Laser microscope sees even smaller

From a setting that sounds like something which inspired Primer, two ex-Bell scientists have developed a laser microscope capable of resolving things at the molecular scale even better than ever before.

Chemical and Engineering News writes:

A new fluorescence technique called PALM resolves signals from individual tagged molecules (red dots), yielding optical images with nearly molecular-scale resolution (second from top). PALM and EM also can be combined into more telling composites (second from bottom).

PALM does this by using overlapping laser beams whereby the first beam illuminates the material under study and the second selectively interferes with the first so that very specific areas are lit up.

By tuning short pulses of the doughnut to the tag's fluorescence wavelength, the tags in the annular illumination zone are stimulated to go dark, leaving a doughnut-hole region of excitation. The more the power in the doughnut zone is cranked up, the narrower the hole becomes, Hell says. "This renders continually sharper spots with the size of a molecule being the conceptual limit,"