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Proceedings Paper

Low-stress silicon cladding made by pulsed-ion-assisted evaporation
Author(s): David A. Sheikh
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Paper Abstract

A low-stress, polishable, silicon (Si) cladding process for lightweight mirrors is presented. The cladding process is based on the thermal evaporation of silicon in the presence of low-energy argon ions. The process utilizes an ion bombardment technique whereby the coating stress of a silicon film is manipulated periodically from compressive to tensile in order to achieve a low net stress for the complete layer. A Si cladding with little intrinsic stress is desirable to minimize bending that would otherwise distort the figure of very lightweight mirrors. The process has yielded silicon claddings up to 100-microns thick, with less than 85 MPa of compressive stress. This polishable Si cladding was specifically designed for silicon carbide mirror substrates, however, it is also suitable for graphite composite, beryllium, and aluminum mirror substrates, which may be difficult or impossible to polish to sufficient mirror quality without a specialized coating.

Paper Details

Date Published: 2 September 2015
PDF: 7 pages
Proc. SPIE 9574, Material Technologies and Applications to Optics, Structures, Components, and Sub-Systems II, 95740C (2 September 2015); doi: 10.1117/12.2191445
Show Author Affiliations
David A. Sheikh, ZeCoat Corp. (United States)


Published in SPIE Proceedings Vol. 9574:
Material Technologies and Applications to Optics, Structures, Components, and Sub-Systems II
Matthias Krödel; Joseph L. Robichaud; William A. Goodman, Editor(s)

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