Roughness measurement by confocal microscopy for brightness characterization and surface waviness visibility evaluation

Brightness and waviness appearance are important criteria of surfaces for the success of commercial products, The first part of this paper presents a brightness measurement procedure based on roughness measurements by confocal microscopy and scattering theory. The resolution of the proposed method allows the separation of as many brightness levels as the eye can detect. This method links the brightness level of surfaces to their microroughness and so provides industry with essential information for the management of the fabrication process in order to obtain the desired final aspect. Tn a second part, the scattering diagrams of surfaces are computed from microroughness parameters. Computed waviness images are compared with real waviness images. Their likeness shows the ability of the proposed procedure to predict the waviness visibility and thus to better control the appearance of manufactured products.