Smart Glasses Eliminate Bifocal Zones with Switchable Liquid Crystals
New research demonstrates liquid crystal technology capable of dynamically adjusting focus in eyewear, potentially replacing traditional bifocals and offering benefits for digital device integration.
Scientists have developed a new type of eyewear utilizing liquid crystals to switch focal points, eliminating the segmented zones characteristic of bifocal and progressive lenses. The technology, detailed in a study published in Physical Review Applied, employs a gradient refractive index (GRIN) lens that adjusts refractive power by changing the orientation of liquid crystals within a thin cell – a process requiring minimal power and lacking moving parts.
The innovation addresses a common complaint with progressive lenses: edge distortions, often referred to as the “corridor effect,” which can be distracting for some users. Unlike earlier liquid crystal Fresnel designs limited by diffraction artifacts,the GRIN lens aims to deliver image quality comparable to standard glass lenses.
The technology could initially benefit individuals whose jobs require frequent shifts between near and far vision, such as those performing detailed inspection work followed by broader spatial awareness.
This isn’t the first attempt at variable focus eyewear. Joshua Silver, at Oxford University, pioneered low-cost, fluid-filled glasses tunable by pumping liquid to alter curvature, providing vision correction in areas with limited access to eye care. However, liquid crystal systems offer a different approach, relying on electrical adjustments rather than mechanical pumping. A recent review published in PubMed highlights the potential for liquid crystal (LC) lenses to be compact, stable, and adjustable, while acknowledging design tradeoffs related to response speed, optical power range, and image quality.
Beyond addressing age-related near vision loss and reducing neck strain, the technology has implications for the future of digital displays. Wearable devices and headsets require compact, rapidly refocusing optics, and a liquid crystal cell controlled by voltage presents a compelling building block.Researchers identified two key areas for future growth: widening the active viewing area and accelerating the electronics’ focusing speed for enhanced user comfort. The underlying physics is established, and the materials are familiar to display manufacturers, suggesting a pathway toward commercialization if costs can be managed.
