Sony says Uncharted 4 copies stolen; Issues 'spoiler alert'
Dead body found in Apple's Cupertino HQ
Infosys invests in Trifacta
Encryption: Good or bad, the debate continues
Infosys announce partnership with KUKA Aktiengesellschaft
Meizu to launch M3 Note in India on May 11
Microsoft not ready to give up on Windows 10 Mobile yet
Slow networks hurting Apple growth in India: CEO Tim Cook
Apple says witnessing strong demand for iPhone SE
The nanostructured materials known as Type-II indium arsenide/gallium antimonide/aluminum antimonide (InAs/GaSb/AlSb) superlattices have been around since the 1970s and have served in infrared detection applications since the late 1980s. Since then, Type-II Sb-based superlattice materials have evolved drastically with many variants suited for different applications.
Now researchers at Northwestern University, led by Manijeh Razeghi, have developed a new superlattice design, called M-structure superlattice. It can be used to make devices that operate as a shortwave/mid-wave/long-wave infrared photodetector. Shortwave infrared wave (SWIR) bands make it possible to detect reflected light. Mid-wave detection picks up hot plumes and long-wave infrared detects cooler objects.
The researchers claim that a device designed around this new material can detect any of these infrared wavebands by simply adjusting the applied bias voltage. In terms of actual applications, the researchers claim this device could make possible infrared color televisions and three-color infrared imaging.
In research described in the Nature journal Scientific Reports, the researchers produced this superlattice by alternating the InAs, GaSb, and AlSb layers (with thicknesses of a few angstroms to a few nanometers) over several periods. The result is a one-dimensional periodic structure like that of the periodic atomic chain in naturally occurring crystals.
"The beauty of Type-II superlattice is the gap engineering capability which allows us to artificially manipulate and create novel 'materials' like the way natural semiconductors are created," said Razeghi in an e-mail interview with IEEE Spectrum.
There are currently only a few material systems that are suitable for multi-spectral detection, according to Razeghi. The current state-of-the-art, mercury cadmium telluride (HgCdTe) and quantum well infrared photodetectors (QWIPs), are commercially available for infrared dual-band detection. However, mercury cadmium telluride technology is expensive and hard to make, while quantum well detectors suffer from low quantum efficiency and require low operating temperatures.
"In that context, Type-II InAs/GaSb/AlSb superlattices have proved to be an excellent alternative," says Razeghi. "Controlling the electronic structure by managing the layer thicknesses as they are grown on GaSb substrate [yields] superlattices with the capability of tuning from SWIR to very-long wavelength infrared (VLWIR), covering the whole infrared spectrum."
Despite the immense promise of the M-structure superlattices, this developing new material system has been the focus of considerably less development than II-VI based mercury cadmium telluride photodetectors, according to Razeghi.
"The current state-of-the-art in infrared detection technology is still based on HgCdTe, and relatively little effort has been expended developing dual- and triple-band T2SL based focal plane arrays (FPAs)," Razeghi told Spectrum. "There is a unique opportunity to mature this material system and realize a new generation of dual- and triple-band FPA sensors."
However, Razeghi concedes that, responsivity, which dictates how sensitive a photodetector is, and the dark current, which is related to the noise, must be further improved. This means the optimization of many parameters, including device design, material growth, and all of the processing steps, must result in high reproducibility and high yield.
"We need to reduce the bias dependency of the long-wavelength channel to a reasonable range so that it could be compatible with the currently available readout integrated circuit," says Razeghi.
The next step in the research, she says, will be to fabricate a three-color infrared camera. She added: "Our long term goal is to improve both electrical and optical performance of the detectors in order to make cheap high-performance infrared cameras for different applications."
In ancient times, scribes churned out documents — love poems, prayers, lawsuits — for clients who were illiterate or too busy to write. Although reams of the texts survive on papyrus, bark and parchment, the ingredients of the inks remain a mystery. Scientists, archaeologists, curators, historians and conservators are collaborating on testing these writings and crumbs of ancient pigments to unlock the ink recipes.
