Patent ID: 6804007
Filing Date: 2004-10-12
Classification: G01N

Abstract:
An apparatus for performing optical measurements comprising:a meridional plane; a beam path in said meridional plane; a prism in said beam path, said prism including a sample surface extending in a plane orthogonal to said meridional plane; an intermittent metallic film associated with said sample surface, said intermittent metallic film forming a first pattern of reflective and transparent areas alternating along a direction parallel to said meridional plane and a second pattern of reflective and transparent areas alternating along said direction, wherein said reflective areas of said first pattern are alongside said transparent areas of said second pattern and said reflective areas of said second pattern are alongside said transparent areas of said first pattern, said first and second patterns being simultaneously illuminated by a beam of light on said beam path; and a light-sensitive detector arranged to receive light after reflection from said first pattern and from said second pattern.