Thickness Gauging of Kapton Foil during Web Processing using fast Terahertz Time-Domain-Spectroscopy

We implement a setup for quality control during web processing of thin plastic foils based on a record-speed THz-TDS system combined with a U-frame scanner and fast data analysis. For validation, our thickness measurements of a 75 µm Kapton foil are compared with results obtained by white-light interferometry. Both results agree very well, showing the potential of terahertz systems for inline quality control.