Research on Shack-Hartmann wavefront restoration algorithm under atmospheric scintillation conditions

Optical communication technology is the future direction for realizing high-speed broadband networks in space. However, the performance of optical communication will be limited by atmospheric turbulence in the pathway. Adaptive optics have been proved effective in suppressing atmospheric turbulence, but adaptive optics have reduced efficacy in strong atmospheric turbulence due to light intensity scintillation. When light intensity scintillates, current wavefront recovery algorithms will have reduced spatial resolution and poor wavefront recovery accuracy. In this paper, a novel wavefront recovery algorithm is proposed to set up a light gatherer for every sub-aperture of the Schack-Hartmann wavefront sensor influenced by light intensity scintillation. Distributed light gatherer is set for every sub-aperture with insufficient light intensity, and gatherer will keep ADU accumulation until the set accuracy threshold is satisfied. Then, use mode method to get the distribution of aberration phase. This reconstruction algorithm is numerically simulated and experimentally verified under the condition of light intensity scintillation. The results show that, when the atmospheric turbulence has a scintillation factor of 0.50, the recovered wavefront processed by the distributed light gathering method is significantly improved compared with the results of the conventional recovery algorithm: the wavefront recovery error is reduced from 1.34λ to 0.82λ, which is 0.52λ less, and the accuracy effect is improved by 39%. The proposed algorithm can effectively enhance the accuracy of center-of-mass computation under the light intensity scintillation condition caused by atmospheric turbulence and improve the performance of adaptive optics system.