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Simulation and modeling of silicon pore optics for the ATHENA x-ray telescope
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Paper 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 more than 1000 mirror modules, obtained by stacking wedged and ribbed silicon wafer plates onto silicon mandrels to form the Wolter-I configuration. Even if the current baseline design fulfills the required effective area of 2 m2 at 1 keV on-axis, alternative design solutions, e.g., privileging the field of view or the off-axis angular resolution, are also possible. Moreover, the stringent requirement of a 5 arcsec HEW angular resolution at 1 keV entails very small profile errors and excellent surface smoothness, as well as a precise alignment of the 1000 mirror modules to avoid imaging degradation and effective area loss. Finally, the stray light issue has to be kept under control. In this paper we show the preliminary results of simulations of optical systems based on SPO for the ATHENA X-ray telescope, from pore to telescope level, carried out at INAF/OAB and DTU Space under ESA contract. We show ray-tracing results, including assessment of the misalignments of mirror modules and the impact of stray light. We also deal with a detailed description of diffractive effects expected in an SPO module from UV light, where the aperture diffraction prevails, to X-rays where the surface diffraction plays a major role. Finally, we analyze the results of X-ray tests performed at the BESSY synchrotron, we compare them with surface finishing measurements, and we estimate the expected HEW degradation caused by the X-ray scattering.

Paper Details

Date Published: 27 July 2016
PDF: 24 pages
Proc. SPIE 9905, Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray, 99055O (27 July 2016); doi: 10.1117/12.2232230
Show Author Affiliations
D. Spiga, INAF - Brera Astronomical Observatory (Italy)
F. E. Christensen, DTU Space, Technical Univ. Denmark (Denmark)
M. Bavdaz, European Space Agency, ESTEC (Netherlands)
M. M. Civitani, INAF - Brera Astronomical Observatory (Italy)
P. Conconi, INAF - Brera Astronomical Observatory (Italy)
D. Della Monica Ferreira, DTU Space, Technical Univ. Denmark (Denmark)
E. B. Knudsen, DTU Fysik, Technical Univ. Denmark (Denmark)
S. Massahi, DTU Space, Technical Univ. Denmark (Denmark)
G. Pareschi, INAF - Brera Astronomical Observatory (Italy)
B. Salmaso, INAF - Brera Astronomical Observatory (Italy)
B. Shortt, European Space Agency, ESTEC (Netherlands)
K. Tayabaly, INAF - Brera Astronomical Observatory (Italy)
Politecnico di Milano (Italy)
N. J. Westergaard, DTU Space, Technical Univ. Denmark (Denmark)
E. Wille, European Space Agency, ESTEC (Netherlands)

Published in SPIE Proceedings Vol. 9905:
Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray
Jan-Willem A. den Herder; Tadayuki Takahashi; Marshall Bautz, Editor(s)

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