999results about "Holographic object characteristics" patented technology

The invention relates to holographic head-up displays, to holographic optical sights, and also to 3D holographic image displays. We describe a holographic head-up display and a holographic optical sight, for displaying, in an eye box of the display/sight, a virtual image comprising one or more substantially two-dimensional images, the head-up display comprising: a laser light source; a spatial light modulator (SLM) to display a hologram of the two-dimensional images; illumination optics in an optical path between said laser light source and said SLM to illuminate said SLM; and imaging optics to image a plane of said SLM comprising said hologram into an SLM image plane in said eye box such that the lens of the eye of an observer of said head-up display performs a space-frequency transform of said hologram on said SLM to generate an image within said observer's eye corresponding to the two-dimensional images.

A method of computing a hologram by determining the wavefronts at the approximate observer eye position that would be generated by a real version of an object to be reconstructed. In normal computer generated holograms, one determines the wavefronts needed to reconstruct an object; this is not done directly in the present invention. Instead, one determines the wavefronts at an observer window that would be generated by a real object located at the same position of the reconstructed object. One can then back-transforms these wavefronts to the hologram to determine how the hologram needs to be encoded to generate these wavefronts. A suitably encoded hologram can then generate a reconstruction of the three-dimensional scene that can be observed by placing one's eyes at the plane of the observer window and looking through the observer window.

A device for holographic reconstruction of three-dimensional scenes includes optical focusing means which directs sufficiently coherent light from light means to the eyes of at least one observer via a spatial light modulator that is encoded with holographic information. The device has a plurality of illumination units for illuminating the surface of the spatial light modulator (SLM); each unit comprises a focusing element (21/22/23 or 24), and a light means (LS₁/LS₂/LS₃ or LS₄) that emits sufficiently coherent light such that each of these illumination units illuminates one separate illuminated region (R1/R2/R3 or R4) of the surface, whereby the focusing element and the light means are arranged such that the light emitted by the light means (LS₁-LS₄) coincides close to or at the observer eyes.

A multi-view distribution format is described for stereoscopic and autostereoscopic 3D displays. In general, it comprises multi-tile image compression with the inclusion of one or more depth maps. More specifically, it provides embodiments that utilize stereoscopic images with one or more depth maps typically in the form of a compressed grey scale image and, in some instances, incorporates depth information from a second view encoded differentially.

Holographic and diffractive security devices and documents carrying security devices as well as system, apparatus, and method for making and using security devices. Security devices provide at least one type of security feature in form of secret, hidden, or covert security feature, not visible to a normal unaided human eye. Covert security features may be any graphic or symbolic representation. One or multiple security features may be provided on any single security device in any combination. Covert feature is revealed either when a decoder device is used with the security device, or when the security device is oriented and viewed in predetermined manner. Embodiments may provide a second overt or non-covert security device in the form of a diffractive or holographic image or graphic that is visible to the unaided eye without use of any decoder or special viewing conditions.

The data defining an object to be holographically reconstructed is first arranged into a number of virtual section layers, each layer defining a two-dimensional object data sets, such that a video hologram data set can be calculated from some or all of these two-dimensional object data sets. The first step is to transform each two-dimensional object data set to a two-dimensional wave field distribution. This wave field distribution is calculated for a virtual observer window in a reference layer at a finite distance from the video hologram layer. Next, the calculated two-dimensional wave field distributions for the virtual observer window, for all two-dimensional object data sets of section layers, are added to define an aggregated observer window data set. Then, the aggregated observer window data set is transformed from the reference layer to the video hologram layer, to generate the video hologram data set for the computer-generated video hologram.

A holographic display comprising light sources (L51, L52, . . . ) in a 2D light source array, lenses (L1, L2, . . . ) in a 2D lens array, a spatial light modulator (SLM) and a beamsplitter, in which there are m light sources per lens, and the light sources are in m-to-one correspondence with the lenses. The beamsplitter splits the rays leaving the SLM into two bundles, one of which illuminates the virtual observer windows for m left eyes (VOWL) and the other illuminates the virtual observer windows for m right eyes (VOWR). In one example, m=1. An advantage is 2D-encoding with vertical and horizontal focusing and vertical and horizontal motion parallax.

A method and apparatus for labeling an item using diffraction grating-based encoded optical identification elements 8 includes an optical substrate 10 having at least one diffraction grating 12 disposed therein. The grating 12 has one or more colocated pitches Λ which represent a unique identification digital code that is detected when illuminated by incident light 24. The incident light 24 may be directed transversely from the side of the substrate 10 (or from an end) with a narrow band (single wavelength) or multiple wavelength source, and the code is represented by a spatial distribution of light or a wavelength spectrum, respectively, or a combination thereof. The element 8 can provide a large number of unique codes, e.g., greater than 67 million codes, and can withstand harsh environments. The encoded element 8 may be used to label any desired item, such as large or small objects, products, solids, powders, liquids, gases, plants, minerals, cells and/or animals, or any combination of or portion of one or more thereof. The label may be used for many different purposes, such as for sorting, tracking, identification, verification, authentication, anti-theft/anti-counterfeit, security/anti-terrorism, or for other purposes. In a manufacturing environment, the elements 8 may be used to track inventory for production information or sales of goods/products.

A holographic projection system with a display screen and an optical wave tracking means for controlling the direction of propagation of a modulated wave uses a position controller and an eye finder. An extremely wide tracking range is realised in the projection system for simultaneous viewing of the reconstruction by multiple observers, which are situated beside one another. The reconstruction of the scene is reconstructed for each eye position of an observer such that the entire scene is visible in the visibility region in a large tracking range with minimal errors. The projection system reconstructs the scene with the help of modulated partial waves. Projection means direct these partial waves with separately holographically reconstructed segments of the scene at the desired eye position through a structure of screen segments which are at least horizontally staggered on the display screen.