Abstract: An optical device is provided that exhibits a variable optical effect upon illumination. The optical device has a diffractive structure comprising: a portion of a first kinoform diffractive structure that encodes a first image, arranged to form a first diffractive region (11) of the diffractive structure; and a portion of a second kinoform diffractive structure that encodes a second image, arranged to form a second diffractive region (13) of the diffractive structure; wherein the first diffractive region and the second diffractive region are laterally separate; and each of the first diffractive region and the second diffractive region are discernible by the naked human eye. Methods of manufacture of such optical devices are also disclosed.

Abstract: A security print medium for forming security documents therefrom, the security print medium comprising a core having opposing first and second sides. The core comprises a radiation-responsive substance distributed within the core across at least a first region of the core, the radiation-responsive substance being responsive to a predetermined input radiation by producing a predetermined output radiation. The security print medium further comprises a first encoding layer disposed on the first side of the core and a second encoding layer disposed on the second side of the core, each of the first and second encoding layers comprising an encoding material that modifies the intensity of the predetermined input radiation and/or the predetermined output radiation produced by the radiation-responsive substance transmitted through the respective encoding layer, wherein the first and second encoding layers overlap each other across the first region.

Abstract: A security device includes: a substrate having a reflective surface; and a printed array of elements on a substantially flat area of the substrate. Each element is formed of a first material which is at least semi-transparent and a second material, the materials having different optical characteristics. Each element has a raised surface profile relative to the substrate including at least first and second sides sloping from the top of the element to at least respective edges of the element, at which the sides meet a substantially flat base surface of the element parallel to the substrate. The sides have different orientations and each lie at an acute angle to the substrate normal. Under illumination away from the substrate normal, when viewed from first and second viewing angles the element appears to have respectively substantially the optical characteristics of the first and second materials.

Abstract: A security device is disclosed, including: a substrate having opposing first and second surfaces; on the first surface of the substrate, a surface relief structure formed of one or more cured, at least semi-transparent material(s); and on the second surface of the substrate, a print layer. In at least a first region of the security device in at least part of which the substrate is transparent or translucent, the surface relief structure and the print layer are each defined in accordance with a common image and are in alignment with one another, the surface relief structure exhibiting a first set of feature(s) of the common image and the print layer exhibiting a second set of feature(s) of the common image. The common image is exhibited by the surface relief structure and the print layer in combination with one another and the surface relief structure provides tactility to the common image.

Abstract: An optical device includes: first grating regions each having a plurality of first grating elements each having a principal component of orientation substantially orthogonal to a first direction; and second grating regions each including a plurality of second grating elements each having a principal component of orientation substantially orthogonal to a second direction. At least a subset of the first grating regions each exhibit a diffractive colour such that a user viewing at a first viewing angle perceives a first diffractive colour image. At least a subset of the second grating regions are achromatic, each including a plurality of grating sub-regions having different respective grating element pitches and arranged such that, for a plurality of second viewing angles, the diffractive colours exhibited by the sub-regions cooperate such that the achromatic grating region is perceived to exhibit diffractive whiteness. The sets of first and second grating regions are interlaced.

Abstract: A security device is provided, including: a surface relief structure formed of one or more cured materials on a substantially flat substrate, the surface relief structure defining a primary set of relief elements at a first scale and a secondary set of relief elements at a second scale which is smaller than the first, the primary set of relief elements including a plurality of raised protrusions spaced by recesses and the secondary set of relief elements being disposed on the tops of at least one of the raised protrusions and/or in at least one of the recesses. A security device including a structure formed of cured material(s) and an embossed structure is also provided. Methods of manufacture are also disclosed.

Abstract: A security device is provided, comprising one or more surface relief structure(s), each formed of one or more cured material(s), the surface relief structure(s) being disposed on a substantially flat substrate and defining a plurality of raised elements spaced from one another, the raised elements corresponding to elements of an image, whereby the plurality of raised elements varies across the surface relief structure(s) so as to exhibit a multi-tonal version of the image. Methods of manufacturing such devices are also disclosed.

