APIC : Absolute Position Interfero-Coronagraph for direct exoplanet detection

International audienceContext. For detecting and directly imaging exoplanets, coronagraphic methods are mandatory when the intensity ratio between a star and its orbiting planet can be as large as 10 6. In 1996, a concept of an achromatic interfero-coronagraph (AIC) was presented for detecting very faint stellar companions, such as exoplanets. Aims. We present a modified version of the AIC not only permitting these faint companions to be detected but also their relative position to be determined with respect to the parent star, a problem that was not solved in the original design of the AIC. Methods. In our modified design, two cylindrical lens doublets were used to remove the 180 • ambiguity introduced by the AIC's original design. Results. Our theoretical study and the numerical computations show that the axis of symmetry is destroyed when one of the cylindrical doublets is rotated around the optical axis