At the Metropolitan Museum of Art, the conservator Yana van Dyke has been creating experimental inks from plant extracts, including oak galls, or swollen tissue on oak trees infested by wasps, to compare with those used on manuscripts. Hilary Becker, an assistant classics professor at the University of Mississippi who plans to join the faculty at Binghamton University in New York this f all, is completing a book titled "Commerce in Color," about the ancient Roman pigment trade.
The Ancient Ink Laboratory, a collaboration between Columbia University and New York University, is using nondestructive techniques like micro Raman spectroscopy, microscopy and infrared photography to scrutinize inks on documents. The lab is also studying fermentation residues from winemaking that may have gone into ancient ink mixtures and crusts found inside ancient inkwells at the University of Michigan's Kelsey Museum of Archaeology.
In poring over Roman texts, Ms. Becker has found references to indelible and invisible inks on the market, some of them highly valued, and complaints about adulterated ingredients and poor quality. In the fifth century, Roman law mandated that only emperors could write with prized purple ink made from charred seashells, for example. Anyone else who obtained this expensive dye would face the death penalty.
David Ratzan, the head librarian at N.Y.U.'s Institute for the Study of the Ancient World, said that no one is certain how soot and other charred ingredients in black inks were made and harvested. Pliny the Elder mentions that the "best kind" of black pigment "is adulterated with the soot from furnaces and baths, which is used for writing."
All this new scholarship could be useful for experts authenticating manuscripts and for conservators trying to stabilize documents damaged by corrosive inks. Extracts in the formulas may also indicate where tree species once flourished and help identify the trade routes for ink products.
"It's all part of a puzzle," Ms. van Dyke said.
A Connecticut IdyllFrom the 1880s to the 1910s, the painter J. Alden Weir vacationed with fellow intellectuals in a sleepy corner of eastern Connecticut. At his home there in Windham, he sketched meadows bordered by picturesquely sagging fences and encroaching railroad lines and textile mills; his visitors included John Singer Sargent and Childe Hassam. Anne E. Dawson, an art history professor at Eastern Connecticut State University, has spent seven years tracking down documents and artworks for "A Good Summer's Work: J. Alden Weir, Connecticut Impressionist," opening on Saturday at the Lyman Allyn Art Museum in New London, Conn., and a book, "Rare Light: J. Alden Weir in Windham, Connecticut, 1882-1919," from Wesleyan University Press.
The Windham artists' colony has largely been forgotten, unlike some of its counterparts along the Connecticut coast and in the New York suburbs. Mr. Weir's other family home, in Wilton, Conn., is now the Weir Farm National Historic Site, and studio spaces there are still stocked with brushes, palettes and paints. In Windham, he worked in a converted shoe factory that has since been demolished; its weeded-over remains are not far from the Weir family's graves. His paintings of the area have often been mislabeled as scenes of the countryside around Wilton.
Ms. Dawson analyzed Mr. Weir's correspondence as well as family inventories. The artist sometimes adapted his natural surroundings in Windham to improve his compositions on canvas, shifting hill contours and adding hollyhocks and other plants. He called the technique "hollyhocking."
On May 20 and 21, Boyd Auctions in Portsmouth, N.H., will offer antiques passed down to Mr. Weir's descendants, including art supplies, paintings, letters and family photographs. Ms. Dawson said that she would document the material before it is dispersed.
Photo A glass facsimile of a sea creature known as Comatula mediterranea, made in Dresden, Germany, in 1885 by the glassmakers Leopold and Rudolf Blaschka. Credit Corning Museum of Glass Sea Creatures in GlassLeopold and Rudolf Blaschka, a father-and-son team of Bohemian-born glassmakers based in Dresden, Germany, were known for bending wisps of glass into detailed models of flowers and marine life. In the late 1800s they supplied displays for schools, museums and aquariums while also making prosthetic glass eyes and lab equipment for export. After a few decades on view, the botanical and zoological pieces were often considered outdated; countless items ended up in storerooms, their petals shattered and tentacles snapped.
