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Periscope

Periscope

Overview
A periscope is an instrument for observation from a concealed position. In its simplest form it consists of a tube with mirror
Mirror
A mirror is an object that reflects light or sound in a way that preserves much of its original quality prior to its contact with the mirror. Some mirrors also filter out some wavelengths, while preserving other wavelengths in the reflection...

s at each end set parallel to each other at a 45-degree angle.
This form of periscope, with the addition of two simple lenses, served for observation purposes in the trenches during World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. Military personnel also use periscopes in some gun turret
Gun turret
A gun turret is a weapon mount that protects the crew or mechanism of a projectile-firing weapon and at the same time lets the weapon be aimed and fired in many directions.The turret is also a rotating weapon platform...

s and in armoured vehicles.

More complex periscopes, using prism
Prism (optics)
In optics, a prism is a transparent optical element with flat, polished surfaces that refract light. The exact angles between the surfaces depend on the application. The traditional geometrical shape is that of a triangular prism with a triangular base and rectangular sides, and in colloquial use...

s instead of mirrors, and providing magnification, operate on submarine
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

s.
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Encyclopedia
A periscope is an instrument for observation from a concealed position. In its simplest form it consists of a tube with mirror
Mirror
A mirror is an object that reflects light or sound in a way that preserves much of its original quality prior to its contact with the mirror. Some mirrors also filter out some wavelengths, while preserving other wavelengths in the reflection...

s at each end set parallel to each other at a 45-degree angle.
This form of periscope, with the addition of two simple lenses, served for observation purposes in the trenches during World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. Military personnel also use periscopes in some gun turret
Gun turret
A gun turret is a weapon mount that protects the crew or mechanism of a projectile-firing weapon and at the same time lets the weapon be aimed and fired in many directions.The turret is also a rotating weapon platform...

s and in armoured vehicles.

More complex periscopes, using prism
Prism (optics)
In optics, a prism is a transparent optical element with flat, polished surfaces that refract light. The exact angles between the surfaces depend on the application. The traditional geometrical shape is that of a triangular prism with a triangular base and rectangular sides, and in colloquial use...

s instead of mirrors, and providing magnification, operate on submarine
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

s. The overall design of the classical submarine periscope is very simple: two telescopes pointed into each other. If the two telescopes have different individual magnification, the difference between them causes an overall magnification or reduction.

Early examples


Johann Gutenberg, better known for his contribution to printing
Printing
Printing is a process for reproducing text and image, typically with ink on paper using a printing press. It is often carried out as a large-scale industrial process, and is an essential part of publishing and transaction printing....

 technology, marketed a kind of periscope in the 1430s to enable pilgrims to see over the heads of the crowd at the vigintennial religious festival at Aachen
Aachen
Aachen has historically been a spa town in North Rhine-Westphalia, Germany. Aachen was a favoured residence of Charlemagne, and the place of coronation of the Kings of Germany. Geographically, Aachen is the westernmost town of Germany, located along its borders with Belgium and the Netherlands, ...

. Johannes Hevelius
Johannes Hevelius
Johannes Hevelius Some sources refer to Hevelius as Polish:Some sources refer to Hevelius as German:*Encyplopedia Britannica * of the Royal Society was a councilor and mayor of Danzig , Pomeranian Voivodeship, in the Polish-Lithuanian Commonwealth...

 described an early periscope with lenses in 1647 in his work Selenographia, sive Lunae descriptio
Selenographia, sive Lunae descriptio
Selenographia, sive Lunae descriptio is a milestone work by Johannes Hevelius, printed in 1647. In his treatise Hevelius reflected on the difference between his own work and that of Galileo Galilei. Hevelius remarked that the quality of Galileo's representations of the Moon in Sidereus nuncius ...

