Thickness Determination for Homogeneous Dielectric Materials through THz-TDS

Through the use of terahertz time-domain spectroscopy (THz-TDS), the sample thickness can be determined by exploiting the Fabry-Perot effect. Given the reference pulse and the full-scanned sample pulse traversing a homogeneous dielectric material with a known index of refraction, the method calculates the thickness from the fringe pattern, i.e. the maxima and minima, appearing in the transmission amplitude spectrum. High accuracy is attainable when a material has a constant index of refraction and low loss across the T-ray frequency region. This paper demonstrates results using silicon and cycloolefines as test material.