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Hyperspectral Imaging Improves Food Inspection June / 2012 Hyperspectral Imaging Improves Food Inspection
HyperspectralImaging
Improves Food Inspection
June / 2012
June/1
2Food Inspection • Ultrafast Lasers • Fiber Devices
HyperspectralImaging
Improves Food Inspection
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June 2012
t TABLE OF CONTENTS
16 | TECH NEWSPhotonics Spectra editors curate the most significant photonics research and technology headlines of the month – and take you deeper inside the news. Featured stories include:
• Elementary quantum network realized • Superradiant laser holds bright future• Plasmonic material bridges photonics, electronics gap
28 | FASTTRACKBusiness and Markets
• Innovate responsibly to weather tough economic times• Convention contest shines light on Israeli startups
41 | GREENLIGHT• Spinach may hold key to understanding photosynthesis• “Sweet spot” could help bring organic solar cells to market• Ultrathin solar cells for stretchable applications
10 | EDITORIAL
74 | PEREGRINATIONSLaser swarm could swat asteroids away
NEWS & ANALYSIS
COLUMNS
65 | BRIGHT IDEAS
71 | HAPPENINGS
73 | ADVERTISER INDEX
DEPARTMENTS
THE COVERDavid Bannon and Christopher Van Veen ofHeadwall Photonics Inc. discuss hyperspectralimaging’s evolving role in the food and agriculture sector, beginning on page 44. Design by Senior Art Director Lisa N. Comstock. Images courtesy of Headwall Photonics Inc.
16
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Photonics Spectra June 20124
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PHOTONICS: The technology of generating and harnessing light and other forms of radiantenergy whose quantum unit is the photon. The range of applications of photonics extendsfrom energy generation to detection to communications and information processing.
Volume 46 Issue 6
www.photonics.com
44 | HYPERSPECTRAL IMAGING GETS STAMP OF APPROVAL FOR FOOD PROCESSING
by David Bannon and Christopher Van Veen, Headwall Photonics Inc.A technology that began as a reconnaissance tool has moved into the sphere of foodprocessing and inspection, remote sensing of agricultural land, and plant studies.
50 | LEDs LOWER COSTS, BOOST CROPS INSIDE GREENHOUSESby Lynn Savage, Features EditorCompared to incandescent lighting, LEDs offer more wavelength-specific operation, longer life, lower temperature and cost, and design flexibility.
54 | MODELING IMPROVES FIBER AMPLIFIERS AND LASERSby Rüdiger Paschotta, RP Photonics Consulting GmbHFor developing active fiber devices with the best performance for the lowest cost, numerical modeling is essential.
57 | FEL PULSES AND ULTRAFAST LASERS TEAM UP TO EXPLORE NEW FRONTIERS
by Alan R. Fry, SLAC National Accelerator Laboratory, and Marco Arrigoni, Coherent Inc.Free-electron x-ray laser sources in tandem with ultrafast optical lasers enable ground-breaking experiments in atomic, molecular and materials science.
60 | INTERFEROMETER KEEPS OPTICS SHOP ON TRACKby Mike Zecchino, 4D Technology Corp. The vibrations from a new streetcar line will not disrupt the testing and assembling of optics on the University of Arizona campus, thanks to dynamic interferometry.
PHOTONICS SPECTRA ISSN-0731-1230, (USPS 448870) ISPUBLISHED MONTHLY BY Laurin Publishing Co. Inc., BerkshireCommon, PO Box 4949, Pittsfield, MA 01202, +1 (413) 499-0514; fax: +1 (413) 442-3180; e-mail: [email protected]. TITLE reg. in US Library of Congress. Copyright ® 2012by Laurin Publishing Co. Inc. All rights reserved. Copies of Pho-tonics Spectra on microfilm are available from University Mi-crofilm, 300 North Zeeb Road, Ann Arbor, MI 48103. PhotonicsSpectra articles are indexed in the Engineering Index. POST-MASTER: Send form 3579 to Photonics Spectra, Berkshire Com-mon, PO Box 4949, Pittsfield, MA 01202. Periodicals postagepaid at Pittsfield, MA, and at additional mailing offices. CIRCU-LATION POLICY: Photonics Spectra is distributed withoutcharge to qualified scientists, engineers, technicians, and man-agement personnel. Eligibility requests must be returned withyour business card or organization’s letterhead. Rates for oth-ers as follows: $122 per year, prepaid. Overseas postage: $28surface mail, $108 airmail per year. Inquire for multiyear sub-scription rates. Publisher reserves the right to refuse nonquali-fied subscriptions. ARTICLES FOR PUBLICATION: Scientists,engineers, educators, technical executives and technical writersare invited to contribute articles on the optical, laser, fiber optic,electro-optical, imaging, optoelectronics and related fields.Communications regarding the editorial content of PhotonicsSpectra should be addressed to the managing editor. Con-tributed statements and opinions expressed in Photonics Spec-tra are t hose of the contributors – the publisher assumes noresponsibility for them.
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FEATURES
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Photonics Spectra June 2012
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e EDITORIAL COMMENT
Fit to eat and plenty of it are two characteristics universally desired of the food we eat,but they often go unmet around the world. Now, a growing number of technologiesrooted in photonics are ripe and ready to support demands for a safe and sufficient
food supply for the world’s 7 billion inhabitants.
Meeting the repast requirements of a hungry world requires both a great deal of space andadequate growing conditions. Where growing seasons are short, some specialty crops canbe produced under artificial lighting such as incandescent and fluorescent bulbs. Featureseditor Lynn Savage tells us that, although both have been used, they are inefficient andcostly, and they emit undependable spectra. State-of-the-art LED lighting, however, isgaining traction in crop production, especially in remote areas without dependable year-round sunlight or where specialty crops are in demand. In the article “LEDs Lower Costs,Boost Crops Inside Greenhouses,” beginning on page 50, we look at how LED lighting isbeing used all over the globe – and even beyond.
Although LED lighting addresses the issue of quantity, an inspection method evolved frommilitary satellites and reconnaissance technology is being applied to food quality concerns.In the article “Hyperspectral Imaging Gets Stamp of Approval for Food Processing,” be-ginning on page 44, David Bannon and Christopher Van Veen of Headwall Photonics de-fine the promise of hyperspectral imaging across many applications, including in-line pro-cessing and inspection of everything from strawberries and apples to poultry and seafood.
Also in this issue• “In the short time of their existence as open-source research tools, free-electron x-ray
lasers such as the Linac Coherent Light Source have offered a versatile and powerfulmeans of pushing the frontiers of atomic, molecular and materials sciences,” write AlanFry of SLAC National Accelerator Laboratory and Marco Arrigoni of Coherent Inc.Their article, “FEL Pulses and Ultrafast Lasers Team Up to Explore New Frontiers,” begins on page 57.
• “Working with a numerical model is the best way to learn how fiber devices work, howto optimize their designs and what their limitations may be,” writes Rudiger Paschotta of RP Photonics Consulting GmbH. In the article “Modeling Improves Fiber Amplifiersand Lasers,” beginning on page 54, Paschotta tells us that, although fiber amplifiers andlasers offer interesting advantages over more traditional laser types, the performance details often are more complicated than for bulk lasers as a result of strong saturation effects, consequences of a high laser gain and some peculiarities of quasi-three-levellaser transitions.
• The Modern Streetcar Project in Tucson, Ariz., was designed to be a sustainable trans-portation option connecting the city center, the University of Arizona, the Arizona HealthSciences Center and several residential, historic and shopping districts, according toMike Zecchino of 4D Technology Corp. The project sounded good for the community at large but worried the staff at the National Optical Astronomy Observatory (NOAO). In the article “Interferometer Keeps Optics Shop on Track,” beginning on page 60,Zecchino tells how dynamic interferometry helped the NOAO optics lab beat the vibration.
Meanwhile …We’re pulling together our annual List Issue industry snapshot. We have asked for yourthoughts on essential reading for people in photonics, for the biggest “eureka” moment ofyour career, and for the funniest thing you’ve ever seen in the lab – your responses havebeen enlightening, for sure. Look for your answers in the August issue.
Editorial Advisory Board
Dr. Robert R. AlfanoCity College of New York
Walter BurgessPower Technology Inc.
Dr. Michael J. CumboIDEX Optics & Photonics
Dr. Timothy DayDaylight Solutions
Dr. Donal DenvirAndor Technology PLC
Patrick L. EdsellAvanex Corp.
Dr. Stephen D. FantoneOptikos Corp.
Randy HeylerOndax Inc.
Dr. Michael HoukBristol Instruments Inc.
Dr. Kenneth J. KaufmannHamamatsu Corp.
Brian LulaPI (Physik Instrumente) LP
Eliezer ManorShirat Enterprises Ltd., Israel
Shinji NiikuraCoherent Japan Inc.
Dr. Morio Onoeprofessor emeritus, University of Tokyo
Dr. William PlummerWTP Optics
Dr. Richard C. PowellUniversity of Arizona
Dr. Ryszard S. RomaniukWarsaw University of Technology, Poland
Samuel P. SadouletEdmund Optics
Dr. Steve ShengTelesis Technologies Inc.
William H. ShinerIPG Photonics Corp.
John M. StackZygo Corp.
Dr. Albert J.P. TheuwissenHarvest Imaging/Delft University
of Technology, Belgium
Kyle VoosenNational Instruments Corp.
10 Photonics Spectra June 2012
Impacting Our Food Supply: Good, Enough
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Welcome to
Photonics Spectra June 201212
Photonics Media’s industry-leading site features the latest industry news and events from around the world.
2013 Prism Awards – Call for Entries!The Prism Awards for Photonics Innovation, a joint collaborationbetween Photonics Media and SPIE, is a leading internationalcompetition celebrating innovation and honoring new product invention.
Applications are being accepted until Sept. 14, 2012. Enter to win – see if your product measures up!
Join Us for a Free Webinar2012 Webinar Series - Expert Briefings
Advances in Biomedical PhotonicsThursday, July 19, 2012 - 1 p.m. EDT/ 10 a.m. PDT/ 5 p.m.GMT/UTC
Photonics Media will host Lihong V. Wang, PhD, Gene K.Beare Distinguished Professor, Optical Imaging Laboratory,Department of Biomedical Engineering, Washington University,St. Louis. Wang will speak on "Photoacoustic Tomography: Ultrasonically Breaking Through the OpticalDiffusion Limit." Photoacoustic tomographycombines optical and ultrasonic waves via the
photoacoustic effect, providing in vivo multiscale nonionizing func-tional and molecular imaging. To register, visit:Photonics.com/Webinars
In case you missed it …
2012 Webinar – Expert Briefings Novel Infrared Sensors for Medical, Industrial and Homeland Security Applications
Speaker: Dr. Hooman Mohseni, associate professor, Electrical Engineering and Computer Science, Northwestern University.Learn how Northwestern's Bio-Inspired Sensors and Optoelectronics Lab (BISOL) developed novel IR imagers based on carriercompression and nano-injection technology.
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The latest research on optical engineering and applications, solar energy, nanotechnology, and organic photonics
Location San Diego Convention CenterSan Diego, California, USA
spie.org/aboutop
Conference dates 12–16 August 2012
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Conferences- Nanoscience + Engineering- Solar Energy + Technology- Organic Photonics + Electronics- Optical Engineering + Applications
2012
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Photonics Spectra June 2012
n Lasers for Medical Device Manufacturing
The medical device manufactur-ing industry is focusing moreand more on laser sources thatenable higher throughput andsmaller feature size while reduc-ing upfront capital cost andcost-of-ownership over time,and in addition offer a signifi-cantly longer lifetime.
n Fiber Optic Components for Medical Devices
Optical fiber processing technologies play a vital role from research to large-volume manufacturing in optical fiber-based components for medical devices.These components range from catheters and endoscopes to fiber optic probes for medical imaging and laser deliveries.
n Seeing the Light with Beam ProfilingOne crucial part of ensuring a quality laser process is laser characterization, including laser power/energy measurement, spatial beam profiling and temporalpulse shape measurement. Analyzing the data and applying it are where the fullbenefit of laser characterization can be realized.
n Electronics in Modern Process Control SpectroscopyIn spectrometer process control, the detector array and the related readout electronics are often more crucial to a successful application, and a large signal-to-noise ratio in combination with a high dynamic range are well sought-after characteristics.
n Metrology for Aspheric OpticsAsphere measurements have to be faster, switching from one technique to another has to be done in less time, and more readings are needed to char -acterize more complex surfaces. Tech -nique improvements and integration of measurement capability into asphere design software can help.
You'll also find all the news that affectsyour industry, from tech trends and market reports to the latest productsand media.
In the July issue of
Photonics Spectra …
Check out a sample of the new digitalversion of Photonics Spectra magazine at www.photonics.com/DigitalSample. It’s a whole new world of information forpeople in the global photonics industry.
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Elementary quantum network realizedond atom. The second atom can then sendthe information back to the first, or act asa hub to any number of networked atoms.
The network consists of two coupledsingle-atom nodes that transfer informa-tion through exchanging photons. Theatoms are embedded in optical cavitiescomposed of highly reflecting mirrors.Photons emitted by the atoms can be directed and controlled in very specific ways.
One challenge lay in trapping the atomin the cavity, which was accomplished byusing finely tuned lasers without disturb-ing the atom. From this, the scientistsproved that they could control the emis-sion of the atom, store information on aspecific photon and transfer it to anotherphoton after a storage time. The two nodesin the experiment were in two labs, sepa-rated by a distance of 21 m and connectedvia a 60-m optical fiber.
“We are convinced that much larger dis-tances are possible,” Ritter told PhotonicsSpectra. “One ultimate limit, however, isthe attenuation in the optical fiber. If thedistance becomes so large that the proba-bility for the photon to arrive at the othernode becomes small, efficient quantumstate transfer or remote entanglement be-comes impossible.”
When asked what challenges lie aheadto achieve a quantum Internet, Ritter saidthat it would depend on what one wouldexpect from such an Internet.
“I think there is no clear definition yet,”he said. “What is obvious is that, for alarge-scale quantum network, one willneed more than two nodes. Our approachcertainly supports this, as our networknodes are universal. Nevertheless, this is atechnological challenge, considering thatthe lasers, optics and electronics for con-trolling one network node currently fill awhole laboratory. We plan on improvingall characteristics of our single-atom net-work nodes.”
Besides improving the characteristics oftheir network nodes, the scientists hope toincrease storage time.
“We would like to increase the storagetime by several orders of magnitude bytransferring the atomic qubit to magnetic-
NEWSTECH
Photonics Spectra June 201216
A closer look at the most significant photonics research and technology headlines of the month
A cavity-based quantum network. In the envisaged architecture (top), many single-atom nodes are connected by single-photon links. Here, the scientists explore the universal properties of a system produced by connecting two nodes (middle; A and B) within this configuration. Details of the nodes and connections are shown in the lower part of the figure. The two identical nodes are located in independent labs connectedby a 60-m optical fiber (1). Each node consists of a single rubidium atom (2) in an optical dipole trap at thecenter of a high-finesse optical cavity (3). Quantum state transfer between the atoms and remote entanglementcan be achieved via exchange of a single photon (4), with the quantum information encoded in the internalstate of the atom and the polarization of the photon. Both the production of a photon (node A) and its storage (node B) are achieved via a coherent and reversible stimulated Raman adiabatic passage. Courtesy of Dr. Stephan Ritter, MPQ.
Left: Single atoms form thenodes of an elementaryquantum network in whichquantum information istransmitted by the con-trolled exchange of singlephotons. Courtesy of Andreas Neuzner, MPQ.
GARCHING, Germany – Two single-atomnodes have been used to send, receive andstore quantum information using photons,a quantum information-sharing milestone.
“We have realized the first prototype of a quantum network,” said Dr. StephanRitter of Max Planck Institute of QuantumOptics (MPQ).
For a quantum network to be useful, theexchange of information must be revers-ible. This is difficult because quantum in-formation is very fragile and cannot becloned. A breakthrough in solving this
problem was achieved by researchers ledby professor Gerhard Rempe of MPQ.Their research appeared in the April 12issue of Nature (doi: 10.1038/nature11023).
Unlike classical bits, which are binary, a quantum bit (qubit) can represent a su-perposition of both a 1 and a 0 at the sametime. Information can be transmitted, qubitby qubit, from one atom to another bymapping its quantum state onto individualphotons. The photons travel through afiber optic cable and are stored in the sec-
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field-insensitive ‘clock states,’ ” Rittersaid. “Currently, the storage time is mainlylimited by residual magnetic field fluctua-tions.”
The scientists also are working on ele-ments of a quantum repeater scheme,
which they hope will enable the transfer of quantum information over very largedistances.
“Entanglement of two systems sepa-rated by a large distance is a fascinatingphenomenon in itself,” Ritter said. “How-
ever, it could also serve as a resource forthe teleportation of quantum information.One day, this might not only make it pos-sible to communicate quantum informa-tion over very large distances, but mightenable an entire quantum Internet.”
17Photonics Spectra June 2012
Superradiant laser holds bright promiseBOULDER, Colo. – A new “superradiant”laser that traps 1 million rubidium atomsinto a 2-cm space between two mirrorsproduces a deep-red laser beam that couldboost the performance of the most ad-vanced atomic clocks, communicationsand navigation systems, and space-basedastronomical instruments.
Scientists at JILA, a joint institute ofthe National Institute of Standards andTechnology (NIST) and the University ofColorado at Boulder, developed the proto-type, which has the potential to be 100 to 1000 times more stable than the bestconventional visible lasers. The researchappeared in the April 5 issue of Nature(doi: 10.1038/nature10920).
“The laser we built is not particularlystable or narrow in frequency,” physicistJames Thompson of JILA/NIST told Pho-tonics Spectra. “Mainly, our system exper-imentally demonstrates key physics thatmight allow for future lasers that would beorders of magnitude more narrow in fre-quency than the best lasers of today.”
The device synchronizes the rubidiumatoms with an engineering techniquecalled “phase arrays,” in which electro-magnetic waves from a large group ofidentical antennas are carefully synchro-nized to build a combined wave with spe-cial useful features that are not otherwisepossible. The scientists cooled the rubid-ium atoms to 20 μK with a laser and levi-tated them using a one-dimensional stand-ing wave of light between two finessemirrors, Thompson said.
One set of 780-nm lasers was used tooptically pump the atoms into a particularquantum state that is very stable if nothingelse is done. When a second laser was in-troduced, the atoms decayed from this sta-ble state to a lower state with the emissionof photons into a mode of the optical cav-ity formed by the mirrors.
“The key is that the photons escape veryquickly from the mirrors before they havea chance to act back on the atoms toomuch,” he said. “If they stick around fortoo long, vibrations of the mirrors cancause the frequency of the laser to becomesmeared out – the same limiting factor onthe most frequency narrow lasers that canbe built.”
Because the atoms are constantly ener-gized and emit synchronized photons, onthe average very few – less than one pho-ton, in fact – stick around between the mirrors.
This average, calculated by the scientistsbased indirectly on the laser beam’s outputpower, is enough to maintain an oscillatingelectric field to sustain the atom’s synchro-nized behavior. Almost every photon es-capes before it has a chance to bouncearound the mirrors and disrupt the syn-chronized atoms, which in standard laserscauses laser frequency to wobble.
“The idea of operating at less than onephoton was to really hammer home theidea that one can build a laser in whichnearly all of the phase information isstored within the atoms (or gain medium),”Thompson said. “When this happens, thelasing frequency becomes highly inde-pendent of the frequency of the opticalcavity. This might be key for reducing the impact of fundamental thermal mirrornoise on the world’s most narrow fre-quency lasers at JILA, NIST and otherplaces around the world.”
Just as important, he added, is the factthat such lasers could be moved out of thevibration-controlled laboratory and intoreal-world applications.
“This was just the first step and is really a physics model of what you wouldreally like to build in a system such as JunYe’s strontium atomic clock system here at JILA,” he said. “Such a laser might im-
prove the stability and accuracy of the bestatomic clocks by several orders of magni-tude.”
Superradiant lasers also may enable pre-cise measurements at very long distances.
“For instance, a millihertz linewidthlaser would have a coherence length oforder the Earth-sun separation, while thebest lasers we have now only have coher-ence lengths of order the Earth to moonseparation,” Thompson said. “One candream of looking for Einstein’s gravitywaves or even using the long coherencelength to synchronize distant optical tele-scopes like Hubble in order to build tele-scopes with unprecedented angular resolu-tion, such as might be helpful in searchingfor planets.”
For the superradiant laser design toreach its full stability potential and to beof practical use, Thompson stresses that it
JILA’s superradiant laser traps 1 million rubidiumatoms in a space of about 2 cm between two mir-rors. The atoms synchronize their internal oscilla-tions to emit laser light. Courtesy of Burrus/NIST.
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will need to be re-created using differentatoms, such as strontium or ytterbium,which both have very long-lived excitedoptical states that are better suited for ad-vanced atomic clocks.
Next, the scientists will explore whether
it is possible to build hybrid passive andactive optical atomic clocks that are highlyadaptable to changing vibration environ-ments while still maintaining accuracy.
“We also would like to further under-stand the intrinsic stability properties of
these lasers,” he said. “There are also in-teresting questions related to using thistechnique for realizing special nondestruc-tive measurements that might operate at ornear the standard quantum limit on quan-tum phase measurement.”
t
70 Yearsof OpticalInnovation
1942 - 2012
TECHNEWS
Plasmonic material bridges photonics, electronics gap WEST LAFAYETTE, Ind. – A thin film oftitanium nitride was coaxed into transport-ing plasmons, becoming the first nonmetalto be added to the short list of surface-plasmon-supporting materials and bridgingthe gap between photonics and electronics.The nonmetal could pave the way to anew class of optoelectronic devices thathave unprecedented efficiency and speed.
Until recently, the best candidates forplasmonic materials were gold and silver.However, these noble metals are not com-patible with standard silicon manufactur-ing technologies, limiting their use incommercial products. Of the two metals,silver has the best optical and surface plas-mon properties; however, it forms semi-
continuous or grainy thin films and de-grades in air, which results in optical sig-nal loss. Because of these properties, itsapplication in plasmon technologies islimited.
Now, researchers at Purdue Universityare studying the plasmonic capabilities oftitanium nitride, a ceramic material usedto coat metal surfaces such as medical im-plants or machine tooling parts. Titaniumnitride was chosen as a test material be-cause it is easy to manipulate in manufac-turing, and it can be easily integrated intosilicon semiconductor devices. The non-metal also can be grown one crystal at atime, allowing it to form highly uniform,ultrathin films.
“When we started to think about alter-native plasmonic materials, we turned to several promising candidates, amongwhich are highly doped oxides (but thesewill be operating in the near-infrared, notvisible, region) and intermetallics,” Alex-andra Boltasseva, the lead researcher, toldPhotonics Spectra. “The choice of tita-nium nitride as the first studied materialwas not accidental. This material is knownto have a golden luster. And since it lookslike gold, we expected to find opticalproperties that resemble those of gold.”
