Patent ID: 6108078
Filing Date: 2000-08-22
Classification: G01N

Abstract:
A method of surface inspection for inspecting a foreign matter on the surface of an object of inspection by throwing an inspecting light beam on the surface of the object of inspection through an optical system and sensing a scattered light beam reflected from the surface of the object of inspection while the object of inspection and the optical system are provided with relative displacement, said method of surface inspection comprising the steps of:scanning the inspecting light beam on the surface of the object of inspection through the optical system;sensing a point where the scattered light signal by a foreign matter exceeds a threshold signal or threshold signal level while the inspecting light beam is scanned in a predetermined direction as a start point;sensing a point where the foreign-matter scattered signal thereafter falls below the threshold signal or threshold signal level as an end point;sensing a point where the foreign-matter scattered signal was at its maximum level between the start point and the end point as a peak; andevaluating sensed data to determine existence of foreign matter on the surface of the object of inspection.