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  • INSTRUMENTATION AND PHOTOGRAPHY
  • 1980-1984  (506)
  • 1975-1979
  • 1965-1969
  • 1945-1949
  • 1983  (258)
  • 1981  (248)
Collection
Keywords
Years
  • 1980-1984  (506)
  • 1975-1979
  • 1965-1969
  • 1945-1949
Year
  • 1
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    Si:Bi array detectors and astronomical applications of the Goddard 10 micron camera (1983)
    In:  CASI
    Details
    Publication Date: 2004-12-04
    Description: An improved 4 to 18 micron array camera system was developed at NASA Goddard SFC for astronomical photometry, using an Aerojet Electro Systems Corp. 16 x 16 Si:Bi accumulation mode charge injection device (AMCID) which could be suitable for eventual low-background spaceflight applications. An astronomical observing program using this device was carried out as a collaboration between NASA Goddard (Infrared and Radio Astronomy Branch and Micro Electronics Branch), the Harvard/Smithsonian Center for Astrophysics, and Steward Observatory of the University of Arizona. In 1983 the camera system was revised, and a new Aeroject Si:Bi array with 16 x 16 active pixels was obtained from NASA/Ames Research Center as part of a new scientific collaboration between the Ames and Goddard infrared array research groups. The 16 x 16 device had sufficiently good sensitivity, uniformity and noise characteristics to be used for successful observations at the Mt. Lemmon 60 and 61 inch telescopes in May 1983. Complete laboratory characterization of the 16 x 16 array was carried out in summer of 1983. Initial results indicate that this detector has sensitivity and noise characteristics comparable to other devices from the same generation of Aerojet arrays.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Ames Research Center, Infrared Detector Technology Workshop; 12 p
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  • 2
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    Active cavity radiometer (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: The active cavity radiometer (ACR) experiment on the Spacelab 1 mission to measure the total solar irradiance is discussed. Short and long term variations in the total solar output of optical energy are studied. Solar total irradiance observation provides information on the solar cycle and other long term trends in solar output that are of climatological significance as well as short term solar physics phenomena. The interaction of solar radiation with the Earth's atmosphere, oceans, and land masses provides the primary driving forces for the formation of weather systems and the determination of climate. Astrophysical measurements determine the total energy flux. The principal role of the ACR observations support extended solar irradiance experiments on free flying satellites. Solar irradiance measurements are important in the establishment of the radiation scale at the solar total flux level in the international system of units (SI).
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 4 p
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  • 3
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    Very wide field camera (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: The study of galactic and faint extragalactic extended sources and peculiar ultraviolet objects by a very wide field of view camera, operated in the ultraviolet photometric and spectrometric modes is discussed. The photometric mode is direct photography through filters for observation of the following sources: (1) large scale distribution of ultraviolet radiation in the Milky Way; (2) diffusion of the galactic light above the galactic plane and in front of the large absorbing clouds; (3) the optical emission of the interstellar matter; (4) stars, and starlike objects with diameters less than 3 arc minutes. In the spectrometric mode (nebular spectrograph) the light from the center of the photometric field is concentrated on a slit covering 10 degrees by 10 arc minutes on the sky.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 3 p
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  • 4
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    Personal miniature electrophysiological tape recorder (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-05
    Description: The use of a personal miniature electrophysiological tape recorder to measure the physiological reactions of space flight personnel to space flight stress and weightlessness is described. The Oxford Instruments Medilog recorder, a battery-powered, four-channel cassette tape recorder with 24 hour endurance is carried on the person and will record EKG, EOG, EEG, and timing and event markers. The data will give information about heart rate and morphology changes, and document adaptation to zero gravity on the part of subjects who, unlike highly trained astronauts, are more representative of the normal population than were the subjects of previous space flight studies.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 2 p
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  • 5
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    Metric camera experiment (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: A test of the mapping capabilities of high resolution space photography taken at the resolution limit of image motion on large film format is planned. The metric camera system and its planned operation are described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 4 p
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  • 6
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    Waves in the OH emissive layer (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: Photography and measurement of cloud-like structures of bright parallel bands observed in near infrared photography of the night sky is planned. The instrument is described and the purpose of the experiment summarized.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 2 p
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  • 7
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    Grille spectrometer (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: High resolution infrared spectroscopic observations of the Earth's limb in the wavelength range characteristic of the vibrational-rotational lines of trace atmospheric constituents is planned. The instrument and its operation and the purpose of the experiments are summarized.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 3 p
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  • 8
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    An automatic light scattering CCN counter (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The counter is a static thermal diffusion chamber which has been modified to include an optical system for the determination of droplet concentration by the measurement of scattered light. The determination of concentration is made by measurement of the peak scattered light signal from the cloud of growing droplets which is a function of both the droplet concentration and chamber supersaturation. Because the formation of the peak is related to the rate of growth of the droplets and sedimentation, both of which are determined by supersaturation, the system calibration can be uniquely determined by comparison with an absolute counter such as a static diffusion chamber with a photographic recording system.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 40-41
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  • 9
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    Cloud condensation nucleus counter by impactor sampling technique (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Unlike typical CCN counters, this device counts the numbers of water droplets condensed on aerosol particles sampled on a microcover glass at various different relative humidities. The relative humidities ranged from 75 percent to a calculated value of 110 percent. A schematic of the apparatus is shown. The individual CCN can be identified in an optical micrograph and scanning electron micrograph and may be inspected for their chemical composition later.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 35-36
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  • 10
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    The CCN counter of the IOPG of Puy de Dome: Main characterisics and results of measurements (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: In performing the data analysis of the measurements achieved during the Workshop with the device, a global approach was preferred rather than an individual analysis, in order to illustrate some main characteristics in the behavior of the device with respect to a mean behavior resulting from a general survey of all the equipments involved in each experiment. The device tends generally to overestimate the CCN concentrations measured near the high supersaturations and sometimes underestimates the concentrations close to 0.1% or 0.2% of supersaturation. Despite the fact that it belongs to a type of static diffusion chamber, it shows, however, similar spectra to those obtained with other types of chambers (continuous flow diffusion chamber and haze chamber).
