Pulsed laser scanning lidar technology has revolutionized the field of autonomous driving and robotic mobility. This technology utilizes direct time-of-flight (d-ToF) measurements to enable three-dimensional imaging of complex scenes. However, there are still several challenges to overcome for its widespread industrial application. These challenges include enhancing the observation field of view (FoV) with high angular resolution, improving the imaging frame rate, extending the ambiguity range, reducing fabrication costs, and decreasing component size.
A research group led by Patrice Genevet at Université Côte d’Azur in France has proposed an innovative solution to overcome some of the limitations of lidar technology and meet the demanding requirements of automotive lidar. Their work, published in Advanced Photonics, presents an experimental prototype of an ultra-fast high FoV pulsed metasurface-scanning lidar.
The prototype utilizes a laser diode modulated by an acousto-optic deflector (AOD) combined with a metasurface. This combination enhances the FoV up to 150° in both horizontal and vertical directions. To achieve this, the researchers continuously vary the optical properties of the metasurface to expand the narrow FoV of the deflector. This significant improvement in FoV allows for a more comprehensive and detailed scanning of the environment.
Pulse scanning lidar often faces challenges such as low signal-to-noise ratio (SNR) and poor accuracy for objects located far away within the ambiguity range. Additionally, there is a tradeoff between the ambiguity range and speed in d-ToF imaging. To address these issues, the researchers propose a novel imaging technique inspired by the code division multiple access (CDMA) pulse encoding method.
By leveraging the high scanning speed of the AOD, the imaging process takes advantage of the benefits of CDMA without compromising on the ambiguity range or the simplicity of the architecture. This technique enables imaging in low SNR environments and extends the ambiguity range of the lidar by up to 35 times compared to traditional single pulse lidar. Not only does this enhance the SNR of the lidar images, but it also improves performance in noisy environments or at longer distances.
The researchers emphasize that their new scanning lidar system, combined with metasurfaces, is a significant step towards meeting the requirements of automotive lidar. The system’s compact size and potential for miniaturization to chip-scale dimensions open up new possibilities for autonomous vehicles and the robotic industry. This advancement brings us closer to a future where these technologies are seamlessly integrated into our everyday lives.
This research provides a solid framework for the next generation of high-speed lidar systems. It not only offers insights into new capabilities but also paves the way for the development of cutting-edge technologies. The advancements in lidar technology improve the prospects of smoother autonomous driving and adaptive robots. As lidar technology continues to evolve, we can look forward to a future where these technologies become an integral part of our daily lives, making our world safer and more efficient.