光学元件上不可避免存在的“缺陷”会对传输光束产生调制，基于广义惠更斯菲涅耳衍射积分和角谱的定义，推导出了高斯光束经有限个小尺寸振幅调制型“缺陷”之后的光强和角谱解析式。详细研究了振幅调制型“缺陷”的尺寸大小及调制幅度对受调制光束的光强分布和角谱影响。结果表明，经过“缺陷”的光束传输一定距离之后光强恢复为高斯分布。而“缺陷”的尺寸越大，光强分布恢复为高斯分布所需的传播距离越长，且随“缺陷”尺寸及调制幅度增大，低频区的角谱减小，中高频区的角谱增大。

The unavoidable defects existing in optical components will influence the beam propagation in the optical system. Based on the Fresnel diffraction integral and the definition of angular spectrum, the analytical expressions for the light-intensity distribution and angular spectrum of a Gaussian beam modulated by finite-amplitude modulated defects are derived. The influence of the size and the modulation amplitude of the defects on the intensity distribution and angular spectrum of the beam is also studied. It is shown that the intensity distribution will recover to Gaussian distribution after propagating a certain distance. The larger size of defects is, the longer propagation distance is for the beam recovering to Gaussian distribution. Furthermore, the angular spectrum of the modulated beam in the low-frequency area becomes smaller and the angular spectrum in the high frequency area becomes greater with the increase of the size and the modulation amplitude of the defects.