John Hall is one of the "fathers" of the optical frequency comb

Half of the prize goes to John Hall of Colorado University and Theodor H�nsch of Germany's Max Planck Institute.

The laser-based spectroscopy they pioneered allows the colour of light from atoms and molecules to be determined with exceptional precision.

The other half goes to Roy Glauber of Harvard University for applying modern quantum principles to laser optics.

The Nobel Prizes - which also cover chemistry, medicine, literature, peace and economics - are valued at 10m Swedish Kronor (�728,000; US$1.3m).

Laureates also receive a medal and a diploma.

Very short

Profesor Glauber's work goes back to the 1960s, when he developed theories that explained the extraordinary properties of laser light in terms of modern quantum physics - which is governed by probabilities.

This enabled him to describe the fundamental differences between hot sources of light such as light bulbs, which produce a mixture of frequencies and phases, and lasers, which give a specific frequency and phase.

Celebration in Germany for Theodor H�nsch

Professor Glauber published his breakthrough work in 1963 and it changed the course of his science; the Nobel committee marks it as the start of the field of quantum optics.

Decades later, building on Glauber's work, Hall and H�nsch developed a high-precision technique called the optical frequency comb.

This is generated by a laser specially designed to produce a series of extremely short - a few billionths of a second - equally spaced pulses of light.

It allowed Hall and H�nsch to measure the colour emitted or absorbed by atoms and molecules, and opened a new window for precision instrumentation.

Their laser technology makes it possible to track frequencies with an accuracy of fifteen digits.

Matter probe

With such fine scales, scientists are now producing super clocks that would lose only one second in the age of the Universe.

They are even running the rule over the constants of nature to see if they change over time.

Roy Glauber explained lasers using quantum theory

Further benefits are expected in satellite navigation and timing, quantum computing and cryptography, and holography - any areas that depend on lasers and precision.

Professor H�nsch is even using the technique to see how antimatter - the stuff of science fiction rocket engines - differs from normal matter.

Dr Hall is currently a fellow and senior research associate at Jila, a joint institute of the University of Colorado at Boulder and the National Institute of Standards and Technology (Nist).

Professor H�nsch is the director of the Max Planck Institute for Quantum Optics. Roy Glauber is the Mallinckrodt Professor of Physics at Harvard University.