UNT Digital Library/67531/metadc688477/... · mine detection, to bridge deck inspections, wall...

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Welcome

Wewelcome youtothe Signal & Imaging Sciences Workshop sponsored by C. A. S. I. S., the

Center for Advanced Signal & Image Sciences. The Center, established primarily to provide

a forum where researchers can freely exchange ideas on the signal and image sciences in a

comfortable intellectual environment, has grown over the last three years with the opening of

a Reference Library (located in Building 272).

The Technical Program for the 1997 Workshop include a variety of efforts in both the Signal

and Imaging Sciences. This is the first year we have combined the disciplines to present some

new sessions and applications. After our Keynote Speeches by the Associate Director for

Engineering, Dr. S. Dimolitsas and Dr. D. Matthews, the Program Leader of the recently

formed Joint Medical Technology Program, we will get an in-depth overview of the applied

medical projects under way utilizing many of the high-tech approaches in the Imaging

Sciences (tomography, optics, etc.). This session is then followed by applications and new

developments in non-destructive evaluation including some new and exciting algorithms. We

complete the first day of presentations with many of the applications ranging from satellite

testing and control, to seismic processing, and imaging.

The second day is highlighted by and overview of the current astronomical and adaptive optics

projects, a special session devoted to computations in electromagnetic, acoustics and optics

focusing on the various algorithms available for applications in these areas. Next, we observe

the current accomplishments and applications of microimpulse impulse radars ranging from

mine detection, to bridge deck inspections, wall surveying and projectile tracking. A special

session on applications in optics is presented ‘with the new project on EUV lithography of the

Advanced Microtechnology Program being presented along with some other outstanding

applications. The Workshop is concluded with a special session on optics and processing for

the upcoming TANGO Space Shuttle Experiment. All in all the program looks like an exciting

time for the presentation of new work at the Laboratory.

We would like to formally thank our sponsors in the Laser and Weapons Programs and

Engineering. We hope that you will enjoy the mix of presentations, meet the participating

scientists and engineers and exchange your ideas openly. Thanks for attending.

J. V. CandyC. A. S.I. S. Director

3

n SIGNAL AND IMAGING SCIENCES WORKSHOP + 1997

Table of ContentsMedical Technologies

History of X-ray Mammography at LLNL ...... .................................................................. 9

Overcoming Collimator-Dependent Slice Thickness inCT Using Multiple Detector Arrays ... . .. . . .. .. .. .. .. . .. .. .. .. . .. . .. . .. .. .. . . .. ... .. .. .. . . .. .. .. . . . .. . . .. . .. . .. .. . . 10

Heart Simulator .. . . .. . . .. .. . .. ... . .. .. .. .. .. . . .. .. .. .. . .. . ... .. . .. .. . ... . . .. .. . .. . .. .. .. .. .. . .. .. .. .. .. . . .. . . .. .. . .. . . . .. .. .. . 11

Anechoic Studies for Prosthetic Heart Valve Evaluation .. . .. . .. .. .. .. .. .. .. .. .. . .. . .. .. .. . .. . .. .. .. .. .. 12

Light Transport Through Tissue . .. .. . . .. .. .. . .. .. . .. . .. ... .. . .. . .. .. . .. .. . .. . ... . . .. ... . .. . .. .. . . .. . .. . .. .. . . .. .. .. 13

Optical Coherence Tomography for Studying Periodontal Disease . .. .. . .. . .. .. . .. . . .. . .. . .. .. .. . . 14

A Fast Voltage Switching Detector for Dual Energy Computed Radiography .. .. . . . .. .. .. . . 15

Progress in Radar/Acoustic Speech Recognition ... . .. . .. . .. .. .. . . .. .. .. .. .. .. . .. .. .. . .. . . . .. .. . . .. . .. . .. . .. 16

Radar Detection of Hematomas .. .. .. . . .. .. .. .. . . .. .. .. .. .. .. . .. .. .. . .. . . .. .. .. .. .. .. . .. .. .. .. . .. . . .. . .. . .. . . . .. .. . .. .. . 17

Biomechanics of Osteoporosis: Using 3D Images to Calculate Fracture Risk . .. . .. . . .. . .. .. 18

Non-Destructive Evaluation

Overview of Nondestructive Evaluation .. .. .. . .. .. .. .. .. . .. . .. .. .. . .. . .. .. .. .. .. . ... . .. . .. . .. .. . .. . . .. .. . . .. .. .. 21

Waste Drum Nondestructive Assay by Gamma-ray Computed Tomography . . .. .. .. .. . .. ...22

Porosity Analysis . . .. .. . . .. .. .. .. .. . .. ... . .. . .. . .. .. . .. .. .. . .. .. .. .. .. . . .. .. .. . .. .. . .. .. .. ... .. . .. . .. . .. . . . . .. . .. . .. .. .. . ... . 23

Weapons Applications of Infrwed Thermal Imaging .. .. . . .. .. .. .. .. .. ... ... . .. .. . . .. . . .. . . .. . . . .. . .. .. .. . 24

Apply ing ANew Algorithm for Limited Angle Tomography . ... .. . ... .. .. . . .. . . .. . . .. . .. . . . .. . ... .. 25

The Trick is in the Tails: Using Evanescent Fields to IncreaseResolution in Diffraction Tomography . .. .. . . ... .. .. . ... .. .. .. . .. .. . .. .. .. . .. .. .. .. .. .. . .. . . .. . . .. .. . .. . . .. . .. .. . 26

Optical Inspection of Glass-Epoxy Bonds . .. ... . .. .. .. . .. .. . .. . .. .. .. .. .. ... .. .. .. . .. . .. . .. . .. . . .. . . .. .. . .. . .. . 27

Ultrasonic Techniques for the Department of water Resources .. .. .. . .. .. . .. .. . . . .. . .. . .. .. . . . .. ... 28

Applications of Signal/Image Processing

Dynamic Testing of Agile MicroSatellites . .. .. . .. .. .. .. .. .. .. .. . .. . ... . . .. .. .. ... .. . .. . .. . .. . .. .. . .. . .. .. . . .. .. 31

Optimal Attitude Control of Spacecraft with On-Off Thrusters . .. .. .. .. . .. . .. .. . . . .. . .. .. . . . .. .. .. . 32

Automatic Event Picking in Pre-Stack Migrated Gathers for Oil Exploration .. . .. . . .. . .. .. . 33

Generation of Optimized Signals From an Array ... .. . . .. . .. .. . .. . .. .. .. .. .. .. . .. . .. .. . .. . .. .. . .. .. . .. . . .. . 34

Pantex Lightning Protection System Tests and Modeling . . .. .. . .. .. .. .. .. . .. . .. .. . .. . . .. . . .. . ... . . .. .. 35

Pattern Recognition Algorithms in the Acoustic ResonantSpectroscopy Munition Classification System .. . ... . .. .. . .. .. .. .. .. . .. .. .. . ... .. .. . .. .. .. . .. . .. . .. . . .. . .. ... . 36

Image Analysis Applications in KDP Damage Studies . . .. .. ... .. . ... .. . .. . ... . . .. . . .. . .. . .. . .. . . .. .. ... 37

A Region-Growing Based Segmentation Algorithm for A&PCTImages of Waste Barrels with Radioactive Sources . .. . .. . . .. .. .. .. .. . .. ... . .. .. . . .. . .. . . .. .. . .. .. . . .. .. .. . 38

