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  • INSTRUMENTATION AND PHOTOGRAPHY  (51)
  • 1980-1984  (51)
  • 1950-1954
  • 1930-1934
  • 1982  (51)
  • 11
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    Dual-wavelength correlation measurements with an airborne pulsed carbon dioxide lidar system (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Dual-wavelength correlation data are presented for ground-level and airborne measurements of topographic and ocean backscatter near the 9.5-micron wavelength. Data were acquired with a pulsed carbon dioxide, dual-laser, dual-wavelength lidar system. The best system performance gave a dual-wavelength uncorrelated noise component of 2.8% and 9% standard deviation for ground-based and airborne data, respectively. This sets one limit on lidar measurement accuracy with a single pulse pair.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optics Letters; 7; Dec. 198
    Format: text
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    NASA TECHNICAL REPORTS
  • 12
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    Radiation effects in IRAS extrinsic infrared detectors (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: During the calibration and testing of the Infrared Astronomy Satellite (IRAS) focal plane, it was observed that the extrinsic photoconductor detectors were affected by gamma radiation at dose levels of the order of one rad. Since the flight environment will subject the focal plane to dose levels of this order from protons in single pass through the South Atlantic Anomaly, an extensive program of radiation tests was carried out to measure the radiation effects and to devise a method to counteract these effects. The effects observed after irradiation are increased responsivity, noise, and rate of spiking of the detectors after gamma-ray doses of less than 0.1 rad. The detectors can be returned almost to pre-irradiation performance by increasing the detector bias to breakdown and allowing a large current to flow for several minutes. No adverse effects on the detectors have been observed from this bias boost, and this technique will be used for IRAS with frequent calibration to ensure the accuracy of observations made with the instrument.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 13
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    Analysis of DSN PPM support during Voyager 2 Saturn encounter (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The precision power monitor (PPM) is a precision radiometric instrument used to improve the efficiency of signal reception by the Deep Space Network. Real time estimates of the system operating temperature, the present (signal + noise)-to-noise ratio, and the signal power are utilized to increase the accuracy and resolution of the received spacecraft signal. Due to the critical nature of radio science data returning from Voyager 2 at Saturn Encounter, PPM support was required. The task was undertaken to validate the performance of equipment technically under research and development in time to meet the encounter deadline. Initial studies revealed PPM performance to be out of tolerance. Action was immediately taken to identify the system problems. Using data analysis as feedback, the system failures were identified and corrected in time to contribute to the encounter support efforts. As a result, the radio science data were collected successfully.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Telecommun. and Data Acquisition Rept.; p 139-150
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    NASA TECHNICAL REPORTS
  • 14
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    Light ion mass spectrometer for space-plasma investigations (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Direct satellite measurements and ground-based techniques have given a comprehensive view of the density distribution of the cold plasma population in the earth's magnetosphere. There were, however, no direct measurements of the low-energy plasma mass composition, temperature, density, pitch-angle distribution, or plasma flow velocity. A description is presented of the evolution and development of an instrument, the Light Ion Mass Spectrometer (LIMS), designed to make these low-energy plasma measurements. The instrument was developed for flight on the spacecraft SCA-THA, a satellite to study satellite charging at high altitudes. This satellite, whose primary mission was to study spacecraft-plasma interactions and electrostatic charging, was launched into a near-geosynchronous orbit. The design requirements regarding the instrument are discussed, and attention is given to the calibration procedures, the flight configuration, and some examples of flight data.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 53; Apr. 198
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  • 15
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    Measurement of the dispersive and refractive indices of germanium using diode lasers (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Germanium Fabry-Perot etalons are commonly used in diode laser spectroscopy to establish relative frequency calibration scales for molecular absorption spectra. Typically the channel spectrum of the etalon is recorded simultaneously with the molecular spectrum as the laser injection current is tuned linearly, and the etalon free spectral range (fringe spacing) is used to measure the frequency separations among lines in the molecular spectrum. For this purpose, the etalon free spectral range must be known for the measurement wavelength, and this in turn relies on knowledge of the etalon length and the dispersive index at this wavelength. It is pointed out that the most satisfactory approach is to measure directly the free spectral range or dispersive index of the etalon at the wavelength of interest. A description is presented of measurements of this type, performed near 7.9 and 10.1 micrometers for a 7.7-cm long germanium etalon.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 21; Sept. 15
