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Proceedings Paper

Development of an MIR coronagraph for the SPICA mission
Author(s): Keigo Enya; Shinichiro Tanaka; Takao Nakagawa; Hirokazu Kataza; Lyu Abe; Motohide Tamura; Jun Nishikawa; Naoshi Murakami; Kenta Fujita; Yoich Itoh
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Paper Abstract

We present the status of the development of a coronagraph for the Space Infrared telescope for Cosmology and Astrophysics (SPICA). SPICA is the next generation infrared space-borne telescope missions led by Japan. The SPICA satellite will be equipped with a telescope that has a 3.5 m diameter monolithic primary mirror and the whole telescope will be cooled to 4.5 K. The satellite is planed be launched early in the 2010s into the sun-earth L2 libration halo orbit and execute infrared observations at wavelengths mainly between 5 and 200 micron. The SPICA mission gives us a unique opportunity for coronagraph observations, because of the large telescope aperture, a simple pupil shape, capability of infrared observations from space and the early launch. We have started development of the SPICA coronagraph in which the primary target is direct observation of extra-solar Jovian planets. The main wavelengths of observation, the required contrast and the inner working angle (IWA) of the SPICA coronagraph instrument are set to be 5-20 micron, 106, and approximately 5 λ/D respectively, whereλ is the observation wavelength and D is the diameter of the telescope aperture. Coronagraphs using a checkerboard mask and a concentric ring mask have been investigated. We found some solutions for the SPICA pupil, which has a large obstruction due to the secondary mirror and its supports. We carried out laboratory experiments to examine coronagraphs obtained using checkerboard-type pupil masks with a central obstruction. Nano-fabrication technology with electron beam was applied to manufacture a high precision mask consisting of a patterned aluminum film on a glass substrate and its performance was confirmed by experiments with visible light. Contrast higher than 106 was achieved. In the future, we will be developing a cryogenic mid-infrared test-bed to investigate the SPICA coronagraphs.

Paper Details

Date Published: 7 July 2006
PDF: 9 pages
Proc. SPIE 6265, Space Telescopes and Instrumentation I: Optical, Infrared, and Millimeter, 626536 (7 July 2006); doi: 10.1117/12.670976
Show Author Affiliations
Keigo Enya, Japan Aerospace Exploration Agency (Japan)
Shinichiro Tanaka, Japan Aerospace Exploration Agency (Japan)
Takao Nakagawa, Japan Aerospace Exploration Agency (Japan)
Hirokazu Kataza, Japan Aerospace Exploration Agency (Japan)
Lyu Abe, National Astronomical Observatory of Japan (Japan)
Motohide Tamura, National Astronomical Observatory of Japan (Japan)
Jun Nishikawa, National Astronomical Observatory of Japan (Japan)
Naoshi Murakami, National Astronomical Observatory of Japan (Japan)
Kenta Fujita, Lab. of Solar System Physics, Kobe Univ. (Japan)
Yoich Itoh, Lab. of Solar System Physics, Kobe Univ. (Japan)

Published in SPIE Proceedings Vol. 6265:
Space Telescopes and Instrumentation I: Optical, Infrared, and Millimeter
John C. Mather; Howard A. MacEwen; Mattheus W. M. de Graauw, Editor(s)

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