针对强激光系统所需大口径非球面元件高精度、批量化的加工需求, 提出了一种气囊抛光技术与柔性沥青小工具抛光技术相结合的大口径非球面元件高效制造方法。采用气囊抛光技术进行非球面保形抛光和快速修正抛光, 实现磨削缺陷层快速去除以及低频误差快速修正。采用柔性沥青工具匀滑抛光技术, 在低频误差不被恶化的情况下, 控制元件中高频误差。在抛光过程中, 利用球面干涉仪搭建的自准直波前干涉检测系统和粗糙度仪对非球面元件进行全频段误差检测。基于上述加工与检测方法完成了430 mm×430 mm口径离轴非球面透镜样件实验加工, 实验结果为元件通光口径内透射波前PV=0.1λ, GRMS=5.7 nm/cm, PSD1 RMS=1.76 nm, PSD2 RMS=1 nm, Rq=0.61 nm, 并且中频段功率谱密度曲线均在要求的评判曲线之下。实验结果表明, 离轴非球面透镜样件全频段指标均达到了合格指标要求。所述制造方法也适用于其他类型大口径非球面光学元件的高精度加工。

In order to meet the requirement of high precision and mass manufacturing of large aspheric lens for high power laser device, a novel manufacturing method combining the bonnet polishing(BP) technology and flexible pitch polishing(FPP) technology was explored. Firstly, after the aspheric generating by ultra-precision grinding, the bonnet polishing technology, in keeping the aspherical surface shape, was used to quickly remove the grinding defect layer and improve the roughness of the element so that it can be directly tested by interferometer. Then, the bonnet polishing technology was used to quickly correct the low frequency error. Finally, the flexible pitch tool was adopted to smooth the middle and high frequency error. During the polishing process, the self-built wavefront detection system and the roughness instrument were used to detect the full frequency error of the aspheric element. Based on the above-mentioned fabrication and testing method, a 430 mm×430 mm off-axis apherical lens was manufactured, and the results indicate that, after polishing, the PV, GRMS, PSD1 RMS, PSD2 RMS and Rq are 0.1λ, 5.7 nm/cm, 1.76 nm, 1 nm and 0.6 nm, respectively. In addition, the power spectral density(PSD) curves are below the required evaluation curve. The experimental results show that the full frequency specifications of the off-axis aspheric lens meet the requirements. The manufacturing method is also applicable to the high-precision manufacturing of other types of large aspheric optical elements.