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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 438-444 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Instrumentation for making localized, precise relative reflection measurements of metals and superconductors in the terahertz frequency range is demonstrated. The results can be used to determine the surface resistivity of these materials which is of particular importance to development of high-temperature superconductors. Emission from a commerically available 1000 °C blackbody source was reflected from the materials under test and a reference reflector. The reflected signals were detected by a Schottky diode heterodyne receiver using a CO2-laser-pumped 214.5 μm CH2F2 laser as the local oscillator. Double-sideband bandwidth and receiver noise temperature were 2 GHz and 30 000 K, respectively. The use of a broadband incoherent diagnostic source minimizes instrumentation sensitivity to coherent interference effects. The heterodyne receiver provides for sensitive detection with good spatial and frequency resolution. Unoptimized spatial resolution of four times the diffraction limit was achieved. The potential for relative reflectivity measurement accuracy of better than 0.1% was demonstrated with 30 min measurement times though systematic errors limited actual measurement accuracy to about 0.3%.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 3962-3966 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The submillimeter optical properties of hot-pressed polycrystalline boron nitride with a predominantly hexagonal crystal structure were studied at room temperature from ∼20 to 120 cm−1 (λ=500–84 μm) with a Fourier-transform spectrometer. Several grades were studied and probed both parallel and perpendicular to the material's optic axis. The material was found to behave as a negatively uniaxial birefringent crystal. The birefringence, defined as the difference between the real part of the extraordinary and ordinary indices of refraction (ne–no), was quite large in one case with a value of −0.152. The material's absorption properties were also studied. For certain grades, a modest dichroism was observed. The low absorption (α〈1 cm−1) for grade A at frequencies below 38 cm−1 suggests the possibility for millimeter/submillimeter wave applications. Results are compared with data obtained by other researchers on related materials.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Infrared Physics 33 (1992), S. 219-226 
    ISSN: 0020-0891
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    International journal of infrared and millimeter waves 11 (1990), S. 1299-1302 
    ISSN: 1572-9559
    Keywords: Terahertz ; far-infrared ; submillimeter ; spectroscopy ; refractive index ; extinction coefficient ; dielectric constant ; absorption ; Rexolite™
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The far-infrared optical properties of Rexolite™ 1422 were characterized at the University of Lowell Research Foundation using Fourier transform spectroscopy. The spectroscopic transmission measurements were performed on a 0.0236″ thick sample of material over the submillimeter wavelength region from 10 cm−1 to 360 cm−1. Using multiple reflection theory for transmission through an etalon, the frequency dependent complex refractive index of Rexolite™ is reported.
    Type of Medium: Electronic Resource
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