Mobile Handheld FMCW Terahertz Multilayer Thickness Inspection

We present an all-electronic handheld system for the thickness determination of dielectric multilayer structures with submillimeter to several centimeter layer thicknesses, using a frequency-modulated continuous-wave terahertz transceiver. Besides A-scans, an integrated linear position encoder allows to obtain B-scan images. In order to resolve layers below the inherent resolution limit given by the frequency modulation bandwidth, we take advantage of model-based signal processing techniques.