This paper presents the influence of thermal phenomena on areal measurements of surface topography using contact profilometers. The research concerned measurements under controlled and variable environmental conditions. The influence of internal heat sources from profilometer drives and their electronic components was analyzed. For this purpose, a thermal chamber was designed and built. Its task was to maintain and control environmental conditions and, at the same time, separate the profilometer from external disturbances. Heat sources and temperature values for elements and systems were determined. It further enabled for the calculation of the displacements in axes as a function of temperature. The largest displacement in the probe due to internal heat sources for the considered cases occurred in the X-axis direction. Its value reached 16.2 μm. However, the displacement in the probe in the Z-axis direction had the greatest impact on the measured surface topography. These displacements for a thermally unstable profilometer reached 7.9 μm in Z, causing results even 90% greater than in the case of a device without such problems. The time after which a proper topography measurement can be started was also determined basing on obtained data. This time for tested profilometers was between 6 and 12 h. It was found that performing thermal stabilization of the profilometer significantly reduced surface irregularity errors. The stabilization time should be determined individually for a specific type of device.
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.
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