| Geometric phase(GP) liquid crystal elements have attracted a lot of research interest because of their advantages such as high diffraction efficiency,low power consumption,and compactness.We conduct research on GP elements,and propose a single-exposure fabricating method and a head-up display system based on GP lens.The research is summarized as follows:1.Single-exposure fabrication of GP optical elements with arbitrary wavefronts.GP elements have great potential in many applications,but there are many problems with the existing fabrication methods,such as sensitivity to environmental disturbance and high production costs.In this dissertation,we propose to use a spatial light modulator(SLM)to control the twodimensional linearly polarized light field on the pixel level,and make a single exposure on the sample,so as to achieve an arbitrary GP pattern.The non-interferometric approach is insensitive to environmental disturbance,and moreover,the dynamic phase mask on the SLM can be conveniently reconfigured by a computer,which greatly reduces costs.The fabricated GP devices include gratings,lenses,q-plates and holograms,and exhibit good optical properties.2.GP liquid crystal lens based head-up display(HUD)with electrically controlled contrast ratio.With the growing demand for driving safety and convenience,HUDs have gained more and more interest in recent years.In this dissertation,we propose a HUD system that can adjust the relative brightness of ambient light and virtual information light.The system consists of a cholesteric liquid crystal(CLC)film,a GP liquid crystal lens,and a circular polarizer.By controlling the voltage applied to the GP lens,the brightness of the virtual image and the external environment can be continuously adjusted to ensure good visual performance under different driving conditions. |
