Free access article

DOI: 10.1051/aas:1996148

Astronomy and Astrophysics Supplement Series, Vol. 117, May II 1996, 167-178

Optical design, modelling and tolerancing of a Fizeau interferometer dedicated to astrometry

S. Loiseau and S. Shaklan

Send offprint requests to: S. Loiseau (loiseau@bluenote.obspm.fr)

DESPA, Observatoire de Paris, F-92195 Meudon Cedex, France
Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, U.S.A.

Received September 19; accepted November 2, 1995

Abstract:

Space-based interferometers dedicated to wide-angle astrometry would dramatically increase the accuracy of angular measurements fundamental to a wide range of astrophysical problems. The proposed Global Astrometric Interferometer for Astrophysics (GAIA), a continuously rotating instrument comprising two or three interferometers, will reach the as level on more than 35 million objects. The necessary wide field-of-view for such a precision could be obtained with a Fizeau interferometer. We designed and modelled a 2.6 m baseline interferometer with two 40 cm apertures, and overall dimensions compatible with the size of the Ariane V payload shroud. It has a 1 degree diffraction limited field-of-view. The response of the optical system to small perturbations on each optical element is given in terms of fringe visibility, which is shown to depend mainly on sub-aperture spot separation. The robustness of the design to thermal, mechanical and manufacturing errors is discussed.

Key words: instrumentation: interferometers --- telescopes --- astrometry

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