Material characterization methods for layered dielectric media are highly sought after in many fields including nondestructive evaluation, structural health monitoring, security imaging, biological tissue inspection and agricultural and industrial quality assurance. On the other hand, the still under-explored Terahertz frequency range shows great promise and advantages for imaging and spectroscopy. As such, this dissertation provides a library of material parameter extraction tools of single and multiple layered dielectric mediums for different circumstances and using a variety of measurement and analysis criteria. The conditions required for using each characterization method are laid out. The background theory of the methods is based upon electromagnetic waves transmission and reflection phenomena at interfaces, wave propagation and Fourier optics. Because material characterization is an inverse problem solution, optimization and root finding methods were required to that effect. The optimization method utilized was the Nelder-Mead Simplex method while the root finding method was the Secant method. The inverse problem solution setups and special considerations for each of the characterization tools are presented. The operation validation and material characterization examples for each method are demonstrated. Additionally, the limitations of the methods are discussed along with error analysis pertaining to crucial input parameters. On the other hand, a measurement component for fine spatial resolution interrogation is designed, fabricated and tested. This component can be used in conjunction with the methods presented in this research study for simultaneous imaging and spectroscopy/material characterization of structures. The possible future investigation routes related to the research presented in this dissertation are discussed in the conclusion.
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