Calibration and region extraction of polarization sensor for navigation

Polarization navigation is an autonomous navigation method that relies on stable polarization patterns in the sky. The polarization sensor for navigation is composed of a CMOS image sensor (CIS) and four-direction metal nanograting. The optical conversion deviation of the CIS and the transmittance deviation of metal nanograting are the main factors affecting the angle measurement accuracy of the polarization sensor. A full-parameter calibration method that can accurately calculate the performance parameters in the Mueller matrix of all pixels is proposed. To reduce the error of the sensor, a mode-based region extraction algorithm that can extract the effective region of the sensor according to the statistical law of these performance parameters is proposed. The experimental results demonstrate that the proposed algorithm can effectively improve the angle measurement accuracy of the sensor. Compared with the single-parameter calibration and the region selection method based on the light intensity graph, the proposed method reduces the angle measurement error by 27.89% and significantly improves the robustness.