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Astron. Astrophys. Suppl. Ser. 137, 543-551

A hierarchical phasing algorithm for multi-element optical interferometers

E. Pedretti1[*] - A. Labeyrie2

1 - Collège de France & University of Manchester, Nuffield Radio Astronomy Laboratories, Jodrell Bank, UK-Cheshire, SK11 9DL, UK
2 - Collège de France et Observatoire de Haute-Provence, CNRS, F-04870 Saint-Michel l'Observatoire, France

Received February 26; accepted March 26, 1999


Large multi-aperture interferometers are expected to provide snap-shot images with milli- to nano-arcsecond resolution, directly at the combined focus. This requires a densified exit pupil and phased beams for all the wavelengths used. The wave analysis methods serving for adaptive optics in monolithic telescopes being inadequate for diluted apertures, we have developed a different phasing algorithm. It involves a hierarchy of aperture triplets and uses image sharpness criteria. Numerical simulations on unresolved and resolved objects show that a single iteration is generally sufficient. On wavelength-dependant objects, the proper position indexing of the monochromatic image components appears also efficiently achievable.

Key words: instrumentation: interferometers -- methods: numerical -- techniques: image processing -- techniques: interferometric -- telescopes

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