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US 9,121,757 B2Granted
Terahertz ellipsometer system, and method of use
AssigneeJ.A. Woollam Co., Inc.
InventorCraig M. Herzinger
Life of this patent
Estimating the term…
Abstract
A terahertz ellipsometer, the basic preferred embodiment being a sequential system having a backward wave oscillator (BWO); a first rotatable polarizer that includes a wire grid (WGP1); a rotating polarizer that includes a wire grid (RWGP); a stage (STG) for supporting a sample (S); a rotating retarder (RRET) comprising first (RP), second (RM1), third (RM2) and fourth (RM3) elements; a second rotatable polarizer that includes a wire grid (WGP2); and a Golay cell detector (DET).
Claims16
A method of determining physical and optical properties of samples using a terahertz frequency electromagnetic radiation, comprising the steps of:
- a) providing a terahertz ellipsometer or polarimeter system sequentially system comprising:
- a backward wave oscillator (BWO);
- a rotatable polarizer comprising a wire grid (WGP1);
- a rotating polarizer comprising a wire grid (RWGP);
- a stage (STG) for supporting a sample (S);
- a rotating retarder (RRET) comprising, in any functional order, first (RP), second (RM1), third (RM2) and fourth (RM3) reflective elements from each of which, in use, an electromagnetic beam reflects once, said first reflective element (RP) being prism (RP) which receives a beam through a first side thereof and exits a reflected beam through a third side thereof, said reflection being from a second side thereof oriented at prism forming angles to said first and third sides;
- said elements (RP) (RM1) (RM2) (RM3) being oriented with respect to one another such that the locus of the beam reflecting from the second side of said prism approaches said second reflective side thereof at an angle equal to or greater than that required to achieve total internal reflection within said prism (RP), and such that the locus of beam reflected from the fourth element in the sequence of elements is substantially colinear and without deviation or displacement from the locus of the beam received by the first element in said sequence of elements;
- a second rotatable polarizer comprising a wire grid (WGP2);
- a Golay cell detector (DET);
- 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 (WGP1), then through said rotating polarizer comprising a wire grid (RWGP), then reflect from a sample (S) placed on said stage (STG) for supporting a sample, then pass through said rotating retarder (RRET), then pass through said second rotatable wire grid polarizer (WGP2), enter said Golay cell detector (DET) as output beam (BO);
- b) placing a sample (S) on said stage (STG) for supporting samples;
- c) causing said backward wave oscillator (BWO) to direct a beam (BI) of terahertz frequency electromagnetic radiation Of a fundamental frequency to pass through said first rotatable wire grid polarizer (WGP1) and then through said rotating polarizer comprising a wire grid (RWGP), then reflect from a sample (S) placed on said stage (STG) for supporting a sample, then pass through said rotating retarder (RRET), then pass through said second rotatable polarizer comprising a wire grid (WGP2), and enter said Golay cell detector (DET) as output beam (BO);
- d) obtaining sample describing data from said Golay cell detector (DET).
10 more elements
A method of determining physical and optical properties of samples using a terahertz frequency electromagnetic radiation, comprising the steps of:
- a) providing a terahertz ellipsometer or polarimeter system sequentially system comprising:
- a backward wave oscillator source of terahertz electromagnetic radiation;
- a first rotatable wire grid polarizer (RWG1);
- a stage for supporting a sample (STG);
- a second rotatable wire grid polarizer (RWG2);
- a Golay cell detector (DET) of terahertz electromagnetic radiation;
- said terahertz ellipsometer or polarimeter system further comprising a first rotating element (RE1) and second rotating element (RE2) between said source and detector of electromagnetic radiation;
- such that in use said backward wave oscillator source of terahertz electromagnetic radiation directs a beam (BI) of terahertz frequency electromagnetic radiation to pass through said first rotatable wire grid polarizer (RWG1), then reflect from a sample (S) placed on said stage (STG) for supporting a sample, then pass through said second rotatable polarizer wire grid (RWG2), and as output beam (BO) enter said detector of electromagnetic radiation as output beam (BO), wherein said beam also passes through said first rotating element (RE1) and second rotating element (RE2);
- b) placing a sample (S) on said stage (STG) for supporting samples;
- c) causing said backward wave oscillator (BWO) to direct a beam (BI) of terahertz frequency electromagnetic radiation of terahertz frequency electromagnetic radiation of a fundamental frequency to pass through said first rotatable wire grid polarizer (WGP1), then reflect from a sample (S) placed on said stage (STG) for supporting a sample, then pass through said second rotatable polarizer comprising a wire grid (WGP2), and enter said Golay cell detector (DET) as output beam (BO);
- said input beam (BI) of terahertz frequency electromagnetic radiation also passing through said first rotating element (RE1) and through said second rotating element (RE2) before exiting as said output beam (BO);
- d) obtaining sample describing data from said Golay cell detector (DET).
9 more elements
Dependencies are inferred from the claim text.