Charles Townes, inventor of the laser, dies at 99

In 1951, physicist Charles Townes was lost in thought on a park bench in Washington, D.C., pondering a years-long puzzle: how to create an intense beam of light – short in wavelength and high in frequency – with far-reaching practical uses. Albert Einstein had theorized that it could be done, but no one had yet managed the feat.

On that bench, surrounded by blooming azaleas, the solution came to Townes, then a 35-year-old Columbia University researcher. It involved a flash of bright light, a population of excited ammonia molecules and a mechanism for limiting the wavelengths they could then emit.

On the back of an old envelope, he “just scratched it out,” he said of his brainstorm.

A few years later, he and two colleagues had designed and built a device they called a maser, with the “m” signifying microwave energy.

When the microwaves were replaced by light waves, the laser was born.

Townes, whose invention brought him the 1964 Nobel Prize in physics and spawned advances in nearly every area of modern society – including home entertainment technology, medicine, cosmology and commerce – died Tuesday in Oakland, Calif., while on his way to a hospital, according to the University of California, Berkeley, where he spent the last five decades of his career. He was 99.

“He was one of the most important experimental physicists of the last century,” UC Berkeley astrophysicist Reinhard Genzel said in a statement. “His strength was his curiosity and his unshakeable optimism, based on his deep Christian spirituality.”

Townes once said he regarded his “revelation” on the park bench as a sign of the interplay between spiritual belief and scientific inquiry. In 2005, he received the prestigious Templeton Prize for Progress Toward Research or Discoveries about Spiritual Realities.

Few other modern inventions have had the wide-ranging effect of the laser. Lasers are at the core of the CD and DVD players in the home, the bar-code scanner in the supermarket, range-finders and altimeters used by the military, speed detectors used by state troopers and a host of other commercial products.

In medicine, their uses include laser scalpels, smoothing the skin, removing tattoos, reattaching retinas and shaping the cornea to eliminate the need for glasses. In astronomy, they are used for measuring distances and examining cosmological phenomena in deep space. In industry and government, they are used for high-speed transmission of data over fiber-optic cables.

More than a dozen Nobel Prizes have relied on work done with lasers.

Physicist Theodor W. Hansch of Germany’s Max Planck Institute for Quantum Optics, upon learning that he would receive a Nobel for using lasers to study the properties of atoms and molecules, said, “We all together stand on the shoulders of our giant, Charlie Townes.”

The technology has become so common that the term laser, an acronym for “light amplification by the stimulated emission of radiation” coined by Townes and his students, has become generally understood throughout society – even though few understand the principles behind it.

Normal white light, like that emitted by the sun or a lightbulb, is a jumbled mixture of wavelengths, or colors – all out of step with one another, like a mass of people walking across a bridge. A laser, in contrast, emits a narrow beam of light of one defined wavelength in lockstep, like soldiers marching across that same bridge.

And although the footsteps of the crowd have little effect on the bridge, the combined footfalls of the soldiers have much greater effect, causing the bridge to shake and tremble. Similarly, the coherent light from a laser carries much more power than simple white light, allowing it to burn through flesh or even steel.

The idea of stimulated emission of radiation at the heart of the laser was put forth by Einstein in 1917. He reasoned that the absorption of radiation of a particular wavelength by atoms would stimulate them to emit radiation of the same wavelength.

Townes’ essential contribution was to identify and create conditions in which large numbers of atoms were in an unstable state in which they would emit more energy than they absorbed.

Microwaves can have wavelengths as long as a few feet, but Townes was working with wavelengths of about half an inch and seeking still shorter ones, which would have more uses. But electronic devices that might generate such short wavelengths were too small to produce sufficient power for any foreseeable application.

On the morning of the last day of a futile meeting in Washington to consider new approaches to the problem, Townes sat on a park bench and contemplated the issue. He reasoned that developing electronic amplifiers would not work and started to imagine using molecules, which produce radiation when they vibrate at high speeds.

