale engine which applies the principles ofruling gratings to the production of scales and grids having un-equalled precision.

Intensive Course in Industrial Spectrography

Boston College will give its annual special intensive course inmodern industrial spectrography 27 June through 8 July 1966.

Requests for information should be addressed to Rev. James J.Devlin, S. J., Director, Department of Physics, Boston College,Chestnut Hill, Massachusetts 02167.

Dr. Sanderson Appointed Research andEducation Officer

President-Elect John A. Sanderson has accepted the full-timeposition of officer in charge of the Research and Education Pro-gram. Dr. Sanderson, who retired as Acting Associate Director ofResearch and Planning at the U. S. Naval Research Laboratory asof 1 January 1966, has established his new office in the ExecutiveHeadquarters of the Optical Society at 1155 16th Street N. W.,Washington, D. C. 20036.

Dr. Sanderson, who had been with NRL since 1935, receivedboth bachelor's and master's degrees from the University ofMississippi and the Ph.D. degree from The Johns Hopkins Uni-versity. He taught at Johns Hopkins in the physics departmentfrom 1930 to 1935.

His earliest research at NRL in Washington was concerned withphotoelastic investigation of stresses in ship structures and laterhe employed infrared spectroscopy on problems concerned withthe molecular structure of aviation fuels. He received the U. S.Navy Meritorious Civilian Service Award for his research on low-reflectance coatings for optical elements, investigations whichstarted in 1940.

During World War II, Dr. Sanderson was concerned chieflywith military applications for radiation in the infrared spectrum,including near-infrared image-converter tubes, detection of tar-gets, and related problems. He participated in optical experimentsat the Crossroads atomic-bomb tests at Bikini in 1946 along withother members of the NRL Optics Division. In 1949, he becamethe second Superintendent of the NRL Optics Division, succeeding

E. 0. Hulburt, who became the first Director of Research of theLaboratory.

He is a member of the Philosophical Society of Washington, ofthe Governing Board of the American Institute of Physics, anda Fellow of the Washington Academy of Sciences, of the OpticalSociety of America, and of the American Physical Society.

Contents

Contents: Revue d'Optique, September 1965

Monochromateur pour la region 400 a 3000 A-M. Pouey andJ. Romand

Contribution a une theorie electromagnetique de la diffrac-tion. Reseau & profil sinusoidal. Diffusion superficielle(suite)-J. Pavageau

October 1965

Les sensibilit6s photopiques dans la region du champ visuelsymetrique a la tache de Mariotte-G. Verriest and P.Verhuyten

Contribution a l'etude des constantes optiques de liquidesabsorbants dans l'infrarouge (a suivre)-M. Cameo

Mesure au microscope electronique de l'intensite transmisepar des cristaux d' or dont 1' axe III est parallele au faisceaud'electrons-Croce, Gandais, Gentric, and Sauvin

Vol. 56532

TECHNICAL CALENDAR

Personalia

Roy H. Garstang

Professor Roy H. Garstang, an astrophysicist on the faculty ofthe University of Colorado Department of Physics and Astro-physics and a fellow of the Joint Institute for Laboratory Astro-physics (JILA), has been elected chairman of the Institute effec-tive 1 January 1966.

Garstang, a member of the Optical Society and a Journal author,came to Colorado last year from the Mill Hill Observatory of theUniversity of London, where he was assistant director. He haswritten many papers on atomic spectroscopy as applied to astro-nomical studies. Garstang's work has been of great importance inthe determination of cosmic abundance of the elements, the sourceof much of our knowledge of the probable origin of the universe.

Garstang also serves as chairman of the astrophysics committeeof the Department of Physics and Astrophysics of the University,in which astronomers in JILA and in the High Altitude Observa-tory of the National Center for Atmospheric Research (NCAR)are now brought together to offer a single doctorate curriculum inastrophysics.

As chairman of JILA, Garstang will head a faculty of 24, ofwhom 10 are distinguished visiting fellows who come on one-yearappointments from around the world. In addition, 11 post-doctoralresearch associates and 33 graduate students are working at JILAon a variety of theoretical and experimental studies in the astro-physical sciences.

Necrology

Vincent J. Ellerbrock

Professor Ellerbrock was born in Delphos, Ohio, 13 March 1918.He received his B.Sc. degree in 1940 from The Ohio State Uni-versity, his M.Sc. degree in 1941, and his Ph.D. in 1947 from thesame University. He was a Research Fellow in the DartmouthEye Institute at Dartmouth College, Hanover, New Hampshire,where he worked on aniseikonia and subnormal-vision aids from1944-46. His Ph.D. dissertation was based on a study of fusionalmovements of the two eyes. This continued as the central themeof his research program. In 1947 he was made Assistant Professorof Physiological Optics in the School of Optometry at The OhioState University. In 1951 he was promoted to the rank of AssociateProfessor, and to the rank of Professor in 1956.

As chairman of the Building and Equipment Committee, heplayed a major role in working out the detailed plans for theOptometry Building which was occupied in 1951, and the additionto the Optometry Building which was occupied in 1961; at thetime of his death he was active in formulating plans for furtherexpansion of the building and equipment facilities. He was Direc-tor of the Optometry Clinic and organized the clinical programwith its special clinics in the fields of aniseikonia, subnormal vision,contact lenses, and orthoptics. He published forty-five scientificpapers. In 1949 he published a book, Light, Vision and Lenses, incollaboration with Dr. G. W. Knox. He also published A Manualfor the Optometry Clinics. At the time of his death he had completedthe manuscripts for two additional books, Subnormal Vision andThe Optics of Contact Lenses. He introduced and developed a pro-gram of postgraduate courses for practicing optometrists. Hehelped develop the Museum which features the history of eyewearand visual testing devices from the earliest times to the present.His contributions have made the School of Optometry at TheOhio State University the pride of .the profession.

Dr. Ellerbrock served as a member of the Council of the In-stitute for Research in Vision and played a major role in developingthe Visual Demonstration Center. He was a member of the OpticalSociety of America, American Optometric Association, Ohio StateOptometric Association, and the American Academy of Optome-try. He was a member of the Military Liaison Committee of theAssociation of Schools and Colleges of Optometry, and a memberof the Research Advisory Committee of the American Foundationfor the Blind. He was a member of the Executive Council and theEditorial Council of the American Academy of Optometry. Heintroduced the program of postgraduate courses for the Academyof Optometry and for ten years was chairman of the Committeeon Instruction. This yearly program of postgraduate courses of-fered during the week prior to the annual meeting of the AmericanAcademy of Optometry was his finest contribution to the profes-sion. He was a member of Sigma Xi and was an honorary memberof two of the optometric professional fraternities, Epsilon PsiEpsilon and Omega Epsilon Phi.

Technical Calendar

1966

May

2-7 International Commission for Optics, Paris.9-13 Society of Photographic Scientists and Engineers,

San Francisco.

June

6-8 Symposium on Temporal-Essects, Center for VisualScience, University of Rochester, Rochester,New York.

13-17 Society for Applied Spectroscopy, Chicago, Illinois.20-24 International Conference on Crystal Growth, Bos-

ton, Massachusetts.22-24 Conference on Coherence and Quantum Optics, Uni-

versity of Rochester, Rochester, New York.

October

7-8 Symposium on Physics of New Material, NewYork State APS, Rensselaer Polytechnic Insti-tute, Troy, New York.

19-21 Optical Society of America, Jack Tar Hotel, SanFrancisco, California.

20-29 Society of Photographic Scientists and Engineers,Washington, D. C.

1967

March Optical Society of America, Columbus, Ohio.

June

19-23 International Spectroscopy Colloquium, Ottawa,Canada.

22-28 International Commission on Illumination, Wash-ington, D. C.

533April 1966

LOCAL SECTION CALENDAR

October

11-13 Optical Society of America, Sheraton-CadillacHotel, Detroit, Michigan.

1968

March Optical Society of America, Washington, D. C.

October

8-11 Optical Society of America, Pittsburgh HiltonHotel, Pittsburgh, Pennsylvania.

Local Section Calendar

1966A pril

5 Rochester Section, Dr. A. Keith Pierce, Kitt Peak NationalObservatory, "150-in. Telescope."

19 Rochester Section, Dr. K. Sayanagi, University of Roches-ter, "Studies of Optical Transfer Functions."

May

3 Rochester Section, Beaumont New Hall, Eastman HouseMuseum, "Sir John S. W. Herschel and Photography."

OSA Technical Group on Lens Design

The Lens Design Discussion Group met on Wednesday, 6October, at the Philadelphia meeting of the Society, with aboutfifty in attendance. The great majority stayed for the full meetingand had an interesting and spontaneous discussion of a number ofimportant areas of current interest to lens designers. A number ofmembers submitted written comments following the meeting,indicating a high level of interest in the session and a desire forsimilar activities at future meetings.

The initial discussions were to some degree an extension of thequestion period of the contributed-paper session on GeometricalOptics, held earlier that day. This also provided an opportunityfor some clarification of the significance of the material that hadbeen presented. The discussion then moved to several generalareas of interest. The subject of standardization of optical glasseshas received considerable attention by industrial and Governmentcommittees. Many experienced workers feel that modern optical-design techniques permit the designer a much wider latitude inglass choice than in the past. Agreement among lens designers touse a limited number from the very wide gamut of presentlyavailable optical glasses would permit glass manufacturers to con-centrate on fewer types of glass. This could simplify the supplyproblem so that there might well be an improvement in both thedelivery time and quality of the glasses actually used. It is hopedthat at the next meeting of this technical group it will be possibleto have reports from some individuals who have been involvedin more detailed studies of the problem.

Out of this discussion of glass there developed a discussion of

the problem of the secondary spectrum and its correction, par-ticularly the use of glasses whose partial dispersions differ fromthose for "normal" glasses. If the partial dispersion or P numberis plotted against the dispersion or V number of available opticalglasses, the great majority of glasses lie along a smooth curve. Thediscussion centered on the requirements for accurate measure-ments of data for the extraordinary glasses which lie off this curve,on the importance of the designer being able to anticipate theproperties of the actual glass which will be used to make his lens,and on the general problem of the use of such glasses in the correc-tion of secondary spectrum or residual color. It was emphasizedthat modern computer techniques give the designer great flexi-bility in replacing one glass in a design with a glass with similarcharacteristics. The reoptimization of the design can be accom-plished quite rapidly; since rebalancing a lens with changed glassis practically the same as designing a new lens; with the old tech-niques it was a major task, comparable in some cases to carryingout a complete new design.

This moved the discussion to the area of computer techniquesgenerally. Computer programs available for optical design varyenormously in scope and complexity. For the individual designerentering the field or for a designer solving certain classes of ele-mentary problems, standard computer programs are availablewhich can be used with little or no reprogramming effort. It isclear, however, that for more advanced problems the programs inuse are diverse in scope and concept. These more complex pro-grams, which are often the result of a group effort, are not readilyinterchangeable and are not often transferrable for use by de-signers in some other group. Most programs in this categoryare in a state of more or less continuous development, being ex-panded in scope or in their ability to handle additional or special-ized problems.

There was some discussion of "what is the best program" withreference to advanced programs capable of automatic design. Thediscussion indicated that there is no simple answer and that mostof the advanced programs are so closely allied with a particulardesign effort that any competitive test would be a test not just ofthe program but of the designer's skill as well. The discussionemphasized again that the term automatic lens design is unfor-tunate, in that it implies true automation which would displacelens designers or reduce the skill and judgment needed for lensdesign. It is probably more true to say that the modern automaticdesign program increases the scope of the lens designer to such adegree that he is capable of handling problems of considerablymore complexity than in the past. The demands on the skill andexperience of the designer have probably grown rather than di-minished by this development.

There was some discussion of interchange of optical-design pro-grams between various users. Some sources were identified whereinformation on optical programs is available. It was also recognizedthat many programs are developed on a proprietary basis and,therefore, are not available for general distribution.

The discussion concluded with suggestions for topics for a sub-sequent meeting. Those members who expressed interest at themeeting will receive a notice outlining the proposed topics fordiscussion, prior to the Spring meeting of the Society in Washing-ton. Other members interested in lens-design discussion and thelens-design technical group are requested to send their names tothe chairman so that they may be included in any mailings thatmay be made. Comments and suggestions for future directionsthat might be taken by the technical group will be very welcome.

F. Dow SMITH, Chairman

ITEKC Corp.Lexington, Mass. 02173

534 Vol. 56

JOURNAL OF THE OPTICAL SOCIETY OF AMERICA

Program of the Fiftieth Anniversary Meeting of the Optical Society of America

THE SHOREHAM HOTEL, WASHINGTON, D. C. 15, 16, 17, AND 18 MARCH 1966

TUESDAY, 15 MARCH 1966 REGENCY BALLROOM AT 10:00 A.M.

VAN ZANDT WILLIAMS, Chairman

Opening Remarks by President

Invited Papers

TuAl. Lasers. CHARLES H. TOWNES, Office of the Provost, Massachusetts Institute of Technol-ogy, Cambridge, Massachusetts 02139.-The status of laser developments and their present appli-cations to scientific and technological problems, particularly those traditionally connected withoptics, will be briefly reviewed. In addition, the background from which lasers have developed,their significance to the field of optics, and future prospects for lasers as part of modern opticswill be discussed. (45 min.)

TuA2. The Physics of Laser Oscillators. WILLIS E. LAMB, JR., Yale University, New Haven,Connecticut 06520.-(45 min.)

TUESDAY, 15 MARCH 1966 REGENCY BALLROOM AT 2:00 P.M.

S. Q. DUNTLEY, Chairman

Invited Papers

TuBl. Progress in Physiological Optics. ROBERT M. BOYNTON, Center for Visual Science,University of Rochester, Rochester, New York 14627.-In the beginning, optics and vision wereinseparable: little was known about the physical basis of light, and the eye was the only avail-able photodetector. Light can now be given a completely physical treatment, while an impressivearray of light-sensitive devices challenge the eye's performance, exceeding it in some instances.It would however, be a mistake to divorce visual science from optics, because (a) the eye isstill the best all-round photodetector-even excluding the interpretive functions of the highervisual centers-so that Nature may yet be able to teach old optical designers some new tricks;(b) the eye is the final detector in many optical systems, so that its characteristics need to befully understood as they interact with man-made optical devices; and (c) progress in physio-logical optics (visual science) will in the future depend increasingly upon the infusion of thediscipline with physically, as well as biologically and psychologically oriented experimenters andtheoreticians. With these thoughts as background some of the performance characteristics ofthe eye will be reviewed, recent attempts to put these data into a form useful to the engineerwill be described and evaluated, and the need for more workers having keen physical insight willbe justified. (45 min.)

TuB2. Frontiers in Spectroscopy. BENGT EDLEN, Physics Department, University of Lund,Lund, Sweden.-The present status of accomplishment, the remaining problems, and the trendsin the present activity in the field of optical spectroscopy are reviewed in the historical perspec-tive. The discussion covers techniques of production, recording and evaluation of spectra, and theresults regarding, especially, the term structure of atoms in various stages of ionization. Appli-cations of the results to the interpretation of astronomical spectra, including in particular thevacuum ultraviolet solar spectrum, are also discussed, and some of the laboratory work that ismost urgently needed for this and other purposes is pointed out. (45 min.)

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VOLUME 56, NUMBER 4 APRIL 1966

536 FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA

TuB3. Optical Highlights of Twenty Years of Space Research. RICHARD TOusEy, E. 0.Hulbert Center for Space Research,' U. S. Naval Research Laboratory, Washington, D. C.20390.-Some of the most significant and ingenious research involving optics, carried out fromspace vehicles and selected from the various disciplines of space research, will be reviewed.The state of the art of optical instrumentation has continuously been strained, and this has ledto the development of many special techniques and devices. As results from space experimentationare received, new scientific horizons are appearing, and act, in turn, to stimulate research inground-based laboratories. A glimpse into the future shows possibilities without end for far-reaching space research through optics. (45 min.)* Work sponsored jointly by the Office of Naval Research and the National Science Foundation.

WEDNESDAY, 16 MARCH 1966 REGENCY BALLROOM AT 9:00 A.M.

EMIL WOLF, Chairmian

Invited Papers

WAL. On Some Interesting Models in Classical and Quantum Optics. EDWARD L. O'NEILL,Department of Physics, Boston University, 700 Commonwealth Avenue, Boston, Massachusetts02215.-Due to recent renewed interest in problems concerned with the fluctuations of the lightitself, the meaning of the term "statistical optics" has been restored to the sense originallyimplied in the work of Planck, Einstein, and Von Laue. In the meantime, due largely to theinfluence of information and communication theory, the term has often been used to describerandom scenes or an emerging wavefront or the granular fluctuations in the photographicreceptor. In both senses, the advantages of adopting an "eigenvalue" point of view when dealingwith either image forming or analyzing optical instruments are pointed out. Moreover, thestrictly statistical aspect of wave propagation is demonstrated from first principles. Coupledwith the indistinguishability principle, the effect of playing "quantum dice" on particle correlationexperiments is discussed. Finally, the application of probability theory to several photographicproblems is presented. (30 min.)

WA2. Photon Correlations and Higher Order Coherence Functions. LEONARD MANDEL,Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627.-The manner in which coherence properties of an optical field manifest themselves in the fluctua-tions registered by one or more illuminated photodetectors will be discussed. The fluctuationscan be described either in classical terms, as beats between different Fourier components, or inquantum mechanical terms, as a Bose-Einstein bunching of the photons. The fluctuations canbe measured by correlation experiments, some examples of which will be given. A 3-channeldelayed coincidence experiment will be briefly described and the kind of information about 6thorder coherence functions obtainable from it will be indicated. (30 min.)

WEDNESDAY, 16 MARCH 1966 EMPIRE ROOM AT 10:15 A.M.

BRIAN J. THOMPSON, Chairmnan

Contributed Papers

Holography I

WB11. Holographic Recording on Three-DimensionalMedia. E. N. LEITH, A. KOZMA, J. UPATNIEKS, N. MASSEY,AND J. MARKS, Institute of Science and Technology, TheUniversity of Michigan, Ann Arbor, Michigan 48107.-Whenthe fringe patterns recorded on a hologram have a spacingcomparable to the thickness of the recording medium, themedium must be treated as a volume rather than a surface.The optical properties of such holograms are analyzed. Threecases arise: low-angle reference beam, where the recordedfringes are coarse compared to the medium thickness; high-angle reference beam, where the fringes are fine; and finally,very high-angle reference beam, in which the reference beamis introduced from the back side of the recording medium,

and in which the recorded fringes are nearly normal to thereadout beam. Each case has its special properties, and thetransition between these cases depends upon the thickness ofthe medium. Experimental results are given, showing thesensitivity of the reconstructed image to the wavelength andincidence angle of the readout beam. Both the case of uni-form fringe contrast throughout the medium and the case ofexponential attenuation with depth are considered. An ani-mated hologram has been produced in which successiveframes are superimposed on a single hologram by reorientingthe hologram between exposures. The images are read outin succession using Bragg angle effects by rotating the holo-gram in the illuminating beam. (13 min.)

FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA 537

WB12. (Abstract withdrawn.)

WB13. Characteristics of Thermoplastic XerographicHolograms. JOHN C. URBACH AND REINHARD W. MEIER,Xerox Corporation, Post Office Box 1540, Rochester, NewYork 14603.-Successful reconstructions from phase holo-grams recorded on thermoplastic xerographic materials arereported. The thermoplastic-overcoated photoconductor con-figuration has characteristics that make it particularly suit-able for holographic use. Holograms of this type have beenrecorded with carrier frequencies as high as 1000 cycles/mm.The bandwidth limitations and noise characteristics of ther-moplastic xerography have been examined in the holographiccontext, and it has been found that under certain conditionsthe grainless nature of thermoplastic holograms can lead toa very low level of scattered background light in the recon-structed images. (13 min.)

WB14. Three New Advances in Optical Holography.*GEORGE W. STROKE, The University of Michigan, Ann Arbor,Michigan 48104.-Three new advances yet to be publishedhave now been made in work by the author and his studentsD. Brumm, A. Funkhouser, A. Labeyrie, and R. C. Restrick,in part in collaboration with Prof. D. Gabor.' 1. Holographicinterferometry (based on the Gabor and Stroke et al. prin-ciple2 of successively adding intensities in double-exposed andmultiple-exposed single holograms) a. Double-exposed singleholograms may be used for two-beam interferometry'; b.Two separately exposed holograms permit to first "code" analready 'invisible' phase object by recording one hologram(even through a random diffuser), and next to "decode" theimage with the "decoding" key carried in a second holo-gram.4 2. Absence of any 'twin-image' separation or of anyphase-recording problems in the original Gabor "in-line"holography arrangement has now been demonstrated by us,5

in contrast with a previously stated widely accepted belief'(e.g., statements attributing these properties necessarily to"off-axis" arrangements, now found to be perfectly equivalentand not different). 3. Multi-color images have now beenobtained in ordinary white light from a new type of "reflec-tion volume hologram," in a collaborative effort by L. H.Lin, K. S. Pennington, G. W. Stroke, and A. Labeyrie,7extending the white-light single-color holography method ofStroke and Labeyrie,' and based on a general suggestion byDenisyuk.' (13 min.)

* For a general background, see, e.g., Ref. 1.'G. W. Stroke, An Introduction to Coherent Optics and Holography(Academic Press Inc., New York and London, 1966) (Library of CongressCatalog Card Number: 65-28633).2 D. Gabor and G. W. Stroke, R. Restrick, A. Funkhouser, and D. Brumm,Phys. Letters 18, 116 (1965); see also G. W. Stroke and D. G. Falconer.Phys. Letters 1I, 238 (1965).3 G. W. Stroke and A. Labeyrie, Appl. Phys. Letters (Jan.-Feb. 1966).4 G. W. Stroke and A. Labeyrie, Phys. Letters 20 (Jan.-Feb. 1966).b G. W. Stroke, D. Brumm, A. Funkhouser, A. Labeyrie, and R. Restrick,

Brit. J. Appl. Phys. (submitted 12 Nov. 1965) in print.6 E. N. Leith and J. Upatnieks, Phys. Today 18, 26 (1965).'L. H. Lin, K. S. Pennington, G. W. Stroke, and A. Labeyrie, BellSyst. Tech. J. (Apr. 1966).8 G. W. Stroke and A. Labeyrie, Phys. Leters 20, 367-369 (1966).9 Yu. N. Denisyuk, Soviet Phys. "Doklady" 7, 543 (1962).

WB15. Binary Image Holograms. A. W. LOHMANN ANDD. P. PARIS, IBM San Jose Research Laboratory, San Jose,California 95114.-An image hologram differs from the morecommon Fresnel and Fraunhofer holograms in the distanceof the recording plate from the object (or an image thereof).This distance is zero for an image hologram. Hence, such ahologram is actually the same as an ordinary interferogram,in which the deformations of the interference fringes repre-sent the shape of the wavefront behind the object. Instead ofrecording the image hologram by means of an interferometer(such as a Mach-Zehnder), we have drawn the hologram ona large scale and photographically reduced them. In contrastto ordinary holograms, ours contain only black and fully trans-

parent portions. In other words, the transmittance is binary,which facilitates the production. The quality of an image re-constructed from a binary hologram is the same as if ob-tained from an ordinary grey-tone hologram of comparabledimensions. Our synthetic way of producing an image holo-gram has the advantage that the object does not have toexist physically. The theory, some experiments, and possibleapplications will be discussed. (13 min.)

WB16. The Experimental Production of Synthetic Holo-grams. M. PARKER GIVENS AND WILLIAM J. SIEMENS-WAP-NIARSKI, Institute of Optics, University of Rochester, Roch-ester, New York 14627.-By multiple exposure of a photo-graphic plate to a pattern of Newton's rings the authors haveproduced holograms which reconstruct a predetermined pat-tern such as the letter E. This method of synthesis makesthe interpretation of holograms as a collection of zone platesapparent. Three-dimensional reconstructions have also beenachieved from these synthetic holograms. (15 min.)

