Sensores

Universal Photonics Acquires J.I Morris Surface Polishing Business

photonics - Sáb, 12/16/2017 - 09:49
Surface preparation materials manufacturer Universal Photonics Inc. (UPI) has acquired Massachusetts-based J.I. Morris Co.’s surface polishing pads and materials business.

The business will operate in the JH Rhodes Co. Inc. manufacturing facility in Vernon, New York. JH Rhodes a subsidiary of UPI and specializes in manufacturing polishing pads for glass, crystal, metal and ceramic applications.

“UPI continues its mission to provide and advance critical surfacing materials with the acquisition of J.I. Morris Company’s polishing pad business,” said Neil Johnson, president and CEO of UPI. “J.I. Morris Company’s high-quality products and services fits well into the polishing material business of Universal Photonics. The acquisition will expand our ability to meet specialized customer applications with an even larger variety of pad materials and technology.”

UPI provides polishing pads for processes from pre-polish to final-polish with surface requirements ranging from commercial grade to zero defect levels.
Categorías: Sensores

Concept Laser Breaks Ground on New German Facility

photonics - Sáb, 12/16/2017 - 09:00

Machine technology developer Concept Laser GmbH, a part of GE Additive, has laid the foundation for a new facility in Lichtenfels, Germany.
Groundbreaking ceremony for new location for 3D metal printing in Lichtenfels. Courtesy of Concept Laser.
The new campus will unite R&D with production, service and logistics. The offices will be finished in 2019, with 40,000 sq m of room for 500 employees. The future machine production capacity will be four times higher than its current capacity, making Concept Laser’s Lichtenfels facility a global GE center for the production of 3D metal printing machines. About €105 million ($123.5 million) will be invested into the location.

“I am pleased to take the next step in our growth strategy with today’s groundbreaking,” said Frank Herzog, founder, chairman and CEO of Concept Laser. “We are not only laying the foundation for a new facility, but also creating skilled jobs in the region. Lichtenfels will become a global beacon for industrial 3D printing as the new GE center. Today is a good day for Lichtenfels and the region. I would like to thank everyone involved for making this advancement possible.”

The 3D Campus will accommodate Concept Lasers growth and make room for further expansions.

“The investment made by GE and Concept Laser is a clear statement of confidence in the location,” said Ilse Aigner, Bavarian minister of economic affairs and media, energy and technology. “It secures jobs and provides a vital boost to growth in the region. The 3D Campus will create a center for 3D metal printing that offers real added value for the whole of Bavaria. 3D printing is becoming more prevalent in almost all sectors because it allows lighter, more variable and more stable components to be produced using fewer resources. Additive manufacturing therefore has an important role to play for Bavaria as a forward-looking industrial location.”

Concept Laser is a provider of machine and plant technology for the 3D printing of metal components. Since December 2016, Concept Laser has been part of GE Additive, a division of General Electric Co.
Categorías: Sensores

Silicon Sense to Import Nanodiamond Materials Into US

photonics - Vie, 12/15/2017 - 09:00
Silicon Sense Inc., the U.S. representative of Finnish nanodiamond manufacturer Carbodeon Ltd. Oy, has become the first U.S.-based importer of detonation nanodiamond materials to be granted registration by the U.S. Environmental Protection Agency (EPA) to import nanodiamonds into the country for industrial purposes.

The registrations, under the low-volume exemption (LVE) rule, cover four main Carbodeon product ranges including three monofunctionalized nanodiamond grades and one multifunctionalized grade.

“Following precise environmental risk analysis using data from Carbodeon as well as invaluable inputs from a number of our U.S. customers, the EPA has granted LVE registration for all Carbodeon proprietary nanodiamond materials currently supplied in the U.S.A.,” said James Meriano, vice-president of Silicon Sense.

“Customer safety and environmental issues are always among our top priorities,” said Vesa Myllymäki, CEO of Carbodeon. “This EPA approval will further strengthen our already strong position in the U.S. market place and beyond. The four approved types of nanodiamond product are used in enhancing thermal, mechanical and other properties in polymers, coatings and metal finishing across multiple industries including electronics, automotive, aerospace and defense, industrial and consumer.”
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Rigaku Opens New German Office

photonics - Vie, 12/15/2017 - 09:00
X-ray analytical instrumentation provider Rigaku Corp. has opened a new office in the Frankfurt Rhine-Main region.

The new facility is home to a large and well-equipped application development and demonstration facility, complete with extensive sample preparation and wet chemistry labs. The grand opening event was attended by numerous Rigaku distributors operating in European countries.

Rigaku is a developer of x-ray spectrometry, diffraction and optics, as well as small molecule and protein crystallography and semiconductor metrology.
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Integration of Quantum Emitters to Photonic Device Could Enable Quantum Circuits

photonics - Jue, 12/14/2017 - 14:18

Researchers integrated silicon photonic devices with a solid-state single photon emitter, using a hybrid approach that combines silicon photonic waveguides with quantum dots. The silicon photonic waveguides were used for manipulating light, and the InAs/InP quantum dots were used to generate light efficiently at wavelengths spanning the O-band and C-band. 


A schematic of the integrated InP nanobeam and silicon waveguide. Courtesy of UNIST.
The research team, from Ulsan National Institute of Science and Technology (UNIST) and the University of Maryland, removed the quantum dots via a pick-and-place procedure, using a microprobe tip combined with a focused ion beam and scanning electron microscope. Using the pick-and-place technique the researchers positioned epitaxially grown InAs/InP quantum dots, emitting at telecom wavelengths, on a silicon photonic chip with nanoscale precision. They used an adiabatic tapering approach to efficiently transfer the emission from the quantum dots to the waveguide. The researchers also incorporated an on-chip silicon-photonic beamsplitter to perform a Hanbury-Brown and Twiss measurement.


