The Early Days of the Very Large Telescope Interferometer

Summary

This recollection begins in 1978: ESO was building its future, considering the need and technical possibility of a very large telescope. In 1974, the success of optical interferometry had opened the way to a daring concept for the VLT, soon conceived as an array of four 8-m telescopes. In 1987, the VLT project was approved and began: it included a coherent mode, where the four telescopes, plus two smaller and movable ones, could be combined interferometrically at near-infrared wavelengths. This became possible because adaptive optics, developed for this purpose in France and ESO, succeeded to phase individual pupils, hence providing the full interferometric sensitivity of large pupils. After recalling briefly the early steps which led to the highly successfull operation of a VLTI in 2001, some suggestions may be drawn for the future of optical interferometry in Europe.

The author of this short VLTI story would like to share some of his personal recollections and references. By no means could he pretend to give here an historical account, which would require a thorough search of documentation,interviews of the early actors and confrontation of viewpoints. The author simply hopes to help the readers, especially the younger ones, to find in a reading of the past, even biased, some good reasons to think and build the future. He also apologizes to the many people, often friends, he does not quote and who have been so decisive in the VLTI success