Abstract: A security element includes a first layer having a first surface; an array of image regions across the first surface, each including a first and a second sub-region; a first array of plasmonic nanostructures in or on the first surface across the first sub-regions and defining in each first sub-region a portion of a first image; and a second array of plasmonic nanostructures in or on the first surface across the second sub-regions and defining in each second sub-region a portion of a second image. The first surface is arranged so the sub-regions have respective average inclinations. The average inclinations of the first sub-regions result in the first image being displayed at a first viewing angle. The average inclinations of the second sub-regions result in the second image being displayed at a different second viewing angle. The second image is substantially not displayed or only partially displayed at the first viewing angle.

Abstract: A security element including a first layer having a first surface, an array of image regions across the surface, each including at least first and second sub-regions, a first array of plasmonic nanostructures in or on the surface across the first sub-regions, defining in each a corresponding portion of a first image, a second array across the second sub-regions, defining in each a corresponding portion of a second image; wherein each sub-region has a respective average inclination and the average inclinations of the first sub-regions are such that the first image is displayed at least at a first viewing angle and those of the second sub-regions are such that the second image is displayed at least at a second viewing angle different from the first and the second image is substantially not or only partially displayed at least at the first angle. Also, a method of manufacturing the security element.

Abstract: An optical device that exhibits a variable optical effect upon illumination is provided. The optical device comprises a set of first grating regions, wherein each first grating region comprises a plurality of first grating elements. The first grating elements have one or more first grating pitches such that upon illumination the first grating elements exhibit at least a first order diffractive effect at a first viewing angle and a second order diffractive effect at a second viewing angle. The optical device further comprises a set of second grating regions, wherein each second grating region comprises a plurality of second grating elements, the second grating elements having one or more second grating pitches smaller than the one or more first grating pitches such that upon illumination the second grating elements exhibit a first order diffractive effect substantially at the second viewing angle. The set of first grating regions is interlaced with the set of second grating regions.

Abstract: A method of forming a security device includes: a holographic image layer, diffusion element, and barrier layer. A region of the barrier layer includes a heat-transformable material. The method further includes selectively applying heat at a plurality of positions within the region of the barrier layer, in accordance with a predetermined pattern, so as to modify the heat-transformable material such that the region of the barrier layer is selectively rendered passable to the diffusible substance at each of the plurality of positions, thereby permitting diffusion of the diffusible substance between the regions of the diffusion element and the holographic image layer such that, at a plurality of positions within the region of the holographic image layer and corresponding to the predetermined pattern, the volume hologram is dimensionally modified so as to become viewable in a second observable colour, different from the first observable colour.

Abstract: Systems and methods for measuring changes in mechanical properties, mechanical responses, and or mechanical performances of orthodontic aligners are disclosed. The orthodontic aligners can include a plurality of speckles. The plurality of speckles are adapted for digital image correlation measurements. The methods involve acquiring digital images of the orthodontic aligner and performing digital image correlation on these images. From the digital image correlation, a change in one or more mechanical properties, mechanical responses, and/or mechanical performances in the orthodontic aligner are determined. The systems and methods can provide insight into mechanical properties of physiological structures, which can aid patient diagnosis and treatment.

Abstract: An optical device is provided that exhibits a variable optical effect upon illumination. The optical device has a diffractive structure comprising: a portion of a first kinoform diffractive structure that encodes a first image, arranged to form a first diffractive region (11) of the diffractive structure; and a portion of a second kinoform diffractive structure that encodes a second image, arranged to form a second diffractive region (13) of the diffractive structure; wherein the first diffractive region and the second diffractive region are laterally separate; and each of the first diffractive region and the second diffractive region are discernible by the naked human eye. Methods of manufacture of such optical devices are also disclosed.

Abstract: The present example provides a scalable tooling system using highly parallel convection heating for processing of high temperature composite materials. A single-sided mold is provided with vacuum pressure to cast and consolidate a raw material. The mold is integrally heated by a plurality of discretized heat sources providing a plurality of convection airflow sources to minimize the hot and cold spots inherit to typical convection oven processing. Airflow is arranged by orifices aligned conformally to the mold's profile surface such that rapid heating rates may be achieved while maintaining temperature control along the mold surface.

