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Proceedings Paper • Open Access

Grating scattering BRDF and imaging performances: A test survey performed in the frame of the flex mission
Author(s): Bernd Harnisch; Atul Deep; Ramon Vink; Claude Coatantiec

Paper Abstract

Key components in optical spectrometers are the gratings. Their influence on the overall infield straylight of the spectrometer depends not only on the technology used for grating fabrication but also on the potential existence of ghost images caused by irregularities of the grating constant. For the straylight analysis of spectrometer no general Bidirectional Reflectance Distribution Function (BRDF) model of gratings exist, as it does for optically smooth surfaces. These models are needed for the determination of spectrometer straylight background and for the calculation of spectrometer out of band rejection performances.

Within the frame of the Fluorescence Earth Explorer mission (FLEX), gratings manufactured using different technologies have been investigated in terms of straylight background and imaging performance in the used diffraction order. The gratings which have been investigated cover a lithographically written grating, a volume Bragg grating, two holographic gratings and an off-the-shelf ruled grating. In this paper we present a survey of the measured bidirectional reflectance/transmittance distribution function and the determination of an equivalent surface micro-roughness of the gratings, describing the scattering of the grating around the diffraction order. This is specifically needed for the straylight modeling of the spectrometer.

Paper Details

Date Published: 20 November 2017
PDF: 10 pages
Proc. SPIE 10564, International Conference on Space Optics — ICSO 2012, 105642P (20 November 2017); doi: 10.1117/12.2309031
Show Author Affiliations
Bernd Harnisch, European Space Research and Technology Ctr. (Netherlands)
Atul Deep, European Space Research and Technology Ctr. (Netherlands)
Ramon Vink, European Space Research and Technology Ctr. (Netherlands)
Claude Coatantiec, ASTRIUM SAS (France)

Published in SPIE Proceedings Vol. 10564:
International Conference on Space Optics — ICSO 2012
Bruno Cugny; Errico Armandillo; Nikos Karafolas, Editor(s)

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