How did searchlights evolve

Update:21 Sep 2020
Summary:

The searchlight is a device with powerful light source […]

The searchlight is a device with powerful light source and concave mirror which can focus the light on a specific direction. Considering the volume, weight and convenient operation of the device, most of the searchlights are equipped with tripods or movable vehicles, and large searchlights even have special trucks as vehicles. With the help of a mirror or lens, the outgoing beam is concentrated in a small solid angle, so as to obtain a lamp with larger light intensity.
According to the International Commission on illumination, a searchlight is a projection lamp whose half peak angle (the angle between the maximum intensity and 50% of the maximum intensity on a plane passing through the maximum intensity) is less than 2 °. Around 1870, the searchlights with carbon arc lamp as light source appeared in the world. During World War II, searchlights were mainly used at night to search for targets for anti-aircraft guns.

Modern searchlights are mainly used for navigation (such as marine searchlights) and signal signs. The types of searchlights are classified according to their light sources. In the past, they usually use tungsten halide lamps as light sources, as well as ultra-high pressure mercury lamps, metal halide lamps, ultra-high pressure xenon lamps and LEDs. At present, the main and recent light source is led.
According to the structure design, it can be divided into portable searchlight, portable searchlight, remote control searchlight, mobile searchlight and fixed searchlight. There are explosion-proof searchlights and non explosion-proof searchlights according to their functions.
Searchlight development history in the 19th century, searchlights began to be used in military aspects. During the Japanese Russian war, Navy warships of both sides used searchlights to search for enemy small torpedo boats at night. Searchlights are also common in coastal artillery positions and air defense forces. In World War I, Gen. j.f.c. fuller first used searchlights to create so-called "artificial Moonlight" to assist in night combat, and the same tactic was used in World War II. During the Second World War, searchlights were widely used to fight against the enemy's night air raids. At that time, the antiaircraft artillery used two searchlights at the same time. From the elevation angle of the searchlights, the exact height of enemy bombers can be calculated by trigonometric function, and then used to set the anti-aircraft shell information tube to achieve the maximum effect.
The searchlight can also cause considerable interference to the bombers using the optical bomb sight. During the Second World War, the searchlights made by ge used gyro ritual lamp holder, 152.4 cm diameter rhodium plated disk concave mirror, carbon arc light source with peak output of 800 million light, and special 15 kW generator, with effective range of 45-56 km. Due to the development of electronic monitoring equipment technology, the military use of searchlights is decreasing. Later, most of them were used for advertising, such as the promotion activities of car dealers and the premiere of films. Today's searchlights are also used in industry, mainly in power, metallurgy, oil field, petrochemical, public security, fire protection, military, railway and other industries, as well as large factories and sports grounds.

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