More light: What comes after xenon, LED and laser?

 

The latest innovation to be announced in the meantime is the LED-based laser headlight, which Audi presented accordingly spectacularly in the R18 e-tron Le Mans at CES in Las Vegas. The LED light, which is preparing to replace the conventional light bulb everywhere in the car, offers many more possibilities than a light source with an incandescent filament. For example, individual LED segments can be switched on and off selectively. This allows oncoming vehicles and those ahead to be literally cut out of the high beam cone.

Modern headlights with Matrix LED in the Audi Q7

At Audi, this technology is called matrix light. This feature can be ordered for an extra 2000 euros. Audi is intensively researching and developing a wide range of technologies for the light of the future. The manufacturer from Ingolstadt sees itself as a brand with a formative lighting design and associates the terms aesthetics, dynamics and interaction with it. Recently, a Light Assistance Center (LAZ) was inaugurated in Ingolstadt, which serves as a future laboratory. Reason enough for ams professional to take a closer look at Audi’s current developments and research in the lighting sector.

Matrix light

Audi matrix LED technology divides the LED high beam into 25 small high beam light-emitting diodes that interact with five upstream lenses or reflectors. Managed by a fast control unit, they are switched on and off or dimmed individually depending on the situation. As a result, they always provide highly precise illumination and maximum possible luminous efficacy without the need for a swiveling mechanism.

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Filigree components of a matrix LED headlight.

When the light switch is set to “automatic” and the high beam is switched on, the system becomes active at speeds of 30 km/h in extra-urban areas and 60 km/h in urban areas. As soon as the camera detects vehicles, the LED headlights turn off the high beam in the necessary sub-areas. The system works so precisely that oncoming vehicles and vehicles in front are blanked out, but all other areas in between and next to them continue to be fully illuminated by the high beam.


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The matrix LED headlight can switch individual segments on and off.

This is also made possible by networking the headlights with navigation data (GPS). For the driver, this is a relief, as he can always be on the road with high beam, because the system itself recognizes when it has to switch on or off or change. In addition, the function of a marker light is possible. Here, the high beam cooperates with the night vision assistant and marks detected pedestrians. If a person or obstacle is in the critical area in front of the car, individual LEDs flash them three times briefly. The pedestrian is thus clearly singled out from his surroundings and warned, and of course the driver is warned at the same time.

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The structure of a Q7 matrix LED headlight with 30 controllable LEDs.

However, the LEDs of the Audi matrix LED headlights can also be used for the cornering light function. Then they simply shift the center of gravity of the light in the direction of the curve. With the help of predictable route data from the vehicle navigation system, they can do this shortly before the steering wheel turns.
Audi is currently working with 25 individual segments that can be switched on and off in the matrix light. Other manufacturers also offer such electrically controlled LED headlights. In its multi-beam technology in the CLS, Mercedes currently has 24 LEDs that can be intelligently controlled, and would soon like to accommodate 84 and later 1024 of them in the headlights.

Laser light on the advance

LED technology offers technical advantages, but it also makes ecological sense because it is comparatively energy-efficient. But if LED light is so advantageous, why is there still a need for laser headlights? For Audi and BMW, who are racing each other on this technology, this is clear: a laser headlight achieves twice the range of an LED beam with its spot, namely around 600 meters. Incidentally, the legislator has limited the range to 650 meters. The laser headlight was first introduced in automobiles by BMW in the i8 and by Audi in the R8 LMX.

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Externally, only a lens is visible from the laser headlight.

One thing in advance: You will look in vain for red or green laser beams like in “Star Wars”. In reality, no laser beam is emitted at all and thus cannot be dangerous for the eyes of humans. Instead, the four laser diodes emit light with a wavelength of 450 nanometers. The laser spot has a light with a bluish glow. It is directed onto a phosphor disk, where it is fanned out and converted into white light.


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A laser beam is fanned out by the phosphor element and by many mirrors, and white light reaches the road.

In the R8, the light was then directed onto controllable mirrors (Digital Micromirror Device, see DMD info below).
The principle of DMD technology is also known from DLP video projectors (“beamers”). From the outside, only the projection lens is visible; it forms the pupil of the spotlight. Below it, in a filigree lightweight structure, are five additional plastic lenses that further expand the light. The laser itself is located separately from the headlight in the engine compartment and feeds all the lenses via separate fiber optic bundles. A total of four tiny laser diodes in each headlamp generate a high beam that shines for six hundred meters.

Further laser plans

Audi is now also working on another solution for future laser headlights. Instead of many controllable mirrors, only one very fast-moving micromirror will then be used to deflect the laser beam.

