DE102011005154A1 - Combined light modulation device for user tracking - Google Patents

Abstract

A display with a large tracking area and a variable viewing distance is required for comfortable viewing of a 3D scene from different angles. A controllable light influencing means (500) deflects light in rough steps in a viewing area. Within these stages, the light is deflected continuously or finely graduated by a further controllable light influencing means (600). The light modulation device is suitable in holographic or autostereoscopic displays for tracking the visibility areas (1000) of the image information to be displayed on the eyes (1100) of the viewer.

Description

The invention relates to a combined light modulation device for a holographic or autostereoscopic display with user tracking. In the context of this invention, a combined light modulation device is understood to mean a device which, in a multi-stage process, alters the properties and / or the direction of light emanating from one or more real or virtual light sources.

In this case, a virtual light source is a light source which appears to be located in one place and appears by influencing the light of a real light source by means of usually static imaging means, for example a mirror, and / or beam limiting means, for example diaphragms.

A holographic display in the sense of this application is a display device for three-dimensional image data in which the three-dimensional object data of the scene to be displayed are written as diffraction patterns of the scene to be reconstructed. Reconstructing a three-dimensional scene in a high quality, high visibility area requires both a large computational effort and a high resolution light modulator.

The applicant therefore has in the patent DE 103 53 439 B4 proposed a method in which the calculation of the wavefront takes place only for a small range of visibility, which is only slightly larger in diameter than the diameter of an eye pupil of a viewer's eye. As a result, the object points to be reconstructed each need only be coded into respective sub-holograms in a small area of the light modulator.

For this purpose, with sufficiently coherent light of at least one light source at least one light modulator is illuminated and imaged by means of a field lens this light on at least one observer eye. By mutually connecting at least one further light source synchronized with the light modulator, the reconstruction of the three-dimensional scene for the second observer eye can be generated by encoding an associated hologram or the associated sub-holograms into the light modulator. A colored representation is possible by spatially or temporally interleaving (multiplexing) the hologram information for the individual color components. So that the viewer can move freely in front of the display, the focus areas are tracked to the observer's eyes by separately switching on further light sources. For this purpose, the eye coordinates of one or more observers are constantly determined with the aid of a position detection system.

By recalculating the diffraction pattern, the reconstruction of the scene can be adapted to the new viewer location. By temporal nesting so reconstructions for several observers can be represented.

For a user tracking along the light path, it is additionally advantageous to adapt the focal plane of the focusing unit and thus the size of the visibility range to the eye positions of the viewer.

In an autostereoscopic display (ASD) with user tracking, no diffraction patterns are encoded in the light modulator, but the scene views for the respective eye are written directly.

The user tracking can be done for example by direct or indirect moving the light sources. A well-known example of indirect shifting is deflection mirrors.

Numerous other methods of user tracking are known. This can be done by changing the light path in front of or behind the light modulator used for hologram coding or for stereo presentation. Besides mechanical methods, methods are known for changing reflective, diffractive or refractive properties by means of adaptive optics.

There are also known combined tracking variants, which have a fixed, but over the surface of the Lichtablenkmittels varying Lichtablenkfunktion.

In the patent application of the applicant DE 10 2008 054 438 A1 For example, a matrix of electrically controllable liquid cells is proposed for user tracking, the liquid cells having additional solid light deflecting means varying over the surface of the matrix in order, for example, to realize or support a field lens function. These light deflection means may, for example, comprise refractive elements such as prisms or lenses or diffractive elements such as volume gratings or blazed gratings, ie gratings optimized for a given wavelength.

In the patent application of the applicant DE 10 2009 028 626 A1 , whose disclosures are fully incorporated herein, teaches to use controllable diffractive grids for user tracking.

In order to achieve a larger deflection angle, these gratings can also be arranged one behind the other with the same deflection direction. For two-dimensional deflection, it is also possible to connect at least two controllable deflection gratings rotated at a fixed angle to one another. The diffractive gratings can realize a locally different deflection by varying the inscribed grating period over the surface of the deflection unit in order to achieve or support a field lens function.

For a controllable deflection grating whose grating period is variable to set a desired diffraction angle, there is a minimum settable period due to the spatial resolution with which the deflection grating can be driven. If, for example, the setting of the period takes place by means of a grid-shaped electrode structure, then production-related limitations on the width and spacing of the electrodes occur. In addition, crosstalk between set adjacent phase values occurs, for example, due to stray electrical fields or scattering or diffractive components of the deflection grid. These can also lead to a reduction of the diffraction efficiency and thus to disturbing scattered light or to light in higher diffraction orders.

Since the diffraction angle for a lattice-shaped diffraction structure is inversely proportional to the periodicity of the diffraction structure, the producible electrode spacing limits the controllable angle range and thus the tracking range for a single diffraction device.

For a comfortable viewing of a 3D scene from different angles, however, a display with a large tracking range at a variable observer distance is needed. What is sought is a solution that, despite the restriction of the diffraction angle of a deflection element allows a tracking range that is greater than the achievable with this element diffraction angle.

According to the invention the object is achieved with the features of claim 1.

A light modulation device for a holographic or an autostereoscopic display for displaying three-dimensional image information with at least one real or virtual light source, at least one light modulator for encoding the image information to be displayed for at least one observer eye at least one observer, a first and a second light influencing means for changing the light path of light emitted by the light source, an eye position detection system for detecting and tracking at least one eye position of the at least one viewer of the image information, and a system controller for tracking at least one visibility range of the image information based on the eye position data supplied from the eye position detection system by the first and second light influencing means which defines the visibility area within a viewer area tracking the eyes of the observer in coarse steps and by a second light influencing means, which finely graduated or continuously tracks the visibility range at least in the range of a coarse stage of the first light influencing means the eyes of the beholder using at least one electrically controllable diffraction grating.

