Distortion correction strategy in off-axis metasurface holography

Metasurface holography has gained significant attention for its ability to miniaturize optical systems without compromising their performance, which offers new possibilities for compact and efficient optical designs. However, the presence of off-axis imaging effects and discretization errors in current metasurface holography processes leads to image distortions during holographic reconstruction, which limits the development of off-axis metasurface holography. In this study, distortion correction is implemented by applying inverse distortion to the target image through image processing. During the image processing, each pixel coordinate is translated relative to the image center and converted into polar coordinates. The coordinates are processed using a distortion magnitude parameter (DMP) defined within a cubic distortion term. Finally, the modified polar coordinates are mapped back to the Cartesian coordinate system. The variations in imaging performance under different DMPs were analyzed. By quantitatively analyzing imaging quality using the structure similarity index measure (SSIM), peak signal-to-noise ratio (PSNR), and intensity correlation coefficient, the results showed that as the DMP increased, distortion gradually decreased, and imaging quality improved significantly. The maximum improvements in SSIM, PSNR, and intensity correlation coefficient were 0.0864, 1.83 dB, and 0.0979, respectively. By selecting DMP ranging from 0 to 3.2, distortion can be effectively corrected, while excessive modulation introduces negative distortion, adversely affecting imaging quality. Furthermore, experiments verify the simulation results, demonstrating consistent performance and confirming that metasurface holography can achieve effective distortion correction. This study provides strong support for expanding the effective range of metasurface holographic imaging and enhancing the performance of off-axis metasurface holography.