COMPANY SPOTLIGHT
New pioneering 3D Topography technology from BYK-Gardner to objectively evaluate total perception , combining Colour and Gloss measurement with new and surface structure & depth
Our visual perception is influenced by Colour , gloss and the surface structure . Our visual rating takes all three parameters into consideration and makes an overall judgement . Up to now , grain or surface structure could only be judged visually or with high sophisticated microscopes . This has changed with the new spectro2- profiler , a pioneering technology combining Colour , gloss , 2D reflectivity and 3D topography in a robust , portable tool with a short measuring time .
Introduction - Colour analysis is not enough
Uniform appearance is a crucial quality criterion for many products . The choice of material and production process variations influence the surface quality , for example the cell size of powder coatings is highly dependent on paint film thickness and curing conditions . Another example are injection molding applications where fluctuations in tool pressure and temperature will show up in gloss and contrast variations . With the change of just one material or process parameter , the visual perception of Colour and appearance can be changed significantly . So far visual assessment was the only way to deliver a complete judgement of a textured surface including Colour and gloss evaluation . The recent developments of Colour and gloss meters significantly improved quality control , but do not include the effects of structure or complex gloss behavior of 3D-surfaces . Therefore , 3D microscopes are used to provide very detailed information of the surface structure in the laboratory for research purposes , but not suitable for fast and easy analysis of production quality .
3D Topography analysis using photometric stereo technique
Photometric stereo is a technique for estimating surface normals in order to calculate a 3D topography of that surface . The technique was originally introduced by Woodham in 1980 I . The surface normals are calculated by observing an object from different illumination directions . With each direction , the object casts different shadows on the surface and a camera acquires images for each illumination ( Figure 1 ). Using shape from shading , the surface curvature is estimated , and the height map of the object can be calculated . The result is a real 3D topography of the measured object surface ( Figure 2 ).
Figure 1 : Image acquisition of different illuminations II to calculate surface topography
Figure 2 : Height map of a powder coated surface measured with the spectro2profiler instrument . The unit P- ยต m is perceived height .
4 DECEMBER 2020 read online : www . surfaceworld . com