Developments in THz-Range Ellipsometry: Quasi-Optical Ellipsometer

A novel experimental setup for multiangular ellipsometric measurements in terahertz spectral range 0.1- 1 THz is described. The instrument operates in polarizer-compensator-sample-analyzer configuration and allows various measurement schemes (e.g., null and rotating analyzer). The ellipsometer is based on quasi-optical transmittance line-hollow dielectric beamguide (HDB)-and a kit of HDB-based components that provided main advantages of the ellipsometer as compared with known analogs. HDB provides almost flat phase front of the radiation on the entire channel cross section without any lenses or mirrors. Ultra-broadband quasi-optical transmittance line provides operation of the ellipsometer within 0.1- 1 THz frequency range without any modifications of configuration and/or construction. This setup can be assembled/disassembled very easily (as a LEGO meccano) and is easily integrated into other equipment. Experimental testing of the ellipsometer was carried out by comparing dielectric constants of a set of materials measured by the setup with reference data and with the results of independent reflectometry measurements.