Optically smooth and optically rough surface in the view of optical 3D sensors based on imaging

An optical 3D sensor is a device intended to measure the geometric shape of objects using optical methods. When designing an optical 3D sensor, it is necessary to consider whether the surface to be measured is smooth or rough. This is because the signal formation process is different for each of the two cases. Moreover, it turns out that the signal formation process is not only influenced by the roughness of the measured surface but also by other parameters of both the measured surface and the optical measuring system. The additional parameter of the measured surface is the surface correlation length. The parameters of the optical measuring system are the wavelength of the light used and the radius of the resolution cell. Based on the knowledge of the parameter values of the surface to be measured and the measuring system, the surface to be measured can be classified as optically smooth or optically rough. We present an analysis to determine whether a given surface measured by a given optical measuring system will behave as an optically smooth or optically rough surface.