提出空间滤波器的透镜焦距需同时满足真空度和透镜球差最小的要求，滤波小孔的发散角必须小于某一定值才能有效滤除高频分量，并由此计算出本文所用高功率激光系统中的空间滤波器的小孔孔径约为20倍衍射极限。同时，分析了滤波小孔在光轴上所处位置的范围，即得出只要处于距焦平面1.04mm的范围内都是合理的结论。利用光学设计软件Fred建立模型进行验证，模拟结果表明，根据本文提出的计算方法所设计的空间滤波器能够有效地滤除系统中的高频分量和杂散光。

The focal length of the lens in the spatial filter should simultaneously satisfy the requirement of vacuum and the minimum spherical aberration. In order to filter the high frequency components, the divergence angle of the filter must be less than a certain value according to the system requirement. So the aperture of the filter hole used in the high power laser system is about 20 times of the diffraction limitation. At the same time, the scope of the location of the filter hole in the optical axis is reasonable as long as the location within the focal depth. In addition, the model was built by means of the optical design software to simulate validation. The simulation results show that the designed spatial filter according to the method presented in the paper can effectively filter out the high frequency components and stray light in the system.