Quantitative dimensional measurements of micro- and nanometre-sized structures are urgently required from science and industry. Due to their very high vertical resolution (down to sub nanometres) and high lateral resolution (<10 nm) scanning probe microscopes (SPMs) are of great interest for such metrological applications. Additionally, SPM methods are able to measure surfaces in a number of modes like contact, intermittent-contact and non-contact mode. The forces between tip and sample are low during the measurement and, even in contact mode, reach only a few nanonewtons. This fact prevents scratching of the measured surface during the SPM scanning procedure even when very sharp tips are used.