Exposure Laboratory RWTH University Medical Centre Aachen, Germany

Transmission of electricity through high-voltage power lines inevitably generates electric and magnetic fields. Owing to the ever-increasing demand for electrical energy, large amounts of electricity from offshore wind farms are being transmitted through the densely populated areas of central and south Germany.

To determine if these electrical and magnetic fields pose a danger to people's health and wellbeing, an innovative experimental set-up is being used at the Exposure Laboratory of the Research Centre for Bioelectromagnetic Interaction at the RWTH Aachen medical centre in Germany, run by Dominik Stunder.

"The Exposure Laboratory is a key element of our experiments," says Stunder. "Selected according to their age, gender and other characteristics, we bring test subjects to this experimental space, expose them to a precisely defined electrical field and observe their reaction. To be specific, we apply a voltage of approximately 200,000 volts to a metal grid positioned above the test subjects and then ask them if they notice anything, and if so, what?"

It is difficult to communicate with the test subjects during the experiment because the strong electrical characteristics required mean that nothing electrical can be operated in the space. That's why the decision was made to project the questions for the test subjects onto the front wall of the space from outside using a projector. Test subjects can then use a number of buttons, which operate optically, to answer the questions.
The design of the projection brought with it several unusual challenges. Space limitations inside the laboratory meant a powerful wide-angle lens had to be used to allow a large enough image to be projected, despite close proximity to a wall. It was not possible to cover the wall with a layer of white paint that would aid projection, because the wall itself had to comply with strict electrical conditions.

The laboratory required a distortion-free projector that would be capable of producing a large image at a distance of less than one metre in a well-lit environment, with text that could be easily read on grainy, dark wood. After extensively testing various possible solutions, the centre chose an Epson EB-G7900 projector with an 180-degree adjustable ELPX01 lens. The projector itself was installed beneath the insulated laboratory floor, so that the lens projected the image through a very small hole.

"For a lot of suppliers, our requirements initially sounded relatively simple," continues Stunder. "But when it came to the actual implementation, many solutions simply did not work. Either they were not bright enough, or the image was too small or distorted. This solution was found as a result of close cooperation between Epson and our IT partners Keller-Büromaschinen."