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Shack–Hartmann Wavefront Sensor
A Shack–Hartmann (or Hartmann–Shack) wavefront sensor (SHWFS) is an optical instrument used for characterizing an imaging system. It is a wavefront sensor commonly used in adaptive optics systems. It consists of an array of lenses (called lenslets) of the same focal length. Each is focused onto a photon sensor (typically a CCD array or CMOS array or quad-cell). If the sensor is placed at the geometric focal plane of the lenslet, and is uniformly illuminated, then, the integrated gradient of the wavefront across the lenslet is proportional to the displacement of the centroid. Consequently, any phase aberration can be approximated by a set of discrete tilts. By sampling the wavefront with an array of lenslets, all of these local tilts can be measured and the whole wavefront reconstructed. Since only tilts are measured the Shack–Hartmann cannot detect discontinuous steps in the wavefront. The design of this sensor improves upon an array of holes in a mask that had been dev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shack Hartmann
A shack (or, in some areas, shanty) is a type of small shelter or dwelling, often primitive or rudimentary in design and construction. Unlike huts, shacks are constructed by hand using available materials; however, whereas huts are usually rural and made of natural materials (mud, rocks, sticks, etc.) shacks are generally composed of scavenged man-made materials like abandoned construction debris, repurposed consumer waste and other useful discarded objects that can be quickly acquired at little or no cost and fashioned into a small dwelling. Background In areas of high population density and high poverty, shacks are often the most prevalent form of housing; it is possible that up to a billion people worldwide live in shacks. Fire is a significant hazard in tight-knit shack settlements. Settlements composed mostly or entirely of shacks are known as slums or shanty towns. In Australian English ''shack'' can also refer to a small holiday house with limited conveniences, for i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hartmann Mask
Hartmann mask is a tool to help focusing telescopes, mainly used by amateur astronomers. It is named after the German astronomer Johannes Franz Hartmann (1865–1936), who developed it around 1900. Theory and practice Every part of a mirror or lens produces the same image as the whole optical element. The light is focused in the focal point. The light rays, however, go through different points of a plane before or behind the focus. This phenomenon can be used when focusing a telescope. The Hartmann mask is a simple opaque mask containing two or three holes. (This device is called a Hartmann mask if it has multiple holes, or a Scheiner disk if it has two holes.) The mask covers the aperture of the telescope. When the apparatus is out of focus, multiple images can be seen if the telescope is pointed towards a bright light source (Moon, bright star). Adjusting the focuser, the images can be made to overlap, forming a single bright, clear picture. The mask may also be used to che ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James Webb Space Telescope
The James Webb Space Telescope (JWST) is a space telescope which conducts infrared astronomy. As the largest optical telescope in space, its high resolution and sensitivity allow it to view objects too old, distant, or faint for the Hubble Space Telescope. This will enable investigations across many fields of astronomy and cosmology, such as observation of the first stars, the formation of the first galaxies, and detailed atmospheric characterization of potentially habitable exoplanets. The U.S. National Aeronautics and Space Administration (NASA) led JWST's design and development and partnered with two main agencies: the European Space Agency (ESA) and the Canadian Space Agency (CSA). The NASA Goddard Space Flight Center (GSFC) in Maryland managed telescope development, the Space Telescope Science Institute in Baltimore on the Homewood Campus of Johns Hopkins University operates JWST, and the prime contractor was Northrop Grumman. The telescope is named after James E. Webb, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Telescope Element
Optical Telescope Element (OTE) is a sub-section of the James Webb Space Telescope, a large infrared space telescope launched on , consisting of its main mirror, secondary mirrors, the framework and controls to support the mirrors, and various thermal and other systems. The OTE collects the light and sends it to the science instruments in Webb's Integrated Science Instrument Module. The OTE has been compared to being the " eye" of the telescope and the backplane of it to being the " spine". The primary mirror is a tiled assembly of 18 hexagonal elements, each from flat to flat. This combination yields an effective aperture of and a total collecting surface of . Secondary mirrors complete anastigmatic imaging optics with effective 20 focal ratio and focal length of . The main three-mirror telescope is a Korsch-type design, and it feeds into the Aft Optics Subsystem (part of OTE), which in turn feeds into the Integrated Science Instrument Module which holds the science instr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Austria
Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous city and state. A landlocked country, Austria is bordered by Germany to the northwest, the Czech Republic to the north, Slovakia to the northeast, Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the west. The country occupies an area of and has a population of 9 million. Austria emerged from the remnants of the Eastern and Hungarian March at the end of the first millennium. Originally a margraviate of Bavaria, it developed into a duchy of the Holy Roman Empire in 1156 and was later made an archduchy in 1453. In the 16th century, Vienna began serving as the empire's administrative capital and Austria thus became the heartland of the Habsburg monarchy. After the dissolution of the H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Christopher Scheiner
Christoph Scheiner SJ (25 July 1573 (or 1575) – 18 June 1650) was a Jesuit priest, physicist and astronomer in Ingolstadt. Biography Augsburg/Dillingen: 1591–1605 Scheiner was born in Markt Wald near Mindelheim in Swabia, earlier markgravate Burgau, possession of the House of Habsburg. He attended the Jesuit St. Salvator Grammar School in Augsburg from May 1591 until 24 October 1595. He graduated as a "rhetor" and entered the Jesuit Order in Landsberg am Lech on 26 October 1595. At the local seminary, he served his biennial novitiate (1595–1597) under the tutelage of Novice Master Father Rupert Reindl SJ. From 1597 to 1598, he finished his lower studies of rhetoric in Augsburg. He took his first vows before Father Melchior Stör, SJ and received the minor orders from the Augsburg suffragan bishop Sebastian Breuning. He spent the years 1598–1601 in Ingolstadt studying philosophy (metaphysics and mathematics). In 1603, Scheiner invented the pantograph, "Lake County A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Christiaan Huygens
