Estimating the point spread function of the adaptive optics system ADONIS using the wavefront sensor measurements

Laboratoire d'Astrophysique, Observatoire de Grenoble, BP. 53, F-38041 Grenoble, France

Send offprint request to: S. Harder

Received: 20 July 1999
Accepted: 12 October 1999

Abstract

Adaptive Optics (AO) has been developed to compensate the wavefront deformation due to the atmospheric turbulence. The wavefront correction, however, is often only partial and a residual blur is present in a long exposure image. It is therefore important to deconvolve the image to do accurate photometry or to detect faint structures. For this, the point spread function (PSF) has to be known. The PSF is highly variable in time and difficult to calibrate. We developed an algorithm which reconstructs the PSF of the ADONIS AO system from the wavefront sensor measurements. We present the results obtained for different observing conditions and discuss the limits of the method. We prove the existence of a local non-stationary turbulence from analyzing the spatial and temporal behaviour of the turbulent phase. We found difficult to achieve photometric precision higher than 5 to 10% on secondary components of multiple systems with flux ratio larger than 4.