Harvard University engineers have built a laser that could allow researchers to peer into cells with ultrahigh resolution — about 100 nanometers — and watch cellular events as they happen.

Gold bars focus laser light to a spot size equal to the gap between them.

By adding nano antennas to infrared lasers, the researchers have made it possible to focus the light much more tightly and could lead to imaging with at least 100 times greater resolution. Microscopes using the new lasers should be able to detect, for example, changes in individual proteins on the surfaces of cells.