Laboratory experiments on the 8-octant phase-mask coronagraph

Naoshi Murakami; Ryosuke Uemura; Naoshi Baba; Hiroshi Shibuya; Jun Nishikawa; Lyu Abe; Motohide Tamura; Nobuyuki Hashimoto

doi:10.1117/12.788145

12 July 2008 Laboratory experiments on the 8-octant phase-mask coronagraph

Naoshi Murakami, Ryosuke Uemura, Naoshi Baba, Hiroshi Shibuya, Jun Nishikawa, Lyu Abe, Motohide Tamura, Nobuyuki Hashimoto

Author Affiliations +

Proceedings Volume 7010, Space Telescopes and Instrumentation 2008: Optical, Infrared, and Millimeter; 70101J (2008) https://doi.org/10.1117/12.788145
Event: SPIE Astronomical Telescopes + Instrumentation, 2008, Marseille, France

Abstract

A four-quadrant phase-mask (FQPM) coronagraph can suppress perfectly stellar light when a star can be regarded as a point-like source. However, the FQPM coronagraph is highly sensitive to partially resolved stars, and shows second-order sensitivity to tip-tilt error leakage. Higher-order sensitivity is required for extremely high-contrast imaging of nearby stars. We propose an eight-octant phase-mask (EOPM) for achieving fourth-order sensitivity to tip-tilt errors. We manufactured the phase-mask utilizing a nematic liquid crystal (LC) device, which is composed of eight segments. A phase retardation of the LC can be adjustable by an applied voltage to the device. The LC phase-mask can be switched between FQPM-mode and EOPM-mode by applying appropriate voltages to the segments. We carry out experiments on the phase-mask coronagraph with various tip-tilt errors. The experimental results show the higher-order behavior of the EOPM compared to the FQPM. We present a current status of the laboratory experiments on the EOPM coronagraph, and also show coronagraphic performance of the EOPM derived from numerical simulations.

Citation Download Citation

Naoshi Murakami, Ryosuke Uemura, Naoshi Baba, Hiroshi Shibuya, Jun Nishikawa, Lyu Abe, Motohide Tamura, and Nobuyuki Hashimoto "Laboratory experiments on the 8-octant phase-mask coronagraph", Proc. SPIE 7010, Space Telescopes and Instrumentation 2008: Optical, Infrared, and Millimeter, 70101J (12 July 2008); https://doi.org/10.1117/12.788145

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