911signal Strobe light, Police lighting system

A strobe light or stroboscopic lamp, commonly called a strobe, is a device used to produce regular flashes of light.

A typical commercial strobe light has a flash energy in the region of 10 to 150 joules , and discharge times as short as a few milliseconds, often resulting in a flash power of several kilowatts .

The strobe light was popularized on the club scene during the 1960s when it was used to reproduce and enhance the effects of LSD trips. Ken Kesey used strobe lighting in coordination with the music of the Grateful Dead during his legendary Acid Tests.

Special calibrated strobe lights, capable of flashing up to hundreds of times per second, are used in industry to “stop” the motion of rotating and other repetitively-operating machinery and to measure, or adjust, the rotation speeds or cycle times.

Strobe lighting can trigger seizures in photosensitive epilepsy .

Since this stop is only apparent, a marked point on the rotating body will either appear to move backward or forward, or not move, depending on the frequency of the strobe-flash.