Design of Telescopes for Interferometry: Specificity and Key Characteristics.

Intrinsically, the stellar interferometry calls for outstanding the tracking performances, optical pathlength stability, pupil stability and image quality. In addition, the size and configuration of the optical array is prevalent for the resolution and U-V plane coverage and thus the imaging capabilities. The implementation of medium size telescopes on the optical array is a common approach. If these telescopes can be relocated amongst a supernumerary set of piers, the number of baselines even increases drastically.

Some of the features of telescopes operated for stellar interferometry are common to classical telescopes in level of performance: pointing, differential pointing, tracking and image quality for instance. Some other features as the pupil stability are higher by the level of performance, or even specific as for the optical pathlength stability or the relocation accuracy of the telescope on the pier.

The unit telescopes of Magdalena Ridge Observatory Interferometer (New Mexico Tech) and the Auxiliary Telescope System of the VLTI (ESO) are dedicated to interferometry. This presentation intends to explain what the implication in the design of the telescopes is, how the performances are attained trough complex optimization processes making use of multidisciplinary simulation method and at the end validated by test in factory and on-site.