1.
Sight (device)
–
A sight is a device used to assist aligning or aim weapons, surveying instruments, or other items by eye. Sights can be a set or system of markers that have to be aligned together as well as aligned with the target. They can also be optical devices that allow the user to see the image of an aiming point in the same focus as the target. These include telescopic sights and reflector sights, There are also sights that project an aiming point onto the target itself, such as laser 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 navigational tools. On weapons, these sights are usually formed by rugged metal parts, giving them the iron sights. On many types of weapons they are built-in and may be fixed, adjustable, or marked for elevation, windage, target speed and they are also classified in forms of notch or aperture. Optical sights use optics that give the user an image of an aiming point or pattern superimposed at the same focus as the target. Telescopic sights are used on a range of devices including guns, surveying equipment. These sights have been around for over 100 years and been used on all types of weapons, reflector sights were first used as a weapon sight in German aircraft towards the end of World War I. Collimator sight Holographic weapon sight There are many types of sighting devices and they can be fixed, mechanical, optical, computational, or a mixture of all of these attributes
Sight (device)
–
A Cadet looks through a machine gun sight
Sight (device)
–
Picture through an aperture (or closed) iron sight on an H&K
MP5 submachine gun
Sight (device)
–
A view through the 20× power telescopic sight
Sight (device)
–
A
circumferentor featuring a pair of slotted sights effectively constituting an
alidade
2.
Refracting telescope
–
A refracting telescope is a type of optical telescope that uses a lens as its objective to form an image. The refracting telescope design was used in spy glasses and astronomical telescopes but is also used for long focus camera lenses. A refractors magnification is calculated by dividing the length of the objective lens by that of the eyepiece. Refractors were the earliest type of optical telescope, Galileo Galilei, happening to be in Venice in about the month of May 1609, heard of the invention and constructed a version of his own. Galileo then communicated the details of his invention to the public, all refracting telescopes use the same principles. The objective in a refracting telescope refracts or bends light and this refraction causes parallel light rays to converge at a focal point, while those not parallel converge upon a focal plane. The telescope converts a bundle of rays to make an angle α. The ratio β/α is called the angular magnification and it equals the ratio between the retinal image sizes obtained with and without the telescope. Refracting telescopes can come in different configurations to correct for image orientation. Because the image was formed by the bending of light, or refraction, the design Galileo Galilei used in 1609 is commonly called a Galilean telescope. It used a convergent objective lens and a divergent eyepiece lens, a Galilean telescope, because the design has no intermediary focus, results in a non-inverted and upright image. Galileo’s best telescope magnified objects about 30 times, because of flaws in its design, such as the shape of the lens and the narrow field of view, the images were blurry and distorted. Despite these flaws, the telescope was still enough for Galileo to explore the sky. The Galilean telescope could view the phases of Venus, and was able to see craters on the Moon, parallel rays of light from a distant object would be brought to a focus in the focal plane of the objective lens. The eyepiece lens intercepts these rays and renders them parallel once more, non-parallel rays of light from the object traveling at an angle α1 to the optical axis travel at a larger angle after they passed through the eyepiece. This leads to an increase in the apparent angular size and is responsible for the perceived magnification, the final image is a virtual image, located at infinity and is the same way up as the object. The Keplerian telescope, invented by Johannes Kepler in 1611, is an improvement on Galileos design and it uses a convex lens as the eyepiece instead of Galileos concave one. The advantage of this arrangement is that the rays of light emerging from the eyepiece are converging and this allows for a much wider field of view and greater eye relief, but the image for the viewer is inverted
Refracting telescope
–
Image of a refracting telescope from the
Cincinnati Observatory in 1848
Refracting telescope
–
Woodcut illustration of a 46 m (150 ft) focal length Keplerian astronomical refracting telescope built by Johannes Hevelius. From his book Machina coelestis (first part), published in 1673.
Refracting telescope
–
The 1,000-millimeter (40 in) refractor, at
Yerkes Observatory, the largest achromatic refractor ever put into astronomical use
Refracting telescope
–
The Great Refractor at the
Astrophysical Institute Potsdam,
Germany
3.
Reticle
–
Today, engraved lines or embedded fibers may be replaced by a computer-generated image superimposed on a screen or eyepiece. There are many variations of reticles, this article concerns itself mainly with a simple reticle, crosshairs. Crosshairs are most commonly represented as intersecting lines in the shape of a cross, +, though variations exist, including dots, posts, circles, scales, chevrons. The reticle is said to have been invented by Robert Hooke, another candidate as inventor is the amateur astronomer William Gascoigne, who predated Hooke. Telescopic sights for firearms, generally just called scopes, are probably the device most often associated with crosshairs, motion pictures and the media often use a view through crosshairs as a dramatic device, which has given crosshairs wide cultural exposure. Thicker bars are easier to discern against a complex background. The most popular types of cross-hair in modern scopes are variants on the duplex cross-hair, with bars that are thick on the perimeter, the thick bars allow the eye to quickly locate the center of the reticle, and the thin lines in the center allow for precision aiming. The thin bars in a duplex reticle may also be designed to be used as a measure, called a 30/30 reticle, the thin bars on such a reticle span 30 minutes of an arc, which happens to be close to 30 inches at 100 yards. This enables an experienced shooter to deduce the range within an acceptable error limit, originally crosshairs were constructed out of hair or spiderweb, these materials being sufficiently thin and strong. Many modern scopes use wire crosshairs, which can be flattened to various degrees to change the width and these wires are usually silver in color, but appear black when backlit by the image passing through the scopes optics. The advantage of wire crosshairs is that they are tough and durable. The first suggestion for etched glass reticles was made by Philippe de La Hire in 1700 and his method was based on engraving the lines on a glass plate with a diamond point. Many modern crosshairs are actually etched onto a plate of glass. Reticles may be illuminated, either by a plastic or fiber optic light pipe collecting ambient light or, in low light conditions, a graticule is another term for reticle, frequently encountered in British and British military technical manuals, and came into common use during World War One. The reticle may be located at the front or rear focal plane of the telescopic sight, american and European high end optics manufacturers often leave the customer the choice between a FFP or SFP mounted reticle. Collimated reticles are created using refractive or reflective optical collimators to generate an image of an illuminated or reflective reticle. These types of sights are used on surveying/triangulating equipment, to aid celestial telescope aiming, holographic weapon sights use a holographic image of a reticle at finite set range built into the viewing window and a collimated laser diode to illuminate it. The use of a hologram also eliminates the need for image dimming narrow band reflective coatings, a downside to the holographic weapon sight can be the weight and shorter battery life
Reticle
–
The day and low-light reticles of the integral
reflex sight used on the
FN P90 / PS90 USG models
Reticle
–
A comparison of different reticles used in telescopic sights. The lower right represents a reticle found in the
PSO-1 scope of a Russian
SVD dedicated marksman rifle.
4.
Firearm
–
A firearm is a portable gun - a barreled weapon that launches one or more projectiles, often driven by the action of an explosive force. The first primitive firearms originated in 13th-century China when the fire lance was combined with projectiles. The technology gradually spread through the rest of East Asia, South Asia, older firearms typically used black powder as a propellant, but modern firearms use smokeless powder or other propellants. Most modern firearms have rifled barrels to impart spin to the projectile for improved flight stability, modern firearms can be described by their caliber or in the case of shotguns their gauge, by the type of action employed together with the usual means of deportment. The word firearms usually is used in a sense restricted to small arms, shooters aim firearms at their targets with hand-eye co-ordination, using either iron sights or optical sights. The accurate range of pistols generally does not exceed 100 yards, while most rifles are accurate to 550 yards using iron sights, some purpose-built sniper rifles are accurate to ranges of more than 2,200 yards. The smallest of all firearms is the handgun, there are three common types of handguns, single-shot pistols, revolvers, and semi-automatic pistols. Revolvers have a number of firing chambers or charge holes in a revolving cylinder, semi-automatic pistols have a single fixed firing chamber machined into the rear of the barrel, and a magazine so they can be used to fire more than one round. Each press of the fires a cartridge, using the energy of the cartridge to activate the mechanism so that the next cartridge may be fired immediately. This is opposed to double-action revolvers which accomplish the end using a mechanical action linked to the trigger pull. Prior to the 19th century, virtually all handguns were single-shot muzzleloaders, with the invention of the revolver in 1818, handguns capable of holding multiple rounds became popular. Certain designs of auto-loading pistol appeared beginning in the 1870s and had largely supplanted revolvers in military applications by the end of World War I. By the end of the 20th century, most handguns carried regularly by military, police and civilians were semi-automatic, both designs are common among civilian gun owners, depending on the owners intention. A long gun is any firearm that is larger than a handgun and is designed to be held. Early long arms, from the Renaissance up to the century, were generally smoothbore firearms that fired one or more ball shot. Most modern long guns are either rifles or shotguns, both are the successors of the musket, diverging from their parent weapon in distinct ways. A rifle is so named for the spiral fluting machined into the surface of its barrel. Shotguns are predominantly smoothbore firearms designed to fire a number of shot, shotguns are also capable of firing single slugs, or specialty rounds such as bean bags, tear gas or breaching rounds
Firearm
–
US Navy sailor shoots a firearm at a target.
Firearm
–
A
Colt Single Action Army revolver
Firearm
–
A
Glock 17 semi-automatic
pistol
Firearm
–
Springfield Armory
M1903 rifle
5.
Rifle
–
A rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves cut into the barrel walls. The raised areas of the rifling are called lands, which contact with the projectile. When the projectile leaves the barrel, this spin lends gyroscopic stability to the projectile and prevents tumbling and this allows the use of aerodynamically-efficient bullets and thus improves range and accuracy. The word rifle originally referred to the grooving, and a rifle was called a rifled gun, the word rifle is now used for any long hand-held aimed device activated by a trigger, such as Air rifles and the Personnel halting and stimulation response rifle. Rifles are used in warfare, hunting and shooting sports, formerly, rifles only fired a single projectile with each squeeze of the trigger. Modern rifles are capable of firing more than one round per trigger squeeze, some fire in an automatic mode. Thus, modern automatic rifles overlap to some extent in design, in fact, many light machine guns are adaptations of existing automatic rifle designs. A militarys light machine guns are chambered for the same caliber ammunition as its service rifles. Generally, the difference between a rifle and a machine gun comes down to weight, cooling system. Modern military rifles are fed by magazines, while machine guns are generally belt-fed, many machine guns allow the operator to quickly exchange barrels in order to prevent overheating, whereas rifles generally do not. Most machine guns fire from a bolt in order to reduce the danger of cook-off. Machine guns are often crewed by more than one soldier, the rifle is an individual weapon, the term rifle is sometimes used to describe larger crew-served rifled weapons firing explosive shells, for example, recoilless rifles. In many works of fiction a rifle refers to any weapon that has a stock and is shouldered before firing, the origins of rifling are difficult to trace, but some of the earliest practical experiments seem to have occurred in Europe during the 15th century. Archers had long realized that a twist added to the feathers of their arrows gave them greater accuracy. This might also have led to a increase in accuracy. Rifles were created as an improvement in the accuracy of smooth bore muskets, the black powder used in early muzzle-loading rifles quickly fouled the barrel, making loading slower and more difficult. Since musketeers could not afford to take the time to stop and clean their barrels in the middle of a battle, rifles were limited to use by sharpshooters, muskets were smoothbore, large caliber weapons using ball-shaped ammunition fired at relatively low velocity. Due to the high cost and great difficulty of manufacturing, and the need to load readily from the muzzle
Rifle
Rifle
–
Rifling in a
.35 Remington microgroove rifled barrel
Rifle
Rifle
6.
Iron sights
–
Iron sights are typically composed of two component sights, formed by metal blades, a rear sight mounted perpendicular to the line of sight and a front sight that is a post, bead, or ring. Open sights use a notch of some sort as the rear sight, civilian, hunting, and police firearms usually feature open sights, while many military battle rifles employ aperture sights. The earliest and simplest iron sights are fixed and cannot be easily adjusted, many iron sights are designed to be adjustable, so that the sights can be adjusted for elevation or windage. On many firearms it is the sight that is adjustable. For precision applications such as hunting or sniping, the sights are usually replaced by a telescopic sight. Iron sights may still be fitted alongside other sighting devices for back-up usage, iron sights provide horizontal and vertical reference points that allow the shooter to train the weapon. Rear sights are mounted in a dovetail on the barrel or receiver, closer to the eye of the shooter. Front sights are mounted to the barrel by dovetailing, soldering, screwing, or staking close to the muzzle, frequently on a ramp. Some front sight assemblies include a detachable hood intended to reduce glare, with typical blade or post iron sights, the shooter would center the front post in the notch of the rear sight and the tops of both sights should be level. Since the eye is capable of focusing on one plane, and the rear sight, front sight. At 1,000 m, that same misalignment would be magnified 100 times, sights for shotguns used for shooting small, moving targets work quite differently. The rear sight is completely discarded, and the reference point is provided by the correct. A brightly colored round bead is placed at the end of the barrel, often, this bead will be placed along a raised, flat rib, which is usually ventilated to keep it cool and reduce mirage effects from a hot barrel. This method of aiming is not as precise as that of a front sight/rear sight combination, but it is faster. Some shotguns also provide a mid-bead, which is a smaller bead located halfway down the rib, open sights generally are used where the rear sight is at significant distance from the shooters eye. They provide minimum occlusion of the view, but at the expense of precision. Open sights generally use either a square post or a bead on a post for a front sight, to use the sight, the post or bead is positioned both vertically and horizontally in the center of the rear sight notch. For a center hold, the front sight is positioned on the center of the target, for a 6oclock hold, the front sight is positioned just below the target and centered horizontally
Iron sights
–
Sight picture through iron sights of an H&K
MP5 submachine gun. The
annular shroud around the front post sight is aligned with the rear peep sight to ensure the weapon is properly trained.
Iron sights
–
Aerial gunnery iron ring sight on a GAU-21 that allows for compensating for the roll-pitch-yaw of an aircraft.
Iron sights
–
Rear, rotating
diopter drum sight of a
SIG SG 550 assault rifle. The viewing aperture above the "3" (denoting the 300 m setting) can be seen
Iron sights
–
Pictures taken under identical conditions through large (left) and small (right) diameter aperture sights, with camera focused on front sight
7.
