基于相位测量偏折术的透明物体表面缺陷检测OA

At present,the traditional method is still used to control the quality of glass,lens and other transpar-ent objects in China,and the traditional visual evaluation method is inefficient.In order to realize automatic detection of surface defects of transparent objects,a transmission detection method based on PMD(Phase Measuring Deflectome-try)is proposed.The structure light fringe pattern is generated by PMD algorithm combined with the new phase shift pattern generation formula,and the fringe pattern is projected to the surface of the measured object using the transmis-sion system.The distorted fringe image after refraction of the measured object is collected by the camera,then the ab-solute phase diagrams are generated,and the defects are extracted by identifying the local distortion in the absolute phase diagram.Through analyzing the reason of false detection caused by periodic misalignment,a method of correc-ting absolute phase periodic misalignment is proposed.The new formula of phase shift pattern generation can also cor-rect periodic misalignment in advance,the combination of the two methods can improve the precision of phase unwrap-ping.A concave and convex lens with a focal length of 300 mm is taken as an example,the experimental results show that the proposed method can accurately extract the local distortion in the absolute phase diagram caused by surface defects with an accuracy of 0.1 mm.