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 17-19
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  • 11
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    Contribution to CCN Workshop report from University of Wyoming group (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The group's CCN counter is described. It is a static, horizontal, parallel plate thermal gradient diffusion chamber. Examples of the application of the CCN are presented and include the CCN spectra measured during the winter of 1978-79 near Elk Mountain, Wyoming. Comparisons of droplet concentrations derived from upwind CCN spectra are covered.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 11-13
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  • 12
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    Measurement of the aerosol size distribution with NRL's mobility analyzer (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The size distribution was measured in the size range between 0.0057 and 0.57 micrometer radius. A description of the instrumentation and data analysis is given, together with the measured size distributions calculated for 23 experiments.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 69-78
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  • 13
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    Modified MEE Industries static thermal gradient diffusion cloud chamber (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The experiments performed at the Workshop were undertaken to confirm the calculated sample volume, determine the usable range of supersaturation, and minimum detectable size. Comparison of absolute CCN concentrations with other state-of-the-art continuous flow diffusion chambers at supersaturations near 1 percent indicated that the volume used produced CCN concentrations well within the range of CCN concentrations determined at the workshop. This agreement is interpreted to mean the sample volume was correct. Direct measurements of the beam geometry done in the laboratory indicated a factor of 4-5 error. This error is apparently due to the larger apparent visible beam diameter versus the actual usable beam diameter given the droplet illumination, chamber optical geometry, microscope optics and film characteristics.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 44-45
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  • 14
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    Multi-channel chopper system for a total ozone mapping spectrometer (1981)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A multi-channel chopper system designed and built to stringent specifications is providing an excellent performance for a total ozone mapping spectrometer (TOMS). State of the art machining technology, suitable material selection, and a way to hold and position the slit plate resulted in the instrument's better than expected performance. A shutter method used for internal calibration allows compensation for the occurrence of an unlikely wavelength shift during testing, launch, or during the orbiting life of the instrument. The TOMS is part of a payload on Nimbus 7 launched on October 24, 1978.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Marshall Space Flight Center The 15th aerospace Mech. Symp.; p 63-75
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  • 15
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    Description of the NRL isothermal haze chamber (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: In the IHC the critical supersaturation is inferred from the measurement of the size of particles which have grown to their equilibrium size at exactly 100 percent RH. The largest size channel corresponds to a critical supersaturation of 0.014 percent. The growth time required for particles of this size to reach their equilibrium size exceeds the 110 second residence time in the IHC. Since the supersaturation spectrum is always very steep in this region, the contribution of these larger particles which have not yet attained their equilibrium size to smaller size channels is negligible. However, failure of these particles to reach their equilibrium size could result in a significant lowering of the count in the size channel corresponding to the smaller critical supersaturation.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 42-43
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  • 16
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    Static diffusion cloud chambers (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The chamber geometry and optical arrangement are described. The supersaturation range is given and consists of readings taken at five fixed points: 0.25%, 0.5%, 0.75%, 1.0%, and 1.25%. The detection system is described including light source, cameras, and photocell detectors. The temperature control and the calibration of the chamber are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 26-27
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  • 17
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    Description and discussion of the NRL TGDCC (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The NRL thermal gradient diffusion cloud chamber (TGDCC) consists of two plates 7.5 cm in diameter separated by 1.25 cm and covered with saturated filter paper. The cylindrical wall separating the plates is glass. The top plate is at room temperature and the bottom plate is cooled with a thermoelectric cooler. The temperature difference is measured with several sets of thermocouples. The CCN concentration was determined from the video recording. This procedure of averaging the maximum count obtained on several successive recordings at the same supersaturation results in concentrations which are somewhat higher than concentrations calculated from an average across the plateau.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 14-16
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  • 18
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    Comparing dry aerosol size measurements (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Two instruments were used to size dry aerosols for the CCN experiments: the Naval Research Laboratory (NRL) instrument which uses an electrical mobility analyzer to separate the aerosol size fractions and a diffusion chamber to grow and count the particles and the University of Wyoming (WYO) aerosol monitoring system. Measurements from these two systems were usually found to be in agreement during the CCN Workshop. Two examples are presented to compare aerosol size distribution measurements of the two instruments: experiment 8 (monodisperse NaCl) and experiment 27 (polydisperse AgI). Differential (dN/dR) and cumulative plots are shown for both instruments for experiment 8 and experiment 27; also shown are Aitken particle measurements for comparison.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 106-107
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  • 19
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    CCN comparisons of static diffusion chambers (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Nine CCN counters of the static diffusion (SDC) type were compared with one another and with continuous flow diffusion (CFD) chambers. The nine SDCs showed a considerable amount of variation, largely attributable to newness and/or lack of prior calibration of some units. The five more consistent instruments agreed quite well, to within at least 20 percent of the NRL mobility analyzer and to within 10 percent at 1 percent supersaturation. There was satisfactory agreement between the more reliable SDC and CFD chambers.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 57-63
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  • 20
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    Diffusion tube (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The diffusion tube was designed to operate below about 0.25 percent of water supersaturation. It is simply a long tube lined on the inside with a damp chamois cloth, and heated isothermally to a few degrees centigrade above the incoming air. The diffusion coefficient for water vapor is slightly larger than that for heat, making it possible to supersaturate the airflow. This is the same principle by which transient supersaturations may occur in parallel plate cloud chambers. Only the diffusion of vapor and heat from the walls into the moving air are considered.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 37-39
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  • 21
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    A description of the UK Meteorological Office CCN counter (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The chamber is a thermal gradient diffusion type with the upper plate at room temperature and the lower plate thermoelectrically cooled. The light from a 25W projector bulb is focused in a beam of approximations 1x3 mm in the central part of the chamber. The light scattered by drops is viewed in the forward direction (40 deg) by a microscope and a sensitive photodetector. Experiments were performed to relate the peak output from the photocell with the maximum number of drops in the beam recorded photographically. The microscope is used to check the calibration at low concentrations of CCN. The results of the experiments and the performance of the counter are reported.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Desert Research Inst. The Third Intern. Cloud Condensation Nuclei Workshop; p 33-34
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  • 22
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    Heterodyne frequency measurements and frequency calibration standards for tunable diode lasers (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: New frequency calibration tables are required to keep abreast of the resolution attainable by currently available tunable lasers. One key to the generation of tables with requisite accuracy involves accurate heterodyne frequency measurements; another key consists of reliable fitting and analysis. Coordinated activity in NBS involves selection of suitable molecular calibration candidates, their frequency measurement and analysis, and dissemination of the results in the form of frequency calibration tables. Current status of these efforts is described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 23
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    Optogalvanic photodetachment spectroscopy (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A new extension to optogalvanic spectroscopy, in which electrons detached from negative ions formed in the discharge are observed as a function of incident laser wavelength, has been developed. The determination of the electron affinities of I(-) and Cl(-) atomic ions is described. The potential of the technique for studying the spectroscopy of molecular negative ions is also discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal de Physique (ISSN 0449-1947); 44; C7-461 t
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  • 24
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    Nd:YAG holographic interferometer for aerodynamic research (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A holographic interferometer system has been installed in the NASA Ames 2- by 2-Foot Transonic Wind Tunnel. The system incorporates a modern 10 pps, Nd:YAG pulsed laser which provides reliable operation and is easy to align. The spatial filtering requirements of the unstable resonator beam are described, as well as the integration of the system into the existing schlieren system. A two-plate holographic interferometer is used to reconstruct flow field data. For static wind tunnel models, the single exposure holograms are recorded in the usual manner; however, for dynamic models such as oscillating airfoils, synchronous laser hologram recording is used.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 25
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    Differential absorption lidar technique for measurement of the atmospheric pressure profile (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A new two-wavelength lidar technique for remotely measuring the pressure profile using the trough absorption region between two strong lines in the oxygen A band is described. The theory of integrated vertical path, differential ranging, and horizontal-path pressure measurements is given, with methods to desensitize and correct for temperature effects. The properties of absorption troughs are described and shown to reduce errors due to laser frequency jitter by up to two orders of magnitude. A general analysis, including laser bandwidth effects, demonstrates that pressure measurements with an integrated-vertical-path technique are typically fifty times more accurate than with a differential ranging technique. Simulations show 0.1-0.3 percent accuracy for ground and Shuttle-based pressure-profile and surface-pressure experiments.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; 3759-377
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  • 26
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    Airborne detection of oceanic turbidity cell structure using depth-resolved laser-induced water Raman backscatter (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Airborne laser-induced, depth-resolved water Raman backscatter is useful in the detection and mapping of water optical transmission variations. This test, together with other field experiments, has identified the need for additional field experiments to resolve the degree of the contribution to the depth-resolved, Raman-backscattered signal waveform that is due to (1) sea surface height or elevation probability density; (2) off-nadir laser beam angle relative to the mean sea surface; and (3) the Gelbstoff fluorescence background, and the analytical techniques required to remove it. When converted to along-track profiles, the waveforms obtained reveal cells of a decreased Raman backscatter superimposed on an overall trend of monotonically decreasing water column optical transmission.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; 3778-378
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  • 27
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    Low-power portable geophysical data acquisition system and its use in geomagnetic measurements (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A low-power portable data acquisition system presently in use for geomagnetic measurements is described. The system is composed of a data-processing system containing a low-power microprocessor, a 9-track digital tape recorder, and a rechargeable battery pack. The magnetometer is a low-power three axis fluxgate design. Under program control the data processing system keeps track of time of day and date, samples three analog magnetometer outputs at intervals of either 0.4 or 2 s, digitizes the data to 15-bit resolution, and, depending upon relative magnetic activity, decides upon data compression to increase the tape storage capacity. It also monitors and records internal voltages and provides self-checking functions which may be monitored through a visual readout on the control panel. The system is mounted in a rugged, weather-tight carrying case suitable for use outdoors with minimal protection. The system, including magnetometer, uses 1.6-W power and can store 5.7 Mbytes of data.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Transactions on Geoscience and Remote Sensing; GE-19; July 198
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  • 28
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    Nuclear Science Symposium, 27th, and Symposium on Nuclear Power Systems, 12th, Orlando, Fla., November 5-7, 1980, Proceedings (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Advances in instrumentation for use in nuclear-science studies are described. Consideration is given to medical instrumentation, computerized fluoroscopy, environmental instrumentation, data acquisition techniques, semiconductor detectors, microchannel plates and photomultiplier tubes, reactor instrumentation, neutron detectors and proportional counters, and space instrumentation.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 29
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    Performance of room temperature mercuric iodide /HgI2/ detectors in the ultralow-energy X-ray region (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Experiments have been done to study the performance of mercuric iodide (HgI2) detectors in the ultralow-energy X-ray region. Energy resolution values of 245 eV (FWHM) for the Mg K-alpha X-ray line at 1.25 keV and 225 eV (FWHM) for the electronic noise linewidth have been obtained for an HgI2 detector with painted carbon contacts using a pulsed-light feedback preamplifier; the whole system was operated at room temperature. The resolution values in the ultralow-energy region are still limited by electronic noise of the system. In an attempt to minimize X-ray attenuation in the front contact, detectors were prepared with thin evaporated Pd contacts. These detectors show a pronounced low-energy tailing of the photopeak below a few keV, in contrast to the spectra obtained by detectors with carbon contact. An attempt has been made to explain the tailing effect starting with models wich have been proposed to describe similar effects in Ge detectors.
