An infrared, or IR, bullet camera is a special type of camera that is used in security and surveillance. Security cameras come in one of three common body shapes, a box, a dome, and a bullet. IR cameras use light emitting diodes (LEDs) to illuminate an area with infrared light, allowing the camera to function in darkness. An IR bullet camera combines the features of the bullet camera and the IR camera onto one unit that is able to function in both light and darkness.
Though not as popular as box or dome cameras, bullet cameras are one of the most commonly used types of security cameras. They are cylindrical in shape and come in many sizes, from tiny, concealable devices an inch or so long to larger units designed to be mounted on walls. Most of the time, an IR bullet camera is a medium-sized device that is mounted onto a wall with a positionable arm. This allows the camera to be pointed exactly in the desired direction.
The cylindrical shape of an IR bullet camera is optimal for the addition of infrared LEDs. These diodes are placed in a circle around the lens of the camera. The quality of an IR bullet camera is largely determined by the number and strength of the LEDs around the camera's lens because a camera with more and more powerful LEDs will be able to see further in low or no light.
The mechanism that allows an IR bullet camera to function in the dark is relatively simple. The LEDs emit infrared light, which is light at a wavelength that is too long to be seen by the human eye. The lens of the camera, however, is able to detect the light of this wavelength. These cameras use the LEDs to produce a spotlight of invisible light, illuminating an the area in front of the camera at a maximum distance of up a few hundred feet (about 100 meters).
Many times, an IR bullet camera is designed to function in both light and darkness. In the light, the camera may take color or black and white video and uses the light in the visual spectrum. A sensor built into the camera will activate the infrared element when the ambient light becomes low enough, and the infrared LEDs will turn on. The camera will then take video in black and white, utilizing the infrared wavelengths.