The Solar Orbiter/Metis visible and UV solar coronagraph redefines the concept of external occultation in solar coronagraphy. Classical externally occulted coronagraphs are characterized by an occulter in front of the telescope entrance aperture. Solar Orbiter will approach the Sun down to 0.28 AU: in order to reduce the thermal load, the Metis design switches the positions of the entrance aperture and the external occulter thus achieving what is called the inverted external occultation. The inverted external occulter (IEO) consists of a circular aperture on the Solar Orbiter thermal shield that acts as coronagraph entrance pupil. A spherical mirror, located 800 mm behind the IEO, back rejects the disklight through the IEO itself. To pursue the goal of maximizing the reduction of the stray light level on the focal plane, an optimization of the IEO shape was implemented. The stray light calibration was performed in a clean environment in front of the OPSys solar disk divergence simulator (at ALTEC, in Torino, Italy), which is able to emulate different heliocentric distances. Ground calibrations were a unique opportunity to map the Metis stray light level thanks to a pure solar disk simulator without the solar corona. The stray light calibration was limited to the visible light case, being the most stringent. This work is focused on the description of the laboratory facility that was used to perform the stray light calibration and on the calibration results.

Stray light calibration for the Solar Orbiter/Metis solar coronagraph / Landini, F. and Romoli, M. and Fineschi, S. and Casini, C. and Baccani, C. and Antonucci, E. and Nicolini, G. and Naletto, G. and Nicolosi, P. and Spadaro, D. and Andretta, V. and Castronuovo, M. and Casti, M. and Capobianco, G. and Massone, G. and Susino, R. and Da Deppo, V. and Frassetto, F. and Pancrazzi, M. and Teriaca, L. and Schuehle, U. and Heerlein, K. and Uslenghi, M.. - ELETTRONICO. - 11180:(2019), pp. 0-15. (Intervento presentato al convegno International Conference on Space Optics - ICSO 2018, 2018, Chania, Greece) [10.1117/12.2536009].

Stray light calibration for the Solar Orbiter/Metis solar coronagraph

Romoli, M.;CASINI, CHIARA;Baccani, C.;Antonucci, E.;Nicolini, G.;Spadaro, D.;Capobianco, G.;Pancrazzi, M.;
2019

Abstract

The Solar Orbiter/Metis visible and UV solar coronagraph redefines the concept of external occultation in solar coronagraphy. Classical externally occulted coronagraphs are characterized by an occulter in front of the telescope entrance aperture. Solar Orbiter will approach the Sun down to 0.28 AU: in order to reduce the thermal load, the Metis design switches the positions of the entrance aperture and the external occulter thus achieving what is called the inverted external occultation. The inverted external occulter (IEO) consists of a circular aperture on the Solar Orbiter thermal shield that acts as coronagraph entrance pupil. A spherical mirror, located 800 mm behind the IEO, back rejects the disklight through the IEO itself. To pursue the goal of maximizing the reduction of the stray light level on the focal plane, an optimization of the IEO shape was implemented. The stray light calibration was performed in a clean environment in front of the OPSys solar disk divergence simulator (at ALTEC, in Torino, Italy), which is able to emulate different heliocentric distances. Ground calibrations were a unique opportunity to map the Metis stray light level thanks to a pure solar disk simulator without the solar corona. The stray light calibration was limited to the visible light case, being the most stringent. This work is focused on the description of the laboratory facility that was used to perform the stray light calibration and on the calibration results.
2019
procspie
International Conference on Space Optics - ICSO 2018, 2018, Chania, Greece
Landini, F. and Romoli, M. and Fineschi, S. and Casini, C. and Baccani, C. and Antonucci, E. and Nicolini, G. and Naletto, G. and Nicolosi, P. and Spadaro, D. and Andretta, V. and Castronuovo, M. and Casti, M. and Capobianco, G. and Massone, G. and Susino, R. and Da Deppo, V. and Frassetto, F. and Pancrazzi, M. and Teriaca, L. and Schuehle, U. and Heerlein, K. and Uslenghi, M.
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/1174851
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