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  • INSTRUMENTATION AND PHOTOGRAPHY  (248)
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  • 1
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    In:  CASI
    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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  • 2
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    In:  CASI
    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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  • 3
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    In:  CASI
    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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  • 4
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    In:  CASI
    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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  • 5
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    In:  CASI
    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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  • 6
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    In:  CASI
    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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  • 7
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    In:  CASI
    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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  • 8
    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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  • 9
    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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  • 10
    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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  • 11
    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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  • 12
    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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  • 13
    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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  • 14
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    In:  CASI
    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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  • 15
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    In:  CASI
    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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  • 16
    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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  • 17
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    In:  CASI
    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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  • 18
    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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  • 19
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    In:  CASI
    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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  • 20
    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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  • 21
    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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  • 22
    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.
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  • 23
    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.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 24
    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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  • 25
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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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  • 26
    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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  • 27
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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.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering; 20; Jan
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  • 28
    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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  • 29
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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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  • 30
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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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  • 31
    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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  • 32
    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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  • 33
    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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  • 34
    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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  • 35
    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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  • 36
    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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  • 37
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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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  • 38
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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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  • 39
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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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  • 40
    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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  • 41
    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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  • 42
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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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  • 43
    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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  • 44
    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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  • 45
    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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  • 46
    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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  • 47
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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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  • 48
    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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  • 49
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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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  • 50
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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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  • 51
    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.
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  • 52
    Publication Date: 2017-10-02
    Description: The application and analysis of dynamic stability parameters were examined. The effects of wing leading edge modifications on the stalling and spinning characteristics of a single engine general aviation research airplane are evaluated. It is illustrated how dynamic stability parameters measured in wind tunnel tests are used to predict the spin resistance of this class of aircraft, and that autorotation criteria are derived from the relationships which exist between static and dynamic aerodynamic characteristics.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: AGARD Dyn. Stability Parameters; 12 p
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  • 53
    Publication Date: 2016-06-07
    Description: The basic parameters relevant to the design of network timing systems describe the random and systematic time departures of the system elements, i.e., master (or reference) clocks, transmission links, and other clocks controlled over the links. The quantitative relations between these parameters were established and illustrated by means of numerical examples based on available measured data. The examples were limited to a simple PLL control system but the analysis can eventually be applied to more sophisticated systems at the cost of increased computational effort.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Proc. of the 12th Ann. Precise Time and Time Interval Appl. and Planning Meeting; p 515-549
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  • 54
    Publication Date: 2016-06-07
    Description: As a power utility, Hydro-Quebec used the PTTI techniques. The time dissemination system in the Hydro-Quebec Network (11th PTTI) is now installed in several points. A portable clock was built using a rubidium standard and associated circuitry which are necessary for the measurements. The apparatus and the experimental results obtained are described. The use of GOES synchronized clocks for making precise voltage angle measurement on the Hydro-Quebec Network is discussed. Some modifications were made on a commercial unit. Applications and results are presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Proc. of the 12th Ann. Precise Time and Time Interval Appl. and Planning Meeting; p 377-385
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  • 55
    Publication Date: 2016-06-07
    Description: A two-way time synchronization experiment performed in the spring of 1979 and 1980 via the Italian SIRIO-1 experimental telecommunications satellite is described. The experiment was designed and implemented to precisely monitor the satellite motion and to evaluate the possibility of performing a high precision, two-way time synchronization using a single communication channel, time-shared between the participating sites. Results show that the precision of the time synchronization is between 1 and 5 ns, while the evaluation and correction of the satellite motion effect was performed with an accuracy of a few nanoseconds or better over a time interval from 1 up to 20 seconds.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Proc. of the 12th Ann. Precise Time and Time Interval Appl. and Planning Meeting; p 329-350
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  • 56
    Publication Date: 2016-06-07
    Description: Continuous phase recording of the 16kHz transmission from GBR (UK) are being made and published midday phase data of GBR are received regularly from laboratories in the US, FGR, and UK. The local time scale (UTC, India), at the National Physical Laboratory in New Delhi, and those at the foreign laboratories are intercompared using the VLF phase data. A major factor which limits the accuracy of long term comparison is the seasonal variation in the VLF over delay over long paths. By taking into account the seasonal delay variations in a semiempirical way, the accuracy of time and frequency comparisons can be improved. Over a one year period, accuracy of a few parts in 10 to the 14th power in frequency and 1 to 2 micron sec in time were obtained. The relative frequency offset difference between UTC, (India) and UTC (PTB, Germany) of (7.0 + or - 0.1) x 10 to the -13 power agrees well with that obtained in a satellite experiment.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Proc. of the 12th Ann. Precise Time and Time Interval Appl. and Planning Meeting; p 851-862
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  • 57
    Publication Date: 2016-06-07
    Description: Minimum variance estimation requires that the statistics of random observation errors be modeled properly. If measurements are derived through the use of atomic frequency standards, then one source of error affecting the observable is random fluctuation in frequency. This is the case, for example, with range and integrated Doppler measurements from satellites of the Global Positioning and baseline determination for geodynamic applications. An analytic method is presented which approximates the statistics of this random process. The procedure starts with a model of the Allan variance for a particular oscillator and develops the statistics of range and integrated Doppler measurements. A series of five first order Markov processes is used to approximate the power spectral density obtained from the Allan variance.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Proc. of the 12th Ann. Precise Time and Time Interval Appl. and Planning Meeting; p 551-580
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  • 58
    Publication Date: 2016-06-07
