Abstract: A method and apparatus for viewing or authenticating a diffractive device and a diffractive security device (1) are provided in which a first diffractive relief structure (200) is responsive to a first wavelength of visible monochromatic light, a second diffractive relief structure (200) is at least partially interlaced with the first diffractive relief structure (100) and responsive to a second wavelength of visible monochromatic light, and a third diffractive relief structure (400) is at least partially interlaced with the first and second diffractive relief structures (100, 200) and responsive to a third wavelength of visible monochromatic light.

Abstract: An optical security device is disclosed which includes a diffraction layer having a plurality of diffraction elements and a high refractive index layer, wherein the high refractive index layer is applied on the diffraction layer such that selected regions of the diffraction layer have the corresponding diffraction elements partially uncovered by the high refractive index layer and other regions are substantially covered by the high refractive index layer. Accordingly, the optical security device has a first security feature associated with the diffraction layer and a second security feature associated with the high refractive index layer. An image is viewable from the regions of the high refractive index layer, either, covertly by placed an index matched item over the device or, overtly, through selection of the thickness of the high refractive index layer.

Abstract: A method of manufacturing a security document comprising the steps of providing a transparent plastics substrate, applying a radiation curable ink directly to at least side of the substrate and simultaneously embossing and curing with radiation different regions in the same area of the ink on one side of the substrate with at least two different embossed relief structures, each forming a different type of diffractive security element integrated within the same area to form a composite security device.

Abstract: An optical security device (10; 700) is provided which includes a transparent or translucent substrate (15; 705), at least one first array of repeating elements (20; 720) in or on a first side (16; 706) of the substrate (15; 705), at least one second array of repeating elements (30; 730) on a second side of the substrate. The second array of repeating elements (20; 720) is substantially in register with the first array of elements (30; 730), whereby a first image (130; 725) is visible when viewing the device from the first side, and a second image (200; 735) is visible when viewing the device from the second side. The brightness or colour levels of repeating image elements (30; 720, 730) on at least one side of the substrate may be modulated region-wise to produce a greyscale or coloured image.

Abstract: An optical security device, including a substrate (102) having a first surface and a second surface; and a metallic nanoparticle ink (104) provided intermittently in at least one area on the first surface (102) to produce a reflective or partially reflective patch or patches; wherein a high refractive index coating (106) is applied over the area or areas (108) in which the metallic nanoparticle ink is provided, the high refractive index coating (106) adhering to the first surface (102) where the metallic nanoparticle ink is not present, thereby retaining the metallic nanoparticle ink (104) between the first surface (102) and the high refractive index coating (106).

Abstract: A method and apparatus for viewing or authenticating a diffractive device and a diffractive security device (1) are provided in which a first diffractive relief structure (200) is responsive to a first wavelength of visible monochromatic light, a second diffractive relief structure (200) is at least partially interlaced with the first diffractive relief structure (100) and responsive to a second wavelength of visible monochromatic light, and a third diffractive relief structure (400) is at least partially interlaced with the first and second diffractive relief structures (100, 200) and responsive to a third wavelength of visible monochromatic light.

Abstract: A security document and a method of manufacturing a security document are provided in which a radiation curable ink is applied to at least one side of a substrate including at least one region of transparent plastics material forming a window or half-window area. The ink is embossed while soft and cured with radiation to form an embossed security device within the window or half-window area including one or more of a diffractive structure, a lens structure or other security element having a relief structure.

Abstract: A polarising security element for polarising light of a predetermined wavelength including a first dielectric material having a refractive index nb and at least one polarising region of mutually parallel segments of a second material having a refractive index np which is different from nb, the second material being a dielectric or conducting material. The segments of the second material are in contact with the first material and the segments have a width and/or an average spacing which is less than a predetermined range of wavelengths. A method of manufacturing such a security element in which a relief structure is embossed in the layer of the first dielectric material, the relief structure includes mutually parallel peaks and troughs, and the second layer of dielectric or conducting material is applied on the relief structure to form the at least one polarising region of mutually parallel segments.

Abstract: High refractive index coatings having metal oxide particles are disclosed. Dispersions of metal oxide particles in solvent are also disclosed. These find use in the protection of surface relief structures. In some disclosed embodiments, the coatings or dispersions contain UV-curable resins. The coatings and dispersions find application in the field of security devices and documents and tokens incorporating security devices.

Abstract: A security document (1) is provided having a substrate (4) and an integral security device (10) which includes an image layer (12) and a focussing layer (11). each formed from a radiation curable ink layer embossed with relief formations (13; 15). The first radiation curable layer embossed with relief formations (13) to form the image layer (12) is provided on a first surface of the document, and the second radiation curable layer (11) embossed with focussing element relief formations (15) is provided on a second surface of the document. The first and second surfaces are separated by a predetermined distance D to produce a visible optical effect when viewing the image layer (12) through the focussing layer (11). In preferred embodiments, at least one of the first and second radiation curable layers is embossed with diffractive relief structures and high refractive index or reflective coatings may be applied to the embossed relief formations in the image layer (12) and/or the focussing layer (11).

