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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Electro optical performance of an improved deformable mirror device

The design, fabrication, and performance of an improved 128 x 128 deformable mirror device (DMD) are discussed. The present DMD consists of a monolithically formed array of cantilever beams which are electrostatically deflected by an underlying MOS transistor address matrix. In contrast to an earlier version, the improved DMD on-chip address circuitry supports a single video input to the chip, with all demux operations performed on-chip. The cantilever beams are formed by two layers of high-reflectivity aluminum alloy. The dynamic range of the DMD in the Fourier plane at the Nyquist frequency has been determined at greater than 45 dB.

Wu, Wen R.↗
NASA NTRS1990

Finite element analysis of thermal distortion effects on optical performance of solar dynamic concentrator for Space Station Freedom

An analysis was performed to predict the thermal distortion of the solar dynamic concentrator for Space Station Freedom in low earth orbit and to evaluate the effects of that thermal distortion on concentrator on-orbit performance. The analysis required substructural finite element modeling of critical concentrator structural subsystems, structural finite element modeling of the concentrator, mapping of thermal loading onto the structural finite element model, and the creation of specialized postprocessors to assist in interpreting results. Concentrator temperature distributions and thermally induced displacements and slope errors and the resulting receiver flux distribution profiles are discussed. Results determined for a typical orbit indicate that concentrator facet rotations are less than 0.2 mrad and that the change in facet radius due to thermal flattening is less than 5 percent. The predicted power loss due to thermal distortion effects is less than 0.3 percent. As a consequence the thermal distortions of the solar dynamic concentrator in low earth orbit will have a negligible effect on the flux distribution profiles within the receiver.

Doherty, Michael P.↗
NASA NTRS1990

High-performance optical disk mass storage for aerospace imaging systems

The specifications and techniques related to the development of the NASA Spaceflight Optical Disk Recorder (SODR) are presented. The system is being developed for the temporary storage of high-resolution sensor data that will be collected at high data rates by future space programs. Typical spaceflight recording requirements are given for the Space Station Freedom, the Earth Observing System, and some planetary missions. SODR module characteristics are listed, emphasizing the two independent optical disk recorders and the random access to 5 gigabytes of data on each side of the disks. The modular design includes two I/O ports providing 150 Mbits/sec user data rate each, and multimodule reconfigurable architecture permitting the synchronization of up to 16 modules with a maximum data rate of 4.8 gigabits/sec.

Ravner, Stephen M.↗
NASA NTRS1993

Magnetic bearings for a high-performance optical disk buffer

An optical disk buffer concept can provide gigabit-per-second data rates and terabit capacity through the use of arrays of solid state lasers applied to a stack of erasable/reusable optical disks. The RCA optical disk buffer has evoked interest by NASA for space applications. The porous graphite air bearings in the rotary spindle as well as those used in the linear translation of the read/write head would be replaced by magnetic bearings or mechanical (ball or roller) bearings. Based upon past experience, roller or ball bearings for the translation stages are not feasible. Unsatisfactory, although limited experience exists with ball bearing spindles also. Magnetic bearings, however, appear ideally suited for both applications. The use of magnetic bearings is advantageous in the optical disk buffer because of the absence of physical contact between the rotating and stationary members. This frictionless operation leads to extended life and reduced drag. The manufacturing tolerances that are required to fabricate magnetic bearings would also be relaxed from those required for precision ball and gas bearings. Since magnetic bearings require no lubricant, they are inherently compatible with a space (vacuum) environment. Magnetic bearings also allow the dynamics of the rotor/bearing system to be altered through the use of active control. This provides the potential for reduced vibration, extended regions of stable operation, and more precise control of position.

Hockney, Richard↗
NASA NTRS1997

Electrical and Optical Performance Characteristics of 0.74-eV p/n InGaAs Monolithic Interconnected Modules

There has been a traditional trade-off in thermophotovoltaic (TPV) energy conversion development between system efficiency and power density. This trade-off originates from the use of front surface spectral controls such as selective emitters and various types of filters. A monolithic interconnected module (MIM) structure has been developed which allows for both high power densities and high system efficiencies. The MIM device consists of many individual indium gallium arsenide (InGaAs) cells series-connected on a single semi-insulating indium phosphide (InP) substrate. The MIM is exposed to the entire emitter output, thereby maximizing output power density. An infrared (IR) reflector placed on the rear surface of the substrate returns the unused portion of the emitter output spectrum back to the emitter for recycling, thereby providing for high system efficiencies. Initial MIM development has focused on a 1 sq cm device consisting of eight (8) series interconnected cells. MIM devices, produced from 0.74-eV InGaAs, have demonstrated V(sub oc) = 3.2 volts, J(sub sc) = 70 mA/sq cm, and a fill factor of 66% under flashlamp testing. Infrared (IR) reflectance measurements (greater than 2 micron) of these devices indicate a reflectivity of greater than 82%. MIM devices produced from 0.55-eV InGaAs have also been demonstrated. In addition, conventional p/n InGaAs devices with record efficiencies (11.7% AM0) have been demonstrated.