WB17. Contour Generation by Wavefront Reconstruc-tion. B. P. HILDEBRAND AND K. A. HAINES, Institute ofScience and Technology, The University of Michigan, Op-tics Group, IST Bldg., N. Campus, Ann Arbor, Michigan48107.-The wavefront reconstruction technique, first pro-posed by Gabor and later refined by E. N. Leith and J.Upatnieks, provides a method for the storage of three-dimensional information on a two-dimensional storage me-dium. The information so recorded may be retrieved byilluminating the storage surface with a coherent beam oflight, whereupon a complete three-dimensional image of therecorded scene or object is reconstructed. A possible futureapplication for this recording process is in the three-dimen-sional mapping of terrain. Another application might be thecross section tracing of models for certain manufacturedproducts. In such an application, the addition of constantaltitude contour lines would be desirable. The generation ofsuch contours is the subject of this paper. The analysis per-formed in the paper shows that there are two possible meth-ods for obtaining a contoured reconstruction. The firstmethod requires that the object be illuminated by two col-limated beams separated by a small angle, 20, with the holo-gram plate placed at 90' to the illuminating beams. In thiscase the depth separation of the adjacent contours is X/2sin 0. The second method requires two frequencies in theilluminating beam. The depth separation between contours is

'2/AX, where AX is the wavelength separation of the twofrequencies. Both of these methods have certain advantagesand disadvantages which are fully explored in the paper.Experimental results illustrating both methods will be shown.(13 min.)

WB18. Bias Level Reduction of Incoherent Holograms.ADAM KOZMA AND NORMAN MASSEY, Radar and Optics Lab-oratory, Institute of Science and Technology, The Universityof Michigan, Ann Arbor, Michigan 48107.-The known tech-niques for making incoherent holograms succeed for anobject containing several points; however, they fail in prac-tice for an object with a great many discrete points or fora complicated object with a continuous intensity distribution.This results because the incoherent superposition of manyrandomly spaced intensity patterns produces a large biaslevel which masks the spatial intensity modulations requiredto reconstruct the object in the film grain noise. This paperdescribes a technique for eliminating the bias. By introduc-ing a time modulation of the light in one path of the inter-ferometer, the spatially modulated part of the hologramintensity pattern is also modulated at the time frequencywhile the bias part is unmodulated. The bias term can thenbe eliminated by performing a point by point time correlation

538 FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA

over the hologram plane. This technique is similar to thatproposed by Ryle for radio astronomy and by Mertz forspectral line discrimination. The implementation of this tech-nique will be discussed and two possible methods of perform-

WEDNESDAY, 16 MARCH 1966

ing the time correlation, one using a photocell and a narrowband filter and one using an electro-optical correlator basedon a specially modified image orthicon, will be described.(13 min.)

PALLADIAN ROOM AT 10:15 A.M.

LEO M. HURVICH, Chairman

Contributed Papers

Vision I

WC11. Visual Acuity Measurements during ProlongedWeightlessness. SEIBERT Q. DUNTLEY, ROSWELL W. Aus-TIN, JOHN H. TAYLOR, JAMES L. HARRIS, AND W. HADLEYRICHARDSON, Visibility Laboratory, Scripps Institution ofOceanography, University of California, San Diego, Cali-fornia 92152.-Tests of visual acuity were performed in con-nection with the long-duration earth orbital flights of Gemini5 and 7. A small testing device was used by the crew mem-bers on several occasions before the flights, daily during themissions, and again soon after they had landed. Each astro-naut was required to record the orientation of tiny rectanglesof various sizes presented singly and sequentially at the centerof a 300 adapting field having a luminance of approximately100 ft-L. No change in the visual acuity of any of the astro-nauts was detected. (13 min.)

WC12. Super-Summation of Photopic Adaptive EffectRevealed by Mixing Conditioning Fields. ROBERT M.BOYNTON, S. R. DAS, AND JEAN GARDINER, Center for VisualScience, University of Rochester, Rochester, New York14627.-The intensities of conditioning fields that are neces-sary to reduce the visibility of a previously suprathreshold testflash to an increment threshold are determined for each oftwo conditioning fields of different color. Normalizing eachof these intensities to 1.0, subthreshold amounts (e.g., 0.8,0.6, etc.) of one field component are pre-set by the experi-menter; the subject then adjusts the other component untilthreshold is again attained. In an eye whose adaptive state iscontrolled by the action of light upon only one spectral classof photopic mechanism, the normalized intensity sum mustalways equal 1.0. We find however, that this sum is consist-ently less than 1.0, indicating a super-summative interactionof adaptive effect between two or more different mechanisms.This conclusion is contrary to that reached by Alpern andRushton,' who felt that adaptation was entirely specific withintypes of photopic mechanisms-for test and conditioning fieldsizes, durations, and wavelengths identical to ours. The un-usual finding of super-summation has not appeared in pre-vious mixture experiments of Guth2 (who used the thresholdof the mixture field itself as a response criterion) or Boyn-ton, Ikeda, and Stiles3 (who mixed test flashes,. rather thanconditioning fields). (13 min.)

' M. Alpern and W. A. H. Rushton, J. Physiol. 176, 473 (1965).2S. Guth, J. Opt. Soc. Am. 56, 718 (1965).'R. M. Boynton, M. Ikeda, and W. S. Stiles, Vision Res. 4, 87 (1964).

WC13. The Monochromatically Evoked Occipitogram inMan. T. SHIPLEY, R. WAYNE JONES, AND AMELIA FRY,Bascom Palmer Eye Institute, University of Miami School ofMedicine, 1638 N.W. 10th Avenue, Miami, Florida 33136.-By using a xenon lamp, a Maxwellian-view optical system,a special procedure to control the level of adaptation, andan 110 stimulus field, we have reported previously that the

waveform of the monochromatically evoked occipitogram incolor normal observers can be shown, to some extent, to bedependent upon the Fresnel number (frequencyX1012) of thestimulus light. In that early work, however, only four dif-ferent frequencies were used and intensities were only over-lapped not matched. We report now on the preliminary re-sults (N=2) obtained with 25 frequencies at matched intensi-ties covering the visible spectrum from 428F (700nm) to750F (400 nm). By our methods, three different waveformsmay be discerned. (13 min.)

WC14. Effect of Exposure Duration on Contrast Sensi-tivity for Square-Wave Gratings. JAcOB NACHMIAS, De-partment of Psychology, University of Pennsylvania, Phila-delphia, Pennsylvania 19104.-Contrast sensitivity for square-wave gratings of spatial frequencies between 0.44 and 33.2cycles/deg was determined for exposure durations between11 and 500 msec. The space-average luminance of the targetswas kept constant at 10 mL, regardless of contrast, and equalto that of the pre- and post-exposure fields, which containeda cross-hair reticle to help maintain accommodation and fixa-tion. At the longest exposure duration (500 msec) the con-trast sensitivity function exhibited both the high- and thelow-frequency declines described by previous investigators.At the briefest exposure duration tested (11 msec.), the low-frequency decline in contrast sensitivity was virtually absent.Log contrast sensitivity improves with increasing exposureduration, but more for high-frequency than for low-frequencygratings. These results are compatible with the assumptionthat there is a time delay in the occurrence of inhibitoryinteractions in the retina. (13 min.)

WC15. Visual Masking by Sinusoidally Modulated Light,G. M. SHICKMAN, Department of Ophthalmology, Washing-ton University, 660 South Euclid Avenue, St. Louis, Mis-souri 63110.-Visual masking of impulses of light by otherimpulses or fluctuating lights has been shown to be a non-linear process. The present work attempts to investigate theform of the nonlinearity through the use of sinusoidal timemodulation of the masking luminance. If masking were linear,one would expect a sinusoidal variation in the thresholdintensity of brief impulses superimposed regularly but en-harmonically upon the sinusoidally modulated background.Departures from this prediction demonstrate nonlinearity andto an extent allow its quantification. These departures aresmall if the background luminance is presented as a seriesof steady values that cover the range of the sinusoidal fluc-tuation. They increase with the frequency of modulation be-txveen 2 and about 10 cps, and with the amplitude of theluminance cycle. A prominent feature is a maximum of mask-ing nearly coincident with the upward passage of the back-ground luminance through its mean value. Since nonlinearityimplies an inequality between the response to a complex vari-

FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA 539

ation and the sum of the responses to the simple componentsof this variation, the question arises whether sinusoids orimpulses can provide more informative data about the proc-esses that underlie visual masking. (13 min.)

WC16. Frequency Doubling in Visual Responses.* D. H.KELLY, Vidya Division, Itek Corporation, 1450 Page MillRoad, Palo Alto, California 94307.-This paper reports anunexpected visual phenomenon. When a wide, photopic stimu-lus field is sinusoidally modulated in both space and time,over a certain frequency range the apparent spatial fre-quency of the stimulus is doubled. In its original form, the(deLange) flicker-fusion model which has been accepted bythe author and others cannot account for this result. But itcan be explained by the further assumption of a second(low-pass) filtering operation, which follows the nonlinear(brightness) response of the visual system, rather than pre-ceding it. If this assumption is correct, then the frequency-doubling effect is the result of neural mechanisms which aremore central than the locus of flicker fusion. (15 min.)

* Work supported by Warfare Vision Laboratory, U. S. Army ERDL, Ft.Belvoir, Virginia.

WCI7. The Effect of Temporal Waveform in FlickerElectroretinography. ROBERT H. PECKHAM, Eye ResearchFoundation of Bethesda, Maryland, 8710 Old GeorgetownRoad, Bethesda, Maryland 20014.-When the temporal formof flicker stimulation is a square-wave the ERG aroused bythe retinal stimulation is sinusoidal. It has been suggestedthat the stimulus waveform should correspond to this transferfunction of the retina when flicker perception is being inves-tigated. An apparatus has been built which uses the raster ona cathode ray tube as the light source. The horizontal driveprovides the flicker rate, and a much faster vertical drive

WEDNESDAY, 16 MARCH 1966

provides a rectangular raster. Opaque paper masks are cutto shape the waveform. When these are sine-wave tracessine-wave flicker stimulation is provided. A knob controlsintensity. The masks can be made in the shape of a vee-wave,the two slopes of which serve to establish thresholds in therate-of-change of retinal luminance to ON and OFF stimulation.Contrast is controlled by the physical separation of the upperand lower edges of the mask. The stimulation is presentedin Maxwellian view, which greatly enhances the intensity ofthe retinal luminance. The CRT face is imaged within thepupil of the observer, so that the mask contour is not per-ceived in a uniformly alternating illuminated field. Both per-ceptual and objective ERG flicker thresholds are presentedand compared. (12 min.)

WC18. Effect of Photo Excitation of the Two Retinason Pupil Size.* MATHEW ALPERN AND JURRIAAN TEN DOES-SCHATE, University of Michigan (Ann Arbor) and Univer-sity of Utrecht (Netherlands).-Infrared photographic meas-urements of the pupil sizes evoked by ipsilateral, contralateral,and binocular steady-state retinal illumination (Maxwellianview) will be reported. If binocular excitation is equal, thepupil is appreciably smaller than when only one (either one)retina is excited. This effect cannot be accounted for by add-ing either the lights or the contractions nor is it attributableto motor synkinetic effects associated with differences inaccommodation and/or vergence associated with binocular-as compared to monocular-excitation. If the binocular ex-citations are unequal, then the pupil shows characteristicsquite analogous to brightness perception. Data will be pre-sented which suggest that the relative role of rods andcones to these effects deserves more attention than theyhave so far received. (15 min.)

* Work assisted by a grant from NINDB.

DIPLOMAT ROOM AT 10:15 A.M.

GEORGE J. ZISSIS, Chairman

Contributed Papers

Radiometry

WD11. Reference Standards of Spectral Irradiance inthe Erythemal Region of the Spectrum (250-350 nm).FRANK J. STUDER AND R. F. VAN BEERS, Large Lamp De-partment, General Electric Company, Nela Park, Cleveland,Ohio 44112.-The spectral region 250 to 350 nm is of interestbecause of erythemal and photochemical effects. Referencestandards of spectral irradiance for energy measurement inthis region are available in two types. One is a quartz-iodinetungsten lamp calibrated at the National Bureau of Stand-ards on the basis of a blackbody source. The other is a cali-brated mercury arc produced by Philips and by Osram. Bothtypes show good reliability and maintenance, but neither isvery satisfactory to use. In the case of the former, the energyin this wavelength region is very small, with a stated cali-bration accuracy of approximately 8%. For the latter, thereare strong lines superposed on an appreciable continuum,which makes it difficult to use, especially where the linesare relatively close together. This paper will describe aprocedure used in measuring the erythemal energy outputof a lamp using these reference standards. It will also givethe results of a study of other possible standards for thisregion, particularly the concentrated xenon arc, and thehydrogen or deuterium arc. (13 min.)

WD12. Spectrally Variable Ultraviolet Source. MURPHYL. DALTON, JR., Electro-Optical Systems, 300 North Hal-stead, Pasadena, California 91107, AND JOHN ARVESEN,

Ames Research Center, Moffett Field, California 94035.-An optical system has been developed, primarily for photo-chemical applications, which is capable of altering the spec-tral distribution of the radiation striking the circular en-trance aperture of the system. This altered spectrum appear-ing at the plane of the exit aperture is unique in that itpossesses the same spectral isotropy and homogeneity as theentering beam. The spectral distribution can be continuouslyvaried from 100 percent to zero in any 200 A spectral bandfrom 1700A to 4100A in the present instrument, althoughin theory the bandwidth and spectral range are arbitrary.Irradiance in the 1700A to 4100 A spectrum is expected toexceed 200 mw/cm2 over a one-inch diameter exit aperture.(13 min.)

WD13. Spectral Radiance of the Low-Current GraphiteArc. ALBERT T. HATTENBURG, National Bureau of Standards,Washington, D. C., Connecticut & Van Ness, Washington,D. C. 20234.-The spectral radiance of the anode of a low-current graphite arc has been determined from 8500A to

540 FIFTIETH ANNIVERSARY MEETING

2000 A, utilizing a recently developed high-accuracy spectro-radiometer. The estimated accuracy varies from about 2%at the higher wavelengths to 4% at the lower. Regions of sig-nificant atomic and molecular radiation are largely omitted.Some data on contributions from the arc stream are included.(10 min.)

WD14. Cryogenic Photometers for Rocket Measure-ments of the Night Sky. IRENE S. GULLEDGE, E. 0. HslburtCenter for Space Research,* U. S. Naval Research Labora-tory, Washington, D. C. 20390.-Two recent NRL Aerobeerocket experiments included clustered photoelectric photom-eters cooled with liquid nitrogen for about 2 hours priorto launch. Effect on signal-to-noise ratio depended on tubetype and temperature. The optimum temperature was notthe same for the several types of tubes employed. The bestcompromise was found to be about zero degrees centigrade,where all types used showed significant improvement insignal-to-noise ratios. Data will be presented on the perform-ance of RCA S-li, EMI S-il and S-20, and Dumont S-1photomultipliers. Solutions to problems incurred at low tem-perature, such as frosting of the optics, will also be discussed.(12 min.)

* Work sponsored jointly by the Office of Naval Research and the NationalScience Foundation.

WD15. Dark Current Characteristics of High-Sensitiv-ity Multiplier Phototubes. MARTIN ROME, Electro-Mechani-cal Research, Inc., Princeton, New Jersey 08540.-Theperformance of a multiplier phototube at very low light levelsis determined by the tube's sensitivity and dark current.These characteristics, investigated in multi-alkali ruggedizedphotomultipliers used in space research, are strongly inter-related. The relationships of dark current and equivalentnoise input are examined showing the dependence of thephotocathode thermionic emission with long wavelength cut-off. The spectral response in quantum efficiency (photo-electrons per incident photon) is shown for the typical caseand with extended red response. Dark current for bothsemitransparent cathode and reflective cathode multiplierphototubes is presented as both dc anode current and numberof pulses per second as a function of temperature over therange of -40 to +80'C. Based on the data presented theoptimum choice of tube characteristics for maximum signal-to-noise ratio under low-level radiation is detailed. (13 min.)

WD16. Infrared Communication by Nocturnal Insects.*WILLIAM L. WOLFE AND MARVIN J. LUBBERS, Ilstitute ofScience and Technology, The University of Michigan, AnnArbor, Michigan 48107.-Several investigators"' have pro-posed that certain types of nocturnal insects communicateprincipally for mating purposes by infrared radiation. Thefemale moth's thorax is sometimes as much as 100K above

WEDNESDAY, 16 MARCH 1966

ambient by virtue of her metabolism and certain organs of themale appear ideal for 10-pt radiation detection. We are investi-gating these proposals by theoretical and experimentalmethods. The work reported here consists of calculations ofthe required detectivity of moth sensing apparatus for threeradiation types: (1) incoherent wideband and narrowbandradiation signals centered at 10 je, (2) coherent detection ofthe partially coherent graybody radiation of the female'sthorax, (3) graybody signals modulated temporally by wingbeats. The calculations of detectivity are all based on photonfluctuation noise rather than characteristic noises of specificdetectors or detector types; they therefore represent atheoretical limit for the type of radiation concerned. Methodsbased on the first type of radiation detection show thatextremely small detection bandwidths would be required-probably too small to respond to moths in flight. The secondmethod is no better than the first. The third method is adistinct possibility dependent upon the frequency response ofthe receiver and the frequency distribution of the sourceenergy. (13 min.)* Work supported by the U. S. Department of Agriculture, Beltsville,Maryland.IPrivate communication from P. S. Callahan, U. S. Department of Agricul-ture, Entomology Division, Tifton, Georgia.2

E. C. Okress, Appl. Opt. 4, 1350 (1965).

WD17. Infrared Spectral Reflectance at Controlled Tem-peratures.* H. J. KEEGAN AND V. R. WEIDNER, NationalBureau of Standards, Washington, D. C. 20234.-A methodfor the measurement of infrared reflectance at controlledtemperatures between that of liquid-nitrogen (-175'C) and850'C has been developed over the spectral range 4000 to450 cm-' (2.5 to 22 ,) on a high-resolution spectrophotometerwith a reflectance attachment.' The sample temperature iscontrolled by varying the power input to the source and tothe sample holder for the high-temperature measurements.For low-temperature measurements, a super-cooled substrateis employed.2 The measurement of the temperature of thesample, however, is made by means of thermocouple probesand potentiometer. Typical applications of this method areas follows: (1) Study of organic paint samples at 25, 100,200, 300, and 400'C and the deterioration of the sample heldat 3000C at 20-min intervals showing the change in reflect-ance as a function of time; (2) Reflectance measurementsof 10 of the 14 lanthanide rare-earth oxides (PrPOa, Nd!O3,SmrO0¢, Eu:03, Gd5O5, Tb2Oi, Dy20,, Ho,03, Er20,, andYb 2O3) at room temperature and at 3000C to determine in-fluence of water of hydration on the absorption bands of thesepowders; (3) Low-temperature measurements of N204 frost,NH3 ice, and NH. frost using a liquid-nitrogen frost cell atapproximately -175'C. (15 min.)* Work supported in part by the Advanced Research Projects Agency,Department of Defense.IJ. U. White, 3. Opt. Soc. Am. 54, 1332 (1964).2H. J. Keegan and V. R. Weidner, J. Opt. Soc. Am. 55, 1567 (1965).

REGENCY BALLROOM AT 2:00 P.M.

F. Dow SMITH, Chairmian

Invited Papers

WEL. The Role of Optics in Information Processing. ROBERT J. POTTER, Xerox Corporation,Rochester, New York 14603.-The variety of ways in which optical techniques are now beingapplied to information-processing problems will be reviewed and compared. Information to beprocessed is sometimes in optical or image form, i.e., image processing; in this case, optics isessential, at least for the input/output phase. Emphasis will be placed on the problems ofinformation storage by optical and photographic means. Also, optics has been used to goodadvantage for certain analogue processing problems. (30 min.)

. OPTICAL SOCIETY OF AMERICA

FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA 541

WE2. The Formation of Optical Images. ANDRE MARtCHAL, Institut d'Optique, 3 BoulevardPasteur, Paris 15', France.-The knowledge of the mechanism of the formation of opticalimages has been enriched during the last decade.-Phase contrast has been invented and developed.-The concept of partial coherence has been introduced and extensively studied.-The Fourier analysis has been used for practical applications as well as for theoretical studies.-The laser has renewed the interest for coherent light and stimulated the development ofholography and filtering techniques. Nevertheless some problems are still to be solved, at leastfrom a practical point of view, especially in the field of microscopy. (30 min.)

WEDNESDAY, 16 MARCH 1966 EMPIRE ROOM AT 3:15 P.M.

M. PARKER GIVENS, Chairman

Contributed Papers

Holography II and Coherence

WF1. Bochner's Theorem and the Wiener-KhintchineTheorem for the Quantized Electromagnetic Field.* E.WOLF AND C. L. MEHTA, Department of Physics and Astron-omy, University of Rochester, Rochester, New York 14627.-Some new positive-definiteness conditions, which are obeyedby the second-order coherence tensors and by the cross-spectral tensors of the quantized electromagnetic field areformulated and various consequences of the conditions arediscussed. These include an analogue of Bochner's theorem'and of the Wiener-Khintchine theorem, applicable to anyquantized stationary electromagnetic field. (A special formof the Wiener-Khintchine theorem for homogeneous quan-tized fields was recently given by Glauber).' Other conse-quences which will be discussed concern completely coherentfields and some aspects of the phase problem of coherencetheory.3 (13 min.)

* Work supported by the Air Force Office of Scientific Research and theAir Force Cambridge Research Laboratories.I cI. E. Lukacs: Characteristic Functions (Charles Griffin and Co., London,1960), p. 62.2R. J. Glauber, Phys. Rev. 131, 2786 (1963).

C. L. 'Mehta, E. Wolf, and A. P. Balachandran, J. Mlath. Phys. (inpress).

WF12. Phase Contrast Microscopy in Partially CoherentLight. M. DE* (INTRODUCED BY 0. N. STAVROUDIS), AppliedPhysics Department, University College of Technology, Cal-cutta University, 92 Acharya Prafulla Chandra Road,Calcutta-9, India.-In an earlier paper,1 results were reportedof the effect of partial coherence on the phase-contrast imagesof phase objects when the source was (i) circular andcentered on the axis, and (ii) annular. The phase-modifyingpatch on the phase-plate was assumed to be in an areaconjugate to the source. This paper shall describe somefurther results obtained with the circular source being shiftedaway from the axis (oblique illumination) and the phase-patch still lying on the axis and modifying the higher orderspectra. If the obliquity of the illumination is increased suchthat the zero-order spectra falls just outside the effectiveaperture, one would have a simulation of single-side-bandtransmission, and with the phase-patch still there to modifyone or the other order of the spectra, one would obtain whatmay be called a "schlieren-phase-contrast." Further exten-sion has been made to introduce a second similar sourceplaced symmetrically about the axis. This second source mayeither (i) be completely incoherent with respect to the firstone, or (ii) have a point-to-point coherence. The first caserepresents two simultaneous single-side-band transmissions,

while the second case represents the situation where thephase-object is being modulated with a carrier frequency.The effects of partial coherence have been studied for boththe above cases. (13 min.)

* Present address: Physics Department, Laval University, Quebec, Canada.'M. De and P. K. Mondal, J. Res. N.B.S. 69o, 199 (1965).

WFI3. Comparison of Coherently Illuminated Images.JAMES E. RAU, Autonetics, A Division of North AnsericanAviation, Inc., 3370 Miralonia Avenue, Anaheim, California92803.-If two coherently illuminated distributions arespatially separated at the front focal plane of a sphericallens and the resulting diffraction pattern is square law re-corded, the Fourier transform of the record contains com-parative data about the two input distributions. The transformof the record presents data in a reference frame that simplifiesthe problem of identifying and locating differences betweenthe two input distributions. The process of transforming,detecting, and retransforming is a method of convolving thetwo input distributions. If the inputs are identical, the auto-correlation function is derived. If only real functions areevaluated, the autocorrelation function is symmetrical aboutthe correlation peak. An asymmetry indicates a differencebetween the inputs, i.e., a cross-correlation function. Thevalue of the technique is that it reduces the procedure forcomparing spatial distributions to a search for asymmetryabout an easily defined point. Experimental results ofheterodyning the spectra of spatial distributions show thesensitivity of the technique to differences between two inputdistributions. (13 min.)

