Piston control with adaptive optics in stellar interferometry

Free access article

Issue		A&A Volume 365, Number 2, January II 2001


Page(s)		314 - 323
Section		Instruments, observational techniques and data processing
DOI		http://dx.doi.org/10.1051/0004-6361:20000185

A&A 365, 314-323 (2001)
DOI: 10.1051/0004-6361:20000185

Application to the GI2T interferometer and bimorph mirrors

C. Vérinaud¹ and F. Cassaing² .

¹ Observatoire de la Côte d'Azur (OCA), Département Fresnel, 2130, route de l'Observatoire, 06460 Saint-Vallier-de-Thiey, France
² Office National d'Études et de Recherches Aérospatiales (ONERA), DOTA, BP 72, 92322 Châtillon Cedex, France

(Received 29 August 2000 / Accepted 18 October 2000)

Abstract
The general purpose of an adaptive optics system is to correct for the wavefront corrugations due to atmospheric turbulence. When applied to a stellar interferometer, care must be taken in the control of the mean optical path length, commonly called differential piston. This paper defines a general formalism for the piston control of a deformable mirror in the linear regime. It is shown that the usual filtering of the piston mode in the command space is not sufficient, mostly in the case of a bimorph mirror. Another algorithm is proposed to cancel in the command space the piston produced in the pupil space. This analysis is confirmed by simulations in the case of the GI2T interferometer located on Plateau de Calern, France. The contrast of the interference fringes is severely reduced in the case of a classical wavefront correction, even in short exposures, but is negligible with our algorithm, assuming a realistic calibration of the mirror. For this purpose, a simple concept for the calibration of the piston induced by a deformable mirror is proposed.

Key words: instrumentation: interferometers -instrumentation: adaptive optics - atmospheric effects -methods: numerical -techniques: interferometric

Offprint request: C. Vérinaud

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.