Drive-through movies

A fog screen raises the possibility of moving image projections that appear to hang in mid-air.

Moving images and advertisements that appear to hang in mid-air will be made possible using a novel display technology that creates screens from nothing but thin air and fog.

The device, developed at Tampere University of Technology in Finland, can be used to display both still and film images.

The technology consists of a non-turbulent flow of air, into which fog droplets are injected, said Ismo Rakkolainen, senior researcher at the university.

The fog screen could be used to project images in art exhibitions, theatre productions, museum displays, and in amusement parks, said Rakkolainen, who developed the technology with his colleague in the university’s signal processing laboratory, Karri Palovuori.

The device could also lead to walk-through advertising displays within shopping centres, he said. ‘It allows people to play with the advertisement, which no other technology allows you to do. This should make adverts much more memorable.’

The laminar airflow is produced by blowing air slowly through a system of thin pipes, which removes any turbulence. The fog is then produced by applying an ultrasound device to water, creating tiny droplets that are then injected into the airflow through nozzles. ‘Because the air flow is laminar the fog screen stays flat and can be used to display images.’

A vacuum system could be added to the device to reduce humidity, but moisture is not a serious problem, said Rakkolainen. Even without a vacuum the device could simply be switched off without producing a puddle of water on the floor. ‘Fog does not contain much water, and the device only produces as much moisture as 20 people breathing. When you touch it you do not feel any humidity, you feel nothing at all, except perhaps a slight flow of air.’

The fog screen is not poisonous, allowing it to be used safely for computer games, combat exercise or training, and non-supervised public presentations. Light, mobile screens, table displays or even virtual rooms could be created using the technology.

The research team also hopes to produce cylindrical-shaped screens, and even 3D shapes, by developing a computer-controlled fog injection nozzle.

The researchers have built a prototype device, and are hoping to develop the technology further by improving the quality of the display at larger sizes. The width of the screen can be anything up to 10m without damaging its quality, but at present the height is limited to around 1m.

‘Our biggest technical enemy is turbulence: trying to produce larger flows of air that remain laminar is a difficult task,’ said Rakkolainen.

The team is hoping to increase the height of the screen to at least 2m, to make possible the creation of life-sized penetrable displays, he said. The university has already been contacted by a number of companies interested in commercialising the technology, while an advanced prototype of the screen will go on display next January at the Communications Museum in Tampere.

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