THz time domain spectroscopy of materials in reflection and transmission

This thesis presents and describes various improvements to a Terahertz time domain spectroscopy setup using plasma filament for generation and free space electro optic sampling for detection. By performing measurements on several materials, and comparing them to the literature, we explicitly demonstrate that general experimental considerations, e.g. humidity, small misalignments, beam spot, behavior around the focal plane, and polishing of samples are detrimental for accurate measurements of the complex refractive index n = n + iK. We also demonstrate that an EO-crystal detection scheme substantially limits the measurements