为了实现二氧化硫分析仪精确连续地检测空气中低含量SO2，针对传统二氧化硫检测仪在荧光汇聚时存在光线汇聚效果弱、像差大且由于透镜的焦距长增大了荧光采集光路长度等问题，在传统仪器的基础上对荧光采集光路重新进行了设计优化。采用分解光焦度的方法改善系统的球差问题，进行了理论分析和实验验证。改进后对其进行ZEMAX仿真并运用正交法对新光路进行修正。通过仿真两种光路的非序列结构阴影模型图、探测查看器的光照图以及点列图，取得了光强以及光斑直径的实验数据。结果表明，优化后的光路系统峰辐强度达到了219.41W/cm2，弥散斑直径减少了17%。该方案能够有效解决传统光路中的不足之处，成像质量效果更佳。

In order to realize the accurate and continuous detection of SO2 in air by SO2 analyzer, and solve the problems of weak light convergence effect, large aberration and longer optical path of fluorescence acquisition due to the lengthening of focal length of lens in traditional sulfur dioxide detector when fluorescence converges, on the basis of traditional instruments, the optical path of fluorescence acquisition was redesigned and optimized. The method of decomposition of light focus was used to improve the spherical aberration of the system. Theoretical analysis and experimental verification were carried out. After the improvement, ZEMAX simulation was carried out and orthogonal method was used to correct the new optical path. By simulating the non-sequential structured shadow model of two light paths, the illumination map of the detection viewer and the point chart, experimental data of light intensity and spot diameter were obtained. The results show that, the peak-to-radial intensity of the optimized optical system reaches 219.41W/cm2. The diameter of the speckle is reduced by 17%. This scheme can effectively solve the shortcomings of traditional optical path and the imaging quality is better.