1. Optics. a device that separates a beam of light into two ray beams, usually by means of reflection, and that brings the rays together to produce interference, used to measure wavelength, index of refraction, and astronomical distances.
  2. Astronomy. an instrument for measuring the angular separation of double stars or the diameter of giant stars by means of the interference phenomena of light emitted by these stars.

Origin of interferometer

First recorded in 1895–1900; interfere + -o- + -meter
Related formsin·ter·fer·o·met·ric [in-ter-feer-uh-me-trik] /ˌɪn tərˌfɪər əˈmɛ trɪk/, adjectivein·ter·fer·o·met·ri·cal·ly, adverbin·ter·fer·om·e·try, noun Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for interferometer

Historical Examples of interferometer

  • The interferometer has much refined the indications of the balance.

  • The resolving power of the interferometer is found to be somewhat more than double that of a telescope of the same aperture.


    David Todd

  • By applying the interferometer method to Capella, arc distances of much less than one-twentieth of a second of arc were measured.


    David Todd

  • Many diverse applications of the interferometer have been developed, as, for example, in thermometry.

  • In the interferometer the approach of the small ball to the large one produced a displacement of seven whole fringes.

British Dictionary definitions for interferometer


  1. physics any acoustic, optical, or microwave instrument that uses interference patterns or fringes to make accurate measurements of wavelength, wave velocity, distance, etc
  2. astronomy a radio or optical array consisting of two or more telescopes separated by a known distance and connected so that the radiation from a source in space undergoes interference, enabling the source to be imaged or the position of the source to be accurately determined
Derived Formsinterferometric (ˌɪntəˌfɛrəˈmɛtrɪk), adjectiveinterferometrically, adverbinterferometry, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for interferometer

"instrument for measuring the interference of light waves," 1897, a hybrid from interfere + meter (3).

Online Etymology Dictionary, © 2010 Douglas Harper

interferometer in Science


  1. Any of several optical, acoustic, or radio frequency instruments that use interference phenomena between a reference wave and an experimental wave or between two parts of an experimental wave to determine wavelengths and wave velocities, measure very small distances and thicknesses, and calculate indices of refraction.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.