OPTIMIZING THE PERFORMANCE OF CLOSED-LOOP ADAPTIVE-OPTICS CONTROL-SYSTEMS ON THE BASIS OF EXPERIMENTALLY MEASURED PERFORMANCE DATA

An experimental method is presented to optimize the control algorithm for a closed-loop adaptive-optics system employed with an astronomical telescope. The technique uses wave-front sensor measurements from an independent scoring sensor to calculate adjustments to the wave-front reconstruction algorithm and the bandwidth of the adaptive-optics cont rol loop that will minimize the residual mean-square phase distortion as measured by this sensor. Specifying the range of possible adjustmen ts defines the class of control algorithms over which system performan ce will be optimized. In particular, the technique can be used to comp ute an optimized wave-front reconstruction matrix for use with a presp ecified adaptive-optics control-loop bandwidth, optimize the control-l oop bandwidth for a given reconstruction matrix, optimize the individu al modal control bandwidths for a fixed modal reconstructor, or simult aneously optimize both the wave-front modes and their associated contr ol bandwidths for a fully optimized modal control algorithm. The metho d applies to closed loop adaptive-optics systems that incorporate one or more natural or laser guide stars and one or more deformable mirror s that are optically conjugate to distinct ranges along the propagatio n path. Initial experimental results are reported for the case of a hy brid adaptive-optics system incorporating one natural guide star, one laser guide star, and one deformable mirror. These results represent w hat is to the authors' knowledge the first stable closed-loop operatio n of an adaptive-optics system using multiple guide stars. (C) 1997 Op tical Society of America.