According to the theory of geometrical optics and the requirements of a particle observation experiment

the systematic initial parameters were researched and a 532 nm Fourier transform lens was designed using ZEMAX. The opto-mechanical structure was designed according to the system feature. By using the software of finite element method

the influence of vacuum on optics spacing and mirror surface shape was analyzed. The analytical and experiment results indicate that the changes of optics spacing and mirror surface shape caused by vacuum can not affect on the imaging quality. The testing experiment using the visual microscope shows that the system resolution is 2.81 μm. After the alignment

the system can keep low-vacuum (lower than 100 Pa) 12 h. And the system has already been used in the particle observation experiment successfully.