Inline multilayer thickness sensing by using terahertz time-domain spectroscopy in reflection geometry

We present a novel approach to determine the individual layer thickness in a dielectric multilayer sample using pulsed terahertz spectroscopy in reflection geometry. In a first step, the optical parameters of each layer have to be determined. Based on these parameters, we simulate the reflected THz-pulse from the multilayer system and compare it to the measurement. A genetic algorithm is used to determine the best agreement between simulation and measurement by varying the thickness of each layer.