Page 251 - Optofluidics Fundamentals, Devices, and Applications

226 Cha pte r Ni ne

(Gelest 1.41), the force needed for driving the fluidic IOL to achieve an
accommodation range of 7 D is approximately 0.085 N. Given that cili-
ary muscles in human eyes generally produce approximately 0.08 N of
net force during accommodation [72–74], the elastic properties of the
fluidic IOL match well with the muscular force. If desired, the required
driving force can be further reduced via engineering of the mechanical
properties of PDMS membrane.

9-3-4 Summary
Unlike optic-shift IOL having very low accommodation range, the
fluidic IOL demonstrated in this section possesses an accommoda-
tion range comparable to or even wider than a young human eye
and can produce good image quality. The result also indicates that
the required force to achieve the desired accommodation range is
comparable to the force generated from ciliary muscles of human
eyes. We hereby conclude that fluidic IOLs hold promise to fully
restore the acuity and accommodation range of vision and could
potentially produce superhuman vision.

9-4 Liquid Molding Technique—Prototyping
of Aspherical Lenses
Most optical systems are designed using a ray-tracing software
equipped with efficient routines that optimize the profile of each
lens surface according to user-defined merit functions. Before vol-
ume production, prototypes are produced first to verify the design.
These prototypes often reveal design faults and potential issues not
conceived in the original design. The use of aspherical lenses has
become increasingly popular because, compared with systems
solely made of spherical lenses, systems containing aspherical
lenses produce superior performance and are more compact.
Although plastic aspherical lenses can be made cost-effectively in
very high-volume production, small-volume fabrication of aspheri-
cal lenses for prototypes is time consuming and costly [75–77]. In
this section, we will show that when a fluidic lens is used as a tun-
able mold, we can form aspherical lenses of designed shape and
property promptly and cost-effectively, and thus greatly shorten the
design cycle for optical systems.

9-4-1 Tunable Liquid-Filled Molding Technology
A simple yet accurate process to fabricate aspherical polymer lenses
using a tunable liquid-filled molding technology has been reported
[78]. The authors modified a fluidic lens [35–39] into a tunable liquid-
filled mold and used it to fabricate a variety of focus-fixed polymer
lenses of designed aspherical profiles. A layer of 100- to 300-μm-thick
optically transparent elastomer membrane is formed in the same way