利用复高斯函数展开法，有限尺寸圆形平面镜被分解为一系列高斯孔径的叠加。在此基础上，利用ABCD矩阵结合Rytov近似，计算了湍流中有限尺寸圆形平面镜回波的平均强度及后向增强系数，揭示了反射波二阶矩振荡区间的存在。通过计算相干度函数及相干长度，证明了振荡区间湍流会对波前产生更大的影响。

Based on complex Gaussian-function expansion method, the transmitting wave is decomposed into a series of Gaussian beam components. ABCD ray-matrix theory combined with Rytov approximation is used to derive the expressions of the mean intensity and the backscattering enhancement coefficient of the reflected wave from a finite circular mirror in the atmospheric turbulence, which reveals the existence of the oscillation zone. The degree of coherence function and coherence length are calculated and the results prove that the turbulence in the oscillation zone has a larger effect on the wave front.