Set phasers to stun

HSV Technologies of San Diego, California, is developing a non-lethal weapon that uses ultraviolet laser beams to harmlessly immobilise people and animals from a safe distance.

The Phaser-like device uses two beams of UV radiation to ionise paths in the air along which an electrical current is conducted to and from the target. In effect, the beams create wires through the atmosphere wherever they are pointed.

The current within these beams is a close replication of the neuro-electric impulses that control skeletal muscles and is thought to be imperceptible to the targeted person because it differs from his or her own neural impulses.

This is because repetition rate in the beam is sufficiently fast to tetanize muscle tissue, tetanization being the stimulation of muscle fibres at a frequency that merges their individual contractions into a single sustained contraction.

HSV Technologies claims no retinal damage can occur because the cornea absorbs all ultraviolet radiation at the wavelengths used.

Moreover, the beams are said to be too weak to produce corneal inflammation unless they are directed at the eyes for several minutes. In addition, the current they transmit is insufficient to affect the muscles of the heart and diaphragm.

Successful tests have been performed at the University of California at San Diego, and further refinements using novel laser designs are said to be forthcoming.

Although the smallest laser now available for this application is the size of a suitcase, a hand-held version should, according to HSV Technologies, become feasible with only modest advances in laser technology.

Also under development is an engine-disabling variation for use against the electronic ignitions of automobiles.

The disabling voltage would be transmitted through two channels of electrically conductive air. The conductive channels would, in theory, be created by multi-photon and collision ionisation within the paths of two beams of coherent ultraviolet radiation directed to the target.

The high-voltage current would flow from electrodes at the origin of the beams, then along the channels of free electrons within them. Alternately, a single beam could be used when the high voltage source and the target are grounded.

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