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  • 1
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    Neutron transmutation doped Ge bolometers (1983)
    In:  CASI
    Details
    Publication Date: 2004-12-04
    Description: Some conclusions reached are as follow. Neutron Transmutation Doping (NTD) of high quality Ge single crystals provides perfect control of doping concentration and uniformity. The resistivity can be tailored to any given bolometer operating temperature down to 0.1 K and probably lower. The excellent uniformity is advantaged for detector array development.
    Keywords: SOLID-STATE PHYSICS
    Type: NASA. Ames Research Center, Infrared Detector Technology Workshop; 10 p
    Format: text
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  • 2
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    Ge:Be far infrared photoconductors (1983)
    In:  CASI
    Details
    Publication Date: 2004-12-04
    Description: Some conclusions reached are as follow. Ge:Be detectors provide lower Noise Equivalent Power (NEP) and higher responsivities than state of the art Ge:Ga detectors at 42 microns. Reliable Be doping was achieved with Czochralski growth from a carbon susceptor under vacuum. The photoconductive behavior of Ge:Be detectors is strongly influenced by the concentration of residual shallow impurities. Optimization of Ge:Be detectors requires both a low concentration and precise compensation of shallow acceptors.
    Keywords: OPTICS
    Type: NASA. Ames Research Center, Infrared Detector Technology Workshop; 10 p
    Format: text
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  • 3
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    A cryogenic blackbody for millimeter wavelengths (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The present cryogenic blackbody reference, or 'cold load', for mm-wavelength radiation has an emissivity of more than 0.99 over a two-octave wavelength range and can be used as a calibrating standard for sensitive IR photometers. The transmittance spectrum obtained indicates that wave impedance and index do not vary significantly over the 80-360 GHz range.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: International Journal of Infrared and Millimeter Waves (ISSN 0195-9271); 5; 1507-151
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  • 4
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    Parametric amplification and oscillation at 36 GHz using a point-contact Josephson junction (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The paper reports observation of doubly degenerate parametric amplification and oscillation at 36 GHz from a single point-contact Josephson junction. The experimental results agree qualitatively with theoretical calculations based on the resistively shunted junction model. The estimated noise temperature of an amplifier with 11 dB net gain is consistent with zero, but has an upper limit of 50 K. Attempts to observe parametric amplification in the singly degenerate mode with a pump frequency of 72 GHz were not successful.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Journal of Applied Physics; 48; Mar. 197
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  • 5
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    Near millimeter wave bandpass filters (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The properties of bandpass filters for broadband photometry are reported in the 3-12/cm frequency range. The filters are based on a combination of capacitive grids deposited on thick Mylar substrates and are designed to have very high out-of-band rejection. Low frequencies are blocked by a thick grill that consists of a hexagonal grid of circular holes in a thick metal plate.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Applied Optics; 20; Apr. 15
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  • 6
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    Grid polarizers for infrared Fourier spectrometers (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Infrared grid polarizers consisting of copper lines with a 3.6-micron grid constant on a 4-micron-thick Mylar polyester substrate have been prepared by the techniques of photolithography and sputter-etching. Their polarization properties have been measured and found to be suitable for use at infrared frequencies below 700/cm. The polarizers have been used to extend the useful frequency range of a Martin-Puplett polarizing interferometer designed for Fourier transform spectroscopy. The efficiency of the interferometer has been measured over a frequency range from 50 to 700/cm and compared to that of a conventional Michelson interferometer. The results are shown to be consistent with the measured properties of the polarizers. Methods are suggested for improving the efficiency of a Martin-Puplett interferometer which employs these polarizers.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Infrared Physics; 20; July 198
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  • 7
