基于剪切干涉法的大气相干长度直接实时测量

Real-Time Measurement of Atmospheric Coherence Length Based on Lateral Shearing Interferometry

大气湍流的随机变化对星地激光通信性能有所限制,高速激光通信对瞬时湍流特性的描述提出新的要求。基于剪切干涉法对大气相干长度进行直接、实时测量。通过测量经过大气扰动的畸变光波前的剪切相位分布,利用满足各态历经随机过程条件时,相位结构函数的时间平均等于系综平均的特点,结合Fried相位结构函数,得到实时的大气相干长度。采用波长为635nm的光波进行1.2km距离实验,成功测得了大气相干长度,并通过对比实验验证了其可行性,解决了在高速激光通信中,传统的测量大气相干长度方法在时间累积和统计分析方面的限制。

Random changes of atmospheric turbulence have restrictions on the performance of satellite-to-ground laser communication. High-speed laser communication proposes new requirements on the description of turbulence characteristics in a short period. A direct, real-time measurement of atmospheric coherent length method based on lateral shearing interferometry is proposed. By measuring the sheared phase distribution of the phase distortion caused by atmospheric turbulence, considering that the time average of phase structure function is equal to the ensemble average when the turbulence is an ergodic random process and combining the Fried phase structure function, the atmospheric coherent length can be measured. Experiments are conducted by using a 635 nm laser wave through a 1.2 km distance. The results demonstrate the feasibility of this method, and solve the constraints in time accumulation and statistical analysis of the traditional measurements.