This is a scanning electron microscope image of the fabricated nanobeam that is suspended by thin tethers that attach it to the bulk substrate. Courtesy of UNIST. The research team believes their approach could enable integration of precharacterized III–V quantum photonic devices into large-scale photonic structures, which would enable complex devices composed of many emitters and photons. 
“In order to build photon-based integrated quantum optical devices, it is necessary to produce as many quantum light sources as possible in a single chip,” said UNIST professor Je-Hyung Kim. “Through this study, we have proposed the basic form of quantum optical devices by producing a highly effective quantum light source with quantum dots and creating the pathway to manipulate light with the use of silicon substrates.”

The research team said the integration “opens up the possibility to leverage the highly advanced photonics capabilities developed in silicon to control and route nonclassical light from on-demand single photon sources. In addition, the fabricated devices operate at telecom wavelengths and can be electrically driven, which is useful for fiber-based quantum communication.”

The research was published in Nano Letters (doi: 10.1021/acs.nanolett.7b03220). 
Categorías: Sensores

Heck Appointed Principal Device Development Engineer at CST Global

photonics - Jue, 12/14/2017 - 09:00

Optoelectronic semiconductor foundry CST Global has appointed Susannah Heck as principal device development engineer.

“Susannah brings a wealth of technical experience in monolithic and hybrid optoelectronic integration; active and passive device design and verification on III-V compound semiconductors; and epitaxy, lithographic-mask and process design for wafer production,” said Andrew McKee, technical director at CST Global. “She also brings invaluable project planning, budgeting, resource allocation and management expertise with exceptional communication skills.”

Heck was previously the principal engineer at Kaiam Corp., as well as senior research and development engineer at Oclaro Inc. She has been both program manager and technical lead on projects such as next-generation, 100G, data-center, optoelectronic hardware design, development and verification. Heck began her working career as a research intern at the Tyndall National Institute before becoming a research associate in the Experimental Solid-State Physics department at Imperial College London.

She holds a bachelor’s degree and Ph.D. in physics from University College Cork, specializing in characterization of quantum dot and dash devices, material properties related to quantum dot anisotropy, threshold current and efficiency of III-V semiconductor lasers.

CST Global develops, manufactures and sells cutting-edge chips, components, modules and subsystems based on proprietary advanced semiconductor technology in microwave, millimeter wave and optical semiconductors.
Categorías: Sensores

Optical Surfaces Completes Order for The Table Stable

photonics - Jue, 12/14/2017 - 09:00
Optical component developer Optical Surfaces Ltd. has announced receipt of an order for precisely matched etalon pairs from active vibration isolation technology developer The Table Stable Ltd. for use as a key component in their ultrahigh-resolution JRS series interferometers.

Operating in a uniquely stable manufacturing environment, it is possible to produce the 50-mm diameter fused silica etalons pairs for Table Stable with matching accuracies of >λ/200. Etalon manufacture places extreme demands on a company’s production capabilities. Material purity, optical figure, plate parallelism, plus surface, spacer and coating quality are all critical to the overall performance of an etalon.

"We have worked closely with Optical Surfaces for a long time and have been very pleased with the quality of the matched etalon pairs they supply to us,” said John Sandercock, managing director of Table Stable. “When hard dielectric coatings are deposited on the substrates, differential expansion causes surface strains, which distort the surface. We have developed a procedure in cooperation with Optical Surfaces to compensate these forces and so obtain hard-coated etalons with surface quality of λ/200 or better.”

Optical Surfaces develops large optics, beam expanders, collimators, prototypes, custom systems and optics. The Table Stable develops active vibration isolation and high-resolution, high-contrast spectroscopy technologies.
Categorías: Sensores

Bosch Sensortec Named CES Honoree

photonics - Mié, 12/13/2017 - 09:00
Bosch Sensortec has been named an embedded technologies honoree at the CES 2018 Innovation Awards for its BMA400 ultralow-power accelerometer designed for wearables and Internet of Things applications.

“The BMA400 offers an unrivalled combination of low power consumption, outstanding performance and advanced features, making it ideal for wearables,” said Stefan Finkbeiner, CEO of Bosch Sensortec. “I’m delighted that its value has been recognized through this prestigious award.”

The accelerometer uses 10 times less current than existing products while still delivering exceptional performance and significantly extends battery lifetime for always-on wearable devices such as fitness bands, smart clothing, watches and activity trackers. The integrated ultralow-power step counter of the BMA400 makes it easy to add activity recognition into new types of wearables such as regular watches, cutting down development time and effort.

The CES Innovation Awards are sponsored by the Consumer Technology Association. Entries are evaluated by an expert panel on their engineering, aesthetic and design qualities, intended use/function, and user value, unique/novel features present, and how the design and innovation of the product directly compares to other products in the marketplace.
Categorías: Sensores

CSIR Celebrates 10 Years of R&D

photonics - Mié, 12/13/2017 - 09:00
The Council for Scientific and Industrial Research, South Africa's central and premier scientific research and development organization, is celebrating its tenth year of R&D in the nanotechnology field.

The CSIR’s National Centre for Nanostructured Materials (NCNSM) was launched in 2007 as part of the implementation of government’s national nanotechnology strategy. Nanotechnology research is a key pillar of the CSIR’s activities, focused on finding solutions that address the broader societal challenges of South Africa.

