Friday 24 June 2016

Metamaterial Lens is Thinner than the Light It Bends and Focuses


Light-Warping Metamaterials Lens

A lens has been developed which seems to be thinner than the waves of light it tends to focus which has been made from light-warping metamaterials. It is expected that these lenses may one day replace the heavier glass lensed being utilised in everything from microscopes to phone cameras. A curved glass surface in normal lenses of a few millimetres or even centimetres thick tends to redirect the light rays to a common focal point.

To enhance the image, for instance to remove distortion or ensure different wavelengths of light, all seem to get focused appropriately and one will have to keep adding glass layers.This results in the cameras, telescopes and microscopes being limited in part by the size and weight of the lenses they may need. Reza Khorasaninejad, who has designed the new lens with team led by Federico Capasso of Harvard University, had commented that `virtual reality has the same problem and that they want to have high purpose imaging system but what they will end up having is heavy helmets’.

Metamaterials Bend Light – Common Point

In comparison, metamaterials tends to bend light towards a common point utilising structures which seems to be small or smaller than the wavelengths of the light waves itself. Khorasaninejad states that `the lens is flat though it is called virtual curvature. Utilising a beam of electrons, `nanofins’ had been carved by the team, 600 nanometre-tall blocks which together tend to resemble the worlds’ smallest Stonehenge, from a block of titanium dioxide.

They fixed that lens on a thin piece of glass which tends to provide a stiff backing depriving the focus of any light. Through the titanium oxide lens, the nanofins tend to rotate at various angles in order to capture the polarised light that enables them to pull light rays together. The three lenses were examined, tuned to red, green and violet light and each could focus light more harshly than a 55-millimetre thick Nikon microscope lens having same optical properties although the 600-nanometre-thick metamaterial lens has been 100,000 times thinner than the Nikon.

This design, unlike the earlier metamaterial lenses which seemed to handle visible wavelengths, did not lose much light in the procedure.

Entirely Novel Way of Constructing Lens

John Pendry of Imperial College, London had commented that `this is an entirely novel way of constructing a lens and still cannot compete with a glass lens in handling various colours at once, but several application could work with monochromatic light.

The team has plans in expansion of lens’s colour range. Khorasaninejad has mentioned that `the first step was to make a lens which at least could do a good job in the visible and the next step is to do colour correction’.

According to him the most exciting potential applications is in wearable optics like virtual reality and augmented reality. He further added that `any good imaging system present is heavy since the thick lenses need to be stacked on top of each other and no one desires to wear a heavy helmet for a couple of hours.

This technique could reduce weight and volume and shrink lenses thinner than a sheet of paper and imagine the possibilities of wearable optics, flexible contact lenses or telescopes in space’.

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