Experts at Newport News Lab Develop Powerful New Laser

By John S. MacNeil, Richmond-Times Dispatch
July 18, 1999

A year after emitting its "first light," a highly focused and powerful experimental laser at the Thomas Jefferson National Accelerator Facility has become the world's most powerful tunable laser.

Don't expect this laser on a compact disc player. With just 10 watts, the Jefferson Lab laser, called the Free Electron Laser, can burn holes through metal and pieces of ceramic. With 1,720 watts, reached Thursday night, researchers hope to use the laser to harden the surfaces of Virginia Power hydroelectric turbine blades and increase their corrosion resistance.

In the next few months, scientists at the Newport News lab, along with researchers from Virginia Power and other industry partners, will begin preliminary experiments to apply the laser's capabilities to a number of real problems, such as developing better lasers for communication and identifying impurities in the silicon wafers used to make computer microchips.

"At about the same time we're starting our experiments, we've reached our very impressive goal," said Dr. Fred Dylla, the director of the Free Electron Laser project.

The Jefferson Laser differs from most lasers because of its vastly increased power -- it's about 1.7 million times more powerful than the laser found on a CD player -- and because the color of it's light is tunable.

The ability to tune a laser is important because experiments on different types of material require different frequencies of light, and the frequency of light determines its color. Although light from the sun comes from a range of frequencies, a laser focuses light into one powerful beam of uniform frequency and color.

To create its laser beam, the FEL shoots 40 million bunches of electrons a second into a super-chilled 60-foot-long column. The column charges the electrons to 40 million volts, and shoots them out at the speed of light into a series of magnets.

The magnets cause the electrons to lose their energy, which is released as extremely intense light. A series of mirrors then tweaks the light beam to alter its size, and the magnets alter its wavelength.

When the FEL came online with 155 watts on June 17 of last year, it was already one of the most powerful tunable lasers operating in the infrared region of visible light. Two months ago, Dylla and his team first attempted to push the laser to 1,000 watts, the goal of the current $25 million project. However, the mirrors that focus the light into a monochromatic beam could not reflect the light precisely enough to produce a beam of the required power.

Now, Dylla hopes to further extend the capabilities of the 1,720-watt laser by increasing the power to 10,000 watts, and adding the ultraviolet (UV) region of light to the laser's tunable range.

Already, the primary sponsor of the current project, the Navy, has agreed to support the FEL's application for a grant to upgrade the laser, said Dylla.

"Three years from now we want a one-kilowatt, UV laser," said Dylla. "Now that would be a stupendous undertaking."