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The Vortek water-wall plasma arc lamp, invented in 1975 by David Camm and Roy Nodwell at the University of British Columbia, Vancouver, Canada, made the Guinness Book of World Records in 1986 and 1993 as the most powerful continuously burning light source at over 300 kW or 1.2 million candle power. [4]
ATS officers-in-training crew a 90 cm searchlight in Western Command, 1944. A searchlight (or spotlight) is an apparatus that combines an extremely bright source (traditionally a carbon arc lamp) with a mirrored parabolic reflector to project a powerful beam of light of approximately parallel rays in a particular direction.
In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human eye. The SI unit of luminous intensity is the candela (cd), an SI base unit.
The tank's normal turret was replaced with a cylindrical one containing both a 13 million candlepower (12.8 million candela) searchlight and a machine gun. [1] The searchlight turret included a station for an operator, who had the task of changing the light's carbon electrodes when they burned out. [1]
Candlepower (abbreviated as cp or CP) is a unit of measurement for luminous intensity. It expresses levels of light intensity relative to the light emitted by a candle of specific size and constituents. The historical candlepower is equal to 0.981 candelas. In modern usage, candlepower is sometimes used as a synonym for candela. [1]
Developed in the late 1930s, the Flakscheinwerfer (Flak Searchlight) 34 and 37 used 150-centimetre (59 in) diameter parabolic glass reflectors with an output of 990 million candelas. The system was powered by a 24-kilowatt generator, based around a 51-horsepower (38 kW) 8-cylinder engine, giving a current of 200 amperes at 110 volts. [ 1 ]
The light output of an incandescent lamp in a flashlight varies widely depending on the type of lamp. A miniature keychain lamp produces one or two lumens. A two-D-cell flashlight using a common prefocus-style miniature lamp produces on the order of 15 to 20 lumens of light [11] and a beam of about 200 candlepower.
Luminous efficacy can be normalized by the maximum possible luminous efficacy to a dimensionless quantity called luminous efficiency.The distinction between efficacy and efficiency is not always carefully maintained in published sources, so it is not uncommon to see "efficiencies" expressed in lumens per watt, or "efficacies" expressed as a percentage.