Abstract: A security element including a first layer having a first surface, an array of image regions across the surface, each including at least first and second sub-regions, a first array of plasmonic nanostructures in or on the surface across the first sub-regions, defining in each a corresponding portion of a first image, a second array across the second sub-regions, defining in each a corresponding portion of a second image; wherein each sub-region has a respective average inclination and the average inclinations of the first sub-regions are such that the first image is displayed at least at a first viewing angle and those of the second sub-regions are such that the second image is displayed at least at a second viewing angle different from the first and the second image is substantially not or only partially displayed at least at the first angle. Also, a method of manufacturing the security element.

Abstract: A digitally printed security document includes: a security document substrate; a first digitally printed print working on a first surface of the substrate in a first region, the first print working including a first array of printed elements arranged according to a first grid of lattice points having a first pitch; and a second digitally printed print working on the first surface of the substrate in a second region, the second print working including a second array of printed elements arranged across a second grid of lattice points having a second pitch different from the first pitch.

Abstract: A security element including: a first layer having a first surface; an array of image regions across the surface, each region including at least first and second sub-regions; a first diffractive optically variable effect generating structure in or on the surface across the first sub-regions; and a second diffractive optically variable effect generating structure in or on the surface across the second sub-regions; wherein the surface is arranged so each first sub-region has a first average inclination and each second sub-region has a second average inclination different from the first, wherein the first structure and inclination provide that the first effect is exhibited across the first sub-regions at least at a first viewing angle and the second structure and inclination provide that the second effect is exhibited across the second sub-regions at least at a second viewing angle different from the first. Also, a method of manufacturing the security element.

Abstract: A method for forming an optical device and an optical device, wherein upon illumination, exhibits diffractive images dependent upon viewing angle, the device having a diffractive structure including grating regions, each region corresponding to a component of a respective diffractive image, wherein: each region of the diffractive structure includes grating elements along a first direction having a principal orientation component within the device plane that is substantially orthogonal to the first direction; wherein, the grating elements within each grating region have a constant pitch and the same orientation wherein each grating region, upon illumination, exhibits a diffractive color wherein the corresponding diffractive image is exhibited; wherein, the diffractive structure includes first and second grating regions elongated along a common first direction, the regions being adjacent along the first direction, and wherein the pitch and/or orientation of the grating elements of the first and second grating r

Abstract: A method of inspecting a substantially transparent light control layer for an optically variable security device and a corresponding inspection apparatus, the substantially transparent light control layer including a surface relief defined by an array of substantially transparent refractive microstructures. The method includes: directing a beam of substantially collimated light towards a first region that is expected to contain the surface relief of the light control layer so as to generate an inspection light pattern; providing reference data that is indicative of a light control layer that meets a predetermined quality threshold; comparing the inspection light pattern with the reference data; and determining whether the light control layer meets the predetermined quality threshold based on the comparison.

Abstract: A security device includes a diffractive structure, including grating elements and having a first area, the grating elements within a region have a constant pitch or spacing; the first area regions pitches or spacings increase from one region to the next between a first region having a grating element pitch or spacing of less than or equal to 0.6 microns and an end region having a grating element pitch or spacing of greater than or equal to 5 microns; upon illumination and viewing along a first viewing direction substantially orthogonal to the first axis, the device exhibits a first optical effect in that at least one region exhibits a diffractive colour; each region has at least first and second sub-regions having different grating element orientations within the plane of the device such that the first optical effect is exhibited at more than one angle of tilt about the second axis.