To measure its plasmonic capabilities,Boltasseva’s team laid a very thin film oftitanium nitride evenly over a sapphiresurface and discovered that titanium ni-
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tride transmits plasmons about as well asgold does, but not as efficiently as silverunder ideal conditions. The scientists arenow seeking to improve the performanceof titanium nitride using molecular beamepitaxy, a manufacturing technique thatenables the crystal-by-crystal growth ofsuperlattices.
The investigators believe that titaniumnitride could outperform noble metals incertain devices based on transformationoptics and metamaterials, such as thosewith hyperbolic dispersion, in the visibleand near-IR regions.
“Titanium nitride could provide per-formance that is comparable to that of
gold for plasmonic applications (includingplasmonic waveguides and nanoparticles)and can significantly outperform gold and silver for transformation optics andsome metamaterial applications in the visible and near-infrared regions,” Boltas-seva said.
Next, the scientists plan to move frommaterial to devices to better understandmetamaterial structures that have opticalperformance acceptable for real-life appli-cations and that are compatible with stan-dard semiconductor processing lines, she said.
“We have found that titanium nitride isa promising candidate for an entirely newclass of technologies based on plasmonicsand metamaterials,” Boltasseva said. “Thisis particularly compelling because surfaceplasmons resolve a basic mismatch be-tween wavelength-scale optical devicesand the much smaller components of inte-grated electronic circuits.”
The research appeared in Optical Mate-rials Express (http://dx.doi.org/ 10.1364/OME.2.000478).
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(a) Excitation by light of a surface plasmon polariton on a thin film of titanium nitride. (b) Atomic force microscopy image of the surface of titanium nitride film. (c) Scanning electron microscopy image of titanium nitride thin film on sapphire. Courtesy of Alexandra Boltasseva, Purdue University/Optical Materials Express.
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VIENNA – A new method of Raman spec-troscopy uses laser light to detect chemi-cals inside a container from a distance ofmore than 100 m.
Laser light is scattered in a very specificway by various substances. This is thebasis of Raman spectroscopy and can beused to analyze the contents of a nontrans-parent container without opening it.
Scientists at Vienna University of Tech-nology (TU Vienna) used the technique tosee what was in certain containers, irradi-ating samples with a laser beam. When the light was scattered by the molecules of the sample, it changed its energy; e.g.,the photons transferred energy to the mol-ecules by exciting molecular vibrations,changing the wavelength of the light and,thus, its color. By analyzing the colorspectrum of the scattered light, the re-searchers determined what kind of mole-cules scattered it.
“Until now, the sample had to be placedvery close to the laser and the light detec-
tor for this kind of Raman spectroscopy,”said Bernard Zachhuber of TU Vienna.
His technological advancements en-abled measurements to be made over longdistances.
“Among hundreds of millions of pho-tons, only a few trigger a Raman-scatter-ing process in the sample,” he said.
These light particles scatter uniformly inall directions. Only a tiny fraction of themtravel to the light detector, and as much in-formation as possible must be extractedfrom this very weak signal. This can bedone using a highly efficient telescope andextremely sensitive light detectors.
The scientists collaborated with privatecompanies and with partners in publicsafety, including the Spanish GuardiaCivil, to apply their method to the ex-treme. With the help of the Austrian mili-tary, they tested frequently used explosivessuch as TNT, ANFO and RDX on theirtesting grounds.
The results proved successful. Even at
a distance of more than 100 m, the sub-stances could be detected accurately andreliably, said researcher Engelene H.Chrysostom of TU Vienna.
And when the scientists hid a sample ina nontransparent container, the laser beamwas scattered by the container wall, but asmall portion of the beam still penetratedthe box, exciting Raman scattering pro-cesses inside the sample.
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Photonics Spectra June 2012
Lasers find distant hidden explosives
Bernhard Zachhuber mounts optical elements of thespectrometer. Courtesy of TU Vienna.
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“The challenge is to distinguish thecontainer’s light signal from the samplesignal,” said scientist Bernhard Lendl.
This can be done using a simple geo-metric trick: The laser beam hits the con-tainer on a small, well-defined spot. Thelight signal emitted by the container stemsfrom a very small region, while the lightthat enters the container is scattered into amuch larger region. If the detector tele-scope is not aimed exactly at the point atwhich the laser hits the container, butrather just a few centimeters away, the
characteristic light signal of the contentscan be measured, instead of the signalcoming from the container.
The researchers’ new method couldmake security checks at airports a lot eas-ier, but they believe that applications arebroader than that. It could be used wher-ever it is hard to get close to the subject ofinvestigation – for studying icebergs or forgeological analysis on a Mars mission, forexample, or for a host of chemical indus-try applications.
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Photonics Spectra June 2012
The Raman spectroscope at TU Vienna.
Cold atoms in an optical lattice simulate grapheneZURICH – The creation of a tunable sys-tem of ultracold atoms within a honey-comblike structure similar to that found ingraphene may help identify the electronicproperties of materials that have yet to bediscovered.
Professor Tilman Esslinger of the Institute of Quantum Electronics at ETHZurich and his team loaded ultracoldpotassium atoms into a special latticestructure made of laser light. Using a setof orthogonal and precisely positionedlaser beams, they created a variety of two-dimensional light field geometries, in-cluding graphene’s honeycomb structure.
They cooled several hundred thousandpotassium atoms inside a vacuum chamberto temperatures just above absolute zero,which brought the atoms to rest, thenplaced the optical lattice over the cloud of atoms.
“Designing a structure like this with
laser beams is similar to creating a beauti-fully regular pattern in a lake by simulta-neously throwing several pebbles in atcarefully chosen positions,” Esslinger said.
Shortly after the discovery of graphene,scientists raised the question as to whatwould happen if the lattice structure ofgraphene could be modified. Researchershave tried to simulate graphene in experi-ments, but until now had been unsuc-cessful.
The behavior of electrons in the vicinityof the so-called Dirac point is central tounderstanding the special properties ofgraphene. At the Dirac point, the valenceand conduction band of graphene touch ina linear crossing, where electrons behavelike massless particles traveling at the effective speed of light.
Esslinger and his team reproducedgraphene’s distinctive Dirac points in a 2-D honeycomb lattice by criss-crossing
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the laser beams. The lattice contained potas-sium atoms, which played the role of elec-trons in graphene.
Once the potassium atoms were trappedin an optical lattice, they began to act like electrons in the crystal structure of
graphene. Upon accelerating the atomswith a magnetic field gradient, the re-searchers could identify Dirac points inthe optical lattice. They observed that theatoms behaved like massless particles nearthe Dirac points, just as the electrons did
in graphene, and that they can move fromthe valence to the conduction band, sincethe bandgap vanishes.
It is this transition to the higher bandthat the researchers observed in time-of-flight measurements. Once they switchedoff the laser beams, the optical honeycomblattice disappeared, and the atoms flewthrough the vacuum.
A short time afterward, an absorptionimage of the atomic distribution wastaken, which reconstructed the atomic tra-jectories.
Using the flexibility of the optical lat-tice setup, Esslinger’s team played withthe Dirac points, moving and mergingthem until they suddenly vanished. Theyalso observed that a slight change to thelattice symmetry restored the mass to the atoms.
“Using this method, it may become pos-sible to simulate the electronic propertiesof materials long before they can be physi-cally realized,” he said.
The work was described in Nature (doi:10.1038/nature10871).
What is left to be answered, however, iswhat is going to happen if there are stronginteractions between the atoms, a situationthat has not yet been attained for the elec-trons in graphene.
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Photonics Spectra June 2012
The density distribution of the potassium atoms measured after acceleration through Dirac points (left and center) and without Dirac points (right). The upper row shows the corresponding regions of the calculated band structure. Courtesy of Tilman Esslinger’s Research Group/ETH Zurich.
Laser built on a silicon chipSINGAPORE – A laser with a novel micro-loop mirror design fabricated on a siliconchip uses III-V semiconductor materials –a step forward for high-speed optical com-munications and interconnects on elec-tronic chips.
Active optical fibers with silicon pho-tonic chips carry much more informationfor data interconnects than copper cables.Silicon could be the material of choice forwiring lab-on-a-chip devices but for itspoor ability to emit light.
Now, scientists at A*Star Data StorageInstitute have built a laser on top of a silicon chip, bonding III-V semiconductormaterials to the device to provide opticalgain. Compared with conventional feed-back mirrors based on device facets, the new design promises enhanced operation.
“Integrated Si/III-V lasers can take advantage of low-loss silicon waveguideswhile addressing the problem of low light-emission efficiency that silicon devices
Scanning electron microscope image of the silicon-based microloop mirror. Light entering the waveguide fromthe left is guided around the loop and directed back into the laser structure. The inset shows the laser spotphotographed with an infrared camera. Courtesy of A*Star.
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typically have,” said researcher DorisKeh-Ting Ng.
Attaching a Si/III-V laser atop siliconrequires some difficult fabrication tech-niques, and device performances canweaken as a result. And because lasers require mirrors to maintain lasing action,such designs typically rely on the interfacebetween air and the semiconductor – thefacets of the chip. Unfortunately, suchmirrors are not perfect and further reduceoperation efficiency.
To improve on the drawbacks associ-ated with mirrors, the team designed themicroloop mirror, which guides light emit-ted from one end of the laser along thewaveguide, around a narrow bend andback into the device. The mirror at theother end of the device is still formed bythe interface with air so that laser radiation
can exit. The scientists achieved a light reflection efficiency of 98 percent withthis design.
More than 30 delicate, high-precisionfabrication steps were needed to build thedevice. The researchers plan to further enhance the laser by miniaturizing the device.
“Further improvements, for example, at the interface between the mirror and the lasing structure itself could lead toeven better performance,” Ng said. “Alaser with lower threshold and higher output power can possibly be achieved,leading to a potential solution to develophigh-speed and low-cost optical communi-cations and interconnects on electronicschips.”
The work appeared in Applied PhysicsLetters.
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Photonics Spectra June 2012
Many-body system beats computer in simulatingquantum dynamics
MUNICH – A recent experiment hasshown that a many-body system of ultra-cold atoms can be used as a quantum sim-ulator for experiments where classicalcomputers fail. This also allows physiciststo have a better understanding of how par-ticles tunnel, and it opens up new avenuesof study in condensed matter physics.
A group led by Immanuel Bloch of MaxPlanck Institute of Quantum Physics andof Ludwig Maximilians University Mu-nich has demonstrated that a quantum sys-tem can outperform classical calculationsby confining a gas of supercooled rubid-ium atoms to an optical lattice and follow-ing the relaxation behavior of the systemon a much larger timescale than any clas-sical method could handle.
An optical lattice formed by counter-propagating laser beams created a spatiallyperiodic polarization pattern through theinterference of the beams. The rubidiumatoms were trapped in the dark and lightareas of the lattice and became aligned ina regular pattern.
The atoms in the lattice were thengrouped in pairs into an optical superlat-tice by adding another light field withtwice the spatial period of the original lat-tice. This created a density wave state farfrom the system’s equilibrium point. Theatoms were allowed to tunnel along thespatial direction of the superlattice and tocollide with one another on their way backto thermal equilibrium, creating compli-cated many-body dynamics.
(a) Schematic shows how the atoms in an optical lattice relax from an excited density wave to a quasi-steadystate. (b) The experimental data (blue circles) is very much in line with the simulation’s data (black line). However, the experiment could track the system’s behavior for a much longer period of time. J = strength of tunnel coupling, t = time. Courtesy of Max Planck Institute of Quantum Physics.
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After the system returned to equilib-rium, as with a plucked string returning to rest, the system’s local density, tunnelcurrents and observable properties wereprobed for a variety of lattice heights andevolution times. They showed a rapid re-
laxation back to quasi-steady-state valuesand were in excellent agreement with pre-viously computed numerical simulations.
Classical computers can track many-body dynamics for a short period, and thisprovided a benchmark for the quantum ex-
periment. The timescale of the experimentwas much greater than that of the classicalsimulator’s predictions and could track theevolution of the system for far longer, giv-ing much more precise data for a longerperiod of evolution.
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Photonics Spectra June 2012
Laser mixing generates multifrequency lightSANTA BARBARA, Calif. – A ground-breaking laser mixing technique can ma-nipulate electron-hole collisions to createmany frequencies of light simultaneously.This mechanism for ultrafast light modula-tion has potential applications in high-speed optical communications.
Researchers at the University of Cali-fornia use a free-electron laser aimed at agallium arsenide nanostructure semicon-ductor to create a quasiparticle called anexciton, a bound electron-hole pair, in thematerial. Excitons occur when a semicon-ductor absorbs a photon. The excess energy excites an electron, causing it tojump into another energy level and to
leave behind a positively charged hole inthe energy level it left. The electron andhole are bound because of their mutual attraction.
Normally, the exciton would have asmaller energy than the original electronand hole, but the researchers use a secondlaser with a lower frequency to smash theelectron back into the hole with a greaterenergy than that with which it left. As aresult, the electron-hole recombinationemits photons at different frequencies thanthose it absorbed.
“It’s fairly routine to mix the lasers andget one or two new frequencies, said MarkSherwin, the lead researcher, a professor at
Benjamin Zaks (left) and Mark Sherwin. Courtesy of UCSB.
Artist’s rendition of electron-hole recollision. Near-infrared (amber rods) and terahertz (yellow cones)radiation interact with a semiconductor quantumwell (tiles). The near-IR radiation creates excitons(green tiles) consisting of a negative electron and apositive hole (dark-blue tile at center of green tiles)bound in an atomlike state. Intense terahertz fieldsfirst pull the electrons (white tiles) away from thehole and then push them back toward it (electronpaths represented by blue ellipses). Electrons period-ically recollide with holes, creating periodic flashesof light (white disks between amber rods) that areemitted and detected as sidebands. Courtesy ofPeter Allen, UCSB.
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UCSB and director of the university’s In-stitute for Terahertz Science and Technol-ogy. “But to see all these different newfrequencies, up to 11 in our experiment, isthe exciting phenomenon. I’ve never seenanything like this before.”
Each frequency generated by the elec-tron-hole recollision phenomenon corre-sponds to a different color, he added.
In terms of real-world applications, thetechnique can be used to transmit more in-formation at a faster rate by sending datathrough multiple channels – multiplexing– or it can be used for high-speed fre-quency modulation for a faster Internet.
“Think of your cable Internet,” saidBenjamin Zaks, a doctoral student atUCSB and lead author on a paper aboutthe work. “The cable is a bundle of fiberoptics, and you’re sending a beam with awavelength that’s approximately 1.5 mi-crons down the line. But within that beam,there are a lot of frequencies separated bysmall gaps, like a fine-toothed comb. In-formation going one way moves on onefrequency, and information going anotherway uses another frequency. You want tohave a lot of frequencies available, but nottoo far from one another.”
Because the laser currently used is thesize of a building, the researchers areforced to come up with a more practicalway to implement these findings. One solution is to use a transistor that modu-lates in the near-infrared to produce strongterahertz fields akin to those of the free-electron laser.
Sherwin hopes that his discovery opensup more electron-hole recollisions research.
“We have a unique tool ... which givesus a big advantage for exploring the prop-erties of fundamental materials. We justput it in front of our laser beams andmeasure the colors of light going out.Now that we’ve seen this phenomenon,we can start doing the hard work of put-ting the pieces together on a chip,” hesaid. “I want to continue working on it,but I’d like to see a lot of other peoplejoin in.”
Also contributing to the research, whichappears in the online issue of Nature, isR.B. Liu of The Chinese University inHong Kong.
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Apparatus used for electron-hole recollision experi-ments. Large flat and curved mirrors guide andfocus terahertz radiation, emitted in a different roomby one of the UCSB free-electron Lasers, through around cryostat window onto the sample (not visible).Smaller flat mirrors guide near-infrared radiationfrom the left, through a small hole barely visible atthe center of the curved mirror surface, through around cryostat window to the sample (not visible).Near-IR laser and sidebands caused by recollisionsin the sample exit through a second cryostat window(hidden), are reflected by the small round mirror onthe right and directed to a spectrometer (not visible).Courtesy of Alison McElwee, UCSB.
Thermal cloak hides heatPARIS – In a new approach to invisibilitycloaking, French researchers propose iso-lating or cloaking objects from sources ofheat – essentially “thermal cloaking.”
The method, developed by SebastienGuenneau and his colleagues at CentreNational de la Recherche Scientifique(CNRS), taps into some of the same prin-ciples as optical cloaking. Ultimately, itcould lead to novel ways to control heat inelectronics.
“Our key goal with this research was tocontrol the way heat diffuses in a mannersimilar to those that have already beenachieved for waves, such as light waves orsound waves, by using the tools of trans-
formation optics,” Guenneau said. Until now, cloaking research revolved
around manipulating wave trajectories,such as electromagnetic (light), pressure(sound), elastodynamic (seismic) and hy-drodynamic (ocean) waves. Guenneau’sstudy of heat, he points out, focuses on thephysical phenomenon of diffusion, ratherthan wave propagation.
“Heat isn’t a wave – it simply diffusesfrom hot to cold regions,” he said. “Themathematics and physics at play are muchdifferent. For instance, a wave can travellong distances with little attenuation,whereas temperature usually diffuses oversmaller distances.”
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The CNRS team designed its cloak sothat heat diffuses around an invisibility re-gion, which is protected from heat. The re-searchers also can force heat to concen-
trate in a small volume, which will thenheat up rapidly.
The ability to shield an area from heator to concentrate it is highly desirable for
a range of applications. Shielding nano-electronic and microelectronic devicesfrom overheating, for example, is one ofthe biggest challenges facing the electron-ics and semiconductor industries; thermalcloaking could have a tremendous impacton these sectors. As for the ability to con-centrate heat, this could prove useful tothe solar industry. On a larger scale andfar into the future, thermal cloaking couldbe helpful for protecting large computersand spacecraft.
Guenneau’s team is working to developprototypes of its thermal cloaks for micro-electronics, which are expected to beready within the next few months.
The method appears in OSA’s open-access journal Optics Express.
t TECHNEWS
Ashley N. [email protected]
This figure shows that the object in the center of the cloak (letters OSA) stays cold, while the heat diffuses elsewhere. The source of the heat, which is at a constant temperature of 100 °C, is on the left-hand side, while the material inside the invisibility region remains cold. Courtesy of Sebastien Guenneau, Institut Fresnel, CNRS/AMU.
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Innovate responsibly to weather tough economic times
Innovation doesn’t wait for the econ-omy to get better – and neither doesthe competition. New products provide
new revenue sources for businesses asthey look to continue growth following the “great recession.”
The economic ups and downs of thepast few years have been enough to forceany technology manufacturing businessinto making difficult choices about how to spend its money. The agonizingly slowpace of recovery has boardrooms aroundthe world worrying about the next quar-ter’s sales – never mind the next new product coming from R&D or product development.
At times like this, it is easy to drasticallycut back on new-product budgets in thename of riding through the rough patches,but smart companies are taking advantageof this time to leapfrog the competition andposition themselves for better economicdays to come. They know that innovationand the market that follows it don’t waitfor the economy to pick up.
Think long-termProduct development is one of several
business processes that take time. Turningoff investment will save expenses thisquarter but will cause potentially ruinousresults when business begins to take offagain in future quarters. It is crucial forcorporate management to think long-termwhen considering decreasing investmentin new products because neglect will re-sult in an extended downturn for the busi-ness, while innovative companies willbenefit from building new offerings today.
Additionally, technology manufactur-ing companies that placed value on main-taining their technical staff through the“great recession” already have the per-sonnel infrastructure in place to continueproduct innovation. Maintaining productinnovation keeps your engineering staffengaged and ready to tackle the growththat undoubtedly will occur.
Much of the development process can be done with minimal expense,
and product managers can work closelywith R&D and finance to identify less-expensive ways to develop products.Continual advances in communicationtools mean better collaboration betweengroups, and new software tools for mod-eling, development and simulation aswell as rapid prototyping speed up designcycles while lowering residual costs.
Innovate responsiblyResponsible product development
means focusing efforts around specificopportunities, backed by clear customerfeedback and market data. Although theoccasional “wildcat” idea may be consid-ered, product managers must prioritize
development efforts around projects withclear customer demand and strategic ben-efit. What products is the company miss-ing that are currently offered by the com-petition? What is missing that could putthis company ahead? What technologyimprovements do customers require toaddress the needs of their own customersand competition?
Given limited resources and ever-decreasing development time, the prod-uct development department must workclosely with sales and marketing toclearly define customer needs. It musttake advantage of its sales force’s experi-ence and customer network and workwith marketing to identify trends in its
28 Photonics Spectra June 2012
TRACKFAST
Leveraging sales and customer data, exploring innovativeengineering and manufacturing techniques, and takingadvantage of an international supply chain are just a few of the factors involved in new product development in today’s optics and photonics markets.
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customer interactions. Companies mustmine their databases and transaction his-tories for concrete customer behaviordata. In today’s “crowd sourcing” world,customers can even actively participate in product development through surveys,online forums and other direct methodsfor soliciting feedback. One thing nocompany can afford is to make productdecisions in the dark.
Responsible product developmentcomes with a price. At Edmund Optics,our team is constantly focusing on newproducts, and we have continually ex-panded our offerings over the past severalyears. Although we benefit from beingmostly a components company, our chal-lenge comes from responsibly expandingour inventory to meet the same servicerequirements on new products (roughly2000 every year) as we have for all ourproducts (which number above 26,250).
To achieve this balance, our team focuses on the following initiatives:
• Growth in market segments As withmost photonics companies, we benefitfrom optical applications in a variety of
industries, including the life sciences,machine vision, materials processing andresearch/academics. By introducing prod-ucts that address several industries, suchas filters and imaging lenses, we take ad-vantage of growth trends in some, suchas the life sciences, while hedging against
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Initiatives important for responsible product development during down times:
• Growth in market segments
• Coordination with supply chain
• Identifying manufac-turing efficiencies
declining trends in others, such as de-fense and semiconductors. Our team alsois doing more to work with sales to makesure that our new products have the rightpre- and postsales technical support forthe industries and applications. For exam-ple, our product line managers are spend-ing more time searching our opportunitydatabase to identify volume sales projectsthat could use a technical expert to assistin closing the deal.
• Coordination with supply chain Developing the right products is only partof the product manager’s job; forecastingdemand and working with purchasing tohave the right amount of stock on theshelves is another full-time job. This is especially true for our business because of our large and varied catalog, but giventoday’s tighter economy, all businessesmust be cash-conscious. Tying too muchinto one product means missing out onother opportunities, but not investingenough means disappointing prospects for a new product.
Fortunately, we were largely unaffectedby the recent flooding in Southeast Asia,but the dramatic increase in rare-earth material costs has pushed us to work withour supply-chain organization to leverageour vendor and supplier networks.
• Identifying manufacturing efficien-cies The booms and busts of recent yearshave wreaked havoc on manufacturing,both in our own factories and in those ofour suppliers. Without careful coordinationbetween product management and manu-facturing, new products can amplify thewaves of an already stormy sea. As newproducts come online, be sure to workclosely with your manufacturing engineersand technicians to identify best practicesfor streamlined production. Companieswith flexible practices and prototyping cellscan quickly incorporate new products intotheir mix, while still meeting any and allexisting product demand.
