UV Fluorescent Hi-lites
Small colored or colorless particles of different sizes randomly embedded in the paper pulp during paper sheet formation. The particles glow when exposed to UV light.
a
b
c
Fig. 1. Greece. Passport issued in 2014:
a — page 17. Paper substrate. UV light (365 nm); b — the same. UV fluorescent hi-lites of different colors are randomly distributed on the surface of the page; c — the same. Zoomed fragment. UV fluorescent hi-lites of different sizes and forms