    Description: At NASA Goddard Space Flight Center and through associated contractors, a broad spectrum of work is being carried out to develop improved hydrogen maser frequency standards for field use, improved experimental hydrogen maser frequency standards, and improved frequency and time distribution and measurement systems for hydrogen maser use. Recent progress in the following areas is reported: results on the Nr masers built by the Applied Physics Laboratory of Johns Hopkins University, the development of a low cost hydrogen maser at Goddard Space Flight Center, and work on a low noise phase comparison system and digitally phase locked crystal oscillator called the distribution and measurement system.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Proc. of the 12th Ann. Precise Time and Time Interval Appl. and Planning Meeting; p 463-493
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  • 59
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    Publication Date: 2016-06-07
    Description: Initial test results indicated that the Global Positioning System/Time Transfer Unit (GPS/TTU) performed well within the + or - 100 nanosecond range required by the original system specification. Subsequent testing involved the verification of GPS time at the master control site via portable clocks and the acquisition and tracking of as many passes of the space vehicles currently in operation as possible. A description and discussion of the testing, system modifications, test results obtained, and an evaluation of both GPS and the GPS/TTU are presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Proc. of the 12th Ann. Precise Time and Time Interval Appl. and Planning Meeting; p 387-415
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  • 60
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    Publication Date: 2016-06-07
    Description: The LASSO (Later Synchronisation from Stationary Orbit) experiment, designed to demonstrate the feasibility of achieving time synchronization between remote atomic clocks with an accuracy of one nanosecond or better by using laser techniques for the first time is described. The experiment uses groundbased laser stations and the SIRIO-2 geostationary satellite to be launched towards the end of 1981. The qualification of the LASSO on-board equipment is discussed with a brief description of the electrical and optical test equipment used. The progress of the operational organization is included.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Proc. of the 12th Ann. Precise Time and Time Interval Appl. and Planning Meeting; p 307-327
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  • 61
    Publication Date: 2016-06-07
    Description: Innovation and reliability in hyperfine frequency standards and clock systems are discussed. Hyperfine standards are defined as those precision frequency sources and clocks which use a hyperfine atomic transition for frequency control and which have realized significant commercial production and acceptance (cesium, hydrogen, and rubidium atoms). References to other systems such as thallium and ammonia are excluded since these atomic standards have not been commercially exploited in this country.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Proc. of the 12th Ann. Precise Time and Time Interval Appl. and Planning Meeting; p 275-280
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  • 62
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    Publication Date: 2016-06-07
    Description: Methods of resolving the iron lines, the most common X-ray emission lines in both galactic and extragalactic X-ray sources, are reviewed. A self-focussing crystal spectrometer is shown to be the most suitable instrument, and the optimum crystal geometry is spherical (Schnopper and Taylor 1980). The principles of operation of such a spherical crystal imaging spectrometer are examined and its sensitivity is shown to be two orders of magnitude better than a focal plane crystal spectrometer on AXAF. A Spacelab version of this payload would be very cost-effective.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center X-ray Astronomy in the 1980's; p 497-522
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  • 63
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    Publication Date: 2016-06-07
    Description: A wide-field soft X-ray camera (WFSXC) sensitive in the 50 to 250 eV band is described. The camera features Wolter-Schwarzschild optics with an 8 degree field of view and 300 cu cu collecting area. The focal plane instrument is a microchannel plate detector. Broad-band energy discrimination is provided by thin-film filters mounted immediately in front of the focal plane. The WFSXC is capable of detecting sources with intensities greater than 5 percent of HZ 43 during typical sounding rocket exposures, and it would approach the same sensitivity range as EUVE during a typical exposure from the Shuttle.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center X-ray Astronomy in the 1980's; p 319-323
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  • 64
    Publication Date: 2016-06-07
    Description: A time and frequency intercomparison experiment conducted using Earth stations in New Delhi, India and Raisting, FRG is described. The NPL clock was placed at New Delhi Earth Station and the Raisting Clock was calibrated with PTB/Primary standard via LORAN-C and travelling clocks. The random uncertainity of time comparisons, represented by two sample Allan Variance sigma (30 seconds), was less than 10 nanoseconds. The relative frequency difference between the NPL and Raisting Clocks, SNPL, RAIS, as measured over the 44 days period was found to be -15.7 x 10 to the -13th power. The relative frequency difference between PTB Primary Standard and Raisting Clock, SPTB, RAIS, during this period, was measured to be -22.8 x 10 to the -13th power. The relative frequency difference between NPL clock and PTB Primary Standard, SNPL, PTB, thus, is +7.1 x 10 to the -13th power. The clock rate (UTC, India) of +7.1 + or - 0.5 x 10 to the -13th power, agrees well with that obtained via VLF phase measurements over one year period and with USNO travelling clock time comparisons made in September, 1980.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Proc. of the 12th Ann. Precise Time and Time Interval Appl. and Planning Meeting; p 863-874
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  • 65
    Publication Date: 2016-06-07
