Topic of the Moment: lasers

As the US Navy demonstrates a ship-mounted laser capable of disabling drones and small boats, we recap the history of the laser and its various uses

USS Ponce
The USS Ponce, which has been fitted with a laser system designed to stop drones and boats

  
The word ‘laser’ originated as an acronym for “light amplification by stimulated emission of radiation”.

Stimulated emission is used to produce a coherent beam of light – an atomic electron in an excited state interacts with a photon of light; as it drops to a lower energy level it emits a second photon with the same phase, frequency and polarization as the original one.

The underlying theory behind the laser was first developed by Albert Einstein in 1917, but a working device wasn’t produced – operating at microwave frequencies – until 1953. A laser using visible light came seven years later in 1960.

Improvements since then have meant that modern lasers can work in continuous operation rather than having to be pulsed, have a wider range of frequencies of light that they can produce, and both a higher maximum power and greater efficiency at lower cost.

Despite their ubiquity as “death rays” in science fiction, lasers had not been put to use as weapons until the development of the system now installed on the USS Ponce. In fact, they initially had no immediately obvious applications at all.

Soon, however, they revolutionised supermarkets’ stock control when the barcode scanner became commonplace in 1974, and then changed the way music was listened to at home with the CD player in 1982.

Now their range of uses is extensive, from surgery through spectroscopy to light shows. And while the latest devices might be able to stop boat or drones, none are likely to blow up whole planets anytime soon.