Open Access Paper
12 July 2019 Stray light calibration for the Solar Orbiter/Metis solar coronagraph
F. Landini, M. Romoli, S. Fineschi, C. Casini, C. Baccani, E. Antonucci, G. Nicolini, G. Naletto, P. Nicolosi, D. Spadaro, V. Andretta, M. Castronuovo, M. Casti, G. Capobianco, G. Massone, R. Susino, V. Da Deppo, F. Frassetto, M. Pancrazzi, L. Teriaca, U. Schuehle, K. Heerlein, M. Uslenghi
Author Affiliations +
Proceedings Volume 11180, International Conference on Space Optics — ICSO 2018; 111802I (2019) https://doi.org/10.1117/12.2536009
Event: International Conference on Space Optics - ICSO 2018, 2018, Chania, Greece
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) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
F. Landini, M. Romoli, S. Fineschi, C. Casini, C. Baccani, E. Antonucci, G. Nicolini, G. Naletto, P. Nicolosi, D. Spadaro, V. Andretta, M. Castronuovo, M. Casti, G. Capobianco, G. Massone, R. Susino, V. Da Deppo, F. Frassetto, M. Pancrazzi, L. Teriaca, U. Schuehle, K. Heerlein, and M. Uslenghi "Stray light calibration for the Solar Orbiter/Metis solar coronagraph", Proc. SPIE 11180, International Conference on Space Optics — ICSO 2018, 111802I (12 July 2019); https://doi.org/10.1117/12.2536009
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Cited by 2 scholarly publications.
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KEYWORDS
Stray light

Calibration

Coronagraphy

Information operations

Light emitting diodes

Sun

Vignetting

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