Radar and LiDAR sensors integrated into headlights

Five Fraunhofer institutes, including the Institute for High Frequency Physics and Radar Techniques FHR, have joined forces as part of the Smart Headlight project to create a method of installing sensors that is both space-saving and as subtle as possible – without compromising on function or performance. The project’s aim is to develop a sensor-integrated headlight for driver assistance systems that makes it possible to combine a range of sensor elements with adaptive light systems. It is hoped that this will improve sensors’ ability to identify objects on the road – and especially other road users, such as pedestrians. LiDAR Radar sensors, for instance, can be used in electronic brake assist or distance control systems.

“We’re integrating radar and LiDAR sensors into headlights that are already there anyway – and what’s more, they’re the parts that ensure the best possible transmission for optical sensors and light sources, and are able to keep things clean,” says Tim Freialdenhoven, a researcher at Fraunhofer FHR. LiDAR (Light Detection And Ranging) sensors operate using a measuring principle that is based on determining the time between a laser pulse being emitted and the reflected light being received, a method that produces exceptionally precise distance measurements.

The first stage in creating headlight sensors involves designing a LiDAR system that is suitable for integration into automotive technology. This also needs to consider the fact that the light beamed onto the road by the headlight cannot be impeded by the two additional sensors, even though the LEDs that are responsible for the light are located far back in the headlight. For this reason, the researchers are positioning the LiDAR sensors at the top and the radar sensors at the bottom of the headlight casing. At the same time, the beams from both sensor systems need to follow the same path as the LED light – something that is made more difficult by the fact that all the beams involved have different wavelengths. The visible light from the headlight measures in the region of 400 to 750 nanometers, while infrared LiDAR beams range from 860 to 1,550 nanometers, close to the visible range. Radar beams, on the other hand, have a wavelength of four millimeters. “These three wavelengths need to be merged coaxially – that is, along the same axis – and this is where what we call a multispectral combiner comes in,” states Freialdenhoven. Guiding the beams coaxially in this way is crucial for preventing parallax errors, which are complicated to untangle. Additionally, arranging the sensors next to one another would take up significantly more space than a coaxial configuration, so the researchers are getting round this using what are known as bi-combiners. To combine LED light and LiDAR light, this solution uses a dichroic mirror with a special coating, which guides the two beam bundles along a single axis by means of wavelength-selective reflection. The same effect happens in the second combiner (albeit in a more complex way due to the very different wavelengths), where the LED light, LiDAR light and radar are combined. As Radar sensors are already in widespread use in the automotive sector, bi-combiner designs have to allow manufacturers to continue using existing sensors without the need for modifications.

We specialize in manufacturing Radar sensors in China. we have the highest technology and stable quality control, welcome to inquiry it, please contact us by e-mail sales@radar-sensors.com for quotation requests, please provide quantity and any other specific requirements.