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Red Dot Sight
A red dot sight is a common classification for a non- magnifying reflector (or reflex) sight that provides an illuminated red dot to the user as a point of aim. A standard design uses a red light-emitting diode (LED) at the focus of collimating optics, which generates a dot-style illuminated reticle that stays in alignment with the firearm the sight is attached to, regardless of eye position (nearly parallax free). Red dot sights are considered to be fast-acquisition and easy-to-use gun sights for firearms used in civilian target shooting, hunting, or in police and military applications. They are also used on cameras and telescopes. On cameras they are used to photograph flying aircraft, birds in flight, and other distant, rapidly moving subjects. Telescopes have a narrow field of view and therefore are often equipped with a secondary "finder scope" such as a red dot sight to orient them. Description The typical configuration for a red dot sight is a tilted spherical mir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tasco PDP2
Tasco may refer to: * Tasco (company), American company which sells consumer telescopes * Tasco, Boyacá, Colombian municipality * Tasco, Kansas, unincorporated community in Sheridan County, Kansas, United States * , United States Navy ship See also * Tasca (surname) * Tesco (other) * Tosca (other) * Tosco (other) {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collimated Light
A collimated beam of light or other electromagnetic radiation has parallel ray (optics), rays, and therefore will spread minimally as it propagates. A laser beam is an archetypical example. A perfectly collimated light beam, with no beam divergence, divergence, would not disperse with distance. However, diffraction prevents the creation of any such beam. Light can be approximately collimated by a number of processes, for instance by means of a collimator. Perfectly collimated light is sometimes said to be ''focused at infinity''. Thus, as the distance from a point source increases, the spherical wavefronts become flatter and closer to plane waves, which are perfectly collimated. Other forms of electromagnetic radiation can also be collimated. In radiology, X-rays are collimated to reduce the volume of the patient's tissue that is irradiated, and to remove stray photons that reduce the quality of the x-ray image ("film fog"). In scintigraphy, a gamma ray collimator is used in fron ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ireland
Ireland (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelanda sovereign state covering five-sixths of the island) and Northern Ireland (part of the United Kingdomcovering the remaining sixth). It is separated from Great Britain to its east by the North Channel (Great Britain and Ireland), North Channel, the Irish Sea, and St George's Channel. Ireland is the List of islands of the British Isles, second-largest island of the British Isles, the List of European islands by area, third-largest in Europe, and the List of islands by area, twentieth-largest in the world. As of 2022, the Irish population analysis, population of the entire island is just over 7 million, with 5.1 million in the Republic of Ireland and 1.9 million in Northern Ireland, ranking it the List of European islands by population, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dublin
Dublin is the capital and largest city of Republic of Ireland, Ireland. Situated on Dublin Bay at the mouth of the River Liffey, it is in the Provinces of Ireland, province of Leinster, and is bordered on the south by the Dublin Mountains, part of the Wicklow Mountains range. Dublin is the largest city by population on the island of Ireland; at the 2022 census of Ireland, 2022 census, the city council area had a population of 592,713, while the city including suburbs had a population of 1,263,219, County Dublin had a population of 1,501,500. Various definitions of a metropolitan Greater Dublin Area exist. A settlement was established in the area by the Gaels during or before the 7th century, followed by the Vikings. As the Kingdom of Dublin grew, it became Ireland's principal settlement by the 12th century Anglo-Norman invasion of Ireland. The city expanded rapidly from the 17th century and was briefly the second largest in the British Empire and sixth largest in Western Europ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflector Sight
A reflector sight or reflex sight is an optical sight that allows the user to look through a partially reflecting glass element and see an aiming point or some image (helping to aim the device, to which the sight is attached, on the target) superimposed on the field of view. These sights work on the simple optical principle that anything (such as an illuminated reticle) at the focus of a lens or curved mirror will appear to be sitting in front of the viewer at infinity. Reflector sights employ some form of "reflector" to allow the viewer to see the infinity image and the field of view at the same time, either by bouncing the image created by lens off a slanted glass plate, or by using a mostly clear curved glass reflector that images the reticle while the viewer looks through the reflector. Since the reticle image is at infinity, it stays in alignment with the device to which the sight is attached regardless of the viewer's eye position to the sight, removing most of the parallax ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Night Vision
