Characteristics And Applications Of Large-aperture Liquid Crystal Lenses

Liquid crystal lens is a kind of optical lens,which has the functions of electronically controlled focusing and optical axis movement.Liquid crystal lens have been used in various optical systems such as automatic focusing,intelligent imaging,and depth acqui-sition.The liquid crystal lens with a circular hole electrode is the most common type,but due to the edge effect of the electric field,it is difficult for the liquid crystal lens to achieve a parabolic wavefront distribution close to an ideal lens under a large aperture and low voltage driving.At present,researchers have proposed many structures and methods to realize large aperture.Among them,a more widely used way is the lens based on modal control,which can solve the problem caused by the edge effect of electric field.This pa-per studies a new type of liquid crystal lens with large aperture based on modal control.The lens has low driving voltage,and can realize any rectangular aperture.This paper focuses on the driving method of the liquid crystal lens,and realizes the adjustment of the lens power.The moving method of the electric field distribution in the lens is proposed to realize the optical axis moving at any position in the effective area.The main contents and achievements are summarized as follows.Firstly,in order to meet the needs of portable imaging equipment and realize large aperture and low-voltage liquid crystal lens,a lens structure with strip electrodes on the upper and lower substrates based on the modal control principle is adopted in this paper.The electric field distribution inside the liquid crystal lens is calculated by circuit simu-lation,and the effective voltage calculation formula at any position in the effective area is derived.In addition,through the analysis of the electric field distribution,the voltage driving method of the circular central symmetry state is obtained,and the electric field movement formula in the effective region is derived.The electric field can move without changing the gradient and absolute value,and only change the position of the electric field symmetry center in the process.Then,three driving methods of the studied lens are proposed,including amplitude drive,phase drive and amplitude phase drive.Among them,the amplitude drive and phase drive are easy to implement.Amplitude phase driving is more complex,but it can achieve a larger focusing range and faster response speed with smaller aberration.The experi-ments verify the correctness of the proposed driving method and the electric field moving method.Finally,the zoom imaging experiment is completed by using the proposed driving method,and the electronic focusing of objects with different distances is realized.By us-ing the proposed electric field moving method,the spot moving experiment is carried out,and the quality of the spot is nearly the same during the moving process.The liquid crystal lens has the characteristics of low-voltage driving,electronic focusing,large aperture and movable optical axis,which has a good application prospect in new intelligent imaging,portable imaging equipment and other fields.