Hell's group was interested in using this technique to cause stained cells and other biological structures to fluoresce in as tiny a spot as possible. so they could be imaged at very high resolution under the microscope. (His team has since done this to great effect: In 2009, they showed they could resolve features under the micro scope as small as 6 nm-just a few atoms across-using visible light, well under the Abbe diffraction barrier.)