KDP晶体表面微缺陷修复的中高频误差抑制机理及其抗强激光损伤能力影响研究

The optical properties and service life of functional KDP crystal have been badly limited by the middle-high frequency errors on micro-defects repair surface by precision micro-milling .In order to suppress middle-high frequency errors on micro-defects repair surface and explore its influence on laser-induced damage resistance, this work will be carried out following four aspects.The influence law of the micro-repair surface characteristic (e.g., tool marks’ morphology,width and depth ratio,curvature change)on the laser-induced damage is to be investigated and the optimal threshold range of the amplitude and period of tool marks will be obtained. Meanwhile, the generation mechanism of the repaired surface morphology will be theoretically analyzed and the influence of machining condition (e.g.,geometric parameters of end-ball mill，repair technological parameters,the milling-tool wear) on the generation of the tool marks is to be studied. Moreover, the effect of dynamic characteristics of micro-repair system and crystalline anisotropy on the surface morphology would be discussed and the strategy to suppress the middle-high frequency errors on repair surface would also be explored. In addition, the influence of mitigation pit fabricated by micro milling on the optical properties and the ability of anti-laser damage would be evaluated comprehensively and the service performance curve of the repair crystal treated under strong laser irradiation would be obtained. This work may not only provide theoretical basis for improving both the laser transmission properties and service life of functional crystal components, but also offer parameter references for effective application of full scale crystal elements in inertial confinement fusion device. Therefore, making an in-depth study of this project has profound scientific significance and practical values.

KDP功能晶体表面微缺陷精密微铣削修复后存在的中高频误差严重地限制了自身的光学性能和使用寿命，课题针对微缺陷修复后的中高频误差控制及其对抗强激光损伤能力的影响问题，揭示微修复表面的刀纹形貌、宽深比、曲率变化等参数对其激光损伤的影响规律，获取微缺陷修复时允许的刀纹幅值与周期阈值范围；理论解析晶体修复表面轮廓形貌的生成机理，研究微球刀几何参数、修复工艺参数及刀具磨损等对曲面刀纹的影响规律；探究微修复系统动态特性及晶体各向异性等对加工表面中高频误差的影响规律与程度大小，开展修复表面中高频误差的抑制策略研究；综合评价微缺陷修复后的光学性能和抗强激光损伤能力，获取修复后晶体在强激光辐照下的服役性能曲线。该课题研究可为提高功能晶体元件的抗激光损伤阈值及延长其使用寿命提供理论基础，并为大口径晶体元件微缺陷修复后在核聚变装置中的实际应用提供参数依据。因此，对本课题进行深入研究有着重要的科学意义与实用价值。

KDP光学元件表面缺陷的微铣削修复表面形貌的中高频误差严重影响了其光学传输性能和服役寿命，进而大大限制了其在激光核聚变工程中的应用。针对晶体修复表面中高频误差的形成机理与抑制策略等科学问题，开展了微修复表面形貌特征对其激光诱导损伤机理，脆性材料塑性域去除及表面形成机理、修复表面中高频误差抑制策略研究及微修复表面对其抗激光损伤能力影响等方面的研究工作。主要成果如下：..1、建立了微缺陷修复后表面形貌在强激光辐照下的能量沉积和光场增强模型；解析了不同修复表面轮廓特征尺寸对其光学性能的影响规律，揭示了微修复形貌特征对激光束能流密度的影响机制；获得了微缺陷修复时允许的轮廓宽深比等阈值范围，为微缺陷点的有效修复提供理论基础。..2、揭示了温度效应对KDP脆性晶体塑性域去除和加工效率的影响规律；建立了该材料的塑性域切削的预测模型，揭示了修复表面微缺陷形成机制，获得了无缺陷修复表面的工艺参数的临界阈值；建立了微修复后表面形貌的仿真模型，确定了微铣削走刀步距是修复表面残留刀痕形貌特征的主要影响因素。..3、通过对现有微铣削修复系统升级改造，实现了其微缺陷自动监测与微铣削自动对刀功能，大幅提升了微缺陷单点修复效率；基于遗传算法获得了可实现高效效率高质量修复表面的微铣削工艺参数组合；提出了变步距修复策略实现了晶体修复表面中高频误差的有效抑制，为其光学性能的提升提供了理论支撑。..4. 理论研究了微修复残留刀痕形貌特征对抗激光损伤能力的影响规律；提出了“层铣-螺旋铣”多流程修复策略，获得了可实现微铣削修复最优参数组合，进行了大口径KDP晶体的微铣削修复后表面形貌的工程应用评估考核，修复成功率达95%以上，修复后晶体元件的平均激光损伤阈值可达到理想飞切表面激光损伤阈值的92.5%，接近晶体完美飞切表面阈值。..项目发表学术论文21篇，其中SCI收录16篇(含JCR1区10篇, IF>3.0共13篇)，IF因子总计42.914，单篇最高IF因子7.991；授权发明专利8项，受理6项；培养青年教师2人，博士生2人，硕士生5人。