INTERFEROMETER
interferometer
(noun) any measuring instrument that uses interference patterns to make accurate measurements of waves
Source: WordNet® 3.1
Etymology
Noun
interferometer (plural interferometers)
(physics) any of several instruments that use the interference of waves to determine wavelengths and wave velocities, determine refractive indices, measure small distances, temperature changes, stresses, and many other useful measurements.
Source: Wiktionary
In`ter*fe*rom"e*ter, n. [See Interfere and -meter.] (Physics)
Definition: An instrument for measuring small movements, distances, or
displacements by means of the interference of two beams of light; --
called also refractometer.
Source: Webster’s Unabridged Dictionary 1913 Edition