Dramatic interdisciplinary collaboration using the free-electron laser leads researchers to contemplate its scientific and medical promise

Sitting in the conference room of the W. M. Keck Foundation Free-Electron Laser Center, Glenn Edwards reflects on the first 10 years in the life of one of the world's most intriguing scientific tools: "It's been a lot of fun."

Edwards, a biophysicist who directs the FEL Center, need only look around him for ample evidence. Not only have 10 years gone into the creation of Vanderbilt's FEL program, tens of millions of dollars have been invested, as well. The result is the broadest existing program for the application of free-electron lasers to problems in biology, physics, materials science and medicine. And in many ways, the building that houses the world's most powerful free-electron laser provides the best metaphor describing Vanderbilt's FEL program.

"As the promise of realizing what we set out to do, as written in the original proposal, gets closer, the gravity of the situation is taking over. It's becoming very serious," Edwards says.

What's the frequency?

The foundation of the program is the laser itself, which resides in a vault two floors underground in a building at the conjunction of the College of Arts and Science and the Schools of Engineering and Medicine.

Developed in the 1970s by John Madey, then at Stanford University, free-electron lasers are a major departure in laser technology. As the name suggests, free-electron lasers differ from their conventional counterparts in their use of electrons which have been liberated from their usual bound state. Conventional lasers operate at specific wavelengths dictated by the atomic structures binding their electrons. Free-electron lasers, on the other hand, use high-energy electrons traveling at near the speed of light to produce a high-powered beam of infrared laser radiation.

Vanderbilt's FEL program began in 1986 with the vision of physics faculty members Norman H. Tolk, Richard F. Haglund and Glenn Edwards, otolaryngologist Robert H. Ossoff, radiologist Frank Carroll and molecular biologist Sidney Fleischer. With the approval of Arts and Science Dean Jacque Voegeli, who committed matching funds, they submitted an application to the Office of Naval Research's Medical FEL Program for the development of Vanderbilt as an FEL research site.

Their proposal strongly emphasized the interdisciplinary nature of research at Vanderbilt and the involvement of the College, the School of Engineering and the School of Medicine in the project.
As a result, Vanderbilt beat out six other prestigious institutions to win an initial grant of $8 million to build the FEL, and the College funded the cost of the initial building. Professor of Physics Charles A. Brau arrived at Vanderbilt in 1988 to direct the FEL Center. A co-inventor of the excimer laser, his prior experience as manager of the FEL program at Los Alamos National Laboratory served him well in a long and trying process of laser installation and commissioning.
Vanderbilt's FEL achieved "first light" in 1991.

The FEL accelerates electrons to an energy of 40 million volts and then injects them into a "wiggler," a series of magnets which causes the electrons to vibrate and emit intense energy as infrared laser light. The light is then transported into the center's laboratories and operating rooms for use in experiments.

The energy of free electrons can be adjusted, making it possible to tune the laser wavelength from 2 to 10 microns (a micron is 1/1000th of a millimeter) in the infrared part of the spectrum. The FEL is more powerful and brighter than conventional lasers and is further characterized by its ultra-short pulse lengths, less than a billionth of a second. The peak power of Vanderbilt's FEL is more than 10 megawatts; its average power exceeds 10 watts.

Tunability is the most critical attribute of FEL technology. Computer controls developed for the Vanderbilt FEL enable its beam to be tuned easily across different parameters (wavelength, power and pulse) and for multiple researchers to use the FEL each day. The FEL can be retuned to the specifications and needs of different researchers in as little as five minutes.

This flexibility gives researchers an unlimited number of wavelength and pulse length combinations to study photon interactions with materials and to apply these studies to chemistry, physics, and the materials and biomedical sciences. Thus, a class of spectroscopic experiments inconceivable a decade ago has already been performed using the Vanderbilt FEL.

Follow the blue tube

Once generated, the beam from the FEL must be directed to a target. Using a complex system of blue pipes containing strategically placed mirrors, the beam is routed up to the second floor of the building where it runs along ceilings and through walls. That floor contains five laser target rooms, two experimental surgical rooms, the FEL control room, and supporting biological and electronic workrooms.

