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A hierarchical phasing algorithm for multi-element optical interferometers

E. Pedretti

Collège de France & University of Manchester
Nuffield Radio Astronomy Laboratories, Jodrell Bank, UK-Cheshire, SK11 9DL, England
(Now at Observatoire de Haute-Provence - CNRS)

A. Labeyrie

Collège de France & Observatoire de Haute-Provence - CNRS
F-04870 Saint-Michel l'Observatoire, France

Astronomy & Astrophysics, Received 26 January 1999 / Accepted 19 February 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.

Keywords: Instrumentation: Interferometers - Methods: numerical - Techniques: image processing - Techniques: interferometric - Telescopes


Ettore Pedretti