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Mangin Mirror
In optics, a Mangin mirror is a negative meniscus lens with the reflective surface on the rear side of the glass forming a curved mirror that reflects light without spherical aberration if certain conditions are met. This reflector was invented in 1876 by a French officer Alphonse Mangin as an improved catadioptric reflector for search lights and is also used in other optical devices. Description The Mangin mirror's construction consists of a concave ( negative meniscus) lens made of crown glass with spherical surfaces of different radii with the reflective coating on the shallower rear surface. The spherical aberration normally produced by the simple spherical mirror surface is canceled out by the opposite spherical aberration produced by the light traveling through the negative lens. Since light passes through the glass twice, the overall system acts like a triplet lens. The Mangin mirror was invented in 1876 by a French military engineer named Colonel Alphonse Mangin as a subs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mangin Mirror
In optics, a Mangin mirror is a negative meniscus lens with the reflective surface on the rear side of the glass forming a curved mirror that reflects light without spherical aberration if certain conditions are met. This reflector was invented in 1876 by a French officer Alphonse Mangin as an improved catadioptric reflector for search lights and is also used in other optical devices. Description The Mangin mirror's construction consists of a concave ( negative meniscus) lens made of crown glass with spherical surfaces of different radii with the reflective coating on the shallower rear surface. The spherical aberration normally produced by the simple spherical mirror surface is canceled out by the opposite spherical aberration produced by the light traveling through the negative lens. Since light passes through the glass twice, the overall system acts like a triplet lens. The Mangin mirror was invented in 1876 by a French military engineer named Colonel Alphonse Mangin as a subs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ludwig Schupmann
Ludwig Ignaz Schupmann (23 January 1851 in Geseke (Westphalia), Germany – 2 October 1920 also in Geseke) was a German professor of architecture and an optical designer. He is principally remembered today for his Medial and Brachymedial telescopes, types of catadioptric reflecting-refracting telescopes with Mangin mirrors that eliminate chromatic aberrations while using common optical glasses. Used in early lunar studies, they are used now in double-star work. The asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ... 5779 Schupmann is named in his honour. Works ''Die Medial-Fernrohre - Eine neue Konstruktion für große astronomische Instrumente'', Teubner-Verlag, 1899 External links Ludwig Schupmann and some Early Medial Telescopes 1851 births 1920 deaths Architect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Argunov–Cassegrain Telescope
The Argunov–Cassegrain telescope is a catadioptric telescope design first introduced in 1972 by P. P. Argunov. All optics are spherical, and the classical Cassegrain secondary mirror is replaced by a sub-aperture secondary corrector group consisting of three air-spaced elements, two lenses and a Mangin mirror (the element farthest from the primary mirror). Discussion Argunov systems only employ spherical surfaces and avoid the practical difficulties of making and testing aspheres. However, this benefit is marginal, as it is almost as difficult to make a true zone-free sphere of precise radius of curvature as it is to make an aspheric surface with comparable precision. Further, since multiple surfaces are involved, creating a design with good aberration correction can become very complicated. See also * Klevtsov–Cassegrain telescope * List of telescope types The following are lists of devices categorized as types of telescopes or devices associated with telescopes. They ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Klevtsov–Cassegrain Telescope
The Klevtsov–Cassegrain telescope is a type of catadioptric Cassegrain telescope that uses a spherical primary mirror and a sub-aperture secondary corrector group composed of a small lens and a Mangin mirror. Design In the Klevtsov-Cassegrain, all of the optical surfaces are spherical or near-spherical. The secondary Mangin mirror () and the meniscus corrector (''C'') are held in place by a spider vane and the front of the telescope tube is otherwise open. These types of telescopes have the disadvantage of the spider, which holds the corrector, causing diffraction artifacts and, since multiple surfaces are involved, achieving good aberration correction can be very complex. This design was originally envisaged by G. I. Popov with a practical implementation by Yuri A. Klevtsov. Commercial manufacturers of the design include Novosibirsk TAL and Vixen. See also * Argunov–Cassegrain telescope * Cassegrain reflector * List of telescope types The following are lists of de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Head-mounted Display