Wilt, David M.↗
NASA NTRS1997

Electrical and Optical Performance Characteristics of p/n InGaAs Monolithic Interconnected Modules

There has been a traditional trade-off in ThermoPhotoVoltaic (TPV) energy conversion development between system efficiency and power density. This trade-off originates from the use of front surface spectral controls such as selective emitters and various types of filters. A Monolithic Interconnected Module (MIM) structure has been developed which allows for both high power densities and high system efficiencies. The MIM device consists of many individual Indium Gallium Arsenide (InGaAs) devices series-connected on a single semi-insulating Indium Phosphide (InP) substrate. The MIMs are exposed to the entire emitter output, thereby maximizing output power density. An InfraRed (IR) reflector placed on the rear surface of the substrate returns the unused portion of the emitter output spectrum back to the emitter for recycling, thereby providing for high system efficiencies. Initial MIM development has focused on a 1 sq cm device consisting of eight (8) series interconnected cells. MIM devices, produced from 0.74eV InGaAs, have demonstrated V(sub infinity) = 3.2 volts, J(sub sc) = 70 mA/sq cm and a fill factor of 66% under flashlamp testing. IR reflectance measurements (greater than 2 microns) of these devices indicate a reflectivity of greater than 82%. MIM devices produced from 0.55 eV InGaAs have also been demonstrated. In addition, conventional p/n InGaAs devices with record efficiencies (11.7% AM0) have been demonstrated.

Wilt, David M.↗
NASA NTRS1991

Multichip imager with improved optical performance near the butt region

A compound imager consists of two or more individual chips, each with at least one line array of sensors thereupon. Each chip has a glass support plate attached to the side from which light reaches the line arrays. The chips are butted together end-to-end to make large line arrays of sensors. Because of imperfections in cutting, the butted surfaces define a gap. Light entering in the region of the gap is either lost or falls on an individual imager other than the one for which it is intended. This results in vignetting and/or crosstalk near the butted region. The gap is filled with an epoxy resin or other similar material which, when hardened, has an index of referaction near that of the glass support plate.

Kinnard, Kenneth P.↗
NASA NTRS1986

Diffraction-limited performance of grazing incidence optical systems

Diffraction effects of X-ray optical systems are often (justifiably) ignored due to the small wavelength of the X-ray radiation. However, the extremely large obscuration ratio inherent to grazing incidence optical systems produces a profound degradation of the diffraction image over that produced by a moderately obscured aperture of the same diameter. The contradictory requirements of large collecting area and relatively short length of optical elements has tended to result in proposed designs containing many concentric shells with increasingly higher obscuration ratios. In this paper it is shown that diffraction effects in such systems can significantly affect the achievable optical performance at the low energy (long wavelength) end of the intended operating spectral range. Parametric diffraction-limited performance predictions for both imaging and spectrographic applications will be presented and compared to AXAF performance goals and/or BBXRT fabrication techniques.

Harvey, James E.↗
NASA NTRS2015

Development of Flight Slit-Jaw Optics for Chromospheric Lyman-Alpha SpectroPolarimeter

In sounding rocket experiment CLASP, I have placed a slit a mirror‐finished around the focal point of the telescope. The light reflected by the mirror surface surrounding the slit is then imaged in Slit‐jaw optical system, to obtain the alpha‐ray Lyman secondary image. This image, not only to use the real‐time image in rocket flight rocket oriented direction selection, and also used as a scientific data showing the spatial structure of the Lyman alpha emission line intensity distribution and solar chromosphere around the observation area of the polarimetric spectroscope. Slit‐jaw optical system is a two off‐axis mirror unit part including a parabolic mirror and folding mirror, Lyman alpha transmission filter, the optical system magnification 1x consisting camera. The camera is supplied from the United States, and the other was carried out fabrication and testing in all the Japanese side. Slit‐jaw optical system, it is difficult to access the structure, it is necessary to install the low place clearance. Therefore, influence the optical performance, the fine adjustment is necessary optical elements are collectively in the form of the mirror unit. On the other hand, due to the alignment of the solar sensor in the US launch site, must be removed once the Lyman alpha transmission filter holder including a filter has a different part from the mirror unit. In order to make the structure simple, stray light measures Aru to concentrate around Lyman alpha transmission filter. To overcome the difficulties of performing optical alignment in Lyman alpha wavelength absorbed by the atmosphere, it was planned following four steps in order to reduce standing time alignment me. 1: is measured in advance refractive index at Lyman alpha wavelength of Lyman alpha transmission filter (121.567nm), to prepare a visible light Firuwo having the same optical path length in the visible light (630nm). 2: The mirror structure CLASP before mounting unit standing, dummy slit and camera standing prescribed position in leading frame is, to complete the internal alignment adjustment. 3: CLASP structure F mirror unit and by attaching the visible light filter, as will plague the focus is carried out in standing position adjustment visible flight products camera. 4: Replace the Lyman alpha transmission filter, it is confirmed by Lyman alpha wavelength (under vacuum) the requested optical performance have come. Currently, up to 3 of the steps completed, it was confirmed in the visible light optical performance that satisfies the required value sufficiently extended. Also, put in Slit‐jaw optical system the sunlight through the telescope of CLASP, it is also confirmed that and that stray light rejection no vignetting is in the field of view meets request standing.

