Keywords: 
• fluorescence microscopy imaging /
• super resolution /
• stimulated emission depletion

Abstract: Stimulated emission depletion (STED) is a kind of super resolution fluorescence microscopy imaging technology. It can break through the traditional optical diffraction limit, and make the far field optical resolution improved to less than 100 nm, which is widely used in biomedical field, and becomes one of the hotspots in optical imaging research. A STED microscope system based on ultra-continuous spectrum picoseconds pulsed white laser source was introduced, and super-resolution imaging was realized. The optimized results were discussed from the aspects of precise collimation, pulse delay and residual intensity of the STED light, therefore the best imaging effect was obtained. The experiments data of the about 25 nm diameter fluorescent microspheres imaging shows that the resolution of the system is about 60 nm, which is much higher than the diffraction limit. In addition, the system succeeds in realizing super resolution imaging of nuclear pore complexes, microtubules and microfilaments and a series of biological samples. Some obscure structures imaged in confocal microscopy can be legible in STED imaging.