Design And Realization Of Adaptive Optical Principle System Without Wavefront Sensing

The adaptive optics system can effectively correct the wavefront distortion caused by atmospheric turbulence and improve the quality of the received light field,the adaptive optics system has been successfully applied in astronomical observation and free space optical communication.However,the conventional adaptive optics system needs to detect and reconstruct the measured beam,which leads to the complex structure of the system,which is not conducive to the miniaturization of the technology and the increase of the system cost.In order to simplify the structure and reduce the system cost,especially to meet some conventional adaptive optics wavefront sensorless adaptive optics system concept has been proposed and since developed rapidly in recent years.It differs from the conventional adaptive optical system in that it does not need to be directly subjected to wavefront detection and reconstruction,but rather to the use evaluation function module to optimize the processing of realizing the adaptive optical function.In this paper,we focus on the performance improvement of near-ground wireless free space optical communication system,and carry out the research of adaptive optics without wavefront detection.Based on the structure of conventional adaptive optics,the adaptive optics principle is introduced,as well as the research status and development trend of adaptive optics are expounded in detail.The structure of the turbulence,the mathematical model and its influence on the optical wave field are studied.The phase fluctuation under different turbulence intensity and the far field intensity distribution of the beam after turbulence transmission are simulated.Based on the stochastic parallel gradient descent(SPGD),we carry out the theory of adaptive optics.Here we use the pure phase liquid crystal spatial light modulator(SLM)as the wavefront corrector,and the CCD camera to collect the intensity information of the distorted wavefront for the objective function optimization.We design and development of the wavefront controller based on the ARM Cortex-A8 core to achieve the objective function of the original optical field image information processing,optimization algorithm and wavefront corrector drive control function;Based on the Linux system,we developed a wavefront sensorless adaptive optics principle system control software to achieve thesystem closed-loop control.Turbulence is generated by one SLM and the other SLM is use to correct.The experiment results show that after 200 iterations the energy of the performance evaluation function(the total gray value of 25 pixels)increases from 3037 to 4863.The effect of the algorithm is proved,and the closed-loop correction sensorless is realized,which provides platform support for the non-wavefront sensing adaptive optics research and technology development.