OUT-OF-PATTERN COATING DEFECT DETECTION SYSTEM

Out-of-Pattern Coating Defect Detection System A defect detection system (10) of this invention applies one or more orthogonally-aligned light beams (22 and 24) to a coated fiber (32) such that the light passes through the entire width of both the fiber (32) and its applied coating (31). As the light passes through a fiber (32) and coating (31) of good quality, a particular pattern, with a predictable intensity level, is produced by the forward scattered portions of the light beams directed through the coated fiber (32). In accordance with the present invention, the intensity of the forward scattered patterns is continuously monitored by a series of photodiodes (44, 45, 46 and 47) each located adjacent to the expected forward scatter pattern. Various defects in the coating cause the path of the light passing through the coated fiber (32) to be altered, thereby directing some of the forward scattered light outside of the normally expected pattern and into the detection area of the photodiodes (44, 45, 46 and 47). Such distortion to the forward scatter patterns causes the light intensity level measured at the photodiodes (44, 45, 46 and 47) to increase. Therefore, by continuously monitoring the light intensity level adjacent to the forward scatter patterns for an increase of light relative to the light intensity expected, the present invention provides reliable and accurate means for detecting, temporally short defects, such as air bubbles, which may be present within the coating (31) of a fiber (32).