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At least 1,729 records · Page 96

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NASA NTRS1972

Thermal-optical properties of Fluorel L-3203-6 and 1059

Fluorel L-3203-6 and 1059 and four Fluorel derivatives were irradiated monochromatically and hemispherically with electromagnetic energy in the solar- and infrared-wavelength range to determine the thermal-optical properties that are required for engineering analysis. The thermal-optical properties were measured and analyzed, and the resulting data were tabulated for convenient engineering use. The results prove that the electromagnetic-energy distribution and the measured reflectance and transmittance of materials can be used to calculate several mean values, which are the total and hemispherical thermal-optical properties. The test results also illustrate that Fluorel effectively absorbs energy in the solar- and infrared-wavelength range. In addition, the results demonstrate that fabrication alters the thermal-optical properties of Fluorel.

French, B.↗

NASA NTRS1971

A compact and low power coherent optical system for on-board spacecraft data processing.

Discussion of the design and performance of a compact low-power coherent optical data processing system suitable for spacecraft onboard applications. The system is a modification of the conventional optical data processing system in which a much more efficient solid state GaAs laser is substituted for the bulky and inferior He-Ne laser and paraboloidal mirror segments are substituted for the axially symmetric optical system of the conventional data processing system. Theoretical considerations are given to substantiate the improvement of performance aimed at in the modified system. Preliminary tests of the modified design being in progress indicate that a low power, rugged, small size optical system, capable of onboard spacecraft data processing, can be constructed by using off-axis paraboloidal mirror segments.-

Husain-Abidi, A. S.↗

NASA NTRS1972

On the magnon interaction in haematite. I - Magnon energy of optical mode.

The effect of magnon interaction on the magnon energies of haematite was studied by the use of a recently developed random phase approximation. In this study, the spin Hamiltonian and the magnon energy were written in a power series of (1/S), where S denotes the magnitude of spin. It is known that the expression of magnon energy is rigorous up to the second term of this series. It is found that the optic mode energy is small if the free optic mode energy is small, which is contrary to Herbert's (1969) conclusion. This direct proportionality between the optic mode energy and the free optic mode energy was not confirmed in the higher order terms of 1/S.

Nagai, O.↗

NASA NTRS1973

Optical monitoring system

Instrument can measure optical transmission, reflectance, and scattering. This information can be used to identify changes in optical properties or deviations from required optical standards. Device consists of monochromatic source, photo detector, transfer mirror, and hemiellipsoid. System might be used to measure optical properties of thin film.

Nev, J. T.↗

NASA NTRS1972

Review of optical memory technologies

Optical technologies for meeting the demands of large capacity fast access time memory are discussed in terms of optical phenomena and laser applications. The magneto-optic and electro-optic approaches are considered to be the most promising memory approaches.

Chen, D.↗

NASA NTRS1972

Identification of the X-ray pulsar in Hercules: A new optical pulsar

A series of photographic, photoelectric, and spectroscopic observations beginning June 1, 1972 has led to the optical identification of Her X-1 (2U 1705 + 34), a pulsed X-ray source in an eclipsing binary system, with the thirteenth magnitude blue variable star HZ Herculis. The detection of optical pulses at the frequency of the X-ray pulsar on three nights makes the identification conclusive and establishes HZ Her as the second known optical pulsar. The strength of the optical pulses may be correlated with the orbital phase but is not obviously related to the high or low intensity states of the X-ray source.

Davidsen, A.↗

NASA NTRS1973

Investigation of uses of holographic optical elements

The data represent a thorough study of the aberrations and imaging properties of holographic optical elements. Principle studies include (1) the indepth experimental investigation of single holographic optical elements, (2) the verification of the accuracy of the theoretical computer-based description of hologram behavior, (3) the computer-generation of interferograms that are characteristic of a prescribed aberrated imaging condition, (4) the experimental verification of wavelength optimization, (5) the experimental determination of the space bandwidth product of single holographic optical elements as a function of bending and field angle, and (6) the first experimental study of the aberration properties of holographic optical elements constructed in very thick (750 microns) recording media.

Zech, R. G.↗

NASA NTRS1973

Electro-optical processing of phased array data

An on-line spatial light modulator for application as the input transducer for a real-time optical data processing system is described. The use of such a device in the analysis and processing of radar data in real time is reported. An interface from the optical processor to a control digital computer was designed, constructed, and tested. The input transducer, optical system, and computer interface have been operated in real time with real time radar data with the input data returns recorded on the input crystal, processed by the optical system, and the output plane pattern digitized, thresholded, and outputted to a display and storage in the computer memory. The correlation of theoretical and experimental results is discussed.

Casasent, D.↗

NASA NTRS1973

A survey of integrated optics with bibliography

The field of integrated optics is surveyed. Light coupling into films, modulation of light propagating in films, and current integrated optics developments and devices are discussed. It is concluded that integrated optics technology is expected to revolutionize the electronics industry as completely as did microcircuit technology. An extensive bibliography for the field of integrated optics is included.

Owen, R. B.↗

NASA NTRS1972

Optical computing.

Applications of the optical computer include an approach for increasing the sharpness of images obtained from the most powerful electron microscopes and fingerprint/credit card identification. The information-handling capability of the various optical computing processes is very great. Modern synthetic-aperture radars scan upward of 100,000 resolvable elements per second. Fields which have assumed major importance on the basis of optical computing principles are optical image deblurring, coherent side-looking synthetic-aperture radar, and correlative pattern recognition. Some examples of the most dramatic image deblurring results are shown.