Reflector sight
–
These sights work on the simple optical principle that anything at the focus of a lens or curved mirror will look like it is sitting in front of the viewer at infinity. Since their invention in 1900, reflector sights have come to be used as gun sights on all kinds of weapons. They were used on aircraft, in a limited capacity in World War I, widely used in World War II. Reflector sights are used in civilian applications such as sights on surveying equipment, optical telescope pointing aids. The collimated reticle image can also be seen at any eye position in the volume of collimated light created by the sight behind the optical window. Eye movement perpendicular to the optical axis will make the reticle image move in exact relationship to eye position in the cylindrical column of light created by the collimating optics. A common type uses a lens and a beam splitter. This type tends to be bulky since it requires at least two components, the lens and the beam splitter/glass plate. The reticle collimation optics are situated at 90° to the optical path making lighting difficult, usually needing additional electric illumination, condensing lenses and this type is most often seen as the red dot type used on small arms. It is also possible to place the reticle between the viewer and the mirror at the mirrors focus. The reticle itself is too close to the eye to be in focus, the viewing portion of a reflector sight does not use any refractive optical elements, it is simply a projected reticle bounced off a beam splitter or curved mirror right into the users eye. This gives it the characteristics of not needing considerable experience and skill to use. The primary drawback of reflector sight is that they need some way to illuminate the reticle to function, reticles illuminated by ambient light are hard to use in low light situations, and sights with electrical illumination stop functioning altogether if that system fails. The idea of a reflector sight originated in 1900 with Irish optical designer and this arrangement would be of course equally impracticable for obvious reasons but it is instanced to show that a beam of light has the necessary qualifications for our purposes. It was noted soon after its invention that the sight could be an alternative to iron sights. The reflector sight was first used on German fighter aircraft in 1918, through their development in the 1930s and into World War II the sight was also being referred to in some applications by the abbreviation reflex sight. Reflector sights were invented as an improved gun-sight and since their invention they have adapted to many types of weapons. When used with different types of guns, reflector sights are considered an improvement over simple iron sights, the reflector sights single, parallax-free virtual image, in focus with the target, removes this aiming problem, helping poor, average, and expert shooters alike
Reflector sight
–
Prototype of the Grubb reflector sight attached to a rifle
Reflector sight
–
Diagram of three types of reflector sights. The top uses a collimating lens (CL) and a beam splitter (B) to create a
virtual image at infinity (V) of a reticle (R). The bottom two use half silvered curved mirrors (CM) as the collimating optics
Reflector sight
–
German paratrooper looks through the reflector sight of the Flakvisier 40 gunsight on a FlaK 38 anti-aircraft gun (1944), one of the more sophisticated sights at the time
Reflector sight
–
Longitudinal cross-section of a basic reflector sight for pre-WWII German fighter planes (1937 German Revi C12/A)
8.
Laser sight
–
Many scientific, military, medical and commercial laser applications have been developed since the invention of the laser in 1958. The coherency, high monochromaticity, and ability to reach extremely high powers are all properties which allow for specialized applications. Laser based lidar technology has application in geology, seismology, remote sensing, lasers have been used aboard spacecraft such as in the Cassini-Huygens mission. In astronomy, lasers have been used to create artificial laser guide stars, lasers may also be indirectly used in spectroscopy as a micro-sampling system, a technique termed Laser ablation, which is typically applied to ICP-MS apparatus resulting in the powerful LA-ICP-MS. The principles of spectroscopy are discussed by Demtröder. Most types of laser are a pure source of light. By careful design of the components, the purity of the laser light can be improved more than the purity of any other light source. This makes the laser a useful source for spectroscopy. Other spectroscopic techniques based on lasers can be used to extremely sensitive detectors of various molecules. Due to the power densities achievable by lasers, beam-induced atomic emission is possible. Heat treating with lasers allows selective surface hardening against wear with little or no distortion of the component, because this eliminates much part reworking that is currently done, the laser systems capital cost is recovered in a short time. An inert, absorbent coating for laser heat treatment has also developed that eliminates the fumes generated by conventional paint coatings during the heat-treating process with CO2 laser beams. One consideration crucial to the success of a heat treatment operation is control of the laser beam irradiance on the part surface, the optimal irradiance distribution is driven by the thermodynamics of the laser-material interaction and by the part geometry. Typically, irradiances between 500-5000 W/cm^2 satisfy the constraints and allow the rapid surface heating and minimal total heat input required. For general heat treatment, a square or rectangular beam is one of the best options. For some special applications or applications where the treatment is done on an edge or corner of the part. When the Apollo astronauts visited the moon, they planted retroreflector arrays to make possible the Lunar Laser Ranging Experiment, some laser systems, through the process of mode locking, can produce extremely brief pulses of light - as short as picoseconds or femtoseconds. Such pulses can be used to initiate and analyze chemical reactions, the short pulses can be used to probe the process of the reaction at a very high temporal resolution, allowing the detection of short-lived intermediate molecules
Laser sight
–
Laser pointers
Laser sight
–
A target designator
Laser sight
–
Laser sight used by the
Israel Defense Forces during commando training
Laser sight
–
Smith & Wesson revolver equipped with a laser sight mounted on the
trigger guard.
9.
Night vision device
–
A night vision device, also known as a night optical/observation device, is an optoelectronic device that allows images to be produced in levels of light approaching total darkness. The image may be a conversion to light of both visible light and near-infrared, while by convention detection of thermal infrared is denoted thermal imaging. The image produced is typically monochrome, e. g. shades of green, NVDs are most often used by the military and law enforcement agencies, but are available to civilian users. The term usually refers to a unit, including an image intensifier tube, a protective and generally water-resistant housing. Many NVDs also include components such as a sacrificial lens. An NVD may have an IR illuminator, making it an active as opposed to passive night vision device, Night vision devices were first used in World War II and came into wide use during the Vietnam War. The technology has evolved greatly since their introduction, leading to several generations of night vision equipment with performance increasing, consequently, they are available for a wide range of applications, e. g. for gunners, drivers and aviators. The classification below was introduced by the US manufacturers through the US government. Other manufacturers do not abide by it, in 1929, Hungarian physicist Kálmán Tihanyi invented the infrared-sensitive electronic television camera for anti-aircraft defense in Britain. The first military night vision devices were introduced by the German army as early as 1939, the first devices were being developed by AEG starting in 1935. In mid-1943, first tests with infrared night-vision devices and telescopic rangefinders mounted on Panther started, two different arrangements / solutions were created and used on Panther tanks. Solution A - Sperber FG1250, with range up to 600m, was made up of one 30 cm infrared searchlight and this was matched by an earlier experimental Russian version dubbed the PAU-2 and was field tested in 1942. From late 1944 to March 1945, some Panzerkampfwagen V Panther Ausf G mounted with FG1250, were successfully tested, by the end of World War II, the German Reich had equipped approximately 50 Panther tanks, which saw combat on both the Eastern and Western Fronts. The Vampir man-portable system for infantrymen was being used with Sturmgewehr 44 assault rifles, parallel development of night vision systems occurred in the USA. The M1 and M3 infrared night sighting devices, also known as the sniperscope or snooperscope, were introduced by the US Army in World War II and they were active devices, using a large infrared light source to illuminate targets. Vladimir K. Zworykin working for the Radio Corporation of America, zworykins idea came from a former radio guided-missile. At that time infra-red was commonly called black light, a term later restricted to ultraviolet and it was not a success due to its size and cost. First generation passive devices, introduced during the Vietnam War, were an adaptation of earlier active GEN0 technology, using an S-20 photocathode, their image intensifiers produce a light amplification of around 1, 000×, but are quite bulky and require moonlight to function properly
Night vision device
–
A
U.S. Army aviator uses a pair of helmet-mounted AN/AVS-6 vision goggles. The effect on the
natural night vision of the eye is evident
Night vision device
–
A standard
telescopic sight augmented with a night vision device in front. Note that in addition to the image intensifier the NVD gathers much more light via its much larger
aperture
Night vision device
–
A
1PN51-2 night vision
reticle with markings for
range estimation
Night vision device
–
An
M16A1 rifle fitted with the AN/PVS-2 Starlight scope.
10.
William Malcolm
–
William Malcolm was a New York City merchant and officer in the American Revolution. He commanded Malcolms Regiment, with Aaron Burr as his second in command, william Malcolm was born in Glenrothes, Scotland on January 23,1745. He moved to New York City while in his twenties and established himself as an import/export merchant, Malcolm grew wealthy, and as his influence increased he took part in politics and government, including serving as a member of the New York Assembly in 1774. Malcolm was also active in the militia, and volunteered for service during the American Revolution. He served in New Yorks military and the Continental Army throughout the Revolution, in 1777 Malcolm was appointed to command a regiment. Called Malcolms Additional Continental Regiment, he raised the organization and used his own funds to pay, Malcolm took part in the battles of Long Island, White Plains, Trenton and Princeton. He was with the Army during the 1777-1778 winter at Valley Forge, near the end of the Revolution he was appointed commander of the militia in New York, Kings and Richmond Counties with the rank of Brigadier General. In 1785 he served on New York Citys Board of Aldermen, and he served in the New York Provincial Congress in 1786 and 1787, where he advocated adoption of the United States Constitution. As head of the militia in and around New York City, Malcolm was a Freemason, a member of the Saint Andrews Society and the Saint Nicholas Society, and a founder of New York Citys Chamber of Commerce. William Malcolm died in New York City on September 1,1791 and he was buried in Manhattans Brick Presbyterian Church Cemetery. His first wife was Abigail Tingley, whom he married in 1765, and his second wife was Sarah Ayscough, whom he married in 1772. Malcolms descendants included members of the prominent Bayard, Schuyler and Montgomery families
William Malcolm
–
Contents
11.
Swedish Mauser
–
These are the m/94 carbine, m/96 long rifle, m/38 short rifle and m/41 sniper rifle. In 1898 production began at Carl Gustafs stads Gevärsfaktori in Eskilstuna, all Swedish Mausers were chambered for the 6. 5×55mm cartridge, and all Swedish-made actions were proof-tested with a single 6. 5×55mm proof round developing approximately 455 MPa piezo pressure. Swedish Mausers were manufactured by Waffenfabrik Mauser AG in Oberndorf a/N in Germany and in Sweden by Carl Gustafs stads Gevärsfaktori, the rear sight was graduated for 6. 5×55mm service cartridges from 300 to 2,000 m in 100 m increments. Submitted for Swedish trials were the M/1892 rifle and carbine based on elements of the m/1889 Belgian, m/1890 Turkish, one rifle is chambered in 8×58mmR Danish Krag caliber. One example exists in the Museum at Aberdeen Proving Ground, Aberdeen, Maryland, the m/1894 carbine was adopted in 1894 with the first 12,000 carbines being manufactured by Waffenfabrik Mauser in Oberndorf am Neckar, Germany. This series of carbines were all manufactured in 1895, and a few spare receivers dated 1895 were received from Mauser Oberndorfs manufacturers Ludwig Loewe. Some of these spare receivers have been built as complete m/1896 rifles with serial numbers falling into the regular m/1896 rifle ranges. Production in Sweden under license commenced in 1898, Swedish production continued sporadically until 1918. Very limited numbers were produced with receiver dates of 1929. The highest 1918 serial number noted is 111,002, the m/94 carbines have a unique serial number sequence beginning with 1. The highest number so far noted is 113,150 dated 1932, there have been no carbines noted with receiver dates of 1902,1905,1908,1909,1910,1911,1912 and 1913. It may be surmised that carbines produced from the end of production in 1918 until 1932 numbered about 2,150. Mauser produced 12,000 m/1894 carbines between 1894 and 1896 and Carl Gustafs Stads Gevärsfaktori 115,000 m/1894 carbines between 1895 and 1933, giving a total of 127,000 m/1894 carbines. Some carbines were lost from regular use by conversion to sub-caliber targeting & practice devices for artillery pieces, many other carbines have been lost due to conversion to m/63 target rifles. Sub variants m/1894-14 carbines have a nose piece, not dissimilar to the No.1 Mk3 Lee–Enfield. There were two intended for the 94-14 carbine. The most prevalent was the m/1914 long bayonet, the second minor bayonet was the very long bladed m/1915 navy bayonet with the edge facing upwards. M/1894-67, This was an 1894 carbine modified to accept the m/1867 Yataghan blade saber bayonet, the modification involved a slot machined on the nose cap and a stud sleeve attached to the barrel
Swedish Mauser
–
6,5 mm Gevär m/1896. Pattern, approved 20 March 1896.
Swedish Mauser
–
6,5 mm Karbin m/1894 (m/1894-14 with bayonet mount)
Swedish Mauser
–
Carl Gustav M96 rifle, bayonet, 2 different bayonet frogs and Swedish Cartridge Belt.
Swedish Mauser
–
6,5 mm Gevär m/1938. Shortened rifle m/1896, rebuilt in 1938-1940.
12.
Refractor telescope
–
A refracting telescope is a type of optical telescope that uses a lens as its objective to form an image. The refracting telescope design was used in spy glasses and astronomical telescopes but is also used for long focus camera lenses. A refractors magnification is calculated by dividing the length of the objective lens by that of the eyepiece. Refractors were the earliest type of optical telescope, Galileo Galilei, happening to be in Venice in about the month of May 1609, heard of the invention and constructed a version of his own. Galileo then communicated the details of his invention to the public, all refracting telescopes use the same principles. The objective in a refracting telescope refracts or bends light and this refraction causes parallel light rays to converge at a focal point, while those not parallel converge upon a focal plane. The telescope converts a bundle of rays to make an angle α. The ratio β/α is called the angular magnification and it equals the ratio between the retinal image sizes obtained with and without the telescope. Refracting telescopes can come in different configurations to correct for image orientation. Because the image was formed by the bending of light, or refraction, the design Galileo Galilei used in 1609 is commonly called a Galilean telescope. It used a convergent objective lens and a divergent eyepiece lens, a Galilean telescope, because the design has no intermediary focus, results in a non-inverted and upright image. Galileo’s best telescope magnified objects about 30 times, because of flaws in its design, such as the shape of the lens and the narrow field of view, the images were blurry and distorted. Despite these flaws, the telescope was still enough for Galileo to explore the sky. The Galilean telescope could view the phases of Venus, and was able to see craters on the Moon, parallel rays of light from a distant object would be brought to a focus in the focal plane of the objective lens. The eyepiece lens intercepts these rays and renders them parallel once more, non-parallel rays of light from the object traveling at an angle α1 to the optical axis travel at a larger angle after they passed through the eyepiece. This leads to an increase in the apparent angular size and is responsible for the perceived magnification, the final image is a virtual image, located at infinity and is the same way up as the object. The Keplerian telescope, invented by Johannes Kepler in 1611, is an improvement on Galileos design and it uses a convex lens as the eyepiece instead of Galileos concave one. The advantage of this arrangement is that the rays of light emerging from the eyepiece are converging and this allows for a much wider field of view and greater eye relief, but the image for the viewer is inverted
Refractor telescope
–
Image of a refracting telescope from the
Cincinnati Observatory in 1848
Refractor telescope
–
Woodcut illustration of a 46 m (150 ft) focal length Keplerian astronomical refracting telescope built by Johannes Hevelius. From his book Machina coelestis (first part), published in 1673.