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  • 16
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    Color visualization for fluid flow prediction (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: High-resolution raster scan color graphics allow variables to be presented as a continuum, in a color-coded picture that is referenced to a geometry such as a flow field grid or a boundary surface. Software is used to map a scalar variable such as pressure or temperature, defined on a two-dimensional slice of a flow field. The geometric shape is preserved in the resulting picture, and the relative magnitude of the variable is color-coded onto the geometric shape. The primary numerical process for color coding is an efficient search along a raster scan line to locate the quadrilteral block in the grid that bounds each pixel on the line. Tension spline interpolation is performed relative to the grid for specific values of the scalar variable, which is then color coded. When all pixels for the field of view are color-defined, a picture is played back from a memory device onto a television screen.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Mechanical Engineering; 104; Mar. 198
    Format: text
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  • 17
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    Energetic ion mass spectrometer (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A new type of spectrometer for space application has been developed to measure separately mass/charge and the three-dimensional velocity distribution of incident ions. The instrument has relatively high resolution and allows rapid measurement of the four-dimensional set of mass/charge, speed, elevation angle, and azimuth angle. The instrument includes a sector magnet, an electrostatic deflector, microchannel plate detectors with position sensitive readout, and a set of grids with variable applied voltage.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 53; Mar. 198
    Format: text
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  • 18
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    Application of the laser Doppler velocimeter in aerodynamic flows (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Applications of the laser doppler velocimeter (LDV) are discussed. Measurements were made of the flowfield around a tangent-ogive model in a low turbulent, incompressible flow at an incidence of 45 deg. The free-stream velocity was 80 ft per second. The flowfield velocities in several cross-flow planes were measured with a 2-D, two-color LDC operated in a backscatter mode. Measurements were concentrated in the secondary separation region. A typical survey is given. The survey was taken at a model location where the maximum side force occurs. The overall character of the leeward flowfield with the influence of the two body vorticles are shown. Measurements of the velocity and density flowfields in the shock-layer region of a reentry-vehicle indented nose configuration were carried out at Mach 5. The velocity flowfield was measured with a 2-color, 2-D, forward-scatter LDV system. Because of the need to minimize particle lag in the shock-layer region, polystyrene particles with a mean diameter of 0.312 microns were used for the scattering particles. The model diameter was 6 inches.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 295-302
    Format: application/pdf
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  • 19
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    Development of a laser velocimeter for a large transonic wind tunnel (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: On a 8 x 6 Foot Supersonic Wind Tunnel a laser velocimeter was utilized in the testing of advanced high speed turbopropellers. The system, using a 15-W argon-ion laser, a 3-beam 2-axis transmitting-receiving optics package, a zoom lens with 1- to 4-m focal lengths, and a 0.4-m corner mirror was initially assembled and tested in the checkout room. During the time the system was located in the checkout area, experience was acquired in the alignment and operation of the system and the data acquisition system and software were developed. By using air jets to simulate tunnel air flow, the system worked quite well. However, problems with beam alignment arose because of reduced atmospheric pressure. Mounting the laser into a vessel maintained at atmospheric pressure with deflectors mounted to the external walls improved operation for about 2 hours before misalignment reoccurred. The system was remounted to the positioning platform in an enclosure that provides both thermal and acoustic isolation.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 243-247
    Format: application/pdf
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  • 20
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    Holographic flow visualization: State-of-the-art overview (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Components and system designs of holographic flow visualization techniques are reviewed. Recording materials, lasers, and data processing and display are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 149-158
    Format: application/pdf
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