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  • 30
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    Response of large cavity ion chambers to space protons (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The assumption that spherical-shell ion chamber rssponse is equal to the dose in the center of the cavity is found to be a poor approximation for ion chambers used for area monitoring in the space program. The dose response is calculated using the appropriate areal density distribution function. Effects of nuclear reaction are evaluated using proton buildup factors. Errors of up to 100% are found for some components of the space radiation environments.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Nuclear Technology; 52; 1, Ja; Jan. 198
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  • 31
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    Description and overview of an instrument designed to measure line-of-sight delay due to water vapor (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Eight dual channel microwave radiometers were constructed as a research and development effort for the Crustal Dynamics Project and the Deep Space Network. These instruments, known as water vapor radiometers, are primarily intended to demonstrate that the variable path delay imposed by atmospheric water vapor can be calibrated in microwave tracking and distance measuring systems but could also be used in other applications involving moist air meteorology and propagation studies. They are being deployed to various stations and observatories that participate in Very Long Baseline Interferometry experiments. The development history of these instruments are reviewed, the theory of operation and overall design considerations are outlined, and the instrumental parameters and performance characteristics are described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Telecommun. and Data Acquisition Rept.; p 1-19
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  • 32
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    Deviation-free Bragg cell frequency-shifting (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A method is described of applying a variable frequency-shift to a laser beam, by means of Bragg cells, in which the direction of the output diffracted beam is unaffected by the magnitude of the applied shift. Applications of the technique to reference-beam and Doppler-difference forms of laser anemometry are discussed together with methods of obtaining increased dynamic range.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 20; Feb. 15
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    Selection of fluorescence lidar operating parameters for SNR maximization (1981)
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    Publication Date: 2011-08-18
    Description: Fluorescence lidar when applicable offers one of the most sensitive methods for measuring the concentration of trace constituents of the atmosphere. In the conduct of a fluorescence lidar experiment, a number of parameters which can be used to optimize the SNR can be controlled. In this paper the optimum division of laser pulses centered on and off the fluorescence excitation wavelength is calculated as a function of the ratio of the fluorescence signal strength to the strength of fluorescence from interfering species. For strong interference signals the time should be divided equally on and off the line. For strong fluorescence signals the time on line is proportional to the square root of the on-line off-line signal ratio. The optimization of the integration time for varying values of signal-to-background and signal-to-interference ratios, atmospheric attenuation, laser energy variations, background measurement time, and on-line off-line time division is also considered.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 20; Feb. 15
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    Remote Raman measurement techniques (1981)
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    Publication Date: 2011-08-18
    Description: The use of laser Raman measurement techniques in remote sensing applications is surveyed. A feasibility index is defined as a means to characterize the practicality of a given remote Raman measurement application. Specific applications of Raman scattering to the measurement of atmospheric water vapor profiles, methane plumes from liquid natural gas spills, and subsurface ocean temperature profiles are described. This paper will survey the use of laser Raman measurement techniques in remote sensing applications using as examples specific systems that the Computer Genetics Corporation (CGC) group has developed and engineered.
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    Type: Optical Engineering; 20; Jan
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    Measuring molecular flows with high-resolution stimulated Raman spectroscopy (1981)
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    Publication Date: 2011-08-18
    Description: It is proposed to use high-resolution stimulated Raman spectroscopy to directly measure high-speed molecular flow velocities in wind tunnels and in combustive chambers. A feasibility study indicates that flow speeds from Mach 0.04 up may be measured with the proposed method using available laser systems. It is pointed out that the success of the proposed technique will make it possible to measure all interesting flow parameters, i.e., species concentration, temperature, and velocity, in a time of less than 1 microsecond at a repetition rate of 10,000/s using a single experimental arrangement.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Journal of Quantum Electronics; QE-17; Jan. 198
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    Annular apertures with low and high obstruction (1981)
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    Publication Date: 2011-08-18
    Description: The distribution of image energy by the central obstruction of annular apertures is discussed with special emphasis on the effect of an aperture shape parameter which can be interpreted optically as the inverse obstruction ratio. This parameter generates group arrangements with the number of rings given by N2 = 1/a, where a is the central obstruction ratio.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 20; Jan. 15
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    Temperature stabilized phase detector (1981)
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    Publication Date: 2011-08-18
    Description: The construction, tests, and performance of a temperature stabilized phase detector are discussed. It has a frequency stability of 5 parts in 10 to the 16th power at 100 MHz, with a temperature step of 20 C (15 to 35 C).
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Telecommun. and Data Acquisition Progr. Rept. 42-64; p 90-95
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    ORION: Microwave water vapor radiometer subsystem design (1981)
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    Publication Date: 2011-08-18
    Description: Electrical path delay caused by atmospheric water vapor may be a limiting error source for geodetic measurements made with VLBI. Direct measurement of atmospheric water vapor is necessary to obtain path delay correction required by the ORION project. A dual channel water vapor radiometer is described which operates at frequencies near the 22 GHz water vapor line and is capable of collecting data that permits calculation of path delay within 2 cm accuracy.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Telecommun. and Data Acquisition; p 10-14
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  • 39
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    Apparatus for high-pressure and low-temperature experiments (1981)
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    Publication Date: 2011-08-18
    Description: A new type of apparatus for high-pressure experiments at low temperature (1.5 K) is presented. It uses a flat diamond anvil with a spherical indentor. It utilizes a load ring placed under the sample, so that the load (and hence pressure) can be measured in situ at low temperature. The apparatus was successfully used to investigate the high-conductivity state of sulphur. It can be used to investigate other thin film samples.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 52; Feb. 198
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  • 40
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    Telecentric optical system for observing daytime chemical releases at high altitudes (1981)
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    Publication Date: 2011-08-18
    Description: A system to be used for the tracking of high altitude chemical releases in the presence of a bright daytime sky is described. The system uses telecentric optics, a tilting filter, a solid state image sensor, and a real time digital processor to produce the release image. Field test data are presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 20; Mar. 15
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    Automated analyzer for aircraft measurements of atmospheric methane and total hydrocarbons (1981)
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    Publication Date: 2011-08-18
    Description: An automated methane/total hydrocarbon analyzer is presented, which can produce alternate methane/total hydrocarbon measurements every 7 seconds to provide the spatial resolution required for regional hydrocarbon measurements at aircraft speeds. The construction and sampling techniques developed for the aircraft mounted system are discussed. A technique to periodically measure atmosphere oxygen is incorporated into the analyzer to ensure accurate hydrocarbon measurements, and a data collection methodology is developed to minimize errors resulting from changes in flame ionization detector sensitivity at different altitudes. Aircraft data acquired at the 1979 Southeastern Virginia Urban Plume Study are also presented, which illustrate the application of the instrument to a troposphere pollution plume.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 52; Oct. 198
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  • 42
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    Multichannel scanning radiometer for remote sensing cloud physical parameters (1981)
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    Publication Date: 2011-08-18
    Description: A multichannel scanning radiometer developed for remote observation of cloud physical properties is described. Consisting of six channels in the near infrared and one channel in the thermal infrared, the instrument can observe cloud physical parameters such as optical thickness, thermodynamic phase, cloud top altitude, and cloud top temperature. Measurement accuracy is quantified through flight tests on the NASA CV-990 and the NASA WB-57F, and is found to be limited by the harsh environment of the aircraft at flight altitude. The electronics, data system, and calibration of the instrument are also discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 52; Oct. 198
