A large number of coronagraphs have been proposed to overcome the ratio that exists between the star and its planet. The planet finder of the Extremely Large Telescope, which is called EPICS, will certainly need a more efficient coronagraph than the ones that have been developed so far. We propose to use a combination of chromatic Four Quadrant Phase Mask coronagraph to achromatize the dephasing of the device while maintaining a high rejection performance. After describing this multi-stage FQPM coronagraph, we show preliminary results of a study on its capabilities in the framework of the EPICS instrument, the planet finder of the European Extremely Large Telescope. Eventually, we present laboratory tests of a rough prototype of a multi-stage four-quadrant phase mask. On one hand, we deduce from our laboratory data that a detection at the 10^-10 level is feasible in monochromatic light. On the other hand, we show the detection of a laboratory companion fainter than 10^-8 with a spectral bandwidth larger than 20%.

Date Published: 15 July 2008
PDF: 9 pages
Proc. SPIE 7015, Adaptive Optics Systems, 70156C (15 July 2008); doi: 10.1117/12.788722

Published in SPIE Proceedings Vol. 7015:
Adaptive Optics Systems
Norbert Hubin; Claire E. Max; Peter L. Wizinowich, Editor(s)