Test & Measurement

A Synthetic Quadrature Phase Detector/ Demodulator for Fourier Transform Spectrometers

This method makes it possible to use simple, low-cost, high-resolution audio digitizers. Langley Research Center, Hampton, Virginia Fourier transform spectroscopy works by measuring a spectral/light signal through a Michelson interferometer. In order to know the wavelength of the signal, one must use a stable reference, which is typically a metrology laser. In a standard Fourier transform spectrometer (FTS) system, the laser signal also runs through the interferometer and the laser beam is guided to a separate detector that is then used to trigger an analog-to-digital converter, which then captures the spectral signal.

Posted in: Briefs, TSP, Test & Measurement


Device for Direct Measurement of the Diffusivity and Molecular Release Through Membranes and Filters

Controlled-release systems for drug delivery, molecular sieving, and single-molecule detection use micro and nano structures. Lyndon B. Johnson Space Center, Houston, Texas Concentration-driven molecular diffusion is a fundamental phenomenon essential for the transport of nutrients in cells, for oxygen exchange in the lungs, and mating of chemicals in industrial reactors and the food industry. Thus, diffusion plays a key role in a variety of disciplines. The concentration-driven diffusive transport is commonly described by Fick’s laws of diffusion. It is most often approximated by the Stokes-Einstein equation, which assumes a rigid solute sphere diffusing in a continuum of solvent at a low Reynolds number and infinite dilution.

Posted in: Briefs, Test & Measurement


Magnetic Encoders

POSITAL (Hamilton, NJ) introduced new models of IXARC magnetic encoders that combine incremental and absolute rotation measurement capabilities in a single, compact package. Absolute encoders provide a control system with a report of the rotational angle and rotation count at a specific point in time; incremental encoders provide a signal pulse each time the encoder shaft rotates by a specified angle. The hybrid encoders are based on the company’s magnetic measurement technology, and offer shock, dust, and moisture resistance. The hybrid incremental and absolute rotary encoders have communications interfaces that support both measurement modes: RS-422, HTL, or TTL for incremental readings; and SSI for absolute measurements. Available multi-turn versions can count up to 64,000 revolutions, while incremental measurements have resolutions as high as 16,384 pulses per revolution. For Free Info Visit http://info.hotims.com/55588-300

Posted in: Products, Manufacturing & Prototyping, Mechanical Components, Motion Control, Measuring Instruments


Emily Wilson, Scientist, Goddard Space Flight Center, Greenbelt, MD

Emily Wilson developed a miniaturized laser heterodyne radiometer (mini-LHR) to measure the emissions of carbon dioxide and methane from melting permafrost. Wilson’s technology will be one of several NASA instruments sent to Alaska in June to analyze trace gases in the region’s atmosphere.

Posted in: Who's Who, Environmental Monitoring, Greenhouse Gases, Lasers & Laser Systems, Measuring Instruments, Monitoring


Sampling Mechanism for a Comet Sample Return Mission

A similar sampling mechanism could be deployed in dangerous situations on Earth. Goddard Space Flight Center, Greenbelt, Maryland Sample return missions have the ability to vastly increase scientific understanding of the origin, history, current status, and resource potential of solar system objects including asteroids, comets, Mars, and the Moon. However, to make further progress in understanding such bodies, detailed analyses of samples are needed from as many bodies as possible. A standoff sample collection system concept has been developed that would quickly obtain a sample from environments as varied as comets, asteroids, and permanently shadowed craters on the Moon, using vehicles ranging from traditional planetary spacecraft to platforms such as hovering rotorcraft or balloons on Mars, Venus, or Titan. The depth of penetration for this harpoon- based hollow collector was experimentally determined to be proportional to the momentum of the penetrator in agreement with earlier work on the penetration of solid projectiles. A release mechanism for the internal, removable sample cartridge was tested, as was an automatic closure system for the sample canister.

Posted in: Briefs, TSP, Aerospace, Data Acquisition, Mechanical Components, Machinery & Automation, Monitoring


An Operationally Based Vision Assessment Simulator for Domes

Applications include remote visualization, flight simulation, virtual environments, and planetariums. Ames Research Center, Moffett Field, California The work described here is part of the U.S. Air Force-sponsored Operational Based Vision Assessment (OBVA) program that has been tasked with developing a high-fidelity flight simulation laboratory to determine the relationship between human vision and performance in simulated operationally relevant tasks. The OBVA simulator was designed and built to provide the Air Force School of Aerospace Medicine (USAFSAM) with a scientific testing laboratory to study human vision and testing standards.

Posted in: Briefs, Aeronautics, Computers, Simulation Software, Test & Measurement


Low Er-Doped Yttrium Gallium Garnet (YGG) as Active Media for Solid-State Lasers at 1651 nm

This technology could serve applications in the bio-medical areas such as nerve stimulation and dentistry. Goddard Space Flight Center, Greenbelt, Maryland The typical approach for producing laser output at the 1651-nm wavelength is via nonlinear frequency conversion. Lasers based on nonlinear conversion are complex, and it is very difficult to provide stability over time and over a wide range of operating temperatures. The efficiency of such optical sources is also low. A much more promising approach is the use of active media that allows for the development of solid-state lasers (SSL) with spectral emission at 1651 nm. An important requirement for this active medium is the ability to support in-band pumping with a low quantum defect since this approach leads to significant improvement in efficiency of SSLs and excellent beam characteristics due to low thermal stress of the active media.

Posted in: Briefs, TSP, Instrumentation, Medical, Lasers & Laser Systems, Test & Measurement


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