A head-mounted display (HMD) is a display device, worn on the head or as part of a helmet (see Helmet-mounted display for aviation applications), that has a small display optic in front of one (monocular HMD) or each eye ( binocular HMD). An HMD has many uses including gaming, aviation, engineering, and medicine. Virtual reality headsets are HMDs combined with IMUs. There is also an optical head-mounted display (OHMD), which is a wearable display that can reflect projected images and allows a user to see through it. Overview A typical HMD has one or two small displays, with lenses and semi-transparent mirrors embedded in eyeglasses (also termed data glasses), a visor, or a helmet. The display units are miniaturized and may include cathode ray tubes (CRT), liquid-crystal displays (LCDs), liquid crystal on silicon (LCos), or organic light-emitting diodes (OLED). Some vendors employ multiple micro-displays to increase total resolution and field of view. HMDs differ in whethe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sight (device)
A sight is an aiming device used to assist in visually aligning ranged weapons, surveying instruments or optical illumination equipments with the intended target. Sights can be a simple set or system of physical markers that have to be aligned together with the target (such as iron sights on firearms), or optical devices that allow the user to see an optically enhanced — often magnified — target image aligned in the same focus with an aiming point (e.g. telescopic sights, reflector sights and holographic sights). There are also sights that actively project an illuminated point of aim (a.k.a. "hot spot") onto the target itself so it can be observed by, such as laser sights and infrared illuminators on some night vision devices. Simple sights At its simplest, a sight typically has two components, front and rear aiming pieces that have to be lined up. Sights such as this can be found on many types of devices including weapons, surveying and measuring instruments, and nav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Headlamp
A headlamp is a lamp attached to the front of a vehicle to illuminate the road ahead. Headlamps are also often called headlights, but in the most precise usage, ''headlamp'' is the term for the device itself and ''headlight'' is the term for the beam of light produced and distributed by the device. Headlamp performance has steadily improved throughout the automobile age, spurred by the great disparity between daytime and nighttime traffic fatalities: the US National Highway Traffic Safety Administration states that nearly half of all traffic-related fatalities occur in the dark, despite only 25% of traffic travelling during darkness. Other vehicles, such as trains and aircraft, are required to have headlamps. Bicycle headlamps are often used on bicycles, and are required in some jurisdictions. They can be powered by a battery or a small generator like a bottle or hub dynamo. History of automotive headlamps Origins The first horseless carriages used carriage lamps ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Image-forming Optical System
In optics, an image-forming optical system is a system capable of being used for imaging. The diameter of the aperture of the main objective is a common criterion for comparison among optical systems, such as large telescopes. The two traditional systems are mirror-systems (catoptrics) and lens-systems (dioptrics), although in the late twentieth century, optical fiber was introduced. Catoptrics and dioptrics have a focal point, while optical fiber transfers an image from one plane to another without an optical focus. Isaac Newton is reported to have designed what he called a ''catadioptrical phantasmagoria'', which can be interpreted to mean an elaborate structure of both mirrors and lenses. Catoptrics and optical fiber have no chromatic aberration, while dioptrics need to have this error corrected. Newton believed that such correction was impossible, because he thought the path of the light depended only on its color. In 1757 John Dollond was able to create an achromatised diop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Naval
A navy, naval force, or maritime force is the branch of a nation's armed forces principally designated for naval warfare, naval and amphibious warfare; namely, lake-borne, riverine, littoral zone, littoral, or ocean-borne combat operations and related functions. It includes anything conducted by surface Naval ship, ships, amphibious warfare, amphibious ships, submarines, and seaborne naval aviation, aviation, as well as ancillary support, communications, training, and other fields. The strategic offensive role of a navy is Power projection, projection of force into areas beyond a country's shores (for example, to protect Sea lane, sea-lanes, deter or confront piracy, ferry troops, or attack other navies, ports, or shore installations). The strategic defensive purpose of a navy is to frustrate seaborne projection-of-force by enemies. The strategic task of the navy also may incorporate nuclear deterrence by use of submarine-launched ballistic missiles. Naval operations can be broa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optics
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviolet, and infrared light. Because light is an electromagnetic wave, other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties. Most optical phenomena can be accounted for by using the classical electromagnetic description of light. Complete electromagnetic descriptions of light are, however, often difficult to apply in practice. Practical optics is usually done using simplified models. The most common of these, geometric optics, treats light as a collection of rays that travel in straight lines and bend when they pass through or reflect from surfaces. Physical optics is a more comprehensive model of light, which includes wave effects such as diffraction and interference that cannot be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
