An optical profiler for three dimensional measurements obtains the height data by scanning the sample under measurement through the depth of focus of the objective under use. The most common scanning devices are linear motorized stages and piezoelectric devices in both, close-loop and open-loop control. The accuracy and repeatability of height data are subject to the linearity movement of the vertical scanning stage. Today, optical profilers are characterized by using a traceable standard, such as a vertical step height, which is measured several times to compute its avera

Nowadays the determination of the accuracy and repeatability of an optical profiler is done by performing several repetitions of a step height measurement and calculating the accuracy error (mean) and the repeatability error (standard deviation) of the data obtained. This process is inefficient, time consuming and highly dependant on the non-linearity error of the vertical stage which highly determines the values of both accuracy and repeatability. In this paper we show the existence and further characterization of non-linearities in the movement of the vertical scanner of an optical profiler and their influence in the determination of the optical profiler specifications.