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Open AccessArticle

Non-Contact Roughness Measurement in Sub-Micron Range by Considering Depolarization Effects

Institute for Measurement Systems and Sensor Technology, Technical University of Munich, Theresienstrasse 90, 80333 Munich, Germany
ETSI Minas y Energía, Universidad Politécnica de Madrid, Calle de Ríos Rosas 21, 28003 Madrid, Spain
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Sensors 2019, 19(10), 2215;
Received: 27 March 2019 / Revised: 7 May 2019 / Accepted: 10 May 2019 / Published: 14 May 2019
(This article belongs to the Section Physical Sensors)
The characteristics of a surface, particularly the roughness, play an important role in different fields of the industry and have to be considered to ensure quality standards. Currently, there are numerous sophisticated methods for measuring surface roughness but plenty of them cause long-term damage because they are in contact with the sample. This article presents a non-contact method to accurately determine small surface roughnesses resulting from the consideration of the depolarization effects caused by the rough surface. This technique can be applied as an extension in various roughness measurements and improves the approach of Chandley’s technique, which does not take into account the depolarization of the light scattered by the sample. The experimental setup and the measurements are easy to perform. The essential component is a quarter wave plate, which is incorporated into a Michelson interferometer. With the resulting two different contrasts and the recorded intensities of the sample and the reference mirror, the surface roughness can be estimated straightforwardly. This article details the theoretical approach, followed by the experimental results and the corresponding uncertainties. The experimental results are compared with Chandley’s method. In order to have reference roughness values of the samples, measurements with a stylus profilometer and with a confocal microscope are performed and compared. View Full-Text
Keywords: roughness measurement; non-contact method; depolarization; contrast roughness measurement; non-contact method; depolarization; contrast
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Pöller, F.; Salazar Bloise, F.; Jakobi, M.; Wang, S.; Dong, J.; Koch, A.W. Non-Contact Roughness Measurement in Sub-Micron Range by Considering Depolarization Effects. Sensors 2019, 19, 2215.

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