A bio-inspired polymeric gradient refractive index (GRIN) human eye lens

Abstract

A synthetic polymeric lens was designed and fabricated based on a bio-inspired, "Age=5" human eye lens design by utilizing a nanolayered polymer film-based technique. The internal refractive index distribution of an anterior and posterior GRIN lens were characterized and confirmed against design by µATR-FTIR. 3D surface topography of the fabricated aspheric anterior and posterior lenses was measured by placido-cone topography and exhibited confirmation of the desired aspheric surface shape. Furthermore, the wavefronts of aspheric posterior 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 as compared a homogenous PMMA lens of an identical geometry. Finally, the anterior and posterior GRIN lenses were assembled into a bio-inspired GRIN human eye lens through which a clear imaging was possible.

Polymeric nanolayered gradient refractive index lenses: technology review and introduction of spherical gradient refractive index ball lenses

“…Wavefront measurements of the posterior GRIN and PMMA control lenses were tested with light incident on the planar lens surfaces, i.e., from the same direction as their design. 25 In the lens design, there was no tilt contribution to the wavefront measurement; however, the finished lens possessed a tilt contribution that indicated a level of parallelism achieved in the diamond turning process. The tilt contribution of the wavefront for the posterior GRIN and PMMA control lenses was determined to be 7.6 and 18.8 waves (peak-to-valley), respectively, across the measured aperture [ Fig.…”

“…A summary of the recently published bio-inspired human GRIN eye lens is included to demonstrate that the nanolayered film GRIN optic fabrication technique has the ability to build a lens with any arbitrary refractive index distribution and lens shape. 25 An optical design based on the geometry and internal refractive index distribution of the human eye lens was selected based on previously published works. One caveat to design a synthetic version of the human eye lens is an agedependent GRIN distribution and lens geometry.…”

“…One caveat to design a synthetic version of the human eye lens is an agedependent GRIN distribution and lens geometry. 12,32,33 Based on one such age-dependent human lens model for the refractive index distribution and geometry developed by Diaz et al, 25 an "Age ¼ 5" human eye lens was selected as a design case. The "Age ¼ 5" model eye possesses a maximum GRIN magnitude in the lens, estimated at Δn ¼ 0.05, which illustrates the maximum corrective contribution of the GRIN to the lens performance.…”

“…Nanolayered anterior and posterior refractive index distributions were confirmed through attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). 25 Diamond turned aspheric anterior and posterior lens surface curvatures were mapped and compared to the prescribed surface profiles by noncontact profilometry with a placido-cone topographer (Fig. 6).…”

“…20 This unique materials approach has enabled the fabrication of GRIN lenses with an unprecedented variety of GRIN profiles, index distribution magnitudes, geometries, and lens apertures. [21][22][23][24][25][26] This paper reviews the enabling technology and describes unique nanolayered polymeric GRIN lenses, including original research demonstrating the fabrication of a polymericlayered GRIN ball lens. These GRIN lenses demonstrate the technology's potential to utilize unrestricted lens geometries and refractive index profiles to improve lens performance, realize optical element savings, and reduce optical system size and weight.…”