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Results for “Fabry–Perot interferometer”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Neutral winds in the polar thermosphere as measured from Dynamics Explorer

Remote sensing measurements of the meridional thermospheric neutral wind using the Fabry-Perot Interferometer on Dynamics Explorer have been combined with in-situ measurements of the zonal component using the Wind and Temperature Spectrometer on the same spacecraft. The two data sets with appropriate spatial phasing and averaging determine the vector wind along the track of the polar orbiting spacecraft. A study of fifty-eight passes over the Southern (sunlit) pole has enabled the average Universal Time dependence of the wind field to be determined for essentially a single solar local time cut. The results show the presence of a 'back-ground' wind field driven by solar EUV heating upon which is superposed a circulating wind field driven by high latitude momentum and energy sources.

Killeen, T. L.↗
NASA NTRS1984

Plasma and magnetospheric research

Research activities on the following topics were summarized: (1) software for the Space Plasma computer Analysis Network (SPAN), (2) plasmaspheric field-aligned temperature gradients, (3) the shift in spacecraft potential as a function of plasma density, (4) plasma flow, (5) the Fabry-Perot interferometer, and (6) the Differential Ion Flux Probe (DIFP).

Comfort, R. H.↗
NASA NTRS1983

Optical effects of spacecraft-environment interaction Spectrometric observations by the DE-B satellite

Data from the Fabry-Perot interferometer on board the Dynamics Explorer-B satellite is used to show that the contaminant glow observed by Yee and Abreu at 7320A on the AE satellites is produced by emission lines of one or more species. A comparison is made of the contaminant spectrum near 7320A with the nightglow OH spectrum measured below 155km. Evidence is presented to the effect that OH might be one of the metastable species producing the glow.

Abreu, V. J.↗
NASA NTRS1983

O(1S) from dissociative recombination of O2(+) - Nonthermal line profile measurements from Dynamics Explorer

The measurements reported were made of the O(1S) emission line profile at 5577 A at high spectral resolution with the Fabry-Perot interferometer on the Dynamics Explorer spacecraft. It is found that the line profile has marked nonthermal characteristics in the nightglow. A simple collisional relaxation model is used to analyze the nighttime emission line profiles, measured in the equatorial region. The branching ratio is inferred for the dissociative recombination of O2(+) leading to O(1S). The result reveals that the O(1S) + O(1D) channel is favored over the O(1S). The result reveals that the O(1S) + O(1D) channel is favored over the O(1S) + O(3P) channel by a factor of 4; this does not agree with the ratio reported by Hernandez (1971). It is noted, however, that the result is consistent with the active channel for O(1S) production being via the 1Sigma u + repulsive state of O2, as suggested by the theoretical calculations of Guberman (1983). In addition, a value is obtained for the excitation exchange cross section for O(1S).

Killeen, T. L.↗
NASA NTRS1984

Spatial mapping of the thermospheric neutral wind field

There are many possible observing strategies available for mapping the thermospheric wind field by using observations of the Doppler shift of the O (1D) airglow with a Fabry-Perot interferometer. The determination of the neutral wind field from observed line-of-sight velocities invariably involves some assumptions about the nature of the wind field. A standard method of observing employs the assumption that horizontal gradients in the wind field are linear. An analysis of measurements from Arecibo, Puerto Rico, that makes use of this assumption, is discussed. For work at high latitudes this assumption may be unrealistic. An alternative approach that requires that local time and longitude be interchangeable but eschews the assumption of linear gradients has been developed and used at Ann Arbor, Michigan, and Calgary, Alberta. These different techniques are examined, and the discussion is illustrated with some typical results.

Tepley, C. A.↗
DOE OSTI2025

Fiber-optic bolometer with low detection limit fabricated using thermal release tape and precise laser heating

Fiber-optic bolometers (FOBs) based on a fiber-tipped silicon Fabry–Perot (FP) interferometric temperature sensor and a gold disk absorber have been shown to be an attractive alternative to conventional resistive bolometers for plasma radiation measurement in fusion devices. Either a high-finesse FP or a low-finesse FP can be used, each with trade-offs between noise performance and fabrication complexity. In this paper, we present an FOB design that overcomes these limitations by combining a low-finesse long silicon FP cavity with a large gold disk absorber to achieve enhanced sensitivity and noise performance without increasing the fabrication complexity and the time constant. We also demonstrated a fabrication method for the sensor head facilitated by thermal release tape and precise laser heating. Our FOB demonstrates a temperature resolution of 0.08 mK, a cooling time constant of 230 ms, and a noise equivalent power density of 0.015 W m −2 . This represents an eightfold improvement over previous high-finesse FOBs and 26-fold improvement over previous low-finesse FOBs with similar demodulation bandwidths and similar cooling time constants.

Fabry–Perot interferometer↗
NASA NTRS1983

The High Spectral Resolution Lidar

The High Spectral Resolution Lidar (HSRL) system was developed for the remote measurement of atmospheric optical properties. Measurements are obtained by the separation of the backscattered signal into aerosol and molecular channels using a high spectral resolution Fabry-Perot optical interferometer to separate the aerosol contributions to backscatter near the laser wavelength from the Doppler-shifted molecular component of the backscatter. The transmitter consists of an optically pumped pulsed dye laser of the oscillator-amplifier design which emits at 467.88 nm, with a bandwidth of less than 0.3 pm. The transmitter and receiver share a common Schmidt-Cassegrain telescope, although they do not share the same field stop, but rather two conjugate stops. The HSRL system uses a computer-controlled dual-channel photon-counting data acquisition system providing for stable measurements at very low power levels and an excellent dynamic range. The system has been used to obtain airborne measurements of height profiles of aerosol and molecular backscatter cross sections.

Eloranta, E. W.↗
NASA NTRS1983

High spectral resolution lidar to measure optical scattering properties of atmospheric aerosols. I - Theory and instrumentation

A high spectral resolution lidar technique to measure optical scattering properties of atmospheric aerosols is described. Light backscattered by the atmosphere from a narrowband optically pumped oscillator-amplifier dye laser is separated into its Doppler broadened molecular and elastically scattered aerosol components by a two-channel Fabry-Perot polyetalon interferometer. Aerosol optical properties, such as the backscatter ratio, optical depth, extinction cross section, scattering cross section, and the backscatter phase function, are derived from the two-channel measurements.

Shipley, S. T.↗
NASA NTRS1971

A pressure scanning Fabry-Perot magnetometer.

Description of an oscillating magnetic analyzer (KDP crystal plus Glan-Thompson prism) coupled to an echelle-interferometer spectrograph, and of single-slit magnetometer which by pressure variations can be made to scan the entire profiles of the circularly and linearly polarized Zeeman components. Freon gas is used as the scanner gas with wavelength displacements of 0.02 A per 0.1 in. Hg pressure change at the NaD lines. The available scan range is 15 A in the visual spectral region.

Fay, T. D.↗
NASA NTRS1977

Infrared Fabry-Perot and heterodyne spectrometers

The status of infrared instrumentation for astronomical investigations at U.C. Berkeley is described with emphasis on the techniques of high spectral and spatial resolution. Present instrumentation includes three Fabry-Perot spectrometers for the 10, 20, and 100 micron wavelength regions, a submillimeter receiver using an optically pumped laser, a 10 micron heterodyne spectrometer for studies of planetary atmospheres, and a 2-element 10 micron stellar interferometer for measuring the angular diameters of infrared stars.

Betz, A.↗