基于相干合成涡旋光束光场分布角向不变性的评价函数构建及其应用研究  

Metric Function Construction for Coherent Synthetic Vortex Beam Based on Angular Invariance of the Light Field Distribution and Its Application

作　　者：秦广为 谢文科[1] 邹行健 于涛 谢巧 QIN Guangwei;XIE Wenke;ZOU Xingjian;YU Tao;XIE Qiao(School of Physics,Central South University,Changsha 410083,China;Department of Materials Science and Engineering,Shenzhen MSU-BIT University,Shenzhen 518172,China)

机构地区：[1]中南大学物理学院,长沙410083 [2]深圳北理莫斯科大学材料科学与工程学院,深圳518172

出　　处：《光子学报》2023年第12期176-186,共11页Acta Photonica Sinica

基　　金：中南大学中央高校基本科研业务费专项资金(No.2022ZZTS0728)。

摘　　要：大气湍流引入的波前畸变导致相干合成涡旋光束质量劣化,需进行波前畸变校正。基于相干合成涡旋光束光场分布的角向不变性,通过像清晰度函数提取明暗干涉条纹区域的总光强,构建角向条纹对比度评价函数,将评价函数应用于随机并行梯度下降算法,可以实现单环以及双环阵列结构的相干合成涡旋光束波前畸变自适应校正。仿真实验结果表明,相较于光强相关系数等传统评价函数,以角向条纹对比度作为评价函数的随机并行梯度下降算法具有校正性能好、收敛速度快的优点。此外,单环和双环结构相干合成涡旋光束的波前校正结果均验证了角向条纹对比度作为相干合成涡旋光束评价函数的有效性及优势。In the atmospheric transmission,due to the effect of atmospheric turbulence,the Coherent Synthetic Vortex(CSV)beam will undergo wavefront distortion and lead to intensity profile aberration and Orbital Angular Momentum(OAM)mode expansion,making the CSV beam quality unable to meet the practical application requirements.In order to mitigate the wavefront phase distortion brought by turbulence,the phase correction technology based on adaptive optics is particularly important.The SPGD algorithm is widely used in adaptive optical systems without wavefront sensing because of its fast convergence speed and high convergence accuracy.However,the performance of the Stochastic Parallel Gradient Descent(SPGD)algorithm depends on the accuracy of metric function.Given the uniqueness of the CSV beam,it is necessary to develop a new metric function by evaluating the light field features of the CSV beam.By theoretical analysis,it is known that the intensity of the CSV beam is distributed periodically in the angular direction.Since the periodic variation feature is independent of transmission distance and array structure parameters,the angular fringe contrast,which evaluates energy concentration in the bright fringe and prevents energy accumulation in the dark fringe,is an appropriate metric function.When the angular fringe contrast is used as the metric function,the chosen bright and dark fringe angle widthαwill affect the SPGD algorithm performance.To establish the selection criteria of angular fringe contrast metric function,the SPGD correction experiment is performed when the value ofαis changed in steps of 1.41°,which shows that a smaller value ofαcan result in higher convergence accuracy and the faster convergence speed for the SPGD algorithm.On the basis of this,the wavefront distortion of CSV beam is corrected by SPGD algorithm with the angular fringe contrast as the metric function.In order to verify the validity of the angular fringe contrast as metric function,comparative experiment is carried out to verify the effe

关 键 词：自适应光学 涡旋光束 角向不变性 评价函数 随机并行梯度下降算法 

分 类 号：O439[机械工程—光学工程]