An infrared light emitting diode (IR LED) is a device that creates light with a wavelength just slightly longer than what the human eye can see. These devices emit light in the near infrared range, meaning that they produce light that is closer to the visible light spectrum than microwaves, which are the next longest wavelength. An IR LED light functions in a similar way to an LED light that produces visible light, though it often has different power requirements. These devices are commonly used in electronics and security systems.
An IR LED light is made up of two sections of semiconductor material, a positively charged section and and a negatively charged section. When the LED light is powered off, the area in-between these two sections becomes a neutral depletion zone that does not allow current to pass from one side to the other. With the addition of an electrical charge, electrons on the negative side are able to jump to the positive side, a process that allows the electrons to release a certain amount of energy and emit a photon. The distance that the electrons jump dictates the wavelength of the photon they release. In an IR LED light, the device is designed to allow the electrons to only jump across a limited distance that corresponds to the range of acceptable infrared wavelengths.
One of the most common uses for an IR LED light is in a security system. Though infrared light is beyond the range of light visible to the human eye, a camera’s is able to detect infrared light that is just below the visible spectrum. This means that infrared light can be used to illuminate an area at night so that a camera can see clearly and continue to videotape the area, though the light will be invisible to humans in the area. Security cameras designed to function at night will often have an IR LED array mounted around the lens to light up the area being filmed.