The Property Of The Liquid Crystal Lens System’s Field Of View

A traditional optical system requires the mechanical movement of lens groups to achieve changing focal length,which restricts its application.The appearance of liquid crystal lens has broken through the limitation.Variable focal length is realized by the applied voltages in a liquid crystal lens system,and not by the mechanical movements of lenses in traditional imaging systems,this feature of the liquid crystal lens allows it to be employed in many fields.For any optical system,quality evaluation of imaging is essential.The evaluation includes evaluations before and after the real manufacture of an optical system.However,the image evaluation for the optical system of liquid crystal lens is not very thorough.In particular,the research on the field of view of the liquid crystal lens still has room for exploration.Therefore,this paper mainly accomplished three tasks,including theoretical investigation,simulation analysis and experimental research.Firstly,an optical simulation method preserving the birefringence characteristic of the liquid crystal lens is proposed.Through investigation,it is found that the optical simulation method of the liquid crystal lens can be improved.This paper rebuilds the wavefront by Zernike polynomial from the actual wavefront data of a liquid crystal lens and further obtains the mean distribution of liquid crystal directors in the cell.Also,by importing the distribution data into ZEMAX,this paper builds a modal of the liquid crystal lens with birefringence characteristic.Secondly,imaging experiments based on a liquid crystal lens are carried out to analyze the variation of the imaging quality during the process of focus changing.Contrast analysis and SFR analysis show that the light from different fields of view achieve imaging clearly in succession when the focal length of the liquid crystal lens is changing,this phenomenon is consistent with the result of optical simulation.This indicates that the difference in the imaging quality along the rubbing direction of the lens is caused by the different angle of field.Finally,image fusion and a lens structure of two liquid crystal layers are proposed to improve the imaging quality of the liquid crystal lens optical system.Two methods are used in this paper to collect images,one is taking a picture for each different voltage condition,the other is recording a video during the focus changing process.The result indicates that image fusion can make full use of the distinct regions of different images collected under the circumstances of different voltages,and show a rather clear image in the whole field.The structure of a lens with two liquid crystal layers is simulated in ZEMAX,analysis results show that this structure can improve the imaging quality of the liquid crystal lens.