MEMS based lighting control optimises road illumination

April 29, 2015 // By Christoph Hammerschmidt
On the basis of its laser spot high-beam headlight, Audi is developing a system that automatically adjusts the illumination by the speed of the vehicle. The new technology utilises only a single MEMS mirror to deflect the laser beam.

The laser spot technology for the high beam went into series production for the first time in 2014, in the Audi R8 LMX sports car. Progress in the field of laser light generation now made it possible to integrate the projector technology in a compact yet powerful headlight assembly. The latest iteration uses a single but fast-moving micro mirror that deflects the laser beam. At low speeds, the light is distributed widely across a large area. At higher speed, the aperture angle gets smaller; the intensity as well as the luminous range of the beam is increased. This is of benefit in particular during high-speed rides on motorways.

The technology also allows controlling the distribution of the light. Thus, the beam can illuminate specific sections of the illuminated area, resulting in a highly dynamic and variable overall illumination and, likewise, shading.

Another achievement is the intelligent, lighting-fast switching of the laser diodes depending on the mirror position. Similar to today’s matrix LED headlights, the new dynamic laser headlight always illuminates the road at high intensity without dazzling other traffic participants. The decisive difference to matrix LED headlamps is that the matrix laser offers a significantly higher resolution and thus a higher utilisation which improves traffic safety. In addition, this technology enables innovative lighting assistance functions.

The new technology employs blue laser diodes (provider: Osram) that feature a light wavelength of 450 nm. The light is directed towards a fast moving mirror with a diameter of 3 mm which deflects the blue light to a converter which generates white light and projects it to the road. The micro mirror is implemented as a silicon MEMs device (provider: Bosch). The same MEMS is used for acceleration sensors and for electronic stability control (ESP) gear.

The development of this intelligent lighting system takes place in the iLaS project along with research partners Karlsruhe Institute of Technology (KIT), Bosch and Osram.

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