Marking of materials using luminescent and optically stimulable glasses

Abstract

Objects are marked for identification by a luminescent label including an optically stimulable glass having trapping centers and luminescence centers. The objects are marked by exposing the luminescent label to a radiation flux to populate metastable trapping centers in the luminescent label. The labels are read by exposing the label to a second radiation flux of optical radiation, to stimulate the release of trapped charges, causing the label to luminesce. The labels may also be read without previously populating these metastable trapping centers, by stimulating prompt luminescence through exposure to a flux of UV radiation. The label is made from an optically stimulable glass, where this glass has a glass matrix with defects, where these defects may be: (i) an alkaline earth sulfide, activator Sm ions, and an additional coactivator dopant (Eu or Ce); (ii) ZnS and activator ions (Cu, Pb, Mn, Ce, Eu, Ag, Au, or Fe); or (iii) activator ions without metal sulfides.

Dependencies are inferred from the claim text.