When you think of a lens, you think of a glassy material used for focusing light, right?
Did you know that there are lenses that can focus sound? That’s not even the new development I’m going to talk about. Acoustic lenses have existed for years.
So what’s new here then?
What’s new is that researchers from Graduate Aerospace Laboratories and our prolific buddies at the California Institute of Technology have created a metamaterial lens that can focus and amplify sounds 100 times better than any other similar lens.
You may remember hearing about metamaterials. They’ve been in the news a lot the past few years. The most common Metamaterials are engineered structures designed to interact and influence electromagnetic waves. These metamaterials can bend light around objects invariably causing everyone to compare the tech to Harry Potter’s invisibility cloak. Metamaterials can be used to influence not only electromagnetism but acoustic energy as well. This is exactly what these scientists have done.
The metamaterial used in these experiments consisted of 411 small steel balls arranged in 21 x 21 array.
The inspiration was apparently a toy called Newton’s cradle.
I’m sure most of you have seen or played with one of these. As you can see, it has 5 or so metal balls next to each other suspended from above. You take one ball, move it away from the others, let it go and it slams into the next ball but the ball at the far end is the one that moves away with similar energy as the original and it comes back down and reverses what just happened. This is a great tool for demonstrating conservation of energy and momentum, how a pendulum works, friction etc. It’s a veritable physics class unto itself.
It is also very similar to what this new metamaterial lens does.
The pressures of steel spheres against each other in the lens are modified in such a way that when something hits the back end of this device a few things happen
The first is that instead of motion being channeled through like a Newton’s Cradle, it’s a shockwave of sound that passes through; this is called a solitary wave
The length of all the touching spheres also apparently causes this energy to exit that last row as sound instead of reverberating back through the device.
The key to this process though is that the spheres amplify and focus the shock-wave a hundredfold as it travels from one row or chain to another.
For an analogy. Imagine if this device was configured to accept sound and you go up to it and just speak a normal sentence into it. This would then be turned into an “ear drum rupturing explosion”
As you might imagine, the potential applications are pretty interesting.
From a medical perspective, a future version of this device could be focused on a tumor deep under the skin. The high pressure sound that hit the tumor would raise its temperature until it was obliterated yet it would leave surrounding tissue unaffected.
One could also use it to make images of your insides. These images could be much higher resolution than common ultrasound images. There would also be no radiation risks common to other imaging tools like x-rays.
The military of course could get their toys from this as well. These sound bullets, as they’ve been called, are essentially unaffected by hard substances like water or rock. It would be like shooting a bunch of ethereal bullets that could go through anything until they all converged on a point deep in the material.
Some predict this tech could one day make “submarine melting waves of pressure ” or “shock waves powerful enough to destroy caves otherwise untouchable by conventional weapons”.
My personal hope is that we’ll use this tech to make a weirding module to aid me in my quest to be Muad’Dib, thank you very much.