Effects of a realistic adaptive optics system on the atmospheric propagation of a high-energy laser beam

An adaptive optics (AO) correction system is generally required to compensate for beam degradations caused by interactions between a high energy laser (HEL) beam and the atmosphere. The GRAND propagation code includes a model of a realistic AO system representing many features of a state-of-the-art beam control system. This AO system includes models of a wavefront sensor, a tilt mirror, a focus (secondary) mirror, and a woofer-tweeter deformable mirror arrangement. This paper reports the results of a study to assess the impact of the realistic AO system on the correctability of HEL-atmosphere interactions. The GRAND code results compare the performance of the low-pass filter model and the realistic AO system model in the presence of turbulence and moderate-to-severe thermal blooming. In addition, the effects of low frequency Kolmogorov turbulence were studied in terms of its impact on the AO system requirements.