Multilayered security devices comprising a patterned substrate over which a graphene-based coating has been applied.

The present invention relates to the use of nanosystems as non deactivable security markers comprising metal atomic quantum clusters (AQCs) of at least two different size distributions encapsulated in a cavity with an inner diameter less than or equal to approximately 10 nm. These nanosystems are luminescence, particularly fluorescence after external excitation. The invention also relates to security documents, articles or elements incorporating these markers as well as to a method and a system for detecting the same.

The present invention relates to the use of nanosystems as non deactivable security markers comprising metal atomic quantum clusters (AQCs) of at least two different size distributions encapsulated in a cavity with an inner diameter less than or equal to approximately 10 nm. These nanosystems are luminescence, particularly fluorescence after external excitation. The invention also relates to security documents, articles or elements incorporating these markers as well as to a method and a system for detecting the same.

The invention relates to a multi-layer body (1) comprising a first layer (13) having a multiplicity of first zones (21), which are respectively separated from one another by one or a plurality of transparent second zones (22). The multi-layer body has a second layer (14) composed of a transparent material, said second layer being arranged below the first layer (13), and a reflection layer (15) arranged below the second layer (14). The second layer (14) has a multiplicity of third zones (23), in each of which a microstructure (17) is impressed into the interface—facing away from the first layer—between the second layer (14) and the reflection layer, which is covered with the reflection layer (15). Each of the microstructures (17) is configured such that it reflects back and/or diffracts back light incident perpendicularly with respect to the plane spanned by the first layer from the direction of the first layer in the region of the respective third zone (23) onto a region of the first layer whose area is smaller than the area of the respective third zone (23) by at least a factor of 10. The microstructures (17) are arranged in accordance with a microstructure grid having a distance between adjacent microstructures in a second spatial direction of less than 300 μm.

The invention relates to a multi-layer body (1) comprising a first layer (13) having a multiplicity of first zones (21), which are respectively separated from one another by one or a plurality of transparent second zones (22). The multi-layer body has a second layer (14) composed of a transparent material, said second layer being arranged below the first layer (13), and a reflection layer (15) arranged below the second layer (14). The second layer (14) has a multiplicity of third zones (23), in each of which a microstructure (17) is impressed into the interface—facing away from the first layer—between the second layer (14) and the reflection layer, which is covered with the reflection layer (15). Each of the microstructures (17) is configured such that it reflects back and/or diffracts back light incident perpendicularly with respect to the plane spanned by the first layer from the direction of the first layer in the region of the respective third zone (23) onto a region of the first layer whose area is smaller than the area of the respective third zone (23) by at least a factor of 10. The microstructures (17) are arranged in accordance with a microstructure grid having a distance between adjacent microstructures in a second spatial direction of less than 300 μm.

An optical device includes an array of lenses and a plurality of first and second segments disposed under the array of lenses. At a first viewing angle, the array of lenses presents a first image for viewing without presenting the second image for viewing, and at a second viewing angle different from the first viewing angle, the array of lenses presents for viewing the second image without presenting the first image for viewing. In some examples, individual ones of the first and second segments can comprise specular reflecting, transparent, diffusely reflecting, and/or diffusely transmissive features. In some examples, individual ones of the first and second segments can comprise transparent and non-transparent regions. Some examples can incorporate more than one region producing an optical effect.

An optical device includes an array of lenses and a plurality of first and second segments disposed under the array of lenses. At a first viewing angle, the array of lenses presents a first image for viewing without presenting the second image for viewing, and at a second viewing angle different from the first viewing angle, the array of lenses presents for viewing the second image without presenting the first image for viewing. In some examples, individual ones of the first and second segments can comprise specular reflecting, transparent, diffusely reflecting, and/or diffusely transmissive features. In some examples, individual ones of the first and second segments can comprise transparent and non-transparent regions. Some examples can incorporate more than one region producing an optical effect.

Examples described herein relate to a system consistent with the disclosure. For instance, the system may comprise a printing device including hardware to form an image on a print medium, a memory resource, and a controller to receive a print job to form the markings on the print medium, designate a pixel of the received print job to form a covert dot pattern on the markings, where the pixel corresponds to a first laser intensity level; and adjust a laser intensity of the printing device to a second laser intensity level based on the first laser intensity level of the designated pixel to form the covert dot pattern.

An optical security element made of a refractive transparent or partially transparent optical material and comprising an optical assembly of a caustic layer having a light-redirecting surface with a relief pattern of given depth and a focal length f.sub.C and an adjacent lens element of focal length f.sub.L configured to redirect incident light received from a point-like light source through it and to form a projected image containing a caustic pattern directly on a retina of an observer. A marked object, as well as a method of visually authenticating an object, and use of optical security elements for authenticating or securing against counterfeiting are also disclosed.

An optical security element made of a refractive transparent or partially transparent optical material and comprising an optical assembly of a caustic layer having a light-redirecting surface with a relief pattern of given depth and a focal length f.sub.C and an adjacent lens element of focal length f.sub.L configured to redirect incident light received from a point-like light source through it and to form a projected image containing a caustic pattern directly on a retina of an observer. A marked object, as well as a method of visually authenticating an object, and use of optical security elements for authenticating or securing against counterfeiting are also disclosed.