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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS1981

Radiance profile enhancement for solar occultation measurements

It is pointed out that distortions in received signals in solar occultation measurements made from space derive from the systematic motion of the electrooptical sensor. In a wide range of cases, the motion-related signal distortions brought about by the instrument's full modulation transfer function are as important as those from the optics. It is shown through simulation that existing techniques in the field of digital-image processing can be applied directly to solar occultation experiments to correct for these distortions. The resulting enhanced radiation profile is found to be much closer to the true radiance profile than is the sampled output of the instrument.

Gomberg, R. I.↗

NASA NTRS1981

Optical detection of pulsed surface particle displacements

The detection of acoustic surface wave pulses by a wideband differential interferometric laser technique which is insensitive to low frequency noise is described. System bandwidth is determined by the relationship between acoustic wavelength and the variable spacing between two laser probe beams focused on the solid surface which supports the waves. Theoretical sensitivity to surface displacement amplitude is equal to, or better than, that of other electrooptical techniques. Response to an ideal step function displacement is analyzed and experimental measurements of gated 2.5 MHz pulses generated on an aluminized pyrex plate are discussed. Potential application in the characterization of acoustic emission in composites is described.

Zerwekh, P. S.↗

NASA NTRS1982

Integrated optics technology study

The materials and processes available for the fabrication of single mode integrated electrooptical components are described. Issues included in the study are: (1) host material and orientation, (2) waveguide formation, (3) optical loss mechanisms, (4) wavelength selection, (5) polarization effects and control, (6) laser to integrated optics coupling,(7) fiber optic waveguides to integrated optics coupling, (8) souces, (9) detectors. The best materials, technology and processes for fabrication of integrated optical components for communications and fiber gyro applications are recommended.

Chen, B.↗

NASA NTRS1981

The Magsat three axis arc second precision attitude transfer system

The Magsat Attitude Transfer System (ATS), which provides attitude alteration in pitch, yaw, and roll is described. A remote vector magnetometer extends from Magsat on a 20 ft boom, requiring vector orientation by reference to coordinate axes determined by a set of star mapping cameras. The ATS was designed to perform in a solar illuminated environment by using an optically narrow bandwidth with synchronous demodulation at 9300 A. The pitch/yaw optical design, the electrooptics, and signal and switching diagrams are provided. Simple mirrors with no moving parts are placed on the magnetometer to reflect a collimated beam from the ATS for attitude indication, which is accurate to one part in 96. Alignment was completed within 24 hr after launch.

Schenkel, F. W.↗

NASA NTRS1982

A miniature electro-optical air flow sensor

Miniature sensors are needed for rapid and uncomplicated installation on light aircraft engaged in stability research programs. One particularly difficult sensor to miniaturize to the required degree has been a flow angle and velocity sensor for measuring the local flow ahead of a wing. However, by using an electrooptical technique it was possible to overcome the encountered difficulties and to design a sensor satisfying the requirements. The developed sensor for measuring angle-of-attack, yaw, and airspeed was shown to be suitable for rapid instrumentation of research aircraft because of its small size. The size reduction was accomplished by a design feature which eliminates the need for slip rings and wiring within the movable components of the sensor.

Kershner, D. D.↗

NASA NTRS1983

A tunable dual frequency dye laser - dual frequency oscillator design

The pulsed dye laser offers a tunable oscillator, followed by three amplifiers. It is pumped by a dual frequency Nd:YAG laser. Tuning and spectral width are controlled by a holographic network connected to a high power telescope. The modified two wavelength dye laser allows for absorption lidar techniques for remote sensing of the atmosphere. Line switching is achieved by electrooptical commutation. A feasibility experiment was performed with the original oscillator. A model was then built, and tested with different dyes. After a few modifications were made to improve the conversion efficiency, this oscillator was inserted in the laser to check whether the amplifier stages were correctly adjusted.