The root of the “Technology Age” restsin the fact that people want to do morewith less, and they want to do it faster andmore cheaply than they did last year. Forphotonics companies, new products meannew sales, new markets and new marketshare – both now and in the boom times to come.
Meet the authorTodd Sierer is director of product marketing at Edmund Optics in Barrington, N.J.; email:[email protected].
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RAMAT GAN, Israel – Small Israeli start-ups with technologies for retinal imaging,3-D wavefront analysis and particle analy-sis took the top prizes in the new 2012Startup Contest, held during the OpticalEngineering 2012 conference. The confer-ence and the contest were put on by theOptical Engineering chapter of SEEEI (theSociety of Electrical and Electronics Engi-neers in Israel) at Bar-Ilan University inlate March.
Applicants had to represent companiesor startups less than 5 years old that areregistered in Israel and that have no morethan $6 million in funding. In the firststage of the competition, applicants sub-mitted a short business plan summary;each submission was reviewed by severalevaluators, who then selected the finalists.
The second stage started with a plenarysession where each finalist had just sevenminutes to introduce the startup. This in-troduction was followed by a typical “ele-vator pitch.” The startups also got to dis-play posters during the conference’smorning plenary session, and interestedparticipants and the evaluators could askquestions and discuss the proposals withthe entrepreneurs.
Scores were calculated using four crite-ria: surveys, in which conference atten-dees selected the startup with the highestsuccess potential; official referee evalua-
tion of the elevator pitch and the posterpresentation; evaluation of the technologybehind the venture and related strategicplanning; and the business model andstrategy. The scores were approved by anevaluation committee and announced dur-ing a special contest awards session.
The six finalists were Kayon Technolo-
gies Inc., with its FiveSite laser diamondevaluator; PML-Innovative Particle-Moni-toring Technologies, with its particle moni-toring technology; OWLinx, with its free-space optical communications system;AdOM Advanced optical technologies Ltd.,with its retinal imager; Acrylicom, with itsEthernet over plastic optical fiber technol-
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Convention contest shines light on Israeli startups
The 2012 Startup Contest award ceremony panel, from left: professor Gabby Sarusi of Ben Gurion University,professor David Mendlovic of Tel Aviv University and Core Photonics, professor Liora Katzenstein of ISEMI Entrepreneurship College in Israel, Hananel Kvatinsky of Orbotech, Yossi Tendler of Ernst & Young, and Dr. Rami Finkler of SEEEI. Images courtesy of SEEEI.
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ogy; and JeruLux, with its WaveImager,which makes 3-D measurements of trans-parent and specular objects.
AdOM won first place, JeruLux tooksecond, and PML came in third.
Retinal imaging“Internal eye diseases – mainly age-
related macular degeneration, glaucomaand diabetic retinopathy – are currently irreversible in the sense that once visioncells are damaged, their condition cannotbe restored,” said Yosi Weitzman, founderand chief operating officer of AdOM. “Forthis reason, and since blindness causesenormous suffering and costs, early detec-tion of such conditions is highly valuable,considering there are various surgical andmedication therapies that are able to slowdown or even stop the progress of the dis-ease, once properly diagnosed.
“Nevertheless, the current technology for
proper diagnosis of those diseases – opti-cal coherence tomography [OCT] – is toocostly and lacks the availability required for reaching the growing population.”
AdOM’s multimodal retinal imager usesnext-generation OCT technology to extendto the larger market of optometrists, gen-eral ophthalmologists and screening cen-ters the diagnostic capabilities that cur-rently are available only to retinal experts.
Spectral domain technology presentsimportant improvements over traditionalOCT, but OCT remains limited and costly,according to the company’s contest pro-posal. AdOM’s technology is a new OCTengine that is based on the same funda-mental physical principles as OCT, butnew implementation extends its perform-ance. A conventional fundus camera canbe equipped with a structural imagingmodule for less than 20 percent of theend-user cost of a modern OCT system,but the performance remains competitive.
OCT uses raster-scanned images;AdOM’s retinal imager combines full-fieldimages with oximetry, producing a widefield of view, high resolution, high-speedstructural imaging and vasculature exami-nation, eliminating angiography.
The technology is in the proof-of-concept stage. “We plan to release a pre-clinical version next year that will support regulatory requirements in the US and EU [European Union], and start saleswhen the product is approved, [an] esti-mated six months later,” Weitzman said.
The company plans to incorporate meta-bolic imaging into the basic structural im-aging product to enhance early detectionof eye disorders.
3-D wavefront analysisThe WaveImager from JeruLux is a new
3-D analysis method that enables contact-less, precise measurement of the wave-front (3-D slopes) exiting transparent objects and specular surfaces, using colorcoding inside classical 2-D imaging sys-tems. The method is patent-pending.
It allows simultaneous wavefront analy-sis and object imaging at relatively low costwith no moving parts or interferometry.The real-time image processing is straight-forward (color = 3-D slope). The device’sspatial X,Y resolution is equal to the cam-era’s image sensor resolution, and its sloperesolution equals the image sensor’s dy-namic range. It offers high resolution forcontinuous surfaces – down to nanometerscale – and a large depth of focus.
“It is basically a wavefront analyzer butwith specific characteristics that make it attractive to applications without satisfyingsolution today,” said Elie Meimoun of Jeru-Lux in Jerusalem. Among other features,Meimoun added, the technology enables simultaneous object imaging and wavefrontanalysis, which allows mechanical featuresand their optical properties to show up;also, high spatial (X,Y) and angular resolu-tion is possible, because classical imagingdata and wavefront data both are containedin each of the pixels. “[It is] applicable toarea sensing as well as to line scanning; noother technology is capable of measuringfull 3-D data with a line sensor.”
Target markets include ophthalmologyand image sensor fabrication, but thestartup’s plans do not stop there. “Thetechnology can be successfully integratedinto diverse markets, from tiny objects(MEMS, microlens arrays) to ophthalmicproducts (progressive lenses, IOL, cornea)and even to the huge mirrors used in thethermo-solar industry,” Meimoun noted.
Particle analysisPML’s automatic continuous online
particle analyzer offers information onparticle-size distribution down to thenanoscale, particle concentration and particle clustering. It was designed for inspection and monitoring in liquids andgases for use in air and water monitoring,cleantech environments, cement manu-facturing, and the pharmaceutical and
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Contest entrants displayed posters featuring their proposals.
Dr. Meir Teichner, CEO of PML-Innovative Particle-Monitoring TechnologiesLtd., accepts the third-placeaward on behalf of hiscompany.
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food industries. Future applications include nanoparticle-basedsensors for the automobile industry.
The analyzer is based on a patented method of interaction be-tween particles and a unique structured non-Gaussian “dark” laserbeam. The compact system automatically differentiates types ofparticles – clay, carbon, algae, germs, parasites, submicron virusesand more – according to their optical properties. The system,which can withstand harsh conditions, also offers high sensitivityand resolution in a wide particle size and concentration range.
“Laser-based methods are the prevailing technologies for in-process particle size analysis,” said Dr. Meir Teichner, CEO ofPML. These methods fall into two groups – laser diffraction andlaser scanning – but these have some pitfalls in terms of resolu-tion, robustness and speed, he added, and PML’s technology over-comes those.
The technology has been patented in the US, Australia and Israel, and is pending in the European Union; PML already hasbegun to sell systems in 2012 to teaching and design partners, adesalination plant and a medical device company.
“The markets that will want to adopt the technology first are thecement and pharmaceutical (dry medium),” Teichner said. “In bothmarkets, the need is relatively high. However, those markets [pose]relatively high technological challenges and, therefore, the com-pany has addressed first the wet applications (particles in water).”
Contest committeeProfessor Gabby Sarusi of Ben-Gurion University in Be’er Sheva
chaired the contest. Until recently, Sarusi was the chief scientist of Elop (Elbit Systems). Eliezer Manor, president and founder ofShirat Enterprises Ltd., chaired the evaluations committee.
The contest committee comprised serial entrepreneurs, opticsprofessors, business managers, financial companies and R&Dmanagers from leading industries.
First prize was a mentoring session with an expert team fromErnst & Young Israel. Second prize was a review of the com-pany’s IP policy by professionals from Orbotech.
Optical Engineering 2012 is a photonics networking event,bringing together practicing engineers, researchers, technologyproviders, scientists and students. It offers updates on the photonicscommunity as well as a place to exchange information and presentpapers, posters and technical information.
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Fabrinet Contracts for Transceivers OneChip Photonics of Ottawa,Ontario, Canada, has selected Fabrinet as the contract manufacturer for its photonic integrated circuit (PIC)-based passive optical networktransceivers. Under the agreement, Fabrinet will provide a range ofmanufacturing services for OneChip, including optical component at-tachments for the company’s bidirectional optical subassemblies, andfinal integration and testing of its fully packaged optical transceivers.Cayman Islands-based Fabrinet, a vertically integrated precision opticsand electronics manufacturer, will use the operations of its Pinehurstcampus in Thailand. Privately held OneChip manufactures optical transceivers based on monolithic PICs in indium phosphide for accessnetworks and other mass-market broadband applications.
BUSINESSBRIEFS
Laura S. [email protected]
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Companies Expand Partnership HamiltonThorne Ltd. of Beverly, Mass., a provider oflaser devices and imaging systems for the fertil-ity, stem cell and developmental biology re-search markets, has expanded its distributionpartnership with Leica Microsystems of Wetzlar,Germany, a microscope and scientific instru-mentation supplier. The collaboration will givethe German company access to Hamilton’s cur-rent portfolio of laser products as well as selectpipeline products. The new multiyear agreementprovides Leica with nonexclusive rights to mar-ket and distribute Hamilton products in Spain,Portugal and Italy, in addition to the NorthAmerican market. The companies will continueto collaborate on technical product integration.
Luxtera, STMicroelectronics Join ForcesSTMicroelectronics of Geneva has announcedan agreement with Luxtera Inc. to produce sili-con complementary metal oxide (CMOS) prod-ucts using the latter’s intellectual property andknowledge. The products will be developed atST’s 300-mm semiconductor wafer facility inCrolles, France. The collaboration enables thecompanies to produce low-cost, high-volumesolutions for silicon photonics components andsystems, which could have applications in high-speed computing and communications. It alsogrants STMicroelectronics the right to use Lux-tera’s silicon photonics technology, which willbe implemented in the new ST photonicsprocess. ST will provide the Carlsbad, Calif.-
based Luxtera with a suitable supply chain.In other news, Luxtera announced that it has
closed a $21.7 million C round of growth capi-tal financing to support design win opportunitiesand market adoption of silicon CMOS photon-ics. Participation in the C round includes insideinvestment for New Enterprise Associates, Au-gust Capital, Sevin Rosen Funds and Lux Capitalas well as new investment from Tokyo Electronand personal investment from an industry titan,the company said.
GigOptix Books $1.8M Order GigOptix Inc.of San Jose, Calif., has secured a $1.8 millionpurchase order for its 100G Mach-Zehndermodulator (MZM) quad-driver, a customizedversion of the GX62451, for a Tier 1 telecom100G dense wavelength division multiplexingnetworking system. The GX62451 100G dual-polarization quadrature phase shift keying (DP-QPSK) driver is a four-channel MZM designedfor 100G DP-QPSK long-haul optical transmit-ters. The device is GPPO-connectorized and isplug-in-compatible with industry-standard 100GMZMs and multiplexors. The systems addressthe bandwidth demands generated by smart-phones and cloud-based services. The orderwas scheduled for delivery during the first quar-ter of 2012, with additional orders to follow.
Quarles Named CEO B.E. Meyers & Co. Inc. ofRedmond, Wash., has named current presidentand chief operating officer Dr. Gregory Quarles
as its new CEO. He replaces CEO and founderBrad Meyers, who will assume the role of CEOemeritus. Joining the company in 2010, Quarlesused his electro-optics market experience togarner it a US Army Green Laser InterdictionSystem award. Previously, he served as directorof corporate research, development and tech-nology for II-VI Inc. of Saxonburg, Pa. B.E. Mey-ers is an ISO 9001:2008-certified manufacturerof optoelectronic devices for defense and lawenforcement applications.
Laser Targeting System Is Soldier BoundLondon-based BAE Systems received a $23 mil-lion contract from the US Army to provide light-weight handheld Laser Target Locator Modules(LTLMs). BAE Systems’ TRIGR system enablessoldiers to quickly and accurately identify targetlocations while on foot, both in daylight and atnight, and in obscured-visibility conditions suchas smoke or fog. For production of the LTLMsystems, the company initially was awarded a $72 million contract in 2009 from the USArmy’s Program Executive Office Soldier. Workunder the new contract will be performed at thecompany’s Lexington, Mass., Nashua, N.H., andAustin, Texas, facilities.
Block MEMS Garners SBIR Contract BlockMEMS LLC has received a US Army Small Busi-ness Innovation Research (SBIR) Phase II en-hancement contract for its LaserScan analyzer.The award will allow it to enhance the Laser-
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Scan’s capabilities through the development ofchemical recognition algorithms. The algorithmswill enable the system to detect liquid and solidchemical warfare agents and other emergingchemical threats from a standoff distance on avariety of substances, said Petros Kotidis, CEOof Block MEMS. LaserScan is a next-generationspectrometer that incorporates widely tunablemid-IR quantum cascade lasers. Applications include the detection of explosive materials,chemical and biological agents, and toxic industrial chemicals.
Company Grows in Latin America OceanOptics of Dunedin, Fla., has appointed MarcioSiqueira as regional sales manager for Brazil.Based in São Paulo, he will work with customersand distributors throughout Brazil and LatinAmerica, offering educational and sales supportfor the company’s product line, including spec-trometers, chemical sensors, analytical instru-mentation and metrology equipment. He alsowill facilitate the growth of the company inthese territories and will continue to develop its distributor network. Before joining OceanOptics, Siqueira worked at Hanna Brasil Imp. e Exp Ltda as sales manager for Brazil.
Zecotek Files Patent Suit Zecotek ImagingSystems Pte Ltd., a subsidiary of Zecotek Photon-ics Inc. of Richmond, British Columbia, Canada,has filed a patent suit in the US against Saint-Gobain Corp. and Philips for infringing its US
Patent No. 7,132,060. The patent covers thesubstances and chemical formulations used togrow lutetium fine silicate (LFS) scintillation crys-tals. The lawsuit alleges that Saint-Gobain’sLYSO crystals infringe Zecotek’s patent, and thatPhilips infringes by using those crystals in thepositron emission tomography scanners it sells.Zecotek is joined by its exclusive licensee for certain LFS crystals, Beijing Opto-ElectronicsTechnology Co. Ltd., as co-plaintiff.
OKI Develops Light Source Telecommunica-tions company OKI Electric Industry of Tokyohas announced its development of a quantumentangled light source that offers the highestpurity level achieved to date. The source isbased on cascaded nonlinear optical effectsusing a proprietary periodically poled lithiumniobate ridge waveguide device operating atroom temperature. Research led by professorShuichiro Inoue at the Institute of Quantum Science at Nihon University confirms a signal-to-noise ratio more than a hundredfold betterthan that of optical fiber light sources. OKI willcontinue to refine the light source. Its goal is toachieve a practical quantum cryptography com-munications system.
REO Names President, CEO Photonics industryveteran Paul Kelly has been appointed presidentand CEO of REO of Boulder, Colo., a high-vol-ume precision optical solutions manufacturer.Kelly has more than 25 years of experience man-
aging and growing high-technology businesses.Before joining REO, he served as president ofmachine vision solutions provider Microscan.“Paul has unmatched knowledge, skill and expe-rience in directing companies whose productsare based in photonics technology,” said RobertKnollenberg, REO founder. REO expects thatKelly will be able to further accelerate the growthit has experienced over the past 10 years.
Phone Microscope Accessory Developed A pocket-size accessory that turns an ordinarycamera phone into a high-resolution microscopecan accurately obtain images with resolution of0.01 mm. Scientists at VTT Technical ResearchCentre of Espoo, Finland, have developed a mi-croscope that attaches to a mobile camera lenswith a magnet. It can examine various surfacesand structures in microscopic detail and can takehigh-resolution images that can be forwarded asMMS (Multimedia Messaging Service). It has ap-plications in the security, health care and print-ing industries. VTT and KeepLoop Oy of Tam-pere, Finland, are exploring the commercialpotential of the device. The first industrial appli-cations and consumer models were expected tobe released in early March 2012.
Imra, Disco Collaborate Femtosecond fiberlaser manufacturer Imra America Inc. of AnnArbor, Mich., a subsidiary of Aisin Seiki Co. Ltd.of Kariya, and Disco Corp. of Tokyo have teamedto develop lasers and processing systems for
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dicing of semiconductor materials. The compa-nies will provide solutions that use the capabili-ties of femtosecond lasers, which feature mini-mal thermal effects in materials processing.Imra is the exclusive licensee of US Patent No.5,656,186 by the University of Michigan, essen-tial for femtosecond and picosecond laser mate-rials processing, which it licenses to its cus-tomers. Disco manufactures precision cutting,grinding and polishing machines.
Companies to Build 3-D Microscopy SystemToshiba Imaging Systems Div. of Irvine, Calif.,and ISee3D Inc. of Vancouver, British Columbia,Canada, will develop a 3-D microscope digitalvideo system using Toshiba’s IK-HD1 three-chip-CCD high-definition camera. ISee3D’spatented optical switch technology and its cus-tomized interface to the IK-HD1 camera will result in 3-D microscope images with highlymagnified object detail. The system, which willuse a single camera, can be integrated into newsystems or adapted to the installed base of microscopes for use in clinical, surgical and in-dustrial microscopy applications. Finalization of a commercial system is expected this year.
Stockholders OK UTC Buyout Goodrich Corp.shareholders have approved the acquisition ofGoodrich by United Technologies Corp. (UTC).Goodrich investors will receive $127.50 in cashfor each share of common stock they own, a47.4 percent premium to the closing stock pricein September, when news of the acquisitionreached the market. The transaction is valued at$18.4 billion, including $1.9 billion in net debtassumed. Upon completion of the acquisition,Goodrich will become a wholly owned sub-sidiary of the Hartford, Conn.-based UTC, andits operation will remain at its base in Charlotte,N.C. The merger is set to be completed by mid-year.
Riber, Imec Extend Collaboration Molecularbeam epitaxy supplier Riber SA of Bezons,France, and R&D company imec of Louvain, Belgium, will continue work on epitaxy processtechnologies for next-generation III-V CMOS de-vices. In the new project, Riber’s 300-mm ultra-high-vacuum (UHV) chamber, equipped with insitu tools for surface analysis and clustered with300-mm silicon CMOS production equipment,will be evaluated for the production of CMOSdevices based on high-mobility germanium andIII-V channels. Through the collaboration, imecsaid it can integrate the power of UHV systemsinto state-of-the-art semiconductor productionequipment on large-diameter wafers.
JK Lasers Appoints Manager Michael Haasehas been appointed JK Lasers’ new Germansales manager to support its growing Germanpresence. A mechanical engineer with morethan 10 years of experience in the laser indus-try, he will provide sales and technical supportto JK Lasers’ customers throughout Germany.He is based in Planegg, near Munich. Prior tojoining JK Lasers, Haase established the lasercompany H2B Photonics, which was acquired byRofin-Baasel Lasertech. Afterward, he becameits solar industry sales manager. Based inRugby, UK, JK Lasers, part of the GSI Group,manufactures fiber lasers, Nd:YAG lasers and
process tools that operate around the clock inindustrial environments.
UC-Boulder Technique Optioned The Univer-sity of Colorado at Boulder has completed anexclusive option agreement with Double HelixLLC, also of Boulder, to develop the university’s3-D superresolution imaging technique. Devel-oped by Rafael Piestun, a professor at Boulderwho founded Double Helix, the technique com-bines 3-D optics and a signal postprocessingmethod used for quality improvement in imageprocessing. It provides multifunctional 3-D superresolution imaging capability to cellular,molecular biology and biophysics laboratories.“We are looking forward to bringing this tech-nology to the market, initially in microscopyand, later, to more markets, including metrol-ogy and digital optics,” said Leslie Kimerling, afounding partner of Double Helix.
Global Lighting Association Formed To rep-resent the more than 5000 lighting manufactur-ers and $50 billion in annual sales, the globallighting industry has formed the Global LightingAssociation. Founded in 2007 as the GlobalLighting Forum, the new association representsthe same members but with a renewed focusand commitment to shaping how the world is illuminated. Its goal is to share information,within the limits of competition law, on scientific,social, environmental, political and business issues related to the industry. The associationwill focus its efforts in 2012 on energy efficiency,LED performance quality and innovation.
Novaled Registers for IPO Novaled AG ofDresden, Germany, has filed a Form F-1 regis-tration statement with the US Securities and Exchange Commission for a proposed initialpublic offering (IPO) of its American depositoryshares (ADSs). It also will apply to have its ADSslisted on the NASDAQ Global Market or theNew York Stock Exchange. Goldman, Sachs &Co. and Deutsche Bank Securities are acting asjoint book-running managers for the offering.Acting co-managers include Canaccord Genuity,Commerzbank, Cowen and Co. and JMP Securi-ties. Novaled develops technologies and materi-als that enhance the performance of organicLEDs and organic electronics.
Laser Research Lab Opened In France, ultra-fast laser specialist Amplitude Systèmes of Bor-deaux and Laboratoire Charles Fabry have es-tablished a joint research laboratory that willsupport 10 scientists working on high-perfor-mance lasers. Called DEFI, the new lab is basedat the Institut d’Optique in Palaiseau and willfocus on diode-pumped ultrafast lasers. Theteam will work on emerging concepts and pro-totype laser development for the next genera-tion of ultrafast sources. Amplitude has workedon ytterbium ultrafast lasers with LaboratoireCharles Fabry since 2006, a collaboration thathas demonstrated results including shortest du-ration from oscillators and regenerative ampli-fiers and sub-100-fs high-energy fiber lasers.
Oclaro Outsourcing Operations Optical com-munications and laser components providerOclaro Inc. of San Jose, Calif., is outsourcing itsShenzhen, China-based final assembly and test
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operations to Venture Corp. Ltd.’s Malaysia fa-cility. The transfer, expected to take three years,will free up more than $35 million, Oclaro said.During the transition period, Oclaro will con-tinue to operate its Shenzhen manufacturing facility and will retain its employees. Several ofVenture’s operational personnel will relocate toShenzhen to provide support to Oclaro. Theywill oversee the transfer and ensure that prod-ucts transitioned to the Malaysia facility are fullyqualified by customers before they are phasedout of the China facility.
Company Signs Distributors Laser diode man-ufacturer Laser Operations LLC of Sylmar, Calif.,has expanded its sales organization in Europeand the Asia-Pacific market through two distribu-tion agreements and the appointment of an in-house consultant. Michael Wang, who wasnamed in-house consultant for China, will advisethe company on business opportunities there andon managing local distributors. Soliton GmbHhas been named a nonexclusive distributor forGermany, Austria, the German-speaking portionof Switzerland and Poland and will focus on thecompany’s nonmedical market. Indeco has beenappointed a nonexclusive distributor in Japan.
