Adaptive optics operation with two wavefront sensors in a coronagraph for exoplanet observations

Masahito Oya; Jun Nishikawa; Masaaki Horie; Naoshi Murakami; Takayuki Kotani; Lyu Abe; Shiomi Kumagai; Motohide Tamura; Takashi Kurokawa; Hiroshi Murakami

doi:10.1117/12.925858

21 September 2012 Adaptive optics operation with two wavefront sensors in a coronagraph for exoplanet observations

Masahito Oya, Jun Nishikawa, Masaaki Horie, Naoshi Murakami, Takayuki Kotani, Lyu Abe, Shiomi Kumagai, Motohide Tamura, Takashi Kurokawa, Hiroshi Murakami

Author Affiliations +

Proceedings Volume 8442, Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave; 844255 (2012) https://doi.org/10.1117/12.925858
Event: SPIE Astronomical Telescopes + Instrumentation, 2012, Amsterdam, Netherlands

Abstract

A stellar coronagraph system for direct observations of extra solar planets is under development by combining unbalanced nulling interferometer (UNI), adaptive optics, and a focal plane coronagraph^{1, 2, 3, 4, 5}. It can reach a high contrast as using lambda/10000 precision optics by lambda/1000 quality ones. However, a sufficiently high contrast has yet to be obtained for the experiment. It is thought that the remaining speckle noise at the final coronagraph focal plane detector is produced by a “non-common path error” of lambda/100 level, which is a wavefront error of differences between the coronagraph and a wavefront sensor (WFS) of adaptive optics, even when the WFS indicates lambda/1000 conversion. The non-common path error can be removed by the focal plane sensing method of wavefront correction by wavefront sensing at the final focal plane detector, although it has an issue of operation for very faint targets because of a slow feedback loop. In the present paper, we describe how our coronagraph system becomes practically higher contrast by upgrading the control method of adaptive optics with the WFS assisted by a focal plane wavefront sensing. Then, we control a wavefront error by two feedback loops, the first of which uses a WFS to make fast control for telescope optics deformation and the second of which uses a focal plane detector to compensate for the non-common path error with slow control. We show experiment results of the coronagraph system performance with both wavefront sensing methods.

Citation Download Citation

Masahito Oya, Jun Nishikawa, Masaaki Horie, Naoshi Murakami, Takayuki Kotani, Lyu Abe, Shiomi Kumagai, Motohide Tamura, Takashi Kurokawa, and Hiroshi Murakami "Adaptive optics operation with two wavefront sensors in a coronagraph for exoplanet observations", Proc. SPIE 8442, Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave, 844255 (21 September 2012); https://doi.org/10.1117/12.925858

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available