Stray-light analyses of the METIS coronagraph on Solar Orbiter

Date Issued
2015
Author(s)
•
Sandri, Paolo
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DaDeppo, Vania
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Verroi, Enrico
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•
Morea, Danilo
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•
•
DOI
Abstract
The METIS coronagraph on board the Solar Orbiter mission will have the unique opportunity of observing the solar outer atmosphere as close to the Sun as 0.28 A.U., and from up to 35° out-of-ecliptic. The telescope design of the METIS coronagraph includes two optical paths: i) broad-band imaging of the full corona in linearly polarized visible-light (VL: 580-640 nm), ii) narrow-band imaging of the full corona in the ultraviolet (UV) Lyman α (121.6 nm). This paper describes the stray-light analyses performed on the UV and VL channels of the METIS Telescope with the nonsequential modality of Zemax OpticStudio. A detailed opto-mechanical model of the METIS Telescope is simulated by placing the CAD parts of all the sub-assemblies at the nominal position. Each surface, mechanical and optical, is provided with a modelled coating and BSDF reproducing the optical and the diffusing properties. The geometric model allows for the verification of the correct functioning of the blocking elements inside the telescope and for an evaluation of the stray-light level due to surface roughness. The diffraction off the inner edge of the IEO on the plane of the IO is modelled separately from the contributor of the surface micro-roughness. The contributors due to particle contamination and cosmetic defects are also analysed. The results obtained are merged together and compared to the requirements of stray-light. The results of this analysis together with those from two different analyses based on a Montecarlo ray-trace and a semi-analytical model are consistent with each other and indicate that the METIS design meets the stray-light level requirements
Coverage
Solar Physics and Space Weather Instrumentation VI
All editors
Fineschi, Silvano; Fennelly, Judy
Series
Volume
9604
Start page
96040K-1
Conferenece
Solar Physics and Space Weather Instrumentation VI
Conferenece place
San Diego, CA, USA
Conferenece date
9-13 August, 2015
Uri
Url
Issn Identifier
0277-786X
Ads BibCode
2015SPIE.9604E..0KF
Rights
open.access
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2015_SPIE-Fineschi_stray-light Metis.pdf

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