Autor: Marc Wendel

Summary Quality of highly stressed surfaces is determined by their functional purpose. So-called functional surfaces are frequently encountered in our modern industrial environment, e.g. in automative or medical applications. Production tolerances in all fields of applications, in the micro as well as the macro structures domain, are getting more and more stringent in the recent past. That is why the monitoring of production processes demands sensitive, task specific measuring instruments. While tactile profile measurement methods can still be seen as the reference in roughness and form measurements, they also habe disadvantages, especially in production-related (inline) tasks. Tactile methods are highly sensitive to external impresses vibrations, e.g. caused by machine tools nearby. They also yield only single profile sections of the surface. As uniform characteristics of micro and macro structures across the whole surface can´t be considered, many distributed profile sections have to be acquired. Taking numerous measurements to determine areal characteristics of a surface is very time-consuming. Therefore the acquisition of areal topographies is better done by optical measurement methods. But latter are usually also highly sensitive to vibrations. A measuring instrument, which is insensitive to vertical vibrations due to an angular measurement principle, is the angle resolved scatterd light sensor: The scattered light of an illuminated surface is collected by a lens and imaged to a linear photodiode array in the back focal plane. The expectation value, i.e. the mean position of the scatterde lifht distribution at the diode array, is a measure of the surface´s macro structure. The width of the measured distribution delivers information about the micro structure. The achieved parameters are areal parameters of the illuminated surface, because no phase information is acquired. This thesis deals with the above mentioned promising measurement method and highlights two topics. First of all, an existing measuring device for two-dimensional acquisition of scattered light, using a linear photodiode array, is qualified. Afterwards, the extension of the measuring device to acquire the third dimension is discussed. Latter will be done by examining two approaches: rotation of the three-dimensional scattered light distribution over the linear diode array via a rotating prim, as well as the acquisition by an areal sensor. A short introduction and motivation is followed by the state of the art, covering all relevant topics. Here, the interaction between surface and light, as well as the introduced surface models, can be seen as a fundamental basis. Two approaches for the description of scattered light are presented in this context: physical and geometric optics.