Design And Application Of Large-aperture Fresnel Liquid Crystal Lens

Liquid crystal lens has the characteristics of electronically controllable focusing,small size and low power consumption.It can be used in various optical systems to replace the traditional mechanical moving zoom and realize functions such as automatic zoom,intelligent imaging.However,the traditional liquid crystal lens has a small aperture and cannot be used in large-aperture near-eye devices,which limits its application range.In this thesis,the liquid crystal lens is divided into several Fresnel zones by using Fresnel lens principle,which can greatly improve the aperture of the liquid crystal lens,and at the same time maintain a fast response time and a large adjustable range of light focus,so as to broaden the application of liquid crystal lens.This thesis focuses on the structural design,internal electric field simulation,and high impedance film resistance of Fresnel liquid crystal lenses.The liquid crystal lens with a diameter of 1 cm is successfully prepared.Its parameters are tested and the lens is applied to various optical systems to check its electronically controlled focusing function.The main contents and achievements of this thesis are summarized as follows.First,this thesis designs and simulates the Fresnel liquid crystal lens.The Fresnel structure is applied to the liquid crystal lens,and the ring annular auxiliary electrode and the disk electrode are added to the central area of lens to improve the phase adjustment capability of the central lens,realize the adjustment effect of positive and negative power,and enlarge the focusing range;Since the electrode line of the pattern electrode layer of this structure is only 5μm width,the resistance of the traditional ITO electrode is large,which will affect the driving of the lens,so the gold electrode is used instead.The finite difference method is used to simulate the electric field inside the lens.According to the electric potential distribution,the refractive index distribution of the lens and the phase distribution of the central lens are calculated,which are compared with Fresnel lens to verify the rationality of the structure in this thesis.Then,this thesis solves the biggest problem of the structure,the high impedance film.Liquid crystal molecules can be equated to a resistance and a capacitance in parallel,and the square resistance of the high impedance film required for the structure of this thesis is calculated to be about 10~5Ω/.By comparing the results of spinning PEDOT:PSS solution and magnetron sputtering,magnetron sputtering is finally used to prepare high impedance film with stable resistance,which solves the problem of high impedance film and reduces the driving voltage of lens.Finally,the lens parameters are tested and the lens is applied to each imaging system.The prepared lens is placed in the interference optical path,and the interference fringe map is collected to observe the optical performance of the lens.The driving voltage is traversed to obtain the optical focal length and aberration at each voltage.The lens is applied to the zoom imaging,corrective human eye,and AR imaging systems,and the system performance can be improved by using the electronically controlled focusing function.The Fresnel liquid crystal lens designed in this thesis has a large aperture,electronically controlled focusing,low driving voltage,and large zoom range,and can be applied to various zoom imaging and near-human eye imaging systems with promising applications.