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  • Other Sources  (11)
  • 1975-1979  (11)
  • 1
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    A coherent optical feedback system for optical information processing (1975)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: A unique optical feedback system for coherent optical data processing is described. With the introduction of feedback, the well-known transfer function for feedback systems is obtained in two dimensions. Operational details of the optical feedback system are given. Experimental results of system applications in image restoration, contrast control and analog computation are presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Physics; 8; Sept
    Format: text
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  • 2
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    Optical computing with laser light (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Linear and nonlinear optical processing techniques (Fourier transformation, convolution and correlation, arithmetic operations - addition and subtraction with gratings, generalized orthogonal transformations; theta modulation, half-tone screen process, optical feedback) for mathematical computations are reviewed. The use of gratings and computer holograms in addition, subtraction, differentiation, and application of generalized transformations is discussed. Use of nonlinear optical elements with or without optical coherent feedback in such nonlinear operations as taking logarithms and thresholding is described. Applications in hybrid systems incorporating digital computer and optical processor with real-time interface devices, or optical threshold and logic devices for parallel processing to apply digital techniques to optical information are considered.
    Keywords: COMPUTER OPERATIONS AND HARDWARE
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  • 3
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    The application of an optical Fourier spectrum analyzer on detecting defects in mass-produced satellite photographs (1976)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Various defects in mass-produced pictures transmitted to earth from a satellite are investigated. It is found that the following defects are readily detectable via Fourier spectrum analysis: (1) bit slip, (2) breakup causing loss of image, and (3) disabled track at the top of the imagery. The scratches made on the film during mass production, which are difficult to detect by visual observation, also show themselves readily in Fourier spectrum analysis. A relation is established between the number of scratches, their width and depth and the intensity of their Fourier spectra. Other defects that are found to be equally suitable for Fourier spectrum analysis or visual (image analysis) detection are synchronous loss without blurring of image, and density variation in gray scale. However, the Fourier spectrum analysis is found to be unsuitable for detection of such defects as pin holes, annotation error, synchronous loss with blurring of images, and missing image in the beginning of the work order. The design of an automated, real time system, which will reject defective films, is treated.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-148198
    Format: application/pdf
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  • 4
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    Optically activated switch/modulator using a photoconductor and two channel waveguides (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: An optically activated switch was fabricated on LiNbO3 substrate by deposition of photoconductor-metal electrode structure on two channel waveguides obtained by the outdiffusion process. One waveguide was overcoated with a CdS film, and served as a light detector which converted the optical signal in that waveguide into an electric signal. Utilizing the electrooptic effect, this electric signal modulated the light propagating in the second waveguide by changing the refractive index, and the cutoff condition, of the waveguiding channel between two metal electrodes. The waveguides in the optically controlled switch can be either single or multimode. The length of the device can be short in comparison with other switching schemes. When binary optical signals are applied to the two waveguides, the switch can perform logic AND, NEGATION, OR and pseudo-amplification operations.
    Keywords: OPTICS
    Type: Radio Science; 12; July-Aug
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  • 5
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    Two improved coherent optical feedback systems for optical information processing (1976)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Coherent optical feedback systems are Fabry-Perot interferometers modified to perform optical information processing. Two new systems based on plane parallel and confocal Fabry-Perot interferometers are introduced. The plane parallel system can be used for contrast control, intensity level selection, and image thresholding. The confocal system can be used for image restoration and solving partial differential equations. These devices are simpler and less expensive than previous systems. Experimental results are presented to demonstrate their potential for optical information processing.
    Keywords: COMPUTER OPERATIONS AND HARDWARE
    Type: Seminar on Optical information processing: Real-time devices and novel techniques; Aug 24, 1976 - Aug 25, 1976; San Diego, CA
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  • 6
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    Comparison of modal test results - Multipoint sine versus single-point random (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The Mariner Jupiter/Saturn (MJS) spacecraft was subjected to the traditional multipoint sine dwell (MPSD) modal test using 111 accelerometer channels, and also to single-point random (SPR) testing using 26 accelerometer channels, and the two methods are compared according to cost, schedule, and technical criteria. A measure of comparison between the systems was devised in terms of the cumulative difference in the kinetic energy distribution of the common accelerometers. The SPR and MPSD method show acceptable agreement with respect to frequencies and mode damping. The merit of the SPR method is that the excitation points are minimized and the test article can be committed to other uses while data analysis is performed. The MPSD approach allows validity of the data to be determined as the test progresses. Costs are about the same for the two methods.
    Keywords: GROUND SUPPORT SYSTEMS AND FACILITIES (SPACE)
    Type: SAE PAPER 760879 , Aerospace Engineering and Manufacturing Meeting on Cyclic structural analyses of air-cooled gas turbine blades and vanes; Nov 29, 1976 - Dec 02, 1976; San Diego, CA
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  • 7
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    Contrast enhancement of transparencies (1976)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: System can enhance or reduce contrast of photographic transparency for printing or projection by using constructive and destructive interference of collimated laser beam. System is potentially less expensive than electronic CRT methods and is more accurate than trial-and-error manual techniques.
    Keywords: PHYSICAL SCIENCES
    Type: GSC-11989 , NASA Tech Briefs (ISSN 0145-319X); 1; 2; P. 190
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  • 8
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    Studies in optical parallel processing (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Threshold and A/D devices for converting a gray scale image into a binary one were investigated for all-optical and opto-electronic approaches to parallel processing. Integrated optical logic circuits (IOC) and optical parallel logic devices (OPA) were studied as an approach to processing optical binary signals. In the IOC logic scheme, a single row of an optical image is coupled into the IOC substrate at a time through an array of optical fibers. Parallel processing is carried out out, on each image element of these rows, in the IOC substrate and the resulting output exits via a second array of optical fibers. The OPAL system for parallel processing which uses a Fabry-Perot interferometer for image thresholding and analog-to-digital conversion, achieves a higher degree of parallel processing than is possible with IOC.
    Keywords: OPTICS
    Type: NASA-CR-158237
    Format: application/pdf
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  • 9
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    Method and apparatus for producing an image from a transparent object (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The contrast produced from a photographic transparency is controlled by placing the transparency between a pair of partially reflecting mirrors forming walls of an optical cavity. Mirrors trap a collimated laser beam illuminating the transparency so that at least a portion of the beam energy is passed through the transparency plural times. The distance that the light beam travels between the mirrors is controlled as a function of the wavelength of the beam energy to control the phase of light interference in the beam passing through the transparency, thereby controlling the intensity of the beam derived from the mirror downstream of the transparency.
    Keywords: OPTICS
    Format: application/pdf
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  • 10
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    Comparison of modal test methods on the Voyager payload (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A comparison of the performance of modern modal data analysis methods on test data from the Voyager Jupiter/Saturn payload is presented. Four different test/data-analysis combinations are compared - multiple-point sine excitation tests, single-point random-excitation tests using two different techniques of manipulating Fourier transform data, and a time-domain method for analyzing random data. Results indicate that all four methods can give comparable results. Of the four, the time-domain approach detects more modes in the test data and, at the same time, shows the greatest promise for reducing the time and cost of modal testing.
    Keywords: GROUND SUPPORT SYSTEMS AND FACILITIES (SPACE)
    Type: SAE PAPER 781044 , Society of Automotive Engineers, Aerospace Meeting; Nov 27, 1978 - Nov 30, 1978; San Diego, CA
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