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Telescope system of the infrared imaging surveyor (IRIS)

Takashi Onaka(a), Yoshikazu Sugiyama(b), and Shinji Miura(c)

(a) Department of Astronomy, School of Science,
University of Tokyo, Tokyo 113-0033, Japan

(b) Optical Designing Headquarters, Nikon Corporation,
Ohi Plant, Tokyo 140-8601, Japan

(c) Designing Department, Customized Industrial Supplies & Equipment Division,
Nikon Corporation, Mito Plant, Mito, Ibaragi 310-0843, Japan

Abstract:

The telescope system of a Japanese Infrared Astronomical Space Mission, ``Infrared Imaging Surveyor (IRIS)'', is described. The IRIS is a cryogenically-cooled telescope, being planned to be launched in 2003. It will make astronomical observations from near-infrared to far-infrared ( m) regions. The IRIS telescope system is a Ritchey-Chretien type, whose primary mirror size is 700mm in diameter and whose system F ratio is 6. In order to share the focal plane with two scientific instruments and a focal-plane star sensor, it has a clear field of view of 38 arcminutes in radius. It is being designed to achieve the diffraction-limited performance at 5 m for temperatures below 10K. The IRIS telescope will use light-weight silicon carbide (SiC) mirrors. The current estimate of the primary mirror weight is 9 kg and the goal of total weight of the telescope system is less than 27 kg. Preliminary tests of small size SiC mirrors at 4.2K suggest that slight distortion of the surface figure detected at low temperatures can be reduced by improved CVD processes. The telescope system is designed to meet the launch conditions of the M-V rocket and to have the fundamental frequencies above 100 Hz.

Infrared Space Telescope, Cryogenic Telescope, SiC Lightweight Mirror

 
• 1 INTRODUCTION
• 2 Telescope Design
• 3 Silicon Carbide Mirror
• References

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Last modified: February 17, 1999