An all guided two-beam stellar interferometer: preliminary experiment

We report an experiment demonstrating the potential of optical fibres in the design of stellar interferometers for space missions. For the first time to our knowledge, only guided optics components are used to achieve the different basic functions of a stellar interferometer: optical field propagation from the telescope to the mixing station; synchronisation of the field to be mixed by delay Lines; and beams splitting and recombination using optical fibre couplers. This preliminary experiment uses a two-telescope configuration and is mainly focused on the demonstration of the capability of the interferometric system to operate with a compensation of the optical path difference resulting from a telescope array tilt. Over this compensation the fringe visibility remains calibrated with a 3% accuracy. The investigation on the dispersion differential effects allows to compute simulations of the fringe visibility variation versus the fibre delay line status for any spectral distribution of the source. (C) 2000 Elsevier Science B.V. All rights reserved.