From the article: Researchers have come up with a new idea for a light microscope. They placed between the light source and the object a lens made from a slab of a crystalline substance called gallium phosphide. This design drastically reduces the theoretical minimum size of a visible object. However, for complex technical reasons, no one has ever managed to get close to this theoretical minimum with a standard lens made of gallium phosphide. So the researchers took a different tack. They started by etching the lens with sulphuric acid, producing a frosted surface that, far from focusing the light, scattered it randomly in all directions. They then used a computer to design an incoming light wave that, when scattered by the lens, would focus to a point. This process of randomize and reconstruct produces a tighter focus than simply focusing the light with a traditional lens.
Very clever.