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    Noise effects in an optical heterodyne spectrometer using tunable diode lasers (1981)
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    Publication Date: 2011-08-18
    Description: A comparison of measured and predicted signal-to-noise ratio is made in an optical heterodyne spectrometer utilizing a tunable diode laser which exhibited excess noise. It is shown that good agreement between predicted and measured signal-to-noise ratios results if excess noise effects due to tunable diode lasers are included in the predictions. The methods used to quantify excess noise and to incorporate their effects into predictions of signal-to-noise ratio are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Physics Letters; 39; Nov. 1
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    Satellite oceanography - The instruments (1981)
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    Publication Date: 2011-08-18
    Description: It is pointed out that no instrument is sensitive to only one oceanographic variable; rather, each responds to a combination of atmospheric and oceanic phenomena. This complicates data interpretation and usually requires that a number of observations, each sensitive to somewhat different phenomena, be combined to provide unambiguous information. The distinction between active and passive instruments is described. A block diagram illustrating the steps necessary to convert data from satellite instruments into oceanographic information is included, as is a diagram illustrating the operation of a radio-frequency radiometer. Attention is also given to the satellites that carry the various oceanographic instruments.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Oceanus; 24; Fall 198
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  • 45
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    Schlieren with a laser diode source (1981)
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    Publication Date: 2011-08-18
    Description: The use of a laser diode as a light source for a schlieren system designed to study phase objects such as a wind-tunnel flow is explored. A laser diode schlieren photograph and a white light schlieren photograph (zirconium arc source) are presented for comparison. The laser diode has increased sensitivity, compared with light schlieren, without appreciable image degradiation, and is an acceptable source for schlieren flow visualization.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering; 20; Sept
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    Spacelab high density digital recorders (1983)
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    Publication Date: 2011-08-18
    Description: The design and performance of the high-density digital recorder (HDDR) developed for use at the NASA centers (KSC, JSC, and GSFC) and at the JPL to store and retrieve 50-Mb/s PCM data streams from the Spacelab experiments are reported. The recording reproduction, and transport requirements are reviewed; and the design solutions adopted in the final version of the HDDR are described, incuding three-position-modulation and Y-phase encoding, microprocessor-controlled automatic bit synchronization and equalization, cyclic-redundancy-check error detection and correction, clock regeneration, data and clock variations, tape-speed control, and EEE-488 remote control. Reliable performance, with bit error rates 1 in 10 to the 10th forward and 1 in 10 to the 9th reverse or better and packing density up to 50 percent greater than that obtainable using conventional codes, is reported after 1.5 years of service.
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    Design philosophy of the Jet Propulsion Laboratory infrared detector test facility (1983)
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    Publication Date: 2011-08-18
    Description: To support the development of advanced infrared remote sensing instrumentation using line and area arrays, a test facility has been developed to characterize the detectors. The necessary performance characteristics of the facility were defined by considering current and projected requirements for detector testing. The completed facility provides the desired level of detector testing capability as well as providing ease of human interaction.
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    Comparison of measurements by different instruments of the far-infrared reflectance of rough, optically black coatings (1983)
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    Publication Date: 2011-08-18
    Description: Two comparisons of available specular infrared measurements using identical or very similar coatings reveal that specular BRDF (bidirectional reflectance distribution function) measurements of rough coatings are comparable but that simple measured reflectances are not. This is seen as indicating that the diffuse component of the measured specular reflectance is significantly larger than that of the specular component. It is noted that the diffuse component of the measurement is a convolution of the intrinsic directional reflectivity of the surface with the instrument function and that because the value of that function increases at the wavelengths under consideration, the diffuse component is larger than would otherwise be expected. The BRDF normalization is found to cause a primitive deconvolution of the instrument function and to produce a quantity that is approximately equal to the mean intrinsic directional reflectivity very near the specular direction. The analysis and comparison of data reveal that nonspecular BRDF measurements at angles well outside the instrument function can be calibrated as well by an image of the source upon the detector as by reference to a known surface.
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    Hollow cathode startup using a microplasma discharge (1981)
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    Publication Date: 2011-08-18
    Description: Attention is given to a microplasma discharge to initiate a hollow cathode discharge for such applications as plasma flow experiments, the electric propulsion of space vehicles, and as a replacement for filament cathodes in neutral beam injector ion sources. The technique results in a cathode that is easy to start, simple in design, and which does not require external RF exciters, inserts or heating elements. Future applications may include ion beam milling and ion implantation.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 52; Aug. 198
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    Improved formula for continuous-wave measurements of ultrasonic phase velocity (1981)
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    Publication Date: 2011-08-18
    Description: An improved formula for continuous-wave ultrasonic phase velocity measurements using contact transducers is derived from the transmission line theory. The effect of transducer-sample coupling bonds is considered for measurements of solid samples even though it is often neglected because of the difficulty of accurately determining the bond thickness. Computer models show that the present formula is more accurate than previous expressions. Laboratory measurements using contacting transducers with the present formula are compared to measurements using noncontacting (hence effectively correction-free) capacitive transducers. The results of the experiments verify the validity and accuracy of the new formula.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Applied Physics; 52; May 1981
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    CO2 DIAL sensitivity studies for measurements of atmospheric trace gases (1983)
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    Publication Date: 2011-08-18
    Description: An analysis is presented of the accuracy of infrared differential absorption lidar (DIAL) measurements of trace constituents in the atmosphere. Expressions are derived for the signal-to-noise ratios applicable in the detection of a signal from a scattering cell for the cases of single-detection heterodyne detection and direct detection. Results of computer simulations of the expectation value of the measured return for various measurement conditions are presented which illustrate the sensitivities of plume measurements for horizontal range-resolved and vertical content measurements of NH3 in heterodyne and direct detection. Advantages for long-range measurements of the use of rare isotope laser frequencies, tuning by collision broadening, and closely spaced on and off frequencies are pointed out.
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    Coherent CO2 lidar systems for remote atmospheric measurements (1983)
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    Publication Date: 2011-08-18
    Description: Several examples of applications of coherent CO2 Doppler lidar systems are summarized to illustrate the potential of these systems. The applications discussed include the use of continuous-wave systems for detecting and tracking aircraft wake vortices, transverse velocity measurements, and measurements of mass flow rates of high stack emissions. The use of pulsed coherent lidars is illustrated by applications involving the measurement of thunderstorm gust fronts, the measurement of wind profiles, and clear air turbulence detection. Following a summary of previous efforts, some current programs are reviewed. These include investigations into two-dimensional wind field measurements, atmospheric backscatter measurements, transverse velocity measurements, and the feasibility of space operations.
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    The NASA/Goddard balloon borne lidar system (1983)
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    Publication Date: 2011-08-18
    Description: The present investigation represents a part of a NASA program which is concerned with a study regarding the seriousness of man-made stratospheric ozone depletion. Such a depletion could possibly be caused by exhaust gases of aircraft at high altitudes or the release of chlorofluorocarbons into the lower atmosphere. A balloon-borne optical radar system was employed to conduct ozone measurements in the altitude region from 21 to 36 km and hydroxyl radical measurements in the region from 33 to 36 km. The hydroxyl radical was determined by making use of a procedure which is based on fluorescence induced by laser radiation. The technique of differential absorption lidar (DIAL) was used to measure ozone. According to this technique, two wavelengths are transmitted simultaneously and their backscattered intensities are measured. the obtained results show that optical radar represents an effective tool for stratospheric investigations.
