Patent ID: 6407809
Filing Date: 2002-06-18
Classification: G01N

Abstract:
An optical inspection system for detecting defects on a substantially flat workpiece having an axis of symmetry, the system comprising a stage supporting said workpiece in an inspection plane, and a scanning apparatus accommodated above said workpiece, wherein:(a) said stage is mounted for rotation in a plane parallel to said inspection plane; (b) said scanning apparatus is constructed to define an inspection area covering substantially a half of the workpiece, thereby enabling half-by-half inspection of the workpiece, and comprises: an illumination assembly producing a plurality of incident radiation components, each component illuminating a corresponding one of a plurality of regions of the workpiece within a strip illuminated by said plurality of incident radiation components, the strip extending parallel to the axis of symmetry of the workpiece between two opposite sides thereof; a plurality of optical assemblies accommodated above said workpiece, each optical assembly directing a corresponding one of a plurality of radiation components returned from the corresponding illuminated region away from the workpiece, wherein the optical assemblies are aligned along said axis of symmetry in a spaced-apart parallel relationship, and are mounted for reciprocating movement within a plane parallel to the inspection area covering substantially half of the workpiece; (c) a plurality of area sensors are arranged in a predetermined manner, each area sensor being associated with a corresponding one of the optical assemblies for receiving the component of the returned radiation and generating data representative thereof; (d) a first drive mechanism is coupled to said optical assemblies for driving said reciprocating movement thereof; and (e) a second drive mechanism is coupled to said stage for driving said rotation thereof.