Exeter physicist bends light waves on surfboards

Aug 06, 2012
Exeter physicist bends light waves on surfboards
Image: Jim Wileman

(Phys.org) -- Scientists across the globe are trying to develop materials that can refract light to create ‘invisibility cloaks’, which are of particular interest to the aerospace industry. ‘Invisibility cloaking’ means building properties into a material that allow the device to guide light waves around an object, making it invisible.

Dr Matt Lockyear grew up in Exeter and completed his undergraduate Physics degree at the University of Exeter as a mature student. He returned for his PhD after working as an engineering manager at BNFL Sellafield, and now works as a Research Fellow in the Electromagnetic and Acoustic Materials Group in Physics. His research focuses on metamaterials: materials that consist of specifically engineered ‘pseudo-atoms’ to provide bulk material or interface properties that are not found in nature.

For his work, Dr Lockyear needed to find a material that is uniformly dense, and in response to electromagnetic radiation, behaves in a similar way to air. He discovered that the foam inside his surfboards was ideal for his experiments. Luckily, his friend Tris Cokes owns the Redruth-based surfboard blank manufacturing company Homeblown. Tris was able to provide him with samples of the material, and then lent him the factory to test the loading of the foams with high refractive index powders.

Dr Lockyear has recently built what he describes as a ‘surface wave black hole’ using the surfboard foam. He has created a circle of material that has a radially graded index (the higher the index, the slower the light travels through the medium), and placed it on the surface of a metamaterial. The radiation propagating across the metamaterial is then refracted, spiralling inwards to an absorbing core. Dr Lockyear is now working on the surface wave invisibility cloak as a stepping stone to his current research project’s ultimate goal, a free space 3D .

Dr Matt Lockyear said: “I never thought I’d be able to combine my passion for physics with my love of surfing - usually one competes with the other. But the foam inside the boards I’ve been riding for all these years has proved absolutely perfect for my research. I was having a discussion with a colleague regarding suitable materials for the project whilst looking at one of Tris’s foam blanks propped up against the office wall, which I had been meaning to turn into a 6ft 10 single fin pintail. I am also very lucky to have an office opposite the theory guys who, quite literally, wrote the book on transformation optics.”

The Electromagnetic and Acoustic Materials group undertakes pioneering studies with metamaterials and is developing new designs for radio frequency identification, anti-counterfeiting, and sound proofing technologies. The group’s research is primarily built around the development and subsequent study of metallic surfaces with exceptional properties and a range of applications.

Dr Lockyear’s interests including stealth materials, light-weight flexible ultra-thin radar absorbers, cloaking, beam steering, smart antennas, electronic tagging and frequency selective wallpaper, and of course surfing.

Explore further: The risks of blowing your own trumpet too soon on research

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User comments : 7

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DarkHorse66
not rated yet Aug 06, 2012
That not only thinking outside of the square, but a nice way to combine your work and play too!

Cheers, DH66
antialias_physorg
not rated yet Aug 06, 2012
Combine this with the one way propagation filter for photons
http://phys.org/n...tic.html
and you have the ultimate thermos.

(Or just a machine that sucks up ambient energy and puts it in a heat core...which could have all kinds of neat uses...maybe even 'free' AC / 'free' energy)
SoylentGrin
not rated yet Aug 06, 2012
How about making the surfboard invisible to water waves?
...or would that be the opposite of a surfboard? The ocean is smooth as glass all around it...
DarkHorse66
not rated yet Aug 06, 2012
How about making the surfboard invisible to water waves?
...or would that be the opposite of a surfboard? The ocean is smooth as glass all around it...

Actually, you would see a surfboard shaped indentation in the water, and the rider appearing to be standing/gliding in mid-air, keeping pace with the, apparently, empty space.... Now, THAT would be a way to look as though you were walking on water! ;D
Cheers,DH66
antialias_physorg
not rated yet Aug 06, 2012
How about making the surfboard invisible to water waves?

...which would sink like a rock.
DarkHorse66
not rated yet Aug 06, 2012
How about making the surfboard invisible to water waves?

...which would sink like a rock.

If you are talking about high-index materials being heavy. And needing to be really thick. How much of a correlation is there between index, mass, density etc? Does the thickness of the material NEED to be high too? I haven't had lectures on that kind detail yet. I'm just trying to understand the reasoning behind your comment.
Regards, DH66
antialias_physorg
5 / 5 (3) Aug 06, 2012
If you are talking about high-index materials being heavy. And needing to be really thick.

I was talking about if you create a material that would let a wave/water pass (i.e. an assembly of atoms which transfers momentum to your board) then you will have no force that holds your board up against the drag of gravity.

In metamaterials photons pass around the object. If you were to extend this to actual atoms then you have something where the water just 'passes around it' without interacting. And if it passes from the bottom around it to the top then you sink.

Though that is just a bit of fun, since the effective wavelength of atoms is incredibly short. so I'm not expecting 'matter metamaterials' for all wavelengths in the immediate future.

In ship design there may be an application, though. If you have a characteristic bow wave at normal crusing speed then one could probably design a hull so that that one would pass around it without producing (much) drag.