Refractor telescope
–
The 1,000-millimeter (40 in) refractor, at
Yerkes Observatory, the largest achromatic refractor ever put into astronomical use
Refractor telescope
–
The Great Refractor at the
Astrophysical Institute Potsdam,
Germany
13.
Eye relief
–
The eye relief of an optical instrument is the distance from the last surface of an eyepiece within which the users eye can obtain the full viewing angle. If a viewers eye is outside this distance, a field of view will be obtained. The calculation of eye relief is complex, though generally, the higher the magnification and the larger the intended field-of-view, an exit pupil larger than the observers pupil wastes some light, but allows for some fumbling in side-to-side movement without vignetting or clipping. Eye relief distance can be important for eyeglass wearers and shooters. The eye of a wearer is typically further from the eyepiece so needs a longer eye relief in order to still see the entire field of view. A simple practical test as to whether or not spectacles limit the field of view can be conducted by viewing first without spectacles, ideally there should be no difference in the field. For a shooter, eye relief is also a safety consideration, if the eye relief of a telescopic sight is too short, leaving the eye close to the sight, the firearms recoil can force the optic to strike the skin around the shooters eye, leaving a cut. This is frequently called the cut due to the obvious. Typical eye relief distances for telescopic sights are often one and four inches, as opposed to the much shorter 15 to 17 mm for typical binoculars. The exit pupil widths in rifle sights are designed to be larger than the eyes pupil, the eye relief given in product specifications does not always give a realistic view of what a user can expect. A better measure for those with strict needs would be one that takes account of this available eye relief and this point can account for confusion in performance and is rarely expressed clearly. Additionally, when a spectacle wearer orders new glasses, the optician will ask him whether he prefers his spectacles close to the eyes or at some distance and this distance is referred to as the Back Vertex Distance, or BVD on a prescription. Since this property affects the eye relief of any binocular or other optics used. The matter should be discussed with the optician, though the only way of testing the comfort is to try the optical device while wearing the usual spectacles. The optician can however make sure that the BVD is no worse in your new glasses than in the old ones that were used during evaluation. In the event that a spectacle wearer cannot obtain the eye relief that they require, some cameras, in this way, the user can temporarily dispense with glasses in favor of the lens mounted on the optics. Although this method does not afford good vision for the field around them
Eye relief
–
Optics showing eye relief and exit pupil 1 Real image 2 Field diaphragm 3 Eye relief 4 Exit pupil
14.
Zf-41
–
The Zf-41 was an optical sight produced in Germany during the Second World War. Starting from 1941 the short 1. 5x Zielfernrohr 41 telescopic sight was fitted to some Karabiner 98k rifles for sharpshooting use. The Zf-41 was in fact the first attempt to provide the ordinary infantryman with a capable of being used, if not for pure sniping. Most modern-day armies have adopted some form of optical aiming device on infantry weapons and it was initially planned to equip most combat units with the Zf-41 scopes, but only 6% of German weapons production could fit the sight. Problems were the scopes extreme eye relief, poor functioning in bad light, by the end of the war in 1945 more than 100,000 Zf-41 scopes had been produced, the largest production of German optical sights during the war. Mp-43, MP-44, FG-42 automatic select fire weapons had the ZF-41/1 fitted for test only, these were not produced past prototype stage, the Germans also produced a small amount of prototype and pre production test batch of the g33/40 equipped with the zf 41 sharpshooter scope. These were photographed for inclusion in the zf 41 manual in 1942, however the BRNO factory switched over to the Mauser 98 K in 1943. Approximately 350 to 400 scoped g 33/40 rifles were made in total, as of 2013 only one has been examined and found to be a real test batch scoped rifle, it has serial number 3962C. It is a late dot 1942 production rifle, out of Nowhere, A History of the Military Sniper p. 188-189
Zf-41
–
An SS rifleman aims through a ZF-41 scope on his
Kar98k rifle (the scope can be seen on the last visible part of the rifle)
15.
Karabiner 98k
–
The Karabiner 98 kurz is a bolt-action rifle chambered for the 7. 92×57mm Mauser cartridge that was adopted on 21 June 1935 as the standard service rifle by the German Wehrmacht. It was one of the developments in the long line of Mauser military rifles. Although supplemented by semi- and fully-automatic rifles during World War II, millions were captured by the Soviets at the conclusion of World War II and were widely distributed as military aid. The Karabiner 98k therefore continues to appear in conflicts across the world as they are out of storage during times of strife. In February 1934 the Heereswaffenamt ordered the adoption of a new military rifle, the Karabiner 98k was derived from earlier rifles, namely the Mauser Standardmodell of 1924 and the Karabiner 98b, which in turn had both been developed from the Gewehr 98. Since the Karabiner 98k rifle was shorter than the earlier Karabiner 98b, it was given the designation Karabiner 98 kurz, meaning Carbine 98 Short. Just like its predecessor, the rifle was noted for its reliability, great accuracy, the desire for adapting new shorter barreled rifles and introduction of the Karabiner 98k, featuring a 600 mm long barrel, were reasons for changing the standard German service ball rifle cartridge. The 1903 pattern 7. 92×57mm Mauser S Patrone produced excessive muzzle flash when fired from arms that did not have a long barrel like the Gewehr 98 and it was found that the s. S. Patrone, originally designed for long range machine gun use, produced less muzzle flash out of rifles that had a long barrel. Because of this the S Patrone was phased out in 1933, Patrone became the standard German service ball cartridge in the 1930s. The Karabiner 98k is a controlled-feed bolt-action rifle based on the Mauser M98 system and its internal magazine can be loaded with five 7. 92×57mm Mauser cartridges from a stripper clip or one-by-one. The straight bolt handle found on the Gewehr 98 bolt was replaced by a bolt handle on the Karabiner 98k. This change made it easier to operate the bolt, reduced the amount the handle projected beyond the receiver. Each rifle was furnished with a length of cleaning rod. The joined rods from 3 rifles provided one full-length cleaning rod, the metal parts of the rifle were blued, a process in which steel is partially protected against rust by a layer of magnetite. Such a thin oxide layer provides only minimal protection against rust or corrosion, unless also treated with a water-displacing oil to reduce wetting. From 1944 onwards phosphating/Parkerizing was introduced as a more effective metal surface treatment, the impractical Langevisier or rollercoaster rear sight of the Mauser Gewehr 1898 was replaced with a conventional tangent leaf sight. The Karabiner 98k rear tangent sight was flatter compared to and does not obstruct the view to the sides during aiming as the Langevisier, originally, the Karabiner 98k iron sight line had an open-post-type front sight, and a tangent-type rear sight with a V-shaped rear notch
Karabiner 98k
–
Karabiner 98k in mint condition, made in 1940. From the collections of the
Swedish Army Museum
Karabiner 98k
–
Karabiner 98k stripper clip with five 7.92×57mm Mauser cartridges
Karabiner 98k
–
A disassembled Karabiner 98k action
Karabiner 98k
–
S84/98 III bayonet and scabbard
16.
Night vision
–
Night vision is the ability to see in low light conditions. Whether by biological or technological means, night vision is possible by a combination of two approaches, sufficient spectral range, and sufficient intensity range. Humans have poor night vision compared to animals, in part because the human eye lacks a tapetum lucidum. 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 sources of electromagnetic radiation. Some animals such as the shrimp can see using much more of the infrared and/or ultraviolet spectrum than humans. Sufficient intensity range is simply the ability to see with very small quantities of light, many animals have better night vision than humans do, the result of one or more differences in the morphology and anatomy of their eyes. These include having a larger eyeball, a lens, a larger optical aperture, more rods than cones in the retina. Enhanced intensity range is achieved via technological means through the use of an image intensifier, gain multiplication CCD, or other very low-noise and high-sensitivity array of photodetectors. All photoreceptor cells in the eye contain molecules of photoreceptor protein which is a combination of the protein photopsin in color vision cells, rhodopsin in night vision cells, and retinal. The retinal must diffuse from the cell, out of the eye. In bright light conditions, most of the retinal is not in the photoreceptors and it takes about 45 minutes of dark for all of the photoreceptor proteins to be recharged with active retinal, but most of the night vision adaptation occurs within the first five minutes in the dark. Adaptation results in sensitivity to light. In dark conditions only the rod cells have enough sensitivity to respond, rhodopsin in the human rods is insensitive to the longer red wavelengths, so traditionally many people use red light to help preserve night vision. Red light only slowly depletes the rhodopsin stores in the rods, another theory posits that since stars typically emit light with shorter wavelengths, the light from stars will be in the blue-green color spectrum. Therefore, using red light to navigate would not desensitize the receptors used to detect star light, using red light for night vision is less effective for people with red–green color blindness, due to their insensitivity to red light. This is found in nocturnal animals and some deep sea animals. Humans, and monkeys, lack a tapetum lucidum, nocturnal mammals have rods with unique properties that make enhanced night vision possible
Night vision
–
Two
American soldiers pictured during the
2003 Iraq War seen through an image intensifier
Night vision
Night vision
–
"Night sight can mean life or death. Eat carrots and leafy greens or yellow vegetables, rich in vitamins," WWII poster
Night vision
–
Binocular night vision goggles on a flight helmet Note: the green color of the objective lenses is the reflection of the light interference filters, not a glow.
17.
Wehrmacht
–
The Wehrmacht was the unified armed forces of Nazi Germany from 1935 to 1946. It consisted of the Heer, the Kriegsmarine and the Luftwaffe, after the Nazi seizure of power in 1933, one of Adolf Hitler’s most overt and audacious moves was to establish the Wehrmacht, a modern armed forces fully capable of offensive use. In December 1941, Hitler designated himself as commander-in-chief of the Wehrmacht, the Wehrmacht formed the heart of Germany’s politico-military power. In the early part of World War II, Hitlers generals employed the Wehrmacht through innovative combined arms tactics to devastating effect in what was called a Blitzkrieg, the Wehrmachts new military structure, unique combat techniques, newly developed weapons, and unprecedented speed and brutality crushed their opponents. Closely cooperating with the SS, the German armed forces committed war crimes and atrocities. By the time the war ended in Europe in May 1945, only a few of the Wehrmacht’s upper leadership were tried for war crimes, despite evidence suggesting that more were involved in illegal actions. The German term Wehrmacht generically describes any nations armed forces, for example, the Frankfurt Constitution of 1848 designated all German military forces as the German Wehrmacht, consisting of the Seemacht and the Landmacht. In 1919, the term Wehrmacht also appears in Article 47 of the Weimar Constitution, establishing that, from 1919, Germanys national defense force was known as the Reichswehr, a name that was dropped in favor of Wehrmacht on 21 May 1935. In January 1919, after World War I ended with the signing of the armistice of 11 November 1918, in March 1919, the national assembly passed a law founding a 420, 000-strong preliminary army, the Vorläufige Reichswehr. The terms of the Treaty of Versailles were announced in May, the army was limited to one hundred thousand men with an additional fifteen thousand in the navy. The fleet was to consist of at most six battleships, six cruisers, submarines, tanks and heavy artillery were forbidden and the air-force was dissolved. A new post-war military, the Reichswehr, was established on 23 March 1921, General conscription was abolished under another mandate of the Versailles treaty. The Reichswehr was limited to 115,000 men, and thus the armed forces, under the leadership of Hans von Seeckt, though Seeckt retired in 1926, the army that went to war in 1939 was largely his creation. Germany was forbidden to have an air-force by the Versailles treaty, nonetheless and these officers saw the role of an air-force as winning air-superiority, tactical and strategic bombing and providing ground support. That the Luftwaffe did not develop a strategic bombing force in the 1930s was not due to a lack of interest, but because of economic limitations. The leadership of the Navy led by Grand Admiral Erich Raeder, officers who believed in submarine warfare led by Admiral Karl Dönitz were in a minority before 1939. By 1922, Germany had begun covertly circumventing the conditions of the Versailles Treaty, a secret collaboration with the Soviet Union began after the treaty of Rapallo. Major-General Otto Hasse traveled to Moscow in 1923 to further negotiate the terms, Germany helped the Soviet Union with industrialization and Soviet officers were to be trained in Germany
Wehrmacht
–
Werner Goldberg, who was blond and blue-eyed, was used in Wehrmacht recruitment posters as the "ideal German soldier". He was later dismissed after it became known that he was a half Jew.
Wehrmacht
–
The straight-armed
Balkenkreuz, a stylized version of the
Iron Cross, the emblem of the Wehrmacht
Wehrmacht
–
Inspection of German conscripts
Wehrmacht
–
A
Volga Tatar Wehrmacht unit
18.
StG 44
–
The StG44 is a German selective-fire rifle developed during World War II. It is also known under the designations MP43 and MP44, by all accounts, the StG44 fulfilled its role effectively, particularly on the Eastern Front, offering a greatly increased volume of fire compared to standard infantry rifles. However, it too late to have a significant effect on the outcome of the war. Its lasting effect was its impact on modern infantry small arms development. MP43, MP44, and StG44 were different designations for what was essentially the same rifle with minor updates in production, the variety in nomenclatures resulted from the complicated bureaucracy in Nazi Germany. Developed from the Mkb 42 machine carbine, the StG44 combined the characteristics of a carbine, submachine gun, StG is an abbreviation of Sturmgewehr. After the adoption of the StG44, the English translation assault rifle became the designation for this type of infantry small arm. Over the course of its production, there were changes to the butt end, muzzle nut, shape of the front sight base. The rifle was chambered for the 7. 92×33mm Kurz cartridge, full-power rifle cartridges were excessive for the vast majority of uses for the average soldier. The British were critical of the weapon, saying that the receiver could be bent, a late-war U. S. assessment derided the weapon as bulky and unhandy, prone to jamming, and meant to be thrown away if the soldier could not maintain it. In the late 19th century, small-arms cartridges had become able to fire accurately at long distances, jacketed bullets propelled by smokeless powder were lethal out to 2,000 metres. This was beyond the range a shooter could engage a target with open sights, only units of riflemen firing in salvos could hit grouped soft targets at those ranges. That fighting style was taken over by the introduction of machine guns. Weapons for short range were semi-automatic pistols, and later submachine guns. The gap in cartridge ranges caused research into creating an intermediate round and this type of ammunition was being considered as early as 1892, but militaries at the time were still fixated on increasing the maximum range and velocity of bullets from their rifles. He pointed out that firefights rarely took place beyond 800 metres, a smaller, shorter, and less powerful round would save materials, allow soldiers to carry more ammunition, and increase firepower. Less recoil would allow semi-automatic or even fully automatic select-fire rifles, the German Army showed no interest, as it already had the MP18 submachine gun firing 9 mm pistol rounds and did not want to create a new cartridge. In 1923, the German Army set out requirements for a Mauser 98 replacement and it had to be smaller and lighter than the Mauser, have similar performance out to 400 metres, and have a magazine with a 20 or 30 round capacity
StG 44
–
StG 44 from the collections of the
Swedish Army Museum
StG 44
–
A soldier demonstrates the transitional MP 43/1 variant, used to determine the suitability of the rifle for sniping purposes, October 1943. The rifle is fitted with a ZF 4 telescopic sight.
