interferometry

Interferometry is the use and analysis of superimposed electromagnetic radiation (EMR) waves. The patterns produced by waves from different directions and/or wavelengths (wave interference) include information about relative directions and wavelengths. A device carrying out this function is called an interferometer, which offers data for analysis on the differences found in waves gathered by pairs of data sources, such as the EMR waves gathered by two telescopes that are some distance apart.

Radio astronomy makes much use of interferometry (radio interferometry), using multiple radio telescopes (dishes) to achieve a higher angular resolution. Keck Observatory and other twin/multiple telescopes can be used for interferometry of visible light (optical interferometry). A type of imaging spectrograph, the imaging Fourier transform spectroscopy makes use of a type of interferometry.

Gravitational-wave detectors such as LIGO also use interferometry (with Michelson interferometers) to measure extremely small distance-differences.