Laser light: New headlight technology

Pioneering lighting technology for the high beam headlight

The BMW i8 and the Audi R8 LMX hit the market in 2014 at almost exactly the same time and were the first mass-produced cars with laser headlights. We played a large part in the development of this innovative laser light technology. This lighting trend opens up completely new horizons for headlights in terms of design and performance.

DR. ROLAND FIEDERLING, PORTFOLIOMANAGER:

Laser technology can now be used to build headlights that are significantly smaller and more efficient

Laser light is an absolute innovation in automotive lighting and marks the next big step forward since the introduction of halogen, xenon and LED headlights. It opens up completely new horizons for the design and performance of headlights. Laser diodes are particularly impressive thanks to their small size: A laser diode generates an almost point-like luminous flux of just a few micrometers in diameter.

The brightness is already at least four times as strong as that of an LED. This means that headlights can now be built to be much smaller than before – without having to compromise on light output.

The greatest advantage for drivers is that headlights with laser light have the longest reach of all currently available technologies, which means better visibility and greater road safety.

BMW i8, Audi R8 LMX and the new BMW 7 series: The first mass-produced vehicles with laser headlights

The BMW i8 and the Audi R8 LMX hit the market in 2014 at almost exactly the same time and were the first mass-produced cars with laser headlights. The BMW 7 Series followed in 2015. The experts at OSRAM played a significant role as system partners: Thanks to the laser technology, the high beam headlight on these vehicles achieves a reach of up to 600 meters – twice that of current conventional LED headlights.

Laser light in the car: Questions and answers about this innovative laser technology

QUESTION 1:

How exactly does laser light work?

The high beam headlight in the BMW i8 is able to reach up to 600 meters – twice as far as is usual with current LED high beam headlights – thanks to the relevant laser modules we developed, which are integrated in the full LED headlights.

They are activated as soon as the vehicle speed exceeds 70 km/h and the on-board camera reliably detects that there is no oncoming traffic. Here, we use the physical advantage of the laser.

Laser diodes can generate a lot of light in a small amount of space. A laser diode generates an almost point-like luminous flux of a few thousandths of a millimeter – which is why the lenses used can be very small.

The extremely high light intensity is also what enables the large reach.

QUESTION 2:

How exactly is the laser beam produced, and what are the individual steps?

The basis for the laser high beam headlight is a development from the research labs of OSRAM Opto Semiconductors in Regensburg. It’s only been a few years since blue laser diodes with a sufficiently high output of at least one watt have been available. They are based on indium-gallium-nitride technology and were originally developed for professional projection technology. The light color of such laser diodes can be freely adjusted within wide limits using the mixing ratio of the elements indium and gallium.

But you can’t simply transfer the laser diodes to a car, because in vehicles they must be able to function in a wide temperature window of minus 40 to plus 100 degrees Celsius.

It was hard work developing laser diodes that would safely function at temperatures of more than 50 degrees, because such temperatures are quickly reached in the presence of intense solar radiation.

The laser diodes emit monochromatic light with a wavelength of 450 nanometers, which is perceived as blue by the human eye. This light would be unsuitable for use in a car. What’s needed here is white light, ideally with a color temperature of around 5,500 Kelvin.

That’s why our specialists developed a module in which the laser light from several diodes first meets a converter. With the help of a phosphor, this converts blue light into white light – exactly what happens in modern light-emitting diode (LEDs).

QUESTION 3:

When did your company begin to develop laser light, what were the technical milestones along the way and who were your project partners?

The development of automotive “Laser Activated Remote Phosphor” (LARP) light sources began around five years ago. Milestones along the way included the drafting of various designs and the development of the prototype levels through to mass production.

QUESTION 4:

Where did this research and development take place?

The development of automotive “Laser Activated Remote Phosphor” (LARP) light sources began around five years ago. Milestones along the way included the drafting of various designs and the development of the prototype levels through to mass production.

QUESTION 5:

How is the laser for the car headlight different to lasers for other sectors (for example entertainment)?

The main differences between the automotive LARP systems and lasers in other sectors are the specific customer requirements from the automotive sector regarding space, environmental conditions as well as interfaces with the headlights, and time and cost pressures.

QUESTION 6:

How much does a headlight with laser light cost? How can you reduce the price in the future?

LARP systems are still cost-intensive solutions for premium vehicle manufacturers. Costs can be reduced by increasing quantities. This can be achieved by implementing LARP systems in mid-size vehicles, for example.

QUESTION 7:

What is the advantage of laser light compared with other light technologies (halogen, xenon, LED)?

Laser light generates extremely high light density, far higher than that of conventional technologies. The attainable luminance of a laser light source is at least a factor of 3 higher than with LED light sources. The extreme light density enables the use of very small lens components. These can be arranged randomly in the headlight and thus give headlight designers a great deal of freedom. Conversely, lens systems of a similar size as those found in LED applications can result in extreme reaches. Reaches of up to 600 meters are being achieved in current production vehicles.

QUESTION 8:

What is the status quo and what does the road map of laser light look like for the next few years?

LARP is facing strong development pressure. In addition to today’s complex systems in production, in the future there will also be smaller packages, which will give headlight designers more freedom and open up new areas of application. In the future, complex modules with corresponding luminous flux performance as well as small, compact modules with reduced performance will be offered.