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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。
For the LIDAR laser radar, in order to reduce the influence of atmospheric disturbance, it is necessary to study the influence of atmospheric attenuation and atmospheric turbulence on its detection performance. Based on the complex amplitude of light field and the Ariake model of the spot on the detection surface, the key performance index of signal-to-noise ratio heterodyne detection system is given. The influence of atmospheric attenuation and atmospheric turbulence on the complex amplitude of signal is analyzed. The detection efficiency of optical heterodyne under atmospheric attenuation and weak turbulent phase fluctuation is studied. The results show that the atmospheric attenuation does not reduce the efficiency of heterodyne. At this moment, the signal-to-noise ratio decreases mainly due to the attenuation of the echo energy. The atmospheric turbulence will cause the phase fluctuation, amplitude fluctuation and transmission direction of the light field, Reduced efficiency.