Study On The Measuring Of Quality For Grin Lens End On The Basis Of Image Processing

GRIN lens is the basic component of the passive device for optical communication.With the development of optical communication technology,more and more GRIN lenses are in demand,accompanied by the gradually highlighted problem of production quality test of lens,especially the lens end face.Relying on the experience of quality inspectors,the quality inspectors are strictly required to conduct the test manually with optical equipment by the traditional quality testing method with low efficiency and large probability of false inspection and missing inspection.Therefore,it is of practical value to develop an automatic testing system for the end face quality of the GRIN lens and important practical significance for ensuring the quality of the product and improving the production efficiency.In this paper,the method of testing the defect feature of the end face of a small-sized GRIN lens as the research object is deeply studied.The main contents are as follows:1)According to the structural characteristics of the GRIN lens,a special tool suitable for the testing of the end face of the GRIN lens is designed as a part of the end image acquisition system besides the CCD industrial camera,the telecentric lens and the light source.2)According to the acquired images,the image processing method is studied and the defect features are extracted.The image preprocessing is conducted to reduce the image noise and enhance its effect;the regional edge fitting is achieved based on the optimum circumscribed circle method to obtain the ideal edge of the end contour;the image equalization processing is achieved by reducing halo based on Retinex algorithm;and the defect features are extracted by the Otsu threshold segmentation algorithm.The feature extraction experiments are carried out on the three main defects(broken edge,needle damage and scratch)on the end face.3)The software is developed by the MATLAB GUI,and the man-machine dialogue during the lens end image processing process is realized.Through the obtained the end face defect feature data of the GRIN lens,such as defect size,defect area,number of defects and defect position,and the product quality evaluation parameters are given combined with the quality evaluation standard of the GRIN lens.The experiment shows that the proposed method can be applied to the end face quality test of GRIN lens with high accuracy.