基于条纹调制的透明物体表面缺陷检测方法  

Surface Defect Detection of Transparent Objects Based on Fringe Modulation

作　　者：许小波 段明辉 范鑫 竺长安[1] 金一[1] Xu Xiaobo;Duan Minghui;Fan Xin;Zhu Chang'an;Jin Yi(Department of Precision Machinery and Precision Instruments,University of Science and Technology of China,Hefei 230022,Anhui,China;Innovation Laboratory of Wuhu State-Owned Factory of Machining,University of Science and Technology of China,Hefei 230022,Anhui,China)

机构地区：[1]中国科学技术大学精密机械与精密仪器系,安徽合肥230022 [2]中国科学技术大学国营芜湖机械厂创新实验室,安徽合肥230022

出　　处：《光学学报》2023年第5期136-148,共13页Acta Optica Sinica

基　　金：安徽省科技重大专项(201903c08020002)。

摘　　要：针对透明物体后表面的寄生反射对单视角下表面缺陷光学检测的干扰问题,提出了基于条纹调制的透明物体表面缺陷检测方法,以消除后表面的寄生反射。为分析透明物体对入射光通量的影响,建立了基于条纹投影的透明物体光学成像模型。该模型揭示了透明物体双表面的形貌变化可以由双形貌参数来表征,且双参数共同构成余弦分布的平均强度和对比强度。提出了一种多频时域迭代策略以估计表面的双形貌参数,通过投影多频条纹序列到待测透明物体表面,并通过数值拟合投影条纹频率和调制强度之间的余弦分布,从振幅中提取表面的双形貌参数。实验结果证明所提出的检测方法能够在消除后表面寄生反射干扰的同时准确识别和定位出透明物体的表面缺陷。Objective Transparent objects have been broadly applied in optical lenses,liquid crystal displays,airplane windshields,etc.During production and transportation,various defects may appear on the surfaces of transparent components,such as pits,scratches,and scuffs.In general,surface defects change the surface topography and transform the optical characteristics,thereby seriously degrading the structural stability and functional optimality of transparent components.Consequently,surface defect detection is essential for the quality evaluation of transparent-component-based systems.However,in principle,the parasitic reflection caused by the refracted light reflected by the back surface will inevitably induce extra detection errors or even false detection.To eliminate the parasitic reflection,we propose a single-view surface defect detection method with digital fringe projection,and an optical detection system is built to prove the feasibility of the proposed method.Comparative experimental results verify that the proposed method can accurately classify and locate surface defects of transparent components under the interference of parasitic reflection.Methods In our work,we propose a single-view surface imaging method based on reflection to eliminate parasitic reflection with digital fringe projection.A fringe-projection-based optical model is first built under the effect of fringe modulation by analyzing the difference between incident luminous flux and captured luminous flux.The model indicates that the topography variation of double surfaces can be reflected by two topography parameters,which constitute the average and contrast amplitudes of a cosine distribution.Subsequently,a multi-frequency temporal iterative technique is presented to precisely fit the cosine distribution during practical single-view surface imaging.In the practical iterative process,multiple fringe patterns with different frequencies are projected onto a transparent object.Then,the cosine distribution composed of intensity and frequency values i

关 键 词：测量 缺陷检测 透明物体 条纹调制 结构光 

分 类 号：O435[机械工程—光学工程]