New optical method bypasses light's limit by 100,000× to image atoms

Researchers at the University of Regensburg have developed a novel optical microscopy method that overcomes the long-standing diffraction limit of light, enabling imaging at scales nearly 100,000 times smaller than conventional light microscopes—down to about 0.1 nanometers, comparable to atomic spacing. This breakthrough was achieved by using a sharp metal tip placed extremely close to a sample’s surface, creating a gap smaller than an atom. When illuminated with a continuous-wave mid-infrared laser, light is squeezed into this tiny gap, enhancing resolution beyond the typical diffraction limit. Unexpectedly, as the tip approached even closer, the optical signal intensified dramatically, revealing atomic-scale features without requiring powerful ultrafast lasers. The key to this advancement lies in quantum electron tunneling: electrons move between the tip and the sample under the influence of the laser’s electric field, generating a weak electromagnetic signal known as near-field optical tunneling emission. By detecting this signal through intensity-based optical measurements, the researchers directly probed quantum