We discuss how the results obtained from a white-light interferometer can be compared to tactile measurements. The core
idea to achieve comparability is to determine a short cut-off wavelength up to which the spatial frequency components of
the surface topography are measured with less than 3 dB attenuation. We demonstrate for different interferometers that
the data has to be filtered to achieve a linear transfer characteristic which allows to define the short cut-off wavelength. In
addition, we demonstrate investigations of the error sources in shape measurements that we have identified. Results of our
work are influencing a VDI/VDE calibration guideline for shape measurements which is currently under development.
We show in this paper how the procedure developed for the guideline can be employed to real measurement devices.
Uncertainty contributions to the error budget are also discussed and measurements on shape standards are presented.
For precision traceable measurements with interference microscopes it is necessary to know the aperture correction
factor. The source of the correction is the finite diameter of the illumination light source. If there is no further knowledge
about it, the usual way is the calibration of the instrument with a reference standard. In this contribution a practical way
is described to determine the aperture correction factor of an interference microscope by direct measuring the diameter of
the illumination aperture. A diffraction pattern of a line scale is directed into the microscope objective. In the back focal
plane the set of diffraction orders acts a scale with known dimension. The scale of the diffraction orders can be observed
through the eye piece tube together with the image of the aperture. Under the assumption of an accepted model the
correction factor can be determined. Some considerations for the practical use and results are presented.
A novel compact sensor head combining optical interference and scanning probe microscopy in a single instrument has been developed. The instrument is able to perform complementary quantitative measurements, combining fast non-destructive three-dimensional surface analysis with high lateral resolution imaging. The sensor head has been integrated within the architecture of a commercial interference microscope. The combined instrument makes available both the acquisition software and the hardware interface of the commercial microscope. Furthermore, the use of an optical fiber to transmit light from an external laser removes a major heat source from the measurement environment and its small diameter makes aperture correction unnecessary. Lateral resolution is extended by the attachment of a specially designed scanning probe microscope (SPM) module to the microscope objective. The SPM unit is based upon piezo-resistive cantilever technology and is self-sensing to ensure a compact design that satisfies working distance criteria defined by the optics. A major benefit of the system, in terms of a quantitative nano-metrology, is the possibility to perform a traceable and direct calibration of the SPM module. Ellipsometry has been used to quantify the impact of material differences upon interference height data. Corrected values show excellent agreement with SPM height data.