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.

Disclosed herein is a method for forming a surface relief microstructure, including the steps of A) applying a curable composition to at least a portion of the frontside of the paper substrate, B) contacting at least a portion of the curable composition with surface relief microstructure, C) curing the composition by using at least one UV lamp which is arranged on the backside of the paper substrate, and D) depositing a metallic layer, and optionally a layer of a transparent high refractive index material, on at least a portion of the cured composition, wherein the UV lamp has an emission peak in a UV-A range of 320 nm to 400 nm and additionally in a near VIS range of 400 nm to 450 nm, the curable composition comprises a photoinitiator which absorbs in the UV-A range and also in the near VIS range.

An optical film including a recording surface on which a plurality of unit blocks is disposed at regular intervals. For these unit blocks, phase components of light from a reconstruction point are calculated. The recording surface includes a calculated element region provided with an array of the unit blocks for which phase components of light from the reconstruction point are calculated for reproduction of an image. A first image is a monotone reconstruction image having even brightness, and a second image is a grayscale image having brightness gradation.

Disclosed herein is a method for forming a surface relief microstructure, including the steps of A) applying a curable composition to at least a portion of the frontside of the paper substrate, B) contacting at least a portion of the curable composition with surface relief microstructure, C) curing the composition by using at least one UV lamp which is arranged on the backside of the paper substrate, and D) depositing a metallic layer, and optionally a layer of a transparent high refractive index material, on at least a portion of the cured composition, wherein the UV lamp has an emission peak in a UV-A range of 320 nm to 400 nm and additionally in a near VIS range of 400 nm to 450 nm, the curable composition comprises a photoinitiator which absorbs in the UV-A range and also in the near VIS range.

There is provided a method of forming a metallic structure on an optical element comprising a surface relief structure, the method comprising: applying a metal-containing ink to said surface relief structure to form said metallic structure, wherein the metal-containing ink comprises one or more organic solvents and one or more of: a homogeneously soluble metal salt; a metal complex; or metallic nanoparticles having a size of less than 50 nm.

A method and an apparatus for forming a surface relief microstructure, especially an optically variable image on a paper substrate are provided, the method comprising the steps of: A) applying a curable composition to at least a portion of the frontside of the paper substrate; B) contacting at least a portion of the curable composition with surface relief microstructure, especially optically variable image forming means; C) curing the composition by using at least one UV lamp (1, 2, 3) which is arranged on the backside of the paper substrate; D) optionally depositing a layer of a transparent high refractive index material and/or a metallic layer on at least a portion of the cured composition, wherein the lamp (1, 2, 3) having emission peak(s) in the UV-A and near VIS range and the curable composition comprises at least a photoinitiator which absorbs in the UV-A region and preferably in the near VIS range. A paper product obtainable uses the method and an apparatus for forming a surface relief microstructure on a paper substrate. Surface relief microstructures, such as holograms may be replicated rapidly and with accuracy on a paper substrate by using the method and the apparatus.

A counterfeit prevention structure including a concave/convex formation layer having a surface and including a first concave/convex structure in a first portion of the surface and a second concave/convex structure in a second portion of the surface, and a reflective layer formed on the second concave/convex structure in the second portion. The first and second concave/convex structures are formed such that the first concave/convex structure has a depth-to-width ratio greater than a depth-to*width ratio of the second concave/convex structure, and that a light transmittance is higher in the first portion than in the second portion.

An image display device includes image cells arranged two-dimensionally. Each image cell has a hologram layer. The hologram layer includes a diffraction grating in which a one-dimensional grating pattern extending in a first direction is repeated in a second direction perpendicular to the first direction. Among the plurality of image cells, two or more image cells that are in a row in the second direction and correlated to one color constitute one image cell group. The image cell group includes a section in which the spatial frequency of the diffraction grating is proportionately small as the distance in the second direction from one end of the image cell group increases such that, while a viewpoint is positioned at a predetermined angle relative to an image display device, the two or more image cells constituting the image cell group display the same color as each other.

A liquid crystal laminate includes a substrate including a first diffraction surface and a second base material surface and having optical transparency, a metal layer located on a part of the first diffraction layer, an adhesion layer located on a part of the second base material layer and made of a photocured resin, and liquid crystal layer located on a surface of the adhesion layer at a side opposite to the contact surface of the substrate.

A forgery prevention structure, in one configuration, includes a relief forming layer, a first reflection layer, a functional thin film layer, a second reflection layer and a protection layer in this order. In this configuration, the relief forming layer has a relief structure comprising a first relief and a second relief; each of the reliefs has an uneven surface, a surface area of the uneven surface of the first relief being smaller than a surface area of the uneven surface of the second relief; the first reflection layer and the functional thin film layer each are provided along a whole of the uneven surfaces of the reliefs and each has uneven surfaces corresponding respectively to the uneven surfaces of the reliefs; and the second reflection layer and the protection layer each has an uneven surface corresponding to the uneven surface of the first relief.