StG 44
–
A German infantryman armed with a StG 44, wearing
"splinter" camouflage and a
ghillie cap in 1944.
StG 44
–
The early Haenel MKb 42(H), the precursor to the MP 43/44. This example belongs to the
Springfield Armory National Historic Site.
19.
Optical
–
Optics is the branch of physics which involves 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 using the classical 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, physical optics is a more comprehensive model of light, which includes wave effects such as diffraction and interference that cannot be accounted for in geometric optics. Historically, the model of light was developed first, followed by the wave model of light. Progress in electromagnetic theory in the 19th century led to the discovery that waves were in fact electromagnetic radiation. Some phenomena depend on the fact that light has both wave-like and particle-like properties, explanation of these effects requires quantum mechanics. When considering lights particle-like properties, the light is modelled as a collection of particles called photons, quantum optics deals with the application of quantum mechanics to optical systems. Optical science is relevant to and studied in many related disciplines including astronomy, various engineering fields, photography, practical applications of optics are found in a variety of technologies and everyday objects, including mirrors, lenses, telescopes, microscopes, lasers, and fibre optics. Optics began with the development of lenses by the ancient Egyptians and Mesopotamians, the earliest known lenses, made from polished crystal, often quartz, date from as early as 700 BC for Assyrian lenses such as the Layard/Nimrud lens. The ancient Romans and Greeks filled glass spheres with water to make lenses, the word optics comes from the ancient Greek word ὀπτική, meaning appearance, look. Greek philosophy on optics broke down into two opposing theories on how vision worked, the theory and the emission theory. The intro-mission approach saw vision as coming from objects casting off copies of themselves that were captured by the eye, plato first articulated the emission theory, the idea that visual perception is accomplished by rays emitted by the eyes. He also commented on the parity reversal of mirrors in Timaeus, some hundred years later, Euclid wrote a treatise entitled Optics where he linked vision to geometry, creating geometrical optics. Ptolemy, in his treatise Optics, held a theory of vision, the rays from the eye formed a cone, the vertex being within the eye. The rays were sensitive, and conveyed back to the observer’s intellect about the distance. He summarised much of Euclid and went on to describe a way to measure the angle of refraction, during the Middle Ages, Greek ideas about optics were resurrected and extended by writers in the Muslim world
Optical
–
Optics includes study of
dispersion of light.
Optical
–
The Nimrud lens
Optical
–
Reproduction of a page of
Ibn Sahl 's manuscript showing his knowledge of the law of refraction, now known as
Snell's law
Optical
–
Cover of the first edition of Newton's Opticks
20.
Magnification
–
Magnification is the process of enlarging something only in appearance, not in physical size. This enlargement is quantified by a number also called magnification. When this number is less one, it refers to a reduction in size. Typically, magnification is related to scaling up visuals or images to be able to see detail, increasing resolution, using microscope, printing techniques. In all cases, the magnification of the image does not change the perspective of the image, some optical instruments provide visual aid by magnifying small or distant subjects. A magnifying glass, which uses a lens to make things look bigger by allowing the user to hold them closer to their eye. A microscope, which makes an object appear as a much larger image at a comfortable distance for viewing. A microscope is similar in layout to a telescope except that the object being viewed is close to the objective, a slide projector, which projects a large image of a small slide on a screen. Optical magnification is the ratio between the apparent size of an object and its size, and thus it is a dimensionless number. Optical magnification is sometimes referred to as power, although this can lead to confusion with optical power, for real images, such as images projected on a screen, size means a linear dimension. For optical instruments with an eyepiece, the dimension of the image seen in the eyepiece cannot be given. Strictly speaking, one should take the tangent of that angle, example, The angular size of the full moon is 0. 5°. In binoculars with 10x magnification it appears to subtend an angle of 5°, the linear magnification of a thin lens is where f is the focal length and d o is the distance from the lens to the object. Note that for real images, M is negative and the image is inverted, for virtual images, M is positive and the image is upright. The image recorded by a film or image sensor is always a real image and is usually inverted. When measuring the height of an image using the cartesian sign convention the value for hi will be negative. However, the sign convention used in photography is real is positive. Therefore in photography, Object height and distance are always real, when the focal length is positive the images height, distance and magnification are real and positive
Magnification
–
The stamp appears larger with the use of a magnifying glass
21.
Objective lens
–
In optical engineering, the objective is the optical element that gathers light from the object being observed and focuses the light rays to produce a real image. Objectives can be a lens or mirror, or combinations of several optical elements. They are used in microscopes, telescopes, cameras, slide projectors, CD players, objectives are also called object lenses, object glasses, or objective glasses. The objective lens of a microscope is the one at the bottom near the sample, at its simplest, it is a very high-powered magnifying glass, with very short focal length. This is brought close to the specimen being examined so that the light from the specimen comes to a focus inside the microscope tube. The objective itself is usually a cylinder containing one or more lenses that are made of glass. Microscope objectives are characterized by two parameters, magnification and numerical aperture, the magnification typically ranges from 4× to 100×. Numerical aperture for microscope lenses typically ranges from 0.10 to 1.25, corresponding to focal lengths of about 40 mm to 2 mm, respectively. A typical microscope has three or four lenses with different magnifications, screwed into a circular nosepiece which may be rotated to select the required lens. These lenses are often color coded for easier use, the least powerful lens is called the scanning objective lens, and is typically a 4× objective. The second lens is referred to as the objective lens and is typically a 10× lens. The most powerful out of the three is referred to as the large objective lens and is typically 40–100×. Some microscopes use an oil-immersion or water-immersion lens, which can have greater than 100. These objectives are designed for use with refractive index matching oil or water. These lenses give greater resolution at high magnification, numerical apertures as high as 1.6 can be achieved with oil immersion. Camera lenses need to cover a large plane so are made up of a number of optical lens elements to correct optical aberrations. Image projectors use objective lenses that simply reverse the function of a lens, with lenses designed to cover a large image plane. In a telescope the objective is the lens at the front end of a refractor or the primary mirror of a reflecting or catadioptric telescope
Objective lens
–
Several objective lenses on a microscope.
Objective lens
–
A photographic objective,
focal length 50 mm,
aperture 1:1.4
Objective lens
–
Diastar projection objective from a 35 mm
movie projector, (focal length 400 mm).
Objective lens
–
Two Leica
oil immersion microscope objective lenses; left 100×, right 40×.
22.
Diameter
–
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle, both definitions are also valid for the diameter of a sphere. In more modern usage, the length of a diameter is called the diameter. In this sense one speaks of the rather than a diameter, because all diameters of a circle or sphere have the same length. Both quantities can be calculated efficiently using rotating calipers, for a curve of constant width such as the Reuleaux triangle, the width and diameter are the same because all such pairs of parallel tangent lines have the same distance. For an ellipse, the terminology is different. A diameter of an ellipse is any chord passing through the midpoint of the ellipse, for example, conjugate diameters have the property that a tangent line to the ellipse at the endpoint of one of them is parallel to the other one. The longest diameter is called the major axis, the word diameter is derived from Greek διάμετρος, diameter of a circle, from διά, across, through and μέτρον, measure. It is often abbreviated DIA, dia, d, or ⌀, the definitions given above are only valid for circles, spheres and convex shapes. However, they are cases of a more general definition that is valid for any kind of n-dimensional convex or non-convex object. The diameter of a subset of a space is the least upper bound of the set of all distances between pairs of points in the subset. So, if A is the subset, the diameter is sup, if the distance function d is viewed here as having codomain R, this implies that the diameter of the empty set equals −∞. Some authors prefer to treat the empty set as a case, assigning it a diameter equal to 0. For any solid object or set of scattered points in n-dimensional Euclidean space, in medical parlance concerning a lesion or in geology concerning a rock, the diameter of an object is the supremum of the set of all distances between pairs of points in the object. In differential geometry, the diameter is an important global Riemannian invariant, the symbol or variable for diameter, ⌀, is similar in size and design to ø, the Latin small letter o with stroke. In Unicode it is defined as U+2300 ⌀ Diameter sign, on an Apple Macintosh, the diameter symbol can be entered via the character palette, where it can be found in the Technical Symbols category. The character will not display correctly, however, since many fonts do not include it. In many situations the letter ø is a substitute, which in Unicode is U+00F8 ø
Diameter
–
Circle with
circumference (C) in black, diameter (D) in cyan, radius (R) in red, and centre or origin (O) in magenta.
23.
Exit pupil
–
In optics, the exit pupil is a virtual aperture in an optical system. Only rays which pass through this virtual aperture can exit the system, the exit pupil is the image of the aperture stop in the optics that follow it. In a telescope or compound microscope, this image is the image of the element as produced by the eyepiece. The size and shape of disc is crucial to the instruments performance. The term exit pupil is sometimes used to refer to the diameter of the virtual aperture. Older literature on optics sometimes refers to the pupil as the Ramsden disc. To use an instrument, the entrance pupil of the viewers eye must be aligned with. This properly couples the optical system to the eye and avoids vignetting, the location of the exit pupil thus determines the eye relief of an eyepiece. Good eyepiece designs produce an exit pupil of diameter approximating the eyes apparent pupil diameter, if the disc is larger than the eyes pupil, light will be lost instead of entering the eye, if smaller, the view will be vignetted. Since the eyes pupil varies in diameter with viewing conditions, the exit pupil diameter depends on the application. A set of 7×50 binoculars has a pupil just over 7.1 mm. The emergent light at the eyepiece then fills the eyes pupil, in daylight, when the eyes pupil is only 4 mm in diameter, over half the light will be blocked by the iris and will not reach the retina. However, the loss of light in the daytime is not significant since there is so much light to start with. By contrast, 8×32 binoculars, often sold with emphasis on their compactness, have a pupil of only 4 mm. That is sufficient to fill a typical daytime eye pupil, making these binoculars better suited to daytime than night-time use. The maximum pupil size of an eye is typically 5–9 mm for individuals below 25 years old. The optimum eye relief distance also varies with application, for example a rifle scope needs a very long eye relief to prevent recoil from causing it to strike the observer. The exit pupil can be visualized by focusing the instrument on a bright, nondescript field and this projects a disc of light onto the card
Exit pupil
–
The image side of the lens of an SLR camera; the exit pupil is the light area in the middle of the lens.
Exit pupil
–
Binoculars showing Exit Pupil
24.
Eyepiece
–
An eyepiece, or ocular lens, is a type of lens that is attached to a variety of optical devices such as telescopes and microscopes. It is so named because it is usually the lens that is closest to the eye when someone looks through the device, the objective lens or mirror collects light and brings it to focus creating an image. The eyepiece is placed near the point of the objective to magnify this image. The amount of magnification depends on the length of the eyepiece. An eyepiece consists of several elements in a housing, with a barrel on one end. The barrel is shaped to fit in an opening of the instrument to which it is attached. The image can be focused by moving the eyepiece nearer and further from the objective, most instruments have a focusing mechanism to allow movement of the shaft in which the eyepiece is mounted, without needing to manipulate the eyepiece directly. The eyepieces of binoculars are usually mounted in the binoculars, causing them to have a pre-determined magnification. With telescopes and microscopes, however, eyepieces are usually interchangeable, by switching the eyepiece, the user can adjust what is viewed. For instance, eyepieces will often be interchanged to increase or decrease the magnification of a telescope, eyepieces also offer varying fields of view, and differing degrees of eye relief for the person who looks through them. Several properties of an eyepiece are likely to be of interest to a user of an optical instrument, eyepieces are optical systems where the entrance pupil is invariably located outside of the system. They must be designed for optimal performance for a distance to this entrance pupil. In a refracting astronomical telescope the entrance pupil is identical with the objective and this may be several feet distant from the eyepiece, whereas with a microscope eyepiece the entrance pupil is close to the back focal plane of the objective, mere inches from the eyepiece. Microscope eyepieces may be corrected differently from telescope eyepieces, however, elements are the individual lenses, which may come as simple lenses or singlets and cemented doublets or triplets. When lenses are cemented together in pairs or triples, the elements are called groups. The first eyepieces had only a lens element, which delivered highly distorted images. Two and three-element designs were invented soon after, and quickly became standard due to the image quality. Today, engineers assisted by computer-aided drafting software have designed eyepieces with seven or eight elements that deliver exceptionally large, internal reflections, sometimes called scatter, cause the light passing through an eyepiece to disperse and reduce the contrast of the image projected by the eyepiece
Eyepiece
–
A collection of different types of eyepieces.
Eyepiece
–
A 25 mm Kellner eyepiece
Eyepiece
–
Simulation of views through a telescope using different eyepieces. The center image uses an eyepiece of the same focal length as the one on the left, but has a wider apparent field of view giving a larger image that shows more area. The image on the right also has a shorter focal length, giving the same true field of view as the left image but at higher magnification.
Eyepiece
–
The Plössl, an eyepiece with a large apparent field of view
25.
Prime lens
–
In film and photography, a prime lens is either a photographic lens whose focal length is fixed, as opposed to a zoom lens, or it is the primary lens in a combination lens system. Confusion can sometimes result due to the two meanings of the if the context does not make the interpretation clear. Alternative terms primary focal length, fixed length, and FFL are sometimes used to avoid ambiguity. The term prime has come to be used as the opposite of zoom, that is, while a prime lens of a given focal length is less versatile than a zoom, it is often of superior optical quality, wider maximum aperture, lighter weight, smaller size. The larger maximum aperture allows photography in lower light, and a depth of field. An alternative and apparently somewhat older meaning of the prime lens is the main lens in a combination lens system. When the camera lens is used some other optical device, such as a close-up lens, teleconverter, or teleside converter. Prime is here used in the sense of primary, chief, original, first in order, a variable prime is sometimes distinguished from a true zoom in that the latter maintains focus as the focal length is varied. This use of the prime lens is an example of a retronym. Early in photography only primary camera lenses were available, and were merely called lenses or objectives, later, auxiliary lenses were available, which usually fit in front of the front element of the primary, or prime lens. For these lengths many manufacturers produce two or more lenses with the focal length but with different maximum apertures to suit the different needs of photographers. Additional focal lengths can be created by using a teleconverter,24 to 35mm, Wide — these lenses capture a wider field of view than a standard lens. Because they tend to be used at shorter distances the resulting perspective can show some distortion,50 mm, Standard — with a focal length near the 44mm image diagonal. 85 mm, Portrait — A short telephoto lens that allows a subject to camera distance, to produce pleasing perspective effects. 135 mm, Telephoto — these lenses are used by action,200 to 500 mm, Super Telephoto — these are specialized, bulky lenses for sports, action, and wildlife photography. Some specialist lenses are available as prime lenses due to design or cost constraints. Examples of such specialist lenses are, extreme telephoto or wide angle, lenses with tilt and / or shift function, lenses with large apertures and macro lenses
Prime lens
–
A 29mm prime lens accompanied by a diagram of its internal lens elements.
