DIAGNOSING UNKNOWN ABERRATIONS IN AN ADAPTIVE OPTICS SYSTEM BY USE OFPHASE-DIVERSITY

We outline a novel method for estimating a fixed aberration that is in the image path but not in the wave-front-sensor (WFS) path of an adap tive optics (AO) imaging system. We accomplish this through a nontradi tional application of the Gonsalves [Proc. SPIE 207, 32 (1997)] least- squares phase-diversity technique, using an ensemble of images and WFS data. The diversity phases required for this technique are provided b y the temporal differences in WFS residual phase measurements for diff erent members of the ensemble. We demonstrate the technique by using a ctual observations from an operational AO system exhibiting such an ab erration. An estimate of this aberration was obtained by the proposed algorithm that agrees reasonably well with the observed point-spread f unction. (C) 1997 Optical Society of America.