Abstract: A method of producing a security document or article including a substrate (100), which is transparent at least to visible light, and a diffractive optical microstructure (112). The method includes applying an opacifying layer (102) to at least one surface of the transparent substrate (100). An area of the opacifying layer (102) is exposed to laser radiation (108) to ablate apertures (110) in selected portions of the opacifying layer (102), thereby forming a diffractive optical microstructure (112) on the surface of the substrate (100). The laser radiation may be patterned prior to exposing the opacifying layer (102), for example by passing the radiation through a mask (104). Alternatively, a focussed or collimated laser beam (206) may be directed onto the selected portions of the opacifying layer (102). Laser radiation may be directed onto the opacifying layer (102) either directly, or through the transparent substrate (100).

Abstract: Various methods of producing a security document or article including a diffractive optical microstructure are disclosed. One method includes applying an opacifying layer (102) to at least one surface of a transparent substrate (100). An area of the opacifying layer (102) is exposed to laser radiation (108) to ablate apertures (110) in selected portions of the opacifying layer (102), thereby forming a diffractive optical microstructure (112) on the surface of the substrate (100). The laser radiation may be patterned prior to exposing the opacifying layer (102), for example by passing the radiation through a mask (104). Alternatively, a focussed or collimated laser beam (206) may be directed onto the selected portions of the opacifying layer (102). Laser radiation may be directed onto the opacifying layer (102) either directly, or through the transparent substrate (100). Security documents or articles made in accordance with the method are also provided.

Abstract: A diffractive optical element (DOE) and various methods of producing such a DOE are provided in which a diffractive optical microstructure is formed with encrypted data on at least one side of a transparent substrate or in a layer applied to the substrate. The diffractive optical microstructure when illuminated with collimated light, generates a far field interference pattern corresponding to the encrypted data which may be decrypted with suitable optical detectors and processing equipment.

Abstract: A method of producing a personalized security document or article includes providing a substrate which is transparent at least to visible light. A diffractive optical microstructure is formed in a substantially opaque layer disposed on a surface of the substrate. The diffractive structure comprises a plurality of apertures formed in the opaque layer, such that when the structure is suitably illuminated, for example by a beam of collimated light, a projected image is generated which is unique to a particular individual. Also, personalized security documents or articles made in accordance with the method.

Abstract: A security document or device is provided which incorporates one or more optical components. Each component includes at least one orientating layer, preferably a photo-orientated polymer network (PPN), and at least one liquid crystal polymer (LCP) layer, and either or both of the orientating layers and LCP layers include a cross-linker to improve the robustness of the document or device without detracting from the desired optical properties. Such a document or device can be authenticated using an external polariser, or using a polariser integral to the document or device itself.

Abstract: A method and apparatus for inspection of a security article (10) is provided in which a substantially collimated light beam (15) from a point light source (14) is directed onto a diffractive optical projection element (DOE) (11). The light beam is transformed by the DOE (11) into a patterned beam (17) which is reconstructed to form a projected image at a particular position in space remote from the surface of the security article 910). An optical detection device 916) is located at which the patterned beam (17) is reconstructed to detect the projected image. The inspection method and apparatus may be used in equipment for handling, sorting, counting or otherwise processing security articles, in particular security documents such as banknotes. The apparatus may include a processor for generating a signal when the absence or poor quality of a DOE is detected and which is used to isolate or mark the security article.

Abstract: A method of protecting a security document from counterfeiting includes applying at least one security element containing a concealed Fourier pattern to the document. The concealed Fourier pattern is produced from a master Fourier profile, and is applied to the document by embossing, engraving, laser ablation or chemical etching, and/or by a cylinder or plate bearing the master Fourier profile. When a counterfeit security document produced without knowledge of the master Fourier profile is scanned or imaged and subjected to a Fourier transform, the resulting test Fourier pattern will differ from a master Fourier pattern corresponding to the master Fourier profile for the authentic security document. In a particular embodiment, the concealed Fourier pattern is applied to the document by rotogravure printing.

Abstract: A security document and a method of manufacturing a security document are provided in which a radiation curable ink is applied to at least one side of a substrate including at least one region of transparent plastics material forming a window or half-window area. The ink is embossed while soft and cured with radiation to form an embossed security device within the window or half-window area including one or more of a diffractive structure, a lens structure or other security element having a relief structure.

Abstract: A method and apparatus for inspection of a security article (10) is provided in which a substantially collimated light beam (15) from a point light source (14) is directed onto a diffractive optical projection element (DOE) (11). The light beam is transformed by the DOE (11) into a patterned beam (17) which is reconstructed to form a projected image at a particular position in space remote from the surface of the security article 910). An optical detection device 916) is located at which the patterned beam (17) is reconstructed to detect the projected image. The inspection method and apparatus may be used in equipment for handling, sorting, counting or otherwise processing security articles, in particular security documents such as banknotes. The apparatus may include a processor for generating a signal when the absence or poor quality of a DOE is detected and which is used to isolate or mark the security article.

Abstract: A method and apparatus for manufacturing an optical component having at least one photo-oriented polymeric layer is provided. The apparatus includes a single source of laser radiation, beam splitting means for splitting the laser radiation into a first beam of linearly polarized light having a first plane of polarization (P) and a second beam of linearly polarized light having a second plane of polarization (S), first directing means for directing the first beam of linearly polarized light onto a first area or areas of at least one photo-orientatable polymeric layer to cause a first molecular orientation in said first area or areas of the layer and second directing means for directing the second beam of linearly polarized light onto said photo-orientatable polymeric layer to cause a second molecular orientation in a second area or areas of the layer.