For centuries, polished glass has been at the heart of imaging systems. Lenses’ precise curvature allows them to focus light and produce sharp images, whether the object in view is a single cell, a book page, or a distant galaxy. To see clearly at all of these scales, the zoom lens must be physically moved by tilting, sliding, or otherwise shifting the lens, usually with the assistance of mechanical parts that add to the bulk of microscopes and telescopes.
Engineers have now created a tunable zoom lens (metalens) that can focus on objects at various depths without changing their physical position or shape. The tunable lens is made of a transparent “phase-changing” material that, when heated, can rearrange its atomic structure, changing how the material interacts with light.
The zoom lens’s focus can be adjusted without using bulky mechanical elements. The novel design, which currently images in the infrared band, could pave the way for more agile optical devices such as miniature heat scopes for drones, ultracompact thermal cameras for cellphones, and low-profile night-vision goggles.
The results show that their ultrathin tunable lens, which has no moving parts, can achieve aberration-free imaging of overlapping objects at different depths, competing with traditional, bulky optical systems.
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