In recent years, significant efforts have increasingly been focused on the development of optical lenses with electrically tuneable focal length. They are intended to replace conventional glass-made lenses moved by motors for focussing, in systems that are limited by the complexity, size, weight and response time of this typical approach. Examples include video cameras in a broad diversity of products, including cell phones, medical diagnostic devices and flying drones, just to name a few.
“Various strategies are being studied to address that need, using a diversity of physical principles and materials”, says Federico Carpi, Associate Professor in Biomedical Engineering at the University of Florence and corresponding author of the paper. “In 2011 we described the first tuneable lens made of electrically responsive elastomers, mimicking the function of the ciliary muscles that control the curvature of the crystalline lens in our eyes. However, so far, these and other important studies from other groups have only considered the problem of controlling the focal length, but not the need of electrically tuning also the other optical aberrations that can affect any lens in the visible range”.
Now, Carpi and colleagues have addressed this challenge, taking a step forward. They have presented the first electrically tuneable lens, entirely made of silicone, whose shape can be modified by suitable voltages, to vary not only the focal length but also the astigmatism. “We have obtained a fully elastomeric lens that can be deformed with two degrees of freedom, controlling astigmatism in the visible range with a smart lens for the first time”, says Carpi. The work was published in November 2019 in Scientific Reports.
According to the authors, the work opens up the possibility to electrically control even other optical aberrations, so as to implement versatile components for adaptive optics. “We have just proved one new function and there’s still a lot to be done. However, we are confident that this new technology is promising, with a significant potential to obtain also additional functions that at present are precluded to state-of-the-art approaches”, concludes Carpi.