OPTICAL DIFFUSION ELEMENT, PROJECTION SCREEN, DESIGN MEMBER AND SECURITY MEDIUM

摘要

An optical diffusion element in which only a desired portion can have discontinuously different optical characteristics without forming a step or a cut, diffusion properties can be controlled easily, and stray light is not generated. A projection screen employing the optical diffusion element, and a design member are also provided. An optical diffusion element (50) comprises a substrate (2), and a cholesteric liquid crystal polymer layer (10) provided on the substrate (2) and consisting of a plurality of regions on a plane. The diffusion angle of one diffusion region (e.g. a first diffusion region (1a)) of the cholesteric liquid crystal polymer layer (10) is different from that of another diffusion region (a second diffusion region (1b)).