Abstract: In known light modulation means, complex phase and amplitude values for modulating light waves are implemented and modulated either separately by two different light modulation means or a light modulation means having two layers of double-refracting materials, leading to increased expenses for material and adjustment. A new device is disclosed that simplifies the modulation of light waves in phase and amplitude in a single light modulation means made of double-refracting material. In a device having regularly disposed, controllable light-modulated elements having a double-refracting material for complex modulation of coherent light waves, and a modulation controller controlling the force-induced alignment of the optical axes of the molecules of the double-refracting material, means are provided for independently aligning the optical axes of the molecules in the light-modulating elements in two dimensions. The alignment can take place by electrical, magnetic, or optical acting means.

Abstract: Disclosed is a display for the holographic reconstruction of a three-dimensional scene using means which allow a reduction of speckle patterns. Speckle patterns result in the graining of a holographic reconstruction and worsen the quality thereof. The 3D scene is incoherently superimposed with itself chronologically or spatially in the eye of the observer. The modulated wave fronts of each reconstructed object point of the scene are shifted relative to themselves in the reconstruction beam path and superimposed in the eye of the observer. The shifting may occur one-dimensionally and two-dimensionally. Each object point is multiplied with itself in the eye of the observer in accordance with the number of the shifted wave fronts. The various speckle patterns over which the eye of the observer averages are also multiplied. Speckle patterns are reduced and the reconstruction quality is thus increased in holographic displays.

Abstract: A holographic reconstruction device is designed such that visible resolution of the reconstruction of a scene is matched to the resolution capability of the human eye, to the imaging properties of the reconstruction means used or to the resolution capability of the light modulation means used. A grid scale for the object points is generated by system control means in each case in a plane of intersection, which grid scale cannot be used to separately resolve adjacent object points in the plane of intersection, and the compilation of object points of the respective plane of intersection to form an object point group with adjacent object points which can be separately resolved is carried out. In holographic displays, the invention is used to reduce speckle patterns and reduce the number of the holograms of object points of the scene, which are to be calculated and coded, and the calculation complexity.

Abstract: A light modulator is disclosed for representing complex-valued data, comprising an encoding area that has an arrangement of pixels, the phase of which can be controlled. This largely avoids an interfering optical path difference between adjacent pixels or pixel groups when a complex value is encoded in several adjacent phase pixels of the encoding area, the optical path difference varying according to the angle. One respective specific structured delaying layer, which causes the optical path of an incident linearly polarized beam to change according to the angle, is associated with at least one predefined pixel of a group of adjacent pixels of the encoding area. The thickness of the delaying layer is designed such that the modification of the optical path caused by the delaying layer runs in the opposite direction from the angle-related modification of the optical path difference between individual pixels of the pixel group.

Abstract: A method is disclosed for reconstructing a three-dimensional scene in a holographic display. A 3D scene that is to be reconstructed is decomposed into object points, and one respective object point is encoded as a sub-hologram in the light modulator. Processor means and reconstruction means are provided for calculating and encoding as well as for reconstructing the 3D scene in order to overcome known drawbacks encountered when encoding a hologram and holographically reconstructing the 3D scene in holographic display devices. Processor elements are provided for generating a movable two-dimensional grid in the light modulating means, forming groups of object points from grid-related object points, and sequentially encoding the holograms of said groups of object points, by means of which intrinsically coherent partial constructions of the groups of object points are generated in a rapid sequence, said partial constructions being incoherent relative to one another.

Abstract: A method is disclosed for reconstructing a 3D scene made of object points in a holographic display, wherein the reconstruction is visible from a visibility region. Visibility and/or covering of parts of the 3D scene corresponding to the real parameters is realized, with the reconstruction, for a viewer from every place of the visibility region. Processor means generate a spatial point matrix for defining the positions of individual object points, which are assigned predetermined intensity and phase values. Within the visibility region, a complex-value wave front for each single object point is calculated. The intensity values of the object points are multiplied with the associated visibility function, to determine a common modified wave front of the object points, transformed into the plane of a light modulator to calculate modified control values for the object points.

Abstract: The invention relates to a phase-modulating light modulator and to a method for ensuring a minimal amplitude modulation in phase-modulating light modulators, wherein the phase-modulating light modulator comprises an optically active layer with at least one optically active volume region and with boundary surfaces, wherein the optically active layer is assigned at least one transparent compensation volume region which comprises at least one birefringent material with fixed refractive index ellipsoids, and has a polarizer arranged on the output side. An object is to achieve a reduced angle-dependence of the averaged amplitude modulation in the observation angle region. The object is achieved by optimizing the orientation with respect to one another of the refractive index ellipsoids of the optically active layer and of the compensation layers in a simulative manner.

