The Fabrication Of Liquid Crystal Polarization Lens And Study Of Its Optical Characteristics

Liquid crystal polarization lens(LCPL)is a new type of liquid crystal lens with diffraction efficiency up to 100%.Traditional optical devices use optical path differences to perform wavefront modulation..In contrast,LCPL modulates the wavefront by geometric phase difference.The principle is that LCPL has a special spatial arrangement of anisotropic axes(liquid crystal molecules).When the light passes through,the polarization state changes,resulting in the geometric phase difference.LCPL has the advantages of small size,light weight,adjustable beam polarization and low production cost.In addition,the diameter of LCPL can be from micron to meter,which has high applicability,is conducive to integration and industrialization,and its development prospect is very optimistic.Including the United States,South Korea and other countries,research institutions have carried out research on the liquid crystal polarizing lens and explored its application..In order to make up for the technical blanks on LCPL,this article focuses on the preparation of LCPL and the design of LCPL zoom system.First,the Mach Zehnder holographic interference optical setup was designed and constructed.Then Using this optical setup,active and passive LCPL were prepared,and the following innovative work was completed:(1)In the aspect of device design: The influence of the linear polarization error of the interference field between the spherical wave and the plane wave with orthogonal circular polarization on the lens preparation was analyzed.The number of F of the liquid crystal polarizing lens that can be prepared should not be less than(1.51 ?/?0),where ? is the use wavelength and ?0 is the exposure wavelength.The influence of liquid crystal layer thickness on the performance of active LCPL was analyzed.The limit range of liquid crystal layer thickness was determined.It is concluded that the F number of active LCPL should not be less than(0.35/?n).(2)In the aspect of device preparation: Based on the relationship between the diffraction efficiency and the film thickness of the liquid crystal polarizing lens,a novel method for measuring the film thickness of liquid crystal based on the Level-0light leakage spectrum of the LCPL was proposed,and the measurement requirement was given: Zd > 2dl F,where Zd is the measurement distance,Dl is the measurement beam aperture,F is the number of liquid crystal polarizing lens F.The fabrication process of the active / passive LCPL is summarized.Finally,the active and passive LCPL with diffraction efficiency better than 96% and 95% were developed.(3)The design method of the electrically tunable zoom optical system based on the multi-stage liquid crystal polarizing lens was established,and the relationship between the focus distribution and the lens parameters was obtained.By optimizing parameters such as the lens pitch and focal length,the first 6 zoom alignments were achieved in a quasi-linear distribution.Finally,the design experiment verified the scheme and proved the feasibility of the scheme.Through the research in this thesis,we hope to promote the practical application of the LCPL in the fields of portable device projection,virtual reality and augmented reality.