Lenses at the nano-scale

A flat lens measured in nanometres could represent a giant leap forward for spectacles and contact lenses.

Researchers at the Harvard John A Paulson School of Engineering and Applied Science have designed a lens based on a specialised array of titanium dioxide ‘nanofins’ on a glass substrate.

This patented structure – known as a ‘metasurface’ – bends the light as it passes through, according to the paper published in the journal Science.

The technology could replace the current lenses in spectacles and contact lenses, which are ground and shaped into corrective optical curves by specialised machines.

The published research was on a static ‘metalens’ lens, but physics researcher, Professor Federico Capasso, told OT that: “We are right now working on a lens technology that is adjustable.

“Once we do that it should be possible to apply this technology and concept to making an adjustable contact lens,” he explained.

One of the most exciting things about the titanium dioxide nanostructure is that it affected light across the whole visible spectrum, Professor Capasso said.

The manufacturing process could also revolutionise the industry, he explained, adding: “In the near future, metalenses will be manufactured on a large scale at a small fraction of the cost of conventional lenses, using the foundries that mass produce microprocessors and computer chips.”

The technology will have applications for the lenses in microscopes and cameras as well, but the researchers said “one of the most exciting” potential areas is wearable optics, particularly virtual and augmented reality.

Image credit: Peter Allen/Harvard John A. Paulson School of Engineering and Applied Science