Abstract: A holographic projection display for reconstructing a 3D-scene and a coding method that indicates an improvement of the control value of coding through an iterative Fourier transformations-algorithm are disclosed. The display includes a reproduction system including at least two reproducing means. First reproduction means for reproducing the illuminating means and for the Fourier transformation of actual wave fronts modulated in the phase modulator follow a second reproduction means, that functions as a screen. The plane of the screen is a Fourier transformation plane for calculations with the iterative Fourier transformation-algorithm and the plane of the phase modulator (6) is the other Fourier transformation plane.

Abstract: A device for the production of holographic reconstructions having light modulators is disclosed. The device comprises at least one pixelated light modulator illuminated by at least one light source, and a focusing optical element field arrangement which images the light sources in an image plane after the light modulator. For the reconstruction, only one order of diffraction of the Fourier spectrum of the hologram should be used. The light modulator is provided with an assigned filter-aperture field arrangement which is located in the area of the image plane of the light source images and which has a plurality of aperture openings. Said aperture openings are designed in such a way that they each allow the passage of a prespecified area of the overall dimensions either smaller or the same as a diffraction order of the diffraction spectrum following Fourier transformation and produced from the holographic coding of the light modulator.

Abstract: A method for reducing speckle patterns of a three-dimensional holographic reconstruction is disclosed. A controllable light modulator into which a three-dimensional scene is coded is illuminated by coherent light, a reconstruction means projects the modulated light close to an eye position into a space of observation and a control means controls the illumination. This provides a holographic reproduction device in which the speckle patterns occurring during reconstruction of a three-dimensional scene are reduced. Also provided is a next-to-real time method using a carrier medium of conventional image refresh rate.

Abstract: A head-mounted display device for generating reconstructions of three-dimensional representations comprising a frame, in which at least one light source, at least one optical system and at least one encodable light modulator are situated, wherein the light modulator with an encoding of a wavefront of the three-dimensional representation in the encoding area is positioned at the place of an observer window defined in an observer plane or the light modulator with an encoding of a hologram of the wavefront of the three-dimensional representation in the encoding area is positioned in the region closely in front of the observer window for transforming the hologram into the observer window. When the light modulators are illuminated, complex wavefronts of the three-dimensional representation are situated in the observer window and the reconstruction of the three-dimensional representation is visible in a visual cone spanned by the observer window and the light modulator.

Abstract: The object is to largely eliminate the errors which arise in the reconstruction of a hologram, calculated point by point, as a result of the encoding of said hologram into pixels of finite extent. The invention achieves the object by means of a method in which the common wavefront calculated from the object sectional planes is multiplied by the inverse transform of the pixel shape and pixel transparency in the viewer's window before the wavefront modified by the multiplication is transformed to the hologram plane and encoded as an amplitude and/or phase distribution of the hologram in the pixels of the light modulator. This method is implemented in a corresponding apparatus which contains an additional memory unit for providing a Fourier transform or its inverse Fourier transform and also a multiplication unit.

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: A method for reducing speckle patterns of a three-dimensional holographic reconstruction is disclosed. A controllable light modulator into which a hologram of a three-dimensional scene is coded is illuminated by coherent light, a reconstruction lens transforms the modulated light into an eye position and reconstructs the three-dimensional scene in a reconstruction space and a control means controls the illumination. This provides a holographic reproduction device in which the speckle patterns occurring during reconstruction of a three-dimensional scene are reduced. According to one embodiment, a next-to-real time method is presented using a carrier medium of conventional image refresh rate.

Abstract: A controllable device for phase modulation of coherent light with modulator cells comprising liquid crystal molecules is provided which realises a large number of phase steps per modulator cell and whose switching delay is shorter than 1 ms. The device can include a spatial light modulator with a modulator matrix having regularly arranged controllable LC modulator cells, a light source which illuminates the modulator matrix, and control means for controlling the phase modulation in the LC modulator cells. The modulator matrix can be configured to comprise a controllable ?/2 plate disposed between two non-controllable ?/4 plates; the controllable LC modulator cells can be PSS liquid crystal; each LC modulator cell is controllable locally with a positive or negative voltage value, depending on the actual phase values to be written; and the control means generate a globally constant phase offset for the phase values to be written in every other frame.

Abstract: 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; each unit comprises a focusing element, and a light means that emits sufficiently coherent light such that each of these illumination units illuminates one separate illuminated region of the surface, whereby the focusing element and the light means are arranged such that the light emitted by the light means coincides close to or at the observer eyes.

Abstract: The invention relates to a method for the multimodal representation of image contents on a display unit for video holograms. Said unit comprises at least one or several light sources (LS), an optical system (L), and a spatial light modulator SLM (S) with hologram contents. According to the inventive method, the unit directs the wavefront that an object would emit to the associated eye positions (EP) such that the viewer sees the reconstruction of the scene and different views are presented to the eyes by means of temporal or spatial multiplexing in order to generate the stereo effect.

Abstract: 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.

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: 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.