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Proceedings Paper

Two-channel polarization interferometric coronagraph to improve the detectability of extrasolar planets
Author(s): Naoshi Murakami; Tasuku Maeda; Naoshi Baba; Tsuyoshi Ishigaki; Nobuyuki Hashimoto; Motohide Tamura
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Paper Abstract

A dual-channel nulling coronagraph to improve the detectability of extrasolar planets is demonstrated. We have been developing a nulling coronagraph with a four-quadrant polarization mask, and confirmed its performance with monochromatic and polychromatic light sources. However, the imperfections of the mask cause the leakage of the starlight, which is obstructive to the detection of faint companions. Here, we propose a two-channel nulling coronagraph, where s- and p-polarized components of the incident light are separated. The light scattered and reflected from the atmosphere of an extrasolar planet is expected to be partially polarized, while the light from the parent star is usually unpolarized. Thus, the differential method, in which subtraction is taken between coronagraphic images of s- and p-polarized lights, is very useful for direct detection of extrasolar planets. In this approach, cancellation of the residual unpolarized starlight is realized when the coronagraphic performance of the two channels is identical. We constructed the two-channel instrument. The experimental results confirm that the two-channel coronagraph can suppress the residual stellar noise, and improve the detectability of faint companions. The effects of the difference between two channels on the detectability are also discussed.

Paper Details

Date Published: 12 October 2004
PDF: 8 pages
Proc. SPIE 5487, Optical, Infrared, and Millimeter Space Telescopes, (12 October 2004); doi: 10.1117/12.549548
Show Author Affiliations
Naoshi Murakami, Hokkaido Univ. (Japan)
Tasuku Maeda, Hokkaido Univ. (Japan)
Naoshi Baba, Hokkaido Univ. (Japan)
Tsuyoshi Ishigaki, Hokkaido Univ. (Japan)
Nobuyuki Hashimoto, Citizen Watch Co., Ltd. (Japan)
Motohide Tamura, National Astronomical Observatory of Japan (Japan)

Published in SPIE Proceedings Vol. 5487:
Optical, Infrared, and Millimeter Space Telescopes
John C. Mather, Editor(s)

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