When the first Audi R8 appeared in 2008 with those unmistakeable two-tier LED daytime running lights, it set a new precedent. Seven years later, most new cars come with light emitting diodes providing some sort of illumination. So what’s next? Audi again is pushing the boundaries.
Debuting on the Le Mans-winning R18 hybrid racers, laser technology has now been installed on the road-going R8 LMX (featured elsewhere on the app today). Audi says that lasers can illuminate the road up to 500m ahead – around twice the distance of LED main beams – and shine three times as brightly as LEDs. And to quickly banish the elephant in the room, you will not lose your sight if you look into laser headlights. The system uses blue laser diodes to shine a highly concentrated – and highly energised – beam onto a phosphor diffuser. This turns the blue light into an eye-pleasing white, while scattering the focused light into a wider beam. Spreading the energy also means that we don’t go around frying wildlife and pedestrians! The beam is still more concentrated than a conventional high beam, however, so the lasers are used in addition to LED high beams.
To increase the intensity of the laser lighting, each headlight module contains a quartet of laser diodes (see illustration, above). A pair of prisms directs their outputs to an optical lens, which combines the beams before the phosphor converter.
Not only are laser headlights more powerful and efficient than their LED counterparts, but they look cool. And I mean that scientifically. Their light is emitted with a colour temperature of 5500 kelvin, which is roughly the same as daylight, and any colour temperature above 5000 kelvin is termed a ‘cool colour’ by optics scientists. A benefit of this cool light is that drivers can detect contrasts better and suffer less eye fatigue.
You may now be thinking of a potential problem with laser technology. We already know that xenon or LED main beams can be particularly dazzling to other drivers, and now even higher powered laser lights are being added on top. To avoid this being a problem, Audi has included a control system that uses a camera to detect if there is another vehicle in the headlights’ field of view. If there is, main beam, including the lasers, is momentarily turned off so as to not dazzle other drivers.