Compensating Atmospheric Distortions of Point Sources and Extended Objects through an Adaptive Iterative Procedure

In this paper we introduce a technique to correct atmospheric turbulence. The characteristic of this promising procedure is that the distorted wavefront is corrected without any information about the wavefront itself. This technique relies on the combined use of a deformable mirror controlled by a Stochastic Parallel Gradient Descent (SPGD) algorithm and an image quality measurement. Even though this procedure is in terms of time slower than a direct wavefront reconstruction, it appears that compared to conventional AO systems the problems related to scintillations are noticeably reduced. This procedure is being now tested both for the correction of extended as well as point source objects.