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    In memoriam: Charles Townes, laser pioneer and Nobel Laureate

    28 January 2015

    Charles Hard Townes
    Charles Hard Townes, in 2010, at SPIE
    Photonics West. Townes was among
    those honored that year for the
    invention of laser technology.

    Charles Hard Townes, Professor Emeritus of physics at the University of California, Berkeley, who shared the 1964 Nobel Prize in Physics for invention of the laser and subsequently pioneered the use of lasers in astronomy, died 27 January 2015. He was 99. Professor Townes was a Fellow of SPIE, and recipient of the SPIE Gold Medal of the Society and numerous other honors.

    Townes was 35 in the spring of 1951 when, seated on a park bench in Washington, DC, he was struck by the solution to a longstanding problem: how to create a pure beam of short-wavelength, high-frequency light.

    That revelation -- not much different from a religious revelation, Townes believed -- eventually led to the first laser, a now ubiquitous device common in medicine, telecommunication, entertainment and science.

    Tributes to Townes' contributions to science and to the optics and photonics community included comments from SPIE CEO Eugene Arthurs, who offered two personal observations.

    "First, he loved talking to students and was always enthusiastic about doing that at any request," Arthurs said. "He had a great warmth and humility in these student encounters." Second, along with technical genius, Townes possessed a great sense of joy in life, of willingness to try anything that really inspired him, Arthurs said.

    "When we held our Astronomical Telescopes and Instrumentation meeting in Glasgow in 2004, and had some ceilidh dancing as a social mixer, Charles, then aged 89, was first on the floor, and last off," Arthurs remembered. "He certainly gave a wonderful image for a brilliant scientist and one I only wish more young people could have seen -- nothing against 'The Big Bang Theory.' We were blessed by having him for so many years. May he dance on in a better place."

    Born 28 July 1915, in Greenville, South Carolina, Townes attended Furman University and graduated summa cum laude in 1935 at the age of 19 with a BS in physics and a BA in modern languages. He completed an MA in physics at Duke University in 1936 and moved to Caltech, where he obtained his PhD in 1939. His thesis involved isotope separation and nuclear spins.

    At the time of Townes' inspiration on the DC park bench, he was a professor at Columbia University and a consultant for Bell Telephone Laboratories. Townes had transitioned from working on radar during World War II to using shorter wavelengths of light to study the energy states of molecules, a field called spectroscopy.

    The problem then bedeviling him was how to create an intense beam of microwave energy to use as a probe. Albert Einstein proposed in 1917 that the right wavelength of light can stimulate an excited atom to emit light of the same wavelength, essentially amplifying it, but Townes was stymied by how to corral a gas of excited atoms without them flying apart.

    His revelatory solution allowed him to separate excited from non-excited molecules and store them in a resonant cavity, so that when a microwave traveled through the gas, the molecules were stimulated to emit microwaves in step with one another: a coherent burst. He and his students built such a device using ammonia gas in 1954 and dubbed it a maser, for microwave amplification by stimulated emission of radiation.

    Four years later, in 1958, he and his brother-in-law and future Nobelist Arthur Schawlow conceived the idea of doing the same thing with optical light, but using mirrors at the ends of a gas tube to amplify the light to get an "optical maser." Bell Labs patented the laser, while Townes retained the patent on the maser, which he turned over to a nonprofit.

    Theodore Maiman demonstrated the first laser -- light amplification by stimulated emission of radiation -- in 1960.

    Townes shared the 1964 Nobel Prize in Physics with Aleksandr Prokhorov and Nicolai Basov, who independently came up with the idea for a maser.

    Townes went on to use masers for radio astronomy, and lasers for infrared astronomy and interferometry, and promoted their use in areas as diverse as precision timekeeping -- the atomic clock -- and extraterrestrial communication. With the help of lasers, he and colleagues detected the first complex molecules in interstellar space and first measured the mass of the black hole in the center of our galaxy.

    Until last year, Townes visited the Berkeley campus daily, working either in his office in the physics department or at the Space Sciences Laboratory. He was a big supporter of the International Year of Light observance, and made a promotional video for the initiative last year in his office.

    Members of the SPIE community paid tribute to Townes:

    Townes was "a vigorous supporter of graduate research," said SPIE Past President Don O'Shea, professor emeritus at Georgia Tech. "Long after the Nobel laurels had been bestowed he continued to pursue the answers to current questions and to train younger researchers. He certainly did not rest on his laurels."

    "He gave so much to humanity through his intellect, his curiosity, and his generosity, and especially his time," said SPIE Past President M.J. Soileau, professor and vice president of the Office of Research and Commercialization at the University of Central Florida (UCF). "He was an inspiration to so many generations of students and will be for generations to come."

    UCF dedicated the Townes Laser Institute in 2007. Director and SPIE Fellow Martin Richardson said, "It is a sad day today for the optics, photonics and laser communities across the world, and especially for the faculty, scientists and students of the Townes Laser Institute and the College of Optics, CREOL at UCF." Richardson recalled Townes' generosity when he met the Nobel laureate in 1968. "I will always remember this meeting, and the motivation it gave me for science," he said.

    Townes is survived by his wife, Frances Hildreth Townes, whom he married in 1941; daughters Holly Townes, Linda Rosenwein, Ellen Townes-Anderson, and Carla Kessler; six grandchildren; and two great grandchildren.


    Video interview with Charles Townes: The early days of laser and maser research (SPIE Newsroom, 2010)

    Charles Townes '35, beloved scientist teacher, Nobel Prize winner (Furman University)

    Charles Townes, physicist who invented the laser (Los Angeles Times)

    Laser inventor Charles Townes dies at 99 (


    Charles Hard Townes

    Charles Townes, Nobel Laureate for his pioneering work in laser technology, dances during a reception at SPIE Astronomical Telescopes and Instrumentation in Glasgow, in this 2004 photo.