Polarization‐Selective Ultra‐Broadband Reflective Diffuser as a Smart Projection Screen

Abstract

Herein, active smart screens are increasingly investigated to enhance projection‐type transparent displays owing to the high contrast ratio generated by their switchability between projection and transparent states. Despite the development of various active smart screens, most screens employ the scattering state as the projection state, which suffers from low reflectance of the projection state and optical interference with background light. Herein, an active smart screen composed of a passive polymer‐stabilized cholesteric liquid crystal (PSCLC) diffuser and an active polarization modulator (PM) is proposed. The PSCLCs enabled by the chiral monomer have a pitch‐gradient helical structure, wherein liquid crystal molecules form a multi‐domain planar texture and exhibit a broadband reflection band over the entire visible spectrum; their natural circular polarization selectivity facilitates the operation between projection and transparent states when the PSCLC is observed using opposite‐handed circular polarized light. Unlike traditional active smart screens, both transparent and projection states of the PSCLC diffuser can be switched by driving the PM, thereby eliminating the issue of background interference. The proposed active projection screen based on the polarization‐selective PSCLC can potentially improve the display quality of existing projection‐type transparent displays and form the basis for see‐through windows and near‐eye display applications.