Rotating-compensator ellipsometer

Abstract

The present invention relates to a rotating-compensator ellipsometer, comprising the following elements in the light path in this order according to the propagation direction of light: a light source (1); a polarizer (2); a compensator (3a), arranged in a supporting and rotating assembly (4) and comprising an optical axis (O); an analyzer (5); a detector (6), wherein the rotating-compensator ellipsometer further comprises a control unit (7) that is operably connected to at least one of the above elements, wherein the compensator (3a) is a concave prism, having at least five planar surfaces that are perpendicular to a median plane of the prism, said median plane including the optical axis (O), wherein a first planar surface (301) of the prism is perpendicular to the optical axis (O); a second planar surface (302) of the prism forms an angle of 90°-β with the optical axis (O); a third planar surface (303) of the prism is parallel with the optical axis (O), is perpendicular to the first planar surface (301) and is provided with a reflective coating; a fourth planar surface (304) of the prism forms an angle of 90°-β with the optical axis (O); a fifth planar surface (305) of the prism is parallel with the first planar surface (301) and is perpendicular to the third planar surface (303), and wherein 45°<β<65°.

Dependencies are inferred from the claim text.