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Proceedings Paper

Coating thin mirror segments for lightweight x-ray optics
Author(s): Kai-Wing Chan; Marton Sharpe; William Zhang; Linette Kolos; Melinda Hong; Ryan McClelland; Bruce Hohl; Timo Saha; James Mazzarella
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Paper Abstract

Next generation’s lightweight, high resolution, high throughput optics for x-ray astronomy requires integration of very thin mirror segments into a lightweight telescope housing without distortion. Thin glass substrates with linear dimension of 200 mm and thickness as small as 0.4 mm can now be fabricated to a precision of a few arc-seconds for grazing incidence optics. Subsequent implementation requires a distortion-free deposition of metals such as iridium or platinum. These depositions, however, generally have high coating stresses that cause mirror distortion. In this paper, we discuss the coating stress on these thin glass mirrors and the effort to eliminate their induced distortion. It is shown that balancing the coating distortion either by coating films with tensile and compressive stresses, or on both sides of the mirrors is not sufficient. Heating the mirror in a moderately high temperature turns out to relax the coated films reasonably well to a precision of about a second of arc and therefore provide a practical solution to the coating problem.

Paper Details

Date Published: 26 September 2013
PDF: 12 pages
Proc. SPIE 8861, Optics for EUV, X-Ray, and Gamma-Ray Astronomy VI, 88610X (26 September 2013); doi: 10.1117/12.2022444
Show Author Affiliations
Kai-Wing Chan, Univ. of Maryland, Baltimore County (United States)
NASA Goddard Space Flight Ctr. (United States)
Marton Sharpe, Stinger Ghaffarian Technologies, Inc. (United States)
NASA Goddard Space Flight Ctr. (United States)
William Zhang, NASA Goddard Space Flight Ctr. (United States)
Linette Kolos, NASA Goddard Space Flight Ctr. (United States)
Melinda Hong, Stinger Ghaffarian Technologies, Inc. (United States)
NASA Goddard Space Flight Ctr. (United States)
Ryan McClelland, Stinger Ghaffarian Technologies, Inc. (United States)
NASA Goddard Space Flight Ctr. (United States)
Bruce Hohl, SGT, Inc. (United States)
NASA Goddard Space Flight Ctr. (United States)
Timo Saha, NASA Goddard Space Flight Ctr. (United States)
James Mazzarella, Stinger Ghaffarian Technologies, Inc. (United States)
NASA Goddard Space Flight Ctr. (United States)


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

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