Arthur J Schmidt

US Patent:

51794195, Jan 12, 1993

Filed:

Nov 22, 1991

Appl. No.:

7/796204

Inventors:

John M. Palmquist - Lilburn GA
Arthur T. Schmidt - Emmaus PA
Behzad Shahraray - Freehold NJ

Assignee:

AT&T Bell Laboratories - Murray Hill NJ

International Classification:

G01N 2184

US Classification:

356 731

Abstract:

Methods are provided to detect, classify and quantify defects such as chips, pits, scratches and cracks in a polished end surface (31) of optical fiber and specifically in an end face of an optical fiber terminated by a ferrule (34). Images of the end face are acquired at each of three focal positions which collectively include all the features of interest. Information from these images is combined into a single image which is processed further. Discrepancies between the images are used to discriminate between cracks and scratches. Morphological processing is used to segment the fiber from its ferrule and a Hough transform is used to estimate the center and radius of the optical fiber, which facilitates the isolation of the fiber. Chips and pits in the fiber end face are detected and quantified by thresholding and morphological processing of the isolated fiber. Edge detection is used to detect edge segments resulting from scratches and cracks.