Principle of the periscope. The periscope on the left uses mirrors at location "a" whereas the right uses prisms at "b". The observer is "c".

A periscope is an instrument for observation from a concealed position. In its simplest form it is a tube in each end of which are mirrors set parallel to each other and at an angle of 45 with a line between them. A mirror is an object with a surface that has good Specular reflection; that is it is smooth enough to form an Image.

A periscope may be used as a toy or for seeing over people's heads in a crowd. This article is about playthings For other uses of the term see Toy (disambiguation. This form of periscope, with the addition of two simple lenses, was used for observation purposes in the trenches during World War I. World War I (abbreviated WWI; also known as the First World War, the Great War, and the War to End All Periscopes are also used in some gun turrets and armored vehicles. A gun turret is a device 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 An armoured fighting vehicle ( AFV) is a military Vehicle, protected by armour and armed with Weapons Most AFVs are equipped for driving in rugged

More complex periscopes, using prisms instead of mirrors, and providing magnification, are used on submarines. In Optics, a prism is a transparent optical element with flat polished surfaces that refract Light. A submarine is a Watercraft that can operate independently below water as distinct from a Submersible that has only limited underwater capability 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 technology, marketed a periscope in the 1430s to enable pilgrims to see over the heads of the crowd at the vigintennial religious festival at Aachen. Johannes Gensfleisch zur Laden zum Gutenberg ( 1398 &ndash February 3, 1468) was a German Goldsmith and printer who is credited Printing is a process for reproducing text and image typically with ink on Paper using a printing press ( Ripuarian: Oche, Dutch: Aken, Spanish: Aquisgrán, Italian: Aquisgrana, French, Simon Lake used periscopes in his submarines in 1902. For the writer Simon Lake see the pseudonym of Charles L Grant. Sir Howard Grubb perfected it in World War I[1]. Sir Howard Grubb FRS (1844-1931 was a designer and maker of Telescopes from Dublin. Morgan Robertson claims to have patented the periscope, and has described submarine using a periscope in his fictional works. Morgan Robertson ( September 30 1861 &ndash March 24 1915) was a well-known American Author of short stories and Periscopes, in some cases fixed to rifles, were used in World War I to enable soldiers to see out of the trenches. World War I (abbreviated WWI; also known as the First World War, the Great War, and the War to End All Periscopes are extensively used in tanks, enabling drivers or tank's commanders to inspect the situation without leaving the safety of the tank. A tank is a tracked, Armoured fighting vehicle designed for Front-line combat which combines Operational mobility and tactical An important development was Gundlach's periscope allowing tank commander to obtain 360 degree view without moving the seats (pictured). Rudolf Gundlach (1894-1957 was a Polish engineer inventor and Tank designer The design was first used in the Polish 7-TP light tank. Polish Land Forces (Wojska Lądowe RP is a branch of Poland 's Armed Forces. The 7TP was the Polish Light tank of the Second World War. A development of the British Vickers 6-ton, it was significantly better armed Shortly before the war it was given to the British and was used in most tanks of WWII, including the British Crusader, Churchill, Valentine, and Cromwell and the American Sherman. The British Army is the land armed forces branch of the British Armed Forces. World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including One of the primary Cruiser tanks of the United Kingdom during World War II, the Tank Cruiser Mk VI Crusader (A15 was perhaps the most important British The Tank Infantry Mk IV (A22 was a heavy British Infantry tank used in the Second World War, best known for its heavy armour and its use as the The most numerous British manufactured tank of World War II, the Tank Infantry Mk III Valentine was known mainly for its low cost and high reliability The Tank Cruiser Mk VIII Cromwell (A27M, named after the English Civil War leader Oliver Cromwell, was one of the The United States Army is a military organization whose primary mission is to "provide necessary forces and capabilities. World War II foreign variants and use Lend-Lease Sherman tanks. The design was later copied and used extensively in tanks of the USSR (including the T-34 and T-70) and Germany. The Red Army ( Russian: Рабоче-Крестьянская Красная Армия R aboche- K rest'yanskaya K rasnaya A rmiya The T-34 was a Soviet medium tank produced from 1941 to 1958 It is widely regarded as having been the world's best Tank when the Soviet Union The T-70 light tank was used by the Red Army during World War II, replacing both the T-60 scout Tank Wehrmacht (literally "defense force" was the name of the unified Armed forces of Germany from 1935 to 1945

