Far-field super-oscillation imaging based on the super-oscillation elements and PSF feature extraction algorithm.

Suffering from the limited number aperture, a resolution higher than 0.5λ cannot be obtained in conventional far-field optical imaging systems. Recently, research of the optical super-oscillation lens (SOL) has been demonstrated to realize sub-diffractive focusing in both theory and practice successfully. Nevertheless, these systems usually have characteristics of a localized field of view and low-intensity focal spot surrounded by huge sidelobes, which profoundly restricts their application for super-resolution imaging. In this paper, we artificially segment the SOL into two simple-fabrication portions to generate the super-oscillation optical field and realize off-axis far-field imaging. Meanwhile, the point spread function (PSF) feature extraction algorithm is proposed to break the limitation of low core intensity of the PSF and then effectively extract the sub-diffractive structure annihilated by huge sidelobes. Simulations demonstrate its feasibility and reliability in sub-diffraction information recovery, and targets with a resolution of 250 nm are well recovered in the super-oscillation area.