A Combined Analytical- and Optimization-Based Angle Calibration Method for Prism-Galvo LiDAR

The scanning angle error of light detection and ranging (LiDAR) degrades the imaging quality; therefore, accurate calibration of scanning angles is crucial for improving the system performance. However, there is a lack of research on the angle calibration methods for the novel prism-galvo scanner. To achieve accurate calibration of the prism-galvo scanner, a combined analytical- and optimization-based angle calibration method is proposed. For prism zero-position angle calibration, an analytical power-splitting model relating the splitting power ratio (SPR) to the prism scanning angle is established based on the dual-echo phenomenon generated when the emitted beam is split by the prism edge. For galvo reset-angle calibration, a point-cloud-flattening optimization method is proposed to calibrate the galvo reset angle, by minimizing horizontal plane point cloud inclination. A chessboard-based experiment was conducted to evaluate the angular displacement errors (ADEs) of the lab-built prism-galvo scanning LiDAR. Experimental results demonstrate that the vertical and horizontal ADEs are less than 1 and 0.2 mrad, respectively. The presented method provides a physically interpretable and convenient approach for the calibration of prism-galvo scanning LiDAR, enabling the generation of high-quality point cloud data for environmental perception.