Abstract: The invention relates to a method and to a circuit arrangement for recognising and for tracking, in a contact-free manner, eye positions of several users in real time. The input data comprises a sequence of digital video frames. Said method comprises the following steps: combining a face-finder-instance which is used to examine faces, an eye-finder-instance which is used to examine eye areas, and an eye-tracker-instance which is used to recognise and track eye reference points. The aim of the invention is to convert the eye positions within a hierarchical outlet of the instance to the target, which successively restricts the dataset, which is to be processed, emerging from the dataset of the entire video frame (VF) in order to form a face target area (GZ) and subsequently an eye target area (AZ). Also, an instance or a group of instances, which run in a parallel manner, are carried out, respectively, on a calculating unit thereof.

Abstract: A geometrical method for working out how to encode a hologram onto a hologram bearing medium is disclosed. The method involves (a) selecting a point on the three dimensional scene to be reconstructed; then (b) defining a virtual observer window through which the reconstructed three dimensional scene will be seen; then (c) tracing a pyramid from the edges of the observer window through the point and onto a region that forms only a portion of a hologram bearing medium; and finally (d) generating, solely in that region of the hologram-bearing medium, holographic information needed to generate a holographic reconstruction of the point.

Abstract: In a video hologram that enables a three dimensional scene to be reconstructed, a specific region in the hologram encodes information for a particular, single point in the reconstructed scene. This region is the only region in the hologram encoded with information for that point, and is restricted in size to form a portion of the entire hologram, the size being such that multiple reconstructions of that point caused by higher diffraction orders are not visible at the defined viewing position. This contrasts with conventional holograms, in which the information needed to reconstruct a given point is distributed across the entire hologram.

Abstract: The invention relates to video holograms and devices for reconstructing video holograms, comprising an optical system having a light source, lens and the video hologram having cells arranged in a matrix or a regular pattern with at least one opening per cell, the phase or amplitude of said opening being controllable. The holographic video representations of expanded spatial objects can be achieved in a wide viewing area in real time using controllable displays, whereby the objects are either computer-generated or created by different means. The space-bandwidth product (SBP) of the hologram is thus reduced to a minimum and the periodicity interval of the Fourier spectrum is used as a viewing window on the inverse transformation plane, through which the object is visible in the preceding space. The mobility of the viewer(s) is achieved by tracking the viewing window.

Abstract: The invention relates to video holograms and devices for reconstructing video holograms, comprising an optical system that consists of a light source, lens and the video hologram that is composed of cells arranged in a matrix or a regular pattern with at least one opening per cell, the phase or amplitude of said opening being controllable. The video holograms and devices for reconstructing the same are characterized in that holographic video representations of expanded spatial objects can be achieved in a wide viewing area in real time using controllable displays, whereby the objects are either computer-generated or created by different means. The space-bandwidth product (SBP) of the hologram is thus reduced to a minimum and the periodicity interval of the Fourier spectrum is used as a viewing window on the inverse transformation plane, through which the object is visible in the preceding space. The mobility of the viewer(s) is achieved by tracking the viewing window.

Abstract: A method and a device for encoding and reconstructing computer-generated video holograms using a conventional LC display: it provides holographic reconstruction of three-dimensional scenes using electronically controllable pixel in a holographic array (3) with a conventional resolution, and is reasonably free from flickering and cross-talk. Reconstruction is in real time, and for both eyes at the same time, over a large viewing zone. The method takes advantage of an optical focusing means (2) in order to image vertically coherent light emitted by a line light source (1) into viewing windows (8R, 8L) after modulation by the pixel array (3). The holographic reconstruction (11) of the scene is rendered visible from viewing windows (8R, 8L) for both eyes of an observer by way of diffraction at the pixels.

