Infrared Cameras and FLIR cameras
Infrared illuminated cameras use LED's to illuminate an area directly opposite of the camera. Infrared LED's are not visible by the human eye and they will not illuminate anything visible. The camera is able to use this lighta nd display an image on a monitor.
FLIR or forward looking infrared converts radiant energy from a surface into a thermal map or thermogram where color hues or gray shades correlate to a temperature distribution on that area.