Building an adjustable zoom lens in a millimeter-thick cell phone, a miniaturized microscope, or the distal end of a medical endoscope necessitates complex lenses that can handle the entire optical spectrum and be electrically reshaped within milliseconds. Researchers have demonstrated an adjustable technique for manipulating light without the use of mechanical movement, resulting in devices known as smart lenses.
When a current is passed through a well-optimized micrometer-scale resistor, the heating changes the optical properties of a transparent polymer plate that holds the resistor, causing the refractive index of the plate to change. As a result, this microscale hot region can deviate from light. A polymer slab is transformed into a lens and back in milliseconds: small, micrometer-scale smart lenses heat up and cool down quickly and with minimal power consumption.
They can even be made in arrays. The authors demonstrate how several objects at different distances can be brought into focus within the same image by activating the smart lenses in front of each of them, even if the image is in color.
The authors demonstrate that complex optical devices can be optimized using algorithms inspired by natural selection laws to go far beyond simple lenses: a properly engineered resistor can deviate light in a specific direction. At the same time, another will refract it into a ring or other specific shapes.