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A Cut above: Ultrapowerful Laser Offers Greater Precision Sans Heat Damage [Slide Show]

New ultrashort-pulse laser delivers enough power to vaporize more viruses without harming healthy cells
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Image courtesy of Raydiance, Inc.

Most lasers rely on continuous waves of energy to generate heat that allows doctors to make cuts during surgery, computers to burn information onto CDs and DVDs, and scanners to read bar codes. But a newer type of laser promises to do all of these things more efficiently using quick, short blasts of energy. This pulsed-laser technology has been around since the 1980s but high cost has kept it from becoming widely used. Petaluma, Calif.–based Raydiance, Inc., however, hopes to overcome that obstacle with the latest version of its ultrashort pulse (USP) laser system unveiled Wednesday.

USP lasers emit brief but powerful light pulses that last only one femtosecond (a quadrillionth of a second) and, unlike continuous wave lasers, instantly vaporize any material without heat or residual damage to surrounding areas. Raydiance's USP laser system uses software to control the movement of photonic energy through fiber-optic cables (rather than bouncing light beams between mirrors), generating more energy in a smaller amount of space than a conventional laser.

With version 2.0 of its Discovery laser platform, Raydiance has doubled the technology's peak power to 10 megawatts and is looking to market the technology so the company's lasers become as ubiquitous in photovoltaic cell manufacturing and in surgical equipment as Intel processors are in PCs, Raydiance co-founder and president Scott Davison says.

"The technology has been stuck in science project land," he says, "and now it's ready for commercialization." (See our slide show featuring examples of the laser's capability.)

Raydiance Wednesday also announced $20 million in new funding from Greenstreet Partners and Draper Fisher Jurvetson. (The company had previously received more than $25 million in venture capital financing and $10 million in government-funded research and design contracts.)

Raydiance's technology has attracted the attention of the U.S. Food and Drug Administration (FDA), which in July 2007 signed the company to a two-year cooperative research and development agreement that has allowed the FDA's Center for Devices and Radiological Health (CDRH) to evaluate the use, safety and effectiveness of Raydiance's USP laser system in a number of areas, including the ablation of corneal tissues in refractive surgery and corneal repair; the administration of light therapy for treating cancer, cardiovascular disease and diabetes; and the removal of plaque on teeth without damaging the enamel. The agency has yet to report on its findings.

The technology had been part of a Defense Advanced Research Projects Agency (DARPA) project before Davison and Raydiance Chairman/CEO Barry Schuler (formerly CEO of America Online) built a company around it in 2005.

"The Defense Department liked the ultrashort-pulse laser because when you squeeze the pulse down you increase the energy per pulse," Davison says. "You're creating an immense electrical field that, instead of boiling a substance like a conventional laser, you are vaporizing it. You can point it at anything and the material just disappears, and what's left behind is a precise cut."

The laser's effectiveness is what brought together Raydiance and Arizona State University in Tempe physics professor Kong-Thon Tsen earlier this year. Raydiance was so intrigued by Tsen's research into ways of using a laser to zap and kill viruses that it loaned one of its devices to the researcher for six months.

Raydiance's USP laser system has three times as much energy per pulse as his lab's titanium-sapphire laser, which takes up 10-square feet (0.9 square meter). This means Tsen does not have to focus the laser beam as tightly and can kill more virus particles in less time without damaging the healthy cells around the damaged tissue. For the titanium-sapphire laser to be powerful enough to kill HIV and human papillomavirus, Tsen must focus the beam down so that it is 10 microns in diameter. The Raydiance laser system lets him use a beam that is 100 microns in diameter to attack the viruses. (A micron is one millionth of a meter, or about four one hundred-thousandths of an inch.)

Tsen submitted a proposal last month to the U.S. National Institutes of Health for a $1.2-million grant to buy an ultrashort-pulse laser system. (He expects to hear back by May.) He has not committed to Raydiance, however, and says he is investigating USP lasers from Quantronix in East Setauket, N.Y., Spectra-Physics Lasers in Tucson, Ariz., and Coherent, Inc., in Santa Clara, Calif.

One drawback to Raydiance's technology, Tsen notes, is that a researcher cannot adjust the wavelength of its laser. "I want a versatile laser system," he says. "Their system right now is not tunable."

Another problem is its high cost in a very difficult funding environment. Davison says his company has tried to address this by cutting the cost in half with its latest version, which is offered with two different pricing models. The first is to charge customers $20,000 per month for the laser, software and support services. A second model in development will allow customers to buy the laser for about $90,000 and purchase the software separately.

The cost has not scared away several Raydiance customers. NanoGram Corporation, a Milpitas, Calif., maker of photovoltaic modules, uses Raydiance's USP lasers to etch the solar circuits into its devices. Ahamed Idris, a professor of emergency medicine at the University of Texas Southwestern Medical Center at Dallas, is testing the Raydiance laser system's ability to surgically remove dead tissue from burn victims. And researchers at New Mexico State University are testing its ability to perform laser-induced breakdown spectroscopy to study gemstones (which could help the school's department of geological sciences differentiate between real and fake gems).

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