Process monitoring and quality assurance with a microwave radar sensor
By means of microwaves it is possible to perform nondestructive and online capable testing in the domain of material properties, geomaetric dimensions (e.g. thickness) and detection of defects like flaws, delaminating or voids. Often the examination can be performed without contact. Preferred materials to be tested are dielectrics since they are partly transparent with respect to microwaves. A measurement and testing system based on a Frequency Modulated Continuous Wave (FMCW) radar sensor at ca. 94 GHz has been built up and applied on different processes and objects like injection molding with gas bubble injection, contact less imaging of inner defects and measurement of plastic coat thickness on steel pipelines. Furthermore thin metallic layers on dielectric substrates could be characterized with low priced monofrequent microwave sensors at 9.4 GHz.