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May / 2012 3-D Displays Eliminate Need for Glasses Also in this issue: Time Delay Integration Speeds Up Imaging Wafer-Etching Process Brightens Future for LEDs
May / 2012
May/1
2Diffractive M
icro-Optics • Time Delay Integration • W
afer Etching
3-D DisplaysEliminate Need for Glasses
Also in this issue:Time Delay IntegrationSpeeds Up Imaging
Wafer-Etching ProcessBrightens Future for LEDs
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May 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:
• Supercapacitors created from laser-scribed graphene• Hidden 3-D objects imaged • Star comb aids search for exoplanets
30 | FASTTRACKBusiness and Markets
Impact of PV panel penalties pondered
39 | GREENLIGHTFull spectrum boosts solar cell power
10 | EDITORIAL
41 | LASERS IN USEby Antonio Triventi, CHP, CLSO, National Institute for Laser Safety Officers and Health PhysicistsHow to Develop a Laser Safety Culture
82 | PEREGRINATIONSAlexander Graham Bell, we can hear you now
NEWS & ANALYSIS
COLUMNS
70 | BRIGHT IDEAS79 | HAPPENINGS81 | ADVERTISER INDEX
DEPARTMENTS
THE COVERDevelopments in autostereoscopic displays are discussed by Gregg Favalora of Optics for Hire, beginning on page 44. Design bySenior Art Director Lisa N. Comstock.
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Photonics Spectra May 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 5
www.photonics.com
44 | HITTING EVERY ANGLE WITH AUTOSTEREOSCOPIC 3-D DISPLAYSby Gregg Favalora, Optics for HireAutostereoscopic display – creating imagery that looks 3-D without special glasses – is moving forward, thanks to advances in lens arrays, electro-optics, diffusers and software.
50 | TIME DELAY INTEGRATION SPEEDS UP IMAGINGby Xing-Fei He and Nixon O, Teledyne Dalsa Inc.The flat panel display industry depends on this line-scan technology for high-speed inline automatic optical inspection under light-starved conditions.
56 | WAFER-ETCHING PROCESS BRIGHTENS FUTURE FOR LEDSby Derek Mendes, Imtec Acculine LLCFaster and less costly than dry etching, high-temperature wet etching holds promise for scalable manufacturing of energy-efficient LEDs.
60 | 193-nm LITHOGRAPHY OPENS DOORS FOR DIFFRACTIVE MICRO-OPTICSby Marc D. Himel and Jim Morris, DigitalOptics CorporationUpgrades in tools for manufacturing diffractive optics have enabled new applications in the visible and near-IR regimes requiring large angular distributions.
65 | VISION SOFTWARE ENABLES NASA ROBONAUT TO SEEby Dr. Lutz Kreutzer, MVTec Software GmbH The first robotic humanoid to visit the International Space Station uses sophisticated software and a multiple-sensor stereovision system to recognize complex patterns.
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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e EDITORIAL COMMENT
Transfer Technology and Grow
CLEO:2012 is right around the corner, and Photonics Spectra will be there. Thisyear, we are proud to be the media sponsor for the annual Technology Transfer Program, which will take place on Thursday, May 10. We have attended this event
each year since its inception and are pleased to play a more active role this time around.
Working with OSA, we produced a webinar on May 2 about the CLEO 2012 TechnologyTransfer Program, to bring some additional attention to this important session, which will be held in the exhibit hall during show hours on May 10. While we understand thatexhibitors and visitors are busy during the show, we believe that this is an important, informative event, and we hope they will make time to attend it. If you missed our web-inar, please check it out online – much of the information shared there will not be covered during the CLEO program. Experience the webinar, “CLEO: 2012 Technology Transfer Program Preview,” at your leisure at Photonics.com/webinars.
Mike Torrance, VP of business development at Electro-Optics Technology and a memberof the CLEO: 2012 Technology Transfer Committee, was in the webinar lineup to talkabout the May 10 program, which will include tutorials and a technology transfer show-case. Marcos Dantus, president of BioPhotonic Solutions, talked about his experience receiving a license-ready technology and lessons learned along the way in building a successful startup company. Offering insights on the University of Rochester technologytransfer programs and license-ready technologies were Corine Farewell, U of R tech trans-fer office director, and her colleague Patrick Emmerling, technology licensing associate.
Technology transfer affects our industry deeply, and we want to cover it in a meaningfulway in the pages of Photonics Spectra. So, we want to know what you think about the subject. I will be at CLEO this year with Melinda Rose, our senior editor and LightMatters Weekly Newscast host, and we look forward to speaking with you there.
Investing in the future Laurin Publishing was founded in 1964 by Teddi and Fran Laurin, who invested time andmoney to give a voice to the young and growing photonics industry. The company has operated out of a number of buildings in Pittsfield, Mass., since then, growing beyondpublishing Photonics Spectra to add BioPhotonics, Europhotonics, Photonics.com andLightMatters Weekly Newscast, as well as the industry standard Photonics Buyers’ Guide,published since 1954.
Today, our staff is growing to meet our readers’ changing needs, and Tom Laurin, Teddiand Fran’s son and the current company president, recently purchased a building near our current location to give our organization a home base from which to expand and keeppace with the changing technology demands of our audience. “This building allows us tophysically expand as needed,” Tom said, “and is a serious commitment to the future of our company. It’s a sign of our confidence in the continued evolution and growth of thephotonics industry.”
“We are pleased to be able to expand our operation while staying in downtown Pittsfield,which has been our home for so long, as well as to expand opportunities beyond the tradi-tional print publications.”
Our mailing address will remain the same: PO Box 4949, Pittsfield, MA 01202-4949, and you can always find us at Photonics.com, where you can read industry news, watchLight Matters and other videos, and subscribe to our magazines and newsletters.
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. Anthony J. DeMariaCoherent-DEOS LLC
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 May 2012
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LASERS & MATERIAL PROCESSINGOPTICAL SYSTEMS
INDUSTRIAL METROLOGYTRAFFIC SOLUTIONS
DEFENSE & CIVIL SYSTEMS
®
k k h bl d f l dd
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Welcome to
Photonics Spectra May 201212
Photonics Media’s industry-leading site features the latest industry news and events from around the world.
Twice each month, Gary Boas, our nomadic contributing editor, chronicles his takeon the photonics industry through his blog - Different Wavelengths. Whether hetakes inspiration from pop culture, old sci-fi comic books or government policy,Gary has a knack for telling stories that have the reader conjuring new ideas,questioning old theories or remembering what made science so appealing in thefirst place. To explore Gary’s blog, visit www.photonics.com/DifferentWavelengths.
Interactive Laser Wavelength Chart Photonics.com presents a look at the major commercial laser lines, the wavelengths they produce, and their many applications. Visit www.LaserLookUp.com.
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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Lighting for Crop ProductionLEDs are gaining traction in crop production, especially in remote areas withoutdependable year-round sunlight or where specialty crops are in demand.
Photonics Spectra May 2012
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.
FELs Plus Ultrafast Lasers for Scientific ResearchAdvances in FELs and titanium:sapphire ultrafast lasers support various applications in experimental research.
Numerical Modeling Improves Fiber Amplifiers and Lasers
Designing fiber amplifiers and lasers requires more than a few back-of-the-envelope calculations.
Interferometric StabilityThrough Heavy Vibration
A new streetcar line in Arizonasounded good for the community, but staff at an optics shop along theline would have to deal with the extravibration it would cause.
In the June issue of
Photonics Spectra …
Spectral Imaging Monitors Food SafetySpectral imaging sensors are meeting the food-industry requirements for improvedmargins, greater food safety and improved product quality.
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Supercapacitors created from laser-scribed grapheneLOS ANGELES – A novel graphene-based electrode, produced with a standardLightScribe DVD optical drive, ends thesearch for an optimal electrochemical capacitor. The discovery could pave theway for a new class of flexible energy-storage devices.
Electrochemical capacitors, also calledultracapacitors or supercapacitors, storehigher amounts of charge than regular capacitors and have garnered attention as energy-storage devices because theycharge and discharge faster than batteries.However, unlike batteries, they are limitedby low energy densities.
Researchers have sought an electro-chemical capacitor that combines a bat-tery’s high energy density and a capaci-tor’s power performance.
Now, scientists from the University ofCalifornia, Los Angeles, have developedhigh-performance electrochemical capaci-tors with graphene electrodes.
“At the early stages of this research, we invented the method of convertinggraphite oxide to graphene using theLightScribe DVD drives found in ourcomputers,” said Maher El-Kady, a UCLAgraduate student and lead author of thestudy. “Microscopic analysis showed thatthe produced graphene is well exfoliatedwithout any sticking together.”
The LightScribe laser simultaneouslyproduces electrodes with an open networkstructure reducing the electrolyte ions’ diffusion path and allowing a fast, high-power charge.
“We also measured an interestingspecific surface area of over 1500
m2/g, potentially useful for high charge capacity,” El-Kady said.
“Additionally, the electrical conductiv-ity of this graphene, which is another keyfactor for high-power supercapacitors, wasvery decent. We thought this could be theperfect material for making high-perfor-mance supercapacitors.”
To demonstrate the idea to his groupleader, professor Richard B. Kaner, El-Kady developed a device and used it tolight an LED.
“I needed some electrolyte to make thedevice, and since our lab is not primarilyset for making batteries and supercapaci-tors, I placed a purchase order for a newelectrolyte,” he said. “However, I was soexcited that I wanted to make it rightaway, so I looked around the lab for someuseful electrolyte. I found an old bottle ofan electrolyte that dates back to maybe 10years ago, which I thought might work. Imade the device and charged it for a fewseconds and, interestingly enough, it wasable to light the LED.”
Evaluations of the device demonstratedultrahigh energy-density values in variouselectrolytes, while the high power densityand cycle stability of supercapacitors areretained.
“We have tested the device for over10,000 charge/discharge cycles, and the de-vice maintains about 97 percent of its per-formance,” El-Kady said. “This contrastswith a lifetime of less than 1000 cycles for
conventional rechargeable batteries.”The team also tested the device’s
shelf life over four months and dis-covered that there was no sign of
decrease in performance, he said. “We believe that our device will pave
the way to a completely new class of flex-ible energy-storage devices,” El-Kadysaid. “This may find applications as aflexible power supply for roll-up computerdisplays, keyboards, wearable electronicsthat harvest and store energy produced bybody movements, and as energy-storagesystems to be combined with flexible solar cells.”
Commercial batteries and supercapaci-tors are considered hazardous because oftheir toxic, corrosive materials. The liquidelectrolytes within batteries are known tocatch fire under certain conditions, whichmakes them difficult to discard.
To address this, “we further replacedliquid electrolytes used in commercialelectrochemical capacitors with a polymergelled electrolyte, which also acts as aseparator, further reducing the devicethickness and weight, and simplifying thefabrication process,” El-Kady said. “Thismeans that electrochemical capacitors areimmune from leaking problems.”
To test the solid-state device for flexiblestorage under real conditions, they placedit under constant mechanical stress and an-alyzed its performance.
“The supercapacitor continues to func-tion with no degradation, even after bend-ing and straightening multiple times,” hesaid. “We also tried applying a load on thedevice and, interestingly enough, the de-vice stored more charge.”
Next, the scientists hope to demonstratethat the materials and devices can bescaled up in a cost-effective manner.
“Our initial calculations show that theprice of the precursor, graphite oxide, andthe whole process is viable for commercialapplications,” El-Kady said. “We are alsotrying to use this technique to build anumber of different devices such as sen-sors. The combined properties of the laser-scribed graphene make it potentially use-ful as flexible, all-plastic and inexpensivesensors.”
The work appeared in Science (doi:10.1126/science.1216744).
NEWSTECH
Photonics Spectra May 201216
A closer look at the most significant photonics research and technology headlines of the month
Schematic showing the structure of laser-scribed graphene supercapacitors. Courtesy of UCLA.
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Hidden 3-D objects imaged CAMBRIDGE, Mass. – A new ultrafasttime-of-flight imaging technique uses reflections from a nonmirrored surface to recover 3-D shapes hidden from sight, essentially allowing the camera to captureimages around corners.
Scientists at MIT’s Media Lab recov-ered 60 images from an ultrafast camerausing 60 femtosecond laser positions toproduce recognizable 3-D images of awooden figurine and foam cutouts outsidethe device’s line of sight.
The findings could lead to imaging systems that allow emergency respondersto evaluate dangerous environments or to vehicle navigation systems that can negotiate blind turns. The instrument alsocould be used with endoscopic medicaldevices to produce images of previouslyobscure regions of the body. The study appeared in Nature Communications (doi:10.1038/ncomms1747).
Femtosecond lasers formerly were usedto produce extremely high speed imagesof biochemical processes in laboratory set-tings, where the pulses’ trajectories werecarefully controlled.
“Four years ago, when I talked to peo-ple in ultrafast optics about using fem-tosecond lasers for room-size scenes, they said it was totally ridiculous,” saidRamesh Raskar, an associate professor atMIT and leader of the new research.
“It has been, and still is, difficult to getimaging information at these speeds,” Andreas Velten, a former postdoctoral as-sociate in Raskar’s group, told PhotonicsSpectra. “We expect emerging technolo-gies to make this easier in the near future.”
To recover the images of the obscuredwooden figurine, the scientists fired shortbursts of light from a Ti:sapphire laser to-ward an opaque screen. The light reflectedoff the opaque panel, then bounced aroundthe staged room and re-emerged, strikingthe camera detector, which took measure-ments every few picoseconds. Because thelight bursts are so short, the system cangauge how far the light has traveled bymeasuring the time it takes to reach thedetector. Light bursts were fired severalmore times at several angles on the screen.
The data collected from the ultrafastsensor was processed by algorithms devel-
oped by the scientists. The team’s image-reconstruction algorithm uses a techniquecalled filter backprojection, which is thebasis of CAT scans. Although blurry, the3-D images were easily recognizable.
The reconstruction quality may change,however, if there are multiple objects inthe room. In the experiments, Raskar’sgroup found that problems associated withpeering around a corner are similar tousing multiple antennas to determine thedirection of incoming radio signals. Theteam hopes to use this insight to improvethe image quality that the system producesand to enable it to handle more clutteredvisual scenes.
“Reconstruction quality does depend onscene complexity to some degree,” Veltensaid. “Whether or not multiple objects canbe distinguished depends on the resolution
of the system at that given point. The armsand torso of the mannequin in our publica-tion [are] an example of close surfacesthat are still separated.”
At this time, it is not possible to recovermoving objects, but after the system is op-timized for speed, reconstructions shouldbe possible in a few seconds’ time. Be-yond that, resolution would have to besacrificed, Velten said.
“Collision avoidance would require extremely low resolution, since we onlyneed to know if there is something aroundthe corner and not what,” he added.
The present setup cannot be moved out-side of the lab; however, it would be easyto build a more compact, power-efficientsetup that could be moved and operated insuch conditions without chilled water orhigh-voltage outlets, Velten said.
17Photonics Spectra May 2012
Top photo, the experimental setup with the hidden object. Courtesy of Christopher Barsi and Andreas Velten,MIT Media Lab. Bottom left, the image captured around the corner shows a projection of a 3-D confidencemap of the reconstructed volume. The scientists used ultrafast illumination and imaging to analyze scatteredbackground light. They computationally reconstructed this image from the data. Courtesy of Velten et al, MIT.Bottom right, a sketch describing the MIT concept. Courtesy of Tiago Allen.
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Just how far away can the setup be fromthe object to be imaged?
“This is an interesting topic for furtherresearch,” he said. “The possible dimen-sions depend on the desired reconstructionresolution, the size of the available wall,the distance between the wall and the ob-ject, the distance between the wall and the
camera and laser, the scene complexity,the laser power and the signal-to-noiseratio of the detector.”
Next, the team plans to improve thesetup and algorithm and to develop newhardware solutions to test the method overa variety of application scenarios.
In a related side project, which ap-
peared on p. 22 of the March 2012 issueof Photonics Spectra, the scientists cap-tured movies of light in motion at a 2-pstime resolution.
“Modifying our detection setup allowsus to record virtual trillion-frames-per-sec-ond movies of light interacting with table-top scenes,” Velten said.
t TECHNEWS
Star comb aids search for exoplanetsBOULDER, Colo. – A new laser fre-quency comb soon may be able to answerone of the most intriguing scientific ques-tions: Are there other earthlike planets inour galaxy capable of supporting life aswe know it?
A collaboration of the National Instituteof Standards and Technology (NIST), theUniversity of Colorado at Boulder andPenn State University brings together thebest of laser science, frequency combs and precision astronomical instrumenta-tion. The researchers’ goal is to determinewhether life might exist on other planets,said Scott Diddams, a NIST physicist and
co-creator of the frequency comb. The device has for the first time cali-
brated measurements of infrared starlightfrom stars other than the sun by preciselymeasuring the frequencies of their emittedlight. The results suggest that combs even-tually will fulfill their potential to boostthe search for Earth-like planets to thenext level.
“The laser frequency comb we used isunique because its mode spacing of 25GHz is significantly larger than typicalcombs, which might have a mode spacingof 100 MHz to 1 GHz,” Diddams toldPhotonics Spectra. “Another unique fea-
ture is that it was designed to be com-pletely transportable, which enabled us totake it out of our lab in Boulder, move itto the McDonald Observatory and operateit there with the 9.2-m Hobby-Eberly Tele-scope and the Penn State UniversityPathfinder spectrograph.”
Another distinctive feature is that it op-erates in the near-infrared. All other combscurrently used for astronomical observa-tions operate in the visible spectrum.
“Despite its challenges, the near-in-frared has the particular advantage that acertain class of stars (called M stars) emitmost of their light in this spectral region,”
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said Steve Osterman, an astronomer at theUniversity of Colorado. “Moreover, thereare many M stars in our galaxy nearby theEarth (60 percent of the stars within about30 light-years of the Earth are M stars),making them excellent candidates in asearch for exoplanets.”
To search for planets orbiting distantstars, astronomers look for periodic varia-tions in the apparent colors of starlightover time. A star’s nuclear furnace emitswhite light, which is modified by elementsin the atmosphere that absorb certain nar-row bands of color. Periodic changeswithin the characteristic “fingerprint” canbe caused by the star’s wobbling from thegravitational pull of an orbiting planet.
“It is such periodic changes in the emit-ted wavelengths that are used to infer thepresence of a planet orbiting the star,” saidSuvrath Mahadevan, an assistant professorof astronomy and astrophysics at PennState. “In our experiments, we typicallytook a series of approximately 10 expo-sures of five minutes in duration while thetelescope was pointed at a particular stel-lar object. Repeating this over a few
nights, we were able to determine that our system could measure changes in thenear-infrared emitted wavelengths with
a resolution of about 50 femtometers.” The scientists note that many factors
play into how precisely they can makesuch measurements. Although observationtime played a significant role, they discov-ered that the biggest limitation was modalnoise present in the beam that illuminatesthe spectrometer.
“Such noise arises in the type of opticalfibers we used to transport the light be-tween the comb, the telescope and thespectrograph,” Diddams said.
Astronomers have discovered more than600 planets using star wobble analysis, but a planet analogous to Earth, with lowmass and orbiting at just the right distancefrom a star – in the so-called “Goldilockszone” – is hard to detect with conventionaltechnology.
“The challenge is that a planet like ourEarth orbiting ‘not too close or not too far’from a star like our sun would make thestar ‘wobble’ with a velocity of only 10centimeters per second,” said Gabe Ycas,a University of Colorado graduate studentwho helped build the comb. “That is aboutthe speed of a fast spider crawling across
19
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TECHNEWS
Photonics Spectra May 2012
NIST researchers and collaborators measured thefrequencies of infrared starlight (three solid bandswith faint tick marks indicating where light is ab-sorbed by the atmosphere) by comparing the miss-ing light to a laser frequency comb reference “ruler”(sets of bright vertical bars indicating precise wave-lengths, which increase from left to right). The threesets of starlight and comb light are shown in falsecolor, from deeper orange (the most light) to or-ange-white (slightly less light) to black (very littlelight). Courtesy of CU Boulder/NIST/Penn State.
512TechNews_Layout 1 4/20/12 11:52 AM Page 19
the floor. This small velocity change would result in a Dopplershift of the wavelength of the starlight of only 0.5 femtometers,which is very small indeed and difficult to detect – particularly if you consider that such measurements are made across enor-mous distances and with faint stellar sources.”
Combing the galaxy for exoplanetsThe NIST comb, which spans wavelengths from 1450 to 1700
nm, provides strong signals at narrowly defined target frequenciesand is traceable to international measurement standards. Whencombined with Penn State’s Pathfinder spectrograph, the fre-quency comb acts as a precise ruler to calibrate and track theexact colors in the star’s fingerprint and to detect any periodicvariations.