Stroke, G. W.↗

NASA NTRS1975

Optical communication channel simulator system

Optical transmission link is simulated by positioning linear optical modulator between optical carrier source and receiver for carrier. Optical modulator is driven by analog signal, derived from analog computer circuit, having random variations indicative of characteristics of transmission link.

Fitzmaurice, M. W.↗

NASA NTRS1974

Interior radiances in optically deep absorbing media. 3: Scattering from Haze L

The interior radiances are calculated within an optically deep absorbing medium scattering according to the Haze L phase function. The dependence on the solar zenith angle, the single scattering albedo, and the optical depth within the medium is calculated by the matrix operator method. The development of the asymptotic angular distribution of the radiance in the diffusion region is illustrated through a number of examples; it depends only on the single scattering albedo and on the phase function for single scattering. The exact values of the radiance in the diffusion region are compared with values calculated from the approximate equations proposed by Van de Hulst. The variation of the radiance near the lower boundary of an optically thick medium is illustrated with examples. The attenuation length is calculated for various single scattering albedos and compared with the corresponding values for Rayleigh scattering. The ratio of the upward to the downward flux is found to be remarkably constant within the medium. The heating rate is calculated and found to have a maximum value at an optical depth of two within a Haze L layer when the sun is at the zenith.

Kattawar, G. W.↗

NASA NTRS1974

Thermally-restorable optical degradation and the mechanism of current transport in Cu2S-CdS photovoltaic cells

The photovoltaic properties of single-crystal Cu2S-CdS heterojunctions have been investigated as a function of heat treatment by detailed measurements of the dependence of short-circuit current on photon energy, temperature, and the state of optical degradation or enhancement. A coherent picture is formulated for the relationship between enhancement and optical degradation, and their effect on the transport of short-circuit photoexcited current and dark, forward-bias current in the cell. Optical degradation in the Cu2S-CdS cell is shown to be closely identical to optical degradation of lifetime in a homogeneous CdS:Cd:Cu crystal, indicating that the CdS:Cu layer near the junction interface controls carrier transport in the cell. It is proposed that both the photoexcited short-circuit current and the dark, forward-bias current are controlled by a tunneling-recombination process through interface states.

Fahrenbruch, A. L.↗

NASA NTRS1975

An optical radar for airborne use over natural waters

An optical radar for detecting targets in natural waters was built and tested in the Gulf of Mexico. The transmitter consists of a Q switched neodymium glass laser, with output amplified and doubled in KDP to 0.53 micrometer wavelength. The receiver incorporates a noval optical spatial filter to reduce the dynamic range required of the photodetector to a reasonable value. Detection of targets to a depth of 26 meters (84 feet) was achieved with a considerable sensitivity margin. The sensitivity of the radar is highly dependent on the optical attenuation coefficient. In general, measured returns fell between the values predicted on the basis of monopath and multipath attenuation. By means of simple physical arguments, a radar equation for the system was derived. To validate this theoretical model, measurements of optical attenuation and of water surface behavior were also instrumented, and some of these results are given.

Levis, C. A.↗

NASA NTRS1975

Reconciling the requirements of the science team and the spacecraft engineering team with a realizable optical system

Problems in the development of a suitable optical system for the imaging science payload of an interplanetary space probe are considered, taking into account the characteristics of the three categories of optical systems from which the engineer selects his system. These categories include the Catoptric or all mirror optical system, the Dioptric or all refracting optical system, and the Catadioptric system which combines elements of the other two categories. Examples of equipment selection and development in the preparation of a number of interplanetary space missions are discussed.

Larks, L.↗

NASA NTRS1976

Optical bias assembly

Assembly, used to achieve linear response in optical detection system, consists of tungsten lamp source, optical filters, fiber optics bundle, aperture mask, relay lens, and folding mirror. Tungsten lamp source provides sufficient background illumination to make input optical flux small compared to background.

Weagant, R.↗

NASA NTRS1976

Optical pulsations in HZ Herculis. 5. Pulse-resolved spectrophotometry

Digital spectra of HZ Herculis were obtained with 10 A resolution in the 3,600 - 6,000 A region, synchronously dividing the 1.24-s optical pulsation period into eight 155-ms phase bins. The optical pulses are detected in the data, but their fractional amplitude is only 0.08 percent, a factor of 4 less than typically observed. The separate spectra of each one-eighth of the pulse are identical to within the statistics of the observation. If the X-ray to optical pulse reprocessing mechanism concentrates the optical pulsations into discrete spectral line features, data require the pulses to be distributed among more than four such lines.

Margon, B.↗

NASA NTRS1976

The ion-optics of a two-grid electron-bombardment thruster

A detailed experimental investigation was performed to determine the ion-optical performance of an electron-bombardment ion thruster as a function of grid geometry changes. The results show that each geometrical grid parameter independently affects one aspect of ion-optical performance. These observations are used in developing a graphical technique to predict the ion-optical performance of an arbitrary ion source and grid geometry combination. The usefulness of this technique is demonstrated by comparing predicted ion-optical performance of the 30-cm diameter engineering model ion thruster with independent experimental determinations. Good agreement is shown between predicted and experimental results.

Aston, G.↗