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Proceedings Paper

A three-layer eight-octant phase mask towards broadband high-contrast observations
Author(s): Naoshi Murakami; Jun Nishikawa; Natsumi Akaiwa; Yusuke Komuro; Naoshi Baba; Motohide Tamura
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Paper Abstract

We designed and fabricated an achromatic eight-octant phase mask (8OPM) for broadband coronagraphic observations of exoplanets. The fabricated 8OPM is composed of three-layer eight-octant half-wave plates based on photonic crystals. By using Jones calculus, it is shown that the three-layer 8OPM achieves much higher contrast over broad wavelength range than that of the previous single-layer design. We carry out preliminary laboratory experiments of the coronagraph using the fabricated three-layer 8OPM. As a model star, we use several visible laser light sources for characterizing the coronagraphic performance. As a result, we obtain higher contrasts than theoretical ones of the single-layer 8OPM. However, the achieved contrasts are lower than the theoretical values of the three-layer one. At present we suspect that manufacturing errors of the half-wave plates in the 8OPM limit the achieved contrasts.

Paper Details

Date Published: 22 July 2016
PDF: 10 pages
Proc. SPIE 9912, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation II, 99126G (22 July 2016); doi: 10.1117/12.2231946
Show Author Affiliations
Naoshi Murakami, Hokkaido Univ. (Japan)
Jun Nishikawa, National Astronomical Observatory of Japan (Japan)
The Graduate Univ. for Advanced Studies (Japan)
National Institutes of Natural Sciences (Japan)
Natsumi Akaiwa, Hokkaido Univ. (Japan)
Yusuke Komuro, Hokkaido Univ. (Japan)
Naoshi Baba, Muroran Institute of Technology (Japan)
Motohide Tamura, National Astronomical Observatory of Japan (Japan)
National Institutes of Natural Sciences (Japan)
The Univ. of Tokyo (Japan)


Published in SPIE Proceedings Vol. 9912:
Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation II
Ramón Navarro; James H. Burge, Editor(s)

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