    Description: A satellite time receiver was tested in various environmental conditions during the past year. The commercial receiver designed to work with the National Oceanic and Atmospheric Administration's (NOAA) Geostationary Operational Environmental Satellites (GOES). The test program included operation at low elevation during flight in a military cargo aircraft and long term comparison with laboratory standards. The GOES satellite time receiver offers an opportunity to provide easy wide area coverage synchronization at low cost.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Proc. of the 12th Ann. Precise Time and Time Interval Appl. and Planning Meeting; p 351-376
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  • 66
    Publication Date: 2016-06-07
    Description: A spherical array of twenty LiF 200 crystals was built to test the performances of a freestanding, self-focussing spherical crystal cosmic X-ray spectrometer. Measurements presently available show that the size of the image for a point source at infinite distance would be 3 mm (FWHM) along the focalisation axis and 2.1 mm (FWHM) along the dispersion axis. The mosaic spread on individual crystals is less than 0.1 degree. A slightly systematic deviation from the ideal bending (0.1 degree) is observed at the edges of most crystals and this appears to be the major limitation to spectrometer performance.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center X-ray Astronomy in the 1980'; p 523-526
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  • 67
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    Publication Date: 2016-06-07
    Description: A design for a diffuse X-ray spectrometer utilizing Bragg reflection is described. The geometry has a very high throughput for a given physical size and allows simultaneous observation at all wavelengths within its range. Spectral resolving power is about 35 to 50. A similar unit equipped with thallium acid pthallate crystals will cover the 11 - 24 A-range with about half this throughput and twice the resolving power.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center X-ray Astronomy in the 1980's; p 379-401
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  • 68
    Publication Date: 2016-06-07
    Description: Results of intial performance tests on X-ray sensing properties of charge-coupled devices (CCDs) are presented. CCDs have demonstrated excellent spatial resolution and good spectral resolution, superior to that of non-imaging proportional counters.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center X-ray Astronomy in 1980's; p 289-299
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  • 69
    Publication Date: 2019-06-28
    Description: The Pinhole Occulter Facility (P/OF) is a Space Shuttle based experiment for the production of solar coronographics and hard X-ray images. The system is basically pinhole camera utilizing a deployable 50-m flexible boom for separating the pinholes and coronograph shields from the recording devices located in the Shuttle bay. At the distal end of the boom from the Shuttle is a 25 kg mask containing pinholes and coronograph shields. At the proximal end the detectors are located and mounted, along with the deployable boom, to the ASPS gimbal pointing system (AGS). The mask must be pointed at the Sun with a high degree of pointing stability and accuracy to align the axes of the detectors with the pinholes and shields. Failure to do so will result in a blurring of the images on the detectors and a loss of resolution. Being a Shuttle based experiment, the system will be subjected to the disturbances of the Shuttle. The worst of these is thruster firing for orbit correction; the Shuttle uses a bang-bang thruster control system to maintain orbit to within preset limits. Other disturbances include man motion, motion induced by other systems, and gravity gradient torques.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-171152 , NAS 1.26:171152 , BER-274-100
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  • 70
    Publication Date: 2019-06-28
    Description: An analysis of pixel labeling by probabilistic relaxation techniques is presented to demonstrate that these labeling procedures degenerate to weighted averages in the vicinity of fixed points. A consequence of this is that undesired label conversions can occur, leading to a deterioration of labeling accuracy at a stage after an improvement has already been achieved. Means for overcoming the accuracy deterioration are suggested and used as the basis for a possible design strategy for using probabilistic relaxation procedures. The results obtained are illustrated using simple data sets in which labeling on individual pixels can be examined and also using Landsat imagery to show application to data typical of that encountered in remote sensing applications.
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  • 71
    Publication Date: 2019-06-28
    Description: A method is proposed for optimizing the on-axis resolution of a Kirkpatrick-Baez reflecting element. The proposed procedure provides a way to determine the location of each of the 11,200 support points (175 different points plus repeats) by using a computer-assisted structural-optical software package. This automated procedure will make it possible to determine the optical characteristics of an entire telescope module consisting of seventy mirrors.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 20; May 1
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  • 72
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    Publication Date: 2019-06-28
    Description: A programmable system for enhancing monocular and stereographic images at video rates is presented. The system provides both automatic and interactive enhancement modes based on histogram modification and intensity mapping techniques. Experimental results which illustrate enhancement capabilities under a variety of scene types and conditions are described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE; vol. 69
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  • 73
    Publication Date: 2019-06-28
    Description: A determination of the plasma potential using an electrostatic analyzer is described in which the potential difference between the instrument slit system and surrounding plasma is minimized. Data obtained from rocket-borne instrumentation demonstrate the viability of this technique for electron fluxes between thermal energies (about 0.5 V) and suprathermal energies (many volts).
