High-Precision Calibration Algorithm for Large Field-of-View Polarization-Modulated 3D Imaging

To improve the performance of 3D LiDAR imaging and reduce the negative effects of interference fringes on polarization modulation of electro-optical crystals, a calibration algorithm based on polarization modulation principle was proposed in this letter. The reflect light of targets is received by the system, modulated by an electro-optical crystal, then divided into two complementary light beams after passing through polarization beam splitting (PBS), and finally received by two electron-multiplying CCDs (EMCCDs). The depth map and intensity image can be reconstructed by adding the two modulated images. However, the cone interference effect of the electro-optic crystal affects the modulation of the polarized light, resulting in the distance error. By fitting the curve of grayscale ratio of each pixel acquired by two EMCCDs with the changing of voltage, the actual range can be calculated by the light intensity corresponding to the accurate polarization modulation. Ultimately, we found that the algorithm showed outstanding performance on high-precision imaging with an error less than 0.1m in a wide field-of-view of 0.9 mrad.