Evaluation of repeatability of topographic measurements based on multiscale analysis

This paper describes a new method, based on wavelet transformation, for evaluation repeatability during optical measurements of surface topography. Repeated measurements are made with the same parameters without repositioning the measuring object. The analysis carried out proved differences in the variability of surface irregularities with respect to scale. On the surface it is possible to distinguish a number of morphological features which, during the realization of subsequent measurements, were defined by a different distribution of irregularity height, resulting in highlighting measurement errors. The analysis showed that these changes are particularly visible for scales up to 13 μm, nevertheless for larger scales the differences occur only in selected sections of the profile and not along the entire length, which has a direct correlation with the occurrence of peak or valley. For small scales, slight shifts of certain morphological features in corresponding profiles were noted, as highlighted by the varying orientation of the arrows. The study has the potential for practical use in both the research field and industrial applications, and can contribute to supplementing the current standards.