Leave it to the Finns. Just when you thought there wasn’t anything else you could do with ice, here comes a use right out of Harry Potter: a multi-touch ice screen.

Mobile giant Nokia decided that – since Finland has a tradition of ice sculpuring anyway – why not make an interactive touch ice wall. Really, why not?

Built out of a slab of 25cm ice weighing a ton, and then cut into 50cm to build the 2 meter by 1.5 meter wall. Nokia then polished the surface with a heat gun to give it a smooth surface. The wall uses rear-diffused illumination (the same tech used by the Microsoft Surface) which is basically a smart projection, instead of embedding sensors. According to New Scientist which first reported the ice wall:

A near-infrared light source mounted behind the “screen” bathes it in invisible light, and an array of near-infrared cameras, also behind the wall, are focused on the front surface. A hand placed on the ice reflects the light towards the camera array and the signal each camera receives helps a nearby PC establish the hand’s position, size and motion. The PC is also connected to a projector, which uses the data to project imagery – such as flames – beneath the user’s hand.

Of course, one of Nokia’s first suggestions for using this new tech is for the famous Ice Hotel in Sweden – now that would be something.