Fast and Accurate Thickness Determination of Unknown Materials using Terahertz Time Domain Spectroscopy

Abstract

We present a fast and accurate time domain based algorithm which extracts simultaneously the thickness and refractive index of highly transparent samples from terahertz time domain spectroscopy data. The utilized transfer function considers the FabryPerot oscillations of the sample and enables to analyze data with multiple reflections. The algorithm can also be applied to signals corrupted by vapor absorption lines. Since the data extraction takes only fractions of a second, this computation method is well suited for realtime monitoring of industrial processes. We show that the accuracy of the new algorithm is comparable to that of sophisticated, highly accurate and time consumptive frequency domain algorithms.

Integrated On-Chip THz Sensors for Fluidic Systems Fabricated Using Flexible Polyimide Films

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“…Furthermore, time-domain spectroscopic measurements represent a powerful tool to determine the sample thickness [111,117,118] or even layer thickness in multilayer structures [119]. Moreover, it has been employed to measure the birefringence of materials [120].…”