Radiometric calibration and performance analysis of Fourier transform emission spectrometers

Daniel Lamarre; Jean Giroux; Henry L. Buijs

doi:10.1117/12.56316

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1 March 1992 Radiometric calibration and performance analysis of Fourier transform emission spectrometers

Daniel Lamarre, Jean Giroux, Henry L. Buijs

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Proceedings Volume 1575, 8th Intl Conf on Fourier Transform Spectroscopy; (1992) https://doi.org/10.1117/12.56316
Event: Eighth International Conference on Fourier Transform Spectroscopy, 1991, Lubeck-Travemunde, Germany

Abstract

FTIR instruments aimed at low temperature emission measurements require a two-point radiometric calibration because of significant emission from the instrument itself. Calibration measurements with two reference blackbodies are conducted for ground instruments. In space, the low temperature reference blackbody can be substituted with deep space observation. On the ground, pointing at a liquid nitrogen bath is used. Calibration operations involve complex arithmetics to obtain from reference and actual scene measurements a calibrated spectrum. Frequency and duration of calibration measurements are dependent upon instrument stability and noise budgets. When reference spectra are free of high resolution features, calibration measurements can be performed at a resolution lower than that of actual scene measurements. The Michelson interferometer for passive atmospheric sounding (MIPAS) will limb sound the atmosphere by measuring its mid-infrared emission with an apodized resolution of 0.05 cm-1. This instrument is used as an example to illustrate the trade-offs required in calibrating an emission FTIR. Given the current expected temperature variations of the instrument over the orbit, MIPAS will require a deep space reference measurement after every altitude scan, and a combined deep space and blackbody measurement at a lower frequency. For an adequate acquisition efficiency, low resolution calibration measurements are performed, at 0.2 cm-1 or 1 cm(superscript -1.

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Daniel Lamarre, Jean Giroux, and Henry L. Buijs "Radiometric calibration and performance analysis of Fourier transform emission spectrometers", Proc. SPIE 1575, 8th Intl Conf on Fourier Transform Spectroscopy, (1 March 1992); https://doi.org/10.1117/12.56316

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