WF14. Interferometry with Reconstructed Wavefronts.J. M. BURCH AND A. E. ENNOS, National Physical Labora-tory, Teddington, Middlesex, England.-Hologram tech-niques make it possible to record and to reproduce subse-quently the phase information contained in a travelling lightwave. In hologram interferometry '-' at least one of theinterfering beams has been stored in this manner, and com-parison can be made for example between samples of thesame beam taken at different epochs. In many arrangementsthe wavefront reconstructed by diffraction at the holograminterferes with another wavefront transmitted through thehologram, and "live" two-beam fringes are obtained. Alter-natively "frozen" two-beam or even multiple-beam 2 patternsare obtained merely by recording double or multiple ex-posures on the same photographic plate. White light fringes

542 FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA

can sometimes be obtained by using a "direct image"hologram in a compensated system. Hologram interferometrycan be used to cancel unwanted aberration or to extract moreinformation from a wind-tunnel interferogram,5 but perhapsits most striking application is in detecting the deformation,whether gradual, sudden, or vibratory,' of an irregular ordiffusely reflecting surface, e.g., of an engineering structure.Alternatively, if the surface finish and obliquity of illumina-tion are sufficient to ensure specular reflection, severalseparately machined components can be compared inter-ferometrically against a master. Examples will be shown ofrecent work on these possibilities. (13 min.)

I R. L. Powell and K. A. Stetson, J. Opt. Soc. Am. 55, 612A (1965).2 J. M. Burch, 1965 Viscount Nufficld Memorial Paper, The ProductionEngineer 44, 431-449 (1965).3 R. J. Collier, E. T. Doherty, and K. S. Pennington, Appl. Phys. Letters7, 223 (1965).

R. L. Powell and K. A. Stetson, J. Opt. Soc. Am. 55, 1570 (1965).'M. H. Horman, J. Opt. Sac. Am. 55, 615A (1965).

WF15. Effect of Nonlinearities in Optical Data Process-ing. A. A. FRIESEM AND J. S. ZELENKA, Radar and OpticsGroup, Institute of Science and Technology, Tile Universityof Michigan, Ann Arbor, Michigan 48107.-A study of theeffects of photographic nonlinearities in optical data process-ing is reported. Particular emphasis is placed on holographyusing the two beam interferometry technique. A phenomeno-logical model which provides the mathematical formulationfor describing the effects of nonlinearities is described. Themodel includes a zero-memory nonlinearity which representsexperimentally derived transmittance-exposure curves forvarious photographic emulsions. An analysis of this model'reveals many interesting phenomena which are supportedexperimentally. In particular the nonlinearity of the filmgenerates false targets, causes weak signal suppression, andcan introduce additional noise as a result of spectral folding.Experimental results, verifying the analysis, are presented.These include (a) representative samples of transmission-exposure characteristics of various photographic plates andfilms, and (b) photographs of hologram reconstructionsdepicting increased noise and false targets with progressivelyincreasing nonlinearity levels. (13 min.)

WF16. Resolution of Images Reconstructed from CopiedHolograms. HAROLD W. ROSE (INTRODUCED BY BRIAN J.THiOMPSON), Air Force Avionics Laboratory (AVTL),Wright-Patterson Air Force Base, Ohio.-The problem ofproducing copies of a hologram is considered. In particular,the contact printing technique is analyzed in accordance withdiffraction theory. The results indicate that images recon-

WEDNESDAY, 16 MARCI-I 1966

structed from the "copy" will be noisier than those of theoriginal, even though (I) the original and copy emulsionswere in "perfect" contact, and (2) the optimum waveshapewas used for the contact exposure. Experimental results com-pare image resolution reconstructed from the copy withthat reconstructed from the original. (13 min.)

WF17. Wavefront Reconstruction with CentimeterWaves. G. TRICOLES AND E. L. ROPE, General DynamicsElectronics Division-San Diego Operations, 3302 PacificHighway, P.O. Box 127, San Diego, California, 92112.-Adescription is given of wavefront reconstructions which weremade with electromagnetic waves of centimeter wavelengths.The objects were a metallic strip and a hollow, dielectric,hemicylinder. Diffraction patterns are given for these objectsilluminated with nearly plane waves. Microwave analoguesof holograms are described. The configurations of the holo-gram analogues were determined with three different tech-niques corresponding to known optical methods.` Wavefrontreconstructions were made by illuminating the analogues witha microwave beam. These reconstructions are compared withthe fields diffracted by the objects. Some results are givenfor laser beam illumination of photographically reducedanalogues. (13 min.)'D. Gabor, Proc. Roy. Soc. (London) A197, 454 (1949).2E. N. Leith & J. Upatnieks, J. Opt. Soc. Am. 52, 1123 (1962).3 A. S. Hoffman, J. G. Doidge, & D. G. Mooney, J. Opt. Soc. Am. 55,1559 (1965).

WF18. Diffraction from Surface Ripple of AluminizedPhotographic Emulsions. KARL A. STETSON, G. C. A.Corporation, Burlington Road, Bedford, Massachusetts.-Thediffraction of light into hologram reconstructions byaluminized 649-f emulsion surfaces has been reported.' If itis assumed that the physical mechanism for this diffractionis a set of ripples in the emulsion surface that correspond tothe amount of silver developed at each point in the emulsion,then the diffraction process is described by the boundaryvalue problem solutions that have been published.2 In thecase of photographic emulsions, however, the height of theripples may be assumed to be small and an approximationmay be introduced into the formal solution which gives aninteresting result. Ripples of a few thousandths of a wave-length height give almost a percent or two of the incidentlight diffracted into the first order. This indicates that thediffraction of light may be the most practical method ofdetecting small periodic deformations in metal surfaces.(13 min.)IT. P. Vogl and A. K. Rigler, J. Opt. Soc. Am. 55, 1566A (1965).2 G. W. Stroke (thesis, The University of Paris, 1960).

PALLADIAN RooM AT 3:15 P.M.

GLENN A. FRY, Chairman

Contributed Papers

Vision II

WG11. Facilitation and Inhibition of Target Visibilityby the Spatial Characteristics of the Surround Field.JOSEPH F. STURR AND THOMAS E. FRUMIEES, Laboratory ofPhysiological Psychology, Syracuse University, 601 Univer-sity Avenue, Syracuse, New York 13210.-We have pre-viously shown that visibility of a black "test" disc (10' visualangle) was impaired by prior exposure to a larger, concen-

tric "masking" disc; threshold inhibition was greater inthe periphery than in the fovea, and the smallest masks weremost effective.' This report extends the data to a largerrange of mask sizes, from 15' to 2°. Targets were presentedcentrally and at 20 and 6° in the horizontal meridian of theleft visual field by means of a two-channel tachistoscope.In addition to threshold inhibition with masks smaller than

FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA 543

30', the present results showed facilitation in the fovea withsurrounds greater than 30', and in the periphery with maskslarger than 1°. The data for both fovea and periphery shownegatively accelerated functions, reaching asymptotes at alevel below the unmasked conditions. For intermediate masksizes, facilitation is demonstrated in the fovea, inhibition inthe periphery. Visibility is facilitated at all retinal positionswith the largest masks. These results are discussed in termsof contour interactions and signal detection theory, and therole of afterimages in threshold facilitation is evaluated.(13 min.)

'J. F. Sturr, T. E. Frumkes, and D. M. Veneruso, Psychon. Sci. 3, 327(1965).

WG12. Flash Photolysis of Rhodopsin: A Maximum inthe Bleaching Function. E. BRUCE GOLDSTEIN AND THEO-DORE P. WILLIAMS, Division of Biological and Medical Sci-ences, Walter S. Hunter Laboratory of Psychology, BrownUniversity, Providence, Rhode Island 02912.-Solutions offrog and cattle rhodopsin were irradiated with flashes whosedurations ranged from 0.8 to 30 ms. Plots of percent bleachedvs log intensity show that, beyond some intermediate inten-sity, the percent bleached begins to decrease with increasingintensity, i.e., the functions exhibit peaks. This effect issmall or absent at short flash durations but is quite pro-nounced at long durations. For example, for a 0.8 ms flashthe bleaching function for cattle rhodopsin levels off at 50percent bleaching at high intensities. However, for a 30 msflash the curve reaches a maximum of 81 percent and thendecreases as the intensity is increased further; flashes 0.3,0.6, and 0.9 log units more intense than the flash whichbleaches 81 percent cause 77, 71, and 65 percent bleaching,respectively. This decrease in bleaching is shown to be dueto the photoreversal of metarhodopsin II to rhodopsin. Astatistical analysis of rhodopsin bleaching is applied to theknown bleaching mechanism and theoretical curves arecalculated which fit the experimental results and predict thata 50 percent bleach will obtain at very high intensities evenwith long duration flashes. (13 min.)

WG13. Binocular Stabilization of Image. E. P. HORNEAND R. M. HILARIDES, University of Florida, Gainesville,Florida.-Binocularly perceived movement (apparent) de-pends on pulse rate of alternately pulsed illuminated aper-tures. Induced binocular hyperphoria is an effective variableon the total duration of apparent movement. Fixation-non-fixation conditions indicated no significant difference. Theoryof image stabilization in absence of apparent movement willbe discussed. (13 min.)

WG14. Relation Between the Ongoing Electroencephalo-gram and Fluctuations of Visibility of a StabilizedRetinal Image.* t ULKER TULUNAY KEESEY AND DENNIS J.NICHOLS, Department of Surgery (Ophthalmology), Uni-versity of Wisconsin Medical Center, Madison, Wisconsin53706.-The subject viewed an 8' field whose image wasrendered stationary with respect to the retina, and signalledthe disappearance and reappearance of the target during a16-sec inspection period. Together with these signals, oc-cipital EEG was recorded and analyzed on-line by a 160-ACDC computer. The computer was programmed to recognizean alpha pattern and relate it to the reported disappearanceand reappearance of the image during each of the 250trials. The analysis showed that for the majority of thecases, alpha activity precedes fading of the image by ap-proximately B sec. A computer aided control experimentshowed that under normal viewing conditions, the small

amount of alpha present followed simulated disappearance.Subsequently, an effort was made to control the visibility ofthe stabilized image by means known to alter alpha activity.A closed-loop computer program was used to present a flashof light to the other eye or a burst of white noise at aselected time following the start of the alpha burst. Suchinterference with alpha resulted in a marked reduction of thetotal disappearance time of the image, but when disappearancedid take place it was found to be preceded by alpha activity.(13 min.)

* This project was supported by a General Research Support Grant to theUniversity of Wisconsin Medical School from the National Institutes ofHealth, Division of Research Facilities and Resources, Bethesda, Maryland.t While this project was being completed a report of a similar study con-ducted by D. Lehman, G. W. Beeler, and D. H. Fender appeared inElectroencephalography and Clinical Neurophysiology 19, 336 (1965).

WGl5. Objective Discrimination of Document Readabil-ity. H. M. A. EL-SUM, El-Sums Consultants, 74 MiddlefieldRoad, Atherton, California 94025.-When the image of apattern of concentric rings is blurred by progressive defocus-sing the central illumination of the image exhibits abruptdiscontinuities between which the intensity changes mono-tonically. At any discontinuity the intensity at the centerrelative to neighboring off-center points is always an ex-treme. Successive discontinuities have alternate maxima andminima. The position of the discontinuity is a function ofboth the degree of blur and the rings' radii. An optimumdesign of concentric-rings target can be made such that thediscontinuities coincide with specific readability measureson the continuous readability scale.1 In its simplest form thetarget consists of one ring, yielding one discontinuity. Ifthis discontinuity occurs at that state of defocus which hasbeen established or adopted as the threshold of readability, atarget pattern imprinted upon a document may serve as aninstant indicator of impairment of readability incurred byany imprecise focussing, since the incidence of a discontin-uity is revealed by a cursory glance at the target bull's-eye.(13 min.)

IH. M. A. El-Sum, J. Opt. Soc. Am. 55, 1580A (1965).

WG16. A Family of Portable Reading Machines for theBlind. GLENDON C. SMITH (INTRODUCED BY EUGENE F. MUR-PHY) AND HANS A. MAUCH, Mauch Laboratories, Inc., 3035Dryden Road, Dayton, Ohio 45439.-The most advancedpersonal type reading machine described provides the blinduser with an aural "spelled speech" equivalent for each upperand lower case letter or ligature scanned by a hand heldoptical probe. The seven-eighths inch diameter optical barrelof the probe contains a 13 mm focal length f: 1.9 lens, andan array of photocells. Both are positioned by special camswhich permit easy adjustment of the magnification to anyamount between 1X and 5X. This character recognition ma-chine recognizes the most popular type fonts (9 have beentested to date) with moderate accuracy (90-95%) and speed(80-90 words per minute) by using a special arrangementand orientation of twelve CdSe photoconductive cells togather information on letter features. The development ofthe hand held probe for this machine has resulted in a familyof aural and tactile "direct translation" reading aids whichare pocket sized and battery operated and may be used inde-pendently for low speed reading. A mechanical tracking aidis also described. One or more operating devices of eachtype discussed have been built and tested. (13 min.)

WG17. Reading Machines for the Blind. EUGENE F.MURPHY, Research and Development Division, Prostheticand Sensory Aids Service, Veterans Administration, 252Seventh Avenue, New York, New York, 10001.-A coordi-

544 FIFTIETH ANNIVERSARY MEETING

nated program to develop reading machines for the blind hasbeen supported for some years by the Veterans Administra-tion. Six conferences have provided guidance and exchange ofinformation. Some relatively simple scanning devices havebeen developed to transfer typed or printed characters intopatterns of tones or tactile stimulation, and a 200-lessontraining program has been compiled. Clinical trials show afew carefully selected blind subjects can decipher typingslowly but independently. A more complex yet moderatelypriced machine for recognizing typed or printed charactersof a dozen common fonts has been completed in bench modelform. Attention has been given to both audible and tactileoutputs; the former range from patterns of organ-like tones(from simple portable optophone-like devices) through"spelled-speech" to actual spoken words (from prerecorded"dictionaries"), rules for synthesizing continuous speech, orhybrid schemes. Optical problems include simple means tomaintain focus over a range of type sizes and constructionof cadmium selenide photocell arrays. (13 min.)

WG18. A History of Gloss Measurement. RICHARD S.HUNTER, Hunter Associates Laboratory, Inc., 9529 LeeHighway, Fairfax, tVirginia.-The earliest recorded instru-mental measurements of gloss were by Ingersoll in 1914.

WEDNESDAY, 16 MARCH 1966

He developed a polarization instrument to compare specularwith diffuse reflection. He called the ratio glare, but it isnow called contrast gloss. Jones in 1922 described a contrast-gloss method for photographic papers. He supplemented hisstudies with some early goniophotometric curves. Otherworkers in the late 20's and early 30's used visual instrumentsfor measuring contrast gloss, or luster as it is known inthe textile industry where much of this work was done.Pfund, in 1925 and 1930, working mainly with paints, evalu-ated contrast gloss, specular gloss, and distinctness-of-reflected images. He thereby showed that different glossprocedures are necessary to handle different gloss problems.In 1937, Hunter described six different light-reflectance cri-teria which are used in commerce for the visual grading ofvarious materials for gloss. Correspondingly, there need to besix different instrumental techniques for gloss detection tomeet all the requirements of this field. The American Societyfor Testing Materials, primarily in its Paint Committee D-1,has led the way in preparing and standardizing instrumentalmethods for gloss measurement. There now exist roughlyten different industry-wide instrumental procedures for spec-ular gloss and one for sheen. Specific procedures for themeasurement of contrast gloss, haze, and distinctness-of-image gloss have been proposed but not yet adopted. (13min.)

DIPLOMAT ROOM AT 3:15 P.M.

W. LEwis HYDE, Chairman

Contributed Papers

Geometrical Optics

WHIl. Optical Systems for Modern Large Telescopes.HORST K6I(LER, Carl Zeiss, Inc., Oberkochen, West Ger-inany.-It is shown that, with a Ritchey-Chretien system,an almost anastigmatic image flattening can be achieved bymeans of one single-field flattener in the vicinity of the imageplane. Furthermore, reference is made to the development ofcorrection systems which, together with the primary mirrorof a Ritchey-Chretien system, yields a field of 10 at anaperture ratio of 1: 3 'and a mirror diameter of 3.5 m.(13 min.)

WHI2. Modulation Transfer Functions for UnusualAperture Shapes. DARRYL E. GuSTAFSON AND THOMAS I.HARRIS, Optical Research Associates, 550 North RosemneadBoulevard, Pasadena, California.-A special computer pro-gram has been written to compute the modulation transferfunction of various aperture shapes such as the half-annulusand pie-type apertures. Comparisons between the MTFcurves for these apertures and those of the full annulus andcircular apertures will be shown. Where possible, rough rulesof thumb for estimating the MTF for a given aperture typewill be given. (10 min.)

WH13. (Abstract wvithdrawn.)

WH14. Lens Optimization by Computer Methods. DAVIDS. GREY, Aerospace Corporation, PO Box 95085, Los An-geles, California 90045.-There now exist many successfulcomputer programs for optimizing preliminary lens specifica-

tions. To our knowledge, these basically proceed by minimiz-ing a sum of squares of defect items, they use the linearizationmethod, and they evoke safeguards against the fact that thematrix inverted is almost certainly nearly singular. Twoconsiderations plagued early development of such programs:(1) Balance of image "flare" vs "core" and (2) Investiga-tion of local minima vs finding true minima. The first of thesehas been solved by various investigators and it has beenadequately demonstrated to be solvable by programs whichrate optical performance by ray trace residuals. It will beargued that programs based on ray trace residuals proceedmore quickly and more precisely to local minima than doprograms based on classical aberration coefficients. Thesecond of the above considerations has not been solved bycomputer methods. The computer does, however, free thelens designer to exercise his ingenuity and inventive abilityto pursue study of local minima to the utmost. Foreseeablefuture developments of these computer methods seem to usmore dependent on increased core memory than on lessexpensive arithmetic. (13 min.)

WH15. The Lens-Cone Microscope. ROBERT E. WARD,JR., 7881 Niagara Street, Commerce City, Colorado.-In thispaper we will describe and demonstrate an optical instrumentemploying a lens-cone image projecting system. The lens-cone system enables the instrument to produce high imagemagnification on a comparatively large screen, but in avery confined space. We will also describe and demonstratethe high image resolution produced by the instrument. The

. OPTICAL SOCIETY OF AMERICA

FIFTIETH ANNIVERSARY MEETING

lens-cone system is fully described in the paper "OpticalProperties and Uses of the Conical Mirror" published inAppl. Opt. 4, 201 (1965). (13 min.)

WH16. A Three-Mirror Flat-Field Photographic Objec-tive. R. V. SHACK AND A. B. MEINEL, University of Arizona,Tucson, Arizona.-A design is described which consists ofthree aspheric mirrors with no refracting components, yetwhich provides excellent imagery over a 5.4o flat field atf/1l.75 (effective f/2) with a six-inch entrance pupil diameter.The resolving power exceeds 100 lines per mm over themajor part of the field. The design is unusually compact, itsover-all length being five inches, and is well baffled againststray light. (10 min.)

WH17. Dioptric Schmidt Lenses. RUBIN GELLES, Kolls-man Instrument Corporation, Elnhurst, New York 11373.-The principle of placing the stop at the center of curvaturein order to correct coma and astigmatism is applied to arefractive system. The result is an exact equivalent to theSchmidt camera. Two versions of the refractive system areshown and an application as a spectrograph is discussed.(10 min.)

WH18. Lens Design by a Flexible Computer Program-ming System. RICHARD J. HEiMER (INTRODUCED BY ARTHURMAGILL), Fairchild Space and Defense Systems-A Divisionof Fairchild Camera and Instrument Corporation, 2718 Grif-fith Park Boulevard, Los Angeles 27, California.-An auto-

THURSDAY, 17 MARCH 1966

* OPTICAL SOCIETY OF AMERICA 545

matic programming system for optical design has been de-veloped for use on a large scale computing machine. Theprogramming system has been organized with a view towardsobtaining comprehensive control over the principal stagesof the lens design process. The framework of the program iscomposed of three addressable levels. The lower level con-tains a semi-automatic correction routine for the third- andfifth-order aberrations similar to the program described byHennessy and Spencer.' The functions of this program levelare lens precalculations and the preparation of possibleprovisional design solutions with a good balance betweentime of computation and accuracy. The second level of theprogram system contains the automatic ray aberration cor-rection routine. The correction method used is a furtherdevelopment of a program described by Spencer.2 Positivecontrol of boundary conditions, accommodations for 50 imageerrors, aspherics, and decentered optics design are amongthe capabilities of this routine. The third level of the programcontains the evaluation routines. The evaluation modes in-clude (1) spot diagrams, (2) knife edge trace, (3) energydistribution, (4) geometrical and wave optical frequencyresponse of sinusoidal and three bar chart targets. This paperdescribes the programming system briefly and includes a de-tailed disclosure of the results obtained in the application ofthe system to a number of practical problems. (13 min.)

I W. P. Hennessy and G. H. Spencer, J. Opt. Soc. Am. 50, 494 (1960).2 G. H. Spencer, Appl. Opt. 2, 1257 (1963).

WH19. (Abstract withdrawn.)

REGENCY BALLROOM AT 9:00 A.M.

KARL G. KESSLER, Chairman

Invited Papers

ThAl. Optical Resonators. G. TORALDO DI FRANCIA, Institute of Physics of the University,Florence, Italy.-The open resonator, a new type of optical component introduced in recentyears, is now widely used in laser and microwave techniques. Strictly speaking, such a devicedoes not have true resonating modes, but only virtual modes or quasi-modes. For this reasonthe theory of open resonators has appropriately been developed in terms of traveling modes.Two main approaches have been used, namely physical optics and waveguide theory. Themathematics is sometimes involved and one has often to resort to numerical integrations.However, spherical-mirror resonators, which constitute the main family and include as aparticular case the plane parallel Fabry-Perot, are today pretty well understood and there is alot of experimental evidence on their operation. However, the flat-roof resonator, recently intro-duced by the author, and other types of geometry probably deserve some more theoreticaland experimental work. As a by-product of optical resonator theory, valuable new insight hasbeen gained in such general problems of physical optics as for instance beam theory and thecorrespondence between object and image. (30 min.)

ThA2. New Methods in Instrumental Spectroscopy. R. CHABBAL, Place Aristide Briand,78-Bellevue, France.-(30 min.)

THURSDAY, 17 MARCH 1966 EMPIRE ROOM AT 10:15 A.M.

ARTHUR L. SCHAWLOW, Chairman

Contributed Papers

LasersThBI1. Fabry-Perot Resonators Immersed in MovingHost Media. HARRY SCHACHTER AND LEONARD BERGSTEIN,Polytechnic Institute of Brooklyn, 333 Jay Street, Brooklyn,

New York 11201.-An integral equation is derived for theresonant modes of Fabry-Perot resonators immersed in mov-ing host media and its solution is found. It is shown that

546 FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA

to the first order of approximation, a resonator immersed inan isotropic and homogeneous moving host medium can bereduced to a corresponding equivalent resonator with astationary host medium. The resonant frequencies of theinterferometer are found to be approximately linearly de-pendent upon the velocity of the moving medium. Theresulting phase and frequency modulation of the beam emerg-ing from the resonator is discussed. (13 min.)

ThB12. Filters, Wave Plates and Protected MirrorsMade of Thin Polished Supported Layers. D. R. HERRioTT,J. R. WIMPERIS, AND D. L. PERRY, Bell Telephone Labora-tories, Incorporated, Mountain Avenue, Murray Hill, NewJersey.-A number of optical devices including low-orderwave plates, solid spherical Fabry-Perot filters, and protectedhigh-reflectance laser mirrors have been made using thinpolished supported layers of quartz, fused silica, and glass.Techniques for fabricating the devices and their performancewill be described. (13 min.)

