Searchlight
Encyclopedia
Curved mirror
A curved mirror is a mirror with a curved reflective surface, which may be either convex or concave . Most curved mirrors have surfaces that are shaped like part of a sphere, but other shapes are sometimes used in optical devices...
or other optics to project a powerful beam of light
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
of approximately parallel rays in a particular direction, usually constructed so that it can be swiveled about.
Military use
The Royal NavyRoyal 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...
used searchlights in 1882 to prevent Egyptian forces from manning artillery batteries at Alexandria
Alexandria
Alexandria is the second-largest city of Egypt, with a population of 4.1 million, extending about along the coast of the Mediterranean Sea in the north central part of the country; it is also the largest city lying directly on the Mediterranean coast. It is Egypt's largest seaport, serving...
. Later that same year, the French and British forces landed troops under searchlights.
By 1907 the value of searchlights had become widely recognized. One recent use was to assist attacks by torpedo boat
Torpedo boat
A torpedo boat is a relatively small and fast naval vessel designed to carry torpedoes into battle. The first designs rammed enemy ships with explosive spar torpedoes, and later designs launched self-propelled Whitehead torpedoes. They were created to counter battleships and other large, slow and...
s by dazzling gun crews on the ships being attacked. Other uses included detecting enemy ships at greater distances, as signaling devices, and to assist landing parties. Searchlights were also used by battleships and other capital vessels to locate attacking torpedo boats and were installed on many coastal artillery batteries for aiding night combat. They saw use in the Russo-Japanese War
Russo-Japanese War
The Russo-Japanese War was "the first great war of the 20th century." It grew out of rival imperial ambitions of the Russian Empire and Japanese Empire over Manchuria and Korea...
from 1904–05.
World War I
Searchlights were first used in World War IWorld 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 create "artificial moonlight" to enhance opportunities for night attacks, a practice which continued in 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...
. Artificial moonlight was invented by historian and tank warfare
Tank
A tank is a tracked, armoured fighting vehicle designed for front-line combat which combines operational mobility, tactical offensive, and defensive capabilities...
theorist, Gen. J.F.C. Fuller
J.F.C. Fuller
Major-General John Frederick Charles Fuller, CB, CBE, DSO was a British Army officer, military historian and strategist, notable as an early theorist of modern armoured warfare, including categorising principles of warfare...
. The term "artificial moonlight" was used to distinguish illumination provided by searchlights from that provided by normal moonlight, which was referred to as "movement light" in nighttime manoeuvers.
World War II
Searchlights were used extensively in defense against nighttime aerial bomberBomber
A bomber is a military aircraft designed to attack ground and sea targets, by dropping bombs on them, or – in recent years – by launching cruise missiles at them.-Classifications of bombers:...
raids around the time of 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...
. In particular, pairs of searchlights spaced a known distance apart were used to determine (via triangulation
Triangulation
In trigonometry and geometry, triangulation is the process of determining the location of a point by measuring angles to it from known points at either end of a fixed baseline, rather than measuring distances to the point directly...
) the altitude
Altitude
Altitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...
of enemy bombers, so that the fuses on anti-aircraft flak shells could be set appropriately for maximum effect. In addition, the lights may have blinded bombardiers using optical bombsight
Bombsight
A bombsight is a device used by bomber aircraft to accurately drop bombs. In order to do this, the bombsight has to estimate the path the bomb will take after release from the aircraft. The two primary forces during its fall are gravity and air drag, which makes the path of the bomb through the air...
s.
Searchlights were occasionally used tactically in ground battles. One famous occasion was the Soviets' use of seachlights during the Battle of Berlin
Battle of Berlin
The Battle of Berlin, designated the Berlin Strategic Offensive Operation by the Soviet Union, was the final major offensive of the European Theatre of World War II....
in April 1945. 143 searchlights were directed at the German defense force across the Neisse River with the aim of temporarily blinding them during a Soviet offensive. However, the morning fog diffused the light and silhouetted the attacking Soviet forces, making them clearly visible to the Germans. The Soviets suffered heavy losses as a result and were forced to delay their invasion of the city.
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...
