Fig. 1. The imaging picture obtained by the POL method on the existing experimental device

Fig. 2. Side-view imaging of polarization-maintaining fiber in matching liquid

Fig. 3. Schematic of polarization-maintaining fiber at polarization axis of 90°

Fig. 4. When rotating forward 110°，part of the polarization-maintaining fiber images captured by the CCD and normalized data

Fig. 5. When rotating to special angles，part of the PM fiber images captured by the CCD

Fig. 6. Relative distance of diffraction fringes at different angles

Fig. 7. The geometric relationship between the angle of the polarization axis θ and d3

Fig. 8. Operation flow chart of alignment polarization axis

Fig. 9. Three cross-sectional schematic diagrams when the stress zone distribution of PMFs are asymmetric

Fig. 10. The simulated relationship between eigenvalues and polarization axis angle when radius of panda eyes are inconsistent

Fig. 11. Detected normal characteristic of the tested data with the polarization angle θ=110°