In 1873, Ernst Abbe proposed an expression that described the resolution limit of a microscope, or in other words, how close two objects could be before it was impossible to tell whether there really were two objects, or just one slightly bigger object. This expression, termed the Abbe Diffraction Limit, does not just describe the limits of manufacturing technology, but is a fundamental property of nature; nomatter how advanced future technology becomes, the limit would always be true.

Abbe was a careful scientist, and made sure to state that the diffraction limit only applied in the case of linear optical phenomena (i.e. in which the effect or signal is a linear function of the optical intensity). In the case of nonlinear phenomena, the limit did not apply. Nevertheless, because almost all optical phenomena are linear, for a hundred years it was believed that there was no way to image below the diffraction limit.

This all changed when researchers such as Stefan Hell, Eric Betzig, Harald Hess, Xiowei Zhuang and Mats Gustafsson all developed different methods for overcoming the diffraction limit and imaging features substantially smaller than half the wavelength of light. These techniques can be broadly split into three categories: point-spread function engineering techniques such as Stimulated Emission Depletion (STED) and REversible Saturable Optical Linear Fluorescence Transitions (RESOLFT); localization techniques such as PhotoActivated Localization Microscopy (PALM), Fluroescence PhotoActivated Localization Microscopy (FPALM) and Stochastic Optical Reconstruction Microscopy (STORM); and frequency-domain techniques like Structured Illumination Microscopy (SIM).

Selective High-Throughtput STORM

Work in progress - this section will be updated as soon as it gets published!

High-speed 3D SIM

Work in progress - this section will be updated as soon as it gets published!