IR Fluorescent Inks
Inks containing fluorescent pigments which glow when exposed to visible light of 400-530 nm. Fluorescence appears in IR light of 850-950 nm as bright light images on a dark background.
a
b
Fig. 1. Oman. Passport issued in 2014:
a — central page spread with a stitching thread. Paper substrate. White light; b — the same. IR fluorescent inks. A picture on the page spread, a stitching thread
a
b
Fig. 2. Slovenia. Diplomatic passport issued in 2009:
a — page 17. Paper substrate. White light; b — the same. IR fluorescent inks. Text, security fibers, a security thread