高电阻浮置电极液晶透镜的仿真研究

Simulation of high resistance floating electrode liquid crystal lens

设计了采用薄膜介质层分隔浮置电极与模式控制电极的液晶透镜,浮置电极与模式控制电极处于基板的同一侧,避免了浮置电极与模式控制电极处于基板两侧而需要采用薄型基板的限制。采用Comsol Multiphysics仿真软件仿真研究了浮置电极方块电阻和薄膜介质层厚度对液晶透镜波前误差的影响规律。对于直径2 mm的液晶透镜,当浮置电极方块电阻在150Ω·□^(−1)~300 MΩ·□^(−1)间变化时,液晶透镜波前误差先减小后增大,在40 MΩ·□^(−1)时波前误差达到极小值。当介质层厚度在50~5000 nm间变化时,液晶透镜波前误差最小的浮置电极方块电阻由50 MΩ·□^(−1)减小到2 MΩ·□^(−1),最佳方块电阻参数呈现单调减小规律。取浮置电极方块电阻40 MΩ·□^(−1)和介质层厚度250 nm时,研究了液晶透镜的调焦特性和波前误差特性,当焦距在250 mm至无限远间变化时,589 nm光波长下的波前均方根误差最大值为0.0412μm,小于λ/14,满足Marechal判据的要求。

A thin film dielectric layer was used to separate the floating electrode and the mode control electrode.The floating electrode and the mode control electrode were on the same side of the substrate,which avoided the restriction of using a thin substrate.Comsol Multiphysics software was used to simulate the influence of the square resistance of floating electrode and the thickness of thin film on the wavefront error of liquid crystal lens.For the liquid crystal lens with a diameter of 2 mm,when the square resistance of floating electrode varies from 150Ω·□^(−1) to 300 MΩ·□^(−1),the wavefront error of liquid crystal lens decreases first and then increases,and reaches a minimum value at 40 MΩ·□^(−1).When the thickness of the dielectric layer varies from 50 nm to 5000 nm,the square resistance of the floating electrode with the smallest wavefront error decreases from 50 MΩ·□^(−1) to 2 MΩ·□^(−1),and the optimal square resistance parameters decrease monotonically.When the square resistance of floating electrode is 40 MΩ·□^(−1) and the thickness of dielectric layer is 250 nm,the focusing characteristics and wavefront error characteristics of liquid crystal lens are studied.When the focal length varies from 250 mm to infinity,the maximum root mean square error of wavefront at 589 nm is 0.0412μm,less thanλ/14,which satisfy the Marechal criterion.