$1M Endoscope Order Received Optical in-struments maker Precision Optics Corp. Inc. ofGardner, Mass., has announced a $1 millionorder for its Microprecision-based endoscopes.Details of the agreement were not disclosed.The endoscopic medical devices deliver opticaland mechanical specifications that are amongthe most challenging in the industry, the com-pany said. They rely on proprietary Micropreci-sion technology for fabrication and assembly oflenses and prisms with sizes <1 mm. The orderis contingent upon the successful validation test-ing of prototype units and the execution of anacceptable supply agreement delivery schedule.
Excelitas Expands Harlid Capacity In responseto the growing demand for protection againstlaser designation and ranging systems, optoelec-tronics maker Excelitas Technologies of Waltham,Mass., has completed its investment in state-of-the-art automation to expand production capac-ity for its proprietary Harlid (high angular resolu-tion laser irradiance detector). The device is usedin laser warning receiver systems for ground ve-hicles, naval vessels, fixed or rotary wing aircraft,and static perimeter facilities. It also is used todetect and provide angle-of-arrival informationfrom direct and indirect scattered light from laserrangefinders and target designators, and fromactive electro-optic systems.
Hamamatsu to Resell Visiopharm ProductsVisiopharm of Hørsholm, Denmark, and Hama-matsu of Hamamatsu City, Japan, have an-nounced a nonexclusive worldwide OEM agree-ment and reseller partnership for Visiopharm’squantitative digital pathology (QDP) solutions.Under the agreement, Visiopharm will serve asan OEM for Hamamatsu’s NDP.Analyze soft-ware, a research tool for tissue image analysisthat is fully compatible with Visiopharm’s suiteof QDP solutions. Hamamatsu will market andsell the suite of QDP solutions, including Cloud-Analysis, DeployedAnalysis, Stereology and Ap-plication Protocol Packages from Visiopharm’s
new APPCenter. Hamamatsu, which is knownfor its NanoZoomer Digital Pathology (NDP)whole slide scanners, will expand its offering to include quantitative digital pathology.
Lee Named EPIC Director General CarlosLee has been appointed director general of the Paris-based EPIC, the European PhotonicsIndustry Consortium. He succeeds ThomasPearsall, who has led the association since itsfounding in 2003. Lee is the current directorgeneral of SEMI Europe, the SemiconductorEquipment and Materials Industry Association,where he leads the advocacy program. He hasmore than 15 years’ experience in industry association management, including buildingmembership value through standardization, collaboration, networking platforms and events,and through other activities of collective interestthat benefit the industry at large.
Modulight Receives Contract Laser manufac-turer Modulight Inc. of Tampere, Finland, hasdesigned, integrated and CE-certified an OEMmedical laser system for PCI Biotech of Oslo,Norway, for a novel cancer therapy process.Under a multiyear OEM manufacturing agree-ment, Modulight will deliver a seven-channelmedical laser system solution to PCI Biotech forits PCI (PhotoChemical Internalisation) patentedphotochemical drug delivery technology usedfor cancer therapy and other diseases. PCI is atechnology for light-directed drug delivery bytriggered endosomal release. It was developedto introduce therapeutic molecules in a biologi-cally active form specifically into diseased cells.
RPO Officially Opens Facility Rochester Preci-sion Optics (RPO) of Henrietta, N.Y., held a rib-bon-cutting ceremony April 11 to celebrate itsnewly expanded 107,500-sq-ft facility. RPObegan the $10.7 million expansion project at itsheadquarters in June 2011 by adding 43,000square feet of space to its pre-existing 64,500-sq-ft facility. The expansion adds more than 150new jobs while retaining the 180 positions cur-rently filled in the company. Formerly KodakOptical Imaging Systems, a unit of EastmanKodak, RPO manufactures optical componentsand assemblies for commercial, military and in-dustrial systems. The company also has facilitiesin New Hampshire and overseas in Shanghai.
Emcore Secures Solar Panels Contract Em-core Corp. has been awarded a $6 million, two-year contract by Ball Aerospace & TechnologiesCorp. of Boulder, Colo., to design, manufacture,test and deliver solar panels for a new space-craft. The panels will be populated with Em-core’s ZTJ multijunction, space-grade solar cells,which deliver a beginning-of-life conversion ef-ficiency nearing 30 percent, with the option fora patented, onboard monolithic bypass diode.Production of the solar cells and panels will takeplace at the company’s Albuquerque, N.M.,manufacturing facilities.
Power Technology Appoints Distributor To expand its business and to serve its growing customer base in Israel, Power Technology Inc. ofLittle Rock, Ark., has appointed New TechnologyS.K. Ltd. of Ramat Gan, Israel, as its new distri -butor. “Israel is an exciting market for Power
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Corning to Acquire Labware Unit Specialtyglass and ceramics manufacturer Corning Inc.of Corning, N.Y., plans to buy the majority of
Becton, Dickinson and Co.’s Billerica, Mass.-based Discovery Labware division later this yearfor approximately $730 million in cash. Whencompleted, the acquisition will expand Corn-ing’s global market access and enhance its lifesciences portfolio in the areas of drug-discoverytools, bioprocess solutions and laboratory re-search instruments.
EOS Files Patent Suit Laser-sintering systemsmanufacturer EOS of Krailling, Germany, filed apatent lawsuit March 5 against Phenix Systemsof Riom, France, for infringing two US patents
for its dental product lines, the company an-nounced. The lawsuit alleges infringement of USPatent Nos. 5,753,274 and 6,042,774 throughthe manufacture, sale and use of the PXL, PXM,PXS and PXS Dental product lines from Phenix inthe US. During the second half of 2011, Phenixpublicly announced the commercial manufac-ture, sale and use of exactly these product lines,even though EOS had apprised Phenix of itspatent portfolio several times, EOS alleges.
Space Systems/Loral, NASA CollaborateSpace Systems/Loral (SS/L) of Palo Alto, Calif.,will partner with NASA’s Goddard Space FlightCenter to host a laser communications relaydemonstration on a commercial satellite to belaunched in 2016. NASA’s Space TechnologyProgram selected Goddard’s mission proposalto use the SS/L satellite platform to help enablethe next era of space communications. Opticalcommunications uses an uncongested portion of spectrum compared with radio-frequencycommunications currently used to transmit datafrom space. For commercial satellites, lasercommunications could provide even faster ratesthan radio frequency, with much less power andmass – the typical constraints of satellite design.
Norman Edmund Inspiration AwardLaunched Optical components manufacturer Ed-mund Optics of Barrington, N.J., has establishedthe Norman Edmund Inspiration Award to honorthe contributions made by founder Norman Ed-mund toward advancing the science of optics.The $5000 product award will be presented toone of the three 2012 first-place prize recipientsof the company’s worldwide higher educationgrant program. It will be given to the college oruniversity optics program in science, technology,engineering or mathematics that best embodiesthe legacy of Norman Edmund, who died earlierthis year. The winner will be announced Oct. 10.
Illumitex Secures Funding, Hires CEO LEDmaker Illumitex Inc. of Austin, Texas, has se-cured an additional $9.3 million in funding todevelop its lighting fixture product lines and toprovide ongoing support for the development of proprietary precision beam packaged LEDs.Investors participating in the funding round in-clude NEA, Morgan Creek Capital, Mousse Part-ners, Apex Venture Partners, DFJ Mercury andSyngenta Ventures. Illumitex also has hiredChris Hammelef as chief executive officer. He isthe former vice president and general managerof outdoor lighting company Hadco Group, adivision of Philips. Illumitex is now focusing onlighting fixtures as its main product offering.
Companies Ink Display Engine AgreementsProjection display technology company Micro-Vision Inc. of Redmond, Wash., has signed defin-itive agreements with Pioneer Corp. of Kana-gawa, Japan, to manufacture, distribute, licenseand supply its HD PicoP Gen2 display enginetechnology using direct green lasers. Under theagreements, Pioneer will produce PicoP Gen2display engines for its own automotive aftermar-ket products and will pay MicroVision royaltiesfrom sales of these products. Pioneer plans to release its first aftermarket head-up display laterthis year. It also will manufacture and supply keydisplay engine subsystems to MicroVision forconsumer, industrial and other applications.
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And, like most of Zygo’s manufacturing technology, Ed does not rely on generic manufacturing equipment to get the job done. Rather, he looks to machines like the “Big Eddie” that bear his name. Zygo has used these machines to produce some of the most challenging optics in the world, year after year.
For your most challenging windows, aspheres, machined optical structures and opto-mechanical assembly needs, contact Zygo today and know that people like Ed understand that the impossible is just another opportunity for innovation.
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GreenLightSpinach may hold key to understanding photosynthesis
Photosynthesis is vital to the continuedsurvival of life on Earth because itproduces most of Earth’s supply of
oxygen. For a long time, scientists havebeen convinced that if they could com-pletely understand how photosynthesisworks, they could apply it to syntheticsystems to create clean energy from waterand sunlight, with the only emissionsbeing oxygen and hydrogen.
Researchers at Georgia Institute of Tech-nology have shown the importance of ahydrogen bonding water network in thephotosynthesis substructure called photo-system II. They extracted photosystem IIfrom ordinary spinach and replaced waterwith ammonia to test the idea that a net-work of hydrogen-bonded water moleculeswould provide a catalyst for the processthat produces oxygen.
“By substituting ammonia, an analog of the water molecule that has a similarstructure, we were able to show that thenetwork of hydrogen-bonded water mole-cules is important to the catalytic pro-cess,” said Bridgette Barry, a professor atGeorgia Tech’s School of Chemistry andBiochemistry. “Substituting ammonia for water inhibited the activity of the photosystem and disrupted the network.The network could be re-established byaddition of a simple sugar: trehalose.”
Photosynthesis is controlled by thechloroplasts of green plants. Oxygen is pro-duced through the illumination of calciumand manganese ions in the oxygen-evolvingcomplex (OEC) of the chloroplast. Shortlaser flashes can be used to step through thereaction cycle, which involves four sequen-tial light-induced oxidation reactions. Forthe oxygen to separate from the OEC, itforms an electrostatic network with the ionsin the OEC and a protein called amide carbonyl (C=O). Oxygen’s hydrogen bondsare used as a catalyst component to split off the oxygen.
The researchers used Fourier transforminfrared spectroscopy to observe how the
hydrogen-bonded network reacted to pulsesfrom an Nd:YAG laser. After each pulse,they analyzed the photosystem’s transitionand measured the bond strength of the C=O
groups, which were, in turn, used as mark-ers of hydrogen bond strength. With theflash, there was an observed increase inC=O hydrogen bond strength; however,when ammonia was added, the C=O hydro-gen bonds weakened. Trehalose blocked theammonia’s effects.
“This research helps to clarify how ammonia inhibits the photosystem, whichis something that researchers have beenwondering about for many years,” Barrysaid. “Our work suggests that ammoniacan inhibit the reaction by disrupting thisnetwork of hydrogen bonds.”
Barry hopes that her research can beused to harness or imitate energy and oxygen production.
“We are only looking at a single partof the overall reaction now, but we wouldlike to study the entire cycle, in whichoxygen is produced, to see how the inter-actions in the water network change andhow the interactions with the proteinchange,” Barry said. “The work is an-other step in understanding how plantscarry out this amazing series of photosyn-thetic reactions.”
The research was published in the April 2 online edition of Proceedings ofthe National Academy of Sciences. l
41Photonics Spectra June 2012
Georgia Tech graduate student Brandon Polanderprepares for a Fourier transform infrared spectroscopy experiment. The green laser light is used to photoexcite the spinach photosystem IIsample. Courtesy of Gary Meek.
“Sweet spot” could help bring organic solar cells to market
Abetter fundamental understanding ofhow to optimize performance in or-ganic solar cells could bring this
type of cell closer to market. Prototype solar cells made of organic ma-
terials currently lag far behind conventionalsilicon-based photovoltaic cells in terms ofelectricity output. However, if efficient or-ganic cells could be developed, they wouldhave distinct advantages: They would costfar less to produce than conventional cells,could cover larger areas and, conceivably,
could be recycled far more easily.Now, scientists at the National Institute
of Standards and Technology (NIST) andthe US Naval Research Laboratory (NRL)are studying cells made up of hundreds ofstacked thin layers that alternate betweentwo organic materials – zinc phthalocya-nine and C60, the soccer-ball-shaped carbon molecules known as buckyballs.When light strikes the multilayered film,all of the layers are excited, causing themto give up electrons that flow between the
612_Greenlight_Layout 1 5/24/12 2:34 PM Page 41
buckyball and phthalocyanine layers andcreating an electric current.
When the researchers varied the thick-ness of each layer – each only a few nano-meters thick – they discovered that theamount of electrical current the overall cellputs out changes dramatically. In this sense,determining the ideal thickness of the lay-ers is crucial to making the best-performing
cells, said NIST chemist Ted Heilweil. “In essence, if the layers are too thin,
they don’t generate enough electrons for asubstantial current to flow, but if too thick,many of the electrons get trapped in theindividual layers,” he said. “We wanted to find the sweet spot.”
To find that “sweet spot,” they exploredthe relationship between layer thickness
and two aspects of the material. Althoughthe layers generated an initial spike in cur-rent when struck with light, the current de-cayed fairly quickly. The ideal cell wouldgenerate electrons as steadily as possible.The researchers discovered that changingthe layer thickness affects not only the ini-tial decay rate, but also the overall capacityof the material to carry electrons.
They set out to find the optimum combi-nation of these two factors by measuring a number of films – grown by Paul Lane of NRL – that had layers of varying thick-ness. They found that layers approximately2 nm thick give the best performance.
Heilweil said the results have encouragedhim to think that prototype cells based onthis geometry can be optimized, althoughone engineering hurdle remains: finding the best way to get the electricity out.
“It’s still unclear how to best incorpo-rate such thin nanolayers in devices,” hesaid. “We hope to challenge engineerswho can help us with that part.”
The findings appeared in Physical Review Letters (doi: 10.1103/PhysRevLett.108.077402). l
GreenLight
Light that strikes this organic solar cell causes electrons to flow between its layers, creating an electric current.Measurements made by the NIST/NRL research team determined the best thickness for the layers, a findingthat could help optimize the cell’s performance. Courtesy of NIST.
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An ultrathin flexible organic solar cell less than2 μm thick could have implications for thedesign of future flexible electronic devices.
Scientists from Johannes Kepler University Linzand the University of Tokyo developed the stretch-able cells – which can generate 10 W/g – based onan ultrathin polymer substrate.
They maintain their performance after beingstretched repeatedly, displaying power conversion efficiency equal to that of their glass counterparts.They could be used in applications such as robotics,synthetic skin or e-textiles.
“In all these areas, it is important that the cells are not only powerful, but also light and flexible,”said Dr. Martin Kaltenbrunner of the Institute of Experimental Physics. “[In] many things, you cannot install rigid cells.”
Follow-up projects are being conducted at Johannes Kepler University.
“The basic system is also applicable to electricalcircuits,” Kaltenbrunner said. “This is of course extremely interesting for the industry.”
The research was published in Nature Communi-cations (doi:10.1038/ncomms1772). l
43
GreenLight
Photonics Spectra June 2012
Ultrathin solar cells for stretchable applications
An ultrathin organic solar cell also can beused for surface-conforming electronics.The cell pictured is glued to a prestretchedelastomer, biaxially compressed and thenpushed out of plane by a plastic tube.
“It is important that the cells are not onlypowerful, but also light and flexible.”
– Dr. Martin Kaltenbrunner, Institute of Experimental Physics
An ultrathin organic solar cell is so flexible that it can be used for stretchableapplications. The cell pictured is glued toa prestretched elastomer. The random network of wrinkles that form upon relaxation allows for repeated stretchingunder continuous operation. Images courtesy of Martin Kaltenbrunner.
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Hyperspectral Imaging Gets Stampof Approval for Food Processing
BY DAVID BANNON AND CHRISTOPHER VAN VEEN, HEADWALL PHOTONICS INC.
Hyperspectral imaging holds so muchpromise across so many applica-tions, and companies specializing in
this technology are working to drive outcomplexity and cost, which will make it amore mainstream inspection technologyfor improving food safety and quality.
Three primary areas of food and agri-culture have adopted hyperspectral imag-ing. The first is in-line processing and inspection of everything from specialty(high value) crops such as strawberriesand apples to meat products such as poul-try and seafood. The second is remotesensing of agricultural areas; with thistechnique, data-rich analysis of crops andfarmlands can be performed from an air-borne platform. The third is an emergingcategory of plant research and crop sci-ence incorporating plant phenotyping andgenomics. Here, hyperspectral imagingcan assist research efforts to analyze genefunctions that become key elements inplant breeding, with the goal of optimizinggrowth and disease protection. In this market, advanced imaging technology enables a new class of agricultural re-search and in-line, high-throughput in-spection of food products.
Not just for the labHyperspectral sensing is not a “new”
technology, per se – it has been around for about 20 years. Long favored in de-fense and reconnaissance circles, it wasseen as complex and dedicated to airborneapplications. These characterizations werenot entirely untrue, but over time, the ability to see and classify objects based on the inherent chemical composition orspectral signature became a value proposi-tion that could not be ignored by all sortsof commercial endeavors, especially theinspection of foods on high-volume processing lines.
From a regulatory perspective, very fewindustries depend on rigorous inspectionmore than food processing. Governmentaloversight is more rigid than ever, which
Photonics Spectra June 201244
A technology that evolved from the cloaked secrecy of military satellites and reconnaissance technology is finding its way into poultry- and produce-processing facilities.
Green apples whiz by on an inspection line. Images courtesy of Headwall Photonics Inc.
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means that these companies cannot simplyoperate with systems and processes totheir liking. Disease, contaminants andother health-related conditions must beidentified quickly and completely, whethera company is processing specialty crops,seafood or poultry. Passing muster meanslabor-intensive inspection processes, some-times on a continual basis and across mul-tiple facilities. Under such tight regulation,private-sector companies feel continualpressure to somehow remain efficient andprofitable.
Because of this pressure, food-process-ing companies invest in spectral imaginginstruments to make the inspection side of their operation more than pay for itself.After all, rejected products “cost” muchmore the later they are found. Occasion-ally, contaminated products do reach storeshelves; the financial cost, coupled withthe public relations backlash, can cripple a brand for years or even result in closureof operations.
One way for food-processing companiesto invest in new technologies while seeinga demonstrable return on investment is tomake sure the inspection processes arerapid, accurate and repeatable. Highthroughput is key, because the faster a facility can inspect its products, the moreefficient the operation becomes.
Any increase in speed must not dimin-ish safety or quality, however, so the USDepartment of Agriculture (USDA) isthoroughly investigating new ideas andtechnologies in limited pilot programs
across the country. For example, the de-partment is planning to fundamentallychange the way poultry products maketheir way to the American dinner table. If new automated technologies can helpreduce manual labor costs while quicken-ing the inspection process, consumers benefit from food products that not onlyare safer but also more affordable.
Hyperspectral sensing has an advantagein food inspection because it can seethings that other machine-vision technolo-
gies cannot. Because every object has itsown unique spectral signature, a hyper-spectral sensor can noninvasively and rapidly scan products for anomalies. Fecal and chemical contamination, diseaseconditions and foreign objects can be “redflagged” once these triggers have beenproperly cataloged with the right spectralsignature. Equipped with these unique“spectral libraries,” the sensors go abouttheir business of determining good productfrom bad.
45Photonics Spectra June 2012
The Hyperspec data processing unit from HeadwallPhotonics analyzes spectral and spatial imagingdata cubes, which can grow to several gigabytes insize; extremely rapid data acquisition and analysisare needed to extract spectral features of interest.
Disease conditions, contaminants and other health-related concerns must be identified quickly and completely, whether a company is processing poultry, seafood or specialty crops.
How in-line high-speed hyperspectral sensing works: (a) As the product moves under the sensor, a visualimage of the sample is rendered by unique signatures; (b) the full spectra are captured for any position in the field of view; and (c) the visual image of the sample at any wavelength is captured.
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Spectral bands of interest compriseeverything from UV (250 to 600 nm) allthe way up to SWIR (950 to 2500 nm),and include VIS (380 to 825 nm), visibleand NIR (380 to 1000 nm), and NIR (900to 1700 nm). A poultry-processing facility,for example, may have a very distinct setof anomalies for which it checks. Eachcondition will therefore fall into one ofthese spectral bands, and the hyperspectralinstrument will look for these.
Although the technology behind hyper-spectral sensing is generally well under-stood, adapting it to the rigors of hot, wet,
noisy and unappealing conditions is achallenge requiring experience with harshenvironments. First, the imaging systemsmust be reliable and affordable. Instru-ment reliability is a factor derived fromthe imaging performance as well as thespectral and spatial resolution of the hy-perspectral instrument.
Here, the use of aberration-correcteddiffractive optics – representing the heart-beat of the instrument – is a distinguishingcharacteristic. Headwall Photonics, for ex-ample, manufactures in-line hyperspectralsensors that are corrected for aberrations.
This patented design allows the sensor toinspect a scene across a very wide processconveyor line without image distortionsthat could affect the measurement. Aberra-tion correction also yields higher signal-to-noise ratios, and levels of spectral andspatial resolution. In practical terms, a precisely engineered grating leads to aprecisely engineered hyperspectral sensor;a food inspection line, for example, willsee fewer false-positives if the spectrome-ter uses aberration-corrected gratings.
To gain full processing line coverage, awide field of view is important in a hyper-spectral sensor. These systems are builtupon the push-broom architecture, withfood products passing by the hyperspectralinspector. For each moment in time (eachframe capture by the sensor), the sceneobserved by the fore lens is imagedthrough a tall slit aperture within the in-strument. The scene that fills this slit aper-ture is then dispersed through the spec-trometer (containing the grating), with theresulting spectral and spatial informationimaged onto a two-dimensional focalplane array (FPA) using silicon CCD, In-GaAs or HgCdTe arrays. One axis of theFPA (pixel rows) corresponds to the im-aged spatial positions within the field ofview all along the slit height. The slitheight determines the overall field of view. The second axis (spectral for pixelcolumns) corresponds to the spectralwavelength that is linearly dispersed andcalibrated. Each 2-D image (or frame cap-ture) is digitized by the FPA to build adata set – representing the hyperspectralscan – that comprises all the spectral andspatial information within the scene orfield of view of the sensor.
The user can evaluate any point or pixelwithin the field of view for its chemicalspectral signature while maintaining theintegrity of the spatial information ob-tained. Hyperspectral sensors also can interrogate spectral signatures of interest,based on the defined algorithms. Whenthese algorithms are used on the process-ing line, “accept” or “reject” decisions can be passed to robotic arms or air knivesfor product removal. Headwall Photonicshas worked very closely with USDA re-searchers to establish algorithms and spectral libraries for a wide number ofagricultural products.
