Livermore lab laser hits new record

0 Comments | Oakland Tribune, Apr 1, 2004 | by Ian Hoffman, STAFF WRITER

In less than an hour, technicians Balbir Bhachu and Kurt Cutter clamped thick slabs of exotic glass into a device they're building for the U.S. Army and blew away the world's record for power on a solid-state laser.

The invisible beam on Monday measured 29.7 kilowatts, instantly topping a U.S. military goal of 25 kilowatts that defense giants Raytheon and Northrop Grumman are racing to achieve by the end of 2004.

That's still a fraction of the power that military experts say is needed to turn light beams into weapons. To knock rockets, missiles and aircraft out of the sky reliably from several miles away is likely to require 100 kilowatts of laser power.

That's what the Air Force and the Army's Space and Missile Defense Command are after. So far, only chemical lasers ranging in size from a shopping center to a convenience store have been able to shoot down mortars and rockets on the fly. They require truckloads of chemicals.

Just a decade ago, many laser scientists thought such high- powered kilowatt-class beams were beyond the reach of lasers relying on electricity and a solid core of crystal.

A band of scientists, engineers and technicians at Lawrence Livermore lab has made and broken all of the power records for solid- state lasers in the last five years.

Their refrigerator-size laser, sitting on a lab table, uses dozens of lithium-ion cells to power 8,000 tiny laser diodes that flood light into a rack of square, pinkish crystals that produce a coherent beam of infrared light.

After installing new, larger crystals, Bob Yamamoto's team fired off some test shots then ran the laser for a full second at maximum power.

"Getting a solid-state laser to this high power is a major accomplishment of physics and suggests a new route for development of weapons," said Loren B. Thompson, a security analyst at the Washington-based Lexington Institute who has studied directed-energy weapons extensively.

"It's pretty impressive because nobody's ever been there before," he said.

At about 15 kilowatts, a laser beam can eat through a half-inch steel plate in less than a second. While 30 kilowatts of light beam may not knock down rockets miles away, Yamamoto has plenty of ideas for Earth-bound targets.

At 30 kilowatts, a laser in theory would explode pockets of moisture in the upper surface of the ground 100 to 200 yards away. Yamamoto's laser, firing 200 pulses a second, would invisibly propel a plume of dirt into the air to locate land mines and detonate them or cook off their explosives.

What Yamamoto really wants to aim at is IEDs -- the improvised explosive devices or roadside bombs that are now the leading cause of American casualties in Iraq since the end of major combat in May. Insurgents are hiding them in Coke cans, dead animal carcasses and 55- gallon drums.

"With 30 kilowatts, you could zap a Coke can and in fractions of a second, you'll know if there's a bomb in there," he said.

Contact Ian Hoffman at newspapers.com">ihoffman@ang-

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