Abury, Y.↗

NASA NTRS1983

Long-range surface plasmons in electrode structures

Surface polaritons guided by symmetric double metal film structures are analyzed, with particular attention given to the attenuation of the two long-range modes that occur. It is found that long-range surface plasmon polariton modes do exist for double electrode structures over a limited range of material parameters. Guided by thin metal electrodes, surface plasmon polaritons can achieve millimeter plus propagation distances in the near infrared. It is pointed out that if the slab is electrooptic, then very low voltages will be needed to manipulate the waves. The fact that long-range modes exist simultaneously with junction tunnel plasmons may be of use in providing directional radiation from light-emitting junctions or the inverse process of light to electrical energy conversion.

Stegeman, G. I.↗

NASA NTRS1985

Frequency-Modulation Correlation Spectrometer

New type of correlation spectrometer eliminates need to shift between two cells, one empty and one containing reference gas. Electrooptical phase modulator sinusoidally shift frequencies of sample transmission spectrum.

Margolis, J. S.↗

NASA NTRS1984

Space environment effects (M0006)

The effects of long term exposure to the near Earth space environment on advanced electrooptical and radiation sensor components were examined. The effect of long duration spaceflight on the germination rate of selected terrestrial plant seeds is observed in exobiological experiments.

Angelo, J. A., Jr.↗

NASA NTRS1985

Flowmeter for Clear and Translucent Fluids

Transducer with only three moving parts senses flow of clear or translucent fluid. Displacement of diaphragm by force of flow detected electrooptically and displayed by panel meter or other device. Transducer used to measure flow of gasoline to automobile engine.

White, P. R.↗

NASA NTRS1984

Advanced infrared laser modulator development

A parametric study was conducted to develop an electrooptic waveguide modulator for generating continuous tunable sideband power from an infrared CO2 laser. Parameters included were the waveguide configurations, microstrip dimensions device impedance, and effective dielectric constants. An optimum infrared laser modulator was established and was fabricated. This modulator represents the state-of-the-art integrated optical device, which has a three-dimensional topology to accommodate three lambda/4 step transformers for microwave impedance matching at both the input and output terminals. A flat frequency response of the device over 20 HGz or = 3 dB) was achieved. Maximum single sideband to carrier power greater than 1.2% for 20 W microwave input power at optical carrier wavelength of 10.6 microns was obtained.

Cheo, P. K.↗

NASA NTRS1985

Development of the sonic pump levitator

The process and mechanism involved in producing glass microballoons (GMBs) of acceptable quality for laser triggered inertial fusion through use of glass jet levitation and manipulation are considered. The gas jet levitation device, called sonic pumps, provides positioning by timely and appropriate application of gas mementum from one or more of six sonic pumps which are arranged orthogonally in opposed pairs about the levitation region and are activated by an electrooptical, computer controlled, feedback system. The levitation device was fabricated and its associated control systems were assembled into a package and tested in reduced gravity flight regime of the NASA KC-135 aircraft.

Dunn, S. A.↗

NASA NTRS1983

Short wavelength infrared hybrid focal plane arrays

The employment of area focal plane arrays (FPA) has made it possible to obtain second generation infrared imaging systems with high resolution and sensitivity. The Short Wavelength Infrared (SWIR) region (1-2.5 microns) is of importance for imaging objects at high temperature and under conditions of reflected sunlight. The present investigation is concerned with electrooptical characterization results for 32 x 32 SWIR detector arrays and FPAs which are suitable for use in a prototype imaging spectrometer. The employed detector material is Hg(1-x)Cd(x)Te grown by liquid phase epitaxy on a CdTe transparent substrate. Attention is given to details of processing, the design of the detector array, the multiplexer, the fabrication of the hybrid FPA, and aspects of performance.

