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 laminated tamper evident security document (10) is provided which has a transparent or translucent support layer (12), first and second security layers (16, 16?) on opposite sides of the support layer (12), first and second tamper evident layers (14, 14?) between the support layer (12) and the security layers (16, 16?) layers of printed information (22) over the security layers (16, 16?) and polymeric outer layers (18). The security layers (16, 16?) have security regions (26, 26?) which together form a composite security device or image (30) to indicate an authentic security state. Upon exposure to predetermined conditions to delaminate the document at least one of the tamper evident layers (14, 14?) is arranged to destruct or otherwise affect at least one of the security layers (16, 16?) to indicate an unauthentic state.

Abstract: A security document or token in the form of an identity card (10) is provided which incorporates a biometric or photographic image (24) provided in a transparent region or window (18) such that the image is substantially distinguishable from both sides of the card (10). Regions of partial or varying opacity (20, 30) are provided adjacent to or surround the window (18). A portion (27) of the photographic image (24) extends into at least one region of partial or varying opacity (20), and another portion (25) of the image extends into the substantially opaque region (22) surrounding the window (18) and the regions (20, 30). The portion (27) of the image which extends into the region of partial or varying opacity is at least partly visible from both sides of the document in transmission, but only visible from one side of the document in reflection.

Abstract: A method of determining at least one characteristic of one or more security documents such as banknotes, each security document including a sheet-like substrate of plastics material and opacifying layers applied to opposing faces of the substrate, the method comprising the steps of: (a) projecting radiation from a radiation source into the substrate of each security document for propagation therein, the opacifying layers acting to guide the projecting radiation within the substrate; (b) detecting a radiation emission of the substrate of each security document, the radiation emission resulting from the propagated radiation; and (c) analysing one or more characteristics of the radiation emission.