3D raster image correlation spectroscopy based on ultra-continuous laser STED system

Abstract

Stimulated emission depletion is a kind of super resolution imaging technology widely used in biomedical fields, which improves far-field optical resolution to less than 100nm. In this paper, 3D raster image correlation spectroscopy which is based on ultra-continuous laser STED system is introduced. The optimized system will be discussed from the aspects of precise collinear alignment, pulse time delay and central intensity of STED spot. Experiments show that the resolution is about 60nm. The laser reduces the effects of photobleaching and dark state. Moreover, the combination of STED and 3D raster image correlation spectroscopy can extend applications of STED into molecular dynamics. Simplified but rigorous fitting equations were rewritten according to the benefits from the laser. Diffusion coefficients of particles in different situations are obtained.