Practice question

STED achieves 20-70 nm lateral resolution through targeted depletion. Excitation spot is narrowed by overlaying doughnut-shaped STED laser that quenches peripheral fluorophores via stimulated emission, leaving emission from nanometer-scale center. Resolution scales inversely with STED beam intensity, breaking diffraction barrier without requiring stochastic blinking or molecular reconstruction. Originally developed by Stefan Hell, it uses organic dyes compatible with high-intensity depletion. STORM relies on photo-switching rather than depletion, while SIM uses Moiré and TEM uses electrons. STED's deterministic approach provides fast super-resolution suited for live-cell dynamics and synaptic studies.