| 摘要 |
Methods and systems for creating optical effects in pigments, inks, and on media are described. There is in particular described a system or indicia for use as a security or identification feature comprising a combination of material that is capable of inducing a change of optical appearance of the system or indicia in response to exposure to ultraviolet (UV) light. The combination of materials includes at least a first material that changes its optical appearance under exposure to UV light and a second material that provides a color under ambient visible light or under exposure to UV light. The first and second materials are selected in such a way that exposure to UV light causes a visible spectrum of the system or indicia to dynamically shift over time from a first spectrum to a second spectrum distinct from the first spectrum |
