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## Specially Scratched Eyeglasses Allow Clear, Focused Vision at Any Distance

Glasses-wearers, take hope: An Israeli professor named Zeev Zalevsky has developed a method of lens engraving that allows for clear, focused eyesight from any distance from 33 centimeters away to the horizon. In fact, if you were to wear these glasses and look through the channel of rings described below, everything would be in perfect focus at once. But could you handle that?

New Scientist reports:

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, says Zalevsky.

The rings shift the phase of the light waves passing through the lens, leading to patterns of both constructive and destructive interference. Using a computer model to calculate how changes in the diameter and position of the rings alter the pattern, Zalevsky came up with a design that creates a channel of constructive interference perpendicular to the lens through each of the 25 structures. Within these channels, light from both near and distant objects is in perfect focus.

“It results in an axial channel of focused light, not a single focal spot,” Zalevsky says. “If the retina is positioned anywhere along this channel, it will always see objects in focus.”

Zalevky’s solution has its drawbacks, however: For one thing, the contrast between images would be reduced, and for another, if you looked outside of the main channel, you’d lose focus. Then there’s the question of simultaneous perfect focus: As one Redditor put it, “The whole world will look like a 3D game engine from the time before graphics cards simulated depth-of-field.”

(New Scientist via Neatorama. Title pic via Ron Hanko’s Flickr. | Professor Zalevsky’s website)

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