Abstract: A security element including: a first layer having a first surface; an array of image regions across the surface, each including at least first and second sub-regions; a first array of plasmonic nanostructures in or on the surface across the first sub-regions, defining in each a corresponding portion of a first image; a second array across the second sub-regions, defining in each a corresponding portion of a second image; wherein each sub-region has a respective average inclination and the average inclinations of the first sub-regions are such that the first image is displayed at least at a first viewing angle and those of the second sub-regions are such that the second image is displayed at least at a second viewing angle different from the first and the second image is substantially not or only partially displayed at least at the first angle. Also, a method of manufacturing the security element.

Abstract: A security device includes an array of reflective elements including at least first and second sets of reflective elements, which are regularly or irregularly interlaced along at least a first interlacing direction across a first area of the security device. A non-dispersive colour-generating structure is in the surface of first and/or second sets of reflective elements. The first set of reflective elements is configured to collectively exhibit a first image across the first area of the security device to a viewer within a first viewing zone and direct incident light convergently and/or divergently towards this zone. The second set of reflective elements is configured to collectively exhibit a second image across the first area of the security device to the viewer within a second viewing zone. The structure is modulated across the first and/or second sets of reflective elements such that the first and/or second images include multiple colours.

Abstract: An optical device is provided that exhibits a variable optical effect upon illumination. The optical device has a diffractive structure comprising: a portion of a first kinoform diffractive structure that encodes a first image, arranged to form a first diffractive region (11) of the diffractive structure; and a portion of a second kinoform diffractive structure that encodes a second image, arranged to form a second diffractive region (13) of the diffractive structure; wherein the first diffractive region and the second diffractive region are laterally separate; and each of the first diffractive region and the second diffractive region are discernible by the naked human eye. Methods of manufacture of such optical devices are also disclosed.

Abstract: A security device includes: a substrate having a reflective surface; and a printed array of elements on a substantially flat area of the substrate. Each element is formed of a first material which is at least semi-transparent and a second material, the materials having different optical characteristics. Each element has a raised surface profile relative to the substrate including at least first and second sides sloping from the top of the element to at least respective edges of the element, at which the sides meet a substantially flat base surface of the element parallel to the substrate. The sides have different orientations and each lie at an acute angle to the substrate normal. Under illumination away from the substrate normal, when viewed from first and second viewing angles the element appears to have respectively substantially the optical characteristics of the first and second materials.

Abstract: An optical device includes: first grating regions each having a plurality of first grating elements each having a principal component of orientation substantially orthogonal to a first direction; and second grating regions each including a plurality of second grating elements each having a principal component of orientation substantially orthogonal to a second direction. At least a subset of the first grating regions each exhibit a diffractive colour such that a user viewing at a first viewing angle perceives a first diffractive colour image. At least a subset of the second grating regions are achromatic, each including a plurality of grating sub-regions having different respective grating element pitches and arranged such that, for a plurality of second viewing angles, the diffractive colours exhibited by the sub-regions cooperate such that the achromatic grating region is perceived to exhibit diffractive whiteness. The sets of first and second grating regions are interlaced.

Abstract: A security element including a first layer having a first surface, an array of image regions across the surface, each including at least first and second sub-regions, a first array of plasmonic nanostructures in or on the surface across the first sub-regions, defining in each a corresponding portion of a first image, a second array across the second sub-regions, defining in each a corresponding portion of a second image; wherein each sub-region has a respective average inclination and the average inclinations of the first sub-regions are such that the first image is displayed at least at a first viewing angle and those of the second sub-regions are such that the second image is displayed at least at a second viewing angle different from the first and the second image is substantially not or only partially displayed at least at the first angle. Also, a method of manufacturing the security element.

