Closed-loop control for laser beam shaping system before guide star projection

The adaptive optics system performance depends on multiple factors, including the quality of the laser beam before being projected to the mesosphere. Cumbersome procedures are required in the laser system to optimize the laser beam in terms of amplitude and phase. However, aberrations of the laser beam are still detected during the operations. The performance of laser projection systems can be improved compensating the effects of aberrations in the laser source or misalignment in the transfer optics before the laser beam propagating through the aperture. Despite the algorithm previously reported predict effective amplitude and phase correction is strongly dependent of an accurate DM characterization and transfer optics alignments. The use of feedback makes the system response better in presence of modeling error and external disturbances. A 2-DM closed loop approach for amplitude and a phase correction is designed. Finally the results of simulations and comparisons are discussed.