Abstract: The invention relates to an image display device comprising an imaging matrix, which consists of imaging elements which are arranged in a lateral manner, for example, lenticulars or a lens array, and a plurality of point elements which are disposed on a object plane and which are formed from the imaging elements in an observation chamber. In order to reduce imaging errors resulting in the image field curvature of the individual imaging elements of a large observation angle, compensation by a correction matrix, which contains a plurality of optical corrections elements, takes place. An optical correction element is associated with each individual optical imaging element. Said invention can be used, for example, in image or video display devices, such as autostereoscopic displays, multi-user-displays with sweet-spot-units and multi-view-displays, in order to image illuminating elements.

Abstract: 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.

Abstract: 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.

Abstract: The invention relates to a method and an apparatus for replicating planar, thin-layered, and microstructured flat lens system and optical mask (LM) that are provided with such microstructured lens system which are hardened from a highly viscous transparent fluid on a supporting substrate plate (TP). The fluid is introduced between a plate-shaped master plate (M) and a movable supporting substrate plate and remains joined to said substrate plate after hardening. The inventive method is carried out in a non-rotational manner while the molding space is not delimited by sidewalls or similar in the direction of expansion of the fluid. The inventive flat lens systems or optical masks are embodied as lenticular arrays, field lenses, or Fresnel lenses. The final shape of the mask is homogeneous, has a geometrically accurate layer thickness, and is free from air pockets. The inventive method and apparatus allow for controlled replication at great geometrical accuracy and extremely good optical quality.

Abstract: The invention relates to a sweet spot unit for multiple user display with an enlarged observation area, preferably for an electronic display for reproducing stereoscopic and/or monoscopic representation which are automatically oriented towards the eyes of different observers by means of a position finder and a tracking and image control system. A said sweet spot unit contains deviation means (5), between the imaging means (3) and the image matrix, provided with deviation elements (511, 512, . . . 51n) which have a width (WL) and are periodically arranged in groups (L, N, R) in a matrix, vertically in accordance with the vertical screening (HV) of the illumination matrix (1). Each group deviates the bundle of rays (91, 92, 93, . . . ) respectively at another pre-determined angle, in order to reproduce the same in one of a plurality of horizontally arranged sweet spots areas.

Abstract: An autostereoscopic multi-user display comprising a sweet-spot unit which is directionally controlled by a tracking and image control device (160), wherein an illumination matrix (120) is provided with separately activatable illuminating elements (11 . . . 56), in addition to an imaging device used to alternatingly image active illuminating elements, for making expanded sweet spots (SR1/SR2) visible to various eye positions (EL1/ER1, EL2/ER2) of viewers observing alternating images or a stereoscopic image sequence on a transmissive image matrix (140) with the aid of directed beams (B1R . . . B5L).

Abstract: A video holographic display device operates so that the size of a reconstructed three dimensional scene is a function of the size of the hologram-bearing medium; the reconstructed three dimensional scene can then be anywhere within a volume defined by the hologram-bearing medium and a virtual observer window through which the reconstructed three dimensional scene must be viewed. This contrasts with conventional holograms, in which the size of the reconstructed scene is localised to a far smaller volume and is not a function of the size of the hologram-bearing medium at all.

Abstract: The invention relates to an optical imaging system for separating images, more specifically a sweet spot beam splitter, for an autostereoscopic display, which allows for greater freedom of movement of at least one observer in a lateral direction as well as regarding the distance from the display by expanding sweet spots up to and beyond the size corresponding to the distance between the eyes. The observer can move within said area without losing the 3D impression such that the demands on the positional accuracy and the reaction time of the tracking system are lowered. The inventive sweet spot beam splitter comprises a first lenticular system (L1) and a second lenticular system (L2), the strip-shaped lenses of which are disposed parallel to each other while being offset by half a lens width in a vertical direction relative to the columns of the image matrix (M). The distance therebetween preferably corresponds to the focal length of the second lenticular system (L2).

