Patent ID: 8736838

Claim:
A terahertz ellipsometer or polarimeter system sequentially comprising: a source (BWO) of terahertz electromagnetic radiation; a first rotatable polarizer (WGP 1 ); a stage (STG) for supporting a sample (S); a second rotatable polarizer (WGP 2 ); a detector (DET) of terahertz electromagnetic radiation; said terahertz ellipsometer or polarimeter system further comprising a first element (RE 1 ) and second element (RE 2 ) between said source and detector of electromagnetic radiation, said first (RE 1 ) and second (RE 2 ) elements being capable of rotating continuously in use; said terahertz ellipsometer or polarimeter system being characterized by said first element (RE 1 ) and second element RE 2 which are capable of rotating continuously in use being on the source, and detector of electromagnetic radiation sides of said stage (STG) and sample, respectively; and wherein said source and detector of electromagnetic radiation are a backward wave oscillator (BWO) and a Golay cell (DET), respectively; and wherein said first (WGP 1 ) and second (WGP 2 ) rotatable polarizers each comprise a wire grid; such that in use said backward wave oscillator (BWO) directs a beam (BI) of terahertz frequency electromagnetic radiation of a fundamental frequency to pass through said first rotatable polarizer comprising a wire grid (WGP 1 ), then through said first element (RE 1 ) which is capable of rotating continuously in use, then reflect from a sample (S) placed on said stage (STG) for supporting a sample, then pass through said second element (RE 2 ) which is capable of rotating continuously in use, then pass through said second rotatable polarizer comprising a wire grid (WGP 2 ), and, as output beam (BO) enter said Golay cell detector (DET).