An optical device is formed by hot stamping a demetallized hologram to an optically variable foil or to a coating of optically variable ink. In another embodiment a hologram is hot stamped to a banknote or document printed with a color-shifting ink.

A device for producing a master diffraction grating includes a light source unit and a reflecting member 11. The light source unit forms a first interference fringe by irradiating a substrate surface of a master substrate 101 with light. The reflecting member 11 reflects the light from the light source unit reflected on the substrate surface of the master substrate 101 and guides the light again to the substrate surface side to form a second interference fringe. A resist pattern based on the first interference fringe and the second interference fringe is formed on the substrate surface of the master substrate 101.

There is provided a holographic optical element including: a hologram portion including a plurality of groups of unit regions, each group of unit regions of the hologram portion being configured to produce a respective holographic image under a respective light illumination having a respective predetermined wavelength; and a colour filter portion formed on the hologram portion, the colour filter portion including a plurality of groups of unit regions, each group of unit regions of the colour filter portion being arranged on a corresponding group of the plurality of groups of unit regions of the hologram portion, whereby the plurality of groups of unit regions of the colour filter portion is spatially arranged to form a predetermined colour image. There is also provided a method of forming the holographic optical element. There is further provided an article having optical security incorporated therein.

An object of the present invention is to provide a thin volume hologram sheet to be embedded sufficiently resistant to a mechanical stress such as a stress including a tensile stress, a shear stress and a compression stress at the time of processing even under a heating condition, a forgery prevention paper and a card using the same. The object is achieved by providing a volume hologram sheet to be embedded comprising a volume hologram layer, and a substrate disposed only on one side surface of the volume hologram layer using an adhesion means, wherein a peeling strength of the volume hologram layer and the substrate is 25 gf/25 mm or more.

There are provided volume holograms and combinations of lenticular lenses and holograms in particular for security applications. In embodiments, a volume hologram comprises a holographic medium (102) including a first optical interference structure which, upon illumination, replays a first image (110); wherein the first image includes a lenticular lens layer (111) including an array of lenticules and a lenticular image layer (113) including first (114) and second (115) interlaced images corresponding with the array of lenticules.

A method for determining the validity of a parallax image, comprising: receiving a captured two-dimensional image of a parallax image having at least three target identifiers, where at least two target identifiers are located at different depth planes in the parallax image; identifying the at least three target identifiers in the captured two-dimensional image of the parallax image and determining the spatial relationship between the at least three target identifiers in the two-dimensional image of the parallax image; comparing the spatial relationship of the at least three target identifiers in the captured two-dimensional image of the parallax image against a predetermined spatial relationship of the at least three target identifiers that indicates authenticity; and adjudicating the authenticity of the parallax image based on the degree of difference between the spatial relationship of the at least three target identifiers in the captured two-dimensional image of the parallax image and the predetermined spatial relationship of the at least three target identifiers.

Object marking, and method for producing same, for optical authentication of an object, wherein at least one section of a material piece of a basic material is determined arbitrarily or randomly and the object marking is produced with the at least one section, and wherein the basic material of the material piece has a repeating security feature having optical properties dependent on the viewing angle, the dimensions of said security feature being larger than the dimensions of the section, more particularly larger than the dimensions of the object marking, such that each section is unique and has only a part of the security feature.

Object marking, and method for producing same, for optical authentication of an object, wherein at least one section of a material piece of a basic material is determined arbitrarily or randomly and the object marking is produced with the at least one section, and wherein the basic material of the material piece has a repeating security feature having optical properties dependent on the viewing angle, the dimensions of said security feature being larger than the dimensions of the section, more particularly larger than the dimensions of the object marking, such that each section is unique and has only a part of the security feature.

A method for determining the validity of a parallax image, including: receiving a parallax image's captured two-dimensional image having at least three target identifiers, where at least two target identifiers are located at different depth planes in the parallax image; identifying at least three target identifiers in the parallax image's captured two-dimensional image and determining spatial relationship between at least three target identifiers in the two-dimensional image of the parallax image; comparing the spatial relationship of at least three target identifiers in the parallax image's captured two-dimensional image against a predetermined spatial relationship of at least three target identifiers that indicates authenticity; and adjudicating the authenticity of the parallax image based on the degree of difference between spatial relationship of at least three target identifiers in the parallax image's captured two-dimensional image and the predetermined spatial relationship of at least three target identifiers.

A system includes a plurality of optical identifiers and a reader for the optical identifiers. Each optical identifier has an optical substrate and a volume hologram (e.g., with unique data, such as a code page) in the optical substrate. The reader for the optical identifiers includes a laser, and a camera. The laser is configured to direct laser light into a selected one of the optical identifiers that has been placed into the reader to produce an image of the associated volume holograms at the camera. The camera is configured to capture the image. The captured image may be stored in a digital format by the system.