Artificial lenses designed to reproduce the optical qualities of natural lenses (VIDEO)

These polymeric light-collecting lenses are 3.5 times more powerful than glass and are the first commercial nanolayer product resulting from many years of R&D at Case Western Reserve University. To create the lenses, a 4,000 layer film is coextruded, then 200 layers of film are stacked to create a sheet of 800,000 nanolayers. Photo courtesy of Michael Ponting.

Artificial eye lenses are regularly used by ophthalmologists to correct various vision problems. Patients are generally delighted after surgery as their vision improves dramatically, revealing the beauty of the world they only remembered before. Yet modern artificial lenses are imperfect and act more like conventional glasses than the eyes‘ own surprisingly complicated lenses.

Everyone has known since school about refraction and how lenses are used to focus light. Many teachers and textbooks use the lens of the eye as an example of a natural lens that looks like what is found in a camera. The point is, most lenses found in optical equipment are made of pieces of solid glass that only bend light on their surface. Once a beam enters the lens, it travels in a straight line.

The eye’s own crystalline lens makes light of it continuously as it passes through it, called “GRIN”, or refractive index gradient optics. To make more perfect artificial replacement lenses, researchers at Case Western Reserve University, Rose-Hulman Institute of Technology, US Naval Research Laboratory and PolymerMore (Valley View, Ohio) have created technology that stack tens of thousands of ultrafine layers of polymer to produce a continuous refractive gradient.

From the study summary in Optical Express:

A synthetic polymer lens was designed and manufactured based on an “Age = 5” bio-inspired human ocular lens design using a nanolayer polymer film technique. The distribution of the internal refractive index of an anterior and posterior GRIN lens has been characterized and confirmed relative to design by µATR-FTIR. The 3D surface topography of the fabricated anterior and posterior aspheric lenses was measured by placid-cone topography and confirmed the desired aspherical surface shape. In addition, the wavefronts of the posterior aspherical GRIN and PMMA lenses were measured and simulated by interferometry and Zemax software, respectively. Their results show that the gradient index distribution reduces the overall wavefront error compared to a homogeneous PMMA lens of identical geometry. Finally, the anterior and posterior GRIN lenses were assembled into a bio-inspired human GRIN ocular lens through which clear imaging was possible.

Here is an animation describing the M-GRIN manufacturing process used to craft the new lenses:

Press Release: Human Eye Offers Researchers Visionary Design for New, More Natural Lens Technology

Study in Optical Express: A polymeric refractive index gradient (GRIN) bio-inspired lens for the human eye

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