Cited research: Opt. Lett. 35, 1245–1247 (2010)

Fluorescence microscopy has become an indispensable tool for cell biologists. But the light beams used to penetrate a sample are scattered by tissues, complicating efforts to image below a tissue's surface.

Now, Ivo Vellekoop and Christof Aegerter of the University of Zurich in Switzerland have developed a type of fluorescence microscopy that can see what lies beneath. They adjusted the properties of the incoming light so that it constructively interfered with light scattered by the intervening material. The result was a sharply focused beam that could detect fluorescent beads below a light-scattering zinc-oxide layer, with the same resolution as a conventional fluorescent microscope.