Thermal infrared-imaging spectrometry with room-temperature optics

Clayton C. LaBaw

doi:10.1117/12.148060

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15 July 1993 Thermal infrared-imaging spectrometry with room-temperature optics

Clayton C. LaBaw

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Proceedings Volume 1874, Infrared and Millimeter-Wave Engineering; (1993) https://doi.org/10.1117/12.148060
Event: OE/LASE'93: Optics, Electro-Optics, and Laser Applications in Scienceand Engineering, 1993, Los Angeles, CA, United States

Abstract

Conventional approaches to spectroscopy at thermal infrared (IR) wavelengths have involved either cooling of the spectrometer to reduce background radiation in the waveband of interest, or the provision for a cold optical chopper, or both. These methods always required rigorous baffling, and often, relay optics to preclude the viewing of warm surrounds by the detectors, leading to increased cost, complexity, mass and power. A technique has been devised wherein energy at only the wavelength to be measured is imaged onto a detector column. This can provide radiance signal-to-(background) noise ratios > 300 when viewing the Earth in emitted thermal infrared while allowing the optics and the spectrometer to remain at local ambient temperature. Shuttering or chopping of the optical signal is not required with this scheme. A newly developed variable spectral filter is placed in proximity to the detector array to accomplish the necessary background radiation rejection. The theory leading to the development of this filter is described, and a discussion of the application to real optics/detector combinations is provided. A `proof-of-concept' instrument, the Thermal InfraRed Imaging Spectrometer has been built to demonstrate the practibility of the concepts described above. This unit and plans for developmental testing along with proposed areas of improvement are discussed.

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Clayton C. LaBaw "Thermal infrared-imaging spectrometry with room-temperature optics", Proc. SPIE 1874, Infrared and Millimeter-Wave Engineering, (15 July 1993); https://doi.org/10.1117/12.148060

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