Editing Periscope (section)

==Armored vehicle periscopes==
[[Tank]]s and armoured vehicles use periscopes: they enable drivers, tank commanders, and other vehicle occupants to inspect their situation through the vehicle roof.  Prior to periscopes, direct vision slits were cut in the armour for occupants to see out.  Periscopes permit view outside of the vehicle without needing to cut these weaker vision openings in the front and side armour, better protecting the vehicle and occupants.

A protectoscope is a related periscopic vision device designed to provide a window in armoured plate, similar to a direct vision slit.  A compact periscope inside the protectoscope allows the vision slit to be blanked off with spaced armoured plate.  This prevents a potential ingress point for small arms fire, with only a small difference in vision height, but still requires the armour to be cut.

In the context of [[armoured fighting vehicle]]s, such as [[tank]]s, a periscopic vision device may also be referred to as an '''episcope'''.  In this context a periscope refers to a device that can rotate to provide a wider field of view (or is fixed into an assembly that can), while an episcope is fixed into position.

Periscopes may also be referred to by slang, e.g. "shufti-scope".<ref>{{cite book|last=Partridge|first=Eric|title=A Dictionary of Slang and Unconventional English|url=https://books.google.com/books?id=IAjyQdFwh4UC&pg=PA1065|date=2006|publisher=Routledge|isbn=978-1-134-96365-2|pages=1065–}}</ref>

===Gundlach and Vickers 360-degree periscopes===
An important development, the [[Rudolf Gundlach|Gundlach rotary periscope]], incorporated a rotating top with a selectable additional prism which reversed the view.  This allowed a tank commander to obtain a 360-degree field of view without moving his seat, including rear vision by engaging the extra prism.  This design, patented by [[Rudolf Gundlach]] in 1936, first saw use in the [[Polish Army|Polish]] [[7-TP]] light tank (produced from 1935 to 1939).

As a part of Polish–British pre-[[World War II]] military cooperation, the patent was sold to Vickers-Armstrong where it saw further development for use in [[British Army|British]] tanks, including the [[Crusader tank|Crusader]], [[Churchill tank|Churchill]], [[Valentine tank|Valentine]], and ''[[Cromwell tank|Cromwell]]'' models as the [[Vickers Tank Periscope MK.IV]].

The Gundlach-Vickers technology was shared with the [[United States Army|American Army]] for use in its tanks including the [[M4 Sherman|Sherman]], built to meet joint British and US requirements. This saw post-war controversy through legal action: "After the Second World War and a long court battle, in 1947 he, Rudolf Gundlach, received a large payment for his periscope patent from some of its producers."<ref name=r1/>

The [[Red Army|USSR]] also copied the design and used it extensively in its tanks, including the [[T-34]] and [[T-70]].  The copies were based on Lend-Lease British vehicles, and many parts remain interchangeable.  [[Wehrmacht|Germany]] also made and used copies.<ref name=r1>Łukomski, Grzegorz and Stolarski, Rafał E. (1999) ''Nie tylko Enigma... Mjr Rudolf Gundlach (1892–1957) i jego wynalazek'' (Not Only Enigma... Major Rudolf Gundlach (1892–1957) and His Invention), Warsaw-London.</ref>

===Periscopic gunsights===
Periscopic [[Sight (device)|sights]] were also introduced during the Second World War. In British use, the Vickers periscope was provided with sighting lines, enabling front and rear prisms to be directly aligned to gain an accurate direction.  On later tanks such as the Churchill and Cromwell, a similarly marked episcope provided a backup sighting mechanism aligned with a vane sight on the turret roof.

Later, US-built Sherman tanks and British [[Centurion tank|Centurion]] and [[Charioteer tank|Charioteer]] tanks replaced the main telescopic sight with a true periscopic sight in the primary role. The periscopic sight was linked to the gun itself, allowing elevation to be captured (rotation being fixed as part of rotating turret). The sights formed part of the overall periscope, providing the gunner with greater overall vision than previously possible with the telescopic sight. The [[Chieftain (tank)|FV4201 Chieftain]] used the TESS (Telescopic Sighting System) developed in the early 1980s that was later sold as surplus for use on the [[McDonnell Douglas Phantom in UK service|RAF Phantom]] aircraft.<ref>{{cite web | url=https://www.david-gledhill.co.uk/the-phantom/tess/ | title=TESS :: David Gledhill }}</ref><ref>{{cite web | url=https://bpag.co.uk/the-day-of-the-j/ | title=The Way of the J. – British Phantom Aviation Group }}</ref>

===Modern specialised AFV periscopes===
In modern use, specialised periscopes can also provide night vision.  The Embedded Image Periscope (EIP) designed and patented by Kent Periscopes provides standard unity vision periscope functionality for normal daytime viewing of the vehicle surroundings plus the ability to display digital images from a range of on-vehicle sensors and cameras (including thermal and low light) such that the resulting image appears "embedded" internally within the unit and projected at a comfortable viewing position.