针对神光Ⅲ主机装置使用的光学元件, 基于分形理论, 分析中高频相位畸变的统计分布特征, 指出其满足分数布朗随机场, 并利用结构函数法对分形维数进行计算, 统计结果显示, 大口径钕玻璃片的分形维数在2.34~2.43之间。利用局部稳态的随机中点位移法, 提出一种新的表征光学元件相位的方法, 将分形维数作为参数, 可衡量中高频相位畸变, 对高功率激光光学元件的评价有参考意义。

Based on the fractal theory, this paper analyzed statistical distribution features of middle-high frequency phase distortion of the optics for Shenguang-Ⅲ laser facility. The middle-high frequency phase distribution is found to be consistent with the model of fractional Brownian random field. The fractal dimension was calculated by structure function. The fractal dimension of large-aperture neodymium-doped phosphate amplifier glass is distributed between 2.34 and 2.43. A method of phase simulation by random midpoint-displacement was presented. In this method, the fractal dimension can be viewed as a parameter for estimating phase distortion, which helps to evaluate the high laser optics.