The Optical Aspect of Errors in Measurements of Surface Asperities Using the Optical Profilometry Method

Abstract : The paper presents the impact of lighting type and direction on measurements of surface asperities using focus-variation microscopy. Particular attention was paid to the direction of lighting when using a light ring. It was pointed out that the lighting direction directly affects the values of the parameters Rt, Rz, and Rc. The article also presents the impact of a light polarizer on the surface topography parameters. It has been shown that the positioning of a sample with a regular and directed structure relative to the optical axis of the light polarizer affects the accuracy of mapping surface asperities. The largest differences were observed for Rz and Rt parameters. A method of using an external polarizer mounted on a focus variation microscope lens was also presented. Keywords: surface topography,