Increasing the useful field of view of an adaptive optics system

The size of the corrected field of view of an adaptive optics system is though to be a severe limitation on the usefulness of an adaptive optics system. We show that under good seeing conditions the useful field of view is an order of magnitude larger than the field predicted by the classical isoplanatic angle. The corrected field of view is experimentally shown to increase when using spatially degraded wavefront corrections. Two methods of spatially degrading the wavefront were tested: low-order modal wavefront reconstructions and the use of a low-altitude Rayleigh wavefront reference beacon. In both cases the on- axis performance is sacrificed for an increased field of view.