Dutch United Instruments (DUI) is a Dutch company based in Delft, the Netherlands. DUI provides optics surface metrology tools for different sizes of optics. Our flagship product is the NMF600 S for optics up to 600mm in diameter. NMF products are based on the proven NANOMEFOS technology by TNO (Netherlands Organisation for Applied Scientific Research). DUI NMF products are specifically designed to provide easy and accurate surface metrology of complex optics to the workshop floor. The fast, non-contact tools are capable of measuring optics ranging from convex to concave and from flat to freeform, with a typical measurement uncertainty below 15 nm RMS. NMF products are based on three basic principles: A cylindrical coordinate measurement machine setup. This ‘giant cd-player’ setup enables universal measurement of all sorts of optics (small to large, convex to concave), and fast measurement with minimal fast moving axes. A non-contact probe with large range captures the freeform departure of the surface, enabling high measurement speeds even for highly freeform surfaces (up to 1.5 m/s at the probe). This in turn gives a very high data point density making it especially suitable for mid-spatial frequency characterization. A separate metrology system with a stabilized HeNe interferometer and a Silicon Carbide reference frame. This system corrects for motion and vibration errors resulting in repeatability below 1 nm rms and traceable measurement accuracy.