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    Signal averaging limitations in heterodyne- and direct-detection laser remote sensing measurements (1983)
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    Publication Date: 2011-08-18
    Description: The improvement in measurement uncertainty brought about by the averaging of increasing numbers of pulse return signals in both heterodyne- and direct-detection lidar systems is investigated. A theoretical analysis is presented which shows the standard deviation of the mean measurement to decrease as the inverse square root of the number of measurements, except in the presence of temporal correlation. Experimental measurements based on a dual-hybrid-TEA CO2 laser differential absorption lidar system are reported which demonstrate that the actual reduction in the standard deviation of the mean in both heterodyne- and direct-detection systems is much slower than the inverse square-root dependence predicted for uncorrelated signals, but is in agreement with predictions in the event of temporal correlation. Results thus favor the use of direct detection at relatively short range where the lower limit of the standard deviation of the mean is about 2 percent, but advantages of heterodyne detection at longer ranges are noted.
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    Atmospheric pressure and temperature profiling using near IR differential absorption lidar (1983)
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    Publication Date: 2011-08-18
    Description: The present investigation is concerned with differential absorption lidar techniques for remotely measuring the atmospheric temperature and pressure profile, surface pressure, and cloud top pressure-height. The procedure used in determining the pressure is based on the conduction of high-resolution measurements of absorption in the wings of lines in the oxygen A band. Absorption with respect to these areas is highly pressure sensitive in connection with the mechanism of collisional line broadening. The method of temperature measurement utilizes a determination of the absorption at the center of a selected line in the oxygen A band which originates from a quantum state with high ground state energy.
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    Remote detection of gases by gas correlation spectroradiometry (1983)
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    Publication Date: 2011-08-18
    Description: The present investigation is concerned with the application of a pressure modulated radiometer (PMR) to the remote sensing of trace amounts of gases in the atmospheres as well as to the direct measurement of upper atmospheric winds. The PMR operates as a gas correlation spectrometer. Compared to conventional gas correlation parameters, it has some advantages which are related to greater versatility and the employment of a simpler method for maintaining electrical/optical balance. The PMR has a high sensitivity in connection with its essentially very high effective resolution. It represents a passive system and emits no radiation. A PMR is flown on Nimbus 6 which was launched in 1975. The instrument has also been used on the Nimbus 7 satellite and the Tiros N satellite.
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    Airborne remote sensing measurements with a pulsed CO2 DIAL system (1983)
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    Publication Date: 2011-08-18
    Description: The present investigation is concerned with an optical radar instrument which has been developed for airborne remote sensing of atmospheric trace species at infrared wavelengths. The instrument makes use of compact, pulsed carbon dioxide lasers. It was designed for conducting differential absorption lidar (DIAL) measurements. The backscatter of laser pulse energy from the ocean and terrain surface is utilized to determine trace species column content. The instrument, which is carried by the NASA P3 aircraft, is used in a flight test program started in July 1981. The results obtained with the instrument in this program are discussed, taking into account ocean surface backscatter statistics, the ratio of ocean to terrain backscatter, the dual-wavelength correlation coefficient, the dual-wavelength cross-covariance, and the dependence of un-correlated noise variance on the mean backscatter signal.
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    Balloon-borne diode-laser absorption spectrometer for measurements of stratospheric trace species (1983)
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    Publication Date: 2011-08-18
    Description: An instrument has been designed for the measurement of stratospheric trace species which utilizes tunable infrared diode lasers as sources for sensitive in situ absorption spectroscopy in selected wavelength regions. This instrument, the Balloon-Borne Laser In Situ Sensor (BLISS), is a high-resolution absorption spectrometer designed to provide measurements of the concentrations of stratospheric species and their diurnal variations. The instrument employs second-harmonic detection of the absorption of tunable diode laser (TDL) radiation (3-30 microns) in a 1 km path length defined by a retroreflector lowered 0.5 km below the BLISS gondola. Retroreflector tracking under microprocessor control is obtained using a He-Ne laser and coaligned TV camera with CID imaging. Simultaneous measurements of molecular species in the 20-40 km altitude range will be performed using four TDLs, with the predicted minimum-detectable mixing ratio at 30 km being typically less than or equal to 0.1 ppbv.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; Sept. 1
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    New technological developments for the remote detection of atmospheric hydroxyl radicals (1983)
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    Publication Date: 2011-08-18
    Description: New developments in the areas of narrowband tunable excimer lasers, high-resolution high-rejection optical filters, and wavelength measurement devices are considered for application to the remote sensing of atmospheric hydroxyl radicals. The conclusion is that an increase in the SNR of 10,000 could readily be gained through the use of these new devices. Also, considerable reductions in size and electrical energy consumption could be realized.
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    Type: Applied Optics (ISSN 0003-6935); 22; Sept. 1
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    Frequency-doubled CO2 lidar measurement and diode laser spectroscopy of atmospheric CO2 (1983)
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    Publication Date: 2011-08-18
    Description: A lidar instrument based on pulsed frequency-doubled carbon-dioxide lasers has been used at 4.88 microns for remote sensing of atmospheric carbon dioxide. A tunable-diode laser spectrometer provided the high-resolution spectroscopic data on carbon-dioxide line strength and line broadening needed for an accurate differential absorption measurement. Initial field measurements are presented, and instrument improvements necessary for accurate carbon dioxide measurement are discussed.
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    Type: Applied Optics (ISSN 0003-6935); 22; Sept. 1
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    An all fiber-optic sensor for surface acoustic wave measurements (1983)
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    Publication Date: 2011-08-18
    Description: A surface acoustic wave (SAW) sensor constructed from single-mode fiber-optic components is described. An analysis of reciprocal and nonreciprocal modes of operation of the sensor is presented. Results from measurements on a variety of SAW devices illustrate the use of the sensor. The amplitude sensitivity is 0.0003 A for an integration time of 0.1 s.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Lightwave Technology (ISSN 0733-8724); LT-1; June 198
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    Environmental data display (1983)
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    Publication Date: 2011-08-18
    Description: Methods for using a combination of computer-generated color graphics and image processing techniques to display a large data base of environment information are described. The data source can be either field data or mathematical models, reduced to summary statistics that characterize the data field as a whole. Sharp gradients are plotted into contour plots, which can also feature shades, degree of brightness, and saturation levels for fine-tuning the image. The basic concepts of digital image processing are reviewed, including location of the pixels, intensity mapping operations, pseudocolor enhancements, neighborhood averaging, and smoothing. Sample applications are presented in terms of emissions and air quality distributions over the south coast air basin of southern California.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Environmental Science and Technology (ISSN 0013-936X); 17; Feb. 198
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    A nonintrusive laser interferometer method for measurement of skin friction (1983)
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    Publication Date: 2011-08-18
    Description: A method is described for monitoring the changing thickness of a thin oil film subject to an aerodynamic shear stress using two focused laser beams. The measurement is then simply analyzed in terms of the surface skin friction of the flow. The analysis includes the effects of arbitrarily large pressure and skin friction gradients, gravity, and time varying oil temperature. It may also be applied to three dimensional flows with unknown direction. Applications are presented for a variety of flows, including two dimensional flows, three dimensional swirling flows, separated flow, supersonic high Reynolds number flows, and delta wing vortical flows. Previously announced in STAR as N83-12393
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Experiments in Fluids (ISSN 0723-4864); 1; 1, 19; 1983
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    The function and response of an improved stratospheric condensation nucleus counter (1983)
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    Publication Date: 2011-08-18
    Description: An improved condensation nucleus counter (CNC) for use in the stratosphere is described. The University of Minnesota CNC (UMCNC) has a sequential saturator and condenser and uses n-butyl alcohol as the working fluid. The use of a coaxial saturator flow, with aerosol in the center and filtered, alcohol-laden air around it, speeds the response of this instrument and improves its stability as pressure changes. The counting efficiency has been studied as a function of particle size and pressure. The UMCNC provides an accurate measure of submicron aerosol concentration as long as the number distribution is not dominated by sub-0.02 micron diameter aerosol. The response of the UMCNC is compared with that of other stratospheric condensation nucleus counters, and the results of a (near) comparison with a balloon-borne condensation nucleus counter are presented. The UMCNC has operated 14 times on a NASA U-2 aircraft at altitudes from 8 to 21.5 km.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; Aug. 20
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    Gas flow through rotameters (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Using data available for small rotameters that use spherical floats in gas flow, a linear relationship is derived. It is noted that the relationship provides a good fit for variable volumetric flow, density, and viscosity at constant flow height. With low Reynolds numbers (Re being less than 1), the product of the variable volumetric flow and the viscosity becomes constant; at high Reynolds numbers (Re being greater than 2000), the product of the variable volumetric flow and the square root of the density becomes constant. It is pointed out that the equation given here can be used to obtain an indirect calibration with any gas of known density and viscosity. The constancy of the product of the variable volumetric flow and viscosity at low variable volumetric flows is seen as suggesting the development of simple, inexpensive gas viscometers using rotameter technology.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: I & EC-Industrial and Engineering Chemistry, Fundamentals (ISSN 0196-4313); 22; 2, 19; 1983