In this case, the system controller selects the deflection direction of the first light influencing means which comes closest to the currently selected eye position of the selected observer and adjusts these in the first light influencing means. The difference angle between this deflection angle and the actual selected eye position is calculated simultaneously or promptly by the system controller and set in the second light influencing means.

Both eyes of a selected observer can be operated in time division multiplexing by the system controller, the eye position detection system providing the necessary eye position data.

For a 3D representation, the system control will display the image content to be displayed, ie. H. the respective stereo view or the encoded hologram, adapted to the respective right or left eye. The eye detection system can also be configured as a system for detecting the line of sight to z. For example, in a system with a large possible viewing angle, only reconstruct the parts of a scene that the viewer is looking at.

Multiple viewers can also be operated in time division multiplex mode, which however requires fast light modulators and fast light influencing means.

For a flicker-free display, a refresh rate of at least 60 frames per second is required for each view of the time division multiplex operation. With simultaneous time division multiplexing of the three color components and the two eyes of each observer, this value refers to the view of a color channel for an observer's eye.

Particularly in the case of a projection system, it is possible to use a separate deflection system for each viewer eye, which enables a simultaneous representation of the image contents for both viewer eyes via a beam combining system.

By adapting the image content to be displayed by the system control to the respective observer position, it is possible for the observer to move around the displayed image content within the visibility range of the display when moving the head, whereby this effect can also be artificially inflated or reduced.

Since achromatic diffractive Stahlablenksysteme can be produced only with great effort, a color representation in a preferred embodiment variant also takes place in the time division multiplex operation of the individual color components.

Depending on the configuration of the light modulation device, the second light influencing means with the controllable light deflection gratings may be located in front of or behind the first light influencing means for the coarse-light light deflection. A light influencing means for coarse light deflection, which requires fixed entrance angle for its function, as z. B. volume grating represent for diffractive beam deflection is arranged in an advantageous manner in front of the second light influencing means.

One or both light influencing means may be in front of or behind the. Be arranged light modulator.

They can be designed for a transmissive, an emissive or a reflective light modulator.

A transmissive or reflective light modulator is used in conjunction with a lighting device, which typically generates collimated light that illuminates the light modulator.

Examples of transmissive modulators are liquid crystal modulators on a transparent substrate having a multiplicity of controllable liquid crystal cells or modulators based on electrowetting cells arranged in rows and columns.

As reflective modulators, for example, liquid crystal modulators on a reflective substrate (eg LCOS - Liquid Crystal on Silicon) or micromirror devices (DMD - Digital Micromirror Device) are suitable as fast light modulators.

In a transmissive or reflective light modulator, the first and / or the second light influencing means or parts thereof can be integrated into the lighting device.

If, for example, the light modulator is a phase modulator for encoding complex-valued hologram values into two (two-phase coding) or multiple phase pixels of the modulator, then the associated phase values in a beam combination optics are combined to form an intensity value with defined amplitude and phase value advantageous to arrange both light influencing means behind the light modulator when the beam combination optics requires a defined transmission direction.

Such a beam combination optics, for example, in the not yet published German patent application DE 10 2009 044 910.8 proposed.

In an autostereoscopic display with a largely direction-independent amplitude modulator or a holographic display with a largely direction-independent complex-valued modulator, however, it may be advantageous to integrate one or both light influencing partially or completely into the illumination device of the light modulator.

Remaining direction-dependent intensity dependencies can advantageously be taken into account by the system controller when coding the image information, so that these dependencies can be compensated.

Emissive light modulators, such as electroluminescent displays or plasma displays, do not require a lighting device because they themselves serve as the light source. Since their individual pixels are incoherent to each other, they are preferably used in autostereoscopic displays as a light modulator.

In holographic displays, their use as a switchable light source in combination with collimating optics of the illumination device of a transmissive display is useful when the extent of a pixel is small enough to have a sufficient coherence length.

By means of the two light influencing means, the beam directions of the light sources are selected with the aid of the system control such that the information of a viewer eye to be displayed at the moment is within the visibility range of this eye.

Depending on the design and coding the light path can only be changed in the horizontal or in the horizontal and vertical directions.

A tracking of the visibility range only in the horizontal direction greatly simplifies the structure, since only light influencing means are needed, which can change the light path in one direction.

In a holographic display, the computational outlay for the hologram calculation in the case of a one-dimensional coding is considerably reduced compared to a two-dimensional coding.

One-dimensional viewer tracking can be done with linear real or virtual light sources. These can be, for example, display columns of an emissive display with an upstream collimation optics in the form of cylindrical lens arrays. In autostereoscopic displays often only a horizontal observer tracking is realized.

By changing the position of a real or virtual light source in front of a collimating optics in the horizontal or vertical direction, the direction of the collimated illumination beam in the horizontal or vertical direction can be changed. This can be achieved, for example, by switching on or controlling the brightness of individual light spots or light spot areas of a high-resolution light source matrix in conjunction with an upstream field of collimating optics, for example a lens array.

For a one-dimensional deflection, illumination strips can be used in conjunction with a cylindrical lens array.

A deflection of the light spots or light stripes can also be realized by mechanical or by scanning (scanning) methods.

By shifting the light sources in the direction of the optical axis of the associated collimating optics, the size of the light spot in the observer plane can be adjusted. This can also be achieved by a collimating optics whose refractive power is variable and can be controlled accordingly.

A light influencing means, which has a light source array with displaceable light sources and an associated collimating optics, can also serve as part of the illumination device when using a transmissive modulator.

By controlling the brightness of individual light source points, errors of the optical system can be compensated.

If individual light points of the controllable light source matrix have a clear distance from one another, the visibility range can be tracked in coarse steps. The mean deflection angle α for a light source, which is located at a distance l from the object-side main plane and at a distance a from the optical axis of the collimating optics, is in this case: α = arctane (a / l).

