White-light interference microscopy: minimization of spurious diffraction effects by geometric phase-shifting.

A common problem when profiling surfaces with steps or discontinuities using white-light (coherence-probe) interferometry is localized spikes (batwings) or spurious peaks due to diffraction effects. We show that errors due to these effects can be minimized by processing the irradiance data obtained with an achromatic phase-shifter operating on the geometric (Pancharatnam) phase to yield the values of the surface height. (c) 2009 Optical Society of America