The Euclid space mission aims at elucidating dark matter and dark energy mysteries thanks to two scientific instruments: VIS, the visible camera and NISP, the Near Infrared Spectro-Photometer. Millions of galaxies spectra will be recorded thanks to its spectroscopic mode using four grisms developed under LAM (Laboratoire d’Astrophysique de Marseille) responsibility. These dispersive optical components are made of a grating on a prism and include also, specifically for NISP, three other optical functions: spectral filtering, focus adjustment and spectral wavefront correction. Therefore, these optical elements are very challenging to manufacture (four industrial partners work on a single optical component) and to test before integration into NISP. In this paper, first we describe the optical specifications and the manufacturing process. Second, we explain the optical validation tests campaign: optical setups, measurements and data processing procedures used to validate these complex optical components, particularly for transmitted efficiency and wavefront error for which specifications are very stringent. Finally, we present the first results obtained on the grism EQM which manufacturing is on-going and almost finished.

Date Published: 29 July 2016
PDF: 13 pages
Proc. SPIE 9904, Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave, 99040R (29 July 2016); doi: 10.1117/12.2231425

Published in SPIE Proceedings Vol. 9904:
Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave
Howard A. MacEwen; Giovanni G. Fazio; Makenzie Lystrup; Natalie Batalha; Nicholas Siegler; Edward C. Tong, Editor(s)