ThBI3. Saturated Absorption of Color Centers in 1.06 tzLaser Glass. E. SNITZER AND R. WOODCOCK, AmericanOptical Company, Southbridge, Massachuesetts.-By saturatedabsorption of color centers in glass, self Q-switched pulsesand limit cycles are obtained in Nd3 and Nd3`-Yb3+ laserglasses emitting at 1.06 u. The glass base consisted of 73wt.% SiO2, 11 I(O, 8 Naa0, 1 Li2O, 5 BaO, and 2 A12O2.The color centers give broad absorption bands at 310 nm,450 nm, and 620 nm" 2 and are produced by uv light shorterthan 300 nm. The centers are bleached by visible or longwavelength uv light, and by heating to 2000C for one hour.However, the saturable absorption is associated with addi-tional color centers that are in the glass only while the shortwavelength uv from the flashlamp is present. The self Q-switched pulses can be separated by 200 pusec, with a durationof 35 nsec and an energy of 1 joule/pulse. The spectrumfrom a Nd2+ glass is 2 A wide. In the case of a Nd3+-Yb2+laser glass which produces only limit cycles, the rate equa-tions3 give for the saturated absorption coefficient the value6X11Y 2-%/cm. (13 min.)

"R. Yokota, Phys. Rev. 95, 1145 (1954).2 A. Kats and J. M. Stevels, Philips Res. Repts. 11, 115 (1956).'K. Shimoda, Optical Masers, Microwave Res. Inst. Symp. Series 13(Polytechnic Press, Brooklyn, New York, 1963), p. 95.

ThB14. A Sun-Pumped CW One-Watt Laser.* C. G.YOUNG AND J. Z. ZDROK, American Optical Company, 14Mechanic Street, Southibridge, Massachusetts.-One watt ofCW laser output has been obtained at room temperaturefrom a sun-pumped neodymium-doped YAG crystal. Thewater-cooled laser rod was pumped with a modified Casse-grain sun-tracking telescope consisting of a 61-cm diameterparaboloidal primary mirror collector, a water-cooled hyper-bolic-cylindric secondary mirror and a hemicircular cylindrictertiary mirror. The cylindrical image volume was coincidentwith 22 mm of the 3 mm by 30-mm YAG rod. The spike-freeoutput was obtained for hours at a time with a late-Octobersun at a 420 North latitude. Using the same primary mirrorand near-unity numerical aperture refractors, approximatelyone and a quarter watts were obtained in 7-msec pulsesfrom an uncooled sun-pumped neodymium-doped glass rod.Further refinements in the telescope and the laser crystal,and a space environment, should allow one watt of laseroutput to be generated by using a 30-cm diameter collector.(13 min.)

* Work supported by AF Avionics Lab., Research and Technology Division,A.F. Systems Command, USAF, Wright-Patterson Air Force Base, Ohio.

ThB15. Precision Measurement of the Spatial Distribu-tion of CW Laser Power. HERBERT B. HALLOCK, CARLKROLIrC, AND JOSEPH GRUSAUSKAS, Grummnan Aircraft En-gineering Corporation, Bethpage, New York.-It is probablethat the use of wideband laser communications will accom-plish a manifold increase in effectiveness for the deep spacescientific mission. Since waste of coherent power defeatsweight conservation the practical engineering of the narrow-beam optical communications system demands very accuratemeasurement of laser far-field output power patterns. Itmust be possible to predict the effective intensity of thetransmitter, not only on axis, but also at small angles fromthe axial direction. On these measurements is based theoptical design of laser power coupling devices and also theprecision high-power telescope objective, the "antenna" ofthe system. The laboratory instrumentation used in the evo-lution of an "optical antenna range" is described and datataken on optically pumped Nd"3 YAG, GaAs injection diode,and He-Ne gas lasers are presented. (13 min.)

ThB16. Calculated Mode-Patterns for Infinite Strip Res-onators with Phase Distortion. J. M. BURCH AND R. E.BORLAND, National Physical Laboratory, Teddington, Mid-dlesex, England.-A KDF9 computer has been used to ob-tain numerical eigenfunctions and eigenvalues for the fourdominant modes of an infinite strip confocal resonator whosemirrors have been slightly distorted. The phase variationsintroduced across either mirror are represented by a trigono-metric series with up to ten Fourier coefficients. 201 pointsacross the mirror surface are used for evaluation of thecomplex symmetric kernel, and 49 points for solving theintegral equation. Results are presented for Fresnel numbersbetween 1 and 4 and for several simple types of corrugationwhose amplitude varies from ±X/16 to -X. The behavior ofthese solutions is discussed. (13 min.)

ThB17. Rays and Ray-Envelopes Within Stable Opti-cal Resonators Containing Focusing Media.* WALTER K.KAHN AND NORITAKA KURAUCHI (Sumitomio Electric mId.,Ltd., Japan), Polytechnic Institute of Brooklyn, 333 JayStreet, Brooklyn, New York 11201.-In stable resonatorsany given initially paraxial rays remain close to the axis ofthe structure and are, in fact, confined within well-definedcontours, the envelope of the ray system. Outside this en-velope intensities decay rapidly. Previously, envelopes of raysin empty resonators had been found and their form identifiedwith the variation of the spot size.12 This geometric opticalapproach is extended to general resonators, comprising arbi-trary arrangement of lenses and convergent or divergentinhomogeneous focusing media. An invariant quadratic forminvolving parameters descriptive of any of the ray-segmentswhich result from a given initial ray-segment leads to adifferential equation satisfied by the ray-segments in portionsof the resonator. A maximum-minimum problem for the en-velope is formulated and solved. In convergent media theenvelope function is found to be periodically modulated. Theperiod of the modulation depends only on the properties ofthe convergent medium; the location of relative maxima andminima as well as their ratio depends on both the mediumand associated optics. In special cases, results are comparedwith available solutions of the corresponding electromagneticproblem. (13 min.)

* This work was, in part, supported by the Joint Services: AFOSR, ARO,ONR..

V. P. Byhov and L. A. Vainstein, JETP (Trans.) 20, 338 (1965).2 W. K. Kahn, Appl. Opt. 4, 758 (1965).

FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA 547

THURSDAY, 17 MARCH 1966 PALLADIAN ROOM AT 10:15 A.M.

DAVID H. RANK, Chairman

Contributed Papers

Atomic and Molecular Spectroscopy

ThC11. Critique of the MIT Wavelength Tables. GEORGER. HARRISON, Massachusetts Institute of Technology, Cam-bridge, Mass.-In 1931 tables were published listing 110 000spectrum lines chosen as most strongly emitted by atomicelements under normal excitation. Although these tables havestood up well under a quarter century of use, more completeand up-to-date lists of atomic wavelengths are now needed.These should include new data from the literature as well asmeasurements made with the greatly improved equipmentand methods now available. To satisfy requirements of mostusers of such tables, seven figure wavelengths, and intensitieson a uniform scale, are needed for more than a million linesfrom neutral and ionized atoms. Both the necessary and theaccidental limitations of the MIT Tables will be discussed,together with present-day methods of automatic measure-ment, reduction, and recording which could greatly reducethe estimated thousands of man-years of effort otherwiserequired. Of particular value are improved standard sources,secondary standards of wavelength, and diffraction gratingswhich exceed in speed and resolution the Fabry-Perot etalonsavailable in the 1930's. Groups interested in compiling mod-ern successors to the MIT Tables should be encouraged toproceed. (13 min.)

ThC12. The Instrumental Profile of High ResolutionSpectrometer Obtained from a Laser Line. L. DELBOUILLE(introduced by MARY E. WARGA) AND G. ROLAND (paperpresented by M. V. MIGEOTTE), University of Litge, Institutd'Astrophysique, Cointe-Sciessin, Belgium-The exact knowl-edge of the apparatus function of a spectrometer is veryimportant, permitting one to apply corrections to observedspectra. For low and medium resolving power instruments,the observation of narrow emission lines, as for examplegiven by an isotopic, Hg lamp, gives a sufficiently accuraterecord of the instrumental profile. In the case of the mostmodern instruments of very high resolution, the physicalwidth of such emission lines is no more negligible in com-parison with the instrument profile. A special ionized argonlaser, emitting at 4880 A in only one mode and well tempera-ture-stabilized, has been used to observe the profile of thespectrometer associated with the MacMath solar telescope(Kitt Peak), and of our Jungfraujoch spectrometer. Acomparison of the two instruments will be given as well asa correction test on the solar strontium resonance line. (13min.)

ThC13. Studies of Iron I and II Spectral Line Intensitiesat Various Currents and Neon Gas Pressures in a HollowCathode Discharge Tube.* DAVID W. STEINHAUS ANDMICHAEL A. ZERWEKH, Los Alamos Scientific Laboratory,Los Alamos, New Mexico 87544.-Relative intensity meas-urements were made on a set of spectrograms containingthe spectra obtained from an iron hollow cathode dischargetube operated at currents ranging from 0.10 to 1.14 A andneon gas pressures from 0.6 to 21.5 torr. Five Fe I and sevenFe II lines were chosen to cover a wide range of upperenergy level values for each spectrum. For each line, theintensity ratios at various current and pressure values weredetermined. These ratios indicate that many combinations ofpressure and current can be used for a unique separation ofthe first spectrum from the second spectrum. Certain com-

binations of pressure and current indicate that an estimateof the upper energy level value may be possible also. Thesedata are important as an additional clue in the analysis ofcomplex spectra, where the usual thermal light sources can-not be used because of the line width limit to the spectralresolution. Additional measurements of many more lines arebeing made on these same spectrograms for particular valuesof current and pressure. The LASL automatic comparator isbeing used for these precision relative intensity measurements.(10 min.)

* Work performed under the auspices of the U. S. Atomic Energy Com-mission.

ThC14. Excitation Transfer Cross-Section in Hg-Tl Va-pors.* B. CURNUTTE, JR., AND B. C. HUDsoN, Kansas StateUniversity, Manhattan, Kansas 66504.-The relative intensi-ties of mercury resonance fluorescence and of thallium sensi-tized fluorescence in Hg-Tl vapor mixtures have been deter-mined experimentally. The quartz cells employed were out-gassed for prolonged periods at 10000C at pressures of 5X10-8torr or less. Small amounts of Hg vapor were introduced,along with copious amounts of Tl located in a side reservoir.During measurements the main cell temperature was variedover the range 5000 to 9000C, and the Tl reservoir wasmaintained at a temperature of 50'C below that of the maincell. Mercury densities were monitored by line absorptiontechniques; thallium densities were based on vapor-pressuredata. Equilibrium rate analysis of collision processes, absorp-tion processes, and emission processes allows the calculationof excitation transfer cross sections from the experimentallydetermined intensity ratios. The experimental arrangementswill be described, and the approximations involved in thecalculations will be discussed. The values obtained for theexcitation cross sections are comparable in magnitude withcollision cross sections based on considerations of gas kinetics.(13 min.)

* Work supported in part by ONR and ARPA as a part of ProjectDEFENDER.

ThC15. Far Infrared Spectra of D20 Solutions of AlkaliHalides.* DAVID A. DRAEGERT AND DUDLEY WILLIAMS,Kansas State University, Manhattan, Kansas 66504.-Recentstudies' of the far infrared spectra of water and heavy waterhave been extended to include aqueous solutions of the alkalihalides. The present report gives the results obtained for DOsolutions of these salts. The major far infrared band centerednear 505 cmy' at room temperature and commonly attributedto hindered rotation is strongly influenced by the solutes.Comparison of spectra obtained with various sets of solu-tioris having common concentrations indicates that this bandis more strongly influenced by negative ions than by positiveions. In the presence of a common positive ion, the frequencyof the absorption maximum decreases in the order F-, Cl-,Br-, I-. A similar shift in band position is observed as thetemperature of the pure solvent is increased. It is difficult toassess the effects of solutes on the minor 165-cm-' band,which appears as a shoulder on the much stronger majorband. (13 min.)

* Work supported in part by U. S. Air Force Cambridge Research Labora-tories, Office of Aerospace Research.'Draegert et al., J. Opt. Soc. Am. 56, 64 (1956).

548 FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA

ThC16. Photoionization of O2 in the Metastable a'A,State. G. R. COOK AND R. J. McNEAL, Aerospace Corpora-tion, P. 0. Box 95085, Los Angeles, California 90045.-Amixture of molecular oxygen and helium, excited in a 2450-Mc/sec microwave cavity, has been pumped through a paral-lel plate ion chamber attached to the exit slit of a one meterSeya-Namioka vacuum monochromator. Recent evidence sug-gests the presence of an appreciable concentration of themetastable a'A, state of 02 in the afterglow.1 A search forthe photoionization process 02 (a'A0 )++h-O 2 I(X

2Hg) +e-has been made between 1068 and 1495 A with an argon con-tinuum background light source. A sharp onset of ionizationis observed at 1118.0A (89445 cm'a) which continues withvarying intensity to the limit of observation at 1068A. Byadding the known energy2 (7882.39 cm-') of the transition0(a 1 A,-X32 X7) to the observed ion edge, the ionizationpotential of O2 (X 2;,-) is calculated as 12.067+0.001 eV,which is in good agreement with the value of 12.075±0.01 eVreported by Watanabe et al.? (13 min.)

I F. Kaufman and J. R. Kelso, Discussions Faraday Soc. 37, 26 (1964).2 G. Hcrzberg, Spectra of Diatomic Molecules (D. van Nostrand Co., Inc.,New York, 1950), p. 560.- K. Watanabe, T. Nakayama, and J. Mottl, J. Quant. Spectr. Rad.Trans. 2, 369 (1962).

ThC17. Enhancement of EuW2 Fluorescence by ComplexFormation.* HARVEY FOREST (introduced by FRANCE B.

THURSDAY, 17 MARCH 1966

BERGER), ARYEH H. SAMUEL, AND DANIEL GRAFSTEIN, Aero-space Group Research Center, General Precision Inc., 1225McBride Avenue, Little Falls, New Jersey.-The Eu`2 fluor-escence in solution has been found to be significantly en-hanced in aprotic solvents of the type O=PX3. The fluores-cence enhancement is attributed to complex formation whichdecreases the nonradiative deactivation of the excited 'Dostates of Eu+3. A complex between Eu+3 and hexamethylphos-phoramide (HMPA) has been isolated and found to havethe formula EuC133HMPA. The high resolution (<1A)fluorescence spectrum of a EuCl2 -HMPA solution indicatesthat the ligand fields of the solid complex and of its HMPAsolution are identical. Other solvents studied include tri-ethylphosphate (TEP) and tributylphosphate (TBP); theseappear to form similar tricoordinated complexes with Eu43.The fluorescence and absorption spectra of the complexeshave been analyzed in terms of the ligand field about theEut. The ligand field symmetry favors the 'Do->F 2 fluores-cent transition. However, one-step chemical reaction involv-ing TEP- and TBP-solvated EuCl1 is reported which pro-duces a new complex of the general formula EuPOc20=P(OR)3. Profound effects on the Eu+3 fluorescence, dueto the change in ligand symmetry, are found and investigated.This latter complex favors the 'Do--F 1 fluorescent transi-tion. (13 min.)

* Work supported in part under ONR Contract NONR 4644(00).

DIPLOMAT ROOM AT 10:15 A.M.

ORESTES N. STAVROUDIS, Chairman

Contributed Papers

Physical Optics

ThD11. A New Theorem on the Ultimate Limit of Per-formance of Optical Systems. WALTER LUKOSZ (introducedby M. E. WARGA), Institut A fiur Physik, Technische Hoch-sc/rule, 33 Brazunschweig, Gersnany.-The modern and moreexact formulation of the (classical) resolution limit is thatoptical systems transfer a limited band of spatial frequenciesonly. The bandwidth depends on the angular aperture of thesystem and the wavelength of the light used. We will presenta new theorem saying that not this optical bandwidth butthe total number of degrees of freedom of the optical mes-sage transferred by the system is constant, when the angularaperture of the system and the wavelength are given. Thetotal number of degrees of freedom is equal to the productof object area times the two-dimensional optical bandwidth,times a factor 2-due to the two possible states of polariza-tion-, times the number of temporal degrees of freedom.According to the new theorem there are several possibilities toincrease resolution beyond the classical limit. It must be pos-sible (a) to extend the two-dimensional bandwidth by reducingthe object area, or (b) to increase the bandwidth in x direc-tion while reducing it in y direction, so that the two-dimen-sional bandwidth is constant, or (c) to extend the two-

dimensional bandwidth while reducing the temporal resolution,etc. Experimental methods achieving this will be described.(13 min.)

ThD12. On the Measurement of the Optical TransferFunction. GEORGE B. PARRENT, JR., AND RICHARD J. BECH-ERER, Technical Operations Research, Burlington, Massachu-setts.-Many of the recent treatments of optical imagingmake extensive use of linear systems analysis. Since, how-ever, the intensities of the image and of the object are themeasured quantities, an optical imaging system is nonlinearfor all but incoherent illumination. This, together with thetheorem that an incoherent field cannot exist in free space, 1

means that the imaging problem is inherently a nonlinear one.To determine the significance of this conclusion two com-monly used techniques of measuring optical transfer functionswere examined in detail using the formalism of the theoryof partial coherence. With the use of a realistic model forthe coherence of the light in an analyzing instrument e.g.a microdensitometer, it is shown that both sine wave analysisand edge trace analysis lead to significantly erroneous trans-

FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA 549

fer functions at line frequencies considered to be within thestate of the art. It is further shown that since the significantparameter is the ratio of the spot size to the coherence in-terval in object space, nonlinearities can become importantat relatively low spatial frequencies. The implications of theseresults for image evaluation are discussed. (13 min.)

1 Beran and Parrent, Theory of Partial Coherence (Prentice-Hall, Inc.,Englewood Cliffs, N. J., 1964), p. 47.

ThD13. Spatial Phase Measurement for Image Correla-tion. M. HALBERSTAM, Newtek, Inc., 39-25 62nd Street,Woodside, New York 11377 .-In many applications it isnecessary to register two images to each other. This is nor-mally done by scanning the two images and computing thecross correlation of the two fields. Maximum correlation isobtained when there is best registration between the images.In this paper a method is presented whereby the registrationis accomplished by measuring the spatial phase differencewhich is due to misregistry. This is accomplished by movinga grating across the two image fields and measuring thetransmitted light through the system. The two signals ob-tained have a phase difference which is simply related to thespatial frequency of the grating and the amount of mis-registry between the images. Experimental measurements ofphase difference as a function of relative image displacementwill be presented. Further extensions of the method formeasuring image displacement in two directions will also bedescribed. (13 min.)

ThD14. Optical Network Synthesis Using BirefringentCrystals. IV. Synthesis of Lossless Double-Pass Net-works. E. 0. AMMANN, Electronic Defense Laboratories,Sylvania Electronic Systems, Mountain View, California.-Harris et al.' have found a procedure for synthesizing bire-fringent networks whose amplitude transmittance C (a) is arbi-trarily specified. They have shown that a C(w) consisting of(n+l) terms of a finite exponential series can be realizedby a network containing is identical birefringent crystals.This talk describes modifications of their procedure whichallow the realization of birefringent networks containing ap-proximately half the number of crystals normally required.These networks (which we term double-pass networks) con-tain fewer crystals because the light makes two passesthrough the network. The double-pass network basicallyconsists of the first half of the network of Harris et al.,'followed by a mirror. Two double-pass synthesis proceduresare described, one for which the output and input coincide(i.e., are spatially degenerate), and one for which the outputand input are spatially separated. These procedures can beused whenever the term coefficients (the C+) of C(co) satisfythe restrictions Co=-C," Cx-Co-1., C2 =-C,-2. . . . etc., orequivalently stated, whenever a sine series has been used forC(co). (13 min.)

IS. E. Harris, E. 0. Ammann, and I. C. Chang, J. Opt. Soc. Am. 54,1267 (1964).

ThD15. A Wide-angle, Narrow-band Optical Filter. D.W. WILMOT AND E. R. SCHINELLER, Wheeler Laboratories,Inc., Box 561, Smithtown, N. Y. 11787.-A novel opticalfilter is described which is capable of simultaneously achiev-ing a wide field of view and a narrow frequency bandwidth.This performance is obtained by fabrication of the filter froman array of single-mode optical waveguides, in the form ofglass fibers. The fibers are limited to a single mode of propa-

gation by the proper choice of their size and refractive index.The filtering is accomplished in a manner analogous to con-ventional Fabry-Perot or multilayer interference filters byinserting semitransparent mirrors within the waveguide. Theprinciple of operation is that a wave incident on the array iscoupled into the fiber waveguides where energy can propa-gate in only a single mode. The propagation characteristicswithin the fibers are independent of the angle of incidentradiation, and therefore, the frequency characteristics of afilter fabricated within the waveguide are also independentof the angle of incidence. The bandwidth and center fre-quency of the filter are determined by the spacing and thereflectivity of the mirrors while the angle response is deter-mined only by the fiber size. Therefore the angle and fre-quency characteristics are mutually independent and eachcan be designed separately for a particular application. Thedesign criteria and specifications of this filter are discussed,and anticipated performance in terms of field of view, band-width, transmission, and resolution are presented. (13 min.)

ThD16. Specular Reflection and Characteristics of Re-flected Radiation in the Optical Region. HERBERT B. ROLL,U. S. Army Missile Command, Redstone Arsenal, Alabama35809.-Numerical solutions of the Fresnel equations forapproximately 2500 indices of refraction, recently publishedby the presentor are compared with similar efforts by Dr.Vasicek of the University of Brno. The discussion then de-scribes in detail the occurrence of reflection characteristicsfor which (a) the amplitude of the wave oscillating parallelto the plane of incidence is a minimum, (b) the degree ofpolarization is a maximum, and (c) the two amplitudes ofthe reflected wave have a difference in phase of 900. Thenumerical solutions provide a means, in addition to thosealready in general use, for the determination of the indexof refraction of the bulk material. The above mentioned re-flection characteristics are related to those now known aspseudo Brewster angle, polarization angle, and principal angleof incidence. Since some physics textbooks and several pub-lications make incorrect use of these names, a clarificationof the distinction to avoid misunderstanding is proposed. Itwas found that for a certain small region of N we have twoor even three angles of incidence where the difference inphase after reflection is 90°. That fact is not in line withthe name-principal angle of incidence. The proposal is touse the name Brewster angle only in the case of a real indexof refraction (X), and to use the. names first, second, andthird Brewster angles for the cases of complex indices (N).Careful inspection of the material presented shows that thefollowing relation holds, without exception, for the threeangles (denoted by 01*, 6a*, 03*): 0i*<02*<0a*). (13 min.)

ThD17. The Reflectance Envelope of an Iterated Multi-layer.* JOsEPH ARNDT AND PHILIP BAUMEISTER, Instituteof Optics, College of Engineering and Applied Science, Uni-versity of Rochester, Rochester, New York 14627.-Twoenvelopes, corresponding to the minimum and maximum re-flectance curves of an iterated multilayer, have been obtainedanalytically in terms of the matrix elements of the basicperiod. The analytic expressions are applicable to the generalcase without restriction to the number, thicknesses and in-dices of the layers in the basic period, and where the layersmay be inhomogeneous and the substrate absorbing. Severalnumerical examples are shown. (10 min.)

* Work supported in part by the National Science Foundation.

550 FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA

THiURSDAY, 17 MARCH 1966 REGENCY BALLROOM AT 2:00 P.M.

A. G. SHENSTONE, Chairmnan

Invited Paper

ThEl. Autoionization Effects in Atomic Spectra. W. R. S. GARTON, Imperial College ofScience and Technology, London, S.W.7, England.-Autoionization effects-large natural line-width and apparent perturbations of spectral intensities-were first recognized by Shenstoneand Majorana in the early 1930s, and explained in terms of Auger ejection of one of the outerelectrons of an atom raised to an excited state above the first ionization potential, by inner-shellor double-electron excitation. Though in thirty years much observational material accumulatedfrom laboratory spectra-especially through absorption work in the vacuum-ultraviolet pioneeredby Beutler, developed further at Reading University and Imperial College-little systematicdescription or theoretical interpretation had been achieved. Recently, theory and experiment haveadvanced rapidly. Thus, the older qualitative explanation in terms of "radiationless transitions"has been supplemented by employment of the "configuration mixing" concept and the computa-tion of positions and widths of "resonances" in the scattering cross sections for electrons orphotons. Experimentally, utilization of the background continuum of an electron synchrotronhas revealed striking effects in the extreme-ultraviolet absorption spectra of the inert gases.

