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).

The present invention provides a novel photopolymer formulation comprising matrix polymers, writing monomer and a photoinitiator and further comprising a compound of formula (1) ##STR00001##
where A.sup.1, A.sup.2 and A.sup.3 are each independently hydrogen, fluorine, chlorine, bromine or iodine, R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are each independently hydrogen, halogen, cyano, nitro, amino, alkylimino, azide, isonitrile, enamino, formyl, acyl, carboxyl, carboxylate, carboxamide, orthoester, sulphonate, phosphate, organosulphonyl, organosulphoxidyl, optionally fluorinated alkoxy or an optionally substituted aromatic, heteroaromatic, aliphatic, araliphatic, olefinic or acetylenic radical while suitable radicals may be connected together via bridge of any desired substitution, or in that two or more compounds of formula (I) may be connected together via at least one of the radicals R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5, in which case these radicals therein constitute a 2- to 4-tuply functional bridge, with the proviso that at least one of the radicals R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 is not hydrogen. Further subjects of the invention are a photopolymer comprising matrix polymers, a writing monomer and photoinitiator, a holographic medium comprising a photopolymer formulation of the present invention or being obtainable by use thereof, the use of a holographic medium of the present invention and also a process for producing a holographic medium by using a photopolymer formulation of the present invention.

The layered generation of at least one volume grating in a recording medium by way of exposure, the recording medium having at least one photosensitive layer which is sensitized for a presettable wavelength of the exposure light. Each volume grating is generated in the recording medium by at least two wave fronts of coherent light capable of generating interference, the wave fronts being superposed in the recording medium at a presettable depth, at a presettable angle and with a presettable interference contrast. The depth and the thickness of the refractive index modulation and/or transparency modulation of a volume grating in the recording medium is controlled by depth-specific control of the spatial and/or temporal degree of coherence of the interfering wave fronts in the direction of light propagation.

A lighting device for vehicles, in particular a signal light, with a light source for emitting a light beam and an optical unit associated with the light source for producing a predetermined light function, the optical unit having a holographic element and a lens arranged in the main emission direction in front of the holographic element, the holographic element comprising such a diffraction structure that the light beam emitted from the light source onto the holographic element is varied according to a predetermined illumination pattern such that the holographic light beam lights an illumination surface of the lens to generate the light function.

A system for controlling access to secured resources using a security token having a hologram embossed thereon is provided. A key is split into a user key and a complimentary key based on a mask, wherein key values in the user key correspond to idle state values in the complimentary key and vice versa. The user key is used to generate a user key array, that is used to generate a three-dimensional virtual image that is holographically embossed onto a security token. The hologram is merged with a corresponding hologram for the complimentary key and the combination compared to an image of an ensemble of the key. The combination can be mergers of images or extractions of holograms. If a match is found, within a tolerance, an access grant signal is sent to the secure resources, thereby securing the resources based on presence of the security token.

A system for controlling access to secured resources using a security token having a hologram embossed thereon is provided. A key is split into a user key and a complimentary key based on a mask, wherein key values in the user key correspond to idle state values in the complimentary key and vice versa. The user key is used to generate a user key array, that is used to generate a three-dimensional virtual image that is holographically embossed onto a security token. The hologram is merged with a corresponding hologram for the complimentary key and the combination compared to an image of an ensemble of the key. The combination can be mergers of images or extractions of holograms. If a match is found, within a tolerance, an access grant signal is sent to the secure resources, thereby securing the resources based on presence of the security token.

Some embodiments are directed to a technique having an off-axis interferometric geometry that is capable of spatially multiplexing at least six complex wavefronts, while using the same number of camera pixels typically needed for a single off-axis hologram encoding a single complex wavefront. Each of the at least six parallel complex wavefronts is encoded into an off-axis hologram with a different fringe orientation, and all complex wavefronts can be fully reconstructed. This technique is especially useful for highly dynamic samples, as it allows the acquisition of at least six complex wavefronts simultaneously, optimizing the amount of information that can be acquired in a single camera exposure. The off-axis multiplexing holographic system of some embodiments provide an off-axis holography modality that is more camera spatial bandwidth efficient than on-axis holography. Moreover, the off-axis interferometric system allows simple simultaneous acquisition of at least six holographic channels, making it attractive for imaging dynamics.

The present invention provides a light-guiding plate which is applicable to incident rays over a wide ray angular range and wide wavelength rage, and is able to suppress a decrease in optical efficiency. A light-guiding plate 200 having a light diffracting portion 1200 for diffracting incident light by a multiple-recorded hologram is configured such that, in the light diffracting portion, when light 1210 of a single wavelength having a certain angular range is incident, at least two or more outgoing rays 1220 are discretely emitted with a first angular space θs, and the emitted rays each have a second angular range θa, and the first angular space θs is equal to or larger than the second angular range θa.

A display device according to embodiments of the present disclosure includes a determination unit to determine a display mode, a light generator to selectively irradiate a 2D light or a hologram 3D light, a spatial light modulator to selectively display a 2D image or a hologram 3D image, and a control unit that controls the light generator to selectively irradiate the 2D light or the hologram 3D light and controls the spatial light modulator to modulate the 2D light or the hologram 3D light irradiated from the light generator to display the 2D image or the hologram 3D image according to the display mode determined by the determination unit.

A display device according to embodiments of the present disclosure includes a determination unit to determine a display mode, a light generator to selectively irradiate a 2D light or a hologram 3D light, a spatial light modulator to selectively display a 2D image or a hologram 3D image, and a control unit that controls the light generator to selectively irradiate the 2D light or the hologram 3D light and controls the spatial light modulator to modulate the 2D light or the hologram 3D light irradiated from the light generator to display the 2D image or the hologram 3D image according to the display mode determined by the determination unit.