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Its ability to access higher frequencies means SIM breaks the diffraction limit and doubles the resolution of light microscopy. However, SIM is slower than either iSIM or Airyscan and it is not confocal, so is not ideal for thick specimens with lots of out of focus light. For SIM at the LMCB, use the Carl Zeiss Elyra PS.1.
Stimulated Emission Depletion (STED)
In Stimulated Emission Depletion a (usually) doughnut-shaped depletion laser is used to stimulate re-emission of excitation photons from a region around the periphery of the excitation spot of a laser scanning microscope, effectively making the excitation spot smaller and allowing the microscope to scan at a higher resolution. Resolution increases with depletion laser power and very high laser powers are needed. Time-gating of the detectors improves resolution further by eliminating the small amount of fluorescence emission in the region of the doughnut, which makes it possible to reduce the depletion laser power.
