Importance

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Abstract

A system and method of optically inspecting a structure on a surface of a production object which is supported on a moving inspection platform. The method reliably traces structure edges and stores structure and structure island characteristics. The system uses a camera and a light or energy source to sharply delineate the structure edges. A sequence of images of the object and the structure are captured, and the structure is detected in each image. The structure is then symbolically decomposed into primitives, and a histogram is produced for each image identifying the slope and length of each edge of the structure. The histograms are compared in each image, and are aligned to eliminate differences due to wobble of the inspection platform or differences in magnification. A production structure grammar is then produced from the aligned images. The production structure grammar is compared to a reference structure grammar generated from a defect-free object. Differences in the two grammars, if any, are used to identify missing, misaligned, or misoriented structures on the production object, and to detect foreign objects and other defects.

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First Claim