Prime lens
–
Prime lenses can have quite large apertures, compared with zoom lenses. These 85mm lenses have maximum apertures of
f/1.8 (left) and f /1.2 (right).
Prime lens
–
The
Canon EF 50mm f/1.8 II.
26.
Zoom lens
–
A zoom lens is a mechanical assembly of lens elements for which the focal length can be varied, as opposed to a fixed focal length lens. A true zoom lens, also called a lens, is one that maintains focus when its focal length changes. A lens that loses focus during zooming is more properly called a varifocal lens, despite being marketed as zoom lenses, virtually all consumer lenses with variable focal lengths use varifocal design. The convenience of variable focal length comes at the cost of complexity - and some compromises on image quality, weight, dimensions, aperture, autofocus performance, and cost. For example, all zoom lenses suffer from at least slight, if not considerable, loss of resolution at their maximum aperture. This effect is evident in the corners of the image, when displayed in a format or high resolution. The greater the range of length a zoom lens offers. Zoom lenses are described by the ratio of their longest to shortest focal lengths. For example, a lens with focal lengths ranging from 100 mm to 400 mm may be described as a 4,1 or 4× zoom. This ratio can be as high as 300× in professional television cameras, as of 2009, photographic zoom lenses beyond about 3× cannot generally produce imaging quality on par with prime lenses. Constant fast aperture zooms are typically restricted to this zoom range, quality degradation is less perceptible when recording moving images at low resolution, which is why professional video and TV lenses are able to feature high zoom ratios. Digital photography can also accommodate algorithms that compensate for optical flaws, some photographic zoom lenses are long-focus lenses, with focal lengths longer than a normal lens, some are wide-angle lenses, and others cover a range from wide-angle to long-focus. Lenses in the group of zoom lenses, sometimes referred to as normal zooms, have displaced the fixed focal length lens as the popular one-lens selection on many contemporary cameras. The markings on these lenses usually say W and T for Wide, Telephoto is designated because the longer focal length supplied by the negative diverging lens is longer than the overall lens assembly. Some digital cameras allow cropping and enlarging of a captured image and this is commonly known as digital zoom and produces an image of lower optical resolution than optical zoom. Exactly the same effect can be obtained by using image processing software on a computer to crop the digital image and enlarge the cropped area. Many digital cameras have both, combining them by first using the optical, then the digital zoom, Zoom and superzoom lenses are commonly used with still, video, motion picture cameras, projectors, some binoculars, microscopes, telescopes, telescopic sights, and other optical instruments. In addition, the part of a zoom lens can be used as a telescope of variable magnification to make an adjustable beam expander
Zoom lens
–
Nikkor 28-200 mm zoom lens, extended to 200 mm at left and collapsed to 28 mm focal length at right
Zoom lens
–
A photograph taken with a zoom lens, whose focal length was varied during the course of the exposure.
Zoom lens
–
Unusual trailed-zoom view of the
VLT.
Zoom lens
–
The Voigtländer Zoomar, 36–82 mm f /2.8
27.
Field of view
–
The groups tenure lasted until their break up in December 2002. One of their hit singles, Dan Dan Kokoro Hikareteku, was used as the theme for the popular anime series Dragon Ball GT. Another single, 「渇いた叫び」, was used as the opening for the original Yu-Gi-Oh and they released 2 singles under the name view. Just after the Last Goodbye EP in 1995, Abe left the group, after the Truth of Love EP in 2001, the was added in front of the band name for later releases. In 1996, the band gave their first concert, Live Horizon Version 1, Version 2 followed in 1997 and Live Horizon Version 3 in 1999. On June 25,1999, they performed in the Dublin Castle in London, the Field of View broke up one month after their November 2002 performances held in Tokyo and Osaka. On December 1,2002, the Field of View performed Field of View Live Horizon - The Final, in all, they released 22 singles,5 studio albums and 5 best albums
Field of view
28.
Angle
–
In planar geometry, an angle is the figure formed by two rays, called the sides of the angle, sharing a common endpoint, called the vertex of the angle. Angles formed by two rays lie in a plane, but this plane does not have to be a Euclidean plane, Angles are also formed by the intersection of two planes in Euclidean and other spaces. Angles formed by the intersection of two curves in a plane are defined as the angle determined by the tangent rays at the point of intersection. Similar statements hold in space, for example, the angle formed by two great circles on a sphere is the dihedral angle between the planes determined by the great circles. Angle is also used to designate the measure of an angle or of a rotation and this measure is the ratio of the length of a circular arc to its radius. In the case of an angle, the arc is centered at the vertex. In the case of a rotation, the arc is centered at the center of the rotation and delimited by any other point and its image by the rotation. The word angle comes from the Latin word angulus, meaning corner, cognate words are the Greek ἀγκύλος, meaning crooked, curved, both are connected with the Proto-Indo-European root *ank-, meaning to bend or bow. Euclid defines a plane angle as the inclination to each other, in a plane, according to Proclus an angle must be either a quality or a quantity, or a relationship. In mathematical expressions, it is common to use Greek letters to serve as variables standing for the size of some angle, lower case Roman letters are also used, as are upper case Roman letters in the context of polygons. See the figures in this article for examples, in geometric figures, angles may also be identified by the labels attached to the three points that define them. For example, the angle at vertex A enclosed by the rays AB, sometimes, where there is no risk of confusion, the angle may be referred to simply by its vertex. However, in geometrical situations it is obvious from context that the positive angle less than or equal to 180 degrees is meant. Otherwise, a convention may be adopted so that ∠BAC always refers to the angle from B to C. Angles smaller than an angle are called acute angles. An angle equal to 1/4 turn is called a right angle, two lines that form a right angle are said to be normal, orthogonal, or perpendicular. Angles larger than an angle and smaller than a straight angle are called obtuse angles. An angle equal to 1/2 turn is called a straight angle, Angles larger than a straight angle but less than 1 turn are called reflex angles
Angle
–
An angle enclosed by rays emanating from a vertex.
29.
Vignetting
–
In photography and optics, vignetting is a reduction of an images brightness or saturation at the periphery compared to the image center. The word vignette, from the root as vine, originally referred to a decorative border in a book. Later, the word came to be used for a portrait which is clear in the center. A similar effect occurs when photographing projected images or movies off a projection screen, vignetting is often an unintended and undesired effect caused by camera settings or lens limitations. However, it is deliberately introduced for creative effect, such as to draw attention to the center of the frame. A photographer may deliberately choose a lens which is known to produce vignetting to obtain the effect, when using superzoom lenses, vignetting may occur all along the zoom range, depending on the aperture and the focal length. However, it may not always be visible, except at the widest end, in these cases, vignetting may cause an exposure value difference of up to 0. 75EV. There are several causes of vignetting and this has the effect of changing the entrance pupil shape as a function of angle. Darkening can be gradual or abrupt – the smaller the aperture, when some points on an image receives no light at all due to mechanical vignetting, then this results in an restriction of the field of view – parts of the image are then completely black. This type of vignetting is caused by the dimensions of a multiple element lens. Rear elements are shaded by elements in front of them, which reduces the lens opening for off-axis incident light. The result is a decrease in light intensity towards the image periphery. Optical vignetting is sensitive to the aperture and can often be cured by a reduction in aperture of 2–3 stops. Unlike the previous types, natural vignetting is not due to the blocking of light rays, the falloff is approximated by the cos4 or cosine fourth law of illumination falloff. Here, the light falloff is proportional to the power of the cosine of the angle at which the light impinges on the film or sensor array. Wideangle rangefinder designs and the designs used in compact cameras are particularly prone to natural vignetting. Telephoto lenses, retrofocus wideangle lenses used on SLR cameras, a gradual grey filter or postprocessing techniques may be used to compensate for natural vignetting, as it cannot be cured by stopping down the lens. Some modern lenses are designed so that the light strikes the image parallel or nearly so
Vignetting
–
A vignette is often added to an image to draw interest to the center and to frame the center portion of the photo.
Vignetting
–
Vignetting is a common feature of photographs produced by
toy cameras such as this shot taken with a
Holga.
Vignetting
–
This example shows both vignetting and restricted
field of view (FOV). Here a "
point-and-shoot camera " is used together with a
microscope to create this image. Pronounced vignetting (fall off in brightness towards the edge) is visible as the optical system is not well adapted. Please note that furthermore a circular restriction of the FOV is visible (the black area in the image).
Vignetting
–
Vignetting can be used to artistic effect, as demonstrated in this panorama.
30.
Handgun
–
A handgun is a firearm designed to be handheld, in either one or both hands. This characteristic differentiates handguns as a class of firearms from long guns such as rifles. Major handgun subtypes are the revolver and pistol, other subtypes include derringers, the words pistol and handgun have overlapping variations, in meaning. Although handgun use often includes bracing with a hand, the essential distinguishing characteristic of a handgun is its facility for one-handed operation. The word pistol is often synonymous with the word handgun, some handgun experts make a technical distinction that views pistols as a subset of handguns. But UK/Commonwealth usage often does not make this distinction, handheld firearms were first made in China where gunpowder was first developed. By the 14th century, they existed in Europe as well, the first handheld firearms that might better be called pistols were made as early as the 15th century, but their creator is unknown. By the 18th century, the term came to be used often to refer to handheld firearms, previously there had been no such differentiation, and in fact Samuel Colts original patent was for a revolving-breech pistol. There is no equivalent for handgun in the Romance languages. The general types of handguns are listed below in their order of historical appearance, each type can be classified into many sub-types. Some of these types can also be classified using the general distinction between muzzle-loading firearms and breech-loading firearms. Single-shot pistols are the simplest possible form of pistols and are known to have existed in AD1365, the earliest handguns were single-shot, muzzle-loading guns with ignition provided by inserting a smoldering match cord into a touch hole. As such, they were nothing more than miniature cannon. Improvements followed in subsequent centuries, as types of locks were invented. In the matchlock, the separate match cord was affixed to a pivot which could be tripped by a trigger. In the wheellock, an analogous to that used in todays cigarette lighters replaced the smoldering match cord. In the 17th century, the flintlock, which strikes a flint against steel, the flintlock remained the standard method of small arms ignition around two hundred years. In the 19th century, percussion caps were developed, followed shortly by modern integrated-primer cartridges, an example of a single-shot pistol is the flare gun
Handgun
–
.44 Magnum revolver and bullet, photographed with an
air-gap flash.
Handgun
–
A
9×19mm Walther P99,
German semi-automatic pistol
Handgun
–
SIG Pro semi-automatic pistol
Handgun
–
Hand cannon from the
Chinese Yuan Dynasty (1271–1368).
31.
Recoil
–
Recoil is the backward movement of a gun when it is discharged. To apply this counter-recoiling force, modern mounted guns may employ recoil buffering comprising springs and hydraulic recoil mechanisms, early cannons used systems of ropes along with rolling or sliding friction to provide forces to slow the recoiling cannon to a stop. Recoil buffering allows the maximum counter-recoil force to be lowered so that strength limitations of the gun mount are not exceeded, however, the same pressures acting on the base of the projectile are acting on the rear face of the gun chamber, accelerating the gun rearward during firing. This results in the required counter-recoiling force being proportionally lower, modern cannons also employ muzzle brakes very effectively to redirect some of the propellant gasses rearward after projectile exit. This provides a force to the barrel, allowing the buffering system. The same physics affecting recoil in mounted guns and cannons applies to hand-held guns, hands, arms and shoulders have considerable strength and elasticity for this purpose, up to certain practical limits. For this reason, establishing recoil safety standards for small arms remains challenging, a change in momentum of a mass requires a force, according to Newtons first law, known as the law of inertia, inertia simply being another term for mass. That force, applied to a mass, creates an acceleration, according to Newtons second law, the law of momentum -- changing the velocity of the mass changes its momentum. It is important to understand at this point that velocity is not simply speed, velocity is the speed of a mass in a particular direction. In a very technical sense, speed is a scalar, a magnitude, in summation, the total momentum of the system equals zero, surprisingly just as it did before the trigger was pulled. There are two conservation laws at work when a gun is fired, conservation of momentum and conservation of energy, recoil is explained by the law of conservation of momentum, and so it is easier to discuss it separately from energy. The nature of the process is determined by the force of the expanding gases in the barrel upon the gun. It is also determined by the force applied to the gun. The recoil force only acts during the time that the ejecta are still in the barrel of the gun, except for the case of zero-recoil, the counter-recoil force is smaller than the recoil force but lasts for a longer time. Since the recoil force and the force are not matched. In the zero-recoil case, the two forces are matched and the gun will not move when fired. In most cases, a gun is very close to a free-recoil condition, an example of near zero-recoil would be a gun securely clamped to a massive or well-anchored table, or supported from behind by a massive wall. For example, placing the butt of a large caliber gun directly against a wall, the recoil of a firearm, whether large or small, is a result of the law of conservation of momentum
Recoil
–
An early naval cannon, which is allowed to roll backwards slightly when fired, and therefore must be tethered with strong ropes.
Recoil
–
Recoil while firing
Smith & Wesson Model 500 revolver
Recoil
–
Real kickback of a canon
Recoil
–
Recoilless designs allow larger and faster projectiles to be shoulder-launched.
32.