Research projects undertaken here have fulfilled the ideals of the original investigators. They are interdisciplinary, highly collaborative and international in scope. Scientists, engineers and physicians from the College of Arts and Science, School of Engineering and School of Medicine already have begun to yield important insights in the basic sciences, engineering disciplines and medical specialties. Other scientists have traveled from Switzerland, Japan and Germany to use the FEL.

Edwards is fond of describing a cycle of basic research that enables applied research which in turn enables practical application. Any given project at the FEL center will be at some stage in this cycle.
As projects reach their ultimate potential, new ones will be suggested, either by results from prior research or by faculty who bring in new ideas. New proposals are peer-reviewed for a high degree of scientific merit.

By 1993, a significant research finding had already emerged. Edwards, in collaboration with researchers from the School of Medicine, had discovered a wavelength that vaporized soft tissues without causing as much peripheral damage as conventional laser techniques. Their findings were acclaimed in the journal Nature in 1994.

Other research efforts in the center's early years have focused on measuring important properties of the structure and function of cells, particularly the process of energy transfer within DNA; working to generate monochromatic x-rays that will produce higher quality images than current mammograms at one-50th their radiation dose and to develop new cancer therapies; and discovering properties of semiconducting and optical materials that could lead to such electronic advancements as a television screen thin enough to be hung on a wall or improved performance of computer networks.

Going up?
In fact, the demand for FEL beam time quickly exceeded its availability. Researchers pursuing a variety of projects also began to feel the constraints of the center's limited space. The demand for additional space, however, had been anticipated. The center's initial two floors stopped slightly above ground level but had been designed to allow the construction of further stories. In 1991, the idea of funding the construction of two new stories, essentially doubling the size of the facility, was put before the W. M. Keck Foundation of Los Angeles. By 1993, preliminary discussions had developed into a formal grant application for $3.7 million. In December 1993, the grant was awarded.

The result is a third-floor suite of rooms that meet two needs. The first is the need for research space. Two large bullpen-style laboratories have been constructed for the purpose of conducting basic and applied research. The FEL beam delivery system is being extended to these laboratories, but related projects not requiring the FEL beam itself are already underway.

The third floor also houses offices and conference areas that for the first time bring the various researchers and FEL staffers into regular and frequent contact with each other. "When the physicists, surgeons, cell biologists and engineers refer to each other on a first name basis, you crack outstanding problems," says Edwards.

The sky's the limit
"In our original proposal, we sought a very high-risk research program that includes human care. Those goals have been 80 percent accomplished," says Edwards.

And the missing 20 percent? It's on the fourth floor where surgical suites, procedure rooms, recovery rooms, a patient-family waiting area and other facilities are designed specifically for human medical surgery. The ultimate promise of the FEL, the application of research findings to benefit humanity, will be realized on the topmost story of the FEL Center.

Using the soft tissue research findings, as well as findings from other center projects, efforts are proceeding along parallel tracks to apply the FEL to human surgical procedures in ophthalmology, otolaryngology, neurosurgery and dermatology. "Two years should put us on the doorstep," says Edwards. If successful, investigational surgery in these disciplines has the potential to revolutionize laser surgery entirely.

To its credit, Vanderbilt's is the only center in the country with the facilities to even be able to contemplate human surgery. This credit is shared with the Office of Naval Research, the W.M. Keck Foundation and the Whitaker Foundation, which recently granted the School of Engineering $1 million to support two faculty working on FEL technology issues.

According to Edwards, the support from these outside sources and the University's own commitment of financial support through the College and the Chancellor have enabled FEL researchers "to hold a steady course in our scientific mission at a time of near turmoil in scientific funding. We very much have a sense of purpose shared by all the disciplines. They fund our judgment."

For the FEL Center's first decade, that judgment has been very good indeed.

-Kurt Brobeck

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This document created November 18, 1996