Experiment Using Extended Wavefront Controller Software Based On SPGD Algorithm

Laser beam is influenced by atmospheric turbulence during the transmission in free space and produces wavefront distortion,which has an impact on the imaging quality and performance of the optical system.Adaptive optics technology is an effective way to solve this problem.Compared with the traditional adaptive optics technology,the wavefrontsensorless adaptive optics technology does not require wavefront sensing.Compensation of wavefront distortion is achieved by optimizing the objective function using iterative algorithm controll the correction device.It has the advantages of simple structure and low cost.However,in practical applications and experiments,the photodetector used to obtain the objective function or the phase correction device that regulates the phase of the light field are different.Therefore,the wavefront control software structure framework needs to be scalable and easy to reuse.In this paper,the development and experimental verification of scalable wavefront control software based on SPGD algorithm(stochastic parallel gradient descent algorithm)is carried out for different detectors and correctors of wavefront-sensorless adaptive optics in different applications.Firstly,we numerically simulate the static and dynamic atmospheric turbulence based on phase-screen method,and designs a wavefront-sensorless adaptive closed-loop simulation program based on SPGD algorithm.Through the program simulation,the optimization parameters selection range is analyzed.The correction effects of the system under different atmospheric turbulence intensity and different wind speed conditions are systematically given.The influence of different turbulence conditions on the convergence of the algorithm is compared and analyzed.A scalable wavefront control software based on SPGD algorithm is designed and the extension methods are explained.The whole wavefront control program adopts objectoriented design,functions realize interface-oriented,with low coupling,reusable,and easy to expand.Technical support is provided for the extension of the interface between the application and the experimental input and output devices.The wavefront control software is used to control the UVC camera collecting the light field,and the 52-unit deformable mirror correcting the wavefront distortion.The adaptive optical closed-loop experimental system is designed and built.The parameters of the experimental system are given by the experiments,and the method of variable parameters is proposed to improve the convergence performance of the system.The correction results of the static and dynamic turbulence simulated by the liquid crystal spatial light modulator are given respectively.The effects of different turbulence conditions and wind speeds on the convergence performance of the system are compared and analyzed.Finally,a hot-air atmospheric turbulence simulation device which is muche closer to the actual atmospheric environment is used to verify system performance.Results show that the wavefront-sensorless adaptive optics system built with the wavefront control software has the ability to effectively correct the wavefront distortion and improve the quality of the received beam.Even under the conditions of strong turbulence and high wind speed simulated by the laboratory,the system has the ability to stabilize and converge.The work of this thesis provides a theoretical basis and reference for the subsequent application of the system in multiple occasions.