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 52; Feb. 198
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  • 74
    Publication Date: 2019-06-28
    Description: The design and performance of an f/35 submillimeter photometer are discussed. It is noted that the instrument provides for both broad- and medium-width passbands between 350 microns and 2 mm and for beam sizes between 28 arcsec and 100 arcsec FWHM. Under good atmospheric conditions, a broad-band 400 micron sensitivity of approximately 1.5 Jy is found to be obtainable in one hour. A description is given of the photometer's support housing, submillimeter radiometer, and electronics and data-handling system. In evaluating the performance, attention is given to sensitivity, beam profiles, and the effect of changes in the aperture on the signal.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Astronomical Society of the Pacific; vol. 92
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  • 75
    Publication Date: 2019-06-28
    Description: CaF2 beam splitters and compensation and test cell windows have been installed in a VUV Mach-Zehnder interferometer. Results of an evaluation of their performance in the VUV, namely, a measurement of the oscillator strength (f value) of the resonance transition at atomic xenon at 146.9610 nm are reported.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 20; Feb. 15
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  • 76
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    Publication Date: 2019-06-28
    Description: Spectrophotopolarimetric capability can be added to a laboratory interferometer-spectrometer by use of a specially designed module described herein. With the instrument so augmented, high-resolution spectra can be obtained of the Stokes parameters of the reference beam and the beams diffusely reflected or transmitted by a sample medium of interest. For any such beam, the exponential Fourier transforms of the two interferograms obtained with a polarizer-analyzer oriented along the 0 deg and the 90 deg directions provide the spectra of I and Q, separately. Within experimental (and numerical) noise, this I spectrum should be the same as the one obtained with the polarizer removed. The remaining Stokes parameters U and V are obtained with a third interferogram recorded with the polarizer along the 45 deg direction. The complete theory of this instrument is described including the detailed analysis of the polarization-interferograms it provides.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering; 20; Jan
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  • 77
    Publication Date: 2019-06-28
    Description: Information theory is used to formulate a single figure of merit for assessing the performance of line scan imaging systems as a function of their spatial response (point spread function or modulation transfer function), sensitivity, sampling and quantization intervals, and the statistical properties of a random radiance field. Computational results for the information density and efficiency (i.e., the ratio of information density to data density) are intuitively satisfying and compare well with experimental and theoretical results obtained by earlier investigators concerned with the performance of TV systems.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-TP-1897 , L-14542
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  • 78
    Publication Date: 2019-06-28
    Description: A scheme for flicker noise generation is given. The second approach is that of successive segmentation: A clock fluctuation is represented by 2N piecewise linear segments and then converted into a summation of N+1 triangular pulse train functions. The statistics of the clock instability are then formulated in terms of two sample variances at N+1 specified averaging times. The summation converges very rapidly that a value of N 6 is seldom necessary. An application to radio interferometric geodesy shows excellent agreement between the two approaches. Limitations to and the relative merits of the two approaches are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Proc. of the 12th Ann. Precise Time and Time Interval Appl. and Planning Meeting; p 681-701
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  • 79
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    In:  CASI
    Publication Date: 2019-06-28
    Description: The pinhole occulter system, a space shuttle based experiment for the production of hard X-ray images taken primarily from the Sun is described. The system is a pinhole camera utilizing a deployable 50 m flexible boom for separating the pinhole from the recording devices located in the shuttle. The system is subjected to the disturbances of the shuttle. The worst of these are thruster firing for orbit correction, man motion, motion induced by other systems, and gravity gradient torques. The control system of the pointing mount senses both position and velocity of the mask tip and uses these to estimate accurately the flexible modes of the system.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-161819
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  • 80
    Publication Date: 2019-06-28
    Description: A sample having self subtraction characteristics that were very promising was tested in depth: hologram formation times were on the order of 150 sec, the null signal was less than 2.5% of the peak signal, and no fatigue nor instability was detected over the span of the experiments. Another sample, fabricated with, at most, slight modifications did not perform nearly as well. In all samples, attempts to improve self subtraction characteristics by various thermal treatments had no effects or adverse effects, with one exception in which improvement was noted after a time delay of several days. A theory developed to describe self subtraction showed the observed decrease in beam intensity with time, but the shape of the predicted decay curve was oscillatory in contrast to the exponential like decay observed. The theory was also inadequate to account for the experimental sensitivity of self subtraction to the Bragg angle of the hologram. It is concluded that self subtraction is a viable method for optical processing systems requiring background discrimination.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-159336
