THE diffraction limit鈥攁 fundamental barrier in light
microscopy鈥攈as been broken, paving the way for high-resolution imaging of
live cells, say Stefan Hell and colleagues at the Max Planck Institute for
Biophysical Chemistry in G枚ttingen, Germany.
The resolution of a fluorescent light microscope depends on the size of the
spot it produces in the material being viewed: the smaller the spot, the better
the resolution. So Hell鈥檚 team first created a spot using a green laser. Then,
using a red laser, they 鈥渟witched off鈥� the fluorescence at the edges, making the
green spot much smaller (Proceedings of the National Academy of
Sciences, vol 97, p 8206). 鈥淲e open up a window in resolution that
corresponds to current problems in biology,鈥� says team member Thomas Klar.