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Prism Sight
A prism sight or prismatic sight, sometimes also called prism scope or prismatic scope, is a type of telescopic sight which uses a reflective prism for its erect image, image-erecting system, instead of the series of relay lenses found in traditional telescopic sights. The use of prisms makes it possible to construct a shorter and lighter sight, or with an offset between the eyepiece and objective (optics), objective Coordinate axis, axes, although restricting the achievable range of magnification. Description Prism sights are a type of telescopic sight with similar features and limitations. Most prism sights use roof prisms commonly seen in compact binoculars and spotting scopes. The reticle is etched onto one of the internal reflection, internal reflective surface of the prism, making it easy to illuminate the reticle from the back of the prism even when active illumination is turned off. Magnification Prism sights often have fixed low-power magnification such as 1× (pari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squad Day Optic (SDO)
In military terminology, a squad is among the smallest of Military organization, military organizations and is led by a non-commissioned officer. NATO and United States, U.S. doctrine define a squad as an organization "larger than a fireteam, team, but smaller than a Section (military unit), section", while United States Army, U.S. Army doctrine further defines a squad as a "small military unit typically containing two or more Fireteam#United_States, fire teams". In American usage, a squad consists of eight to fourteen soldiers, and may be further subdivided into fireteams. Organization NATO The standard NATO symbol for a ''squad'' consists of one single dot (●) placed above a framed unit icon. United States United States Army Historically, a "squad" in the US Army was a sub-unit of a Section (military unit)#United States Armed Forces, section, consisting of from as few as two soldiers to as many as 9–10 soldiers and was originally used primarily for drill and adminis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Close Quarter Combat
Close-quarters battle (CQB), also called close-quarters combat (CQC), is a close combat situation between multiple combatants involving ranged (typically firearm-based) or melee combat. It can occur between military units, law enforcement and criminal elements, and in other similar situations. CQB is typically defined as a short duration, high intensity conflict characterized by sudden violence at close range. History Close-quarters battle has occurred since the beginning of warfare, in the form of melee combat, the use of ranged weaponry (such as slings, bows, and muskets) at close range, and the necessity of bayonets. During World War I, CQB was a significant part of trench warfare, where enemy soldiers would fight in close and narrow quarters in attempts to capture trenches. The origins of modern close-quarters battle lie in the combat methods pioneered by Assistant Commissioner William E. Fairbairn of the Shanghai Municipal Police, the police force of the Shanghai Interna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Repeating Rifle
A repeating rifle is a single-barreled rifle capable of repeated discharges between each ammunition reload. This is typically achieved by having multiple cartridges stored in a magazine (within or attached to the rifle) and then fed individually into the chamber by a reciprocating bolt, via either a manual or automatic action mechanism, while the act of chambering the round typically also recocks the hammer/ striker for the following shot. In common usage, the term "repeating rifle" most often refers specifically to manual repeating rifles (e.g. lever-action, pump-action, bolt-action, etc.), as opposed to self-loading rifles, which use the recoil, gas, or blowback of the previous shot to cycle the action and load the next round, even though all self-loading firearms are technically a subcategory of repeating firearms. Repeating rifles were a significant advance over the preceding single-shot, breechloading rifles when used for military combat, as they allowed a much grea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
M1903 Springfield
The M1903 Springfield, officially the U.S. Rifle, Caliber .30, M1903, is an American five-round magazine-fed, bolt-action service repeating rifle, used primarily during the first half of the 20th century. The M1903 was first used in combat during the Philippine-American War and was officially adopted by the United States as the standard infantry rifle on 19 June 1903. It saw service in World War I and was replaced by the faster-firing semi-automatic eight-round M1 Garand starting in 1936. However, the M1903 remained a standard-issue infantry rifle during World War II, since the U.S. entered the war without sufficient M1 rifles to arm all troops. It also was used as a sniper rifle during World War II, the Korean War and the Vietnam War. It remains popular as a civilian firearm, collector's piece, a competitive shooting rifle and as a military drill rifle. History Background During the 1898 war with Spain, the Mauser M1893 used by the Spanish Army gained a deadly reputat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Army
The United States Army (USA) is the primary Land warfare, land service branch of the United States Department of Defense. It is designated as the Army of the United States in the United States Constitution.Article II, section 2, clause 1 of the United States Constitution (1789).See alsTitle 10, Subtitle B, Chapter 301, Section 3001 It operates under the authority, direction, and control of the United States Secretary of Defense, United States secretary of defense. It is one of the six armed forces and one of the eight uniformed services of the United States. The Army is the most senior branch in order of precedence amongst the armed services. It has its roots in the Continental Army, formed on 14 June 1775 to fight against the British for independence during the American Revolutionary War (1775–1783). After the Revolutionary War, the Congress of the Confederation created the United States Army on 3 June 1784 to replace the disbanded Continental Army.Library of CongressJournals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World War I
