光学表面微纳粒子强激光诱导多相瞬态耦合下的损伤机制研究

The life-time of optics components is seriously influenced by laser-induced damage resulting from the surface micro-nano particles during the operation of high-power laser facility, which also limits the fluence of system. It is closely related to surface particles UV absorption characteristics and surface microstructure induced by pollution under high power laser irradiation. In this work, the ultrafast diagnostic combined with spectral analysis are proposed to study the transient phase transition of photosensitive micro-nano particles irradiated by nanosecond laser. Meanwhile, the mechanisms of UV absorption characteristics of optical surface under the multiphase coupling in the process of micro particle phase transition are also investigated. The specific mechanism of micro-nano particles on laser-induced damage can be obtained by understanding the phase transition process of micro-nano particles absorbing UV laser and reconstruction principle of optical surface microstructure. The results can provide an important scientific basis and theoretical support on the controlling of micro-nano particles on optics surface used in high-power laser facility.

在高功率激光装置运行过程中，光学元件表面沉积的微纳粒子在强紫外激光作用下会诱导表面发生损伤，严重影响光学元件的使用寿命，限制高功率激光装置运行通量的提升。这与表面微纳粒子紫外吸收特性及激光辐照下微纳粒子诱导光学表面微观结构的变化规律密切相关。本项目针对光敏类吸收特质的微纳粒子，采用超快探测结合光谱分析的技术，研究其在纳秒激光作用下的瞬态相变过程，及光学表面在微纳粒子相变过程引起的复杂多相耦合条件下的紫外吸收特性变化的物理机制，通过系统研究微纳粒子吸收紫外激光的相变过程，探索在此多相场条件下光学表面微观结构重构的规律，深入认识微纳粒子在激光诱导损伤过程中所起的作用机制。通过本项目的研究，可以为高功率激光系统光学表面的微纳粒子的控制提供科学依据和理论支撑。

在高功率激光装置运行过程中，光学元件表面沉积的微纳粒子在强紫外激光作用下会诱导表面发生损伤，严重影响光学元件的使用寿命，限制高功率激光装置运行通量的提升和稳定运行。这与表面微纳粒子紫外吸收特性及激光辐照下微纳粒子诱导光学表面微观结构的变化规律密切相关。本项目探索了激光装置内部光敏类微纳粒子的来源、产生机理，明确了高功率激光装置内部污染物的来源，并确定了微纳粒子的产生过程。在此基础上，利用光热吸收的方式研究了激光装置内光学表面微纳粒子的吸收特性，并搭建超快激光探测平台和离线损伤测试平台，对光学表面微纳粒子诱导损伤的多相耦合过程进行观测，揭示了微纳粒子在强紫外激光辐照作用下的行为变化机制。最后通过对损伤点吸收特性、损伤形貌及成分的分析，确定了多相场耦合作用下的微纳粒子诱导光学元件损伤物理机制。在此基础上，掌握了微纳粒子相变引起的光学表面紫外吸收特性和损伤特性的变化规律，为高功率激光装置内部光学元件表面微纳粒子的控制标准和评价体系的建立提供技术支撑。