A Dual-Band Linescan Camera System for Measuring WaterContent on a Paper Web .... .. . .. .. .. . .. . . .. . .. .. . ... . .. .. .. .. .. .. . .. .. . .. .. .. .. .. .. .. .. .. . .. .. .. . .. . . . . .. .. . . .. . . .. .. . .. . 39

5

m SIGNAL AND IMAGING SC IENCFS WORKSHOP + 1997

J!2ser Guide Star and Adaptive Optics

A Review of Laser Guide Star and Adaptive Optics Projects .. .. . . .. .. .. .. ... . . .. . .. . .. . .. . .. . .. . . .. . 43

Computational Electromagnetic, Acoustics and OpticsLLNL Contributions to Time-Domain Electromagnetic Modeling and Simulation .. . ....47

The Swiss Army Knife for Frequency Domain EM Modeling . . .. .. . .. ... . .. ... . . .. . .. . .. . . . .. . . .. . . 48

A Forward Simulation for the Electromagnetic Fields in Lossy Media .. .. .. .. .. . . .. . .. . . . .. . .. 49

Wave Optics in Phase Space ... .. . .. .. .. . .. .. . . .. .. .. .. .. . .. .. .. .. .. .. .. .. . .. . .. .. . .. .. .. ... . .. .. .. . .. . .. . . . .. . .. . . .. . . 50

Preliminary Wakefield Calculations Using TIGER for aSimplified Kicker Structure .. .. .. . .. .. .. .. . .. . .. .. . .. .. .. . .. . ... .. .. . .. . .. . .. .. .. . .. . .. .. ... . .. .. .. . .. . . . . .. . .. . . .. . . .. 51

Broadband Acoustic Array Simulations for Localized Waves .. .. .. . .. .. .. .. .. . .. .. . . .. . . .. . . . .. . .. . . 52

MELD - Simulation ofltiultiscale ELectroDynamic Systems . .. .. . . ... .. .. .. .. . . .. . .. . . .. . . . .. . . .. . . 53

Discrete Time Vector Finite Element Methods for Solving Maxwell’s Equations .. . . .. ...54

Eyeglass: Fresnel Imaging from GEO .. . .. . .. . .. .. .. .. . .. .. .. .. .. . . .. .. . .. .. .. . . .. ... .. .. .. . . .. . .. . .. . . . . .. . . .. . . 55

Finite Element Modeling Applied to Radar and Optical Imaging .. .. .. . .. .. .. .. . .. .. . .. . .. . . .. .. . . 56

An Overview of Maxwell Eminence . .. . .. . .. . .. .. .. . .. . .. ... .. .. . . .. .. .. . . .. .. . .. .. .. .. .. . .. . .. .. . .. . . . .. . .. . . .. . . 57

A Human Supervisory Approach to Modeling Industrial ScenesUsing Geometric Primitives . .. ... . .. . ... . .. . . .. .. . .. .. .. . .. .. .. .. .. . . .. .. .. .. . .. . .. . .. .. .. .. . .. .. .. . .. .. . . . .. . .. .. . . . .. 58

Micro-Impulse Radar ProcessingMicropower Impulse Radar (MIR)for Landmine Detection .. .. .. . .. .. .. . ... . .. .. . .. .. . .. . . . .. . .. . .. . 61

HERMES: A High-Speed Radar Imaging System for theInspection of Bridge Decks .. ... . .. .. .. .. .. . . .. .. . .. .. .. . . .. .. .. .. ... .. .. .. . .. .. . . ... . .. .. .. . ... . .. .. .. . . .. . . .. . .. . . .. . . 62

Imaging Algorithms Research for MIR ... .. . .. .. . .. .. .. . .. .. .. .. .. . .. . .. .. . .. .. . .. .. .. .. .. .. . . .. .. . . .. . . .. . . .. . .. 63

Projectile Tracking with MIR ... .. . .. .. . .. .. . .. . .. .. . .. .. .. . .. .. ... . .. . . .. .. . .. .. .. . .. . ... .. .. . .. .. . .. . .. . . . . .. . .. . .. . 64

The MIR Wall Survey or . . .. .. . ... . ... .. . . .. .. .. . .. .. . .. . .. .. ... . . ... . .. .. .. .. . . .. .. . .. .. . .. . .. ... .. . . .. . .. . .. . .. .. . .. . . .. 65

OpticalApplicationsStatic Wavefront Correction for Inexpensive Large Optics .. . .. . . ... . .. .. .. . .. .. .. .. . . .. . . .. . .. . . .. . . . 69

Mask Blank Defect Detection for EUVLithography . .. .. . . .. . .. . .. .. . .. .. .. . .. .. . .. .. .. . .. .. . . . . .. . .. . . .. 70

Maskless Lithography . .. .. . . .. .. ... .. .. . .. . .. .. . .. . .. . .. .. .. .. . .. .. .. .. .. .. .. .. . .. .. . .. . .. .. .. .. .. . . .. .. . .. . .. .. . .. . .. . . .. 71

Linearization of a Micromechanical MicromirrorUsing aDSP Chip Work in Progress . .. .. . . .. . .. .. .. .. . .. .. .. . .. .. . .. .. . .. .. . . .. . .. .. .. .. . .. .. .. . . .. . . . .. . .. . .. . .. 72

Neuromorphic Tracker . ... . . .. .. .. ... .. . . .. .. . .. .. . . .. .. . .. .. .. . .. .. .. .. .. .. . . .. . .. .. . .. . .. .. .. . ... . . .. . .. . .. . . . .. . .. .. . . . 73

Signal Processing Requirements for Landmine Detection .. . .. . .. .. . .. .. .. . .. .. .. . .. . .. . . . .. . .. . .. . . . . 74

Sensitive Optical Detectors for Distance Moving Objects . .. . .. . .. . .. .. .. .. .. . ... . .. . . . .. . . .. . . .. . . . . .. 75

TANGO Space ShuttleOverview of the TANGO Space Shuttle Experiment and theOptical Imaging Diagnostic .. .. .. . .. . .. .. . .. . . .. .. . .. .. .. . .. .. .. .. .. . .. . .. .. . . ... .. .. . ... . .. .. . .. .. . .. . .. . .. . .. . . .. . . . . 79

Optical Design and Image Processing for the TANGO Space Shuttle Experiment .. . .. . . . 80

Rotational Dynamic Surface Imaging for the TANGO Space Shuttle Experiment . .. . . . . .. . .. . . 81

6

SIGNAL AND IMAGING SCIENCES WORKSHOP + 1997

MEDICAL

TECHNOLOGIES

❑ SIGNAL AND IMAGING SCIENCES WORKSHOP + 1997

History of X-ray Mammography at LLNL

Laura A4ascio and Clint Logan

LLNL has made contributions to the field of x-ray mammography in various areas:

● Developing a new digital x-ray system ●

(hardware) to acquire better images,

● Creating software algorithms to analyzedigital mammograms for early detection of “cancer warning signs,

Developing a database of patient cases withknown diagnosis for quality control ofsoftware algorithms, and

Addressing the issue of data storage andtransmission of digital mammogram data.