World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting took place mainly in European theatre of World War I, Europe and the Middle Eastern theatre of World War I, Middle East, as well as in parts of African theatre of World War I, Africa and the Asian and Pacific theatre of World War I, Asia-Pacific, and in Europe was characterised by trench warfare; the widespread use of Artillery of World War I, artillery, machine guns, and Chemical weapons in World War I, chemical weapons (gas); and the introductions of Tanks in World War I, tanks and Aviation in World War I, aircraft. World War I was one of the List of wars by death toll, deadliest conflicts in history, resulting in an estimated World War I casualties, 10 million military dead and more than 20 million wounded, plus some 10 million civilian de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dial Sight No
Dial may refer to: Mechanical device *Rotary dial, a device for the input of number(s) in telephones and similar devices * Dialling, usually means to make a telephone call by turning the rotary dial or pressing the buttons *Dial (measurement), a display device in radio, measuring instruments, etc. *Mode dial, part of dSLR and SLR-like digital cameras DIAL * DIAL, an acronym for differential absorption LIDAR * DIAL, an acronym for Discovery and Launch, a network protocol * DIAL, an acronym for Digital Impact Alliance * Dunedin International Airport Limited, New Zealand *Delhi International Airport (P) Limited, Delhi, India Other * Dial (surname), people named Dial *Dial Corporation, a consumer products company that is a wholly owned subsidiary of Henkel AG & Co. KGaA. *Dial (soap), a brand of antibacterial soap and related products * Dial, West Virginia, a community in the United States * Dial (band), a Dutch progressive rock band * Dial Press, a publishing house founded in 192 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different sightline, lines of sight and is measured by the angle or half-angle of inclination between those two lines. Due to perspective (graphical), foreshortening, nearby objects show a larger parallax than farther objects, so parallax can be used to determine distances. To measure large distances, such as the distance of a planet or a star from Earth, astronomers use the principle of parallax. Here, the term ''Stellar parallax, parallax'' is the semi-angle of inclination between two sight-lines to the star, as observed when Earth is on opposite sides of the Sun in its orbit. These distances form the lowest rung of what is called "the cosmic distance ladder", the first in a succession of methods by which astronomers determine the distances to celestial objects, serving as a basis for other distance measurements in astronomy forming the higher rungs of the ladder. Because parallax ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Farsightedness
Far-sightedness, also known as long-sightedness, hypermetropia, and hyperopia, is a condition of the eye where distant objects are seen clearly but near objects appear blurred. This blur is due to incoming light being focused behind, instead of on, the retina due to insufficient accommodation by the lens. Minor hypermetropia in young patients is usually corrected by their accommodation, without any defects in vision. But, due to this accommodative effort for distant vision, people may complain of eye strain during prolonged reading. If the hypermetropia is high, there will be defective vision for both distance and near. People may also experience accommodative dysfunction, binocular dysfunction, amblyopia, and strabismus. Newborns are almost invariably hypermetropic, but it gradually decreases as the newborn gets older. There are many causes for this condition. It may occur when the axial length of eyeball is too short or if the lens or cornea is flatter than normal. Cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nearsightedness
Myopia, also known as near-sightedness and short-sightedness, is an eye condition where light from distant objects focuses in front of, instead of on, the retina. As a result, distant objects appear blurry, while close objects appear normal. Other symptoms may include headaches and eye strain. Severe myopia is associated with an increased risk of macular degeneration, retinal detachment, cataracts, and glaucoma. Myopia results from the length of the eyeball growing too long or less commonly the lens being too strong. It is a type of refractive error. Diagnosis is by the use of cycloplegics during eye examination. Tentative evidence indicates that the risk of myopia can be decreased by having young children spend more time outside. This decrease in risk may be related to natural light exposure. Myopia can be corrected with eyeglasses, contact lenses, or by refractive surgery. Eyeglasses are the simplest and safest method of correction. Contact lenses can provide a relativel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dioptre
A dioptre ( British spelling) or (American spelling), symbol dpt or D, is a unit of measurement with dimension of reciprocal length, equivalent to one reciprocal metre, . It is normally used to express the optical power of a lens or curved mirror, which is a physical quantity equal to the reciprocal of the focal length, expressed in metres. For example, a 3-dioptre lens brings parallel rays of light to focus at metre. A flat window has an optical power of zero dioptres, as it does not cause light to converge or diverge. Dioptres are also sometimes used for other reciprocals of distance, particularly radii of curvature and the vergence of optical beams. The main benefit of using optical power rather than focal length is that the thin lens formula has the object distance, image distance, and focal length all as reciprocals. Additionally, when relatively thin lenses are placed close together their powers approximately add. Thus, a thin 2.0-dioptre lens placed close to a th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holographic Sight
A holographic weapon sight or holographic diffraction sight is a non- magnifying gunsight that allows the user to look through a glass optical window and see a holographic reticle image superimposed at a distance on the field of view. The hologram of the reticle is built into the window and is illuminated by a laser diode. History The first-generation holographic sight was introduced by EOTech—then an ERIM subsidiary—at the 1996 SHOT Show,Jane's international defence review: IDR.: Volume 34, page 76 under the trade name HoloSight by Bushnell, with whom the company was partnered at the time, initially aiming for the civilian sport shooting and hunting market. It won the Optic of the Year Award from the Shooting Industry Academy of Excellence. EOTech was the only company that manufactured holographic sights until early 2017, when Vortex introduced the Razor AMG UH-1 into the market as a competing product. As Vortex introduced the Gen II model on mid July, 2020 which later r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