Abstract: A security element including: a first layer having a first surface; an array of image regions across the surface, each region including at least first and second sub-regions; a first diffractive optically variable effect generating structure in or on the surface across the first sub-regions; and a second diffractive optically variable effect generating structure in or on the surface across the second sub-regions; wherein the surface is arranged so each first sub-region has a first average inclination and each second sub-region has a second average inclination different from the first, wherein the first structure and inclination provide that the first effect is exhibited across the first sub-regions at least at a first viewing angle and the second structure and inclination provide that the second effect is exhibited across the second sub-regions at least at a second viewing angle different from the first. Also, a method of manufacturing the security element.

Abstract: Systems and methods for measuring changes in mechanical properties, mechanical responses, and or mechanical performances of orthodontic aligners are disclosed. The orthodontic aligners can include a plurality of speckles. The plurality of speckles are adapted for digital image correlation measurements. The methods involve acquiring digital images of the orthodontic aligner and performing digital image correlation on these images. From the digital image correlation, a change in one or more mechanical properties, mechanical responses, and/or mechanical performances in the orthodontic aligner are determined. The systems and methods can provide insight into mechanical properties of physiological structures, which can aid patient diagnosis and treatment.

Abstract: A method for forming an optical device and an optical device, wherein upon illumination, exhibits diffractive images dependent upon viewing angle, the device having a diffractive structure including grating regions, each region corresponding to a component of a respective diffractive image, wherein: each region of the diffractive structure includes grating elements along a first direction having a principal orientation component within the device plane that is substantially orthogonal to the first direction; wherein, the grating elements within each grating region have a constant pitch and the same orientation wherein each grating region, upon illumination, exhibits a diffractive color wherein the corresponding diffractive image is exhibited; wherein, the diffractive structure includes first and second grating regions elongated along a common first direction, the regions being adjacent along the first direction, and wherein the pitch and/or orientation of the grating elements of the first and second grating r

Abstract: A security device includes a diffractive structure, including grating elements and having a first area, the grating elements within a region have a constant pitch or spacing; the first area regions pitches or spacings increase from one region to the next between a first region having a grating element pitch or spacing of less than or equal to 0.6 microns and an end region having a grating element pitch or spacing of greater than or equal to 5 microns; upon illumination and viewing along a first viewing direction substantially orthogonal to the first axis, the device exhibits a first optical effect in that at least one region exhibits a diffractive colour; each region has at least first and second sub-regions having different grating element orientations within the plane of the device such that the first optical effect is exhibited at more than one angle of tilt about the second axis.

Abstract: A method of forming a security device includes: a holographic image layer, diffusion element, and barrier layer. A region of the barrier layer includes a heat-transformable material. The method further includes selectively applying heat at a plurality of positions within the region of the barrier layer, in accordance with a predetermined pattern, so as to modify the heat-transformable material such that the region of the barrier layer is selectively rendered passable to the diffusible substance at each of the plurality of positions, thereby permitting diffusion of the diffusible substance between the regions of the diffusion element and the holographic image layer such that, at a plurality of positions within the region of the holographic image layer and corresponding to the predetermined pattern, the volume hologram is dimensionally modified so as to become viewable in a second observable colour, different from the first observable colour.

Abstract: device includes an array of reflective sampling elements. A non-dispersive colour-generating relief structure is formed in a surface of the reflective sampling elements. The non-dispersive colour-generating relief structure defines an array of image elements across the array of reflective sampling elements. The array of image elements defined by the non-dispersive colour-generating relief structure and the array of reflective sampling elements cooperate to exhibit an optically variable effect.

Abstract: A security device includes an array of reflective elements including at least first and second sets of reflective elements, which are regularly or irregularly interlaced along at least a first interlacing direction across a first area of the security device. A non-dispersive colour-generating structure is in the surface of first and/or second sets of reflective elements. The first set of reflective elements is configured to collectively exhibit a first image across the first area of the security device to a viewer within a first viewing zone and direct incident light convergently and/or divergently towards this zone. The second set of reflective elements is configured to collectively exhibit a second image across the first area of the security device to the viewer within a second viewing zone. The structure is modulated across the first and/or second sets of reflective elements such that the first and/or second images include multiple colours.