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Proceedings Paper

Adaptive optics system for Cassegrain focus of Subaru 8.2-m telescope
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Paper Abstract

The adaptive optics system for Subaru 8.2m telescope of the National Astronomical Observatory Japan has been developed for the Cassegrain ear-IR instruments, CIAO and IRCS. The system consists of a wavefront curvature sensor with 36 subaperture photon-counting avalanche photodiode modules and a bimorph deformable mirror with 36 electrodes. The expected Strehl ratio at K band exceeds 0.4 for objects that are located close enough to a bright guide star as faint as R equals 16 mag at the median seeing of 0.45 arcsec at Mauna Kea. The system will be in operation in 1999 as a natural guide star system, and will eventually be upgraded to a laser guide star system in cooperating an IR wavefront tilt sensor to provide nearly full sky. The construction of this common use system to Subaru telescope is now underway in our laboratory in Tokyo. Prior to starting the fabrication of this common use system, a full size prototype system was constructed and tested with the 1.6 m IR telescope at our observatory in Tokyo. This system has the identical optical design, deformable mirror, loop control computer to those for the Subaru system, while the wavefront sensing detectors were less-sensitive analog APDs. We succeeded in getting closed loop images of stars in K band with diffraction limited core. The Strehl ratio was around 0.5 and the factor of improvement was about 20 at K-band under the average seeing of 2 arcsec during the observation. The loop sped of the system was 2 K corrections per second.

Paper Details

Date Published: 11 September 1998
PDF: 8 pages
Proc. SPIE 3353, Adaptive Optical System Technologies, (11 September 1998); doi: 10.1117/12.321685
Show Author Affiliations
Hideki Takami, National Astronomical Observatory of Japan (United States)
Naruhisa Takato, National Astronomical Observatory of Japan (United States)
Masashi Otsubo, National Astronomical Observatory of Japan (Japan)
Tomio Kanzawa, National Astronomical Observatory of Japan (United States)
Yukiko Kamata, National Astronomical Observatory of Japan (Japan)
Koji Nakashima, National Astronomical Observatory of Japan (Japan)
Masanori Iye, National Astronomical Observatory of Japan (Japan)

Published in SPIE Proceedings Vol. 3353:
Adaptive Optical System Technologies
Domenico Bonaccini; Robert K. Tyson, Editor(s)

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