From Event: SPIE Astronomical Telescopes + Instrumentation, 2018
The MetOp-SG 3MI mission is part of the EUMETSAT Polar System Second Generation (EPS-SG), an Earth observation Program for Operational Meteorology from Low Earth Orbit. It consists of two multi-spectral cameras, one operating in VNIR and one in SWIR. With 13 spectral channels between 410nm and 2130nm, including polarized channels, the instrument covers a semi-field of view of 57°. Due to tight stray-light specifications, on-ground calibration and post-processing correction are required. This paper covers the stray-light correction and calibration methods. The correction is indeed based on the on-ground measurement of Spatial Point Source Transmittance (SPST) maps. Due to the limited amount of maps which can actually be calibrated within a reasonable amount of time, an interpolation method was developed to deduce the stray-light behavior in the whole field of view of the instrument. Furthermore, dynamic range decomposition was required during the acquisition of the maps to get a high signal to noise ratio. Ray-tracing data from the 3MI optical model were used to evaluate the performance of the correction algorithm, including the contribution of SPST maps interpolation and acquisition errors.
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L. Clermont, C. Michel, E. Mazy, C. Pachot, N. Daddi, C. Mastrandread, and Y. Stockman, "Stray-light calibration and correction for the MetOp-SG 3MI mission," Proc. SPIE 10704, Observatory Operations: Strategies, Processes, and Systems VII, 1070406 (Presented at SPIE Astronomical Telescopes + Instrumentation: June 11, 2018; Published: 10 July 2018); https://doi.org/10.1117/12.2314208.