Physical Sciences

Low-Distortion Imaging Spectrometers

"Pushbroom" imaging spectrometers of a proposed type would exhibit little or no distortion in either the spectral or spatial direction. These spectrometers would feature modified Offner optics, which afford a desirable combination of compactness and a high degree of optical correction. Although Offner optics have been used in some spectrometer designs, their potential for eliminating distortion does not appear to have been exploited.

Posted in: Briefs, TSP, Physical Sciences, Measurements, Imaging, Imaging and visualization, Optics, Spectroscopy, Imaging, Imaging and visualization, Optics, Spectroscopy
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Evaluation of Exhaust Flows From Thrust-Vectoring Nozzles

A unique dual-flow, cold-jet facility has been developed and operated by California Polytechnic State University (Cal Poly) at San Luis Obispo for NASA Dryden Flight Research Center. The facility supports flight research on thrust-vectoring nozzles and thrust-vector control systems. To date, the facility has completed tests on subscale nozzles of the F/A-18 High Alpha Research Vehicle (HARV), the X-31 airplane, and the F-15 Advanced Control Technology for Integrated Vehicles (ACTIVE).

Posted in: Briefs, Physical Sciences, Nozzles, Test facilities
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Monolithic Electrostatic Sector for Miniature Mass Spectrometers

An improved miniature electrostatic sector has been designed for a miniature double-focusing mass spectrometer (see figure). Miniature mass spectrometers are essential components of high-performance, miniature, low-power instruments that are being developed for use in analyzing chemical compositions of small amounts of substances (e.g., toxic chemicals in the environment) in scientific laboratories, in industrial settings, and in the field.

Posted in: Briefs, TSP, Physical Sciences, Spectroscopy, Spectroscopy
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Oscillating-Flow Heat-Transfer and Pressure-Drop Test Rig

The figure illustrates an apparatus for measuring heat-transfer and pressure-drop characteristics of porous plug specimens in oscillating flows. The apparatus is built around an oscillating-flow test rig that was originally designed for pressure-drop (but not heat-transfer) measurements and has since been modified and refined. The flows and specimens are chosen to be representative of those encountered in the regenerators of Stirling engines.

Posted in: Briefs, TSP, Physical Sciences, Heat transfer, Heat transfer, Stirling engines, Test equipment and instrumentation
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Adjacent-Pair Imaging Shearography Using Bacteriorhodopsin

In a developmental technique of real-time adjacent-pair imaging shearography, a thin film of bacteriorhodopsin is used to record shearograms in argon-laser light for immediate readout in helium/neon-laser light. Unlike conventional silver-halide-based photographic film, bacteriorhodopsin can be used as a real-time recording medium because it yields an image immediately upon exposure and is optically erasable. Bacteriorhodopsin also offers the advantage of resolution as high as 5,000 lines/mm — comparable to the resolutions of silver-halide-based films and much greater than the 80 lines/mm typical of the charge-coupled-device video cameras used heretofore in real-time shearography. Issues to be addressed in subsequent development include the difficulty of recording over a previously recorded image at the recording wavelength, the need for Fourier-transform optics for readout, the need to optimize the optics to realize the full potential for high resolution, and the relative insensitivity of bacteriorhodopsin film (about a tenth of that of silver-halide-based film).

This work was done by Colleen Fitzpatrick of Rice Systems, Inc., for Kennedy Space Center. For further information, access the Technical Support Package (TSP) free on-line at www.nasatech.com under the Physical Sciences category, or circle no. 161 on the TSP Order Card in this issue to receive a copy by mail ($5 charge).

In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:

Colleen Fitzpatrick
Rice Systems, Inc.
1150 Main Street, Suite C
Irvine, CA 92614
(714) 553-8768
E-mail: ricesys@prodigy.com

Refer to KSC-11838, volume and number of this NASA Tech Briefs issue, and the page number.

Posted in: Briefs, Physical Sciences, Imaging, Imaging and visualization, Lasers, Imaging, Imaging and visualization, Lasers, Bacteria, Research and development
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Black-Body Evaporator Unit for a Point-Focus Solar Collector

The figure illustrates a solar thermal energy system for boiling water or another liquid. The system can be used for a variety of purposes that can include drying aqueous hazardous waste, distilling pure solvent from spent solvent, purifying water by distillation, or generating steam. The principal innovative feature of this system is an absorber/evaporator unit, which is designed to absorb radiant solar energy with an effectiveness close to that of an ideal (in the black-body sense) absorber. The design is such that unlike in some other systems, it is not necessary to coat the solar-irradiated surface with a high-solar-absorptivity ("solar black") material to obtain the desired black-body characteristic. The design is also simpler than that of other absorber/evaporator units.

Posted in: Briefs, TSP, Physical Sciences, Water treatment, Solar energy, Materials properties
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