Patent ID: 7294825
Filing Date: 2007-11-13
Classification: G01J,G01N

Abstract:
1. An optical system, comprising: an illumination system for providing a coherent beam for illuminating a surface of interest through a first partially reflective surface; at least one reflector including said first partially reflective surface for sustaining multiple internal reflections in a resonant cavity formed at least partially between said at least one reflector and said surface of interest, and wherein an extraction partially-reflective one of said at least one reflector permits light to exit said resonant cavity; a detector for detecting an intensity of light leaving said cavity through said extraction surface; and a polarizing element located within a resonant path within said resonator, wherein said polarizing element alters a polarization of light between a forward path and a reverse path of a ray through said resonant cavity, such that light traveling along said forward path prior to entering said polarizing element is orthogonal to light leaving said polarizing element along said reverse path.