Minute of arc
–
A minute of arc, arcminute, arc minute, or minute arc is a unit of angular measurement equal to 1/60 of one degree. Since one degree is 1/360 of a turn, one minute of arc is 1/21600 of a turn, a second of arc, arcsecond, or arc second is 1/60 of an arcminute, 1/3600 of a degree, 1/1296000 of a turn, and π/648000 of a radian. To express even smaller angles, standard SI prefixes can be employed, the number of square arcminutes in a complete sphere is 4 π2 =466560000 π ≈148510660 square arcminutes. The standard symbol for marking the arcminute is the prime, though a single quote is used where only ASCII characters are permitted. One arcminute is thus written 1′ and it is also abbreviated as arcmin or amin or, less commonly, the prime with a circumflex over it. The standard symbol for the arcsecond is the prime, though a double quote is commonly used where only ASCII characters are permitted. One arcsecond is thus written 1″ and it is also abbreviated as arcsec or asec. In celestial navigation, seconds of arc are used in calculations. This notation has been carried over into marine GPS receivers, which normally display latitude and longitude in the format by default. An arcsecond is approximately the angle subtended by a U. S. dime coin at a distance of 4 kilometres, a milliarcsecond is about the size of a dime atop the Eiffel Tower as seen from New York City. A microarcsecond is about the size of a period at the end of a sentence in the Apollo mission manuals left on the Moon as seen from Earth, since antiquity the arcminute and arcsecond have been used in astronomy. The principal exception is Right ascension in equatorial coordinates, which is measured in units of hours, minutes. These small angles may also be written in milliarcseconds, or thousandths of an arcsecond, the unit of distance, the parsec, named from the parallax of one arcsecond, was developed for such parallax measurements. It is the distance at which the radius of the Earths orbit would subtend an angle of one arcsecond. The ESA astrometric space probe Gaia is hoped to measure star positions to 20 microarcseconds when it begins producing catalog positions sometime after 2016, there are about 1.3 trillion µas in a turn. Currently the best catalog positions of stars actually measured are in terms of milliarcseconds, apart from the Sun, the star with the largest angular diameter from Earth is R Doradus, a red supergiant with a diameter of 0.05 arcsecond. The dwarf planet Pluto has proven difficult to resolve because its angular diameter is about 0.1 arcsecond, space telescopes are not affected by the Earths atmosphere but are diffraction limited. For example, the Hubble space telescope can reach a size of stars down to about 0. 1″
Minute of arc
–
Comparison of angular diameter of the Sun, Moon, planets and the International Space Station. To get a true representation of the sizes, view the image at a distance of 103 times the width of the "Moon: max." circle. For example, if this circle is 10 cm wide on your monitor, view it from 10.3 m away.
33.
Stadiametric rangefinding
–
Stadiametric rangefinding, or the stadia method is a technique of measuring distances with a telescopic instrument. The term stadia comes from a Greek unit of length, stadiametric rangefinding is used for surveying and in the telescopic sights of firearms, artillery pieces, or tank guns, as well as some binoculars and other optics. It is still used in long-range military sniping, but in many professional applications it is being replaced with microwave, infrared. The stadia method is based upon the principle that in similar triangles homologous sides are proportional and this means that, for a right triangle with a given angle, the ratio of adjacent side length to opposite side length is constant. In either case, the parameter is used, in conjunction with the angular measurement. An object 5 meters high, for example, will cover 1 mrad at 5000 meters, or 5 mrad at 1000 meters, or 25 mrad at 200 meters. Since the radian expresses a ratio, it is independent of the units used, stadia readings used in surveying can be taken with modern instruments such as transits, theodolites, plane-table alidades and levels. When using the measuring method, a stadia rod is held so that it appears between two stadia marks visible on the instruments reticle. The stadia rod has measurements written on it that can be read through the telescope of the instrument, an instrument equipped for stadia work has two horizontal stadia marks spaced equidistant from the center crosshair of the reticle. The interval between stadia marks in most stadia instruments gives a stadia interval factor of 100, the distance between the instrument and a stadia rod can be determined simply by multiplying the measurement between the stadia hairs by 100. The instrument must be level for this method to work directly, if the instrument line of sight is inclined, the horizontal and vertical distance components must be determined. Some instruments have additional graduations on a circle to assist with these inclined measurements. These graduated circles, known as circles, provide the value of the horizontal. This system is sufficiently precise for locating topographic details such as rivers, bridges, buildings, the stadia method of distance measurement is primarily historical for surveying purposes, as distance nowadays is mostly measured by electronic or taping methods. Total station instruments do not have stadia lines marked on the reticle, traditional methods are still used in areas where modern instruments are not common or by aficionados to antique surveying methods
Stadiametric rangefinding
–
The stadiametric rangefinder in the bottom-left corner of the
PSO-1 telescopic sight reticle can be used to determine the distance from a 1.7 meters (5 ft 7 in) tall person/object from 200 m (2) to 1,000 m (10).
Stadiametric rangefinding
–
mil-dot reticle as used in
telescopic sights.
Stadiametric rangefinding
–
If the helmeted head of a man (≈ 0.25 m tall) fits between the fourth bar and the horizontal line, the man is at approximately 100 meters distance. When the upper part of the body of a man (≈ 1 m tall) fits under the first line, he stands at approximately 400 meters distance.
34.
Angular mil
–
A milliradian, often called a mil or mrad, is an SI derived unit for angular measurement which is defined as a thousandth of a radian. Mils are used in adjustment of firearm sights by adjusting the angle of the sight compared to the barrel, Mils are also used for comparing shot groupings, or to compare the difficulty of hitting different sized targets at different distances. Using optics with mil markings in the one can make a range estimation of a known size target, or vice versa to determine a target size if the distance is known. In such applications it is useful to use a unit for target size that is a thousandth of the unit for range, for instance by using the metric units millimeters for target size and meters for range. This coincides with the definition of the milliradian where the arc length is defined as 1/1000 of the radius, a common adjustment value in firearm sights is 1 cm at 100 meters which equals 10 mm/100 m = 1/10 mil. The true definition of a milliradian is based on a circle with a radius of one. There are other definitions used for mapping and artillery which are rounded to more easily be divided into smaller parts. The milliradian was first used in the mid nineteenth century by Charles-Marc Dapples, degrees and minutes were the usual units of angular measurement but others were being proposed, with grads under various names having considerable popularity in much of northern Europe. However, Imperial Russia used a different approach, dividing a circle into equilateral triangles, around the time of the start of World War I, France was experimenting with the use of milliemes for use with artillery sights instead of decigrades. The United Kingdom was also trialing them to replace degrees and minutes and they were adopted by France although decigrades also remained in use throughout World War I. The United States, which copied many French artillery practices, adopted mils, before 2007 the Swedish defence forces used streck which is closer to the milliradian but then changed to NATO mils. After the Bolshevik Revolution and the adoption of the system of measurement the Red Army expanded the 600 unit circle into a 6000 mil one. Hence the Russian mil has a different origin than those derived from French artillery practices. In the 1950s, NATO adopted metric units of measurement for land, Mils, meters, and kilograms became standard, although degrees remained in use for naval and air purposes, reflecting civil practices. The approximation error by using the linear formula will increase as the angle increases. New shooters are often explained the principle of subtensions in order to understand that a milliradian is an angular measurement, subtension is the physical amount of space covered by an angle and varies with distance. Thus, the corresponding to a mil varies with range. Subtensions always change with distance, but a mil is always a mil regardless of distance, therefore ballistic tables and shot corrections are given in mils thereby avoiding the need of mathematical calculations
Angular mil
–
Estimating mils with hands
Angular mil
–
Mildot chart as used by snipers
Angular mil
–
Map measure M/70 of the NATO member
Denmark with the full circle divided into 6400 angular mils
35.
NATO
–
The North Atlantic Treaty Organization, also called the North Atlantic Alliance, is an intergovernmental military alliance based on the North Atlantic Treaty which was signed on 4 April 1949. The organization constitutes a system of collective defence whereby its member states agree to mutual defence in response to an attack by any external party, three NATO members are permanent members of the United Nations Security Council with the power to veto and are officially nuclear-weapon states. NATOs headquarters are located in Haren, Brussels, Belgium, while the headquarters of Allied Command Operations is near Mons. NATO is an Alliance that consists of 28 independent member countries across North America and Europe, an additional 22 countries participate in NATOs Partnership for Peace program, with 15 other countries involved in institutionalized dialogue programmes. The combined military spending of all NATO members constitutes over 70% of the global total, Members defence spending is supposed to amount to 2% of GDP. The course of the Cold War led to a rivalry with nations of the Warsaw Pact, politically, the organization sought better relations with former Warsaw Pact countries, several of which joined the alliance in 1999 and 2004. N. The Treaty of Brussels, signed on 17 March 1948 by Belgium, the Netherlands, Luxembourg, France, the treaty and the Soviet Berlin Blockade led to the creation of the Western European Unions Defence Organization in September 1948. However, participation of the United States was thought necessary both to counter the power of the USSR and to prevent the revival of nationalist militarism. He got a hearing, especially considering American anxiety over Italy. In 1948 European leaders met with U. S. defense, military and diplomatic officials at the Pentagon, marshalls orders, exploring a framework for a new and unprecedented association. Talks for a new military alliance resulted in the North Atlantic Treaty and it included the five Treaty of Brussels states plus the United States, Canada, Portugal, Italy, Norway, Denmark and Iceland. The first NATO Secretary General, Lord Ismay, stated in 1949 that the goal was to keep the Russians out, the Americans in. Popular support for the Treaty was not unanimous, and some Icelanders participated in a pro-neutrality, the creation of NATO can be seen as the primary institutional consequence of a school of thought called Atlanticism which stressed the importance of trans-Atlantic cooperation. The members agreed that an attack against any one of them in Europe or North America would be considered an attack against them all. The treaty does not require members to respond with military action against an aggressor, although obliged to respond, they maintain the freedom to choose the method by which they do so. This differs from Article IV of the Treaty of Brussels, which states that the response will be military in nature. It is nonetheless assumed that NATO members will aid the attacked member militarily, the treaty was later clarified to include both the members territory and their vessels, forces or aircraft above the Tropic of Cancer, including some Overseas departments of France. The creation of NATO brought about some standardization of allied military terminology, procedures, and technology, the roughly 1300 Standardization Agreements codified many of the common practices that NATO has achieved
NATO
–
The
North Atlantic Treaty was signed in Washington, D.C., on 4 April 1949 and was ratified by the United States that August.
NATO
–
Flag
NATO
–
The German Bundeswehr provided the largest element of the allied land forces guarding the frontier in Central Europe.
NATO
–
Reforms made under
Mikhail Gorbachev led to the end of the
Warsaw Pact.
36.
Objective (optics)
–
In optical engineering, the objective is the optical element that gathers light from the object being observed and focuses the light rays to produce a real image. Objectives can be a lens or mirror, or combinations of several optical elements. They are used in microscopes, telescopes, cameras, slide projectors, CD players, objectives are also called object lenses, object glasses, or objective glasses. The objective lens of a microscope is the one at the bottom near the sample, at its simplest, it is a very high-powered magnifying glass, with very short focal length. This is brought close to the specimen being examined so that the light from the specimen comes to a focus inside the microscope tube. The objective itself is usually a cylinder containing one or more lenses that are made of glass. Microscope objectives are characterized by two parameters, magnification and numerical aperture, the magnification typically ranges from 4× to 100×. Numerical aperture for microscope lenses typically ranges from 0.10 to 1.25, corresponding to focal lengths of about 40 mm to 2 mm, respectively. A typical microscope has three or four lenses with different magnifications, screwed into a circular nosepiece which may be rotated to select the required lens. These lenses are often color coded for easier use, the least powerful lens is called the scanning objective lens, and is typically a 4× objective. The second lens is referred to as the objective lens and is typically a 10× lens. The most powerful out of the three is referred to as the large objective lens and is typically 40–100×. Some microscopes use an oil-immersion or water-immersion lens, which can have greater than 100. These objectives are designed for use with refractive index matching oil or water. These lenses give greater resolution at high magnification, numerical apertures as high as 1.6 can be achieved with oil immersion. Camera lenses need to cover a large plane so are made up of a number of optical lens elements to correct optical aberrations. Image projectors use objective lenses that simply reverse the function of a lens, with lenses designed to cover a large image plane. In a telescope the objective is the lens at the front end of a refractor or the primary mirror of a reflecting or catadioptric telescope
Objective (optics)
–
Several objective lenses on a microscope.
Objective (optics)
–
A photographic objective,
focal length 50 mm,
aperture 1:1.4
Objective (optics)
–
Diastar projection objective from a 35 mm
movie projector, (focal length 400 mm).
Objective (optics)
–
Two Leica
oil immersion microscope objective lenses; left 100×, right 40×.
37.
Carl Zeiss AG
–
Carl Zeiss is a German manufacturer of optical systems, industrial measurements and medical devices, founded in Jena, Germany in 1846 by optician Carl Zeiss. Together with Ernst Abbe and Otto Schott they built a base for modern optics, there are currently two parts of the company, Carl Zeiss AG located in Oberkochen with important subsidiaries in Aalen, Göttingen and Munich, and Carl Zeiss GmbH located in Jena. Carl Zeiss AG is the company of the Zeiss Gruppe. The Zeiss Gruppe is located in Heidenheim and Jena, also controlled by the Carl-Zeiss-Stiftung are the glass manufacturers Schott AG and Jenaer Glas, located in Mainz and Jena respectively. Carl Zeiss is one of the oldest existing optics manufacturers in the world, Carl Zeiss opened an optics workshop in Jena in 1846. By 1847 he was making microscopes full-time, by 1861 Zeiss was considered to be among the best scientific instrument makers in Germany with about 20 people working under him with his business still growing. By 1866 the Zeiss workshop sold their 1, 000th microscope, in 1872 physicist Ernst Abbe joined Zeiss and along with Otto Schott designed greatly improved lenses for the optical instruments they were producing. After Carl Zeisss death in 1888, the business was incorporated as the Carl-Zeiss-Stiftung in 1889, by World War I, Zeiss was the worlds largest location of camera production. Zeiss Ikon represented a significant part of the production along with dozens of brands and factories. The Hensoldt System Technology division was continued by Zeiss under the Hensoldt name until 2006, as part of Nazi Germany Zwangsarbeiter program, Zeiss used forced labour during the Second World War. The destruction of the war caused many companies to divide into smaller subcompanies, at the end of the war Jena was occupied by the US Army. As part of the World War II reparations, the Soviet army took most of the existing Zeiss factories and tooling back to the Soviet Union as the Kiev camera works. The western business was restarted in Oberkochen as Opton Optische Werke Oberkochen GmbH in 1946, which became Zeiss-Opton Optische Werke Oberkochen GmbH in 1947, but was soon renamed to Carl Zeiss. West German Zeiss products were labelled Opton for sale in the Eastern bloc and this collaboration continued under Yashicas successor, Kyocera, until the latter ceased all camera production in 2005. Zeiss later produced lenses for the industry and, more recently, has again produced high-quality 35 mm camera lenses. Jenoptik GmbH was split off as a specialty company in the areas of photonics, optoelectronics, the Hensoldt AG was renamed Carl Zeiss Sports Optics GmbH on 1 October 2006. The companies of the Zeiss Gruppe in and around Dresden have branched into new technologies, screens and products for the automotive industry, today, there are arguably three companies with primarily Zeiss Ikon heritage, Zeiss Germany, the Finnish/Swedish Ikon, and the independent eastern Zeiss Ikon. On 28 June 2013, Carl Zeiss officially announced its plan to rename the brand from Carl Zeiss to simply Zeiss, all the products will be standardized under the Zeiss brand
Carl Zeiss AG
–
Carl Zeiss Jena (1910)
Carl Zeiss AG
–
We make it visible
Carl Zeiss AG
–
2 historical lenses Carl Zeiss, Jena, Nr. 145077 and Nr. 145078, Tessar 1:4,5 F=5,5cm DRP 142294 (produced before 1910).
