Wide-angle diffuser establishes uniform lidar illumination

June 24, 2019 //By Christoph Hammerschmidt
Wide-angle diffuser establishes uniform lidar illumination
Lidar has established as a key technology for automated driving. For high-precision detection of distances between vehicles and their static and dynamic environment, the laser beam must be shaped into a light field with a defined field of view. Thanks to its zero hot spot beam shaping, the wide-angle diffuser from LIMO GmbH (Dortmund, Germany) delivers consistent performance, even in extreme operating temperatures, while its illumination area enables full coverage of the 360° surrounding view with just four lidar systems for reliable driving safety.

It takes more than the careful selection of an appropriate laser source and compatible detector to engineer a state-of-the-art lidar system. In a state-of-the-art lidar system, the optics that shape the laser light in the right direction are widely regarded as the most critical components. Up to now, the use of diffractive optical elements (DOE) has been limited to small angles and moderate ambient conditions. In addition, most of the optics used have an intensity distribution that drops flat at the edges.

The diffuser technology from LIMO takes a different approach: Similar to homogenization optics, LIMO designs glass refractive optical elements that have the ability to disperse laser light in one direction up to a full illumination angle ranging from a few mrad to over 100°. When combined with a second functional surface, the light can also be shaped at any desired angle in the other direction, making it possible to obtain a rectangular field with a steep edge slope and a user-defined size of 120° x 25°, for example.

“We can provide even illumination of the target area using the different angles, while a surface structure defined for the customer’s application delivers a consistent intensity distribution for the specific application,” notes Dr. Daniel Braam, Optics Product Line Manager at LIMO. “This is beneficial for noise reduction and increases the signal-to-noise ratio, and it also enhances the range of the lidar sensors as a result. In addition, since the new diffuser offers a large illumination angle of over 100°, self-driving cars only need to be equipped with four lidar systems to fully map the surrounding spatial environment.”

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