BMW's piercing laser headlights

BMW is officially pioneering the development of laser-powered headlights for production cars and has beaten rival brand Audi to the punch.

The advanced safety technology will roll out with the high-tech hybrid i8 sports car, quickly followed by the 7-Series and, possibly, the next X6 as well.

In two months, when the laser-powered units arrive as an i8 option there will only be one other production light in the world with more lighting power, and that’s the one fitted to the Leopard tank.

So powerful is the laser light in the i8 that it’s nearly three times as powerful as the maximum allowed under an archaic United States law, so the self-proclaimed most advanced country in the world won’t be getting the system.

At 344 lux, the i8 headlight’s high-beam function is limited to the very maximum strength allowed under EU law, though it is engineered to deliver 400 lux.

The reality of what we saw on a late-night test drive in France yesterday was that all that power added up to deliver clean, soft white light as far out as 600 metres. If your eyes could manage it, you could read a newspaper from half a kilometre away.

And, far from dazzling oncoming traffic, the system links to BMW’s existing active headlight control units to arc away from the cars it’s following or heading towards, providing enormous vision without impacting other road users.

The lights not only track around corners on swivels, but they also move vertically and horizontally around other road users, from cars to motorbikes to bicycles, leaving a black spot where the other road user is.

The system fires up in high beam with two intense bright lights, which seem a little like long rabbit ears, nearly joining, but leaving a slightly darker patch between them.

Ideal for a country like Australia, with its potential for hours of barely interrupted high beam driving, the system lights up the trees, grass and scrub on the roadside like nothing before it.

In fact, its biggest issue we found with the laser lights is that they reflect too strongly and brightly off reflective road signs. With these lights, the roadside signs don’t need to reflect at all.

Mr Hausmann says his team is aware of the issue and it’s being worked on, with production units being able to swerve the light beams around large reflective surfaces as well as away from other cars.

To allay fears that people will be blinded by the laser lights, just like pilots have reported when assailed by ground-based lasers while trying to land aircraft, the lasers on the BMW headlights are actually directed back towards the car, not out into the darkness.

The light unit itself contains three laser light-generating engines, a prism containing phosphorous and a reflector unit, all contained in BMW’s swiveling active light core, BMW’s Manager of Pre-Development for Exterior Lighting Thomas Hausmann explained.

“You never see the actual laser part of the laser light. The laser just excites the phosphorous and the photons from the phosphorous create the light and that comes back towards the car and is reflected out the front of the unit,” Mr Hausmann said.

“Three lasers are mirrored onto the prism of phosphorous, then back to the reflectors.

“The laser beam converts to bright white light because it heats the yellow phosphorous. The blue laser diode converted its stream of light into white photons from the phosphorous.

“The light comes out all scrambled like normal light, but cleaner, very white and not at all uniform like a laser.”

Another issue is cost and, while it won’t be cheap (BMW hasn’t announced the cost of the system yet), it won’t be the leap over LED systems that LEDs were over Xenons before them.

“The first generation is never cheap. The first generation is not representative of the cost going forward. That’s why, after we are first, we are comfortable letting Audi use the technology. It helps the price to come down.

“Look when we put the LED in the 6-Series, the costs were immense. This is a lot less than the first LED cost, though.”

Mr Hausmann insisted they’d even bought in the best rally pod lights in the business for comparative testing in BMW’s German laboratory, but found them no match for the lasers – even when the rally lights were arrayed in groups.

“We aren’t the most powerful light out there, because the Leopard tank has over 600 lux, but it’s a relatively old technology,” Mr Hausmann said.

“It uses High-Intensity Discharge (HID) technology. We know exactly what that one does because I bought one for 700 euros over the internet to use it as a benchmark.”

BMW has data on all of these lights because, on top of on-road testing, it compared them all in its own lighting lab.

“You can test them on the road, but it’s difficult to remember what the exact light spreads are once you walk out of the car. That’s why we do them all in the lab. It’s precise there,” Mr Hausmann said.

Employing a light engine made by Osram, but developed in conjunction with BMW, the system uses around 10 Watts of power, which is about a 30 per cent improvement over a typical LED headlight – itself about a 30 per cent drop from HID lights.

“The problem is the heat of it. If you touch the outside of the light, it’s actually cold, but not inside,” he said.

“It’s a very, very small surface to produce the light and that’s where we also produce the temperature. It gets very hot there.

“To get that temperature away from the laser diode was a big problem – far more of a problem than with LED units and the diodes aren’t made for the same temperature as LED diodes.”

Sadly for them, this is not a technology headed for the United States, which adheres to halogen-era lighting rules.

“In the US, it’s pointless to deliver this system. We’d have to turn it down too far. LED is fine for what they’re allowed to do,” Mr Hausmann said.