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How BMW's New Laser Headlights Will Work And Not Kill You

Ever since America escaped the tyranny of the round and rectangular sealed beams, there's been continuous and determined progress in the field of seeing at night with your car. We've gone from incandescents to halogens to HIDs to LEDs, and now, finally, we're going to have lasers. Like a pair of Death Stars at the front of your car.


Of course, like most currently hyped headlight designs, the name is deceptive. I hear laser headlights and I think, sure, I know how those will work. You just fire a pair of high-intensity laser beams out of the front of your car and you drive by the light of all the burning cars and buildings and trees. Brilliant!

Illustration for article titled How BMWs New Laser Headlights Will Work And Not Kill You

But, it turns out, that's not how they work. At all. In fact, the name is a little deceptive: they're not strictly laser headlights, they're something closer to laser-powered headlights.

If you think about light you've seen from lasers, two things in particular probably pop into your mind. First, the light is so focused and coherent that the beam tends to be focused into a tiny little dot that drives your cat bonkers. Second, you're probably aware that looking into most laser light is not a good idea if you like undamaged retinas.

BMW also seems interested in undamaged retinas and illuminated areas larger than a pimple, because they're not using direct laser light for their new laser headlights, which should first find use on the i8 as an option. Instead, the way BMW's laser headlights work is by aiming a trio of blue-laser diodes, situated at the rear of the light assembly, into a set of mirrors, which reverse the direction of the light and send it through a lens filled with yellow phosphorus.


Phosphorus is capable of emitting light when suitably encouraged, and yellow phosphorous, when excited by the light of a blue laser, emits a brilliant white light, which is exactly what happens when the reflected blue laser light passes through that yellow phosphorus-filled lens. That brilliant white light is then bounced off a reflector and, diffused, exits the headlight housing forward.

Illustration for article titled How BMWs New Laser Headlights Will Work And Not Kill You

The resulting light can be up to 1,000 times brighter than an LED while consuming 2/3rds (some say half) of the power. That's pretty impressive. Also nice is that the light's color temperature will be between 5500 and 6000 Kelvin. For comparison, natural daylight is usually estimated at about 6500 Kelvin.

The blue laser being used is powerful enough to catch things on fire, easily — watch that video above to see what I mean. But the actual light emitted from the headlights isn't coherent laser light at all, and as such is completely safe to look at. BMW says that in situations like accidents where the laser emitters may end up pointed past the mirrors and lens, the system would automatically shut down.


Still, I'm sure there's a way to override that, and an enterprising car hacker could, in theory, remove the other components so the car actually could shoot a functional laser beam from the lights. I'm not advocating this, but I imagine it's at least theoretically possible.

Illustration for article titled How BMWs New Laser Headlights Will Work And Not Kill You

Still, I don't think there's any reason to worry about that — any headlight system that casts light so well and uses so little power is a huge advancement, and I'm looking forward to seeing these on many vehicles in the future.

Also, the overall size of the unit is much smaller than current LED configurations, which should allow for more styling and packaging flexibility for future cars as well. The future looks pretty bright. And lasery.

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Why the mirrors? Why not have the lasers just hit the phosphorus cube directly?