Carl Zeiss AG
–
The manufacturer Zeiss in
Göttingen
38.
Battery (electricity)
–
An electric battery is a device consisting of one or more electrochemical cells with external connections provided to power electrical devices such as flashlights, smartphones, and electric cars. When a battery is supplying power, its positive terminal is the cathode. The terminal marked negative is the source of electrons that when connected to a circuit will flow. It is the movement of ions within the battery which allows current to flow out of the battery to perform work. Historically the term specifically referred to a device composed of multiple cells. Primary batteries are used once and discarded, the materials are irreversibly changed during discharge. Common examples are the battery used for flashlights and a multitude of portable electronic devices. Secondary batteries can be discharged and recharged multiple times using mains power from a wall socket, examples include the lead-acid batteries used in vehicles and lithium-ion batteries used for portable electronics such as laptops and smartphones. According to a 2005 estimate, the battery industry generates US$48 billion in sales each year. Batteries have much lower energy than common fuels such as gasoline. This is somewhat offset by the efficiency of electric motors in producing mechanical work. The usage of battery to describe a group of electrical devices dates to Benjamin Franklin, alessandro Volta built and described the first electrochemical battery, the voltaic pile, in 1800. This was a stack of copper and zinc plates, separated by brine-soaked paper disks, Volta did not understand that the voltage was due to chemical reactions. Although early batteries were of value for experimental purposes, in practice their voltages fluctuated. It consisted of a pot filled with a copper sulfate solution, in which was immersed an unglazed earthenware container filled with sulfuric acid. These wet cells used liquid electrolytes, which were prone to leakage and spillage if not handled correctly, many used glass jars to hold their components, which made them fragile and potentially dangerous. These characteristics made wet cells unsuitable for portable appliances, near the end of the nineteenth century, the invention of dry cell batteries, which replaced the liquid electrolyte with a paste, made portable electrical devices practical. Batteries convert chemical energy directly to electrical energy, a battery consists of some number of voltaic cells
Battery (electricity)
–
Various cells and batteries (top-left to bottom-right): two
AA, one
D, one handheld
ham radio battery, two
9-volt (PP3), two
AAA, one
C, one
camcorder battery, one
cordless phone battery.
Battery (electricity)
–
A
voltaic pile, the first battery
Battery (electricity)
–
From top to bottom: a large 4.5-volt (3R12) battery, a
D Cell, a
C cell, an
AA cell, an
AAA cell, an
AAAA cell, an
A23 battery, a 9-volt
PP3 battery, and a pair of
button cells (CR2032 and LR44).
Battery (electricity)
–
A device to check battery voltage
39.
LED
–
A light-emitting diode is a two-lead semiconductor light source. It is a p–n junction diode, which emits light when activated, when a suitable voltage is applied to the leads, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence, and the color of the light is determined by the band gap of the semiconductor. LEDs are typically small and integrated optical components may be used to shape the radiation pattern, appearing as practical electronic components in 1962, the earliest LEDs emitted low-intensity infrared light. Infrared LEDs are still used as transmitting elements in remote-control circuits. The first visible-light LEDs were also of low intensity and limited to red, modern LEDs are available across the visible, ultraviolet, and infrared wavelengths, with very high brightness. Early LEDs were often used as indicator lamps for electronic devices and they were soon packaged into numeric readouts in the form of seven-segment displays and were commonly seen in digital clocks. Recent developments in LEDs permit them to be used in environmental, LEDs have allowed new displays and sensors to be developed, while their high switching rates are also used in advanced communications technology. LEDs have many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. Light-emitting diodes are now used in applications as diverse as aviation lighting, automotive headlamps, advertising, general lighting, traffic signals, camera flashes, as of 2017, LED lights home room lighting are as cheap or cheaper than compact fluorescent lamp sources of comparable output. They are also more energy efficient and, arguably, have fewer environmental concerns linked to their disposal. Electroluminescence as a phenomenon was discovered in 1907 by the British experimenter H. J. Round of Marconi Labs, using a crystal of silicon carbide, russian inventor Oleg Losev reported creation of the first LED in 1927. His research was distributed in Soviet, German and British scientific journals, rubin Braunstein of the Radio Corporation of America reported on infrared emission from gallium arsenide and other semiconductor alloys in 1955. Braunstein observed infrared emission generated by simple diode structures using gallium antimonide, GaAs, indium phosphide, in 1957, Braunstein further demonstrated that the rudimentary devices could be used for non-radio communication across a short distance. As noted by Kroemer Braunstein …had set up a simple optical communications link, the emitted light was detected by a PbS diode some distance away. This signal was fed into an amplifier and played back by a loudspeaker. Intercepting the beam stopped the music and we had a great deal of fun playing with this setup. This setup presaged the use of LEDs for optical communication applications, by October 1961, they had demonstrated efficient light emission and signal coupling between a GaAs p-n junction light emitter and an electrically-isolated semiconductor photodetector
LED
–
Blue, pure green, and red LEDs in 5 mm diffused cases
LED
–
A bulb-shaped modern retrofit
LED lamp with aluminium
heat sink, a light
diffusing dome and
E27 screw base, using a built-in power supply working on
mains voltage
LED
–
Green electroluminescence from a point contact on a crystal of
SiC recreates
H. J. Round 's original experiment from 1907.
LED
–
LED display of a
TI-30 scientific calculator (ca. 1978), which uses plastic lenses to increase the visible digit size
40.
Scotopic vision
–
Scotopic vision is the vision of the eye under low light conditions. The term comes from Greek skotos meaning darkness and -opia meaning a condition of sight, scotopic vision is dominated by retina amacrine cells, specifically all-amacrine cells. AII-amacrine cells capture rod bipolar cell input and redistribute it to cone bipolar cells since rod-driven bipolar cells do not synapse on ganglion cells, scotopic vision occurs at luminance levels of 10−3 to 10−6 cd/m². Other species are not universally color blind in low-light conditions, the Elephant Hawk-moth displays advanced color discrimination even in dim starlight. Mesopic vision occurs in intermediate lighting conditions and is effectively a combination of scotopic and photopic vision and this however gives inaccurate visual acuity and color discrimination. In normal light, the vision of cone cells dominates and is photopic vision, there is good visual acuity and color discrimination. In scientific literature, one encounters the term scotopic lux which corresponds to photopic lux. The normal human observer’s relative wavelength sensitivity will not change due to background illumination change under scotopic vision, the wavelength sensitivity is determined by the rhodopsin photopigment. This is a red pigment and can be seen at the back of eye of animals that have a background to their eye called Tapetum lucidum. The pigment is not noticeable under photopic and mesopic conditions, the principle that the wavelength sensitivity does not change during scotopic vision led to the ability to detect two functional cone classes in individuals. If two cone classes are present, then their relative sensitivity will change the wavelength sensitivity. ”For adaption to occur at very low levels. This leads to the eye being unable to resolve high spatial frequencies in low light since the observer is spatially averaging the light signal. The behavior of the rhodopsin photopigment explains why the human eye cannot resolve lights with different spectral power distributions under low light, the reaction of this single photopigment will give the same quanta for 400 nm light and 700 nm light. Therefore, this photopigment only maps the rate of absorption and does not encode information about the spectral composition of the light. Another reason that vision is poor under scotopic vision is that rods and this many-to-one ratio leads to poor spatial frequency sensitivity. Photopic vision Mesopic vision Adaptation Averted vision Night vision Purkinje effect Rod cell Spatial frequency Marc, R. E. Anderson, J. R. Jones, B. W. Sigulinsky, C. L. Lauritzen, the AII amacrine cell connectome, A dense network hub
Scotopic vision
–
Simulated examples of vision under low light. Top: human; bottom: cat
Scotopic vision
–
The CIE 1951 scotopic
luminosity function. The horizontal axis is
wavelength in
nm.
41.
Radioactive isotopes
–
A radionuclide is an atom that has excess nuclear energy, making it unstable. During those processes, the radionuclide is said to undergo radioactive decay, the unstable nucleus is more stable following the emission, but will sometimes undergo further decay. Radioactive decay is a process at the level of single atoms. However, for a collection of atoms of an element the decay rate. The range of the half-lives of radioactive atoms have no known limits, Radionuclides occur naturally and are artificially produced in nuclear reactors, cyclotrons, particle accelerators or radionuclide generators. There are about 730 radionuclides with half-lives longer than 60 minutes, with the longest half lives are the 32 primordial radionuclides that have survived from the creation of the Solar System. Over 60 further radionuclides are detectable in nature, either as daughters of these, more than 2400 radionuclides have half-lives less than 60 minutes. Most of those are produced artificially, and have very short half-lives. For comparison, there are about 254 stable nuclides, even the lightest element, hydrogen, has a well-known radionuclide, tritium. Elements heavier than lead, and the elements technetium and promethium, unplanned exposure to radionuclides generally has a harmful effect on living organisms including humans, although low levels of exposure occur naturally without harm. However, radionuclides with suitable properties are used in medicine for both diagnosis and treatment. An imaging tracer made with radionuclides is called a radioactive tracer, a pharmaceutical drug made with radionuclides is called a radiopharmaceutical. On Earth, naturally occurring radionuclides fall into three categories, primordial radionuclides, secondary radionuclides, and cosmogenic radionuclides, Radionuclides are produced in stellar nucleosynthesis and supernova explosions along with stable nuclides. Most decay quickly but can still be observed astronomically and can play a part in understanding astronomic processes, primordial radionuclides, such as uranium and thorium, exist in the present time because their half-lives are so long they have not yet completely decayed. It is possible decay may be observed in other nuclides adding to this list of primordial radionuclides, secondary radionuclides are radiogenic isotopes derived from the decay of primordial radionuclides. They have shorter half-lives than primordial radionuclides and they arise in the decay chain of the primordial isotopes thorium-232, uranium-238 and uranium-235. Examples include the natural isotopes of polonium and radium, cosmogenic isotopes, such as carbon-14, are present because they are continually being formed in the atmosphere due to cosmic rays. Many of these radionuclides exist only in trace amounts in nature, secondary radionuclides will occur in proportion to their half-lives, so short-lived ones will be very rare
Radioactive isotopes
–
Americium-241 container in a smoke detector.
Radioactive isotopes
–
Americium-241 capsule as found in smoke detector. The circle of darker metal in the center is americium-241; the surrounding casing is aluminium.
42.
Elcan
–
Ernst Leitz Canada is a Canadian optics and electronics company owned by American defense contractor Raytheon. ELCAN manufactures devices geared towards civilian and military markets, the company currently has a location in Midland, Ontario. Elcan optics are sold through Armament Technology Incorporated and their channel of dealers, ELCAN is perhaps best known for making the 3. 4x28 power ELCAN C79 optical sight that is widely used on the Diemaco C7, FN MINIMI, FN MAG and CZ-805 BREN families of firearms. The C79 sight is not designed as a sniper sight per se, the M145 machine gun optic differs from the C79s standard 3. 4x sight in that ballistic compensation is provided for in the reticle, rather than in the mount. Reticle illumination is by a battery-powered LED with eleven intensity settings and it is used by the US military for its M249s and M240s. ELCAN manufactures the Specter line of combat optics and they come in a variety of configurations. Specter DR1. 5x/6x, DR 1x/4x, 4x Optical Sight, Specter M145 Specter 3x Optical Sight Aimpoint AB Trijicon EOTech ITL MARS Official website Armament Technology Incorporated, distributor
Elcan
–
An ELCAN C79 3.4x28 sight.
43.
C79 Optical Sight
–
The C79 Optical sight is a small arms telescopic sight of 3. 4×28 magnification. A tritium illuminated reticle provides for normal and low-light conditions sighting, the sight itself is nitrogen-purged to prevent fogging and is covered with an armoured coating of rubber. It can be mounted to a variety of rifles and light machine guns using the M1913 Picatinny rail mounting system or the similar Diemaco rail system found on small arms produced by Diemaco/Colt Canada and it is manufactured by Elcan and can be found on military service weapons around the world. Its Elcan product name is the SpecterOS3. 4x, although in Canadian service, similar rifle sights are the Sight Unit Small Arms, Trilux and the Advanced Combat Optical Gunsight. It is also used in the armies of Denmark, the Royal Netherlands Army and Netherlands Marine Corps, in Canadian service, all C7A1 and -A2 rifles come equipped with a C79 sight as standard. The C7A1 uses a C79 sight, which is distinguished by its matte black rubber overcoating. After reviewing feedback from the soldiers who used the sight, Elcan produced the fourth generation mount C79, known as the C79A2, the C79A2 sight is a component of the C7A2 mid-life update program of the Canadian Forces inventory of C7A1 rifle systems. The older rifles and sights are meant to be exchanged 1,1, in Dutch service it is used on the Diemaco C7, C7A1 and C8, FN minimi and FN MAG series of firearms. The reticle of the C79 sight was designed to serve on the C9 Light Machine Gun, the reticle consists of a single vertical post with a sharp tip in the center. The tip is flanked by horizontal Mil-bars on either side, under the left-hand Mil-bar, a second horizontal bar was added for judging distances. The tritium light source is an isotope with a half-life of 12.32 years that gradually loses its brightness due to radioactive decay. It is to be replaced every 8–12 years to maintain adequate brightness, the C79 sight is attached to a mounting rail on the receiver of the weapon. On CF weapons, this is in the form of a modified Weaver rail, two adjustment knobs are used to secure the base to the receiver. A bore-sighting device is used to roughly zero the sight before a first-time shooter takes it to the range. Sighting in a C79 sight is normally done at a range of 200 m, windage adjustments are made on the left hand side of the base, using a flat object such as a flat-head screwdriver or a coin. The windage adjustment is intended only for the sighting in procedure of the C79. Elevation adjustments are made via a knob and are adjusted from 200 to 800 m. To bring the sight to a proper elevation zero, a small gate must be elevated which disconnects the elevation cam, for precise shooting, the gate is usually left open to allow for finer adjustments than the rougher presets
C79 Optical Sight
–
A C79 Optical Sight
C79 Optical Sight
–
A Canadian soldier with a C7A1 assault rifle equipped with a C79
C79 Optical Sight
–
C79 3.4x28 sight adjustment controls
C79 Optical Sight
–
A Canadian soldier fires the current issue
C7A2 rifle at the range with a C79A2 sight.
44.
