基于外置光阑针孔相机的高精度偏折测量技术  

High Precision Deflectometric Measurement Based on Pinhole Camera with an External Stop

作　　者：叶璐 张祥朝[1] 王军华[1] 徐敏[1] 郑列华[2] YE Lu;ZHANG Xiangchao;WANG Junhua;XU Min;ZHENG Liehua(Shanghai Engineering Research Center of Ultra-precision Optical Manufacturing,Fudan University,Shanghai 200438,China;Shanghai Institute of Technical Physics,Chinese Academy of Sciences,Shanghai 200083,China)

机构地区：[1]复旦大学上海超精密光学制造工程中心,上海200438 [2]中国科学院上海技术物理研究所,上海200083

出　　处：《光子学报》2023年第12期126-137,共12页Acta Photonica Sinica

基　　金：国家自然科学基金(No.51875107);江苏省重点研究发展计划(No.BE2021035)。

摘　　要：设计了一种外置光阑的针孔相机镜头,可免去传统方法复杂的相机标定过程,采用影像仪和三坐标测量机实现测量系统各元件空间位置的几何标定,并依靠相移算法实现屏幕与相机像素的精准匹配。实验结果表明,本文提出的偏折测量结果与干涉仪测试结果偏差优于20 nm RMS,可满足光学镜面加工研磨阶段到抛光阶段的过渡测量需求,为光学加工车间提供了可靠、经济、高效的面型评估,具有广泛的应用前景。With the increasing requirements of complex shapes and high resolution of optical systems,the precision measurement of optical mirrors is of great challenge.In the grinding stage,a coordinate measurement machine is generally adopted,which is realized by contact measurement,but it suffers from long measurement time and low accuracy.In the polishing stage,laser interferometry is generally adopted.Due to its limited measurement range,a specially designed compensator is required for measuring an aspheric surface.Usually,it is impossible to achieve full aperture interferometric measurement of a surface with deep asphericity,especially when it has a large form deviation.Fortunately,the Phase Measuring Deflectometry(PMD)can overcome this problem,which has the advantages of fast measurement speed,low cost,high dynamic range and high flexibility.However,it also has limitations.First,the accuracy of system calibration directly affects the measurement accuracy.The camera is usually regarded as a pinhole camera.The internal and external parameters of the camera are obtained through complicated calibration.Images of a calibration plate are taken at different positions and poses,and the coordinates of each camera pixel are obtained accordingly.The traditional calibration method has a complicated process and it is greatly affected by the quality of the calibration plate.Moreover,camera calibration and geometric calibration are generally obtained separately,and there will be error coupling and propagation in the conversion of coordinate systems.Second,most industrial camera lenses adopt a symmetrical structure in order to eliminate aberrations.The aperture stop is located in the middle of the lens group.In order to directly specify the position of the camera stop,an external stop can be set at the front of the lens,which will greatly affect the camera's field angle and bring inconvenience to measurement.Third,a theoretical model is needed for the surface under test to estimate the position of measured points to solve the height

关 键 词：偏折术 离轴抛物面 相机标定 几何标定 面型重构 

分 类 号：TH74[机械工程—光学工程]