Sunlight acts like laser. (Solar Surgery).

Surgeons may someday use super-concentrated sunlight to burn tumors off major organs. So say Israeli scientists, who have succeeded in channeling sunlight down a fiber optic cable to produce laserlike beams. The device might provide a cheap alternative to medical lasers in countries with limited access to high technology but plenty of sunlight.

Laser equipment can reduce tumors, blood loss, pain, healing time, and infections. While assessing the state of laser surgery in Israel, Jeffrey M. Gordon found that even in that moderately wealthy nation, the supply of the expensive equipment was sparse.

Gordon, a physicist at the Jacob Blaustein Institute for Desert Research at Ben-Gurion University of the Negev in Sede Boqer, and his colleagues knew that radiation from the sun is more than sufficient to match a medical laser's output, but they faced the problem of how to concentrate sunlight into useful beams.

Their solution relies on a saucepan-size parabolic mirror aimed with a mechanism that tracks the sun. The novelty of their design is the addition of a smaller flat mirror to shunt sunlight from the parabolic mirror into the tip of a 20-meter fiber optic cable. At the other end of the cable, the researchers measured sunlight, now concentrated by a factor of 11,000, at power densities comparable to those used in laser fiber-optic surgery.

In the Sept. 30 Applied Physics Letters, Gordon's team reports using its solar device to produce laser-quality lesions on chicken breasts. Gordon has now teamed up with a surgeon to test the solar equipment's efficacy against liver tumors in rats.

Thomas E. Milner, an optical engineer at the University of Texas in Austin, says that the new device has useful aspects, citing its simplicity and the optic fiber's flexibility. However, many technical aspects, such as ways to keep the light dosage constant, need to be worked out.

"It's kind of neat to see that you can do that with the sun, but there would be a lot of hurdles to jump over before it was applied for laser surgery," Milner says.

Gordon admits that solar surgery can never replace the most sophisticated laser procedures, such as those used in eye surgery. "I am not describing a panacea," he says.

An obvious drawback is that solar surgery requires sunny weather. Benefits will probably be greatest in countries with clear conditions, such as those in the Middle East, where the sun shines at least 7 hours per day on more than 250 days per year. Many hospitals in poor nations might balk at a $100,000 laser but could easily afford $1,000 for solar-surgery equipment. "No new process or material needs to be developed in order for this concept to work," Gordon notes.

The new device could also benefit solar power. Now that sunlight can be captured into a fiber-optic cable, smaller and more efficient solar panels could replace current ones. Agami Reddy, an engineer at Drexel University in Philadelphia, is working with Gordon and the U.S. Department of Energy to adapt the sunlight concentrator for energy applications.