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

Abstract-All fiber-coupled THz-TDS system with kHz measurement rate based on electronically controlled optical

http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-39-22-6482
Roman J. B. Dietz, Nico Vieweg, Thomas Puppe, Armin Zach, Björn Globisch, Thorsten Göbel, Patrick Leisching, and Martin Schell  »View Author Affiliations

We demonstrate a completely fiber-coupled terahertz (THz) time-domain spectrometer (TDS) system based on electronically controlled optical sampling with two erbium-doped femtosecond fiber lasers at a central wavelength of 1560 nm. The system employs optimized InGaAs/InAlAs photoconductive antennas for THz generation and detection. With this system, we achieve measurement rates of up to 8 kHz and up to 180 ps scan range. We further achieve 2 THz spectral bandwidth and a dynamic range of 76 dB at only 500 ms measurement time.

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