大口径非球面镜面形加工环带提取  

Extraction of Processing Annulus for Large Aspheric Mirror

作　　者：岳孝悌 李博[1,2] YUE Xiao-ti;LI Bo(National Astronomical Observatories/Nanjing Institute of Astronomical Optics&Technology,Chinese Academy of Sciences,Jiangsu Nanjing 210042,China;CAS Key Laboratory of Astronomical Optics&Technology,Nanjing Institute of Astronomical Optics&Technology,Jiangsu Nanjing 210042,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院国家天文台南京天文光学技术研究所,江苏南京210042 [2]中国科学院天文光学技术重点实验室(南京天文光学技术研究所),江苏南京210042 [3]中国科学院大学,北京100049

出　　处：《机械设计与制造》2024年第6期128-131,共4页Machinery Design & Manufacture

基　　金：国家自然科学基金面上项目—基于子口径二维传感器阵列的大型光学镜面面形测量技术研究(11873070)。

摘　　要：数控小工具是现代大口径非球面镜面研磨抛光加工中常用的一种计算机控制表面成形技术。在数控小工具加工实践中,当非球面面形精修到一定精度时,面形残差常常表现为环带形式,与相邻部分面形相差较大。为提高加工效率,可以针对这些环带使用小口径研抛工具进行单独修正,因此需要提取环带的位置和宽度。文章提出一种适用于大口径非球面镜的加工方法,通过将面形残差的高度信息映射到色彩空间成为图像,然后使用K-Means聚类分割图像,选择目标区间,得到待加工环带,此时可以计算出环带的宽度信息用于确定研抛工具的大小;另一方面,对环带提取骨架得到位置信息,从而生成数控机床可用的加工路径。该方法应用于1.6m望远镜非球面主镜面形的处理,从中提取了待加工环带信息用于指导面形加工,经多次加工与辅助平滑修抛迭代,主镜面形RMS值优于1/40波长。Numerical control gadget is a computer controlled optical surfacing(CCOS)technology commonly used in large aspheric mirror grinding and polishing nowadays.In engineering practice,when the surface shape is refined to a certain preci-sion,the residual error of the surface shape is often annular,which is quite different from the adjacent parts residual.In order to improve the machining efficiency,these annuluses can be individually corrected by small lapping tools.So the position and width of the zones need to be extracted.This thesis proposes a method suitable for large aspheric mirrors,which maps the height of the surface residual to the color space to become an image,then uses K-Means clustering to segment the image,selects the target interval,and obtains the annulus to be processed.At this time,the width information of the annulus can be calculated to determine the size of the lapping tool;On the other hand,the skeleton is extracted to get the position information of the target annulus,and then generate the processing path available for the machine tool.This method is applied to the aspheric primary mirror of a 1.6 meter telescope,and the annulus is extracted to guide the surface processing.The RMS value primary mirror shape is better than 1/40 wavelength after multiple machining and auxiliary smooth polishing iteration.

关 键 词：光学制造 镜面加工 计算机控制光学表面成形 图像处理 K-MEANS聚类 

分 类 号：TH16[机械工程—机械制造及自动化] TH743