Light technology is developing rapidly. To make the most of its potential, Porsche has designed a new light tunnel. After taking roughly three years to complete, this state-of-the-art development instrument will start operation at the turn of the year. The light tunnel is directly adjacent to the design studio at the Weissach Development Centre. The one-and-a-half storey building offers some 2,300 square metres of floor space. The mezzanine level has a test facility for automatic test procedures for legally prescribed light measurements, as well as a warehouse for sample headlights from many Porsche vehicle models. The front area of the new building is used to prepare the trials. This is where the vehicles are cleared of snow and ice, if applicable, in an airlock. If necessary, the headlights can also be swapped here. The building also has an in-house analysis and testing laboratory for independent measurements of the luminous intensity and light distribution of headlights.
The heart of the system is a 100-metre-long and 15-metre-wide test track. For the first time, this enables developers and designers to test and fine-tune light systems under consistent conditions at any time of day or night, regardless of weather conditions. The tests can range, for example, from the simple presentation of a headlight using a sample to a situation involving oncoming traffic in road traffic. The 100-metre-long asphalt track features a two-lane design for this purpose. For a given situation, the dazzle from oncoming traffic can be identified at an early stage in the light development process. In a further scenario, the two vehicles are placed next to each other at the start of the test track – this allows a direct comparison of the beam length, illuminated area and headlight graphics.
Two mobile folding partitions make it possible to divide the test track into up to three individual sections to circumscribe the spaces for light testing. This enables experts to assess different lighting situations in isolation – for example, headlights and tail lights. A mobile ten-metre screen that enables the display and evaluation of light distributions is installed in the first segment. The vehicle stands on a very precisely levelled surface to enable examination of factors that impact the vehicle level, such as the air suspension or load.
Extremely smooth walls and ceiling for undistorted light distribution
The floor, walls and ceilings of the new light tunnel have been specifically adapted for the intended use. The wall and ceiling areas are dark grey and feature a homogeneous colour over the entire track distance. This is a fundamental requirement for defining and checking the exact light distribution of high-resolution headlamps. “Unevenness, reflections or deviations in colour inevitably falsify the result,” says Steffen Poganatz, the Overall Project Manager for the construction project. The walls are therefore also exceptionally smoothly plastered and coated with a matte paint, since even a slight unevenness of just a few millimetres would be visible in the light. The four-meter-high ceiling also has a low-reflection design.
This optimal environment also helps identify variations in the luminous intensity of individual LEDs in a matrix headlight. Manufacturing tolerances like these can be largely compensated by means of an adapted control setup. “When cornering in particular, such deviations may become noticeable in the form of abnormalities in carpet of light,” explains Markus Heinrich, Specialist for Front Lighting Systems.
The light tunnel significantly improves and shortens development capabilities and times for complex light systems. Until now, developers had to wait for darkness to fall in order to examine or compare light systems. In the summer months in particular, this usually meant working at night. And the results were only partially comparable: “Wet conditions, the composition of the asphalt and the ambient lighting also significantly influence the impression,” says Jörg Biegling, Manager of Light System Testing and Integration.
