Pattern fault checking system for IC circuits, plasma image screens, or LCD plates

摘要

The checking system detects a fault in a regular pattern applied to the surface of a checked object (41) via a parallel light beam reflected from the surface of the object and directed through a filter (7) onto an image detector (8). An image processor (10) provides the difference between the detected image and a number of stored reference images, obtained by stepped displacement of the filter perpendicular to its optical axis, for detection of pattern faults. An Independent claim is included for a pattern fault checking method.