9

m SIGNAL AND IMAGING SCIENCES WORKSHOP + 1997

Overcoming Collimator-Dependent Slice Thicknessin CT Using Multiple Detector Arrays

J.A4. Boone, Associate Professor of RadiologyUniversity of Cal#ornia Davis A4ed Center

In computed tomography (CT) currently, theslice thickness-defining collimator is the primarydelimiter in the imaging chain that determinesthe z-axis resolution. By increasing the numberof detector arrays (contiguous arrays perpendicu-lar to the z-axis), the detector height defines thez-axis resolution. Such a design (one CT manu-facturer markets a 2 detector array system)allows excellent z-axis resolution without reduc-ing x-ray quanta th~ough collimation. Therefore,.from a single acquisition, many different slicethicknesses can be reconstructed depending onhow the data is rebinned prior to reconstruction.The purpose of this study was to evaluate usingboth computer simulation and experimentalacquisition, the trade-offs associated with mul-tiple detector array scanners. A small-bore (2cm) CT scanner with multiple (>200) thin (50

mm) detector arrays has been developed, whichis capable of acquiring both conventional andhelical data sets. Using these data sets, variousinterpolation algorithms have been developedwhich can deliver either thin slice (but noisier)images or thicker slice, low noise CT reconstruc-tions. Computer models have also been devel-oped to study the performance of interpolationalgorithms in the simulation environment.Signal to noise performance, MTF, and slicesensitivity profiles have been calculated forvarious rebinning strategies. The results demon-strate that CT scanners using multiple (310)linear detector arrays will be able to simulta-neously acquire thin and thick section images,which will be useful clinically in reducing partialvolume uncertainties, in 3D rendering applica-tions, and in better delineation of pathology.

10

mSIGNAL AND IMAGING SCIENCES WORKSHOP + 1997

Heart Simulator

Lee Haddad

11


Anechoic Studies for Prosthetic Heart Valve Evaluation

Skip Perkins, Graham Thomas, Jim Candy

One design of a prosthetic heart valve suffersfrom a failure mechanism known as single-leg-separation. While this failure occurs only in avery small fraction of the valves in existence andis not fatal, it does weaken the valve and anysubsequent failures are fatal. The medical com-munity is interested in a non-invasive method ofdetermining the integrity of the heart valve toavoid unnecessary replacement, a procedure notwithout risk. A passive acoustic method forevaluating the valyes shows promise but thebody is a very noisy environment and actualmedical data from patients is quite limited. As aresult distinguishing the difference between good

and bad valves in vivo has proved very difficult.Several methods have been tried to determine anon-ambiguous signature for the different typesof valves. These methods - FEM modeling,mechanical heart simulator, valves implanted insheep - all have short comings of one form oranother. In an effort to obtain a clear signaturefor valves with sufficient statistics to allowdistinguishing between good valves and single-leg-separation valves we are testing them in apseudo anechoic environment. The results ofthis work will then be used in semi-empiricalmodels to automatically distinguish good andbad valves in patients.

12


Light Transport Through Tissue

Duncan Maitland and Rich London

13


Optical Coherence Tomography for Studying Periodontal Disease

Matt Everett, Bill Colston, Luiz Da Silva, Linda Otis

We have developed a hand-held device for in vivo optical coherence tomography (OCT) imagingin the oral cavity. OCT is an optical technique for non-invasive imaging of biological tissue. Itgenerates high resolution (<20 pm) cross-sectional images of tissue similar to histological images,but without the need for tissue biopsy.

14


A Fast Voltage Switching Detector for Dual Energy Computed Radiography

J. Anthony Seibert,Department of Radiology,

University of Cal@ornia Davis Medical Center,Sacramento, C’alfornia

Robert A. Alvarez,Aprend Technologies,

Mountain View California

PURPOSE: To measure the image quality ofa new active detector for dual energy com-puted radiography which acquires data withtwo different x-ray tube voltages in a fractionof a second.

MATERIALS AND METHODS: The activedetector uses a sub-millisecond light pulse toacquire two images on storage phosphor screenswithout a screen changer. An experimentalsystem has been built, consisting of the activedetector interfaced to a computer controlled x-ray generator. Time to acquire the two imageswas measured, and comparison of the bone/soft-tissue images from the active detector systemwas made with those from a conventional “sand-

wich” detector. A quality factor equal to thesignal to noise ratio squared divided by theincident exposure was used for the analysis.

RESULTS: The active detector provides overten times better quality factor than a sandwichdetector. It is able to acquire data in less than100 milliseconds. Images of the same regiontaken with the same incident exposure qualita-tively demonstrate these findings.

CONCLUSION: The active detector systemproduces substantially better image quality thansandwich detectors for dual-energy tissue de-composition and can be implemented within anacceptable exposure time for chest radiography.

15


Progress in Radar/Acoustic Speech Recognition

G. C.Burnett, T.J. Gable, J.F.Holzrichter*, and L. C.Ng

It has recently been shown by the authors that micropower radars, configured in many transmittingand receiving modes, can be used to measure speech articulator behavior as speech is sounded.These ideas appear to make possible improved speech recognition and synthesis, noise removal,speaker identification, speech disability detection and correction, and research devices. Recentmeasurements, calibrations, signal processing experiments, and their implications will be presented.

*Presenter of paper

16


Radar Detection of Hematomas

Lee Haddad

17


Biomechanics of Osteoporosis: Using 3D Images to Calculate Fracture Risk

J.H. Kinney, * D.L. Haupt, ** and A.J. C. Ludd* **

Osteoporosis is an important public healthproblem. It is known that fracture risk is stronglycorrelated with 10SSof bone mass, yet more thanhalf of all patients diagnosed with low bonemass do not suffer from osteoporotic fracture.Furthermore, even for a given bone mass there isan age–related increase in fracture risk. Theseclinical observations suggest that there areadditional factors, such as changes in geometricstructure, accumulated microdamage, anddifferences in tissue properties, which mayexplain the occurrence of fracture in someosteoporotics and not in others.

We have imaged specimens of human vertebralbone at a resolution of 10–20~m with the syn-chrotrons tomographic microscope. Synchrotronradiation is monochromatic and highly colli-mated; it can be used to construct an accuratethree–dimensional map of the structure of miner-alized tissue at a spatial resolution as fine as2pm. In order to exploit the imaging power ofthe microscope, we have developed an efficientfinite-element method to calculate the mechani-cal properties of trabecular and cortical bone; thex–ray tomographs are used to provide the de-tailed structural input to the simulations. We

have calculated the elastic constants of structurescontaining as many as 17 million elements on asingle DEC Alpha processor.

The key contribution of the finite-elementcalculations is that they allow for an accuratedetermination of the effects of trabecular archi-tecture, and also take account of the variations inapparent modulus that result from differentmeasurement methods and different boundaryconditions at the load platens. This significantlyreduces the uncertainties inherent in mechanicaltesting of trabecular bone and allows us todetermine a reliable measure of the modulus ofthe bone tissue. The finite element model canalso incorporate a failure model based on themaximum local tensile strain. Even though thespecimen is loaded in compression, the geo-metrical structure of trabecular bone causesmany regi,ons to be in tension. It is reasonable tosuppose that fracture begins at these regions ofhigh tensile strain. We are currently comparingnumerical simulations of compressive failure ofrat vertebra with x-ray images of the samespecimen before and after loading. These studieshave important implications for the treatment ofosteoporosis.

* Chemistryand Materials Science Department, Lawrence Livermore National Laboratory, and Division of Biomaterials,University of California, San Francisco.

