A flat lens made of paint whitener on a sliver of glass could revolutionise optics, according to its US inventors.

Just 2mm across and far thinner than a human hair, the tiny device can magnify nanoscale objects and gives a sharper focus than top-end microscope lenses.

It is the latest example of the power of metamaterials, whose novel properties emerge from their structure.

Shapes on the surface of this lens are smaller than the wavelength of light involved: a thousandth of a millimetre.

"In my opinion, this technology will be game-changing," said Federico Capasso of Harvard University, the senior author of a report on the new lens which appears in the journal Science.

The lens is quite unlike the curved disks of glass familiar from cameras and binoculars. Instead, it is made of a thin layer of transparent quartz coated in millions of tiny pillars, each just tens of nanometres across and hundreds high.

Singly, each pillar interacts strongly with light. Their combined effect is to slice up a light beam and remould it as the rays pass through the array.