Robust reconstruction of the topography of metal additive surfaces based on focus variation microscopy

When using an optical profiler to measure rough surfaces, especially surfaces generated by metal additive manufacturing, topographical artifacts such as spikes on a reconstructed surface are nearly unavoidable. These may affect the determination of roughness parameters of the topography and lead to erroneous surface features. This paper proposes a new preprocessing method to eliminate most artifacts before extracting surface heights of rough surfaces measured by focus variation microscopy. In this method, the axial region where a surface height value is located with highest probability is estimated, based on datasets of planes parallel to the axial scanning direction. Results regarding height measurements with and without the proposed method are compared by measuring a Rubert Microsurf 329 comparator test panel for reference and a workpiece produced by metal additive manufacturing.