In recent months experts have been restoring the Blaschkas' glass minutiae in preparation for "Fragile Legacy: The Marine Invertebrate Glass Models of Leopold and Rudolf Blaschka," an exhibition opening on May 14 at the Corning Museum of Glass in Corning, N. Y. It will explore the Blaschkas' methods of reinforcing models with wires and glue, the their shipping crates and the surviving glass creations worldwide. Videos will show conservators repairing the antiques, many of which belong to Cornell University.
The curator of the Cornell holdings, Drew Harvell, a marine biologist, researched the contemporary fates of the creatures that were immortalized in glass for her recent climate-change-related book, "A Sea of Glass: Searching for the Blaschkas' Fragile Legacy in an Ocean at Risk" (University of California Press). She collaborated with the filmmaker David O. Brown on a documentary about the subject, "Fragile Legacy," and the team's footage of marine life depicted by the Blaschkas will be screened at the Corning Museum.
An exhibition of the photo grapher Guido Mocafico's close-ups of Blaschka sculptures runs through May 24 at Hamiltons Gallery in London. Harvard's Blaschka collections are the subject of a book due this fall, "Sea Creatures in Glass: The Blaschka Marine Animals at Harvard" (Harvard Museums/Scala), and a renovated display that reopens there on May 21.
Continue reading the main storyOZ Minerals says a $150 million copper concentrate treatment plant at Whyalla in regional South Australia could create about 100 jobs during two years of construction and 100 ongoing jobs once it is operational.
The Adelaide-based resources company has applied to the South Australian Government for major project status, which can fast-track approvals.
OZ Minerals also has signed a non-binding memorandum of understanding with steelmaker Arrium to share its port and other facilities at Whyalla.
OZ Minerals chief executive Andrew Cole told shareholders the company's studies showed that building a standalone processing facility near a port was a better option than building one at its mine site.
"We get cheaper access to rail, to port, to roads, to power, to water, gas and oxygen plants and of course we have a much wider pool of people to draw on," he said.
Whyalla has been facing uncertainty about the future for many local jobs since Arrium, its biggest employer, went into administration a month ago.
OZ Minerals, formed when Oxiana and Zinifex merged in 2008, has two major copper assets in South Australia, the Carrapateena project near Port Augusta and Prominent Hill near Coober Pedy, from which it shed 100 workers earlier in the year.
The nanostructured materials known as Type-II indium arsenide/gallium antimonide/aluminum antimonide (InAs/GaSb/AlSb) superlattices have been around since the 1970s and have served in infrared detection applications since the late 1980s. Since then, Type-II Sb-based superlattice materials have evolved drastically with many variants suited for different applications.
Now researchers at Northwestern University, led by Manijeh Razeghi, have developed a new superlattice design, called M-structure superlattice. It can be used to make devices that operate as a shortwave/mid-wave/long-wave infrared photodetector. Shortwave infrared wave (SWIR) bands make it possible to detect reflected light. Mid-wave detection picks up hot plumes and long-wave infrared detects cooler objects.
The researchers claim that a device designed around this new material can detect any of these infrared wavebands by simply adjusting the applied bias voltage. In terms of actual applications, the researchers claim this device could make possible infrared color televisions and three-color infrared imaging.
In research described in the Nature journal Scientific Reports, the researchers produced this superlattice by alternating the InAs, GaSb, and AlSb layers (with thicknesses of a few angstroms to a few nanometers) over several periods. The result is a one-dimensional periodic structure like that of the periodic atomic chain in naturally occurring crystals.
"The beauty of Type-II superlattice is the gap engineering capability which allows us to artificially manipulate and create novel 'materials' like the way natural semiconductors are created," said Razeghi in an e-mail interview with IEEE Spectrum.
