光学元件表面缺陷的显微散射暗场成像及数字化评价系统

根据国际ISO10110-7的表面缺陷标准及惯性约束聚变(ICF)工程标准,提出了一种新颖的光学元件表面缺陷的光学显微散射成像及数字化评价系统,多束光纤冷光源呈环状分布并以一定角度斜入射到数毫米视场的被检表面,形成适合数字图像二值化处理的暗背景上的亮疵病图像。对X,Y两方向进行子孔径图像扫描成像,利用模板匹配原理对获得的子孔径图像进行拼接得到全孔径表面疵病图像信息。基于数学形态学建立了可用于大口径表面检测扫描的图像处理的模式识别软件体系,并应用二元光学制作了标准对比板,以获得疵病正确的评价依据。最终利用该变倍光学显微镜散射成像系统得到能分辨微米量级表面疵病的图像,其单个子孔径物方视场约为3 mm,对X,Y两方向进行5×5子孔径图像扫描成像,并给出了与标准比对的定量数据结果。实验结果表明,本系统完全可以实现光学元件表面缺陷的数字化评价。

Microscopic Dark-Field Scattering Imaging and Digitalization Evaluation System of Defects on Optical Devices Precision Surface

A novel measurement and digitalization system of surface defects on optical devices——microscopic scattering imaging is put forward based on international ISO10110-7 surface defects standard and inertial cofinement fusion engineering standard. The multi-beam optical fiber cold light source illuminates the detected surface whose view field is about several millimeters in a special angle. The image of bright defects in black background is formed that is suitable for digital image binary processing. The sub-aperture is detected and imaged using the X-Y scanning system. The information of full surface defects is obtained by stitching the sub-aperture images with the template matching principle. A complete digital evaluation software system of large aperture surface imperfections measurement based on morphology is presented. A group of standard reticules are fabricated by binary optics to scale defects. The resolution of the optical system of defects-microscopic scattering imaging is better than sub-micrometer and the view field of a sub-aperture is about 3 mm. An image array of 5×5 sub-aperture is obtained by two-dimensional scanning system. The full image of surface defects is reconstructed, and the quantitive comparison with the standard value is also presented. The experimental results show that the system is valid for measuring defects of precision surfaces.