Beaucamp Anthony, Takizawa Ken, Han Yanjun, Zhu Wule
Opt Express. 2021 Sep 13;29(19):29802-29812. doi: 10.1364/OE.435945.
Pseudo-random paths are a useful tool to reduce mid-spatial frequency errors created in the processing of optical surfaces by sub-aperture polishing tools. Several types of patterns have been proposed, including hexagonal, square and circular, but prior literature has largely focused on flat and gently curved surfaces. Here, an extension of the circular-random path to strongly curved aspheric and freeform surfaces is proposed. The main feature of the algorithm is to cover the entire surface to be polished with a uniformly distributed tool path. Aspheric condenser lenses are then polished with a regular raster and circular-random path. Analysis of the optical performance shows that the random path can reduce the amplitude of mid-spatial frequency errors and relative intensity of satellite images. These features are particularly desirable in short wavelength applications, such as mirrors for EUV and X-ray.
伪随机路径是一种有用的工具，可减少子孔径抛光工具在光学表面加工过程中产生的中空间频率误差。已经提出了几种类型的图案，包括六边形、正方形和圆形，但先前的文献主要集中在平面和缓曲面。在此，提出了将圆形随机路径扩展到强弯曲非球面和自由曲面。该算法的主要特点是用均匀分布的刀具路径覆盖整个待抛光表面。然后用规则光栅和圆形随机路径对非球面聚光透镜进行抛光。光学性能分析表明，随机路径可以降低中空间频率误差的幅度和卫星图像的相对强度。这些特性在短波长应用中尤为可取，例如用于极紫外和X射线的反射镜。
