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Proceedings Paper

Functional tests of modular elements of segmented optics for x-ray telescopes via an expanded beam facility
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Paper Abstract

Future large X-ray observatories will be equipped with very large optics obtained by assembling modular optical elements. The final quality of the modular optic is determined by the accuracy in the assembly alignment, but also by the compliance of the focusing elements to the nominal shape and the roughness tolerance in order to avoid excessive levels of X-ray scattering. Because of the large number of modules, quality tests need to be routinely performed to assess the technology readiness, and, in a later phase, to select the most performing stacked blocks to be integrated into the final optic. Besides the usual metrology based on profile and roughness measurements, a direct, at-wavelength, focusing measurement in X-rays would be the most reliable test. Synchrotron light beams are in general not sufficiently broad to cover the aperture of a block without scanning it, which requires a focal spot reconstruction. To this end, we designed a 12 m long X-ray facility to be realized at INAF/ OAB, devoted to the functional tests of the focusing elements. A grazing incidence parabolic mirror and an asymmetric Silicon crystal will produce a wide, parallel, and uniform beam of X-rays to illuminate the entire aperture of the focusing elements. A X-ray camera at the focal distance from the mirrors directly records the image. The tests will be performed at 4.5 keV, with the components operating in gaseous Helium to minimize the absorption.

Paper Details

Date Published: 17 September 2012
PDF: 6 pages
Proc. SPIE 8443, Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray, 84435F (17 September 2012); doi: 10.1117/12.927280
Show Author Affiliations
Daniele Spiga, INAF, Osservatorio Astronomico di Brera (Italy)
Giovanni Pareschi, INAF, Osservatorio Astronomico di Brera (Italy)
Carlo Pelliciari, International Research School of Planetary Sciences, Univ. degli Studi D'Annunzio (Italy)
Bianca Salmaso, INAF, Osservatorio Astronomico di Brera (Italy)
Gianpiero Tagliaferri, INAF, Osservatorio Astronomico di Brera (Italy)

Published in SPIE Proceedings Vol. 8443:
Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray
Tadayuki Takahashi; Stephen S. Murray; Jan-Willem A. den Herder, Editor(s)

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