Charles Hard Townes


Charles Hard Townes
(1915)

American physicist, joint winner with the Soviet physicists Aleksandr M. Prokhorov and Nikolay G. Basov of the Nobel Prize for Physics in 1964 for his role in the invention of the maser and the laser.
Charles H. Townes played the major role in the development of the laser, one of science's greatest accomplishments. Townes finished Greenville High School at 15. He graduated summa cum laude from Furman University, in 1935, with degrees in physics and modern languages. He took an active interest in the university's museum. Townes did graduate work at Duke University. In 1939, he earned his doctorate in physics from California Institute of Technology.

The many pictures and displays in the Charles Townes Center - Commemorative Gallery detail the rich and productive life of one of South Carolina's leading scientist.

Charles Townes married Francis H. Brown in 1941 while he as a research physicist at Bell Laboratories. In the early 1950s, he was a professor of physics at Columbia University and was doing the spectroscopy research that would lead to the invention of the maser. In 1959, while still at Columbia University, he was awarded the patent for the maser and in 1960, with Arthur Schawlow, the first laser patent. A leading research scientist, Townes, was also a dynamic teacher. Many of his students have earned acclaim in physics research.

In the 1960s, while at the Massachusetts Institute of Technology, Townes, along with his colleague Ali Javan, worked with experimental equipment that tested the theory of relativity using rotating lasers. Before going to MIT, Townes, spent two years in Washington as director or research at the Institute for Defense Analyses. In the mid-1960s, Townes served as a member of the President's Science Advisory Committee, during the Lyndon Johnson administration. Townes has served on presidential advisory committees since the late 1950s. In 1967 Townes became a professor of physics at the University of California, Berkeley.

In 1960, many people were surprised by the invention of a way to generate a new form of light energy. Not surprised was Charles Townes and some of his colleagues in physics. This breakthrough was the culmination of more than a decade of intense research in maser and laser technology. It would change the sciences of optics and electronics and have a major impact on everyday life. It was the beginning of the Laser Age.

Early Microwave Study
Microwaves are short radio waves. By the late 1930s, systems using vacuum tubes could produce microwaves as short as a few millimeters. In the 1940s, while doing applied research for the military at Bell Laboratories, Charles Townes studied microwave radiation systems for radar and spectroscopy. Foreseeing its value for both science and technology, he carried out research on the interaction between microwaves and matter. He knew this information would give a better understanding of molecules and atoms and how their characteristics could be used to control radiation.

At the time, microwave technology was based mainly on systems and devices developed from the work in the early 1900s of Ernest Alexanderson of General Electric, Lee de Forest of New York, and Alexander Fleming of London.

Strong microwave radiation of short wavelengths was important in the development of reliable radar detection systems and electronic bomb sights. Shorter wavelengths allowed radar beams to show the shapes of objects more distinctly. A radar system Townes helped develop was installed in B-32 bombers near the end of World War II.

Some of the basic microwave devices of the 1940s included: the Klystron Oscillator, invented by Sigurd and Russell Varian in 1939, the klystron oscillator was a vacuum tube used to produce microwave radiation for radar and spectroscopy; the Microwave Wave Guide, used to channel the microwave radiation to desired area or instruments; and, the Diode Detector. Diodes, devices which control the flow of electricity, are used in instruments for detecting, measuring, and studying microwave radiation.

The Maser and the Laser Discoveries
Townes and other scientists wanted to obtain stronger radiation with even shorter wavelengths using sources other than vacuum tubes. In 1916 Albert Einstein had shown theoretically that atoms stimulated by radiation could emit, as well as absorb, radiation.

In 1951 Townes showed how useful radio waves only a centimeter long could be obtained form ammonia molecules. By 1954 he and two associates at Columbia University were operating a system called the MASER, for Microwave Amplification by the Stimulated Emission of Radiation.

Masers were soon put to practical use in many instruments: for example, in a time-measuring device called the "atomic clock" and in extremely sensitive devices for detecting and measuring radiation.

On display is a focuser from one of Townes' earlier maser set-ups. All gases contain some high-energy molecules. This device used a static electrical charge to discard low-energy molecules of ammonia gas and to focus, or concentrate, the high-energy molecules, causing them to enter the opening of the resonant cavity. As molecules inside the cavity return to a lower energy level, they release microwave radiation. This radiation, reflecting inside the cavity, stimulates additional molecules to radiate energy. This process amplifies, or intensifies, the microwave radiation, which is then emitted.

