Abstract: Holographic storage system with multiple reference beams The present invention relates to a coaxial type apparatus for reading from and/or writing to holographic storage media with multiple reference beams. The invention further relates to a beam generator and a filter for use in such an apparatus. According to the invention, in an apparatus for reading from and/or writing to a holographic storage medium, with a coaxial arrangement of three or more focused reference beams and an object beam or a reconstructed object beam, the foci of the focused reference beams are arranged on a circle around the object beam in a Fourier plane of the apparatus. A beam generator generates the three or more reference beams from an incoming reference beam. A filter low-pass filters the object beam and rotates the polarization of the three or more reference beams.

Abstract: The invention describes a collinear optical head for a reflection-type holographic recording medium, which is capable of obtaining an increased capacity. The optical head presented here allows for high capacity by combining holographic multiplexing methods, based on a shift and/or phase-coded reference beam, and/or scanned reference beam and/or angle and/or confocal addressing techniques. The parallel reading method and the format of the holographic recording medium ensure high-speed data transfer. Combined multiplexing is implemented in the system by means of a confocal optical arrangement that reduces crosstalk between adjacent holograms by filtering out object beams unintentionally reconstructed from non-addressed holograms.

Abstract: The invention relates to a method for the recording and reading of data with a holographic write/read apparatus onto a holographic recording medium with a thin holographic recording layer. The medium is preferably an optical card (2). The recording of the information is in the form of data pages stored as thin Fourier holograms (61). According to the invention, it is foreseen to use reflected transmission and polarisation holography with different write and read wavelengths, and to correct during reading the distortion in the readout channel caused by the difference between the write and read wavelengths. The invention further relates to an apparatus and system for performing the method. There is also disclosed a method of coding the recorded information.

Abstract: The present invention relates to a holographic storage system, and more specifically to a holographic storage system using a phase spatial light modulator. According to the invention a holographic storage system with a phase SLM for imprinting a 2-dimensional phase data pattern onto an object beam includes a common path interferometer for converting the phase data pattern of the object beam into an intensity data pattern.

Abstract: The object of the invention is a high data density holographic data storage method. The holograms are written into the volumetric data storage layer or layers, and during the writing process the accurate places of holograms in the data carrier structure are determined by the intersection domain of the object and reference beam or beams, and during the reading process the selection of holograms simultaneously illuminated by the reference beam or beams, the read-out of the addressed hologram, and the suppressing of un-addressed holograms are carried out by a spatial filter located confocally with the addressed hologram and/or by satisfying the Bragg condition. The optical arrangement for recording and reading out holograms has three dedicated planes in confocal arrangements, where the addressed hologram is in the middle dedicated plane in the storage material, and in the two outer dedicated planes there are spatial filters. The optical arrangement is a 12f optical System consisting of three pairs of objectives.

Abstract: A head mounted display is disclosed that utilizes a single video display screen to transport images to both eyes. Multiple reflections are created by illuminating the display screen form a plurality of directions, or by illuminating the display screen with light beams of differing polarizations. The reflections of the display screen are focused in order to reduce the splitting volume and then redirected by a plurality of reflective surfaces located near the focal point of the display images. Different images may be sent to each eye of a user by interlacing multiple data streams for the display and linking each data stream with a specific illumination direction, or specific polarization.

Abstract: A mechanism for adjusting an apparatus for the inter-pupilar distance of a user is disclosed. Example embodiments of the disclosed mechanism use gears that link the movements of eye-optics and reflectors placed along the optical path. When the eye-optics are adjusted, this movement causes a movement in the linked reflectors that maintains a constant length for the optical path.

Abstract: A head mounted display is disclosed that utilizes a single video display screen to transport images to both eyes. Multiple reflections are created by illuminating the display screen form a plurality of directions, or by illuminating the display screen with light beams of differing polarizations. The reflections of the display screen are focused in order to reduce the splitting volume and then redirected by a plurality of reflective surfaces located near the focal point of the display images. Different images may be sent to each eye of a user by interlacing multiple data streams for the display and linking each data stream with a specific illumination direction, or specific polarization.

Abstract: A head mounted display is disclosed that utilizes a single video display screen to transport images to both eyes. The image of this display screen is focused in order to reduce the splitting volume and then split by a plurality of reflective surfaces located near the focal point of the image.

Abstract: There is disclosed a method and apparatus for coding data, for the purpose of preventing unauthorised readout of information. In the method, user information is converted into digital data (UD), and the digital data is recorded in a first data set (CD) and a second data set (HD), where the first data set (CD) is recorded in a first optical storage medium of a data carrier, and the second data set (HD), is recorded in a second, holographic storage medium of the data carrier. According to the method, the digital data (UD) is divided between the first and second data sets (CD,HD) in a manner so that a part of the user information is contained only in the first data set (CD), and another part of the user information is contained only in the second data set (HD), and the relative proportion of the user information in the data sets is selected so that the information contained in any one of the data sets is insufficient by itself to restore the complete user information (UD) contained in both data sets.

Abstract: There is disclosed a method for the holographic recording of data, wherein a hologram containing the date is recorded in a waveguide layer (3). The holograms are formed in a layer structure containing multiple waveguide layers (3). Coupling means (12) are provided for selectively coupling the reference beam (11) into the single waveguide layers (3) of the layer structure. The invention also relates to an arrangement for holographic recording of data, comprising a data storage medium with a waveguide holographic storage layer, and an optical system for writing and reading the holograms. The optical system comprises means for imaging an object beam (5) and a reference beam (11) on the storage medium. The arrangement comprises multiple waveguide holographic storage layers (3) in the storage medium, and means for selectively coupling the reference beam (11) into the single waveguide layers (3) of the layer structure.

Abstract: A head mounted display is disclosed that utilizes a single video display screen to transport images to both eyes. Multiple reflections are created by illuminating the display screen form a plurality of directions, or by illuminating the display screen with light beams of differing polarizations. The reflections of the display screen are focused in order to reduce the splitting volume and then redirected by a plurality of reflective surfaces located near the focal point of the display images. Different images may be sent to each eye of a user by interlacing multiple data streams for the display and linking each data stream with a specific illumination direction, or specific polarization.

Abstract: A head mounted display is disclosed that utilizes a single video display screen to transport images to both eyes. The image of this display screen is focused in order to reduce the splitting volume and then split by a plurality of reflective surfaces located near the focal point of the image.

Abstract: There is disclosed a method for the holographic recording of data, wherein a hologram containing the date is recorded in a waveguide layer (3). The holograms are formed in a layer structure containing multiple waveguide layers (3). Coupling means (12) are provided for selectively coupling the reference beam (11) into the single waveguide layers (3) of the layer structure. The invention also relates to an arrangement for holographic recording of data, comprising a data storage medium with a waveguide holographic storage layer, and an optical system for writing and reading the holograms. The optical system comprises means for imaging an object beam (5) and a reference beam (11) on the storage medium. The arrangement comprises multiple waveguide holographic storage layers (3) in the storage medium, and means for selectively coupling the reference beam (11) into the single waveguide layers (3) of the layer structure.