Last month, BMW announced it was developing laser-based headlights and the Internet lit up with Star Wars jokes and concerns about potential hazards. To clear things up, BMW invited Scott Evans of Motor Trend to Munich to see how they work.
BMW’s laser headlight system, which debuted on the i8 Concept at the Frankfurt show last month, uses not one, but three blue lasers per headlight for a total of twelve on a standard four-headlight BMW.
To understand how the lights work, refer to the diagram. The three lasers (A) are mounted in a triangular pattern and shine onto small mirrors (B) which redirect the beams into a lens (C). Within the lens is yellow phosphorus, which when excited by the blue lasers, emits intense white light. That light is directed by the lens to the reflector (D), which bounces the white light back 180 degrees and out onto the road ahead. The headlight casing contains any extra reflections and helps direct all the white light out the front. In the upper right corner of the diagram you can see one of the lasers, though it’s being interrupted by a card in this picture. It should be noted that this demonstration rig is just one possible configuration of the system, which can be scaled to just about any size needed.
BMW says its laser system is 1000 times brighter than LED headlights but uses half the power, reducing the electrical draw on the engine. Further, the company says that its lasers will last 10,000 hours, just like LED systems. What’s more, the scalability of the system allows BMW’s designers much more freedom in sculpting headlights on future models.
Of course, the first thing we all learned about lasers is not to point them at yours or anyone else’s eyes for fear of retina damage. With headlights, that simply isn’t possible, but BMW says there’s no need to worry. Laser light is dangerous to your eyes because it’s extremely concentrated and focused. The white light produced by the excited phosphorus is not and to demonstrate its safety, the engineer in charge of the project stared straight into the headlights and invited assembled journalists to do the same. Though the lights are extremely light, neither your author nor anyone else present suffered any ocular damage.
There’s also no risk of the headlights doing any damage to objects in front of them or causing any fires (despite the fact that the engineer lit an incense stick from one of the laser beams to demonstrate its power) for the same reason. The actual light produced by the headlights is not laser light despite the use of lasers to create it. And if you’re worried about escaped laser beams flying around after an accident, like Xenon headlights, power is immediately cut to the laser headlights in the event of any damage.
BMW also showed off its new Dynamic LightSpot system, which in essence is a spotlight that illuminates pedestrians in your path. On the engineering model, the two spotlights were mounted in place of fog lights and are motorized like adaptive headlights. The system uses the same technology in BMW’s NightVision camera system, which uses cameras and infrared sensors to identify pedestrians by body heat and by their silhouette. Where the NightVision system would display a warning on the infotainment screen, the LightSpot system is more proactive, shining one of the spotlights on the pedestrian. Because there are two spotlights, two pedestrians can be tracked at once and because the spotlights are motorized, they can track the pedestrians as they cross your path.
To keep from being a distraction, the system has a relatively narrow field of view. While the computer keeps an eye out for any pedestrian who may dart out in front of you, it won’t active the spotlights unless a pedestrian actually enters your path and is in danger of being hit. BMW says the spotlights can swivel faster than a human can run, so there’s no missing any pedestrian lit up by LightSpot. The company says that early tests show that drivers are able to identify pedestrians in their path much earlier and at much greater distances, 112 feet farther out on average. Oncoming drivers will be spared any extra glare, as BMW says the system works with its Active High Beam system to stop the spotlights from pointing up into other drivers’ eyes.
Both systems are still prototypes, but BMW says they’re both headed to production in the future. LightSpots will reach consumers first, though BMW won’t say exactly when. Laser headlights are farther in the future.—Paul Duchene
