Patent ID: 7283227
Filing Date: 2007-10-16
Classification: G01B,G01N

Abstract:
1. An oblique illumination inspection system, comprising: a primary light source that emits a first light beam which passes through a portion of a glass sheet; a secondary light source that emits a second light beam which passes through the portion of the glass sheet; a camera having an optic axis which is offset from said primary light source and said secondary light source that generates an image of the illuminated portion of the glass sheet where the image is used to detect, characterize and classify a defect of the glass sheet; wherein said primary light source is responsible for image contrast enhancement of the defect because said primary light source provides a relatively balanced directional gradient illumination across the field of view of said camera which happens because the primary light source is located on one side of the optic axis of said camera and because the primary light source is located relatively close to the optic axis of said camera; and wherein said secondary light source is responsible for image enhancement of edges of the defect because said secondary light source provides a relatively balanced directional gradient illumination across the field of view of said camera which happens because the secondary light source is located on another side of the optic axis of said camera and because the secondary light source is located relatively far from the optic axis of said camera.