Sensing from aboveOne interesting use of hyperspectral
sensors is in precision agriculture, where small, lightweight sensors are deployed aboard airborne platforms rang-
46 Photonics Spectra June 2012
Hyperspectral Imaging
(a) Spectral analysis of specialty fruit identifies contaminants: wood (blue), metal (green) and disease (orange). (b) In-line process inspection of contaminated, diseased fruit. (c) Visible and NIR (400 to 1000 nm) analysis finds bruised and unbruised strawberries.
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ing from Cessna aircraft to unattended aerial vehicles.
In the same way that food-processinglines are evolving from straightforwardmachine-vision systems to hyperspectralsensors, many growers and agriculturistsalso are moving to hyperspectral imag-ing. The richness of the data collectedcan give farmers a sense of what andwhere to plant, and when to fertilize andharvest. High-value crops such as pecans,grapes and walnuts must be managedwith precision. Nutrient levels, ripenessand disease can be “seen” by hyperspec-tral sensors in much the same way thatfood-processing lines can be seen. Be-cause these sensors are deployed aboardaircraft, hundreds of acres can be sur-veyed quickly – and the data-processingpower coupled to these sensors meansthat more useful information can be ob-tained. The result is better overall cropmanagement across the globe.
VineView Scientific Aerial Imaging ofSt. Helena, Calif., uses high-resolutionaerial imaging and scientifically calibrateddata products to assist in crop uniformityoptimization, irrigation management andharvest planning. VineView has used in-
frared sensors for the most part, but thecompany now is going beyond IR to hy-perspectral.
“Adding hyperspectral data allows us toprovide more specific actionable informa-
tion to our clients who manage high-valuecrops,” said Dr. Matthew Staid, the com-pany’s president. The hyperspectral sens-ing technology means that VineView notonly can map vigor or stress within crops,
47Photonics Spectra June 2012
Hyperspectral Imaging
The USDA is investigating new technologies to fundamentally change the way poultry products make their way to the table. Automated technologies can reduce labor costs and speed inspection, resulting in healthier, more affordable food products.
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but also can better identify the specificcauses of those stresses. The presence ofleaf roll, weeds and invasive species willbe mapped as VineView aircraft patrol orchards and crop fields.
At the Instituto de Agricultura Sosten-ible in Córdoba, Spain, small, unmannedaircraft outfitted with high-resolution sen-sors look down on crop fields and or-chards to make precision planting and har-vesting decisions. Because the sensorsweigh less than 2 lb and exhibit excellentspatial and spectral resolution, they areperfectly suited to giving farmers and agri-culturists a wealth of previously “unseen”spectral information from altitudes of1000 to 15,000 ft.
Although the sensor technology is thereto see what is on the ground, hyperspectraldata processing can be processor-inten-sive. Fortunately, data-processing horse-power is similarly increasing in capabilitywhile costs continue to go down or at leastmoderate. Headwall Photonics, for exam-ple, offers its Hyperspec data processingunit, which focuses on the analysis and in-terrogation of the spectral and spatial im-aging data cubes. Hyperspectral datacubes can grow to several gigabytes in
size, and they require extremely rapid dataacquisition and analysis to extract spectralfeatures of interest. They also depend onspecific algorithms and the classificationor search for certain threshold conditionswithin the scene.
Plant phenotyping, crop scienceThe ability of hyperspectral sensing to
see beyond the visible also makes it avaluable tool in plant phenotyping andcrop science research. In simple terms, aphenotype is a composite of an organism’sobservable characteristics or traits. Thesecan include its morphology, development,biochemical or physiological properties,phenology and products of behavior.
The practical application of phenotyp-ing is to assist in plant breeding: identify-ing traits such as disease resistance, en-hancing growth and development charac-teristics, and more. Seed companies, forexample, can use this science to introducehigher-quality, hardier specimens for cer-tain environments and regions, and tostandardize growth conditions more accu-rately than ever.
Würselen, Germany-based LemnaTecGmbH has been a pioneer in the science
of phenotyping since 1998. The companyuses Headwall’s Hyperspec Inspector in itsharsh “greenhouse” environments to ana-lyze the chemical composition, overallstructure and specific traits of plants pass-ing within the field of view. Hyperspec Inspector is the same type of “point andstare” system that food-processing facili-ties use, but it is optimized for specificspatial and spectral resolutions.
The advantage of hyperspectral imagingsystems is that, although the basic funda-mentals are the same from one system tothe next, key parameters such as spectralbands, resolution, signal to noise andlighting conditions can be modified to suiteach specific application. And becausethese systems are deployed in environ-ments where humidity, moisture, vibra-tion, heat and chemicals are often thenorm rather than the exception, the enclo-sures are very protective of the instru-ments contained within.
Meet the authorsDavid Bannon is CEO of Headwall PhotonicsInc.; email: [email protected] Van Veen is in marketing at Head-wall; email: [email protected].
48 Photonics Spectra June 2012
Hyperspectral Imaging
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The latest in photonics for researchers,
engineers, product developers, clinicians
and others in medicine, biotechnology
and other life sciences.
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From the publisher ofPhotonics Spectra magazine.
MICROSCOPY
SPECTROSCOPY
IMAGING
OPTICS
LASERS
612_BIO_HouseAD_Pg49_Layout 1 5/24/12 11:35 AM Page 49
BY LYNN SAVAGEFEATURES EDITOR
M aximizing food resources inlarge-scale operations may be the best way to bring sustenance
to those without, but doing so does notcome cheaply. There is increasing interestaround the world not only in boostingfood production, but also in controllingthe associated costs.
One way that horticulturists look at theproblem is to try to take control of plantbiology. Tweaking the photosynthesismechanisms of plants or refining the wayin which they use various wavelengths oflight delivered at different times of the dayare two such methods. And LED-basedlighting gives scientists a good shot atcontrolling these factors and more.
Sunlight is the standard for growingcrops, of course. It’s been around forever
and isn’t going away anytime soon. How-ever, sunlight contains every visible wave-length known – and many outside thatrange. The amount of available sunlightvaries with season, climate and weather aswell, making it one of the least control-lable factors in agriculture.
Bringing plants indoors and shining thelight from incandescent lamps is common,but not really that much better. You get theyellow, red and far-red wavelengths thatplants desire for good growth, but you alsoget a lot of thermal energy, which trans-lates into heat that must be exhausted froma greenhouse or other growing chambers,or from indoor plant factories.
“Growers are always interested in
reducing their input costs,” said Erik S.Runkle, associate professor of horticultureand a floriculture extension specialist atMichigan State University in East Lans-ing. “One of the ways this can be accom-plished is by reducing electrical consump-tion. Potential benefactors of our researchinclude growers of flowering plants (forlow-intensity lighting applications) andyoung plant and vegetable crop growers(for high-intensity lighting applications).”
Low-intensity applications includecrops that require long photoperiods, orblocks of daylight. High-intensity applica-tions include plants that thrive best whentheir photosynthetic processes are boostedover short time spans.
50 Photonics Spectra June 2012
LEDs Lower Costs, Boost Crops Inside Greenhouses
Cooler, longer-lasting and more wavelength-specific than incandescentbulbs, far-red LEDs will be the green future of horticulture.
Researchers at Michigan State University aretesting the ability of LED systems to promoteplant growth inside greenhouses. Courtesyof Erik S. Runkle.
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The light-intensity range required forboosting plant growth depends upon thelocation, time of year, crop, temperatureand CO2 content in the air surrounding theplants, Runkle said. Given those vagaries,the common light intensities used to in-crease photosynthesis range from 50 to200 μmol/m2/s – or approximately 4100 to16,400 lx from high-pressure sodiumlamps. Horticulturists measure intensity inmolar units rather than lux because the lat-ter is defined by how light is perceived byhuman vision.
“Growers of day-length-sensitive crops
(many bedding plants and herbaceousperennials) can benefit from low-intensityphotoperiod lighting,” Runkle said. “People who grow plants in completelyenclosed environments can also benefitfrom LED lighting, such as a tissue-culture facility.”
“Greenhouse production of flowers,potted plants and vegetables has clear advantages over field production, wherecrops are exposed to the vagaries ofweather and other environmental condi-tions,” said A.J. Both, associate extensionspecialist at Rutgers University in New
Brunswick, N.J. Because modern green-houses require significant initial and on -going investment and consume a lot of energy, he added, it is important to useany resource as efficiently as possible.
“LEDs offer the potential to reduceelectricity consumption, while maintainingor even improving plant growth and devel-opment,” he said.
51Photonics Spectra June 2012
Orbital Technologies Corp. (Orbitec) of Madison, Wis., is a keysupplier of lighting systems for the greenhouse LED consortiumbased out of Michigan State University. Working with terrestrialsystems, however, was not the company’s starting point. The following is an interview with the company’s bioproducts andbioproduction systems head, Robert C. Morrow:
What is Orbitec’s purpose in making LED lighting systems?Morrow: We began making LED systems as part of our work developing plant research systems for space, and we began to expand that into traditional agricultural and research applications. In addition to LED systems, Orbitec develops aerospace life-support-system technologies and propulsion-related technologies.
Who is your typical customer, and how do you impress them with the benefits of LED lighting systems?Morrow: Most of our LED systems are currently developed ascustom systems to support university and government research.These customers generally are interested in the ability to individ-
ually control multiple spectral bands independently, and the ability to provide high photon flux levels. Much of our work has resulted from collaborative projects or word of mouth. We work with the customer to understand their requirements, determine what is feasible, and then design and fabricate the system.
What cooling systems do you recommend for LED lighting systems in greenhouse environments? Does this differ betweencelestial and space-based systems?Morrow: We primarily use forced convection (fans) for both our terrestrial and flight systems. For very high output arrays, we use a chilled water cooling system.
Is there an advantage to moving the LED light sources across the plant canopy?Morrow: For some agricultural applications, this can reduce hardware costs. We make custom systems that do this and areworking on future products that would use this technique.
LEDs That Fit Agriculture – on Earth and Beyond
C. Michael Bourget of Orbitec and Celina Gómez and Cary Mitchell of Purdue University adjust the red-to-blueratio and total photon flux on an overhead LED array that minimizes shading of solar irradiance throughoutthe day in the greenhouse. Courtesy of Robert C. Morrow, Orbitec.
Advantages of LEDs in Greenhouses
• Lower heat output, permittingproximity to plants
• Highly selectable wavelengths
• Lower cost of use
• Longer life than incandescentlighting
• Compact device size
• Flexible design options for horizontal or vertical lightingand for moving fixtures
• Potentially higher quantum efficiency
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Supplementing SolPlants contain phytochromes – proteins
that react to light in the way that the rodsand cones in eyes do. Phytochromes maypreferentially react to various wavelengths,and the proportion of proteins that react tored and far-red wavelengths in any givenplant type helps determine how much sup-plemental lighting will affect the plant. Aconsortium of research institutions, includ-ing Rutgers, has, for example, reported thatmore far-red than red tends to help mostplants grow faster, while more red than far-red can suppress growth.
Horticultural LED investigators alsohave noted that far-red light is particularlyuseful to plant growth and development,with 735 nm being the sweet spot formany crop plants. Far-red light particu-larly helps the development of plantstems, including the hypocotyls that markthe early stage of seedling development. It also enhances later leaf production andoverall growth rates. Improving the devel-opmental speed of hypocotyls helps espe-cially with grafting operations, includingincreasing speed and enhancing the gen-eral health of hybrids.
Supplementing the amount of light that
plants receive at the end of the day canpositively affect stem growth, which gen-erally happens at night for many planttypes. Adding far-red LED light for a short period after daylight helps promotestem, hypocotyl and leaf growth duringthe night following.
LEDs can be made to emit highly spe-cific wavelengths; e.g., keeping plantshappy with a continuous 735-nm bath.Unfortunately, the availability of far-redLEDs is very low.
At the University of Arizona in Tucson,for example, Chieri Kubota and her col-
leagues found that greenhouse-grown leaflettuce experienced more than 25 percentimprovement in growth when exposed tofar-red light for 3.3 minutes at the end ofeach growing day at an intensity of 46μmol/m2/s.
Whereas the sun has a well-definedtrace across the sky, LED devices could be placed in the most optimal spots. Un-like with incandescent lamps, proximity of LEDs to leaves and stems does notcause burning or dehydration of plants.However, LED placement is still not welldetermined, and there may yet be a dis-tance that defines “too close.” Studies are ongoing at Arizona, Michigan State,Rutgers and other institutions to find outwhere the truth lies.
Another open question is whetheradding motion to the light source mightaid growth conditions indoors. Passing a bank of LED emitters over an array ofyoung plants seems in some cases to enhance hypocotyl growth and to inhibit it in others.
“The main goal is to provide the lightwhere it is most needed,” Both said. “Asplants grow and develop, their size andconfiguration change. As a result, it may
52 Photonics Spectra June 2012
LEDs for Crops
Cuttings of herbaceous New Guinea impatiens are propagated under red andblue supplemental lighting from LEDs, shortly after sunset at Purdue University.Reprinted from Chronica Horticulturae, Vol. 52, No. 1 (2012). Courtesy of International Society for Horticultural Science.
Young tomato plants receive supplemental lighting from LED towers. While theplants are small, only the lower portion of the LED array must be lit, thus savingelectricity. Reprinted from Chronica Horticulturae , Vol. 52, No. 1 (2012). Courtesy of International Society for Horticultural Science.
LED Research Consortium
Michigan State University
Orbital Technologies Corp. (Orbitec)
Purdue University
Rutgers University
University of Arizona
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be more efficient to deliver the light at dif-ferent locations of what we call the cropcanopy.”
Whether moving light sources over thecanopy or even between rows is practicalor economically feasible remains to be determined. Both said that stationary LED sources likely will turn out to bepreferential.
More challengesDousing greenhouse crops in specific far-
red or other wavelengths may be great forthe plants themselves, but not so much forthe people tending to them. Low-intensityfar-red light may not lead to accidents, but itcertainly would color workers’ perceptionsof plant health come inspection time.
“Based on the absorption of light byplants, they are most efficient in convert-ing blue and red light in the process calledphotosynthesis,” Both said. “But underblue and red light, plants look very differ-ent when observed by the human eye.Therefore, additional colors may need tobe added to improve human perceptionduring the production process.”
Many companies advertise LED sys-tems for plant lighting, but few systemshave been tested extensively in commer-cial applications, Both said. In addition,claims about spectral output, intensity,lamp life, lamp decay, efficiency and otheraspects have been difficult to verify.
“The LED research consortium westarted under the leadership of Dr. CaryMitchell of Purdue University is attempt-ing to develop some standards and mea-surement procedures that the greenhouseindustry can use to determine what sys-tems are most appropriate for their spe-cific applications,” Both said.
The consortium thus far has workedwith Orbital Technologies Corp. of Madi-son, Wis., and the Regensburg, Germany-based Osram Opto Semiconductors AG todevelop LED systems in a range of wave-lengths.
Because LEDs are a relatively newtechnology for plant-lighting purposes,
53Photonics Spectra June 2012
LEDs for Crops
Lynn [email protected]
Master’s student Daedre Craig of Michigan State works with several plant species that receive various ratios of red and far-red wavelengths from overhead LEDs during night-interruption studies of floral induction and development. Courtesy of Erik S. Runkle.
Both said, much research is still needed todetermine their best use and application.
“It is very likely that the best use ofLEDs differs from crop to crop and evenduring the different life stages of a particu-lar crop,” he said. “Artificial light hasbeen used for plant growth applicationsfor over a hundred years, and we are stilldiscovering novel aspects as we learnmore about plant physiology, lightsources, control strategies, etcetera.”
It likely will take some time before researchers sufficiently understand the advantages and challenges associated withLEDs used for plant lighting, Both said,adding that rapid developments in LEDtechnology continue to present new obsta-cles to research and applications.
“LEDs offer the potential to reduce electricity consumptionwhile maintaining or even improving plant growth and development.”
– A.J. Both, Rutgers University
The use of LEDs for plant lighting isjust getting started, and there are manyquestions left unanswered about this appli-cation, Both said.
“Our research hopes to contribute to ourcollective understanding of plant lightingand the benefits and challenges of LEDlighting,” he added.
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Modeling Improves Fiber Amplifiers and Lasers
BY RÜDIGER PASCHOTTARP PHOTONICS CONSULTING GMBH
Fiber amplifiers and lasers offer interesting advantages over more traditional laser types, including pos-
sible cost savings. However, the perform-ance details often are more complicatedthan for bulk lasers as a result of strongsaturation effects, consequences of a highlaser gain and some peculiarities of quasi-three-level laser transitions. The design of such devices requires more than a few back-of-the-envelope calculations.
A trial-and-error approach easily canlead to time-consuming and costly itera-tions and nonideal results, not exploitingthe full performance potentials. In mostcases, the most efficient approach startswith numerical modeling, which allowsthe designer to analyze and solve prob-lems and optimize the design quickly –before buying any expensive parts orspending substantial lab time. Diagnosingproblems is much faster with a numericalmodel than in the laboratory because amodel, unlike a real amplifier or laser, isfully “transparent.” It allows inspection of optical powers and excitation densitiesanywhere within the fiber and at any time,and the effects of considered design modi-fications can be simulated quickly.
Laser-active ion behaviorFirst, consider a single laser-active ion
at some location in the fiber core beingexposed to some number of optical fields(pump and signal waves, amplified spon-taneous emission) with known intensities.Broadband amplified spontaneous emis-sion (ASE) can be considered as a set ofoptical channels with various wavelengths.All these optical fields can drive transi-tions between electronic levels (more precisely, Stark level manifolds) of theions, namely by absorption (from theground state or from excited states) and bystimulated emission. Additional transitionscan occur as a result of spontaneous emis-sion and nonradiative effects such as multi-phonon emission and energy transfers be-tween ions.
Figure 1 shows the simple example ofan Er3� ion, subject to a pump and signalwave, ignoring excited-state absorptionand upconversion effects. Because thenonradiative transition from level 3 to 2 is very fast, it often may be considered asinstantaneous, leading to a zero populationdensity of level 3. The model may then include only the levels 1 (ground state)and 2 (upper laser level), and pumping is considered as transferring ions directlyinto level 2.
The dynamics are governed by wave-length-dependent effective transition crosssections and the upper-state lifetime, apartfrom the optical intensities, and can be described with a set of rate equations.Powerful simulation software can evensolve nonlinear rate equation systems forsophisticated systems; for example, withmultiple metastable levels and energytransfers between various types of ions.
Some fiber manufacturers supply com-prehensive spectroscopic data for theirfibers, and as the industry matures, thiswill become the standard. Customers oftenhesitate to work only with guesses or trialand error, or to set up their own spectro-scopic measurements. Ideally, directly usable data sets for various commercialfibers are provided together with simula-tion software, or they can be produced on demand within the user support.
Local gain or lossOnce the level populations have been
calculated from the local optical intensi-ties, the local gain or loss coefficient forthe optical waves can be calculated. Thisalso depends on the doping concentrationprofile of the fiber and the optical inten-sity profiles, which may be wavelength-dependent. The software should be able to calculate these intensity profiles with amode solver or to work with profiles givenby the fiber manufacturer. The fiber alsomay have some background loss, althoughthis is negligible in many cases.
As an example, consider a signal andpump wave in a double-clad fiber. Figure2 shows that the signal wave has a strong
Photonics Spectra June 201254
Developing active fiber devices based only on experimental tests is highly inefficient, often leading to time-consuming, expensive iterations in the laboratory. Working with a numerical model is the bestway to learn how fiber devices work, how to optimize their designs and what their limitations may be.
Signal Absorptionand StimulatedEmission
MultiphononEmission
Pump
SpontaneousEmission
Figure 1. Simplified level scheme of Er3� ions exposed to a pump and a signal wave. Images
courtesy of RP Photonics Consulting GmbH.
Er3�-DopedFiber Core
Signal
Pump
Figure 2. Transverse profiles of the intensities of signal and pump in a double-clad fiber.
612_Modeling Feat_Layout 1 5/24/12 1:56 PM Page 54
overlap with the single-mode fiber core,whereas the pump wave fills the wholeundoped inner cladding, having only asmall overlap with the doped core. Theinner cladding actually supports a largenumber of modes, having substantiallydifferent overlap.
Precise modeling requires one to con-sider all modes separately, but in manycases it is sufficient to consider the wholepump wave as a single optical channelwith a top-hat intensity profile – at leastwhen strong mode mixing can be as-sumed; for example, resulting from a Dshape of the inner cladding or from tightbending. As a result of the low core over-lap in a double-clad fiber, the coupling ofthe pump wave to the ions often is muchweaker than that of the signal wave, evenif the pump cross sections are larger thanthe signal cross sections. This aspect hasimportant implications for the perform-ance details.
Dynamic simulationsIn some cases, the dynamic behavior of
the system is of interest. In principle, thisis relatively straightforward to simulate.Consider a simple case, where a signalpulse is amplified in a single pass througha fiber. Here, it often is not relevant forthe model that various parts of the fiber“see” the signal pulse at different times.Propagation times can then be ignored. It is sufficient to numerically divide thepulse into small temporal slices and thefiber into small pieces, and then to propa-
gate each temporal slice through all fiberpieces. When one slice travels through onefiber piece, it is amplified to some extent,and at the same time it extracts some ofthe stored energy; i.e., it changes the levelpopulations. Later slices may thus obtain a reduced power gain, which can lead topulse distortions.
In other cases, the propagation timescannot be ignored; e.g., they are essentialfor pulse formation in a Q-switched fiberlaser. Here, one can use a numerical tech-nique where each time step corresponds to the time required by light to propagate
further by the length of one fiber piece. In each time step, the total field distribu-tion in the laser resonator is moved for-ward by one fiber piece. Time delays outside the doped fiber also must be takeninto account. Technically, this is more demanding, and such simulations often require more computation time becausethe method enforces the use of rather short time steps.
Figure 3 shows the result of an examplesimulation for an actively Q-switchedfiber laser. Instead of a smooth pulse envelope, as is common for a bulk laser,the fiber laser emits a series of spikes because the lasing begins with amplifiedspontaneous emission, which is very un-evenly distributed in the resonator becauseof the high gain. For the simulation, Q switching with a very fast modulatorwas assumed, but it would be easy tostudy the effects of slower switching, both on the temporal shape and on thepower efficiency. Such simulations oftencreate surprising results because it is difficult to anticipate all relevant detailsand effects before the simulation.
Steady stateEfficient calculation of the steady state
for an amplifier or laser with constantinput powers can be substantially more demanding than a dynamic simulation because the distributions of optical powersand ionic excitation densities influenceeach other. Therefore, a self-consistent solution is required.
55Photonics Spectra June 2012
Figure 3. Temporal evolution of output power and averaged ionic excitation in a Q-switched fiber laser, simulated with the software RP Fiber Power. The separation of the spikes corresponds to one resonator round trip.
Figure 4. Distribution of steady-state pump and signal powers and the upper-state population in a fiber amplifier with a signal coming from the left side and a counterpropagating pump wave.