That the autoionization process and its converse ("dielectronic recombination"), have rele-vance to detailed mechanisms in laboratory and astrophysical plasmas, was recently illustratedby computation of electron recombination rates and recognition of Fraunhofer lines with auto-ionizing upper states.

Recent work at Harvard, employing shock-tubes, has led to recognition of "forced autoioniza-tion" in Ba i due to microfield depression of the ionization potential, and, through measurementof reversal temperatures on autoionized lines, to support for assumption of local thermal equi-librium in the shock-heated gas. (45 min.)

THURSDAY, 17 MARCH 1966 EMPIRE ROOM AT 3:00 P.M.

HAROLD E. BENNETT, Chairman

Contributed Papers

Materials and Scattering

ThF11. Improved Thermal-Expansion Measurements ofOptical Materials.* STANLEY S. BALLARD, JAMES S. BROW-DER, AND HOYT M. I(AYLOR,t Department of Physics, Uni-versity of Florida, Gainesville, Florida 32603.-Additionaldata have been obtained on the linear coefficient of thermalexpansion of small samples of optical materials, using animproved apparatus.' Two techniques are available, the "tem-perature-drift" technique 2 for samples of medium thermalconductivity, and an adjustable-temperature technique em-ploying thermoswitches for samples of low thermal conduc-tivity. The available temperature range has been broadenedand is now 00 to 900C. Very good internal consistency ofdata is obtained, despite the fact that calculations are madeover a temperature interval of only 100C. New data arereported on various infrared-transmitting materials: singlecrystals, hot-pressed compacts, and glasses. (13 min.)

* Work supported by the U. S. Air Force Cambridge Research Laboratories,Office of Aerospace Research.t Permanent address: Birmingham-Southern College, Birmingham, Alabama.IS. S. Ballard, J. L. Streete, and J. S. Browder, J. Opt. Soc. Am. 54,1401A (1964).IS. S. Ballard and J. S. Browder, J. Opt. Soc. Am. 55, 612A (1965).

ThF12. Measurement Technique for Thin Surface Layerof Color Centers. ROBERT F. EDGERTON, Department ofPhysics, Carleton College, North field, Minnesota.-The re-flectivity of a perfect dielectric-vacuum interface at Brew-

ster's Angle for light polarized with the electric field vectorparallel to the plane of incidence is zero. The measurementof this reflectivity requires a source of light that is mono-chromatic, collimated, plane polarized, and intense. The laseras a light source fills all of these requirements. When ultra-violet light is used to create F centers and self-trapped holesin alkali halide crystals, they are formed in a thin layer(approximately 100 nm thick) at the surface of the crystaldue to the high absorption coefficient of the material in theexciton absorption region of the spectrum. Direct measure-ments by transmitted light of these thin absorbing layers isdifficult because although the centers are present in highconcentration, there is a small total number, and the amountof light absorbed is very small compared to the transmittedlight. A layer of absorbing centers should make the indexof refraction become complex and increase the value of thereflectivity at Brewster's Angle. It is proposed that meas-urements on the reflected light of a polarized laser beam atBrewster's angle might make it possible to detect and there-fore measure the excitation spectrum for the generation of Fcenters by ultraviolet light. (13 min.)

ThF13. Optical Properties of Mo and Sn in the Vacuumuv.* R. A. MAcRAE (introduced by E. T. ARAKAWA), Cen-tral Piedmont Community College, Charlotte, North Caro-lina 28204, E. T. ARAKAWA AND R. N. HAMM, Oak Ridge

FIFTIETH ANNIVERSARY MEETING

National Laboratory, Oak Ridge, Tennessee 37831.-The realand imaginary parts (n,k) of the complex index of refrac-tion were obtained from reflectance measurements at 200 and70° angles of photon incidence on bulk Mo and vacuum-evaporated Sn. The complex dielectric constant e and theenergy loss function Im(l/e) were calculated from the ex-perimental n and k values. An intense peak was found inthe Im(1/e) curve of Sn at 13.8 eV and a weak peak at 10.6eV in Mo. The 13.8-eV loss in Sn agrees well with thevalues of 14.1 eV found by Powell' from characteristic elec-tron energy loss experiments and 13.6 eV by Walker et al.2

from the onset of optical transmission. The theoretical valueof the volume energy is 14.3 eV, with the number of freeelectrons per atom being taken to be the number of valenceelectrons (4). The value of 10.6 eV for the volume plasmaenergy of Mo can be compared with the theoretical value9.4 eV, calculated using n=l. A loss at about 12 eV has beenfound from characteristic electron energy loss experiments.(13 min.)

* Research sponsored by the U. S. Atomic Energy Commission under con-tract with Union Carbide Corp.1 C. J. Powell, Proc. Phys. Soc. (London) 76, 593 (1960).2 W. C. Walker, 0. P. Rustgi, and G. L. Weissler, J. Opt. Soc. Am. 49,471 (1956).

ThF14. Interferometric Quality Beam Splitter for theWavelength Region 5 to 30 t. P. L. HEINRICH AND R. C.BASTIEN, Electro-Optical Division, The Perkin-Elmer Cor-poration, Norwalk, Connecticut 06852.-An all dielectricbeam splitter for use in an Infrared Interferometer from 5to 30tt has been designed and fabricated. The beam splitterand mount assembly were designed for launch pad and or-bital environments. Substrates studied included rare-earthhalides. Criteria for substrate selection included refractiveindex homogeneity, high infrared transmission from 5 to 30,ttand maintenance of interferometric quality after simulatedlaunch vibration tests. Filming materials were investigatedfor use in multilayer systems meeting environmental andoptical performance requirements. Step-graded index filmsystems were employed to satisfy the requirement of thebeam splitter operating over a frequency range of 6 to 1.This work was supported by NASA-Goddard Space FlightCenter. (10 min.)

ThF15. Polarization of Rayleigh Scattering. D. H. RANK,D. P. EASTMAN, AND AMOS HOLLINGER, Osmond Lab, ThePennsylvania State University, University Park, Pennsyl-vania 16802.-Polarization of Rayleigh scattering has beeninvestigated for eight liquids making use of a 300-mW He-Ne laser as the light source. The measurements were madeusing polarized incident light. The method is capable ofeasily detecting depolarization of only a few tenths of oneper cent. We have measured the depolarization of the un-modified and modified "Brillouin components," and also thedepolarization of the "rotational wings." The results obtainedvary from complete polarization to complete depolarizationdepending on the liquids investigated. In addition, the velocityof hypersound has been accurately measured for these liquidsas a function of temperature. (13 min.)

ThF16. Stimulated Effects in N2 and CH 4 Gases. T. A.WIGGINS, R. V. WICK, AND D. H. RANK, Osmond Lab, ThePennsylvania State University, University Park, Pennsyl-vania 16802.-Stimulated Brillouin scattering from N2 andCH 4 using a giant pulse laser has been observed in an ar-rangement whereby the laser cannot release and amplify the

* OPTICAL SOCIETY OF AMERICA 551

backscattered radiation. This allows a quantitative study ofthe parameters affecting stimulated Brillouin scattering. Thebackscattered beam converges at the same angle at whichthe laser beam diverges. The Brillouin component can havea narrow spectral width, ;i that of the laser itself, and insome cases can have a duration of only a few nanoseconds.N2 at high pressure can backscatter as much as 45% of theincident power. The speeds of sound in CH4 and N2 have beenmeasured at lower pressures than were previously reported.(10 min.)

ThF17. Photoelectric Recording of Laser-Excited Ra-man Spectra of Gases. S. P. S. PORTO, L. E. CHEEESMAN,Bell Telephone Laboratories, Incorporated, Murray Hill,New Jersey, A. WEBER, Fordham University, New York,New York,* AND J. J. BARRETT, Perkin-Elmer Corp., Nor-walk, Conn.-The use of the He-Ne red laser as a sourcefor pure rotational Raman spectra of gases has made thissource comparable to the classical mercury sources1 as faras photographic work is concerned. We wish to report thatcontinuous photoelectric recording of pure rotational Ramanspectra in simple gases has been obtained, with signal-to-noise ratios close to 100:1. The sources used were A' lasersoperating at 4880 and 5145 A. Raman spectra were obtainedfor N2, 0, CO2, and methyl acetylene. The samples wereplaced both inside and outside the laser cavity and compari-son of results in different geometries are to be given. Thedepolarization ratios of both the Rayleigh and Raman lineswere measured and an estimate of the absolute cross sectionfor the pure rotational spectrum is to be given. A tandemspectrometer was used to reduce the stray radiation and toavoid grating ghosts. A geometry in which such tandemspectrometer might not be needed is to be discussed andresults evaluated. Improvements obtained in the photographicrecording of the rotational Raman effect using the 6328AHe-Ne laser are also to be shown. (13 min.)

* Work supported by the National Science Foundation.1A. Weber, S. P. S. Porto, J. Opt. Soc. Am. 55, 1033 (1965); Bull. Am.Phys. Soc. 10, 101 (1965).

ThF18. Enhancement of Stimulated Raman Emission byTransverse Electrostatic Field. ZINDEL HERBERT HELLERAND JOSEPH A. CALVIELLO, Airborne Instruments Labora-tory, Div. of Cutler-Hammer, Inc., Walt Whitman Road,Melville, Long Island, New York 11749.-The authors haveobserved that stimulated Raman emission from organicliquids located inside the cavity of a Q-spoiled ruby lasercan be enhanced by application of a transverse electrostaticfield. The effect has been obtained with the 30 00-cm' infra-red-active vibration of fluorobenzene and the 990-cm' sym-metric vibration of benzene. It is proportional to field up tothe maximum value thus far applied, 6 kV/cm, and exhibitsdirectional properties relative to the polarization of theoptical laser field. Simultaneous with the stimulated emis-sion, a current pulse is observed in the transverse field sup-ply leads. In polar molecules, such as fluorobenzene, the axishaving greatest Raman coefficient (change of polarizabilitywith vibration coordinate) can be oriented by the appliedfield to produce the observed effect. However, in benzene,which has only an induced dipole, orientation effects aremuch smaller. The enhancement may be caused by a travel-ling infrared wave at the vibration frequency. In either case,the current pulse could be explained by variation of bulkdc capacitance of the liquid sample cell caused by anhar-monic polarizability of the molecules undergoing intensestimulated vibrations. (12 min.)

552 FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA

TH URSDAY, 17 MARCH 1966 PALLADIAN ROOM AT 3:00 P.M.

WILLIAM C. MARTIN, Chairman

Contributed Papers

Atomic Spectroscopy

ThG11. The Spectra Ni II and CuIII and the Possibil-ity of Making Much More Complete Analyses of Well-Known Spectra. A. G. SHENSTONE, Palmer Physical Lab-oratory, Princeton University, Princeton, New Jersey.-The isoelectronic spectra Ni II and Cu III originally pub-lished as partial analyses have now both been observed withsuitable sources and spectrographs so that the number oflines in each has been increased to several thousand from afew hundred. The resulting analyses are far advanced andshow that the analyses of many complex spectra can begreatly improved and extended by means of new observa-tions. (13 min.)

ThG12. Experimental Values of the Oscillator Strengthsfor Some of the Two Electron Transitions in Bariumand Strontium.* R. D. HUDSON AND VIRGINIA L. CARTER,

Aerospace Corporation, P.O. Box 95085, Los Angeles, Cali-fornia 90045.-Absorption spectra of barium and strontiumvapors have been obtained photoelectrically at a bandwidthof 0.075A from their respective series limits to 1600A. Theinstrumentation and experimental techniques were similar tothose described by Hudson and Carter.' All of the absorp-tion lines resulting from two electron transitions as reportedby Garton, Pery and Codling,' and Garton and Codling,5

have been observed. For those lines whose half widths aregreater than 0.4A the true line shapes, and consequently theoscillator strengths, could be measured. For those havinghalf-widths between 0.15 and 0.4 A true line shapes could notbe obtained, but it is believed that estimates of oscillatorstrengths can be made from the experimental line shapes, towithin an accuracy of ± 50%. The oscillator strengths, anda discussion of the assumptions involved in obtaining themwill be presented. (13 min.)

* Work performed under USAF contract.'R. D. Hudson and V. L. Carter, Phys. Rev. 137, A1648 (1965).2 W. R. S. Garton, A. Pery, and K. Codling, Proceedings of the 4th Inter-national Conference on Ionization Phenomena in Gases, Uppsala, 1959(North-Holland, Amsterdam, 1960), p. 206.'W. R. S. Garton and K. Codling, Proc. Phys. Soc. (London) 75, 87(1960).

ThG13. The Absorption Spectrum of Neon in theSpectral Region 150-275 A. K. CODLING AND R. P. MADDEN,

National Bureau of Standards, Washington, D. C. 20234.-The absorption spectrum of neutral neon has been studiedphotographically and photoelectrically' using the synchrotronlight as a background source. The wealth of structure ob-served can be associated basically with two types of transition:(i) The excitation of a subshell 2s electron to outer p orbitsand (ii) simultaneous excitation of two outer 2p electrons.The latter transitions account for the bulk of the observedstructure and attempts have been made to classify it interms of optically allowed transitions. Many cases of con-figuration interaction are apparent. The resonance in thephotoionization continuum due to the one-electron transition2s22p5 'So-> 2s2p0 3p 'P,' has been studied photoelectricallyand values of q (line shape parameter) and r (width ofresonance) obtained. Also of interest is the degree to whichthe discrete state mixes with the various continua available,measured in terms of the autoionization-to-dipole correlationcoefficient p. Values obtained experimentally for these param-

eters will be presented and the theoretical implicationsconsidered. (13 min.)1 D. L. Ederer and R. P. Madden, see Abstract ThG 14.

ThG14. A High-Resolution Monochromator for Study ofResonance Profiles in the Extreme Ultraviolet. D. L.EDERER t (introduced by R. P. MADDEN) AND R. P. MADDEN,National Bureau of Standards, Washington, D. C. 20234.-A 3-m grazing-incidence grating monochromator has beendesigned and built for use in the wavelength region 50-800 A.This instrument was designed specifically to utilize the con-tinuum radiated by the NBS 180-MeV electron synchrotron.Some of its design features are: (a) rugged kinematic con-struction with few adjustments, thus maintaining resolutionin the presence of vibrations generated by the synchrotronmagnet, (b) resolution of 0.06 A, allowing the quantitativemeasurement of many absorption features, (c) effectiveisolation of the gas absorption region from the high vacua inthe synchrotron donut and the detector chamber withoutthe use of windows. To demonstrate the capability of theapparatus some measurements of line profiles due to innershell excitations in the rare gases ' will be presented.(13 min.)t NRC postdoctoral fellow.'R. P. Madden and K. Codling, Phys. Rev. Letters 12, 516 (1963).

ThG15. A Study of the Kinetic Energies of ElectronsProduced by Photoionization.* JAMES A. R. SAMSON ANDR. B. CAIRNS, Experimental Physics Department, GCACorporation, Burlington Road, Bedford, Massachusetts 01730.-The kinetic energies of electrons produced by the photo-ionization of xenon have been measured using a sphericalelectron energy analyzer. Two discrete energies are observedin the wavelength range 900 to 520 A corresponding to the2P3/2 and 2P1/2 states of the ion. The ratio of the number ofelectrons with these discrete energies has been measuredover the above spectral range. The extension of this techniqueto the study of electrons ejected from inner subshells of theatom will be discussed. (13 min.)* This work is supported by the National Aeronautics and SpaceAdministration.

ThG16. The Excitation of Helium by the Impact of FastProtons.* EDWARD W. THOMAS AND GARY D. BENT, Georgiainstitute of Technology, Atlanta, Georgia 30332.-The exci-tation of a helium target gas by the impact of fast (150-1000 keV) protons has been studied under single collisionconditions. Light emitted from the collision region wasanalyzed spectroscopically and detected using a low noisephotomultiplier. The effects of detector noise were minimizedby chopping the light entering the spectrometer at 100 cpsso that the resulting signal could be identified by its specificfrequency and phase. The over-all quantum detection efficiencyof the spectrograph was determined by calibration againsta standard tungsten filament light source. Measurements havebeen made of the cross sections for the emission of variousHe I spectral lines. The use of theoretical transition prob-abilities to calculate branching ratios and cascade contribu-tions allows the determination of the cross *sections for thepopulation of various 'S, 'P, and 'D states by direct collisionalexcitation. The high energy behavior predicted by the Born

FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA 553

approximation is observed. Comparison is also made withdata on excitation by electrons at the same velocity of impact.Preliminary data on the excitation of other target gases byproton impact are also presented. (10 min.)

* Work supported by the U. S. Atomic Energy Commission.

ThG17. Excitation of the He II 3s,p,d-4s,p,d,f Line Com-plex (4686 A) in a Helium Atomic Beam. H. P. LARSONAND R. W. STANLEY,* Purdue University, Lafayette, Indi-ana 47907.-The gaseous atomic beam developed by Stanley'has been used to excite the n=4 to n=3 transition in ionizedhelium by electron bombardment of a beam of neutral heliumatoms. The fine structure has been studied photoelectricallywith a pressure-scanned double Fabry-Perot interferometerutilizing phase sensitive detection with digitized output. Theatomic beam has reduced the linewidths to 0.008 cmn' instrong He i singlets using a collimation of 18. Even with thecollimation reduced to 3, to obtain strong excitation of thisHe ii transition, line widths of only 0.056 cm' still wereobserved. The collision-free and field-free characteristics ofthis atomic beam source have been demonstrated, respectively,by the almost complete absence of the He i triplet transitionsand by the absence of Stark shifts among these He ii transi-

The Technical Group on Spectroscopyend of this session.

THURSDAY, 17 MARCH 1966

tion components which would be sensitive to field strengthsof the order of 20 V/cm. Thus, the measured relative in-tensities and separations of these He ii fine structure compo-nents should represent more closely those of an unperturbedatom at rest than with any other source used in this studyin the past. (13 min.)

* Present address: Laboratorie Aime-Cotton, CNRS, Bellevue (S.-et-O.),France.1 R. W. Stanley, J. Opt. Soc. Am. 53, 1349 (1963).

ThG18. Least-Squares Adjustment of Atomic EnergyLevels.* K. L. VANDER SLUIS, Oak Ridge National Labora-tory, Oak Ridge, Tennessee.-A practical solution to theleast-squares adjustment of atomic energy levels has beenobtained. This solution is particularly compatible to computa-tion by a digital computer since it is conservative of totalstorage space and computational time. Examples of fittedarrays in the spectra of erbium will be presented and dis-cussed. A typical array of 185 energy levels adjusted to fit1122 transitions required a fast memory storage of approxi-mately 5400 words and used 70 sec of computational time.(13 min.)

* Research sponsored by the U. S. Atomic Energy Commission undercontract with the Union Carbide Corporation.

will meet in the Tudor Room at the

DIPLOMAT ROOM AT 3:00 P.m.

J. T. Cox, Chairman

Contributed Papers

Thin Films

ThH11. Optical Constants of Aluminum Determinedfrom Reflectance and Transmittance. JEAN M. BENNETT(introduced by H. E. BENNETT), Michelson Laboratory,China Lake, California 93557.-Using the computationalmethod previously described,' it is possible to determine theoptical constants n and k of semitransparent films from themeasured reflectance, transmittance, and film thickness. Thismethod has been successfully applied to nearly opaque filmsof aluminum deposited by rapid evaporation in a vacuum ofapproximately 5X10-' torr. The film thicknesses were about250 A and were measured interferometrically. The reflectanceof opaque aluminum can be calculated using optical constantsdetermined from these films. Even if no oxide film correctionis applied, the calculated reflectance agrees with measuredvalues to better than 0.01 in the wavelength range 0.35 to4.0 y. Still better agreement can be obtained if the surfaceoxide film is taken into account. Thus, this method appearsto be useful both for determining bulk optical constants andfor determining the optical thickness of surface oxide films.(13 min.)

I Jean M. Bennett and Maxine J. Booty, J. Opt. Soc. Am. 55, 597A(1965).

ThH12. Multilayer Interference Coatings for the NearUltraviolet. JOSEPHi H. APFEL, Optical Coating Laboratory,Inc., Santa Rosa, California 95401.-Thin films of magnesiumoxide and magnesium fluoride have been used to coat en-vironmentally stable multilayer filters for use in the 2000 to4000 A region. The ratio of indices is too small to allowfeasible manufacture of narrow bandpass filters, however,several types of short wavelength pass filters and reflection

filters have been made. The high stress in these filmingmaterials limits the total number of layers that may be usedwithout severe film fracture. Filters with sixty layers arefeasible, and absorption free coatings for wavelengths greaterthan 2200 A have been made. (10 min.)

ThH13. Spectrally Selective Filters for the Middle Ultra-violet.* WILLIAM R. McBRIDE, U. S. Naval Ordnance TestStation, China Lake, California 93557.-The need for photo-detectors which respond to middle ultraviolet radiation atwavelengths below 3000 A, yet reject energy at longer wave-lengths, has led to the development of multiplier phototubeswith semitransparent cesium telluride or rubidium telluridecathodes. The spectral selectivity of these so-called "solarblind" multiplier phototubes, however, can be improvedsubstantially near their photocathode threshold with a shortwavelength passband filter. The feasibility of such dielectricfilters which possess both high transmission in the middleultraviolet and sharp cutoff characteristics near 3000 A hasbeen demonstrated recently by research supported at theOptical Coating Laboratory, Incorporated. Since solar radia-tion is attenuated by atmospheric ozone below 3000 A, aterrestrial-based detector can be designed to operate in themiddle ultraviolet without regard to background discrimina-tion. The main discussion describes the spectral character-istics of ultraviolet filters useful for this purpose. (10 min.)* Work was supported in part by the U. S. Advanced Research ProjectsAgency.

ThU14. Induced Absorption for Internal Reflection Spec-troscopy. N. J. HARRICK (introduced by A. F. TURNER),

Philips Laboratories, Briarcliff Manor, N. Y. 10510 AND

554 FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA

A. F. TURNER, Bausch & Lonlib Inc., Rochester, N. Y. 14602.-Induced absorption ' may be employed to amplify weakabsorption for Internal Reflection Spectroscopy. Completeabsorption for either the p or s polarized component can beinduced in a given absorbing layer at one wavelength by theprior application of thin-film coating to the surface of theinternal reflection element. The coatings have the function ofmaking the optical admittance into the internal reflectionsystem equal the complex conjugate of the admittance intothe absorbing layer. The design of the coatings thus incorpo-rates two sections, one for phase adjustment, and one foramplitude matching. The first is an interference film; thesecond, for simplicity, may be a frustrated total reflection(FTR) film. A structure consisting of an internal reflectionprism of Ge coated with a BaFa FTR film followed by a Gephase adjusting film has been designed for enhancing theabsorption at 2.9 u due to a certain thickness of water film onthe free surface of the Ge film. The total system representsa high Q optical cavity with an absorbing layer located onthe free surface in the absorption-sensitive loop of its stand-ing wave pattern.2 (13 min.)

'A. F. Turner and P. H. Berning, J. Opt. Soc. Am. 15, 408(A) (1955);F. Berz, Mullard Research Laboratories, England has shown that enhancedabsorption should also be obtained in a structure consisting of a quarterwave film on a substrate of higher refractive index. Brit. J. Appl. Phys.16, 1733 (1965).2 N. J. Harrick, J. Opt. Soc. Am. 55, 851 (1965).

ThH15. Square-Top Transmission Band Interference Fil-ters for the Infrared. J. A. Do1ROWvOLSKI, Division of Ap-plied Physics, National Research Council of Canada, Ottatwa,Ontario, Canada, AND R. C. BASTIEN, Electro-Optical Divi-sion, The Perkin-Elmner Corporation, Norwalk, Connecticut06852.-A program for the automatic synthesis of thin-filmsystems' was used to generate a series of designs of square-top transmission band interference filters for the infraredspectral regions. With comparatively few layers a very steepcutoff and a high rejection ratio can be achieved. By placingtwo or more such filters in series (either coherently on onesubstrate, or incoherently on several substrates) it is possibleto further increase the rejection ratio. In a typical filter com-bination consisting of two separate filters placed in series thetheoretical transmission in the transmission region was of theorder of 99% and the average transmission in the rejectionregion was of the order of 5X10-4%. Filters of this type canbe produced in practice and the performance of actual filterswill be compared with the theoretical results. (13 min.)

