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Proceedings Paper

Gemini primary mirror in situ wash
Author(s): Tomislav Vucina; Maxime Boccas; Claudio Araya; Clayton Ah Hee; Chas Cavedoni
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Paper Abstract

The Gemini twins were the first large modern telescopes to receive protected silver coatings on their mirrors in 2004. The low emissivity requirement is fundamental for the IR optimization. In the mid-IR a factor of two reduction in telescope emissivity is equivalent to increasing the collecting area by the same factor. Our emissivity maintenance requirement is very stringent: 0.5% maximum degradation during operations, at any single wavelength beyond 2.2 μm. We developed a very rigorous standard to wash the primary mirrors in the telescope without science down time. The in-situ washes are made regularly, and the reflectivity and emissivity gains are significant. The coating lifetime has been extended far more than our original expectations. In this report we describe the in-situ process and hardware, explain our maintenance plan, and show results of the coating performance over time.

Paper Details

Date Published: 10 July 2008
PDF: 13 pages
Proc. SPIE 7012, Ground-based and Airborne Telescopes II, 70122Q (10 July 2008); doi: 10.1117/12.788388
Show Author Affiliations
Tomislav Vucina, Gemini Observatory (Chile)
Maxime Boccas, Gemini Observatory (Chile)
Claudio Araya, Gemini Observatory (Chile)
Clayton Ah Hee, Gemini Observatory (United States)
Chas Cavedoni, Gemini Observatory (United States)

Published in SPIE Proceedings Vol. 7012:
Ground-based and Airborne Telescopes II
Larry M. Stepp; Roberto Gilmozzi, Editor(s)

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