Abstract: A method of marking a thermoplastic article can comprise: combining a thermoplastic with a light-marking additive to form a composition, forming the composition into an article having a maximum optical absorption wavelength; and illuminating, at a marking wavelength, at least a portion of the article with a device having a power of less than or equal to about 200 mW, to form a light-mark. The light-mark can have a size, as measured along a major axis, of greater than or equal to about 10 micrometers. The light-mark can also have a mark absorption wavelength that is greater than or equal to about ±100 nm of the maximum optical absorption wavelength, and can have a spectral absorption curve.

Abstract: A molded article is formed by molding a holographic recording material into a shape that is determined by the function of an molded article and a volume hologram is formed in the molded article. Alternatively, only a portion of the molded article is formed from the holographic recording medium, or a molded article is formed by molding a thermoplastic into a shape that is determined by the function of the article, and then this article is then coated, for example by dip-coating, with a holographic recording medium, and al volume hologram is formed in the coating of the molded article.

Abstract: One method for playing a disk, comprises illuminating a first portion of the optical article with a first laser to obtain a first optical signal, wherein the first laser has a first wavelength, illuminating a second portion with a second laser to obtain a second optical signal, wherein the second laser has a second wavelength that is different from the first wavelength, and determining if the optical article is authentic by comparing the first optical signal and the second optical signal.

Abstract: Limited-play optical medium with improved shelf stability are formed from a plurality of layers, including in sequence: (a) a first substrate layer; (b) a data layer; (c) a reflective layer; (d) a reactive layer comprising a dye having a reduced state and an oxidized state and further comprising an oxidized form of a reducing agent effective to convert the dye from the oxidized state to the reduced state, and (e) a second substrate layer. The dye in the reduced state is substantially transparent to light of wavelengths used to read the optical medium, and the dye in the oxidized state absorbs light of wavelengths used to read the optical medium. The reflective metal layer is formed from a metal or metal alloy that is not significantly oxidized by the oxidized form of the reducing agent. For example, the reflective metal layer is suitably formed from silver or gold.

Abstract: Limited-play optical medium with improved shelf stability are formed from a plurality of layers, including in sequence: (a) a first substrate layer; (b) a data layer; (c) a reflective layer; (d) a reactive layer comprising a dye having a reduced state and an oxidized state and further comprising an oxidized form of a reducing agent effective to convert the dye from the oxidized state to the reduced state, and (e) a second substrate layer. The dye in the reduced state is substantially transparent to light of wavelengths used to read the optical medium, and the dye in the oxidized state absorbs light of wavelengths used to read the optical medium. The reflective metal layer is formed from a metal or metal alloy that is not significantly oxidized by the oxidized form of the reducing agent. For example, the reflective metal layer is suitably formed from silver or gold.