Optical simulations for design, alignment, and performance prediction of silicon pore optics for the ATHENA x-ray telescope
Date Issued
2017
Author(s)
•
Della Monica Ferreira, D.
•
Shortt, B.
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Bavdaz, M.
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Bergback Knudsen, E.
•
Bianucci, G.
•
Christensen, F.
•
•
Collon, M.
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Conconi, P.
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Fransen, S.
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Marioni, F.
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Massahi, S.
•
•
•
Jegers, A. S.
•
Tayabaly, K.
•
Valsecchi, G.
•
Westergaard, N.
•
Wille, E.
Description
ESA contracts No.: 4000114410 SIMPOSiuM, 4000114931 ASPHEA, 4000111244 SPIRIT
Abstract
The ATHENA X-ray observatory is a large-class ESA approved mission, with launch scheduled in 2028. The technology of silicon pore optics (SPO) was selected as baseline to assemble ATHENA's optic with hundreds of mirror modules, obtained by stacking wedged and ribbed silicon wafer plates onto silicon mandrels to form the Wolter-I configuration. In the current configuration, the optical assembly has a 3 m diameter and a 2 m2 effective area at 1 keV, with a required angular resolution of 5 arcsec. The angular resolution that can be achieved is chiefly the combination of 1) the focal spot size determined by the pore diffraction, 2) the focus degradation caused by surface and profile errors, 3) the aberrations introduced by the misalignments between primary and secondary segments, 4) imperfections in the co-focality of the mirror modules in the optical assembly. A detailed simulation of these aspects is required in order to assess the fabrication and alignment tolerances; moreover, the achievable effective area and angular resolution depend on the mirror module design. Therefore, guaranteeing these optical performances requires: a fast design tool to find the most performing solution in terms of mirror module geometry and population, and an accurate point spread function simulation from local metrology and positioning information. In this paper, we present the results of simulations in the framework of ESA-financed projects (SIMPOSiuM, ASPHEA, SPIRIT), in preparation of the ATHENA X-ray telescope, analyzing the mentioned points: 1) we deal with a detailed description of diffractive effects in an SPO mirror module, 2) we show ray-tracing results including surface and profile defects of the reflective surfaces, 3) we assess the effective area and angular resolution degradation caused by alignment errors between SPO mirror module's segments, and 4) we simulate the effects of co-focality errors in X-rays and in the UV optical bench used to study the mirror module alignment and integration.
Coverage
Optics for EUV, X-Ray, and Gamma-Ray Astronomy VIII
All editors
O'Dell, Stephen L.; Pareschi, Giovanni
Series
Volume
10399
Start page
103990H
Conferenece
Optics for EUV, X-Ray, and Gamma-Ray Astronomy VIII
Conferenece place
San Diego, California
Conferenece date
6-10 agosto, 2017
Issn Identifier
0277-786X
Ads BibCode
2017SPIE10399E..0HS
Rights
open.access
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