Analysis of the retarders’ errors in the channeled spectropolarimeters

Channeled spectropolarimetry (CS) system is an attractive scheme with compact structure, which can acquire full spectrally resolved Stokes parameters without any internal moving or electrically controllable parts. For the CS system, retarders are the key components to extract the spectral polarization information of the targets. However, there always exist non-negligible errors brought by the retarders which would severely damage the measurement accuracy. In this paper, the effects of the retardance errors and orientation errors of the retarders on the measurement accuracy of three typical CS systems, including the dual high-order retarders system (DHRS), the single high-order retarder system (SHRS), and the linear spectropolarimetric system (LSPS), are theoretically derived and analyzed. A numerical simulation is then performed for verification. The analysis and simulation results show that the SHRS and DHRS are less sensitive to the retarders’ errors than the LSPS. Although the LSPS is only used for measurement of the linear polarization state, the measurement accuracy is affected by the circular polarization state of the input light.