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Paper: The nulling coronagraph applied to interferometric arrays
Volume: 194, Working on the Fringe: Optical and IR Interferometry from Ground and Space
Page: 201
Authors: Guyon, O.; Roddier, F.
Abstract: The nulling stellar coronagraph, first proposed by Roddier and Roddier (PASP 109, p. 815, 1997), uses a small phase mask to shift by 180 degrees the phase of the central part of the Airy spot. This leads to destructive interference which strongly attenuates the central Airy spot as well as the rings, as demonstrated by the result of an experiment we carried out on an optical bench (Guyon et al., PASP submitted). The nulling coronagraph can also be used on an interferometric array by first densifying the entrance pupil (Labeyrie, A&A Supl., 118, p. 517, 1996). The pupil is then rediluted to avoid the narrowing of the field of view. This is the only known nulling technique that produces a true undisturbed image with the central bright star removed. Numerical simulations allow us to evaluate the performance of this nulling technique with different geometrical configurations of subapertures.
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