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Proceedings Paper • Open Access

Measuring, modeling and removing optical straylight from venμs super spectral camera images
Author(s): Philippe Gamet; Sébastien Fourest; Tuvia Sprecher; Emmanuel Hillairet

Paper Abstract

The Venμs Super Spectral Camera suffers from high level of optical straylight. The probable causes of this defect will be discussed. Two types of straylight are observed: local ghost is caused by scattering of optical surfaces of the instrument, and multiple reflexions between detector and filter or filter window, or lenses. Cross-talk ghost is constituted of light going through the filter of one band, and impacting another band on the same detector. It is caused by multiple reflexions between detectors and filter. The optical set-up used to evaluate the straylight patterns will be presented, and then, the approach used to characterize and model the observed phenomena will be detailed: Local straylight model is computed as a global system MTF that includes the local straylight. The assumption is made that the phenomenon can be modeled by a convolution, and that it is slowly variable within the instrument field of view. Crosstalk straylight is modeled from a pinhole, used to extract the impulsive response of the cross-talk. The cross-talk pattern is observed through the ghost generated by a saturated input signal. The cross-talk signals for all contributing bands of the same tri-detector are substracted from the image of each band. The performances of the correction model are presented: on the ground over test pattern images, and then in-flight during the image quality commissioning phase, over specific targets: moon, sand/water transitions.

Paper Details

Date Published: 12 July 2019
PDF: 24 pages
Proc. SPIE 11180, International Conference on Space Optics — ICSO 2018, 111804F (12 July 2019); doi: 10.1117/12.2536078
Show Author Affiliations
Philippe Gamet, Ctr. National d'Études Spatiales (France)
Sébastien Fourest, Ctr. National d'Études Spatiales (France)
Tuvia Sprecher, Elbit Systems Electro-Optics El-Op Ltd. (Israel)
Emmanuel Hillairet, Magellium Toulouse (France)


Published in SPIE Proceedings Vol. 11180:
International Conference on Space Optics — ICSO 2018
Zoran Sodnik; Nikos Karafolas; Bruno Cugny, Editor(s)

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