A system for measuring vibrations of a surface (VSURF) of a mechanical part (M), comprising a source (SOURCE) of radiation (L), a first separator element (ELI) configured to define a first incident ray (LB1) and a reference ray (RLB), a shaping module (DOEM) producing a second incident ray (LB2) from said first incident ray (LB1), and an optical element (OE) capable of an interferential addition of the reference ray (RLB) and a ray produced by a reflection of said second incident ray (LB2) on said surface (VSURF), the shaping module (DOEM) comprising one or more diffracting optical elements (DOE1, . . . , DOEn), each comprising at least one diffraction structure (FSTRUCT) diffracting all or part of the first incident ray (LB1) so as to illuminate a chosen surface of the mechanical part.

A security document having a security element including a multilayer body with a volume hologram layer and a partial opaque layer, arranged on a surface of the volume hologram layer, which is present in a first area and is not present in a second area.

A method for producing holograms with a multiplicity of holographic prescriptions from a single master is provided. A multiplicity of holographic substrates each containing a first hologram is stacked on a second holographic recording medium substrate. The first hologram is designed to diffract light from a first direction into a second direction. When expose to illumination from the first direction zero order and diffracted light from each first hologram interfere in the second holographic recording medium substrate forming a second hologram. The second hologram is then copied into a third holographic recording medium substrate to provide the final copy hologram.

Various examples of out-of-plane multicolor waveguide holography systems, methods of manufacture, and methods of use are described herein. In some examples, a multicolor waveguide holography system includes a planar waveguide to convey optical radiation between a grating coupler and a metasurface hologram. The grating coupler may be configured to couple out-of-plane optical radiation of three different color incident at three different angles into the planar waveguide. The combined multicolor optical radiation may be conveyed by the waveguide to the metasurface hologram. The metasurface hologram may diffractively decouple the three colors of optical radiation for off-plane propagation to form a multicolor holographic image in free space.

An optical master is created by using a nanoimprint alignment layer to pattern a liquid crystal layer. The nanoimprint alignment layer and the liquid crystal layer constitute the optical master. The optical master is positioned above a photo-alignment layer. The optical master is illuminated and light propagating through the nanoimprinted alignment layer and the liquid crystal layer is diffracted and subsequently strikes the photo-alignment layer. The incident diffracted light causes the pattern in the liquid crystal layer to be transferred to the photo-alignment layer. A second liquid crystal layer is deposited onto the patterned photo-alignment layer, which subsequently is used to align the molecules of the second liquid crystal layer. The second liquid crystal layer in the patterned photo-alignment layer may be utilized as a replica optical master or as a diffractive optical element for directing light in optical devices such as augmented reality display devices.

A method for producing holograms with a multiplicity of holographic prescriptions from a single master is provided. A multiplicity of holographic substrates each containing a first hologram is stacked on a second holographic recording medium substrate. The first hologram is designed to diffract light from a first direction into a second direction. When expose to illumination from the first direction zero order and diffracted light from each first hologram interfere in the second holographic recording medium substrate forming a second hologram. The second hologram is then copied into a third holographic recording medium substrate to provide the final copy hologram.

There is provided a holographic optical element including: a hologram portion including a plurality of groups of unit regions, each group of unit regions of the hologram portion being configured to produce a respective holographic image under a respective light illumination having a respective predetermined wavelength; and a colour filter portion formed on the hologram portion, the colour filter portion including a plurality of groups of unit regions, each group of unit regions of the colour filter portion being arranged on a corresponding group of the plurality of groups of unit regions of the hologram portion, whereby the plurality of groups of unit regions of the colour filter portion is spatially arranged to form a predetermined colour image. There is also provided a method of forming the holographic optical element. There is further provided an article having optical security incorporated therein.

Optical elements with anisotropic, patterned surface relief microstructures in which information is encoded in the distribution of the orientation of different zones. From the analysis of the distribution of the light scattered from the element, the orientation distribution in the element and therefore the encoded information can be evaluated. The elements are particularly useful for securing documents and articles against counterfeiting and falsification.

Provided is a hologram recording medium that can achieve suppression of deterioration of the storage stability in an unexposed state. The hologram recording medium includes a base material and a photosensitive layer. The oxygen permeability of the base material measured in an environment at 23? C. and 0% RH is more than 0.1 cm.sup.3.Math.(m.sup.2.Math.day.Math.atm).sup.?1 and 10000 cm.sup.3.Math.(m.sup.2.Math.day.Math.atm).sup.?1 or less. The photosensitive layer contains a polymerizable compound, and the polymerizable compound contains a compound represented by a specific general formula.

An authentication medium includes a sheet-like laminate sheet; a first region that is formed on the laminate sheet and where personal identification information is recorded; and a second region that is formed on the laminate sheet and has a hologram structure where check data associated with first individual information is recorded.