Abstract-Fastest Thickness Measurements with a Terahertz Time-Domain System based on Electronically Controlled Optical Sampling

Milad Yahyapour, Angelika Jahn, Katja Dutzi, Thomas Puppe, Patrick Leisching, Bernhard Schmauss, Nico Vieweg,  Anselm Deninge

https://www.mdpi.com/2076-3417/9/7/1283

We apply a fast terahertz time-domain spectroscopy (TDS) system based on electronically controlled optical sampling (ECOPS) to contact-free thickness gauging. Our setup achieves a measurement speed of 1600 terahertz pulse traces per second, which—to our knowledge—represents the fastest thickness measurement performed with any terahertz system to-date. Using a silicon wafer as a test sample, we compare data of the ECOPS experiment to results obtained with a conventional terahertz TDS system and a mechanical micrometer gauge. We show that all systems provide consistent results within the measurement accuracy. Moreover, we perform thickness measurements of a rapidly moving sample and characterize the ECOPS setup with respect to time-domain dynamic range, signal-to-noise ratio, and spectral properties