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Proceedings Paper

Preliminary results on the EUCLID NISP stray-light and ghost analysis
Author(s): Norbert Geis; Frank Grupp; Eric Prieto; Ralf Bender
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Paper Abstract

The EUCLID mission within the European Space Agencies 2015 - 2025 Cosmic Vision framework addresses cosmological questions related to dark matter and dark energy. EUCLID is equipped with two instruments that are simultaneously observing patches of > 0:5 square degree on the sky. The VIS visual light high spacial resolution imager and the NISP near infrared spectrometer and photometer are separated by a di-chroic beam splitter. With its large FoV (larger than the full moon disk), together with high demands on the optical performance and strong requirements on in flight stability lead to very challenging demands on alignment and post launch { post cool-down optical element position. In addition the demanding requirements from spectroscopy and galaxy photometry lead to a highly demanding stray light and ghost control need. With this paper we present a preliminary - PDR level - analysis of ghosting and stray light levels in the EUCLID NISP near infrared spectrometer and photometer. The analysis presented focuses on the photometric channel, as this, together with the wide field of the instrument, shows most of the challenges and features of the instrument. As one requirement is to have a non vignetting design, extensive baffling is not possible, and only secondary and higher order light can be actively baffled. A comprehensive ZEMAX based analysis is being presented, showing in summary that baffles are only necessary due to the EUCLID fine guiding sensors auxiliary fields of view. The total level of contaminating light is thereafter dominated by stray light from dust on the lenses. Ghosts play a minor role.

Paper Details

Date Published: 22 September 2015
PDF: 14 pages
Proc. SPIE 9602, UV/Optical/IR Space Telescopes and Instruments: Innovative Technologies and Concepts VII, 96020H (22 September 2015); doi: 10.1117/12.2187948
Show Author Affiliations
Norbert Geis, Max-Planck-Institut für extraterrestrische Physik (Germany)
Frank Grupp, Max-Planck-Institut für extraterrestrische Physik (Germany)
Univ.-Sternwarte München (Germany)
Eric Prieto, Aix Marseille Univ., CNRS (France)
Ralf Bender, Max-Planck-Institut für extraterrestrische Physik (Germany)
Univ.-Sternwarte München (Germany)


Published in SPIE Proceedings Vol. 9602:
UV/Optical/IR Space Telescopes and Instruments: Innovative Technologies and Concepts VII
Howard A. MacEwen; James B. Breckinridge, Editor(s)

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