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Proceedings Paper

Restraint deformation and corrosion protection of gold deposited aluminum mirrors for cold optics of mid-infrared instruments
Author(s): Mizuho Uchiyama; Takashi Miyata; Shigeyuki Sako; Takafumi Kamizuka; Tomohiko Nakamura; Kentaro Asano; Kazushi Okada; Takashi Onaka; Itsuki Sakon; Hirokazu Kataza; Yuki Sarugaku; Okiharu Kirino; Hiroyuki Nakagawa; Norio Okada; Kenji Mitsui
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Paper Abstract

We report the restraint deformation and the corrosion protection of gold deposited aluminum mirrors for mid-infrared instruments. To evaluate the deformation of the aluminum mirrors by thermal shrinkage, monitoring measurement of the surface of a mirror has been carried out in the cooling cycles from the room temperature to 100 K. The result showed that the effect of the deformation was reduced to one fourth if the mirror was screwed with spring washers. We have explored an effective way to prevent the mirror from being galvanically corroded. A number of samples have been prepared by changing the coating conditions, such as inserting an insulation layer, making a multi-layer and overcoating water blocking layer, or carrying out precision cleaning before coating. Precision cleaning before the deposition and protecting coat with SiO over the gold layer seemed to be effective in blocking corrosion of the aluminum. The SiO over-coated mirror has survived the cooling test for the mid-infrared use and approximately 1 percent decrease in the reflectance has been detected at 6-25 microns compared to gold deposited mirror without coating.

Paper Details

Date Published: 18 July 2014
PDF: 9 pages
Proc. SPIE 9151, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation, 915143 (18 July 2014); doi: 10.1117/12.2054917
Show Author Affiliations
Mizuho Uchiyama, The Univ. of Tokyo (Japan)
Takashi Miyata, The Univ. of Tokyo (Japan)
Shigeyuki Sako, The Univ. of Tokyo (Japan)
Takafumi Kamizuka, The Univ. of Tokyo (Japan)
Tomohiko Nakamura, The Univ. of Tokyo (Japan)
Kentaro Asano, The Univ. of Tokyo (Japan)
Kazushi Okada, The Univ. of Tokyo (Japan)
Takashi Onaka, The Univ. of Tokyo (Japan)
Itsuki Sakon, The Univ. of Tokyo (Japan)
Hirokazu Kataza, Japan Aerospace Exploration Agency (Japan)
Yuki Sarugaku, Japan Aerospace Exploration Agency (Japan)
Okiharu Kirino, Crystal Optics, Inc. (Japan)
Hiroyuki Nakagawa, Crystal Optics, Inc. (Japan)
Norio Okada, National Astronomical Observatory of Japan (Japan)
Kenji Mitsui, National Astronomical Observatory of Japan (Japan)


Published in SPIE Proceedings Vol. 9151:
Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation
Ramón Navarro; Colin R. Cunningham; Allison A. Barto, Editor(s)

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