蓝宝石光学腔体选择性激光刻蚀技术的研究

Because of the excellent material characteristics and compact optical texture, sapphire optical cavity has the incomparable advantages in the fields of biochemical analysis, life science, and bio-sensing and so on. However, the existing sapphire optical cavities have the problems of low machining precision, poor surface quality, and low machining efficiency. Take the advantage of high etching ratio between the modified and unmodified material in sapphire, this project improves the machining efficiency by increasing the laser induced modified region and improving the etching rate. Variable multiple-focuses femtosecond laser scanning technology is proposed. The project aims to study the efficiency of temperature to etching rat of sapphire. Ultrasonic chemical etch technology combined with ultrasonic abrasive polishing technology are proposed to obtain the ultra-smooth cavity surface. The processing time is further shorted by combining the high temperature chemical etch technology and ultrasonic chemical etch technology. The error model is given to compensate the machining error of sapphire cavity in laser scanning trajectory. The project will enable the high performance optical cavity elements to implement engineering fabrication and application, provide theoretical foundation and technical support for fabrication of complex precision optical elements and the development of some optical system.

蓝宝石光学腔体因其优异的材料特性和紧凑的光学结构，在生化分析、生命科学和生物传感等方面具有不可替代的优势。针对目前加工精度难以保证、表面质量差、加工效率不高等问题，本项目利用飞秒激光照射后蓝宝石相变区和非相变区存在的高腐蚀速率比，分别从增大激光诱导相变区域和提高相变区域腐蚀速率方面来提高加工效率，提出可变式多焦点激光扫描技术；研究温度对激光照射后蓝宝石样件的腐蚀规律；研究超声化学腐蚀和超声磨粒抛光技术组合方案来获得超光滑蓝宝石腔体内表面；并提出高温腐蚀和超声腐蚀相结合的新方法，来减少工艺过程；建立误差分析和补偿模型，研究具有误差补偿效果的激光扫描路径。本项目的研究成果将促进高性能腔体类光学元件的工程化制造和应用，为复杂精密光学零件的加工和相关光学系统的研制提供理论指导和技术支持。

研制用于选择性激光刻蚀和超声辅助抛光的加工装置，并进行性能测试，包括：焦点参数可调节的飞秒激光聚焦扫描装置；带动蓝宝石工件运动的三自由度运动平台两套，分别采用音圈电机和压电陶瓷驱动柔性铰链结构实现，可实现毫米级和十微米级运动行程；研制了用于超声辅助抛光的超声椭圆振动装置；协助搭建了飞秒激光加工系统。. 对选择性激光刻蚀技术进行了分析与优化，详细分析了激光加工参数（光斑能量、扫描速度、脉冲时间等）对加工质量和去除效率的影响；提出了超声辅助腐蚀技术，有助于提高材料去除效率并提高表面质量。. 提出了超声水合抛光方法，包括：对蓝宝石进行亲水处理，然后采用高温高压水蒸气对蓝宝石被加工表面进行水合反应，水合氧化铝会大大降低硬度；然后采用超声磨粒抛光对蓝宝石进行超光滑处理。本项目研究了亲水处理和水合反应对蓝宝石硬度的影响规律；采用Flunet仿真分析了抛光液速度、被抛光表面的压强、抛光磨粒粒径大小、磨粒浓度以及抛光时间等对抛光质量和抛光效率的影响规律。