Study On Photo-aligned Liquid Crystal Lens Based On Geometric Phase

Geometric phase(GP),known as the Pancharatnam Phase(PP),refers to the phase in which the light undergoes a continuous polarization transition in a closed path.Liquid Crystal Geometric Phase Lens(LCGPL),a special phase device,shapes and modulates the light beam that uses the liquid crystal molecules to continuously change the orientation in the plane.Compared with the traditional liquid crystal lens,in addition to the theoretical difference between the two in the realization of the focus function,the liquid crystal geometric phase lens can achieve the "positive and negative" transition of the lens under the condition of only changing the polarization state of the incident light.This article firstly reviews the development history of liquid crystal lenses and the important applications of liquid crystal lenses in modern hot industries.Compared with the single-orientation rubbing alignment technology,the liquid crystal photo-alignment technology has advantages of non-contact and area-controllable orientation,and has become the most popular orientation research direction at the moment.Because of the particularity of the liquid crystal arrangement of the geometric phase lens,it also makes the light control orientation technology the most convenient solution.In this paper,the liquid crystal geometric phase lens is prepared by the left and right circular polarized light interference.By adding a lens in a certain optical path,the two light beams interfere at the orientation surface to obtain the desired polarization distribution.The traditional lenses are all transmissive.The reflective geometry lens prepared in this paper achieves the convergence of reflected light and completes the reflected light imaging.The photo-alignment agent uses SD1 material with a wider photosensitivity range and can be oriented multiple times to replace the traditional photo-alignment agent,thereby improving the experimental error tolerance rate.In the process,the method of adding a spacer in the sealant is used to further improve the uniformity of the cell thickness of the cell.Polarization interferometry has a simple optical path and a high resolution.It has natural advantages for preparing alignment devices such as liquid crystal gratings and lenses,but it cannot achieve a specific pattern orientation.Although the mask method can achieve a specific pattern orientation,it also has a problem of the limitations of a one-by-one diagram.Therefore,the dynamic digital masking method not only solves the problem of orientation of a specific pattern,but also does not require re-preparation of a template when the new pattern is oriented.In this paper,LCoS phase devices are used to align the liquid crystal molecules.With only one exposure,the arbitrary orientation angle can be achieved in any pixel area.In addition,based on the characteristics of the LCoS device,the phase information can be converted into polarization information using only a single quarter wave plate device,further simplifying the alignment of the optical path.Compared to conventional lenses,LCGPL makes it easier to integrate in a variety of devices.Head-mounted displays devices require extremely high levels of integration and the development of LCGPL has great significance.In addition,theorientation optical path in the paper not only applies to the lens,but also be applied to the polarization orientation of any image,providing a solution for the device design of other special orientation requirements.