The Michelson Interferometer is an optical instrument used to measure the interference of light waves. It splits a beam of light into two paths using a beam splitter, reflecting each beam back to recombine them. The resulting interference pattern can reveal minute changes in distance or refractive index. This device is essential in various scientific fields, including metrology and astronomy. It was famously used by Albert A. Michelson to measure the speed of light and contributed to the development of the theory of relativity. Its precision makes it valuable for experiments requiring high accuracy.