After removing this filter, I reassembled the webcam and went to the park just by the geography department. Here I took a 'Full Spectrum' image (left below) and one with a visible light filter (in one specific wavelength - right below). I am sure you can agree the results are very cool! There are a number of things you can use for cheap visible light filters, you may even have one of them lying around the house or in a dusty cupboard somewhere. A very simple option is to use a black bin liner or an exposed camera negative which is as dark as possible.
Why not try it yourself, it is very easy to do and takes no time at all. There are many applications of this sort of photography including night vision (generally using a separate infrared light source), looking at absorption of greenhouse gases and general coolness!