Comparison of Optoelectronic Time- and Frequency-Domain Systems for Single- and Multilayer Thickness Measurements

We present the first comparison of optoelectronic frequency- and time-domain terahertz (THz) systems for thickness measurements on sub-mm single- and multilayer samples using identical setups, samples and evaluation procedures in order to obtain comparable results. We find that single layer PET and Kapton foils with a thickness of 23 mm - 350 mm can be measured with similar accuracy with both systems. Hence, frequency-domain THz systems may replace time-domain systems in future industrial layer thickness measurements.