US Army's New Ray Gun

From the BBC

The gun uses a large dish mounted on a Humvee vehicle

The US military has given a first public demonstration what it says is a revolutionary heat-ray weapon to repel enemies or disperse hostile crowds.

The gun - called Silent Guardian - projects an invisible high energy beam that produces a sudden burning feeling, but is actually harmless.

The beam can be fired as far as 500m (500 yards), much further than existing non-lethal weapons like rubber bullets.

The gun should be in use by the US military within three years.

The prototype weapon uses a large rectangular dish mounted on a Humvee vehicle.

The waves can penetrate clothes but not walls, suddenly heating up the skin of anyone in its path to 50C.

Journalists who volunteered to be zapped during the demonstration on an air base in the US state of Georgia described the sensation as similar to a blast from a very hot oven - too painful to bear and forcing them to dive for cover.

Military officials say the so-called "active denial system" is harmless, but could prove invaluable in the increasingly complex situations they face.

The marine colonel in charge said it was an alternative to going straight from shouting to shooting and could save lives.

The system could be used both for dispersing hostile crowds during peace time, or in conflicts like Iraq and Afghanistan.