Patent ID: 6100971
Filing Date: 2000-08-08
Classification: G01N

Abstract:
An apparatus for inspecting a planar surface of an object using (A-beam) having a first path and a second laser beam (B-beam) having a second path, comprising:means for generating a first laser beam (A-beam) having a first path;a first telecentric lens assembly;a first polygon scanner in the first path to direct the A-beam through the first telecentric lens assembly to scan the A-beam across the first planar surface of the object at a substantially constant angle which deviates from perpendicular in one plane by an angle which causes a portion of the A-beam to form a reflected beam (A/R-beam) passing back through the telecentric lens assembly and being reflected off of the first polygon scanner along a second path;a first aperture mask in the second path which allows the A/R-beam to pass while blocking a portion of the near field scattered light; anda first light detector arranged in the second path producing an A-analog signal proportional to the intensity of the A/R-beam.