The comb calibrated the spectrograph at the Hobby-Eberly Telescope in the Texas mountains, where it measured star wobblewith a precision of about 10 m/s. This accuracy is comparable tothe best achieved in the infrared region of the electromagneticspectrum.
“Observation time was limited in our first field test becauseours was a very new and high-risk experiment that had to fit intothe schedule of a significant research telescope,” Diddams said.“The biggest technical difficulties arose in part from the fact thatsuch an experiment had never been done before.”
However, the scientists say that the device has the inherent capability of measuring star wobble of just a few centimeters persecond – 100 times better – although limitations in the spectro-graph and in the stability of the star itself may constrain the ulti-mate precision.
Next, the NIST and University of Colorado team plans to create a comb with 30-GHz mode spacing that covers the 1000-to 1200-nm spectral range.
“Our partners at Penn State have been funded by the NSF [National Science Foundation] to turn their Pathfinder spectro-graph into a facility instrument which will be called the HabitableZone Planet Finder (HPF),” Diddams said.
“Demonstrating that the laser comb enabled precision radialvelocity measurements on the prototype Pathfinder is an impor-tant component of the successful HPF proposal,” added Mahade-van, who is the HPF’s principal investigator. “We are continuingto work together in the development and building stages, and we hope to return to the Hobby-Eberly telescope in two to threeyears to join the comb with the HPF, which would then begin adedicated campaign of exoplanet searches.”
The study was published in the open-access journal Optics Express (http://dx.doi.org/10.1364/OE.20.006631).
t TECHNEWS
Photonics Spectra May 2012
Tsunami mapped with laser scannersSENDAI, Japan – Using eyewitness video and terrestrial lasers tomap the epic March 2011 Tohoku tsunami could produce flood-ing forecasts that influence future evacuation plans and buildingdesigns and could help prevent disasters of similar magnitudefrom taking such a huge toll.
Researchers from Georgia Institute of Technology used theequipment from atop the tallest buildings that survived the disas-ter to map the tsunami’s height and flood zone and to better un-derstand the flow of its currents.
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“The ultimate goal is to save lives,”said associate professor Hermann Fritz.“In order to do so, we have to have a bet-ter understanding of what worked and didn’t work.”
The tsunami was Japan’s deadliest inmore than 100 years. Although the countrytook extraordinary measures to prepare forit, the disaster caused more than 90 per-cent of the almost 20,000 fatalities that occurred last March.
The researchers surveyed the impact of the tsunami on a fishing town in Kesen-numa Bay, where 1500 people died. Thebay had been hit by historic tsunamis in1896, 1933, 1960 and 2010, making it themost vulnerable spot in Japan. Its coastalstructures and other mitigation measureswere designed based on conservative, historic high-water marks rather than onprobable maximum tsunamis.
Fritz’s reconnaissance team used lasersto scan the port and bay entrance, creatinga 3-D topographic model of the floodzone. The group determined that thetsunami reached a maximum height of 9 m, followed by outflow currents of 11 m/s less than 10 minutes later, a speed impossible to survive or navigate by ves-sels, Fritz said.
“What we can learn from the hydro-graph is confirmation that the water goesout first, drawing down to more than neg-ative three meters on the landward side of the trench, which can make vessels hitground inside harbors,” Fritz said. “Duringthe subsequent arrival of the main tsunamiwave, the water rushing back in changedthe water level by 40 feet, engulfing theentire city in 12 minutes.”
Understanding the impact of tsunamiswill help prepare for future disasters –whether it is designing seawalls andbreakwaters strong enough to control the flow of water or erecting buildingshigh enough to serve as vertical evacua-tion points.
Besides these mitigation measures, Fritzemphasizes tsunami education.
“People need to be tsunami-aware,” he said.
Fritz worked with teams of researchersfrom the University of Southern Californiaand the University of Tokyo, the TokyoUniversity of Marine Science and Tech-nology, and the Port and Airport ResearchInstitute, in coordination with the UN-ESCO-organized International TsunamiSurvey Team and Tohoku University inSendai.
21
tTECHNEWS
Photonics Spectra May 2012
Professor Hermann Fritz used terrestrial laser scanners to map the height of the March 2011 Tohoku tsunamiand learn more about the flow of its destructive currents. His team determined that the tsunami reached a maximum height of 9 m, followed by outflow currents of 11 m/s less than 10 minutes later, a speed that Fritz said is impossible to survive or navigate by vessel. Courtesy of Georgia Tech.
For more information on the effect of the tsunami and earthquake on the photonics industry, see “Optics industry on steady ground after quake,” on p. 38 of the March2012 issue of Photonics Spectra.
512TechNews_Layout 1 4/20/12 11:52 AM Page 21
COLUMBUS, Ohio – The first real-timeimage of two atoms vibrating in a mole-cule was recorded with a new ultrafastcamera.
A team from Kansas and The Ohio stateuniversities used ultrafast laser pulses to
knock one electron out of its natural orbitin a molecule, and the electron then fellback toward the molecule scattered off it.The use of the energy of a molecule’s ownelectron acted as a “flashbulb” to illumi-nate the molecular motion.
The feat marks the first step toward observing chemical reactions and control-ling them on an atomic scale, said princi-pal investigator Louis DiMauro, a physicsprofessor at Ohio State.
“Through these experiments, we real-ized that we can control the quantum tra-jectory of the electron when it comes back
to the molecule by adjusting the laser thatlaunches it,” he said. “The next step willbe to see if we can steer the electron injust the right way to actually control achemical reaction.”
Standard imaging methods for a still object involve shooting it with an electronbeam, which bombards the object withmillions of electrons per second. The newsingle-electron quantum approach, how-ever, enabled the researchers to take im-ages of rapid molecular motion based ontheoretical developments by scientists atKansas State.
The scientists used laser-induced elec-tron diffraction (LIED) – a technique com-monly used in surface science to studysolid materials – to study the movement of atoms in a single molecule of nitrogenand oxygen, two common gases.
In each case, they hit the molecule with50-fs laser light pulses, knocking a singleelectron out of the shell of the moleculeand detecting the scattered signal of theelectron as it recollided with the molecule.
22
t TECHNEWS
Photonics Spectra May 2012
Camera captures atoms moving in a molecule
Laser-induced electron diffraction (LIED) provides anew method for imaging gas-phase molecular imag-ing with picometer spatial resolution and femtosec-ond timing. In panel 1, the LIED approach is en-abled by strong-field molecular tunnel ionizationthat occurs in a low-frequency laser field (greenline). In panel 2, the ionized electron is driven backby the laser field and diffracts from the molecularstructure. In panel 3, measurement of the electron’smomentum distribution conveys the structural infor-mation at the diffraction time. Courtesy of CosminBlaga, The Ohio State University.
512TechNews_Layout 1 4/20/12 11:52 AM Page 22
DiMauro and Ohio State postdoctoralresearcher Cosmin Blaga likened the scat-tered electron signal to the diffraction pattern that light forms when it passesthrough slits. Given only the diffractionpattern, scientists can reconstruct the sizeand shape of the slits. In this case, giventhe diffraction pattern of the electron, thephysicists reconstructed the size and shapeof the molecule – i.e., the locations of theconstituent atoms’ nuclei.
The key element of the experiment wasthat, during the brief time between whenthe electron was knocked out of the mole-cule and when it recollided, the atoms inthe molecules had moved, Blaga said. TheLIED method can capture this movement– “similar to making a movie of the quan-tum world,” he added.
The method also provides a new tool tostudy a matter’s structure and dynamics.Ultimately, the scientists want to under-
stand how chemical reactions occur. “You could use this to study individual
atoms,” DiMauro noted, “but the greaterimpact to science will come when we canstudy reactions between more complexmolecules. Looking at two atoms – that’sa long way from studying a more interest-ing molecule like a protein.”
The experiment was published in theMarch issue of Nature (doi:10.1038/nature10820).
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tTECHNEWS
Photonics Spectra May 2012
Microlens arrays from a test tubePOTSDAM, Germany – Simplecalcium carbonate precipitationat ambient conditions can pro-duce microlens arrays of uni-form size and focal length. Theprocess offers a cheaper alterna-tive to lithographic techniquesused to create inorganic-basedmaterials.
Scientists at Max Planck Institute of Colloids and Inter-faces collaborated with re-
searchers from the Universityof Konstanz, the Korea Instituteof Geoscience and Mineral Re-sources, and KAIST (formerlythe Korea Advanced Institute of Science and Technology),both in South Korea, to developthe optically functional micro-meter-size hemisphericalCaCO3 structures. To create the microarrays by simple min-eral precipitation, they used a
saturated calcium solution andCO2 in air, along with an or-ganic surfactant that regulatesmineral formation.
Biominerals, such as sea-shells and bones, grow in aque-ous media at ambient condi-tions in a genetically program-med way. The researchers dis-covered that, under atmosphericconditions, micrometer-sizeCaCO3 structures form in
a few minutes at the surface of a calcium-saturated solution. In less than two hours, the precipitate forms a thin film.The addition of organic surfac-tants allowed hemisphericallyshaped uniform structures to be synthesized.
“This is such a simple andcheap process for the fabrica-tion of high-quality microlensarrays, and you just need [a]
512TechNews_Layout 1 4/20/12 11:53 AM Page 23
calcium-saturated solution witha small amount of the organicsurfactant, while alternativelithographic techniques requiremultiple steps and a clean-room,” said Kyubock Lee, a researcher who worked on theproject at Max Planck and atKAIST.
Multiple images of a micron-size “A” were observed throughthe array of microlenses. Thecollimated light can be focusedinto a 1-μm spot by passingthrough 6-μm CaCO3 micro-
lenses with a focal length rang-ing from 7 to 8 μm.
“It was very surprising whenwe observed that hemisphericalCaCO3 structures work as mi-cron-size convex lenses withsuch a high quality,” said Wolf-gang Wagermaier, a researcherat Max Planck. “These opticalproperties have not been dem-onstrated before with syntheticCaCO3 structures.”
The biocompatible CaCO3 isa base material for the skeletonsof a large number of biological
organisms. The biocompatibil-ity of the CaCO3 microlens arrays was demonstrated byseeding fibroblasts, the com-mon connective cell tissue inanimals, proving the viability of the cell array.
They also observed that asingle cell can cover multiplemicrolenses, signifying thatCaCO3 microlens arrays com-bined with optics have potentialfor cell biology research.
“Usually, it is very challeng-ing to fully understand and
mimic the biologically con-trolled formation of such ad-vanced mineral structures, although it is an eventual goalof biomimetic materials re-search,” said Peter Fratzl, headof the biomaterials departmentat Max Planck Institute. “Thefabrication of CaCO3 microlensarrays demonstrates that theprinciples of self-assembly andorganic controlled formation of mineral could be realized to produce advanced optical devices.”
24
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TECHNEWS
Photonics Spectra May 2012
Lab lightning strikes same place more than twicePALAISEAU, France – With the help of a laser-based lightning rod, laboratory-generated lightning was coaxed to strikethe same place not just twice but numer-ous times, and contrary to the path of least resistance. This advance demonstrates the potential of such rods for research and protection.
In earlier experiments, femtosecondlasers were used to produce a virtual light-ning rod from ultrashort filaments of ion-ized gas that act as electrical guide wires.Now, for the first time, researchers inFrance have used laser-induced atmos-pheric filaments to reroute an electricaldischarge from striking the “highest tree,”
instead striking a lower object – over and over again.
A team from Laboratoire d’Optique Appliquée, EADS France, CILAS and Astrium conducted experiments to testhow well lasers can harness and controllightning. They sent a laser beam past aspherical electrode toward an oppositely
512TechNews_Layout 1 4/20/12 11:53 AM Page 24
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charged planar electrode. The laserstripped away the outer electrons from the atoms along its path, creating a plasmafilament that channeled an electrical dis-charge from the planar electrode to thespherical one.
A longer, pointed electrode was addedto determine whether the filament couldredirect an electrical discharge from itsnormal path.
They found that they could divert theelectrical discharge even after it was al-ready on its way, meaning that they couldchange the path of the lightning.
“The laser lightning rod would be avaluable alternative to lightning rockets,”devices that control lightning strikes, saidDr. Aurélien Houard of the Laboratoired’Optique Appliquée.
The research was published online inthe American Institute of Physics’ journalAIP Advances.
t TECHNEWS
Integrated picture of the discharge and measure-ments of the voltage and current in the case of anunguided discharge (a, b) and a laser-guided dis-charge (c, d). Courtesy of AIP Advances, AmericanInstitute of Physics.
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Photonics Spectra May 2012
Ashley N. [email protected]
Attosecond laser takes aim at “holy grail” of chemistry researchLONDON – Ultrafast pulses of laser lightfired at oxygen, nitrogen and carbonmonoxide molecules could pave the waytoward imaging the movement of atomsand their electrons as they undergo chemi-cal reactions – one of the holy grails ofchemistry research.
A team from Max Born Institute inBerlin, FOM-Institute AMOLF in Amster-dam and Texas A&M University in Col-lege Station fired pulses that span only afew hundred attoseconds at a sample ofmolecules to map the quick movements of atoms within the molecules as well asthe charges that surround them.
Previous research probed at the struc-ture of molecules using a variety of tech-niques; however, the inherent challenge isto perform these experiments in systemswhere changes are rapidly occurring onvery small timescales.
In the new work, short laser pulses werefired at the target molecule in an attemptto dislodge an electron. This photoioniza-tion process images atoms and moleculesin unprecedented detail.
The researchers wanted to monitor inreal time the electrical and molecularchanges that occurred as an atom under-went a chemical reaction. They intendedto do this by triggering a reaction with the laser, breaking the chemical bond that
held the molecules together and using the photoionization method to image thechanges that occurred in the molecule asthey happened.
“We show that the photoelectron spectrarecorded for a small molecule, such asoxygen, nitrogen and carbon monoxide,contain a wealth of information aboutelectron orbitals and the underlying mo-lecular structure,” said Dr. Arnaud Rouzéeof Max Born Institute, lead author of thestudy. “This is a proof-of-principle experi-ment that electrons ejected within the molecule can be used to monitor ultrafastelectronic and atomic motion.”
The study was published in IOP Pub-lishing’s Journal of Physics B: Atomic,Molecular and Optical Physics.
Photoelectron angular distributions for the ionizationof aligned and anti-aligned molecules using an attosecond pulse train. CO2 � carbon dioxide.Courtesy of Arnaud Rouzée, Max Born Institute.
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Impact of PV panel penalties ponderedWASHINGTON – In March, the US Department of Commerce imposed dutieson imports of crystalline silicon photo-voltaic (PV) cells from China after findingthat companies there received illegal gov-ernment subsidies. But the long-term effect of the move, on both the US-basedsolar market and on China, remains to be seen.
The tariffs, ranging from 2.9 to 4.73percent, were smaller than expected bythose on both sides of the issue. The find-ing is a preliminary determination; a finalruling is expected to be announced inJune.
The “surprisingly low” numbers wouldlikely mean that the major Chinese com-panies would have to pay between about$5 million and $10 million to cover prod-ucts shipped, a relatively minimal impact,Citigroup analyst Timothy Arcuri toldReuters news agency.
Still, the fact that tariffs were imposedat all “affirms what US manufacturershave long known: Chinese manufacturershave received unfair and [World Trade Organization]-illegal subsidies,” saidSteve Ostrenga, CEO of Milwaukee-basedHelios Solar Works, in a statement on thewebsite of the Coalition for AmericanSolar Manufacturing (CASM). The seven-manufacturer CASM represents about15,000 workers at more than 150 US companies.
The initial duties do not “cover the fullextent of the harm” caused by China’ssubsidies, said Gordon Brinser, presidentof SolarWorld AG’s US unit, in an inter-view with Bloomberg News in March. He expects the final tariffs to be higher.SolarWorld, a member of CASM, is peti-tioner in the government’s anti-subsidyand anti-dumping cases. Based in Ger-many, it also has production facilities inHillsboro, Ore.
Suntech Power Holdings Co. Ltd. ofWuxi, China, the world’s largest manufac-turer of solar panels, received countervail-ing, or anti-subsidy, duties of 2.9 percentfrom the Commerce Department on itscrystalline silicon PV cells.
“This initial decision reflects the realitythat Suntech’s global success is based on
free and fair competition,” said AndrewBeebe, Suntech’s chief commercial officer, in a statement. He added that “unilateraltrade barriers” such as these will “furtherdelay our transition away from fossil fuelsat a time when the majority of Americansdemand cleaner and more secure energysuch as solar.”
Besides China, Suntech has manufactur-ing sites in Japan and the US. “Regardless[of] whether tariffs are imposed on solarcells from China, we can provide our cus-tomers in the US with hundreds of mega-watts of … solar products that are not sub-ject to tariffs,” Beebe said.
“We are not dumping, nor do we be-lieve that we are unfairly subsidized,” said Robert Petrina, managing director ofYingli Green Energy Americas Inc., theUS subsidiary of Yingli Green EnergyHolding Co. Ltd. of Baoding, China. “Wewill continue to fight for affordable solarenergy and further growth of the tens ofthousands of US solar jobs that we help to create. Regardless of the outcome ofthis proceeding, we remain dedicated tothe US solar market.”
The Commerce Department’s decision“is a relatively positive outcome for theUS solar industry and its 100,000 employ-ees,” said Jigar Shah, president of theCoalition for Affordable Solar Energy
(CASE), in an official statement. “This decision clearly demonstrates that theCommerce Department did not find theChinese government engaged in massivesubsidization, as SolarWorld and CASMclaim.”
CASE objects to any solar tariffs, Shahsaid, because they will hurt American jobsand prolong dependence on fossil fuels.He cited a recent study by the BrattleGroup, an international economic consult-ing firm, which determined that placing“artificially high” tariffs on solar panelswill result in the loss of up to 60,000 USjobs by 2014. “Fortunately, this decisionwill not significantly raise solar prices inthe United States,” he added.
“The major trade issues between Chinaand the US affect every export-orientedindustry, not just solar panels,” wrote TomGutierrez, CEO of industry productionequipment provider GT Advanced Tech-nologies, in an editorial on the CASEwebsite. “This issue should be addressedby bilateral negotiations between the twocountries. The answer is not imposing aspecial tariff – really a tax – on solar panels. That ‘tax’ would be built into thecosts of solar energy systems, makingsolar power much more expensive forelectric utilities and commercial and resi-dential consumers.”
30 Photonics Spectra May 2012
TRACKFAST
Gordon Brinser, US president of SolarWorld, speaks at the solar trade action press conference in October2011 about the case against China as US Sen. Jeff Merkley, D-Ore., looks on. Courtesy of SolarWorld USA.
512FastTrack_Layout 1 4/20/12 1:47 PM Page 30
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“If fair international trade can be re-established, the solar-pioneering US indus-try will once again compete on legitimatemarket factors such as product perform-ance, production efficiency and unsubsi-dized pricing,” Brinser said. “We needboth the domestic manufacturing and in-stallation businesses to participate in fair
competition to advance our solar indus-try’s reach for greater national energy,economic and environmental security.”
In 2010, the US Department of Energyestimated that the Chinese governmentprovided its manufacturers with more than$30 billion in subsidies. CASM contendsthat China’s subsidies spurred its produc-
ers to build huge excesses of manufactur-ing capacity, to export more than 95 per-cent of production and to sell products atartificially low prices to unfairly seize US market share at the expense of domes-tic producers. At least 12 US manufactur-ers of crystalline silicon solar cells andpanels have closed plants, gone bankruptor staged significant layoffs since 2010,the coalition says.
One such company is Solyndra, a Fremont, Calif., manufacturer of rooftop solar panels that filed for bankruptcy inSeptember. Although not a significant industry player, the company drew muchmedia attention and government investi-gation after receiving more than $500 million in federally guaranteed loans.
In early March, CASM released a reportthat found that the US swung from a smallsurplus in solar product trade with Chinain 2010 to a $1.6 billion trade deficit in2011. This swing unfolded, the coalitionsaid, despite the fact that a National Re-newable Energy Laboratory presentationconcluded that Chinese manufacturers actually face a 5 percent cost disadvantage
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SolarWorld solar cells manufactured at the US headquarters in Hillsboro, Ore. Courtesy of SolarWorld USA.
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in producing and delivering solar into theAmerican market compared with US man-ufacturers. The Chinese producers built 16 times more manufacturing capacitythan it needed to satisfy domestic demand,then exported more than 95 percent ofproduction, CASM said.
In 2011, China exported 93.2 millionproducts to the US, with a combined valueof $3.1 billion, the Commerce Departmentsaid, while in 2009, it exported 26.8 mil-lion products, valued at $639.5 million.
