中文摘要：

对于光外差体制的激光雷达而言，为减弱大气扰动的影响，需要研究大气衰减及大气湍流对其探测性能的影响。从光场的复振幅和探测面上光斑的爱里斑模型出发，给出了信噪比这一表征外差探测系统关键性能指标。分析了大气衰减和大气湍流对信号光复振幅的影响，研究了大气衰减和弱湍流相位起伏下的光外差探测效率。研究表明，大气衰减不会造成外差效率降低，此时信噪比降低的主要原因是回波能量的衰减；大气湍流将会引起光场的相位起伏、振幅起伏及传输方向变化，进而造成探测效率的降低。

英文摘要：

The influence of atmospheric attenuation and atmospheric turbulence on the detection performance of optical heterodyne detection ladar system should be analyzed in order to attenuate the effect of atmospheric turbulence. SNR, which is the key performance index of heterodyne system, was derived from the complex amplitude of light field and airy disk model on the detector surface. The influence of atmospheric attenuation and atmospheric turbulence on the complex amplitude of signal light field was analyzed, and the heterodyne detection efficiency affected by attenuation and phase vibration in weak turbulence was also analyzed. Numeric simulations show that atmospheric attenuation can＇t reduce the heterodyne detection efficiency, the main reason leading to lower SNR is the attenuation of return wave energy. The turbulence can cause phase vibration, amplitude vibration and transmitting direction fluctuation, and then make heterodyne detection efficiency reduce.