In the last decade, the center has undertaken innovative research on nanostructured materials and established an extensive research network with key local and international research organizations. The center is well equipped with cutting-edge scaling up, polymer processing, characterization and testing facilities. It is funded by the Department of Science and Technology (DST).

Other achievements include a prototype breath analyzer to detect diabetes without a blood test; the setting up of the water and catalysis research groups as new research areas in nanotechnology; the polymer processing laboratory for the testing and evaluation of industrial samples; and the development and establishment of the Nanomaterials Industrial Development Facility in 2015.

“Research and development at the nano center supports the manufacturing of bulk materials with improved properties, such as plastics, that are able to tolerate very high and low temperatures and plastics that possess fire retardant properties or high resistance to tearing,” said Suprakas Sinha Ray, CSIR chief researcher. “This includes the development of detection devices that use nanomaterials capable of detecting gases at parts-per-million levels with greater sensitivity and accuracy.”

Constituted by an Act of Parliament in 1945 as a science council, the CSIR undertakes directed and multidisciplinary research, technological innovation, as well as industrial and scientific development to improve the quality of life of the country’s people.
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Team Studies Optical Properties of Plasmonic Nanovesicles Using Computational Approach

photonics - Mar, 12/12/2017 - 15:37

An on-demand, light-triggered drug release method, known as vesicular assembly of small plasmonic nanoparticles, or plasmonic vesicle, could be used to treat disease; support the study of the nervous system in real time; provide insight into how the brain works; and provide rapid clearance of small inorganic particles from the body. Wide ranges of optical properties have been reported for plasmonic vesicles, including characteristic absorption peak in the visible or NIR ranges. However, it is unclear how the interaction among a large number of small plasmonic gold nanoparticles contribute to the collective optical property of a plasmonic vesicle.

To learn more about plasmonic vesicles, including how to best engineer them, researchers performed computational investigations into their collective optical properties.

The research team, from the University of Texas at Dallas (UT Dallas) and the University of Reims in France, focused its study on the dynamics of clusters of small gold nanoparticles with liposome cores and the nanoparticles’ potential applications in diagnostic and therapeutic areas. The team used the Stampede and Lonestar supercomputers at the Texas Advanced Computing Center, as well as systems at the ROMEO Computing Center at the University of Reims Champagne-Ardenne and the San Diego Supercomputing Center (through the Extreme Science and Engineering Discovery Environment) to perform large-scale virtual experiments of light-struck vesicles.

“A lot of people make nanoparticles and observe them using electron microscopy,” UT Dallas professor Zhenpeng Qin said. “But the computations give us a unique angle to the problem. They provide an improved understanding of the fundamental interactions and insights so we can better design these particles for specific applications.”

Cross-plane view of near-field electrical enhancement in plasmonic vesicles. Shown are 10-nm gold nanoparticles around 75-nm vesicle cores. Courtesy of Jaona Randrianalisoa, Xiuying Li, Maud Serre and Zhenpeng Qin.
Using the discrete dipole approximation (DDA) computation method, the team made predictions of the optical absorption features of the gold-coated liposome systems. Using DDA allowed the team to design new complex shapes and structures and to determine quantitatively what their optical absorption features would be.

The team simulated different liposome core sizes, different gold nanoparticle coating sizes, a wide range of coating densities, and random vs uniform coating approaches. The coatings included several hundred individual gold particles, behaving collectively.

“It is very simple to simulate one particle. You can do it on an ordinary computer, but we’re one of the first to be looking into a complex vesicle,” said professor Jaona Randrianalisoa from the University of Reims. “It is really exciting to observe how aggregates of nanoparticles surrounding the lipid core modify collectively the optical response of the system.”

Geometric features of gold-coated liposomes based on random (A-D) and uniform (E-H) arrangements of gold nanoparticles on the core surface. Courtesy of Jaona Randrianalisoa, Xiuying Li, Maud Serre and Zhenpeng Qin.
The team identified four characteristic regimes — the isolated nanoparticle regime, Coulomb interaction regime, black gold regime and nanoshell regime. They found that the small plasmonic nanoparticles needed to be very close together, or even overlapping, to give a broadband absorption (i.e., black gold regime) or form a NIR plasmon peak. They further found that smaller gold nanoparticle or larger core size led to higher NIR peak shift and photothermal conversion efficiency.

“We’d like to develop particles that interact with light in the near-infrared range — with wavelengths of around 700 to 900 nanometers — so they have a deeper penetration into the tissue,” Qin said.

The researchers anticipate that this study will provide design guidelines for nanoengineers and that it could have a significant impact on further development of complex plasmonic nanostructures and vesicles for biomedical applications.

The research was published in Advanced Optical Materials (doi: 10.1002/adom.201700403).   
Categorías: Sensores

Improving Quality of Hologram Memory for Use in Optical Data Storage

photonics - Mar, 12/12/2017 - 12:24

A research team has applied magnetic assist recording technology to magnetic-holographic memory, reducing recording energy consumption and achieving non-error data reconstruction. Their work could pave the way for practical application of magnetic-holographic memory for storing large volumes of data at ultrahigh recording density and at ultrahigh speed.

In magnetic hologram recording, a medium is magnetized in one direction, then irradiated with a signal beam and a reference beam. The resulting interference pattern is recorded in the form of the difference in magnetization directions. When this recording proceeds with an external magnetic field applied to it, the recording of the difference in magnetization directions becomes clearer — a process known as magnetic assist recording.

Researchers at Toyohashi University of Technology, led by professor Yuichi Nakamura, investigated the effects of magnetic assist (MA) recording through numerical simulation and experiment to improve the diffraction efficiency and the resulting reconstructed images.

