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Proceedings Paper • Open Access

Optical performance of the Metis coronagraph on the Solar Orbiter ESA mission
Author(s): Fabio Frassetto; Vania Da Deppo; Paola Zuppella; Marco Romoli; Silvano Fineschi; Ester Antonucci; Giana Nicolini; Giampiero Naletto; Piergiorgio Nicolosi; Daniele Spadaro; Vincenzo Andretta; Marco Castronuovo; Marta Casti; Gerardo Capobianco; Giuseppe Massone; Roberto Susino; Federico Landini; Maurizio Pancrazzi; Luca Teriaca; Udo Schühle; Klaus Heerlein; Michela Uslenghi

Paper Abstract

The Metis coronagraph aboard the Solar Orbiter ESA spacecraft is expected to provide new insights into the solar dynamics. In detail, it is designed to address three main questions: the energy deposition mechanism at the poles (where the fast wind is originated), the source of the slow wind at lower altitude, and how the global corona evolves, in particular in relation to the huge plasma ejections that occasionally are produced. To obtain the required optical performance, not only the Metis optical design has been highly optimized, but the alignment procedure has also been subjected to an accurate evaluation in order to fulfill the integration specifications. The telescope assembling sequence has been constructed considering all the subsystems manufacturing, alignment and integration tolerances. The performance verification activity is an important milestone in the instrument characterization and the obtained results will assure the fulfillment of the science requirements for its operation in space.

The entire alignment and verification phase has been performed by the Metis team in collaboration with Thales Alenia Space Torino and took place in ALTEC (Turin) at the Optical Payload System Facility using the Space Optics Calibration Chamber infrastructure, a vacuum chamber especially built and tested for the alignment and calibration of the Metis coronagraph, and suitable for tests of future payloads.

The goal of the alignment, integration, verification and calibration processes is to measure the parameters of the telescope, and the characteristics of the two Metis channels: visible and ultraviolet. They work in parallel thanks to the peculiar optical layout. The focusing and alignment performance of the two channels must be well understood, and the results need to be easily compared to the requirements. For this, a dedicated illumination method, with both channels fed by the same source, has been developed; and a procedure to perform a simultaneous through focus analysis has been adopted.

In this paper the final optical performance achieved by Metis is reported and commented.

Paper Details

Date Published: 12 July 2019
PDF: 9 pages
Proc. SPIE 11180, International Conference on Space Optics — ICSO 2018, 111806Y (12 July 2019); doi: 10.1117/12.2536169
Show Author Affiliations
Fabio Frassetto, CNR-Istituto di Fotonica e Nanotecnologie (Italy)
Vania Da Deppo, CNR-Istituto di Fotonica e Nanotecnologie (Italy)
Paola Zuppella, CNR-Istituto di Fotonica e Nanotecnologie (Italy)
Marco Romoli, Univ. degli Studi di Firenze (Italy)
Silvano Fineschi, INAF – Osservatorio Astrofisico di Torino (Italy)
Ester Antonucci, INAF – Osservatorio Astrofisico di Torino (Italy)
Giana Nicolini, INAF – Osservatorio Astrofisico di Torino (Italy)
Giampiero Naletto, Univ. degli Studi di Padova, CNR-IFN Padova, INAF, CISAS (Italy)
Piergiorgio Nicolosi, Univ. degli Studi di Padova (Italy)
Daniele Spadaro, INAF – Osservatorio Astrofisico di Catania (Italy)
Vincenzo Andretta, INAF – Osservatorio Astronomico di Capodimonte (Italy)
Marco Castronuovo, Agenzia Spaziale Italiana (Italy)
Marta Casti, INAF – Osservatorio Astrofisico di Torino (Italy)
Gerardo Capobianco, INAF – Osservatorio Astrofisico di Torino (Italy)
Giuseppe Massone, INAF – Osservatorio Astrofisico di Torino (Italy)
Roberto Susino, INAF – Osservatorio Astrofisico di Torino (Italy)
Federico Landini, INAF – Osservatorio Astrofisico di Arcetri (Italy)
Maurizio Pancrazzi, Univ. degli Studi di Firenze (Italy)
Luca Teriaca, Max-Planck Institute for Solar System Research (Germany)
Udo Schühle, Max-Planck Institute for Solar System Research (Germany)
Klaus Heerlein, Max-Planck Institute for Solar System Research (Germany)
Michela Uslenghi, INAF-IASF (Italy)


Published in SPIE Proceedings Vol. 11180:
International Conference on Space Optics — ICSO 2018
Zoran Sodnik; Nikos Karafolas; Bruno Cugny, Editor(s)

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