STOCKHOLM, Oct. 8 -- U.S. scientist Eric Betzig, William E. Moerner and German scientist Stefan W. Hell won this year's Nobel Prize in Chemistry, the Royal Swedish Academy of Sciences announced on Wednesday.

The academy said the award was given to the three "for the development of super-resolved fluorescence microscopy."

Nobel Laureate Hell said in an on-site telephone interview that the discovery is "important for understanding physiology and disease," and that he had been quite "confident" in his instinct and kept on the development. Hell currently works at the German Cancer Research Center.

Betzig and Moerner are from U.S. Howard Hughes Medical Institute and Stanford University, respectively.

According to the statement from the Royal Swedish Academy of Sciences, "helped by fluorescent molecules," this year's laureate has" brought optical microscopy into the nanodimension," overcoming a long time presumed limitation of optical microscopy that it would never obtain a better resolution than half the wavelength of light.

In what has become known as nanoscopy, scientists visualize the pathways of individual molecules inside living cells. They can see how molecules create synapses between nerve cells in the brain; they can track proteins involved in Parkinson's, Alzheimer's and Huntington's diseases as they aggregate; they can follow individual proteins in fertilized eggs as these divide into embryos, according to the statement.

"Today, nanoscopy is used world-wide and new knowledge of greatest benefit to mankind is produced on a daily basis," the statement said.

In 1873, the microscopist Ernst Abbe stipulated a physical limit for the maximum resolution of traditional optical microscopy: it could never become better than 0.2 micrometres, according to the statement.

However, Stefan Hell developed in 2000 a revolutionized principle which "enables the method stimulated emission depletion (STED) microscopy."

"Two laser beams are utilized; one stimulates fluorescent molecules to glow, another cancels out all fluorescence except for that in a nanometre-sized volume. Scanning over the sample, nanometre for nanometre, yields an image with a resolution better than Abbe's stipulated limit," according to the statement.

Eric Betzig and William Moerner, working separately, laid the foundation for the second method, single-molecule microscopy.

"The method relies upon the possibility to turn the fluorescence of individual molecules on and off. Scientists image the same area multiple times, letting just a few interspersed molecules glow each time. Superimposing these images yields a dense super-image resolved at the nanolevel," according to the statement.

Today, nanoscopy is used world-wide and new knowledge of greatest benefit to mankind is produced on a daily basis.

Eric Betzig, U.S. citizen, was born in 1960. He got Ph.D. in 1988 from Cornell University. He is now Group Leader at Janelia Farm Research Campus, Howard Hughes Medical Institute.

Stefan W. Hell, German citizen, was born in 1962. He got his Ph.D. in 1990 from the University of Heidelberg, Germany. He is now Director at the Max Planck Institute for Biophysical Chemistry, and Division head at the German Cancer Research Center in Germany.

William E. Moerner, U.S. citizen, was born in 1953. He got his Ph.D. in 1982 from Cornell University. He is now professor at Stanford University.

The three laureates will equally share the prize amount of 8 million SEK (about 1.12 million U.S. dollars).