Coherence Measurement Using Michelson Interferometer and Fourier Transform Spectroscopy

It is known that, in an interferometer, the fringe contrast may depend on the coherence of the light source. For example, in a Michelson interferometer with a source of a certain bandwidth, the interference fringe contrast decreases as the optical path difference between the two arms increases. By measuring the interferogram contrast at different positions of the movable mirror, the coherence length of the source can be concluded. Typical Fourier-transform spectroscopy is usually based on optical setups of this kind.