For the US solar industry, 2011 was anhistoric year, according to a report by theSolar Energy Industries Association andGTM Research Solar Analysts. Installa-tions were up 109 percent over 2010, andthe fourth quarter saw by far the mostmegawatts of solar power installed in anyquarter in US market history.
But 2011 also saw solar panel prices go into free fall, plunging more than 50percent during the year.
In an action related to the levying of duties, the Commerce Department and theInternational Trade Commission are con-ducting an anti-dumping investigation on
solar cells from China, with the Com-merce Department scheduled to announceits preliminary determination on May 17,at which time additional tariffs could beimposed. In June, if the Commerce De-partment finds that China is “dumping”solar panels in the US for less than theiractual cost, the ITC will begin to make itsinjury determination. No final tariff deci-sions will be made until the ITC investiga-tion is completed.
“The important thing to remember isthat tariffs are bad for the entire solar in-dustry,” said Liansheng Miao, chairmanand CEO of Yingli Green Energy Holding.“We will continue to support the US as an important solar market, and believe that global trade and fair competition willpersevere. [Commerce’s] decision vali-dates that.”
B&W Tek Marks 15 Years Optical spectro-s copy and laser systems provider B&W Tek Inc. ofNewark, Del., is celebrating its 15th anniversaryin the photonics industry. Established as a greenlaser manufacturer in January 1997, the com-pany has grown into a total solutions provider forspectroscopy applications. B&W Tek’s key compo-nents are designed and manufactured in-house,allowing OEM customers to use an assortment ofits ready-to-use, off-the-shelf modular productsto create their own solutions.
Jenoptik Wins Order in Asia In Jena, Ger-many, the Optical Systems Div. of Jenoptik hasreceived a multimillion-euro order for flat paneldisplay equipment from an unnamed Asian customer. The products have been developedand will be integrated into a new productionsystem. The display order, which will be deliv-ered this year, further strengthens the division’smarket position developing customized opticaland micro-optic systems in the semiconductorand flat panel display segments.
OSA Forms Section in Egypt The Optical Soci-ety (OSA), based in Washington, has estab-lished the Alhazen Egyptian OSA Local Section,the society’s first in the Middle East. The Cairo-based group has been approved by the OSAMember and Education Services Council. Profes-sor Mohamed Abdel Harith of the National
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Photonics Spectra May 2012
FASTTRACK
Melinda A. [email protected]
BUSINESSBRIEFS
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Institute of Laser Enhanced Science at CairoUniversity will serve as president of this section,which is a self-governing organization. Thename comes from the 11th-century scientist Alhazen, who was born in Mesopotamia (cur-rent-day Iraq) and lived in Egypt. The sectionwill support the growing optics and photonicsindustry in Egypt and throughout the region.
Arden Photonics Names Distributor Opticalfiber company Arden Photonics Ltd. of Solihull,UK, has appointed OgMentum Inc. of State
Line, Nev., as its sales and marketing partnerfor China and the western US. OgMentum willprovide Arden with sales channel managementand support services in the telecommunications,fiber optics, and test and measurement fields.
EMagin Granted Microdisplay ContractEMagin Corp. of Bellevue, Wash., has receiveda $1.12 million Small Business Innovation Research (SBIR) contract from the US SpecialOperations Command to optimize its WUXGAorganic LED microdisplay for mass production.
The project includes a $435,000 option. Underthe contract, eMagin plans to make the 1920 �1200-pixel OLED microdisplay more affordablefor military and commercial applications. Themicrodisplay is currently available as an engi-neering sample to commercial OEM customersand military contracts.
Advanced Photonix Secures Reseller Opto-electronics company Advanced Photonix Inc. of Ann Arbor, Mich., has signed Thermo Fisher Scientific of Waltham, Mass., as its first value-added reseller for its T-Gauge industrial tera-hertz gauging system. The system offers on- and offline measurement for quality assuranceand process control of web-based and convert-ing industries. The technology is adaptable tovarious sensor configurations. The agreementwill enable T-Gauge industrial process controlsolutions for continuous web, discrete manufac-turing and anomaly defect inspection applica-tions.
Renishaw Launches Subsidiary The globalmetrology and spectroscopy company Renishawhas opened a subsidiary in San Pedro GarzaGarcia, Mexico, to support its expanding cus-tomer base in Mexico and Central America. Alejandro Silva C., the founder and formerowner of Metric Precision Group of Mexico, a distributor of Renishaw’s metrology products,will serve as director and general manager of the new operation. “We see significant potential for our business in Mexico, where sectors such as automotive and electronics are showing good growth,” said Ben Taylor,Renishaw’s assistant chief executive. The sub-sidiary will focus on supporting technologies for motion control, measuring systems and machine tools.
TU Berlin Licenses Patent The Technical University of Berlin and its partner ipal GmbH in Berlin have closed a €500,000 (about$652,000) deal with a key global semiconduc-tor company for use of the university’s energyconversion patent allowing a significant in-crease in the energy conversion efficiency ofphotonic components. Ipal, the exclusive partnerfor technology transfer and patent licensing andsale for Berlin’s universities and technical col-leges, negotiated the deal. “Revenue of thismagnitude for technologies from universities issignificant and is not the general rule,” said Dr.Kirk Haselton, licensing manager at ipal andlead negotiator for ipal and TU Berlin.
Thorlabs Acquires Laser Line, Expands InNewton, N.J., Thorlabs Inc. has acquired theOctavius line of ultrafast lasers and ultrafastpulse characterization products from idestaQuantum Electronics (IQE). The transaction isexpected to strengthen Thorlabs’ portfolio withlasers and diagnostic tools for the imaging andphotonics industries, and to allow IQE to focuson other technology. The Octavius devices aresuitable for photonics and biological applica-tions. IQE’s two-dimensional scanning interfer-ometer, developed in collaboration with MIT,also is being transferred to Thorlabs.
In other news, Thorlabs has completed itsnew three-story, 120,000-sq-ft facility in New-ton, which will act as the central hub for the
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company’s sales, service, R&D and manufactur-ing operations. Subsequent construction phasesare planned for the next seven to 10 years andwill ultimately expand the company’s space toapproximately 300,000 sq ft. The privately heldcompany has experienced double-digit growthsince its founding in 1989.
Excelitas Expands in Medical LightingExcelitas Technologies of Waltham, Mass., hasaugmented its lighting portfolio through the acquisition of privately held Carsan Engineering
of Golden, Colo., a manufacturer of arc lamppower supplies for the medical and dental mar-kets. The transaction increases the array ofpower supplies in Excelitas’ portfolio of lightingsolutions for medical and dental OEMs. Car-san’s newest 400-W product is highly differenti-ated and is gaining interest in the medical anddental markets, the company said.
North American MV Market Grew in 2011Machine vision components and systems salesin North America increased 5 percent in 2011
to nearly $1.9 billion, according to the globaltrade group AIA of Ann Arbor, Mich. Machinevision components grew 13 percent, while ap-plication-specific systems grew 2 percent, saidPaul Kellett, AIA’s director of market analysis.He also said that the first half of 2011 wasmuch stronger than the second half, whenoverall economic growth began to slow. “As vision becomes more critical to a growing number of industries, we expect to see contin-ued growth in both manufacturing and non-manufacturing sectors,” said AIA President JeffBurnstein.
Boston Scientific, Lumenis Renew DealMedical device maker Boston Scientific Corp. of Natick, Mass., and Lumenis Ltd. of Yokneam,Israel, have signed a five-year contract to ex-tend their existing commercial agreement andto promote continued investments in laser andfiber product development for urologic applica-tions. Under the agreement, Boston Scientificwill continue as the exclusive US distributor forthe Israeli company’s holmium laser fibers, de-signed for use with surgical lasers to treat vari-ous urologic conditions. Medical laser companyLumenis manufactures and distributes laser-and light-based devices for surgical, ophthalmicand aesthetic applications.
OLED Inventor Joins QD Vision BoardOrganic LED (OLED) inventor and Wolf Prizewinner in chemistry Ching Tang has joinedquantum-dot product supplier QD Vision Inc.’sscientific advisory board. Tang, the Doris JohnsCherry Professor at the University of Rochester,is credited with several innovations that led tothe commercialization of OLED flat panel dis-play technology, said Dr. Seth Coe-Sullivan,founder and chief technology officer of QD Vision. Based in Lexington, Mass., the companyexpects that Tang and his expertise will have astrong impact on its quantum-dot devices in thelighting and display markets.
Kodak Selling Online Photo Service East-man Kodak Co. of Rochester, N.Y., has enteredinto an agreement with Shutterfly, an Internet-based social expression and personal publish-ing service, for the proposed sale of certain as-sets of its Kodak Gallery online photo servicesbusiness for $23.8 million. Kodak will transferits US and Canada Gallery customer accountsand images to Shutterfly. The agreement com-prises the initial, stalking horse bid in a court-supervised auction process under Section 363of the US Bankruptcy Code, which will ensurethe maximization of value for the assets. Kodakplans to complete the sale process by thisspring. It filed for Chapter 11 in mid-January.
DOC Acquiring Camera Module Assets In a bid to grab a bigger piece of the $9 billionmarket for mobile phone cameras, TesseraTechnologies’ DigitalOptics Corp. (DOC) of SanJose, Calif., will acquire the China-based cam-era module manufacturing brand and assets ofFlextronics International Ltd. of Singapore for$23 million in cash. The deal will allow DOC to significantly increase its imaging technologysales by making about 50 million camera mod-ules a year, with the goal of becoming prof-itable by 2013.
f
Photonics Spectra May 2012
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GreenLightFull spectrum boosts solar cell power
Solar cell efficiency can be boosted to as high as 70 percent by printingspecially engineered nanostructures
on the cells.Conversion efficiency of solar cells has
long been thought limited to 34 percentfor a single material or less than about 45 percent for the most efficient cells. Athermodynamic limit is responsible forthis practical impediment.
The conversion process of solar cells is typically not very efficient: A conven-tional silicon solar cell commerciallyavailable today converts only 15 to 20 percent of the energy of the sunlight toelectricity, with the balance lost as heat.
Blue and green lightwaves are con-verted to electricity with an efficiency of less than 50 percent, while infraredlight is not absorbed by a silicon solar cell at all. The highest efficiency recordrealized by a silicon solar cell was 27 percent.
Light that is not converted in the solarcell leads to thermodynamic disorderknown as entropy and, as a result, to re-duced cell voltage. As a result, the maxi-mum achievable efficiency is limited to 34 percent, also known as the Shockley-Queisser limit.
The incomplete trapping of light insidethe solar cell and defects in the solar cellmaterial’s crystal structure also cause effi-ciency loss.
But Harry Atwater, an applied physicistat California Institute of Technology inPasadena, and his colleague Albert Pol-man of the FOM Institute for Atomic andMolecular Physics in Amsterdam haveachieved efficiency as high as 70 percent.By managing the light with specially engi-neered nanostructures printed on the sur-face of the solar cells, it can be bettertrapped, and many of the efficiency prob-lems can be solved.
In their Nature Materials paper, Atwaterand Polman describe several recipes forachieving these improvements. The inspi-ration for some of these ideas, which arebased on the integration of photonic nano -structures and circuits on the solar cell,comes from optical integrated circuit tech-
nology, where structures to guide and con-trol light are routinely made.
“Before 2000, scientists and technolo-gists had developed materials and deviceswith high electronic quality, but little at-tention was paid to optical design,” Atwa-ter said. “But in the last decade, revolu-tions in photonic material design andlarge-area nanostructure fabrication havegiven researchers and technologists toolsto enable a new era of ultrahigh-efficiencyphotovoltaics.”
He noted that the solar cell communityhistorically has assumed that cells couldbe made either with low efficiency at alow cost or with high efficiency at a highcost. Now, however, high-efficiency, low-cost solar cells are achievable.
“The solar cell community has drivendown solar panel cost, yet is very conser-vative and has not boosted efficiency sig-nificantly,” Polman said. “But solar panelswith a high efficiency take up much lessspace because you need fewer panels togenerate the same amount of power. Thatsaves costs of land, installation and infra-structure.
“With a slightly more complex solarcell, it becomes possible to convert all colors of the light from the sun to electric-ity, and an efficiency of up to 70 percent is achievable.” l
39
“… in the last decade, revolutions in photonicmaterial design andlarge-area nanostructurefabrication have given researchers and technologists tools to enable a new era of ultrahigh-efficiencyphotovoltaics.”– Harry Atwater,
California Institute of Technology
Photonics Spectra May 2012
512GreenLight_Layout 1 4/20/12 1:56 PM Page 39
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41Photonics Spectra May 2012
How to Develop a Laser Safety CultureBY ANTONIO TRIVENTI, CHP, CLSO NATIONAL INSTITUTE FOR LASER SAFETY OFFICERS AND HEALTH PHYSICISTS
The art of inspiring and coordinatingpeople’s activities beyond the en-forcement dictated by rules and regu-
lations translates into a cultural asset thatleads to tangible performance excellence.A laser safety program, with all its partici-pating parties, is the perfect ground for organizational team play, and the lasersafety officer (LSO) becomes a leaderwho can motivate, involve and integratepersonnel to achieve common and sharedgoals within the organization.
Laser safety leaders are facilitators andorchestrators. They communicate purposesand have their teams internalize what theywant the members to do. They must be explicit about their intentions, plans andexpectations, and they must ask questionsto probe whether the teams understandwhat they are saying.
In this scenario, trust is an essentialcomponent. Trust means not being afraideven if we feel vulnerable and weak. Thelaser safety leader must take responsibilityfor errors and not blame team members.Trusting acts create the potential for mu-tual benefit. If you are appointed LSO for a large and complex research facilityor medical institution, don’t worry aboutlooking vulnerable or weak if you don’timmediately have all the solutions and answers. Be willing to learn and createknowledge; be passionate and show commitment.
How? Ask questions – ask a lot of questions. Think of yourself as a student
of daily life, extracting useful informationand lessons from situations around you.And you must never give up, ever! Youmust be inspired to inspire others, andyour passion will be the major source of inspiration for others.
Obviously, laser safety leaders musthave a suitable set of skills in their arsenals; to put it simply, they must becompetent. But rank, position and author-ity don’t contribute to effective lasersafety leadership. If you are appointedlaser safety officer, pursue “leadership bycommitment” instead of “leadership bycompliance.” Don’t be diverted by theword “officer” in your professional title;you are not the “photon cop”!
Leadership by compliance is exertingformal power and being the boss. Strictlyusing codes and regulations to force othersto do what you want is easy to set up, butit is energy-depleting for everyone in-volved. This approach gives you only
what you have asked for and makes personnel comply with the letter of the policy but not with its spirit. That kind of laser safety leadership houses subtle sabotage; worse, it is inefficient because you have to always be present to ensure compliance.
Leadership by commitment, however,means that your team members internalizewhat you want them to do and, ultimately,they will follow your game plan becausethey want to stay safe. This way, your in-fluence is kept alive even when you arenot around, and you can get the outcomesyou want even if you are not physically onsite. To quote President Dwight D. Eisen-hower: “Leadership is the art of gettingsomeone else to do something you wantdone because he wants to do it.”
This leadership style is energy-expand-ing and enhances your professionalachievements: It allows you to creativelystrive to reach shared purposes and workin the best interests of the organization. It also facilitates the establishment ofsound laser safety.
So personnel involvement is crucial.Workers involved feel that the laser safetyprogram is their own and not imposed onthem by you. They see your requirementsand recommendations as long-term en-hancement of their workplace. But be sure to set realistic expectations withoutoverselling values and ideals, and keep the laser safety program open to revisionand reconsideration if events indicate thatmodifications are needed.
Give before you are asked. In otherwords, create and develop interactive sys-tems. For example, face-to-face communi-cation and regular laser safety audits andmeetings foster open dialogue and trustbeyond conventional, rigid reporting tools
LASERS IN USESAFETY PERSPECTIVES
What is the most important measure of a laser safety program’s success? Developing a true culture of laser safety is the ultimate goal of any serious laser safety officer.
How to ensure lasersafety success• Inspire trust.
• Ask questions.
• Pursue leadership by commitment.
• Develop interactive systems.
• Push people – but care aboutthem.
The seventh annual US Department of Energy LaserSafety Officer Workshop, held at MIT in August2011. Images courtesy of Antonio Triventi.
Laser Safety_Layout 1 4/20/12 1:51 PM Page 41
or checklists. As I said earlier, organiza-tional attention and learning rely on the direct involvement of participants: Thepersonnel involved gain commitment for cultural change and its effective im-plementation.
Another aspect of interactive systems is the ability of the laser safety leader toidentify whose support will be required for the systems to succeed and to create or develop political coalitions and cohe-sion among different layers of the organi-zation. Useful and productive support cancome from subordinates, peers, supervi-sors, line managers, safety designates, operators, scientists, engineers, executivesand top management. If your team mem-bers have an idea, then they want it to beheard – they want to have a voice.
Imagine that everyone would like tohave input in your program. Create an atmosphere of psychological safety by listening, and your team will feel safe tocontribute. This approach enhances theperformance of your team members andmakes it more effective in the execution of your game plan. Give them responsibil-ity, and delegate things to them. Consideryourself the director of the laser safetyprogram who is helped by numerous lasersafety project managers; personnel willfeel like they are “in charge.”
The key here is to identify who is re-sponsible for what as you work on ad-dressing obstacles and issues. Then, set atimetable and deadlines for tasks’ comple-
tion. But remember,interactive systemsrequire strong com-mitment.
To develop asafety culture, welaser safety officersmust treat our safetyprograms as socialactivities. We mustthink about our-selves as coaches ofextraordinary teams. We must think notonly about what we do but also what ourteam members do. We must pay attentionto the tasks and the people because onewithout the other is ineffective.
As laser safety leaders, we must pushpeople to accomplish our tasks, but wemust sincerely care about our people, too.We must be supportive and praise them,but then we must push them to do more.This is “tough love”: People will not ap-preciate us pushing them until they see the end results of our pushing – for in-stance, a clear/clean report from state inspectors or federal auditors. We may encounter resistance, but we must keeppushing and caring.
Albert Einstein is considered to be oneof the most influential leaders of all time.Louis de Broglie, the 1929 Nobel Prizewinner in physics, wrote this about Ein-stein in his 1962 book New Perspectivesin Physics: “I was particularly won overby his sweet disposition, by his general
kindness, by his simplicity, and by hisfriendliness. Occasionally, gaiety wouldgain the upper hand and he would strike a more personal note and even disclosesome detail of his day-to-day life. Thenagain, reverting to his characteristic moodof reflection and meditation, he wouldlaunch into a profound and original dis-cussion of a variety of scientific and otherproblems. I shall always remember the enchantment of all those meetings, fromwhich I carried away an indelible impres-sion of Einstein’s great human qualities.”
Our ultimate goal is to develop people’sskills so that they can perform on theirown and contribute to the success of theprogram. And we will share the successand even form stronger bonds through celebrating victories. As laser safety leaders, we must see a better world anduse our own human qualities to help otherpeople see it, too.
Meet the author Antonio Triventi is a health physicist and LSOat Northwestern University as well as presidentof the National Institute for Laser Safety Offi-cers and Health Physicists (www.nilsohp.org).He is a member of the American Academy ofHealth Physics, the Health Physics Society, theLaser Institute of America and the ANSI Ac-credited Standards Committee Z136. He also isa licensed Italian professional engineer, a certi-fied health physicist (CHP) through the Ameri-can Board of Health Physics, and a certifiedlaser safety officer (CLSO) through the Boardof Laser Safety; email: [email protected].
42
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Hitting Every Anglewith Autostereoscopic 3-D Displays
BY GREGG E. FAVALORAOPTICS FOR HIRE
The broad field of autostereoscopic display – the creation of imagery thatappears three-dimensional without
requiring the use of additional eyewear1,2 –is evolving. Optical engineers continue topush 3-D display technologies to matchdepictions in science fiction movies. It’s2012, after all – can’t one simply buy a“holographic video display” that snapsinto a DVI port and generates a cubicmeter of full-color, occlusion-bearing, utterly natural imagery?
Well, almost. There is much to consider in our jour-
ney, with 38 species of stereoscopic andautostereoscopic displays in 3D@Home’staxonomy, and several possible classifica-tions.3,4 (Reference 3 is a recommendedstarting point for technically oriented new-comers to the topic.)
The 3-D display is just one element of a broad pipeline spanning content genera-tion, or acquisition, to the production of a 3-D image (Figure 1).