Night vision is the ability to see in low-light conditions, either naturally with scotopic vision or through a night-vision device. Night vision requires both sufficient spectral range and sufficient intensity range. Humans have poor night vision compared to many animals such as cats, dogs, foxes and rabbits, in part because the human eye lacks a tapetum lucidum, tissue behind the retina that reflects light back through the retina thus increasing the light available to the photoreceptors. Types of ranges Spectral range Night-useful spectral range techniques can sense radiation that is invisible to a human observer. Human vision is confined to a small portion of the electromagnetic spectrum called visible light. Enhanced spectral range allows the viewer to take advantage of non-visible sources of electromagnetic radiation (such as near-infrared or ultraviolet radiation). Some animals such as the mantis shrimp and trout can see using much more of the infrared and/or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polarization (waves)
, or , is a property of transverse waves which specifies the geometrical orientation of the oscillations. In a transverse wave, the direction of the oscillation is perpendicular to the direction of motion of the wave. One example of a polarized transverse wave is vibrations traveling along a taut string, for example, in a musical instrument like a guitar string. Depending on how the string is plucked, the vibrations can be in a vertical direction, horizontal direction, or at any angle perpendicular to the string. In contrast, in longitudinal waves, such as sound waves in a liquid or gas, the displacement of the particles in the oscillation is always in the direction of propagation, so these waves do not exhibit polarization. Transverse waves that exhibit polarization include electromagnetic waves such as light and radio waves, gravitational waves, and transverse sound waves ( shear waves) in solids. An electromagnetic wave such as light consists of a coupled oscillating el ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telescopic Sight
A telescopic sight, commonly called a scope informally, is an optical sighting device based on a refracting telescope. It is equipped with some form of a referencing pattern – known as a ''reticle'' – mounted in a focally appropriate position in its optical system to provide an accurate point of aim. Telescopic sights are used with all types of systems that require magnification in addition to reliable visual aiming, as opposed to non-magnifying iron sights, reflector (reflex) sights, holographic sights or laser sights, and are most commonly found on long-barrel firearms, particularly rifles, usually via a scope mount. Similar devices are also found on other platforms such as artillery, tanks and even aircraft. The optical components may be combined with optoelectronics to add night vision or smart device features. History The first experiments directed to give shooters optical aiming aids go back to the early 17th century. For centuries, different optical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Rifle Association Of America
The National Rifle Association of America (NRA) is a gun rights advocacy group based in the United States. Founded in 1871 to advance rifle marksmanship, the modern NRA has become a prominent Gun politics in the United States, gun rights lobbying organization while continuing to teach Gun safety, firearm safety and competency. The organization also publishes several magazines and sponsors competitive marksmanship events. The group claimed nearly 5 million members though that figure has not been independently confirmed. The NRA is among the most influential advocacy groups in U.S. politics. The NRA Institute for Legislative Action (NRA-ILA) is its lobbying division, which manages its political action committee (PAC), the Political Victory Fund (PVF). Over its history, the organization has influenced legislation, participated in or initiated lawsuits, and endorsed or opposed various candidates at local, state, and federal levels. Some notable lobbying efforts by the NRA-ILA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Rifleman
''American Rifleman'' is a United States–based monthly shooting and firearms interest publication, owned by the National Rifle Association of America (NRA). It is the 33rd-most-widely-distributed consumer magazine and the NRA's primary magazine. The magazine has its headquarters in Fairfax, Virginia. History Arthur Corbin Gould, an avid shooter and member of the Massachusetts Rifle Association, published ''The Rifle'' in 1885 as an effort to focus discussion on the sport of rifle shooting. ''The Rifle'' later changed its title to ''Shooting and Fishing'' in 1888, branching out into other outdoor sports. In 1894, while the magazine was titled ''Shooting and Fishing'', Gould attended the National Rifle Association matches held at Sea Girt and was impressed with the level of competition, leading him to write several editorials urging the public to join. This call eventually led to the revitalization of the NRA and established a board of directors to help manage the nationwi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meniscus Corrector
A meniscus corrector is a negative meniscus lens that is used to correct spherical aberration in image-forming optical systems such as catadioptric telescopes. It works by having the equal but opposite spherical aberration of the objective it is designed to correct (usually a spherical mirror). Types Meniscus correctors are used as full aperture correctors, most commonly in a Maksutov telescope sub type called the Gregory or “spot” Maksutov–Cassegrain telescope. They are also used in the Bouwers meniscus telescope. There are Maksutov variations that use the same principle but place the meniscus lens as a sub-aperture corrector near the focus of the objective. There are other sub-aperture meniscus corrector catadioptric telescopes such as the Argunov–Cassegrain telescope and the Klevtsov–Cassegrain telescope. Invention The idea of using the spherical aberration of a meniscus lens to correct the opposite aberration in a spherical objective dates back as far as W. ... [...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 1874 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 1874 by a French military engineer named Colonel Alphonse Mangin as a subs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
