弹性域零损伤超光滑表面形成机理及关键工艺研究

Cracks and plastic scratches in surface/subsurface induced in brittle or plastic removal mode not only are the major factor for decreasing the laser induced damage threshold, but also increase the micro surface roughness on the optical workpiece. Material removal relying on mechanical action in traditional processing method cannot satisfy for the modern optical system demand for ultra-smooth surface. This project proposes an ultra-smooth fabrication method with material removal in elastic mode. The formation of ultra-smooth surface in this method is deeply researched. Chemisorption and separation mode between nanoparticles and optical surface is established to provide a theoretical basis for the selection of the optimal combination of nanoparticles. The best catalyst for improving interfacial chemical reaction is select to solve inefficient application processing bottlenecks. Surface evolutions for different type materials are studied to meet the requirements for initial processing requirements in a specific polishing time. Public rotation hydrodynamic polishing equipment is optimally designed to ensure the material removal efficiency under restraining the micro polishing marks. On-line polishing gap measurement can resolve problem of the gap changes due to changes in the tilt or curvature of the polishing gap. Defect-free atomic-level ultra-smooth can be easily obtained through theoretical innovation and process optimization.

脆性材料的脆性和塑性去除模式引起的裂纹、划痕等损伤不但会严重导致激光损伤阈值降低，还会影响增加光学元件表面的微观不平度。针对现代光学系统对超光滑表面的需求，克服目前依靠机械去除作用为主加工方法的不足，本项目提出了弹性域内的超光滑表面加工方法。对弹性域范围内超光滑表面的形成机理进行深入研究，建立纳米抛光颗粒与光学元件表表面的界面化学吸附和分离模型，为选择了最优的纳米抛光颗粒组合提供理论依据。通过添加最佳催化剂促进界面化学反应提高弹性域范围内材料去除效率，解决加工效率低下的应用瓶颈。通过研究表面形貌演变规律确定在特定时间完成加工对初始表面的要求。优化设计弹性域流体动压公自转抛光装置，在保证材料去除效率的前提下抑制加工表面的微细抛光纹路。抛光间隙在线测量结构解决了光学元件由于倾斜或曲率变化对抛光间隙的影响。通过理论创新和工艺优化，实现零损伤原子级超光滑表面的加工。

现代光学系统性能的不断提升对光学元件的表面质量提出了越来越高的要求，项目针对极紫外光刻物镜、高精度激光陀螺反射镜等重大需求开展了弹性域零损伤超光滑表面关键加工工艺研究。项目对弹性域化学辅助加工超光滑表面形成的内在动力研究，从原子层面分析了在相同工艺参数光学元件表面不同位置材料去除速率的差异。探索研究了溶液PH值、抛光颗粒粒径以及种类、抛光轮表面结构特性以及加工装置的精度等因素对材料去除速率的影响。基于微细抛光纹路的产生机理在第一代自转弹性域流体动压超光滑加工的装置的基础上，创新性提出了公自转（双转）弹性域流体动压抛光系统(外在动力)，对其工艺参数的影响进行了仿真和实验分析，获得的最优的工艺组合参数。在一块传统抛光的石英玻璃上进行应用实验，加工后表面损伤完全被去除，表面粗糙度Rms达到0.0789nm，已经达到原子级超光滑水平，验证了该工艺优异的加工性能已达到了项目预期研究的指标。