为保障偏振扫描仪长期在轨的偏振测量精度，研究了偏振扫描仪的星上偏振定标原理与方法。首先，针对分孔径和分振幅的技术特点，结合实际的误差来源，理论推导了系统探测矩阵；其次，根据仪器参数，利用已知偏振态的线偏振光和非偏振光，推导了星上偏振定标方程；然后，设计了用于星上偏振定标的线偏振定标器和非偏振定标器；最后，提出了利用已知偏振度的太阳漫射板辐射定标数据来校正偏振扫描仪的低偏振度测量精度和稳定性。所提出的星上偏振定标方法具有高精度、高频次、高效率等特点，可满足长期在轨偏振测量精度为0.005的应用需求。

In order to guarantee the long-term on-orbit polarimetric measurement accuracy of scanning polarimeter, the onboard calibration mechanism and method of scanning polarimeter are studied. First, the system detection matrix is derived according to the technical characteristics of aperture-division and amplitude-division and with the consideration of practical error sources. Second, the onboard polarimetric calibration equation is deduced according to the instrument parameters and by use of the linearly polarized light and the non-polarized light with the known polarization states. Third, the linear polarization and non-polarization calibrators are designed for the onboard polarimetric calibration. Finally, the radiometric calibration data with the known polarization degree from the onboard solar diffuser is proposed to correct the low polarimetric measurement accuracy and stability. The proposed onboard polarimetric calibration method possesses the characteristics of high precision, high frequency, high efficiency, and so on, which can satisfy the application requirement that the long-term on-orbit polarimetric measurement accuracy is 0.005.