Methods of detecting, classifying and quantifying defects in optical fiber end faces

A method of detecting, classifying and quantifying defects in a polished end face of an optical fiber, which is terminated in a connector component, said method comprising the steps of:

• acquiring images of an end face of a fiber, which has been terminated by a connector component, at an optimum focal position and at auxiliary positions behind and in front of said optimum focal position;
• generating a combined image of the terminated optical fiber end face which depicts any feature of interest which exist only in said terminated end face;
• isolating the end face of the optical fiber from the materials of the connector component which terminates the fiber to provide an image which depicts any features of interest which exist only in the end face of the optical fiber;
• identifying the features of interest which exist only in the end face of the optical fiber;
• and
• comparing quantitative data generated for each of the features of interest with acceptable values to determine the acceptability of the terminated optical fiber.

A method of detecting, classifying and quantifying defects a polished end face of a terminated optical fiber, said method comprising:

• generating a focus function of the end face of a ferrule in which the optical fiber is terminated;
• determining a location of the focus function where the focus of the terminated end face of the fiber is optimum;
• acquiring a primary image of the end face of the fiber at the optimum focus location;
• acquiring auxiliary images of the end face of the fiber behind and in front of the optimum focus location;
• storing the acquired primary and auxiliary images;
• providing a difference image which is the absolute value of the difference between the auxiliary images;
• thresholding the difference image;
• refining the difference image to discard portions of the difference image which result from minor variations between the two auxiliary images;
• smoothing the refined difference image to change binary lines in said refined difference image to lines having a generally gradually varying distribution;
• comparing pixels between the primary image and smoothed difference image to provide a combined image which depicts any scratches and cracks in the fiber end face;
• isolating the fiber portion of the primary image from materials of the ferrule to provide an image which depicts any feature of interest which exists only in the end face of the optical fiber;
• detecting and quantifying chips and pits in the isolated combined image;
• detecting and determining edge strength and direction of lines in said isolated combined image;
• identifying cracks which exist in the end face of the optical fiber and which appear in said isolated combined image;
• tracing edges in the isolated combined image and decomposing them into segments;
• matching line segments in the isolated combined image;
• and
• comparing quantitative data generated for each of the features of interest with acceptable values to determine the acceptability of the terminated optical fiber.