What are the aims of current research? This depends on the particular use of
each type of display. A mobile device,such as Sharp’s directional parallax barrierbacklighting in the Nintendo 3DS, permitsa solitary user to view the display at lessthan arm’s length, from one constantviewing angle. Therefore, a two-view autostereoscopic image suffices. Contrastthis with the aims of research in auto -stereoscopic television, which might re-quire hundreds of unique viewpoints tonumerous simultaneous viewers at variousdistances and viewing angles or, alter-nately, some combination of head-trackingand fewer unique views. Finally, considerboardroom and military uses, in which 10people might encircle a horizontal displaythat projects volume-filling imagery abovea tabletop.
Other than mobile, which I consider“solved enough” because of technologies
from Sharp, MasterImage 3D and 3M, the field is experimenting with acceptablesolutions for larger displays. Researchersstill yearn to combine high-definition(HD) resolution, a natural effect of hori-zontal motion parallax for multiple simul-taneous viewers, and the high-fidelity re-production of depth both in and out of thedisplay surface. For example, there aremany vendors of flat panel autostereo-scopic displays for desktop or living roomuse, but these devices usually are ham-
pered by uncomfortably narrow restric-tions on the viewer’s head placementwithin a viewing zone.
Bandwidth requirementsMost autostereo displays generate im-
agery by electro-optically modulating illu-mination; e.g., a display might sequen-tially direct photons modulated by a mi-croelectromechanical system (MEMS) to-ward a series of viewing zones, or use alens array to direct the light from manyLCD pixels to several simultaneous zones.Their image quality is constrained by themodulator’s bandwidth, which is a func-tion of time and space: the product of thenumber of light-modulating elements andthe rate at which they can change state.Three-dimensional displays of comparableimage quality consume more bandwidththan 2-D displays for a variety of reasons.
For example, some autostereo displaysproject a collection of perspective images,or views, in sequence to different angles inrapid sequence. Perceived depth increaseswith various factors, such as tighter angu-lar definition of each of those views,which ends up consuming spatial band-width as the number of views increases.
Increasing the number of views is an-other desirable outcome because it de-creases the distraction of interview alias-ing, or flipping, in which one perceivesthe imagery jarringly change from oneview to the next,5 but this consumes spaceor time bandwidth, too. Or, for a particu-larly elementary example, if the 3-D dis-play uses an LCD panel, its resolution in-fluences the system’s perceived resolution.Bandwidth, therefore, enables or constrictsthe optical engineer’s ability to provideimage fidelity.
Let’s say you’re designing a displaywith numerous views to provide a com-fortably wide viewing zone. Consider a300-view, 1080-p autostereo display, with
Photonics Spectra May 201244
Clever use of electro-optics, lens arrays, diffusers and software advances the multidimensional way of seeing
Content Generation
Content Capture
Compression
Transmission
Decompression
Rendering
Display
Figure 1. The data pipeline from scene capture todisplay. The “display” block may further include thesteps of calibration, local storage, local processing,control systems and 3-D image projection.
512_3DTV_Layout 1 4/23/12 10:15 AM Page 44
eight bits for each of three color channels,running at 60 Hz. This implies that youneed the following light-modulation spacebandwidth product (SBP):
SBP � 300 views � (1920 � 1080)pixels/view � 24 � 60 (s�1) � 895.8 billion pixels/second.
To my knowledge, Texas Instruments’Digital Light Processing (DLP) technol-ogy offers the highest SBP in a rectangulararray. For example, the ALP-4.1 made by ViALUX Messtechnik + Bildverar-beitung GmbH in Chemnitz, Germany,uses the Discovery 4000 chipset, provid-ing 22,727 XGA-resolution fps at singlebit depth, equaling nearly 18 billion pixelsper second.
This is a tremendous improvement overother modulators, but still almost two orders of magnitude less than what is re-quired for some types of displays. Thus,most experimental high-view-count 3-Ddisplays have limited color fidelity, requiremultiple light modulators and provide sig-
nificantly fewer than 300 views, whichsome researchers believe is desirable.
One method for improving image qual-ity in the absence of sufficient SBP is theintentional blurring or band-limiting of el-ements of the displayed 3-D scene with in-creasing distance from the display, a tech-nique developed by Michael W. Halle.6
Similar calculations hold for other dis-play types. The Perspecta volumetric dis-play stacked 198 2-D XGA-resolutionslices of a scene with three-bit color at 30 Hz using a three-DLP light engine.Thus, a 100-million-pixel image was cre-ated at the expense of color fidelity.
Spatially multiplexed displaysSpatially multiplexed displays are those
autostereo 3-D displays most frequentlyencountered by the public. Two examplesare parallax barrier displays and lenticulardisplays. See the left panel of Figure 2,which illustrates an example of the former.Invented in the early 1900s, spatially mul-
tiplexed displays contain at least twoviews (one for each eye) interleaved on a surface, such as in vertical columns orother subpixel groupings. These are madeselectively visible from several viewinglocations or “sweet spots.”
Today, these displays typically offer be-tween two and eight views, sometimesmore, with 24 cited as an approximatepractical upper limit because of the trade-off between view count and perceived res-olution, and the impact of diffraction andlight efficiency.
45Photonics Spectra May 2012
Figure 3. Some lenticular displays align the lensarray on a slant with respect to an underlying interleaved image source. Courtesy of Alioscopy.
Figure 4. Each projector in a system made by theTakaki Laboratories directs 800 images toward arotating horizontal screen. The result is a 360° dis-play with a 300-mm diameter (b). Images courtesy of Yasuhiro Takaki.
Figure 2. Cross-sectional views, looking down. Left: A traditional parallax barrier display places a regular array of transparent columns in front of an image source. In some displays, the role of “rear” and “front” LCDs are swapped. Right: A content-adaptive display computes optimized patterns on both display surfaces to improvethe fidelity of the reconstructed scene. (Not to scale; the viewer is usually significantly farther away.) Courtesy of Matt Hirsch, MIT Media Laboratory.
a
b
512_3DTV_Layout 1 4/23/12 10:16 AM Page 45
You might have seen a lenticular arrayused as a multiple-image panoramagramon DVD cover art or on advertisingposters. In that case, a sheet of narrowlenslets directs an interleaved arrangementof views to a collection of zones in space– the word “panoramagram” implying thatmore than two views are created.3
Users of the Nintendo 3DS see two-view autostereoscopic imagery in a varia-tion of the parallax barrier technique, directing illumination past microscopiccolumns of a rear LCD panel en route toan image-bearing front LCD panel. This isa rearrangement of the left illustration inFigure 2.
One of the many vendors of lenticularpanoramagrams – and related software andservices – is Paris-based Alioscopy. Thecompany sells four lenticular displays,from 61 to 119 cm diagonally, each pro-viding eight views. Firms differentiate thequality of their displays in various ways,such as custom lens design, careful qualitycontrol during manufacturing and registra-tion, and proprietary algorithms.
Alioscopy reports that it fabricateslenses on-premises and applies them at anangle to the vertical axis of the underlyingLCD display panel (Figure 3). This inten-tional slant is used in various lenticulardisplays to reduce moiré effects and toequalize perceived horizontal and verticalresolutions. The firm also is exploringplug-and-play systems, which combinehardware and software for a turnkey ef-fect, such as a simulated 3-D aquariumthat works out of the box.
A third popular category of spatiallymultiplexed displays provides parallax notonly in the left-to-right direction, but alsoin the up-down direction. These integralimage displays use either fly’s-eye lens ar-rays or an array of tiny apertures, throughwhich views can be seen. Integral im-agery, also a 1900s invention, is seeing themost prolific ongoing development in Asiaby companies such as NHK and Toshiba.
Professor Henry Fuchs and colleaguesat the University of North Carolina atChapel Hill have been developing a mod-ern improvement of this technique, calledrandom hole displays. In a recent versionof the technique, a 2560 � 1600-pixel dis-play is oriented horizontally, like a table,and viewed through a Poisson distributionof tiny apertures in a polyester film 6.35mm above the display. In one mode of op-eration, two location-tracked simultaneousviewers each see approximately 2.8 mil-lion pixels that change with viewer mo-tion.7
Time-multiplexed displaysNot all autostereoscopic displays use
purely spatially multiplexed input im-agery. The frame rate of certain light mod-ulators is high enough to enable new dis-play architectures to have time-varyingproperties, such as sequentially scanningthe visibility of a series of 2-D patternsleft and right across the audience, so that a multitude of unique perspectives can bedepicted. These are time-multiplexed dis-plays. The Discovery 4000 referenced ear-lier can depict about 378 binary patternscycled at 60 Hz. An area of open researchregards the mechanisms by which thosepatterns can be scanned.
One method, dual-lenticular scanning,was developed by Actuality Systems,8 andsimilar methods are being pursued by Ze-cotek Photonics Inc. of Richmond, BritishColumbia, Canada, and by the BrusselsPhotonics Team.9 In this method, a DLP-based projector directs a sequence of im-ages toward a “sandwich” of two or morelenticular arrays that repeatedly translateleft and right by a distance a fraction ofthe lenslet pitch; e.g., 125 μm. This formsa macroscopic beam-steering device.
Besting traditional spatially multiplexedlenticular displays, these temporally multi-plexed displays can provide 100 or moreviewpoints, each at XGA resolution. Thisresults in imagery having a comfortablywide horizontal field of view for at leastone user, providing excellent look-aroundand a compelling sensation of depth,though at the expense of color fidelity.
It also is possible to project 3-D im-agery visible 360° around a flat horizontalsurface. These theta-parallax-only (TPO)displays use a swiftly rotating disk-shapedoptical component to repeatedly sweep arapid sequence of viewpoints in a circleabove the system.10 The purpose of thecomponent is to restrict the active viewingangle at any given instant, and the pro-jected image changes in synchronizationso the appropriate image is directed toeach viewing angle.
Absent viewer location compensation,the imagery has distortion when viewedfrom above or below the intended viewingheight, but the results are promising. Theoptical component can take several forms:a disk cut out of an off-axis Fresnel lens,or a directional diffuser.
As shown in Figure 4, the Takaki Lab atTokyo University of Agriculture and Tech-nology produced a system incorporatingseveral projectors illuminating a rotatingdisk.11 Other TPO displays include a com-mercially available display from Holymine
46 Photonics Spectra May 2012
3-D Displays
512_3DTV_Layout 1 4/23/12 11:15 AM Page 46
Ltd. of Kanagawa, Japan; the “fVisiOn”system developed by the National Instituteof Information and Communication Tech-nology in Tokyo, which uses a cone-shaped directional diffuser; and the workof Xu Liu and his colleagues at ZhejiangUniversity in Hangzhou, China.
Volumetric and multiprojector displays
Another type of 3-D display producesvolume-filling imagery: volumetric dis-plays, which offer many benefits.12 Theeyes converge at the same point on whichthey focus, the imagery offers full parallaxor “look around,” and the voxels thatmake up a 3-D image truly occupy a vol-ume of space that looks correct to simulta-neous users.
My former company, Actuality Systems,developed an approximately 100-million-voxel volumetric display, Perspecta, whichilluminated a flat diffuse surface with 198� 2 2-D patterns as it rotated about a ver-tical axis at 900 rpm.12 The technologieswere acquired by Optics for Hire in 2009.Other examples include displays that ion-ize molecules in the air, creating groups of glowing addressable spots in 3-D13 andsystems that rapidly move the intersectionpoint of several infrared lasers within amedium doped with rare-earth ions.14
How likely is it that tomorrow’s 3-Dmovies will be viewed without glasses, as they were in several periods in the lastcentury?15 Holografika of Budapest, Hun-
gary, has worked under the leadership ofTibor Balogh since the early 1990s to de-velop autostereo displays that scale to cin-ema sizes. A group of custom modularprojectors illuminates a selectively diffusescreen, providing each audience memberwith a unique view of the imagery. Pic-tured in Figure 6 is the C80 cinema dis-play, measuring 3 � 1.8 m, providingbright 1500-cd/m2, 24-bit RGB color im-agery visible across a 40° horizontal fieldof view, using 80 projector modules.
At these densities, the eyes may seerays of light projected by more than oneprojector at a time. Therefore, the underly-ing software considers groups of inde-pendently addressable rays that intersect in groups at each point in the image – asubtle distinction over displays that arestrictly “view”-based.
What’s next?Nearly every aspect of 3-D system de-
sign – from capture to processing and dis-playing – is still a vibrant area of research.Among the hottest topics for 2012 are thebenefits of tightly coupling the mathemat-ics of optimization to the functions of pix-
els and barriers, some recent progress inelectroholographic display and cross-disciplinary results from computationalphotography.
A successful recent example of compu-tational displays is the work being done byMIT Media Laboratory’s Camera CultureGroup in Cambridge, in which a stack oftransmissive LCDs modulates illuminationto provide 3-D imagery of greater expres-siveness than the original parallax barrierdisplays of the 1900s.16
Traditionally, as described above, a reg-ular array of vertical opaque-and-translu-cent columns directs left- and right-eyeviews toward just two viewing zones. Incontrast, content-adaptive displays rely on the techniques of mathematical opti-mization to compute – dynamically – whatpatterns on the front, rear and any inter-vening surfaces best approximate a desiredlight field. This is illustrated in the rightpanel of Figure 2. The group’s analysisalso extended the linear algebraic notionof rank to the world of display technology.A rapid sequence of various multilayerframes within the eye’s integration periodresults in 3-D imagery reconstructed withhigher fidelity, increasing the system’s effective rank.
Others seek to provide more realisticcurvature to the wavefronts emanatingfrom 3-D displays in the hope of encour-aging the eyes to converge and focus atthe same place (unlike, for example, desktop stereoscopic displays in whichyour eyes focus at the screen regardless of the depth of a reconstructed point in ascene).17
Also, autostereoscopic display engi-neers continue to yearn for progress in applied physics to provide devices withgreater numbers of rapidly modulatingpixels. Imec in Louvain, Belgium, is de-veloping MEMS technology with a pixelcount that it hopes is sufficient for trueholographic video display,18 while the
47Photonics Spectra May 2012
3-D Displays
Figure 5. The Perspecta volumetric display created100-million-voxel imagery from medical scans, 3-D graphics applications and seismic data. Picturedare M. Massey, M. Goldstein, J. Napoli and the author, with PerspectaRAD, an application for viewing and modifying external-beam radiation therapy plans. Photo by Sara Forrest.
Figure 6. The HoloVizio C80 cinematic display.Courtesy of Holografika.
512_3DTV_Layout 1 4/23/12 10:16 AM Page 47
Object-Based Media Group of the MITMedia Laboratory has been developing aspects of the pipeline shown in Figure 1,such as fundamental light-modulator components and methods of rapid 3-Dscene capture for a future holographic 3-D display.19
Furthermore, cross-disciplinary work is being done within computer graphics,signal processing and optics. It is possiblethat the field of 3-D display technologywill benefit from advances in light-fieldcameras, a topic described as early as1908 with integral photography and reju-venated by recent camera products fromLytro Inc. of Mountain View, Calif., andRaytrix GmbH of Kiel, Germany. Anotherresult of cross-disciplinary work is themathematical theory of light transporttreated as manipulations in Fourier space,including the research of Frédo Durandand his colleagues at MIT.20
Advances are announced at global con-ferences, such as the SPIE-IS&T Stereo-scopic Displays and Applications confer-ence, a part of Electronic Imaging, eachJanuary in California. Topics include 3-Dcapture, compression, processing, displayand perception, with vibrant work beingreported across the spectrum.
Meet the authorGregg E. Favalora is a principal at the engineer-ing consultancy Optics for Hire in Arlington,Mass. He founded and was CTO of the auto -stereoscopic technology firm Actuality Sys-tems; email: [email protected].
AcknowledgmentsThe author wishes to thank the following 3-Ddisplay pioneers for updates and materials: Matt Hirsch, Douglas Lanman, Pia Maffei, V. Michael Bove Jr., Yasuhiro Takaki, PappTamás and Zsuzsa Dobrányi. He also is gratefulto Matthias Ferber and John Ellis for providingfeedback on a draft of the manuscript. The author discloses that he is a chairman of theaforementioned SPIE-IS&T conference.
References1. N.S. Holliman et al (June 2011). Three-
dimensional displays: A review and applica-tions analysis. IEEE Trans Broad, Vol. 57,Issue 2, pp. 362-371.
2. J. Hong et al (2001). Three-dimensional display technologies of recent interest: prin-ciples, status, and issues. Appl Opt 50, pp.H87-H115.
3. M. Halle (May 1997). Autostereoscopic displays and computer graphics. CompGraph, Proc. ACM SIGGRAPH, Vol. 31,Issue 2, pp. 58-62.
4. S.A. Benton, ed. (2001). Selected papers on three-dimensional displays. SPIE, Vol.MS162.
5. T. Okoshi (1976). Three-Dimensional Imag-ing Techniques, Academic Press.
6. M.W. Halle (1994). Holographic stereogramsas discrete imaging systems. PracticalHolography VIII. Stephen A. Benton, ed.SPIE, Vol. 2176, pp. 73-84.
7. G. Ye et al (October 2010). A practicalmulti-viewer tabletop autostereoscopic display. Proc. ISMAR, Seoul, South Korea.IEEE, pp. 147-156.
8. O.S. Cossairt et al. Optical scanning assem-bly. US Patent No. 7,864,419. Provisionalfiled Jun. 8, 2004, issued Jan. 4, 2011.
9. L. Bogaert et al (2010). Demonstration of a multiview projection display using decen-tered microlens arrays, Opt Exp, Vol. 18, pp. 26092-26106.
10. G.E. Favalora and O.S. Cossairt. Theta-parallax-only (TPO) displays. US Patent No.7,364,300. Provisional filed Jan. 12, 2004, issued April 29, 2008.
11. S. Uchida and Y. Takaki (2012). 360-degree, three-dimensional table-screen dis-play using small array of high-speed projec-tors. Stereoscopic Displays and ApplicationsXXIII, A.J. Woods et al, eds. Proc. SPIE-IS&T Elect Imag, Vol. 8288, 8288 0D.
12. G.E. Favalora (2009). Progress in volumet-ric displays and their applications. Front Opt,OSA Technical Digest (CD), paper FTuT2.
13. H. Saito et al (2008). Laser-plasma scan-ning 3D display for putting digital contentsin free space. SPIE Stereoscopic Displaysand Applications XIX. A.J. Woods et al, eds.Proc. SPIE-IS&T Electr Imag, Vol. 6803, p. 680309.
14. H.H. Refai (2009). Static volumetric three-dimensional display. Journ Disp Tech, Vol.10, pp. 391-397.
15. W. Funk (2012). History of autostereo-scopic cinema. Proc. SPIE-IS&T ElectronicImaging, Stereoscopic Displays and Applica-tions XXIII. A.J. Woods et al, eds. Vol.8288, p. 8288 0R.
16. D. Lanman et al (2010). Content-adaptiveparallax barriers: Optimizing dual-layer 3Ddisplays using low-rank light field factoriza-tion. Proc. SIGGRAPH Asia, ACM Transac-tions on Graphics. ACM Press, Vol. 29,Issue 6, pp. 163:1-163:10.
17. W. Plesniak et al (Nov. 29, 2006). Recon-figurable image projection holograms. OptEng, Vol. 45, p. 115801.
18. R. Courtland. Spring-loaded pixels to driveholographic displays. Weblog entry. IEEESpect Tech Talk. Retrieved March 27, 2012,from http://spectrum.ieee.org/tech-talk/semi-conductors/devices/spring-loaded-pixels-to-drive-holographic-displays.
19. V.M. Bove Jr. (2011). Live holographicTV: From misconceptions to engineering.Proc. 2011 SMPTE, International Conferenceon Stereoscopic 3D for Media and Entertain-ment.
20. F. Durand et al (2005). A frequency analy-sis of light transport. Proc. SIGGRAPH,ACM Transactions on Graphics, ACM Press,pp. 1115-1126.
Photonics Spectra May 2012
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Time Delay Integration Speeds Up Imaging
BY XING-FEI HE AND NIXON O TELEDYNE DALSA INC.
T ime delay integration (TDI) imagingtechnology enables high-speed in-lineautomatic optical inspection (AOI) of
high-performance displays such as thoseused in iPhones, iPads and high-definitiontelevisions. The $130 billion flat panel display industry relies on TDI technologyto ensure that every picture is perfect.
Recently, low-temperature polysiliconused for in-plane switching liquid crystaldisplays and organic LEDs has pushedpixels to very small dimensions. For ex-ample, the iPhone’s Retina display has a density of 326 pixels per inch and a sub-pixel size of about 26 μm. The increasingdensity results in a demand for higher-speed and higher-resolution digital imagers that become increasingly light-starved and, in turn, need even higher re-
sponsivity. TDI technology is a proven so-lution that can meet these often conflictingdemands.
