Super-resolution microscopy achieved by metalens-generated longitudinal polarization illumination

The focusing of radially polarized light creates a longitudinally polarized focal spot with a substantially smaller size than those generated by linear or circular polarization, offering an effective route to improve the lateral resolution of confocal microscopy. In this work, we report a super-resolution microscopy approach that utilizes longitudinally polarized illumination generated by a metalens, which can convert linearly polarized-light into radially-polarized light and focused the radially-polarized light into longitudinally polarized light for illumination. The generated longitudinally focal spot has a size of 0.428 λ. Notably, the proposed microscopy system exhibits edge detection capability. Experimental results demonstrate that the microscope can resolve grating structures with a linewidth of 0.316 λ and a pitch of 0.632 λ. This label-free method shows significant potential for probing sub-wavelength structures and provides a powerful tool for both biomedical and non-biomedical applications.