Numerical super-oscillatory filtering for sub-diffraction optical imaging

Super-oscillatory (SO) imaging is a far-field imaging technique to super-resolve unlabeled objects. Previous theoretical and simulation-based studies have shown attractive possibilities to simplify the SO imaging configuration by implementing SO imaging numerically. However, numerical SO imaging has not yet been experimentally demonstrated in real optical systems. In this work, we reconstruct the complex field of a diffraction-limited (DL) image with the phase-shifting interferometry (PSI) technique, enabling the application of numerically designed SO filters in the Fourier domain. Experimental results at a wavelength of 632.8 nm validate the proposed method, showing improved resolution and image fidelity. Quantitatively, the full-width-at-half-maximum (FWHM) is reduced by 42% and the structural similarity index (SSIM) is enhanced from 0.19 to 0.29.