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Lyot Type Coronagraph
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Lyot may refer to: *Bernard Lyot, French astronomer *Lyot filter * Lyot stop *Lyot depolarizer * Lyot (lunar crater) * Lyot (Martian crater) *2452 Lyot, asteroid *Bernard Lyot Telescope The Bernard Lyot Telescope (''Téléscope Bernard Lyot'', or TBL) is a 2 m Cassegrain telescope operating in the visible domain, since 1980. It is located at 2877 m elevation on the Pic du Midi in the French Pyrenees. Since 2007, the Bernard L ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bernard Lyot
Bernard Ferdinand Lyot (27 February 1897 in Paris – 2 April 1952 in Cairo) was a French astronomer. Biography An avid reader of the works of Camille Flammarion, he became a member of the Société Astronomique de France in 1915 and made his first observations using the society's telescope on rue Serpente in Paris. He soon acquired a telescope and soon upgraded to a . From graduation in 1918 until 1929, he worked as a demonstrator at the École Polytechnique and studied engineering, physics, and chemistry at the University of Paris. From 1920 until his death he worked for the Meudon Observatory, where in 1930 he earned the title of ''Joint Astronomer of the Observatory''. After gaining the title, he earned a reputation of being an expert of polarized and monochromatic light. Throughout the 1930s, he labored to perfect the coronagraph, which he invented to observe the corona without having to wait for a solar eclipse. In 1938, he showed a movie of the corona in action to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lyot Filter
A Lyot filter, named for its inventor Bernard Lyot, is a type of optical filter that uses birefringence to produce a narrow passband of transmitted wavelengths. Lyot filters are often used in astronomy, particularly for solar astronomy. A Lyot filter is made from one or more birefringent plates (usually quartz), with (in multi-plate filters) each plate being half the thickness of the previous one. Because the plates are birefringent, the ''ordinary'' and ''extraordinary'' polarization components of a light beam experience a different refractive index and thus have a different phase velocity. Therefore, the polarization state of light with an arbitrary wavelength will in general be modified after a passage through the filter plate, and this causes a loss of optical power in a subsequent polarizer. For certain wavelengths, however, the optical path length difference is an integer multiple of the wavelength, so that the losses are very small. By rotating the plates, one can shift ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lyot Stop
A Lyot stop (also called a glare stop) is an optical stop, invented by French astronomer Bernard Lyot, that reduces the amount of flare caused by diffraction of other stops and baffles in optical systems. Lyot stops are located at images of the system's entrance pupil In an optical system, the entrance pupil is the optical image of the physical aperture stop, as 'seen' through the front (the object side) of the lens system. The corresponding image of the aperture as seen through the back of the lens system ... and have a diameter slightly smaller than the pupil's image. Examples of applications can be found in Ref. See also * Lyot filter * Lyot depolarizer * Coronagraph References External linksNASA Coronagraphs [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lyot Depolarizer
A depolarizer or depolariser is an optical device used to scramble the polarization of light. An ideal depolarizer would output randomly polarized light whatever its input, but all practical depolarizers produce pseudo-random output polarization. Optical systems are often sensitive to the polarization of light reaching them (for example grating-based spectrometers). Unwanted polarization of the input to such a system may cause errors in the system's output. Types Cornu depolarizer The Cornu depolarizer was one of the earliest designs, named after its inventor Marie Alfred Cornu. It consists of a pair of 45° prisms of quartz crystal, optically contacted to form a cuboid. The fast axes are 90° apart and 45° from the sides of the depolarizer (see figure). Any ray entering the prism effectively passes through two wave plates. The thickness of these wave plates and therefore their retardance varies across the beam. The phase shift is given by :\delta(y) = \frac _2 - n_12y - ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lyot (lunar Crater)
Lyot is a large lunar impact crater that is located along the southeastern limb of the Moon. It lies within the irregular and patchy lunar mare named Mare Australe, and to the south of the crater Hamilton. Due to its location, this formation is viewed at a low angle from the Earth, and its visibility is affected by libration. The interior floor of this crater has been resurfaced by lava, leaving a dark interior with an albedo that matches the surrounding mare. The outer rim is low and heavily worn, with a perimeter that forms a somewhat distorted circle. The southwest part of the floor and rim is marked by several small, bowl-shaped craters. There is also the remains of a ghost crater A palimpsest , in planetary astronomy, is an ancient crater that has been degraded over time. They may also be referred to as "ghost craters", "degraded craters", "buried craters", or "pathological craters". Palimpsests have been identified on ... to the east of the crater midpoint. Satelli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lyot (Martian Crater)
Lyot is a large peak ring crater in the Vastitas Borealis region of Mars, located at 50.8° north latitude and 330.7° west longitude within the Ismenius Lacus quadrangle. It is 236 km in diameter. Its name refers to Bernard Lyot, a French astronomer (1897–1952). Lyot crater, featuring a central peak in the middle, stands out on the flat plains of Vastitas Borealis, which is generally flat and smooth with few large craters. Lyot is the deepest point in the northern hemisphere of Mars. To the south are the Deuteronilus Mensae, and further to the southeast are Protonilus Mensae. To the west is the smaller Micoud crater, and to the east-southeast is Moreux crater. Research published in 2009 describes evidence for liquid water in Lyot in the past. Many channels have been found near Lyot Crater. Research, published in 2017, concluded that the channels were made from water released when the hot ejecta landed on a layer of ice that was 20 to 300 meters thick. Calculations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2452 Lyot
45 may refer to: * 45 (number) * one of the years 45 BC, AD 45, 1945, 2045 Film * ''45'' (film), directed by Peter Coster (2009) * ''.45'' (film), directed by Gary Lennon (2006) Music * ''45'' (Jaguares album), 2008 * ''45'' (Kino album), 1982 * "45" (Bon Iver song), 2016 * "45" (The Gaslight Anthem song), 2012 * "45" (Shinedown song), 2003 * "45" (Elvis Costello song), 2002 *"Forty Five", a song by Karma to Burn from the album ''Appalachian Incantation'', 2010 *45 rpm record or 45, a common form of vinyl single Other uses *Donald Trump, the 45th President of the United States, with the nickname "45" * ''45'' (book), written by Bill Drummond *.45 caliber, a family of firearm cartridges ** A nickname for a handgun chambered in .45 caliber, such as the M1911 pistol or Colt Single Action Army **.45 ACP, pistol cartridge **.45 Colt, revolver cartridge *Jacobite rising of 1745 or "The '45", in the United Kingdom *Forty-fives, a card game *'The 45%', collective term used by Scottish i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
