Camera phone photographers can soon compete with professionals

Scientists have developed a super-thin lens that can function either as a convex or a concave lens with the flick of a switch. It means a scene can either be magnified or viewed at wide angle.

It could provide a new generation of small lenses used in devices such as mobile phones and tablet computers, allowing keen photographers to capture images that previously required expensive SLR lenses.

Dr Shuang Zhang, a reader in metamaterials at the University of Birmingham who led the research team, said: "This new device will give greater flexibility in designing and adding new functionalities to optical systems.

"The focusing properties of the same lens can be altered between a convex lens and a concave lens at will. Furthermore, the compact size, and the flat nature of the lens could useful."

The scientists created the lens, known as a plasmonic metalens, by layering gold nano-rods onto a thin, flat shard of glass half the width of a human hair.

Conventional lenses use curved glass surfaces to alter the direction of the light as it enters a camera to either magnify an object or make it smaller.

The layer of gold rods on top of the new lens, however, allows this effect to be achieved on a flat surface by controling the direction the light travels as it passes through the glass.

A prototype of the lens created by the researchers has an aperture of 80 micrometers - roughly the width of a human hair - and a focal length of 60 micrometers.