. . Engineering Jlepartrnent,LawrenceLivermore National Laboratory

*** now at university of Florida, Gainesville.

18

Is SIGNAL AND IMAGING SCIENCES WORKSHOP + 1997

lvoN-DEsTR UCTIVE

EVAL VAT-ION

HI SIGNAL AND IMAGING SCIENCES WORKSHOP + 1997

Overview of Nondestructive Evaluation

Graham Thomas

Nondestructive evaluation is a collection examples where NDE combined with signalof techniques to assess the condition of and image processing have resulted in datacomponents, It encompasses many modes fusion. By fusing the different NDE resultsof interrogation. All nondestructive evalu- we have been able to gain more informationation techniques benefit from signal and about the defects than if individual inspec-image processing. This paper will discuss tions where performed.

21


Waste Drum Nondestructive Assay by Gamma-ray Computed Tomography

G. Patrick Roberson, Harry Martz and Daniel Decrnan

Traditional gamma measurement errors arerelated to non-uniform measurement responsesassociated with unknown radioactive source andmatrix material distributions. These errors can bereduced by application of tomographic tech-niques, that measure these distributions.

LLNL has developed two tomographic-basedwaste assay systems. They use external radioac-tive sources and tomography-protocol to map theattenuation within a waste barrel as a function ofmono-energetic gamma-ray energy in wastecontainers. Passive tomography is used to local-ize and identify specific radioactive wastecontents within the same waste containers.Reconstruction of the passive data via the activeimages allows internal waste radioactivities in abarrel to be corrected for any overlying heteroge-

neous materials, thus yielding an absolute assayof the waste radioactivities. Calibration of bothsystems requires only point source measure-ments and are independent of matrix materials.

The first system housed at LLNL has partici-pated and successfully passed the requirementsof a formal DOE-sponsored intercomparisonstudy. The second system is housed within amobile waste characterization trailer, and hasmade measurements at three DOE facilities.Both systems have measured 1 to 70 grams ofplutonium within a variety of waste matrixmaterials. Laboratory and field results from thesetwo systems over the past several years showthat both systems are capable of precision of 1to 3?70and accuracies to within 30% of the truevalues of known standards.

22

SIGNAL AND IMAGING SCIENCES WORKSHOP @ 1997

Porosity Analysis

Skip Perkins, Ken Dolan, Jerry Haskins

The American Society for Testing and Materi- dards available in digital form. Once theseals (ASTM) produces standard casting samples standards are available in digital form, automaticcontaining various types of defects. Radiographs characterization becomes a sought after goal.

of these samples are available to the Nondestruc- This paper describes the digitization of thetive Evaluation community for use in training ASTM aluminum casting standards and a pre-radiographers. The recent trend to digital radiog- Iiminary attempt to automatically quantify theraphy has introduced a need to have these stan- porosity observed in the images.

23

SIGNAL AND IMAGING SCIENCES WORKSHOP + 199’

Weapon Applications of IR Thermal Imaging

Nancy K. Del Grande, Philip F. Durbin and James D. LeMay

We are applying IR thermal imaging to viewthe location, shape and relative depth of poly-meric inserts in multi-layered stainless steel andalumina plates. Using a dual-band IR camerasystem, we image time sequences of surfacetemperatures for flash-heated parts. Our thermalimage processing algorithms convert tempera-ture-time responses to thermal inertia maps.Thermal inertia is the square root of the product:

conductivity, density, and heat capacity. Byimaging thermal inertia for these parts, we knowwe can depict bulk thermal property differencesfor gaps, bubbles or foreign materials in hostweapon components. We found and verified thepresence of gaps at locations predicted by ther-mal imagery. IR thermal imaging provides aquick, non-contact method for assessing pottingoperations on 3D weapon components.

24

111 SIGNAL AND IMAGING SCIENCES WORKSHOP + 1997

Applying A New Algorithm for Limited Angle Tomography

Dennis Goodman

We have developed an extension of theconjugate gradient algorithm that incorporatesbound constraints on the variables; this algo-rithm is particularly appropriate for limitedangle tomography because these bound con-straints can greatly reduced the ill-posednessthat is a major issue in reconstruction fromlimited angles. It has the added advantage that,unlike conventional optimization methods, itincorporates a bending line search that allowsmore than one variable per iteration to attain a

bound. Given the large dimensionality oftomography problems, the incorporation of abending Iinesearch was crucial. Our algorithmhas been applied in the past with great success toa variety of practical problems. These includedeconvolution, speckle interferometry, crystal-lography, and pulsed photothermal radiometry.This year we have demonstrated its value onseveral limited data tomography problems. Wewill give some preliminary results.

25


The Trick is in the Tails: Using Evanescent Fieldsto Increase Resolution in Diffraction Tomography

Sean Lehman

Few diffraction tomography reconstruction algorithms use the evanescent fields to increaseresolution. We present some of the current techniques to use these non-propagating fields whenoperating in near-field environments.

26


Optical inspection of glass-epoxy bonds

Diane Chinn, Dwight

The National Ignition Facility (NIF) at LLNLfaces new challenges in the inspection of thou-sands of precision laser optics. Among thoseoptics are 3,100 laser amplifier slabs, the 0.8-by-0.4 meter pieces of glass that act as the energystorage medium of the NIF laser. We assembledand demonstrated the essential elements forautomated inspection of NIF amplifier slab

Perkins, Ray Brusasco

cladding bonds. From this demonstration, wedeveloped a preliminary design, cost estimateand completion plan for an automated inspectionsystem that would replace the current manualinspection technique. With this inspectionsystem, NIF will have a reliable, accurate andrecordable tool to evaluate the quality ofampifier slab cladding bonds.

27


Ultrasonic Techniques for the Department of Water Resources

Al Brown

28


AP=ICATIONS OF

SIGNAL/IMAGE

PROCESSING

m AND IMAGINGSCIENCES WORKSHOP + 1997

SIGNAL

Dynamic Testing of Agile MicroSatellites

Larry Ng

A team of scientists, engineers, and techniciansat the Lawrence Livermore National Laboratoryis developing technology essential for a newclass of satellite, the microsatellite, or microSat.Equipped with high resolution sensors, thesemicroSats have the ability to perform precisionattitude pointing and agile translation maneuversin near earth space. Integral to the success of this

development, the Livermore team has con-structed a Micro Hover Facility that imple-ments the concept of a dynamic air bearing,allowing faster, better, and cheaper develop-ment through comprehensive testing. Thispaper describes the test methodology and theplanned activities associated with the develop-ment of agile microSats.

31


Optimal Attitude Control of Spacecraft with On-Off Thrusters

Principal Researchers: Fermin N. Garcia and Lawrence C. Ng

Most modern spacecraft require a high degreeof precision attitude pointing capabilities inorder to accomplish their mission. Satellites, forinstance, are required to constantly point theirsolar panels toward the sun while maintaining acertain attitude to stay in a specific orbit. TheClementine II team at Lawrence LivermoreNational Laboratory needs high precisionattitude control in order to perform surveillance,tracking, and interception maneuvers in nearearth space. The choice of on-off reaction jets,as opposed to using the more linear actuationprovided by momentum wheels or controlmoment gyroscopes (CMG’ s), to provide the

attitude control torques presents an additionalchallenge to the Clementine II group . The hardnonlinearity generated by the “bang-bang”control nature of reaction jets introduces a limitcycle in steady-state operation, thereby resultingin excessive fuel consumption. A control algo-rithm is developed to optimally command thereaction jets such that attitude error is drivenbelow a required tolerance while minimizingfuel consumption in the limit cycle mode. Thispresentation discusses the model and the controlalgorithm employed in the development of afuel-optimal attitude controller for theClementine II project.