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    Stressed Ge:Ga photoconductors for space-based astronomy. (Is there life beyond 120 micron) (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Information is given in viewgraph form. Information is given on the characteristics of stressed Ge:Ga, a spring type stress cavity, mounting hardware, materials parameters affecting dark current, and the behavior of low dark current stressed Ge:Ga. It is concluded that detectors exist today for background-limited detection at 200 microns, that researchers are narrowing in on the significant parameters that effect dark current in stressed photoconductors, that these findings may be applied to other photoconductor materials, and that some creative problem solving for an ionizing effect reset mechanism is needed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA, Ames Research Center, Proceedings of the Third Infrared Detector Technology Workshop; p 5-2
    Format: application/pdf
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  • 8
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    A broadband THz receiver for low background space applications (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: We have developed a sensitive bolometric receiver for low background space applications. In a 10 percent bandwidth at 1 THz, this receiver is approximately 100 times more sensitive than a quantum limited heterodyne receiver with a 1 GHz IF bandwidth. This receiver is designed to be used for the long wavelength band (200-700 microns) in the MIPS instrument on NASA's SIRTF satellite. The bolometers are cooled to 100 mK by an adiabatic demagnetization refrigerator. Roughly 60 g of cesium chrome alum salt is partially demagnetized to 100 mK, followed by a slow regulated downramp to compensate for the heat leak. The hold time of the ADR system is about 18 hours with a temperature stability of delta T(sub rms) approx. equals 10 micro-K. The composite bolometers have electrical responsivities of 10(exp 9)V/W and electrical NEP's of about 3x10(exp -17) W/square root of Hz. The bolometer signals are read out by JFET preamplifiers located on the helium plate and operated at 120 K. We have addressed a number of space qualification issues, such as the development of an analog magnet controller, construction of a cryogenic shake-table for bolometers and selection of the paramagnetic salt CCA which can survive a bakeout at 50 C. The receiver is scheduled to be flown in the spring of 1992 on a balloon telescope. This flight has a dual purpose. One is to provide realistic test of the capabilities of the new receiver. The other is to search for anisotropies in the cosmic microwave background on scales of a few degrees.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Michigan Univ., The Third International Symposium on Space Terahertz Technology: Symposium Proceedings; p 678-687
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  • 9
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    A two-stage magnetic refrigerator for astronomical applications with reservoir temperatures above 4 K (1993)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: We propose a novel adiabatic demagnetization refrigerator (ADR) to produce temperatures as low as 100 mK starting from a high temperature reservoir between 4 and 8 K. The high temperature reservoir for the ADR can be provided by a mechanical cooler or an unpumped liquid helium bath. This refrigerator can be used to cool bolometric infrared detectors for low background astronomy from mountain tops, balloons or satellites as well as to cool cryogenic x-ray detectors. The two-stage ADR consists of a single magnet with a paramagnetic chromic-cesium-alum (CCA) salt pill to produce the low temperature and paramagnetic gadolinium-gallium-garnet (GGG) as the first stage to intercept heat from the high temperature reservoir. Thermal contact between the paramagnets and the reservoir during magnetization is made with a mechanical heat switch. The ADR is suspended with Kevlar chords under tension for high mechanical stiffness and low parasitic heat leak. In a single cycle, the ADR maintains a temperature of 100 mK for 10 to 100 hours. This time depends strongly on the magnetic field and reservoir temperature but not on the volume of the paramagnetic material as long as the heat leak is dominated by the suspension.
    Keywords: ENGINEERING (GENERAL)
    Type: NASA-CR-192365 , NAS 1.26:192365
    Format: application/pdf
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  • 10
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    Performance of Ge:Ga far infrared detectors (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A systematic study was carried out of the properties of Ge:Ga photoconductive infrared detectors for wavelengths approx. 100 micron. The detectors studied were made from Ge:Ga with acceptor concentration N sub A approx. 2 x 10 exp 14/cu cm with both low compensation (10 exp -2) and ultralow compensation (10 exp -4). Noise measurements have been made as a function of background photon rate, bias voltage, and chopping frequency. Detective quantum efficiencies approaching unity have been observed over a side range of experimental parameters. Photocurrent has been measured as a function of voltage and temperature. Hall mobility and lifetime have been measured to determine their effect on detector properties. A small potential drop has been observed in nominally ohmic contacts produced by implantation of B ions.
    Keywords: OPTICS
    Type: NASA. Ames Research Center, Infrared Detector Technology Workshop; 16 p
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