New "metalens" shifts focus without tilting or moving
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.