The Research Of A Coaxiality Measuring System Of Ceramic Ferrule For Optical Fiber Connector

Ceramic ferrule is the key element of the optical fiber connector, has higher manufacture precision, it's coaxiality error need to be not larger than 0.5μm. Accordingly, it's testing system must have higher measurement precision. At present, the most coaxiality testing systems used in the home and abroad manufacture of the ceramic ferrule are microscopical magnifier measuring system, optical interference microscopical measuring system and sensor measuring system. The technology and equipments applied in these systems all are from abroad. This thesis based the fact of current home manufacture and our laboratory's production research of the ceramic ferrule, designs a CCD microscopical magnifier measuring system, discusses the measuring principle of the system in detail, devises the corresponding hardware and software system. The hardware structure is mainly put up of the microscopical magnifier, a black and white CCD vidicon, and computer. The software system includes the image processing and result-computing program. Image processing and result-computing algorithm are the sticking points of the system. By the research and tests, this thesis applies the best threshold and dynamic threshold methods to divide the CCD images, pick-up the edge of ceramic ferrules, using the adjacent-field average method to get rid of noise. Based the theory of computation geometry, the result-computing program applies the most circumcirle and least inscribed circle methods to compute the envelope-circles of the ceramic ferrule's outer circle and inner hole, and calculate the coaxiality according to the envelope-circles. Aimed at the measuring system, this thesis makes researches on two measuring methods to achieve the ceramic ferrule's coaxiality. The method one bases on the theory of analytic geometry, not on image-processing method to divide the ceramic ferrules CCD images, measure and compute the coaxiality directly; the method two applies image-processing to program to compute the coaxiality. Experiment shows that :compared with the method one, the method two can be applied to measure coaxiality of the rough ceramic ferrules, and the CCD microscopical magnifier measuring system designed by this thesis can be applied to measure coaxiality of the ceramic ferrules.