Tech Briefs

2.2-Micron, Uncooled, InGaAs Photodiodes and Balanced Photoreceivers up to 25-GHz Bandwidth

These photodiodes have applications in LiDAR sensors, telecommunications links, and pulsed laser systems.

Traditional applications for 2-micron photodetectors have been largely dominated by passive remote sensing where detectors having bandwidth of even one megahertz are deemed sufficient. The onus in such applications is to achieve low dark current through active cooling. The advent of high-power, 2-micron-wavelength lasers has made coherent LiDARs viable for active sensing applications. Such a system needs photodetectors that can handle high local oscillator optical power and have large bandwidth. Through a combination of high coherent gain and small integration time, a large signal-to-noise ratio can be achieved. Operation at high optical power levels reduces the significance of photodiodes' dark current. As a result, uncooled operation at room temperature is feasible, simplifying the overall instrument design.

Posted in: Briefs, Photonics
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PC-Board-Mountable Corrosion Sensors

These sensors address the problem of corrosion in microelectronics in many different applications.

Corrosion is a pervasive and expensive problem in applications ranging from construction to microelectronics. Corrosion has been widely studied in theories, and empirical studies exist for common materials, material combinations, and myriad environmental conditions. In order for microelectronic devices to perform and function properly, high-reliability packaging is important. Failure of microelectronic devices and packages not only causes a malfunction of the devices themselves, but can lead to catastrophic events for entire systems, which may cause loss of life, property, and safety.

Posted in: Briefs, Sensors
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Gas Sensing System Employing Raman Scattering

This system identifies and characterizes various gases in a mixture or sample, and monitors and controls industrial processes or reactions.

The detection and characterization of molecular gases in a sample is a relatively difficult challenge. Usually, this task is relegated to expensive and time-consuming processes like mass spectrometry and gas chromatography. Furthermore, numerous industrial applications require such gas-phase analysis for pollution and process control; for example, in large, natural-gas-fired turbine electricity generators, large quantities of natural gas are mixed with air and burned. Because natural gas comes from a variety of sources, the composition of the gas changes often. If the composition of natural gas were known a-priori, turbine efficiency could be improved by adjusting the fuel/air mixture and other operating parameters. This control capability requires measurement of the components of the natural gas to better than 0.1% accuracy, with the measurement being performed at least once every second. There is currently no commercially available sensor or sensing system that can measure all of the natural-gas components in one second.

Posted in: Briefs, Sensors
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Absorbent Polymer Reinforcing Fiber

This material improves mechanical properties without degrading their absorption performance.

Absorbent polymers can be used, for instance, to absorb hydrocarbons from an aqueous medium such as the absorption of oil from water. In some configurations, conventional absorbent polymers are contained within a permeable material; for example, conventional spill “socks” and booms can hold an absorbent polymer within a fabric to enable the absorbent polymer to be applied directly to the site of interest. Moreover, conventional absorbent booms can float on a water surface to help contain a spill from spreading beyond the boom. This application, however, requires the absorbent polymer to be contained within a permeable membrane or fabric.

Posted in: Briefs, Materials
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MSET Industrial Early Warning System

MSET is applicable to any industry in which continuous operation and safety are imperative, including the power industry, manufacturing, aerospace, and pharmaceuticals.

System breakdowns in modern industrial environments can result in millions of dollars in lost time and productivity, and even the loss of life and property. In the utilities industry — where the continuous operation of coolant pumps is essential — the breakdown of a single pump can result in a loss of as much as $10 million in downtime.

Posted in: Briefs, Software
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Wireless Temperature Sensor Having No Electrical Connections, and Sensing Method for Use

The temperature sensor is damage-tolerant, wireless, flexible, precise, and inexpensive.

NASA's Langley Research Center has developed a robust wireless temperature sensor that does not require an electrical connection. The temperature sensor is built on NASA's SansEC sensor platform, which takes advantage of measuring dielectric changes. The temperature sensor is damage-tolerant, wireless, flexible, precise, and inexpensive. One promising application is for tire temperature sensors.

Posted in: Briefs, Sensors
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Lightweight, Crack-Resistant, Silk Composite Sensor

The damage-sensing probe embedded into a composite of epoxy and silk could be used for building more resilient infrastructure, airplanes, and consumer products.

New lightweight, energy-saving composites that won't crack or break even after prolonged exposure to environmental or structural stress are needed in industries such as civil infrastructure for bridges and buildings, consumer products, and aerospace. To help make that possible, a method was developed to embed a nanoscale damage-sensing probe into a lightweight composite made of epoxy and silk. The probe, known as a mechanophore, could speed up product testing, and potentially reduce the amount of time and materials needed for the development of many kinds of new composites.

Posted in: Briefs, Sensors
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Compact, Lightweight, Athermal, Nanocomposite Telescopes with Freeform Optics

Small space missions such as CubeSats frequently require telescopes with highly sophisticated optical systems that are also low in mass and cost. The very limited spacecraft volume and mass limits also preclude adjustments to maintain critical alignment with change in temperature. Existing systems, especially those that employ folded optical paths with freeform optics, are expensive to fabricate. The optics, and support and metering structures, are also heavy due to the use of high-density material such as glass, aluminum, or nickel.

Posted in: Briefs, Photonics
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TiBor Skin Composite Coatings

TiBor Skin is a two-part technology that creates toughened, corrosion- and wear-resistant composite structures. The technology consists of coatings or surface materials for application on metals, plus methods of applying these materials. It also provides methods of integrating the applied coatings with their substrates to form composite structures, the surfaces of which wear and corrode at rates much lower than those currently experienced in the industry.

Posted in: Briefs, Materials
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Airborne Sense-and-Avoid Radar Panel

This lightweight, low-cost antenna could be used on unmanned vehicles in security and disaster response efforts, communications, aerial mapping, and aerial surveillance.

Although unmanned aerial systems (UAS) have proven increasingly useful in a variety of applications, their widespread usage within the National Airspace System is limited because of regulatory restrictions on their access to shared airspace.

Posted in: Briefs, Aeronautics, Aerospace
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