612_Modeling Feat_Layout 1 5/24/12 1:56 PM Page 55
First, we consider the simple case of anamplifier with a co-propagating pump andsignal light and with negligible ASE. Wealready know all optical intensities at theinput end, so we can calculate the excita-tions at this point. From that, we can cal-culate the local gain, which allows us topropagate the pump and signal powerthrough a first short fiber piece. Step bystep, we can propagate the powers and excitations all the way to the other fiberend. High precision is obtained simply byusing small enough fiber pieces, and thecomputation time for a single-pass propa-gation can be very short, even when using1000 pieces.
A more complicated case is that of anamplifier with a counterpropagating pumpand signal. Here, we know only the localpump intensity at the pump input end, andonly the local signal intensity at the oppo-site end. At no position do we initiallyknow all optical powers. However, there is a relatively simple method to solve thisproblem, called the shooting method.
We begin at the signal input end; for example, with an initial guess for theresidual pump power at this point. Thenwe propagate signal and pump through thefiber, using the fact that pump power risesin a backward direction according to thecalculated level of pump absorption. Atthe pump input end, we will generally notobtain the true input pump power, but wecan compare the propagated and the truepump input power and correct our guessaccordingly. An appropriate one-dimen-sional root-finding mechanism allows us
to find an accurate solution within a fewiterations. Figure 4 shows the power dis-tributions in an example case. The methodalso can be adapted to a linear fiber laser,where the backward-propagating signalwave is initially not known. Of course, the forward and backward signals must bemade consistent with the end reflectivities.
Although the shooting method is simpleand efficient in the aforementioned cases,it is not practical in other cases, where wehave multiple or even many backward-propagating fields. Here, we essentiallywould have to do a multidimensional rootfinding, which is substantially more diffi-cult – particularly for high-gain cases,where we can have exponential dependen-cies. Because such cases often occur, it isdesirable to have a method that can copewith them.
The basic principle can be that of a relaxation method. The simplest approachis to perform a sequence of steps, whereone always first calculates the opticalpowers resulting from the currently as-sumed ionic excitations and then updatesthe excitations according to the local optical intensities. The problem is that the convergence properties dependstrongly on the situation.
Although one may fine-tune an algo-rithm to be efficient in a specific situation,it is challenging to obtain reliable and efficient convergence in all situations, including high- and low-gain amplifiers(or amplifiers with different gain for dif-ferent signals), ASE sources and lasers.However, it is possible to achieve this goal
with a very refined algorithm. Elements of that can be to introduce some numerical“damping” to the calculated optical pow-ers and to automatically adjust various numerical parameters according to the“observed” convergence properties. RPPhotonics’ RP Fiber Power softwaremakes that approach applicable to a vastrange of situations. The user does not haveto deal with the iterative procedure but can just enjoy the fast convergence.
Learning by playingThe results of fiber amplifier and laser
simulations often exhibit surprising fea-tures. In one example, shown in Figure 5,a single pump wave at 920 nm (and nosignal) was injected into an ytterbium-doped fiber with no end reflections. Here,the distributions of pump power andupper-state population have quite surpris-ing shapes because of ASE. BackwardASE becomes quite strong on the left side,extracting more than 40 percent of thepump power. It substantially pulls downthe upper-state population, leading to increased pump absorption. The pump absorption is weaker at positions a littlefarther to the right, where ASE is weak.Roughly in the middle of the fiber, for-ward ASE becomes substantial, but thendrops again as it is reabsorbed (because ofthe quasi-three-level nature of Yb3�). Ad-ditional diagrams, not shown here, wouldreveal that the spectral shape of ASE atvarious positions and traveling in differentdirections can be extremely different.
The behavior of the system can changeprofoundly when changing the fiber lengthor the pump wavelength. It would be veryhard to fully understand and reliably pre-dict the behavior of such a system withoutnumerically simulating it. Even extensivemeasurements in the lab would not revealthe important role of forward ASE, as thathas substantial power at positions onlywithin the fiber, which are hardly accessi-ble. Further, the behavior can be substan-tially more complicated when additionalsignal channels and/or end reflections areadded.
Only numerical modeling can lead toquantitative understanding of device per-formance and, thus, is key to reachinghigh performance with the least possibledevelopment effort.
Meet the authorDr. Rüdiger Paschotta is founder and presidentof RP Photonics Consulting GmbH in Bad Dür-rheim, Germany; email: [email protected].
56 Photonics Spectra June 2012
Fiber Device Design
Figure 5. Distribution of pump and amplified spontaneous emission (ASE) powers and the upper-state population in an ytterbium-doped fiber pumped at 920 nm. RP Fiber Power software iteratively calculated
a self-consistent solution of optical powers and ionic excitations. Less refined numerical algorithms could beplagued by convergence problems or require extensive computation time in such cases.
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FEL Pulses and Ultrafast LasersTeam Up to Explore New Frontiers
BY ALAN R. FRY, SLAC NATIONAL ACCELERATORLABORATORY, AND MARCO ARRIGONI, COHERENT INC.
In the short time of their existenceas open-source research tools, free-electron x-ray lasers such as the Linac Coherent Light Source (LCLS)have offered a versatile and powerful
means of pushing the frontiers of atomic,molecular and materials sciences. Many ofthese applications rely on using a combi-nation of the femtosecond x-ray pulsesfrom the free-electron laser (FEL) and thefemtosecond optical pulses from advancedTi:sapphire lasers.
An FEL such as the recently developedLCLS at SLAC National Accelerator Lab-oratory can produce millijoule femtosec-ond pulses at x-ray wavelengths with un-matched brightness. Diverse types ofpump-probe experiments currently arebeing performed by using the FEL outputin conjunction with that of an ultrafastfemtosecond laser.
Pump-probe overviewIn the brief time that the LCLS has pro-
vided scientists with access to ultrafast x-ray pulses (the LCLS was commissionedfor this purpose only in 2009), a broad
range of experiments have been proposedor completed that use ultrafast opticalpulses as well. For example, an ultrafastlaser pulse can be used to promote a mo-lecular system into an excited state thatmay last for only tens of femtoseconds.The x-ray pulse is then used to probe thestructure of the sample while in this tran-sient state.
In biochemistry, it may be possible touse this approach to study the unfolding of proteins in real time. These experimentsare possible because the FEL pulses are 1 billion times brighter than conventionalx-ray sources, and single pulses can pro-duce diffraction patterns from small sam-ples that are bright enough for analysisand structure determination. This can en-able studies of samples such as nanocrys-tals, where the entire crystal is simultane-ously analyzed and vaporized by theintense pulse.
In condensed-matter physics experi-ments, a sample is irradiated with an ultra-fast pulse to cause lattice compression ormelting, while the x-ray pulse observesthe compression and relaxation in realtime, again relying on x-ray diffraction,absorption or scattering. In another broadrange of experiments to study dynamicproperties of crystal lattices, a laser-gener-ated terahertz pulse changes the magneticand electronic properties of samples thatare then probed with ultrafast x-rays fromthe FEL.1
Molecular alignment applicationsA particularly innovative class of exper-
iments using these lasers involves molecu-lar alignment. Here the ultrafast laser isused to align molecules in the lab frame.The aligned molecules are then probed bypolarized x-ray pulses from the FEL (seeFigure 1). A very successful example ofthis has been examining how Auger elec-trons are emitted relative to the molecularframe (principal axes).2
In Auger spectroscopy, high-energyphotons or electrons remove an electronfrom the inner core of an atom. As shown
57Photonics Spectra June 2012
Free-electron lasers are uniquelybright sources of extremely short x-ray pulses that can becombined with synchronized ultrafast laser pulses to performcutting-edge experiments inphysics and chemistry.
Electron Timeof Flight
MX-ray
Polarization
Linac CoherentLight Source
Half-WavePlate
800-nmAlignment
Pulse
Figure 1. Schematic of a typical laser pump/x-ray probe experiment showing how the pulses are overlapped in the sample and analyzed. (In this case, the resultant data “signals” are Auger electrons whose energy is analyzed via their time of flight. Figure reprinted with permission from J.P. Cryan et al, Phys Rev Lett, 105 (2010), 083004. Copyright 2010 by the American Physical Society.
612_Feat Coherent_Layout 1 5/24/12 2:35 PM Page 57
in Figure 2, this eventually causes an outershell (valence) electron to be ejected. Inmolecular systems, the kinetic energy dis-tribution of this electron contains fine de-tails related to the chemical bonds in themolecule. For example, a nitrogen atombonded to a carbon atom will produce apattern different from that of a nitrogenatom bonded to another nitrogen atom.The availability of femtosecond x-raypulses thus offers the potential to useAuger spectroscopy to probe changingchemical conditions on the femtosecondscale; i.e., on the timescale of the bondformation during a chemical reaction.
Scientists using the LCLS FEL recentlyadvanced this research in two ways thatenable novel measurements of moleculardynamics.2 First, they used the high inten-sity of the FEL pulses to remove two coreelectrons from nitrogen (N2) molecules(Figure 2). Second, they used an intense,800-nm polarized pulse from a Ti:sapphirelaser to drive coherent Raman interactionswith the rotating N2 molecules. The Ramaninteraction changes the rotational quantumstate of the molecule while also aligningthe axis of rotation of a significant popula-tion of the N2 molecules to the polariza-tion direction of the laser beam. As a re-sult, the axes of the molecules underexamination are no longer randomlyarranged but are preferentially aligned to alaboratory-fixed direction. This directioncan be switched at will simply by rotatingthe polarization direction of the ultrafastlaser beam.
A polarized FEL pulse then drives theAuger process before any collisions orother mechanisms can destroy the align-ment. The first published results from thislandmark experiment show that, as ex-pected from theory, the intensity of Augerelectrons emitted using lower x-ray ener-gies is dependent on the orientation of themolecules relative to the polarization ofthe x-rays (Figure 3).
Matter in extreme conditionsHigh-energy-density physics is con-
cerned with matter in states of extremepressure and temperature, such as the conditions found in stars, the cores oflarge planets and nuclear fuel under iner-tial confinement in fusion research. Manyunanswered fundamental questions remainabout the physics of materials in theseconditions, and ultrafast x-ray FELs nowprovide unique capabilities for measuringthe dynamic properties of the short-livedhigh-energy density states. For example,whether the standard gas equation (PV =nRT) holds under these extreme conditionsis still an open question. Since the 1970s,pulsed lasers have been used to drive ma-terials into these extreme conditions byrapid heating and compression of materi-als, and significant extension of the rangeof available energy density has been en-abled by amplified ultrafast lasers produc-ing intensities above 1018 W/cm2.
The LCLS Matter in Extreme Condi-tions instrument is being commissioned atSLAC specifically to explore this area ofphysics. The instrument comprises a largetarget chamber, a suite of x-ray diagnos-
tics and several laser systems, including a50-J, few-nanosecond Nd:glass laser and aterawatt 150-mJ, 35-fs Ti:sapphire laser.Examples of the experiments proposed totake advantage of this capability includeheating materials with optical lasers andusing x-ray diffraction, scattering and ab-sorption spectroscopy to probe the equa-tion of state. Other experiments will in-volve creating high-pressure matter bydriving a shock wave through a materialwith an optical laser and probing the stateof the compressed lattice with x-rays. Andyet others will use x-rays to rapidly heatmaterials before using ultrafast lasers fortime-resolved interferometric measure-ment of the velocity of the surface of thematerial.
Synchronizing FEL pulses, fs lasersTaking full advantage of the temporal
resolution in experiments involving ultra-fast and FEL pulses requires timing con-trol of the variable delay between thepulses on a timescale of 30 fs or less.There are two complementary approachesto meeting this challenge. A fundamentalrequirement is active synchronization ofthe ultrafast laser to the FEL master radio-frequency oscillator. To date, however,various sources of timing jitter in the x-raybeam at LCLS are difficult to reconcileand limit this synchronization to the >100-fs (rms) level. For many experi-ments where phenomena on the 10-fstimescale are important, this level of jitteris not adequate and requires a second ap-proach: measuring the relative timing between the laser and x-rays on a shot-by-shot basis. The raw data is then re-sorted,with every recorded data point re-binnedaccording to the measured delay betweenthe x-rays and the optical laser.
Obviously, this requires a method of re-liably measuring the temporal separationof the x-ray/ultrafast pulses on every shot.Eventually, scientists would like the abil-ity to see the complete temporal profile ofthe x-ray pulse, which will require com-plete temporal profile retrieval methodssuch as frequency-resolved optical gatingin the x-ray domain using a physical pro-cess that is sensitive to these x-rays andsignificantly faster than 30 fs. Scientists atSLAC and other FEL facilities haveshown that relative timing can be meas-ured by imparting a spectral and/or spatialchirp to the ultrafast pulse. This then re-flects off – or is transmitted through – a material whose optical properties are dy-namically modified by the x-ray pulse.
In one such method, a small fraction of
58 Photonics Spectra June 2012
Free-Electron Lasers
Time
Ener
gy
Ener
gy
P A
Figure 2. In Auger spectroscopy, a high-energy(e.g., x-ray) photon causes an inner-core electron tobe eliminated from the target atom or molecule. Avalence electron then drops down to fill the resultantorbital vacancy. This creates excess energy, which is released by ejection of another valence electronwhose kinetic energy is measured by time of flightor similar means. A detailed examination of the kinetic energy of the released electrons from a sample provides important information about thelocal chemistry of the sample.
Figure 3. Angular yield of Auger electrons for 90°,45° and 0° (blue, green, red) with respect to themolecular axis for double-core (two electrons) vacancies in prealigned nitrogen molecules. Clearly, this distribution peaks at 0° molecular orientation. Figure reproduced with permission from Physical Review Letters.
612_Feat Coherent_Layout 1 5/24/12 2:35 PM Page 58
the ultrafast laser pulse is collimated andreflected off a silicon nitride (Si3N4) mem-brane at a 50° angle of incidence beforereaching a CCD camera.3 Using this largeangle of incidence causes the time atwhich the pulse reaches the membrane tovary linearly across the collimated beam.The collimated x-ray pulse from the FELpasses through this membrane at normalincidence, releasing a large population ofcharge carriers and temporarily causing achange in the membrane’s refractive indexand, hence, optical reflectivity. This geom-etry effectively maps various relative ar-rival times of the two pulses across theprofile of the ultrafast beam that can beseen in the CCD camera output; the tem-poral overlap between the optical laser andthe x-rays manifests as a step in the inten-sity of the reflected ultrafast beam profile.Because this method uses only a smallportion of the ultrafast pulse intensity, andbecause more than 80 percent of the x-rayintensity passes through the membrane,sufficient x-ray flux is available for the actual experiment.
In a related study, the ultrafast laserpulse is focused into a sapphire disk tocreate a supercontinuum that is chirped bytransmitting it through a few centimetersof glass.4 A smooth section of this contin-uum (620 to 700 nm) is then transmittedthrough a thin Si3N4 membrane. Again,this is irradiated at normal incidence bythe collimated x-ray pulse, which causes atransient change in refractive index and, inthis case, optical transmission. The opticalpulse is then dispersed in a spectrographto produce a time-dependent distributionof wavelength that is recorded with aCCD. A step function in the intensity plotindicates the onset of the x-ray pulse witha measured rms accuracy of <25 fs.
Ultrafast laser system requirementsLCLS is equipped with a considerable
array of Ti:sapphire-based ultrafast laseroscillators and amplifiers, such as Coher-ent’s Vitara (oscillator) and Legend (am-plifier), as well as various wavelength-extension accessories. To take full advan-tage of the FEL’s capabilities, the ultrafastlaser should provide state-of-the-art per-formance and flexibility and yet be reli-able and easy to use.
For example, many experiments requireexternal timing synchronization to theFEL’s master radio-frequency system witha jitter of 100 fs or better. This simplifiesdata processing and eliminates the needfor pulse correlation measurements inmany applications. In addition, with an
LCLS beam time cost of more than$30,000 per hour, 24/7 reliability and minimum maintenance are mandatory!The decision to purchase Coherent Vitaraoscillators was determined partly by thefact that these next-generation flexiblelasers are one-box turnkey instrumentssupporting hands-free operation over thou-sands of hours, while also delivering state-of-the-art performance specifications.
Other key laser requirements of the fullamplifier system include high shot-to-shotstability, with fluctuations <0.5 percentand straightforward flexibility in switchingbetween quite different wavelength do-mains from the UV through mid-IR – evenproducing teraherz with appropriate usersetup.
Meet the authorsAlan R. Fry is deputy director of the Laser Sci-ence and Technology division at SLAC Na-tional Accelerator Laboratory in Menlo Park,
Calif.; email: [email protected]. MarcoArrigoni is director of marketing at CoherentInc. in Sunnyvale, Calif.; email: [email protected].
References1. M. Först et al (December 2011). Driving
magnetic order in a manganite by ultrafastlattice excitation. Phys Rev B, Vol. 84, Issue24, 241104(R).
2. J.P. Cryan et al (August 2010). Auger elec-tron angular distribution of double core-holestates in the molecular reference frame. PhysRev Lett, Vol. 105, Issue 8, p. 083004.
3. M. Beye et al (March 2012). X-ray pulse pre-serving single-shot optical cross-correlationmethod for improved experimental temporalresolution. Appl Phys Lett, Vol. 100, Issue12, p. 121108.
4. M.R. Bionta et al (October 2011). Spectralencoding of x-ray/optical relative delay. OptExp, Vol. 19, No. 22, p. 21855.
59Photonics Spectra June 2012
Free-Electron Lasers
Figure 4. (a) 100 nm of continuum is generated by focusing 800-nm Ti:sapphire pulses into 1-mm-thick C-plane cut sapphire. A reference HeNe is co-propagated with the 800-nm light. The continuum spectrum is shown in the inset (b). The spectrometer limits the effective bandwidth to a 620- to 700-nm smooth region that is used in this experiment. The pulses are chirped to 3 ps with 2 in. of SF11 glass. (c) The continuum thenprobes the Si3N4 membrane. The x-rays change the index in the membrane, thus changing the spectral transmission of the probe (d). Two equivalent spectra are separated into two distinct stripes, as shown in the inset (e). The reference HeNe spectral line is seen on the right side of this image. Figure reproduced with permission from Optics Express.
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Interferometer Keeps Optics Shop on Track
BY MIKE ZECCHINO4D TECHNOLOGY CORP.
Sometimes making transit run moresmoothly can create a few bumpselsewhere. The Modern Streetcar
Project in Tucson, Ariz., was designed tobe a sustainable transportation option con-necting the city center, the University ofArizona, the Arizona Health SciencesCenter and several residential, historic andshopping districts. It sounded good for thecommunity at large, but when personnel atthe National Optical Astronomy Observa-tory (NOAO) heard about the plans, theygot worried.
The NOAO’s Optics Shop is on theUniversity of Arizona campus, where itcoats, tests and assembles telescope op-tics and systems, including optics for the
3.5-m WIYN (a consortium comprisingthe University of Wisconsin, Indiana andYale universities, and NOAO) Telescopeon Arizona’s Kitt Peak. The facility also issituated directly along the streetcar pro-ject’s proposed path. So the staff was con-cerned that vibrations generated by thestreetcars – which are scheduled to passthe facility as often as every 10 minutesbetween 6 a.m. and 11 p.m. – would se-verely prohibit accurate interferometricmeasurements within the facility, saidGary Poczulp, NOAO’s Optics Shop andCoating Lab supervisor.
The facility already deals with a highdegree of ambient vibration, particularlywhen traffic is heavy on nearby roads. Its
large testing rigs are not vibration-isolated,which has required technicians to makemeasurements during off-hours, with air-handling equipment turned off.
Testing for vibration impactThere was the potential for several re-
search facilities on the University of Ari-zona campus to be affected by the project,both by vibration and by electromagneticfields generated by passing streetcars, saidShellie Ginn, program manager for theTucson Modern Streetcar.
In response to the NOAO concerns, theModern Streetcar Project hired ATS Con-sulting, a Pasadena, Calif.-based acousti-cal consulting firm, to analyze the street-cars’ potential impact. The firm used atechnique called vibration propagationtesting to simulate the effect of a passingstreetcar and placed accelerometersthroughout the Optics Shop’s coating andfabrication areas to measure the effects.
The predicted streetcar vibration ex-ceeds the measured nighttime ambient vibration in the low-frequency range whenmost heating, ventilation and air-condi-tioning (HVAC) systems are turned off,according to an ATS memorandum. Thereport also noted that, because the pre-dicted streetcar vibration exceeds themeasured nighttime ambient vibration insome frequency ranges, streetcar opera-tions may cause vibration levels that
Photonics Spectra June 201260
Dynamic interferometry allows the National Optical Astronomy Observatory’s optics lab to avoid heavy vibration when the city builds a streetcar line nearby.
Figure 1: Engineers faced vibration-isolation issues when it was found that the Tucson Modern Streetcar willpass within 100 feet of NOAO’s Optics Shop. Courtesy of ATS Consulting.
Figure 2: The AccuFiz interferometer was selectedto help the NOAO optics lab overcome a vibra-tion challenge caused by a new streetcar projectnear the lab. Courtesy of 4D Technology.
612_4DTech Telescope_Layout 1 5/24/12 2:10 PM Page 60
would interfere with interferometer tests in the Optics Lab.1
Several options for mitigating the ef-fects of vibration were proposed and con-sidered, including installing vibration iso-lation for equipment in the facility andincorporating vibration isolation into thetrack design. The latter options were foundto require massive isolation structures andto be prohibitively expensive. Relocation,a solution employed for another universitylaboratory located along the route, was notpossible for the Optics Shop because ofthe massive size of its equipment. And, ofcourse, restricting the hours of measure-ments in the shop would greatly limit thefacility’s productivity, while limiting thehours of operation for the streetcar woulddiminish its effectiveness and jeopardizeits fiscal well-being.
Vibration-insensitive testingNOAO staff suggested a different ap-
proach, Poczulp said, and began investi-gating laser-based instruments that canperform high-precision measurement evenin the presence of vibration and motion.
In traditional phase-shifting laser inter-ferometry, which can measure surfaceshape down to nanometer levels, multipleframes of measurement data are acquiredsequentially over hundreds of millisec-onds. This acquisition time is very longrelative to environmental noise such as vibration and air turbulence, particularly atthe nanometer scale. Vibration isolation ispossible but can be extremely expensiveon the large scale required by the shop’stesting setup.
Over the past decade, several compa-nies have introduced technologies that enable laser interferometry to be usedwithout isolation. In one such method, dy-namic interferometry, all measurementdata is acquired simultaneously in a singlecamera frame. The entire acquisition cycleis completed in less than a millisecond,more than a thousand times faster thanphase-shifting interferometry. Such fastacquisition time enables measurements tobe made despite vibration, without addi-tional isolation. Averaging multiple meas-urements removes the effect of air turbu-lence as well.
Dynamic interferometry, therefore, offered a potential solution to streetcar vibration, and with a cost approximatelyone-tenth that of other proposed mitiga-tion methods.
