ADAPTIVE OPTICS LONG EXPOSURE POINT SPREAD FUNCTION RETRIEVAL FROM WAVEFRONT SENSOR MEASUREMENTS: TESTS ON REAL DATA

Current astronomical adaptive optics (AO) systems are not able to fully correct the atmospheric turbulence. As a result, the quality of the AO long exposure images is degraded by a residual blur which significantly reduces the contrast of the fine details [1]. Removing this residual blur is the field of image restoration (deconvolution) and since this problem is general to many imaging applications, many different methods have already been developed. To achieve an accurate restoration however, an accurate estimation of the system Point Spread Function (PSF) is usually required. For adaptive optics imaging, the shape of the PSF depends on how well the deformable mirror is able to compensate for the wavefront distortions. This “degree of correction” in turn depends on the size and magnitude of the object used as a reference for wavefront sensing, but also on the characteristics of the turbulence, which is known to be a non-stationary process. As a results, the AO PSF is highly variable [2]. The usual way around this problem involves dedicating of significant portion of the observing time to the sole acquisition of a point source, from which the current PSF is estimated.