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 control loop that will minimize the residual mean-square phase distortion as measured by this sensor. Specifying the range of possible adjustments defines the class of control algorithms over which system performance will be optimized. In particular, the technique can be used to compute an optimized wave-front reconstruction matrix for use with a prespecified adaptive-optics control-loop bandwidth, optimize the control-loop bandwidth for a given reconstruction matrix, optimize the individual modal control bandwidths for a fixed modal reconstructor, or simultaneously optimize both the wave-front modes and their associated control bandwidths for a fully optimized modal control algorithm. The method applies to closed loop adaptive-optics systems that incorporate one or more natural or laser guide stars and one or more deformable mirrors that are optically conjugate to distinct ranges along the propagation path. Initial experimental results are reported for the case of a hybrid adaptive-optics system incorporating one natural guide star, one laser guide star, and one deformable mirror. These results represent what is to the authors' knowledge the first stable closed-loop operation of an adaptive-optics system using multiple guide stars. (C) 1997 Optical Society of America.