There are currently only a few material systems that are suitable for multi-spectral detection, according to Razeghi. The current state-of-the-art, mercury cadmium telluride (HgCdTe) and quantum well infrared photodetectors (QWIPs), are commercially available for infrared dual-band detection. However, mercury cadmium telluride technology is expensive and hard to make, while quantum well detectors suffer from low quantum efficiency and require low operating temperatures.
"In that context, Type-II InAs/GaSb/AlSb superlattices have proved to be an excellent alternative," says Razeghi. "Controlling the electronic structure by managing the layer thicknesses as they are grown on GaSb substrate [yields] superlattices with the capability of tuning from SWIR to very-long wavelength infrared (VLWIR), covering the whole infrared spectrum."
Despite the immense promise of the M-structure superlattices, this developing new material system has been the focus of considerably less development than II-VI based mercury cadmium telluride photodetectors, according to Razeghi.
"The current state-of-the-art in infrared detection technology is still based on HgCdTe, and relatively little effort has been expended developing dual- and triple-band T2SL based focal plane arrays (FPAs)," Razeghi told Spectrum. "There is a unique opportunity to mature this material system and realize a new generation of dual- and triple-band FPA sensors."
However, Razeghi concedes that, responsivity, which dictates how sensitive a photodetector is, and the dark current, which is related to the noise, must be further improved. This means the optimization of many parameters, including device design, material growth, and all of the processing steps, must result in high reproducibility and high yield.
"We need to reduce the bias dependency of the long-wavelength channel to a reasonable range so that it could be compatible with the currently available readout integrated circuit," says Razeghi.
The next step in the research, she says, will be to fabricate a three-color infrared camera. She added: "Our long term goal is to improve both electrical and optical performance of the detectors in order to make cheap high-performance infrared cameras for different applications."
Sony says Uncharted 4 copies stolen; Issues 'spoiler alert'
Dead body found in Apple's Cupertino HQ
Infosys invests in Trifacta
Encryption: Good or bad, the debate continues
Infosys announce partnership with KUKA Aktiengesellschaft
Meizu to launch M3 Note in India on May 11
Microsoft not ready to give up on Windows 10 Mobile yet
Slow networks hurting Apple growth in India: CEO Tim Cook
Apple says witnessing strong demand for iPhone SE
By a News Reporter-Staff News Editor at Electronics Newsweekly -- LARGAN PRECISION CO., LTD. (Taichung, TW) has been issued patent number 9316819, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.
The patent's inventors are Hsu, Po-Lun (Taichung, TW); Chen, Wei-Yu (Taichung, TW); Hsueh, Chun-Che (Taichung, TW).
This patent was filed on November 15, 2012 and was published online on April 19, 2016.
From the background information supplied by the inventors, news correspondents obtained the following quote: "The present invention relates to an imaging lens system, and more particularly, to an imaging lens system used in electronic products and infrared photography.
"The demand for compact imaging lens assembly grows in recent years with the increasing popularity of portable electronic products with photographing function. The sensor of a general photographing camera is none other than CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) sensor. Furthermore, as the advanced semiconductor manufacturing technology has allowed the pixel size of the sensors to be reduced, and the current electronic products are leaning toward a trend of being more compact, there is an increasing demand for high quality imaging lens.
"On the other hand, the emerging motion capture technology applied in smart TV or motion sensing games also expands the application of compact imaging lens. The feature of these applications is by an infrared camera directly capturing the user's motion, the user takes control of the device intuitively; the experience of the motion sensing operation is elevated. Therefore, the demand for compact imaging lens operated in the infrared wavelength range has increased; what is more, lenses with wide viewing angle are even more welcome because they can extend the capturing range of the camera.
"In view of this, an imaging lens structure applied in slim and portable electronic devices is needed; on one hand, imaging lenses with this structure can be optimized for the requirement of ordinary photography (wide viewing angle, large aperture, image quality, etc.), on the other hand, lenses with this structure can be optimized for motion capture in the infrared wavelength range."
Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors' summary information for this patent: "The present invention provides an imaging lens system, in order from an object side to an image side comprising: a first lens element with positive refractive power having a convex object-side surface at a paraxial region and a convex image-side surface at the paraxial region; a plastic second lens element with positive refractive power having a concave object-side surface at the paraxial region, a convex image-side surface at the paraxial region, and both of the object-side and image-side surfaces thereof being aspheric; and a plastic third lens element with negative refractive power having a concave object-side surface at the paraxial region, a concave at the paraxial region and convex at a peripheral region image-side surface, and both of the object-side and image-side surfaces thereof being aspheric; wherein the lens elements of the imaging lens system with refractive power are the first lens element, the second lens element, and the third lens element, a curvature radius of the object-side surface of the first lens element is R1, a curvature radius of the image-side surface of the first lens element is R2, a focal length of the first lens element is f1, a focal length of the second lens element is f2, and they satisfy the following relations: -0.5<(R1+R2)/(R1-R2)<1.0; and 1.65<f1/f2<5.0.
"In another aspect, the present invention provides an imaging lens system, in order from an object side to an image side comprising: a first lens element with positive refractive power having a convex object-side surface at a paraxial region and a convex image-side surface at the paraxial region; a plastic second lens element with positive refractive power having a concave object-side surface at the paraxial region, a convex image-side surface at the paraxial region, and both of the object-side and image-side surfaces thereof being aspheric; and a plastic third lens element with negative refractive power having a concave object-side surface at the paraxial region, a concave at the paraxial region and convex at a peripheral region image-side surface, and both of the object-side and image-side surfaces thereof being aspheric; wherein the lens elements of the imaging lens system with refractive power are the first lens element, the second lens element, and the third lens element, a c urvature radius of the object-side surface of the first lens element is R1, a curvature radius of the image-side surface of the first lens element is R2, a curvature radius of the object-side surface of the third lens element is R5, a focal length of the imaging lens system is f, and they satisfy the following relations: -0.5<(R1+R2)/(R1-R2)<1.0; and -1.33<R5/f<-0.55.
"In still another aspect, the present invention provides an imaging lens system, in order from an object side to an image side comprising: a first lens element with positive refractive power having a convex object-side surface at a paraxial region and a convex image-side surface at the paraxial region; a plastic second lens element with positive refractive power having a concave object-side surface at the paraxial region, a convex image-side surface at the paraxial region, and both of the object-side and image-side surfaces thereof being aspheric; and a plastic third lens element with negative refractive power having a concave at the paraxial region and convex at a peripheral region image-side surface, and both of the object-side and image-side surfaces thereof being aspheric; wherein the lens elements of the imaging lens system with refractive power are the first lens element, the second lens element, and the third lens element, the imaging lens system is used for optical wavelen gths ranging from 780 nm to 950 nm, a curvature radius of the object-side surface of the first lens element is R1, a curvature radius of the image-side surface of the first lens element is R2, and they satisfy the following relation: -0.5<(R1+R2)/(R1-R2)<1.0.
"In the aforementioned imaging lens system, the first lens element has positive refractive power to effectively distribute the refractive power of the second lens and helps to reduce the sensitivity of the imaging lens system. The second lens element has positive refractive power and provides the main refractive power of the system to control the total track length of the lens system effectively and avoid too large a volume of the lens system. The third lens element has negative refractive power and forms a positive-negative telephoto structure with the second lens element and can reduce the total track length of the imaging lens system effectively. With the aforementioned configuration, the present invention can reduce the total track length of the imaging lens system, increase the viewing angle of the lens system effectively, and facilitate the compact and wide-angle applications."
For the URL and additional information on this patent, see: Hsu, Po-Lun; Chen, Wei-Yu; Hsueh, Chun-Che. Imaging Lens System. U.S. Patent Number 9316819, filed November 15, 2012, and published online on April 19, 2016. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=9316819.PN.&OS=PN/9316819RS=PN/9316819
Keywords for this news article include: Technology, Electronics, Semiconductor, LARGAN PRECISION CO. LTD..
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