The demands on headlights are getting higher and higher. For instance, the installation space of headlights has to be reduced, while both efficiency, light quality and safety are improved. To meet these requirements, high-definition systems are increasingly being chosen, in many cases using laser light sources. Within the research project HipE, HELLA KGaA Hueck & Co. and the Fraunhofer Application Centre for Inorganic Phosphors are working on a high-definition headlight with a laser light source.
The development is part of the HipE research project, which aims to develop pixelated phosphors for laser emissions in headlights. The research project started in March 2016 and has a duration of 3 years. The project is co-funded by the European Regional Development Fund (ERDF).
Individually adjustable light pixels
Laser light sources contain individually adjustable light pixels, leading to higher efficiency. In addition, the light sources have a high light output, so a smaller light area provides more light. As a result, installation parts such as reflectors can be made smaller, allowing for a more compact design of headlights. These features make laser light sources an interesting alternative to traditional headlights based on halogen or xenon lighting.
Commenting to Maakindustrie.nl, HELLA says that such headlights can only be used in practice after blue short-wave laser radiation is converted into white broadband radiation. This is as the Economic Commission for Europe (ECE) mandates the use of white lighting in cars on European roads. To convert blue short-wave laser radiation into white broadband radiation, a phosphor coating is used on the light source, HELLA explains. This coating absorbs part of the blue short-wave laser radiation and produces yellow light using fluorescence. This yellow light is combined with the remaining blue short-wave laser radiation, making the final light appear white to the human eye.
Optimising materials
As part of HipE project, the Fraunhofer Application Centre for Inorganic Phosphors is testing the conversion properties and heat expansion of different materials for this process. Suitable materials are then optimised. HELLA is focusing on a new mechatronic-optical concept for the construction of a complete headlight module. This includes investigating which optical systems offer a more compact design and greater efficiency. HELLA is also working on a 'demonstrator', a prototype in which the new components will be demonstrated. Eventually, this prototype should lead to a final product, which will be produced on a large scale. HELLA says it cannot predict when this final product will be available.
Incidentally, some laser light sources are already available on the market. Among others, the Audi R8 and BMW i8 are optionally available with high-beam headlights based on laser light sources. HELLA states that these increase vehicle visibility at a distance of 300 to 600 metres.
By: Wouter Hoeffnagel
Source: HELLA
Source photo: StockSnap via Pixabay
