Nondiffractive optically variable security devices
Rudolf L. van Renesse · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1991
This paper discusses security applications of reversible photosensitivity that resulted from a search in SECURIDAT--viz. dual fluorescence with longwave remanence, thermochroism, stimulation of mixed inorganic phosphors, and photochroism.