Reconstructed image with and without magnetic assist. Courtesy of Toyohashi University of Technology.
The stray magnetic field distribution was calculated for the nonmagnetized region. Researchers found that the intensity of the stray magnetic field depended on garnet film thickness or substantially on the aspect ratio of the nonmagnetized region. The improvement of diffraction efficiency was more effective in garnet films thinner than the width of a fringe. A suitable value of the assist magnetic field was identified for the improvement.

Through further experiments, researchers found that MA recording improved the intensity of reconstructed images and broadened the non-error recording conditions to the low energy region.

This research could enable a significant reduction in errors in data recording and reconstruction using only a small amount of energy, as well as non-error recording and reconstruction using magnetic holographic memory.

“Until now it has been difficult to obtain a clear reconstruction image with a magnetic hologram, due to strict requirements for material characteristics, optical conditions, and so on. Using magnetic assist recording, we have relaxed these requirements and also improved the reconstruction performance of recording media. This technology is promising for the future application of magnetic-holographic memory,” said researcher Zen Shirakashi.

Associate professor Yuichi Nakamura (left) and Ph.D. candidate Zen Shirakashi. Courtesy of Toyohashi University of Technology.
The researchers will continue looking for ways to improve recording density. Their goal is to use this technology to make a portable, ultrahigh-density, high-speed optical information storage medium that outperforms Blu-ray discs and that is capable of storing high-volume contents from various sources, including 8K Super Hi-Vision broadcasting and 3D films. The team hopes to enable wide application of this technology in various types of storage systems, including archive and cold storage for storing information such as medical image data, social networking service data on the internet, and high-volume data in data centers.

The research was published in Scientific Reports (doi: 10.1038/s41598-017-12442-z).
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RPI’s Sawyer, Tufts’ Valencia, Awarded NSF Award

photonics - Mar, 12/12/2017 - 09:00
 Shayla Sawyer from Rensselaer Polytechnic Institute and Valencia Koomson from Tufts University, both part of the Center for Lighting Enabled Systems and Applications (LESA), have been awarded a National Science Foundation (NSF) EAGER award from the Division of Biological Infrastructure for $297,451 for their proposal titled “Ultrasensitive frequency domain spectrometer for high throughput bacteria detection in floodwater.”

This two year EAGER research project will advance fundamental research on sensing technology for rapid characterization of pathogenic bacteria in floodwater generated by future catastrophic events. In the aftermath of major catastrophic hurricanes, danger quietly continues in the form of microbial contamination in the remaining floodwaters. NSF announced this special EAGER solicitation in early September in response to Hurricane Harvey to address a variety of technical challenges related to recovery from storm damage.

The awarded work leverages previous research at LESA to develop microbial contamination biosensors that are ultrasensitive, low power, compact and robust. This sensor technology will have broad applications in detecting microbial biohazards as part of a growing Internet of Things environmental security sensing platform.

Aspects of the research program involve merging self-assembled nanocomposite structures, high-sensitivity analog electronics, ultralow-power multiplexing and digitization circuitry and emerging microfabrication techniques to design a new class of compact fluorescence spectrometers. This enables high throughput spatial and temporal correlation of biofluorescence emission data for bacteria characterization unachievable with current systems.

The award’s cross-disciplinary research and education program will have significant broader impacts on fluorescence spectroscopy and optical sensor technology based on heterogeneous integration of nanocomposite optoelectronic sensors with state of the art silicon signal processing technology. The new sensor platform hopes to lead to a new class of low-power, miniature biosensors that will enable detection of microbial contamination in water, air and on surfaces. Interactive workshops with biochemists, environmental engineers and students will be organized to guide spectrometer development.

Funded primarily by NSF, LESA is an interdisciplinary, multi-university center developing smart lighting systems.
Categorías: Sensores

Zwicky Transient Facility Camera Undergoes First Light

photonics - Mar, 12/12/2017 - 09:00
A robotic camera with the ability to capture hundreds of thousands of stars and galaxies in a single shot has taken its first image as part of the Zwicky Transient Facility (ZTF) automated sky survey project based at Caltech's Palomar Observatory.

As partners in the ZTF effort, University of Maryland (UMD) astronomers contributed to the planning and design of the survey project. UMD participation in ZTF is facilitated by the Joint Space-Science Institute, a partnership between UMD and NASA's Goddard Space Flight Center in Greenbelt, Maryland.

Every night, ZTF's camera will scan a large swath of the Northern sky, discovering objects and events that vary in brightness over time, collectively known as transients. Survey targets will include explosive supernovae, hungry black holes and hurtling asteroids and comets.

"The ZTF survey will be transformative for the study of supermassive black holes feasting on stars in the centers of galaxies," said Suvi Gezari, an assistant professor of astronomy at UMD and a fellow of the Joint Space-Science Institute. “The timing of these events, known as tidal disruption events, can be used to constrain the mass and spin of black holes. Data from ZTF may also offer a rare, real-time glimpse into the formation of an accretion disk — and possibly relativistic jets — around a supermassive black hole."

The ZTF survey is named after Caltech's first astrophysicist, Fritz Zwicky, who discovered 120 supernovae in his lifetime. Recently installed at the Oschin Telescope, ZTF's new survey camera can take in seven times more sky in a single image than its predecessor. At maximum resolution, each ZTF camera image is 24,000 × 24,000 pixels.

Additionally, ZTF's upgraded electronics and telescope drive systems enable the camera to take more than twice as many exposures every night. Astronomers will not only be able to discover more transient objects, they will also be able to catch more ephemeral features that appear and fade quickly.

