New 'hyperlens' to help us see tiny objects

A new slinky lookalike hyperlens can help us see tiny objects that elude even the most powerful optical systems, scientists say.
The metamaterial hyperlens may someday help detect some of the most lethal forms of cancer, researchers said.
It could also lead to advancements in nanoelectronic manufacturing and boost scientists' ability to examine single molecules - a development with implications in physics, chemistry, biology and other fields.
"There is a great need in health-care, nanotechnology and other areas to improve our ability to see tiny objects that elude even the most powerful optical systems. The hyperlens we are developing is, potentially, a giant step toward solving this problem," said Natalia Litchinitser, professor of electrical engineering at the University at Buffalo and the paper's lead author.

Conventional optical systems, such as microscopes and cameras, are limited by diffraction, a phenomena in which light bends as it passes around an edge or through a slit.
An example of this are the closely spaced tracks of a DVD, which form a rainbow pattern when looking at the disk.

Diffraction sets a fundamental limit to the resolution of optical systems.
Scientists are working to solve diffraction with metamaterials, which are materials engineered to have properties not yet discovered in nature.
Typically, the materials are arranged in repetitive patterns, often smaller in scale than the wavelengths of the phenomena they influence.

Metamaterial hyperlenses overcome the diffraction limit by transforming decaying evanescent waves into propagating waves.
Once converted, the former decaying waves, which were commonly lost in conventional imaging, can be collected and transmitted using standard optical components.
Some of the first metamaterial hyperlenses consisted of tiny concentric rings of silver and dielectric (an insulating material).
However, this design only works within a narrow range of wavelengths and it suffers from large losses of resonance.
Instead of concentric rings, researchers formed tiny slivers of gold and PMMA (a transparent thermoplastic) into a radial shape.
The design of this metamaterial hyperlens, which looks like a Slinky suspended in motion, overcomes the diffraction limit in visible frequency range.

Moreover, it can be integrated with an optical waveguide, opening the door to hyperlens-based medical endoscopes.
Such a tool could improve doctors' ability to detect some of the most lethal forms of cancer, such as ovarian cancer, researchers said.
For example, today's high-resolution endoscopes can resolve objects to about 10,000 nanometers. The hyperlens could improve that to at least 250 nanometers or better.
The research was published in the journal Nature Communications.