Use of White Light and Laser 3D Scanners for Measurement of Mesoscale Surface Asperities

Depending on the purpose of a manufactured part, quality assessment is performed within macro-, micro-, or mesoscale. The first two apply strictly to geometry and surface texture (topography or profile) measurements, respectively. The latter however, applies for measurements of features that do not belong strictly to either of the two scales mentioned above, and its boundaries are ambiguous in their nature, often overlapping the two basic scales. In this paper the authors have undertaken the assessment of the possibility to use macro-scale dedicated scanners for surface asperities measurement – features usually considered as micro-scale. The choice of the measurement systems was inspired by the limitations of previously used roughness measurement systems, which lacked a sufficient vertical range. At the same time, due to high roughness values, large areas have to be measured, which would take significant amount of time, when performing traditional roughness measurement. Several scanners were evaluated: white and blue structural light, laser, and laser with tracking device. The collected data were compared to the results obtained from a specialized Coherent Scanning Interferometer (CSI). The final results have undergone a two-level assessment: qualitative, which compared the quality of whole surfaces; quantitative, using surface texture parameters. The results allow to state that 3D scanners can be used in some cases for surface asperities assessment, however most promising values were obtained, when using devices with higher resolution.