Super-Resolution Microscopy: A Brief History and New Avenues

This chapter starts with a brief historical overview of both conceptual and commercial developments and highlights important parameters for imaging successfully with a particular super-resolution modality. Early super-resolution microscopy developments initially addressed the inferior axial resolution in far-field epifluorescence microscopy to achieve close to isotropic three-dimensional resolution by standing wave illumination using opposing objectives in confocal or widefield. Moreover, both SMLM and STED employ non-linear excitation/detection to become diffraction-unlimited which comes at the price of undercounting fluorescent signals/molecules in some areas of the sample while overestimating them in others. In contrast, in linear SIM relative intensities between features with fewer or higher labeling densities are retained, allowing valid intensity quantifications. Finally, the chapter discusses the importance of reproducibility and quality control and the significance of open-source tools in microscopy. The sharing of data and resources has the immense advantage of enabling other researchers to reproduce the results or even recreate entire experiments.