Abstract: A method of forming a security device includes: a holographic image layer, diffusion element, and barrier layer. A region of the barrier layer includes a heat-transformable material. The method further includes selectively applying heat at a plurality of positions within the region of the barrier layer, in accordance with a predetermined pattern, so as to modify the heat-transformable material such that the region of the barrier layer is selectively rendered passable to the diffusible substance at each of the plurality of positions, thereby permitting diffusion of the diffusible substance between the regions of the diffusion element and the holographic image layer such that, at a plurality of positions within the region of the holographic image layer and corresponding to the predetermined pattern, the volume hologram is dimensionally modified so as to become viewable in a second observable colour, different from the first observable colour.

Abstract: A security device is provided, comprising: a colour shifting element that exhibits different wavelengths of light at different viewing angles, and; an at least partially transparent light control layer covering at least a part of the colour shifting element and comprising a surface relief adapted to modify the angle of light from the colour shifting element, wherein; a first region of the light control layer comprises a first optical characteristic, whereby light at a first viewing angle from the first region of the light control layer is perceived to have a resultant optical effect that is the resultant of the wavelength of light exhibited at that viewing angle due to the combination of the colour shifting element and the surface relief of the light control layer, and the first optical characteristic, and; a second region of the light control layer either: (i) is substantially colourless such that light at the first viewing angle from the second region is perceived to have a resultant optical effect exhibite

Abstract: A method of manufacturing a document of a series identical documents in content except for a respective identifier which identifies each document within the series, each identifier having at least a first indicium, the or each indicium defining a boundary; the method having the steps of: providing a substrate; applying a first background print, defining part of the boundary of an indicium receiving area; applying the respective identifier on the substrate, such that the first indicium is provided in the indicium receiving area; the first background print and the respective identifier being applied such that when the document is viewed in at least one of transmission and reflection the juxtaposition of the first background print and the first indicium is such that a keyline extending around a portion of the boundary of the first indicium is defined between the first indicium and the boundary of the indicium receiving area.

Abstract: A security print medium for forming security documents therefrom, the security print medium comprising a core having opposing first and second sides. The core comprises a radiation-responsive substance distributed within the core across at least a first region of the core, the radiation-responsive substance being responsive to a predetermined input radiation by producing a predetermined output radiation. The security print medium further comprises a first encoding layer disposed on the first side of the core and a second encoding layer disposed on the second side of the core, each of the first and second encoding layers comprising an encoding material that modifies the intensity of the predetermined input radiation and/or the predetermined output radiation produced by the radiation-responsive substance transmitted through the respective encoding layer, wherein the first and second encoding layers overlap each other across the first region.

Abstract: device includes an array of reflective sampling elements. A non-dispersive colour-generating relief structure is formed in a surface of the reflective sampling elements. The non-dispersive colour-generating relief structure defines an array of image elements across the array of reflective sampling elements. The array of image elements defined by the non-dispersive colour-generating relief structure and the array of reflective sampling elements cooperate to exhibit an optically variable effect.

Abstract: A security device includes an array of reflective elements including at least first and second sets of reflective elements, which are regularly or irregularly interlaced along at least a first interlacing direction across a first area of the security device. A non-dispersive colour-generating structure is in the surface of first and/or second sets of reflective elements. The first set of reflective elements is configured to collectively exhibit a first image across the first area of the security device to a viewer within a first viewing zone and direct incident light convergently and/or divergently towards this zone. The second set of reflective elements is configured to collectively exhibit a second image across the first area of the security device to the viewer within a second viewing zone. The structure is modulated across the first and/or second sets of reflective elements such that the first and/or second images include multiple colours.

Abstract: There is described a printing press (100***; 100****) adapted to carry out printing on a sheet-like or web-like substrate (S), in particular for the production of security documents such as banknotes, comprising a printing unit (2*; 2**; 2***; 2****) designed to print a first side (I) and/or a second side (II) of the substrate (S). The printing press (100***; 100****) further comprises an in-line casting device (80; 80*; 80**; 80***) adapted to apply a layer of material acting as an optical medium on a portion of a first side (I, II) of the substrate (S) and to replicate and form a micro-optical structure (L) in the layer of material acting as optical medium.