London, Oct 5 (ANI): A researcher at Bar-Ilan University in Ramat Gan, Israel has created the perfect glasses - whose lenses allow you to see clearly regardless of how long or short-sighted you are.
A condition called presbyopia leaves people who are already short-sighted unable to focus on either near or distant objects. Bifocals offer a solution by having two lenses in the same frame, but users must get used to tilting their head up or down to switch focus.
Zeev Zalevsky has developed a technique to turn a standard lens into one that perfectly focuses light from anything between 33 centimetres away and the horizon, reports New Scientist.
It involves engraving the surface of a standard lens with a grid of 25 near-circular structures each 2 millimetres across and containing two concentric rings. The engraved rings are just a few hundred micrometres wide and a micrometre deep.
"The exact number and size of the sets will change from one lens to another," depending on its size and shape, said Zalevsky.
However, the glasses have one drawback - the interference pattern tends to cancel out some of the light passing through the lens, which reduces the contrast of images viewed through it.
Pablo Artal of the University of Murcia, Spain, warns that if the contrast reduction becomes too large, the brain will struggle to interpret the information.
But Zalevsky said that people wearing the lenses do not notice a loss in contrast because the eye is very sensitive to light at low intensity.
He says that the brain adapts to and minimises the reduced contrast within a few seconds. (ANI)