Spectrally resolved white light interferometry for profilometry with polarization phase shifter

A spectrally resolved white light interferometer with polarization phase shifter is described for use in surface profiling. Phase shifting is introduced by a rotating half-wave plate while the interferometer is illuminated with collimated white light. The phase shifted intensity values needed for the phase calculation at each pixel are obtained from the same pixel instead of different pixels, thereby avoiding error due to variation in sensitivities of different pixels. The linear relationship between measured phase φ(σ) and σ indicates that the nearly achromatic behavior of the phase shifter.