Abstract: A microelectronic device comprises a stack structure comprising a stack structure comprising a vertically alternating sequence of conductive structures and insulative structures arranged in tiers, the stack structure divided into block structures separated from one another by slot structures, strings of memory cells vertically extending through the block structures of the stack structure, the strings of memory cells individually comprising a channel material vertically extending through the stack structure, an additional stack structure vertically overlying the stack structure and comprising a vertical sequence of additional conductive structures and additional insulative structures arranged in additional tiers, first pillars extending through the additional stack structure and vertically overlying the strings of memory cells, each of the first pillars horizontally offset from a center of a corresponding string of memory cells, second pillars extending through the additional stack structure and vertically ove

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: 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 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 security element including: a first layer having a first surface; an array of image regions across the first surface arranged along at least a second direction, each region including at least a first image sub-region having an average inclination defining an angle, relative to a plane of the security element, about an image region axis extending along a first direction; a diffractive optically variable effect generating structure provided in or on the first surface across the first image sub-regions, the structure including diffractive elements that extend along a direction within 45° of the first direction, wherein the structure is provided across the first image sub-regions and spatially arranged and/or modulated across the first image sub-regions in accordance with a first image so the first image is displayed by the first image sub-regions in combination at least at a first viewing angle. Also, a method of manufacturing the security element.

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 security element including: a first layer having a first surface; an array of image regions across the first surface arranged along at least a second direction, each region including at least a first image sub-region having an average inclination defining an angle, relative to a plane of the security element, about an image region axis extending along a first direction; a diffractive optically variable effect generating structure provided in or on the first surface across the first image sub-regions, the structure including diffractive elements that extend along a direction within 45° of the first direction, wherein the structure is provided across the first image sub-regions and spatially arranged and/or modulated across the first image sub-regions in accordance with a first image so the first image is displayed by the first image sub-regions in combination at least at a first viewing angle. Also, a method of manufacturing the security element.

Abstract: A method of embroidery on a fabric and an embroidery tool enable the production in a simple manner of decorative effect on knitted or other garments. The tool has a tubular needle portion with a handle at one end and a closed curved point at the other. The handle has an entry aperture for continuous work material such as yarn, which passes from the entry aperture through a smooth duct in the tool to an exit aperture formed on the convex surfaces of the curved end adjacent the point. The method of embroidery using the tool comprises the initial steps of passing the point, carrying a loop of yarn, through the fabric from the front to the rear and back again at a different location, the handle remaining at the front, and the repeated steps of retaining the loop of yarn at the front while withdrawing the point from the fabric, and then passing the point, carrying a fresh loop of yarn, through the previous loop, and then through the fabric as before.