Thus, for example, the center beam of a light source, which is located 10 mm in front of the object-side main planes of the collimating optics and has a lateral offset of 2 mm with respect to the optical axis, a beam inclination of 11.3 degrees relative to the optical axis.

As already shown, a light influencing means can be constructed from a plurality of individual components. The first and / or the second light-influencing means of the light modulation device may be composed of a plurality of light-influencing elements with which the beam direction and / or the position of the real or virtual light sources can be changed independently of one another.

Thus, a plurality of electrically controllable deflection gratings with the same deflection direction can be partially or completely switched into a row in order to increase the achievable deflection angle or to realize a separate deflection region. For a two-dimensional deflection, one-dimensionally deflecting light-influencing elements can be combined to form a light influencing means. This can be done, for example, in a crossed arrangement.

The individual light-influencing elements of a light influencing agent can also be based on different physical principles of action.

The system controller takes into account the deflection characteristics of each individual element, whereby it is possible to compensate for errors arising in one element in one or more further elements.

By changing the magnitude of the change in position of the light of the light source and / or the size of the beam direction change in the first and / or second light influencing means depending on the impact of the light on the surface of the light influencing means can be a Field lens function to set the size of the visibility area in the observer level or affect the effect of a separate field lens.

By controlling this position or beam direction change over the area of one or more light influencing means by the system controller, the size of the visibility region can be changed variably and thus, for. B. this size can be adapted to a changed viewer distance to the display, so that the visibility range is greater than the pupil diameter but smaller than the eye relief.

For this purpose, the system controller evaluates the position or distance data supplied by the eye detection system and adjusts the calculated angle changes in the associated light influencing means in addition to the lateral angles which determine the position of the visibility area in the observer plane.

The beam direction change in the light influencing means for the coarse tracking of the visibility range may include both diffractive and refractive light influencing elements.

In a design variant with a fixed light source matrix, the individual lenses of the collimating optics have a controllable lens effect, so that the focal length and / or the lateral location of the lens vertex can be changed. Such a controllable lens based on a Elektrobenetzungszelle is for example in the European patent EP 1579249 B1 described.

For a coarse graduated beam deflection, volume gratings can advantageously be used in the first light influencing means, into which at least two holograms are inscribed.

By imprinting the holograms with the desired input and output distributions with the respective operating wavelength, the required volume grid or a template for further copies can be produced. The imprinting of the holograms can also be carried out in an optical system, which essentially corresponds to the insert system or is contained therein (in-situ exposure), in order to compensate as completely as possible for aberrations of participating optical components.

Volume grids can be optimized for very narrow angles of incidence, which differ only slightly from one another, and / or for narrow wavelength ranges. In this case, high diffraction efficiencies of approximately 100% for phase holograms can be achieved. The volume grids act as an angle filter, d. H. only light of a narrow angular range is diffracted in the desired direction, and / or as a wavelength filter, with only light of a selected wavelength range being diffracted in the desired direction. Light from other angles or wavelengths passes unbowed through the volume grid.

Thus, when passing through the volume grating only a diffraction order, d. H. For example, the first, second or higher diffraction order occurs, the Bragg condition must be complied with and the refractive index modulation selected accordingly. If the refractive index modulation deviates from the optimum, then - even in compliance with the Bragg condition - an undiffracted portion of the light, i. H. a zeroth order of diffraction, present.

Depending on the thickness of the volume grating and the maximum possible refractive index difference, it may be necessary to illuminate the grating in such a way that multiple beam interference occurs, ie. H. that a sufficient number of lattice planes are passed through by the individual light beams. This means that the minimum generated diffraction angle is not too small, for example 30 degrees. This can be achieved by obliquely illuminating the volume grating. By means of a further upstream volume grid, a necessary pre-deflection can be generated, if required by the geometric conditions.

The thicker the volume grille is, the greater its selective effect.

The diffraction processes at volume gratings were described by Kogelnik using the theory of coupled waves ( H. Kogelnik, "Coupled Wave Theory for Thick Hologram Gratings", Bell Syst. Techn. J. 48 (1969) 2909-2947 ). Dick is a volume lattice, if its Q factor: Q = 2πdλ / (n ₀ Λ ² ) is greater than 10. Here, d is the thickness of the volume grating, λ the working wavelength of the light in a vacuum, Λ the lattice constant of the volume grating and n ₀ the average power.

Instead of a volume grating which is optimized for several entrance angles and / or several wavelengths, a plurality of volume grids with a smaller functional range can be connected in series, i. H. each volume grid deflects the light in another direction or focuses it on another location.

In addition to different exit angles, additional field lens functions can advantageously be imprinted into the volume grid during production, which limit the diameter of the visibility area in the observer plane.

In general, arbitrary different wave fields can be reconstructed by angle multiplexing. This corresponds to the principle of holographic reconstruction. So field lenses with different focal lengths can be reconstructed. So it may also be advantageous to reconstruct in different directions propagating plane waves when z. B. a separate field lens is present.

The Foki the field lenses, which are generated by light distributions with different input angles, do not have to be in the same plane as this. Thus, for example, a series of field lenses could be generated from light distributions with different vertical input angles, the foci z. B. in the horizontal direction, in the horizontal and vertical direction or in the horizontal direction, in the vertical direction and in the focal plane differ.

In order to create or support a field lens function, it is possible to decompose the volume hologram into at least two sub-holograms arranged side by side, each of which individually satisfies the Bragg condition with slightly different exit angles, ie the volume lattice is segmented. The production and mode of action of such volume holograms is - by itself - for example from the German patents DE 19 700 162 B4 or DE 19 704 740 B4 known.

