We've retrofitted an old webcam to see the ifrared spectrum, via infrared diodes. The uses for this, aside from just seeing an alternate light source, include night vision.
First, gather the neccessary materials:
One (1) webcam w/ an IR filter. Most of the cheap ones have these.
One (1) chisel and/or flathead screwdriver.
One (1) philips screwdriver.
Step 1: Disassemble
Step 2: Remove the Infrared Filter
Step 3: Reassemble
Put the webcam back together, leaving the infrared filter out. Make sure to line up the lens so it's centered on the camera, otherwise it may not work as well.
Now, plug in the camera and use an infrared diode, or some other form of infrared light to check it's functionallity. To try night vision, use an infrared light in a dark room. You won't be able to see the light yourself, but the camera should pick it up and display it on screen.
Thanks for reading!