Built by the U.S. firm Raytheon, it is part of its "Directed Energy Solutions" programme.This tabletop model looks pretty nifty. I can imagine teenaged boys making them and then having contests with their friends to see how long they can endure the pain-ray. Link
What it amounts to is a way of making people run away, very fast, without killing or even permanently harming them.
I tested a table-top demonstration model, but here's how it works in the field.
A square transmitter as big as a plasma TV screen is mounted on the back of a Jeep.
When turned on, it emits an invisible, focused beam of radiation - similar to the microwaves in a domestic cooker - that are tuned to a precise frequency to stimulate human nerve endings.
It can throw a wave of agony nearly half a mile.
Previously on Boing Boing:
• Pain transmitter to be used for riot control (Thanks, Steve in Paris!)