For selecting the individual directions inscribed in the volume hologram, at least one horizontal and / or vertical displacement unit may be present which controllably influences the light of the light sources so that the angle of incidence and / or the impact location on the volume hologram can be changed. This unit may for example be part of a backlighting device in a transparent light modulator or a front side lighting device in a reflective light modulator. The necessary shift and / or tilt is set by the system control based on the determined selected eye position. It can be done in a known manner with mechanical, reflective, refractive or diffractive methods. When using a flat lighting device, for example, the coupling angle can be varied in a planar waveguide.

A further advantageous embodiment variant used for each wavelength range, ie z. For example, for the red, green or blue spectral range, multiple narrowband light sources differing only slightly in their centroid wavelength and which are selectively selected and activated by the system controller to select or address the individual diffraction angles in the at least one volume grating , For such light sources, preferably lasers, for example semiconductor lasers, or narrow-band light-emitting diodes can be used.

The system controller can, depending on the selected narrow-band spectral ranges, perform a color correction of the information to be displayed.

Both methods can be combined with one another so that diffraction gratings for different angles of incidence and for different closely adjacent wavelengths are written into the at least one volume hologram.

In a further embodiment, at least one polariser switchable by the system control in conjunction with at least one birefringent lens is used for the roughly stepped change in the beam direction in the first light influencing means. Such a system is for example from the WO 03 015 424 A2 known for 2D / 3D switching in an autostereoscopic display.

A birefringent material, for example a liquid-crystal mixture, is arranged between two interfaces of two transparent media which serve as a substrate. In this case, at least one interface is partially curved to achieve a lens effect, and / or partially inclined relative to the other in order to achieve a wedge effect.

By selecting one of two possible polarization directions through the switchable polarizer, one of two possible lens and / or deflection effects can be selected using system control. The strength of the lens effect and / or the wedge angle may vary over the area of the deflection and / or focusing unit. It is also possible to perform the switchable polarizer segmented to select the two polarization directions locally variable.

The switchable polarizer can be formed, for example, as a variable retardation plate with the aid of an electrically controllable birefringent material, which may for example likewise consist of a liquid-crystal mixture. In this case, the birefringent material is embedded between two substrates, which are provided with suitable electrode structures. Here, too, it is possible to connect several such light-influencing elements in succession in order to increase the overall effect in the light-influencing means.

Instead of a switchable polarizer and a fixed birefringent light-influencing element, it is also possible to use switchable birefringent light-influencing elements. In such a device, as z. B. for the 2D / 3D switching in autostereoscopic displays in the WO 2007/007 285 A2 is proposed, the number of required substrates compared to the aforementioned solution can be reduced. These light influencing elements can also be segmented and / or arranged one behind the other.

By means of suitable electrode structures, it is also possible to produce planar light-influencing elements in which a controllable gradient index curve of the refractive index can be generated by applying suitable electric field distributions, with which the direction of light can be influenced.

In further embodiments, at least one polarization grating is used to influence the light. In such a grid, only the -1 exist. the 0th and the +1. Diffraction order. By using incident circularly polarized light, it is possible, approximately 100% of the light depending on the direction of rotation of the circular polarization only in the +1. or only in the -1. Distract diffraction order.

Both actively switchable polarization gratings and passive polarization gratings are known. The preparation of polarization gratings can be done by aligning liquid crystals on appropriately prepared surfaces. Such surfaces, which act as alignment layers for the liquid crystals, can be produced by, for example, polymerizing out linear photopolymerizable polymers (LPP). For this purpose, the layers are, for example, with interference patterns of circularly polarized ultraviolet light, z. B. of a UV laser, designed accordingly.

With no or low voltage on an electrode structure, the active polarizing gratings form a periodic lattice structure and can be in the +1. Depending on the direction of rotation of the incident circularly polarized light. or in the -1. Distract diffraction order with high diffraction efficiency. With sufficiently high voltage, the liquid crystals can be aligned so that the lattice structure is destroyed, so that the incident light in the 0th order of diffraction passes undeflected by such a light influencing element.

Passive gratings can be formed, for example, by polymerizing out liquid crystal polymers (LCPs). Both active and passive polarization gratings can be used in combination with a switchable polarizer, such as a switchable retarder plate, to select the desired diffraction order. With an active polarization grating, the system controller controls both the switchable polarizer and the controllable grating to select the desired diffraction direction. With a passive grid, only the switchable polarizer is activated. It is possible to connect several combinations of switchable polarizers and polarization gratings as light-influencing elements in succession. The lattice constant of the polarization grating can be varied over the light entry surface to achieve a locally different deflection effect. This variation can be continuous or segmented. As a result, z. B. a field lens function can be realized or supported. For example, cylindrical lenses or crossed cylindrical lenses can also be implemented.

In order to select the respectively suitable diffraction angle by the system control, the areal switchable polarizer can likewise be structured.

If the grating is used in combination with other light deflection elements, for example a superior field lens and / or other light influencing elements, the grating must be locally optimized for a corresponding oblique light incidence. This can be done with an active polarization grid by a local adjustment of the driving voltage and thus the effective birefringence.

For passive polarization gratings, the hologram used for fabrication must have a local variation of the grating period.

For a simple polarization grating, the deflection angle depends on the wavelength. In a color display in which the individual color components are generated in a time division multiplex operation, this angular difference must be compensated by the system control in further controllable deflection elements.

From the WO 2008/130 561 A1 are z. As well as multi-layer systems passive polarization grating known in which the deflection angle remains almost constant over a wide spectral range.

In a further embodiment variant diffractive gratings are used for coarse light deflection whose grating period can be changed by changing the voltage applied to a liquid crystal cell voltage. Such a system is for example in the US Pat. No. 6,188,462 B1 described. By Variation of the applied voltage across the grid surface can also be variably set by a locally different deflection angle by the system controller.