Several vendors held demonstrations for
NOAO and Modern Streetcar Project man-agement to prove the feasibility of themethod. “While the city of Tucson peoplehad agreed in principle that a vibration-insensitive interferometer was the way togo, they were interested in seeing howsuch a piece of equipment would be ableto mitigate our anticipated vibration prob-lems,” Poczulp said. The demonstrationssuccessfully showed the technique’s mer-its, and the instrument was chosen.
Poczulp said 4D Technology’s AccuFizinterferometer was selected because of itssmall size, which allows the instrument tobe moved easily between test stations andfacilities, and because of the flexibility ofits software, which would enable the sys-tem to be used for a variety of futuremeasurement tasks as well as for the cur-rent projects at the facility. The interfer-ometer also gave the shop significantlyimproved resolution and precision com-pared with its older, traditional measure-ment equipment.
Project managers were particularlyhappy that they found a solution from alocal vendor. “What are the chances offinding the solution in Tucson? That usu-ally doesn’t happen,” Ginn said. “Wewould have found a solution to the vibra-tion problem no matter what, but this op-tion made the most sense. We were able toimprove the working environment [at theOptics Shop] and at the same time supportthe local economy.”
The interferometer was delivered toNOAO in December 2011 and is now inservice at the Optics Shop. The system’s
vibration insensitivity has exceeded expec-tations, Poczulp said. “We are able tomeasure at pretty much any time of day,with HVAC equipment running and truckscoming and going at our dock,” he added.
For one test, the instrument was movedto an adjacent setup to complete opticaltesting for the One Degree Imager (ODI)instrument destined for the WIYN tele-scope. Poczulp said that the measurementswere completed quickly, and the opticaltesting, a major milestone for the ODIproject, was completed on time.
The streetcar project is now in its con-struction phase and is expected to haveminimal effect on measurements at the labwhen it becomes fully operational nextyear.
Meet the authorMike Zecchino is the marketing communicationmanager for 4D Technology Corp. in Tucson,Ariz.; email: [email protected].
AcknowledgmentsNOAO is operated by the Association ofUniversities for Research in AstronomyInc., under Cooperative Agreement withthe National Science Foundation. 4DTechnology Corp. develops and manufac-tures optical metrology instruments for applications in astronomy, aerospace, general optics and other industries.
Reference1. Analysis of Streetcar Noise and Vibration in
NOAO Laboratories. ATS Consulting Mem-orandum, April 7, 2011.
61Photonics Spectra June 2012
Figure 3: The vibration-insensitive interferometer at NOAO’s Optics Shop measures components for the WIYN Telescope’s One Degree Imager. Courtesy of NOAO and the Association of Universities for Research in Astronomy Inc.
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62 Photonics Spectra June 2012
Imaging Components & Systems
Hi-Def Compact Video Camera with USB Frame CaptureToshiba’s new IK-HR2D CMOS-based high-definition color camera deliverstrue progressive-scan, real-time video with the ability to send video frames directly to your computer via USB. This compact, one-piece camera providessharp, high-definition imagery in 1920 × 1080-pixel output at 60 frames persecond. Ideal for scientific, diagnostic, microscopy and industrial applications.
(810) [email protected]
Low-Noise 16-Bit, Cooled CCD CamerasDesigned for a wide range of applications in the life sciences, industrial and scientific imaging, the QSI 600 Series is a family of 16-bit, cooled CCD cameras with high sensitivity and linear response, and exceptionally low noise.
• High-speed USB 2.0. ROI rates up to 20 fps• Wide range of sensors up to 8.3 megapixels• Regulated cooling to >45 °C below ambient• Available internal 5-or 8-position color filter wheel• Windows and Linux software support
(888) [email protected]
Wavelength Meters Covering from 192 to 11,000 nm!Extending capabilities into the mid-IR range (up to 11 µm), TOPTICA’s wavelength meters can measure single-pulse, pulse, quasi-CW and CW lasers. The unique instrumental design features no moving parts, ensuringgreater stability with no down time. Our Fizeau-based wavelength meters provide the user with better accuracy, greater stability, faster measurementspeeds, terrific reliability and coverage from the hard-UV to the mid-IR. The effective high-speed measurement (up to 500 Hz) enables simultaneous measurement of up to eight lasers. The system features standard optionssuch as linewidth, multichannels, laser feedback-PID controller, TTL-trigger,diffraction grating and double pulse trigger. TOPTICA’s wavelength metersgive you everything you need and more!
(585) [email protected]
www.toptica.com
Microdisplays for Structured LightForth Dimension Displays’ high-resolution reflective microdisplays are usedglobally for structured light projection in 3-D optical metrology. The high fill factor (>96%) and linear gray-scale display technology, coupled with theflexibility of the 3DM driver interface, make this the perfect choice for 3-D metrology systems builders. The application-specific driver interface, with its small size, configurable timing, synchronization and I/O ports, hasbeen designed for easy integration into structured light projection systems.So if you want a fast, precise, accurate and cost-effective solution for your AOI, SPI or 3-D inspection system, contact our experts now.
+44 1383 827 [email protected]
Robust Multifilter Assemblies and Multizone FiltersEnhanced capabilities enable us to provide robust multifilter assemblies and multizone filters. The multizone filters can be customized for size, spectral performance and layout (number and size of zones). They addressneeds for optical filters for order-sorting, multispectral imaging, etc. Typicalcoatings include antireflection coatings. Filters include long-/short-pass andbandpass in the wavelength range from the UV (300 nm) to LWIR (15 µm).
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www.iridian.ca
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63Photonics Spectra June 2012
Imaging Components & Systems
CMOS SensorPHOTONIS announces the Lynx CMOS sensor for low-light imaging. Designed for camera applications where light levels will vary between full daylight and quarter-moon, it provides read noise well below 4e� at up to 100 fps, with superior signal-to-noise performance due to its large 9.7-µm2
pixels, high fill factor and <200-mW power consumption. Lynx CMOS is idealfor man-portable systems, unmanned posts and 24/7 CCTV surveillance.
(770) [email protected]
www.photonis.com
Precision Polymer OpticsG-S Plastic Optics manufactures precision polymer optics for imaging, scan-ning, detection and illumination applications. In addition to an extensive cata-log offering of plastic optics, the company has in-house capability to providecustom-designed diamond-turned and injection-molded prototypes, produc-tion injection molding of optics, thin-film and reflective coatings, and inte-grated optical solutions for the military, medical, commercial and consumermarkets. (585) 295-0200
iChrome MLE – The Most Advanced
Multilaser Engine for Multicolor ApplicationsThe iChrome MLE is a complete solution for demanding multicolor applica-tions in biophotonics. It comprises up to four diode lasers or, alternatively, up to three diodes and one DPSS laser fully integrated into one compact box.The individual lasers are efficiently combined, yielding highest power levels,and are delivered via one SM/PM fiber. TOPTICA’s ingenious COOLAC technol-ogy ensures a Constant Optical Output Level due to push-button autorecali-bration, ensuring exceptional long-term power stability. The microprocessor-controlled system enables flexible OEM integration in instruments such asmicroscopes and flow cytometers. High-speed analog (1 MHz) and digital modulation (20 MHz) allow fast switching of laser wavelength and intensity.
(585) [email protected]
www.toptica.com
Nanopositioning Stages, Motors and Sensors, and Hexapods PI’s precision positioners, piezo actuators, flexure guided stages and capacitive sensors combine subnanometer stability with submillisecond responsiveness.
• 1- to 6-axis stages with many digital control options • Ultrasonic motors for high-speed automation • Piezo stepping linear motors for high-force, high-precision applications • Hexapods for optics alignment • Hybrid linear translation stages for long travel and nanometer precision
(508) [email protected]
BeamMic, Entry-Level Laser Beam AnalysisSpiricon, global leader in precision laser measurement equipment and a Newport Corporation brand, has announced BeamMic™, a new laser beam analyzer that combines the essentials for monitoring laser performance in a low-cost entry-level system.
(866) [email protected]
www.ophiropt.com/photonics
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64 Photonics Spectra June 2012
Imaging Components & Systems
Making Life Easier for Photomultiplier UsersUsing photomultipliers is now even easier with the new HV2520 series of compact, low noise, low power HV Bases. Incorporating socket, voltage divider and HV supply, this series of HV Bases operates from low-voltage DC and is compatible with a wide range of 25mm and 30mm diameter photomultiplier types in analog, pulse counting or photon counting applications. Being very efficient, the HV Bases can support high signal currents while avoiding the heat dissipation issues associated with resistivevoltage dividers. They can also be integrated into the QL30 series of photomultiplier housings.
(800) [email protected]
www.et-enterprises.com/about-us/news
New sCMOS CameraThe new Zyla 5.5-megapixel scientific CMOS (sCMOS) camera is ideal for research and OEM usage. Zyla sCMOS offers a 100-fps rate, rolling and snapshot (global) shutter modes, and ultralow noise performance in a light, compact and cost-effective design. Zyla achieves down to 1.2-electron rms read noise and can read out the 5.5-megapixel sensor at a sustained 100 fps through a “10-tap” Camera Link interface. A highly cost-effective “3-tap” version is also available, offering up to 30 fps.
(800) [email protected]/zyla
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� InSb Infrared Camera Telops Inc. has released the TEL-1000 MW, an InSbcooled infrared camera that covers the 3.6- to 4.9-µm range. It can be customized to cover arange from 1.5 to 5 µm, combining good spatialresolution and a high frame rate. It captures up to200 fps at full frame (640 � 512 pixels) and up to600 fps when windowing (320 � 256 pixels) isused. The camera features patent-pending real-time processing and real-time temperature calibra-tion algorithms, providing either raw or thermallycalibrated data in real time without the need for
external blackbodies. It also can be equipped with automatic exposure control to adjust the exposure time according to the scene’s dynamic temperature variations. It facilitates observation of dynamic events by combining real-time temperature calibration, real-time processing andnonuniformity correction into one imaging tool. Telops [email protected]
� High-Speed CameraPhotron Inc.’s high-speed Fastcam SA-X cameradelivers 12,500 fps at full 1024 � 1024-pixel reso-lution and features 64-GB onboard memory and a 12-bit dynamic range. It permits short exposuretimes and is used in materials science, fluid dynam-ics, defense and aerospace research, ballistics imaging, combustion research, and shock waveand detonation applications. With a 20-µm pixelsize and a 12-bit analog-to-digital converter (Bayer system color, single sensor), it includes a dual high-speed Gigabit Ethernet interface, a fast hardwaretrigger and flexible frame synchronization to exter-nal devices. Camera control is provided by an op-tional keypad or via Photron Fastcam Viewer soft-ware. The capping shutter facilitates automatedimage calibration, and the software developmentkit enables integration with user-specific softwareas well as wrappers for MatLab and LabView.Photron [email protected]
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� High-Power IR EmittersOpto Diode Corp.’s OD-110L GaAlAs infraredemitters feature ultrahigh optical output with a nar-row optical beam for night-vision and military imag-ing applications. They are housed in a three-lead,hermetically sealed TO-39 package to accommo-date the 0.6604 × 0.6604-mm chip. There are fourwire bonds on die corners, and all surfaces aregold-plated. Typical total power output at 25 °C is110 mW, and minimum is 55 mW with a peakemission wavelength at 850 nm. The absolute max-imum rating at 25 °C (case) for power dissipation is1000 mW, with a continuous-forward-current ratingof 500 mW. Lead-soldering temperature (1⁄16 in.from the case for 10 s) is 260 °C. Storage and oper-ating temperatures range from −40 to 100 °C,making them suitable for use in harsh environmentsand for integration into illuminators, markers, andsystems using night-vision goggles and cameras. Opto Diode [email protected]
� Plastic Linear PolarizersEdmund Optics’ TechSpec high-contrast plastic linear polarizers feature a good extinction ratio and high trans-mission of unpolarized light from 400 to 700 nm. They im-prove contrast by reducing glare, rendering them suitablefor applications such as edge detection, and they can beused with cameras employing small-aperture lenses. Whenunpolarized light enters a linear polarizer, light polarizedperpendicular to the polarization axis is absorbed, whilelight parallel to the polarization axis is transmitted. Theplastic linear polarizers use a proprietary stretchedpolyvinyl alcohol (PVA) film to create the polarization axis. For increased protection and durability, the PVA filmis laminated between two plastic plates. The polarizers are available, unmounted, in 12.5- to 300-mm diameters.Edmund [email protected]
� Copper Laser Mirrors A line of oxygen-free high-thermal-conductivitycopper mirrors is being offered by Laser ResearchOptics, with or without water cooling, for high-power multikilowatt CO2 laser systems. They areavailable in polished, uncoated versions or withplasma gold coatings. Providing >99.6% reflec-tivity at 10.6 µm with �/4 surface accuracy, theyare designed for laser beam delivery and beamshaping. Available in 1- to 3-in. outside diametersizes, the mirrors feature a clear aperture of 90%of the diameter and are effective for beam bend-ing in all beam paths and beam guidance sys-tems, from simple measurement setup to high-performance lasers. Laser Research [email protected]
Single-Frequency CW Green Laser �Spectra-Physics, a Newport Corp. brand, has launched the Millennia Edge single-frequency, continuous-wave green laser. The 532-nm industrial-grade laser featuresultralow optical noise of <0.02% rms, goodbeam quality with M2 <1.1, and pointing stability of <2 µrad/°C in a compact pack-age. It is suitable for pumping Ti:sapphireand other lasers, including carrier-envelope-phase stabilized systems, and for holography an d interferometry applications. The rugged instrument outputs 5 W of single-longitudinal-mode CW green power. [email protected]
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Small Laser Modules
Laser Components GmbH’s LC-LMD series smalllaser modules measure 7 mm in length. Lasermodules designed for the consumer market are often, for lack of space and finances, self-assembled. Laser diodes, collimators and driveelectronics are commonly assembled. The LC-LMD series offers an alternative: complete lasermodules with a small design. High demand hasled to production of additional types. Modulesthat have a diameter of 3.3 mm, focusablemodules and coaxially aligned lasers are en-abling additional applications. Besides the 650-nm types that already have been introduced,versions are offered at 635, 780 and 850 nm.They are available as individual devices as wellas in large production volumes. Laser Components [email protected]
Laser Beam Steering Correction
A laser beam steering correction system intro-duced by New Focus, the Picomotor mirror-mount-based GuideStar II, controls laser point-ing and position drift. It includes two indepen-dent Picomotor-actuated motorized mirrormounts to provide manual and active four-axiscontrol. Two miniature CMOS cameras provideposition sensing and continuous tracking oflaser beam positions and profiles. A patentedcontrol algorithm ensures alignment of the laserbeam in X and Y, and in the near and far fields.The controller can be connected to cameras andto a Windows computer via USB, making it easyto view beam profiles, position and shape datain real time, or track, store and analyze thedata later. The DVD software and setup menuguide users through installation. Intuitive set-tings menus permit user control of camera andbeam stabilization parameters. The system issuitable for research, laboratory and industrialapplications. New [email protected]
Long-Life Fiber-Pigtailed Lasers
Coherent Inc. has expanded its OBIS family of plug-and-play laser modules with a fiber-pigtailed option at 405, 488 and 640 nm. The devices offer 1 m of single-mode, polariza-tion-preserving fiber, terminating in an FC/APCconnector and simplifying integration into OEMinstruments. The compact, self-contained lasersproduce low noise and can be directly modu-lated. Their output beam delivers low drift tomaintain efficient coupling, and a telecom-typearchitecture yields drift-free optomechanicalcoupling. The modules have longer lifetimes because they address facet damage caused bythe high power density at the fiber facets. Appli-cations span the life sciences, metrology and inspection, where fiber delivery is used forminiaturization. Examples include fluorescence-based techniques such as flow cytometry, confo-cal microscopy and array readers for drug dis-covery. The wavelength scalability of the OBISplatform enables optimum excitation of targetfluorophores. Coherent [email protected]
Mirror Mounts
Newport Corp. has unveiled the stainless steelSuprema SN200 series mirror mounts for 50.8-mm-diameter optics. The clear edge mir-ror mounts are compact, enabling unencum-bered access to the edge of the mirror. They areavailable in either right- or left-handed versionsfor situations where the mirrors have to touchor be in proximity. The mounts are availablewith two or three locking actuators, renderingthem suitable for demanding research applica-tions. The precision mounts use micropolishedcarbide pads and 100-thread-per-inch adjust-ment screws, which enable smooth, high-reso-lution alignment and good stability. Newport [email protected]
High-Power NIR Light SourceOcean Optics’ Vivo near-infrared compact tung-sten halogen light source for VIS-NIR spec-
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troscopy across the 360- to 2000-nm range iscompatible with the company’s spectrometers,optical fibers and sampling accessories. It deliv-ers powerful output for reflection and othermeasurements. The high-power light source issuitable for near-infrared analysis of pharma-ceuticals, grains and oils, and for food safetyapplications. Its four tungsten halogen bulbs,arranged for reflection measurements at a 90°angle to the detection fiber, can be turned onand off for precision control. The powerful bulboutput enables spectrometer integration timesof 1 ms. To ensure accuracy, an inner coolingfan reduces the risk of overheating the sample.The light source can be attached to the com-pany’s RTL stage or other standard for stabilityand control. Powered by an included universalsupply, its tungsten halogen bulbs are rated fora 2000-h lifetime.Ocean [email protected]
Automation Machine Controller
Aerotech has introduced a motion control industrial computer for its Automation 3200multiaxis automation machine controller. Thepanel- or rack-mount (1U or 4U) computer hasfront and top connections that simplify installa-tion with panel-mount devices, while the 183 �183 � 70-mm enclosure saves space. OptionalFireWire, USB and serial ports, dual Ethernetand solid-state storage enhance operation. The
controller includes active cooling, full functional-ity on a single printed circuit board, optionalSSD and advanced motherboard watchdogtechnology. Features include a 2-GHz proces-sor, a 12-VDC or 120-VAC power adapter,audio, integrated graphics, and a Windows XPPRO or Windows 7 operating system. Applica-tions include semiconductors, data storage,medical laser processing, automotive and ma-chine tools. A software-only motion controlleroffers 32 axes of synchronized motion control. [email protected]
Thermoelectric Temperature Controller
ILX Lightwave, a Newport Corp. brand, haslaunched the LDT-5940C, a thermoelectric tem-perature controller for testing laser diodes. Itfeatures 60 W of temperature control, an intu-itive front panel, and IEEE 488.1 general-pur-pose interface bus and USB 2.0 remote inter-faces. With a digital proportional integral deriv-ative (PID) control loop, it achieves temperaturestability of <±0.003 °C with output currentnoise and ripple of <2 mA rms. It incorporatespreset PID values and an autotune PID modethat determines optimal values. It is compatiblewith thermistors, resistance temperature detec-tors, and LM335 and AD590 integrated circuitsensors. The linearized thermistor sensor modeachieves ±0.2 °C accuracy from �30 to 85 °Cwith a standard 10-K⏐ thermistor. Interlocksconnect the controller to a laser diode driverand will disable the laser output if the controlleris over the user-configurable temperature limit.LabView drivers are available for downloadfrom the company’s website.ILX [email protected]
Fluorescence Imaging Light SourcesThe PhotoFluor II and PhotoFluor II NIR lightsources for quantitative fluorescence imaginghave been unveiled by 89 North. With a 1600-h-lifetime prealigned lamp and extended-UV(PhotoFluor II) or extended-NIR transmission(PhotoFluor II NIR), they operate from 360 to800 nm. The PhotoFluor II provides enoughpower in the UV for DAPI and Hoechst imaging.The metal halide source’s DC power supply sta-bilizes lamp output over time for minimal fluctu-ation during time-sensitive experiments. Thesoftware control interface allows operators toadjust the shutter, choose filter position, ad-vance the filter wheel, change settings and rename wheel contents. Liquid light couplingminimizes vibration at the microscope, and theliquid lightguide maximizes output. Applicationsinclude cyan, green and yellow fluorescent pro-tein; mCherry, Texas Red, MitoTracker Red,FITC, TRITC, Di-4-ANNEPS, Fluo-4, Fura Red,Cy7, IRDye 800, AlexaFluor 750 and iRFP. 89 [email protected]
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FIB-SEM Workstation
Carl Zeiss’ Auriga system combines the AurigaCrossBeam focused ion beam/scanning electronmicroscope (FIB-SEM) workstation with a pulsedmicrofocus laser for ablation of materials andfor examining samples where the target struc-ture is buried under material layers that mustbe removed. The laser beam does not damagethe sample. The Trumpf nanosecond pulseddiode-pumped solid-state scanning laser oper-ates at 355 nm. To protect the workstation anddetectors from debris, the system has a separatechamber for laser operation. After the structureis prepared, the sample is transferred to themain chamber for SEM examination or FIB pol-ishing. CAD software controls the scanner head,enabling the user to predefine complex patternsof the sample structure. Applications include ex-amination of next-generation nanotechnologyprocessors and thin-film solar cells, semiconduc-tor manufacturing, photovoltaics, polymer elec-tronics, pharmaceuticals, life sciences and mate-rials research. Carl [email protected]
Bright LED Line-Scan Illuminator
ProPhotonix Ltd.’s Cobra Max, an addition tothe patented Cobra machine vision lighting illu-minators, delivers increased power and func-tionality. A compact line-scan illuminator with amodular form factor, it produces a uniform lineup to 5 million lx and offers field-adjustable op-tics for selecting the optimum lens position for a specific application. It is available in lengthsup to 5 m and in a range of power levels andwavelengths from the ultraviolet to the visibleand infrared. It uses chip-on-board technologyto ensure high brightness and uniformity. Op-tions include a strobing function and onboard
Ethernet control. Applications include web andline-scan inspection of foil, plastic film, printedcircuit boards, semiconductors, flat panel dis-plays, paper, currency and glass.ProPhotonix [email protected]
Electrostatic Actuator IC
Teledyne Dalsa Semiconductor has announcedits DH9685AB electrostatic actuator integratedcircuit (IC). Using proprietary high-voltageCMOS/diffusion metal oxide semiconductortechnology, it is designed for next-generationhigh-density small-footprint systems using mi-croelectromechanical or micro-optoelectro-mechanical systems activation with electrostaticforces. It offers low power consumption andball-grid-array packaging, and it achieves inte-gration with the smallest footprint area perchannel. It has 96 high-voltage channels up to240 V in a 17 � 17-mm package and is RoHS-compliant. It operates through a digital three-wire interface. Features include a 16-bit digital-to-analog (D/A) converter with sample andhold; power consumption <500 mW; 24 selec-table quads of four high-voltage channels pro-grammable with four low-voltage 16-bit D/Aconverters; an adjustable output range; single-polarity low-voltage power supplies; stablehigh-voltage output over time; and an internaldiode for temperature monitoring.Teledyne Dalsa [email protected]
NIR Streak Camera
Hamamatsu Photonics UK Ltd. has unveiled astreak camera with sensitivity in the near-in-frared up to 1650 nm. The C11293 simulta-neously records intensity versus time versus position (or wavelength) with high temporal res-olution. The streak photocathode is made ofInP/InGaAs, and its sensitivity is several ordersof magnitude higher than that of S-1. To sup-press dark current and make the device suitablefor low-light-level applications, the photocath-ode operates at approximately �100 °C bymeans of liquid nitrogen cooling. The time reso-lution of the C11293 is better than 20 ps fullwidth half maximum. It can run at arbitrary rep-
etition rates up to a maximum of 20 MHz, mak-ing it easy to combine with many experimentalsetups. Applications include time-resolved spec-troscopy in semiconductor physics, quantumdots, carbon nanotubes and other nanostructureresearch, photovoltaic research and photoniccrystals. Hamamatsu Photonics UK [email protected]
Dedicated Digital Reproduction Camera
Phase One’s iXR is a medium-format dedicateddigital reproduction camera for high-quality dig-itization, including fine-art reproduction and in-dustrial applications. Using it with proprietaryCapture One software, reproduction photogra-phers can move from live view to capture withthe click of a mouse. The industrial design elim-inates the mirror and viewfinder, reducing mov-ing parts and vibration, and its aircraft-gradealuminum alloy camera body enables perform-ance under demanding conditions. The systemis available in 80-, 60- and 40-megapixel con-figurations as well as in a stand-alone camerabody. It is FCC (Class A)-, CE- and RoHS-com-pliant. Operating temperature ranges from �10 to 40 °C, and the system runs on Windows7 and Mac OS X 10.6 or later. Applications alsoinclude machine vision and aerial photogram-metry.Phase Onewww.phaseone.com
Laser Beam Analysis System
Ophir-Spiricon LLC has introduced BeamMic, a laser beam analyzer that measures a beam’ssize, shape, uniformity and mode content. Beamintensity profiles are displayed simultaneously in 2- and 3-D. Statistical analyses can be per-formed on measurement functions, and mini-
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mum/maximum limits can be set for pass/failtesting. A report generator enables cutting andpasting of results, images and settings. Displaysare zoomable and resizable, shown in satellitewindows on one or multiple monitors. The sys-tem performs ISO measurements and test meth-ods on beam width, diameter, power/energydistribution and spatial orientation. Statisticalanalysis can be performed on all measure-ments, such as mean, standard deviation andminimum/maximum. The software sets the gainand exposure time of the camera array to maxi-mize the beam signal while keeping it belowsaturation. Ophir-Spiricon [email protected]
Bright-Field LED Illuminator
Prior Scientific Inc. has enhanced its line of illu-mination products for microscopy. The Bright-Field LED illuminator is supplied in a flexiblepackage that can be fitted to most modern up-right and inverted microscope systems. With≥10,000 h of operating lifetime, the LED re-places the standard lamp house and is easily fitted to the microscope. Control of the unit is achoice of manual, transistor-transistor logic oron/off, eliminating the need for shutter mecha-nisms. Intensity can be regulated manually via a small controller for precise adjustment of theillumination. The intensity is sufficient for phase contrast and differential interference
contrast imaging. Illumination is even across thefield of view, and constant color temperature isassured at all intensities. The LED can be pow-ered from the company’s ProScan and OptiScancontrollers via the shutter connections or as astand-alone light source with a separate powercable. Prior Scientific [email protected]
Dual-View Imaging System
Navitar Inc. has introduced a dual-view imagingsystem that allows simultaneous viewing of asingle subject and image capture at multiplefields of view. A single lens is presented to twoimaging channels that can be fixed, zoom or acombination, and two light sources and wave-lengths can be used. The system has a mini-mum optical magnification range of 0.09� to6.13�, corresponding to 120-mm-diagonalfields of view on a 2⁄3-in.-format sensor down toa 0.65-mm diagonal on a 1⁄4-in. sensor. Maxi-mum optical magnification ranges from 20� to583� using a 50� objective. The system com-
prises a combination of a fixed 1� tube lens,precise eye lens, zoom 6000 or 12� zoom lens;a dual-view fold block; LED light sources; andadapter tubes. Applications include camera sensor inspection, laser beam monitoring andthin-film transistor repair. Navitar [email protected]
Image Analysis Software
Leica Microsystems has released Tissue 1A 2.0image analysis software for drug discovery andfor capture, management and analysis of digitalpathology images. Combining fluorescence andbright-field analysis with cell modeling, it per-forms immunohistochemistry (IHC) biomarkerquantification and retrieves quantitative, repro-ducible data from tissue-based IHC studies.Color separation and multimarker colocalizationenable measurement of multiple antigen im-munostaining in bright-field or fluorescent sam-ples. Cell modeling detects and quantifies dif-ferential expression of staining in cellular com-partments, providing insight into cytoplasmic,membrane and nuclear biomarker localization.Dual staining enables researchers to identify cell
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cohorts at the molecular level. Algorithms areadjusted for different markers, tissue and proto-cols. With high-throughput batch analysis, thesoftware processes whole slides, regions of in-terest or tissue microarray cores, and integratesanalysis results with the user’s slides. Leica [email protected]
Fiber-Coupled Optical Isolator
A polarization-maintaining optical isolator opti-mized for 638-nm diode lasers has been un-veiled by Blue Sky Research. The fiber-pigtailedPSFI is designed for isolating visible laser diodesfrom reflected light that may otherwise produceinstability in the source laser or induce damageto it. It is tuned for light in the wavelengthrange of 635 to 670 nm but can be optimizedto meet any application inside the visible spec-trum. The device is designed for fiber-to-fiberindustrial applications, where polarization main-tenance, low insertion loss and high optical iso-lation are key criteria. The all-passive optical
design ensures reliable fiber alignment and per-formance over a wide range of operating envi-ronments. All fibers are polarization-maintain-ing for their specified wavelength and may be spliced to lasers or fitted with FC/APC con-nectors. Blue Sky [email protected]
Blue-Light Transilluminator
Syngene’s UltraBright-LED blue-light transillumi-nator safely images fluorescently labeled gelson the bench or inside the company’s G:BOXimaging systems. It uses two high-intensity LEDarrays that produce uniform, bright excitation at470 nm, and it illuminates dyes that excite at420 to 480 nm. It is suitable for visualizing
small amounts of ethidium bromide and non-toxic DNA stains, including the proprietary UltraSafe Blue dye, SYBR Safe and GelGreen,and SYPRO Ruby and Pro-Q Diamond proteinstains. It images fluorescent DNA gels and fea-tures a filter that enhances band contrast. It vi-sualizes faint bands and enables precise bandcutting and production of high-quality imagesfor analysis and publication. It is an alternativeto UV for work with nontoxic fluorescent dyes, isnot as harmful as UV and does not photo-nickDNA samples. [email protected]
70
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JULY2012 Astronomical Telescopes + Instrumentation (July 1-6) Amsterdam. Contact SPIE, +1 (360) 676-3290;[email protected]; spie.org.
