An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



Number of Results: 8 Search : interferometer
evolved Laser Interferometer Space Antenna (eLISA)

Fr.: eLISA   

A space project, initially → LISA, consisting of a configuration of three satellites, aimed to detect low frequency → gravitational waves that cannot be measured by ground-based detectors. The detection range will be from about 0.1 milliHz to 1 Hz. One "mother" and two "daughter" spacecrafts will be brought into an orbit around the Sun, which is similar to the Earth's orbit. The satellites will fly in a near-equilateral triangle formation, with a constant distance of one million km between, following the Earth along its orbit at a distance of around 50 million km. The mother spacecrafts carries two and each of the daughter spacecraft carry one free-flying → test masses that will be kept as far as possible free of external disturbances. The mutual distances of the test masses from satellite to satellite will be measured by means of high-precision, → Michelson-like laser → interferometry. In this way, the extremely small distance variations between the test masses of two satellites can be detected which are caused by the passages of a gravitational waves. The required measurement accuracy of the distances amounts to typically 1/100 of the diameter of a hydrogen atom (10-12 m) at a distance of two million km.

evolve; → laser; → interferometer; → space; → antenna.

Fabry-Perot interferometer
  اندرزنش‌سنج ِ فابری-پرو   
andarzaneš-sanj-e Fabry-Perot

Fr.: interféromètre Fabry-Pérot   

A type of interferometer wherein the beam of light undergoes multiple reflections between two closely spaced partially silvered surfaces. Part of the light is transmitted each time the light reaches the second surface, resulting in multiple offset beams which can interfere with each other. The large number of interfering rays produces an interferometer with extremely high resolution, somewhat like the multiple slits of a diffraction grating increase its resolution.

The design was conceived by French physicists Charles Fabry (1867-1945) and Alfred Pérot (1863-1925) in the late nineteenth century; → interferometer.


Fr.: interféromètre   

1) Physics: A device that divides a beam of light into a number of beams and re-unites them to produce → interference. → Fabry-Perot interferometer; → Michelson interferometer.
2) Astro.: An arrangement of two or more separate telescopes placed at some distance from one another, each one receiving electromagnetic radiation (optical, infrared, or radio) from a celestial object and brought together to form an interference pattern.

Interferometer, from interfer, → interfer, + -o- a connective/euphonic infix + → -meter.

Andarzanešsanj, from andarzanešinterference + -sanj, → -meter.

Laser Interferometer Gravitational-Wave Observatory (LIGO)
  نپاهشگاه ِ موجهای ِ گرانشی با اندرزنش‌سنجی ِ لیزری   
nepâhešgâh-e mowjhâ-ye gerâneši bâ andarzaneš-sanji-ye leyzeri

Fr.: Observatoire d'ondes gravitationnelles par interférométrie laser   

A facility dedicated to the detection and measurement of cosmic → gravitational waves. It consists of two widely separated installations, or detectors, within the United States, operated in unison as a single observatory. One installation is located in Hanford (Washington) and the other in Livingston (Louisiana), 3,000 km apart. Funded by the National Science Foundation (NSF), LIGO was designed and constructed by a team of scientists from the California Institute of Technology, the Massachusetts Institute of Technology, and by industrial contractors. Construction of the facilities was completed in 1999. Initial operation of the detectors began in 2001. Each LIGO detector beams laser light down arms 4 km long, which are arranged in the shape of an "L." If a gravitational wave passes through the detector system, the distance traveled by the laser beam changes by a minuscule amount -- less than one-thousandth of the size of an atomic nucleus (10-18 m). Still, LIGO should be able to pick this difference up. LIGO directly detected gravitational waves for the first time from a → binary black hole merger (GW150914) on September 14, 2015 (Abbott et al., 2016, Phys. Rev. Lett. 116, 061102).

laser; → interferometer; → gravitational; → wave; → observatory.

Laser Interferometer Space Antenna (LISA)
  آنتن ِ فضایی ِ اندرزنش‌سنج ِ لیزری   
ânten-e fezâyi-e andarzanešsanj-e leyzeri

Fr.: Observatoire d'ondes gravitationnelles par interférométrie laser   

A collaborative project between → NASA and → ESA to develop and operate a space-based gravitational wave detector sensitive at frequencies between 0.03 mHz and 0.1 Hz. LISA detects gravitational-wave induced strains in → space-time by measuring changes of the separation between fiducial masses in three spacecraft 5 million km apart. Ultimately, NASA and ESA decided in 2011 not to proceed with the mission. LISA was not the highest ranked mission in the 2010 Decadal Survey and funding constraints prevented NASA from proceeding with multiple large missions ( → LISA pathfinder.

laser; → interferometer; → space; → antenna.

Michelson interferometer
  اندرزنش‌سنج ِ مایکلسون   
andarzanešsanj-e Michelson

Fr.: Interféromètre de Michelson   

An apparatus that produces interference fringes by splitting a beam of monochromatic light so that one beam strikes a fixed mirror and the other a movable mirror. When the reflected beams are brought back together, an interference pattern results. It is used to measure very precise lengths, such as the wavelength of light, and for high-resolution spectroscopy.

Named after Albert Abraham Michelson (1852-1931), German-American physicist, who built the interferometer for the → Michelson-Morley experiment of 1887; → interferometer.

Andarzanešsanj, → interferometer.

radio interferometer
  اندرزنش‌سنج ِ رادیویی   
andarzanešsanj-e râdioyi

Fr.: interféromètre radio   

An → interferometer designed for radio frequencies.

radio; → interferometer.

VLT Interferometer (VLTI)
  اندرزنش‌سنج ِ VLT   
andarzanešsanj-e VLT

Fr.: interféromètre VLTI   

An interferometer using a combination of the four 8.2 m VLT telescopes with the assistance of one or more of the the four 1.8 m Auxiliary Telescopes in order to achieve a very high spatial resolution. The system works in the visible and near- and mid-infrared wavelengths.

Very Large Telescope (VLT); → interferometer.