激光预处理后的高反膜表面会形成等离子体烧蚀，等离子体烧蚀结构的存在会对传输光束的光强分布产生调制效应，引起光束畸变。实验测试了1064 nm连续光束经过烧蚀样品后的光斑能量分布，分析了产生调制的原因并讨论了这种调制效应随距离的变化情况，为功能性损伤阈值判断及安全有效使用预处理样品提供依据。实验结果表明，等离子体烧蚀结构中的锥形坑可引起峰值强度增强并形成环状条纹，经烧蚀斑结构调制的光束与未经调制的光束之间的峰值强度对比度和调制度都随传输距离的增加逐渐降低，即调制效应随光束传输距离的增加而逐渐减小。

Plasma scalds will be induced in the 1064 nm high reflectivity thin film during laser preconditioning, and they will modulate the laser beam which irradiates the scalds area, leading to laser beam distortion. Energy distribution of 1064 nm continuous laser which irradiates the scalds area is tested, and the reason of modulation and its expression in different laser propagation distance is analysed, both of which provides basis for the functional damage evaluaiton and reasonable use of laser-conditioned sample. The result of the experiment indicates that the pit in the center of scalds may strengthen the peak intensity of beam with annular fringes, and the maximum energy contrast and modulation degree between un-modulated laser beam and modulated laser beam becomes smaller with the laser propagation distance increasing, which means the phenomenon of laser modulation caused by plasma scalds becomes weak with the increasing propagation distance.