"There's a lot of activity happening in our night skies," said Shrinivas Kulkarni, the principal investigator for ZTF and the George Ellery Hale Professor of Astronomy and Planetary Science at Caltech. "In fact, every second, somewhere in the universe, there's a supernova that's exploding. Of course, we can't see them all but with ZTF we will see up to tens of thousands of explosive transients every year over the three-year lifetime of the project."

Images from ZTF will be adjusted, cleaned and calibrated at IPAC, Caltech's astronomy and data center. Software will search the flood of ZTF data for light sources--in particular those that change or move. These data will be made public to the entire astronomy community for both research and education.

"Data from ZTF presents a really great opportunity for students here at UMD, because large survey programs like ZTF will play a big role in the future of astronomy," said Melissa Hayes-Gehrke, a principal lecturer and undergraduate director of astronomy at UMD. Hayes-Gehrke has led efforts to develop educational materials that make use of data from PTF and ZTF. "It is fantastic to get students in on the ground floor. Astronomers will be mining this data for years to come, so this is an important step to help prepare students for a career in research."
Categorías: Sensores

Optical Surfaces Provides Paraboloid and Flat Mirror to Simera Technology

photonics - Mar, 12/12/2017 - 09:00
Optical component and system provider Optical Surfaces Ltd. has delivered a 300-mm diameter off-axis paraboloid and a mounted flat mirror to Simera Technology Group Ltd., an engineering design and development company specializing in the development of unmanned aerial vehicles (UAVs) and small satellite optical payload systems.

Optical Surfaces manufactured the off-axis parabolic mirror with a surface accuracy of >λ /15 P-V, surface quality of 20/10 scratch/dig and surface slope error of λ /10/cm P-V. This, together with an ultrasmooth coated reference flat, has been produced from Zerodur as the main reflective and reference components for a large flight test alignment collimator under construction in Simera Technology Group’s optical clean room. This will be the largest and most capable privately-owned facility for testing of airborne and spaceborne optics in South Africa.

"The contract for the off-axis parabolic and flat mirrors was awarded to Optical Surfaces Ltd. based upon its proven expertise and experience in producing demanding optical systems for the space and satellite systems community,” said Louwrens Marais, Systems Engineer at Simera Technology. "We have been very pleased with the technical expertise shown and the support provided by Optical Surfaces Ltd., both in direct dealings, and through Talex UK Ltd., our U.K. collaborator. We therefore placed an additional order on Optical Surfaces Ltd. for the manufacture of Flight Model mirrors for a space telescope project we’re currently involved in. These consist of an annular Zerodur Primary Mirror and second-surface Secondary Mirror. Both are chemically etched spherical mirrors, requiring surface accuracies >λ /10 P-V."

Optical Surfaces is a provider of large optics, beam expanders, collimators and prototypes, plus custom systems and optics. Simera Technology is a mechanical and mechatronic engineering design and development company servicing government, research, design and production industry sectors throughout all phases of the product development life cycle.
Categorías: Sensores

That Was Then, This Is Now: Fiber Optic Cables Find New Use as Seismic Sensors

photonics - Lun, 12/11/2017 - 13:41

The decade that gave us the Sony PlayStation also gave us dark fiber — an excess of optical fiber cables installed underground, mostly in the 1990s, before advances in data transmission reduced the need for all those cables. Now, research teams on the earthquake-prone West Coast of the U.S. are putting dark fiber optic cables to use as sensor arrays for seismic monitoring.

Scientists at the Lawrence Berkeley National Laboratory (Berkeley Lab) and Stanford University have shown that dark fiber networks can be used for sensing earthquakes, the presence of groundwater, changes in permafrost and a variety of other subsurface activity.

In a project using laser interrogators provided by OptaSense, Stanford researchers have recorded more than 800 seismic events by monitoring a three-mile loop of optical fiber installed in existing telecommunications conduits beneath the Stanford University campus. A parallel study, conducted by Berkeley Lab scientists, utilized two networks installed in Richmond, Calif. and Fairbanks, Alaska to acquire similar datasets using a laser interrogator provided by Silixa Ltd. The two teams worked together to compare results, as discussed in a recent article in Geophysical Research Letters. The teams told Photonics Media that ongoing experiments are being conducted in California’s Central Valley and the Mojave desert in collaboration with several other institutions.

Map shows location of a three-mile, figure-8 loop of optical fibers installed beneath the Stanford campus as part of the fiber optic seismic observatory. Courtesy of Stamen Design and the Victoria and Albert Museum.
The two teams have reported seismic monitoring results comparable to those achieved with conventional seismometers using distributed acoustic sensing (DAS), a technology that measures seismic wavefields by shooting short laser pulses across the length of the fiber. Tiny impurities in the fiber cause the laser light to scatter. If the fiber is stationary, the backscatter signal stays the same. But if the fiber starts to stretch in some areas, due to vibrations or strain, the signal changes.

“When the fiber is deformed, we will see distortions in the backscattered light, and from these distortions, we can measure how the fiber itself is being squeezed or pulled,” Jonathan Ajo-Franklin, a researcher at Berkeley Lab, said.

“We got interested in DAS due to research at LBNL in a related technology that uses fiber to measure temperature — distributed temperature sensing,” Ajo-Franklin told Photonics Media. “We had used DTS to monitor deep wells which are difficult to instrument. Since I’m a seismologist, when DAS started developing we immediately jumped on the technology to help instrument wells for seismic measurements . . .

“Oil and gas wells . . . are tough on traditional sensors (geophones). Fibers, when correctly packaged, can be very rugged and handle these environments, hence the DAS technology is a great match for borehole geophysics,” Ajo-Franklin said.

The Berkeley Lab and Stanford teams conducted two studies related to the use of DAS for seismic sensing.

