Stimulated emission depletion microscopy on lithographic nanostructures

Stimulated emission, predicted by Albert Einstein in 1917, not only prepared the grounds for the invention of the laser, but also for a far-field fluorescence microscopy with diffraction-unlimited resolution. In stimulated emission depletion (STED) microscopy, stimulated emission is not used for light amplification but for a saturated quenching of the fluorescence emission. After demonstrating a five-fold improvement of the lateral (x and y) resolution over the diffraction barrier, we apply STED microscopy to nanostructures of stained PMMA. For the first time, periodic line structures of 80 nm width and 40 nm gaps are resolved with focused visible light.