Both optical and tactile probes are often used in dimensional metrology applications, especially for roughness, form, thickness and surface profile measurements. To perform such kinds of measurements with a nanometre-level of accuracy (∼30 nm), Laboratoire National de Métrologie et d’Essais (LNE) has developed a new high-precision machine. The architecture of the machine contains a short and stable metrology frame dissociated from the supporting frame. It perfectly respects the Abbe principle. The metrology loop supports reference laser interferometers and is equipped either with an optical probe or a tactile probe of nanometric resolution and linear residuals. The machine allows in situ calibration of the measuring optical and tactile probes by comparison to the laser interferometer measurements, considered as a reference. In this paper, both architecture and operation of the LNE's high-precision profilometer are detailed. A brief comparison of the behaviour (linear residuals) of the confocal chromatic and tactile probes is presented. Optical and tactile scanning of V-grooves artefacts with 75, 24, 7.5, 2.4, 0.75 and 0.24 µm depths are illustrated and discussed. In addition, a comparison between optical, tactile and atomic force microscopy measurements on a VLSI SHS 880-QC is also performed. Finally, a comparison of an optical and tactile scanning of optical aspherical lens with a polymer coating is presented and discussed.

Chromatic confocal probes are increasingly used in high-precision dimensional metrology applications such as roughness, form, thickness and surface profile measurements; however, their measurement behaviour is not well understood and must be characterized at a nanometre level. This paper provides a calibration bench for the characterization of two chromatic confocal probes of 20 and 350 µm travel ranges. The metrology loop that includes the chromatic confocal probe is stable and enables measurement repeatability at the nanometer level. With the proposed system, the major error sources, such as the relative axial and radial motions of the probe with respect to the sample, the material, colour and roughness of the measured sample, the relative deviation/tilt of the probe and the scanning speed are identified. Experimental test results show that the chromatic confocal probes are sensitive to these errors and that their measurement behaviour is highly dependent on them.