# interferometer

## Definitions

• WordNet 3.6
• n interferometer any measuring instrument that uses interference patterns to make accurate measurements of waves
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Webster's Revised Unabridged Dictionary
• n Interferometer (Physics) An instrument for measuring small movements, distances, or displacements by means of the interference of two beams of light; -- formerly also called also refractometer, but that word now has a different meaning.
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Century Dictionary and Cyclopedia
• n interferometer An instrument for the measurement of lengths by means of the phenomena resulting from the interference of two rays of light. The development of the interferometer is chiefly due to Michelson, but the instrument in its modern form is based upon an extension of the principle used by Jamin in his refractometer. The Jamin refractometer was designed for the measurement of the indexes of refraction of transparent bodies by means of the retardation of a ray of ght passing through a given thickness of the substance as indicated by its manner of interference with a ray not thus retarded. In this refractometer two plates of parallel glass of equal thickness, silvered on the back, are monnted in a vertical position with their faces parallel as shown in Fig. I. One of these plates, AA, makes an angle of 45° with the axis of the instrument; the second, BB, can be turned about a vertical axis and its distance from AA can be altered at will. A beam of light passes through the slit Sand a portion of it reflected from the first face of AA reaches the other plate BB. That portion of this ray which penetrates the second plate and is reflected from the silvered surface at the back (D) is shown in the diagram. That portion of the incident ray which is transmitted by the plate AA is similarly reflected from the silvered back (C) of that plate and likewise reaches BB, a portion of it being reflected from the first surface of that plate. This ray and the one reflected from the back of BB follow the same path after leaving the second plate. When the plates are parallel the two rays will have followed equal and similar paths and will be in the same phase. If now the plate BB is slightly displaced from its vertical position there will be a difference of phase between the rays and a series of horizontal dilfraction-fringes will appear. If a thin plate L of any refracting substance is placed in the path of one of the rays between AA and BB the retardation of the light in transmission through it will produce a shifting of the diffraction-fringes from which the index of refraction of the substance may be computed, if its thickness is known; or its thickness, provided the index is known. The instrument therefore may be used either as a refractometer or an interferometer.
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## Etymology

Webster's Revised Unabridged Dictionary
See Interfere and -meter,

## Usage

### In literature:

A photograph of the interferometer is shown in Fig.
"The New Heavens" by George Ellery Hale
The telescope shown is part of an interferometer used to measure flexure of the support.
"Development of Gravity Pendulums in the 19th Century" by Victor Fritz Lenzen and Robert P. Multhauf
A. Michelson's interferometer there is no such restriction.
"Encyclopaedia Britannica, 11th Edition, Volume 14, Slice 6" by Various
The telescope shown is part of an interferometer used to measure flexure of the support.
"Smithsonian Institution - United States National Museum - Bulletin 240" by Anonymous
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### In news:

Chu's atom interferometer could lead to GPS without the satellites.
The JPL MkIV interferometer .
The Jet Propulsion Laboratory MkIV interferometer is a high resolution Fourier Transform Infra-Red (FTIR) spectrometer, designed to remotely sense the atmospheric composition.
Nicolaus fired up his laser interferometer, the device used to determine their volume.
An atom interferometer provides most precise test yet of Einstein's gravitational redshift Provided by the University of California, Berkeley.
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### In science:

Map of the 1.3 mm continuum obtained with the IRAM interferometer in the ﬁeld of the source HDF 850.1 by Downes et al. (1999).
High-Redshift Galaxies: The Far-Infrared and Sub-Millimeter View
More recent dynamical mass estimates of a low-redshift infrared galaxy sample observed in CO with the Plateau de Bure Interferometer indicate that α can be as low as 1 M⊙ [K km s−1 pc2 ]−1 (Downes & Solomon 1998).
Molecular Gas in Infrared-Excess, Optically-Selected QSOs and the Connection with Infrared Luminous Galaxies
Short spacing interferometers have usually been used in interferometric CMB anisotropy measurements to give higher surface brightness sensitivity.
Observing the CMB with the AMiBA
This may represent the interferometer being constructed as a prototype for the AMiBA.
Observing the CMB with the AMiBA
The Tanaka-Tagoshi construction is effective for all ﬁrst generation interferometers .
Optimum Placement of Post-1PN GW Chirp Templates Made Simple at any Match Level via Tanaka-Tagoshi Coordinates
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