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    The Airborne Laser Ranging System - Its capabilities and applications (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Airborne Laser Ranging System is a proposed multibeam short pulse laser ranging system on board an aircraft. It simultaneously measures the distances between the aircraft and six laser retroreflectors (targets) deployed on the earth's surface. Depending on the host aircraft and terrain characteristics, the system can interrogate hundreds of targets distributed over an area as large as 60,000 sq. km in a matter of hours. Potentially, a total of 1.3 million individual range measurements can be made in a 6 hr flight. The precision of these range measurements is approximately 1 cm. These measurements are then used in a procedure which is basically an extension of trilateration techniques to derive the intersite vector between the laser ground targets. By repeating the estimation of the intersite vector, strain and strain rate errors can be estimated. These quantities are essential for crustal dynamic studies which include determination and monitoring of regional strain in the vicinity of active fault zones, land subsidence, and edifice building preceding volcanic eruptions.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Bulletin Geodesique (ISSN 0007-4632); 57; 2, 19; 1983
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  • 67
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    Moire deflectometry with deferred analysis (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A simplified version of moire deflectometry for flow visualization is presented. The modification comprises replacement of the second grating, the ground glass screen, and the camera with a plate film holder to obtain a shadow picture. Postanalysis proceeds by placing a grid transparency of the same periodicity of the remaining glass grating on the negative for projection viewing. The rotational angle between the grating and the plate alters the moire fringe periodicity. Use of the method in studying flows is predicted to reveal weak density gradient areas and shocks.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 22; Mar. 1
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    Lidar system analysis for measurement of atmospheric species (1983)
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    Publication Date: 2011-08-18
    Description: Several important aspects of lidar are discussed, which pertain to a system analysis of the applicability of certain types of lidar to specific measurement objectives. The differential absorption lidar (DIAL) technique is emphasized. A brief treatment of the DIAL technique is followed by a discussion of the comparison of DIAL with other lidar measurement techniques. Sensitivity expressions are presented for DIAL with either direct or coherent (heterodyne) detection systems. A treatment of the fundamental similarities and differences in using the UV and IR spectral regions for species measurements, such as backscattering properties, spectral characteristics of the absorbing species, and factors relevant to the optimization of the DIAL measurement accuracy, is also included. Finally, results obtained from an existing ground-based DIAL system used to measure water vapor profiles are briefly discussed.
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    IR detectors - Heterodyne and direct (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Recent developments in the area of wide-bandwidth infrared detectors, both for direct and heterodyne detection, are reviewed with emphasis on the differences and tradeoffs between photodiodes and photoconductors. In the direct-detection mode, where amplifier noise is an important consideration, the state-of-the-art detection noise equivalent power is approximated by 500 (B/10 MHz) pW. At short wavelengths (less than 1.7 micron), avalanche photodiodes offer superior performance, with a detection noise equivalent power of about 50 (B/10 MHz) pW. In heterodyne operation, near-ideal sensitivities of about 0.3 (B/10 MHz) pW have been achieved with 77K photodiodes. At 10 microns, HgCdTe photoconductors offer very good heterodyne performance at elevated temperatures: 2 (B/10 MHz) pW at 195 K and potentially 3 (B/10 MHz) pW at 250 K.
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    The time-space relationships among data points from multispectral spatial scanners (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Multispectral scanner and thematic mapper (TM) data from Landsat satellites are discussed in terms of the perceived 'simultaineity' of the images, which are obtained by scanning techniques. Scanning the scenes ensures that the data points of the images are actually sequential, even if the scan is performed at rates that are fast relative to the motion of the spacecraft. The last datum gathered by the MSS is, in fact, taken 29 sec after the first, witih a 56 m distance being present between pixels. The spacing in uneven from band to band on the TM and analyses of the data to produce an image requires consideration of nonfixed time relationships for different locations on the scan within and among the bands. Additionally, corrective measures must be taken to compensate for instrument jitter and attitude changes.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: International Journal of Remote Sensing (ISSN 0143-1161); 4; July-Sep
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  • 71
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    X-ray imaging of extended objects using nonoverlapping redundant array (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A common problem associated with X-ray imaging using coded apertures is the reconstruction of low-intensity extended objects. In the decoding of such objects, the overlapping images from the multiple pinholes give rise to noise cross talk and, in many cases, also to signal cross talk. In this paper, an alternate approach is proposed based on the principle used in an earlier (Yin et al., 1980) laboratory device for the real-time viewing of X-ray objects. It is shown that with this approach, the nonoverlapping redundant array, the sidelobes in the point spread function are not eliminated but merely displaced through a suitable choice of geometry. In this manner, the sidelobes no longer contribute to the background in the vicinity of a reconstructed image, and both signal and noise cross talks are completely eliminated. It may now be possible to reconstruct extended X-ray objects in 3-D by simple optical correlation and tomographically by a computer.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; July 15
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  • 72
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    Supersonic-nitrogen flow-field measurements with the resonant Doppler velocimeter (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The application of the resonant Doppler velocimeter (RDV) for obtaining the mean velocity, temperature, and pressure measurements and flow-field visualization in a supersonic free nitrogen jet is reported. This method utilizes laser-induced fluorescence to determine the spectral absorption of an atomic or molecular species seeded into the flow. A narrow linewidth tunable laser is directed into the flow and the total fluorescence from any point is obtained as the laser is tuned. The velocity of the flow is obtained from the Doppler shifted absorption frequency, and the temperature and pressure of the gas are determined from line broadening measurements. Results are presented for the use of this technique to determine the velocity, temperature, and pressure of the flow of sodium atoms seeded into a supersonic nitrogen jet. It is concluded that the visible signal is sufficiently intense for spatially resolved flow visualization purposes.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Physics Letters (ISSN 0003-6951); 43; July 15
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  • 73
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    Seven-hole cone probes for high angle flow measurement Theory and calibration (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Previously cited in issue 08, p. 1219, Accession no. A82-22070
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: (ISSN 0001-1452)
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  • 74
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    A small, battery-operated fluoroscopic system - Lixiscope with X-ray generator (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A small, battery-operated X-ray generator has been developed to be used as part of a small-format fluoroscopic system, the Lixiscope (Low Intensity X-ray Imaging Scope). The X-ray generator consists of a grounded rod-anode X-ray tube with a 0.2 mm focal spot and a specially designed, battery-operated, 0 to -80 kV high-voltge supply. Total power consumption is about 10 W. The fine focal spot, in conjunction with the continuously variable X-ray intensity and spectral distribution, helps to extend both the versatility and the performance of the Lixiscope toward a much wider range of terrestrial and spacecraft applications. The complete fluoroscopic system is described, and some examples of possible applications are shown.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Materials Evaluation (ISSN 0025-5327); 41; June 198
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  • 75
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    Analysis method for Fourier transform spectroscopy (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A fast Fourier transform technique is given for the simulation of those distortion effects in the instrument line shape of the interferometric spectrum that are due to errors in the measured interferogram. The technique is applied to analyses of atmospheric absorption spectra and laboratory spectra. It is shown that the nonlinear least squares method can retrieve the correct information from the distorted spectrum. Analyses of HF absorption spectra obtained in a laboratory and solar CO absorption spectra gathered by a balloon-borne interferometer indicate that the retrieved amount of absorbing gas is less than the correct value in most cases, if the interferogram distortion effects are not included in the analysis.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 22; Mar. 15
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    Laboratory Automation of a Quadrupole Mass Spectrometer (1983)
    In:  CASI
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    Publication Date: 2014-09-11
    Description: Efforts directed toward interfacing an LSI II bus of a PDP 11/23 desktop computer with a quadrupole mass spectrometer for the purpose of providing a convenient system whereby mass spectral data, of the products of thermal decomposition, may be rapidly acquired and processed under programmed conditions are described. The versatility and operations of the quadrupole mass spectrometer are discussed as well as the procedure for configurating the LSI II bus of the PDP 11/23 desktop computer for interfacing with the quadrupole mass spectrometer system. Data from the mass filter and other units of the spectrometer are digitally transferred to the computer whereupon mass spectral data and related data are generated.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Alabama Univ. Res. Rept.: 1983 NASA(ASEE Summer Faculty Fellowship Program; 26 p
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  • 77
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    Simultaneous multiple-point velocity measurements using laser-induced iodine fluorescence (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A technique is demonstrated for measuring velocity at multiple locations in a plane of a gaseous flowfield using Doppler-shifted absorption with fluorescence detection from iodine molecules, excited by a sheet of tunable single-axial-mode argon-ion laser radiation at 514.5 nm. Measurements were made simultaneously at 10,000 points in an iodine-seeded supersonic flow field with a 100 x 100 element photodiode array camera and were found to agree well with a numerical solution for the velocity field. The accuracy with which a component of velocity can be measured is limited, in the current approach, by the iodine linewidth to about 5 m/sec.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optics Letters; 8; Jan. 198
