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Fringe spacing in white-light interferometry

Interference microscopes use quasi-monochromatic, broad band, and white light illumination for surface topography measurement. Fringe spacing for quasi-monochromatic illumination changes with the numerical aperture of system, and these changes have been previously examined by others. In this article we compare changes in fringe spacing for white light and broad band illumination for objectives with a numerical aperture of 0.13 and 0.55. We find that white light fringe spacing changes with tilt of the object much faster than for monochromatic illumination. We also investigate the influence of reference mirror tilt on changes in white light fringe spacing.