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Proceedings Paper

Phase-shifting coronagraph
Author(s): François Hénault; Alexis Carlotti; Christophe Vérinaud
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Paper Abstract

With the recent commissioning of ground instruments such as SPHERE or GPI and future space observatories like WFIRST-AFTA, coronagraphy should probably become the most efficient tool for identifying and characterizing extrasolar planets in the forthcoming years. Coronagraphic instruments such as Phase mask coronagraphs (PMC) are usually based on a phase mask or plate located at the telescope focal plane, spreading the starlight outside the diameter of a Lyot stop that blocks it. In this communication is investigated the capability of a PMC to act as a phase-shifting wavefront sensor for better control of the achieved star extinction ratio in presence of the coronagraphic mask. We discuss the two main implementations of the phase-shifting process, either introducing phase-shifts in a pupil plane and sensing intensity variations in an image plane, or reciprocally. Conceptual optical designs are described in both cases. Numerical simulations allow for better understanding of the performance and limitations of both options, and optimizing their fundamental parameters. In particular, they demonstrate that the phase-shifting process is a bit more efficient when implemented into an image plane, and is compatible with the most popular phase masks currently employed, i.e. fourquadrants and vortex phase masks.

Paper Details

Date Published: 1 September 2017
PDF: 22 pages
Proc. SPIE 10400, Techniques and Instrumentation for Detection of Exoplanets VIII, 104001J (1 September 2017); doi: 10.1117/12.2272775
Show Author Affiliations
François Hénault, Institut de Planétologie et d’Astrophysique de Grenoble (France)
Alexis Carlotti, Institut de Planétologie et d’Astrophysique de Grenoble (France)
Christophe Vérinaud, Institut de Planétologie et d’Astrophysique de Grenoble (France)

Published in SPIE Proceedings Vol. 10400:
Techniques and Instrumentation for Detection of Exoplanets VIII
Stuart Shaklan, Editor(s)

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