Four-directional linear polarization ghost imaging based on multi-focal metalens

We propose a method that combines a multi-focal metalens with polarization computational ghost imaging (PCGI). Specifically, this multi-focal metalens integrates the functions of beam splitting, focusing, and polarization analysis while increasing energy utilization efficiency by 17%, and the metalens achieves an extinction ratio of 113.5:1. Notably, PCGI integrated with this metalens enables aberration-free imaging, and the lens's multifunctional design further enhances PCGI efficiency, reducing its acquisition time by 75% compared with time-sharing acquisition systems. Within the same acquisition time as conventional computational ghost imaging (CGI), the proposed system simultaneously acquires four linear polarization components and the derived non-polarized intensity, degree of linear polarization (DOLP), and angle of polarization (AOP). To evaluate the method's performance, we investigated the effects of different patterns, sampling ratios, and resolutions on PCGI. The results indicate that PCGI retains high reconstruction quality even at low sampling ratios and low resolutions. Furthermore, the proposed method exhibits strong generalization performance, as the structural similarity index metric (SSIM) values of both the reconstructed non-polarized intensity images and AOP images remain above 0.9 across various scenarios.