Patent ID: 7477371
Filing Date: 2009-01-13
Classification: G01N

Abstract:
1. An optical system for detecting contaminants and defects of a test surface comprising: a device providing a polarized light beam along a path at an oblique angle to the test surface, producing an illuminated spot thereon; a first and a second detector; a first collector having an optical axis substantially along a line perpendicular to the test surface, said first collector collecting light from the polarized light beam scattered by the illuminated spot of the surface and conveying the collected light to the first detector, causing the first detector to provide a single output in response to the light collected by the first collector; and a second collector collecting light from the polarized light beam scattered by the illuminated spot of the surface and conveying the collected light to the second detector, causing the second collector to provide a single output in response to the light collected by the second collector, wherein the first and second collectors collect light scattered by the surface within different ranges of collection angles from the line.