FLIR

FLIR (Forward looking infrared) cameras, typically used on military and civilian aircraft and sometimes on rifle sight, use an imaging technology that senses infrared radiation

The sensors installed in forward-looking infrared cameras—as well as those of other thermal imaging cameras—use detection of infrared radiation, typically emitted from a heat source (thermal radiation), to create a "picture" assembled for video output. They can be used to help pilots and drivers steer their vehicles at night and in fog, or to detect warm objects against a cooler background.

Battlefield 4
The FLIR is set to appear in Battlefield 4