| 摘要 |
<p>Coins, medals, tokens, precious metals and other non-fibrous articles protected against counterfeiting by the application of optical thin film systems to at least part of one surface are disclosed. The thin film systems have colors that change with angle of viewing which is difficult to reproduce without specialized expensive equipment. The thin film systems consist of two or more layers composed of metallic, dielectric or semiconducting materials with thicknesses chosen to obtain the desired color change effect. In addition, one or more of the layers may be deposited to ensure good adhesion to the substrate and to provide a base spectral reflectance for the thin film system. An optical protective coating can be the outermost layer of the thin film systems. The resulting optically variable coins, medals, tokens or other non-fibrous articles are subjected to an annealing process to enhance their durability and hardness. The thin films produced in accordance with this invention can withstand stamping operations to add relief to the surface to be protected.</p> |
