High-accuracy and efficient method for calibrating spatial laser beam based on optimized PSD

The laser sensing technique with visual laser beam has been an increasing interest in large-scale 3D measurement. However, a major limitation has been the high-accuracy positioning of laser beam in 3D space. An efficient calibration method of spatial laser beam in large-scale measurement is proposed in this paper. A novel PSD-based laser detecting device is presented to accurately collect the laser beam data. The 3D coordinates of points on the laser beam can be transformed from the PSD coordinate system to the world coordinate system by the pre-calibrated reference points and spatial transformation analysis. Furthermore, the optimized method of PSD data processing is proposed to reduce the influence of ambient light on detecting laser point coordinates. Finally, the spatial posture of laser beam can be obtained by linear fitting from the high-accuracy acquired points. The calibration process is greatly simplified compared with the existing methods. The experimental results show that the average deviation between the obtained spatial points and the fitted line is less than 0.015 mm within 5 m. The proposed method is applied to non-orthogonal shafting theodolites, and the point measurement average error is less than 0.17 mm, and the distance measurement average error is less than 0.16 mm.