Stratified dispersive model for material characterization using   terahertz time-domain spectroscopy
  We propose a novel THz material analysis approach which provides highly accurate material parameters and can be used for industrial quality control. The method treats the inspected material within its environment locally as a stratified system and describes the light-matter interaction of each layer in a realistic way. The approach is illustrated in the time-domain and frequency-domain for two potential fields of implementation of THz technology: quality control of (coated) paper sheets and car paint multilayers, both measured in humid air. 
J.L.M. van Mechelen, A.B. Kuzmenko, and H. Merbold
cond-mat.mtrl-sci physics.optics