KDP晶体加工表面微缺陷诱导激光损伤的演变机制及其对抗光伤能力的影响研究

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.

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。

KDP功能晶体加工表面微缺陷严重限制了自身光学性能和激光负载能力，从而大大限制了其在激光核聚变工程中应用。针对该晶体加工表面微缺陷诱导激光损伤机制及其对抗激光损伤能力的影响问题，开展了晶体加工表面微缺陷多模态表征、缺陷诱导激光损伤机制、缺陷对元件抗激光损伤能力影响等方面研究工作。主要研究成果如下：. 1、完成了软脆KDP晶体加工表面微缺陷多模态表征，实现了晶体表面微缺陷几何形貌、荧光特性等特征参量提取；研究了加工表面微缺陷对微观力学性能的影响规律；探究了晶体加工表面微缺陷光致瞬/稳态荧光光谱特性；获得了强激光辐照下微缺陷诱导激光光场调制规律，为建立晶体加工表面微缺陷与激光损伤性能关联关系提供了重要依据。. 2、建立了强激光辐照下KDP晶体加工表面微缺陷诱导激光损伤初、中后期动力学模型，首次揭示了KDP晶体元件表面激光辐照初期能量沉积机制；获得了微缺陷诱导激光损伤典型动力学行为演变规律；揭示了晶体元件表面微缺陷诱导激光损伤与损伤扩展行为规律及内在物理机制，为大口径KDP晶体元件表面微缺陷的有效抑制和修复提供了参数指导与理论依据。. 3、研究了KDP晶体加工表面典型微缺陷对激光损伤形貌演变的影响规律；结合KDP晶体表面复合微缺陷对激光损伤的影响规律，获得对激光损伤最为敏感的危险微缺陷类型和尺寸范围；创新性提出基于水溶剂介导的KDP晶体表面微缺陷修复方法，实现了晶体元件加工表面抗激光损伤性能的提升，为超光滑、低缺陷、高激光损伤阈值大口径功能晶体元件加工提供了重要技术支撑。. 本项目发表高水平学术论文16篇，其中SCI收录12篇，SCI影响因子总和44.813，单篇最高影响因子6.289；授权国家发明专利5项，受理5项，登记软件著作权3项；参加学术会议12人次，做口头报告交流7人次，出国联合培养1人次；入选中国科协“青年人才托举工程”计划1人、哈尔滨工业大学“青年拔尖人才”选聘计划1人，新聘博士生导师1人；指导（含协助指导）研究生13人，其中已毕业5人。