Groundbreaking new lens will make future AR glasses lighter

A groundbreaking new lens will make future augmented reality (AR) glasses lighter and less obtrusive, replacing complex displays with a revolutionary alternative.

Metalenses use nanostructures to focus different colours of light on a single, flat surface unlike traditional lenses that stack multiple lenses to achieve the result. However, their potential, until now has been more theoretical than practical.

Although advances in modern AR and VR headsets have seen them shrink down in bulk and weight, the optical requirements inevitably have to deal with the rules of physics.

This requires the lenses to focus the whole visible spectrum and white light, but the different properties of each light wavelength makes that tricky.

Since blue wavelengths are slower to pass through glass than, say, red wavelengths, they do not reach the eye simultaneously, which results in chromatic  aberration.

This has, until now been sought to be addressed using multiple lenses with different thicknesses, materials, curves, and treatments that, when stacked together, even the optical performance for all the wavelengths involved. This however, makes the lens assembly quite hefty.

Researchers at the Harvard John A Paulson School of Engineering and Applied Sciences (SEAS) believe that they have a solution to the problem of replacing such lens assemblies. It makes use of metalenses, a flat surface that uses nanostructures to focus light and thus avoid chromatic aberration.

The laboratory research was published on Monday in the journal Nature Nanotechnology.

''Metalenses have advantages over traditional lenses,'' Harvard physicist Federico Capasso, the study's senior author, said in a statement. ''Metalenses are thin, easy to fabricate, and cost-effective. This breakthrough extends those advantages across the whole visible range of light. This is the next big step.''

"This brings us one step closer to the goal of incorporating them into common optical devices such as cameras,'' said study co-author Alexander Zhu.