For the coarse light deflection, it is also advantageous to use diffractive phase gratings, as provided for the continuous deflection in the second light influencing means. In these gratings, the grating periods and thus the size of the deflection angle are adjusted by applying a sawtooth voltage gradient to a fine electrode structure. The smallest possible grating period and thus the largest possible deflection angle is determined by the electrode grid. Because very fine grid with few. Microns to a few hundred nanometers raster period are difficult to control, especially in large-scale deflection, can be summarized for the deflection grid for coarse deflection electrodes and acted upon by a common signal, if the distance is greater than the grating period for the largest possible deflection angle in the Deflector for the fine-step deflection corresponds. For example, the finely deflected deflection grating may have a period of electrodes of a few microns, in which each electrode can be driven individually, and the grating for the coarse-wave deflection consist of a grating with an electrode spacing of less than one micrometer, with each electrode after a larger distance are summarized, as it corresponds to the electrode grid of the fine-scale grating.

The combination of the electrodes can be segmented over the surface of the deflection grating. It is also possible to vary the electrode grid over the grid surface to z. B. at the grid edge by a finer electrode grid to allow a larger deflection angle required there.

For beam deflection of light bundles with a small cross-section, as they are emitted in the illumination device of light sources with a small expansion directly or after a corresponding beam shaping, can advantageously be used further Lichtablenkelemente in a transmissive or reflective operation. Thus, acousto-optic modulators (AOM) allow high-speed beam deflection. In this case, the deflection angle can be changed by varying the drive frequency. The diffraction efficiency can be influenced by the height of the drive voltage. There are also AOM's known, which have several transducers that can be controlled with phase-shifted signals. As a result, the effective phase grating in the AOM can be tilted as a function of the phase angle and thus adapted to changing exit angles, so that the Bragg condition is largely fulfilled at the same entrance angle in order to obtain a high diffraction efficiency for a wide output angular range and a wide operating wavelength range. Such a modulator is for example from the US 5 576 880 known. Since only small deflection angles can be generated with an AOM, a volume grating with several encoded exit angles or a corresponding volume grid stack of individual gratings with respectively different exit angles at entry angles, which differ only slightly, can be connected downstream to increase the angular range. Such an arrangement is for example from the US 3,980,389 known.

All optical interfaces of the light influencing means or light influencing elements should advantageously be provided with antireflection layers to avoid stray light. These can be carried out spectrally and / or at an angle narrow or broadband in a known manner depending on the application.

In the optical beam path suitable diaphragms for filtering out unnecessary diffraction orders and / or scattered light may be included. Also, the use of additional means for wave front shaping, such as Apodisationsmasken possible.

Further possible measures for the optimization and special design of the method, such as the use of lookup tables for rapid calculation of the setting parameters for the deflection angle, the use of common substrates in the multi-layer structure of Lichtablenkelementen, measures for calibration, for error compensation, for compensation of a temperature influence, for Compensation of aging phenomena or for the design of the drive circuits and electrode structures are part of this invention and are not explained in more detail, since these measures are known to a person skilled in the knowledge of the teaching described herein. All controllable components can be designed with the help of suitable additional measuring devices as controllable components.

Instead of electrically controllable diffraction gratings, other known light deflection elements can be used for the continuous observer tracking.

There are now various possibilities for designing and developing the teaching of the present invention in an advantageous manner. On the one hand on the claims subordinate to claim 1 and on the other hand on the to refer to the following explanation of the preferred embodiments of the invention with reference to the drawings. In the drawings show (each in a schematic representation)

1 a first embodiment variant of the invention,

2 a section of a light influencing means for coarsely graduated tracking by means of switchable light sources,

3 a light influencing means for coarsely graduated tracking by means of switchable light sources with additional field lens function,

4 a section of a light influencing means for coarsely graded tracking with a light source tracking by means of diffractive deflection gratings in the illumination device,

5 a section of a lighting device with a volume grid and angle multiplex

6 a light modulation device with a reflective modulator,

7 the generation of two field lenses by means of an active liquid crystal lattice,

8th a light modulation device having a transmissive modulator and a liquid crystal phase grating with controllable grating period in conjunction with a multiplex field lens,

9 a flat backlight device which allows vertical and horizontal displacement of the wave field generated by a collimation unit prior to entry into a first volume grating,

10a to 10c the exemplary effects of two controllable volume gratings as vertical light influencing elements from the 9 and

11 a light modulation device with a transmissive modulator and a polarization grating in conjunction with a switchable polarizer.

In 1 a typical embodiment variant of a light modulation device is shown schematically. A light source 100 , which is designed here as a planar light source field, comprises a plurality of individual light sources 101 to 123 with small extent, which via a system control 900 individually or in groups switchable or in their brightness can be controlled or regulated. In this case, each individual light source 101 to 123 also consist of several light sources with different center of gravity wavelength, which are also controlled separately. The light sources 101 to 123 Illuminate about a collimation optics 200 consisting of a field of single lenses 201 - 203 or cylindrical lens strip may consist of a planar light modulator 400 , The lenses 201 to 203 can also be designed to be controllable, so that their focal point in one, two or three directions by the system control 900 is changeable adjustable. The device can be an aperture field 250 have to prevent light from a light source 101 to 123 through several lenses 201 to 203 the collimation optics 200 occurs. This is especially important if the device is designed for multiple viewers. At the in 1 The example shown becomes a transmissive light modulator 400 used, which changes the amplitude and / or the phase of the light areal. This forms the controllable light source field 100 in combination with the collimation optics 200 a dynamic lighting device 300 ,

The light modulator 400 receives its modulation values for the display of three-dimensional image information from the control panel 900 , the these values based on the input data of the 3D scene 902 and that of an eye position detection system 800 delivered position data from at least one eye position 1100 determined at least one observer of the image information. The system control takes this into account 900 the characteristic of the light modulator 400 and other correction values resulting from the design of the optical system and the position data. The image information to be displayed, in particular the section of the scene to be displayed, may also be outside the system control 900 from the Control Panel 900 Eye position data supplied to an external arithmetic unit 901 be prepared. The known eye position recognition system 800 can z. B. consist of at least one camera and an associated evaluation, wherein the evaluation also part of the system control 900 can be. The evaluation unit determines from the camera images the position of the eye pupils in the respective camera image and calculates therefrom the associated location coordinates of all observer eyes 1100 , Also other eye position detection systems 800 For example, working with ultrasound or using passive or active brands or signal sources, which are connected to the viewer, can be used.

