大变焦范围电调谐液晶变焦透镜的研究

Liquid crystal lens with large-range electrically controllable variable focal length

基于向列相液晶指向矢随施加电场作用发生变化的特性,结合几何光学和液晶理论提出了一种液晶透镜结构模型,研究了电极大小、隔垫物厚度等液晶透镜参数对液晶透镜焦距的影响.通过优化参数,得到结构简单、变焦范围较大的新型液晶透镜样品,在驱动电压0 V_(RMS)-250 V_(RMS)下可调的焦距范围为75-230 mm,达到155 mm.

A novel structure model with different disc-ring radii of liquid crystal lens is proposed,in which liquid crystal director could be controlled by changing the electric field intensity dependence.Then the theory of liquid crystal and the geometric optics are analyzed.By using the finite element method,under the same constant voltage,we obtain the distributions of the electric field intensity at different positions of the liquid crystal layer.Then,the simulation results provide a theoretical guideline for the experimental fabrication.Due to the fact that the electric field intensity at the electrode edges is stronger than that at the circular hole,a shorter focal convergence could be realized by controlling the voltage between the upper and the lower substrates.In this paper,the influences of the electrode size and spacer thickness on the focal length of liquid crystal lens are also discussed experimentally and theoretically.Through optimizing various parameters,a prototype liquid crystal lens with a large zoom range and simple structure is obtained.Its focal length can be controlled to be 75-230 mm in a range of 25 V（RMS）-250 V（RMS）.