Other scientists developed masers based on Townes' research and proposals. Nicholaas Bloembergen, at Harvard, provided an idea for an effective solid-state maser. A common version used a ruby crystal to amplify microwaves. Crystal atoms are raised to a higher energy level by external microwave radiation. As the atoms return to a lower energy level, they emit microwaves. The use of this ruby crystal then makes yet more atoms emit radiation. Man-made ruby is cheaper than ruby formed in nature and can be made to specifications. The museum has on display a piece of man-made ruby, or boule, from Townes' supply of the 1950s. Smaller pieces could be cut form it to make maser crystals.

Dr. Theodore Maiman and an assistant, Dr. Irnee D'Haenens, working at Hughes Research Laboratories in 1960, were the first to demonstrate laser emission using a ruby system. In 1957, Schawlow had been the first to suggest using a parallel optical mirror system to make the light intense enough to become a beam. he had pulsed ruby laser operating within days of the Maiman announcement. In 1960 at Bell Labs, Ali Javan, William Bennett, and Donald Herriott, constructed the first laser using a gas lasing medium. Townes chose the name quantum electronics to describe the new field of study associated with the maser.

Documents on display at this exhibit show Townes' notes containing the first reference to a system for laser emission. He called it an optical maser. In Gordon Gould's notes, we see the first written use of the term laser. Members of Townes' research group had already used similar terms, including irasers, for infrared amplification by stimulated emission of radiation, and rasers, for devices using radio waves. At the time, Townes and Gould were both affiliated with Columbia University.

The first laser patent, also on display, was issued to Townes and Schawlow in 1960. Townes was at Columbia University; Schawlow was working for Bell Labs. Townes was the first living member inducted into the United States Patent Office's Inventors' Hall of Fame.

In this exhibit is a replica of the first working laser. A blinding flash from a xenon lamp raises the chromium atoms in the ruby crystal to a higher energy level. Photons, the tiniest units of light, are released by the atoms. They reflect back and forth in the ruby crystal, which, with its polished and silvered ends, acts as a resonant cavity. The reflecting photons stimulate additional atoms to emit radiation. The emitted light is coherent, moving on the same frequency, and monochromatic, of a very pure wavelength, or color. As the photons build up enough energy, they surge through the partially silvered end of the ruby rod as a brilliant, powerful red beam of laser light.

Awards Received by Townes
"It appears at first incredible that any such discovery should be made, and when it has been made, it appears incredible that it should so long have escaped men's research. All of which affords good reason for hope that a vast mass of inventions yet remains."

Francis Bacon, 1561-1626

In 1964, Charles H. Townes received the Nobel Prize for contributions to the study of quantum electronics, primarily for work in the development of the maser and laser. Townes shared the Nobel Prize with two Soviet scientists, Alexander M. Prokharov, and Nickolai G. Basov, who also made contributions to quantum electronics. Before the Nobel Prize, Townes had received other prestigious awards for his work.

Townes also received these awards: the 1961 David Sarnoff Electronics Award given by the Institute of Electrical and Electronics Engineers in recognition of outstanding contributions in electronics; the 1962 John Carty Award given by the National Academy of Science for distinguished accomplishments in science; the 1961 Rumford Medal, awarded to Townes by the American Academy of Arts and Science for his outstanding discoveries in the study of heat and light; the 1982 National Medal of Science, presented in 1982 by President Ronald Regan, this award is given yearly to an American scientist whose work has shown great and immediate practical value; the Niels Bohr international medal awarded in 1979 for contributions to the peaceful use of atomic energy; and, the LeConte Medallion, a S.C. Hall of Science and Technology Citation. In 1980 Townes was inducted into the South Carolina Hall of Science and Technology. He was its first living member.

Townes helped build the foundation of laser technology. He has continued to distinguish himself in other fields connected with the study of electromagnetic radiation.

In 1967 Townes began astrophysical research at the University of California in Berkeley. His work involves the study of radiation from space using principles of radio and infrared astronomy. In interstellar space Townes and his associates discovered water and ammonia, the first complex molecules found outside our solar system, and showed that water was producing intense natural maser activity there. In addition they have gathered solid evidence supporting the existence, in the center of the Milky Way, of a region where gravity is so strong that not even light can escape. Such regions are known as black holes.

Demonstrating his continued interest in space science is a picture of Townes in 1982 with infrared telescope aboard NASA's Kuiper Airborne Observatory. His team designed instruments that were used to analyze infrared radiation from space. Townes had long been interested in space science. Between 1966 and 1970 he was chairman of NASA's Science Advisory Committee for the Lunar Landing. The committee provided many of the ideas behind mankind's fist visit to an extraterrestrial body.

 


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