A research team has developed tiny optical elements from metal nanoparticles and a polymer that one day could replace traditional refractive lenses to realize portable imaging systems and optoelectronic devices.

During a single imaging session, the device can evolve from a single-focus lens to a multi-focal lens that can produce more than one image at any programmable 3D position. (Credit: Northwestern University)

The flat and versatile lens, a type of metalens, has a thickness 100 times smaller than the width of a human hair. The team built their lenses out of an array of cylindrical silver nanoparticles and a layer of polymer patterned into blocks on top of the metal array. By simply controlling the arrangement of the polymer patterns, the nanoparticle array could direct visible light to any targeted focal points without needing to change the nanoparticle structures.

This scalable method enables different lens structures to be made in one step of erasing and writing, with no noticeable degradation in nanoscale features after multiple erase-and-write cycles. The technique that can reshape any preformed polymer pattern into any desirable pattern using soft masks made from elastomers.

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