The lenses are built from an array of cylindrical silver nanoparticles and a layer of polymer patterned into blocks on top of the metal array. By controlling the arrangement of the polymer patterns, the nanoparticle array can direct visible light to any targeted focal points without needing to change its structure.
![Metalens for fully reconfigurable imaging, Northwestern University.](https://www.photonics.com/images/Web/Articles/2019/3/29/REAS_Northwestern_Tiny_optical_elements_could_one_day_replace_traditional_refractive_lenses.jpg)
This reconfigurable materials platform enables tunable focusing with diffraction-limited resolution and could offer prospects for highly adaptive, compact imaging. “In this study, we demonstrated a versatile imaging platform based on fully reconfigurable metalenses made from silver nanoparticles,” said professor Teri W. Odom. “During a single imaging session, our metalens device can evolve from a single-focus lens to a multifocal lens that can form more than one image at any programmable 3D position.”
For imaging operations such as zooming and focusing, most existing metalenses cannot adjust their focal spots without physical motion. One major reason, Odom said, is that the building blocks of these lenses are made of hard materials that cannot change shape once fabricated.
The Northwestern team’s reconfigurable metalens system could one day be used in portable imaging systems and optoelectronic devices. “This miniaturization and integration with detectors offers promise for high-resolution imaging in devices from small wide-angle cameras to miniature endoscopes,” Odom said.
The research was published in ACS Nano (https://pubs.acs.org/doi/10.1021/acsnano.9b00651).