UV Fluorescent Ink
An ink containing luminophores. When exposed to UV light (250–380 nm), the luminophores transform UV light into fluorescent light of different colors visible to the naked eye.
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Fig. 1. Kosovo. Passport issued in 2013:
a — data page. Paper substrate; b — the same. UV light (365 nm); c — the same. UV light (254 nm)
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Fig. 2. Hungary. Service passport issued in 2012:
a — data page. Hybrid substrate; b — the same. Fluorescent ink: smooth transition of color in vertical direction. Rainbow printing. UV light (365 nm); c — the same. UV light (254 nm)