The researchers suspended a metasurface on square silicon chip in a thin-film PZT MEMS-actuated ring (yellow). (Credit: Christopher Dirdal, SINTEF Smart Sensors and Microsystems)

A metasurface lens has been created that uses a piezoelectric thin film to change focal length when a small voltage is applied. Because it is extremely compact and lightweight, the new lens could be useful for portable medical diagnostic instruments other applications where miniaturization can open new possibilities.

The researchers made the new lens using metasurfaces — flat surfaces that are patterned with nanostructures to manipulate light. They can integrate several functionalities into a single surface and can also be made in large batches using standard micro- and nanofabrication techniques at potentially low cost.

Tunability, or adaptivity, in conventional optical systems is typically accomplished using bulky and power-consuming components such as stepper motors, rotators or magnets. To create this capability on a smaller scale, the researchers turned to MEMS technology. These chip-based electrically controlled mechanically moveable parts are fast, require little power and are also compatible with high-volume batch processing techniques, which can reduce the size, cost, and weight of optical systems.

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