Path difference measurement using phase stepping with white light

Phase stepping algorithms are commonly used with narrow bandwidth sources for fast accurate measurement of interferometer phase differences. We show that path difference can also be measured using phase stepping with a wide bandwidth source. The errors resulting from the spectral characteristics of the source are discussed and shown to be relatively small, allowing measurement of path difference to typically 0.1 μm or better. White-light phase stepping is demonstrated experimentally with results which closely match those predicted theoretically.