KDP功能晶体加工表面微缺陷严重限制了自身的光学性能和激光负载能力，课题针对该晶体加工表面微缺陷诱导激光损伤的演变机制及其对抗激光损伤能力的影响问题，综合表征加工表面裂纹、划痕、凹坑等典型微缺陷的特征参数，探究微缺陷在强激光辐照下的热力学和电磁学作用机制，实现其综合特性表征；建立加工表面微缺陷诱导激光损伤的动力学模型，深入研究微缺陷在应力、温度、电磁、流场等多场耦合作用下引起的激光损伤动力学过程，探索晶体元件强激光损伤和损伤扩展的内在物理机制；揭示基频、二倍频和三倍频重频激光辐照下微缺陷对元件抗激光损伤能力的影响规律，获得对激光损伤最为敏感的缺陷种类和尺寸范围，由此建立用于强激光环境下晶体加工表面微缺陷光伤性能评价的新方法。本课题旨在揭示KDP晶体强激光诱导损伤机理并提升其激光负载能力，课题的研究可为大口径功能晶体元件的超精密加工、激光预处理及精密微修复技术提供理论基础和参数依据。

The optical properties and laser load capacity of KDP functional crystal have been badly limited by the machining-induced surface micro-defects. Aiming at the issues of evolution mechanisms of laser damage initiated by micro-defects on KDP surface and their effect on laser damage resistance, this work will be carried out following three aspects shown below. Firstly, the feature parameters of typical micro-defects (e.g., cracks, scratches and dents) are to be tested, and the thermodynamic and electromagnetic mechanisms involving the interaction between micro-defects and intense lasers are to be explored for the characterization of their comprehensive properties. Then, the dynamics model of defect-induced laser damage will be built, and the laser damage dynamic processes are to be intensively investigated with the consideration of multi-physics coupling effects (e.g., stress, temperature, electromagnetic, and flow fields). The underlying physical mechanisms involving the defect-induced laser damage and its growth behavior would be explored as well. Besides, the effect law of surface micro-defects on the laser damage resistance of KDP optics will be revealed, and the size range and category of the most dangerous defect, which is the most susceptible to laser damage would be determined. On basis of this, new methods for effectively evaluating the laser damage performance of micro-defects on machined KDP optical surfaces would be correspondingly developed. This work is strongly motivated not only by exploring the laser damage mechanisms of KDP crystal but also improving its laser load capacity. The anticipated achievements of this project could provide theoretical and parametric basis for the ultra-precision machining, laser preprocessing and precision micro-repairing of large-aperture KDP crystal components.