Vural, K.↗

NASA NTRS1983

Integrated optics for fiber gyro's

Expected advantages of incorporating integrated optical waveguide components into fiber gyroscopes are summarized. The structural-simplicity benefits which can be achieved through the use of solid-state lasers, and integrated and fiber optics are examined; angular rate noise and random walk drift for the current technology in the 0.84-micron wavelength region are reported as 0.00001 deg/sec and 0.0002 deg/hr to the 1/2, respectively. The state-of-the-art in the pertinent materials research is reviewed; lithium niobate, suggested to be used as a waveguide substrate material, is noted to have a complex chemistry that is not yet fully understood. However, most of the optical and electrooptical components of a fiber gyro are conceptually understood and have been demonstrated.

Goss, W.↗

NASA NTRS1985

Low altitude, one centimeter, space debris search at Lincoln Laboratory's (M.I.T.) experimental test system

The majority of work performed by the Lincoln Laboratory's Space Surveillance Group, at the request of NASA, to define the near-earth population of man-made debris is summarized. Electrooptical devices, each with a 1.2 deg FOV, were employed at the GEODSS facility in New Mexico. Details of the equipment calibration and alignment procedures are discussed, together with implementation of a synchronized time code for computer controlled videotaping of the imagery. Parallax and angular speed data served as bases for distinguishing between man-made debris and meteoroids. The best visibility was obtained in dawn and dusk twilight conditions at elevation ranges of 300-2000 km. Tables are provided of altitudinal density distribution of debris. It is noted that the program also yielded an extensive data base on meteoroid rates.

Taff, L. G.↗

NASA NTRS1986

Technology achievements and projections for communication satellites of the future

Multibeam systems of the future using monolithic microwave integrated circuits to provide phase control and power gain are contrasted with discrete microwave power amplifiers from 10 to 75 W and their associated waveguide feeds, phase shifters and power splitters. Challenging new enabling technology areas include advanced electrooptical control and signal feeds. Large scale MMIC's will be used incorporating on chip control interfaces, latching, and phase and amplitude control with power levels of a few watts each. Beam forming algorithms for 80 to 90 deg. wide angle scanning and precise beam forming under wide ranging environments will be required. Satelllite systems using these dynamically reconfigured multibeam antenna systems will demand greater degrees of beam interconnectivity. Multiband and multiservice users will be interconnected through the same space platform. Monolithic switching arrays operating over a wide range of RF and IF frequencies are contrasted with current IF switch technology implemented discretely. Size, weight, and performance improvements by an order of magnitude are projected.

Bagwell, J. W.↗

NASA NTRS1984

Retroreflector field tracker

An electrooptical position-measuring instrument, the Retroreflector Field Tracker or RFT, is described. It is part of the Dynamic Augmentation Experiment - a part of the payload of Space Shuttle flight 41-D in Summer 1984. The tracker measures and outputs the position of 23 reflective targets placed on a 32-m solar array to provide data for determination of the dynamics of the lightweight structure. The sensor uses a 256 x 256 pixel CID detector; the processor electronics include three Z-80 microprocessors. A pulsed laser diode illuminator is used.

Wargocki, F. E.↗

NASA NTRS1986

Technology achievements and projections for communication satellites of the future

Multibeam systems of the future using monolithic microwave integrated circuits to provide phase control and power gain are contrasted with discrete microwave power amplifiers from 10 to 75 W and their associated waveguide feeds, phase shifters and power splitters. Challenging new enabling technology areas include advanced electrooptical control and signal feeds. Large scale MMIC's will be used incorporating on chip control interfaces, latching, and phase and amplitude control with power levels of a few watts each. Beam forming algorithms for 80 to 90 deg wide angle scanning and precise beam forming under wide ranging environments will be required. Satellite systems using these dynamically reconfigured multibeam antenna systems will demand greater degrees of beam interconnectivity. Multiband and multiservice users will be interconnected through the same space platform. Monolithic switching arrays operating over a wide range of RF and IF frequencies are contrasted with current IF switch technology implemented discretely. Size, weight, and performance improvements by an order of magnitude are projected.

Bagwell, J. W.↗