A Multiple Angle Method for THz Time-Domain Material Characterization

A multiple angle technique for Terahertz (THz) time-domain material characterization is described. In order to extract the properties of a material system, the technique utilizes the relations between a signal transmitted through a reference material at normal incidence and signals transmitted through the material system at different oblique angles of incidence. The material system may be composed of multiple dielectric layers. The extracted properties of the material system can include not only dielectric properties but also layer thickness. The method presented in this paper contributes to the available library of material characterization tools in the literature in that it provides the capability to carry out single and multiple dielectric layer material system characterization simultaneous with layer thickness extraction. Previous techniques that can characterize both constitutive parameters and layer thicknesses using THz time-domain signals have been scarce. The extraction procedure is simplified to solving a system of equations using a root finding algorithm. The data collection procedure and manipulation is uncomplicated. The method background theory, measurement procedure, forward solution from calculated and measured signals, inverse problem solution from calculated and measured signals, and current method limitations are presented.