New Generation Adaptive Optics For Astronomy. An Inverse Problem With Large Number Of Degrees Of Freedom

摘要

Observations of fainter and fainter astrophysical objects in the universe require an increasing flux-collecting area, which means larger and larger telescopes. However, the optical turbulence in the atmosphere damages the resolution of the images provided by the ground-based telescopes. In order to combine high sensitivity and angular resolution large ground-based telescopes are nowadays associated with adaptive optics systems (0A)[1]. OA must provide real-time correction of the atmospherical perturbation thanks to a servo-loop system including at least one wavefront sensor (AFO), a controller and one deformable mirror (MD) to apply the compensation, as illustrated by figure 1. The OA design must evolve for the future telescopes with mirror diameters of several tenths of meters planned for 2017. On the one hand, the sensed part of the wavefront (WF) will not always match the part to be corrected for the astrophysical observations, so that the criterion of performance should be expressed in the WF space. On the other hand, the next generation of OA will have to cope with several thousands of actuators, to be controlled in real-time, which requires new and fast algorithms.