Teich, M. C. (1968). Infrared heterodyne detection. In Proc. IEEE (Vol. 56, pp. 37–46). IEEE.
Abstract: Heterodyne experiments have been performed in the middle infrared region of the electromagnetic spectrum using the CO2laser as a radiation source. Theoretically optimum operation has been achieved at kHz heterodyne frequencies using photoconductive Ge:Cu detectors operated at 4°K, and at kHz and MHz frequencies using Pb1-xSnxSe photovoltaic detectors at 77°K. In accordance with the theory, the minimum detectable power observed is a factor of 2/η greater than the theoretically perfect quantum counter, hvΔf. The coefficient 2/η varies from 5 to 25 for the detectors investigated in this study. A comparison is made between photoconductive and photodiode detectors for heterodyne use in the infrared, and it is concluded that both are useful. Heterodyne detection at 10.6 µm is expected to be useful for communications applications, infrared radar, and heterodyne spectroscopy. It has particular significance because of the high radiation power available from the CO2laser, and because of the 8 to 14 µm atmospheric window.
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Johnson, M. A., Betz, A. L., McLaren, R. A., Townes, C. H., & Sutton, E. C. (1976). Nonthermal 10 micron CO2 emission lines in the atmospheres of Mars and Venus. A&A, 208, 145.
Keywords: carbon dioxide, emission spectra, infrared spectra, mars atmosphere, nonthermal radiation, optical heterodyning, planetary radiation, venus atmosphere, absorption spectra, energy transfer, line spectra, molecular absorption, molecular collisions, near infrared radiation, solar flux
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Betz, A. L., Johnson, M. A., McLaren, R. A., & Sutton, E. C. (1976). Heterodyne detection of CO2 emission lines and wind velocities in the atmosphere of Venus. Astrophys. J., 208, L141–L144.
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Soifer, B. T., & Pipher, J. L. (1978). Instrumentation for infrared astronomy. Annual Rev. Astron. Astrophys., 16(1), 335–369.
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Rothermel, H., Käufl, H. U., & Yu, Y. (1983). A heterodyne spectrometer for astronomical measurements at 10 micrometers. A&A, 126, 387–392.
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