Simulation and experimental analysis of aspherical double-liquid lens based on parallel plate electrode

Based on the principle of dielectrophoresis, an aspherical double-liquid lens based on parallel plate electrode is designed. In comparison with the liquid lenses based on patterned-electrode, the aspherical double-liquid lens structure uses continuous electrode, which has the advantages of simpler processing, lower cost, easier realization and more practicability. The droplet in the dielectric electrophoretic liquid lens is polarized in the electric field and move towards the direction of higher electric field intensity under the action of the dielectrophoretic forces. With the change of applied voltage, the dielectrophoretic forces are also changed, thus the contact angle of the droplet at the liquid-liquid interface is changed. Firstly, the models of aspherical double-liquid lenses under different voltages are established with Comsol software, and the data of interfacial profile are derived. Then using Matlab software, the derived interface surface data are fitted by polynomial, and the aspherical coefficients are obtained. Finally, the optical models are built with Zemax software, the variation range of focal length and RMS radius of aspherical double-liquid lens under different voltages are analyzed. In order to further research the characteristics of aspherical double-liquid lens, it is compared with spherical double-liquid lens model. The liquid material, cavity structure and droplet volume of spherical double-liquid lens are consistent with those of aspherical double-liquid lens. The corresponding spherical double-liquid lens model is established by Zemax software, the range of focal length and RMS radius of spherical double-liquid lens under different voltages are obtained. The results show that the focal length variation range of aspherical double-liquid lens is larger than that of spherical double-liquid lens, and the imaging quality of the former is better than that of the latter. The experimental preparation of the designed aspherical double-liquid lens device is carried out, and its focal length and imaging resolution are measured. When the operating voltage is 0V-280V, the focal length varies from 54.2391mm to 34.5855mm, which is basically consistent with the result of simulation. The feasibility of the liquid lens structure is verified by experiments. The imaging resolution can reach 45.255lp/mm. The designed aspherical double-liquid lens based on parallel plate electrode can provide a new scheme for the high-quality imaging of liquid lens and its application, and can expand the application of liquid lens.