In the light path between the light sources 101 to 123 and the viewer's eyes 1100 can be more light influencing elements 501 are located by the Control Panel 900 be controlled. The dynamic lighting device 300 forms in the illustrated embodiment alone or in combination with the others Light influencing elements 501 the light influencing agent 500 for the coarse beam deflection. To the respective visibility area 1000 based on the eye position data 901 through the system control 900 to steer continuously or finely graduated to the respective observer's eye, is a second light influencing means 600 in the form of diffractive controllable deflecting gratings, which may also be composed of a plurality of light influencing elements. To focus the visibility area 1000 to the observer level is in the example 1 a field lens 700 present, which can also be configured as a controllable adaptive lens, the upper the system control 900 an adaptation of the extent of the visibility area 1000 to the distance of the observer's eyes 1100 from the light modulator 400 allows. The function of the field lens 700 however, may also be partially or fully incorporated in the dynamic lighting device 300 and / or in other light influencing elements 501 and or in light influencing elements of the second light influencing means 600 to get integrated.

2 schematically shows a section of a lighting device, which as a light influencing means for the coarsely graded tracking at least one visibility area on the location of at least one observer eye by means of switchable light sources 101 to 103 is trained.

A variety of switchable or controllable light sources 101 . 102 . 103 are in front of a collimation optics 200 , which may contain refractive and / or diffractive elements. By switching on one of the exemplified light sources 101 . 102 or 103 the desired deflection direction is selected. The deflection angle depends on the distance of the light source to the optical axis OA of the segment of the collimating optics 200 and their distance to the object-side main plane of these imaging segments. In the example shown are the light sources 101 to 103 in the object-side focal plane, so that the collimation optics 200 parallel light leaves. This illuminates the light modulator 400 ,

3 schematically shows a variant of the coarsely graded tracking by switching or controllable light sources 101 - 123 with additional field lens function. The individual light sources 101 - 123 a light source 100 , which is designed as a planar light source field, are asymmetrical behind the Kollimationslinsen 201 - 203 a collimation optics 200 arranged so that the light of the light sources 101 - 123 which passes through the light modulator 400 passes, in the direction of the edge region of the light modulator 400 is deflected more towards the center of the viewer area of the display screen than the light from light sources in the center of the collimating optics 200 , The light sources 101 - 123 can, as shown here, outside the focal plane of the collimating lenses 201 to 203 be arranged so that they are mapped into the middle observer plane.

The individual light sources 101 - 123 can be composed of individually switchable or controllable sub-light sources with different spectral distributions of the emission characteristic. The individual sub-light sources can easily be staggered in depth, ie at different positions in the direction of the optical axis in order to compensate for chromatic aberrations of the collimation optics, so that all color components are largely imaged in the same central observer plane.

For this purpose, z. B. also the refractive power of the Kollimationslinsen 201 to 203 be variably changed by the system control to compensate for such color errors and adjust the observer level to the distance of the viewer to the display screen.

There are a number of other ways to realize a field lens function. So could the optical axis of the individual Kollimationslinsen 201 to 203 more and more to the edge of the lens field 200 be tilted so that, for example, all optical axes in the center of the observer area intersect in the middle observer plane. It can also be a lens 201 to 203 associated light sources 101 to 123 be arranged inclined.

4 shows the principle of observer tracking by means of diffractive grating on a section of a lighting device. A collimated light source 101 Illuminates a switchable or controllable light influencing element 501 for beam deflection, which may for example contain at least one diffractive deflection grating. This directs the rays of the collimated light source 101 depending on the set deflection angle to another location of a screen 110 , The scattering profile can be varied locally such that the best possible illumination of the following collimating lens 201 which z. B. may contain diffractive and / or refractive elements is achieved. The locally varying scattering profile of the ground glass 110 For example, it can be generated holographically. The impact points of the light influencing element 501 deflected light rays form depending on the deflection angle secondary light sources 111 - 113 which via the collimating lens 201 a collimating optics analogous to an area of the light modulator 2 or 3 illuminate. Again, the light source 101 from individually switchable. Sublight sources with different spectral distributions of the radiation pattern exist. The light influencing element 500 may be composed of a plurality of baffles to allow, for example, a two-dimensional deflection. By suitable screens 250 can be prevented, that light unused diffraction orders, which at the light influencing element 501 may arise, or light of the secondary light sources 111 - 113 which is not on the collimation lens 201 falls, further Kollimationslinsen the collimating optics illuminated or propagates as unwanted stray light in the lighting device.

As a deflecting grid in the light influencing element 501 For example, it is possible to use controllable diffractive gratings in which the grating period can be set variably.

For example, phase gratings based on liquid crystal cells can be used, in which variable grid periods and thus deflection angles can be written in via a grid-shaped electrode structure.

Likewise acousto-optic modulators can be used.

However, other design variants are possible, such as the use of active and passive polarization grids in conjunction with controllable retarder plates.

As the distance between the light influencing element 501 and the focusing screens 110 can be chosen large, it is possible in the light influencing element 501 Use deflection gratings that can only generate small deflection angle. As a result, only small demands are placed on the required minimum grating period, which considerably simplifies the production of such deflecting elements.

In order to hide unwanted intensities in the zeroth diffraction order, you can obliquely illuminated the controllable grid. In order to obtain an optimal deflection range for each operating wavelength, which overlap as far as possible, the grating can be illuminated for each working wavelength range with a different adapted angle.

