Abstract

A high speed optical inspection system for determining the conformity of a sample printed circuit pattern with a master circuit pattern by digitized template matching techniques including illuminating the sample pattern by high intensity lamps and filtering the incident light and reflected light, such as by cross polarization of such light, for contrasting. The contrasted pattern is viewed by an electronic video camera including a charge coupled multi-element pixel array which senses reflected points of light on the illuminated sample pattern for sending electrical signals to a micro-engine for forming a digitized image of the sample pattern. The digitized image is compared with a digitized image of the master pattern in which the digitized image of the master pattern includes an inner digitized pattern template and an outer digitized pattern template which define the inner and outer tolerances to be applied to the sample circuit pattern to determine acceptable or non-acceptable conformity of the sample pattern with the master pattern. The location of nonconforming portions of the sample pattern are identified and displayed and enlarged for inspection.