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  • 81
    Publication Date: 2019-06-28
    Description: A calorimeter apparatus for measuring high temperature thermophysical properties of materials is disclosed which includes a containerless heating apparatus in which the specimen is suspended and heated by electron bombardment.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 82
    Publication Date: 2019-06-28
    Description: Possible sources of systematic error in solar Doppler rotational velocities are examined. Scattered light is shown to affect the Mount Wilson solar rotation results, but this effect is not enough to bring the spectroscopic results in coincidence with the sunspot rotation. Interference fringes at the spectrograph focus at Mount Wilson have in two intervals affected the rotation results. It has been possible to correlate this error with temperature and thus correct for it. A misalignment between the entrance and exit slits is a possible source of error, but for the Mount Wilson slit configuration, the amplitude of this effect is negligibly small. Rapid scanning of the solar image also produces no measurable effect.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Solar Physics; 73; Sept
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  • 83
    Publication Date: 2019-06-28
    Description: An optical scanner using the principle of light reflection has been designed for determining directional slope distributions of the wind-disturbed water surface. The instrument has been tested successfully in the laboratory and could be used in the field. Some sample results along with procedures for data analysis are also presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: AD-A143152 , Review of Scientific Instruments; 52; Aug. 198
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  • 84
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    In:  Other Sources
    Publication Date: 2019-06-28
    Description: The microchannel array plate (MCP) is a photoelectric detector with an imaging capability comparable to that of a photographic plate. Recently MCPs in which the channels are curved to inhibit ion feedback have become available. These devices represent a major advance in MCP technology, since a single curved-channel MCP can be operated stably at high gain in the pulse-counting mode without any of the problems of stability of response or short lifetime reported for 'chevron' MCP detectors. Attention is given to the mode of operation of channel electron multipliers (CEM) and MCP, curved-channel MCP, test procedures, and performance characteristics. The accumulated test data show that the fundamental operating characteristics of the curved-channel MCP are directly related to those for the CEM.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 52; Aug. 198
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  • 85
    Publication Date: 2019-06-28
    Description: A laser Doppler velocimeter employing a microscope objective as the receiving lens has been developed for measuring fluid velocity inside the boundary layer flow field with a spatial resolution of 40 microns. The method was applied for direct measurement of aerodynamic skin friction drag from the measured velocity gradient at the wall. Experimental results obtained on skin friction and on velocity components in a turbulent boundary layer on a low speed wind tunnel showed good agreement with previously reported data using conventional instruments such as hot-wire anemometers and Preston tubes. The method thus provides a tool for measurement and control of skin friction on aerodynamic bodies without perturbing the flow field.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 20; Aug. 15
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  • 86
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    In:  Other Sources
    Publication Date: 2019-06-28
    Description: A new instrument which combines the good energy resolution of the gas scintillation proportional counter with the high position resolution of the microchannel plate is proposed. A study of the factors which determine the combined energy and position resolution of the new instrument is discussed. Submillimeter position resolution along with good energy resolution (8% fwhm at 6 keV) should be achievable.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Nuclear Instruments and Methods; 184; 1981
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  • 87
    Publication Date: 2019-06-28
    Description: The formulation of the crossed beam correlation technique is generalized to include strongly absorbing media. The first measurements of point density fluctuations at contact surfaces have been obtained. The presence of turbulent bursts is confirmed and a characteristic spectral frequency of approximately 400 Hz is estimated.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 52; June 198
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  • 88
    Publication Date: 2019-06-28
    Description: A simple method of determining thin film parameters from mode indices measured using a prism coupler is described. The problem is reduced to doing two least squares straight line fits through measured mode indices vs effective mode number. The slope and y intercept of the line are simply related to the thickness and refractive index of film, respectively. The approach takes into account the correlation between as well as the uncertainty in the individual measurements from all sources of error to give precise error tolerances on the best fit values. Due to the precision of the tolerances, anisotropic films can be identified and characterized.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 20; June 15
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  • 89
