One of the most currently applied super-resolution method for imaging beyond the diffraction limit is stochastical optical reconstruction microscopy (dSTORM or GSD). With localization microscopy it is possible to achieve super-resolution images with a lateral resolution of down to 20 nm. However the z resolution of a widefield microscope was still limited to around several hundred nanometers.
With the latest development of a GSD 3D super-resolution platform, it is now possible to overcome this limit down to an axial resolution of 70 nm. The technology is based on an astigmatism approach using a manipulated PSF to localize the molecule in z. This following tutorial describes the basic principles of the 3D GSD technology.