Astron. Astrophys. Suppl. Ser. 137, 543-551
A hierarchical phasing algorithm for multi-element optical interferometers
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