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In the future, only one controllable mirror will be used in the laser headlamp

At low speeds, the light is distributed over a larger area and the road is very broadly illuminated. At high speeds, the aperture angle is smaller and the intensity and range of the light are significantly increased. This is particularly advantageous for highway driving. In addition, the light can be distributed in a targeted manner. This means that by controlling the time spent in certain illumination areas, the brightness is variable. Another new feature is the intelligent and lightning-fast switching on and off of the laser diodes depending on the mirror position.

Interior lighting design

Audi wants to integrate lighting functions into the décor elements in such a way that they warn the driver of dangers or convey important signals during piloted driving. An interior model shows just how far the new information and safety functions could extend in the future.

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Center tunnel, doors, instrument panel and steering wheel are backlit by LED and warn when needed.

The oak plywood that serves as a decorative inlay on the center tunnel console, doors and instrument panel is backlit by LED. When exiting or parking, the light serves as a warning. For example, when the driver activates piloted driving and the car is driving autonomously in a traffic jam, parts of the steering wheel rim light up green. As soon as he has to take over the wheel again, the lighting changes to red.
Both here and in the so-called marker lights – extremely narrow light guides that follow the contours on the instrument panel, in the doors and on the center tunnel console – there is a choice of 32 colors each. The marker lights work intelligently with the “exit warning” assistance system.

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So-called marker lights work closely with the driver assistance systems

If either the driver or a passenger wants to open a door even though a bicycle or vehicle is approaching from behind, the light guide flares up in signal red and pulses at short intervals.

Networked light: car-to-x communication

Car-to-X communication, i.e. the networking of vehicles with each other and with the traffic infrastructure, also offers great potential for lighting. Cars will then be able to exchange data with each other and thus coordinate the luminosity of their headlights with high precision. As a result, they could jointly illuminate a road brightly or avoid glare at intersections and in meeting traffic. During a stop at a red light or in a traffic jam, the headlights could be dimmed. The light thus adapts to the existing conditions and communicates both with the driver of the car and with its environment.

OLED – the exterior light of the future

In addition to these many innovations, another technology is increasingly coming to the fore at Audi and also at BMW – OLED technology. At the moment, the premium manufacturers are working on sensibly integrating organic light emitting diodes (OLED) into the car. Among other things, Audi is using a model of a taillight unit in which several OLED surfaces stand upright one behind the other. Depending on the viewing angle, the surfaces look straight or wavy.

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Taillights in OLED technology

The problem that technicians still have to contend with is susceptibility to environmental influences such as temperature fluctuations. The material can currently only tolerate a maximum of 80 °C, which is why OLED lights require extensive thermal management.
The light-active material of OLEDs is an organic substance. The material is applied in its initial pasty state during production in a very thin layer, in the range of micrometers, to a one-mm-thick highly polished display glass. Without electricity, the OLED is a mirror. When an electrical voltage is applied, the molecules trapped in the paste emit photons and the surface lights up. Depending on the distribution of the voltage, this occurs either homogeneously, with specific light-dark effects, or even with dynamic movement.
Because OLEDs are so thin and also malleable in principle, they offer designers unprecedented potential for illuminating the car. In addition to normal lights, illumination of the interior, doors or tailgates is conceivable. The exterior light design in OLED technology that Audi is preparing for series production should be as intelligent as it is attractive. A scenario is conceivable, for example, in which the light reacts to the driver when he approaches his car:

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OLEDs offer designers unprecedented potential for lighting the car.

It moves with him, showing him important vehicle contours or the door handle. When the driver gets in, the light follows him – as discreet OLED lighting becomes active in the interior. The OLEDs greet the driver on the outside as he passes by.

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Design model OLED rear

Audi lighting designer Cesar Muntada’s vision for 2030 “is a light that is in motion and constantly interacts with the customer – from the moment he approaches the car.”

 

Future scenarios

The future scenarios of Audi’s lighting designers reach even further into the future, however, and in some cases sound like science fiction. The swarm light, for example, turns the entire rear end into a light surface.

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The so-called swarm light appears to be constantly in motion

And also like a swarm of locusts or birds, light pixels are constantly in motion within the taillight unit, which looks extremely fascinating and very dynamic.

Even more futuristic, however, is the idea of completely decoupling the headlights from the car and having them hover above the car in a light drone! The drone illuminates the vehicle apron and “explores” flying ahead already the parking lot in front of the nearest restaurant. This might even be technically feasible, but will probably never find favor with lawmakers.

Car lighting technologies have advanced at a breathtaking pace in recent years. Innovative lighting with controllable LEDs and lasers is making road users increasingly safer. LED and laser light, and not least OLED light, will also make lighting as a whole more dynamic, interactive and communicative.

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