激光雷达信号在大气中传输时，大气中的气体分子和大气气溶胶粒子、尘埃、雨等对激光信号的吸收和散射导致光信号能量的衰减是影响激光雷达信号传输的重要因素。另外，由于大气密度分面目 不均匀导致激光沿光路上的折射，大气湍流效应导致光束横截面上能量分布起伏、光束扩展和漂移等，这些对激光雷光信号的传输产生一定的影响。本文对激光在大气中传输的各种能量衰减机制进行分析和讨论，为激光雷达系统的设计提供理论依据。

When radar signals propagate in the atmosphere,the absorption and scattering of air molecule,aerosol particles,dust and cloud,fog and rain result in energy attenuation of ladar signals,In addition,the unhomogeneous distribution of atmospheric density leads to refraction of ladar signals propagation,and turbulence in the atmosphere results in energy fluctuation in the cross-section,the attenuation mechanisms of ladar signals propagating in the atmosphere are discussed and analyzed,and these give a theoretical basis of ladar system.