为解决强激光系统中大口径光学元件抛光面形精度收敛困难的问题,提出了一种基于压力补偿原理的抛光面形快速收敛技术。利用独特的抛光垫修整技术, 将抛光垫表面修整成特定形状, 使工件与抛光垫的接触面产生不均匀的压力分布, 并结合精确的抛光转速控制, 以加快工件面形精度的收敛速度。实验结果表明, 将抛光垫修整成微凸面形,可以有效避免抛光中元件过早塌边问题, 能将大口径平面元件的初抛时间从数天缩短到6 h以内, 元件面形精度提高到1个波长左右。

A technique based on contact pressure compensation is presented in order to quicken the convergence of surface of large-aperture optical components during the pre-polishing processes. The pad surface is conditioned to a specific shape using an innovative pad conditioning technique, and thus the non-uniform distribution of contact pressure will be engendered at the interface between workpiece and polishing pad. Combining with accurate polishing speed controlling, the uneven pressure distribution will make workpiece’s surface converge to the desired shape more quickly, which was verified by our experiments. The experiments also indicate that conditioning pad surface to convex can avoid excessive removal of workpiece edge region during the early stages of polishing process. Compared to the traditional single spindle polishing, the aforementioned technique can shorten the entire polishing process from several days to within 6 hours and in the meantime improve the surface precision to about one wavelength.