| Title | New Metalens Shifts Focus Without Tilting or Moving | |
| Date | Wednesday February 24 2021, @06:35PM | |
| Author | Fnord666 | |
| Topic | ||
| from the like-cooking-a-steak? dept. | ||
Polished glass has been at the center of imaging systems for centuries. Their precise curvature enables lenses to focus light and produce sharp images, whether the object in view is a single cell, the page of a book, or a far-off galaxy.
Changing focus to see clearly at all these scales typically requires physically moving a lens, by tilting, sliding, or otherwise shifting the lens, usually with the help of mechanical parts that add to the bulk of microscopes and telescopes.
Now MIT engineers have fabricated a tunable "metalens" that can focus on objects at multiple depths, without changes to its physical position or shape. The lens is made not of solid glass but of a transparent "phase-changing" material that, after heating, can rearrange its atomic structure and thereby change the way the material interacts with light.
[...] The new lens is made of a phase-changing material that the team fabricated by tweaking a material commonly used in rewritable CDs and DVDs. Called GST, it comprises germanium, antimony, and tellurium, and its internal structure changes when heated with laser pulses. This allows the material to switch between transparent and opaque states -- the mechanism that enables data stored in CDs to be written, wiped away, and rewritten.
[...] "In general when one makes an optical device, it's very challenging to tune its characteristics postfabrication," Shalaginov says. "That's why having this kind of platform is like a holy grail for optical engineers, that allows [the metalens] to switch focus efficiently and over a large range."
[...] The experiments show that a metalens can actively change focus without any mechanical motions. The researchers say that a metalens could be potentially fabricated with integrated microheaters to quickly heat the material with short millisecond pulses. By varying the heating conditions, they can also tune to other material's intermediate states, enabling continuous focal tuning.
Additional coverage on Interesting Engineering.
Journal Reference:
Mikhail Y. Shalaginov, Sensong An, Yifei Zhang, et al. Reconfigurable all-dielectric metalens with diffraction-limited performance [open], Nature Communications (DOI: 10.1038/s41467-021-21440-9)
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printed from SoylentNews, New Metalens Shifts Focus Without Tilting or Moving on 2024-04-19 08:46:16