Digital camera's are infrared sensitive. Far to sensitive: that's why there is a filter that blocks most of the infrared. Not all of it: look with your camera at the led of a tv remote. Push a button! You'll see a white dot where the led of the remote is. That means that all three sensors (R, G, and B) are equally sensitive to infrared light.
If you remove the filter from the camera it wil not be useable in the 'normal' manner anymore. The filter is the pinkish piece of glass, just behind the lens. Possibly the autofocus does not work anymore if the filter is removed, a 'neutral' piece of glass with the same refraction should replace the filter.
The camera gets better if you mount a filter that blocks everything except infrared, you get black and white images. Such a filter can be cut from a black piece of an old negative film.
It's more fun to make night foto's using an infrared lightsource. I made one using 25 led's. I use a Logitech webcam. Fixed focus, meaning that the lens is adjusted in the factory. Using some force you can re-adjust it after removing the filter. Now some software to detect motion. Look here for the result.