' J. A. Dobrowolski, Appl. Opt. 4, 937 (1965).

THURSDAY, 17 MARCH 1966

ThHI6. Optical Properties of Inhomogeneous ThinFilms of Varying Modes of Gradation. GERHARD LESSMAN,General Dynamnics, Pomona Division, Pomnona, California.-The variation in optical properties of gradated thin filmswhose index of refraction varies as a function of thickness iscalculated for various modes of gradation using a recentlywritten' inhomogeneous thin film computer program. Linear,sinusoidal, and other modes of gradation of the refractiveindex as a function of thickness are compared with variousmultiple homogeneous layer approximations' of inhomog-eneous films. It is shown that the properties of gradated filmsof equivalent optical thickness are not markedly affected bythe gradating function, and that such films may be consideredvectorially as though their Fresnel coefficients at the twodiffering index boundaries are functionally independent. Thisgreatly extends multiple layer configuration design possi-bilities, of which some examples are given. (13 min.)

'A. G. Tescher abstract ThH 18.2 H. Anders and R. Eichinger, Appl. Opt. 4, 899 (1965).

ThH17. Equivalent Layers in Multilayer Filters. ALFRED

THELEN, Optical Coating Laboratory, Santa Rosa, California.-Extending the work of Epstein,' the theoretical basis andthe properties of equivalent layers in multilayer configura-tions are presented. The results are applied to the design ofpractical long-, short-, and bandpass filters. (10 min.)

'L. Ivan Epstein, J. Opt. Soc. Am. 42, 806 (1952).

ThHl8. Computer Techniques for the Analysis of In-homogeneous Thin-Film Configurations. A. G. TESCHER,General Dynamics, Pomzona Division, Pomsona, California91766.-A computer program has been developed which willcalculate the exact transmittance, reflectance, and absorptionof multiple layer inhomogeneous thin-film configurations. Thetechnique of the Characteristic Matrix ' is employed, adaptedto arbitrary inhomogeneous layers. The real and imaginarycomponents of the matrix elements of the inhomogeneouslayers are individually evaluated by numerical integration.The indices of refraction may be complex quantities whosereal and imaginary parts are functions of their distance fromthe interface. The refractive index is taken to be wavelengthindependent. Both polarizations are considered, and anyincident angle is permitted. The parameters relevant to thenumerical integration and error checking are discussed.(13 min.)

'M. Born and E. Wolf, Principles of Optics (The MacMillan Co., Inc.,New York, 1964), 2nd (revised) Ed., p. 55.

LOWER LOBBY AT 6:30-7:30 P.M.

Social Hour

PALLADIAN RooM AT 7:30 P.M.

Dinner

The Adolph Lomb Medal for 1966

will be presented to Dr. C. K. N. PATEL

After-dinner speaker: Professor H. W. THOMPSON, CBE, FRS,

St. John's College, Oxford, England

"Internationalism in Science"

FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA 555

FRIDAY, 18 MARCH 1966 REGENCY BALLROOM AT 9:00 A.M.

JOHN D. STRONG, Chairman

Invited Paper

FAl. Metallic Vapors Used as High Resolution Spectrographs. J. E. BLAMONT, Serviced'Aeronomnie, Centre National de la Recherche Scientifique, Verrieres-le-Buisson (Seine-et-Oise), France.-The optical resonance of metallic vapors provides a filter with an extremelynarrow optical bandwidth. Since the resonance wavelength can be modified by Zeeman splitting,Doppler effect, or multiple scattering, the system can be used as a spectrograph. Application ofrelativity redshift measurements on the sun to the observation of light by metals in the highatmosphere, the Lyman a on the sun, and also the determination of the temperature of neutralgases in the ionosphere will be described. (45 min.)

FRIDAY, 18 MARCH 1966 EMPIRE ROOM AT 10:00 A.M.

GILBERT N. PLASS, Chairman

Contributed Papers

Atmospheric Optics I

FB 11. Polynomial Representation of Absorption LineShapes. JOHN STRONG, Laboratory of Astrophysics &Physical Mlleteorology, The Johns Hopkins University, 34th& Charles Streets, Baltimore, Maryland 21218.-WhenX =Sw/

2 ry is greater than 7r we find that infrared absorptionline shapes, insofar as they derive from Lorentz absorptioncoefficient contours, can be represented to within a few per-cent, or less, by the following two integrable polynomials: Acore polynomial, for ZI <22: A,(Z) =1- (q/Z)Z2 and awing _ polynomial, for_ ,Z >2Z: At(Z) = (irZ2) (1/Z

2)

-(srpZ4) (1/Z4). Here Z2 =2x/ir and Z= (e-vo)/-y. Theconstants p and q are p= 1.23+0.42 Z-

2, q=0.107+0.06 8

Z-2.These polynomials give the equivalent width of single linesto about 3% or less; and integration of their products, fortwo overlapping lines, gives the correction for the blend,yielding equivalent widths precise to 2% (when the correctionis of the order of 20%). The areas in which this representa-tion has potential application will be discussed. (13 min.)

FB12. Bands of Carbon Dioxide at 4.3 ta.* K. NARAHARIRAO AND RALPH OBERLY, Department of Physics, The Ohio

State University, 174 West 18th Avenue, Columbus, Ohio.-In connection with the absorption and emission studies pur-sued at Ohio State employing high resolution infraredspectrographs, it became necessary to have a complete mapof the bands of carbon dioxide occurring in the region of4.3 p. An analysis of all the carbon dioxide bands occurring inthis region revealed many interesting details with respect tosome of the energy levels of the carbon dioxide molecule.The analysis of the bands was facilitated by the use of thetechnique of Loomis-Wood type diagrams employed exten-sively by Scott and Rao'; usefulness of this technique inhigh resolution infrared research will be elaborated. Theinterest in this problem will be discussed in relation to themolecular structure of carbon dioxide as well as the currentlaser emission studies undertaken in the infrared. (13 min.)

* Work supported in part by the U. S. Air Force, Cambridge ResearchLaboratories, Office of Aerospace Research, through contracts with TheOhio State University Research Foundation.'J. F. Scott and K. Narahari Rao (to be published).

FB13. Calculations of Spectral Absorption for the 9.4-and 1OA4-9 Bands of CO 2 . L. D. GRAY, Jet PropulsionLaboratory, Pasadena, California.-The absorption of the

9.4- and 10.4 -p bands depends strongly upon the temperaturebecause the lower vibrational states of these transitions arenot the ground state. This temperature dependence makesthese bands particularly useful for studying the temperaturedistribution in a planetary atmosphere as a function of height.Calculations of spectral absorption are compared with homog-eneous path measurements obtained in the laboratory fortemperatures ranging from 296' to 555'K. The randomElsasser band model was used and 14 vibrational transitionswere included in the computation. Good agreement with ex-perimental observations is obtained using a nitrogen-broad-ened half-width of 0.07 cm' and integrated intensities of 0.016and 0.030 cm 2 atmn' for the 10.4- and 9 .4-,u bands at 300'K(13 min.)

FB14. Absorption by Overlapping Infrared Bands of NMOand CO.t C. E. HATHAWAY, GARY M. HoOVER, AND DUDLEYWILLIAMS, Kansas State University, Manhattan, Kansas.-Burch, Howard, and Williams' have demonstrated that inthe case of the CO 2 and H.0 vapor absorption bands in the37 00-cm-' region the spectral transmittance of a mixture asmeasured with broad spectral slits is, within certain rangesof absorber concentration and total pressure, equal to theproduct of the transmittances of CO2 and H20 vapor meas-ured separately at corresponding values of absorber con-centration and total pressure. The present work was under-taken with the view of establishing the limitations of similarrelations for N20 and CO, both of which exhibit a "regular"line spacing in the 2200-cm' region in contrast to the"regular" and "nearly random" line spacings characteristicof CO2 and D20, respectively. The data obtained establishlimitations to the application of the product-of-transmittancerelations for CO and N20. The present experimental resultswill be compared with calculations of transmittance of over-lapping bands published recently by Gray and McClatchey.2

(13 min.)t Work supported in part by U. S. Air Force Cambridge Research Labora-tories, Office of Aerospace Research.

D. E. Burch, 3. N. Howard, and D. Williams, J. Opt. Soc. Am. 46, 452(1956).'L. D. Gray and R. A. McClatchey, Appl. Opt. 4, 1924 (1965).

FB15. The Use of a CW Molecular Laser to Probe LineWidths and Strengths.* T. K. MCCUBBIN, JR., AND RONALDDARONE, Physics Dept., The Pennsylvania State University,

556 FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA

University Park, Pennsylvania.-Nitrogen pumped molecularlasers developed by Patel provide a monochromatic source ofradiation very nearly coincident in frequency with the centersof the vibration-rotational absorption lines resulting from thetransitions for which the laser oscillations take place. Thelaser radiation can therefore be used to measure the trueor infinite resolution absorption coefficient at the line centers.We have measured the absorption of Nz-CO2 laser radiationas a function of foreign and self broadening gas pressure forseveral lines in the 10.4-t CO 2 band. Line and band strengthsand collision broadened widths are determined from themeasurements. (10 min.)

* This research received support from the Air Force Cambridge ResearchCenter, Office of Aerospace Research.

FB16. Temperatures in the Upper Atmosphere of Venus,As Indicated by the Infrared CO 2 Bands. PHILIP L.HANST, NASA Electronics Research Center, Cambridge,AMIassachusetts 02139.-The appearance of the infrared emis-sion spectrum of Venus is considered with regard to (1) theemissivity of the clouds of Venus, (2) the temperature ofthe atmosphere in the vicinity of the clouds, and (3) thetemperature profiles in the atmosphere above the clouds.Computations are made of the emission and absorption inthe 10.4-,k band of CO2 under a variety of assumptions ofemissivity and temperature. The infrared emission spectrumrequires the emissivity of the clouds to be at least as highas 0.65, and the temperature of the clouds to be less than2500K. The atmospheric temperature most likely decreaseswith increasing altitude in the vicinity of the clouds. Thespectrum also indicates an absence of temperature inversions

FRIDAY, 18 MARCH 1966

and associated warm zones in the upper atmosphere, unlessthey are at extremely high altitudes. (13 min.)

FB17. Computation of Band Absorption with Correctionfor Overlapping. HAJIME SAKAI, Air Force Cambridge Re-search Laboratories (OAR), L G Hanscom Field, Bedford,Massachusetts 01731.-The method for computing the in-tegrated absorptance due to two overlapping absorption linesis extended to the calculation of the band absorption. Theaccuracy of the computation is discussed using the "Elsasser"band model, and the actual absorption band in 3800 to 3900cm-' constructed using the H20 2 .7 -M band theoreticallycalculated by Benedict et al.' Further extension of thiscomputation has been applied to the whole spectral range ofthe 2.7-1 H20 band and the results will be presented.(10 min.)

'IH. Sakai and F. R. Stauffer, J. Opt. Soc. Am. 54, 759 (1964).2 W. S. Benedict et al., NBS Memograph 71.

FB18. Absorption by HO in the 340-aL Window. DARRELLE. BURCH AND ELIAS REISMAN, Aeronutronic Division ofPhilco Corporation, Room 77, Weapon Systems Building,Ford Road, Newport Beach, California.-Quantitative meas-urements of the absorption by H20 near the 340 -je windowhave been made. Samples of H20 and H20+N2 were con-tained in a multiple-pass absorption cell in which path lengthsgreater than 400 m were attained. Absorption spectra werecomputed from interferograms obtained by using a Michelsoninterferometer employing a Mylar beam splitter. The resultsare discussed and compared with some theoretical predictions.-(13 min.)

PALLADIAN ROOM AT 10:00 A.M.

WILLIAM E. BitRING, Chairman

Contributed Papers

Instrumentation II

FC11. Accurate Method for Determining PhotometricLinearity. H. E. BENNETT, Michelson Laboratory, ChinaLake, California 93557.-Accurate photometric measurementsdepend on the linearity of the detection system, i.e., whetherthe output is strictly proportional to the incident light flux.The usual method for checking linearity is to introduce filtersof known absorption into the optical path. Unfortunately,the many possible errors inherent in this method make itdifficult to determine linearity in this way to better than 1%.By using three polarizers in series, keeping the axes of theouter two parallel and rotating the middle polarizer, it ispossible to eliminate most of these sources of error. Ifpolarizers of the highest quality are used, photometric linear-ity may be determined to considerably better than 0.1%o. Anerror analysis and some experimental results obtained usingsuch a system will be given. (13 min.)

FC12. Optical Development of a Dual-Field StabilizedTelescopic Sight. M. GAWARTIN AND I. C. SANDBACK,Hughes Aircraft Company, Culver City, California.-Opticalinstrumentation for a fire-control system requiring twomodes of operation, a low-power acquisition mode and ahigh-power tracking mode, has been extended to an airborneapplication. The optical development of a dual-power sta-bilized telescopic sight is discussed, along with design trade-offs leading to a choice for the model configuration. (13 min.)

FC13. Generation of Two-dimensional Optical SpatialAuto- and Cross-Correlation Functions for Sonar Dis-plays. HANS J. WILDE (introduced by E. L. GREEN), U. S.Navy Underwater Sound Laboratory, Fort Trumbull, NewLondon, Connecticut.-Two dimensional auto- and cross-correlograms have been generated with a Mayer-Eppler'type geometric-optical correlator of our design. Principlesof operation and factors affecting performance are discussed.Correlograms of small objects are described. Possible appli-cations to statistical analysis of sonar data are indicated.Two dimensional correlograms of PPI moving target displaysare presented. (13 min.)

1Nachrichtentechnische Fachberichte Beihefte der NTZ (1956), Band 3,S. 40.

FC14. Out-of-Focus Operation of the Pritchard Photom-eter. DOMINA EBERLE SPENCER, University of Connecticut,Storrs, Coun., AND ROBERT E. LEvIN, Sylvania LightingProducts Inc., 100 Endicott St., Danvers, Mass.-Previouspapers1 have studied the out-of-focus operation of photom-eters employing thin lenses and thick lenses. The theoreticalanalysis has hitherto been applied to a number of hypotheticalinstruments and to one commercially available photometer.The present paper applies the theory presented earlier to thePritchard photometer. Circumstances under which the cali-bration factor is independent of focal position are determined.

FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA 557

Definite information on the field of view of the Pritchard andon the weighting function within the field of view is givenfor various focal positions. A number of idiosyncraciespeculiar to this instrument are also discussed. (13 min.).D. E. Spencer, J. Opt. Soc. Am. 55, 396 (1965).2 D. E. Spencer and R. E. Levin, "On the Significance of PhotometricMeasurements," paper presented at the 1965 National Technical Confer-ence of the Illuminating Engineering Society, New York, N. Y., 29August-2 September.ID. E. Spencer and R. E. Levin, J. Opt. Soc. Am. 55, 1569A (1965).

FC15. Internal Reflection at Near-Critical Angles; TheDifferential Photogoniometer. R. S. LEVITT (introduced byM. G. DREYFUS) AND N. J. HARRICK, Philips Laboratories,Briarcliff Manor, New York.-When light is incident on adielectric interface from the higher index side at an angleOi just less than the critical angle Oc, the reflected intensityis a rapidly varying monotonic function of (Oc-0i). Measure-ment of the internally reflected intensity, therefore, permitsdetection of minute angular changes. We find that for theTM polarized collimated light of a He-Ne laser at 6328 Athe air-interface reflectivity in lucite (n=1.49) changes bylXl0'/arcsec at 70% reflection as expected. A novel two-beam, differential internal reflection technique makes possibledetection of changes in reflected intensity of 1 part in 10$using cw light, silicon solar cell detectors, and dc amplifica-tion; use of chopped light with narrow-band ac amplificationpermits detection of 1 part in 105, which should correspond toa 10' arcsec (10' rad) change in angle. Application of thisphotogoniometric technique to precision tracking of lightsources will be discussed. (10 min.)

FC16. Photocurrent Multiplication in Cadmium Sulfideby Simultaneous Spot Illumination.* RAYMOND P. BOR-KOWSKI, (introduced by FRANCE B. BERGER), ARYEH H.SAMUEL, WILLIAM M. BLOCK, IRVING BLEICHER, AND DANIELGRAFSTEIN, General Precision Inc., Aerospace Group Re-search Center, 1225 McBride Avenue, Little Falls, NewJersey.-The current multiplication effect is the enhancementof the photocurrent which occurs when directly oppositepoints on the surfaces of a sandwich-type photocell, consistingof either undoped single-crystal or doped polycrystalline CdS,are simultaneously irradiated by spots of light. Values as highas 100 for the enhancement factor, which is the ratio of thephotocurrent produced under simultaneous illumination to thearithmetic sum of the photocurrents produced by each spotseparately, have been observed. The effect is absent whenboth spots illuminate the same surface or different points onopposite surfaces, or when both surfaces are entirely illumi-nated. The optimum effect is observed when: (1) the wave-length combination utilized is 6550-5180 A; (2) an inter-mediate intensity of one light source is used, while maintainingthe intensity of the other source constant; (3) low electricfields, approximately 100 V/cm or less are applied; (4) lightspot areas of approximately 2Xl0O'cm5 are used; (5) bothlight spots are in coincidence. The effect is independent of theangle of incidence of either of the two beams. A model based

FRIDAY, 18 MARCH 1966

on the diffusion of charge carriers explains the results in partbut presently no complete theoretical analysis has beenachieved. (13 min.)

I Work supported in part under NASA Contract Nas 12-8.

FC17. Digital Control Unit for a Spectrophotometer.A. S. FILLER AND S. LITWIN, University of Pennsylvania,Philadelphia, Pennsylvania.-A digital control unit has beendeveloped, primarily for a spectrophotometer used to measureweak emission spectra. Detection is by photon counting, sothat the output is digital and is fed to a scaler. Two otherscalers record elapsed time, and photon counts from a beammonitor (e.g. from the exciting radiation in Raman spec-troscopy). Grating motion is discontinuous and is effected bya Slo-Syn motor, actuated by a programmed number ofpulses. Switches are used to allow programming of thefollowing functions: wavelength calibration, dark and back-ground measurements, polarization studies, and external fieldeffects. Solenoids are used to set up the instrument for thesefunctions. Various parameters, such as amount of gratingrotation, maximum number of counts, maximum time permeasurement, are programmed by inserting plugs into a jackpanel. Filters may be inserted, under program control, toextend the dynamic range of the measurements. The scalerreadings are recorded on punched tape, and a computer printsthe results and plots the spectra. Some of the circuits arebrought to a plug panel, so that the control unit may be usedwith several instruments. Typical spectra will be shown,to illustrate the operation of the unit. (13 min.)

FC18. An Automatic Ellipsometer Employing Modula-tion Technique. HIROSHI TAKASAKI, The National Bureauof Standards, Washington, D. C. 20234.-A method to auto-matize both polarizer and analyzer settings in all four zonesof an ellipsometer is described. The optical arrangement ofthe basic instrument is the most common type; i.e., polarizer,sample, quarter-wave plate and analyzer. ADP cells aremounted on the polarizer and analyzer and alternating volt-age is applied to the cells to modulate the state of polariza-tion. The transmitted light intensity includes two modulatedsignals corresponding to the modulations applied to the ADPcells. An analysis shows that extinguishing both of themodulated signals is equivalent to adjusting polarizer andanalyzer for extinction. The two signals are separated asfollows: Modulate the ADP unit 1 (2) with sinwt (coswt)phase. The two signals are amplified together and fed to twoservo-motors. The field winding of one of the servo-motorswhich expected to pick up sinmt (cosawt) signal component isexcited with cosact (sint). Because the two phase-servo-motor is sensitive only to signal component with 90° phasedifference relative to field excitation, the motors work asphase sensitive detectors. The outputs of the motors, are fedback to their corresponding optical compensations, thuspolarizer and analyzer are adjusted automatically to obtainthe extinction condition. (13 min.)

DIPLOMAT ROOM AT 10:00 A.M.

DAVID L. MACADAM, Chairman

Contributed Papers

Color

FD11. Terms, Definitions, and Symbols in Reflectome-try. DEANE B. JUDD, National Bureau of Standards, Wash-ington, D. C. 20234.-Existing reflectometers collect formeasurement either all of the reflected flux, that within a

solid angle comprising a group of directions less than all,or that substantially confined to a single direction. Theseangular conditions of collection are denoted: hemispherical,conical, or directional, respectively; and the same terms are

558 FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA

used for the angular conditions of incidence. The ratio ofthe flux collected to that incident is called reflectance, p, inaccord with existing terminology, and the angular conditionsare indicated by stating first the type of incidence, then thetype of collection. Thus, we have nine types of reflectancesuch as hemispherical-directional, conical-hemispherical, bi-hemispherical, or bi-directional. The ratio of the flux col-lected to that which would be collected from the perfectdiffuser identically irradiated receives either the new name,reflectance factor, if the collection is hemispherical or coni-cal, or the existing name, radiance factor p, if the collectionis directional. This extension of existing terminology wasdeveloped at the National Bureau of Standards to facilitatediscussion of interrelations among the quantities measured byvarious reflectometers, and hopefully this extension, or somerevision of it, will merit formal adoption. (13 min.)

FD12. A History of Photoelectric Tristimulus Colorime-try. RICHARD S. HUNTER, Hunter Associates Laboratory,Inc., 9529 Lee Highway, Fairfax, Virginia.-In 1915, Ivesdescribed a thermopile tristimulus calorimeter in which heprojected a spectrum through a series of carefully cut tem-plates to obtain the required tristimulus functions. Twymanand Perry showed in 1928 that an instrument would yielddirect tristimulus measurements of color if it possessedsource-filter-photocell combinations spectrally to the re-sponse functions of the standard observer. It was not until1938 that Perry described an actual instrument for photo-electric tristimulus colorimetry. He called his device theBlancometer because of its special suitability for white andnear-white samples. Guild described the experimental modelof a tristimulus colorimeter in 1934, and Winch and Palmer,Dresler and Fruhling, and Barnes, described devices for thesame purpose between 1934 and 1942. Gibson and Van denAkker, in the same period, reviewed some of the problemsof obtaining source-filter-photocell combinations having spec-tral equivalence to the standard observer. Hunter's first tri-stimulus measurements were made with the MultipurposeReflectometer developed in 1937. In 1942, NBS CircularC429 described the variety of useful color measurementswhich are possible with this and other similar instruments.C429 studied the errors of the method in some detail. In 1948,the writer developed a color difference meter in which Ohm'slaw analog circuits convert photoelectric tristimulus signalsdirectly to values of color in the scales of a uniform-colorsolid. The high precision obtainable with tristimulus coi-orimetry and the convenience of direct readings on theuniform color scales has led to the widespread employmentof this method for the measurement of small color differ-ences. (13 min.)

FD13. Fifty Years of the Spectrophotometer: Its His-tory, Both Known and Needed. LESTER CLARK LEwis,*Apt. 310, 1661 Crescent Place, NW, Washington, D. C.20009.-Five historical charts have been developed, whichwill be used to highlight the history, and provoke discussion.Well-established facts are the late beginning of spectropho-tometry with Vierordt in 1869; its limited use (because itsphotometry had to be visual) until about 1925; its basic de-velopment with Gibson and colleagues at the National Bu-reau of Standards; and its rapid development after the Hardyautomatic curve-drawing instrument with photocell detectorwas produced commercially by the General Electric Co. in1935. That instrument, coming soon after the CIE adoptedan international standard observer for color in 1931, madepossible sufficiently precise and rapid specifications of "color"for many products. Many later instruments, with new de-tectors especially, made possible the rapid and certain iden-tification of chemical (especially organic) compounds bytheir spectra in the range from ultraviolet through infrared.

Hundreds of thousands of spectrophotometers in use todaybuilt by several manufacturers at home and abroad, are usedfor diverse determinations far beyond the basic reflectance,transmittance, and emittance measurements. The developmentof both the instruments and their diversified uses need to bebetter understood-for the period of the thirties and after1946. (13 min.)* Formerly of U. S. National Museum, Smithsonian Institution-wheremost of this work was done.

