Abstract: An optical security label for security and anti-counterfeit applications comprises a first layer having an optically variable portion (diffractive, holographic or interference film) generating an optically variable effect secured to a support layer by a weak adhesive layer such that the first layer can be scratched off the third support layer to reveal underlying data and the label is affixed to a substrate by a pressure sensitive adhesive. The label or substrate carry the data to be protected such a printed or personalized paper or plastic substrate. In one aspect the scratch off region is patterned and also the data can comprise a pattern of alternate scratch off and permanent areas. In one aspect the label is a thin frangible structure delivered to the substrate with a weakly bound top carrier. In another aspect the optical variable device includes a covert image authenticated by a decoder carried on the top of the removable carrier.

Abstract: A diffuse reflector comprises a substrate (20) having an asymmetric, reflective, periodic surface relief microstructure formed such that, under illumination by a multiplicity of wavelengths in a plane of incidence or illumination lying along the axis of asymmetry, substantially all the said wavelengths are preferentially scattered or guided into a single, common viewing zone offset from the direction of specular reflection hereinbefore defined.

Abstract: The present invention provides for a method of producing an optical device by means of electron beam lithography and including the step of varying the characteristics of the electron beam spot during formation of the device and also an apparatus for producing diffractive optical devices and/or holographic devices by means of electron beam lithography and including an electron beam lithograph, controlling and processing means, means for varying the characteristics of the electron beam spot during formation of the device, and wherein the processing means is arranged for compiling and pre-processing data and for providing optimization and allocation control and to optical devices such as those produced thereby.

Abstract: The present invention provides for a method of producing an optical device by means of electron beam lithography and including the step of varying the characteristics of the electron beam spot during formation of the device and also an apparatus for producing diffractive optical devices and/or holographic devices by means of electron beam lithography and including an electron beam lithograph, controlling and processing means, means for varying the characteristics of the electron beam spot during formation of the device, and wherein the processing means is arranged for compiling and pre-processing data and for providing optimization and allocation control and to optical devices such as those produced thereby.

Abstract: A diffuse reflector comprises a substrate (20) having an asymmetric, reflective, periodic surface relief microstructure formed such that, under illumination by a multiplicity of wavelengths in a plane of incidence or illumination lying along the axis of asymmetry, substantially all the said wavelengths are preferentially scattered or guided into a single, common viewing zone offset from the direction of specular reflection hereinebefore defined.

Abstract: An optically variable security device comprising a thin film reflection filter structure (23) which exhibits a first optically variable effect; and a relief structure (20) on or in the thin film reflection filter structure which exhibits a second optically variable effect.

Abstract: A security device includes a holographic optically variable effect generating structure having at least two discrete section. The sections that generate in response to white light illumination an optically variable image having at least two defined graphical elements located at or near an image plane either on or adjacent to the plane of the device. In response to coherent illumination, the sections generate at least two discrete covert images, in the form of indicia, whose image planes are located at a distance away from the real place of the device. The covert images are reconstructed at different angles to a normal to a substrate supporting the device such that the covert images are spatially separated on their image plane, the covert images being non-visible under white light illumnination.

Abstract: A diffuse reflector comprises a substrate (20) having an asymmetric, reflective, periodic surface relief microstructure formed such that, under illumination by a multiplicity of wavelengths in a plane of incidence or illumination lying along the axis of asymmetry, substantially all the said wavelengths are preferentially scattered or guided into a single, common viewing zone offset from the direction of specular reflection hereinebefore defined.

Abstract: A security device comprises an optically variable effect generating structure (3,4). An obscuring layer (7) is located, in use, between the optically variable effect generating structure and a substrate (8) to which the device is secured. A color layer (6) is also included which exhibits one or more predetermined colors when viewed under certain viewing conditions from the side of the device remote from the obscuring layer. The obscuring layer (7) is substantially opaque under the said certain viewing conditions.

Abstract: An optically variable security device comprising a thin film reflection filter structure (23) which exhibits a first optically variable effect; and a relief structure (20) on or in the thin film reflection filter structure which exhibits a second optically variable effect.

Abstract: A holographic security device comprising first and second holographic generating structures (2,3) recorded in respective sets of substantially non-overlapping regions of a record medium is disclosed. The regions of one set are interleaved with regions of the other set, whereby both interleaved line structures are substantially non-visible to the unaided eye, whereby the holographic security device generates two or more holographic images (A,B) viewed from separate viewing directions around the device and normally seen by tilting the device. Each particular holographic image in a viewing direction is generated in whole or part by the holographic structure associated with one set of interleaved lines.

Abstract: A security device comprises a substrate (1) having a viewing region (3) which is provided on one side with first indicia (7) and on the other side with second indicia (9) overlying the first indicia. The substrate carries an obscuring material (10) aligned with the second indicia (9) so as to prevent at least the second indicia from being viewed from the one side of the substrate under reflected radiation. The substrate is sufficiently transparent while the obscuring material permits the passage of sufficient transmitted radiation to allow the second indicia (9) to be viewed from the one side of the substrate under transmission conditions.

Abstract: A holographic effect is generated on a holographic security device by diffraction of light by a surface relief pattern on a film. When illuminated, a moire pattern is generated from a pair of overlapping, regular arrays of lines or dots. Each array has a line of symmetry. The lines of symmetry are aligned. The device exhibits an ordered variation in the form of observed moire patterns in a direction parallel with the alignment direction of the lines of symmetry and a color variation but substantially no form variation transverse to alignment direction.