Design of a space borne optical aperture synthesis system for high resolution astronomy

Abstract

This paper proposes a design for a space borne demonstrator interferometer with imaging capabilities. This demonstrator would be a first step in the development of an operational astronomical instrument using aperture synthesis. Multiple aperture interferometry is a promising technique for high resolution imaging in space. Indeed the use of modular elements based on optical fibres represents an attractive low cost approach. The instrument is based on the use of independent triplets of telescope linked with optical fibres. For each triplet, only the phase closure of the system is measured. This does not require an accurate cophasing of the apertures and leads to realistic stability and control specifications. The complete instrument is then built by adding the desired number of such triplet modules. The detailed design of one module is described starting at level of the receiving telescopes down to the focal plane where the control of the stability of the optical path differences is performed as well as the scientific observations. The global operation of the system will also be described. We also briefly recall the technology validation activities which have shown on the ground the feasibility and performance of all components of such a systems as well as its end to end validation.