At the Fraunhofer Institute of Optronics, System Technologies and Image Exploitation IOSB, Karlsruhe, a testing system has been developed which can determine the optical properties of surfaces and coatings inline in production processes. The system scans the surface of the test specimen with a laser beam in a continuous process. For each point on the surface, the changes in polarisation of the reflected light are measured and the optical properties are determined. This enables a complete inspection of the surface for cosmetic defects, material flaws or coating defects. In contrast to conventional ellipsometric inspection systems with separate transmitter and receiver unit and fixed angle of incidence and angle of reflection, the inspection can be carried out even if the surface is subject to strong changes in inclination. This allows, for example, the inspection of polished and painted metal or plastic surfaces as well as the inspection of functional layers from the automotive, microelectronics and sanitary sectors.