The Hot Slumping Technology is under development by several research groups in the world for the realization of X-ray segmented mirrors, based on thin glass plates: during the process of slumping, a glass foil is shaped over a mould at temperatures above its transformation point. The performed thermal cycle and related operations might have effects on the strength characteristics of the glass, with consequences on the structural design of the elemental optical module and consecutively on the whole X-ray telescope. No reference technical literature exists for this particular aspect since the strength of glass depends on several parameters connected to any of the manufacturing and glass history stages, such as the distribution of surface flaws or the residual internal stresses. It is therefore extremely important to test the mechanical strength of the glass plates after they underwent the slumping process. The Astronomical Observatory of Brera (INAFOAB, Merate - Italy) started a deep analysis of this aspect, with the collaboration of Stazione Sperimentale del Vetro (SSV, Murano - Italy) and BCV Progetti (Milano - Italy). The entire study has been realized on borosilicate glass D263 by Schott, largely considered for the realization of next-generation IXO-like X-ray telescope. More than 200 slumped plates of dimension 100 mm x 100 mm and thickness 0.4 mm, both flat and curved, have been produced and tested; the collected experimental data have been compared to non-linear FEM analyses and treated with Weibull statistics, giving the strength data necessary to assess the current IXO glass X-ray telescope design, in terms of survival probability, when subject to static and acoustic load characteristic of the launch phase. The paper describes the activities performed and presents the obtained results.

Date Published: 26 September 2013
PDF: 11 pages
Proc. SPIE 8861, Optics for EUV, X-Ray, and Gamma-Ray Astronomy VI, 88610S (26 September 2013); doi: 10.1117/12.2024490

Published in SPIE Proceedings Vol. 8861:
Optics for EUV, X-Ray, and Gamma-Ray Astronomy VI
Stephen L. O'Dell; Giovanni Pareschi, Editor(s)