    Publication Date: 2019-06-28
    Description: A pulsed dual-laser direct-detection differential-absorption lidar DIAL system, operating near 10.6 microns, is used to measure the temporal correlation and statistical properties of backscattered returns from specular and diffuse topographic targets. Results show that atmospheric-turbulence fluctuations can effectively be frozen for pulse separation times on the order of 1-3 msec or less. The diffuse target returns, however, yielded a much lower correlation than that obtained with the specular targets; this being due to uncorrelated system noise effects and different statistics for the two types of target returns.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: AD-A105373 , ESD-TR-81-238 , Optics Letters; 6; June 198
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  • 90
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    In:  CASI
    Publication Date: 2019-06-28
    Description: Specifications for the pointing stabilization system of the large space telescope were used in an investigation of the feasibility of reducing ring laser gyro output quantization to the sub-arc-second level by the use of phase locked loops and associated electronics. Systems analysis procedures are discussed and a multioscillator laser gyro model is presented along with data on the oscillator noise. It is shown that a second order closed loop can meet the measurement noise requirements when the loop gain and time constant of the loop filter are appropriately chosen. The preliminary electrical design is discussed from the standpoint of circuit tradeoff considerations. Analog, digital, and hybrid designs are given and their applicability to the high resolution sensor is examined. the electrical design choice of a system configuration is detailed. The design and operation of the various modules is considered and system block diagrams are included. Phase 1 and 2 test results using the multioscillator laser gyro are included.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-161843 , ER81-4177
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  • 91
    Publication Date: 2019-06-28
    Description: A prototype water quality monitoring system is described which offers almost continuous in situ monitoring. The two-man portable system features: (1) a microprocessor controlled central processing unit which allows preprogrammed sampling schedules and reprogramming in situ; (2) a subsurface unit for multiple depth capability and security from vandalism; (3) an acoustic data link for communications between the subsurface unit and the surface control unit; (4) eight water quality parameter sensors; (5) a nonvolatile magnetic bubble memory which prevents data loss in the event of power interruption; (6) a rechargeable power supply sufficient for 2 weeks of unattended operation; (7) a water sampler which can collect samples for laboratory analysis; (8) data output in direct engineering units on printed tape or through a computer compatible link; (9) internal electronic calibration eliminating external sensor adjustment; and (10) acoustic location and recovery systems. Data obtained in Saginaw Bay, Lake Huron are tabulated.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-TM-83152 , EPA-600/4-81-061
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  • 92
    Publication Date: 2019-06-28
    Description: The 10,000 solar constant radiometer was developed for the accurate (+ or - 1%) measurement of the irradiance produced in the image formed by a parabolic reflector or by a multiple mirror solar installation. This radiometer is water cooled, weighs about 1 kg, and is 5 cm (2 in.) in diameter by 10 cm (4 in.) long. A sting is provided for mounting the radiometer in the solar installation capable of measuring irradiances as high as 20,000 solar constants, the instrument is self calibrating. Its accuracy depends on the accurate determination of the cavity aperture, and absorptivity of the cavity, and accurate electrical measurements. The spectral response is flat over the entire spectrum from far UV to far IR. The radiometer responds to a measurement within 99.7% of the final value within 8 s. During a measurement of the 10,000 solar constant irradiance, the temperature rise of the water is about 20 C. The radiometer has perfect cosine response up to 60 deg off the radiometer axis.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-164704 , JPL-PUB-81-42
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  • 93
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    In:  CASI
    Publication Date: 2019-06-28
    Description: The implementation of a rain detection capability for the NOSS Radar altimeter design is proposed which would require only minor hardware modifications to the Seasat altimeter design is proposed. The expected level of performance is indicated.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-TM-73291
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  • 94
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    In:  CASI
    Publication Date: 2019-06-28
    Description: A number of sampling services are disposed in a rack which slides into a housing. In response to a signal from an antenna, the circutry elements are activated which provide power individually, collectively, or selectively to a servomechanism thereby moving an actuator arm and the attached jawed bracket supporting an evaculated tube towards a stationary needle. One open end of the needle extends through the side wall of a conduit to the interior and the other open end is maintained within the protective sleeve, supported by a bifurcated bracket. A septum in punctured by the end of the needle within the sleeve and a sample of the fluid medium in the conduit flows through the needle and is transferred to a tube. The signal to the servo is then reversed and the actuator arm moves the tube back to its original position permitting the septum to expand and seal the hole made by the needle. The jawed bracket is attached by pivot to the actuator to facilitate tube replacement.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 95
