METHOD FOR OPTICAL CHARACTERIZATION AND EVALUATION OF OPTICALLY VARIABLE DEVICES AND MEDIA

摘要

Methods for evaluating an optically variable device ("OVD") or optically variable media ("OVM") are disclosed. The methods include the steps of applying light of a single wavelength from a calibrated light source to the OVD or OVM; measuring the light diffracted by the OVD or OVM with an integrating sphere; measuring the total incident light on the OVD or OVM; and calculating a diffraction efficiency for the OVD or OVM at the single wavelength based on the measurement of light diffracted and the measurement of total incident light.