Sixth International Meeting on Developments in Materials, Processes and Applications of Emerging Technologies(MPA) (July 2-4) Alvor, Portugal. Contact MPA Tech, +44 161 918 6673; [email protected]; www.mpa-meeting.com.
Eighth International Conference on Optics-Photonics Design and Fabrication(ODF ’12) (July 2-5) St. Petersburg, Russia.Contact Eugenia Brui, +7 911 998 21 81;[email protected]; www.odf2012.ru.
17th Optoelectronics and CommunicationsConference (July 2-6) Busan, South Korea.Contact OECC 2012 Secretariat, +82 42 4727461; [email protected]; www.oecc-2012.org.
XVII Symposium on High Resolution Molecular Spectroscopy (HighRus-2012)(July 2-7) Zelenogorsk, Russia. Contact Yurii N.Ponomarev, V.E. Zuev Institute of AtmosphericOptics, +7 3822 49 20 20; [email protected];symp.iao.ru/en.
AM-FPD 12: The Nineteenth InternationalWorkshop on Active-Matrix Flat Panel Displays and Devices – TFT Technologiesand FPD Materials (July 4-6) Kyoto, Japan.Contact AM-FPD 12 Secretariat, c/o MobaraAtecs Ltd., [email protected]; www.amfpd.jp.
XVIII International Conference on Ultrafast Phenomena (July 8-13) Lausanne,
Switzerland. Contact European Physical Society,+33 3 89 32 94 48; [email protected];www.up2012.org.
SEMICON West 2012 (July 10-12)San Francisco. An event of SemiconductorEquipment and Materials International. ContactSEMI Customer Service, +1 (408) 943-6978;[email protected]; semiconwest.org.
39th COSPAR Scientific Assembly (July 14-22) Mysore, India. Contact COSPAR(Committee on Space Research) Secretariat,+33 1 44 76 75 10; [email protected];www.cospar-assembly.org.
Lasers in Medicine and Biology Conference(July 22-27) Holderness, N.H. Contact HollyTobin, Gordon Research Conferences, fax: +1(401) 783-7644; [email protected]; www.grc.org.
M&M 2012: Microscopy and Microanalysis(July 29-Aug. 2) Phoenix. Contact MicroscopySociety of America, +1 (703) 234-4115; [email protected];www.microscopy.org.
Mirror Technology SBIR/STTR Workshop(July 31-Aug. 3) Rochester, N.Y. Contact SPIE,+1 (360) 676-3290; [email protected];spie.org.
AUGUSTSecond International Conference on Optical, Electronic and Electrical Materials(Aug. 5-7) Shanghai. Contact Conference Secretariat, +86 519 8633 4730; [email protected]; www.oeem.org.
Optical MEMS and Nanophotonics Conference (Aug. 6-9) Banff, Alberta,
Canada. Contact Megan Figueroa, IEEE Photonics Society, +1 (732) 562-3895;[email protected]; www.mems-ieee.org.
SPIE Optics + Photonics (Aug. 12-16)San Diego. Includes NanoScience + Engineering; Solar Energy + Technology; Organic Photonics + Electronics; and OpticalEngineering + Applications. Contact SPIE, +1 (360) 676-3290; [email protected];spie.org.
Sixth EOS Topical Meeting on Visual and Physiological Optics (EMVPO 2012)(Aug. 20-22) Dublin. A European Optical Society event. Contact Julia Dalichow, EOS –Events and Services GmbH, +49 511 2772673; [email protected];www.myeos.org.
Fifth EPS-QEOD Europhoton Conference:Solid State, Fibre and Waveguide Coherent Light Sources (Aug. 26-31)Stockholm. A European Physical Society Quantum Electronics and Optics Division event. Contact EPS, +33 389 32 9448; [email protected]; www.europhoton.org.
Ninth International Conference on Group IV Photonics (GFP) (Aug. 29-31)San Diego. Contact Rose Ann Bankowski, IEEE Photonics Society, +1 (732) 562-3898;[email protected]; www.gfp-ieee.org.
SEPTEMBERMIOMD-XI Infrared Optoelectronics: Materials and Devices (Sept. 4-8) Chicago.Contact Manijeh Razeghi, Northwestern University, +1 (847) 491-7251; [email protected]; miomd-11.northwestern.edu.
Speckle 2012, International Conference on Speckle Metrology (Sept. 10-12) Vigo,Spain. Contact Speckle 2012, Universidade de Vigo, [email protected]; speckle2012.uvigo.es.
SPIE Photomask Technology (Sept. 10-13)Monterey, Calif. Contact SPIE, +1 (360) 676-3290; [email protected]; spie.org.
Nanosystems in Engineering and Medicine (Sept. 10-13) Incheon, South Korea.Contact SPIE, +1 (360) 676-3290; [email protected]; spie.org.
XIX International Symposium on HighPower Laser Systems and Applications(Sept. 10-14) Istanbul. Ozgur Tataroglu,Tübitak Mam, +262 677 3133; [email protected]; hplsa2012.mam.gov.tr.
International Manufacturing TechnologyShow 2012 (Sept. 10-15) Chicago. ContactAMT – The Association for Manufacturing Technology, +1 (800) 524-0475; [email protected]; www.amtonline.org.
Avionics, Fiber-Optics and Photonics Conference (AVFOP 2012) (Sept. 11-13)
HAPPENINGSPAPERSSPIE Photonics West (February 2-7) San FranciscoDeadline: abstracts, July 23SPIE is accepting papers for Photonics West. The event will encompass BiOS, focusing on areas such as photonic therapeutics and diagnostics; LASE, addressing laser source engineering and nonlinear optics; MOEMS-MEMS, considering micro- and nanofabricated electromechanical and optical components; OPTO, discussing optoelectronic materials and devices, photonic integration and other topics; and Green Photonics, including solid-state lighting and display. Contact SPIE, +1 (360) 676-3290; [email protected]; spie.org.
IS&T/SPIE Electronic Imaging (February 3-7) Burlingame, CaliforniaDeadline: abstracts, July 23Late abstracts may be considered. Researchers are invited to submit their latest findings at ElectronicImaging, which is sponsored by the Society for Imaging Science and Technology (IS&T) and SPIE. The conference program areas are 3-D imaging, interaction and metrology; visualization, perceptionand color; image processing; image capture; computer vision; mobile imaging; and media processingand communication. Topics to be considered include real-time imaging and video processing, andvideo surveillance and transportation imaging applications. Contact SPIE, +1 (360) 676-3290; [email protected]; spie.org.
SPIE Medical Imaging (February 9-14) Buena Vista, FloridaDeadline: abstracts, July 30; August 6 Check conferences for extended deadline. Papers are invited for SPIE Medical Imaging’s technical conferences, which include Physics of Medical Imaging; Imaging Processing; Computer-Aided Diagnosis; Image-Guided Procedures, Robotic Interventions and Modeling; Biomedical Applications in Molecular, Structural and Functional Imaging; and Advanced PACS-based Imaging Informatics and Therapeutic Applications. Contact SPIE, +1 (360) 676-3290; [email protected]; spie.org.
71Photonics Spectra June 2012
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Cocoa Beach, Fla. Contact Megan Figueroa,IEEE Photonics Society, +1 (732) 562-3895;[email protected]; www.avfop-ieee.org.
Photonics in Switching 2012 (PS 2012)(Sept. 11-14) Ajaccio, France. Contact Michel Dupire, SEE, +33 1 5690 3709;www.ps2012.net.
JSAP-OSA Joint Symposia (73rd Japan Society of Applied Physics Annual Meeting 2012) (Sept. 11-14)Matsuyama, Japan. Symposia held with Optical Society. Contact JSAP, +81 3 58020864; [email protected]; www.jsap.or.jp/english.
SPRC 2012 Annual Symposium (Sept. 17-19) Stanford, Calif. Contact Stanford Photonics Research Center, +1 (650)723-5627; [email protected];photonics.stanford.edu.
Metamaterials 2012: Sixth InternationalCongress on Advanced ElectromagneticMaterials in Microwaves and Optics (Sept. 17-22) St. Petersburg, Russia. [email protected];congress2012.metamorphose-vi.org.
SPIE Laser Damage 2012 (Sept. 23-26)Boulder, Colo. Contact SPIE, +1 (360) 676-3290; [email protected]; spie.org.
ICALEO, 31st International Congress on Applications of Lasers and Electro-Optics(Sept. 23-27) Anaheim, Calif. Contact Laser Institute of America, +1 (407) 380-1553; [email protected]; www.icaleo.org.
IEEE Photonics Conference 2012 (Sept. 23-27) Burlingame, Calif. Contact MaryS. Hendrickx, IEEE Photonics Society, +1 (732)562-3897; [email protected]; www.ipc-ieee.org.
SPIE Remote Sensing and SPIE Security +Defence (Sept. 24-27) Edinburgh, UK. ContactSPIE, +1 (360) 676-3290; [email protected]; spie.org.
Seventh International Conference on LaserInduced Breakdown Spectroscopy (LIBS2012) (Sept. 29-Oct. 4) Luxor, Egypt. [email protected]; tel./fax: +202 35675335; libs2012-niles.org.
22nd International Symposium on OpticalMemory (ISOM’12) (Sept. 30-Oct. 4) Tokyo.Contact ISOM’12 Secretariat, c/o Adthree Publishing Co. Ltd., +81 3 5925 2840; [email protected]; www.isom.jp.
OCTOBER23rd IEEE International SemiconductorLaser Conference (ISLC) (Oct. 7-10)San Diego. Contact Rose Ann Bankowski,
IEEE Photonics Society, +1 (732) 562-3898;[email protected]; www.islc-ieee.org.
IONS-12 Naples Conference (Oct. 10-12)Naples, Italy. An event of IONS, the International OSA (Optical Society) Network of Students. Contact IONS Committee,[email protected]; www.ions-project.org.
Neuroscience 2012 (Oct. 13-17) New Orleans. Contact Society for Neuroscience, +1(202) 962-4000; [email protected]; www.sfn.org.
Frontiers in Optics 2012/Laser ScienceXXVIII (Oct. 14-18) Rochester, N.Y. Annualmeetings of OSA and American Physical Society/Division of Laser Science, respectively.Contact Optical Society, +1 (202) 416-1907;[email protected]; www.frontiersinoptics.com.
22nd International Conference on OpticalFiber Sensors (OFS-22) (Oct. 15-19) Beijing.Contact [email protected]; www.ofs-22.org.
Photonex 2012 (Oct. 17-18) Coventry, UK.Contact Clare Roberts, XMark Media Ltd., +441372 750 555; [email protected];www.photonex.org.
72
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aaADVERTISER INDEX
73Photonics Spectra June 2012
Photonics Media Advertising Contacts
Please visit our websitePhotonics.com/mediakit for all our marketing opportunities.
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Andor Technology .................64www.andor.com
Applied Scientific Instrumentation Inc. .............34www.asiimaging.com
Argyle International ...............20www.argyleoptics.com
BaySpec Inc. .........................47www.bayspec.com
Bristol Instruments Inc. ............14www.bristol-inst.com
Cargille Laboratories ..............48www.cargille.com
Castech Inc. ...........................36www.castech.com
Coherent Inc. .........................27www.coherent.com
DataRay Inc. .........................12www.dataray.com
Directed Energy Inc. ...............43www.ixyscolorado.com
DRS Technologies Inc. ..............9www.drs.com
Edmund Optics .................18-19www.edmundoptics.com
ET Enterprises/ADIT/Electron Tubes .....................64www.et-enterprises.com
Excelitas Technologies .........CV2www.excelitas.com
Fermionics Opto-Technology ................37www.fermionics.com
Forth Dimension Displays .............................62www.forthdd.com
G-S PLASTIC OPTICS .............63www.gsoptics.com
Gooch & Housego .................69www.goochandhousego.com
Hellma USA ............................8www.hellmausa.com
HORIBA Scientific ..................67www.picocomponents.com
Iridian Spectral Technologies .......................62www.iridian.ca
ISP Optics .............................15www.ispoptics.com
Laser Institute of America .........................29www.icaleo.org
LightMachinery Inc............20, 30www.lightmachinery.com
LightWorks Optics Inc. ............................7www.lwoptics.com
Master Bond Inc. ...................66www.masterbond.com
Meller Optics Inc. ..................48www.melleroptics.com
Mightex Systems ....................70www.mightexsystems.com
Moxtek Inc. ...........................42www.moxtek.com
Newport Corporation .............33www.newport.com
Novotech Inc. ........................24www.novotech.net
Nufern ................................CV3www.nufern.com
Ophir-Spiricon LLC ................63www.ophiropt.com
Photonics Media ........39, 49, 64, 70, 72www.photonics.com
PHOTONIS USA Inc. .............63www.photonis.com
PI (Physik Instrumente) L.P. ......63www.pi.ws
piezosystem jena GmbH .........................34www.piezojena.com
Power Technology Inc. ...........11www.powertechnology.com
Qioptiq Inc. ...............21, 23, 25www.qioptiq.com
Quantum Scientific Imaging Inc. .......................62www.qsimaging.com
Research Electro-Optics ...................CV4www.reoinc.com
Ross Optical Industries ............................26www.rossoptical.com
Sensors Unlimited Inc. ............31www.sensorsinc.com
Spectra Physics, A Newport Corporation Brand ...................................6www.newport.com
Spectrogon US Inc. ................72www.spectrogon.com
SPIE International Society for Optical Engineering .......13www.spie.org/aboutop
Stanford Research Systems Inc. ..........................3www.thinksrs.com
StellarNet Inc. ........................38www.stellarnet-inc.com
Tohkai Sangyo Co. Ltd. ..........66www.peak.co.jp
TOPTICA Photonics Inc. ................62, 63www.toptica.com
Toshiba Imaging Systems Division ............35, 62www.cameras.toshiba.com
Zygo Corp. ...........................40www.zygo.com
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p PEREGRINATIONS
Laser swarm could swat asteroids away
It sounds like the climactic scene from a sci-fi thriller: A group of small satel-lite-operated lasers flying in formation
redirects an asteroid headed for cata-strophic collision with Earth. But this isn’t the movies; this is a technique thatcould radically change asteroid-deflectiontechnology.
Researchers at the University of Strath-clyde in Glasgow, UK, are exploring thepossibility that relatively small satellitescollectively could fire solar-poweredlasers at close range to a threatening asteroid. The approach could have advan-tages over current methods, which focuson large, unwieldy spacecraft.
“We could reduce the threat posed bythe potential collision with small- tomedium-size objects using a flotilla ofsmall, agile spacecraft, each equipped with a highly efficient laser, which ismuch more feasible than a single largespacecraft carrying a multimegawatt,” said project leader Massimiliano Vasile, a reader in the university’s mechanical and aerospace engineering department.
“Our system is scalable – a larger aster-oid would require adding one or morespacecraft to the flotilla – and intrinsicallyredundant: If one spacecraft fails, the oth-
ers can continue,” Vasile added.Although large asteroids do not often
collide with Earth, the situation is notwithout precedent. More than a centuryago, a meteorite believed to be about 120ft across entered the atmosphere overSiberia and exploded in the sky. The Tun-guska event, named after a river in the re-gion, devastated 800 sq miles of remoteforest – felling an estimated 80 milliontrees.
Smaller asteroids, which pose a lesserthreat, collide with Earth more frequentlybut are likely to burn in the atmosphere.
One problem with asteroid deflection isthat, when the laser begins to break downthe surface of the object, the resultingplume of gas and debris impinges thespacecraft and contaminates the laser,Vasile said. But the group’s laboratorytests proved that the contamination level islower than expected and that the lasercould continue to function for longer thananticipated, he added.
A major advantage is that the laser doesnot have to be fired from the ground: Hav-ing to travel through the atmospherewould constrain its range of action.
The laser swarm also could help controlthe accumulation of space debris – objects
created by humans that remain in orbit.The lasers could lower the original orbit of debris and reduce congestion, Vasilenoted.
“While there is significant monitoringin place to keep track of these objects,there is no specific system in place to remove them, and our research could be a possible solution,” he said.
The above photo, taken in an experimental laboratory, demonstrates the process of shining a solar-poweredlaser onto an asteroid. At right, Strathclyde researchers Alison Gibbings and Massimiliano Vasile are develop-ing a novel technique that would use a group of smaller satellite-operated space-borne lasers to redirect aster-oids and manage human-created space debris. Images courtesy of University of Strathclyde photographerGraeme Fleming.
74 Photonics Spectra June 2012
Caren B. [email protected]
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