FD14. Implications of a Central Foveal PhotochromaticInterval. BEVERLY M. HILLMANN, Radio Corporation ofAmerica, Burlington, lMassachnsetts.-The so-called photo-chromatic interval in human visual response is the observeddifference between the luminous intensity required for thresh-old detection of light per se, and that level required for theperception of color. In peripheral retinal stimulation, thephotochromatic interval has been attributed to the separateresponses of two types of receptor elements. The duplicitytheory of vision implies the functional division of the rodsand the cones. Rods are thereby assumed to mediate mono-chromatic vision at low light levels, while the cones mediateheterochromatic vision at higher light levels, although thereis considerable, if not complete overlap in the spectral regionto which each is sensitive. Further, it has been noted histo-logically that the central foveal area is essentially rod-free.A psychophysical study of the area-intensity relationship atthreshold for centrally located targets of spectrally restrictedwavelengths is described together with other data to indicatethe existence of a central foveal photochromatic interval. Theproblem of accounting for monochromatic vision in an os-tensibly homogeneous cone population is discussed in thelight of several theories of color vision. (12 min.)

FD15. Chromatic Changes Induced by Changes in Chro-maticity of Backgrounds of Constant Lightness. HIROSEITAKASAKI, National Bureau of Standards, Washington, D. C.20234.-The study of the contrast effect on lightness hasbeen extended to chromaticness. Two series of color sampleswere prepared so that in the dominator-modulator systemproposed by Judd only one of the three fundamental re-sponses varied. Observation was made in such a way as todetermine the range of color match of two half-inch squaretest samples at the center of two five- by eight-inch chro-matic backgrounds. The crispening effect, or the enhancementof the contrast effect when the test area is like the back-ground, was found in each of the chromatic responses, greenand violet, as in lightness. The same form of empirical for-mula obtained from the former study can be applied fairlysuccessfully to the observations of each of the five observers,each with a different set of constants. Compared with thecontrast effect in lightness, the constant for general inductionis a little less for the V and G fundamental responses. Theconstant for amount of crispening differs drastically for eachresponse; about one fourth for V and about one tenth for Gcompared to the value for lightness. On the other hand, cris-pening for the G response is about ten times sharper thanfor lightness. (13 min.)

FD1G. Temporal Factor in Color-Difference Judgments.HILTON WRIGHT, Division of Applied Physics, National Re-search Council, Ottawa, Canada.-An experiment is de-scribed which illustrates how color-difference judgments areinfluenced by the length of time of observations. Eight pairsof colors were used which differed from each other in hue,but the members in each pair were of approximately thesame hue. One observer viewed the color pairs through ashutter mechanism providing exposure times ranging from33 msec to unlimited time. Observed sizes of the color dif-ferences were determined by the method of ratio compari-sons. The observed color differences changed systematically

FIFTIETH ANNIVERSARY MEETING

in magnitude as the exposure times were increased from 33to 500 msec but there was no change in the observations for1-sec exposures or longer. For the short exposure times colordifferences of the blue and violet hues were observed as beinglarger than for those of the other hues. (10 min.)

FD17. Theoretical Limits of Metamerism. EUGENE AL-LEN, American Cyanamid Company, Bound Brook, NewJersey 08805.-The phenomenon of metamerism of objectcolors can be represented by a pair of points in a six-dimensional space having as coordinates the tristimulus valuesfor each of two viewing conditions: X1 , Yi, Zs, X2 , Y2, Z2 .The two points have the same values for Xa, Y., and Z., anddiffer in Xb, Yt, and Z,, where a=1 and b=2 (case 1) ora=2 and b=l (case 2). The space within which pairs ofpoints may fall, which is the same for case 1 and case 2,will be called M space. This space can be shown to be finite,convex, and smaller in hypervolume than the total six-spacedefined by the two sets of tristimulus values. The nearer toeach other the two viewing conditions are, the smaller is thecorresponding M space; if the two viewing conditions areidentical, M space becomes a three-space of zero hyper-volume. The limits of M space, which can be calculated bylinear algebraic techniques, represent limiting metamericmatches for any set of Xa, Y., Z.. The MacAdam limits forobject colors are a special case of the limits of M space,and form part of its boundary. The spectrophotometric curveswhich produce colors at the boundaries of M space can beshown to have values of either 0 or 1 throughout the spec-trum, with no more than a certain number of transitions.-(13 min.)

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* OPTICAL SOCIETY OF AMERICA 559

FD18. Use of an Auxiliary Sphere with a Spectroreflect-ometer to Obtain Absolute Reflectance. DAVID G. GOEBEL(introduced by HARRY K. HAMMOND III), B. PATRICKCALDWELL, AND HARRY K. HAMMOND III, Photometry &Colorimetry Section, National Bureau of Standards, Wash-ington, D. C. 20234.-An auxiliary sphere with a double-beam integrating-sphere spectrophotometer permits measure-ments to be made on an absolute basis." 2 Requirements are:(1) Sphere coating must be uniform, highly-reflecting andhighly-diffusing. (2) Coating reflectance, interior-surfacearea of sphere, and area of entrance port must be known.Hemispheres were coated with smoked MgO, sprayed MgO,or BaSO4 powder in water or alcohol, and pressed-dry pow-der of these materials. Pressed coatings are superior be-cause: (1) they can be made thick without flaking. (2)Sphere interior surface is predetermined to high accuracy byscooping out excess powder with a precisely-positioned, semi-circular plastic blade. Specimens of smoked MgO and ofpressed-reagent-grade powder of both MgO and BaSO4 havebeen measured and found to have 60-hemispherical absolutereflectances at 0.55 gm close to 0.99. Standard deviations for20 or more specimens of each type were less than 0.003.Pressed-powder specimens of highest purity MgO and BaSO4were determined to have absolute reflectances above 0.98 at0.45 um and above 0.99 from 0.55 to 1.08 um. The near-infra-red reflectance of pressed-MgO specimens is higher thanthat for 1-mm-thick smoked-MgO specimens by about 1%at 0.8 Am and 1.5% at 1.08 Am. (13 min.)'J. A. Van den Akker, L. R. Dearth, and W. M. Shillcox, J. Opt. Soc.Am. 46, 378A (1956).2 Proposed Method for Absolute Calibration of Reflectance Standards,ASTM Book of Standards (1966). Part 30.

REGENCY BALLROOM AT 2:00 P.M.

JOHN A. SANDERSON, Chairman

Invited Paper

FEL. Infrared Detectors: Past, Present, Future. HENRY LEVINSTEIN, Department of Physics,Syracuse University, Syracuse, New York.-Infrared detector development proceeds throughthree stages: the search for materials which show some promise as possible detectors, the im-provement of these materials to the point where they are sufficiently responsive to make detectorconstruction feasible, and finally the construction of sophisticated detectors. Virtually all mate-rials which show responsivity are now in, or approaching the final stage, thus providing de-tectors in virtually every region of the IR spectrum from 1 p to beyond 1000 A. These materialsinclude PbS, PbSe, InAs, InSb, and impurity-activated germanium. In the past most emphasisin detector development has been placed on spectral response and magnitude of detectivity. Thereis an increasing demand for the optimization of other parameters which may be required forparticular applications. These include less stringent cooling requirements, shorter time constants,peak response at particular wavelengths, special sensitive element configurations. While con-siderable progress is being made in the control of some of these parameters, further advancesrequire a better understanding of materials now available as well as extensive effort in thedevelopment of new materials. Further developments are closely tied to the level of support aswell as an awareness of future requirements. (30 min.)

FRIDAY, 18 MARCH 1966 EMPIRE ROOM AT 2:45 P.M.

LouIs F. DRUMMETER, JR., Chairman

Contributed Papers

Atmospheric Optics II

FF11. Optical Communication-Atmospheric Effects.BANKIM R. SHAH (introduced by T. J. HARRIs), Inter-national Business Machines Corporation, Poughkeepsie, New

York 12602.-The theoretical possibilties of laser communi-cation are truly remarkable. In practice, however, practicalconsiderations limit the laser communication to less exotic

560 FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA

possibilities. Undoubtedly, atmospheric effects constitute amajor consideration. The aerosol particles in the atmosphereact as discrete centers of disturbance for the laser beam.The principal effect of these particles is scattering ratherthan absorption. An open link on the Earth would certainlybe subject to interruptions due to inclement weather. Otherimportant mechanisms for the weakening of a laser beamare: small angle spreading, beam bending, and low-frequencymodulation. These effects are examined in detail to providea meaningful composite picture. The aerosol loss is deter-mined from Mie scattering theory for aerosol radii from 0.1to 20 A using typical aerosol densities. The transmission rangefor 0.84, 3.5, and 8.7 u wavelength is compared With the visualrange to measure the effectiveness of different wavelengthlasers for optical links. In addition, consideration has beengiven to density discontinuities, variations of temperature,wind, and turbulence structure of the atmosphere. A numberof experimental observations are reported to reinforce theconcise over-all picture. Finally, the all-important question ofsystem availability and error rate is examined in the lightof these findings. (13 min.)

FF12. A Model of Propagation through a TurbulentAtmosphere for Optical Communication. ROBERT S. rxEN-NEDY AND ESTIL V. HOVERSTEN, Massachusetts Institute ofTechnology, Cambridge, Massachusetts.-The basic limita-tions that atmospheric turbulence impose upon the reliabilityof optical communication systems cannot be determined with-out a complete statistical model for the influence of the tur-bulence. The primary requirement of the model is that itspecify the functional form of all the random quantities ofinterest; whether or not it predicts the numerical values ofthe constants in these forms is of secondary importance. Areview of atmospheric characteristics suggests that a rela-tively simple model based upon generalized geometric opticsshould provide a more useful analytical description of therelevant statistical phenomena than do the existing models.The model does not suffer the severe range limitations asso-ciated with most models deduced from geometrical consid-erations. Although it was not developed for that purpose, theresulting model yields the correct numerical values for manyquantities of interest. It has also suggested some experimentswhich should provide further insight into the range of itsvalidity. (13 min.)

FF13. A Point Image Focusing Monitor Without Mov-ing Parts. JURGEN R. MEYER-ARENDT, Indiana State Uni-versity, Terre Haute, Indiana 47809.-The scintillation ofstars is a complex phenomenon that has at least three con-tributions: (a) pure intensity fluctuations, (b) sidewise shiftof the point image, called image motion or dancing, and (c)defocusing. (b) and (c) are due mainly to parcels of air ofdifferent refractive index moving by close to the observingtelescope.1 (a) and (b) can be measured easily. In order toget in addition a quantitative measure of (c), a relativelysimple system has been built, based in part on an idea byEvans.2 It consists of a two-slit aperture screen, with theslits located in opposite quadrants, placed in front or somedistance behind the telescope objective, and a cylinder lensmounted at a given, fixed distance in front of the primefocus. Defocusing is then seen, and measured, by the relativeshift of the two line images that are formed of the star orother point object. (10 min.)XJ. R. Meyer-Arendt and C. B. Emmanuel, Optical Scintillation. NBSTech. Note 225 (1965).2J. W. Evans, Appl. Opt. 3, 1387 (1964).

FF14. Use of Mach-Zehnder Interferometer to StudyControlled Air Turbulence.l S. A. COLLINS, JR., AND M.MONROE, Antenna Laboratory, The Ohio State University.1320 Kinnear Road, Columbus, Ohio 43212.-Atmospheric

refractive index fluctuations are instrumental in determiningtwinkling of stars and breakup of long distance laser beams.This talk describes an experiment on controlled air turbu-lence refractive index fluctuations in a wind tunnel. A doublebeam technique equivalent to the use of a Mach-Zehnderinterferometer for studying turbulent air refractive indexfluctuations is described. The experiment, performed in asubsonic wind tunnel, yields results in agreement with ana-lytic predictions based on recent theories of light turbulence,and on empirical data for wind tunnel turbulence. (13 min.)

* Work supported in part by Contract number AF 33(615)-2287 betweenAir Force Avionics Laboratory, Research and Technology Division, Wright-Patterson Air Force Base, Ohio and The Ohio State University ResearchFoundation.

FF15. Attenuation of Laser Beams. R. M. LANGER, TheJ. R. M. Bege Company, Arlington, Massachusetts.-Expo-nential attenuation is supposedly an attribute of monochro-matic light. Beer originally recognized that in frequencydependent media attenuation of nonmonochromatic beamscould be nonexponential. Actually beams of such narrowspectral width as to be monochromatic for most practicalpurposes often fail to show exponential absorption. Laserbeams are usually described as monochromatic, yet becauseof the complexity of atmospheric absorption spectra, eventhey may show appreciable deviations from the simple ex-ponential attenuation law of Beer. Detailed examination ofabsorption in familiar gases shows many regions where at-tenuation coefficients vary not linearly but exponentially withfrequency. It is moreover often convenient to assign a Gaus-sian spectral intensity distribution to a laser or other beam.The transmission integral then covers a variety of interestingcircumstances. The empirical formula of Elder and Strong,for example, appears under slight revision as a special casefor attenuators which remove about half of the incident beamenergy. A similar formula should apply to other absorbersin addition to those (water vapour and carbon dioxide)which have been reported so far. Different simple expres-sions apply for other special situations. (13 min.)

FF16. Determination of Weak Line Intensities fromAtmospheric Infrared Spectra. HANS-JiYRGEN BOLLE, Me-teorological Institute of the University of Munich, 8000Munich 13, Ainalienstrasse 52/III, Gerinany.-The intensityof weak water vapor lines in the 8-20 1c region has been de-duced from atmospheric emission spectra by comparison ofmeasurements with monochromatic wave number by wavenumber calculations. For medium strong lines the line inten-sities are in good agreement with theoretical data, while forweak lines approximately 30%o larger values were obtained.The intensity of carbon dioxide lines in the 961 cm' (100-001) band was deduced from the Atlas of Migeotte, Neven,and Swenson by a similar procedure. The resulting bandintensity of 0.019 atmnf cm-2 is in agreement with the valuesof other authors. The influence of the superimposed con-tinuum on the evaluation is discussed. (13 min.)

FF17. Spectral Emissivity Measurements of Water Va-por at 27500 K Between 1 and 25 Iti. C. C. FERRISO t AND

C. B. LUDWIG, Space Science Laboratory, General DynamicslConvair, San Diego, California.-Infrared spectral emissivitymeasurements of water vapor at 27509K were obtained. Thesignificance of these measurements lies in the fact that noprevious spectral data exist at this high temperature andthat the water emission may be a major contributor to ra-diant energy transfer in various systems. The heated H20gas was produced in a small rocket burner with an area ratio1.5:1, using gaseous H2 and 02 as propellants. The measure-ments were made at the nozzle exit of the rocket where thecomposition, total pressure, and temperature could be defined.Doubling the optical path showed that except for the pure

FIFTIETH ANNIVERSARY MEETING

rotational band the gas was thin. At 2750'K it was ob-served that the vibration-rotation bands are heavily over-lapped which makes the determination of the integrated in-tensities a of the individual bands uncertain. The value afor the fundamental 6.3-, band is 350±15% (cm-' per cmat STP) which is about 40% higher than the room-tempera-ture value. For the fundamental 2 .7 -, band, a value of 230±15% (cm-' per cm at STP) was obtained, which is inagreement with recent values obtained at room temperature.Values for the integrated intensities of the 1.87-, 1.34-, and l.l-sacombination bands have also been obtained at these tem-peratures and these results will be discussed. (13 min.)

* Work supported by the Advanced Research Projects Agency, through theOffice of Naval Research.t Deceased.

FF18. Time-Resolved Spectra of Hypervelocity Projec-tiles Obtained with a Large Aperture Slitless Spectro-graph. I. D. Liu, GM Defense Research Laboratories, P.O.

FRIDAY, 18 MARCH 1966

* OPTICAL SOCIETY OF AMERICA 561

Box T, Santa Barbara, California.-In a previous abstract'the spectra associated with hypervelocity projectiles obtainedwith a large aperture slitless spectrograph have been pre-sented. When used in conjunction with an image convertercamera, time-resolved spectra showing clear spatial resolu-tion concerning the spectral features originated from theshock layer, the near and far wake flow have also beenobtained. For nonablating models, only emission from theshock cap can be observed. For ablating models at elevatedspeeds and range pressures, such molecular band systems asC2, CH, and CN for models containing hydrocarbons andCu2, CuF, CuO, BeO, and A10 for metallic models havebeen observed in the wake region of the flow. The feasibilityof using a high-gain image intensifier in cascade for thestudy of very far wake emission, as well as meteors andspace vehicles entering into the earth's atmosphere will bepresented. (13 min.)

1 I. D. Liu, J. Opt. Soc. Am. 55, 598A (1965).

PALLADIAN ROOM AT 2:45 P.M.

H. M. CROSSWHITE, Chairman

Contributed Papers

Instrumentation II

FGil. The Intervention of Energy in the Formation ofImages. VASco RONCHI, National Institute of Optics,Arcetri-Firenze, Italy.-The classification of images accord-ing to their nature has led us to take into account a deter-mining factor of their quality that until now had not beenconsidered, at least from a theoretical viewpoint. This factorconsists in the energy that is utilized by the receptor of theimages themselves. Until now the concept of optical imagehad been represented in mathematical terms by means of thegeometrical design of the rectilinear rays and with thedesign, also geometrical, of undulatory movements, and thelaws of images have been studied abstractly, without takinginto account the fact that the practical utilization of imagescan only be achieved through "revelation" by means of suit-able radiation revelators, such as the eye, photosensitiveemulsions, and photoelectric cells. The complete study of"experimental images," that is to say, not mathematical,should therefore take into account what is obtained fromtheir revelation. When the problem is set in these terms, theconclusion is at once reached that the result depends essen-tially on the quality and quantity of the energy that reachesthe revelator, and therefore the practical quality of anoptical system and of an instrument not only depends on itsshape and its geometrical characteristics, but also on howthe received energy is utilized. It is easy to recognize thatthis reasoning had already been widely demonstrated bynumerous experimental occurrences which, however, had beenleft to the arbitrariness of practical operators, and theory hadbecome completely disinterested in them. It is deemed thatinstrumental optics can draw a new possibility of progressif the argument is perceived also from a theoretical pointof view (13 min.)

FG12. High Resolution Vacuum Spectrometer withGolay Coded Grilles. HOWARD W. NEILL, U. S. NavalOrdnance Laboratory, Corona, California 91720.-The recentsuccess of Girard 2 in obtaining increased luminosity in grat-ing spectrometry has prompted a reexamination of theprinciples of multislit devices developed by Golay2 somefifteen years ago but which have not been generally exploited.

This paper describes the incorporation of such "grilles" in a4-m vacuum double-pass grating spectrometer recently com-pleted. The grilles are composed of 10 columns each of thebasic series, its complimentary series, and the reenteredseries of each. Modulation is obtained by mounting the en-trance grille on one tine of a driven tuning fork, the motionbeing perpendicular to the direction of dispersion. Initialresults indicate that the requirement for uniform illumina-tion at the entrance field is much less strict than for Girard'shyperbolic grilles. The present field limitations of 12 by 12mm are due to detector optics. The grilles are relatively easyto construct since standard techniques used in microcircuitryand photoetching may be employed. One mil thick stainlesssteel foil may be used with success for one-element steps(i.e., equivalent slitwidth) as narrow as 150 ti. Narrowersteps require a transparent substrate as used by Girard.Pertinent points as to grille design, construction, and align-ment will be discussed. (13 min.)

1 A. Girard, App. Opt. 2, 79 (1963).2 M. J. E. Golay, J. Opt. Soc. Am. 41, 468 (1951).

FG13. Computer Calibration of the Wavelength Drive ofa Prism Spectrometer. R. E. FRYER (introduced by D. K.BURGE), Michelson Laboratory, China Lake, California93557.-The Sellmeier equation has been slightly modified todescribe the drum position as a function of frequency for aLittrow-type prism spectrometer. A widely available IBMShare program in FORTRAN II can be quickly and easilyadapted to fit calibration data to this equation. The programprovides a least-squares estimate of the constants in theequation when two of the constants, the curve asymptotes,are moderately well established. This method was applied toa Perkin-Elmer model 99 double-pass spectrometer, andthe resulting standard deviation a between data points andcomputed points was only slightly larger than reading repeat-ability. The prisms used were SiO2, CaF2, NaCl, KBr, andCsBr. The maximum a obtained was 1.1 drum numbers forKBr in the 10- to 22-Ae range, which corresponds to a standarddeviation in wavelength of 0.015 A. The best fit was obtainedfor NaCl with a=0.25 drum numbers between 1.4 and 6p,.

562 FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA

Using the calculated dispersion constants, a second programprints a table of drum numbers versus wavelength and wave-number at intervals as small as the error in the fit willallow. This table is an accurate and convenient substitutefor the wavelength calibration graph. (13 min.)

FG14. A New Ruling Engine in Japan. YAHImo YAMADA,TATSUO HARADA, AND I(ENJI MORITA, Central Research Lab.,Hitachi, Ltd., Kokubunji, Tokyo, Japan.-A new ruling en-gine was constructed which is capable of producing grat-ings up to 250 mm in Width and 75 to 2500 grooves permillimeter in spacing. This engine is controlled interfero-metrically with a Michelson interferometer, in which amoving mirror is mounted on the blank carriage. A specialdevice was adopted in the floor construction to prevent thedisturbance of Japanese earthquakes after foundation meas-urements were made with a seismograph for three months.The engine is inserted in a machine-oil tub which keeps theblank carriage sliding in good lubrication. To get groovestraightness, the engine has a drum and steel belt mechanism.A device for the barometric pressure was adopted whichconsists of detector of the pressure and the calculationmechanism connected to the gear trains driving the mainscrew. A grating which is ruled by this engine shows goodquality as tested by Twyman-Green interferometer and thespectra. (13 min.)

FG15. Polarization Properties of a Perkin-Elmer Model21 Spectrometer.* WILLIAMu L. WOLFE, WAYNE L. FLOWERS,GROVER W. TRYTTEN, Institute of Science and Technology,The University of Mlichigan, Ann Arbor, Michigan 48107.-In order to improve our understanding of radiation processespertinent to remote sensing problems, we are preparing tomeasure the reflectance and transmittance of natural mate-rials. A detailed understanding of the radiation processesrequires a knowledge of the angular dependence of reflect-ance with wavelength and polarization angle as parameters.The assumptions that objects are Lambertian and that polari-zation is not significant must be discarded in view of existingevidence. In fact, the distribution of polarized light in bistatic(bidirectional) and integrated (directional) reflection is ofgreat importance. One of the instruments to be used in thesemeasurements is the Perkin-Elmer model 21G spectrometer.A theoretical and experimental analysis of the instrument'spolarization effects has been performed to calibrate the spec-trometer and to understand the relative contribution of thedifferent components to the over-all instrument polarization(13 min.)

I This effort is being supported by the Avionics Laboratory at Wright-Patterson Air Force Base.

FRIDAY, 18 MARCH 1966

FG16. A Compact Polarizer for the Infrared. ROBERT G.GREENLER, IKENNETH W. ADOLPH, AND GEORGE H. EMMONS,University of Wisconsin-Milwaukee, Milwaukee, Wisconsin53211.-An infrared polarizer is constructed from unsup-ported selenium films which are pleated in such a way thatincident radiation strikes each facet of the film at Brewster'sangle. The films are thin enough to produce no appreciablelateral shift of the transmitted radiation and the pleatedconfiguration permits the construction of a complete polarizerwith a thickness of about 2 cm. A polarizer consisting of astack of four pleated films shows a degree of polarization'varying between 84% and 96% in the 400 to 4000 cm' spec-tral region when measured in the f/8 beam of an infraredspectrometer. Over this same spectral region the trans-mittance for the desired orientation of plane polarized lightvaries between 65% and 80%c. (12 min.)

'The degree of polarization reported here is defined as (Trnas-Trin)/(Tznns+Tzn in).

