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Proceedings Paper • Open Access

The optimization of the inverted occulter of the solar orbiter/METIS coronagraph/spectrometer
Author(s): F. Landini; S. Vives; M. Romoli; C. Guillon; M. Pancrazzi; C. Escolle; M. Focardi; S. Fineschi; E. Antonucci; G. Nicolini; G. Naletto; P. Nicolosi; D. Spadaro

Paper Abstract

The coronagraph/spectrometer METIS (Multi Element Telescope for Imaging and Spectroscopy), selected to fly aboard the Solar Orbiter ESA/NASA mission, is conceived to perform imaging (in visible, UV and EUV) and spectroscopy (in EUV) of the solar corona. It is an integrated instrument suite located on a single optical bench and sharing a unique aperture on the satellite heat shield. As every coronagraph, METIS is highly demanding in terms of stray light suppression. In order to meet the strict thermal requirements of Solar Orbiter, METIS optical design has been optimized by moving the entrance pupil at the level of the external occulter on the S/C thermal shield, thus reducing the size of the external aperture. The scheme is based on an inverted external-occulter (IEO). The IEO consists of a circular aperture on the Solar Orbiter thermal shield. A spherical mirror rejects back the disk-light through the IEO. The experience built on all the previous space coronagraphs forces designers to dedicate a particular attention to the occulter optimization. Two breadboards were manufactured to perform occulter optimization measurements: BOA (Breadboard of the Occulting Assembly) and ANACONDA (AN Alternative COnfiguration for the Occulting Native Design Assembly). A preliminary measurement campaign has been carried on at the Laboratoire d’Astrophysique de Marseille. In this paper we describe BOA and ANACONDA designs, the laboratory set-up and the preliminary results.

Paper Details

Date Published: 20 November 2017
PDF: 10 pages
Proc. SPIE 10564, International Conference on Space Optics — ICSO 2012, 105640F (20 November 2017); doi: 10.1117/12.2309079
Show Author Affiliations
F. Landini, Univ. of Firenze (Italy)
S. Vives, Aix Marseille Univ. (France)
M. Romoli, Univ. of Firenze (Italy)
C. Guillon, Aix Marseille Univ. (France)
M. Pancrazzi, Univ. of Firenze (Italy)
Aix Marseille Univ. (France)
C. Escolle, Aix Marseille Univ. (France)
M. Focardi, Univ. of Firenze (Italy)
S. Fineschi, INAF - Osservatorio Astrofisico di Torino (Italy)
E. Antonucci, INAF - Osservatorio Astronomico di Torino (Italy)
G. Nicolini, INAF - Osservatorio Astrofisico di Torino (Italy)
G. Naletto, Univ. of Padova (Italy)
P. Nicolosi, Univ. of Padova (Italy)
D. Spadaro, INAF - Osservatorio Astrofisico di Catania (Italy)

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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