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Determination of the point spread function of a coherence scanning interferometer.

Palodhi, K*; Coupland, J M*; Leach, R K (2011) Determination of the point spread function of a coherence scanning interferometer. In: 13th International Conference on Metrology and Properties of Engineering Surfaces., 12-15 April 2011, Twickenham Stadium, UK.

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Abstract

Coherence scanning interferometry (CSI) combines the lateral resolution of a high power microscope with the axial resolution of an interferometer and provides a rapid and convenient means to measure surface topography. Although CSI measurements of features, such as step heights, have been demonstrated with nanometre accuracy, systematic errors have been reported in the measurement of more general features, such as sinusoids, where surface gradient can be significant.
Recently, methods of three-dimensional imaging systems, including digital holography, confocal microscopy and CSI have been analysed as linear shift invariant processes that are characterised by their point spread function (PSF). In this paper, it is shown that that the linear theory leads to a straightforward model of fringe formation in CSI. The influence of the PSF on measurements of a sinusoidal surface profile and a method to measure the PSF of a CSI instrument is then discussed.

Item Type: Conference or Workshop Item (UNSPECIFIED)
Keywords: coherence scanning interferometry, scanning white light interferometry, surface measurement, calibration
Subjects: Engineering Measurements
Engineering Measurements > Dimensional
Last Modified: 02 Feb 2018 13:14
URI: http://eprintspublications.npl.co.uk/id/eprint/4974

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