#Y2025 #光学材料 光学变色油墨（Optically variable ink，OVI），简称光变油墨，目前大多被应用于纸币上使假币容易被辨别出来。 从不同角度观察，油墨会显现出不同的两种颜色。例如，50美元纸币使用变色油墨印刷面值“50”,所以这一数字从一个角度上看是铜色，而从另一角度看则是亮绿色。光学变色油墨在防伪印刷领域有着极其重要的作用；其主要生产商是一家名为瑞士锡克拜控股公司的瑞士公司。 [regulaforensics](https://regulaforensics.com/glossary/documents/)提供了多种防伪技术的介绍，其中也包括多种光学防伪技术 An ink that changes its color depending on the angle of observation and illumination. The ink contains a nontransparent scaly pigment with a layered structure that includes a reflective metallic layer, a transparent dielectric layer, and a translucent metallic layer. White light is partially reflected from the translucent metallic layer (surface layer) and partially from the reflective metallic layer (bottom layer). Interference and multiple reflections of light beams by the two reflective layers result in selective absorption of the waves that make up the white light spectrum. The reflected light waves cause the ink color we observe. The ink does not contain coloring pigments. It has metallic sheen. The ink color depends on the thickness of the dielectric layer (MgF2), the angle of illumination and the angle of observation.