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Audi's new drivable light tunnel is being used to research ever wider use of lighting systems for future models.

Audi’s tunnel of light leads to the future

Audi is seeing light at the end of its new research tunnel; and it is a laser. But not just any laser: this is a matrix laser that the Volkswagen brand is confident illuminates the way forward in lighting technology via an intensive light pattern for “virtually every situation” experienced on the road.

The company's engineers are focusing far ahead with R&D programs that include future cars saving energy by sharing road illumination. According to Audi’s Dr. Wolfgang Huhn, Head of Development, Light/Visibility: “We are thinking in many directions, including machine learning, where self-learning algorithms continuously improve the illumination.”

Light from matrix laser and matrix LED technologies will be linked to camera systems to control light with great precision, added Stephan Berlitz, Head of Audi’s Lighting Innovations: “And where our field of vision ends, we can use Car-to-X technologies—i.e., information from other cars and infrastructure.”

Audi pioneered the MatrixBeam technology—together with Hella and Automotive Lighting on the TT and ZKW (Q7)—over the past couple of years, and its new “tunnel” will be central to extrapolating that work and pushing the light envelope still further.

The tunnel is at the heart of company’s new €4.5 million Lighting Assistance Center (LAC) at its Ingolstadt, Germany, headquarters. With a length of 120 m (390 ft), it is described as the largest drivable light tunnel in Europe. It has a street-like floor, a turntable and scale for vehicles, and a laser laboratory among its facilities. For most of its length it is 12 m (39 ft) wide and 5 m (16 ft) tall, but these figures expand over the final 25 m (82 ft) length to 18 and 9 m (59 and 30 ft), respectively.

The work in the tunnel and associated laboratories (in the basement of Audi’s Center for Electrics and Electronics’ building) embraces every aspect of car lighting, including not only safety but also aesthetics—something that Audi regards as a very significant aspect of marque identity. Berlitz wants to take the emerging light technologies and arrange them into what he terms “a new aesthetic language.” Various models are being given individually distinctive daylight running lights sufficiently subtle to indicate the type of vehicle.

Audi’s motorsport program—particularly Le Mans—continues to play a significant role in lighting development for road and track. The racing R18 e-tron quattro and special edition road-going version of the outgoing generation R8 LMX were shown at Le Mans with a laser spot system that incorporates laser diodes linked to phosphor converters capable of creating white light.

Earlier this year, Audi revealed matrix laser technology. This involves a laser spatially separated from the headlight. The system includes the use of over 400,000 separately controlled micromirrors breaking up the light into minute pixels. Each micromirror can be tilted by some 5000 times/sec. The system allows the creation of an almost infinite number of light patterns for almost every driving situation. It can also provide light markers on a road surface to help the negotiation of narrow lanes through construction work.

In the R8 LMX, the laser spot supplements the LED high beams.

Laser-spot capability is to be introduced on several Audi models. The system includes four powerful laser diodes in each headlamp module, each with a diameter of 0.3 mm (0.01 in), to generate a monochromatic and coherent blue laser beam having a 450-nm (18-µin) wavelength. A phosphor luminophore is then used to convert it into white light with a color temperature of 5500 K suitable for road vehicles. With its use of laser technology, Audi stresses that there is no risk to human eyesight. The laser spot is dipped when an associated camera detects oncoming vehicles. The matrix laser headlight DMD (Digital Mirror Device) technology, commonly used in video projectors, is now in its pre-development phase at Ingolstadt for wider use in volume production vehicles.

Because lighting is used by Audi as a brand signature, a close association between designers and engineers is vital. Technical Development boss Prof. Dr. Ulrich Hackenberg has described lighting as “bringing technology to life and design differentiation.” Berlitz added: “Our colleagues in Design help themselves to our ideas pool and in turn contribute their own suggestions.”

The lighting systems of the future will also incorporate another differentiating feature: software, developed in-house by Audi.

In the shorter term, R&D work may lead to production vehicles equipped with OLED technology for taillights. Organic light-emitting diodes are based on an organic paste-like material; when a voltage is applied, the molecules enclosed in the material release photons, causing the surface to illuminate.

At the light tunnel, Audi demonstrated OLEDs providing a 3D effect achieved by positioning OLED surfaces upright and one behind the other. “We are working in predevelopment with solutions where we apply OLED coatings directly to the vehicle body’s sheet metal,” said Berlitz. However, the new technology has its limitations. New materials are needed to allow OLEDs to be attached to a curved surface, and the material can only cope with temperatures of up to 80°C (176°F), so requiring effective thermal management. Audi has already succeeded in fusing light and the body in concepts and regards the results as another identity indicator.

For interiors, Audi is also investigating the use of small spots of light to enhance the surface effect of upholstery and decorative inlays. Light can provide what the company terms a “velvety soft” appearance to leather or make a CFRP (carbon fiber reinforced polymer) facing “reflectively glossy.”

The eventual introduction of autonomous driving is expected to provide further roles for light technology. Audi demonstrated a steering wheel rim that uses green lighting that turns to red indicating to the driver when manual vehicle control is needed. An alert could also involve the lower windshield trim erupting into a red flashing line.

In addition to OLEDs, series applications of which could be less than 5 years away, further materials R&D work includes the use of MID (molded interconnected devices). The technology is based on an innovative polymer containing an organic metal complex. MID lighting assemblies can be developed in any desired form, says Audi, adding that it represents a huge improvement compared to present 2D printed circuit boards.

The use of flexible silicone and foamed polymers also offer light treatments, the former allowing the creation of very small lenses with tight radii to provide refracting angles similar to glass lenses. Clasps for daytime running lights could be created using foamed polymers. Optic fibers of polymer or quartz glass emitting tip, or whole length, light that can be woven into textiles are also on Audi’s comprehensive light list.

Advanced lighting systems will require legal requirements to be modified in many markets, a factor which could slow introduction unless addressed soon.

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