For a successful geometrical characterisation of the described micro structured coatings, the lateral resolution of the measurement device should be higher than 250 nm. Therefore, a confocal microscope or white light interferometer was used for the laboratory measurements. To obtain reliable and accurate geometrical information, the optical measurement results were verified by a secondary electron microscope (SEM). Its advantage is the higher lateral resolution and the ability to detect steep angles. Though a SEM only produces 2D images, it is possible to evaluate the 3D-geometry of local structures using the shape from shading method.

For a degradation analysis, the 3D measurement results were used for calculation of the task-relevant geometric parameters. For this purpose, different mathematical instruments such as Fourier analysis and statistical estimation can be used. The parameters are presented as histograms and correspondent distributions.

The solutions, which were developed for laboratory tests, cannot be directly used for quasi-real time measurements because the micro-coating production rates are usually distinctly higher. For this reason, the surface was examined using 2D cameras. Here not the real 3D topography, but secondary characteristics, such as the specific reflection of corners or the darker indications from tilted surfaces, are being controlled. The areal scanning will be achieved with the aid of highly precise linear axes. If a divergence from the desired course is found during the camera examination, this spot will be examined with confocal microscopes. These microscopes can be installed on positioning devices. The 3D measurement results are additionally tested for their precision and robustness. If necessary, improvements may be implemented which aim particularly at the elimination of oscillations in the system.

In conclusion, time optimisation was performed by distributing the control of the system on several synchronised workstations.