Astron. Astrophys. Suppl. Ser. 144, 541-552

Modeling the imaging process in optical stellar interferometers

M. Schöller ¹ - R. Wilhelm ^{1, 2, 3} - B. Koehler ¹

Send offprint request: M. Schöller

1 - European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching b. München, Germany
e-mail: mschoell@eso.org, rwilhelm@eso.org, bkoehler@eso.org
2 - Deutsches Zentrum für Luft- und Raumfahrt, Institut für Weltraumsensorik, Rutherford-Str. 2, 12489 Berlin, Germany
3 - DaimlerChrysler Aerospace, Dornier Satellitensysteme GmbH, SX 2A, 88039 Friedrichshafen, Germany

Received December 10, 1999; accepted April 26, 2000

Abstract:

Optical interferometers on the ground, like ESO's Very Large Telescope Interferometer (VLTI) and the Keck Interferometer, and in space, like the InfraRed Space Interferometer (IRSI/Darwin) and the Space Interferometry Mission (SIM), will bring a major breakthrough in optical and near-infrared high angular resolution astronomy at the beginning of the next millennium. These instruments are complex systems with an exceptionally interdisciplinary character involving active/adaptive optics, structural mechanics, control engineering, electronics and various environmental disturbances (e.g. atmospheric turbulence and absorption, wind, seismic noise). For their design and development an approach from two sides is appropriate: laboratory testbeds are used for experimental investigations while numerical modeling tools perform an End-to-End instrument simulation. We have developed a set of numerical modeling tools to simulate the dynamic imaging process of an interferometer. The time-dependent point spread function (PSF) mainly characterizes the imaging performance of the instrument. It is computed by an optomechanical model. Based on the knowledge of the PSF the image of an incoherently radiating extended object is computed using a Fourier optical method. This article describes the modeling approach including an extension to more than two interferometric beams. Some results of simulations on the VLTI as a representative example are shown.

Key words: image processing -- optical interferometry -- observational methods -- simulation