Homing glasses

Smart glasses taught to focus automatically on the observed object

Nikolay Vorontsov, N+1

Researchers from the University of Utah have developed smart glasses that can independently focus on the object of observation depending on the distance. Article by Hasan et al. Tunable-focus lens for adaptive eyeglasses is published in Optics Express.

People suffering from presbyopia ("senile vision") have difficulty focusing on small details or small print due to age-related loss of elasticity of the lens. As a rule, such patients are prescribed glasses that are not intended for permanent wear and are worn only when necessary – for example, when reading. One of the main problems of this approach is that it is difficult for a person with presbyopia to perform tasks that require focusing on objects at different distances – you have to constantly take off and put on glasses, which can sometimes be a difficult action. As an example, driving a car can be cited – presbyopia does not allow the driver to see the readings of the instruments or the navigator, but does not interfere with the overview of the road situation as a whole.

Scientists have developed a prototype of glasses with liquid lenses that refocus independently depending on the distance to the observed object. Each lens is a sealed flat container with transparent membranes, inside of which there is glycerin. Both membranes are elastic, but a rigid transparent element acting as a piston is fixed on one of them. There are bimorphic piezoelectric elements attached to the piston around the piston, which bend when a current is applied and move the piston along the optical axis of the lens. Thus, along with the movement of the piston, the curvature of the lens changes.

Schematic arrangement of the lens and demonstration of the mechanism of curvature change
by moving a transparent piston (from an article in Optics Express).

Designed glasses with an aperture aperture of 32 millimeters have a focusing range of 5.6 diopters – on average, the same indicator of the human lens is about 11 diopters in 20 years and falls over the course of age up to 2 diopters in 50 years. With the help of a distance sensor, the glasses can detect the object of observation and refocus in 15 milliseconds, while the device is capable of continuously operating on a single battery charge built into the frame for six hours.

Lens with piezoelectric elements installed
(here and below are pictures from the University of Utah press release I can see clearly now).

At the moment, the manufactured glasses are a bulky prototype, but researchers are already working on a more advanced version with tracking the direction of view and an optical depth sensor to more accurately determine the object of observation in the field of view. According to one of the authors of the article, the glasses can become a mass-produced product within two to three years and will cost around 500 or 1000 dollars.

Portal "Eternal youth" http://vechnayamolodost.ru  31.01.2017