ABSTRACT
Interference can be used to explain a number of common optical phenomena such as the color or soap bubbles and the optical fringes. Optical interference is used to make highly accurate measurements of surface shapes, refractive index, mechanical displacement, and velocity. It has also been used to measure stellar diameters and gravity waves, and to test basic theories of light propagation. This entry discusses optical propagation and diffraction, and examines what happens when two or more beams of light interfere. The basics of interferometric metrology are discussed, and examples of how optical interference can be observed are provided. This entry looks at the history of interference, the theory of interference, and how it is produced, observed, optimized, and used to make measurements.
