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Proceedings Paper

Reflective optical system made entirely of ultra low thermal expansion ceramics: a possibility of genuine athermal cryogenic IR instrument
Author(s): Yuki Sarugaku; Yuji Ikeda; Naoto Kobayashi; Takeo Manome; Kentaro Yanagibashi; Naoto Iida; Masahiko Horiuchi; Shinji Mukai; Kenji Oka; Sayumi Kaji; Sohei Kondo; Chikako Yasui; Hideyo Kawakita
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Paper Abstract

Reflective optical system free from chromatic aberration is essential for astronomical instruments, which usually require wider wavelength coverage. However, it cannot always be the optimum choice compared with refractive optical system in terms of cost-effectiveness because mirrors require high surface accuracy and also because non-co-axial systems force tough alignment work. This dilemma could be overcome by a monolithic reflective optical system made entirely of cordierite CO-720, a ceramic material by Kyocera, which is the first material that offers both high-precision 3D-shaping and surface polishing for optical quality. This material also possesses a very low coefficient of thermal expansion (CTE) enabling a genuine athermal system useful for various astronomical applications. This athermality could make a significant breakthrough especially for cryogenic infrared instruments since optical systems made of cordierite are expected to keep as-built performance throughout the cooling process, providing extremely high wavefront accuracy that has never been possible at cryogenic temperature with conventional optical systems made of glasses or metals. In this paper, we report the first cryogenic optical testing of a small cordierite-made imaging optical system that was simply assembled with mechanical accuracy at room temperature. We confirmed that the diffraction-limited optical performance is kept even down to ~80K as built in the room temperature.

Paper Details

Date Published: 10 July 2018
PDF: 6 pages
Proc. SPIE 10706, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation III, 107063P (10 July 2018); doi: 10.1117/12.2314040
Show Author Affiliations
Yuki Sarugaku, Kyoto Sangyo Univ. (Japan)
Yuji Ikeda, Kyoto Sangyo Univ. (Japan)
Photocoding (Japan)
Naoto Kobayashi, Kyoto Sangyo Univ. (Japan)
The Univ. of Tokyo (Japan)
Takeo Manome, KYOCERA Corp. (Japan)
Kentaro Yanagibashi, KYOCERA Corp. (Japan)
Naoto Iida, KYOCERA Corp. (Japan)
Masahiko Horiuchi, KYOCERA Corp. (Japan)
Shinji Mukai, KYOCERA Corp. (Japan)
Kenji Oka, Kyoto Sangyo Univ. (Japan)
Sayumi Kaji, Kyoto Sangyo Univ. (Japan)
Sohei Kondo, Kyoto Sangyo Univ. (Japan)
Chikako Yasui, National Astronomical Observatory of Japan (Japan)
Hideyo Kawakita, Kyoto Sangyo Univ. (Japan)

Published in SPIE Proceedings Vol. 10706:
Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation III
Ramón Navarro; Roland Geyl, Editor(s)

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