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Proceedings Paper

A coronagraph system with unbalanced nulling interferometer: progress of dynamic range
Author(s): Jun Nishikawa; Kaito Yokochi; Naoshi Murakami; Lyu Abe; Takayuki Kotani; Motohide Tamura; Takashi Kurokawa; Alexander V. Tavrov; Mitsuo Takeda; Hiroshi Murakami
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Paper Abstract

We have studied a coronagraph system with an unbalanced nulling interferometer (UNI). It consists of the UNI, adaptive optics, and a coronagraph. An important characteristic is a magnification of the wavefront aberrations in the UNI stage, which enables us to compensate for the wavefront aberrations beyond the AO systems capabilities. In our experiments, we have observed the stable aberration magnification of about 6 times and compensation to about λ/100 rms corresponding to λ/600 rms virtually. As a result, at the final focal plane of a 3-dimensional Sagnac interferometric nulling coronagraph, we have obtained the extra speckle reduction of better than 0.07 by the advantage of the UNI-PAC system. In order to obtain better contrast, we consider improvement of the optics with an 8OPM coronagraph, a dual feedback control, an unbalanced nulling interferometer with 4QPM or VVM, and a wavefront correction inside the UNI.

Paper Details

Date Published: 21 September 2012
PDF: 6 pages
Proc. SPIE 8442, Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave, 84425D (21 September 2012); doi: 10.1117/12.925792
Show Author Affiliations
Jun Nishikawa, National Astronomical Observatory of Japan (Japan)
Kaito Yokochi, Tokyo Univ. of Agriculture and Technology (Japan)
Naoshi Murakami, Hokkaido Univ. (Japan)
Lyu Abe, Lab. Hippolyte Fizeau, CNRS, Univ. de Nice-Sophia Antipolis (France)
Takayuki Kotani, National Astronomical Observatory of Japan (Japan)
Motohide Tamura, National Astronomical Observatory of Japan (Japan)
Graduate Univ. for Advanced Studies (Japan)
Takashi Kurokawa, Tokyo Univ. of Agriculture and Technology (Japan)
Alexander V. Tavrov, Space Research Institute (Russian Federation)
Mitsuo Takeda, Utsunomiya Univ. (Japan)
Hiroshi Murakami, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (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, Editor(s)

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