From MIT Technology Review: Korean researchers have created nanoscale lenses with superhigh resolution using a novel self-assembly method. So far, they’ve demonstrated that the tiny lenses can be used for ultraviolet lithography, for imaging objects too tiny for conventional lenses, and for capturing individual photons from a light-emitting nanostructure called a quantum dot.
The new lenses, developed by researchers at the Pohang University of Science and Technology in Korea, overcome the diffraction limit because of their size. The lenses are flat on one side and spherical on the other and range in diameter from about 50 nanometers to three micrometers.
Kim’s team makes the tiny spherical lenses by evaporating a solution containing cup-shaped organic molecules. First, the molecules, which are based on carbon rings, are dissolved in an organic solvent; then water is added, and the solution is allowed to slowly evaporate. During the evaporation process, the organic molecules form crystalline nanotubes that form the lenses. By changing the temperature and the evaporation rate, Kim says, it is possible to control the lenses’ ultimate size. Once the lenses have formed, they’re stable.