Todd Smith, pioneer in the field of free-electron lasers, dies at 85

Todd Smith, professor (research) of physics, emeritus, in the Stanford School of Humanities and Sciences (H&S) and a pioneering scientist who helped develop the free-electron laser (FEL), died  Sept. 24, 2025. He was 85.

A member of the Stanford community for nearly 60 years, Smith made his biggest impact as part of the W.W. Hansen Experimental Physics Laboratory (HEPL), where he conducted low-temperature research that led to breakthroughs in his field. This included developing a tunable laser that could produce bursts of radiation that were both powerful and precise, a technology now used far and wide for purposes ranging from imaging proteins to conducting surgery.

“Todd was a master at what I called ‘Real Time Science,’” said H. Alan Schwettman, professor of physics, emeritus. “Todd would often address technical problems in unconventional ways, and I sometimes accused him of challenging nature with the mindset ‘Prove to me that I can not get away with this!’ His challenge success rate was remarkable!”

“The Todd Knob”

Smith first arrived at Stanford in 1965 as a research associate, part of the team that eventually developed the free-electron laser in the ’70s. He stayed for four years and then left for the University of Southern California. He returned to Stanford for good in 1973 to work at the High Energy Physics Laboratory, where he was promoted to senior research associate in 1976. In 1989, he became a professor (research) in the Department of Physics in H&S and continued working at the lab, which changed its name to Hansen Experimental Physics Laboratory in 1990.  

His early accomplishments earned him the Free Electron Laser Prize, given to those who advance the field of FELs, in 1990, and in 2000, he was elected to fellowship in the American Physical Society. During his career, he published dozens of papers on FELs, superconductivity, and experimental accelerator physics. He also mentored generations of graduate students and earned a reputation for playfulness that endeared him to those he worked with.

“Todd was full of clever and tricky ideas for doing new things, so I liked to say that Todd came up with the crazy ideas and I had to make them work,” said Richard Swent, who worked under Smith for 25 years as a research scientist at HEPL and with whom Smith co-authored several papers. “Our research group spent many late nights trying to squeeze out more performance from the laser, and Todd was by far the best at it. Even after the control system was computerized, we left a few knobs for him to turn because we knew he liked them. One of them, known as the Todd knob, wasn't connected to anything, but it still seemed that he could tweak it and make the laser work a little better.” 

“As my postdoctoral adviser, he shaped the way I think about physics—questioning assumptions, welcoming curiosity, and aspiring to make bolder contributions,” said Daniel Palanker, professor of ophthalmology in Stanford’s School of Medicine and former director of HEPL. At the same time, he was very kind and generous with his time and attention. I am profoundly grateful for the opportunity to work with him and to learn from him. His legacy lives on in the many students and colleagues he inspired and in the discoveries he helped make possible.”

World traveler, beloved repair man

Smith was born in Mobile, Alabama, and then spent much of his childhood in New Orleans and Houston. His father was the chief geophysicist for Standard Oil Company of California, and his mother had a bachelor's degree in mathematics from the University of California, Berkeley. According to his wife of 55 years, Sandy, he was curious and experimental throughout his life, once setting a field on fire with a model airplane and another time causing an explosion by throwing a cotton ball into a gas heater in his bedroom.

As a teen, he earned money by repairing televisions for friends and neighbors, foreshadowing how he would spend his later years. Smith arrived at Stanford after receiving a bachelor’s degree in physics from Cornell University and a doctorate from Rice University. In his later years, he used the skills he gained in the lab to fix clocks, lamps, heaters, and more, volunteering with local Repair Cafés. He was also a pun enthusiast and world traveler until the end of his life, spending some of his last weeks in Ireland and Scotland.

He is survived by his wife, Sandy; his sons, Kevin (Alicia) and Alex (Elaine); his grandchildren, Neal, Penny, Conner, and Katie; and his sister, Susan Noble (Ward).