STED Nanoscopy: Beating the Diffraction Limit

Stimulated Emission Depletion (STED) microscopy is one of the techniques behind modern super-resolution "nanoscopy" — imaging fluorescent structures far below the ~200 nm optical diffraction limit that ordinary light microscopes cannot cross. This simulator renders a 3D fluorescent sample and a scanning excitation spot overlaid with a donut-shaped depletion beam: as you raise the depletion beam's power, the region left free to fluoresce shrinks according to d_STED = d₀/√(1 + I/I_sat), and a live scan-profile graph shows two nearby point emitters going from one blurred blob to two clearly resolved peaks — the real physical mechanism, not a post-processing trick, that let Stefan Hell share the 2014 Nobel Prize in Chemistry.