Systems and method for eye tracking are provided. In some embodiments, the eye tracking system includes a light source configured to generate light and project the light toward an object in a field of view, a detector configured to receive reflected portions of the light from the field of view in order to image the object, and a combiner including a volume grating configured to direct light reflected from different points in a field of view to the light detector. The volume grating includes a plurality of portions along a first area and each of the portions comprising a unique k-vector that is dependent on a respective portion of the field of view.

A method for producing a hologram (1), (1) for security elements (1a) and/or security documents (1b). One or more virtual hologram planes (10) are arranged in front of and/or behind one or more virtual models (20) and/or one or more virtual hologram planes (10) are arranged such that they intersect one or more virtual models (20). One or more virtual light sources (30) are arranged on one or more partial regions of the surface (21) of one or more of the virtual models (20). One or more virtual electromagnetic fields (40) are calculated starting from at least one of the virtual light sources (30) in one or more zones (11) of the one or more virtual hologram planes (10). In the one or more zones (11), in each case, a virtual total electromagnetic field (41) is calculated on the basis of the sum of two or more, of the virtual electromagnetic fields (40) in the respective zone (11). One or more phase images (50) are calculated from the virtual total electromagnetic fields (41) in the one or more zones (11). A height profile (60) of the hologram (1) is calculated from the one or more phase images (50) and the height profile (60) of the hologram (1) is incorporated into a substrate (2) to provide the hologram (1).

A display article (10) includes a plurality of display areas (12, and 13a to 13c). Display areas adjacent to each other differ in at least one of an average hue, an average brightness and an average chroma and a first object to be displayed (21) is formed by a combination of the plurality of display areas (12, and 13a to 13c). At least one of the display areas (12, 13a to 13c) includes a Fourier transform hologram (20R, 20Y) configured to convert incident ray from a point light source or a laser light source into a second object to be displayed.

To provide a photosensitive composition for hologram recording that enables further improvement in diffraction characteristic. A photosensitive composition for hologram recording that includes at least two kinds of photopolymerizable monomers, a photopolymerization initiator, a binder resin, and a polymerization inhibitor. The at least two kinds of photopolymerizable monomers are a monofunctional monomer and a polyfunctional monomer.

The invention relates to a photopolymer formulation comprising a polyol component, a polyisocyanate component, a writing monomer, and a photoinitiator, containing a coinitiator and a dye having the formula F An, where F stands for a cationic dye and An″ stands for an anion, wherein the dye having the formula F An comprises a water absorption of =5%. The invention further relates to a holographic medium, in particular in the form of a film, containing a photopolymer formulation according to the invention, to the use of such a medium for recording holograms, and to a special dye that can be used in the photopolymer formulation according to the invention.

A method of manufacturing a holographic pattern-expressing organogel, by using a dithering mask, according to an aspect of the present disclosure includes: preparing a dithering mask including white pixels and black pixels arranged in periodic patterns; photocuring a polymer by passing an ultraviolet ray through the dithering mask; passing a first solvent through the cured polymer; and passing a second solvent through the cured polymer through which the first solvent is passed.

A photopolymerizable composition including: a polymer matrix or a precursor thereof containing a reaction product of an acrylate-based polyol and a compound containing at least one isocyanate group; a photoreactive monomer; and a non-reactive fluoro compound and a photoinitiator; a hologram recording medium produced from the composition; an optical element including the hologram recording medium; and a method of recording a hologram using the photopolymerizable composition.

The present invention discloses a method that combines two different hologram origination processes in a single photoresist layer by using an interlayer to transfer structures exposed by electron beam lithography into overlapped with dot-matrix hologram areas, and fabricated holographic structures are replicated in multilayer polymer films. Dot-matrix technique is low cost process, which has high origination speed and can be used for the patterning of large areas of holograms with high diffraction efficiency. Electron beam lithography allows the formation of high resolution structures. The proposed manufacturing method allows combining these two technologies so that the final security device could contain electron beam patterned high resolution diffraction gratings, computer generated holograms, as well as dot-matrix laser patterned large hologram areas with high diffraction efficiency, providing an increased level of protection.

A method for producing a hologram (1), (1) for security elements (1a) and/or security documents (1b). One or more virtual hologram planes (10) are arranged in front of and/or behind one or more virtual models (20) and/or one or more virtual hologram planes (10) are arranged such that they intersect one or more virtual models (20). One or more virtual light sources (30) are arranged on one or more partial regions of the surface (21) of one or more of the virtual models (20). One or more virtual electromagnetic fields (40) are calculated starting from at least one of the virtual light sources (30) in one or more zones (11) of the one or more virtual hologram planes (10). In the one or more zones (11), in each case, a virtual total electromagnetic field (41) is calculated on the basis of the sum of two or more, of the virtual electromagnetic fields (40) in the respective zone (11). One or more phase images (50) are calculated from the virtual total electromagnetic fields (41) in the one or more zones (11). A height profile (60) of the hologram (1) is calculated from the one or more phase images (50) and the height profile (60) of the hologram (1) is incorporated into a substrate (2) to provide the hologram (1).

A photopolymerizable composition including: a polymer matrix or a precursor thereof containing a reaction product of an acrylate-based polyol and a compound containing at least one isocyanate group; a photoreactive monomer; and a non-reactive fluoro compound and a photoinitiator; a hologram recording medium produced from the composition; an optical element including the hologram recording medium; and a method of recording a hologram using the photopolymerizable composition.