[Selenography, or an account of the Moon]. Hevelius saw military applications for his invention. In 1854, E.H. Marie-Davy (Edme Hippolyte) invented the first naval periscope, consisting in a vertical tube with two small mirrors fixed at each end at 45°. Simon Lake
Simon Lake
Simon Lake was a Quaker American mechanical engineer and naval architect who obtained over two hundred patents for advances in naval design and competed with John Philip Holland to build the first submarines for the United States Navy.Born in Pleasantville, New Jersey, Lake joined his father's...

 used periscopes in his submarines in 1902. Sir Howard Grubb
Howard Grubb
Sir Howard Grubb FRS was an optical designer from Dublin, Ireland. He was head of a family firm that made large optical telescopes, telescope drive controls, and other optical instruments...

 perfected the device in World War I. Morgan Robertson
Morgan Robertson
Morgan Andrew Robertson was a well-known American author of short stories and novels, and the self-claimed inventor of the periscope.He is best known for his short novel Futility, first published in 1898...

 (1861–1915) claimed to have tried to patent the periscope: he described a submarine using a periscope in his fictional works.

Periscopes, in some cases fixed to rifles
Periscope rifle
A periscope rifle was first invented by Sergeant William Beech, a builder's foreman in civilian life, of the 2nd Battalion NSW, Australian Imperial Force, in May 1915...

, served in World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

 to enable soldiers to see over the tops of trenches
Trench warfare
Trench warfare is a form of occupied fighting lines, consisting largely of trenches, in which troops are largely immune to the enemy's small arms fire and are substantially sheltered from artillery...

, thus avoiding exposure to enemy fire (especially from snipers).

Tank
Tank
A tank is a tracked, armoured fighting vehicle designed for front-line combat which combines operational mobility, tactical offensive, and defensive capabilities...

s use periscopes extensively: they enable drivers or tank commanders to inspect their situation without leaving the safety of the tank. An important development, the Gundlach rotary periscope
Rudolf Gundlach
Rudolf Gundlach was a Polish engineer, inventor and tank designer. He headed the design division of the Armored Weapons Development Office .He was the chief designer of the Ursus wz...

, incorporated a rotating top; this allowed a tank commander to obtain a 360-degree field of view without moving his seat. This design, patented by Rudolf Gundlach
Rudolf Gundlach
Rudolf Gundlach was a Polish engineer, inventor and tank designer. He headed the design division of the Armored Weapons Development Office .He was the chief designer of the Ursus wz...

 in 1936, first saw use in the Polish 7-TP light tank (produced from 1935 to 1939). As a part of Polish–British pre-World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 military cooperation, the patent was sold to Vickers-Armstrong for use in British
British Army
The British Army is the land warfare branch of Her Majesty's Armed Forces in the United Kingdom. It came into being with the unification of the Kingdom of England and Scotland into the Kingdom of Great Britain in 1707. The new British Army incorporated Regiments that had already existed in England...

 tanks, including the Crusader
Crusader tank
The Tank, Cruiser, Mk VI or A15 Crusader was one of the primary British cruiser tanks of the early part Second World War and perhaps the most important British tank of the North African Campaign...

, Churchill
Churchill tank
The Tank, Infantry, Mk IV was a heavy British infantry tank used in the Second World War, best known for its heavy armour, large longitudinal chassis with all-around tracks with multiple bogies, and its use as the basis of many specialist vehicles. It was one of the heaviest Allied tanks of the war...

, Valentine
Valentine tank
The Tank, Infantry, Mk III, Valentine was an infantry tank produced in the United Kingdom during the Second World War. More than 8,000 of the type were produced in 11 different marks plus various purpose-built variants, accounting for approximately a quarter of wartime British tank production...

, and Cromwell
Cromwell tank
Tank, Cruiser, Mk VIII, Cromwell ,The designation as the eighth Cruiser tank design, its name given for ease of reference and its General Staff specification number respectively and the related Centaur tank, were one of the most successful series of cruiser tanks fielded by Britain in the Second...

. The technology was also transferred to the American Army
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...

 for use in its tanks, including the Sherman
M4 Sherman
The M4 Sherman, formally Medium Tank, M4, was the primary tank used by the United States during World War II. Thousands were also distributed to the Allies, including the British Commonwealth and Soviet armies, via lend-lease...

