Quantification of critical parameters for a rotational shearing interferometer to detect extrasolar planets

Abstract

There is increasing interest to detect extrasolar planets directly. In the last years, more than 500 planets have been discovered by means of indirect methods. However, the small signal-to-noise ratio and the small angular separation of the star-planet system have hindered the direct detection of the optical / IR signals caused by the planets. Several methods have been proposed to cancel the star irradiance and detecting the presence of the planet around them. One proposal is the rotational shearing interferometer (RSI). Previously, by exact ray trace, we determined the positioning tolerances and the resolution of the fine mirror movements needed to satisfy a maximum wavefront deviation of λ/10 (at 633 nm) in the RSI. In this work, we show a method to quantify, employing exact ray trace and the interference pattern, the critical parameters for this RSI to detect extrasolar planets.