LAUSR

Abstract A novel Sagnac imaging polarization spectrometer based on a modified Sagnac interferometer (MSI) with a moving wedge prism is proposed in this paper, and it is a framing instrument with the advantages of miniaturization, variable optical path difference (OPD) and large field of view. The construction and split-beam principle of the system are described detailedly, and the exact expressions of the OPD and lateral displacement changing with different parameters are obtained. The variations of the OPD and lateral displacement as a function of the wedge angle and moving displacement are simulated, and the influences of the wedge angle on the OPD and lateral displacement are very small, while most effects come from the moving displacement. In order to obtain a larger OPD and lateral displacement, the wedge angle is controlled in a range of [ 45 ° , 50 ° ] . In addition, the influences of the dispersion effect of the glass plate on the OPD and lateral displacement are analyzed and discussed, and the suitable material choice for the MSI can reduce the influence of the dispersion effect on the OPD, which also allows the system construction spanning the spectral range of [480 nm, 960 nm]. In comparison with the conventional Sagnac interferometer with a large optical path difference (LOPDSI), the spectral resolution of the MSI can be made much higher if choosing suitable parameters. This study provides a theoretical and practical guidance for the design and engineering of the Sagnac imaging polarization spectrometer.