BMW lights up the future with lasers

A BMW technician wearing orange safety goggles focuses the beam of a laser headlight in the laboratory and yes, Cyril, the light is blue.

A BMW technician wearing orange safety goggles focuses the beam of a laser headlight in the laboratory and yes, Cyril, the light is blue.

Published Oct 17, 2011

Share

BMW is about to change the way we see while driving at night, with two new headlight technologies.

It calls the first Dynamic Spot Light, saying it enables better focusing of the headlight beams, to highlight objects on the road at night such as pedestrians or animals.

The Blue Propeller Boffins don't say whether this means a cleaner, more accurately shaped reflector bowl than is presently possible, an optically ground lens in front of the light source, or an auto-focusing mechanism similar to that used in digital camera lenses that would actually focus the beams on an unlit object that's perceived to be a hazard by the car's radar system.

Our money is on the third possibility, partly because it's electronic and it's complicated (BMW, like Honda, seldom uses one component where three will do) and partly because, complex as it may be, it will be cheaper to mass-produce than the microscopic accuracy required to make the first two a reality.

But the next big thing in night driving, says BMW, is going to be laser headlights - and it's hoping to bring the technology to a showroom near you within a couple of years.

BMW reckons that this is the next step after LED technology, which has gone about as far as it can. LED's are by their nature small, so you need a lot of them bundled together to get the same amount of light emitted by, say, a bi-xenon headlight.

A laser-beam headlight could produce light with an intensity a thousand times greater than an LED while using half the energy. It does that by rearranging the light waves in a beam of light until they are all "in step" (the technical term is coherence) and each wave reinforces the next (that's called constructive interference, and has nothing to do with the building inspector giving you a hard time about your new double garage).

All of which sounds great, but there are issues; the first is, of course, the distinct possibly of permanent blindness for anybody looking into the lights of an oncoming BMW.

The second is that, for light waves to be coherent, they absolutely have to be the same wavelength. All lasers are thus monochromatic - which is why the laser pointer you're so proud of throws a bright red dot.

White light is an even mix of all seven basic colours (each of which has a different wavelength) so a white laser is, by the very nature of coherence, physically impossible.

However, Cyril has pointed out that pale blue xenon headlights are already quite common, so it might be possible to make a workable laser headlight using coherent light from the blue section of the spectrum - which would certainly make that late-night pedestrian stand out, even if it does make him look like a ghost!

We'll just have to wait and see (pun intended) what BMW comes up with.

Related Topics:

bmw