Abstract: The invention relates to a method and device for tracking the sweet spots of a sweets spot unit for a transmissive electronic display. The aim of the invention is to improve the reproduction quality and the uniformity of illumination in displays of this type. The display contains a sweet spot unit consisting of an illumination matrix (1) and reproduction elements, in addition to an image matrix (4). Once the position of at least one observer's eye (6) has been determined by a control unit using inverse ray tracing, address data for activating illumination elements (LE) of the illumination matrix (1) is provided from the position data in order to prepare the defined sweet spots (5) for said observer's eye (6). To improve the reproduction quality, an additional optical component is used in ray path for the inverse ray tracing process.

Abstract: The invention relates to a method and to a circuit arrangement for recognising and for tracking, in a contact-free manner, eye positions of several users in real time. The input data comprises a sequence of digital video frames. Said method comprises the following steps: combining a face-finder-instance which is used to examine faces, an eye-finder-instance which is used to examine eye areas, and an eye-tracker-instance which is used to recognise and track eye reference points. The aim of the invention is to convert the eye positions within a hierarchical outlet of the instance to the target, which successively restricts the dataset, which is to be processed, emerging from the dataset of the entire video frame (VF) in order to form a face target area (GZ) and subsequently an eye target area (AZ). Also, an instance or a group of instances, which run in a parallel manner, are carried out, respectively, on a calculating unit thereof.

Abstract: The invention relates to an autostereoscopic multi-user display comprising a focussing element and a selectable display for the time-sequential representation of 2D and/or 3D images. When viewed in the direction of the observer, said display contains a sweet-spot unit and an image matrix, which function separately from one another. The sweet-spot unit focuses a light distribution with a large surface area onto the eyes of the observer by means of a lateral sweet-spot extension, which is greater than or equal to the distance between the eyes of the observer. The sweet-spot bundle traverses the imaging matrix completely in a uniform manner on its way to the observer(s) and is thus modulated by the image content of the image matrix. The size of the sweet spot reduces the need for tracking precision. The sweet-spot unit consists of an illumination and imaging matrix.

Abstract: The invention relates to a controllable illumination device for an autostereoscopic or holographic display, which illumination device contains an illumination matrix of primary light sources having at least one luminous element per light source and a controllable light modulator (SLM) and a reproduction matrix. A computer-generated hologram (CGH) illuminated by the primary light sources (11, . . . , 1n) is coded on the controllable light modulator (SLM) and generates, in at least one plane downstream of the SLM, a matrix—reconstructed from the computer-generated hologram (CGH)—of secondary light sources (2) having a secondary light distribution for the purpose of illuminating the reproduction matrix (4) and for the purpose of focussing in light bundles onto each eye of the viewer via an imaging matrix. The CGH is calculated and reconstructed on the basis of the number of and the positions of the viewers and the system parameters.

Abstract: The invention relates to a projection device and a method for holographic reconstruction of scenes comprising a light modulator (8), an imaging system (3) with at least two imaging means (4, 5, 9) and an illumination device (1) with sufficient coherent light for illumination of hologram (2) coded in the light modulator (8). The at least two imaging means (4, 5) are arranged such that a first imaging means (4) is provided for the magnified imaging of the light modulator (8) on a second imaging means (5). The second imaging means (5) is provided for imaging of a plane (10) of a spatial frequency spectrum of the light modulator (8) in a viewing plane (6) at least one viewing window (15). The viewing window (15) corresponds to a diffraction order of the spatial frequency spectrum.

Abstract: A method and a device for encoding and reconstructing computer-generated video holograms using a conventional LC display: it provides holographic reconstruction of three-dimensional scenes using electronically controllable pixel in a holographic array (3) with a conventional resolution, and is reasonably free from flickering and cross-talk. Reconstruction is in real time, and for both eyes at the same time, over a large viewing zone. The method takes advantage of an optical focusing means (2) in order to image vertically coherent light emitted by a line light source (1) into viewing windows (8R, 8L) after modulation by the pixel array (3). The holographic reconstruction (11) of the scene is rendered visible from viewing windows (8R, 8L) for both eyes of an observer by way of diffraction at the pixels.