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Proceedings Paper

Comparison of spectral transmittance degradation due to organic gas contamination with on-orbit degradations of launched sensors
Author(s): Nobunari Itoh; Masahiro Katoh; Nobuaki Okano
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Paper Abstract

Gas adsorption onto optical surfaces installed on satellites is one of the causes of signal degradation that occurs in orbit. To estimate the transmittance degradation caused by gas adsorption, transmittance measurements were carried out within the wavelength range of 200 nm to 14 μm. Five types of glasses, SiO2, BK7, Al2O3, CaF2 and ZnSe were selected as glass samples and three gas species were chosen as the adsorption gas samples: 2-propanol, ethyl acetate and dichloromethane. These three molecules are typical paint solvents. In the IR wavelength range, several absorption bands corresponding to vibration and/or bending transitions of the functional groups present in the adsorbed molecules were detected. In the UV-VIS wavelength range, there were no local absorption features; however, broad transmittance degradations were detected. The comparison of measured spectral transmittance degradations with sensor output degradations showed that the signal degradations of launched sensors were similar to the transmittance degradation due to 2-propanol or dichloromethane adsorption. Moreover, we estimated the growth rate of the adsorbed molecular film thickness using the degradation data of the orbiting sensor, MODIS/Aqua, under the assumption that the signal degradation was caused by organic gas adsorption. Our estimation showed that the growth rate of an adsorbed molecular film decreased with time after the launch.

Paper Details

Date Published: 11 December 2008
PDF: 10 pages
Proc. SPIE 7149, Multispectral, Hyperspectral, and Ultraspectral Remote Sensing Technology, Techniques, and Applications II, 71490F (11 December 2008); doi: 10.1117/12.804917
Show Author Affiliations
Nobunari Itoh, Mie Univ. (Japan)
Masahiro Katoh, Univ. of Tokushima (Japan)
Nobuaki Okano, Univ. of Tokushima (Japan)

Published in SPIE Proceedings Vol. 7149:
Multispectral, Hyperspectral, and Ultraspectral Remote Sensing Technology, Techniques, and Applications II
Allen M. Larar; Mervyn J. Lynch; Makoto Suzuki, Editor(s)

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