A measurement result is traceable only if it is provided with a measurement uncertainty. This is why the measurement uncertainty is an essential component of a measurement and requires profound knowledge of the measuring process and the quantities which may influence it. This is why many guidelines for devices used in roughness technology meanwhile contain calculations for measurement uncertainties as examples to help a user to find a clue for calculating the measurement uncertainties in his case of application.
The values of surface metrology parameters in accordance with Symbol Gehezu ISO 4287 or ISO 5436-1 are calculated from a great number of measurement points of a profile section (number > 8000) or an area scanning process. This is why the procedure by which the model for uncertainty calculation is established is the same for all stylus instruments and interference microscopes. In a first step, the uncertainty of a single point is calculated. For this purpose, all influence quantities relevant to the measuring process which may of course be very different depending on the device and the measurand, are summarized. In the next step, the uncertainty of the single point enters together with other influence quantities into the determination of the uncertainty of a surface parameter.