The interferometer is designed to exploit, in any of a variety of ways, the interference of light and

the fringe patterns that result from optical path differences. The interferometer is also called an

optical interferometer. This general description of the interferometer reflects its wide variety of

designs and uses. Applications of interferometers can also extend to acoustic and radio waves. This

chapter explains the basic principles of the Michelson, Mach-Zehnder, and the Fabry-



rot interferometers.