Headlight with 200,000 micro lenses provides better light

Headlight with 200,000 micro lenses provides better light

Technology News |
By Christoph Hammerschmidt

It is a segmented high beam with reduced stray light. The prototype presented is based on the multi-aperture projector, which has been continuously developed over the years. 200,000 micro-optics bundle the light optimally in the direction of travel. These can be switched off individually or in groups as required without any time delay. In combination with modern vehicle sensors, this effectively prevents glare from oncoming road users. Compared to conventional systems, the required installation space is greatly reduced.

Not only can oncoming traffic be blocked out; it is also possible to protect pedestrians or cyclists without light from glare, increasing the safety of all road users.

Over the next few years, manufacturers will also benefit from significantly greater design freedom in the design of car headlamps. Whether they are then installed as usual on the outside of the vehicle front or as a narrow band in the middle is then left solely to the designers’ intention. In addition to a very small overall depth, the system allows greater freedom in terms of dimensions and design. “You don’t have to design the headlights to be rectangular, you can choose any other shape,” explains Stephanie Fischer, a research assistant in the Microoptical Systems Department at the Fraunhofer IOF. “So far, the larger optics required have limited the design options.”

In addition, the new system draws more light from the LEDs. For example, only 35 percent of the luminous efficacy is lost with low beam – a very good value for LED headlights. This increased efficiency improves the energy balance in the vehicle.

The headlamp consists of two modules, each with seven individually controllable LED clusters. Their light is directed by a total of four collimating lenses onto two tandem lens arrays. These micro-optical elements distribute the light from the individual light-emitting diodes. Thousands of microlenses guide the light precisely into each lighting segment. This can be switched on or off in a fraction of a second by individually controlling a total of 24 LEDs.

Square polymer lenses in various dimensions were used for more precise light modeling. The smallest variant has a side length of 0.045 mm x 0.180 mm. Fraunhofer IOF has developed its own new production process for rectangular lenses for this purpose. On the one hand it allows the production of the finest microstructures, on the other hand it also allows the production of comparatively large profile depths up to 100μm. These are necessary in order to make optimum use of the existing luminance of the LEDs. Now the Fraunhofer IOF has been able to realize the first prototype of a dipped beam. Once all the components have been developed, 8,000 microlenses will ensure optimum visibility at night and in poor weather.

The prototype will be presented at the Laser World of Photonics trade fair in Munich (June 24-27), where researchers will present their results.

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