Quote Originally Posted by pete View Post
If you've any old digital cameras /webcams lying around that have been superseded, remove the IR filter and donate them + bottle of coke/opaque beverage to the physics dept as demo kit.
Works even better if you put a visible light filter in place of the IR filter, you then get an IR only webcam. You can make a visible light filter from the magnetic surface of a floppy disc believe it or not, as that lets IR light through but blocks visible light. Another common visible light filter is a fully exposed piece of colour film (that's been developed) which to our eyes will look opaque, but that also lets IR light through. I made an IR webcam by doing this and amazed people with the seeing through coke trick. It will also make an LCD monitor with an image on appear completely black from certain angles, will see through some clothes or dramatically change the colour of them (black t-shirts look much paler for instance) and a few other interesting things.