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  • 78
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    Real-time observation of X-ray diffraction patterns with the Lixiscope (1981)
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    Publication Date: 2011-08-18
    Description: The feasibility of the Lixiscope (Low Intensity X-ray Imaging Scope) is demonstrated for real-time observation of transmission Laue patterns. Making use of the high-gain capability of microchannel plate (MCP) visible-light image intensifier tubes, X-ray images are converted to visible-light images by a scintillator. Pb discs are taped to the center of the Lixiscope input face, and crystal samples are held on a goniometer stage with modeling clay. With a compact size to facilitate off axis viewing, and real-time viewing to allow instantaneous response, the Lixiscope may prove useful in dynamic studies of the effects of plastic flows, stresses, high pressures, and low temperatures.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 52; July 198
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    Gauge calibration system based on piston manometer (1981)
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    Publication Date: 2011-08-18
    Description: An unbaked calibration system is described that permits absolute calibration with a piston manometer in the range 0.0002 to 6 Pa, with a probable error of 5 microPa + 0.8%, or in the range 0.00008 to 0.02 Pa, with a probable error of 2 microPa + 1%. Procedures and techniques that permit this performance are detailed. For hot-cathode ion gauges, the magnitudes of systematic corrections for envelope temperature and grid current are also indicated.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Vacuum Science and Technology; 19; July-Aug
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  • 80
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    Radiometric performance of the test-bed aircraft multispectral scanner /TBAMS/ system (1981)
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    Publication Date: 2011-08-18
    Description: Laboratory and flight radiometric performance testing of an experimental multispectral scanner system is described. High sensitivity performance is confirmed by test results using noise equivalent spectral radiance as the primary figure of merit. A performance comparison between the test-bed aircraft multispectral scanner (TBAMS) and the Bendix modular multispectral scanner (M2S) is presented. Methods for achieving high sensitivity operation are discussed as well as some of the practical implications of such operation for flight remote sensing experiments.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering; 20; Sept
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  • 81
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    Absolute S- and P-plane polarization efficiencies for high frequency holographic gratings in the VUV (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: High frequency plane gratings (3500 and 3600 gr/mm) have been holographically ruled and blazed for the VUV spectral region. All gratings were coated with 70 nm Al + 25 nm MgF2. Absolute unpolarized and S- and P-plane polarization efficiencies have been measured for the first and second orders in the 120- to 450-nm spectral region at 18.5 and 30 deg angles of deviation. For deep grooves, anomalous features are more pronounced for the P-plane polarization efficiency than for the S-plane polarization efficiency. Holographic gratings can be tailored to produce high polarization or low polarization in the VUV. For comparison, efficiencies and polarization of the best conventional high frequency gratings were also determined. Measurements show that scattered light is significantly lower for holographic gratings in the VUV when compared with the conventional gratings.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 20; May 15
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  • 82
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    A study of low-noise preamplifier systems for use with room temperature mercuric iodide /HgI2/ X-ray detectors (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An analysis of different preamplification systems for use with room temperature mercuric iodide X-ray detectors has been performed. Resistor-, drain-, and light-feedback preamplifiers have been studied. Energy resolution values of 295 eV (FWHM) for an Fe-55 source (5.9 keV) and 225 eV (FWHM) for a pulser have been obtained with both the detector and the input FET at room temperature using a pulsed-light feedback preamplifier. Improvement in energy resolution by cooling the input FET using a small Peltier element has been discussed.
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    The effects of focusing on the efficiency of coherent anti-Stokes Raman scattering (1981)
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    Publication Date: 2011-08-18
    Description: The efficiency of coherent anti-Stokes Raman scattering (CARS) is calculated as a function of the input beam sizes of the Stokes and pump laser beams. A Green's function formalism is used to show that maximum efficiency occurs when the confocal parameters of the two input beams are unequal and when the phase mismatch between the anti-Stokes field and the nonlinear polarization is nonzero.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Chemical Physics; 75; Sept. 15
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    Images of single X-ray photons from X-ray phosphor screens (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Photographs show the efficiency and resolution characteristics of single X-ray photons converted to optical photons in a variety of commercial X-ray phosphor screens. The recording system uses a cooled, two-stage image intensifier system with fiber optics coupling to the phosphor screen. High efficiencies in the energy range 20-100 keV with position resolution of the order 200 microns are readily achievable, although the sensitive area is presently limited. Potential applications include X-ray astronomy, high-speed X-ray diffractometry, and extremely low dose radiography.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 52; Aug. 198
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  • 85
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    A photoelastic-modulator polarimeter at Pine Mountain Observatory (1981)
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    Publication Date: 2011-08-18
    Description: The use of photoelastic polarimeters in astronomy is briefly reviewed, and a visible and near-UV photoelastic modulation polarimeter is described which has been in continuous service on the 61-cm telescope of Pine Mountain Observatory for 6 years. The polarimeter is used primarily for linear polarization measurements, but is easily adaptable to circular polarimetry. The instrument has produced data at a sensitivity level of 0.01%, with long-term absolute reproducibility.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Astronomical Society of the Pacific; vol. 93
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  • 86
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    Holographic flow visualization of time-varying shock waves (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Rapid-double-exposure, diffuse-illumination holography is evaluated analytically and experimentally as a flow visualization method for time-varying shock waves. Conditions are determined that minimize the distance (localization error) between the surface or curve of interference-fringe localization and the shock surface. Treated specifically are the cases of shock waves in a transonic compressor rotor for which there is laser anemometer data for comparison and shock waves in a flutter cascade.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 20; Sept. 15
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    LAPR - An experimental pushbroom scanner (1981)
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    Publication Date: 2011-08-18
    Description: A three-band Linear Array Pushbroom Radiometer (LAPR) was built and flown on an experimental basis by NASA, at the Goddard Space Flight Center. The functional characteristics of the instrument and the methods used to preprocess the data, including radiometric correction, are described. The radiometric sensitivity of the instrument was tested and compared to that of the Thematic Mapper and the Multispectral Scanner. The radiometric correction procedure was evaluated quantitatively, using laboratory testing, and qualitatively, by visual examination of the LAPR test flight imagery. Although effective radiometric correction could not yet be demonstrated by laboratory testing, radiometric distortion did not preclude the visual interpretation or classification of the test imagery.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Photogrammetric Engineering and Remote Sensing; 47; May 1981
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    Laboratory analysis of techniques for remote sensing of estuarine parameters using laser excitation (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The theoretical concepts underlying remote sensing of estuarine parameters using laser excitation are examined. The concepts are extended to include Mie scattering as a measure of the total suspended solids and to develop the water Raman signal as an internal standard. Experimental validation of the theory was performed using backscattered laser light from a laboratory tank to simulate a remote-sensing geometry. Artificially prepared sediments and biological cultures were employed to check specific aspects of the theory under controlled conditions. Natural samples gathered from a variety of water types were also analyzed in the tank to further enhance the simulation. The results indicate that it should be possible to remotely quantify total suspended solids, dissolved organics, attenuation coefficient, chlorophyll a, and phycoerythrin in estuarine water using laser excitation.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 22; Jan. 1
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  • 89
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    Multiwavelength analyzer for the determination of diffusion lengths (1983)
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    Publication Date: 2011-08-18
    Description: The minority carrier diffusion length Ln in the base or substrate region is an important parameter which governs a solar cell's performance. The present investigation is concerned with the development of a multiwavelength analyzer (MWA) technique for the nondestructive spatial testing of polycrystalline solar cells. The MWA method is based on the utilization of the short-circuit current generated by two or more light-emitting diodes (LEDs) operating at different wavelengths and modulated 180 deg out-of-phase. For a determination of Ln by the MWA technique, it is necessary to know the value of the absorption coefficient.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Solar Cells (ISSN 0379-6787); 9; Sept
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  • 90
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    Remote sensing of OH in the atmosphere using the technique of laser-induced fluorescence (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The use of a laser-induced fluorescence technique for the sensitive measurement of the atmospheric hydroxyl radical is discussed. Results of laboratory studies of the fluorescence and other spectroscopic properties of OH which allow the calculation of OH concentrations from the returned signals for various altitudes, water vapor contents and temperatures are presented. The experimental setup used for airborne OH measurements is then described, with particular attention given to the use of a telescope for excitation and light collection in a coaxial configuration and the periodic tuning of the exciting radiation necessary to obtain an OH signal in the presence of strong solar and nonresonant fluorescence backgrounds. The best detection limit obtained to date with the system is noted to be about 700,000 OH/cu cm, and it is expected that, with planned improvements in detection and tuning schemes, limits in the neighborhood of 1,000,000 OH/cu cm will be achieved routinely.
