An Active Multi-Power Emission Strategy for Time Walk Error Compensation in SiPM-Based d-ToF LiDAR

Time walk error significantly impacts the accuracy of distance measurements in direct time-of-flight (d-ToF) LiDAR systems. A system-level d-ToF model that comprehensively accounts for the mechanisms is established in this paper. Then, an active multi-power excitation (AMPE) strategy is proposed and verified in a silicon photomultiplier (SiPM)-based d-ToF LiDAR. Compared with conventional passive correction methods, AMPE actively injects known excitation constraints into the measurement process. It exploits the relationship between emission energy and threshold-crossing time by transmitting pulses with controlled power using a customized compensation algorithm. The core strength of this method is that it transforms the correction problem into a constrained estimation problem governed by emission control, thereby avoiding complex receiver-side timing circuitry and extensive offline calibration. A prototyped LiDAR system is developed, and experimental results demonstrate that more than a 72% reduction in walk error induced depth distortion is achieved with only 10 measurements per range point, enabling reliable 200 m operation under 60 klux ambient illumination. The proposed method establishes a novel time walk error compensation strategy, enhancing the energy efficiency and wide dynamic range of d-ToF LiDAR applications.