Patent ID: 7920264

Claim:
A spectroscopic ellipsometer or polarimeter system comprising: a polarization state generator for providing a spectroscopic beam of electromagnetic radiation in a known state of polarization; an element with an upward facing surface and left and right sides which project substantially vertically downward from left and right sides of said upward facing surface, respectively, and a downward facing surface which centrally comprises a cut-out portion comprising upward to the right and upward to the left directed sides surfaces which are mirror images of one another taken about a central vertical plane; and a polarization state detector for analyzing a spectroscopic beam of electromagnetic radiation; said spectroscopic ellipsometer or polarimeter system being configured such that a beam of spectroscopic electromagnetic radiation provided by said polarization state generator is caused to enter said left or right side which projects substantially vertically downward from left and right sides of said upward facing surface, respectively, along a locus which is substantially normal thereto, impinge on said upward to the left or upward to the right directed surfaces of said cut-out in said downward facing surface, respectively, reflect internally from said upward facing surface then reflect from said upward to the right or upward to the left directed surfaces of said cut-out in said downward facing surface, respectively, then pass through said right or left side which projects substantially vertically downward from right and left sides which project substantially vertically downward from right and left sides of said upward facing surface, respectively, along a locus which is substantially normal thereto, and proceed into said polarization state detector.