EDP Sciences
Free access
Volume 403, Number 1, May III 2003
Page(s) 369 - 381
Section Physical and chemical processes
DOI http://dx.doi.org/10.1051/0004-6361:20030278

A&A 403, 369-381 (2003)
DOI: 10.1051/0004-6361:20030278

Achromatic dual-zone phase mask stellar coronagraph

R. Soummer1, K. Dohlen2 and C. Aime1

1  Laboratoire Universitaire d'Astrophysique de Nice - UMR 6525, Université de Nice Sophia Antipolis, Parc Valrose, 06108 Nice Cedex 2, France
    e-mail: Claude.Aime@unice.fr
2  Laboratoire d'Astrophysique de Marseille, 2 place Leverrier, 13248 Marseille, Cedex 4, France
    e-mail: Kjetil.Dohlen@oamp.fr

(Received 31 October 2002 / Accepted 14 February 2003)

This paper presents a generalization of the Roddier & Roddier Phase Mask coronagraph for polychromatic observations. It is shown that using a dual-zone phase mask, combined with complex apodization, both phase and size chromatism can be compensated simultaneously to produce high extinction of a point source over large bandwidths, for example the entire K band with a residual integrated starlight of $3.2\times
10^{-4}$ and a star intensity level of  10-6 at an angular separation of  $3\lambda/D$. Other advantages of the proposed technique include the compatibility with centrally obscured telescopes, absence of blind axes and no symmetrization of the images.

Key words: instrumentation: high angular resolution -- techniques: high angular resolution -- stars: planetary systems

Offprint request: R. Soummer, Remi.Soummer@unice.fr

© ESO 2003

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