Speckle reduction technique using the self-coherent camera for the common-path visible nulling coronagraph

Kenta Yoneta; Naoshi Murakami; Koki Yoshida; Ryuta Koike; Takayuki Kotani; Hajime Kawahara; Naoshi Baba; Motohide Tamura

doi:10.1117/12.2560471

13 December 2020 Speckle reduction technique using the self-coherent camera for the common-path visible nulling coronagraph

Kenta Yoneta, Naoshi Murakami, Koki Yoshida, Ryuta Koike, Takayuki Kotani, Hajime Kawahara, Naoshi Baba, Motohide Tamura

Author Affiliations +

Proceedings Volume 11451, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation IV; 114513Y (2020) https://doi.org/10.1117/12.2560471
Event: SPIE Astronomical Telescopes + Instrumentation, 2020, Online Only

Conference Poster

Abstract

Direct detection of faint exoplanets is challenging due to a high-contrast ratio between a primary star and a planet. A high-contrast imaging system has an important role in directly detecting exoplanets. The system consists of coronagraph and speckle reduction technique. A common-path visible nulling coronagraph (VNC) is one of the attracting methods for high-contrast observation because of a simple optical configuration and achromatic stellar elimination. We introduced a spatial light modulator (SLM) into the common-path VNC to suppress residual speckles caused by wavefront aberrations. The SLM can potentially generate a huge dark hole thanks to its large pixel format. As a focal plane wavefront sensor, we utilized the self-coherent camera (SCC) method for the common-path VNC. We carried out the laboratory demonstration of the speckle reduction technique for the common-path VNC combined with the SCC methods. The experimental results show an initial contrast of 2.2 × 10^-5 and a final contrast of 1.3 × 10^-6 in monochromatic light at a wavelength of 633 nm. We discuss the limiting factors of the contrast for improvement of our demonstration to achieve the higher contrast.

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Kenta Yoneta, Naoshi Murakami, Koki Yoshida, Ryuta Koike, Takayuki Kotani, Hajime Kawahara, Naoshi Baba, and Motohide Tamura "Speckle reduction technique using the self-coherent camera for the common-path visible nulling coronagraph", Proc. SPIE 11451, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation IV, 114513Y (13 December 2020); https://doi.org/10.1117/12.2560471

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