Instead of the deflection grating in the light influencing element 501 Other baffles may be used. For example, it is possible to use controllable electrowetting cells in which the position of a meniscus or the position and shape of a meniscus can be varied in one or in two directions as the interface between two liquids having different refractive indices.

In 5 is a section of a lighting device with a volume grid and angle multiplex of the light sources shown symbolically. The light influencing element 501 that has at least one volume grid 502 contains to light influencing, it is from different directions of multiple light sources 101 - 103 about collimation optics 201 - 203 Illuminated under slightly different directions. Into the volume grid 502 of the light influencing element 501 Different reconstruction geometries are permanently encoded. When illuminated from different directions, different output wavefronts are generated. For example, the volume grid 502 of the light influencing element 501 that also comes from a stack of multiple volume bars 502 can be illuminated at five angles with a pitch of 0.3 °, which produce on the output side five field lens wavefronts with an angular increment of, for example, 12 °.

6 schematically shows a light modulation device for a reflective light modulator 400 for image coding in conjunction with a front lighting device. The front lighting device for illuminating the light modulator 400 with collimated light contains a stack of planar light deflecting elements 510 . 520 , The respective deflection function can be activated by activating the respective light deflection element 510 . 520 associated light source 110 . 120 to be selected. The light sources 110 . 120 be in the example by at least one laser diode for the red 111 . 121 , the green 112 . 122 and the blue one 113 . 123 Spectral range formed. About the light sources 110 . 120 associated collimation units 210 . 220 their light is transmitted through at least one volume grid 511 . 521 in a plane optical fiber 513 . 523 coupled, each on a substrate 514 . 524 are located. In the example are in the volume grid 511 . 521 each inscribed a hologram for the red, the green and the blue spectral range. For coherent optical applications, such as a holographic display, the planar optical fiber should be used 513 . 523 are chosen so thin that in each case only one reflection angle (single mode light guide) can propagate to obtain the coherence properties of the light.

About that the plane optical fibers 513 . 523 assigned volume grid 512 . 522 The light is output from this and onto the reflective light modulator 400 collimated steered. That of the reflective modulator 400 Modulated light will vary depending on the selected light source 111 - 113 . 121 - 123 through the assigned volume grid 512 . 522 deflected in the desired direction or as shown here in the example at the desired location in the Viewer level focused. In the example are also in the volume grid 512 . 522 Holograms for each operating wavelength of the light sources 110 . 120 enrolled. The holograms are designed so that over the entire surface of the light modulator 400 a uniform illumination intensity is generated. This requires the diffraction efficiency in the volume grid 512 . 522 increase, the farther the decoupling point of each coupling grid 511 . 521 is removed.

At least one additional continuous or fine light deflector 600 ensures that, depending on the position of the observer, the light can also be directed to eye positions that are not aligned with the fixed focusing points of the volume grids 512 . 522 registered holograms match. In this case, the deflection element 600 support the field lens function or take over this function completely. Likewise, a separate field lens, for example, between the light deflection 600 and the viewer.

The light sources 110 . 120 associated collimation units 210 . 220 can be passive and / or active optical elements 211 . 212 . 221 . 222 for beam shaping and beam direction change, which can affect the light reflective, diffractive and refractive. You can also include scanning components, such as the infeed volume grid 511 . 521 to illuminate in stripes.

7 schematically shows a further embodiment variant of the invention. It can by a controllable volume grid 532 one in two in a static volume grid 533 inscribed field lenses by a in 7 not shown system control can be selected. A reflective phase modulator 400 , which of a front lighting device 300 is collimated, generates a modulated phase distribution containing the image information to be displayed. In a beam combination optics 410 is achieved by combining light passing through adjacent pixels of the phase modulator 400 was modulated, a wavefront spatially modulated in amplitude and phase 450 to reconstruct the objects to be displayed in the reconstruction space. The object points can be real between the viewer and the light modulator 400 and virtually behind the light modulator 400 be reconstructed. The modulated wavefront 450 is from the static volume grid 531 deflected by a fixed angle to the subsequent controllable volume grid 532 to produce an optimum entry angle. In this case, the exit angles for the individual narrow-band wavelength ranges of the light sources of the front-side illumination device 300 slightly different. Depending on the control of the controllable volume grid 532 the light passes through this unbent or is diffracted at the lattice structure in the first diffraction order. In the controllable volume grid 532 it may, for example, be a polymer-dispersed liquid crystal lattice. The desired diffraction pattern is generated in the manufacturing process by local polymerization when writing a hologram. Depending on the applied voltage on an electrode structure, the refractive index difference between the grid elements can be controlled in such a grid. If the voltage is chosen so that no difference in refractive index is present, the light passes through the grille unbent. By means of a suitable voltage at the electrodes, the refractive index difference in the grating can be selected such that for the current reconstruction wavelength range almost all light is diffracted into the first order.

A static volume grid 533 , which may also be formed as a multiplexed volume grid, focuses the respectively selected direction in the focus area 1001 respectively. 1002 , In this case, the different entry angles for the individual wavelength ranges can also be taken into account so that the focus areas of the individual colors each form a common focus area.

It is also possible to change the diffraction angles in the grids 531 and or 532 to vary locally, for the volume grid 533 locally to obtain a suitable entrance angle to set in this grid the required diffraction angle with high diffraction efficiency. In this case, a segmented arrangement can be used. The arrangement is also suitable for amplitude modulators or complex-valued modulators. Similarly, transmissive modulators can be used with a backlight device. For an autostereoscopic display, for example, the focus points for the right and left viewer eyes can be switched over in this way. In general, the arrangement of a not shown light influencing means for the continuous tracking of the foci is adjusted to the observer position.

