EDP Sciences
Free Access
Volume 374, Number 3, August II 2001
Page(s) 1161 - 1168
Section Instruments, observational techniques and data processing
DOI https://doi.org/10.1051/0004-6361:20010619

A&A 374, 1161-1168 (2001)
DOI: 10.1051/0004-6361:20010619

The achromatic phase knife coronagraph

L. Abe1, F. Vakili1 and A. Boccaletti2

1  Observatoire de la Côte d'Azur, Département Fresnel, CNRS UMR 6528, 06460 Saint Vallier de Thiey, France
2  Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France

(Received 20 November 2000 / Accepted 11 April 2001)

We present the concept of a nulling coronagraph which theoretically attains the brightness ratio of 108 suitable to directly detect exo-Earths in the vicinity of their parent stars. The concept is derived from the classical Foucault's optics test and Zernike's self-destructive phase contrast principle. We propose an achromatic set-up which should dramatically improve its wide band efficiency. The whole system is simulated against a numerical model which validates a formal analytical approach. The coronagraph is then compared to other concepts and its advantages and shortcomings are outlined, suggesting future laboratory developments and tests on the sky.

Key words: techniques: interferometric -- stars: binaries: close -- stars: planetary systems

Offprint request: L. Abe, Lyu.Abe@obs-azur.fr

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