New TDI products are increasingly capable of imaging beyond the visiblerange. The finer display structures haveled to the use of light sources with shorterwavelengths down to the ultraviolet.
Concurrently, the solar panel industry is becoming more automated as it boostsproduction capacity. In-line inspection ofsilicon solar cells has low-illumination requirements, similar to those of flat paneldisplay inspection. However, solar cellsemit electroluminescent or photolumines-cent photons with wavelengths around1150 nm. Hence, solar cell inspection requires cameras that can detect near-IRphotons.
Line-scan and TDI technologiesLine-scan cameras operate differently
from area-scan cameras. With an area-scancamera, a matrix of pixels provides animage of the object, which contains bothlength and width information within a sin-gle image. Line-scan cameras capture im-ages one line at a time as the object beingimaged moves past the field of view. A se-ries of pictures is taken continuously, withthe pixel capture rate timed to be in syncwith the speed of the moving objects (Fig-ure 1). This series of one-dimensional im-ages forms a long two-dimensional image.
The advantage of line-scan imaging isthat it can image at very high speeds – asin hundreds of thousands of lines per sec-ond. With an area-scan camera, the systemmust wait for the camera to transfer theentire multimegapixel image data out ofthe sensor before the camera can captureanother image. With a line-scan camera,only a single line of data must be trans-ferred out before the next exposure. Thisapproach allows a line-scan camera to produce continuous images as wide as thesensor but of virtually unlimited length.Increasing imaging speed requires brighterillumination. The reality is that AOI oftenends up in a light-starved situation, eitherbecause the light source is not brightenough or safety is a concern.
CCD TDI is a special type of line-scantechnology based on multiple exposures ofthe same moving object to achieve higherresponsivity.1 In TDI operation, the speedat which a charge packet containing imagedata is transferred within the CCD is insync with the speed of the moving object,allowing the data packet to track the mo-tion of the object. Photogenerated elec-
Photonics Spectra May 201250
Using a sensor architecture that permits photoelectrons generated from multiple exposures to be summed with no additive noise enables high-speed imaging under light-starved conditions. This technology has become a standard in the automated inspection of flat panel displays and is expanding to markets such as photovoltaic panel inspection.
Object Movement
Single Line
Dual Line
TDI
Figure 1. Various line-scan technologies: single-line, dual-line and time delay integration (TDI). To achieve highresponsivity, TDI uses multiple stages to capture multiple exposures. In these stages, photogenerated signalcharges are transferred in sync with object motion. Dual-line scans are considered two-stage TDIs.
Feat imaging Teledyne_Layout 1 4/20/12 2:42 PM Page 50
trons are transferred from one TDI stageto another in the charge domain. Thetransfer is accomplished without addingany noise. Because the detector signal isproportional to the number of stages, thesignal-to-noise ratio scales linearly withthe number of stages. With resolutions ofup to 12,288 pixels, a 5.2-μm pixel size,512 TDI stages and a maximum line rateof 90 kHz, Teledyne Dalsa’s Piranha HSTDI camera family provides responsivityof more than 1000 (8-bit DN [digital num-bers])/(nJ/cm2) at minimum camera gain.
Figure 2 plots the responsivity results ofvarious standard line-scan and TDI cam-eras as a function of the inverse of themaximum line rate. The output signal ofan imager is proportional to the product of the responsivity and the exposure time,for a constant light intensity. As a result,applications with a higher line rate will require cameras with higher responsivitycapabilities to maintain a useful signal-to-noise ratio. CCD TDI clearly outperformssingle-, dual- and quad-line-scan technolo-gies because it can incorporate hundredsof stages in the detector. Although TDIdoes not have exposure control, pulsedLED lighting can be used to maintain aconstant exposure time when the objectmotion speed varies.
Signal-to-noise ratioIn many imaging applications, two
types of noise are most important. Thefirst, called read noise, is associated with“reading” the signal – that is, convertingphotogenerated signal charges into a volt-age and then to a digital output. The sec-ond, photon shot noise, is associated withquantization of the incident illuminationinto a finite number of discrete photons.Other sources of noise exist, but they aremuch less important than the above.
In CCDs, the read noise (σR) is fixedbecause photoelectron signal packets areconverted only once, after they have beentransferred to a readout structure at theedge of the CCD array. In CCD TDIs, theread noise remains fixed regardless of thenumber of stages. In CMOS, becausecharges must be read before the signal canbe transferred out of each pixel, each readresults in its own noise. Consequently, adual-line-scan CMOS array will have�2� the read noise of an equivalent sin-gle-line-scan CMOS array. Similarly, an n-stage CMOS TDI array will have �n�the read noise of an equivalent single-lineCMOS array.
51Photonics Spectra May 2012
Re
sp
on
siv
ity,
DN
/(n
J/c
m2)
1200
1000
800
600
400
200
0503020100 40 60
1/Maximum Line Rate, µs
HS/HN
ES
P4
P2/P3
DragsterS3
Eliixa+
Figure 2. Responsivity (at minimum gain, 8 bits) versus the inverse of the maximum line rate of various line-scan cameras. HS and ES from Teledyne Dalsa are CCD TDI cameras. The Eliixa+2 from e2v Ltd. is a CMOS quad-line scan. P4 from Teledyne Dalsa and Dragster3 from Awaiba are CMOS dual-line scans. P2 and P3 from Teledyne Dalsa are CCD single-line scans. The solid line plots the responsivity required to achieve a 200-DN (digital number) signal with an irradiance level of 100 µW/cm2.
Figure 3a. This automaticoptical inspection systemfor thin-film transistor (TFT)arrays uses TeledyneDalsa’s HS-12k/5.2-µm256-stage TDI cameras.Light sources are select-able red, green, blue orwhite LEDs. Courtesy ofFavite Inc.
Figure 3b. Images of TFT structures with different lighting conditions: (a) viewed under a microscope; (b) front illumination; (c) backlight; and (d) both front illumination and backlight.
Feat imaging Teledyne_Layout 1 4/20/12 2:42 PM Page 51
The photon shot noise (σPS) is alwaysequal to the square root of the number ofphotoelectrons collected and read (S), ex-cept in highly unusual situations, such asin the deep-UV when each photon cangenerate multiple photoelectrons. Because
the ratio of the signal S to the photonnoise (σPS) is always equal to �S, it isalways advantageous to increase S to maximize the signal-to-noise ratio. TDIscan increase S without increasing the incident illumination.
For an n-stage CCD TDI, the signal-to-noise ratio at signal S per line is as follows:
SNRn � nS / � (�R2 � nS)
� n � SNR, if S is small� �n � SNR, if S is large
For an n-stage CMOS TDI:
SNRn � nS / � (n�R2 � nS) � �n � SNR
In light-starved conditions where thesignal S is small, CCD TDIs achieve thebest signal-to-noise ratio.
Automated display inspectionA thin-film transistor (TFT) LCD is a
sandwich of two panels with liquid crystalmaterial in between. An array of transis-tors on the TFT panel controls the polar-ization of the liquid crystal and, hence, thelight intensity. Another panel contains anarray that filters out the spectra of eachprimary color (red, green and blue) foreach subpixel.
A high-definition television (1920 �1080 pixels) screen has about 6 millionsubpixels. The industry adopts a zero-
52
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Photonics Spectra May 2012
Time Delay Integration
Figure 4. This automatic optical inspection system for color filters uses Teledyne Dalsa’s ES-8k/7-µm 32-stage TDI cameras. The single-pass system uses 34 cameras. Courtesy of Utechzone Co. Ltd.
Feat imaging Teledyne_Layout 1 4/20/12 2:42 PM Page 52
defect policy; thus, every subpixel must beperfect.
The AOI systems for flat panel displaysmust operate in-line with the productionflow. This helps minimize handling of the
large, thin glass panel blanks (0.3 to 0.5mm thick) to avoid breakage. They alsomust be fast enough to avoid becoming abottleneck in the production flow. In a $3 billion fab, takt time is a key metric to
ensure that the production throughput will meet the expected return on invest-ment. To prevent the inspection systemfrom limiting production flow and increas-ing the takt time, high-speed cameras arerequired.
Automatic optical inspection for TFT arrays is one of the most challengingapplications today, and all array AOI sys-tems use CCD TDI cameras. Speed andresolution are increasing with the adoptionof low-temperature polysilicon in smart-phones, where the pixel size is smallerthan the pixel size in amorphous siliconpanels used in televisions. The TFT pixelis only a few microns across. This requiresan AOI object resolution of about 1 μm,and it is getting even smaller. This is closeto the spatial resolution limit of most optical systems.
Figure 3a is an advanced TFT arrayAOI system developed by Favite Inc. of Hsinchu, Taiwan. At the core of the system are Teledyne Dalsa’s latestHS-12k/5.2-μm 256-stage TDI cameras.The system can accommodate G8.5glasses (2500 � 2250 mm) and can detectdefects in TFTs with an object resolutionof 0.8 to approximately 2 μm (see Figure
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Photonics Spectra May 2012
Time Delay Integration
Figure 5. The quantum efficiency of HS and HN TDI cameras: HS TDI is designed for visible imaging, while HN TDI is optimized for near-IR imaging applications.
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3b). Multiple scans are performed at a linerate of 80 to approximately 90 kHz tocover the entire glass. The number of TDIcameras in the system depends on the enduser’s requirements. Because some areas(e.g., pixel area) are transparent whilesome (e.g., metal pad) are opaque, bothfront and back illuminations are used withselectable red, green, blue or white lightsources. Figure 3b shows that simultane-ous front and back illumination producesimages with the contrast necessary to detect many types of small defects.
Beyond the visible spectrumColor filters also require in-line high-
speed automated inspection. Figure 4shows an advanced AOI system for colorfilters developed by Utechzone Co. Ltd. of Taipei, Taiwan. The system uses Tele-dyne Dalsa’s ES-8k/7-μm 32-stage TDIcameras. In its single-pass design, 34 cam-eras are installed in two separate lines.Seventeen cameras capture images withangled front illumination, while the re-mainder capture backlit images. The sys-tem inspects G8.5 glasses at 450 mm/swith a resolution of 8 μm.
As a de facto standard for the flat panel
display AOI industry, the Piranha HS TDIcamera continues to evolve to meet futurerequirements. The next generation featureseven higher spatial resolution and lowernoise. Backside thinning and thick detec-tion layers are a few of the technologiesthat Teledyne Dalsa has developed. Thequantum efficiency at different wave-length ranges can be optimized for UV,visible or near-IR imaging.
The HN-8k/7-μm 256-stage TDI is anew camera for near-IR imaging. At theminimum gain setting, it has a broadbandresponsivity of 1078 (8-bit DN)/(nJ/cm2);at the 1-μm wavelength, its responsivity is 420 (8-bit DN)/(nJ/cm2). Figure 5 com-pares the quantum efficiency spectra ofthe HS-8k/7-μm and HN-8k/7-μm TDIcameras. Unlike the HS TDI camera,which has vertical anti-blooming struc-tures that reduce near-IR response, the HN TDI has lateral anti-blooming, result-ing in enhanced sensitivity in the near-IR.
Solar panel manufacturing continues toadopt automation, and AOI plays a keyrole. Currently, wafers are inspected at aspeed of about one per second. The nor-mally poor CCD sensitivity in the near-IRis the limitation for electroluminescence
and photoluminescence imaging tech-niques that are particularly effective in re-vealing microcracks that can occur duringthe processing.
To detect electroluminescent and photo-luminescent signals, the HN-8k TDI cam-era provides responsivity comparable tothat of InGaAs cameras at ~1 μm. Com-pared with InGaAs imager-based systems,however, the HN-8k has a much lowersystem cost. Because of this, TDI imagingis becoming an enabler in automatinghigh-volume solar panel manufacturing.
Meet the authorsDr. Xing-Fei He is senior product manager at Teledyne Dalsa Inc. in Waterloo, Ontario,Canada; email: [email protected]. Nixon O is technical director at TeledyneDalsa; email: [email protected].
References1. S.G. Chamberlain and W.D. Washkurak
(July 1, 1990). High-speed, low-noise, fine-resolution TDI CCD imagers. Proc SPIE,Vol. 1242, pp. 252-262.
2. e2v Ltd. Eliixa+ 16k pixels CMOS line-scancamera datasheet: http://tinyurl.com/7ju9z5z.
3. Awaiba Dragster linescan sensor short specsheet: http://tinyurl.com/7952784.
54 Photonics Spectra May 2012
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Wafer-EtchingProcess Brightens Future for LEDs
BY DEREK MENDESIMTEC ACCULINE LLC
L ED manufacturers today can choosebetween two very different manufac-turing processes. Dry etching creates
efficient, bright LEDs – but it does soslowly and with limited throughput. Andwet etching is very scalable and fast, butthe LEDs it produces are less effective and less efficient.
Wet etching requires polishing touch-upwork on the wafers to increase light-ex-traction efficiencies, but it still results in a considerable cost savings over dry etch-ing. It also scales much more efficiently,multiplying the savings dramatically asthroughput and wafer size increase.
“Say you look at a flat substrate, andthen you make a patterned substrate – thecost of making a patterned substrate in-creases the cost by 20 percent or maybe25 percent,” said Rajiv K. Singh, vicepresident, co-founder and chief technologyofficer of Sinmat Inc. “The wet etchwould decrease that added cost by half.”
LED manufacturers must cut costswherever they can, while still maintainingor improving quality. And although larger-diameter sapphire wafers hold promise formaking the manufacturing process signifi-cantly more efficient, they also presentchallenges to fabricators.
Using a 4-in.-diameter wafer instead of a standard 2-in. one quadruples thewafer’s available surface area. Movingfrom a 4-in. wafer to a 6-in. one doublesthe surface area, and every subsequentjump in size further increases it.
But if existing manufacturing equip-ment cannot cheaply or easily scale up to
accommodate the larger form factors, thetheoretical gains in efficiency with largerwafers are canceled out.
Patterned sapphire substrates (PSS) play two roles in the LED industry. On the wafer-supplier side, they mean dollarsigns: PSS wafers represent higher grossmargins than traditionally polished sap-phire ones. And on the product develop-ment side, LEDs based on PSS wafers are more efficient and more effective aslight sources.
“The PSS reduces the dislocation den-sity in the GaN layer and enhances thelight extraction efficiency (LEE) from the LED chip by scattering the light con-fined in GaN layer attributed to the criticalangle between GaN (n = 2.4) and sapphiresubstrate (n = 1.7) (or air (n = 1.0),” wroteKazuyuki Tadatomo and Narihito Okadaof Yamaguchi University in Japan in a2011 paper.1
Dry etchingThe most common method for produc-
ing PSS wafers is dry etching, whose tech-niques and technology are commonplace,including the inductively coupled plasmavariant lithography. This process exposes apattern onto the photoresist of the sapphiresubstrate and anisotropically etches it intothe crystalline structure via exposure tofluoride-based plasma gas and microwaveenergy. The resulting pattern – highly uni-form, densely packed and dome-shaped –encourages lateral film growth, which, inturn, means fewer defects and increasedlight refraction.
Photonics Spectra May 201256
With far higher etch rates and per-unit cost savings, high-temperature wet etching of sapphire wafers is giving dry etching a run for its money.
The market for LEDsThe high-brightness (HB) LEDmarket experienced a 93 per-cent growth rate between 2009and 2010, according to a mar-ket research report from Strate-gies Unlimited. In 2009, theglobal market for packaged HBLEDs was $5.6 billion; in 2010,it grew to $10.8 billion. The report predicts that the globalmarket will be worth $18.9 billion by 2015, representing a compound annual growth rate of 11.8 percent.
The US Department of Energyis expected to release a reportstating that, to compete effec-tively with the fluorescent light-ing market, solid-state lightingmanufacturers must cut the costper lumen (currently at $18/klm)by eight times to $2.20/klm by 2015.
512 LEDS Imtec Feat_Layout 1 4/20/12 1:52 PM Page 56
Although LEDs based on dry-etchedPSS wafers are highly efficient lightsources, the process is slow. A standard 2-in. wafer can take between 30 and 60min to etch, depending upon the depth ofthe pattern being etched and the type offilm used. Average rates are practicallyimpossible to define because of all thepossible process variables, but dry-etchingrates generally range between 50 and 200nm/min, or 20 min/μm.
The dry-etch process also cannot be effectively scaled. The throughput of a dryetcher decreases as wafer size increasesbecause, as the size goes up, fewer waferswill fit inside the vacuum chamber. Thismeans that more expensive plasma-etchingtools are required for bigger wafers ifthroughput is to remain comparable. Andmore tools mean more operational costs:facilities, utilities, maintenance and con-sumables.
Wet etchingIn contrast, the high-temperature wet-
etching process is comparatively muchcheaper than dry etching – and faster, too.
During high-temperature wet etching,wafers coated with gallium nitride or in-dium gallium nitride (InGaN) are placedin a tank with a mixture of etching andbuffering agents: sulfuric and phosphoricacids, typically in a 1:1 or 3:1 ratio. Be-fore submersion, a plasma-enhancedchemical vapor process spins a silicondioxide mask onto the sapphire substrate,and lithography exposes the required pat-tern. The mixture is brought to tempera-tures ranging between 260 and 300 °C –much higher than those used in traditionalsemiconductor fabricating, which typicallyrun between 150 and 180 °C.
Etching rates do not increase along alinear scale as temperatures rise. Instead,they increase exponentially, so that a 300°C temperature may make etching twice asfast as at 260 °C. On the other hand, “theetching rate increased linearly when theH2SO volume ratio increased from 0 to 75percent,” as reported by D.S. Wuu of Na-tional Chung Hsing University in Taiwanand colleagues.2
High-temperature wet-etching rates canbe measured in microns per minute; a rateof more than 1 μm/min is achievableunder the correct conditions, according toSinmat’s Singh, who added that it is rea-sonable to expect full etching of a stan-dard 2-in. wafer in five minutes. And withregard to cost, a process tank for a batchof 6-in. wafers is only slightly more ex-
pensive than a tank designed for a batch of2-in. wafers – and it can hold the samenumber of wafers.
Of course, using extremely hot chemi-cals can be challenging for manufacturers:Safety is paramount with chemicals hotand powerful enough to rapidly etch sap-phire surfaces. To maintain safety, anysystem must feature a suitable chemicaltank, designed not to react with any of the chemicals. Preferably it will be con-structed of a sturdy substance such ashigh-purity virgin annealed quartz. Noplastics should come into contact with thechemical mixture, and built-in temperaturesensors should feed precise readings backto the systems management equipment. As added safety features, some tanks include a cooldown module to house the hot chemistry while it cools and overflowtanks that can hold 120 percent of themain tank’s volume in case of an accident.
Wet-etching researchA sapphire-wafer producer in Japan
recently concluded testing of the ImtecAcculine XE-Series bath. The experimentcompared uniformity, etch-rate and struc-ture-formation data with previous in-housetest results. The company especially notedthe tight temperature control throughoutthe bath, which aided etch uniformity.Also cited was the ability of the bath tem-
perature to recover quickly once a newbatch of five 2-in. wafers was loaded intothe 280 °C solution. Testing will continueon 6- and 8-in. sapphire wafers, and simi-lar results are expected.
The PSS created using the high-temper-ature wet-etching process is a significantimprovement over a nonpatterned wafer interms of light extraction and efficiency.The process results in the creation of trun-cated cone shapes – conical structureswith flat tops.
Unfortunately, the flattop surface of thecone poses two significant challenges tothose used to working with the dry-etchingprocess. The flattop acts to discourage thelateral growth of film and encourage verti-cal film growth, resulting in more defects.Also, the shape of the structures inhibitsefficient light refraction.
Because this is still a relatively newprocess, research is being conducted intoimproving the quality of wet-etched sap-phire wafers. Sinmat is one company un-dertaking such research, and it has devel-oped a method to polish the flat structures,producing rounder, more efficient domesthat more closely resemble the shape ofthose produced by the dry-etching process.
Others are investigating the creation ofpatterns other than cone shapes. At Na-tional Chung Hsing University in Taiwan,Jing-Jie Dai and colleagues created “trun-cated-triangle-striped patterned-sapphiresubstrate and a rhombus-like air-voidstructure at the GaN/sapphire interface toincrease the light extraction efficiency.The truncated-triangle-striped patterned-sapphire substrate was fabricated througha wet-etching process in hot sulfuric andphosphoric acid solutions. A rhombus-likeair-void structure at the GaN/sapphire in-terface was formed though a wet-etchingprocess along a V-shaped air-void struc-ture on the patterned sapphire substrate.”3
After testing, the researchers concludedthat “the [rhombus-like air-void structure
57Photonics Spectra May 2012
High-temperature wet etching of sapphire wafers results in the creation of truncated cone shapes: conical structures with flat tops. Images courtesy of Imtec.
