Explicit computational model of dielectric elastomeric lenses

Significance 

Deformable lenses have the ability to improve the performance of optical systems by reducing the effect of incoming wave front distortions. Due to such admirable characteristics, they have numerous applications in various fields and numerous equipment such as medical endoscope, cell phone cameras and machine vision apparatus. Their ability to alter the reflective index of the optical medium/lens curvature has put them a step ahead as the most promising candidates for replacing traditional assemblies in old focus tunable lenses. Furthermore, they have the upper edge in terms of compactness, efficiency, cost benefit and flexibility when compared with traditional lens assemblies. Recent advances in this field have unveiled alternative ways of assembling adaptive lenses. To be more specific, tunable lens mimicking the human eye where a dielectric elastomer actuated by voltage functions as the ciliary muscle and the fluid enclosed by membranes works together as the crystalline lens have been proposed. Unfortunately, the relationship between the focal length and applied voltage for such a system has not been fully established.

A team of researchers led by professor Yu-Xin Xie from Tianjin University in China developed a computational model based on the nonlinear elasticity to characterize the performance of dielectric elastomeric lenses in terms of the focal length variation with respect to the actuation voltage. They hoped to investigate the mechanical deformation of a lens induced by voltage with an integrated actuator in the optical path, and then determine the focal length change. Their work is now published in the research journal, Optics Express.

The researchers initially developed a lens composed of a stiff frame, a transparent liquid of fixed volume and two elastomeric membranes. They then proceeded to determine the initial focal length of the tunable lens by using the diffractive index of the liquid and curvature radii of the membranes. Eventually, they applied a voltage to the second membrane, plotted the variation of the focal length with respect to the voltage and assessed the effects of liquid volume and geometry of the device.

The explicit computational model presented in the study for optimal design of an adaptive focus lens can be electrically controlled by tuning the voltage applied to an electroactive membrane. It has been seen that the developed model has the ability to describe the focal length of the lens as a function of the actuation voltage, the lens geometry as well as the liquid volume contained between two membranes. Moreover, the computational results predicted by the model agree well with the reported experimental data. In totality, it is hoped that their work will influence design of better tunable lenses, thereby translating into better products hence market growth.

Reference

Yanjie Cao, Yanan Wang, Yang Liu, Yu-Xin Xie. Explicit computational model of dielectric elastomeric lenses. Vol. 25, No. 23 | 13 Nov 2017 | Optics Express 28710.

Go To Optics Express

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