Multi-telescope instruments cophasing for astronomy
Résumé
Interferometry is used to combine light from several telescopes to obtain a resolution equivalent to a single telescope with the diameter of the combined spread of beams. However, the performance of the instrument thus synthesized is linked to the measurement and the correction of the aberrations between the telescopes. For cophasing a large number of beams, focal-plane approach has been selected due to its simple opto-mechanical device. Several focal-plane algorithms, developed at ONERA, were validated by simulations and by experiments on a laboratory test bench; the results we obtained demonstrate that a simple focal-plane fringe sensor can be easily implemented on most instruments such as VLTI Very Large Telescope Interferometer /2nd generation (4 to 8 beams) or spaceborne interferometers.