Three dimensional (3D) surface measurements based on (2D) stylus instrument

S. Z. Zahwi, A. Mekawi

Abstract

Three dimensional measurements (3D) of surface topography are increasingly being recognized as the most adequate method for obtaining a better understanding of surfaces. The dimensional and surface metrology department at the National Institute for Standards in Egypt (NIS) developed a computer-controlled system for 3D surface measurements. The developed system is based on a 2D surface measuring instrument using a stylus contact method. A positioning table is used to displace the specimen underneath the stylus in a cross direction to the traverse stroke. The system can scan small areas on the measured surface (5.6 mm × 0.56 mm) by traversing the stylus of the measuring instrument over the surface in parallel traces. The system consists of a “Talysurf 10” stylus surface measuring instrument interfaced to an “IBM” compatible PC computer with a data acquisition device (DAQ). The (DAQ) is used to control the movement of the measuring stroke of the pick up in the X – axis, to control the movement of the positioning table in a cross direction to the stroke as Y- axis, and to take the data of each profile from the stylus vertical movements during the measurement stroke as Z-axis.<br />The software for the mentioned controls is made using “Labview” programming language. All data of the 3D surface are taken using unfiltered skid less mode of operation. A “Matlab” software is developed and used to take out the trend of the surface using a least square surface plane, then an approximation of a Gaussian filter (moving average) is used to filter the data. A software to analyze the data to get the 3D surface parameters and functions is also developed.

Keywords

Surface; measurements; stylus; instrument; three dimensions; topography

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IMEKO TC

TC14 - Measurement of Geometrical Quantities

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