32

n SIGNAL AND IMAGING SCIENCES WORKSHOP + 1997

Automatic Event Picking in Pre-Stack Migrated Gathers for Oil Exploration

Gregory A. Clark

Velocity estimation is currently a “bottleneck,”or barrier to progress in oil exploration, becausethe required seismic event picking step must becarried out manually at great cost in time andmoney. The goal of this research is to create 2Dand 3D algorithms for automating the process ofpicking seismic events in pre-stack migratedgathers arranged in common reflection point(CRP) panels. The work has been fundedthrough the DOE/ACTI (Advanced ComputingTechnology Initiative) and Shell E&P Technol-ogy Company. The approach uses supervisedlearning and statistical classification / neuralnetwork algorithms along with advanced signal /image processing algorithms.

The most significant accomplishments during thefirst 1 1/2 years of work include the following: (i)Delivery of MATLAB code implementing the 2D

automatic picking algorithms and a preliminary 3Dalgorithm. (ii) Excellent performance in pickingevents correctly in CRP panels, both during train-ing and testing with a real data set. (iii) Excellentperformance in reducing or eliminating the difficultloop skipping problem. (iv) Reduction of the timerequired to pick a data set from approximate y oneday (24 hours) to about 6 minutes, using a Shellimplementation of the algorithm. Shell anticipatesthat with the 3D algorithms, the cost of picking afull seismic survey will be reduced from about 12weeks and $75,000 to about 1 week and $6,000,for a factor of 12 savings.

The proposed research for FY98 is focusedon the 3D problem of picking and trackingevents from CRP panel to CRP panel to pro-duce picked common offset panel (COP)displays of the full data set.

33


Generation of optimized signals from an array

D. Kent Lewis and David H. ChambersStrategic Systems Support Program

Recent work in the Strategic Systems Support use of signal processing is somewhat straightProgram on acoustic and microwave arrays has forward, but specific solutions can be subtle.shown that imperfections in field arrays can The Weiner based theory presently used will beoften be corrected by pre-processing the generat- presented, and a specific problem in which othering signals for each element. This pre-launch methods were necessary will be discussed.

34


Pantex Lightning Protection System Tests and Modeling

Mike Ong

Lawrence Livermore National Laboratory(LLNL) has developed a technique based on low-power point-to-point measurements to assess thevulnerability of high-value facilities against light-ning. The methodology consists of a site survey,lower-power RF measurement, and computeranalysis of the data. Induced currents and voltageson metallic penetrations in bays and cells aredetermined from the analysis. This approach wasapplied to the Nevada Test Site (NTS) DeviceAssembly Facility (DAF) to assess lightningvulnerability [1]. It is important to estimate thepossible cell voRages and currents for two reasons:(1) The currents must be diverted by the bondingwires from the penetrations to the “faraday cage”.The current level is needed to determine the rightbonding wire size. (2) The voltage level is neededto determine a safe standoff distance between thepenetrations and any vulnerable weapon compo-nent. This information is also used in the riskanalysis and risk control.

The purpose of the site survey is to estimate thefacility vulnerability. The bases for the evaluationare a visual inspection, knowledge of the lightningand coupling phenomena, and understanding of theplant operation and possible risks. We then selectthe most vulnerable bay and cell for testing. Test-ing consists of injecting RF signals onto metallicexternal structures that might be struck by light-ning. Inside, the resulting currents and voltages onpenetrations are measured. (See Figure 1.) Theseare point-to-point measurements. An example ofan injection point is an air terminal for attractinglightning and protecting an air duct. Inside, pen-etrations might include electrical conduits, waterlines, and air ducts. These measurements producecoupling transfer functions in the frequency do-main. They are converted into linear circuit mod-els. On a computer, the circuits are stimulated with

a full lightning wave form. (See Figures 2 and 3.)The inside currents and voltages can then becalculated for the different penetrations.

IFigure 1. Point-to-point low-power

measurement technique generates coupletransfer function for metallic penetrations.

L3st(f) isenAn(f)

I I

Figure 2. Low-power measurements producethe attenuation and impedance functions.

l,..,(t)

Ilk!htnhw(t)

v...” v.=.”(t)z.”(f) IFFT

Figure 3. Computer modeling of lightningthreat produces estimates of penetration

current and voltage levels.

Energy from a lightning strike can be conveyedto a critical component by two paths, directly onconductors and through the air with the electromag-netic fields. The LLNL assessment technique alsorequires that the induced electric and magneticfields be measured and modeled.

[1] Zachanas, R, A. (LLNL), R. S. Collier (EMA Inc.), et al., “The DAF Lightning Threat and Immunity Estimates for Nuclear Explosive Safety”,

Feb. 1996, UCRL-ID- 125453.

35


Pattern Recognition Algorithms in the AcousticResonant Spectroscopy Munition Classification System

Randy S. Roberts

This presentation describes the pattern recogni-tion algorithms in the Acoustic Resonant Spec-troscopy (ARS) Munition Classification System(MCS). The ARS-MCS is a nondestructiveevaluation system that classifies chemical muni-tions according to agent, and also blindly dis-criminates between liquid- and solid-filledmunitions. The system is slated for use as averification tool in the Chemical WeaponsConvention (CWC), a multilateral chemicalweapons agreement that took effect last April.The system, based on acoustic resonant spectros-copy, has been successfully tested on a widevariety of U. S. chemical munitions. The ARS-MCS is designed for field use, and consists of aportable battery-powered instrument packagealong with a notebook computer. The system hasbeen commercialized, and will be available tomunition inspectors in the near future.

The pattern recognition algorithms in the ARS-MCS perform two tasks: to classify munitionsaccording agent, and to discriminate betweenliquid- and solid-filled munitions. The munition

classification algorithm exploits the acousticspectrum of the munition under inspection.Spectral features are extracted from the acousticspectra of known munition classes. A featureconsists of two components: the frequency of aresonant peak, and a measure of the sharpness ofthe peak. The features from all munitions in thetraining set are clustered so that the variance ofeach cluster is minimized. These clusters form atemplate for a particular class of munition. Whenan unknown munition is classified its spectralfeatures are extracted and compared to a libraryof templates. If the match between the spectralfeatures of the munition and a template in thelibrary is close enough, the munition is declaredto belong to the class associated with that tem-plate. The liquid-solid discrimination algorithmalso exploits the acoustic resonant spectrum ofthe munition under inspection. This algorithmuses average peak width and spectral powerdistribution as features. This feature set allowsthe liquid-solid discrimination algorithm toperform blind classification, i.e., a training set ofspectral data is not required for classification.

36


Image analysis applications in KDP damage studies

Mike Runkel

The study of laser damage and conditioningin KDP is being driven by the maximumfluence system requirements for triple har-monic generation crystals (THG) on the NIFlaser. Current redline fluence specificationscannot be met with current state-of-the-artmaterials without laser conditioning.