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  • 91
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    Coherent anti-Stokes Raman spectroscopic modeling for combustion diagnostics (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The status of modelling the coherent anti-Stokes Raman spectroscopy (CARS) spectra of molecules important in combustion, such as N2, H2O, and CO2, is reviewed. It is shown that accurate modelling generally requires highly precise knowledge of line positions and reasonable estimates of Raman linewidths, and the sources of these data are discussed. CARS technique and theory is reviewed, and the status of modelling the phenomenon of collisional narrowing at pressures well above atmospheric for N2, H2O, and CO2 is described. It is shown that good agreement with experiment can be achieved using either the Gordon rotational diffusion model or phenomenological models for inelastic energy transfer rates.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering (ISSN 0091-3286); 22; May-June
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  • 92
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    X-ray spectrograph design (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An aberration theory is applied to spectrograph design. The initial system considered has a toroidal mirror in front of a concave grating spectrograph, giving spatial resolution perpendicular to the dispersion direction. The accuracy of the theory is shown by comparison of spot diagrams obtained from the aberrations with those produced by raytracing. The major aberrations affecting the vignetting at the intermediate slit and the spatial resolution are identified. A new system, using a holographic grating to give a flat focal plane, is then designed and optimized. It has increased spatial resolution over the wavelength range and is particularly suitable for microchannel array detectors.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; May 15
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  • 93
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    Electron-photon coincidence technique for the absolute calibration of VUV detectors (1983)
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    Publication Date: 2011-08-18
    Description: A method is described whereby VUV photon detectors can be accurately calibrated. This method is illustrated by taking the 58.4-nm transition of He as an example. The technique consists of crossing a monoenergetic electron beam with a beam of He atoms. When inelastically scattered electrons which have excited the 2 1P state are detected in coincidence with the 58.4-nm photons emitted in the decay of the excited state, the interaction volume formed by the crossed beams constitutes a standard source of photons. By comparing the number of detected coincidences with the predicted number the calibration can be made. A total detector efficiency of 0.024 + or - 0.003 is obtained for a Galileo 4830 channeltron.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; May 15
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  • 94
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    dc discharge cell for laser optogalvanic spectroscopy (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A dc electrical discharge cell for laser optogalvanic spectroscopy has been designed and tested. Signal optimization is achieved through the use of adjustable electrode positions and an orthogonal geometry between the probe laser and the discharge axis. Results are presented for visible dye laser and infrared diode laser studies of selected neutral, radical, and ion species.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments (ISSN 0034-6748); 54; 1454-145
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  • 95
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    Submillimeter-wave receivers - A status report (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A development status assessment is presented for the work of U.S. and Western European research groups on heterodyne sub-mm receivers in the 300-1000 GHz frequency range. The applications driving sub-mm receiver and local oscillator source technologies are radio astronomy, atmospheric measurements, plasma diagnostics, and laboratory spectroscopy. Progress is concentrated in two areas, cooled Schottky diode mixers and solid state local oscillators employing frequency multipliers.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Transactions on Microwave Theory and Techniques (ISSN 0018-9480); MTT-31; 873-878
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  • 96
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    Frequency standards for VLBI, present and future (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: During the last several years, J.P.L. has evaluated a number of different types of frequency standards. These evaluations include measurement of environmetal susceptibilities (barometric pressure, humidity, temperature and magnetic field) and evaluation of stability. Data from these tests are presented for quartz oscillators, rubidium vapor standards, cesium beam standards, hydrogen masers (active and passive) and a superconducting cavity stabilized oscillator. Data on reliability and mechanical ruggedness based on actual field use is also presented. A survey of new frequency standards, their likely performance and environmental characteristics is presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 97
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    Delayed darkening of radiation-exposed radiochromic dye dosimeters (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Experiments have verified the existence of considerable delayed darkening in FWT-60 dosimetry films that may, depending on relative humidity, last for several hours. The amount of delayed darkening depends very strongly on the relative humidity at which the films are equilibrated before irradiation. It is pointed out that the delayed darkening effect must be taken into account before any meaningful dosimetric measurements may be made using these nylon-based thin dosimetry films. The particular radiation-sensitive compound used in the FWT-60 films is the hexahydrosyethyl pararosanaline cyanide with the Dupont nylon resin, Elvamide 8061, which forms the host matrix of a solid-state solution.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 98
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    Ozone profile intercomparison based on simultaneous observations between 20 and 40 km (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The vertical distribution of stratospheric ozone has been simultaneously measured by means of five different instruments carried on the same balloon payload. The launches were performed from Gap during the intercomparison campaign conducted in June 1981 in southern France. Data obtained between altitudes of 20 and 40 km are compared and discussed. Vertical profiles deduced from Electrochemical Concentration Cell sondes launched from the same location by small balloons and from short Umkehr measurements made at Mt Chiran (France) are also included in this comparison. Systematic differences of the order of 20 percent between ozone profiles deduced from solar u.v. absorption and in situ techniques are found.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Planetary and Space Science (ISSN 0032-0633); 31; July 198
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  • 99
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    Single-pulse gas thermometry at low temperatures using two-photon laser-induced fluorescence in NO-N2 mixtures (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A technique suitable for measuring fluctuating temperatures in supersonic turbulent flows of N2 seeded with NO has been demonstrated in a nonflowing cell. The method relies on the two photon excitation of two selected ro-vibronic transitions in the NO gamma (alpha 2 sigma+, v prime = 0 yields ch1zp1, v double prime = 0). Previously announced in STAR as N83-20079
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optics Letters (ISSN 0146-9592); 8; July 198
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  • 100
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    Acoustic ground impedance meter (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A compact, portable instrument was developed to measure the acoustic impedance of the ground, or other surfaces, by direct pressure-volume velocity measurement. A Helmholtz resonator, constructed of heavy-walled stainless steel but open at the bottom, is positioned over the surface having the unknown impedance. The sound source, a cam-driven piston of known stroke and thus known volume velocity, is located in the neck of the resonator. The cam speed is a variable up to a maximum 3600 rpm. The sound pressure at the test surface is measured by means of a microphone flush-mounted in the wall of the chamber. An optical monitor of the piston displacement permits measurement of the phase angle between the volume velocity and the sound pressure, from which the real and imaginary parts of the impedance can be evaluated. Measurements using a 5-lobed cam can be made up to 300 Hz. Detailed design criteria and results on a soil sample are presented. Previously announced in STAR as N82-17476
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Acoustical Society of America, Journal (ISSN 0001-4966); 73; June 198
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