Formerly flat, truncated shapes polished and rounded (left) now more closely resemble dry-etched PSS patterns(right).
512 LEDS Imtec Feat_Layout 1 4/20/12 1:52 PM Page 57
LED] has a 65 percent light-output powerenhancement, a smaller divergent angle,and a periodic higher light intensity profilecompared to a [flat sapphire substratestandard LED] that provides a high exter-nal quantum efficiency in nitride-basedLED applications.”3
Meet the authorDerek Mendes is the sales/marketing adminis-trator at Imtec Acculine LLC in Fremont,Calif.; email: [email protected].
References1. T. Kazuyuki and N. Okada (2011). Develop-
ment of patterned sapphire substrate and theapplication to the growth of non-polar andsemi-polar GaN for light-emitting diodes.Proc. SPIE, 7954, 795416; http://dx.doi.org/10.1117/12.874179.
2. D.S. Wuu et al (June 2006). Fabrication ofpyramidal patterned sapphire substrates forhigh-efficiency InGaN-based light emittingdiodes. Journ Electrochem Soc, Vol. 153,No. 8, pp. G765-G770.
3. J.-J. Dai et al (2010. Enhanced the light ex-traction efficiency of an InGaN light emittingdiodes with an embedded rhombus-like air-void structure. Appl Phys Expr, Vol. 3, Issue7, pp. 071002-071002-3.
58
OSA Optics and Photonics Conferences and Meetings
Lasers, Sources, and Related Photonic DevicesOSA OPTICS & PHOTONICS CONGRESS29 January - 3 February 2012San Diego, California, USA
Advanced Solid-State Photonics (ASSP) www.osa.org/assp
Advances in Optical Materials (AIOM) www.osa.org/aiom
Fiber Lasers and Applications (FILAS)www.osa.org/filas
Laser Applications to Chemical, Security and Environmental Analysis (LACSEA)www.osa.org/lacsea
Research in Optical SciencesOSA OPTICS & PHOTONICS CONGRESS19-21 March 2012Berlin, Germany
High Intensity Lasers and High Field Phenomena (HILAS) www.osa.org/hilas
Quantum Information and Measurement (QIM) www.osa.org/qim
International Conference on Ultrafast Structural Dynamics (ICUSD)www.osa.org/icusd
Biomedical Optics and 3D ImagingOSA OPTICS & PHOTONICS CONGRESS29 April-2 May 2012Miami, Florida, USA
Biomedical Optics (BIOMED)www.osa.org/biomed
Digital Holography & 3-D Imaging (DH)www.osa.org/dh
Advanced PhotonicsOSA OPTICS & PHOTONICS CONGRESS17-21 June 2012Colorado Springs, Colorado, USA
Access Networks & In-house Communications (ANIC) www.osa.org/anic
Bragg Gratings, Photosensitivity and Poling in Glass Waveguides (BGPP)www.osa.org/bgpp
Integrated Photonics Research, Silicon, and Nano-Photonics (IPR) www.osa.org/ipr
Nonlinear Photonics (NP)www.osa.org/np
Photonic Metamaterials and Plasmonics (META) www.osa.org/meta
Signal Processing in Photonics Communications (SPPCom)www.osa.org/sppcom
Specialty Optical Fibers and Applications (SOF) www.osa.org/sof
Imaging and Applied OpticsOSA OPTICS & PHOTONICS CONGRESS24-28 June 2012Monterey, California, USA
Applied Industrial Optics: Spectroscopy, Imaging, & Metrology (AIO) www.osa.org/aio
Computational Optical Sensing and Imaging (COSI) www.osa.org/cosi
Imaging Systems Applications (IS) www.osa.org/is
Optical Fabrication and Testing (OF&T) www.osa.org/oft
Optical Remote Sensing of the Environment (ORS) www.osa.org/ors
Optical Sensors (SENSORS) www.osa.org/sensors
Renewable Energy and the EnvironmentOSA OPTICS & PHOTONICS CONGRESS11-15 November 2012Eindhoven, The Netherlands
Optical Instrumentation for Energy & Environmental Applications (E2) www.osa.org/e2
Optical Nanostructures and Advanced Materials for Photovoltaics (PV) www.osa.org/pv
Optics for Solar Energy (SOLAR)www.osa.org/solar
Solid-State and Organic Lighting (SOLED)www.osa.org/soled
Visit www.osa.org/meetings for more information on OSA meetings.
For information about exhibiting at or sponsoring any of these targeted OSA events, please contact the OSA Sales Team at [email protected] or +1.202.416.1474.
Photonics Spectra May 2012
Wafer Etching
The Imtec Acculine XE-Series tanks are constructed of virgin annealed quartz and contain no plastics that come in contact during use of high-temperature chemicals. The XE-Series also includes a cooldown module and an overflow tank in case of an accident.
512 LEDS Imtec Feat_Layout 1 4/20/12 1:52 PM Page 58
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512_AstonSciencePark_Pg59_Layout 1 4/19/12 3:03 PM Page 59
193-nm Lithography Opens Doorsfor Diffractive Micro-Optics
BY MARC D. HIMEL AND JIM MORRISDIGITALOPTICS CORPORATION
The field of diffractive micro-optics isplaying an increasingly importantrole in today’s technology, from high-
speed data communications to bar-codescanners, and even in one of the world’smost popular gaming interfaces.
Now, advances in the tools available forthe manufacture of diffractive optics haveopened up additional opportunities in visi-ble and near-IR applications that requirevery large angular distributions, includingvirtual keyboards, laser levels, opticaltouch panels and screens, and 3-D sensing.In many of these applications, laser diodescombined with diffractive optics are re-placing LEDs that use conventional col-lection optics. This helps decrease packagesize, lower cost and increase wall-plug efficiency.
When the first laser light was produced,Ted Maiman and colleagues probably didnot guess that their invention would be-come ubiquitous in just 50 years. At thetime, they considered laser light to be asolution in search of a problem. But today,lasers shape our world in countless ways,and new applications are developed everyday. Many of these require advanced ma-nipulation of laser light that can be accom-plished only with diffractive optics.
These applications include signal moni-toring for today’s high-bandwidth datacommunication systems, in which a dif-fractive optic not only couples light frommultiple lasers into and out of opticalfiber, but also samples a small percentageof the energy to ensure signal power sta-bility; 2-D bar-code readers, which use a frame generator to identify the region of interest; and off-axis illumination that provides resolution enhancement fortoday’s high-end lithography scanners.
The availability of advanced e-beam
Photonics Spectra May 201260
Design considerations and fabrication affect performance for a near-IR large-angle homogenizer for use in 3-D sensors based on time of flight.
Figures 1-3. Top: A traditional approach for creating a uniform far-field distribution uses a refractive collimating lens in line with a diffractive pattern generator. Center: An all-diffractive approach for creating a uniform far-field distribution. In this example, the collimating lens is on one surface, and the pattern generator is on the second surface. Bottom: By combining the diffractive lens and pattern generator into a single surface, we can optimize the design for efficiency and eye safety. Images courtesy of DigitalOptics Corporation.
Diffractive Optics Tessera Feat_Layout 1 4/20/12 1:49 PM Page 60
and optical lithography tools, originallydeveloped for computer chip manufactur-ing, has opened the door to a wide rangeof applications that require very large divergence angles from the diffractive optical element (DOE). To be efficientenough for practical use, these elementsrequire feature sizes equal to or less thanthe wavelength of light. Two key con-sumer examples are the laser virtual key-board (such as Celluon’s Magic Cube) andMicrosoft’s Kinect 3-D gaming interface,which uses structured light to determinedistances.
Technology based on time of flight(TOF) is also being implemented in depth-sensing applications, such aseeDoo’s iSec gaming system and large-area optical touch screens. One advantageof TOF technology is that simpler opticscan be used to uniformly illuminate thefield of view (FOV) because a structuredlight pattern is not required. Most TOFsystems today use LEDs. However, factorssuch as lower cost, improved wall-plug efficiency, reduced size and improveddepth-sensing performance may drive theadoption of laser-based illumination. Thiswill occur only if micro-optical compo-nents can be used to efficiently create the desired far-field light distribution.
Diffractive-based TOF light sourcesToday’s TOF systems use multiple LEDs
combined with collection optics that pro-duce a circular FOV with a nominal Gauss-ian intensity profile. To maintain a decentdynamic range for a 3-D camera, the illu-mination intensity should be held to a 2:1or 3:1 ratio from center to edge. This re-quires that a Gaussian profile significantlyoverfill the FOV. Therefore, more than 50percent of the light emitted by the LEDsand collected by the lens falls outside thecamera’s FOV and goes to waste. This canbe somewhat improved if we allow the op-tics to be made larger, which would also in-crease the size of an already large assembly(i.e., some TOF systems already use eightor more LED modules).
A typical implementation of a DOE-based illumination system uses a colli-mated laser beam incident on a computer-generated hologram that has been de-signed to generate the desired far-field optical distribution. With TOF 3-D sens-ing, the desired output is to illuminate the field of view of a VGA or megapixelnear-IR camera. To uniformly illuminatethe sensor over a large 70° � 50° FOV
requires correcting the DOE for cosinetheta effects, which means redistributingenergy to send more light to the larger deflection angles. One advantage of aDOE is that the energy distribution can beoptimized, so that the image sensor is uni-formly illuminated after light reflects off
an object and is reimaged with a low f/#lens. Unlike an LED-based system that illuminates a scene with a circular distri-bution, the DOE design can be optimizedto illuminate the rectangular area withinthe sensor’s FOV, thus improving wall-plug efficiency.
61Photonics Spectra May 2012
Figure 4. Far-field image (a) and cross section (b)using a laser source, refractive collimating lens anddiffractive pattern generator; (c) and (d) representan LED-based illuminator. Courtesy of LednLight byGaggione SAS catalog.
a
b
c d
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The shift to a laser-based source also allows the package size to be significantlyreduced, which will be necessary when 3-D sensing and gesture control are to beimplemented beyond industrial, automo-tive and gaming consoles, where modulesize is less critical. Using non-TO-canpackaging approaches, such as C-mount orsilicon benches, in conjunction with dif-fractive optics will provide packages witha total height from 1.5 to 3 mm, which arethin enough to fit into the bezel of flatpanel televisions, computer monitors, lap-top computers and even smartphones.
The requirements for manufacturing aDOE for this application are challenging.A simple binary design requires featuressmaller than the wavelength of the illumi-nation source. Without tight control overthe lithographic process, it will not be pos-sible to meet the requirements for both ef-ficiency and nondiffracted zero-order en-ergy. If the zero-order energy is too high,the system may not meet eye safety re-quirements. Although methods are avail-able to reduce the impact of the zero orderfor this reason, most of these methods fur-
ther reduce the efficiency of the DOE,thus requiring higher power from the laser.To meet eye safety requirements, Digi-talOptics Corp. has developed a processusing deep-UV lithography that maintainsefficiency while reducing the impact ofthe zero order.
A key differentiator for this design isthe ability to combine different opticalfunctions into a single diffractive opticalelement. Figure 1 shows a traditional ap-proach for creating the uniform far-fielddistribution using a refractive collimatinglens in line with a diffractive pattern gen-erator. The combined efficiency of the lens(99 percent) and DOE (75 percent) will beapproximately 75 percent, sufficient formost applications. One drawback to thissystem is that approximately 1 percent ofthe energy will not be diffracted by theDOE and will propagate as a collimatedbeam into the far field.
For higher-power applications, thisposes an eye safety risk. It is also possibleto eliminate the refractive lens by substi-tuting a diffractive lens. If the lens is fab-ricated on one side and the pattern genera-
Photonics Spectra May 2012
Diffractive Micro-Optics
Figure 6. Representative scanning electron microscope images of an eight-phase-level DOE manufactured with 200-nm features. Courtesy of DigitalOptics Corporation.
Figure 5. Far-field image based on a diffractive optical element (DOE) that combines the collimating lens with the pattern generator (70° � 50° diffuser). Note the absence of the zero-order energy peak. Courtesy of DigitalOptics Corporation.
Diffractive Optics Tessera Feat_Layout 1 4/20/12 1:49 PM Page 62
512_SocInfoDisplay_Pg63_Layout 1 4/19/12 3:03 PM Page 63
tor on the second side of a single element,one component is eliminated from the sys-tem. In this case, the net efficiency will be about 56 percent (75 percent for eachDOE surface); however, it will still havean eye safety issue related to the light thatis not diffracted by the second surfaceDOE (Figure 2). It is preferable to com-bine both the collimating and pattern gen-eration functions into a single surface.This can be achieved with advanced 193-nm lithography tools that can produce sub-200-nm features with 12-nm overlay (athree- to fourfold improvement over i-linelithography). This can produce a singlesurface design with an efficiency of 75percent, while the nondiffracted energy di-verges for improved eye safety (Figure 3).
To systematically develop this process,DigitalOptics created three designs: a two-phase-level large-angle diffuser thatmatches the FOV (70° � 50°) of the near-IR camera; a four-phase-level high-numer-ical-aperture collimating lens combinedwith a 70° � 50° rectangular diffuser; andan eight-phase-level lens plus diffuser design with features as small as 200 nm.
The first design was manufacturedusing i-line process equipment; the other
two were manufactured using the 193-nmprocess. The goal for the first was to opti-mize the intensity distribution over thecamera’s entire field of view. The imagesshown in Figure 4 represent the far-fielddistribution imaged with a 14-mm-focal-length lens onto an IR-capable digital sin-gle-lens reflex camera. Note the presenceof the well-defined edge cutoff and thehigh zero-order peak in the center of theimage on Figure 4a. Although the energyin the zero order is less than 1 percent ofthe total energy, it still may not be eye-safe because it is well collimated. Thecross-section profile in Figure 4b showsgood uniform illumination – a significantimprovement over the near-Gaussian dis-tribution characteristic of LED illumina-tors (Figures 4c and 4d).
The second design incorporates both thecollimating and diffusing function into oneDOE and maintains the sharp edge roll-offwhile diffusing the zero order over a largerangle. Figure 5 shows the measurementsfor the combined lens and diffuser design.Most of the energy concentrates into thedesired rectangular FOV with very littleedge roll-off. The zero-order energy isalso dispersed and is not observable in
the image. Finally, Figure 6 shows the initial results of an eight-phase-level DOEmanufactured on a 193-nm lithographytool supporting 200-nm features and 20-nm overlay.
This work demonstrates all of the build-ing blocks required to manufacture aneight-phase-level diffractive optic thattakes the output from a conventional near-IR laser and shapes it into a far-field dis-tribution that uniformly fills the field ofview of a near-IR camera while remainingeye-safe. A 193-nm lithography scannerallows a quick ramp of this design to high-volume production for applications ingaming and other human-machine inter-face systems, such as laptops and flatpanel televisions. The incorporation of thisdesign into an integrated micro-opticalmodule will even allow this capability tobe introduced into smartphones and thintablet computers.
Meet the authorsMarc D. Himel is a former senior principal engineer at DigitalOptics Corporation. JimMorris is senior principal engineer at Digital -Optics Corporation, which is a subsidiary ofTessera Inc.; email: [email protected] [email protected].
Diffractive Micro-Optics
Diffractive Optics Tessera Feat_Layout 1 4/20/12 1:49 PM Page 64
The first humanoid robot astronautboarded the International Space Station (ISS) in August 2011.
Mission STS-133 was scheduled as oneof the last commitments of NASA’s spaceshuttle flights. Onboard that Discoveryflight was Robonaut R2, a humanoid robot– developed by General Motors (GM) andNASA – with more skills than any previ-ously tested similar device. One skill isdecision-making, which it does using so-phisticated imaging algorithms based onMVTec’s software library Halcon.
The robot worked precisely and relia -bly, realizing a 15-year dream of NASA’s.However, that mission was just the begin-ning of another age: robot astronauts thatcan support human activity in space underzero gravity.
Robonaut 2 looks like an astronaut,with its gold-colored head and metallizedvisual field. The proportions of its whitetorso, arms and head are close to that of a human body. But Robonaut 2 does not
have legs. Its body is fixed on a specialrack; thus, it cannot walk or run.
Its development began in 2007. Therobot not only will support the daily workof an astronaut at the space station, butalso will execute boring and recurringwork. As with automobile production robots – and in contrast to a humanworker – Robonaut 2 does not get tired.Thus, it seems the optimal solution fordangerous work such as performing EVA (extravehicular activity) outside thespacecraft.
Robonaut 2’s flexible vision systemcombines a stereovision pair of ProsilicaGC2450 cameras from Allied Vision Tech-nologies GmbH of Stadtroda, Germany,and infrared distance measurements andstructured lighting, enabling it to achieverobust, automatic recognition and pose-estimation of objects on the ISS. Robust
object recognition requires the use of com-plex patterns measured from the environ-ment using multiple sensor types.
Complex pattern recognition of entirescenes can be computationally prohibitive.NASA and GM’s solution was to apply pattern recognition to small segmented regions of the scene. Information within the image, such as color, intensity or tex-ture, was used to segment the regionsscanned by the robot’s imagers.
Myron Driftler, robonaut project man-ager at NASA, said MVTec’s Halcon 9.0was chosen to integrate the sensor datatypes and to perform all the complex computations in a single development environment.
“Halcon supports GigE Vision and allows for a quick setup of each camera in software via its automatic code-genera-tion feature,” he said. The rangefinder is
65Photonics Spectra May 2012
BY DR. LUTZ KREUTZER, MVTEC SOFTWARE GMBH
Robonaut R2 was developed by NASA and General Motors as a humanoid machine with more skills thanany other previously tested similar robot device. Photo courtesy of NASA.
The first robotic visitor to the International
Space Station performs difficult visual and
tactile tasks in service to the human crew.
Vision Software EnablesNASA Robonaut to See
512_Feat_Robonaut_Layout 1 4/20/12 11:54 AM Page 65
a Swiss Ranger SR4000 from Mesa Imag-ing AG of Zurich.
The robot’s tactile force and finger posi-tion sensors are custom-designed and -fab-ricated. Its rangefinder, force sensors andfinger position sensors use custom C/C��code to perform depth measurements andtactile object recognition.
“Halcon’s Extension Package Program-ming feature allows us to import all customcode into a single development environ-ment, such as HDevelop used for rapid pro-totyping of our applications,” Driftler said.“The stereo camera calibration methods in-side Halcon are used to calibrate the stereopair and will also be used eventually to calibrate the Swiss Ranger.”
Of the many planned ISS tasks for Robo-naut 2, sensing and manipulation of softmaterials are among the most challenging,requiring a very high degree of coordinatedactuation. For example, a soft-goods boxmade of a flexible ortho fabric holds a setof EVA tools. To remove a tool, the boxmust be identified, opened and reclosed.The challenge lies in the tendency of thefabric lid to float around in zero-g, despite
the base being secured. The lid can fold inon itself in unpredictable ways. Lid stateestimation and grasp planning will be themost difficult functions to perform for thisspecific task, which requires a good mix ofstandard computer vision and motion plan-ning methods combined with new tech-niques that combine the two fields.
“For all these purposes, Halcon has many
66 Photonics Spectra May 2012
Robotic Vision
This screen shot shows the robonaut’s command and control screen. Courtesy of NASA.
The robonaut’s eyes see a pair of left and right views acquired during control of the position of a togglehood, and that the toggle hood is in a closed position. Courtesy of NASA.
The Robonaut R2 manipulates a space blanket. Handling soft goods such as this is a prime challenge to the robot’s visual and tactile sensors. Courtesy of NASA.
512_Feat_Robonaut_Layout 1 4/20/12 11:54 AM Page 66
features that will allow for the successfulexecution of the soft-goods-box task de-scribed,” Driftler said. A single laptop com-puter connected to the robonaut will runboth the R2 Command and Control and theFlexible Vision System software. Processingpower will therefore be limited, calling forintelligent use of small, focused Halconimage processing regions of interest (ROIs).
To locate the soft-goods-box ROI, Hal-con texture segmentation functions will beused, Driftler said. The box lid fasteners,which are composed of latches and grom-mets, will be identified in the stereo imagesby using Halcon’s shape-based matchingtechniques.
The shape-based matching techniquesalso will be used to search for grommetsthat can be in any orientation once the lid is opened and floating around. Point-basedstereo vision will be used for fast computa-tion of the lid fastener poses. Halcon’s “in-tersect lines of sight” function will use thestereo-pair calibration information and thelocation of the fastener components in eachimage to compute the six-dimensional poseof each component.
“As our own understanding of the taskadvances, Halcon’s built-in classification
techniques and functions will be used forcomplex pattern recognition such as usingfused image, tactile and finger-positiondata within the Halcon development envi-ronment to predict a feasible grasp locationfor unfolding the lid to close the box,”Driftler said.