FG17. Operation of a Two Channel Interferometer forFourier Spectroscopy. ERNEST V. LOEWENSTEIN, OpticalPhysics Laboratory, AFCRL (CRO) L. G. Hanscom Field,Bedford, Mass.; AND Amos ENGELSRATH, Block Engineering,19 Blackstone Street, Cambridge, Mass.-A Michelson inter-ferometer is used with a two channel amplifier to record areference and a sample interferogram simultaneously. Insteadof a beamswitching arrangement, we use a chopper with twoopenings, one of which has the sample mounted in it. Theamplifier is a modified version of a ratio recording amplifierfor a grating spectrometer, which synchronously separatesthe signal into two channels. The operation will be discussed,and some results will be presented on the transmission ofplastic films. (10 min.)

FG18. A Photographic Method of Measuring RocketNozzle Ablation.* EUGENE D. TIDWELL, ARO, Inc., ArnoldAir Force Station, Tennessee.-An accurate measure of noz-zle ablation is the main criterion by which an engineerdesigns the most efficient and effective rocket nozzle con-figuration in terms of thrust. A photographic method ofmeasuring nozzle throat area after firing is described,possible corrections are discussed, and a procedure is out-lined. Examples of ablation from firing are shown andcomparison measurements are made with the conventionalmicrometer diameter method. The photographic techniquepermits post-fired nozzle area measurements with an accuracyof ±0.5%. (13 min.)

* Work supported by the Air Force Systems Command's Arnold EngineeringDevelopment Center.

DIPLOMAT ROOM AT 2:45 P.M.

A. I. MAHIAN, Chairman

Contributed Papers

Physical Optics and Interferometry

FH11. Superposed Monochromatic Haidinger-likeFringes. C. FRANK MOONEY AND BERTRAm L. BARLOW,

Bausch & Lomb, Rochester, New York 14602.-The locusof each Haidinger-like fringe ring formed by a length-measuring interferometer using an extended source is pre-sented as a graph of the cosine of. its field angle versus thenormal interference order number. The effect of introducing

a Fabry-Perot 6talon in line with the metrological inter-ferometer is discussed in terms of this graph. Concordancebetween the superposed fringe systems is observed to occurwhenever the optical separation of the metrological inter-ferometer mirrors is an integral multiple of the 6talonspacer length. Attention is called to (1) the increase withfield angle of the effective length unit despite the mono-

FIFTIETH ANNIVERSARY MEE-TING * OPTICAL SOCIETY OF AMERICA 563

chromatic nature of the light, (2) the uniformity of the fluxversus the cosine of the field angle when the field stop isuniformly illuminated, (3) the effect of an axial field stopthat admits light for just one Fabry-Perot order, and (4)the occurrence of concordant fringe systems for every wave-number of a polychromatic source whenever the plate sepa-ration of the metrological interferometer is an integralmultiple of the 6talon spacer length. (13 min.)

FH12. Mirror Misalignment in Fourier SpectroscopyUsing a Michelson Interferometer with Circular Aper-ture.* CHARLES S. WILLIAMS, Texas Instruments Incorpo-rated, PO Box 5936, Dallas, Texas 75222.-The effect of aslight mirror misalignment in a Michelson interferometerused for Fourier transform spectroscopy is given for thecase of a circular aperture. The effect is related to themodulation index of the electrical signal when recording aninterferogram from which the spectrum is to be computed.(10 min.)

* An interferometer is being developed for the National Aeronautics andSpace Administration Nimbus B weather satellite program. The Nimbusprogram is a project of the Goddard Space Flight Center, Greenbelt,Maryland.

FH13. Fabry-Perot Interferometers in Uniaxially Aniso-tropic Media. LEONARD BERGSTEIN AND THOMAS ZACHOS,Polytechnic Institute of Brooklyn, 333 Jay Street, Brooklyn,New York 11201.-Fabry-Perot interferometers have beenextensively studied recently, primarily because of their im-portance as resonant cavities for laser applications. Theproblem most generally considered, however, assumes thatthe interferometer is imbedded in a linear, homogeneous,isotropic medium. In this paper a departure from thisidealized medium is made so that the effects of the presenceof an anisotropy in the medium may be investigated. Thus,we consider Fabry-Perot interferometers imbedded in linear,homogeneous, uniaxially anisotropic regions. It is shown that(even when the optic axis of the medium is arbitrarilyoriented with respect to the interferometer axis) a given"anisotropic interferometer" can be reduced to a correspond-ing equivalent "isotropic interferometer." Since the analysisof Fabry-Perot interferometers in isotropic regions is wellunderstood, considerable insight into the problem is gainedwithout resorting to detailed solutions, thus providing anunderstanding of the effects of the presence of an anisotropyon the transmission properties and resonant modes of aFabry-Perot interferometer. Extension of the results tointerferometers with curved reflectors is discussed. (13 min.)

FH14. Inverting Interferometers as Alignment Devices.J. W. GATES (introduced by J. B. SAUNDERS), NationalPhysical Laboratory, Teddington, Middlesex, England.-Two-beam interferometers in which the interfering beams arecentered on a common axis, and have corresponding raysof these two beams symmetrically disposed to the commonaxis, show striking possibilities as alignment devices. Onesuch interferometer, employing a confocal unit, is capable ofcentering reflecting surfaces on a given line, as well as pro-viding the means for adjusting the tilt of the surfaces. Atypical unit detects decentration of a 10-mm aperture mirrorto less than 0.01 mm and tilt of the surface of less than1 sec of arc. The reflecting surfaces under examinationneed not be plane since the indication is independent ofcurvature (spherical, astigmatic, or aspheric) as long as thecurvature is symmetrical about the alignment axis. A secondtype of system has the additional virtue of symmetry in theintensity distribution of the two beams, and double passing

is unnecessary. This unit provides a very satisfactory basisfor alignment methods in which the light beam needs totravel one way only. The unit may be used in conjunctionwith conventional sighting methods, but a special techniqueusing a gas laser has been devised which surpasses previousmethods in sensitivity and convenience. (13 min.)

FH15. A Study of the Diffrimoscopic Image and ItsFormation. GuY LANSRAUX AND JACQUES LEGENDRE, Ap-plied Physics, Diffraction Optics Section, National ResearchCouncil, Ottawa 2, Ontario, Canada.-Diffrimoscopy wasintroduced at the last OSA meeting. It designates a newfield of Optics which involves image formation using onlydiffracted light. In a particular case, derived from a classicalexperiment, an object is illuminated by a coherent beam; thelight which strikes the object is obviously cut out; that whichdoes not is focused and cut out by an absorbing mask. Onlythat light which is diffracted by the edge of the objectis focused in a diffrimoscopic image, and this image showsonly the object contour. Along an axis normal to the con-tour the distribution of light is symmetrical. The luminousintensity is zero at the center of symmetry which representsaccurately a point of the geometrical image. These charac-teristics hold when the image is observed out of focus.Moreover, two diffrimoscopic images equally out of focus,inside and outside the focus, are identical. Some of thesefundamental properties are explained by Young's theory ofdiffraction and by a later theory involving light inflected anddeflected by a diffracting edge. The formation of the dif-frimoscopic image may be interpreted by a wave theory basedon the Fourier transform. The validity of such a representa-tion will be discussed briefly. (13 min.)

FH16. The Dispersive Properties of PhotographicallyRecorded Interferences. A. K. RIGLER AND T. P. VOGL,Westinghouse Research Laboratories, Churchill, Pittsburgh,Pa. 15235.-As an outgrowth of our investigation of reflec-tion holograms a series of plates was prepared using planewaves from a He-Ne laser as both the object and referencebeams. The resulting interference patterns were recordedon 649F film and exhibited, as expected, diffraction gratingproperties. The properties of these gratings were investigatedand large dispersions were observed. For example: lineardispersions of 0.6 mm/A for 1-m focal length were measuredusing the 5770-A mercury doublet when the included anglebetween the two recording beams was 1200. These effectscan be observed in both transmission and reflection. Theresults obtained from a series of experiments in which theangle between the two beams was varied will be discussed.(13 min.)

FH17. On the Medium in Which Light Beams ArePropagated. ISABURO YOKOCHI, Department of Science &Engineering, Nihon University, 1-8 Surugadai KandaChiyodaku, Tokyo, Japan.-The pressure of light radiationhas been recognized generally, since Lebedew and Nicholsand Hull verified experimentally that it is in existence asindicated by Maxwell's theory. We do not consider that theirtheory and experiments are perfectly correct, so are tryingto clarify the essential quality of light. As the detector forthis purpose, we used the rotational vane without suspensionand found it to rotate at high speed. The plane surfaces re-ceiving light are mica leaf and are blacked over by soot orvacuum evaporated over by aluminum. As a result of observa-tions, we arrived at the conclusion that the vanes rotated inreverse of the light when offered vacuum condition. (13 min.)

KEY TO AUTHORS AND PAPERS

Adolph, Kenneth W.-FG16Allen, Eugene-FD17Alpern, Mathew, and Jurriaan ten Doesschate-WC18Ammann, E. O.-ThD14Apfel, Joseph H.-ThHl2Arakawa, E. T.-ThF13Arndt, Joseph, and Philip Baumeister-ThD17Arveson, John-WD12Austin, Roswell W.-WC11

Ballard, Stanley S., James S. Browder, and Hoyt M.Kaylor-ThFll

Barlow, Bertram L.-FHllBarrett, J. J.-ThF17Bastien, R. C.-ThF14, ThH15Baumeister, Philip-ThD17Becherer, Richard J.-ThD12Bennett, H. E.-FCllBennett, Jean M.-ThHllBent, Gary D.-ThGl6Bergstein, Leonard-ThBllBergstein, Leonard, and Thomas Zachos-FH13Blamont, J. E.-FA1Bleicher, Irving-FC16Block, William M.-FC16Bolle, Hans-JUrgen-FF16Borkowski, Raymond P., Aryeh H. Samuel, William M.

Block, Irving Bleicher, and Daniel Grafstein-FC16Borland, R. E.-ThBl6Boynton, Robert M.-TuBlBoynton, Robert M., S. R. Das, and Jean Gardiner-

WC12Browder, James S.-ThFl1Burch, Darrell E., and Elias Reisman-FB18Burch, J. M., and R. E. Borland-ThB16Burch, J. M., and A. E. Ennos-WF14

Cairns, R. B.-ThGl5Caldwell, B. Patrick-FD18Calviello, Joseph A.-ThF18Carter, Virginia L.-ThG12Chabbal, R.-ThA2Cheesman, L. E.-ThFl7Codling, K., and R. P. Madden-ThG13Collins, S. A., Jr., and M. Monroe-FF14Cook, G. R., and R. J. McNeal-ThC16Curnutte, B., Jr., and B. C. Hudson-ThC14

Dalton, Murphy L., Jr., and John Arveson-WD12Darone, Ronald-FB15Das, S. R.-WC12De, M.-WF12Delbouille, L., and G. Roland-ThC12Dobrowolski, J. A., and R. C. Bastien-ThH15Draegert, David A., and Dudley Williams-ThC15Duntley, Seibert Q., Roswell W. Austin, John H. Taylor,

James L. Harris, and W. Hadley Richardson-WC11

Eastman, D. P.-ThF15Ederer, D. L., and R. P. Madden-ThG14Edgerton, Robert F.-ThFl2Edlen, Bengt-TuB2El-Sum, H. M. A.-WG15Emmons, George H.-FG16

Englesrath, Amos-FG17Ennos, A. E.-WF14

Ferriso, C. C., and C. B. Ludwig-FF17Filler, A. S., and S. Litwin-FC17Flowers, Wayne L.-FG15Forest, Harvey, Aryeh H. Samuel, and Daniel Grafstein

-ThC17Friesem, A. A., and J. S. Zelenka-WF15Frumkes, Thomas E.-WGl1Fry, Amelia-WC13Fryer, R. E.-FG13

Gardiner, Jean-WC12Garton, W. R. S.-ThElGates, J. W.-FH14Gawartin, M., and I. C. Sandback-FC12Gelles, Rubin-WH17Givens, M. Parker, and William J. Siemens-Wapniarski

-WB16Goebel, David G., B. Patrick Caldwell, and Harry K.

Hammond, III-FD18Goldstein, E. Bruce, and Theodore P. Williams-WG12Grafstein, Daniel-ThC17, FC16Gray, L. D.-FB13Greenler, Robert G., Kenneth W. Adolph, and George H.

Emmons-FG16Grey, David S.-WH14Grusauskas, Joseph-TbB15Gulledge, Irene S.-WD14Gustafson, Darryl E., and Thomas I. Harris-WH12

Haines, K. A.-WB17Halberstam, M.-ThD13Hallock, Herbert B., Carl Krolik, and Joseph Grusauskas

-ThB15Hamm, R. N.-ThFl3Hammond, Harry K., III-FD18Hanst, Philip L.-FB16Harada, Tatsuo-FG14Harrick, N. J.-FC15Harrick, N. J., and A. F. Turner-ThH14Harris, James L.-WC11Harris, Thomas I.-WH12Harrison, George R.-ThCllHathaway, C. E., Gary M. Hoover, and Dudley Williams

-FB14Hattenburg, Albert T.-WD13Heimer, Richard J.-WH18Heinrich, P. L., and R. C. Bastien-ThF14Heller, Zindel Herbert, and Joseph A. Calviello-ThF18Herriott, D. R., J. R. Wimperis, and D. L. Perry-ThB12Hilarides, R. M.-WG13Hildebrand, B. P., and K. A. Haines-WB17Hillmann, Beverly M.-FD14Holl, Herbert B.-ThD16Hollinger, Amos-ThF15Hoover, Gary M.-FB14Horne, E. P., and R. M. Hilarides-WG13Hoversten, Estil V.-FF12Hudson, B. C.-ThCl4Hudson, R. D., and Virginia L. Carter-ThG12Hunter, Richard S.-WG18, FD12

564

FIFTIETH ANNIVERSARY MEETING e OPTICAL SOCIETY OF AMERICA 565

Jones, R. Wayne-WC13Judd, Deane B.-FDl1

Kahn, Walter K., and Noritaka Kurauchi-ThB17Kaylor, Hoyt M.-ThFllKeegan, H. J., and V. R. Weidner-WD17Keesey, Ulker Tulunay, and Dennis J. Nichols-WGI4Kelly, D. H.-WC16Kennedy, Robert S., and Estil V. Hoversten-FF12Kbhler, Horst-WHllKozma, A.-WB11Kozma, Adam, and Norman Massey-WB18Krolik, Carl-Th315Kurauchi, Noritaka-ThI17

Lamb, Willis E., Jr.-TuA2Langer, R. M.-FF15Lansraux, Guy, and Jacques Legendre-FH15Larson, H. P., and R. W. Stanley-ThG17Legendre, Jacques-FH15Leith, E. N., A. Kozma, J. Upatnieks, N. Massey, and

J. Marks-W3llLessman, Gerhard-ThHl6Levin, Robert E.-FC14Levinstein, Henry-FElLevitt, R. S., and N. J. Harrick-FC15Lewis, Lester Clark-FD13Litwin, S.-FC17Liu, I. D.-FF18Loewenstein, Ernest V., and Amos Engelsrath-FG17Lohmann, A. W., and D. P. Paris-WB15Lubbers, Marvin J.-WD16Ludwig, C. B.-FF17Lukosz, Walter-ThD11

MacRae, R. A., E. T. Arakawa, and R. N. Hamm-ThF13Madden, R. P.-ThG13, ThG14Mandel, Leonard-WA2Marechal, Andr6-WE2Marks, J.-WE 1 1Massey, N.-WEllMassey, Norman-WB18Mauch, Hans A.-WG16McBride, William R.-ThH13McCubbin, T. K., Jr., and Ronald Darone-FB15McNeal, R. J.-ThCl6Mehta, C. L.-WFllMeier, Reinhard W.-WB13Meinel, A. B.-WH16Meyer-Arendt, Jurgen R.-FF13Monroe, M.-FFL4Mooney, C. Frank, and Bertram L. Barlow-FHllMorita, Kenji-FG14Murphy, Eugene F.-WG17

Nachmias, Jacob-WC14Neill, Howard W.-FG12Nichols, Dennis J.-WG14

Oberly, Ralph-FB12O'Neill, Edward L.-WA1

Paris, D. P.-WB15Parrent, George B., Jr., and Richard J. Becherer-ThD12Peckham, Robert H.-WC17Perry, D. L.-ThB12Porto, S. P. S., L. E. Cheesman, A. Weber, and J. J.

Barrett-ThF17Potter, Robert J.-WE1

Rank, D. H.-ThF16Rank, D. H., D. P. Eastman, and Amos Hollinger-

ThF15Rao, K. Narahari, and Ralph Oberly-FB12Rau, James E.-WF13Reisman, Elias-FB18Richardson, W. Hadley-WC1lRigler, A. K., and T. P. Vogl-FH16Roland, G.-ThCl2Rome, Martin-WD15Ronchi, Vasco-FGllRope, E. L.-WF17Rose, Harold W.-WF16

Sakai, Hajime-F177Samson, James A. R., and R. B. Cairns-ThG15Samuel, Aryeh H.-ThC17, FC16Sandback, I. C.-FC12Schachter, Harry, and Leonard Bergstein-ThBllSchineller, E. R.-ThDl5Shack, R. V., and A. B. Meinel-WH16Shah, Bankim R.-FFl1Shenstone, A. G.-ThG11Shickman, G. M.-WC15Shipley, T., R. Wayne Jones, and Amelia Fry-WC13Siemens-Wapniarski, William J.-WB16Smith, Glendon C., and Hans A. Mauch-WG16Snitzer, E., and R. Woodcock-ThB13Spencer, Domina Eberle, and Robert E. Levin-FC14Stanley, R. W.-ThGl7Steinhaus, David W., and Michael A. Zerwekh-ThCl3Stetson, Karl A.-WF18Stroke, George W.-WB14Strong, John-FBllStuder, Frank J., and R. F. Van Beers-WD1lSturr, Joseph F., and Thomas E. Frumkes-WGll

Takasaki, Hiroshi-FC18, FD15Taylor, John H.-WCllten Doesschate, Jurriaan-WC18Tescher, A. G.-ThH18Thelen, Alfred-ThH17Thomas, Edward W., and Gary D. Bent-ThG16Tidwell, Eugene D.-FGl9Toraldo di Francia, G.-ThAlTousey, Richard-TuB3Townes, Charles H.-TuAlTricoles, G., and E. L. Rope-WF17Trytten, Grover W.-FG15Turner, A. F.-ThHl4

Upatnieks, J.-WB11Urbach, John C., and Reinhard W. Meier-WB13

Van Beers, R. F.-WDllVander Sluis, K. L.-ThG18Vogl, T. P.-FH16

Ward, Robert E., Jr.-WH15Weber, A.-ThFl7Weidner, V. R.-WD17Wick, R. V.-ThF16Wiggins, T. A., R. V. Wick, andWild, Hans J.-FC13Williams, Charles S.-FH12Williams, Dudley-ThC15, FB14

D. H. Rank-ThF16

566 FIFTIETH ANNIVERSARY MEETING * OPTICAL SOCIETY OF AMERICA

Williams, Theodore P.-WGl2Wilmot, D. W., and E. R. Schineller-ThDl5Wimperis, J. R.-ThB12Wolf, E., and C. L. Mehta-WFl IWolfe, William L., Wayne L. Flowers, and Grover W.

Trytten-FG15Wolfe, William L., and Marvin J. Lubbers-WD16Woodcock, R.-ThB13Wright, Hilton-FD16

Yamada, Yahiko, Tatsuo Harada, and Kenji Morita-FG14

Yokochi, Isaburo-FH17Young, C. G., and J. Z. Zdrok-ThBI4

Zachos, Thomas-FH13Zdrok, J. Z.-ThBl4Zelenka, J. S.-WF15Zerwekh, Michael A.-ThCl3

Committee at Annual Dinner in Philadelphia. Clockwise:Mrs. and Dr. Eugene Green, Naval Underwater Sound Lab.,New London (Invited Exhibits); Mrs. and Donald Hollings-head, Holco Instruments (Instrument Exhibit); Mrs. andDr. John Lang, Lennox Instruments (Instrument Exhibit);Douglas King, Frankford Arsenal (Hotel Liaison)

Committee at Annual Dinner in Philadelphia. Clockwisefrom 5: Mrs. and Mr. Harry Fitzgerald, Frankford Arsenal(Finance); Mrs. and Mr. F. A. Jessen, Ford Philco Corp.(Hotel Liaison); Mrs. Jo Ann Conlon (OSA ExecutiveOffice); Mr. and Mrs. Edward Sanders, 0 & S Research(Instrument Exhibit); Mrs. George Rayl; Mr. and Mrs.James Sheen, Frankford Arsenal (Banquet). At Speakers'Table: (L) Dr. Roderic Scott, Perkin-Elmer Corp. (OSABoard of Directors 1966-68, and Chairman, U. S. NationalCommittee, International Commission for Optics); (R)Marvin Gonshery, Frankford Arsenal (Registration).

From the Executive Office

From the Executive Office

The size of our OSA scientific meetings is steadily increasing,and arranging them without sacrificing quality is presenting

problems. Here we would like help and constructive sug-

gestions from our members.

Arrangements for an OSA meeting are usually started about

2 to 3 years ahead, with the help of some OSA members in

the area being considered for the meeting. Local sections now

frequently take the initiative. This is followed, after Board of

Directors' approval, by selection of a headquarters hotel which

has appropriate facilities for our meetings, and selection of a

program committee chairman and vice-chairman. A full pro-

gram committee is selected 12 to 18 months before the meet-

ing. OSA members receive an announcement, and call for ab-stracts of contributed papers usually 5 to 6 months ahead,

and abstracts are due in the Executive Secretary's office 2-}to 3 months ahead, so that members may receive their pro-

gram bulletins one month before the meeting. With this

schedule and the increasing number of abstracts, 154 at the

recent Washington meeting, room requirements change radi-

cally, especially if we increase the number of simultaneous

sessions from 2 to 3 and perhaps to 4! Sessions of papers are

more crowded and discussion time for each is curtailed. Atthe Washington meeting, the presentation time for 15-min

papers was reduced to 13 minutes to allow for some discussion

time.How can we overcome this congestion problem? Shall we

stay with a 3-day meeting, possibly adding Saturday sessions,

or arrange 4- or 5-day meetings? Shall we go to 4 simultane-

ous sessions for 3 or 32' days? Shall we reject a certain

percentage of papers, perhaps as high as 50% as does one

other scientific society? Currently, each OSA member may

present one paper at an OSA meeting, and possibly a second

if it is on a different topic. Should we accept and print all

abstracts as at present, but at the meeting simply give each

author 5 min to answer questions and assume that the at-

tendees have read the abstract and that there is no need for

more extended presentation than the published abstract? Each

of these suggestions has been proposed seriously.

One OSA officer has proposed the following plan. Let usrequire that each abstract be accompanied by a short paper,approximately 1000 words in length, including data and charts.

The latter might be issued as a "preprint" at the meeting atthe time allotted for that paper; or perhaps a group of such"preprints" on related topics might be reviewed by one or

more discussants of that topic. The author should appear andanswer questions which arise; this plan might permit more

unified and general discussion of individual areas of optics.Under this plan, the original abstracts themselves would still

be printed in the program bulletin and in the Journal as they

are at present. It has also been suggested that such a planmight be tried voluntarily on a small section of our program

to check its feasibility.Another possible change in scheduling the scientific sessions

at OSA meetings has been suggested by the program committeeof the meeting now being arranged in San Francisco, 19-22

October 1966. That committee would like to study in depthseveral selected areas of optics. To accomplish this, theywould like several invited papers on each of these selectedtopics. However, to reduce the congestion, they would like to

have contributed papers in widely different areas of opticsscheduled at the same time, since 3 or 6 or even 9 15-mincontributed papers might be scheduled in the same time as

one 45-min invited paper.A very important new development in the Society is the

formation of the new Technical Groups and Technical Council

under the vigorous leadership of L. M. Biberman, as describedin the February 1966 issues of the Journal and Applied Optics.

These can become voices for different areas of optics in whichOSA members are interested and can certainly modify thenature of our scientific meetings. Time and their success

will tell.To summarize, OSA is experiencing a vast increase in the

scientific information which our members wish to present atour scientific meetings. Can we devise a better plan for dis-seminating this important new scientific information andimproving communication among our members and colleagues

who attend our meetings?MARY E. WARGAExecutive Secretary

567