The application of inexpensive, reliable dataacquisition hardware and software has allowedmany new experimental techniques to be appliedto the KDP damage problem. This has lead to an

increased understanding of how laser damage inKDP will affect the NIF.

Results of a laser damage and conditioningstudy on the Optical Sciences Laser, usingrecently developed damage diagnostics will bedescribed. The damage evolution model result-ing from this study has been applied to modelspatial profiles for third harmonic generationcrystals and predicts acceptably low levels oflaser damage to NIF triplers.

37

B SIGNAL AND IMAGING SCIENCES WORKSHOP + 1997

A Region-Growing Based Segmentation Algorithm forA&PCT Images of Waste Barrels with Radioactive Sources

Sailes K. Sengupta

A region-growing based segmentation algo-rithm has been developed for reconstructedemission images using active and passive com-puted tomographic images. The algorithm hasbeen successfully applied to the A&PCT imagesof waste barrels to locate radioactive sources.The algorithm uses a three step procedure. Thefirst is a pre-processing step that removes ‘noise’voxels by thresholding the logarithmicallytransformed reconstruction images derived fromtwo different gamma-ray energy levels followedby the formation of a boolean product of thethresholded images . The second step uses a 2-dimensional region-growing based segmentationalgorithm that uses a raster scan to make one of

two decisions on each pixel : (a) Merge with oneof the existing regions that is adjacent with thepixel or (b) forma new region starting with thegiven pixel. The decision to merge or not isbased on the gray level of the pixel under consid-eration as well as the statistical property of theadjacent regions, In the final step the 2-D seg-ments obtained for each slice are examined forconnectivity with segments of the next slice anddecision to merge segments is made based on thegray level statistics of the segments. The deci-sion of merging the segments leads to the forma-tion of equivalence classes of 2-D segments. Theindividual segments in each equivalence classare then merged to form the final 3-D segments.

38


A Dual-Band Linescan Camera System forMeasuring Water Content on a Paper Web

Jose E. Hemandez

The purpose of this project is to investigatethe use of linescan cameras and image process-ing techniques for 100% on-line measurement ofpaper web properties. This project is beingfunded by the Department of Energy Office ofIndustrial Technologies (DOE-OIT) under theIndustries of the Future program. Most of theprogress made during this year consisted in thedevelopment of software and hardware forperforming experiments and testing of several

CCD-based imaging systems for on-line paper webmeasurements. The primary imaging systemcurrently under development at LLNL consists of adual-band linescan camera system for measuringmoisture variations on-line with a 100% coverageof the web at all times. We are also collaboratingwith ORNL to develop a system to image the wetend of the paper web process. The author will givea presentation summarizing the progress made thispast year on the project.

39


LASER GUIDE STAR

AND

ADAPTIVE OPTICS


A Review of Laser Guide Star and Adaptive Optics Projects

James M. Brase

A summary presentation of the current status of Laser Guide Star and Adaptive Optics work aswell as an outline of future work.

43


COMPUTATIONAL

EZECTROMXGNETICS,

ACOUSTICS AND

OPTICSi


LLNL Contributions to Time-Domain Electromagnetic Modeling And Simulation

Niel Madsen

Historically, LLNL has played a rather unique role in the development of time-domain EM model-ing and simulation. Significant contributions of the past will be reviewed leading to a description ofcurrent capabilities and research directions. The use of time-domain EM codes relating to SARimaging will be discussed.

47


The Swiss Army Knife for Frequency Domain EM Modeling

J.B. Grant, R.M. Sharpe, and N.J. Champagne

EIGER is an object-oriented frequency domain geometries. For example, in a frequency selec-electromagnetic modeling tool that can utilize tive surface EIGER can model discretizedmultiple numerical techniques in a single model arbitrarily shaped scatterers while analytically(thus the Swiss Army Knife reference). By treating the layering and periodicity. Presentedcombining various integral equations and differ- here are several examples that demonstrate thisential equations EIGER can address complex versatility in EIGER.

48


A Forward Simulation for the Electromagnetic Fields in Lossy Media

N. J. Champagne, J. G. Berryman, J. B. Grant, and R. M. Sharpe

A code that performs a forward simulation forthe electromagnetic fields within lossy mediahas been developed as part of an effort to createaccurate forward solvers to couple with ad-vanced inversion tools for imaging in the earth.The fields within a volume are determined byapplying the integral form of Maxwell’s curlequations to rectangular or brick cells that areelements of a volume mesh. The volume ofinterest may contain material regions that are

anisotropic, i.e., have different material param-eters in each coordinate direction. Regions thatare unbounded are truncated with artificialboundary layers, also known as perfectlymatched layers (PML), so that no outgoingelectromagnetic waves are reflected back intothe interior of the volume. The results that willbe presented show that this formulation pro-duces accurate fields for one, two, and three-dimensional problems

49

E SIGNAL AND IMAGING SCIENCES WORKSHOP + 1997

Wave Optics in Phase Space

R. P. Ratows~, J. S. Kallman, M. D. Feit and B. B. Afeyan

Light propagation calculations using ray opticsare generally far less costly than those usingwave optics, since the former requires calculat-ing only ray paths while the latter demandssolving a partial differential equation. However,traditional ray optics misses diffraction effects,which can be important. For example, a beamwhich is smaller than a few wavelengths will bepoorly modeled using ray tracing. However, it ispossible in som~ circumstances to includediffraction in a ray--tracing calculation by propa-gating a distribution function in the position-angle phase space of the rays. One such function,The Wigner Distribution , is an integral trans-form of the scalar field resembling a local Fou-rier transform. In many situations of practicalinterest, the Wigner function is well conserved

along geometrical rays . Because it is invertible,the field itself can therefore be determined fromray tracing alone. A propagation calculation thenproceeds as follows: Given a (scalar) fielddistribution, one calculates the Wigner distribu-tion function at some input plane. One thencalculates the nearfield and farfield intensity”distributions at an output plane (say an imageplane in an imaging system) by back propaga-tion. Knowledge of the nearfield and farfieldintensities at the image plane are sufficient torecover the complex optical field, using a phaserecovery algorithm . In this presentation we willdevelop the theory of the phase space approachand illustrate with some simple examples: freespace diffraction, two-slit interference, and asimple (but nonideal) lens.

50


Preliminary Wakefield Calculations usingTIGER for a Simplified Kicker Structure

David Steich

This presentation will describe the scope,approach, and progress to date of the Timedomain Generalized Excitation and Response(TIGER) project. TIGER is an object orientedcomputational electromagnetic code based onDiscrete Surface Integral (DSI) and finite differ-ence techniques applied to structured and/orunstructured nonorthogonal meshes. A prototypeversion of the code was built in FY97.

TIGER’s firs! application is to model theelectromagnetic fields of accelerator componentsfor the Advanced Hydro Facility. High currentultra-relativistic beams being deflected through

stripline kickers are strongly dependent on thewake properties of the structure. The accuratecalculation of the wake fields for these complexstructures in 3-D time domain simulations posesseveral challenges, even under the assumptionthat the beam is infinitely rigid (i.e., wake fieldsdo not influence beam trajectory), Implementationdetails central to these kicker simulations will bediscussed. Preliminary 3-D time domain resultsusing TIGER will be compared with quasi-analyticsolutions for several pillbox geometries. Resultswill also be compared with transmission linemodels and previous stair-stepped simulations for asimplified kicker structure.

