提出一种可实现351 nm波长激光高通量传输的终端光学组件(FOA)的物理设计方案，研究了设计优化方法，并利用神光Ⅱ装置第九路系统开展了实验研究。实验共进行了33发激光发射：激光光束净口径310 mm，时间脉冲宽度3 ns，1053 nm波长激光能量1000～4500 J。实验获得最高三次谐波转换效率69.6%和351 nm波长激光传输通量3.76 J/cm2，同时监测到高通量激光传输引起的动态环境污染物颗粒变化数和光学元件激光诱导损伤等现象。实验结果表明，通量密度约为3 J/cm2@351 nm的光学元件损伤主要是由激光传输散射鬼光束辐照材料所激发的污染物所致。

A physical design scheme of final optical assembly (FOA) to achieve 351 nm propagation with high fluence is introduced. The method of optimization design is researched and the experimental study is completed on No.9 system of SG-Ⅱ laser facility. 33 shots have been fired with beam diameter of 310 mm, laser pulse width of 3 ns and 1053 nm energy from 1000 to 4500 J. In the process of the experiment, the most efficiency of third harmonic conversion is 69.6% and the maximum fluence of 351 nm propagation is 3.76 J/cm2. And emphasis is given on the number of contamination change inside the FOA and the process of the optical damage originating from the high fluence propagation. The results show that the first cause to the optics damage with 3 J/cm2 at 351 nm is induced by amounts of contaminants which come from the scatter laser irradiating to materials.