Video of IR sender taken with basic mobile phone digital camera.
Today needed to check if a TV remote control had stopped working or if it was the actual ir receiver on the TV that was at fault. (Didn't want to buy a replacement remote only to find that was not the problem).
After a bit of research it turns out that most digital cameras can "see infra red".
So pointed the ir remote at a mobile phone camera and checked the camera display. Sure enough the ir emitter could be seen to be flashing, appearing to flash with a white light.
Hence fault traced to TV ir receiver.