51

ml SIGNAL AND IMAGING SCIENCES WORKSHOP + 1997

Broadband Acoustic Array Simulations for Localized Waves

David Chambers

Simulations are used to predict the response experimental measurements of far field

of acoustic arrays which launch broadband directivity patterns and axial energy decay.

pulses (localized waves). The formulation of Models for transducer and receiver response

the simulations for broadband pulses is must be incorporated into the simulation to

discussed and comparisons shown with give realistic predictions.

52


MELD - Simulation of Multiscale Electrodynamics Systems

Jejj$rey S. Kallman and Richard P. Ratowsky

There are a number of systems we wouldlike to simulate that incorporate componentsof ‘mixed’ length scale. These componentsare very large with respect to the wavelengthof interest, but have wavelength scale details.An example of such a structure is a ball lenswith a sub wavelength thickness coating. Thisdevice can not be correctly simulated by theusual techniques: It is too large for finite-difference time domain simulation ofMaxwell’s equations, and interest in reflec-tions makes a Beam Propagation Method(BPM) inappropriate. The SPHERE code wasdesigned to deal with coated ball lenses.

The problem comes when we want toincorporate coated ball lenses into systems.We need a way to s~ap together models ofvarious components to see how they worktogether. The MELD code provides aframework in which to do this. MELDincorporates a number of modules:SPHERE, a free space simulator, a sourcesimulator, thin lens, mirror, beam splitter,directional coupler, and BPM simulators.By connecting modules together using agraphical user interface, entire systems canbe modeled.

53

III SIGNAL AND IMAGING SCIENCES WORKSHOP + 1997

Discrete Time Vector Finite Element Methods for Solving Maxwell’s Equations,

Daniel White

In this talk we summarize a mixed finite element method for solving the time-dependentMaxwell equations on three-dimensional unstructured grids. Numerical properties such asstability, conservation, and dispersion will be discussed. If time allows some interestingoptical scattering calculations will be presented

54


Eyeglass: Fresnel Imaging from GEO

Roderick A. Hyde

The Eyeglass is a new type of large aper-ture space telescope, intended to performhigh resolution Earth observation fromgeosynchronous orbit, and designed to solvethe tolerance, weight and deployabilityproblems generally encountered with suchtelescopes. It consists of two distinct space-craft, separated in space by several kilome-ters; one vehicle serves as a MagnifyingGlass and the other as a movable Eyepiece.

The Magnifying Glass is a thin Fresnellens and provides the large (25-50 meter)aperture necessary for high resolutionviewing from GEO; it’s thinness makes itlight, flexible and easy to package anddeploy, while it’s transmissive nature makesit very tolerant of surface ripples andmisalignments. The Fresnel lens will befabricated from a transparent polymermembrane and will be deployed and kepttaut in space via axial rotation. Its largestpositional challenges come from in-planethermal distortions and out-of-plane vibra-tions; the former are tolerable because oftheir uniformity and the latter because themembrane’s rotational stiffness prevents theexcitation of optically intolerable (cm-sized) ripples.

The separate Eyepiece vehicle is similar tomesent suace telescopes in both its size ( 1

meter aperture) and its data collection andhousekeeping features, but has uniqueoptical and propulsive features stemmingfrom its use with a magnifying glass.Fresnel lenses are not normally used inhigh-quality telescopes because of theircolor-dependent focal length; the Eyepieceincorporates special optics to eliminatethese chromatic aberrations and permitdiffraction-limited angular-resolution. Inorder to collect images, the Eyepiece mustbe properly positioned within the focalvolume of the Magnifying Glass. To do thismaneuvering it will use a combination ofelectrical propulsion and internal-mass-shifting, enabling it to hold longitudinalstation (resisting differential orbital drift)and to move transversely between imagesites.

The Eyeglass telescope provides a groundFOV of several kilometers, and can berapidly pointed to different targets withinthe underlying hemisphere. Images within aneighboring, roughly 1000 km sized, groundtheater can be gathered simply by movingthe Eyepiece along the focal surface of the(passive) Magnifying Glass. To look atmore distant targets, as well as to track theEarth during the day, the full Eyeglass mustbe reoriented, in which case the MagnifyingGlass is also swiveled.

55


Finite Element Modeling Applied to Radar and Optical Imaging

Steve Permock, Ansoft Corp.

Electromagnetic modeling can be used toenhance the understanding of radar andoptical images. Techniques like the finite-element method can be used to model be-havior of real imaging targets, and enablethe user to modify or simplify the system toeliminate some of the complexity inherentin the physical world. Details such as mate-rial properties and dimensions can be easily

varied, as can the angle of incidence of theincoming waves, and from such variation, abetter understanding of the actual systemcan be achieved.

A brief overview of the 3D finite elementmethod for solving Maxwell’s equations willbe given, and some examples of its applicationto radar and optical problems will be shown.

56


An Overview of Maxwell Eminence

Sean Lehman

57


A Human Supervisory Approach to ModelingIndustrial Scenes Using Geometric Primitives

Randy S. Roberts

There are many uses for intelligent, semi-autonomous robots in industrial environments.particular, industrial environments such ascontaminated processing plants or hazardouswaste sites can benefit from intelligent robotsduring decontamination and decommissioningoperations. An important ingredient of semi-autonomous robotics is a world model of theenvironment in which the robot operates. Anaccurate world model allows the robot to plan

In

and execute its tasks in a robust fashion. Unfor-tunately, world models for many industrial sitesare either unreliable or unavailable.

The traditional method of generating worldmodels is to manually create the models usingCAD tools. This method is not only extremelytime consuming but may be impossible in haz-ardous areas in which object measurementscannot be collected. Fully autonomous methodshave also been tested in recent years, but these

methods are not reliable enough to be used withreal- world data on hazardous tasks.

The techniques presented here are designed tobuild accurate world models from multiple rangeimages collected from industrial environments.The data used to develop the algorithms werecollected from a structured lighting system atSandia National Laboratories. The data is noisyand contains errors that render most segmenta-tion and modeling algorithms inadequate. Thesegmentation and modeling algorithms thatcompose the method are specifically designedfor industrial environments, and are described indetail. A mapping system based on these algo-rithms has been designed and implemented. Itenables a human supervisor to quickly constructa fully defined world model from unfiltered andunsegmented real-world range imagery. Ex-amples of how industrial scenes are modeledwith the mapping system are provided.

58


MICROPO WER

IMPULSE

RADAR

m AND IMAGING SCIENCESWORKSHOP + 1997

SIGNAL

Micropower Impulse Radar (MIR) for Land-mine Detection

Steve AzevedoOther authors: J.A4. Brase, J.E. Mast, E. T. Rosenbury

There is significant threat to U.S. nationalsecurity from in-place and stockpiled land minesaround the world. The International Red Crossestimates that around 100-million mines are inplace worldwide, 2-million were planted in 1994alone, which is twenty times more than thenumber removed ! Relief efforts by variousgovernment and non-government organizationsare over-taxed and lacking in technology to solvethe problem. An investment in new technologiesis needed now to improve the two key perfor-mance parameters of mine-clearance efforts:reliability and speed of clearance.

Both reliability and speed of clearance areimproved if each individual mine can be found.

