Label-free super-resolution microscopy based on non-diffraction superoscillation beam (NDSB) illumination
Yi Zhou, Kun Zhang, Jinlong Wang, Zhengguo Shang, Gaofeng Liang, Zhihai Zhang, Zhongquan Wen, Yufei Liu, Gang Chen
Abstract
Due to the diffraction properties of light waves, optical microscopy suffers from a fundamentally limited resolution of ∼λ/2, where λ relates to the illumination wavelength. Though near-field methods capturing the evanescent waves can reach a resolution of several nanometers, the extremely short working distance has restrained their applications. Typical far-field super-resolution microscopies using fluorescence to monitor the labelled samples also have their limitations in applications because of their phototoxicity and complex preprocessing. We hereby proposed a label-free super-resolution microscopy based on non-diffraction superoscillation beam (NDSB) illumination. We developed a transmission-mode confocal optical microscopy and experimentally demonstrated an imaging resolution of 0.285 λ at the illumination wavelength of 632.8 nm. As NDSB owns the capabilities of self-healing and deep penetration in dense media, we could clearly visualize the fine complex structures while NDSB illuminated from the backside of a 175-µm-thick glass substrate. As a result of NDSB's excellent penetration and superoscillatory transverse size, the 3D super-resolution capability of the proposed microscopy was experimentally verified. Owing to the advantages of label-free imaging, far field, super resolution, self-healing behaviour and deep penetration, we believe the proposed NDSB microscopy bears the potential to become a promising tool for 3D super-resolution visualization in both biological and nonbiological samples.