Charles Townes is generally considered the American inventor of the maser (an acronym for microwave amplification by the stimulated emission of radiation), an honor he shares with two Russian scientists, Aleksandr Prokhorov and Nikolai Basov. The microwave theories he introduced and pursued throughout the 1960s paved the way for such advances as the modern laser.
The son of a South Carolina attorney, Townes studied modern languages and physics at Furman University in his home town of Greenville, S.C., graduating summa cum laude in 1935. He obtained his master's degree in one year at Duke University and his Ph.D. at the California Institute of Technology in 1939. After completing his education, Townes worked for Bell Telephone Laboratories on the design of radar bombing systems, in support of the U.S. effort in World War II. It was during these years at Bell that Townes' interest in microwave technology bloomed; in 1948, when he was asked to join the physics department at Columbia University, he gladly accepted.
Townes concentrated his research on microwave spectroscopy, the study of the basic structure of matter. Though some advancement was made, it rapidly became clear that an oscillator was needed which could produce radiation of very short wavelengths. Unfortunately, Townes also knew that existing technology was incapable of constructing a device small enough to produce such radiation. In 1951, while sitting on a park bench in Washington, D.C., it struck Townes that an extremely small device might be found if he concentrated not upon electrical circuits but rather upon molecules. Since molecules had very specific rates of vibration, and microwaves had very specific wavelengths, molecular vibrations, if somehow converted into radiation, would be equivalent to the essential short-wavelength microwaves.
Frantically writing on the back of an envelope, Townes calculated that it was possible to produce microwaves if ammonia molecules were " excited" by pumping energy into them and then were stimulated to emit that energy in a controlled, or coherent, pattern. These theories were by no means new; coherence had been studied for years, and stimulated emission was first discussed in depth in Albert Einstein's (1879-1955) theory of relativity. But the application of those two theories for microwaves was unprecedented.
By 1953, Townes, A. L. Schawlow, and Townes' students at Columbia had finally constructed a working ammonia maser. One of its first applications was in timekeeping, for the steady, undeviating frequency of the microwaves was far more accurate than any timepiece prior, and was dubbed the " atomic clock." But Townes and others felt that a more versatile device could be developed if the gaseous ammonia were replaced with a solid crystal.
The resulting solid-state masers were instrumental in the field of radio astronomy, where they were used to amplify very weak signals from distant radio sources. The faint reflected signals from the Echo I satellite were successfully amplified in this manner, as well as radar scannings of the planet Venus.
Perhaps the most important advance in maser technology began in 1957, when Townes and his brother-in-law began speculating on the possibility of creating an "optical maser," delivering infrared or visible light rather than microwaves. Such light would be coherent; rather than spreading out like normal light, the maser light would maintain a tight beam almost indefinitely. Such a beam could also focus its energy to an extremely fine point, making it a cutting tool unsurpassed in power and precision.
In 1960 the first ruby maser, or laser (light amplification by the stimulated emission of radiation), was constructed, paving the way for a technology that would revolutionize engineering, medicine, and communications. For these advances Townes was awarded the 1964 Nobel Prize for physics, sharing it with Prokhorov and Basov (who worked independently in Russia).
In 1959, Townes took a two year leave of absence from Columbia to serve as vice-president and director of research of the Institute for Defense Analyses in Washington, D.C. In 1961, he became provost and professor of physics at the Massachusetts Institute of Technology. He was elected to the National Academy of Sciences in 1956.
This is the complete article, containing 664 words
(approx. 2 pages at 300 words per page).
