A method of manufacturing a security device including: conveying a substrate web including a photosensitive film along a transport path; exposing the photosensitive film to radiation of a predetermined wavelength through a mask, wherein the mask includes a predetermined pattern of regions which are substantially opaque to radiation of the predetermined wavelength and at least semi-transparent to radiation of the predetermined wavelength, respectively; during the exposure, moving the mask alongside the substrate web along at least a portion of the transport path at substantially the same speed as the substrate web, such that there is substantially no relative movement between the mask and the substrate web; and heating the substrate web including the exposed photosensitive film. In this way, regions of the photosensitive film exposed to the radiation of the predetermined wavelength undergo an increase in optical density such that the photosensitive film displays a reproduction of the predetermined pattern.

A method of manufacturing a security device including: conveying a substrate web including a photosensitive film along a transport path; exposing the photosensitive film to radiation of a predetermined wavelength through a mask, wherein the mask includes a predetermined pattern of regions which are substantially opaque to radiation of the predetermined wavelength and at least semi-transparent to radiation of the predetermined wavelength, respectively; during the exposure, moving the mask alongside the substrate web along at least a portion of the transport path at substantially the same speed as the substrate web, such that there is substantially no relative movement between the mask and the substrate web; and heating the substrate web including the exposed photosensitive film. In this way, regions of the photosensitive film exposed to the radiation of the predetermined wavelength undergo an increase in optical density such that the photosensitive film displays a reproduction of the predetermined pattern.

A method and security device, including: a semi-transparent layer exhibiting a first pattern of regions having high optical density and/or raised surface profile relative to layer intervening regions; and a color layer exhibiting a second pattern of elements of at least one color. First and second patterns partially overlap and are configured so the device, appearance varies at different viewing angles. First pattern has color layer following the contours of raised regions. Security device includes: a photosensitive film exhibiting pattern of regions of relatively high and low optical density, the pattern arising from photosensitive film exposure to radiation of a responsive predetermined wavelength from the photosensitive film; and a color layer overlapping the pattern exhibited by photosensitive film, which exhibits increase in optical density upon radiation exposure of a predetermined wavelength and concurrent or subsequent heating. Increases in optical density being due to the bubbles formation within the photosensitive film.

A method and security device, including: a semi-transparent layer exhibiting a first pattern of regions having high optical density and/or raised surface profile relative to layer intervening regions; and a color layer exhibiting a second pattern of elements of at least one color. First and second patterns partially overlap and are configured so the device, appearance varies at different viewing angles. First pattern has color layer following the contours of raised regions. Security device includes: a photosensitive film exhibiting pattern of regions of relatively high and low optical density, the pattern arising from photosensitive film exposure to radiation of a responsive predetermined wavelength from the photosensitive film; and a color layer overlapping the pattern exhibited by photosensitive film, which exhibits increase in optical density upon radiation exposure of a predetermined wavelength and concurrent or subsequent heating. Increases in optical density being due to the bubbles formation within the photosensitive film.