Asearchlight (orspotlight) is an apparatus that combines an extremelybright source (traditionally acarbon arc lamp) with a mirroredparabolic reflector to project a powerful beam oflight of approximately parallel rays in a particular direction. It is usually constructed so that it can be swiveled about. The most common element used in modern searchlights isXenon (Xe).[1] However,Rare-earth elements such aslanthanum (La) andcerium (Ce) are used inphosphors to improve light quality in some specialized searchlights.[2]
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The first use of searchlights using carbon arc technology occurred during theSiege of Paris during theFranco-Prussian War.[3] TheRoyal Navy used searchlights in 1882 to dazzle and prevent Egyptian forces from manning artillery batteries atAlexandria. Later that same year, the French and British forces landed troops under searchlights.[4]
By 1907 the value of searchlights had become widely recognized. One recent use was to assist attacks bytorpedo boats 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 theRusso-Japanese War from 1904–05.[5]
Searchlights were installed on most navalcapital ships from the late 19th century throughWWII, both for tracking small, close-in targets such astorpedo boats, and for engaging enemy units in nighttime gun battles. TheImperial Japanese Navy especially was known for its intensive development of nighttimenaval combat tactics and extensive training. TheWar in the Pacific saw a number of nocturnal engagements fought by searchlight, particularly theBattle of Savo Sound at Guadalcanal. Although searchlights remained in use throughout the war, the newly developedradar proved to be a far more effective locating device, and Japanese radar development lagged far behind that of the US.
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Searchlights were first used in theFirst World War to create "artificial moonlight" to enhance opportunities for night attacks by reflecting searchlight beams off the bottoms of clouds, a practice which continued in theSecond World War. The term "artificial moonlight" was used to distinguish illumination provided by searchlights from that provided by natural moonlight, which was referred to as "movement light" in night-time manoeuvers.[6] Searchlights were also heavily used in the defense of the UK againstGerman nighttime bombing raids usingZeppelins.
Searchlights were used extensively in defense against nighttimebomber raids during theSecond World War. Controlled by sound locators and radars, searchlights could track bombers, indicating targets to anti-aircraft guns and night fighters and dazzling crews.
Searchlights were occasionally used tactically in ground battles. One notable occasion was theRed Army use of searchlights during theBattle of the Seelow Heights in April 1945. 143 searchlights were directed at the German defence force, with the aim of temporarily blinding them during a Soviet offensive, begun with the largest artillery bombardment the world had ever seen until that point. 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.[7]
Second World War-era searchlights include models manufactured byGeneral Electric and by theSperry Company. These were mostly of 60 inch (152.4 cm) diameter withrhodium plated parabolic mirror, reflecting acarbon arc discharge. Peak output was 800,000,000candela. 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.
The searchlight also found a niche for use bynight fighters andanti-submarine warfare aircraft. TheTurbinlite was a powerful searchlight mounted in the nose of anRAFDouglas Bostonlight bomber, converted into a night fighter to shoot downLuftwaffe nightbombers. The aircraft would be directed in the general direction of the enemy by ground-based ormetre-wave airborne radar, and the pilot would then switch on the Turbinlite, illuminating the enemy aircraft, which would then be shot down by accompanying RAFday fighters such as theHawker Hurricane. This never proved very successful, as the light made the emitting aircraft a very big target for rear gunners, who would simply have to shoot into the light and be guaranteed to hit something eventually.
During theBattle of the North Atlantic, RAF aircraft such as theVickers Wellington were assigned to patrol for surfaced GermanU-boats at night, when they would be on the surface, charging theirbatteries. A large searchlight called aLeigh light was suspended from the bottom of thewing orfuselage, and would be used to illuminate the surfaced U-boat while it was being attacked withbombs anddepth charges. The Leigh light was somewhat more successful than the Turbinlite, but in both cases the development of centimeter-wave radar proved to be the far more effective answer.
During the2022 Russian invasion of Ukraine a searchlight has been used foranti-aircraft warfare.[8]
Today, searchlights are used inadvertising,fairs,festivals and other public events. Their use was once common formoviepremieres; the waving searchlight beams can still be seen as a design element in the logos of20th Century Studios and theFox television network. The world's most powerful searchlight today beams from the top of the pyramid-shapedLuxor Hotel inLas Vegas. It concentrates about 13,650,000lumens from 39 7kWxenon lamps into a beam of about 9,129,000,000candela.
Tribute in Light is an art installation that uses two columns of searchlights to represent the formerTwin Towers of the World Trade Center, in remembrance of theSeptember 11 attacks. It is produced annually inLower Manhattan.
Disney parks uses searchlights in their nighttime fireworks displays. They are installed on top of the rooftops of several attractions inFantasyland.
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