Phase shifting by a rotating polarizer in white-light interferometry for surface profiling

In white-light interferometry, the position of the peak of the fringe contrast function is directly related to the surface height of the object. In this paper, we present a phase-shifting technique to determine the fringe contrast function using a rotating polarizer, which introduces an achromatic phase shift. The effect of introducing the rotating polarizer phase shifter at the output of the white-light interferometer has been studied. It is shown that the peak of the fringe contrast function does not occur for zero path difference between the arms of the interferometer; it is rather shifted by a constant amount. This shift, however, does not introduce any error in relative height measurements. The experimental results are presented.