Research for On-Line Measurement of Optical Fiber Diameter Based on Machine Vision

Special optical fiber (D-type optical fiber) geometry parameter directly effect its sensing characteristics, it is very important to measure optical fiber diameter. But the present methods of measuring optical fiber diameter have some disadvantages, such as demanding high level environment and not real-time on-line measuring. This paper describes a method by applying machine vision technology to measure optical fiber diameter in real-time on-line. Firstly, Automatic Focusing System can collect clear fiber image by applying CMOS camera. Secondly, image edge was detected by using edge detector. And the precise location of image was detected by sub-pixel location technology based on gray moments. Lastly, optical fiber diameter is calculated by applying the two priority methods-least beeline fitting method. Experimental results show that the accuracy of measuring fiber diameter system is 1 mu m, and meet the requirements of real-time on-line measuring.