-era searchlights include models manufactured by General Electric
General Electric
General Electric Company , or GE, is an American multinational conglomerate corporation incorporated in Schenectady, New York and headquartered in Fairfield, Connecticut, United States...
and by the Sperry Company
Sperry Corporation
Sperry Corporation was a major American equipment and electronics company whose existence spanned more than seven decades of the twentieth century...
(of gyroscope fame). These were mostly of 60" (152.4 cm) diameter with rhodium plated parabolic mirror, reflecting a carbon arc
Arc lamp
"Arc lamp" or "arc light" is the general term for a class of lamps that produce light by an electric arc . The lamp consists of two electrodes, first made from carbon but typically made today of tungsten, which are separated by a gas...
discharge. Peak output was 800,000,000 candela
Candela
The candela is the SI base unit of luminous intensity; that is, power emitted by a light source in a particular direction, weighted by the luminosity function . A common candle emits light with a luminous intensity of roughly one candela...
. It was powered by a 15 kW generator and had an effective beam visibility of 28 to 35 miles (45 to 56 km) in clear low humidity.
Non-military use
Advertising
Advertising is a form of communication used to persuade an audience to take some action with respect to products, ideas, or services. Most commonly, the desired result is to drive consumer behavior with respect to a commercial offering, although political and ideological advertising is also common...
, fairs, festivals and other public events. Their use was once common for movie
Film
A film, also called a movie or motion picture, is a series of still or moving images. It is produced by recording photographic images with cameras, or by creating images using animation techniques or visual effects...
premiere
Premiere
A premiere is generally "a first performance". This can refer to plays, films, television programs, operas, symphonies, ballets and so on. Premieres for theatrical, musical and other cultural presentations can become extravagant affairs, attracting large numbers of socialites and much media...
s; the waving searchlight beams can still be seen as a design element in the logo of the 20th Century Fox
20th Century Fox
Twentieth Century Fox Film Corporation — also known as 20th Century Fox, or simply 20th or Fox — is one of the six major American film studios...
movie studio
Movie studio
A movie studio is a term used to describe a major entertainment company or production company that has its own privately owned studio facility or facilities that are used to film movies...
, and Fox television network
Fox Broadcasting Company
Fox Broadcasting Company, commonly referred to as Fox Network or simply Fox , is an American commercial broadcasting television network owned by Fox Entertainment Group, part of Rupert Murdoch's News Corporation. Launched on October 9, 1986, Fox was the highest-rated broadcast network in the...
.
See also
- Mangin mirrorMangin mirrorIn optics, a Mangin mirror is a negative meniscus lens with the reflective surface on the rear side of the glass forming a curved mirror that reflects light without spherical aberration...
- Cathedral of lightCathedral of lightThe cathedral of light was a main aesthetic feature of the Nuremberg Rallies that consisted of 130 anti-aircraft searchlights, at intervals of 12 metres , aimed skyward to create a series of vertical bars surrounding the audience. The effect was a brilliant one, both from within the design and on...
- Tribute in LightTribute in LightThe Tribute in Light is an art installation of 88 searchlights placed next to the site of the World Trade Center to create two vertical columns of light in remembrance of the September 11 attacks. It is produced annually by The Municipal Art Society of New York...
- Military applications of searchlight
- Canal Defence LightCanal Defence LightCanal Defence Light was a British "secret weapon" of the Second World War.It was based upon the use of a powerful carbon-arc searchlight mounted on a tank. It was intended to be used during night-time attacks, when the light would allow enemy positions to be targeted...
- TurbinliteTurbinliteThe Helmore/GEC Turbinlite was a 2,700 million candela searchlight fitted in the nose of a number of British Douglas Havoc night fighters during the early part of the Second World War and around the time of The Blitz....
- Leigh lightLeigh lightThe Leigh Light was a British World War II era anti-submarine device used in the Second Battle of the Atlantic.It was a powerful carbon arc searchlight of 24 inches diameter fitted to a number of the British Royal Air Force's Coastal Command patrol bombers to help them spot surfaced...
- G-numbers
- Canal Defence Light
External links
- Sperry searchlight restoration project
- How Were World War II Searchlights Used? Information on a website commemorating the US 225th AAA Searchlight Battalion
- "Giant Lights Paint The Sky To Work New Magic" July Popular Mechanics -- ie early article on one of the first commercial use of searchlights.
- director restored http://www.ftmac.org/DEC_Project.htm