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Prism Sight
A prism sight or prismatic sight, sometimes also called prism scope or prismatic scope, is a type telescopic sight which uses a roof prism for its 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 axes. History Prisms have been used in periscopes and binoculars for a long time. Thomas H. Doughty of the United States Navy invented a prismatic periscope for use in the American Civil War (1861–1865), which was a further development of the mirror-based periscope invented by Marie-Davey in 1854. Binoculars with prisms appeared in the 1890s. During World War I, the US Army chose to equip the M1903 Springfield repeating rifle for the sniper rifle role by mounting a prismatic sight developed by the Warner & Swasey Company. It was a short and compact sight, and the prisms allowed the objective to be angl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squad Day Optic (SDO)
In military terminology, a squad is among the smallest of military organizations and is led by a non-commissioned officer. NATO and US doctrine define a squad as an organization "larger than a team, but smaller than a section." while US Army doctrine further defines a squad as a "small military unit typically containing two or more fire teams." In US 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, consisting of from as few as two soldiers to as many as 12 and was originally used primarily for drill and administrative purposes (e.g., billeting, messing, working parties, etc.). The smallest tactical sub-unit being the section, which was also known as a half-platoon (the platoon itself being a half comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Field Of View
The field of view (FoV) is the extent of the observable world that is seen at any given moment. In the case of optical instruments or sensors it is a solid angle through which a detector is sensitive to electromagnetic radiation. Humans and animals In the context of human and primate vision, the term "field of view" is typically only used in the sense of a restriction to what is visible by external apparatus, like when wearing spectacles or virtual reality goggles. Note that eye movements are allowed in the definition but do not change the field of view when understood this way. If the analogy of the eye's retina working as a sensor is drawn upon, the corresponding concept in human (and much of animal vision) is the visual field. It is defined as "the number of degrees of visual angle during stable fixation of the eyes".Strasburger, Hans; Pöppel, Ernst (2002). Visual Field. In G. Adelman & B.H. Smith (Eds): ''Encyclopedia of Neuroscience''; 3rd edition, on CD-ROM. El ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astigmatism
Astigmatism is a type of refractive error due to rotational asymmetry in the eye's refractive power. This results in distorted or blurred vision at any distance. Other symptoms can include eyestrain, headaches, and trouble driving at night. Astigmatism often occurs at birth and can change or develop later in life. If it occurs in early life and is left untreated, it may result in amblyopia. The cause of astigmatism is unclear; however, it is believed to be partly related to genetic factors. The underlying mechanism involves an irregular curvature of the cornea and protective reaction changes in the lens of the eye, called lens astigmatism, that has the same mechanism as spasm of accomodation. Diagnosis is by an eye examination called autorefractor keratometry (objective, allows to see lens and cornea components of astigmatism) and subjective refraction, but subjective methods are almost always inaccurate, if lens astigmatism is not fully removed first with a week of e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SA80 A2 (L85A2) 5
SA8 may refer to: * SA-8 Gecko, the NATO reporting name for the 9K33 Osa surface-to-air missile system * SA8 (detergent), the brand of laundry detergent sold by Amway * SA-8, a rocket launch used to launch mission AS-104, a test flight in the U.S. NASA Apollo Program moon project * Stits SA-8 Skeeto, an ultralight aircraft * post code SA8, a post code in Swansea, Wales, UK See also * Fiat SA8/75, a Fiat Aviazione Fiat Aviazione was an Italian aircraft manufacturer, at one time part of the Fiat group, focused mainly on military aviation. After World War I, Fiat consolidated several Italian small aircraft manufacturers, like Pomilio and Ansaldo. Most famous ... aircraft engine * SA (other) {{Letter-NumberCombDisambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
L129A1 Sharpshooter Rifle MOD 45162218
L1, L01, L.1, L 1 or L-1 may refer to: Mathematics, science and technology Math *L1 distance in mathematics, used in taxicab geometry * L1, the space of Lebesgue integrable functions * ℓ1, the space of absolutely convergent sequences Science *L1 family, a protein family of cell adhesion molecules *L1 (protein), a cell adhesion molecule *, Lagrangian point 1, the most intuitive position for an object to be gravitationally stationary relative to two larger objects (such as a satellite with respect to the Earth and Moon) *Anthranilic acid, also called vitamin L1 *The first lumbar vertebra of the vertebral column in human anatomy * The first larval stage in the ''Caenorhabditis elegans'' worm development Technology *L1, one of the frequencies used by GPS systems (see GPS frequencies) *L1, the common name for the Soviet space effort known formally as Soyuz 7K-L1, designed to launch men from the Earth to circle the Moon without going into lunar orbit *ISO/IEC 8859-1 (Lati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spotting Scope
A spotting scope is a compact high-power telescope optimized for detailed observation of distant objects. They are used as portable optical enhancement devices for various outdoor activities such as birdwatching, skygazing and other naturalist activities, for hunting and target shooting to verify a marksman's shot placements, for tactical ranging and surveillance, and for any other application that requires higher magnification than ordinary binoculars (typically 20× to 60×). The light-gathering power and resolution of a spotting scope is determined by the diameter of the objective lens, typically between . The larger the objective, the more massive and expensive the telescope. The optical assembly has a small refracting objective lens, an internal image-erecting system, and an eyepiece that is usually removable. The image-erecting system may use relay lenses, prisms such as Porro or roof prisms, or a catadioptric system of the Schmidt or Maksutov design. Spotting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roof Prism
