4. Mach-Zehnder interferometer

In the Michelson interferometer, the bangs are located at infinity if the images of the mirrors in the beam splitter are parallel, and they are located on the mirrors if these images form a small angle. Light interference, which makes it possible to observe local variations in optical path, is a powerful tool for studying variations in air index in a wind tunnel. It is interesting to be able to locate air wedge bangs on the model under study. This is made possible by the Mach-Zehnder interferometer, a set-up derived from the Michelson interferometer with additional degrees of freedom.

A 45° beam splitter S sends the reflected and transmitted beams onto two 45° mirrors M ₁ and M ₂ (figure 13...