Lenses with a cool spiral design could offer an alternative to traditional multifocal lenses. They seem to produce clearer images than standard multifocals, even in low light.
The lenses were created by inventor Laurent Galinier. When Bertrand Simon of the French Institute of Optics met Galinier through a scientific collaboration, he immediately wanted to test the lenses in the laboratory.
The lens is round like a conventional contact lens, but has a carefully rolled spiral created with a lathe on its surface. This spiral shape modifies the path that light rays follow through the lens, meaning that the lens does not have a single focal point but several, some closer to the lens and others further away from it.
It’s unclear exactly how the spiral shape accomplishes this, but Simon says it appears to twist light rays and create optical vortexes, like mini tornadoes of light, that somehow interact with each other.
In the lab, Simon and his colleagues analyzed the laser light passing through the spiral lenses and simulated the process on a computer. In a direct comparison to a conventional multifocal lens, the spiral lens offered more clarity and detail when a lot of light passed through and still performed well in low light conditions.
For this reason, spiral lenses could be suitable in various lighting conditions: for example, they could be useful for people who wear multifocal lenses while driving at night, Simon says. He tried a pair of spiral contact lenses himself and says that, although the rigid material was uncomfortable to touch his eye, it saved him the effort of having to take off his glasses to look at his phone. With the spiral lenses he could see the screen clearly.
James Wolffsohn of Aston University in the United Kingdom says that many people experience problems focusing on close objects even if their distance vision has been corrected. Innovations like spiral lenses are promising, he says, but only through clinical trials can we demonstrate what a big difference the new technology can make for people.
Simon says it may be possible to create more compact cameras by replacing some of their lenses with spiral lens versions, but the team first wants to do more testing to explore the underlying science of spiral light.