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Proceedings Paper

A laboratory experiment for a new free-standing pupil mask coronagraph
Author(s): K. Haze; K. Enya; T. Kotani; L. Abe; T. Nakagawa; H. Matsuhara; T. Sato; T. Yamamuro
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Paper Abstract

This paper presents the results of a laboratory experiment on a new free-standing pupil mask coronagraph for the direct observation of exoplanets. We focused on a binary-shaped pupil coronagraph, which is planned for installation in the next-generation infrared space telescope SPICA. Our laboratory experiments on the coronagraph were implemented inside a vacuum chamber (HOCT) to achieve greater thermal stability and to avoid air turbulence, and a contrast of 1.3×10-9 was achieved with PSF subtraction. We also carried out multi-color/broadband experiments to demonstrate that the pupil mask coronagraph works, in principle, at all wavelengths. We had previously manufactured a checker-board mask, a type of binary-shaped pupil mask, on a glass substrate, which had the disadvantages of light loss by transmission, ghosting from residual reflectance and a slightly different refractive index for each wavelength. Therefore, we developed a new free-standing mask in sheet metal, for which no substrate was needed. As a result of a He-Ne laser experiment with the free-standing mask, a contrast of 1.0×10−7 was achieved for the raw coronagraphic image. We also conducted rotated mask subtractions and numerical simulations of some errors in the mask shape and WFEs. Speckles are the major limiting factor. The free-standing mask exhibited about the same ability to improve contrast as the substrate mask. Consequently, the results of this study suggest that the binary-shaped pupil mask coronagraph can be applied to coronagraphic observations by SPICA and other telescopes.

Paper Details

Date Published: 21 September 2012
PDF: 15 pages
Proc. SPIE 8442, Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave, 84425B (21 September 2012);
Show Author Affiliations
K. Haze, Japan Aerospace Exploration Agency (Japan)
K. Enya, Japan Aerospace Exploration Agency (Japan)
T. Kotani, Japan Aerospace Exploration Agency (Japan)
L. Abe, Lab. J.-L. Lagrange, , CNRS, Univ. of Nice Sophia Antipolis (France)
T. Nakagawa, Japan Aerospace Exploration Agency (Japan)
H. Matsuhara, Japan Aerospace Exploration Agency (Japan)
T. Sato, Agency of Industrial Science and Technology (Japan)
T. Yamamuro, OptCraft (Japan)

Published in SPIE Proceedings Vol. 8442:
Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave
Mark C. Clampin; Giovanni G. Fazio; Howard A. MacEwen; Jacobus M. Oschmann Jr., Editor(s)

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