A homodyne quadrature laser interferometer for micro-asperity deformation analysisPogačnik, Aljaž (Avtor) Požar, Tomaž (Avtor) Kalin, Mitjan (Avtor) Možina, Janez (Avtor) polymerstribologymicro-asperitydeformationlaser interferometryhomodyne detectiondisplacementreal contact arearoughnesscreepWe report on the successful realization of a contactless, non-perturbing, displacement-measuring system for characterizing the surface roughness of polymer materials used in tribological applications. A single, time-dependent, scalar value, dubbed the collective micro-asperity deformation, is extracted from the normal-displacement measurements of normally loaded polymer samples. The displacement measurements with a sub-nanometer resolution are obtained with a homodyne quadrature laser interferometer. The measured collective micro-asperity deformation is critical for a determination of the real contact area and thus for the realistic contact conditions in tribological applications. The designed measuring system senses both the bulk creep as well as the micro-asperity creep occurring at the roughness peaks. The final results of our experimental measurements are three time-dependent values of the collective micro-asperity deformation for the three selected surface roughnesses. These values can be directly compared to theoretical deformation curves, which can be derived using existing real-contact-area models.20132021-09-02 13:43:41Članek v reviji129506UDK: 539.92:531.715ISSN pri članku: 1424-8220DOI: 10.3390/s130100703COBISS_ID: 12590619sl