Tritium
–
Tritium is a radioactive isotope of hydrogen. The nucleus of tritium contains one proton and two neutrons, whereas the nucleus of protium contains one proton and no neutrons, naturally occurring tritium is extremely rare on Earth, where trace amounts are formed by the interaction of the atmosphere with cosmic rays. It can be produced by irradiating lithium metal or lithium bearing ceramic pebbles in a nuclear reactor, the name of this isotope is derived from the Greek word τρίτος meaning third. While tritium has several different experimentally determined values of its half-life and it decays into helium-3 by beta decay as in this nuclear equation, and it releases 18.6 keV of energy in the process. The electrons kinetic energy varies, with an average of 5.7 keV, beta particles from tritium can penetrate only about 6.0 mm of air, and they are incapable of passing through the dead outermost layer of human skin. The unusually low energy released in the beta decay makes the decay appropriate for absolute neutrino mass measurements in the laboratory. The low energy of tritiums radiation makes it difficult to detect tritium-labeled compounds except by using liquid scintillation counting, Tritium is produced in nuclear reactors by neutron activation of lithium-6. This is possible with neutrons of any energy, and is an exothermic reaction yielding 4.8 MeV, in comparison, the fusion of deuterium with tritium releases about 17.6 MeV of energy. High-energy neutrons can produce tritium from lithium-7 in an endothermic reaction. This was discovered when the 1954 Castle Bravo nuclear test produced a high yield. High-energy neutrons irradiating boron-10 will also produce tritium, A more common result of boron-10 neutron capture is 7Li. The reactions requiring high neutron energies are not attractive production methods for peaceful applications, Tritium is also produced in heavy water-moderated reactors whenever a deuterium nucleus captures a neutron. This reaction has a quite small absorption cross section, making water a good neutron moderator. Even so, cleaning tritium from the moderator may be desirable after several years to reduce the risk of its escaping to the environment. Ontario Power Generations Tritium Removal Facility processes up to 2,500 tonnes of water a year. Deuteriums absorption cross section for thermal neutrons is about 0.52 millibarns, whereas that of oxygen-16 is about 0.19 millibarns and that of oxygen-17 is about 240 millibarns. Tritium is a product of the nuclear fission of uranium-235, plutonium-239. The release or recovery of tritium needs to be considered in the operation of reactors, especially in the reprocessing of nuclear fuels
Tritium
–
Radioluminescent 1.8
curies (67
GBq) 6 by 0.2 inches (152.4 mm × 5.1 mm) tritium vials are thin, tritium-gas-filled glass vials whose inner surfaces are coated with a
phosphor. The vial shown here is brand-new.
Tritium
–
Full table
Tritium
–
Swiss Military Watch Commander model with tritium-illuminated face
45.
Advanced Combat Optical Gunsight
–
Advanced Combat Optical Gunsights are a series of telescopic sights manufactured by Trijicon. The ACOG was originally designed to be used on the M16 rifle and M4 carbine, models provide fixed power magnification levels from 1. 5× to 6×. ACOG reticles are illuminated at night by an internal phosphor, some versions have an additional daytime reticle illumination via a passive external fiber optic light pipe or are LED-illuminated using a battery. The ACOG is available in a variety of configurations from the manufacturer with different reticles, illumination, most ACOGs do not use batteries for reticle illumination, being designed to use internal phosphor illumination provided by the radioactive decay of tritium. The tritium illumination has a life of 10–15 years. Some versions of the ACOG have an additional daytime reticle illumination via a passive external fiber optic light pipe, reticles have other features such as a bullet drop compensator and other different reticle shapes such as chevrons. Some ACOG models incorporate rudimentary ghost ring iron sights as a backup for targets that are within 50 m, most ACOG models, when mounted to a carry handle, have an open space through the mount to allow the use of the rifles iron sights without removing the scope. Others include Docter or Trijicon reflex sights mounted on top, the ACOG ECOS line features both of these secondary sighting systems on the same scope. Other features include Picatinny rails, flip caps, and the ability to be waterproof up to 11 m, although the ACOG is designed for the Picatinny rail of the M16A4 and M4, it can be mounted on the carrying handles of previous models by using a special adapter. Several ACOG models are designed to be used with the Bindon Aiming Concept, the technique is essentially using the illuminated part of the reticle and its focusing rear eyepiece as a collimator sight. In this both-eyes-open technique the brain superimposes the aiming reticle on the target, an added part of the technique is to shift focus after acquisition to the dominant eye/telescopic image for more accurate shooting. This overcomes the problem of centering or acquiring fast traversing targets common with all telescopic sights, only certain models of the ACOG are designed with bright enough daylight-lit fiber optic or battery-powered LED reticles that facilitate this technique. Greece, Hellenic Army Commandos and SFs United Kingdom, British Army, United States, United States armed forces, various law enforcement agencies. This sight is designated the M150 Rifle Combat Optic in Army service, after an October 2005 evaluation, the USMC fielded 115,000 ACOGs so that every rifle and every carbine in the Marine Corps inventory would be equipped with one. Other Trijicon models have seen service after being purchased at the unit. Trijicon has been the subject of criticism for inscribing a reference to a Bible verse alongside the model numbers on their ACOG sights. Starting in late 2009, Trijicon began shipping sights to the U. S. military without the Bible verse, sight SUSAT, 4× telescopic sight with tritium-powered illumination similar to the ACOG Article on the Trijicon ACOG An italian article about TA44S
Advanced Combat Optical Gunsight
–
The
United States Army fielded the TA31RCO variant of the ACOG which is designated as the M150 RCO.
Advanced Combat Optical Gunsight
–
ACOG fitted
U.S. Marine M16A4 with an AN/PVQ-31.
Advanced Combat Optical Gunsight
–
USMC 4x32 rifle reticle
Advanced Combat Optical Gunsight
–
TA648 6x48 Machine Gun Optic reticle
46.
Radioactive decay
–
A material containing such unstable nuclei is considered radioactive. Certain highly excited short-lived nuclear states can decay through neutron emission, or more rarely, however, for a collection of atoms, the collections expected decay rate is characterized in terms of their measured decay constants or half-lives. This is the basis of radiometric dating, the half-lives of radioactive atoms have no known upper limit, spanning a time range of over 55 orders of magnitude, from nearly instantaneous to far longer than the age of the universe. A radioactive nucleus with spin can have no defined orientation. If there are multiple particles produced during a single decay, as in decay, their relative angular distribution. Such a parent process could be a previous decay, or a nuclear reaction, the decaying nucleus is called the parent radionuclide, and the process produces at least one daughter nuclide. Except for gamma decay or internal conversion from an excited state. When the number of changes, an atom of a different chemical element is created. The first decay processes to be discovered were alpha decay, beta decay, alpha decay occurs when the nucleus ejects an alpha particle. This is the most common process of emitting nucleons, but highly excited nuclei can eject single nucleons, or in the case of cluster decay, specific light nuclei of other elements. Beta decay occurs when the nucleus emits an electron or positron, the nucleus may capture an orbiting electron, causing a proton to convert into a neutron in a process called electron capture. All of these result in a well-defined nuclear transmutation. By contrast, there are radioactive decay processes that do not result in a nuclear transmutation, another type of radioactive decay results in products that vary, appearing as two or more fragments of the original nucleus with a range of possible masses. For a summary table showing the number of stable and radioactive nuclides in each category, there are 29 naturally occurring chemical elements on Earth that are radioactive. They are those that contain 34 radionuclides that date before the time of formation of the solar system, well-known examples are uranium and thorium, but also included are naturally occurring long-lived radioisotopes, such as potassium-40. Radioactivity was discovered in 1896 by the French scientist Henri Becquerel and these materials glow in the dark after exposure to light, and he suspected that the glow produced in cathode ray tubes by X-rays might be associated with phosphorescence. He wrapped a photographic plate in black paper and placed various phosphorescent salts on it, all results were negative until he used uranium salts. The uranium salts caused a blackening of the plate in spite of the plate being wrapped in black paper and these radiations were given the name Becquerel Rays
Radioactive decay
–
Pierre and Marie Curie in their Paris laboratory, before 1907
Radioactive decay
–
Alpha decay is one type of radioactive decay, in which an atomic nucleus emits an
alpha particle, and thereby transforms (or "decays") into an atom with a
mass number decreased by 4 and
atomic number decreased by 2.
Radioactive decay
–
Taking an X-ray image with early
Crookes tube apparatus in 1896. The Crookes tube is visible in the centre. The standing man is viewing his hand with a
fluoroscope screen; this was a common way of setting up the tube. No precautions against radiation exposure are being taken; its hazards were not known at the time.
Radioactive decay
–
Gamma-ray energy spectrum of uranium ore (inset). Gamma-rays are emitted by decaying
nuclides, and the gamma-ray energy can be used to characterize the decay (which nuclide is decaying to which). Here, using the gamma-ray spectrum, several nuclides that are typical of the decay chain of 238 U have been identified: 226 Ra, 214 Pb, 214 Bi.
47.
Fiber optics
–
An optical fiber or optical fibre is a flexible, transparent fiber made by drawing glass or plastic to a diameter slightly thicker than that of a human hair. Fibers are also used for illumination, and are wrapped in bundles so that they may be used to carry images, thus allowing viewing in confined spaces, as in the case of a fiberscope. Specially designed fibers are used for a variety of other applications, some of them being fiber optic sensors. Optical fibers typically include a transparent core surrounded by a transparent cladding material with an index of refraction. Light is kept in the core by the phenomenon of internal reflection which causes the fiber to act as a waveguide. Fibers that support many propagation paths or transverse modes are called multi-mode fibers, multi-mode fibers generally have a wider core diameter and are used for short-distance communication links and for applications where high power must be transmitted. Single-mode fibers are used for most communication links longer than 1,000 meters, being able to join optical fibers with low loss is important in fiber optic communication. This is more complex than joining electrical wire or cable and involves careful cleaving of the fibers, precise alignment of the cores. For applications that demand a permanent connection a fusion splice is common, in this technique, an electric arc is used to melt the ends of the fibers together. Another common technique is a splice, where the ends of the fibers are held in contact by mechanical force. Temporary or semi-permanent connections are made by means of specialized optical fiber connectors, the field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics. The term was coined by Indian physicist Narinder Singh Kapany who is acknowledged as the father of fiber optics. Guiding of light by refraction, the principle that makes fiber optics possible, was first demonstrated by Daniel Colladon, John Tyndall included a demonstration of it in his public lectures in London,12 years later. When the ray passes from water to air it is bent from the perpendicular. If the angle which the ray in water encloses with the perpendicular to the surface be greater than 48 degrees, the angle which marks the limit where total reflection begins is called the limiting angle of the medium. For water this angle is 48°27′, for flint glass it is 38°41′, unpigmented human hairs have also been shown to act as an optical fiber. Practical applications, such as close internal illumination during dentistry, appeared early in the twentieth century, image transmission through tubes was demonstrated independently by the radio experimenter Clarence Hansell and the television pioneer John Logie Baird in the 1920s. The principle was first used for medical examinations by Heinrich Lamm in the following decade
Fiber optics
–
A bundle of optical fibers
Fiber optics
–
Fiber crew installing a 432-count fiber cable underneath the streets of Midtown Manhattan, New York City
Fiber optics
–
A
TOSLINK fiber optic audio cable with red light being shone in one end transmits the light to the other end
Fiber optics
–
A
wall-mount cabinet containing optical fiber interconnects. The yellow cables are
single mode fibers; the orange and aqua cables are
multi-mode fibers: 50/125 µm OM2 and 50/125 µm OM3 fibers respectively.
48.
Parallax
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The term is derived from the Greek word παράλλαξις, meaning alternation. Due to foreshortening, nearby objects have a larger parallax than more distant objects when observed from different positions, astronomers use the principle of parallax to measure distances to the closer stars. Here, the parallax is the semi-angle of inclination between two sight-lines to the star, as observed when the Earth is on opposite sides of the Sun in its orbit. Parallax also affects optical instruments such as rifle scopes, binoculars, microscopes, many animals, including humans, have two eyes with overlapping visual fields that use parallax to gain depth perception, this process is known as stereopsis. In computer vision the effect is used for stereo vision, and there is a device called a parallax rangefinder that uses it to find range. A simple everyday example of parallax can be seen in the dashboard of motor vehicles that use a needle-style speedometer gauge. When viewed from directly in front, the speed may show exactly 60, as the eyes of humans and other animals are in different positions on the head, they present different views simultaneously. This is the basis of stereopsis, the process by which the brain exploits the parallax due to the different views from the eye to gain depth perception, animals also use motion parallax, in which the animals move to gain different viewpoints. For example, pigeons bob their heads up and down to see depth, the motion parallax is exploited also in wiggle stereoscopy, computer graphics which provide depth cues through viewpoint-shifting animation rather than through binocular vision. Parallax arises due to change in viewpoint occurring due to motion of the observer, of the observed, what is essential is relative motion. By observing parallax, measuring angles, and using geometry, one can determine distance, astronomers also use the word parallax as a synonym for distance measurent by other methods, see parallax #Astronomy. In a geostatic model, the movement of the star would have to be taken as real with the star oscillating across the sky with respect to the background stars, the parsec is defined as the distance for which the annual parallax is 1 arcsecond. Annual parallax is measured by observing the position of a star at different times of the year as the Earth moves through its orbit. Measurement of annual parallax was the first reliable way to determine the distances to the closest stars, the first successful measurements of stellar parallax were made by Friedrich Bessel in 1838 for the star 61 Cygni using a heliometer. Stellar parallax remains the standard for calibrating other measurement methods, accurate calculations of distance based on stellar parallax require a measurement of the distance from the Earth to the Sun, now based on radar reflection off the surfaces of planets. The angles involved in these calculations are very small and thus difficult to measure, the nearest star to the Sun, Proxima Centauri, has a parallax of 0.7687 ±0.0003 arcsec. This angle is approximately that subtended by an object 2 centimeters in diameter located 5.3 kilometers away, the fact that stellar parallax was so small that it was unobservable at the time was used as the main scientific argument against heliocentrism during the early modern age. In 1989, the satellite Hipparcos was launched primarily for obtaining improved parallaxes and proper motions for over 100,000 nearby stars, increasing the reach of the method tenfold
Parallax
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This image demonstrates parallax. The
Sun is visible above the streetlight. The reflection in the water is a
virtual image of the Sun and the streetlight. The location of the virtual image is below the surface of the water, offering a different vantage point of the streetlight, which appears to be shifted relative to the more distant Sun.
Parallax
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A simplified illustration of the parallax of an object against a distant background due to a perspective shift. When viewed from "Viewpoint A", the object appears to be in front of the blue square. When the viewpoint is changed to "Viewpoint B", the object appears to have moved in front of the red square.
Parallax
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Contax III rangefinder camera with
macro photography setting. Because the viewfinder is on top of the lens and of the close proximity of the subject, goggles are fitted in front of the rangefinder and a dedicated viewfinder installed to compensate for parallax.
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