中文摘要：

为研究大气湍流对激光回波的光强起伏、漂移、波前畸变以及偏振退化的影响,计算了大气后向散射回波在不同探测高度下的信噪比（SNR）,结合Hufnagel-Valley模型分析了球面波大气闪烁调制因子,得到了近地大气光强起伏方差;利用模式匹配数值积分方法,得到了不同高度的空间光-单模光纤（SMF）的耦合效率;从光场复振幅和探测面上光斑的爱里斑模型出发,研究了空间相位起伏对外差效率的影响;最后基于20m气体池差分吸收探测CO2浓度的实验数据,分析大气湍流对外场实验影响。结果表明,大气湍流会使系统精度降低1.21倍,20 m光程下系统精度由424.83×10^-6变为514.04×10^-6,性能下降严重。本文所作的分析对差分吸收相干激光雷达（DIAL）外场实验有重要参考意义。

英文摘要：

Atmospheric turbulence can induce intensity scintillation,beam drift,wavefront distortion and polarization degradation of returned signal,which affects the spatial light coupling ratio of the detection system as well as the heterodyne efficiency,and as a result,the detection accuracy will be reduced.The signal to noise ratio（SNR）of the returned atmospheric backward scattering signal is calculated at different heights;also the atmospheric scintillation modulation factor is analyzed based on the HufnagelValley model,and the near-surface intensity scintillation variance is acquired.The method of pattern matching numerical integration is used to simulate the wavefront aberration,and the space light-signal mode fiber coupling efficiencies at different heights are obtained.Based on the complex amplitude of the light field and the airy spot model on the detector surface,the effects of the space phase fluctuation on heterodyne efficiency are analyzed.Combined with CO2 differential absorption detection experiment data using a 20m-optical path gas cell,the CO2 concentration detection accuracy of this experiment setup is determined;and the effects of atmospheric turbulence on outdoor experiment are studied.The results show that the atmospheric turbulence will reduce system detection resolution by 1.21 times,and through the 20 moptical path,the system resolution is changed from 424.83×10^-6 to 514.04×10^-6.This analysis is of importance to the outdoor experiment of coherent differential absorption lidar（DIAL）.