The inventors of a new spiral-shaped lens they say offers clear focus at different distances in varying light conditions believe the design could overcome current optical limitations in progressive, intraocular and contact lenses.
Described in Optica, the researchers have coined the term ‘spiral diopter’ for their lens. It is designed to create many separate points of focus – akin to having multiple lenses in one.
“Unlike existing multifocal lenses, our lens performs well under a wide range of light conditions and maintains multifocality regardless of the size of the pupil,” said Dr Bertrand Simon from Photonics, Numerical and Nanosciences Laboratory (LP2N), a joint research unit between the Institut d’Optique Graduate School, the University of Bordeaux and the CNRS in France.
“For potential implant users or people with age-related farsightedness, it could provide consistently clear vision, potentially revolutionising ophthalmology.”
In addition, Simon said the simple design of this lens could benefit compact imaging systems.
“It would streamline the design and function of these systems while also offering a way to accomplish imaging at various depths without additional optical elements. These capabilities, coupled with the lens’s multifocal properties, offer a powerful tool for depth perception in advanced imaging applications.”
The inspiration for the spiral lens design came when the paper’s first author, Mr Laurent Galinier from SPIRAL SAS in France, was analysing the optical properties of severe corneal deformations in patients. This led him to conceptualise a lens with a unique spiral design that causes light to spin, like water going down a drain.
This phenomenon, known as an optical vortex, creates multiple clear focus points, which allow the lens to provide clear focus at different distances.
“Creating an optical vortex usually requires multiple optical components,” said Galinier. “Our lens, however, incorporates the elements necessary to make an optical vortex directly into its surface. Creating optical vortices is a thriving field of research, but our method simplifies the process, marking a significant advancement in the field of optics.”
The researchers created the lens by using advanced digital machining to mould the unique spiral design with high precision. They then validated the lens by using it to image a digital ‘E,’ much like those used on an optometrist’s light-up board.
The authors said the image quality remained satisfactory regardless of the aperture size used. They also discovered that the optical vortices could be modified by adjusting the topological charge, which is essentially the number of windings around the optical axis. Volunteers using the lenses also reported noticeable improvements in visual acuity at a variety of distances and lighting conditions.
The researchers are now working to better understand the unique optical vortices produced by their lens. They also plan to perform systematic trials of the lens’ ability to correct vision in people to comprehensively establish its performance and advantages in real-world conditions.
In addition, they are exploring applying the concept to prescription spectacles, which could potentially offer users clear vision across multiple distances.
“This new lens could significantly improve people’s depth of vision under changing lighting conditions,” said Simon.
“Future developments with this technology might also lead to advancements in compact imaging technologies, wearable devices and remote sensing systems for drones or self-driving cars, which could make them more reliable and efficient.”