Comprehensive profile and areal calibration by additively manufactured material measures

The calibration of surface texture measuring instruments is standardized with two distinct types of material measures. ISO 25178-70 categorizes material measures that feature a profile and an areal surface topography. The result is that different types of measuring instruments like profilers on the one hand and areal surface topography measuring instruments on the other hand may require different material measures whose scope of application may be limited to only one of the named instrument types. The reason is that most manufacturing principles allow either a linear or circular extrusion of a geometry limiting the possibilities to manufacture material measures that are suitable for both, profile and areal surface topography measuring instruments. Since a comparability is desired for as many different measuring instruments as possible, we examine to what degree profile and areal material measures of ISO 25178-70 can be adapted and combined to possibly allow a calibration of all types of surface topography measuring instruments. Additive manufacturing with direct laser writing (DLW) is characterized by a high degree of freedom in the design of material measures. An enhancement of structures that can be imaged either in multiple lateral directions or extruded to circular geometries is possible, allowing both, a profile sampling in different directions, just as well as an areal measurement. In the present publication, a modification of the ISO 25178-70 material measures is described including the design process, the manufacturing and the measurement with areal and profile surface topography measuring instruments to practically demonstrate the feasibility of a multifunctional calibration that considers the possible effects of directionality. We show that it is possible to combine different profile and areal geometries by linear and/or areal extrusion of the corresponding profile-based geometry. By aligning multiple material measures onto one sample, it can also be demonstrated that a comprehensive calibration of an optical profiler is enabled with only one measurement.