The flexible adaptive optics concept

Abstract

The availability of small deformable mirrors with large number of actuators and stroke, on one hand, and versatile wavefront sensors (pyramid WFS), on the other, allows the development of AO systems whose equivalent pitch can be adapted freely to the guide stars and seeing conditions. On moderately large telescopes (4 m class) this exibility allows a performance (Strehl and limiting magnitude) always better than what a classical, frozen Shack-Hartman design would allow. Moreover, adding several natural guide star wavefront sensors, we believe a single system could do anything from extreme AO to GLAO, i.e using the same hardware, and adapting the control software parameters to the observation mode. Taking advantage of such a system requires the use of a zoom optics in the imager in order to optimally match the plate scale with the PSF. We demonstrate that sub-optimal pixel size would result in a significant loss in term of science data reduction, in particular object detectability. The raison d'etre of such a versatile system is to popularize AO in community of astronomers not familiar with it, by allowing, on the same telescope, high resolution as well as seeing improved observations. This is particularly important for countries where very few large telescopes are available. On the long term, we think that most moderate size telescopes will have this sort of exible multi-purpose AO systems as a default. The exible AO concept will be implemented on the new 4 m Turkish telescope, DAG. © 2017 Instituto de Astrofisica de Canarias. All rights reserved.