The Optical Aspect of Errors in Measurements of Surface Asperities Using the Optical Profilometry Method
Karol Grochalski, Michał Wieczorowski, Jihad H’roura, Gaëtan Le Goïc
Abstract
The paper presents the impact of lighting type and direction on measurements of surface asperities using a focus - variation microscopy. Particular attention was paid to the direction of lighting used 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 obtained. 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.