Direct detection of Earth-like exoplanets requires a high-contrast imaging system to suppress bright stellar light that prevents the detection. The wavefront sensing and control technique which is one component of the high-contrast imaging system can suppress stellar scattered light (speckles) caused by wavefront aberrations. However, deformation of the system due to temperature changes in space telescopes or atmospheric turbulence in ground-based telescopes cause speckles that fluctuate faster than the wavefront sensing and control. As the post-processing technique, the Coherent Differential Imaging on Speckle Area Nulling (CDI-SAN) method was proposed to suppress the fast-fluctuating speckles. We are conducting the laboratory demonstration of the CDISAN method using two types of experimental facilities. One of them is equipped with a deformable mirror and a field programmable gate array. In our initial laboratory demonstration, we achieved 10−8 level contrast. To achieve higher contrast, we are updating our facility. The other facility is equipped with a spatial light modulator (SLM). In this facility, the contrast was improved by 10−1 using the CDI-SAN method.
Various types of high-contrast imaging instruments have been proposed and developed for direct detection of exoplanets by suppressing nearby stellar light. Stellar speckles due to wavefront aberration can be suppressed by the appropriate wavefront control, called the dark hole control. However, the speckles, which fluctuate faster than the dark hole control due to atmospheric turbulence in ground-based telescopes or instrument deformation caused by temperature changes in space telescopes, cannot be suppressed by the control and remain in focal plane images. The Coherent Differential Imaging on Speckle Area Nulling (CDI-SAN) method was proposed to overcome such fast fluctuating speckles and detect exoplanetary light. We constructed an optical setup in a laboratory to demonstrate the CDI-SAN method. With the dark hole control and the CDI-SAN method, we achieved 10−8 level of contrasts.
We propose a new high contrast imager for Kyoto 4m segmented telescope called SEICA (Second-generation
Exoplanet Imager with Coronagraphic Adaptive optics), aiming at detection and characterization of selfluminous
gas giants within 10AU around nearby stars. SEICA is aggressively optimized for high performance
at very small inner working angle, 10-6 detection contrast at 0".1 in 1-hour integration. We start the on-sky
commissioning test in 2016 and the science observations in 2017. Since it is the first time to realize the highcontrast
imaging on the segmented telescope, SEICA is an important step toward future high contrast
sciences on Extremely Large Telescopes (ELTs). This paper presents an overall of the SEICA program and
the conceptual design for ultimate performance under given atmospheric conditions.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
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.