基于外差干涉的涡旋光水下传输相位测量

Phase measurement of vortex beam after underwater transmissionbased on heterodyne interference

涡旋光束在湍流介质中传输时,光束相位会受到湍流运动的影响产生畸变。采用了一种基于外差干涉的点像元相位提取方法,通过采集各个点在一个周期内的干涉条纹获得的相对相位,重构出涡旋光束经过水下湍流传输后的相位分布。通过功率谱反演法生成随机相位屏,完成不同湍流强度下涡旋光束的传输仿真,结果表明光束相位畸变随着湍流强度的增大而增加。搭建了实验装置,实现了水下环境的涡旋光传输及相位测量。实验结果表明,当涡旋光在存在湍流的水下传输时,其复振幅分布经历了较为复杂的传输过程,强度分布及相位均存在畸变,所采用的方法能精确测量出涡旋光的复杂相位分布,有效完成涡旋光的拓扑荷数识别。

When a vortex beam propagates in a turbulent medium,the phase will be distorted by the influenceof turbulent motion.In this paper,a point pixel phase extraction method based on heterodyne interference is proposed.By collecting the relative phase of each point's interference fringes in a period,the phase distribution of a vortex beamis reconstructed after its turbulent transmission under water.The random phase screen is generated by the powerspectrum inversion method,and the transmission simulation of the vortex beams under different turbulence iscompleted.The result shows that the distortion increases with the increase of turbulence intensity.An experimentaldevice was built to realize the phase measurement of vortex beams in underwater environments.The experimentalresults show that when a vortex beam is transmitted in turbulent water,its complex amplitude distribution undergoes arelatively complicated transmission process,and its intensity distribution and phase are distorted.The methodproposed in this paper can accurately measure the complex phase distribution of a vortex beam and effectively identifyits topological charges.