Polarization calibration method of ground-based polarization imaging system for low earth orbit space objects

For the polarization imaging system which was constructed in the adaptive optics system of ground-based telescope and imaged for low earth orbit space objects, a broadband polarization calibration method based on unpolarized standard star and onboard polarization state generator was proposed. This method, which contained two steps for polarization calibration based on nonlinear least-square fitting polarization calibration method, used the unpolarized standard stars as the light source and utilized the polarization state generator inserted in the first image plane of telescope system to modulate the polarization state of incident light. Then to verify the performance of this polarization calibration method, a simulation model based on coherent matrices and polarization ray tracing was constructed and corresponding simulation was carried out by Matlab. The simulation results show that this polarization calibration method can effectively decrease the influence of telescope polarization on the accuracy of polarization detection. And under the influence of random initial angle errors of polarization calibration elements within ±5°, the performance of this polarization calibration method can be affected tinily.