Questions about astronomical observations which involve superimposing waves received by multiple, physically separated, receivers to obtain higher angular resolution.

Interferometry is a technique in which waves, usually electromagnetic waves, are superimposed, causing the phenomenon of interference, which is used to extract information.

Interferometers are used for the measurement of small displacements, refractive index changes and surface irregularities. In most interferometers, light from a single source is split into two beams that travel in different optical paths, which are then combined again to produce interference.