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基于波前功率谱密度(PSD)的定义,分析了采用功率谱密度方法研究中频波前畸变与焦斑旁瓣关系的可行性。由于任意形状的波前畸变都可以由不同空间频率的正弦函数叠加组成,以正弦函数波前为例进行功率谱密度分析和远场分析。分析表明,当中频波前畸变的幅度满足一定条件时,远场二级以上的衍射非常低,可以忽略不计,此时波前功率谱密度与焦斑旁瓣具有非常好的相似性,并且这种相似性仅与中频波前畸变的幅度有关,与空间频率无关。最后还用数值模拟的方法验证了这个结论对叠加后的结果仍然成立。研究结果可以用于设计满足惯性约束聚变(ICF)驱动器打靶对焦斑旁瓣要求的光学元件中频段波前畸变指标。
Based on the definition of wavefront power spectral density (PSD), the feasibility of using power spectral density method to study the relationship between mid-frequency wavefront distortion and focal sidelobe is analyzed. Because any shape of the wavefront distortion can be composed of different spatial frequency sine function superposition, the sine wave function as an example of power spectral density analysis and far-field analysis. The analysis shows that when the amplitude of mid-frequency wavefront distortion satisfies a certain condition, the diffraction above the second-order far-field is very low and can be neglected. At this time, the power spectral density of the wave front has a very good similarity with the focal spot sidelobe, and Similarity is only related to the amplitude of the mid-frequency wavefront distortion, and has nothing to do with the spatial frequency. Finally, numerical simulation is used to verify that this conclusion still holds for the superposition result. The results of this study can be used to design wavefront aberrations in the mid-band of optical components that meet the requirements of the ICF driver to target side-lobes.