I've seen small credit card sized IR detectors for TV Technicians. A small area glows when an IR diode from a remote control is turned on and placed in close proximity. These are used to test the output of the infrared diode.
You can also aim the remote control towards the lens of a small, cheap digital camera with a live LED pixel dispay. In many cases, the camera sees and detects what the human eye cannot.
Does anyone know what minerals or substances glow with visible light when subject to low level Infrared Light radiation?
Beachcomber