Modeling and simulation of a chromatic-confocal sensor to measure rough surfaces

The measurement of geometrical quantities like the profile or the roughness of surfaces is important to ensure that a high quality in a production process is maintained. The use of optical sensors for quality control offers many advantages in comparison to classical tactile principles: It is a non-contact measurement, usually it is faster and by recording of a set of measuring data during one shot, it is nearly invariant to mechanical vibrations. Hence optical sensors seem to be ideal for production process monitoring. As a consequence we have to ensure, that a reliable measurement can be performed on a rough surface. However to design an optical sensor that is adjusted to measure such surfaces in one shot, it is important to understand how a sensor responds to rough surfaces. Therefore, we present the modeling and simulation of a chromatic-confocal sensor by the use of sequential and non-sequential ray-tracing software. By simulating the approach of a chromatic-confocal sensor, we are able to evaluate how the measurement is affected by rough surfaces, which are simplified due to simulation assumptions.