Australian light horseman using a periscope rifle, Gallipoli 1915

Periscopes proved useful in trench warfare, as seen in the illustrations, representative of action at Gallipoli. A periscope rifle was first invented by Sergeant William Beech a builders foreman of the 2nd Battalion NSW, Australian Imperial Force, in May 1915 Trench warfare is a form of warfare where both combatants have fortified positions and fighting lines are static Gallipoli peninsula (Gelibolu Yarımadası is located in Turkish Thrace, the European part of Turkey, with the Aegean Sea to the west and the Dardanelles

Naval use

Periscopes allow a submarine, submerged at a shallow depth, to search for targets and threats in the surrounding sea and air. When not in use, the periscope is retracted into the hull. A sub commander in tactical conditions must exercise discretion when using his periscope, since it creates an observable wake and may be detectable to radar, giving away the sub's position.

A simple, fixed naval periscope using mirrors was built by the Frenchman Marie Davey in 1854. Year 1854 ( MDCCCLIV) was a Common year starting on Sunday (link will display the full calendar of the Gregorian Calendar (or a Common year Thomas H. Doughty of the US Navy later invented a prismatic version for use in the American Civil War (1861-1865). Causes of the war See also Origins of the American Civil War, Timeline of events leading to the American Civil War The coexistence of a slave-owning South

The invention of the collapsible periscope for use in submarine warfare is usually credited to Simon Lake in 1902, who called his device the omniscope or skalomniscope. For the writer Simon Lake see the pseudonym of Charles L Grant. Year 1902 ( MCMII) was a Common year starting on Wednesday (link will display calendar of the Gregorian calendar (or a Common year starting There is also a report that an Italian, Triulzi, demonstrated such a device in 1901 calling it a cleptoscope. Year 1901 ( MCMI) was a Common year starting on Tuesday (link will display calendar of the Gregorian calendar (or a Common year starting

Another early example of naval use of the periscope are the two adapted on the experimental French submarine Gymnote by the Captain Arthur Krebs in 1888 and 1889 (see in French : rbmn). Arthur Constantin Krebs ( November 16, 1850 in Vesoul, France &ndash March 22 1935 in Quimperlé, Year 1888 ( MDCCCLXXXVIII) was a Leap year starting on Sunday (click on link for calendar of the Gregorian calendar (or a Year 1889 ( MDCCCLXXXIX) was a Common year starting on Tuesday (link will display the full calendar of the Gregorian calendar (or a Common

Search and destroy periscopes of a French-built Scorpène class submarine. Scorpène characteristics The Scorpène class of ships has three subtypes: the Basic Basic-AIP (with the MESMA Air-independent propulsion) and Compact

A modern submarine periscope incorporates lenses for magnification and functions as a telescope. A telescope is an instrument designed for the observation of remote objects and the collection of Electromagnetic radiation. It typically employs prisms and total internal reflection instead of mirrors, because prisms, which do not require coatings on the reflecting surface, are much more rugged than mirrors. In Optics, a prism is a transparent optical element with flat polished surfaces that refract Light. It may have additional optical capabilities such as range finding and targeting. A rangefinder is a device that measures distance from the observer to a target for the purposes of Surveying, determining focus in Photography, or The mechanical systems of submarine periscopes are typically hydraulically powered and need to be quite sturdy to withstand the drag through water. The periscope chassis may also be used to support a radio or radar antenna.

Submarines traditionally had two periscopes: a navigation or observation periscope and a targeting, or commander's, periscope. These were originally mounted in the conning tower, one forward of the other in the narrow hulls of diesel-electric submarines. In the much wider hulls of recent US Navy submarines, the two are located side-by-side. The observation scope was used to scan the sea surface and sky and 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, since sonar 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. Sonar (which started as an Acronym for sound navigation and ranging) is a technique that uses Sound propagation (usually underwater to navigate

However, the most modern submarines no longer use periscopes. The United States Navy's Virginia-class submarines instead use photonics masts, which lift an electronic imaging sensor set above the water. Innovations The Virginia s incorporate several innovations Instead of Periscopes the subs have a pair of extendable " Photonics masts quot outside 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 during construction Signals from the sensor set are transmitted electronically to workstations in the submarine's control center. While the cables carrying the signal must penetrate the submarine's hull, that hull opening is much smaller and more easily sealed—and therefore less expensive and safer—than those required by periscopes. Eliminating the telescoping tube running through the conning tower also allows greater freedom in designing the pressure hull and placing internal equipment.

See also

• Vickers Tank Periscope MK.IV

External links

• The Fleet Type Submarine Online: Submarine Periscope Manual United States Navy Navpers 16165, June 1946