Super-resolution deep imaging with hollow Bessel beam STED microscopy

Abstract

Stimulated emission depletion (STED) microscopy has become a powerful imaging and localized excitation method, breaking the diffraction barrier for improved spatial resolution in cellular imaging, lithography, etc. Because of specimen-induced aberrations and scattering distortion, it is a great challenge for STED to maintain consistent lateral resolution deep inside specimens. Here we report on deep imaging STED microscopy using a Gaussian beam for excitation and a hollow Bessel beam for depletion (GB-STED). The proposed scheme shows an improved imaging depth of up to about 155 μm in a solid agarose sample, 115 μm in polydimethylsiloxane, and 100 μm in a phantom of gray matter in brain tissue with consistent super resolution, while standard STED microscopy shows a significantly reduced lateral resolution at the same imaging depth. The results indicate the excellent imaging penetration capability of GB-STED, paving the way for deep tissue super-resolution imaging and three-dimensional precise laser fabrication. A STED based super resolution deep-imaging modality is reported by utilizing a hollow Bessel beam as depletion and a Gaussian beam as excitation beam. Comparing to the conventional STED microscope, an improvement on lateral resolution at the depth up to ~150μm inside the specimen is experimentally demonstrated, with ~100μm depth inside biological phantom. The proposed scheme can find promising applications for deep tissue imaging, laser nano-fabrication, and dense optical storage with super-resolution.