Development of the Coherent Differential Imaging on Speckle Area Nulling (CDI-SAN) Method

Abstract

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. © 2023 SPIE.