Da-Hye Choi, Il-Min Lee, Kiwon Moon, Dong Woo Park, Eui Su Lee, and Kyung Hyun Park
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| Fig. 1 Schematic of the experiment set-up. A beating signal generated from a tunable laser system is injected into the transmitter (Tx) for THz generation. The THz waves are divided by a beam splitter. The beams reflected from the two mirrors are focused on the receiver (Rx). |
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-10-14695
A terahertz continuous wave system is demonstrated for thickness measurement using Gouy phase shift interferometry without frequency sweep. One arm of the interferometer utilizes a collimated wave as a reference, and the other arm applies a focused beam for sample investigation. When the optical path difference (OPD) of the arms is zero, a destructive interference pattern is produced. Interference signal intensity changes induced by the OPD changes can be easily predicted by calculations. By minimizing the difference between the measured and the calculated signal against the OPD, the thicknesses of sub-100-μm-thick samples are determined at 625 GHz.
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