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Fog Screen

Rakkolainen For some time during the 1990s, Finnish researcher Ismo Rakkolainen’s living room was strewn with a pile of banana boxes and thousands of drinking straws. These materials comprised a laboratory of sorts as he worked on a prototype for what would become known as the fog screen. The device produces a magical illusion of giving a person the ability to walk through walls.

A senior researcher in the Technology Signal Processing Laboratory at Finland’s Tampere University of Technology, Rakkolainen worked with Professor Karri Palovuori to create the fog screen, a physically penetrable display made of dry fog that is flat, thin, and translucent. This is achieved mainly via a concept called laminar airflow, where streams of air move parallel to the flow axis and do not mix. The team wanted to create non-turbulent laminar air flow, which requires directing the flow slowly through small channels. Rakkolainen’s early prototypes used plastic drinking straws to achieve this, pushing air up through the small nozzles from below.

Rakkolainen’s screen uses dry fog, created by using dry ice or liquid nitrogen. This means the screen does not wet any person or thing that comes into contact with it. People can get the sensation of walking through a wall as an image is projected onto the screen, giving the effect of objects or surfaces floating on air. Images can be projected from the front or behind. Smoke or water can also be used to achieve a similar effect.

Possible applications are wide-ranging, from the whimsical to business and commercial uses. Some of these include projecting images in art exhibitions, in advertising, for gaming applications, in theater productions, at trade fairs and other special events, in hotel lobbies and museums, and in theme parks. The screens make possible the prospect of virtual rooms and complete virtual spaces.

The fog screen was first demonstrated at the Turku Science Exhibition in Turku, Finland in the fall of 2002. Since then it has been featured in many international journals, magazines, and news reports and was also shown at the 2003 SIGGRAPH Emerging Technologies conference in San Diego and other events around the world. International patents are pending. In January, 2003, a prototype was also installed in the Vapriikki museum in Tampere.

FogScreen Inc. was founded in 2003 to develop, manufacture and market products based on the technology. Rakkolainen serves as the company’s Research and Development Director. The privately held company is headquartered in the Seinäjoki Technology Center, Finland, and clients can purchase various versions of the screens, with optional enhanced features. One of these is an interactivity add-on that allows the FogScreen to act as an immaterial “touch screen.” This could potentially be used in shopping malls, for interactive exhibits at museums and arts events, even in hospitals. This property will be especially utilized in applications operated by the public or in hospitals, in advertising, in malls for presenting shops and products, in art productions and events, and as interactive exhibits in museums.

Meanwhile, Rakkolainen continues to conduct research at the Tampere University of Technology. Last year, he won first prize in the National Innovation Contest of the Finnish New Technology Foundation.

[July 2004]

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