A new artificial lens based on nano-scale, micro-layered plastic film is described as being nearly identical to the natural lens of the human eye.
PolymerPlus, a spinoff from Case Western Reserve University, is launching a manufacturing program to increase the production of these lenses for high-performance applications, including potential replacements for human lenses.
The human eye, which is made up of only two lenses, the cornea and the lens, produces almost flawless (without "optical aberrations") images on the retina. This efficiency is not just due to the shape of the lenses, but also to the gradual changes in their refractive indices. Unlike an artificial lens made from glass or plastic, which is homogenous, the eye's lenses are made up of tens of thousands of layers of proteins with various indices. It is this structure which was reproduced by U.S. researchers.
To achieve this, they first manufactured very thin films with alternating polymer layers (PMMA and styrene acrylonitrile) through a process of co-extrusion. By varying their composition, they were able to obtain 51 layers with slight variations in their respective refractive indices. Each film is approximately 50 microns thick and is made up of layers each about a dozen nanometres thick …These films are then stacked and shaped by moulding to obtain lenses which have the required geometry and indices. By combining a "cornea" type lens with a "lens" type lens, the researchers were able to create an optical system inspired by the working of the human eye and which produces good quality images.