    Publication Date: 2019-06-28
    Description: Measurements of thermal ions are influenced by factors such as spacecraft potential, velocity, angle of attack, and sheath size. A theory is presented for the response of an instrument which accepts ions only within a small angle of incidence from normal. Although a more general theory is available and forms the basis of this one, the small angle restriction allows a simpler formulation which does not depend on sheath size. Furthermore, practical instruments are easily designed around this restriction. Laboratory tests verify that such instruments respond as expected and they illustrate how design details influence perturbations from the ideal response characteristics.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-164378
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  • 96
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    In:  Other Sources
    Publication Date: 2019-06-28
    Description: A quarter-meter diameter, modified Ritchey-Chretien camera is described for spacecraft-based observation of Halley's Comet. The system will operate over an unusually broad spectral region, from 0.1216 micron (the hydrogen Lyman-alpha line) to 1.1 microns using reflective primary and secondary mirror optics and a thin UV-grade lithium fluoride refractive element as a field corrector near the image plane. The f/12, 3000 mm focal length camera has a 0.4 deg full field of view for operation with a 15 x 15 mm charge-coupled device detector array. The UV-enhanced silicon CCD detector is a 1000 x 1000 array of 15 micron pixels which establishes the system resolution requirement. The optical design and performance are discussed, with an emphasis on the image analysis with respect to pixel resolution elements used for viewing extended objects such as comets.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering; 20; Nov
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  • 97
    Publication Date: 2019-06-28
    Description: It is demonstrated that for maximizing the scientific output of future ion cloud release experiments a new type of instrument is required which will measure the line of sight velocity of the ion cloud by the Doppler Technique. A simple instrument was constructed using a 5 cm diameter solid Fabry-Perot etalon coupled to a low light level integrating television camera. It was demonstrated that the system has both the sensitivity and spectral resolution for the detection of ion clouds and the measurement of their line of sight Doppler velocity. The tests consisted of (1) a field experiment using a rocket barium cloud release to check the sensitivity, (2) laboratory experiments to show the spectral resolving capabilities of the system. The instrument was found to be operational if the source was brighter than about 1 kilorayleigh and it had a wavelength resolution much better than .2A which corresponds to about 12 km/sec or an acceleration potential of 100 volts.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-169394 , NAS 1.26:169394
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  • 98
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    In:  Other Sources
    Publication Date: 2019-06-28
    Description: The employment of superconductivity and other material properties at cryogenic temperatures to fabricate sensitive, low-drift, gravity gradiometer is described. The device yields a reduction of noise of four orders of magnitude over room temperature gradiometers, and direct summation and subtraction of signals from accelerometers in varying orientations are possible with superconducting circuitry. Additional circuits permit determination of the linear and angular acceleration vectors independent of the measurement of the gravity gradient tensor. A dewar flask capable of maintaining helium in a liquid state for a year's duration is under development by NASA, and a superconducting tensor gravity gradiometer for the NASA Geodynamics Program is intended for a LEO polar trajectory to measure the harmonic expansion coefficients of the earth's gravity field up to order 300.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 99
    Publication Date: 2019-06-28
    Description: By sputtering, it is possible to make multilayered structures (layered synthetic microstructures or LSMs) with individual layers as thin as a fraction of a nanometer. These techniques have been used to make a multilayered interference mirror to reflect carbon K X rays (at a wavelength of 4.48 nm) at normal incidence. The structure consists of 76 layers of tungsten of thickness 0.765 nm with layers of carbon (thickness 1.510 nm) interspersed, deposited on a 111 line type silicon wafer substrate. This LSM was formed into a concave mirror of radius approximately 1.1 m by bending the substrate, and used in an optical set-up to form images of grids illuminated by an X-ray source. The mirror was found to have a resolution of 5 lines/mm and an efficiency, integrated over the CK band, of between 4 and 8%.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Nature; 294; Dec. 3
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  • 100
    Publication Date: 2019-06-28
    Description: It is shown that CW CARS can be used to measure velocity in supersonic flows. The accuracy with which the Doppler shift can be measured is determined through the drift in the laser frequencies. In the experiment described here, it is found that a laser drift error of 10 MHz during the recording of a spectrum would limit the velocity resolution to 34 m/s. It is noted that improved frequency stabilization of the laser sources could lead to a velocity measurement accuracy of several m/s. In the experiment, a 4-W single axial mode argon ion laser is the pump source, and the Stokes-shifted frequency is generated by a 100-mW tunable dye laser.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Journal of Quantum Electronics; QE-17; Dec. 198
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