Share Email Print

Proceedings Paper

Euclid warm testing of the near-infrared optical assembly using a unique combination of CGH interferometry and tactile precision measurements
Author(s): Frank Grupp; Jennifer Kaminski; Christof Bodendorf; Norbert Geis; Daniela Penka; Ralf Bender
Format Member Price Non-Member Price
PDF $17.00 $21.00

Paper Abstract

The ESA Cosmic Vision “Euclid" mission will conduct a 6-years long survey of 15,000 square degrees of the sky to a look-back time of 10 billion years, with the aim of characterizing the matter-energy content of the Universe and to better understand the dark energy responsible for the acceleration of its expansion. The Euclid payload consists of a wide field 1.2m aperture telescope equipped with two instruments that simultaneously observe patches of < 0.5 square degree on the sky: the visible light camera (VIS, and the near-infrared spectrometer and photometer (NISP). These two instruments are separated by a dichroic plate splitting the beams around a wavelength of 920 nm. The NISP large field of view (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 tight and challenging specifications on the alignment and positioning of the NISP optical assembly (NI-OA). This required an extensive tolerance analysis at system level during the design phase. The hardware is now completed and went through all optical tests at assembly level. In this paper we present the strategy and results of the warm optical test. In this test, we measured the length of the optical axis behind the NI-OA - or back focal distance (BFD) - using a novel combination of computer generated hologram (CGH) and a coordinate measuring machine (CMM). The agreement between the predicted and measured BFD values is excellent, within 1 μm. In addition, we measured the system wave-front error under warm conditions in double path and found diffraction limited performance on- and off-axis all over the field of view. These warm tests validated the anticipated performance of the NI-OA and allowed us to prepare the time-consuming and risky cryogenic tests with a high level of confidence.

Paper Details

Date Published: 16 September 2019
PDF: 12 pages
Proc. SPIE 11116, Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems II, 1111618 (16 September 2019); doi: 10.1117/12.2527723
Show Author Affiliations
Frank Grupp, Max-Planck-Institut für extraterrestrische Physik (Germany)
Univ.-Sternwarte München (Germany)
Jennifer Kaminski, Max-Planck-Institut für extraterrestrische Physik (Germany)
Christof Bodendorf, Max-Planck-Institut für extraterrestrische Physik (Germany)
Norbert Geis, Max-Planck-Institut für extraterrestrische Physik (Germany)
Daniela Penka, Max-Planck-Institut für extraterrestrische Physik (Germany)
Ralf Bender, Max-Planck-Institut für extraterrestrische Physik (Germany)
Univ.-Sternwarte München (Germany)

Published in SPIE Proceedings Vol. 11116:
Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems II
Tony B. Hull; Dae Wook Kim; Pascal Hallibert, Editor(s)

© SPIE. Terms of Use
Back to Top
Sign in to read the full article
Create a free SPIE account to get access to
premium articles and original research
Forgot your username?