Effects of Strobe Lighting
The history of the strobe light begins with a photographer named Harold Eugene Edgerton, who used a flashing lamp to study moving objects. The techniques eventually improved enough to let him take photographs of bullets in flight. During World War II the technique was used to photograph atomic explosions. Strobe lights have had a number of applications outside of photography. Their effects are found in theaters, alarm systems, emergency vehicles, signaling devices, and night clubs and concerts. There is some danger in staring directly at strobe effects. A condition in which strobe flashes can cause seizures is known as photosensitive epilepsy.
Stroboscope
A stroboscope is a type of light or bulb that flashes. The system works by having a gas like xenon or krypton in a bulb, and an electronic discharge that sends several hundred volts through the bulb. The power required can be achieved through an oscillator circuit. In older cameras, the high pitched whining sound was due to the capacitor charging before releasing the proper voltage.
Alarm Systems
Strobe lights are often coupled with loud audible devices for use in alarm systems, especially for large buildings. Tornado and fire alarm systems may have strobe lights in halls, above exit doors or in stairwells. The noises produced by alarm systems are to alert bystanders aurally, while the strobe flashes can do so visually. The strobe flashes are also powerful enough to guide bystanders through smoke.
Theatrics
Strobe lights are used in theater to create various effects like lightning, flashes or pulses. During performances or plays, the lights are often set up to face the performers and are usually hidden from the audience. Sometimes strobe lights can be used as backlighting, positioned behind performers to give them a slow motion silhouette effect. Strobe lights work best in low light when they don't compete with other light sources.
Signaling Applications
Strobe lights are often used for emergency purposes on law enforcement vehicles, fire trucks and ambulances. The distinct colors help identify the type of emergency occurring. The lights are also used on construction equipment, large moving trucks and aircraft. Strobe lights are also effective in conditions with low visibility, such as fog, smoke screens and even underwater.
Photosensitive Epilepsy
Photosensitive epilepsy is a condition in which seizures are caused by rapid pulses, flashes, patterns and other visual stimuli. The flashing of strobe lights has been found to cause these attacks in some cases. Some forms of seizure include jerks by the epileptic timed with the flashes of stroboscopic lights, or clinical seizures as a result of exposure to the lights. Stroboscopic lights are sometimes used in testing for reflex epilepsy, to check if light exposure is a factor in a patient's epilepsy.
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