An infrared illuminator is a device that works by emitting light in an infrared spectrum or reflecting the light which falls on it. The human eye cannot see IR light, but it is reflected by objects around the user and can be detected by night vision optics. IR lights are used as additional light sources and are especially useful for operation in places where the level of natural light is extremely low, as well as for pointing or marking of the target.

Infrared lights for night vision can be divided into three major groups:

1. IR LED – the most popular type of IR lights for night vision. These devices produce IR light that can be detected only by night vision units. These are the safest type of IR lights.
2. Lasers – units that work on the amplification of light, stimulated by generated photons.  As they stimulate emission of radiation, they are not the safest option.
3. Filtered lamps- units that consist of an incandescent lamp and an infrared filter. Such filters block all parts of the spectrum except infrared.