Searchlight
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- For other uses of searchlight see Searchlight (disambiguation).
A searchlight is an apparatus with reflectors for projecting a powerful beam of light of approximately parallel rays in a particular direction, usually devised so that it can be swiveled about.
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.
Searchlights were used extensively in defence 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 helped blind bombardiers using optical bombsights.
World War II searchlights include the General Electric 1942-A Searchlight. This was a 60" (152.4 cm) in diameter lamp producing 800,000,000 candela. It runs off a 15 KW generator and has an effective beam visibility of 28 to 35 miles (45 to 56 km). [link]
More recently, searchlights are often used in advertising, for instance by automobile dealers; the beam of light is visible over a large area, and (at least in theory) interested persons can find the dealer or store by following the beam to its source. This also used to be done for movie premieres; the waving searchlight beams are still to be seen as a design element in the logo of the 20th Century Fox movie studio.
Sources
- http://www.geocities.com/bobz299/searchlight.htm
- http://www.ftmac.org/SperryLight.htm
- http://www.peakbeam.com
See also
- Military applications of searchlight
- *Canal Defence Light
- *Leigh light
| L i g h t i n g and L a m p s | ||
|---|---|---|
| Incandescent: | Incandescent light bulb>Conventional - Halogen - Parabolic Aluminized Reflector (PAR) |
|
| Fluorescent: | Compact fluorescent lamp>Compact Fluorescent (CFL) - Linear fluorescent - Induction lamp | |
| Gas discharge: | High-intensity discharge lamp>High-Intensity Discharge (HID) - Mercury-vapor - Metal-halide - Neon - Sodium vapor | |
| Electric arc: | Arc lamp - Hydrargyrum medium-arc iodide>HMI - Xenon arc - Yablochkov candle | |
| Combustion: | Carbide lamp>Acetylene/Carbide - Candle - Gas lighting - Kerosene lamp - Limelight - Oil lamp - Safety lamp | |
| Other types: | Sulfur lamp - Light-emitting diode>Light-Emitting Diode (LED) - Optical fiber - Plasma | |
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