. The USSR
Red Army
The Workers' and Peasants' Red Army started out as the Soviet Union's revolutionary communist combat groups during the Russian Civil War of 1918-1922. It grew into the national army of the Soviet Union. By the 1930s the Red Army was among the largest armies in history.The "Red Army" name refers to...

 later copied the design and used it extensively in its tanks (including the T-34
T-34
The T-34 was a Soviet medium tank produced from 1940 to 1958. Although its armour and armament were surpassed by later tanks of the era, it has been often credited as the most effective, efficient and influential design of World War II...

 and T-70
T-70
The T-70 was a light tank used by the Red Army during World War II, replacing both the T-60 scout tank for reconnaissance and the T-50 light infantry tank for infantry support. The T-80 light tank was a more advanced version of the T-70 with a two-man turret—it was only produced in very small...

); Germany
Wehrmacht
The Wehrmacht – from , to defend and , the might/power) were the unified armed forces of Nazi Germany from 1935 to 1945. It consisted of the Heer , the Kriegsmarine and the Luftwaffe .-Origin and use of the term:...

 also made and used copies.
Periscope is widely used in many areas but mainly in submarines and it is very helpful in terms of technology

Naval use


Periscopes allow a submarine, when submerged at a shallow depth, to search visually for nearby targets and threats on the surface of the water and in the air. When not in use, a submarine's periscope retracts into the hull. A submarine commander in tactical conditions must exercise discretion when using his periscope, since it creates a visible wake and may also become detectable by radar, giving away the sub's position.

The Frenchman Marie Davey built a simple, fixed naval periscope using mirrors in 1854. Thomas H. Doughty of the US Navy later invented a prismatic version for use in the American Civil War
American Civil War
The American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...

 of 1861-1865.

Submarines adopted periscopes early. Captain Arthur Krebs
Arthur Krebs
Arthur Constantin Krebs was a French officer and pioneer in automotive engineering....

 adapted two on the experimental French submarine Gymnote
Gymnote
The Gymnote was one of the world's first all-electric submarines.Launched on 24 September 1888, she was developed in France following early experiments by Dupuy de Lôme, and, after his death, by Gustave Zédé and Arthur Krebs, who completed the project...

in 1888 and 1889. The Spanish inventor Isaac Peral equipped his submarine Peral
Peral Submarine
The Peral was the first electric battery powered submarine. Its operational abilities has led some to call it the first U-boat. -Conception:...

(developed in 1886 but launched on September 8, 1888) with a fixed, non-retractable periscope that used a combination of prisms to relay the image to the submariner. (Peral also developed a primitive gyroscope for submarine navigation and pioneered the ability to fire live torpedoes while submerged.)

The invention of the collapsible periscope for use in submarine warfare is usually credited to Simon Lake
Simon Lake
Simon Lake was a Quaker American mechanical engineer and naval architect who obtained over two hundred patents for advances in naval design and competed with John Philip Holland to build the first submarines for the United States Navy.Born in Pleasantville, New Jersey, Lake joined his father's...

 in 1902. Lake called his device the omniscope or skalomniscope. There is also a report that an Italian, Triulzi, demonstrated such a device in 1901, calling it a cleptoscope.

modern submarine periscopes incorporate lenses for magnification and function as telescope
Telescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...

s. They typically employ prism
Prism (optics)
In optics, a prism is a transparent optical element with flat, polished surfaces that refract light. The exact angles between the surfaces depend on the application. The traditional geometrical shape is that of a triangular prism with a triangular base and rectangular sides, and in colloquial use...

s and total internal reflection
Total internal reflection
Total internal reflection is an optical phenomenon that happens when a ray of light strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface. If the refractive index is lower on the other side of the boundary and the incident angle is...

 instead of mirrors, because prisms, which do not require coatings on the reflecting surface, are much more rugged than mirrors. They may have additional optical capabilities such as range-finding and targeting. The mechanical systems of submarine periscopes typically use hydraulic
Hydraulic machinery
Hydraulic machines are machinery and tools that use liquid fluid power to do simple work. Heavy equipment is a common example.In this type of machine, hydraulic fluid is transmitted throughout the machine to various hydraulic motors and hydraulic cylinders and which becomes pressurised according to...

s and need to be quite sturdy to withstand the drag through water. The periscope chassis may also support a radio or radar antenna.

