Vertical scanning white-light interferometry (SWLI) is a well-established method that is widely used in high precision surface topography measurement. However, SWLI results show characteristic slope-dependent errors due to dispersion effects and lateral chromatic aberrations of the optical imaging system. In this paper, we present methods to characterize these systematic errors related to dispersion and lateral colour. Lateral colour leads to field-dependent systematic discrepancies of the topography data obtained from the envelope position of a low-coherence interference signal and the data resulting from its interference phase. Hence, an erroneous fringe order obtained from the envelope position leads to a 2π phase jump and thus to a so-called ghost step in the measured topography. Our first approach to solve this problem is based on the measurement of a surface standard of well-known geometry. By comparison of measurement results related to the envelope position and the phase of SWLI signals, the systematic error is estimated and a numerical error compensation method is proposed. Both experimental and simulation results confirm the validity of this numerical method. In addition, using an improved design of a white-light Michelson interferometer we demonstrate experimentally that lateral chromatic aberrations and dispersion influences can be reduced also in a physical way. In this context, a conventional long working distance microscope objective is used which was not originally designed for a Michelson interference microscope.

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Capability to simulate the coherence function is important when tuning an interference microscope in an effort to reduce sidelobes in interference signals. The coherence function cannot directly be derived from the light source spectrum since the microscope's effective spectrum is affected by e.g. spatial coherence effects. We show this by comparing the true system spectrum measured using a spectrometer against the effective system spectrum obtained by Fourier analysis of the interference data. The results show that a modulation function that describes the scattering-induced spatial coherence dampening in the system is needed to correct the observed difference between these two spectra. The validity of this modulation function is further verified by quantifying the arithmetic mean roughness of two specified roughness standards. By providing a spectral transfer function for scattering, our method can simulate a sample specific coherence function, and thus shows promise to increase the quality of interference microscope images.