{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,15]],"date-time":"2026-03-15T03:41:47Z","timestamp":1773546107930,"version":"3.50.1"},"reference-count":38,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2013,1,7]],"date-time":"2013-01-07T00:00:00Z","timestamp":1357516800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>We 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.<\/jats:p>","DOI":"10.3390\/s130100703","type":"journal-article","created":{"date-parts":[[2013,1,7]],"date-time":"2013-01-07T11:07:53Z","timestamp":1357556873000},"page":"703-720","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["A Homodyne Quadrature Laser Interferometer for  Micro-Asperity Deformation Analysis"],"prefix":"10.3390","volume":"13","author":[{"given":"Alja\u017e","family":"Poga\u010dnik","sequence":"first","affiliation":[{"name":"Iskra Mehanizmi d.o.o., Lipnica 8, Kropa 4245, Slovenia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Toma\u017e","family":"Po\u017ear","sequence":"additional","affiliation":[{"name":"Faculty of Mechanical Engineering, University of Ljubljana, A\u0161ker\u010deva 6, Ljubljana 1000, Slovenia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mitjan","family":"Kalin","sequence":"additional","affiliation":[{"name":"Faculty of Mechanical Engineering, University of Ljubljana, A\u0161ker\u010deva 6, Ljubljana 1000, Slovenia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Janez","family":"Mo\u017eina","sequence":"additional","affiliation":[{"name":"Faculty of Mechanical Engineering, University of Ljubljana, A\u0161ker\u010deva 6, Ljubljana 1000, Slovenia"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2013,1,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"074001","DOI":"10.1088\/0957-0233\/23\/7\/074001","article-title":"Recent developments and challenges of nanopositioning and nanomeasuring technology","volume":"23","author":"Manske","year":"2012","journal-title":"Meas. 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