From Spheric to Aspheric Solid Polymer Lenses: A Review

Figure 4

The gradient electrostatic field modulation system 1 developed in this paper. This paper consequently modifies the electrode structure to design electrodes structurally similar to Fresnel zone plate, which can be used to modify the shape of the lens margin. The upper and lower electrodes both consisted of transparent ITO electrodes in this paper's initial design. Nevertheless, due to the approximately 2 mm distance between the upper and lower electrodes, the excessively large depth of field caused difficulty in aligning the upper and lower electrodes. Because of this, the upper electrodes were modified to include an SU-8 3010 insulating layer (SU-8 has a dielectric coefficient of approximately 3.28), and Teflon was used on the aluminum lower electrodes to define the hydrophilic/hydrophobic interface, inducing liquid droplets to perform self-assembly; the Teflon also served as an insulating layer (Teflon has a dielectric coefficient of approximately 2.1–2.5). In addition, the SU-8 3010 design formed hollow round concavities with different radii and width, which caused different electric field effects and gave the edge of the lens an aspherical profile.