A searchlight (or spotlight) is an apparatus that combines a bright light source with some form of curved reflector or other optics to project a powerful beam of light of approximately parallel rays in a particular direction, usually constructed so that it can be swiveled about.
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The Royal Navy used searchlights in 1882 to prevent Egyptian forces from manning artillery batteries at Alexandria. Later that same year, the French and British forces landed troops under searchlights.[1]
By 1907 the value of searchlights had become widely recognized. One recent use was to assist attacks by torpedo 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 the Russo-Japanese War from 1904–05.[2]
Searchlights were first used in World War I to create "artificial moonlight" to enhance opportunities for night attacks, a practice which continued in World War II. Artificial moonlight was invented by historian and tank warfare theorist, Gen. J.F.C. Fuller. 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.[3]
Searchlights were used extensively in defense against nighttime aerial bomber raids around the time of World War II. In particular, pairs of searchlights spaced a known distance apart were used to determine (via triangulation) the altitude 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 bombsights.
Searchlights were occasionally used tactically in ground battles. One famous occasion was the Soviets' use of seachlights during the Battle of Berlin 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-era searchlights include models manufactured by General Electric and by the Sperry Company (of gyroscope fame). These were mostly of 60" (152.4 cm) diameter with rhodium plated parabolic mirror, reflecting a carbon arc discharge. Peak output was 800,000,000 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.
Today, searchlights are used in advertising, fairs, festivals and other public events. Their use was once common for movie premieres; the waving searchlight beams can still be seen as a design element in the logo of the 20th Century Fox movie studio, and Fox television network.
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