Christiaan Huygens, Lord of Zeelhem, ( , , ; also spelled Huyghens; la, Hugenius; 14 April 1629 – 8 July 1695) was a Dutch mathematician, physicist, engineer, astronomer, and inventor, who is regarded as one of the greatest scientists of all time and a major figure in the Scientific Revolution. In physics, Huygens made groundbreaking contributions in optics and mechanics, while as an astronomer he is chiefly known for his studies of the rings of Saturn and the discovery of its moon Titan. As an engineer and inventor, he improved the design of telescopes and invented the pendulum clock, a breakthrough in timekeeping and the most accurate timekeeper for almost 300 years. An exceptionally talented mathematician and physicist, Huygens was the first to idealize a physical problem by a set of mathematical parameters, and the first to fully mathematize a mechanistic explanation of an unobservable physical phenomenon.Dijksterhuis, F.J. (2008) Stevin, Huygens and the Dutch republ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johannes Franz Hartmann
Johannes Franz Hartmann (11 January 1865 – 13 September 1936) was a German physicist and astronomer. In 1904, while studying the spectroscopy of Delta Orionis he noticed that most of the spectrum had a shift, except the calcium lines, which he interpreted as indicating the presence of interstellar medium. Asimov, ''Asimov's Biographical Encyclopedia of Science and Technology'' 2nd Revised edition He was the director of the La Plata Astronomical Observatory, Argentina, from November 1922 to May 1934, and was also known under the name Juan Hartmann. He oriented the work of the observatory towards astrophysics and discovered the three asteroids of the main-belt, 965 Angelica, 1029 La Plata and 1254 Erfordia at La Plata between 1921 and 1932. His doctorate was from the University of Leipzig in 1891 on lunar eclipses. The lunar crater '' Hartmann'' on the far side of the Moon was named in his honor. Note, however, that the asteroid 3341 Hartmann was named after William ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Aberration
In optics, aberration is a property of optical systems, such as lenses, that causes light to be spread out over some region of space rather than focused to a point. Aberrations cause the image formed by a lens to be blurred or distorted, with the nature of the distortion depending on the type of aberration. Aberration can be defined as a departure of the performance of an optical system from the predictions of paraxial optics. In an imaging system, it occurs when light from one point of an object does not converge into (or does not diverge from) a single point after transmission through the system. Aberrations occur because the simple paraxial theory is not a completely accurate model of the effect of an optical system on light, rather than due to flaws in the optical elements. An image-forming optical system with aberration will produce an image which is not sharp. Makers of optical instruments need to correct optical systems to compensate for aberration. Aberration can be anal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inverse Of Shack Hartmann
Inverse or invert may refer to: Science and mathematics * Inverse (logic), a type of conditional sentence which is an immediate inference made from another conditional sentence * Additive inverse (negation), the inverse of a number that, when added to the original number, yields zero * Compositional inverse, a function that "reverses" another function * Inverse element * Inverse function, a function that "reverses" another function **Generalized inverse, a matrix that has some properties of the inverse matrix but not necessarily all of them * Multiplicative inverse (reciprocal), a number which when multiplied by a given number yields the multiplicative identity, 1 ** Inverse matrix of an Invertible matrix Other uses * Invert level, the base interior level of a pipe, trench or tunnel * ''Inverse'' (website), an online magazine * An outdated term for an LGBT person; see Sexual inversion (sexology) See also * Inversion (other) Inversion or inversions may refer to: Art ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wavefront
In physics, the wavefront of a time-varying ''wave field'' is the set (locus) of all points having the same ''phase''. The term is generally meaningful only for fields that, at each point, vary sinusoidally in time with a single temporal frequency (otherwise the phase is not well defined). Wavefronts usually move with time. For waves propagating in a unidimensional medium, the wavefronts are usually single points; they are curves in a two dimensional medium, and surfaces in a three-dimensional one. For a sinusoidal plane wave, the wavefronts are planes perpendicular to the direction of propagation, that move in that direction together with the wave. For a sinusoidal spherical wave, the wavefronts are spherical surfaces that expand with it. If the speed of propagation is different at different points of a wavefront, the shape and/or orientation of the wavefronts may change by refraction. In particular, lenses can change the shape of optical wavefronts from planar to spher ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CMOS
Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss", ) is a type of metal–oxide–semiconductor field-effect transistor (MOSFET) fabrication process that uses complementary and symmetrical pairs of p-type and n-type MOSFETs for logic functions. CMOS technology is used for constructing integrated circuit (IC) chips, including microprocessors, microcontrollers, memory chips (including CMOS BIOS), and other digital logic circuits. CMOS technology is also used for analog circuits such as image sensors (CMOS sensors), data converters, RF circuits (RF CMOS), and highly integrated transceivers for many types of communication. The CMOS process was originally conceived by Frank Wanlass at Fairchild Semiconductor and presented by Wanlass and Chih-Tang Sah at the International Solid-State Circuits Conference in 1963. Wanlass later filed US patent 3,356,858 for CMOS circuitry and it was granted in 1967. commercialized the technology with the trademark "COS-MO ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