Kubo, Masahito↗
NASA NTRS2015

Development of Flight Slit-Jaw Optics for Chromospheric Lyman-Alpha SpectroPolarimeter

In sounding rocket experiment CLASP, I have placed a slit a mirror-finished around the focal point of the telescope. The light reflected by the mirror surface surrounding the slit is then imaged in Slit-jaw optical system, to obtain the a-ray Lyman secondary image. This image, not only to use the real-time image in rocket flight rocket oriented direction selection, and also used as a scientific data showing the spatial structure of the Lyman alpha emission line intensity distribution and solar chromosphere around the observation area of the polarimetric spectroscope. Slit-jaw optical system is a two off-axis mirror unit part including a parabolic mirror and folding mirror, Lyman alpha transmission filter, the optical system magnification 1x consisting camera. The camera is supplied from the United States, and the other was carried out fabrication and testing in all the Japanese side. Slit-jaw optical system, it is difficult to access the structure, it is necessary to install the low place clearance. Therefore, influence the optical performance, the fine adjustment is necessary optical elements are collectively in the form of the mirror unit. On the other hand, due to the alignment of the solar sensor in the US launch site, must be removed once the Lyman alpha transmission filter holder including a filter has a different part from the mirror unit. In order to make the structure simple, stray light measures Aru to concentrate around Lyman alpha transmission filter. To overcome the difficulties of performing optical alignment in Lyman alpha wavelength absorbed by the atmosphere, it was planned 'following four steps in order to reduce standing time alignment me. 1. is measured in advance refractive index at Lyman alpha wavelength of Lyman alpha transmission filter (121.567nm), to prepare a visible light Firuwo having the same optical path length in the visible light (630nm).2. The mirror structure CLASP before mounting unit standing, dummy slit and camera standing prescribed position in leading frame is, to complete the internal alignment adjustment. 3. CLASP structure F mirror unit and by attaching the visible light filter, as will plague the focus is carried out in standing position adjustment visible flight products camera. 4. Replace the Lyman alpha transmission filter, it is confirmed by Lyman alpha wavelength (under vacuum) the requested optical performance have come. Currently, up to 3 of the steps completed, it was confirmed in the visible light optical performance that satisfies the required value sufficiently extended. Also, put in Slit-jaw optical system the sunlight through the telescope of CLASP, it is also confirmed that and that stray light rejection no vignetting is in the field of view meets request standing.

chromospheric↗
NASA NTRS2020

Orion Optical Navigation Performance and Testing

The Orion Optical Navigation System, which is designed to perform the navigation which will allow the crew to return safely to Earth in the event of a permanent loss of communications with the ground, has been matured through analysis and testing. This paper will detail the extensive tests and analysis that have gone into fleshing out the performance of the system in the face of numerous constraints placed on the optical navigation system.

D'Souza, Christopher↗
NASA NTRS1994

Optical Correlator Performs Novelty Filtering

Experimental real-time optical correlator performs correlation and novelty filtering in photorefractive crystal. Crystal oriented enabling cross-polarization diffraction: together with polarizing beam splitter, increases signal-to-noise ratio. Laser and optical components expand, collimate, and divide laser beam.

Liu, Duncan Tsuen-Hsi↗
NASA NTRS1974

Laser geodynamic satellite thermal/optical/vibrational analyses and testing. Volume 1: Executive summary

The results of the LAGEOS Thermal/Optical/Vibrational Analyses and test program conducted for the National Aeronautics and Space Administration are presented. The purpose of this study is to verify, through analysis and test, that the MSFC LAGEOS design inherently provides a retroreflector thermal environment which maintains acceptable retroreflector internal thermal gradients. Acceptable thermal gradients are those which result in less than 50% degradation of optical performance from isothermal optical performance. This volume provides an executive summary of the study program. It summarizes the study objectives, the study approach, the principal assumptions, the type of basic data generated and the significant results.

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