Patent ID: 6590654
Filing Date: 2003-07-08
Classification: G01B,G02B

Abstract:
A method for enhancing the proportion of light detected from an illuminated surface emanating from a diffuse lobe with respect to light specularly reflected by the surface, the method comprising:a. receiving an incident beam of light having a direction of predominant polarization; b. directing the beam through a wedge module having a polarization axis in such a manner as to substantially align the direction of predominant polarization of the beam with the polarization axis of the wedge module; the wedge module including: i. a first optically anisotropic wedge; ii. a second optically anisotropic wedge inclined relative to the first optically anisotropic wedge; and iii. an optical compensation plate having an interface parallel to a face of the first optically anisotropic wedge and a face of the second optically anisotropic wedge so as to compensate any change in optical path of light through the wedge module; and c. detecting light reflected from the surface polarized in a direction perpendicular to the direction of predominant polarization of the incident beam.