MIR technology is an entirely new sensorconcept that is based on high-speed pulsedelectronics. The radars exhibit a combina-tion of interesting properties including,wideband operation, extremely low powerconsumption, extremely small size and lowcost, array configurability, noise-encodedpulse generation and other features. Thepotential for a first-ever fully-3D, real timeimaging system capable of revealing imag-ery of volumes beneath the earth’s surfacewould be a dramatic contribution. The goalis to transition MIR technology intofielded systems that help mitigate the tre-mendous human suffering caused by anti-personnel land mines.

61


HERMES: A High-Speed Radar Imaging System for theInspection of Bridge Decks. Experimental Results and Future Work

Holger Jones, AMP-IDG

In collaboration with the Federal Highways allow structural engineers to pin-point theirAdministration (DOT), LLNL has developed a efforts, which will save tremendous man-ground penetrating radar imaging system, power, equipment and infrastructure costs.which will be used to inspect concrete bridge Results from a recent experiment on a bridgedecks for structural defects. Ascertaining the deck in Weaverville CA. along with futureintegrity of a bridge deck prior to repair will development plans highlight this presentation.

62


Imaging Algorithms Research for MIR

JefiMast

This talkwill present anoverview of MIRimagingat LLNL.

63


Projectile Tracking with MIR

Tom Rosenbuiy

64


The MIR Wall Surveyor

Sean Lehman

The objective of the wall surveyor is to develop a compact device and accompanying signal pro-cessing algorithms to determine the composition of a layered wall probed with a hand-held MIR.The goal is to locate the layers of the wall, determine their material properties, identify objects suchas rebar and voids, and measure overall wall thickness.

65


OPTICAL

APPLICATIONS

M SIGNAL AND IMAGING SCIENCES WORKSHOP + 1997

,

Static Wavefront Correction for Inexpensive Large Optics

David Erskine

69


Mask Blank Defect Detection for EUV Lithography

Jeff Mast

Current commercial optical scattering waferinspection tools are not sufficient for extremeultraviolet lithography (EUVL) mask inspection.These systems detect particle sizes down to 80nm polystryene latex (PSL) spheres. However,initial model analysis indicates that step defectsin the mask substrate of heights on the order oflnm will generate printable EUVL phase de-fects. Therefore, current inspection techniques

must be improved substantially to locatedefects of this scale. Furthermore, currentinspection systems are optimized for lookingfor particles and scratches on the surface ofsubstrates and not for defects beneath orwithin the multilayer coating of EUVL masks.This talk will discuss our approach to EUVLmask blank defect inspection and some pre-liminary results of our study.

70

Ill SIGNAL AND IMAGING SCIENCES WORKSHOP + 1997

Maskless Lithography

Jesse Kolman

A strong candidate for the production offuture generations of integrated circuits ismaskless lithography. This technique involvesusing a dynamic spatial light modulator (SLM)instead of a static mask to produce the patternof light which gets printed on a wafer. Be-sides offsetting the increasing costs of maskproduction, maskless lithography has severalother advantages including the capabilities ofproducing small batches of chips, easilymodifying a design during production, andimplementing kite specific corrections foraberrations in the imaging system.

Current EUV (extreme ultraviolet) lithographyuses a partially coherent imaging system toproduce the distribution of light necessary toprint features at high resolution. This can bemodeled with a bilinear transformation betweenthe pattern on the SLM and the intensity of lightat the wafer. Thus, knowing the signal sent tothe SLM, we can compute a digital simulation ofthe output of the system. Given a desired printedoutput, the challenge is to find an SLM patternwhich most closely produces the appropriateintensity. One way of quantifying this is tomeasure the squared error between the desiredintensity image and the intensity image which

results from a given SLM configuration. Theproblem is then to minimize the error by varyingthe input signal.

Treating each pixel in the SLM as a variable(or a pair of variables for complex SLMS), wehave a nonlinear optimization problem. It turnsout that an expression for the gradient can bederived for this error function, and this gradientis only about twice as expensive to compute asthe output intensity. Therefore, algorithms suchas conjugate gradients can be used to search for aminimum. The main difficulty with this ap-proach is that this problem seems to contain afairly high density of local minima. Our nexttask is to devise constraint techniques whichyield better results for this type of function aswell as better techniques of producing initialestimates of the solution. Improvements in bothof these areas will hopefully yield solutions ofbetter quality with less computation. It is worthnoting, however, that the lithography industry isinterested in even seemingly marginal improve-ments, since the number of chips produced islarge and costs are high. Hence, our algorithmmight be useful as a method of slightly improv-ing the efficiency of circuits designed withcurrent techniques.

71


Linearization of a MicromechanicalMicromirror Using a DSP Chip Work in Progress

Chuck h4cConaghy, Abe Lee

A Micromechanical Micromirror has beenfabricated to be used as an optical phase shifterin an interferometry application. The mirror is 1mm x 1 mm and moves a total distance of 1500nanometers. Because the electrostatic actuatorswhich drive the mirror have a somewhat nonlin-ear transfer function of distance moved vs. drivevoltage, it was decided to use a control system tolinearize the transfer function. The linearizationscheme is based on a built in capacitance posi-tion circuit couple to a Digital Signal Processor.

Currently, the system consists of a table look-up of position information. The DSP circuitdigitizes and incoming ramp and outputs thenon-linear function that results in the lineariza-tion of the mirror position. Work is currentlybeing done to use the capacitance data to peri-

72

odically update the transfer function. Signalprocessing must be done to determine the trans-fer function from the capacitance data.

The mirror position is a nonlinear functionof drive voltage bof properties of which drivethe mirror, Consequently, in. The DSP circuitdigitizes an incoming ramp and puts outsample rates are in the kHz range with thetotal ramp time on the order of 500 mS. Bothrecursive least squares and adaptive FIRschemes are being explored. Some initial workhas been done with MATLAB. Schemes thatare most easily implemented with the Ti DSPchip are being evaluated. Data will be pre-sented showing how each of the approaches fitthe capacitance data and how these can beused to generate the look-up table.

I!illSIGNAL AND IMAGING SCIENCES WORKSHOP + 1997

Signal Processing Requirements for Landmine Detection

David Eimerl

74


Sensitive Optical Detectors for Distance Moving Objects

David Eimerl

75


TANGO

SPA CE SHU~ZZE


Overview of the TANGO Space Shuttle Experimentand the Optical Imaging Diagnostic

Karla Hagans

An overview of the upcoming Tango space shuttle experiment will be given. Background for theoptical imaging diagnostic will be discussed.

79


Optical Design and Image Processing forthe TANGO Space Shuttle Experiment

Nicole A401au

The optical imaging diagnostic that is being designed and built for the upcoming TANGO spaceshuttle experiment will be described. The image processing involved in achieving the position-velocity estimation will be discussed and data frorr, I Preliminary test setup will be presented.

80


Rotational Dynamic Surface Imaging for the TANGO Space Shuttle Experiment

J. V. Candy

The estimation of the rotational dynamics(angle and position) of a surface imaged as partof the TANGO space shuttle experiment sched-uled for launch next year is discussed. An initialimaging of the surface indicates that a set ofmachinery arcs provide a deterministic featurewhich can be exploited to extract the rotationaldynamics of the surface. This surface image is

obtained from a CCD array and processed toenhance the features of interest. After the pre-processing is completed, the image space isthen transformed to the angle/position spaceusing the two-dimensional Radon transform.Once in Radon space, the major features ofinterest are estimated and utilized to extractthe desired information.

81


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