He speculated that a flash of bright light could be used to create a population of excited ammonia molecules and that confining them in an appropriate cavity would limit the wavelengths that they could then produce.

Excited, he returned to his hotel room and consulted with physicist Arthur Schawlow, a collaborator and friend who later became his brother-in-law.

“I told him about it and he said, ‘OK, well, maybe.’ And so that’s how the idea started,” Townes said.

Back at Columbia, his colleagues were skeptical and urged him to abandon the project. But he and Schawlow forged ahead. They built the first maser in 1954.

The pair used the same concepts to design a device that would emit light at frequencies one-100,000th as short as microwaves. They published their design in the December 1958 issue of the journal Physical Review and obtained a patent in 1959.

Other scientists fell on this new idea avidly. In 1960, Theodore Maiman of the Hughes Research Institute in Malibu, Calif., built the first working laser, largely based on the Townes-Schawlow design.

Townes shared the Nobel Prize in 1964 with Nicolay Gennadiyevich Basov and Aleksandr Mikhailovich Prokhorov of the Soviet Union, who also made significant contributions to the development of the maser and laser. (Schawlow was awarded the Nobel in physics in 1981 for his later work with laser spectroscopy.)

The invention of the laser was also claimed by Gordon Gould. As a Columbia University graduate student he drew up a design for the laser on his own in 1957 but did not file for a patent until 1959, after Townes and Schawlow had already submitted their application. He waged a 30-year legal battle and won a patent in 1988.

Charles Hard Townes was born on July 28, 1915, in Greenville, S.C. The family lived on a small farm, where Townes grew up milking cows, picking fruit and indulging his passion for collecting insects, especially butterflies.

He was tempted to try a career in entomology but felt that he would be eclipsed in that field by his brother, the late Henry Keith Townes Jr., a founder of the American Entomological Institute.

He earned bachelor’s degrees in modern languages and physics from Furman University in 1935, followed by a master’s in physics from Duke University in 1936. He was drawn to physics for what he called its “beautifully logical structure.”

Townes moved to the California Institute of Technology to complete his doctorate in 1939, studying under physics legends J. Robert Oppenheimer and Robert A. Millikan. Townes’ thesis was on isotope separation and nuclear spins.

Graduating during the Great Depression, when academic jobs were scarce, Townes joined the technical staff at Bell Labs in New York, where he developed engineering skills and worked on the development of radar-based bombing systems during World War II.

He moved to Columbia University in 1948, where he conducted his fundamental work on the maser and laser.

He directed research for the nonprofit Institute for Defense Analyses in Washington for a few years before moving in 1961 to the Massachusetts Institute of Technology as professor of physics and provost. In 1967, he became a professor of physics at UC Berkeley, where he finished his career.

Townes’ lifelong creativity continually pushed him in new directions.

In the 1970s he began to make substantial contributions in astrophysics that relied partly on his earlier discoveries. Townes was an originator of a method to increase telescopic power by tying together light from two or more telescopes, which laid the foundation for some of the world’s most powerful telescopes.

In the latter part of his life, he turned his gaze to the sky in search for life beyond our world.

To Townes, science was the pursuit of understanding about the order of the universe, religion the pursuit of understanding and acceptance of the meaning of the universe.

“The fact that the universe had a beginning is a very striking thing,” Townes told the Los Angeles Times in 1996, in regard to the widely accepted Big Bang theory. “How do you explain that unique event” without God?

Upon receiving the $1.5 million Templeton Prize, he donated half the money to Furman University, his alma mater, and the rest to church-based charities.

Townes married the former Frances H. Brown in 1941. She survives him, along with their four daughters, Linda Rosenwein, Ellen Townes-Anderson, Carla Kessler and Holly Townes; six grandchildren; and two great-grandchildren.

Piller and Maugh are former Times staff writers. Times staff writer Elaine Woo contributed to this report.