Using DAS for Near-Surface Seismic Monitoring
In the first study, documented in a recent article in Scientific Reports, the teams demonstrated the efficacy of near-surface seismic monitoring using DAS-recorded ambient noise. Results of the study showed that as a low-cost, dense array, DAS could be useful in establishing smarter systems for monitoring the Earth’s near surface.

“The idea is that by using fiber that can be buried underground for a long time, we can transform traffic noise or other ambient vibrations into usable seismic signals that can help us monitor near-surface changes such as permafrost thaw and groundwater-level fluctuations,” said researcher Shan Dou, also from Berkley Lab.

Shan Dou (from left), Jonathan Ajo-Franklin and Nate Lindsey were on a Berkeley Lab team that used fiber optic cables for detecting earthquakes and other subsurface activity. Courtesy of Berkeley Lab.
DAS and Dark Fiber for Earthquake Detection
In a follow-up study, Berkeley Lab and Stanford researchers demonstrated the viability of using fiber-optic cables for earthquake detection.  Using DAS, the two teams took independent measurements on fiber-optic arrays at two locations in California — including the Stanford University campus — and one in Alaska. In all three cases, DAS proved to be about as sensitive to earthquakes as conventional seismometers, despite its higher noise levels. Using the DAS arrays, the Berkeley Lab and Stanford teams assembled a catalog of local, regional and distant earthquakes and showed how novel processing techniques could be used to take advantage of DAS’ many channels, in order to better understand where earthquakes originate. 
According to researchers, a seismic recording approach using DAS, in contrast to traditional seismometers, would be relatively inexpensive to implement and operate.

“Every meter of optical fiber in our network acts like a sensor and costs less than a dollar to install,” said Biondo Biondi, a professor of geophysics at Stanford. “You would never be able to create a network using conventional seismometers with that kind of coverage, density and price.”

Since the fiber optic seismic observatory at Stanford began operation in September 2016, it has recorded and cataloged more than 800 events, ranging from manmade events and small local temblors to events like the 2017 earthquakes in Mexico, which were more than 2,000 miles away from the observatory. In one particularly revealing experiment, the underground array picked up signals from two small local earthquakes with magnitudes of 1.6 and 1.8.

“As expected, both earthquakes had the same waveform, or pattern, because they originated from the same place, but the amplitude of the bigger quake was larger,” Biondi said. “This demonstrates that the fiber optic seismic observatory can correctly distinguish between different magnitude quakes.”

The array also distinguished between two different types of waves that travel through the Earth, called P and S waves.

The Fiber Optic Seismic Observatory successfully detected the 8.2 magnitude earthquake that struck Central Mexico on Sept. 8, 2017. Courtesy of Siyuan Yuan.
“One of our goals is to contribute to an early earthquake warning system. That will require the ability to detect P waves, which are generally less damaging than S waves but arrive much earlier,” Stanford graduate student Eileen Martin said.

Dark Fiber Benefits
Berkley's Ajo-Franklin said that dark fiber allows for dense spatial sampling, because data points are only meters apart, whereas traditional seismometers are typically separated by many kilometers.

Traditional seismometers are expensive to install and maintain, but dark fiber is installed everywhere, including in subsea locations.

One end of the fiber needs to be physically accessible, researchers told Photonics Media, so that there is a place where the laser pulse can be initiated. But the rest of the fiber can be anywhere — down a deep well, on the bottom of the ocean or inside a concrete block, for example.

“Fiber has a lot of implications for earthquake detection, location and early warning,” said Nate Lindsey, who is a UC Berkeley graduate student. “Fiber goes out in the ocean, and it’s all over the land, so this technology increases the likelihood that a sensor is near the rupture when an earthquake happens, which translates into finding small events, improved earthquake locations, and extra time for early warning.”

The researchers told Photonics Media that the primary challenge to monitoring dark fiber undersea is the limits to the distance over which DAS can be utilized. Each interrogator can “sense” between 10 and 50 kilometers depending on the specifics of the technology, and undersea cables can be thousands of kilometers long.

The work done by the Berkeley Lab and Stanford teams is the first step toward developing a city-wide seismic network in the San Francisco Bay area.

The research was published in Scientific Reports (doi: 10.1038/s41598-017-11986-4). Geophysical Research Letters (doi: 10.1002/2017GL075722), and The Leading Edge (doi: 10.1190/tle36121025.1).

The research is also being presented at the American Geophysical Union Fall Meeting, December 11-15, 2017. There are two presentations: Dark Fiber and Distributed Acoustic Sensing: Applications to Monitoring Seismicity and Near-Surface Properties, and Earthquake Recording at the Stanford DAS Array With Fibers in Existing Telecomm Conduits.  
Categorías: Sensores

NASA Radiometry Instrument at MIT to Launch Into Orbit

photonics - Lun, 12/11/2017 - 09:00

The NASA-funded CubeSat MiRaTA  — the Microwave Radiometer Technology Acceleration — will be launched into Earth's orbit from the rocket carrying the National Oceanic and Atmospheric Administration’s JPSS-1U.S. weather satellite into space.

The Microwave Radiometer Technology Acceleration (MiRaTA) satellite, a 3U CubeSat, is shown with solar panels fully deployed, flanking the body of the spacecraft, which has a circular aperture at the top for the microwave radiometer antenna, used for atmospheric science measurements. There are also two small, thin tape-measure antennas on the top, used for UHF radio communication with the ground station. Courtesy of MIT Lincoln Laboratory.

