Researchers at Harvard School of Engineering and Applied Science -SEAS- have developed a meta-lens (to be layered on a lens) that it is similar in its characteristics to our eye’s lens but goes beyond it in terms of performances.
Our eye’s lens changes its shape through compression and extension induced by muscles. This, in turns, changes its optical characteristics and let us focus on objects at different distances.
The meta lens created at Harvard uses adaptive silicon nano-structures that can control in real time focus, astigmatism and image shift (this latter is something that our eye lens cannot do, offloading the stabilisation task to the brain which is pretty good at it but with some limitation).
Image shift control is performed in modern digital cameras and in modern lenses (usually known as Vibration Reduction) but it requires dedicated electronic and mechanics to affect the optics. This meta lens could be layered on the frontal glass (it is just 30µm thick) of a lens to achieve the same shift control.
The optical characteristics of the meta lens are controlled applying different voltages resulting in focus, astigmatism changes and in image shift control. The voltages affect elastomers embedded in the lens stretching and compressing it, a bit like what muscles do in our eye lens. Voltage is delivered through a single layer of carbon nanotubes (that are transparent to light in the visual spectrum).
A first application is foreseen in the manufacturing of glass for digital camera and in the area of augmented reality devices. Further down the lane is the possibility to apply these lenses directly on our eye lens to augment its capability. The problem in this case, as in most application to the human body, is to manage the power aspects: powering the device and dissipating the heat. The first issue has to have a solution that is not cumbersome (harvesting power through induction fields is somewhat cumbersome since it requires a transmitting device close to the receiving one), the second really requires devices to work with µW power to keep dissipation in limits that are acceptable to living cells, and this is so far a stumbling block. The use of dielectric elastomers, carbon nanotubes and nano structures significantly reduces the need for power but more reduction is needed for a prolonged use.