| 摘要 |
An optical security device for preventing unlawful copying or counterfeiting has a readable light diffracting record formed by embossing a relief hologram of diffraction grating into an embossable material in which the embossable material is primed with an at least one tinction of a predetermined chromacity such that coherent monochromatic laser light emissions are blocked or substantially inhibited, or are absorbed and re-emitted as coherent semi-monochromatic light of a different, longer, wavelength. |
