Photonics

Designing for Compressive Sensing: Compressive Art, Camouflage, Fonts, and Quick Response Codes

Compressive sensing (CS) is a relatively new field that has caused a lot of excitement in the signal processing community. It has superseded Shannon's time-honored sampling theorem, which states that the sampling rate of a signal must be at least twice its highest frequency. In CS, the necessary sampling rate depends on the sparsity of signal, not its highest frequency, reducing sampling requirements for many signals that exhibit natural sparsity. This compression happens on the hardware level, allowing systems to be designed with benefits ranging from increased resolution and frame rates to decreased power consumption and memory usage. Despite this enthusiasm for CS and the large quantity of research being performed, the number of commercial systems that use CS is relatively few. The problem of designing a CS strategy that increases functionality while actually reducing overall system cost has not been solved in many areas. This is a developing field where not only are new applications for CS still being developed, but also fundamental aspects of CS theory are still evolving.

Posted in: Briefs, Aerospace, Defense, Electronic Components, Electronics, Electronics & Computers, Energy, Energy Efficiency, Imaging, Fiber Optics, Optical Components, Optics, Data Acquisition, Sensors
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Phonon Confinement Effect in TiO2 Nanoparticles as Thermosensor Materials

TiO2 or ZnO nanoparticles (NPs) have a very strong finite-size dependency in their Raman spectra or photoluminescence (PL) spectra due to the phonon confinement effect or the quantum confinement effect. Together with a fast grain growth kinetics and a high stability under high temperature and pressure, they can forensically retain the complete thermal history of an event. By spatially distributing these NPs during thermal events such as blasts or weapon tests, a spatially and temporally non-uniform thermal environment can be determined by a direct read off their Raman or PL spectra at various locations.

Posted in: Briefs, Aerospace, Defense, Thermal Management, Materials, Nanotechnology, Photonics, Force Sensors and Resistors, Sensors, Test & Measurement
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Air Force Research Lab and Industry Advance Multi-Junction Solar Cells

Experts at the Air Force Research Laboratory (AFRL) continue to expand the scope of their technological expertise, rising above the Earth’s surface to meet the power needs of next-generation military spacecraft. A collaborative effort between the AFRL Materials and Manufacturing and Space Vehicles directorates, the Space Industrial Base Working Group, and SolAero Technologies has resulted in state-of-the art, multi-junction solar cells destined to reduce costs and increase power efficiency for military space applications.

Posted in: News, Defense, Solar Power, Materials, Photonics
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Army Developing Lasers That Pierce Fog, Dust to Destroy Targets

A lot of people think that high-energy lasers, or HELs, can't penetrate fog, rain and dust, said Thomas Webber, director of the Directed Energy Division's Technical Center, U.S. Army Space and Missile Defense Command. That's just plain wrong.

Posted in: News, Defense, Lasers & Laser Systems, Optics
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Identifying and Isolating Signals Using Radio Frequency Photonics

A single antenna can be used for both transmission and reception. To accomplish this, the transmission must be isolated from the reception. In Figure 1, a radio frequency (RF) circulator is connected right after the antenna. The three-port device separates the transmit path from the receive path. After the circulator, a system can be used to identify the frequency of different signals. Once the frequency has been found, a filter with the right pass-band frequency can be used to isolate signals from each other.

Posted in: Articles, Aerospace, Communications, Wireless, Fiber Optics, Lasers & Laser Systems, Optical Components, Optics, Photonics, Antennas, Radio equipment
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Researchers Show How Fear Memories Can Be Erased

Researchers at the University of California, Riverside have devised a method to selectively erase particular fear memories by weakening the connections between the nerve cells (neurons) involved in forming these memories. A sight, sound, or smell we have sensed may not later trigger fear, but if the stimulus is associated with a traumatic event, such as a car accident, then fear memory is formed, and fearful responses are triggered by the stimulus.

Posted in: News, Defense, Medical, Photonics
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Robot’s Speed-of-Light Communication Could Protect You From Danger

Cornell University researchers are developing a system to enable teams of robots to share information as they move around, and if necessary, interpret what they see. This would allow the robots to conduct surveillance as a single entity with many eyes. Beyond surveillance, the new technology could enable teams of robots to relieve humans of dangerous jobs such as disposing of landmines, cleaning up after a nuclear meltdown or surveying the damage after a flood or hurricane. The project, called “Convolutional-Features Analysis and Control for Mobile Visual Scene Perception,” is supported by a four-year, $1.7 million grant from the U.S. Office of Naval Research.

Posted in: News, Defense, Machine Vision, Visualization Software, Optics, Robotics
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Heads-up Display Improves Soldiers’ Situational Awareness

A novel technology called "Tactical Augmented Reality," or TAR, is now helping soldiers precisely locate their positions, as well as the locations of friends and foes. It even enables them to see in the dark, all with a heads-up display device that looks like night-vision goggles (NVG). In essence, TAR replaces NVG, GPS, plus it does much more.

Posted in: News, Defense, Optical Components, Optics
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Laser Integration on Silicon Photonic Circuits Through Transfer Printing

The purpose of this project was to develop a transfer printing process for the massively parallel integration of III-V lasers on silicon photonic integrated circuits. Silicon has long offered promise as the ultimate platform for realizing compact photonic integrated circuits (PICs). That promise stems in part from the material's properties: the high refractive-index contrast of silicon allows strong confinement of the optical field, increasing light-matter interaction in a compact space—a particularly important attribute for realizing efficient modulators and high-speed detectors.

Posted in: Briefs, Aerospace, Photonics, Integrated circuits, Lasers, Fabrication, Materials properties, Semiconductors
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High Energy Computed Tomographic Inspection of Munitions

An advance computed tomography (CT) system was recently built for the U.S. Army Armament Research, Development and Engineering Center, Picatinny Arsenal, NJ, for the inspection of munitions. The system is a charged coupled device (CCD) camera based CT system designated with the name “experimental Imaging Media” (XIM). The design incorporated shielding for use up to 4MeV x-ray photons and integrated two separate cameras into one single field of view (FOV). Other major distinguishing characteristics include its processing functions to digitally piece the two cameras together, use of advanced artifact reduction principles, performing reconstruction simultaneously during acquisition, and its development in accurate beam hardening corrections through digital means.

Posted in: Briefs, Aerospace, Photonics, Charge coupled devices, Imaging, Defense industry, Inspections, Missiles
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