Robonaut R2 is the first step into a new
dimension of humanoid robots in astronau-tics – the start of a hopeful beginning forfuture space flights.
Meet the authorDr. Lutz Kreutzer is manager of PR and market-ing at MVTec Software GmbH in Munich;email: [email protected].
Robotic Vision
The crew of Discovery during mission STS-133: seven humans and one robot astronaut. Courtesy of NASA.
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68 Photonics Spectra May 2012
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69Photonics Spectra May 2012
Lasers, Laser Accessories & Light Sources
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+32 16 38 99 [email protected]
Mid-IR Focusing Objectives
2 µm – 12 µm
• Diffraction-limited focal spot• ZnSe micro-aspheric• AR-AR in mid-IR• Easy alignment using HeNe• Standard RMS or 1-inch plate
In stock for immediate delivery
(973) [email protected]
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L-Mount Fiber-Coupled Diode Laser �A new version of its L-mount fiber-coupleddiode laser has been introduced by Limo Lissotschenko Mikrooptik GmbH. With 60 W ofpower, it delivers high output in a fiber diame-ter of 200 µm. Engineered for 976 and 981 nm,it is suited for pumping solid-state and fiberlasers. A filter protects the chip in the L-mountfrom destruction by reflected external beamsfrom a pumped laser system. The module also is available in a cladding mode-free version in which the light is directed within the core only and not in the fiber cladding. A volume holographic grating reduces the deviation of the laser beam from the set wavelength from 2 to <1 nm, increasing beam quality. The laser also is supplied as an open beam module (maximum power 70 W) that does not have a fiber connection but, instead, emits a rectangular beam of 10 � 5 mm via a window. Limo Lissotschenko Mikrooptik [email protected]
Polarized Multilaser Module Blue Sky Research’s SpectraTec dual-source polarized laser integrates a feedback system thatallows polarization-maintaining fiber to be usedwith better than 0.5% power stability at the exitend. Long-term precision and power stability areachieved via an integrated assembly of all-fibertechnology, power monitors and a low-noise electrical feedback control loop. The instrument is designed for applications that require multiplelaser wavelengths. The technology offers a collo-
cated light source, with no possibility of independent beam wandering over a wide tempera-ture range. Never needing alignment, the system incorporates two semiconductor lasers;permanent fiber coupling technology; electronics to operate, protect and stabilize the laser;and a single-mode or polarization-maintaining single-mode fiber. Wavelengths include violet, blue, green, red and infrared. The laser is temperature-stabilized with a thermoelec-tric cooler, and the integrated controller features a laser driver, output power stabilization,power level control, reverse and overvoltage protection, and fast transient and electrostaticdischarge suppression. Blue Sky [email protected]
Spectrometer �Ibsen Photonics has unveiled the Freedomspectrometer for OEM integrators of ana-lytical instruments. It combines compactsize and cost efficiency with flexibility inchoice of detector systems, and it deliversthe same robust and thermally stable performance as the company’s Rock spectrometers. Suitable for integration into handheld instruments, it measures 50 � 45 mm. Proprietary, in-house-pro-duced holographic transmission gratings provide a low stray light level and high efficiency. Optical resolution can be as good as 1 nm, and the f number (f/3.1) is among the best for ultracompact spectrometers on the market. The first Freedom product covers from 360 to 830 nm and supports several commonly used CCD, back-thinned CCD and N-type metal oxide semiconductor detectors.Ibsen [email protected]
� High-Speed Camera System Photron Inc. has launched the Fastcam SA7, a high-speed camera system that uses a 1280 � 1024-pixelCMOS imaging sensor. It operates at rates of up to 3500 fps at full resolution and provides high-quality images with 12-bit analog-to-digital conversion and high light sensitivity (5000 ISO monochrome, 2500 ISO color measured to the ISO standard 12232 Ssat (speed based on saturation) specification). It is designed for use in high-speed imaging applications, including automotive safety testing, and is supplied in a small and convenient-to-operate package. The Gigabit Ethernet network interface allows operation and control through industry-standard Photron Fastcam Viewer software.Photron [email protected]
Power over Ethernet Cameras To simplify machine visionapplications, including fac-tory floor automation andimaging systems, EdmundOptics has announced newPower over Ethernet (PoE)cameras. They include soft-ware that enables settingarea of interest, gain, exposure, white balance,frame rate, trigger delay,and digital output (flash)delay and duration. Theyalso can implement edgeenhancement, image mir-roring and binning, and hotpixel correction. The ultra-compact housing enables use in applications wherespace is at a premium. The cameras are powered by either a PoE injector, which requires two GigE cables, or a PoE computer card. They capture images in jpeg, bitmap or AVI formats and include drivers forDirect Show, ActiveX and TWAIN. Available in 1/1.8-, 1⁄2- and 1⁄3-in. sizes, they are offered in color and monochrome models. The PoE interface meets the IEEE 802.3af standard, and the cameras are CE-, RoHS- and GenICam-compliant. Edmund [email protected]
Sapphire DomesCustom-fabricated sap-phire domes for protect-ing electro-optical de-vices including detectors,sensors and cameras inweapons systems areavailable from MellerOptics Inc. They featureMoh 9 hardness, secondonly to diamond, andprovide 160° maximumincluded angles to ex-tend the viewing anglesand protect electro-
optics in the front of guided weapons. Providing up to85% transmission uncoated from the ultraviolet to theinfrared, with up to 99% when antireflection-coated on two sides, they can withstand harsh environments.Un-affected by chemicals, temperatures up to 1000 °C,and moving sand, dirt and water, the domes can bemanufactured in sizes of up to a 4-in. outer diameter.They can incorporate edge steps and profiles for mount-ing purposes and can be supplied with surface finishesto 20-10 scratch-dig per MIL-PRF-13830. Spinel domes(Moh 8 hardness) in sizes up to an outer diameter of 6 in. also are offered.Meller Optics [email protected]
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Grazing Incidence Spectrometer
With McPherson Inc.’s Model 248/310 grazingincidence spectrometer, users can make directoptical measurements, test soft XUV high-energy light sources (plasma or laser) and samples, and measure lifetime, persistence anddecay with continuous spectral scanning. A normal scan with a diode or channel-electronmultiplier-equipped instrument takes about 20 min. Users can resolve, discern, record and store spectra and spectral events in the 1- to 300-nm scanning range. Investigation ofspectral events in any wide- or narrow-rangesegment is programmable. Users can analyze a hollow cathode discharge, or other plasmaemission, for spectral content and decay withina preset scan range and can coordinate datacollection at specific wavelengths with soft- orhardware triggers. The company’s vacuum spectrometers are available in focal lengths of0.2 to ≥2 m and are suitable for high-vacuumapplications and equipped with all-metal sealsfor ultrahigh-vacuum operations. McPherson [email protected]
Coherent Photodetector A coherent photodetector that supports up to 64 Gbaud for next-generation networks using400-Gb/s or 1-Tb/s coherent detection-basedoptical transmission has been introduced by u2tPhotonics AG. The CPDV 1200R extends thecompany’s family of integrated coherent photo-detectors and receivers. It consists of a polariza-tion diversity network as well as two 90° hybrids
and four balanced photodiode pairs monolithi-cally integrated on InP. The optical front endwith four coaxial single-ended outputs and atypical bandwidth of 40 GHz can detect up to64-Gbaud polarization diversity x-QAM signalsfeaturing a high common-mode rejection ratioand interpolarization skew of <2 ps. The devicecan be used in next-generation long-haul trans-mission systems at data rates of 400 Gb/s andbeyond, and is suited for test and measurementapplications, and R&D. u2t Photonics [email protected]
USB 3.0 Cameras
Imaging Development Systems has introducedthe UI-3580CP-C industrial cameras with anAptina 5-megapixel CMOS sensor. The colorimager produces 2560 � 1920-pixel resolutionat 15 fps, and the UI-3480CP-M offers thesame detail and frame rate in a monochromesensor. The USB 3.0 interface delivers a datarate up to 400 MB/s. The high bandwidth en-ables multicamera systems and data-intensiveapplications. Because USB 3.0 is downward-compatible, existing USB 2.0 systems can still beused. Digital input/outputs include trigger, flashand pulse width modulation. Two general-pur-pose input/outputs are optically isolated andconnected via a Hirose connector. With a com-pact, lightweight magnesium housing, the cam-eras are suited for applications where space istight. The company offers a software package
for Microsoft Windows and Linux that includes32-/64-bit drivers, demo programs and sourcecode in C ++, C # and Virtual Basic. Imaging Development [email protected]
Excimer Laser for FBG Writing
The BraggStar M from Coherent Inc. is an excimer laser that delivers high pulse energyand spatial coherence for fiber Bragg grating(FBG) writing. High pulse energy is a critical ad-vantage in some FBG writing applications, andhigh spatial coherence is beneficial because itcreates FBGs with higher contrast and/or longerlength. Because it can be operated at repetitionrates of up to 100 Hz, the laser supports high-throughput production. It uses a coherence-enhanced optical design at 248 nm, resulting in higher spatial coherence compared with conventional, broad-use excimer lasers. Featur-ing a compact design and ease of operation, it is based on the COMPex platform. The lasercreates FBGs for reflectors in fiber lasers, refer-ence wavelength stabilization in wavelength division multiplexing telecommunications, andfiber sensing applications.Coherent [email protected]
All-Optical Switches Polatis Inc.’s Series 6000 nonblocking single-mode matrix all-optical switches offer up to 192 � 192 fiber ports and an average loss of
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PI USA is ITAR compliant and providescustom design and manufacturing atits MA, US-HQ. PI Global: 40 years ofexperience, 700+ employees, ISO 9001.
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<1 dB. The devices use proprietary DirectLighttechnology. The control electronics are designedwith carrier-class architecture and power-effi-cient devices. The switches combine a high portcount with rapid reconfiguration. All-opticalswitches have near-zero latency and are trans-parent to future data-rate upgrades. DirectLightuses piezoelectric actuation to steer the light directly between switch ports to obtain the bestoptical connection. Integrated position sensorson every fiber ensure patchcordlike transmissionindependent of the color, direction or powerlevel of light on the fiber. Applications includedefense, test and measurement, data center interconnects, high-definition video broadcastrouting and reconfigurable optical add-dropmultiplexers in telecom networks. Polatis [email protected]
Objective Lenses
Olympus Europa Holding GmbH has releasedits water-immersion MicroProbe Objectivelenses for studying the internal biology of livingorganisms. The 27� magnification IV-OB35F22W20 and the 20� IV-OB13F20W20 arehoused in tips with 3.5- and 1.3-mm diameters,respectively. They can be inserted into smallsurgical excisions, facilitating in vivo imagingwithout disrupting the tissue or organ, or intothe ear or through the body wall via keyholesurgery. They also can be positioned over smalltissues such as the cornea. Combined withpatch clamping, they can produce multifluores-cence images. Designed to work with laserscanning microscopes or multiphoton systems,they offer high IR transmission rates for multi-photon excitation experiments. The lenses aresuitable for intravital imaging because watercan mix with bodily fluids without hindering anexperiment, and extra water can be suppliedusing an aspiration/irrigation system that fitsonto the tip of the objective. Olympus Europa Holding [email protected]
VIS Bandpass FilterDelta Light & Optics’ LVVISBP visible linear vari-able bandpass filter’s spectral properties varylinearly along the long side. The position of the
center wavelength can be adjusted by slidingthe filter with respect to the incident light. Thisopens up new design possibilities for analyticaland diagnostic instruments such as spectrome-ters. By combining linear variable short- andlong-pass filters, bandpass filters can be tunedcontinuously with center wavelengths from320 to 850 nm, with tunable bandwidth. Theyoffer blocking levels better than OD 3 over thecomplete reflection range, or OD 5 when twofilters are placed in series. They are coated onsingle quartz substrates for minimal autofluores-cence and a high laser damage threshold. Theultrahard surface coatings offer high packingdensity and spectral stability with no drift, increased lifetime, mechanical stability and minimal water uptake. Delta Light & [email protected]
Microspectrometer
Avantes BV’s Avabench-RS configurable minia-ture spectrometer allows the user to change theslit and connector on the go. In the laboratoryor on the road, it takes only a screwdriver tocontinue measurements with a new setup. Themicrospectrometer adapts to changing needs,whether the user requires higher throughput orresolution. The proprietary ultralow stray lightoptical bench is the enabling technology for thisand is available on all Avantes UV/VIS/NIRAvaSpec spectrometers. The company says thatcustomers will get up to five times better straylight performance and good thermal and mechanical stability. The spectrometer includes a choice of 13 standard gratings and 10 detec-tor options. Avantes [email protected]
Radiation-Resistant Zoom Lens
Resolve Optics Ltd. has released a longer-focal-length version (24 to 144 mm) of its Model 290motorized radiation-resistant zoom lens. Pre-senting the same compact footprint as the stan-dard Model 290, the new 6� zoom lens allowsusers to get closer to the subject and rendersimages easier to read. The lens enables users toimage objects from 800 mm to infinity withoutthe need for add-on adapters. When focused at
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infinity, the lens achieves high image resolutionon-axis at full aperture throughout the zoomrange without refocusing (image tracking). Operating at f/1.8, the extended-range Model290 provides high image resolution and mini-mum geometric distortion from 400 to 750 nm.All optical elements in the nonbrowning zoomlenses are made using cerium-oxide-dopedglass or synthetic silica, enabling them to with-stand radiation exposure of up to 53 millionrads and temperatures up to 55 °C without discoloration. Resolve Optics [email protected]
IP67 Enclosures
Available in three standard sizes with a maxi-mum length of 250 mm, IP67 protective enclo-sures from autoVimation’s Orca series are suit-able for large cameras with a cross section ofup to 62 � 62 mm. Users can select the versionfor fish-eye or panamorph lenses with an imageangle of up to 200°. Enclosures for thermal imaging cameras featuring a 2- or 3-in. in-frared transparent germanium window areavailable, as are mounting brackets for blockand surveillance cameras. A patented quick lockand heat guide system thermally couples thecamera to the outer enclosure wall, and thepassive cooling effect of the wall reduces cam-era temperature. The 3-in. front window allowsuse of wide-angle and large telecentric lenses.Proprietary mounting kits for laser triangulationtasks allow users to quickly integrate the enclo-sures into 3-D applications. [email protected]
Widely Tunable 3.2-µm Laser Daylight Solutions Inc.’s TLS-41032 externalcavity laser offers >200 cm�1 of tenability, with wavelength coverage in the 3.25-µm (3080 cm�1) region of the mid-infrared spec-trum. Users can embed it into sensors targetedat industrial monitoring, process control,process analytical technology, environmentaland safety applications. The laser provides in-creased performance in spectral brightness, tuning range and power. The center wavelengthmatches the fundamental C-H stretching vibra-tional mode, enabling measurement of most hydrocarbons. The broad tuning range permits
analysis of multicomponent samples, whereblended absorption features or broad back-grounds can produce ambiguous results whenusing distributed feedback devices with limitedtuning ranges. The system enables new instru-ments in the petrochemical and environmentalindustries to detect and discriminate a widerange of molecules based upon their uniquespectral signatures at these wavelengths. Daylight Solutions [email protected]
Broadband Visible Light Source
Ocean Optics Inc.’s BluLoop, a compact LED-based light source, offers balanced spectral output across the visible (400 to 700 nm) range.When coupled to a miniature spectrometer, optical fibers and sampling accessories, it issuitable for color and reflectance measure-ments, and for general-purpose VIS-NIR spec-troscopy. BluLoop’s four LEDs are packaged in arugged, compact housing. Each LED is individu-ally tunable for optimum balancing of the spec-tral output. Unlike tungsten halogen sources,BluLoop produces “flatter” spectral output in the visible range for more predictable response, especially for color analysis. It provides a moreconstant spectral distribution and strongly re-duced instrumental stray light, and its poweroutput is comparable to that of standard tung-sten halogen sources.Ocean Optics [email protected]
Fluorescence Illumination System
Prior Scientific Inc. has released the newest ad-dition to its Lumen series fluorescence illumina-tion systems. The Lumen 200S has a robust in-ternal high-speed shutter and control options
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including RS-232, USB, transistor-transistor logicand a proprietary ProScan III controller shutterport. The system features a 2000-h lifetime anda 200-W metal arc lamp with a stabilized DCpower supply for consistent illumination. It offers a 2- or 3-m lightguide and an easy-to-view display screen for bulb life indication. Withquiet operation and a six-position adjustableaperture/intensity knob to protect samples fromphotobleaching, the 200S is suitable for labora-tory use. Adapters are available for all modernmicroscopes. Also available is the Lumen 220Smodel, which offers the same features alongwith an extended spectral output. Prior Scientific [email protected]
Optical Modulation Analyzer
For testing 40/100-G coherent transmitters andreceivers, Agilent Technologies Inc. has intro-duced the N4392A, a portable integrated opti-cal modulation analyzer with a laptop-sizescreen. It enables engineers to characterize in-phase quadrature modulators and integratedcoherent receivers. Performance verification and recalibration routines extend the recom-mended recalibration period, improving uptime.A 15-in. analysis screen shows more informa-tion simultaneously, making it easier for engi-neers to characterize complex modulated opticalsignals. The device offers four differential radio-frequency input channels for characterizing integrated coherent optical receivers. Signal-processing algorithms perform modulation- format-transparent polarization alignment andphase tracking, and the analyzers offer chro-matic dispersion and first-order polarizationmode-dispersion measurement and compensa-tion. The analyzers provide a defined interfaceto customer-developed MatLab algorithms. Agilent Technologies [email protected]
Low-Noise Microchannel Plates
Photonis USA Inc. has launched a long-life, low-noise (L3N) performance option for its micro-channel plate (MCP) product line. The companysays that the L3N option offers up to a hun-dredfold reduction in background noise whencompared with traditional MCPs. It is suitablefor applications where the background noise islower than the detector noise. Recent tests con-
firmed that, at 0.01 counts per second persquare centimeter, the L3N MCP dark countlevel approaches the background level of cosmic rays. Other applications include low-level imaging and high-energy physics research. The L3N option also is available on any of thecompany’s products that contain MCPs, includ-ing specialty Stripline MCPs and time-of-flightdetectors. Photonis USA [email protected]
UV/Si Calibrated Photodetectors
Newport Corp. has released two wand photo-detectors, the 818-ST2 and 818-ST2-UV. Theyoperate from 200 to 1100 nm, and metal casessafeguard the optics in the setup, especially inthe UV wavelength range, keeping the housingand attenuator glue protected from high heatdamage. The 818-ST2 incorporates a 10 � 10-mm silicon photodiode. The slender wand de-sign is suitable for detection and measurementin tight or confined spaces, and a mountinghole on the side makes it easy to install withoutthe need for angle brackets. Power levels arefrom picowatts to 2 W, with a built-in calibratedOD3 attenuator that has an easily readable and accessible on/off indicator. The DB15 cali-bration module is detachable from the BNCconnector, permitting interface with the com-pany’s power meters. The photodetectors alsoare compatible with oscilloscopes and currentmeters. Newport [email protected]
Improved Four-Axis Precision Mount
Pinpoint Laser Systems’ improved precisionmount for the Microgage laser line is lighterand provides finer accuracy and control. Itmoves the laser in four axes: vertical and hori-zontal, and pitch and yaw. The laser beam canbe positioned to within 0.001 in. and is suitablefor checking machinery travel, precision borealignment and the straightness of fixtures andassemblies. Two micrometers adjust the eleva-tion of the laser up and down, and its positionleft and right. Another pair of adjustments pro-vides angular control of pitch and yaw. The
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mount is attached to a tripod or bolted to a machine, enabling tight laser positioning con-trol over distances of 150 ft. It is used for check-ing machinery parallelism, squareness, flatnessand bore alignment. Made from solid aluminumand protected by a hard anodized coating, it isassembled with roller-bearing slides and stain-less steel hardware.Pinpoint Laser [email protected]
Scalable Matrix Optical Switch
