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Proceedings Paper

Test production of a mirror segment for the Thirty Meter Telescope
Author(s): Tetsuji Oota; Hirohiko Shinonaga; Kotaro Akutsu; Yuichiro Hashimoto; Itaru Otsuka; Yasushi Iwasaki; Masanori Iye; Takuya Yamashita; Hiroshi Akitaya; Ryuji Suzuki
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Paper Abstract

The Thirty Meter Telescope (TMT) is a next-generation optical/infrared telescope to be constructed on Mauna Kea, Hawaii toward the end of this decade, as an international project. Its 30 m primary mirror consists of 492 off-axis aspheric segmented mirrors. This paper describes the progress of the test fabrication of an outermost mirror segment for the TMT as a joint R&D program between National Astronomical Observatory and Canon. A zero-expansion glass CLEARCERAM™ blank was polished by a computer-controlled small-tool polishing machine (CSSP, Canon) and its surface shape was measured by a touch-probe measuring machine(A-Ruler, Canon). Residuals of lower Zernike terms of the surface shape were 11 nmRMS, clearing the original specifications based on the structure function. There remains, however, a need to fulfill latest revised specifications. Possible solutions to improve and achieve the new specifications and a plan for revising the process for mass production are also described.

Paper Details

Date Published: 13 September 2012
PDF: 8 pages
Proc. SPIE 8450, Modern Technologies in Space- and Ground-based Telescopes and Instrumentation II, 84502B (13 September 2012); doi: 10.1117/12.926945
Show Author Affiliations
Tetsuji Oota, Canon Inc. (Japan)
Hirohiko Shinonaga, Canon Inc. (Japan)
Kotaro Akutsu, Canon Inc. (Japan)
Yuichiro Hashimoto, Canon Inc. (Japan)
Itaru Otsuka, Canon Inc. (Japan)
Yasushi Iwasaki, Canon Inc. (Japan)
Masanori Iye, National Astronomical Observatory of Japan (Japan)
Takuya Yamashita, National Astronomical Observatory of Japan (Japan)
Hiroshi Akitaya, Hiroshima Univ. (Japan)
Ryuji Suzuki, National Astronomical Observatory of Japan (Japan)

Published in SPIE Proceedings Vol. 8450:
Modern Technologies in Space- and Ground-based Telescopes and Instrumentation II
Ramón Navarro; Colin R. Cunningham; Eric Prieto, Editor(s)

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