The element to be purified is first incorporated into a chemical that can be turned into a gas. (In this case, the exact compound is still proprietary information.) Then an infra-red laser is shone through the gas.

ECONOMIST: Diamonds

The laser sensor can be reset by a blast of nitrogen gas.

BBC: Plastic lasers shed light on hidden explosives

Those made by his firm use advanced laser-fluorescence technology: more accurate, simpler, cheaper and more robust, he says, than the gas-chromatography apparatus in common use so far.

ECONOMIST: Doom and gloom are not universal