System and method for inspecting an object using structured illumination
AssigneeCognex Corporation
InventorGilbert W. J. Chiang
Life of this patent
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Abstract
A system and method for inspecting the surface of an object using structured illumination is provided. A structured illuminator having a diffuser assembly, grid pattern and beam splitter projects the grid pattern on the surface. The projected grid pattern is viewed by a camera, which is aligned on-axis with the projection and substantially perpendicular to the surface. The structured grid pattern makes more-pronounced any surface defects. The projected image, defined by the grid pattern and received by the camera, is analyzed using a two-step technique that, first locates and scores the individual features of the grid, and then compares the locations of the actual features as viewed, to ideal locations for such features.
Claims13
A system for inspecting a surface comprising:
- a structured illuminator that projects a predetermined grid pattern having a plurality of grid features on the surface;
- a camera arranged to view the arid pattern;
- a machine vision processor constructed and arranged to compare a score of each of the grid features and a location of each of the grid features against predetermined limitations to thereby determine whether the grid features exceed the limitations;
- and
- wherein the machine vision processor is further constructed and arranged to (a) determine a respective score for each of the features based upon predetermined scoring parameters;
- (b) determine actual locations of each of the grid features viewed;
- (c) construct ideal locations for ideal grid features, (d) compare each score against a desired tolerance;
- and (e) compare each of the actual locations against the ideal grid features.
A method for inspecting a surface comprising:
- projecting a predetermined arid pattern having a plurality of grid features on the surface;
- viewing the grid pattern with a camera arranged on a viewing axis with respect to the surface;
- comparing, with a machine vision processor, a score of each of the grid features and a location of each of the grid features against predetermined limitations to thereby determining whether the grid features exceed the limitations;
- and
- wherein the step of comparing the score of each of the grid features further includes (a) determining a respective score for each of the features based upon predetermined scoring parameters;
- (b) determining actual locations of each of the grid features viewed;
- (c) constructing ideal locations for ideal grid features;
- (d) comparing each score against a desired tolerance and (e) comparing each of the actual locations against the ideal grid features.
Dependencies are inferred from the claim text.