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The Maser

Charles Hard Townes (born 1915) built the first Maser, which stands for Microwave Amplification by Stimulated Emission, in 1953. In developing the Maser, Townes built on a brilliant and original idea. He realized that the molecules of certain substances might be coaxed into producing microwaves -- not fast-cooking ovens, but very short electromagnetic waves.

He knew that if molecules were excited, then allowed to return to their original state, radiation would be emitted. With this principle, a kind of domino effect of waves could be made to create a highly amplified beam of radiation.

The Maser was a big hit, being used to amplify radio signals and as an ultrasensitive detector for space research. But in 1957, not satisfied to simply enjoy his success, Townes kept thinking about how the Maser worked, and decided there was no reason why it shouldn't work equally well with light beams. Three years later, Light Amplification by Stimulated Emission (the Laser) was born.

Laser instruments are now so widely used that they have become almost commonplace. In scientific research, they have provided new insights into our understanding of the nature of light, while in industry they have become important in communications systems, precision welding, drilling of previously heat-resistant materials and measuring with a high degree of accuracy.

Military applications include navigation and weapon targeting systems. And in medicine, lasers have enabled groundbreaking treatments of cancer, where they are used to destroy diseased cells. They are also used in sophisticated eye surgery procedures, including welding detached retinas.

[July 1996]

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