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.
We discuss different arrangements of rotational shearing interferometers intended for the observation of faint
companions to nearby stars. Several methods have been proposed for nullifying the radiation of the star to enable the
detection planet. One proposal is the rotational shearing interferometer (RSI). The concept of the RSI is based on the
idea of comparing a wave front to a rotated version of the wave front. We analyze different previously proposed
arrangements of the RSI and find that some represents different instruments.
We are interested in detecting planets around nearby stars by direct methods. Previously, we developed the radiometric
and imaging conditions for detection of extra-solar planets. With star to planet irradiance factor of 105, it appears that the
interferometric method is the most likely to produce adequate signal. A rotational shearing interferometer (RSI) may be
used to cancel the infrared radiation of the host star, allowing the detection of the planet. We have established the
conditions for star-radiation cancellation with an RSI. Among these conditions, we have that the star must be on the
optical axis, and that the phase difference between the interferometer arms must be π. Nevertheless, the ideal conditions
are almost impossible to achieve. Therefore, we have analyzed the caused effect when we consider that the star is not on
the optical axis, and an arbitrary phase difference is included. In this work, we extend the study considering the
interferometer misalignments.
We develop some conditions to detect extra-solar planets with rotational shearing interferometer. We consider that the
star is not on the interferometer axis. In addition, we include an arbitrary optical path difference between the
interferometer arms. Previously, we showed that the light from the star may be cancelled out when the OPD is λ/2. We
obtain analytic expressions for these conditions. We simulate several incidance distributions of the star-planet system. It
is of utter most importance to align the interferometer axis with the host star, to the precision of 5 μrad.
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.