Interferometric apodization of rectangular apertures

Free access article

Issue		A&A Volume 379, Number 2, November IV 2001


Page(s)		697 - 707
Section		Instruments, observational techniques and data processing
DOI		http://dx.doi.org/10.1051/0004-6361:20011293

A&A 379, 697-707 (2001)
DOI: 10.1051/0004-6361:20011293

Application to stellar coronagraphy

C. Aime, R. Soummer and A. Ferrari

UMR 6525 Astrophysique, Faculté des Sciences, Université de Nice Sophia Antipolis, Parc Valrose, 06108 Nice Cedex 2, France
e-mail: Claude.Aime@unice.fr, Andrea.Ferrari@unice.fr

(Received 17 July 2001 / Accepted 20 August 2001 )

Abstract
We describe the principle of an apodization technique for rectangular apertures that can be implemented using a Michelson or a Mach-Zender interferometer. Using several interferometers, any integer power of cosine functions can be obtained. The technique is considered for application to the Apodized Square Aperture (ASA) concept recently proposed by Nisenson & Papaliolios (2001). Simple analytic expressions for the Point Spread Functions of such apodized apertures are given. For a cosine to the power N apodization, the resulting focal plane amplitude is simply the sum of N+1 weighted and shifted sine cardinal functions. The interest of such apodized apertures for coronagraphy is investigated. It appears that these apodization functions are very efficient provided that only a central part of the cosine-arch is used. Analytic expressions are derived for the residual amplitude left in an image of the aperture after the coronagraphic experiment. Best results are obtained with a cosine squared apodization.

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

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

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