Are auto-focusing glasses a thing of the … present?

1 Feb 2017

Early prototype of ‘smart glasses’ with liquid-based lenses that can automatically adjust focus. Image: Dan Hixson/University of Utah College of Engineering

Lasers, batteries, glycerine and some very clever engineering may mean reading glasses are a thing of the past, as ‘auto-focusing’ bifocals are developed in the US.

University of Utah engineers have developed a set of ‘smart glasses’ that adapt to environments and focus on objects within 14 milliseconds.

Led by Prof Carlos Mastrangelo and doctoral student Nazmul Hasan, the study built a prototype that saw liquid-based lenses automatically adjust to objects the wearer is looking at.

In an attempt to copy the way an eye adjusts focal depth with its lens, the study – published in Optics Express – could offer a replacement for glasses that some humans naturally need as their eyes age and their ability to focus fades.

Making lenses out of glycerin, the thick colourless liquid is enclosed in flexible membranes. These membranes are connected to actuators that manipulate the shape of the lens ever so slightly, changing the curvature, which adapts the focus.

“The focal length of the glasses depends on the shape of the lens, so to change the optical power we actually have to change the membrane shape,” said Mastrangelo.

The industrial-looking frames are loaded with batteries and electronics. An infrared light is in the bridge, measuring distances to help the glasses choose what objects to focus on.

The duo claim it takes just 14 milliseconds to focus on different objects, with rechargeable batteries lasting 24 hours.

University of Utah Professor Carlos Mastrangelo, right, and doctoral student Nazmul Hasan. Image: Dan Hixson/University of Utah College of Engineering

From left: Doctoral student Nazmul Hasan and Prof Carlos Mastrangelo. Image: Dan Hixson/University of Utah College of Engineering

“Most people who get reading glasses have to put them on and take them off all the time,” said Mastrangelo. “You don’t have to do that anymore. You put these on, and it’s always clear.”

To tailor the glasses to users, prescriptions are filed into a complementary app, adjusting the information as their needs change over time.

The prototype is too bulky to properly market at the moment, though now that the science has been proven, the team is hoping to design changes that will reduce the size and weight of future models. The hopes are that a commercial product can be developed within three years.

Gordon Hunt was a journalist with Silicon Republic