August 24, 2005

Airborne laser brings Star Wars one step closer

LONDON (Reuters) - A U.S. Pentagon invention could make air
combat resemble a battle scene from Star Wars, with a laser so
small it can fit on a fighter jet, yet powerful enough to knock
down an enemy missile in flight.

The High Energy Laser Area Defense System (HELLADS), being
designed by the Pentagon's central research and development
agency, will weigh just 750 kg (1,650 lb) and measures the size
of a large fridge.

To date, such lasers have been so bulky because of the need
for huge cooling systems to stop them overheating, that they
had to be fitted to large aircraft such as jumbo jets, New
Scientist magazine reported on Wednesday.

But the Pentagon's Defense Advanced Research Projects
Agency reckons it has solved the problem by merging liquid and
solid state lasers to cut the size and weight by "an order of
magnitude," according to its Web site.

Liquid lasers can fire a continuous beam but need large
cooling systems, while solid state laser beams are more intense
but have to be fired in pulses to stop them overheating.

"We've combined the high energy density of the solid state
laser with the thermal management of the liquid laser," New
Scientist quoted project manager Don Woodbury as saying.

Dubbed the "HEL weapon" by its developers, a prototype
capable of firing a mild one kilowatt (kW) beam has already
been produced and there are plans to build a stronger 15-kW
version by the end of the year.

If everything goes according to plan, an even more powerful
weapon producing a 150-kW beam and capable of knocking down a
missile will be ready by 2007 for fitting onto aircraft.