2010 to date Director Optical Technologies at Auer Lighting GmbH, Bad Gandersheim, Germany
2008 – 2010 Optical Engineer at Auer Lighting GmbH, Bad Gandersheim, Germany
2002 – 2008 Research fellow for “Nanostructure Optoelectronics” (University of Paderborn, Germany)
Ph.D. Thesis: ”Temperature dependent properties of single semiconductor quantum dots in the coherent regime”
Light Guides and Asymmetric Optics
It’s needless to say that LEDs are the light source of choice. In former times, when lighting was done using the emission of incandescent lamps with glowing metal filaments or discharge lamps the size of optics was often relatively large. This was due to the fact that discharge lamps have a very high luminance that has not yet been reached by LEDs (and may probably never be), but their emission pattern is omni-directional. This results in efforts to catch all the emission and thus shows drawbacks when it comes to efficiency or the ability to re-direct light into asymmetrical shapes. LEDs, on the other hand, feature a lambertian-type emission into just one hemisphere. This allows for the easier collection of light with the purpose of quality enhancement, feature addition and distribution to other places.
In the entertainment industry for example, colors and effects are essential. In the fixtures a multiplicity of LEDs are used. This spatially separated and spectrally different light sources can be controlled independently, allowing for smooth color variations. But they have to be subsequently mixed. This can be achieved with the use of light guides that rely on the optical principle of total internal reflection. By multiple internal reflections inside the material a homogenization of color is obtained. When combined with an appropriate structure on the output surface a well-defined and specific grade of mixing can be efficiently achieved.
Smartly using the laws of physics also the change of emission patterns becomes possible with light guiding components, resulting in non-symmetrical and complex light distributions. In demanding applications like the homogeneous lighting of baking oven chambers this ability is combined with the spatial separation of light source and target, saving the heat-sensitive LED from the harsh temperatures inside the cooking chamber.
In the world of automotive head-lamps an asymmetric light distribution is essential to avoid glare of oncoming traffic. Combining the light flux of several emitters (LEDs as well as LDs (laser diodes)) and forming the right distribution within smallest dimensions is the challenge in this case.
Since power and power densities of SSL sources are still increasing, glass is the optimal material for such light guiding optics. It easily handles the high temperature loads without ageing or yellowing. The physical dimensions stay constant with temperature and the dispersion is low. Small features for optical or mechanical purposes can also be implemented. We will show how a variety of applications can benefit from light guiding structures: from white goods applications over entertainment fixtures to the use in the automotive industry.