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Proceedings Paper

Model Calculations Of Spectral Transmission For The CLAES Etalons
Author(s): T. C. James; A. E. Roche; J. B. Kumer
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Paper Abstract

The Cryogenic Limb Array Etalon Spectrometer (CLAES) to be flown on the Upper Atmosphere Research Satellite (UARS) is a limb viewing radiometer operating in nine wavelength channels between 3.5 and 13 μm. Each wavelength channel is selected by a combination of a solid Fabry-Perot etalon and suitable blocking filter. Spectral scanning within a given channel is achieved by tilting the etalon. The spectral transmission for a perfect etalon in a collimated beam is given by the Airy function. Deviations from perfect parallelism, absorption in the substrate and coatings, and the instrumental field of view produce changes in the spectral transmission. These changes affect the peak transmission (T), the full width at half maximum intensity (FWHM), and the overall shape of the transmission peaks. High-precision retrieval of geophysical parameters requires that the slit function of the instrument be accurately characterized. We have developed models to accurately characterize the slit function. These models involve a convolution of the Airy function for a given thickness with the distribution of surface thicknesses; the effect of absorption in the substrate, which must be taken into account for the CLAES etalon operating in the 10- to region; and the field of view broadening as a function of etalon tilt angle. We compare our model calculations with experimental transmission data for CLAES etalons centered at 3.52, 5.72, 8.0, and 11.86 μm. The model is also useful in setting tolerance limits on surface quality and permissible substrate absorption for other potential etalon applications.

Paper Details

Date Published: 27 April 1988
PDF: 8 pages
Proc. SPIE 0973, Cryogenic Optical Systems and Instruments III, (27 April 1988); doi: 10.1117/12.948383
Show Author Affiliations
T. C. James, Lockheed Research & Development Division (United States)
A. E. Roche, Lockheed Research & Development Division (United States)
J. B. Kumer, Lockheed Research & Development Division (United States)

Published in SPIE Proceedings Vol. 0973:
Cryogenic Optical Systems and Instruments III
Ramsey K. Melugin; Warren G. Pierce, Editor(s)

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