An application of a phase retrieval method for correcting strong scintillation effects of laser beam projection through turbulence in multimirror adaptive optics system is reported. In this approach, two deformable mirrors are used in the system and the phase applied to the deformable mirrors is obtained based on the phase retrieval method. An extended random beacon is used to provide input signals for the wave front sensor. Computer simulations are used to evaluate the performance of the system in the presence of strong turbulence. Our results show that this phase retrieval method with two deformable mirrors yields better performance compared with the conventional adaptive systems.
We describe a new approach to controlling the deformable mirror in beam projection systems operating in conditions of strong scintillation. Under the conditions of interest, two-way propagation is required to create the light used for wavefront sensing. In this situation, the beacon can subtend an angle that is many times larger than the isoplanatic angle. Our approach uses a nonlinear optimization-based technique to determine the deformable mirror (DM) figure which optimizes an image sharpness metric. This correction is applied to the outgoing laser beam with the goal of concentrating most of the laser's power on a small area of the target. The optimization algorithm chosen for this purpose is the simultaneous perturbation stochastic approximation (SPSA). Our results show that using phase-only conjugation with
nonlinear optimization of an image sharpness metric can provide an improvement in encircled energy performance compared to phase-only conjugation with only linear Hartman wavefront sensor processing.