The LaWS of Laser Light

What’s the first thing that comes to mind when someone mentions “futuristic technology”? A hint: it starts with L and ends with ‘radiation’. If you guessed ‘laser’, give yourself a pat on the back: you’re a bonafide future-tech geek. ‘But there’s no radiation in laser!’ I hear you exclaim. Well actually, there is.

LASER is an acronym of “Light Amplification by Stimulated Emission of Radiation”, a name which is not only a mouthful to say, but also describes exactly what a laser does. Lasers work by ‘radiating’ energy, in the form of photons (light particles), from their source in a highly focused beam. To do this, the electrons in an atom must first be ‘excited’ by another source of intense energy, such as extremely bright light or a powerful electro-magnetic source. Electrons are excited when they receive this energy, allowing them to orbit an atom further from its nucleus. By returning to their original position, electrons release this energy as photons. However, to release enough photons to create a laser beam, ‘stimulated emission’ must occur.

Stimulated emission is effectively a chain reaction of colliding photons. Photons are released with a certain energy depending on how far their electrons are from their original position. This energy determines the ‘wavelength’ of a photon; as it travels, the photon moves along a straight line in a wavelike pattern. When a photon collides with an atom, it transfers this energy to an electron in the same excited state as the previous one. Another photon is emitted in the same direction, with an identical wavelength/energy. Photons in a laser are coherent, meaning each particle moves in time with the others, which is how lasers can travel long distances. To control and amplify this process, mirrors are used to bounce photons back and forth inside a tube to create millions more emissions. One mirror is less opaque than the other (‘half-silvered’), and this is where the photons exit, all travelling in the same direction and at the same wavelength: a laser beam is created!

But why is this important? Why do YOU need to know about lasers? Well, because lasers aren’t future-tech at all: they’re everywhere! How do you listen to music on a CD or watch movies on a DVD? That would be a laser. How do carpenters or astronomers measure distance? Lasers! Every bit of information sent over the internet? Lasers. Supermarket scanners? Yep, they’re lasers too!

In fact, even laser guns, like what we see in science fiction cinema such as Star Wars and Doctor Who, are slowly making their way into reality!  Well, maybe not laser guns (not unless you count DIY projects like this monstrosity), but laser cannons are fully-operational.

The LaWS aboard the bridge of the USS Ponce. Photo: John F. Williams via Wikimedia Commons

One such cannon is known (imaginatively) as the AN/SEQ-3 Laser Weapon System, or LaWS. LaWS is an American “directed energy weapon” which may revolutionise the global arms race. It is currently mounted on bridge of the navy ship USS Ponce. It defends the ship, known as an amphibious transport dock, from hostile threats by firing an array of lasers (rather than a single beam which is susceptible to interference) which can incapacitate or destroy these targets. It has many potential defence applications because it can be tuned to various outputs which vary in their effects, from dazzling a crew member to targeting explosive materials onboard enemy vehicles.

The USS Ponce. Notice the LaWS on the upper deck of the ship. Photo: Daniel M. Young via Wikimedia Commons

What makes the LaWS so potent and efficient however, is the several unique characteristics that lasers have over conventional projectile weapons. Firstly, the beam operates on the infrared wavelength, meaning targets literally never see it coming. Another factor is the cost: each beam costs about $1 to produce, making it much more cost-effective than other short-range conventional defence systems. Additionally, the laser only takes three crew-members and a computer to operate, and ammunition is only limited by its power source requiring no storage space. This means that it is also space and weight effective: a major boon for a transport ship like the USS Ponce. The LaWS has already proven effective; on its test run in 2014, it destroyed a unmanned aerial vehicle (UAV) and a small boat by frying vital parts of their infrastructure.

Don’t expect laser-warfare anytime soon though: these lasers aren’t meant to replace conventional rockets and shells. While the US military is pursuing laser development as part of their continuous power-struggle with other major powers, the LaWS was designated to complement established defence systems. In fact, other projects such as the Electro-Magnetic Railgun make the LaWS appear positively timid…

 

See the LaWS in action here:

For an in depth explanation about the inner workings of lasers check this out!

And to find out more about everyday lasers go to these websites: