A new way of seeing - meta-material lens with ten times more power

29 October 2013

School of Physics researchers have developed a meta-material lens with ten times the resolution of any current lens, making it a powerful new tool for the biological sciences. The results were published in Nature Communications on October 29 2013

Dr Alessandro Tuniz and his team have developed a meta-material lens, a powerful tool for biological science.
Dr Alessandro Tuniz and his team have developed a meta-material lens, a powerful tool for biological science.

"This advance means we can unlock previously inaccessible information on the structure of molecules, their chemical make-up and the presence of certain proteins," said lead author Dr Alessandro Tuniz.

Dr Tuniz, a postdoctoral associate at the University, said, "This opens up an entirely new tool for biological studies. It could allow earlier skin cancer diagnosis, because smaller melanomas can be recognised. For breast cancer, it can also be used to more accurately check that all traces of a tumour have been cut out during surgery."

The four member research team from the University's School of Physics, including Alessandro Tuniz, are all authors on the paper. They created the lens using fibre optic manufacturing technology.

The lens is a metamaterial - a material with completely new properties not found in nature.

Metamaterials are novel artificial materials with unprecedented electromagnetic properties emerging from their structure rather than from their chemical composition. Because they enable the manipulation of light in ways that were unthinkable before them, metamaterials promise an entire range of greatly improved or even previously impossible devices. One such example is microscopes overcoming the diffraction limit, allowing to image details much below what conventional optics would allow.

The meta-material fibre consisting of a long continuous array of metal microwires
The meta-material fibre consisting of a long continuous array of metal microwires

Making the lens was not a matter of making a better form of the lenses already in existence but of making a lens which uses light waves in a way not previously possible.

"Creating metamaterials is a cutting-edge area of science with a massive range of potential uses from aerospace to solar power, telecommunications to defence," said team member Dr Boris Kuhlmey.

"The major challenge is making these materials on a scale that is useful. This is one of the first times a metamaterial with a real world application, quickly able to be realised, has been feasible. Within the next two to three years, new terahertz microscopes that are ten times more powerful than current ones will be possible using our metamaterial.

"We know of only two or three other cases worldwide, including for wireless internet and MRI applications, where metamaterials could also be put into practice in the next couple of years."

The potential to create a new high power lens, able to see much finer details than using conventional lenses was spotted almost a decade ago. It has taken until now to make the lens on a useful scale, a thousand times smaller than the early experimental models.

While many proof-of-concept experiments have been demonstrated over the last few years, a major difficulty with bringing metamaterials into real-world applications is that they require to be structured at a very small scale, throughout the entire, bulk material. This is extremely difficult or even impossible with current nano- and micro- fabrication techniques, which can only pattern surfaces rather than volumes.

To solve this problem, over the last few years we have developed a technique based on the technology used for fabricating optical fibres, demonstrating a lens that is agnostic to the laws of diffraction, allowing us to focus light down to a spot 27 times smaller than the wavelength at terahertz frequencies, and also image details of the same size.

"While the principle of such hyperlenses has been known for several years, and a few experiments have successfully demonstrated they can work, this is the first time such a lens is made with a technique scalable to mass production, and the first time light is able to carry such minute details over distances much longer than the wavelength itself."

"The difficulty was making large quantities of matter structured on a micrometric scale," said Dr Tuniz.

The new lens, made of plastic and metal, uses terahertz waves, electromagnetic waves with frequencies higher than microwaves but lower than infrared radiation and visible light. It operates in a region of the spectrum where very few other optical tools are available and all of them have limitations, in particular in terms of resolution.

"If we think of this in comparison to an X-ray which allows us to see inside objects at a high resolution but with associated danger from radiation, by contrast our metamaterial lens allows us not only to see through some opaque materials, but also to gather information on their chemical composition, and even information on interaction between certain molecules, without the danger of X-rays," said Dr Tuniz.

This means the lens is perfectly suited to analysing the delivery of drugs to cells, which is crucial to medical research.

This research was undertaken with the Freiburg Materials Research Centre from the University of Freiburg and supported by the Australian Research Council, and the Australian National Fabrication Facility using commonwealth and NSW state government funding.

Read the article published in Nature Communications here

Contact: Tom Gordon

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