It has a wide variety of applications and is used in the field of physics, astronomy, oceanography, seiesmology, and more.

Interferometry is a technique used to compare two or more wave forms. The comparison of wave forms is done by superimposing the waves and observing the result. Interferometry is used for a variety of purposes from astronomy to oceanography. It’s wide variety of applications is responsible for a richer understanding of our universe from interstellar molecules to the topography and velocity of glaciers.

See also

• Interferences
• Interferometers

When the waves that come together have the same frequency they are said to be in phase. Waves that are in phase add up and result in one bigger wave in terms of amplitude. For ocean waves this means larger or higher waves while in optics this means a brighter light. The adding up of two waves is called constructive interference.

On the other hand, when two waves that are of different frequencies meet they are said to be out of phase. Since they are not in phase the waves, instead of adding up, cancel each other out resulting in a smaller wave. This kind of interference is called destructive interference.

Most interferometers are optical interferometers, which means that it is light waves that are used and analysed. Examples of other types of interferometers that use other waves forms are the atom interferometer, which uses atoms, and the Interferometric synthetic aperture radar (InSAR), which uses radiation.

Optical interferometers work splitting a beam of light into two using mirrors/lenses. The resulting waves are then combined again to create interference and then the result observed and measured. During the early days of interferometry scientists only used white light sources but now there are interferometers that use even monochromatic light sources like laser. Some of the common kinds of optical interferometers include the Michelson interferometer, Mach-Zehnder interferometer, Sagnac interferometer, and Fabry-Perot interferometer. The Michelson interferometer, which is one of the most basic interferometers, is probably the most popular interferometer having been used to prove Einstein’s Theory of Relativity.