All by itself, however, this technique isn't quite enough to get us meta-atoms small enough to interact with light. The limitation is the Abbe diffraction barrier-a characteristic of microscope optics that limits the spatial resolution of a lens and thus how closely you can put two adjacent features or lines. For an 800-nm laser- which works well with common photoresists—and for high-end microscope lenses, you're limited to a lateral distance of about 300 nm because of Abbe.