While the Michelson interferometer is mainly used to determine the movement of a reflecting object in a nm scale, the Mach-Zehnder interferometer investigates transparent objects and is particularly useful for studying liquid or gas dynamics. Since the Mach-Zehnder is a unidirectional interferometer it is especially useful for measurements where the samples have to be traversed only once or in one direction.
Within the experiment P18.104.22.168 both, a Michelson- and a Mach-Zehnder interferometer will be realised. The former demonstrates the principle generation of interference patterns and the use of fringe counting in metrology. The latter uses the interference pattern to visualise changes of the index of refraction as a result of changes in physical properties of gasses, like pressure or composition.