It can be a hassle, taking your glasses on and off to switch between near and distant vision. There are bifocals, of course, plus there are now glasses on which you can adjust the focus. Scientists from the University of Utah, however, have gone one better – they've developed glasses that change focus automatically, depending on what you're looking at.

Created by a team led by Prof. Carlos Mastrangelo and doctoral student Nazmul Hasan, the glasses feature "liquid lenses" that change shape.

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Each lens is made up of two clear rubber membranes – one in the front and one in the back – with a layer of clear viscous glycerin sandwiched between them. Three mechanical actuators push the rear membrane in and out, compressing or releasing the glycerin and thus changing the curvature of the lens. This, in turn, changes its focal length.

It's not unlike the technology utilized in the Adlens adjustable-focus glasses, although they're operated manually. By contrast, the Utah glasses incorporate an electronic distance meter in the bridge, which uses pulses of infrared light to determine how far away objects are from the eyes. Whenever that distance changes, it instructs the actuators to reshape the lenses accordingly. They do so in a claimed 14 milliseconds.

The first time that a person uses the glasses, they calibrate them to their optical prescription via Bluetooth using a smartphone app. From that point on, they only need to recalibrate them as their prescription changes.

According to Mastrangelo, a rechargeable battery in a commercial version of the specs should be good for over 24 hours of use. That final version of the glasses – which will be considerably lighter and less bulky than the current prototype – may be commercially available within three years. The technology is currently being developed by spinoff company Sharpeyes.

A paper on the research was recently published in the journal Optics Express.

Source: University of Utah

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