A roof prism, also called a Dachkanten prism or Dach prism (from German: ''Dachkante'', lit. "roof edge"), is a reflective prism containing a section where two faces meet at a 90° angle, resembling the roof of a building and thus the name. Reflection from the two 90° faces returns an image that is flipped laterally across the axis where the faces meet. Characteristic for a roof prism is that the beam is split in half, with one half of the beam hitting first one face then the other face, while it is invert for the other half of the beam. Therefore, a roof prism can be used only with some distance to focal planes, or the "edge" of the roof would introduce slight distortions. Furthermore, the angle between the two faces has to be very close to 90°, or image quality would be degraded. The simplest roof prism is the Amici roof prism, with other common roof prism designs being the Abbe–Koenig prism, the Schmidt–Pechan prism and probably the best known being the roof pentapr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
70th Anniversary Of The People's Republic Of China
The 70th anniversary of the founding of the People's Republic of China () was observed with a series of ceremonial events including a grand military parade as its spotlight to celebrate National Day of the People's Republic of China that took place on 1 October 2019 in Beijing. It was the largest military parade and mass pageant in Chinese history. Chinese Communist Party (CCP) general secretary Xi Jinping, who was the guest of honour, gave the holiday address to the nation and Chinese expatriates before inspecting the formations along Chang'an Avenue. Premier Li Keqiang was the master of ceremonies and General Yi Xiaoguang was the chief commander of the parade. Background The CCP had defeated the Kuomintang Party following the Chinese Civil War, which occurred intermittently between 1927 and 1950 In the aftermath of the civil war, the Kuomintang and its loyalists then retreated to the island of Taiwan, formerly a prefecture of the Qing Empire, which had been under J ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
QBZ-191
The QBZ-191 Automatic Rifle () is a Chinese assault rifle chambered for the 5.8×42mm intermediate cartridge, designed and manufactured by Norinco as a new-generation service rifle for the People's Liberation Army (PLA) and People's Armed Police (PAP). The rifle's designation "QBZ" stands for "light weapon (Qīng Wŭqì) - rifle (Bùqiāng) - automatic (Zìdòng)". The new rifle was formally revealed at the 70th Anniversary National Day military parade on October 1, 2019, carried by troopers of the PLA Ground Force and People's Armed Police. History Chinese military initiated the development of conventional layout rifles in 2014, with multiple manufacturers involved in the development and bidding process. Various prototypes of the new weapon platform were leaked online in 2016 and 2017. The QBZ-191 rifle was designed by Norinco's 208 Research Institute, which also designed the QBZ-95 assault rifle. According to the director of the 208 Research Institute, QBZ-191 is a compone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Special Operations Command
The United States Special Operations Command (USSOCOM or SOCOM) is the unified combatant command charged with overseeing the various special operations component commands of the Army, Marine Corps, Navy, and Air Force of the United States Armed Forces. The command is part of the Department of Defense and is the only unified combatant command created by an Act of Congress. USSOCOM is headquartered at MacDill Air Force Base in Tampa, Florida. The idea of an American unified special operations command had its origins in the aftermath of Operation Eagle Claw, the disastrous attempted rescue of hostages at the American embassy in Iran in 1980. The ensuing investigation, chaired by Admiral James L. Holloway III, the retired Chief of Naval Operations, cited lack of command and control and inter-service coordination as significant factors in the failure of the mission. Since its activation on 16 April 1987, U.S. Special Operations Command has participated in many operations, fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Marine Corps
The United States Marine Corps (USMC), also referred to as the United States Marines, is the maritime land force service branch of the United States Armed Forces responsible for conducting expeditionary and amphibious operations through combined arms, implementing its own infantry, artillery, aerial, and special operations forces. The U.S. Marine Corps is one of the eight uniformed services of the United States. The Marine Corps has been part of the U.S. Department of the Navy since 30 June 1834 with its sister service, the United States Navy. The USMC operates installations on land and aboard sea-going amphibious warfare ships around the world. Additionally, several of the Marines' tactical aviation squadrons, primarily Marine Fighter Attack squadrons, are also embedded in Navy carrier air wings and operate from the aircraft carriers. The history of the Marine Corps began when two battalions of Continental Marines were formed on 10 November 1775 in Philadelphia as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hotchkiss M1909 Benét–Mercié Machine Gun
The Hotchkiss M1909 machine gun was a light machine gun of the early 20th century, developed and built by Hotchkiss et Cie. It was also known as the Hotchkiss Mark I, Hotchkiss Portative and M1909 Benét–Mercié. Design It was based on a design by Austrian nobleman and Army officer, Adolf Odkolek von Újezd, who sold the manufacturing rights to Hotchkiss in 1893. Several improved versions were designed by Hotchkiss's American manager, Laurence Benét and his French assistant, Henri Mercié. It was gas-operated and air-cooled, had a maximum range of and weighed 12 kg (27 lb). Initial models were fed by a 30-round feed strip but later models could be either strip-fed or belt-fed. The U.S. types had a bipod, while some others used a small tripod. This tripod, fitted under the firearm, could be moved with the weapon, and thus was very different from larger, heavier tripods of the period. Manufacture Production began at the Hotchkiss factory in Saint-Denis, Paris, but i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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