MiRaTA is designed to demonstrate that a small satellite can carry instrument technology that's capable of reducing the cost and size of future weather satellites and has the potential to routinely collect reliable weather data. Microwave radiometers are one of the workhorse instruments aboard today's weather satellites. These sensitive instruments measure radio frequency signals related to the thermal radiation emitted by atmospheric gases, such as molecular oxygen and water vapor, and also detect particles such as cloud ice. These data are key inputs for models that track storms and other weather events.

Calibrating these radiometers is important for keeping them from drifting so their data can be used for accurate weather and climate models. Therefore, a calibration target is usually included in the satellite to help the radiometer maintain its accuracy. Miniaturizing microwave radiometer instruments to fit on a CubeSat leads to the challenge of finding a calibration instrument that is not only accurate but also compact, according to Kerri Cahoy, principal investigator for MiRaTA and an associate professor in the Department of Aeronautics and Astronautics at the Massachusetts Institute of Technology.

"You don't have room for the bulky calibration targets that you would normally use on larger satellites," Cahoy said. "Microwave radiometer calibration targets on larger satellites can be the size of a toaster, but for CubeSats, it would have to be the size of a deck of cards."

Cahoy and her colleague William Blackwell, the microwave radiometer instrument lead at MIT Lincoln Laboratory, have come up with a solution based on a technique she studied in graduate school called radio occultation (RO), whereby radio signals received from GPS satellites in a higher orbit are used to measure the temperature of the same volume of atmosphere that the radiometer is viewing. The GPS-RO temperature measurement can then be used for calibrating the radiometer.

"In physics class, you learn that a pencil submerged in water looks like it's broken in half because light bends differently in the water than in the air," Cahoy said. "Radio waves are like light in that they refract when they go through changing densities of air, and we can use the magnitude of the refraction to calculate the temperature of the surrounding atmosphere with near-perfect accuracy and use this to calibrate a radiometer."

"Our goal is to have our radiometers perform just as well as those on current weather satellites and be able to provide the kind of data that helps agencies and people in the path of a natural disaster prepare early and wisely," Cahoy said.
Categorías: Sensores

Cancer Detection Device Developers Win McMaster’s John Dyson Award

photonics - Lun, 12/11/2017 - 09:00

Michael Takla, Rotimi Fadiya, Prateek Mathur and Shivad Bhavsar, all graduates of McMaster's Electrical and Biomedical Engineering program, have received the prestigious James Dyson Award with $50K to support the development of The sKan, the team's skin cancer detection device.

Members of the sKan team meet James Dyson during a visit to the company's U.K. Headquarters. Courtesy of McMaster.
The sKan was one of only two Canadian projects that made the shortlist of 20 finalists, selected from over 1,000 entries from 23 countries by a panel of Dyson engineers. Named after the renowned British inventor, designer and force behind Dyson, the home appliance technology company, the James Dyson award celebrates, encourages and inspires the next generation of design engineers. The award is open to current and recent design engineering students.

The sKan assists physicians and the average person in detecting melanoma by creating a thermal map on the region of interest on the skin. The device is made up of 16 temperature-sensitive components called thermistors that look for areas of significant temperature difference on the skin, which may indicate risk of melanoma. Current diagnosis methods are purely qualitative and based only on visual inspection. The sKan provides quantitative information about skin spots so that physicians can select appropriate patients for a biopsy.

"We came across the issue of skin cancer and how technology hasn't had the same impact on its diagnosis as it has on other fields in medicine,"Mathur said. "We found research that used the thermal properties of cancerous skin tissue as a means of detecting melanoma. However, this was done using expensive lab equipment. We set out to apply the research and invent a way of performing the same assessment using a more cost-effective solution."

The knowledge the team gained from their undergraduate engineering program, which has since evolved into the new Integrated Biomedical Engineering & Health Sciences (iBiomed) program, helped them develop and execute their idea.

"Our education on anatomy and physiology allowed us to understand the physiological concepts discussed in the research papers we used," Bhavsar said. "We were also able to design a large portion of our electrical system based on the knowledge we gained from our electrical and computer engineering courses."

"We're proud of The sKan team for winning this international award," said Ishwar K. Puri, McMaster's dean of engineering. "At McMaster Engineering, we inspire all of our students to have big ideas through design thinking, innovation and entrepreneurship. We educate them to become engaged citizen scholars who will transform the world and solve those wicked problems our society faces."

The next step for the sKan group is to create a new prototype that will bring them to the pre-clinical testing phase. "Our aspirations have become a reality," Mathur said. "Skin cancers are the most common form of cancer worldwide, and the potential to positively impact the lives of those affected is both humbling and motivating."
Categorías: Sensores

Columbia Receives NSF Grant for Wireless Sensors

photonics - Lun, 12/11/2017 - 09:00
The Data Science Institute and the Electrical Engineering Department at Columbia University received a $650,000 National Science Foundation grant to develop energy-efficient sensors that allow mobile- and wireless-device users to tap into available unused channels in the radio-frequency spectrum.

The sensors will enable future communication systems to flexibly share the spectrum. Wireless communications and mobile applications have placed an enormous strain on the electromagnetic spectrum, which is a finite and limited resource.

"At some point in the future, as we keep using more and more mobile devices, the spectrum will run out of space," said John Wright, a DSI affiliate and electrical engineering professor who is the principal investigator on the project. "We'll use all the data-science tools we possess — machine learning, neural networks, algorithms and advanced computation techniques, in conjunction with new hardware devices — to sense pieces of the RF spectrum as they become available."

Wright said that Peter Kinget, an electrical engineering professor at Columbia who specializes in analog and radio frequency(RF) integrated circuits, will design circuits that can create snapshots of a large portion of the spectrum. Wright will then use a few of the snapshots to design algorithms to reconstruct the spectrum and help design a more energy-efficient sensor.

