There is provided an optical structure having a quantization phase difference structure on one surface of a quantization phase difference structure layer, wherein in the quantization phase difference structure, a plurality of quantization projecting portions in a constant size and a plurality of quantization recessed portions in a constant size are aligned, wherein a multiple diffraction region has the quantization phase difference structure where ribbed projecting portions, in which the quantization projecting portions are aligned in one direction, are arranged adjacent to and alternately with groove-like recessed portions, in which the quantization recessed portions are aligned parallel to the ribbed projecting portions, and wherein the multiple diffraction region is a quantization phase difference structure configured to reproduce a plurality of reproduction points discrete in one direction and arranged regularly.

There is provided an optical structure having a quantization phase difference structure on one surface of a quantization phase difference structure layer, wherein in the quantization phase difference structure, a plurality of quantization projecting portions in a constant size and a plurality of quantization recessed portions in a constant size are aligned, wherein a multiple diffraction region has the quantization phase difference structure where ribbed projecting portions, in which the quantization projecting portions are aligned in one direction, are arranged adjacent to and alternately with groove-like recessed portions, in which the quantization recessed portions are aligned parallel to the ribbed projecting portions, and wherein the multiple diffraction region is a quantization phase difference structure configured to reproduce a plurality of reproduction points discrete in one direction and arranged regularly.

A printing ink having a first fluorescent dye acting as donor and a second fluorescent dye acting as acceptor. The first fluorescent dye, upon excitation by electromagnetic radiation falling within an excitation wavelength range λ.sub.1a of the first fluorescent dye, is capable of emitting electromagnetic radiation in at least one first emission wavelength range λ.sub.1e, said first emission wavelength range λ.sub.1e of the first fluorescent dye overlapping with at least one excitation wavelength range λ.sub.2a of the second fluorescent dye, to thereby excite the second fluorescent dye to emit electromagnetic radiation in a second emission wavelength range λ.sub.2e.

There is provided a luminescent medium which requires difficult analysis of light emitted from a luminescent material of the medium. A luminescent medium 10 includes a substrate 11, and a luminescent material 12 comprising a first luminescent material 12A which, when irradiated with visible light, infrared light or ultraviolet light, emits first infrared light “a”, and a second luminescent material 12B which, when irradiated with visible light, infrared light or ultraviolet light, emits second infrared light “b”. The first luminescent material 12A is formed in a first planar area 11A, and the second luminescent material 12B is formed in a second planar area 11B. The first planar area 11A and the second planar area 11B overlap each other, forming an overlapping planar area 11C in which the luminescent materials 12A and 12B each have a concentration gradation.

Ultrathin plasmene nanosheets are demonstrated as a new class of flexible surface enhanced Raman scattering (SERS) substrate capable of conformal attachment and sensitive and reproducible detection of chemicals on topologically complex surfaces. Engineering building block morphologies allows for fine-tuning of the SERS performance. In a preferred application the plasmene nanosheets are demonstrated as the next generation plasmonic and/or SERS coded labels, such as for example, anti-counterfeit security label for banknotes. Engineering the morphologies of plasmene-constituent nanoparticles and varying of SERS molecular labels offer virtually unlimited coding capacities.

Ultrathin plasmene nanosheets are demonstrated as a new class of flexible surface enhanced Raman scattering (SERS) substrate capable of conformal attachment and sensitive and reproducible detection of chemicals on topologically complex surfaces. Engineering building block morphologies allows for fine-tuning of the SERS performance. In a preferred application the plasmene nanosheets are demonstrated as the next generation plasmonic and/or SERS coded labels, such as for example, anti-counterfeit security label for banknotes. Engineering the morphologies of plasmene-constituent nanoparticles and varying of SERS molecular labels offer virtually unlimited coding capacities.

A banknote having one or more security features and at least one flexible printed electronic (FPE) element embedded in the banknote. At least one of the security features and at least one FPE element have an interrelationship with each other.

A banknote having one or more security features and at least one flexible printed electronic (FPE) element embedded in the banknote. At least one of the security features and at least one FPE element have an interrelationship with each other.

An optical device includes an array of lenses and a plurality of first and second segments disposed under the array of lenses. At a first viewing angle, the array of lenses presents a first image for viewing without presenting the second image for viewing, and at a second viewing angle different from the first viewing angle, the array of lenses presents for viewing the second image without presenting the first image for viewing. In some examples, individual ones of the first and second segments can comprise specular reflecting, transparent, diffusely reflecting, and/or diffusely transmissive features. In some examples, individual ones of the first and second segments can comprise transparent and non-transparent regions. Some examples can incorporate more than one region producing an optical effect.

An optical device includes an array of lenses and a plurality of first and second segments disposed under the array of lenses. At a first viewing angle, the array of lenses presents a first image for viewing without presenting the second image for viewing, and at a second viewing angle different from the first viewing angle, the array of lenses presents for viewing the second image without presenting the first image for viewing. In some examples, individual ones of the first and second segments can comprise specular reflecting, transparent, diffusely reflecting, and/or diffusely transmissive features. In some examples, individual ones of the first and second segments can comprise transparent and non-transparent regions. Some examples can incorporate more than one region producing an optical effect.