Lens five times thinner than paper developed
Scientists at Canada's Universite Laval have invented a lens that is five times thinner than a piece of paper and can zoom without using mechanical parts. The lens is created by adding a small quantity of photosensitive material to a liquid crystal cell. When a weak electrical current is applied, the crystals realign differently from those in the periphery and thus take on the shape and behavior of a lens. The researchers have been able to modify the lens’ focal distance from 1.6 to 8 meters in a few milliseconds by increasing the voltage from 1.5 to 4.5 volts.
Scientists invent lens five times thinner than a sheet of paper
Québec City, May 18, 2005 – Scientists from Université Laval’s Faculty of Sciences and Engineering have invented a lens five times thinner than a sheet of paper that is able to zoom in and out without mechanical parts. Tigran Galstian and Vladimir Presnyakov present this amazing piece of optical instrumentation in the latest issue of the Journal of Applied Physics.
“There are several possible applications for such a lens. We believe one of its most promising developments could be in camera-embedded cell phones,” says Galstian. “Our opto-electrical zoom lens would be of much higher quality than the ones that currently equip these phones.”
The digital zooms now used in camera phones only enlarge part of a picture without enhancing its quality, giving sometimes disappointing results. Other than its size, the greatest advantage of the lens invented by the two Université Laval researchers is that it allows for the movement of the focal point – as with a real camera – thus increasing the clarity, detail, and overall quality of an enlarged picture.
Such a technology could help boost a market that seems to be losing its snap. According to a recent market study by one of the major camera makers, a significant number of camera phone owners find their devices less than satisfying, mentioning among other problems the poor picture quality.
The lens is made by adding a small quantity of photosensitive material to a liquid crystal cell. When the material is exposed to laser light, it forms a network of stable polymers varying in density according to the intensity of exposure. “The network is like a spiderweb, with its center denser than its periphery,” explains Galstian. “When we apply a weak electrical current to it, the crystals in the center realign differently from those in the periphery and thus take on the shape and behavior of a lens.”
The curve of the lens – its focal point – can be modified by changing the intensity and frequency of the electrical current. The researchers have thus been able to modify the lens’ focal distance from 1.6 to 8 meters in a few milliseconds by increasing the voltage from 1.5 to 4.5 volts. “The reaction is very fast and doesn’t involve any mobile parts or mechanical movements.” The focal point of the lens can go from 60 centimeters to infinity.