21 February 2014 The polarisation correction for space-borne grating spectrometers
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Abstract
Satellite measurements of backscattered sunlight contain essential information about the global distribution of atmospheric constituents. Light reflected from the Earth’s atmosphere is linearly or partially linearly polarized because of scattering of unpolarized sunlight by air molecules and aerosols. In the ultraviolet and visible part of the spectrum, measurements of space-borne grating spectrometers are in general sensitive to the state of polarization of the observed light. The interaction of polarized light with polarization-sensitive optical devices yields a different radiance that is measured by the detectors than the radiance that enters the instrument. In the OMI and the SBUV/2 instruments the problem of instrument polarization sensitivity is avoided because the polarized backscattered sunlight is depolarized before it interacts with the polarization-sensitive optical components. For GOME, SCIAMACHY, and GOME-2 it is intended to eliminate the polarization response of the instrument from the polarization-sensitive measurement. This paper discusses the basic concept of the polarisation correction of the space-borne grating spectrometers by using Mueller matrix calculus. A model was developed using the Mueller Matrices formulation to evaluate the polarization sensitivity of the space-borne grating spectrometers. The optical components are treated as general diattenuators with phase retardance. The correction for this polarization sensitivity is based on broadband polarization measurements. Accurate preflight polarisation calibration of space-borne grating spectrometers is essential for the observational objectives of the instrument, and a special facility has been developed in order to allow the instrument to be calibrated.
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Fa-cai Zhao, Fa-cai Zhao, Quan-she Sun, Quan-she Sun, Kun-feng Chen, Kun-feng Chen, Xing-bang Zhu, Xing-bang Zhu, Shao-shui Wang, Shao-shui Wang, Guo-quan Wang, Guo-quan Wang, Xiang-liang Zheng, Xiang-liang Zheng, Zhong Han, Zhong Han, } "The polarisation correction for space-borne grating spectrometers", Proc. SPIE 9142, Selected Papers from Conferences of the Photoelectronic Technology Committee of the Chinese Society of Astronautics: Optical Imaging, Remote Sensing, and Laser-Matter Interaction 2013, 91421C (21 February 2014); doi: 10.1117/12.2054036; https://doi.org/10.1117/12.2054036
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