Submarines traditionally had two periscopes; a navigation or observation periscope and a targeting, or commander's, periscope. Navies originally mounted these periscopes in the conning tower
Conning tower
A conning tower is a raised platform on a ship or submarine, often armored, from which an officer can con the vessel; i.e., give directions to the helmsman. It is usually located as high on the ship as practical, to give the conning team good visibility....

, one forward of the other in the narrow hulls of diesel-electric submarines. In the much wider hulls of US Navy submarines the two operate side-by-side. The observation scope, used to scan the sea surface and sky, typically had a wide field of view and no magnification or low-power magnification. The targeting or "attack" periscope, by comparison, had a narrower field of view and higher magnification. In World War II and earlier submarines it was the only means of gathering target data to accurately fire a torpedo
Torpedo
The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

, since sonar
Sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

 was not yet sufficiently advanced for this purpose (ranging with sonar required emission of an electronic "ping" that gave away the location of the submarine) and most torpedoes were unguided.

21st-century submarines do not necessarily have periscopes. The United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

's Virginia-class submarines
Virginia class submarine
The Virginia class is a class of nuclear-powered fast attack submarines in service with the United States Navy. The submarines are designed for a broad spectrum of open-ocean and littoral missions...

 and the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

's Astute Class submarine
Astute class submarine
The Astute-class is the latest class of nuclear-powered fleet submarines in service with the Royal Navy. The class sets a new standard for the Royal Navy in terms of weapons load, communication facilities and stealth. The boats are being constructed by BAE Systems Submarine Solutions at...

s instead use photonics mast
Photonics mast
A photonics mast is a sensor similar in concept to a submarine periscope, except that it doesn't require a periscope tube thus freeing design space duringconstruction and limiting risks of water leakage in the event of damage...

s, pioneered by the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

's HMS Trenchant
HMS Trenchant (S91)
HMS Trenchant is a nuclear-powered fleet submarine of the Royal Navy built by Vickers Shipbuilding, Barrow-in-Furness. Trenchant is currently in service and is based at HMNB Devonport.The submarine was ordered on 22 March 1983...

, which lift an electronic imaging sensor-set above the water. Signals from the sensor-set travel electronically to workstations in the submarine's control center. While the cables carrying the signal must penetrate the submarine's hull, they use a much smaller and more easily sealed—and therefore less expensive and safer—hull opening than those required by periscopes. Eliminating the telescoping tube running through the conning tower also allows greater freedom in designing the pressure hull and in placing internal equipment.

See also

  • Coincidence rangefinder
    Coincidence rangefinder
    A coincidence rangefinder is a type of rangefinder that uses mechanical and optical principles to allow an operator to determine the distance to a visible object....

  • Relay lens
    Relay lens
    In optics, a relay lens is a lens or lens group that inverts an image and extends the optical tube. Relay lenses are found in endoscopes and periscopes for the purpose of extending the system, and before eyepieces for the purpose of inverting an image...

  • Rangefinder
    Rangefinder
    A rangefinder is a device that measures distance from the observer to a target, for the purposes of surveying, determining focus in photography, or accurately aiming a weapon. Some devices use active methods to measure ; others measure distance using trigonometry...

  • Vickers Tank Periscope MK.IV
    Vickers Tank Periscope MK.IV
    The Vickers Tank Periscope MK.IV, invented by Polish engineer Rudolf Gundlach, was first patented in 1936 as Gundlach Peryskop obrotowy. It was the first device to allow the tank commander to have a 360-degree view from his turret, with a single periscope...


External links