Diffractive Identification Feature DID
DID – Diffractive Identification Device
An optically variable feature formed by a coating with the effect of polarization. A colour shift is observed, while rotating the image in its own plane by 90° (fig. 1).
a
b
Fig. 1. DID Patch. 500 Philippine Pesos (2010):
a – without rotation; b – rotated by 90°