Study On Liquid Crystal Lens With Low Aberration,Multi-Transparent Ring Electrode

Liquid crystal lens can exert the control voltage to change focal length,its essence is mainly making the polar group of the liquid crystal molecules rotate under the effect of electric field.The liquid crystal molecules after rotation can change the direction of the incident light in liquid crystal materials,so as to realize the divergence or convergence of light and have the effect of lens.Because of its simple structure,ease of integration,liquid crystal lens is an optical element with a broad application prospect.With the further study of liquid crystal lens,optical aberration has become one of the key factors in restricting its application.In order to improve the refractive index distribution of liquid crystal lens and improve the imaging quality,the predecessors put forward a mode controlled liquid crystal lens.It smoothed the distribution of electric field in the smooth lens and reduced the lens aberration in a way of coating a high resistance layer above the round hole electrode of the liquid crystal lens.Based on the mode controlled liquid crystal lens,a new type of multi-transparent circular electrode liquid crystal lens is proposed in this thesis to further improve the aberration of liquid crystal lens.The voltage and refractive index distribution of liquid crystal lens were studied by MATLAB simulation.A transparent multi-ring electrode pattern was designed and fabricated.The combination between this pattern electrode and high resistance layer achieved further balance of the electric field distribution in the lens and improvement of the imaging quality.This thesis proposed the preparation method of AZO high-resistance thin film through sol-gel method.The high-resistance film whose square resistance can vary gradually with the concentration of Al was made,and the repeatability of the high-resistance film was improved.A multi-transparent ring electrode liquid crystal lens was prepared and its refractive index distribution was measured.Specific research contents are as follows:1.Combined with the elastic theory of liquid crystal continuum and the equivalent circuit model of multi-transparent ring electrode of the liquid crystal lens,liquid crystal lens with the multi-transparent ring electrode was simulated and analyzed.And the thesis analyzed the film square resistance’s influence on refractive index and the driven frequency of liquid crystal lens under the fixed focal length.The results show that the film square resistance under 200 MΩ/sq has less impact on the distribution of refractive index of liquid crystal lens which has smaller deviation compared with the ideal rotating parabolic distribution.Square resistance in the range of 10 MΩ/sq-4.3×105 MΩ/sq by adjusting the driving frequency can satisfy refractive error Rayleigh criterion and achieve sound imaging.Fixed film square resistance of 100 MΩ/sq,under the condition of different focal length,this thesis analyzes the changing rule of deviation of the refractive index distribution according to the focal length.The results show that when the focal length is 17.03cm,20.43cm,25.54cm,34.05cm,51.08cm.,102.15cm,lens refractive index distribution deviation can be relatively small.2.In the process of preparing liquid crystal lens,AZO films with different of concentrations A1(5%,7.5%,10%,12.5%,15%,17.5%and 20%,all of which are atomic fractions)were prepared on the glass substrate by sol-gel method,and the influences of doping concentration and coating number on the photoelectric performance of the films were analyzed.The characterization and properties of AZO films were studied by square resistance method,scanning electron microscope,Nano Measurer 1.2 software and spectrophotometer.Research results show that:when the A1 doping concentration increases,square resistance in 2MΩ/sq-405MΩ/sq increases gradually,and the grain size decreases between 24.35 nm 17.53 nm.Doping concentration has less effect on the transmittivity and the transmittivity of different doping concentration of AZO thin films within the scope of the visible light is around 80%.The square resistance of AZO film decreases with the increase of th.e number of coating layers,and the transmittivity of AZO film in visible light range is the best when the number of coating layers is 4 layers.When the square resistance of 10%Al doped AZO thin films is near 100MΩZ/sq,repeatability is well.3.The crystal lens with multi-transparent ring electrode was prepared by the 10%A1 doped AZO film and its performance was analyzed by the interference experiment.The results show that the maximum deviation of the crystal lens with a focal length of 21.80cm from the ideal refractive index distribution is 1.81×10-2,and the deviation of the root-mean-square refractive index is 0.52×10-2.Compared with the traditional mode controlled liquid crystal lens,it has a rotation paraboloid distribution which is closer to the ideal refractive index.