The project mixes the latest computational methods with novel hardware design. Wright will lead a team to develop algorithms and machine-learning methods to model and predict the available areas of the spectrum. Kinget's team will design circuits to sense the available channels in the spectrum.

"This project builds upon our ongoing fruitful collaboration with John's team," Kinget said. "In the past couple of years, we have demonstrated several RF spectral sensors that generally used off-the-shelf signal-processing approaches with our custom hardware and have demonstrated significant speed and energy benefits. It will be exciting to see how much more progress we can make using new algorithms built on the latest insights in signal processing."
Categorías: Sensores

Sandia’s Michelsen, Tsao Elected OSA Fellows

photonics - Sáb, 12/09/2017 - 09:00
Sandia National Laboratories researchers Hope Michelsen and Jeff Tsao have been elected fellows of the Optical Society.

Michelsen was elected for pioneering contributions to the fundamental understanding of laser-radiation interactions with soot particles through laser-induced incandescence, absorption, scattering and laser-induced incandescence to assess environmental impacts of carbonaceous particle.

“It is an opportunity for me to remember and express gratitude for all of the great people I’ve worked with in developing the optical diagnostics for soot and black carbon that have brought me this honor,” Michelsen said. “I have also been very fortunate to have stable funding through the Department of Energy’s Basic Energy Sciences program to accomplish this work.

Michelsen’s research program focuses on developing and using optical techniques for studying the chemistry of combustion-generated particles inside the combustor and their impact on climate when released to the atmosphere. Her research experience includes gas-surface scattering experiments, atmospheric modeling, soot-formation studies, combustion-diagnostics development, atmospheric black-carbon measurements and greenhouse-gas source attribution.

Tsao was elected for seminal, sustained contributions over 20 years to solid-state lighting and its materials and optoelectronic device foundations. His career path includes two national laboratories and brief stints in industry and academia.

In the late 1990s, when the efficiency of phosphor-converted white light light-emitting diodes was only a few percent, few researchers thought these glowing white rocks might someday be used for general illumination. However, Tsao and colleagues at Sandia and HP co-authored a paper that predicted efficiencies as high as 50 percent and the enormous energy-savings potential that would be realized if achieved. The white paper is widely credited with inspiring solid-state lighting activity all over the world. He later served on Energy Department committees that outlines possible paths for improved LED lighting and came up with new ways of improving LED efficiencies and usefulness. His published solid-state lighting work has accumulated 1,750 citations.

Tsao said the fellow award “is also recognition of the many wonderful colleagues at Sandia and elsewhere with whom I have been fortunate to have worked, and of Sandia as an institution, whose exceptional service in the national interest inspires the kind of forward-looking research in the national interest that the award was for.”

The Optical Society is the leading professional association in optics and photonics.
Categorías: Sensores

Researchers Make Transparent Materials Absorb Light

photonics - Vie, 12/08/2017 - 15:09

Researchers have demonstrated an optical paradox — they have made a completely transparent material appear perfectly light-absorbing. The results of their research contradict the idea that materials that look transparent, such as glass, appear that way because they have no light-absorbing qualities. Based on their results, researchers introduce the concept of coherent virtual absorption in a lossless electromagnetic system, a phenomenon that arises when the incident electromagnetic field matches the spatiotemporal distribution of a complex scattering zero of a lossless system.

This is a schematic of a virtual light absorption process: A layer of a transparent material is exposed to light beams from both sides, with the light intensity increasing in time. Image courtesy of the MIPT  researchers. Courtesy of MIPT Press Office.
Researchers from the Moscow Institute of Physics and Technology (MIPT) used special mathematical properties of the scattering matrix to achieve results. When a light beam of time-independent intensity hits a transparent object, the light does not get absorbed but is scattered by the material. However, researchers found that if the intensity of the incident beam was grown exponentially, the total incident light energy accumulated in the transparent material and did not leave it, thus making the material appear perfectly absorbing from the outside. Interruption of the exponential driving gave rise to the release of energy stored in the lossless system through radiation in the background. 
To illustrate the effect, researchers examined a thin layer of a transparent dielectric and calculated the intensity profile required for the absorption of the incident light. The calculations confirmed that when the incident wave intensity grew exponentially, the light was neither transmitted nor reflected — the layer looked perfectly absorbing despite the fact that it lacked the actual absorption capacity. However, when the exponential growth of the incident wave amplitude came to a halt (at t = 0), the energy that was locked in the layer was released.



This is virtual absorption effect in a thin layer of a transparent material. The dotted line indicates the amplitude of a time-dependent incident wave; the solid line is the amplitude of a scattered signal that comprises both incident and transmitted waves. The scattered signal is absent up to t = 0, suggesting that the incident wave energy is perfectly "locked" in the layer. Image courtesy of the researchers. Courtesy of MIPT Press Office.
Researchers found that this effect was robust against frequency dispersion of the system material, possible dissipation, and the finite geometry of the structure. The observed effect could have implications for flexible control of light propagation and storage, low-energy memory, and optical modulation, and could broaden understanding of how light behaves when it interacts with common transparent materials.

“Our theoretical findings appear to be rather counterintuitive. Up until we started our research, we couldn’t even imagine that it would be possible to ‘pull off such a trick’ with a transparent structure,” said researcher Denis Baranov. “However, it was the mathematics that led us to the effect. Who knows, electrodynamics may well harbor other fascinating phenomena.”

The research was published in Optica, a publication of OSA, The Optical Society (doi: 10.1364/OPTICA.4.001457).   
Categorías: Sensores

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