Audi head of lighting innovations and functions Stephan Berlitz spoke with CarAdvice on the attractions and limitations of laser headlight technology, before talking about its ongoing development.
In the Audi R8 LMX, laser beam is used only as a supplement to the existing LED headlights, activating only when automatic high-beam is being used with the aim to double the range of light compared with LED high-beam – to a full 500 metres.
So, how does it work?
Where many light-emitting diodes (LED) are used within a regular headlight assembly, lasers work in a different fashion. In the R8 LMX there are only four laser diodes each with a diameter of 300 micrometres, or just 0.3 millimeters – talk about tiny! They are wrapped tightly in what Audi calls a “radiation-tight aluminium module.”
Rather than pointing out towards the road like a normal beam, however, they instead are directed in a V-shape to a single point on a mirror, each strand of laser producing a wavelength of 450 nanometers.
The light then reflects onto what Audi calls a “converter”.
At this point the laser light is blue in colour, and harmful to the human eye. However the converter is actually a phosphor plate “no larger than a pin head” that is designed to “refract and convert” the light into pleasant-to-the-eye white light. With a colour temperature of 5500 Kelvin, the transformed beam comes closer to looking like daylight than other light sources.
“What comes out at the front is produced by laser, but it’s then converted into normal light,” clarifies Betlitz (above). He pauses and draws an interesting comparison, saying that the blue laser is similar to that used inside a BlueRay disc player, only with a “much stronger” beam.
The laser-produced light is thrown 500 metres down the road – twice as far as regular LED high-beam. If you think that is far, however, the laser headlights used in the Audi R18 e-tron that raced in the Le Mans 24 hour can throw forward 10 times the amount of light of the Audi R8 LMX supercar.
For production cars, Berlitz says laser headlights will likely only be used as “supplements” to LED low- and high-beam. This is partially because the light source of a laser is small and pointed rather than having a sheer breadth of cover.
Technically, there could be all-laser headlight units produced, however given that only four diodes are currently prohibitively expensive for most cars, he argues that price would rule out a full application of laser lighting.
“It could be done with a correspondingly large number of laser diodes, but at ten times the price,” clarifies Berlitz.
The laser headlights in the R8 LMX, which are made by lighting company Osram one hour away from Audi’s Ingolstadt headquarters, work only above 60km/h and they switch on and off automatically at high-beam only.
We found a dark rural road outside of Audi headquarters to test the laser headlight technology, which proved very, erm, illuminating. The system is actually pretty uneventful, using the auto high-beam to dip the headlights when cars are travelling next to you or towards you.
But when the high-beam raises again, it does so in two stages - first the LED high-beam, then the laser beam that extends the range noticeably.
Since the light is so piercing, the automatic high-beam function is necessary to avoid the potentially dangerous situation of blinding other cars to an even greater degree than normal high-beam, tells the lighting innovations manager.
Audi has been in a fierce battle with BMW over which company will be first to release laser headlight technology in a production car, so it’s no surprise that Berlitz is quick to point out that the R8 LMX has four laser diodes compared with three in the BMW i8 – though the BMW claims to extend to 600 metres, 100m further. Laser headlights are also optional in the i8 but standard in the R8 LMX.
BMW apparently pulled forward the on-sale date of its i8 supercar, of which only nine have been made, to beat Audi to market with laser headlight technology, but Berlitz says of the rivalry: “it’s marketing, not technology.”
“We have this 99 [production] cars, BMW has nine cars,” he jokes.
Berlitz said he couldn’t give an exact estimation of the additional costs of the laserlights inside in the R8 LMX compared with the regular model’s LED headlights, but explained that the charge far outweighed the complexities of integrating the system.
“At the moment everything is expensive because we don’t have a big number of pieces … the most expensive is actually the diode itself,” he told.
The physical change to the inside of the R8’s headlights was “not a big change actually,” he continues. “Most of the module is the same. Life was easy for us, we just had to adjust and bring in the laser bezels.”
The laserlight module – incorporating the four laser diodes and the converter – meant shuffling along the R8’s LED headlight modules and reorganising them in a way they could fit within the existing assembly.
Although Berlitz admits laser lighting generates much more heat than the equivalent LED lighting, a fan with complete cooling system had already been integrated into the R8’s headlight assembly to ensure optimum running temperatures are maintained.
The current R8 doesn’t, however, feature Audi’s matrix LED lighting system, which when high-beam is being used detects vehicles travelling ahead or oncoming traffic, then switches off relevant LEDs to block only the strand of high-beam affecting a particular vehicle.
Berlitz admits the laserlight technology would work best in tandem with the brand’s matrix LED lighting system, but adds: “we didn’t want to develop a whole new system [for R8].”
“It could be the next step, I like the idea, for the future it makes sense to combine this technology,” he teases, all but giving away that Audi will combine matrix LED lighting with laserlight technology in future production cars.
Berlitz argues the reason the R8 was chosen to debut laserlight technology was “because it’s for high speeds and it is our fastest car, and it makes sense to have a longer distance [of night vision] if you are going fast.
The R8 was also the first to get LED headlights, and now it is the first to get laser headlights, so it’s some sort of trend that this car gets new light technology.”
He calls laserlighting “top-down technology” that is currently “much more expensive” than regular LED headlights, but reveals that future Audi products are already locked in to utilise the system.
“About the next cars that are coming out, next year maybe. It’s already done, they are already developed,” he adds.