Astrophysics (Index)About

interferometer

(device detecting EMR properties using interference between waves)

An interferometer is a device which combines electromagnetic waves in such manner that their interference can be measured to reveal properties of waves. Astronomy often uses the term for radio interferometers that consists of two or more individual radio telescopes, each of which translates received radio waves into electronic signal oscillations, which, in turn, are combined, producing analogous interference. Through analysis of the interference patterns, the direction of the source of a signal can be determined with very high precision (down to microarcseconds), yielding a very precise location in the celestial sphere, and by observing adjacent locations, yielding detail. A sophisticated type, typically using a number of radio telescopes, carries out what is termed aperture synthesis, producing an image of the radio source. This is now carried out at the short-wavelength end of radio (in the region where microwave radio meets infrared, with a wavelength of about a millimeter), producing probably the most detailed images of astronomical objects.

Astronomy also has optical interferometers, doing the analogous processing at visible light wavelengths, but the corresponding frequency is too high for the electronic processing used to measure the interference of radio waves and the interference must be carried out within optics, requiring extremely precise physical positioning of elements of the interferometer necessary to deal with the wavelengths as short as the typical width of a molecule. Such interferometers are useful but the challenges of making them work has prevented more wide-spread use.

A type of interferometer, the Michelson interferometer is used within some optical astronomical instruments and also is the heart of gravitational-wave detectors such as LIGO.

Many spectroscopes use wave interference produced by a grating, thus by definition are interferometers but invariably go by the name spectroscope, indicating the instrument's function.


(measurement,EMR,physics,optics,interferometry)
Further reading:
https://en.wikipedia.org/wiki/Interferometer
https://en.wikipedia.org/wiki/Astronomical_interferometer
https://astronomy.swin.edu.au/cosmos/R/Radio+Interferometer
https://www.eso.org/public/teles-instr/technology/interferometry/
http://spiff.rit.edu/classes/ast613/lectures/radio_iii/radio_iii.html

Referenced by pages:
ALMA-PILS Survey
angular resolution
aperture
aperture masking interferometry (AMI)
aperture synthesis
Astronomical Image Processing System (AIPS)
Atacama Large Millimeter Array (ALMA)
back end instrument
Badgerys Creek Interferometer 101-MHz Survey (Mills)
baseline
BIMA telescope
Caltech Submillimeter Observatory (CSO)
CARMA EDGE
CASA
Combined Array for Research in Millimeter-wave Astronomy (CARMA)
CONCERTO
Cosmic Anisotropy Telescope (CAT)
Cosmic Background Imager (CBI)
cosmic distance ladder
Darwin
DASI
DECIGO
Dominion Observatory 10.03 MHz Source Catalog (DB)
Earth rotation synthesis
Einstein Telescope (ET)
European Southern Observatory Very Large Telescope (ESO VLT)
Fabry-Pérot interferometer (FPI)
Fast Fourier Transform Telescope
front end instrument
GI2T
Giant Metrewave Radio Telescope (GMRT)
gravitational wave spectrum
imaging Fourier transform spectroscopy (IFTS)
Institut de radioastronomie millimétrique (IRAM)
intensity interferometer
interference
interferometry
JUICE
Large Altazimuth Telescope (BTA-6)
Large Binocular Telescope (LBT)
LIGO
LISA
Long Baseline Array (LBA)
Lowell Discovery Telescope (LDT)
MERLIN
Michelson interferometer
Mount Wilson Observatory (MWO)
National Astronomical Observatory of Japan (NAOJ)
Next Generation Very Large Array (ngVLA)
Northern Extended Millimeter Array (NOEMA)
null corrector
optical interferometer
Palomar Testbed Interferometer (PTI)
PAPER
parallax
Plateau de Bure Interferometer (PdBI)
point source sensitivity
QUBIC
scintillometry
Spektr-R
Square Kilometre Array (SKA)
Submillimeter Array (SMA)
Terrestrial Planet Finder (TPF)
Texas Survey of Radio Sources at 365 MHz (TXS)
Third Cambridge Catalogue of Radio Sources (3C)
TIMED
TripleSpec (TSpec)
u-v plane
Upper Atmosphere Research Satellite (UARS)
Very Large Array (VLA)
Very Long Baseline Array (VLBA)
Very Small Array (VSA)
visibility
Voyager
Yuan-Tseh Lee Array (YTLA)

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