精密光学元件表面洁净度成像检测系统

Surface Cleanliness Level Detection by Imaging Method for Precision Optical Elements

为解决精密光学元件表面洁净度检测面临疵病干扰及测量精度不理想的问题,提出了基于机器视觉方法的图像检测系统,设计了适用于多种尺寸待检测元件的活动夹具和三维电控平台.利用Canny边缘检测算子分割出被检对象边缘,用凸壳的方法得到被检对象的封闭区域,采用关联向量机法,对待检测对象封闭区域的几何空间、灰度空间和变换域空间参数构成的待检测向量进行分析,识别出固体颗粒残留物和非固体颗粒残留物,最终得到精密光学元件表面的洁净度等级.

To avoid the disturbance of flaws and improve the accuracy in measurement of surface cleanliness-level of precise optical elements, an image detection system based on machine vision method was proposed, in which a set of movable clamping fixtures for optical elements of various sizes and a three-dimensional electronic control platform were designed. In image processing, Canny edge detection operator was used to extract image edges, and the convex hull method was employed to obtain enclosed areas for the detected object. Then, a test vector was composed by the characteristic parameters extracted from the geometric space, gray-level space and spectrum domain of the enclosed area, and analyzed by relevance vector machine （RVM） method to recognize particle and non-particle contaminants on surface. Based on the results, the cleanliness-level grade of the precision optical elements can be obtained.