Coherence scanning interferometry (CSI) is a widely used optical method for surface topography measurement of industrial and biomedical surfaces. The operation of CSI can be modelled using approximate physics-based approaches with minimal computational effort. A critical aspect of CSI modelling is defining the transfer function for the imaging properties of the instrument in order to predict the interference fringes from which topography information is extracted. Approximate methods, for example, elementary Fourier optics, universal Fourier optics and foil models, use scalar diffraction theory and the imaging properties of the optical system to model CSI surface topography measurement. In this paper, the measured topographies of different surfaces, including various sinusoids, two posts and a step height, calculated using the three example methods are compared. The presented results illustrate the agreement between the three example models.
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