Real-time imaging-ellipsometry with a polarization camera in R2R-applications

Abstract

We present an inline imaging ellipsometer based on a polarization camera for real-time, full-area quality control of thin-film coatings in roll-to-roll (R2R) production. The system captures two-dimensional distributions of polarization-dependent intensity ratios reflected from the moving substrate with fixed illumination wavelength and angle of incidence. This measurement enables the detection of coating uniformity, shape, and defects, even those hardly visible by conventional optical means. Two simple calculation methods are proposed to estimate the spatial distribution of layer thickness from polarization data. A full 2D image is constructed by accumulating high-frame-rate line measurements across the web. The system is demonstrated for PEDOT-layers on PET and battery electrolyte coatings on copper foil, indicating its potential as a robust, real-time solution for inline thickness monitoring in R2R manufacturing.