41 However, the laser technology has to be combined with high-performance processing to produce the real-time point cloud that can be used for sensing and control algorithms. A typical Lidar system comprises a scanning laser, a receiver, associated optics, and integrated driver and processor circuits. It collaborates with cameras, sensors, and the position and navigation system. Lidar types Recent trends have seen a growing convergence on vertical-cavity surfaceemitting laser (VCSEL) and anti-reflective VCSEL (AR-VCSEL) based solutions. Lidar for autonomous vehicles falls into two main categories: primary Lidar, responsible for long-range forward perception; and supplementary Lidar, used for peripheral environment sensing around a vehicle. These can be used to provide 360° omnidirectional sensing, eliminating blind spots. The required detection range for primary Lidar varies globally from 150m to 350m. This is influenced by the vehicle speed limits, the targeted level of driving automation and regional regulations. Based on the detection method, Lidar technology can be classified into two types: frequency modulated continuous wave (FMCW) and time of flight (ToF). FMCW mixes returned light with frequency-modulated transmitted light to determine the distance and velocity of a moving object. Meanwhile, ToF determines the distance by calculating the time interval between the emitted pulse and the returned pulse. ToF is also the earliest technology used for Lidar such as the LRRR used by NASA in the aforementioned 1971 Moon mission. Currently, most Lidar manufacturers are using ToF technology due to its simplicity and lower cost. This combines separate LED lasers with a modulator, which can be a mirror or a metasurface; a material with a structure small enough to manipulate light (described below). The 1550nm laser used for telecoms optical fibre systems also provides long-distance Lidar with eye safety. While this contributes detection range and resolution, it faces significant challenges related to the high cost of the lasers and detectors built with indium gallium arsenide (InGaAs), as well as heat dissipation issues due to high power, reliability risk and large physical dimensions. The 1550 nm Lidar sensors can be mounted behind a vehicle’s windshield. They consistently deliver high-resolution detection of hard-to-perceive black vehicles at a distance of over 300 m, while maintaining a 120° x 20° overall field of view (FoV). This provides several advantages, including lower overall system costs and a cleaner roofline. The sensors have also accurately detected vehicles and other objects on busy freeways at distances beyond one kilometre. Lidar | Focus Lidar technology was used back in 1971 by NASA for a lunar Laser Ranging RetroReflector (LRRR) in Apollo 15 to map the moon’s surface Uncrewed Systems Technology | April/May 2025 Types of Lidar, from a mechanical mirror (top) through flash and 1D array to a 2D addressable array (bottom) (Image courtesy of Vertilite)
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