Page 246 - Optofluidics Fundamentals, Devices, and Applications

Bio-Inspir ed Fluidic Lenses for Imaging and Integrated Optics 221

Humor
Nasal

Pupil
Retina
IOL in
capsular bag
Visual axis

Optical axis 5°

Fovea

Cornea
Temporal

FIGURE 9-15 Schematic of a pseudoaphakic eye based on Liou and
Brennan’s model eye (top view). (W. Qiao, F. Tsai, S. H. Cho, and Y.-H. Lo,
“Fluidic intraocular lens with a large accommodation range,” IEEE Photonic
Technology Letters, copyright (year) IEEE.)

IOL, the lens in Liou and Brennan’s eye model is replaced by the fluidic
lens (Fig. 9-15). A ray-tracing program (Code V) is used to calculate the
resolution, distortion, and other relevant properties. The fluidic IOL is
optimized to achieve best optical performance on the fovea, which is
located 5 temporally.
One of the most effective approaches to evaluate the performance of
an optical system is to calculate its modulation-transfer-function (MTF)
curves. The averages of sagittal and tangential MTF curves for the
model eye with fluidic accommodative IOL are shown in Figs. 9-16 and
9-17. The on-axis (i.e., at fovea) (MTF) curves, which are focused at
infinity and 25 cm respectively, are compared with Liou and Brennan’s
eye model (Fig. 9-16). The off-axis MTFs (5 object angle from the fovea)
in both horizontal and vertical planes are presented as well (Fig. 9-17).
All the MTF curves are simulated at wavelengths of 475, 555, and
625 nm with a weighting factor ratio of 1:2:1 and with an object distance
of infinity. The results show that fluidic IOL in pseudoaphakic eye can
produce optical performance comparable to human eye.

9-3-2 Experimental Results
The fluidic IOL consists of a polydimethylsiloxane (PDMS) elastomer
membrane, a fluid-containing lens chamber, and a flat supporting sub-
strate. The lens chamber is filled with silicone oil. To experimentally
evaluate the optical performance and to record images, a scaled-up eye
model is constructed (Fig. 9-18) to simulate the eye optics and a 2 mil-
lion pixel CMOS sensor is used to simulate the retina. The output of the