SA Photonics has introduced the Cosmos com-pact scalable matrix all-optical switch for space-based-communications networks. It provides thefoundation for networks within and betweensatellites, enabling higher bandwidth and lowercrosstalk than are possible with radio-frequencycommunication. It has minimal power require-ments, a modular architecture that integratesinto any modern satellite, and a design thatwithstands the extreme temperatures and radia-tion that satellites encounter in space. It uses a solid-state switching mechanism made fromintegrated off-the-shelf components, resulting in low insertion loss, zero drift over years of operation, zero power switch latching and simple integration into communications subsys-tems. Average switch speed is 15 ms, and average insertion loss is 1 dB. SA [email protected]
LED Technology
Z-Laser Optoelektronik GmbH now offers customized OEM Moodlight LEDs for industriesincluding medical technology and architecture.An important aspect of the color surfaces is thesmall building depth, starting from 4 mm. Thescratch-proof polymethyl methacrylate is ren-dered resistant to chemicals by a special proce-dure. Free selectable optical possibilities, includ-
ing transparency and opaque glass effect in desired gradation and/or opacity, open up anumber of possibilities for product design. Thecompany calls the color-changing LED surfaceseye-catching. Depending upon the requirement,various control profiles can be called up, e.g.,for impressive lighting in a single strong color or for rotating straight through the entire colorpalette. Z-Laser Optoelektronik [email protected]
Fiber Optic Simulator
A compact fiber optic network simulator thatcan be customized to emulate a physical net-work in the laboratory with reliability and re-peatability is available from M2 Optics Inc. TheFiber Lab 3200 is a 19-in. rack-mounted opticalfiber management package that can be cus-tomized with virtually any fiber type or mix, in-cluding lengths, splices and connectors, to pre-cisely match a physical network’s specifications.Able to simulate an optical network to 120 km,it eliminates fiber and connector damage andyields repeatable results. Built to customer re-quirements, the simulator holds up to fourlengths and lets network developers emulate aphysical network in their laboratories to ensurethat the systems will work as intended when deployed in the field. Applications include prod-uct development and certification, long-distancenetwork simulation, latency and delay testing,and training.M2 Optics [email protected]
Pitch-Reducing Optical Fiber Array The PROFA (pitch-reducing optical fiber array)product line is an evolution of Chiral PhotonicsInc.’s spot size converting interconnects, whichinterface standard optical fibers with photonicintegrated circuits. The multichannel 2-D densefiber array is suited for vertical interfacing tovertical-cavity surface-emitting lasers, receiversor vertically coupled gratings. A monolithic glass structure incorporating an adiabatic taperand integrated pigtails brings multiple opticalchannels close together for efficient and space-saving coupling. The technology reduces chan-nel pitch while tailoring the numerical apertureof individual channels to customer needs. The company is offering a 50-plus-channel device with single-mode waveguides in the visible spectral range, with channel spacing of <40 µm. Chiral Photonics [email protected]
Forensic Glass Analyzer Craic Technologies Inc. and Laboratory Imagingsro have launched the rIQ (refractive index
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quantification) for analyzing glass trace evi-dence. The automated system combines imageanalysis software, an advanced optical designand electronics to enable criminalists in forensiclaboratories to measure the refractive index ofmultiple glass fragments simultaneously andquickly. When combined with Craic’s micro-scope spectrophotometers and microcolori-meters, it determines transmission and fluores-cence spectral characteristics of glass. The sys-tem uses the thermal immersion method tomeasure the refractive index of microscopicglass fragments. The stand-alone package consists of a phase contrast microscope, a digital camera, the optical interface, a thermalstage, controlling electronics and software. The add-on package can be integrated withCraic microspectrophotometers to determine the color, absorbance microspectra, fluores-cence microspectra and refractive index of smallglass fragments. Craic Technologies [email protected]
ZnS Optics for Mid-IR LasersREO Inc. has released mid-infrared optics with a high laser damage threshold, environ-mental stability and mechanical durability. Thezinc sulfide (ZnS) components are used with Ho:YAG-pumped optical parametric oscillatorsand other laser systems operating in the 2- to5-µm range. The ZnS substrates are precision-
ground and -polished, then coated using ionbeam sputtering, yielding densified thin filmsthat are impervious to water absorption. Appli-cations include IR countermeasures, laser desig-nating/rangefinding, atmospheric sensing andsmall-molecule spectroscopy. The series in-cludes flat and radiused components with 5- to 150-mm-diameter substrates. All feature sur-face accuracy of �/10 at 632.8 nm and 20-10surface quality, and are offered with antireflec-tion, high-reflection and multispectral coatings.The laser damage threshold of the antireflectionbands is >8 J/cm2 at 2.05 µm in a 75-ns pulse,while high reflection bands produce damage resistance of >50 J/cm2 for the same pulsespecifications. REO [email protected]
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Vision Sensor
The IV Vision Sensor from Keyence Corp. ofAmerica combines the functions of machine vision and traditional sensors. Setup takes 1 min using the Navigator software. The sensoraccommodates presence-detection applicationsthat previously required multiple conventionalor proximity sensors. Equipment includes high-intensity illumination, lenses and eight sensorheads to produce sharp and stable images. TheIV camera selection includes close-, medium-and long-range models. The sensor complieswith the IP67 enclosure rating based on IEC/JISstandards. It has applications in the semicon-
ductor, electrical, electronics, automotive, food,pharmaceutical and manufacturing industries.Features include automatic focus, automaticone-touch brightness adjustment, a quad lens,output adjustment, remote operation, a statisticsfunction and a pattern tool. The autotuningfunction enables optimization of threshold andparameters. Illumination accessories and utili-ties include dome lights, a high-speed/high-dynamic-range function and polarizing filters to eliminate glare. Keyence Corp. of [email protected]
Diamond ATR ProbeAxiom Analytical Inc. has announced its DMD-270Fx, a flexibly coupled diamond ATR (attenu-ated total reflectance) probe for use in mid-IRspectroscopy. It uses hollow flexible lightguidesto provide coupling to a Fourier transform in-frared spectrometer, providing flexibility withoutthe drawbacks of solid-core mid-infrared opticalfibers. In contrast to the solid-core mid-IR fibers,the hollow polymer lightguides provide full-fingerprint-region spectral coverage combinedwith stability and durability. Extreme chemicalresistance is ensured by the use of a diamondATR element, Hastelloy construction and ener-gized polytetrafluoroethylene seals. The probe is used in applications ranging from chemicaland pharmaceutical research to incoming in-spection of raw materials and online process
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analysis. It features broad mid-IR spectral response, providing detailedquantitative analysis based on specific chemical functional groups. Axiom Analytical [email protected]
4-Megapixel CameraOptronis GmbH’s CL4000CXP is a 4-megapixel camera with a high-speedCoaXPress interface upgraded with the GenICam standard. The camerahas four CoaXPress channels and can transfer 25 Gb/s across a parallelconnection, allowing 500 images to be received per second in real time onthe connected PC. It is suitable for real-time applications in 2- and 3-Dsurface analysis. The company supplies interfaces for frame grabbers pro-duced by leading manufacturers, providing configuration tools that make iteasier to integrate the camera and that enable semiautomated configura-tion. Supported by the development environment provided by the frame-grabber manufacturer, customers are offered a professional solution forevaluating optical data easily. The camera performs simple image process-ing in industrial applications and produces traceable and precise data. Optronis [email protected]
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b ANOTHER BRIGHT IDEAAdvertise your new product in Photonics Showcase or in theSpotlight section of Photonics Spectra.
Reach all of our readers in these low-cost, lead-generating features.
Call Kristina Laurin at (413) 499-0514, or [email protected].
512 Bright Ideas_Layout 1 4/20/12 11:59 AM Page 78
JUNEDisplay Week 2012 (June 3-8) Boston. Contact Society for Information Display, +1 (408) 879-3901; [email protected];www.sid.org.
Principles of Fluorescence TechniquesCourse (June 4-6) Urbana, Ill. Contact
Samantha Redes, +1 (217) 359-8681; [email protected];www.fluorescence-foundation.org.
Laser Welding: Equipment and Process Validation (June 4-7) Madison, Wis. ContactElaine M. Bower, College of Engineering, University of Wisconsin-Madison, +1 (800)
462-0876; [email protected]; epd.engr.wisc.edu/laserprocess.
Laser Safety Officer Training Course (June 5-8) San Diego. Contact Rockwell Laser Industries, +1 (513) 272-9900; [email protected]; www.rli.com.
3D Microscopy of Living Cells Course (June 9-21) and 3D Image Processing Postcourse Workshop (June 23-25)Vancouver, British Columbia, Canada. Contact James Pawley, University of Wisconsin-Madison, +1 (608) 238-3953; [email protected]; ww.3dcourse.ubc.ca/2012.
QIRT 2012: 11th Quantitative InfraredThermography Conference (June 11-14)Naples, Italy. Contact Secretariat, +39 0817685 184; [email protected]; www.qirt2012.unina.it.
Advanced High Power Lasers 2012 (June 11-15) Broomfield, Colo. Contact Cynnamon Spain, Directed Energy ProfessionalSociety, +1 (505) 998-4910; [email protected]; www.deps.org.
Lasys 2012: International Trade Fair for System Solutions in Laser Material Processing (June 12-14) Stuttgart, Germany.
HAPPENINGS
79Photonics Spectra May 2012
PAPERSJSAP-OSA Joint Symposia (September 11-14) Matsuyama, JapanDeadline: paper submission, June 1, 17:00 JSTPapers are invited for the 73rd Japan Society of Applied Physics Autumn Meeting 2012. Topics include optoelectronics, nanocarbon photonics, plasmonics, biophotonics, medical photonics, photonic crystals and fiber optics, and optical microsensing, manipulation and fabrication. Contact JSAP, +81 3 5802 0864; [email protected]; www.jsap.or.jp/english.
Renewable Energy and the Environment (November 11-15) Eindhoven, NetherlandsDeadline: abstracts, July 8, 12:00 EDT; 16:00 GMTPapers are encouraged for this OSA Optics & Photonics Congress, encompassing Optical Instrumenta-tion for Energy and Environmental Applications (E2); Optical Nanostructures and Advanced Materialsfor Photovoltaics (PV); Optics for Solar Energy (SOLAR); and Solid State and Organic Lighting (SOLED).Contact OSA, +1 (202) 223-8130; [email protected]; www.osa.org.
Laser Florence 2012 (November 9-10) Florence, ItalyDeadline: abstracts, July 30The IALMS (International Academy for Laser Medicine and Surgery) invites papers for its annual con-gress, addressing advantages, limitations and controversies associated with laser use on the humanbody for diagnosis, therapy and surgery. Topics will include laser biomodulation, laser biomedicine,laser therapy for central nervous system injuries, and lasers in dentistry, dermatology and the treat-ment of diabetes. Contact IALMS, +39 055 234 2330; [email protected]; www.laserflorence.org.
Come and see us at OPATEC show, May 22-25, Hall 3, Booth F45
512Happenings_Layout 1 4/20/12 11:55 AM Page 79
Contact Meike Mayer, +49 711 18560, Ext. 2374; [email protected];www.messe-stuttgart.de.
EuroLED 2012 (June 13-14) Birmingham, UK.Contact Michelle Cleaver, +44 121 250 3515;[email protected]; www.euroled.org.uk.
Third EOS Topical Meeting on TerahertzScience and Technology (TST 2012) (June17-20) Prague, Czech Republic. A EuropeanOptical Society Event. Contact Silke Kramprich,EOS – Events and Services GmbH, +49 511277 2674; [email protected]; www.myeos.org/events/tst2012.
Advanced Photonics Congress (June 17-21) Colorado Springs, Colo. IncludesAccess Networks and In-house Communica-tions; Bragg Gratings, Photosensitivity and Poling in Glass Waveguides; Integrated Photon-ics Research, Silicon and Nano-Photonics; Photonic Metamaterials and Plasmonics; Nonlinear Photonics; Specialty Optical Fibersand Applications; and Signal Processing in Photonic Communications. Contact Optical Society of America, +1 (202) 223-8130;[email protected]; www.osa.org.
TechConnect World 2012 (June 18-21)Santa Clara, Calif. Contact Sarah Wenning, +1 (925) 353-5004; [email protected]; www.techconnectworld.com.
BIO International Convention (June 18-21)Boston. Contact Biotechnology Industry Organization, +1 (202) 962-9200;[email protected]; www.convention.bio.org.
Third International Congress on Biophotonics (ICOB 2012) (June 19-21)Jena, Germany. Contact Clemens Homann,+49 3641 206 064; [email protected]; www.myeos.org/events/icob2012.
Imaging and Applied Optics: OSA Opticsand Photonics Congress (June 24-28)Monterey, Calif. Includes Applied Industrial Optics: Spectroscopy, Imaging and Metrology;Computational Optical Imaging and Sensing;Imaging Systems Applications; Optical Fabrica-tion and Testing; Optical Remote Sensing of theEnvironment; and Optical Sensors. Contact Optical Society of America, +1 (202) 223-8130;[email protected]; www.osa.org.
International Workshop on Laser-MatterInteraction (WLMI-2012) (June 25-29)Porquerolles, France. Contact Luc Bergé, CEAFrance, [email protected]; www.pks.mpg.de/~wlmi12.
Ninth International Symposium on DisplayHolography (ISDH 2012) (June 25-29)Cambridge, Mass. Contact MIT Media Lab,[email protected]; isdh2012.media.mit.edu.
10th International Conference on Vibration Measurements by Laser and Noncontact Techniques and Short Course (June 26-29) Ancona, Italy.Contact Janet L. Dubbini, AIVELA (Italian Association of Laser Velocimetry and Non-invasive Diagnostics), +39 071 220 4489;[email protected]; www.aivela.org.
JULY2012 Astronomical Telescopes + Instrumentation (July 1-6) Amsterdam. Contact SPIE, +1 (360) 676-3290; [email protected]; www.spie.org.
Sixth International Meeting on Developments in Materials, Processes and Applications of Emerging Technologies(MPA) (July 2-4) Alvor, Portugal. Contact MPATech, +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.
80
h HAPPENINGS
Photonics Spectra May 2012
For complete listings, visit
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aaADVERTISER INDEX
81Photonics Spectra May 2012
Photonics Media Advertising Contacts
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Aero Research Associates Inc. ....................72www.aerorese.com
Aerotech Inc. .........................53www.aerotech.com
Andor Technology .................68www.andor.com
Applied Scientific Instrumentation ....................28www.asiimaging.com
Argyle International ...............34www.argyleoptics.com
Aston Science Park ................59www.euroled.org
Avantes .................................24www.avantes.com
B&W Tek ................................7www.bwtek.com
Bristol Instruments Inc. ......48, 69www.bristol-inst.com
Castech Inc. ...........................74www.castech.com
China International Optoelectronic Exposition ....64www.cioe.cn
Coherent Inc. ...................15, 27www.coherent.com
ConOptics Inc. .......................68www.conoptics.com
CVI Melles Griot ..............18, 32www.cvimellesgriot.com
Directed Energy Inc. ...............23www.ixyscolorado.com
Edmund Optics ......................13www.edmundoptics.com
89 North ...............................69www.89north.com
Electro-Optical Products Corp. ....................42www.eopc.com
EMD Millipore Corporation ........................21www.emd4photonics.com
Energetiq Technology Inc. ...................12www.energetiq.com
Exciton Inc. ............................68www.exciton.com
FLIR Systems Inc. ....................36www.flir.com
Gooch & Housego .................77www.goochandhousego.com
Hellma USA ..........................28www.hellmausa.com
Horiba Scientific ....................73www.picocomponents.com
ILX Lightwave Corp. ...............29www.ilxlightwave.com
Image Science Ltd. .................76www.image-science.co.uk
Incom Inc. .............................35www.incomusa.com
Innovation Photonics ..............69www.innpho.com
Jenoptik Optical Systems ..................11www.jenoptik.com
Julabo USA Inc. .....................69www.julabo.com
Laser Institute of America ...................54, 78www.icaleo.org
Lightmachinery Inc. ..........22, 34www.lightmachinery.com
Market Tech ..........................68www.markettechinc.net
Martek Power Laser Drive LLC ............................43www.laserdrive.com
Master Bond Inc. ...................52www.masterbond.com
Mercron Inc. ..........................14www.mercron.com
Mightex Systems ....................80www.mightexsystems.com
Newport Corporation ....................6, 20www.newport.com
Novotech Inc. ........................52www.novotech.net
Nufern ..................................33www.nufern.com
Ocean Optics ..........................9www.oceanoptics.com
OPCO Laboratory Inc. ....................46www.opcolab.com
The Optical Society of America ..........................58www.osa.org/meetings
Photonics Media ..............40, 80www.photonics.com
PI (Physik Instrumente) L.P. .......71www.pi.ws
Pico Electronics Inc. ................77www.picoelectronics.com
PIDA .....................................67www.optotaiwan.com
Piezosystem Jena GmbH ........................79www.piezojena.com
Polymicro Technologies, a Subsidiary of Molex .........19www.polymicro.com
Qioptiq Inc. ........................CV2www.qioptiq.com
Research Electro-Optics .....................49www.reoinc.com
Satisloh .................................25www.satisloh.com
Scanlab AG ............................8www.scanlab.de
SEMI .....................................55www.semiconwest.org
Sill Optics GmbH ...................66www.silloptics.de
Siskiyou Corporation ........................62www.siskiyou.com
Society for Information Display ...............................63www.displayweek.org
Spectra-Physics, A Newport Corporation Brand ............CV4www.newport.com
Spectrogon US Inc. ...............................79www.spectrogon.com
Stanford Research Systems Inc. ..........................3www.thinksrs.com
StellarNet Inc. ........................38www.stellarnet-inc.com
Swift Glass Co. Inc. ..............................78www.swiftglass.com
Sydor Optics Inc. ...................76www.sydor.com
Terahertz Technologies Inc. .................68www.terahertztechnologies.com
Tohkai Sangyo Co. Ltd. ..................22www.peak.co.jp
Toptica Photonics Inc .................31, 75www.toptica.com
TRIOPTICS GmbH ..................26www.trioptics.com
Trumpf Inc. ............................37www.us.trumpf.com
Xenics NV .............................69www.xenics.com
Zygo Corp. .........................CV3www.zygo.com
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p PEREGRINATIONS
Alexander Graham Bell, we can hear you now
L inguists, historians and even musi-cians could benefit from noninvasiveoptical scanning technology that
enables us to hear voices and sounds thatwere recorded more than a century ago.
Unlocking these sounds is part of a collaborative sound recovery project in-volving scientists at Lawrence BerkeleyNational Laboratory (LBNL) in Californiaand curators at the Library of Congressand the Smithsonian Institution, both inWashington. The team has tested theprocess on six recordings using imagingequipment installed by LBNL at the Li-brary of Congress.
Using a digital scan made from one ofthe very earliest sound recordings, thegroup got to hear a male voice recorded in the 1880s. Originally recorded on aglass disc with a beam of light, the voiceoriginates from early experiments in soundrecording conducted in Washington byVolta Laboratory Associates – inventorsAlexander Graham Bell, Chichester Belland Charles Sumner Tainter.
Until recently, this historical record-ing has remained silent in storage at theSmithsonian Institution. Many other earlysound recordings could be brought back to life with the new technology as well,including those of musical artists, poetsand writers; extinct Native American languages also could be revived.
The sound often is inaccessible becauseof the fragile, damaged, varied or obsoletetechnology in which it is embedded. Thescanning method preserves the originalhardware and essentially repairs some ofthe existing damage.
“These recordings were made using avariety of methods and materials such asrubber, beeswax, glass, tinfoil and brass,as the inventors tried to find a materialthat would hold sound,” said CarleneStephens, curator at the Smithsonian’s National Museum of American History.“We don’t know what is recorded, exceptfor a few cryptic inscriptions on some ofthe discs and cylinders, or vague notes onold catalog cards written by a Smithsoniancurator decades ago.”
The first 90 years of sound recordingare dominated by mechanical carriers,some in cylinder form, where the groovevaries in depth, and some in disc form,where the stylus moves from side to side
in the spiral groove, according to a recentreport by Carl Haber, a scientist at LBNL.
The optical technique creates a high-resolution digital map of the disc or cylin-der. The digital version is then processedto remove scratches or skips that mayhave appeared on the original recording.Software then calculates the motion of astylus moving through the grooves of thedisc or cylinder, reproducing the audiocontent and producing a standard digitalsound file.
Two-dimensional imaging using a line-scan camera is suitable for a disc with a lateral groove, and 3-D imagingusing a confocal scanning probe is re-quired for a cylinder with vertical groovemodulation, Haber reported.
82 Photonics Spectra May 2012
Caren B. [email protected]
This electrotyped copper negative disc of a soundrecording was deposited at the Smithsonian Institution in 1881 in a sealed tin box. It contains a tone, a male voice counting numbers, and then two more tones.
Participants in a sound recovery project, Carlene Stephens and Shari Stout, curators at the National Museum of American History, handle an early glass disc record. Images courtesy of National Museum of American History, Smithsonian Institution.
Hear for yourselfTo listen to the early sound recordings,visit the Volta Labs Recordings channel on YouTube, provided by the Smithsonian Institution’s NationalMuseum of American History:http://tinyurl.com/cp8ooxt.
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