Focal plane masks in adaptive optics systems

This paper gives a general overview of the application of focal plane masks to adaptive optical wavefront sensing systems, and shows how they are related to several wavefront sensors used in optical shop testing. The results of several numerical simulations of a wavefront sensor based on a phase contrast type focal plane mask are then presented. In the last section, we outline a proposal for a wavefront sensor based on a dark ground type focal plane mask. This method can be used in conjunction with fiber based optical interferometers to yield an adaptive optics system which does not need to take corrected light from the observation path for use in the analysis of the aberrations. Only aberrated light is taken from the observation path and sent to the wavefront sensor, thus creating a very economical wavefront sensor.