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Proceedings Paper

Mirror coating 2003 in Subaru Telescope
Author(s): Tomio Kurakami; Masami Yutani; Tomio Kanzawa; Norio Ohshima; Saeko S. Hayashi; Tomonori Usuda; Shin-ichi Kubota
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Paper Abstract

The SUBARU Telescope has four focal positions to allow different types of astronomical instrument. At present, there are four different Top Units; three types of secondary mirrors and one primary focus unit. IR secondary mirror which is one of the three units, has silver coated surface. Other secondary mirrors are coated by aluminum for observations at visible wavelength. The silver coating for IR secondary mirror was first carried out in 1999 at the medium size (1.6 m) vacuum evaporation chamber in Mitaka campus of NAOJ at Tokyo JAPAN. Since then the reflectivity had deteriorated over the years. Then, we made a plan to recoat IR secondary mirror in 2003 using the SUBARU’s large-size vacuum evaporation chamber at the summit facility on Mauna Kea, Hawaii. Some tests were performed for silver vacuum evaporation at the base facility, and then the IR secondary mirror was recoated at the summit. The reflectivity achieves 97.6% and 99.3% at the wavelength of 500 nm and 2000 nm, respectively. Degradation of the coat has not been seen 8 months after recoating. We also performed the recoating of the aluminum surface of the primary mirror in 2003. This year we made effort to simplify the procedure. The reflectivity is 91.2% and 97.4% at the wavelength of 500 nm and 2000 nm, respectively.

Paper Details

Date Published: 24 September 2004
PDF: 12 pages
Proc. SPIE 5494, Optical Fabrication, Metrology, and Material Advancements for Telescopes, (24 September 2004); doi: 10.1117/12.552291
Show Author Affiliations
Tomio Kurakami, Subaru Telescope/National Astronomical Observatory of Japan (United States)
Masami Yutani, National Astronomical Observatory of Japan (Japan)
Tomio Kanzawa, Subaru Telescope/National Astronomical Observatory of Japan (United States)
Norio Ohshima, National Astronomical Observatory of Japan (Japan)
Saeko S. Hayashi, National Astronomical Observatory of Japan (United States)
Tomonori Usuda, Subaru Telescope/National Astronomical Observatory of Japan (United States)
Shin-ichi Kubota, Mitsubishi Electric Co. (Japan)


Published in SPIE Proceedings Vol. 5494:
Optical Fabrication, Metrology, and Material Advancements for Telescopes
Eli Atad-Ettedgui; Philippe Dierickx, Editor(s)

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