Low Coherence Interferometry for the Inline Measurement of Translucent Multilayer Structures

In a joint national project with industrial partners in the sectors of sensor technology, mechanical engineering and plastic film production, the Fraunhofer Institute for Laser Technology (ILT) has developed a novel optical sensor to monitor the production of plastic films based on interferometric measurements with low coherent radiation [1]. This technique of Optical Coherence Tomography (OCT) is an imaging method generating high-resolution tomography scans. The sensor measures the thicknesses of single layers in multilayer films allowing for the first time inline process monitoring and efficient process guiding of flat-film and blow-film extrusion lines.