ANISOPLANATISM IN ADAPTIVE OPTICS

Anisoplanatism is a major limitation on performance of adaptive optical systems for overcoming the effects of atmospheric turbulence. To reduce anisoplanatic error we have introduced a new concept of "Phase Derivative Adaptive Optics"-PDAO. In conventional adaptive systems only the beacon's wavefront phase is measured and then conjugated to compensate the atmospheric wavefront distortion in a desired path. In our PDAO system both the beacon's wavefront phase and phase derivative are measured. Then the predistortion phase is constructed with the phase and the phase derivative. This predistortion phase has been proven more precise to compensate the desired distortion. Thus the anisoplanatic residual phase error can be reduced and the isoplanatic patch size can be increased. We believe that PDAO is a prospective method to reduce anisoplanatism in adaptive optics.