Optical measurement of two-step roughness

In the paper a contactless method capable to measure a surface unevenness is described. The method is principally based on oblique illumination of the rough surface with normal viewing of the illuminated area by CCD camera. The light intensity distribution in an image read by camera involves inherently information about the surface microprofile. The amount of light scattered to the normal direction of surface follows the relations of light diffraction and shading on surface hills, grains and dimples in microscale scene. In the paper the contribution of these effects on the overall light scattering is discussed and the correlation length of the roughness is used as a criterion to an accounting whether the diffraction is important. A quantitative calibration procedure has been proposed in order to evaluate the main surface roughnesslwaviness parameters.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.