Hybrid phase-amplitude superoscillation element for nonscanning optical superresolution imaging.

In this paper, we report a nonscanning optical superresolution imaging method based on a hybrid phase-amplitude superoscillation element. Using the Chebyshev polynomials as a basis set on the superoscillation waveform, the optimal combination of these, representing the optimal focal -spot in the local field of view, is found by genetic algorithm. Our numerical calculations demonstrate that a subwavelength focal spot with a full width at half-maximum as small as 253 nm is realized, which has more than 30 times improvement in sidelobe suppression ratio, and crucially, a greatly extended needle with continuously shrunken focal spot is yielded, which allows a large imaging tolerance in the axial displacement of the object. We then present our simulated results of the superresolution imaging on sparse point objects and continuous objects, where the practicality and effectiveness of this method are analyzed and discussed in detail.