An infrared illuminator, or IR illuminator, is a tool that emits light in the infrared spectrum. Infrared light, or infrared radiation, has wavelengths longer than visible light and is usually experienced as heat. Infrared radiation is invisible to the human eye, but to night vision devices, an IR illuminator functions like a flashlight.
All night vision devices require at least a small amount of ambient or infrared light to work. Many Gen 2 and Gen 3 devices can make use of very faint moonlight or starlight, but in situations with absolutely no visible light, even the most advanced night vision requires an IR illuminator to function. (For more information about the different generations of night vision, check out our article explaining the difference between Gen 2 and Gen 3.)
Types of IR Illuminators
IR illuminators can be integral (built into the night vision device), attachable, or handheld. Gen 1 devices usually have integral IR lights built in, and integral illuminators are also common in monoculars and goggles designed for walking and traveling at night, like the FLIR MNVD-51.
Night vision devices without an integral illuminator are usually designed with space for an attachable illuminator, which functions independently from the device and includes its own battery. FLIR night vision riflescopes often include detachable IR illuminators.
Handheld IR illuminators are basically night vision flashlights. These units generally have a bigger set of batteries, giving them a longer life and often an overall longer effective range than attachable units.
In addition, night vision devices or firearms may be equipped with IR laser systems, which fire a concentrated beam of IR light and create a small dot. These systems can be carried or mounted to firearms, and are commonly used for aiming at targets or communicating with others using night vision.
Pros and Cons of IR Illuminators
Infrared light is invisible to the human eye, but using an IR illuminator does make the user visible to others with night vision. For this reason, IR illuminators are not preferred for covert or military operations, though may be necessary for navigating and sighting targets in extreme darkness. Other cons of IR illuminators include added weight and additional battery requirements.
The clear advantages of IR illuminators are that they allow night vision to function with no visible light on the scene and are a relatively inexpensive way to drastically improve the sensitivity of a device. For many use-cases, IR illuminators are an integral tool to include when heading out for the night.