8th schematically shows an embodiment variant of a light modulation device with at least one transmissive phase modulator 400 for encoding the image information in conjunction with a controllable liquid crystal phase grating 541 , The light modulator 400 is provided with sufficiently coherent light with a backlight device 300 illuminated. The light modulator 400 modulated light is in at least one beam combining optics 410 to a wavefront spatially modulated in amplitude and phase 450 shaped. This wave front meets at least one controllable liquid crystal phase grating 541 for the stepwise deflection of the wavefront. For this purpose, the liquid crystal phase grid has 541 a plurality of electrodes, which can be controlled individually or in groups with a variable voltage profile. By applying a sawtooth-shaped voltage profile with a variable period length and a variable voltage swing to the electrode structure, a Bragg grating is produced in the liquid crystal lattice. Due to the generated sawtooth curve of the phase profile on the grid this acts as a blazed grating for the set deflection direction when the grating period and the phase deviation are adapted to the current operating wavelength. As a result, the light of the wavefront with high diffraction efficiency is diffracted in the desired deflection direction.

In general, the liquid crystal phase grating 541 generate discrete or continuously variable angles for example, three wavelengths.

In the following field lens, which is a thin volume grid 542 can contain and a thick volume grid 543 has one, the one in the thick volume grid 543 written focus areas 1001 - 1005 through the liquid crystal phase grid 541 selected deflection angle selected. The thin volume grid 542 , if present, diffracts the light from the liquid crystal phase grating 541 comes, so for the at least one thick volume grid 543 an optimal or suitable entrance angle is formed so that the light in the liquid crystal phase grid 541 can be diffracted with high diffraction efficiency.

A light influencing agent 600 , which contains at least one finely structured controllable diffractive liquid crystal phase grating, serves as a light influencing means for the continuous or finely graduated tracking of the selected focus area 1001 - 1005 to the position of the selected eye of the viewer through the in 8th not shown system control. This forms the visibility area for viewing the reconstruction for the selected viewer's eye.

In 9 schematically a light influencing means for the coarse beam deflection is shown, which is integrated in a flat backlight unit. A light source 100 illuminated via a beam expansion optics 210 a collimation optics 220 , The light source 100 can be z. B. contain at least one individually controllable laser diode for the red, the green and the blue spectral range. That of the collimation optics 220 Collimated light is transmitted through a lens field 230 each on the apertures of an aperture field 120 directed. The apertures act as secondary light sources and together form a light source field. In the beam path can be further optical components 110 for the treatment of the light source 100 radiated light are located. Thus, for example, at least one moving focusing screen can be positioned to reduce interfering speckles, which modulates the coherent laser radiation with a random phase. Instead of a single light source 100 and the iris field 120 It is also possible to use a light source field which contains, for example, a plurality of laser diodes of the required wavelength ranges. The individual secondary. Light sources of the aperture field 120 be over another lens field 240 collimates and illuminate a first light influencing element 550 for beam deflection in the vertical direction. Here, too, can in the beam path more optical components 130 for the treatment of the secondary light sources 120 radiated light are located. Thus, at least one fixed or moving focusing screen can limit the spatial coherence on the output surface of the backlight device to a suitable level, so that, for example, sub-holograms to be displayed do not influence one another. A second light influencing element 560 can affect the light in the horizontal direction. It is also possible that the light influencing elements 550 . 560 affect the light in a direction other than horizontal or vertical, or arranged in a changed order. The light influencing elements 550 . 560 may also be combined in a light influencing element having a two-dimensional light-influencing effect. That of the light influencing agent 550 outgoing light illuminates via a light guide 260 a first volume grid 570 , This directs the light over another optical fiber 270 on a second volume grid 580 , Depending on the controllable light influencing elements 550 . 560 generated angular distribution of the light with its selected wavelength distribution is via the into the volume grid 570 and 580 inscribed volume holograms selected the desired angle spectrum for illuminating a light modulator, not shown here. In this case, the angular distribution by the light influencing elements 550 . 560 be designed so that the entire modulator area is illuminated uniformly bright. In addition, the diffraction efficiency of the volume lattice 570 . 580 , as already described, vary locally.

The light guides 260 and 270 should advantageously consist of a material whose refractive power is as little as possible of the associated volume grid 570 and 580 differs to avoid reflections at the interfaces. One or both light guides 260 . 270 can also be configured wedge-shaped. However, they can also be made of other materials, such as air. In this case If necessary, the interfaces must be anti-reflective.

Through the volume grid 570 and 580 At the same time an anamorphic magnification of the through the secondary light sources takes place 120 generated and the lens field 240 collimated illumination wave field. This makes it possible to select the in the volume grid 570 and 580 inscribed hologram functions light influencing elements 550 . 560 to use with small spatial extent. These can be easier and less expensive to produce than large-area arrangements. Small-scale controllable deflection gratings can also be produced with a smaller lattice constant, as a result of which higher diffraction angles can be generated.

In the light path between the light source 100 and the light guide 260 For example, other optical components such as optical fibers or deflection mirrors may be located to allow a compact design of the overall system.

The 10a to 10c schematically show a possible structure and three exemplary effects of a light influencing element from the embodiment of 9 on the basis of the light influencing element 550 for the vertical distraction.

Two consecutive controllable liquid crystal phase gratings 551 and 552 influence as vertical displacement unit an input wave front 150 and transform them into an output wavefront 160 ,

In the example of 10a is due to the two controllable liquid crystal phase grating 551 and 552 both a vertical displacement and an angle change of the propagation direction of the wave field 150 generated.

Example according to 10b demonstrates a widening and shifting of the center of gravity of the wave field 150 ,

In the example according to the 10c there is a shift and locally varying change of the exit angle of the wave field 150 ,

In 11 schematically, an embodiment variant of a light modulation device is shown in which the tracking of the visibility range of the reconstruction of the 3D scene in coarse steps to the position of the eyes of the observer using a passive polarization grid in conjunction with active polarization-changing light influencing elements.

One from a backlight unit 300 sufficiently coherently illuminated phase modulator 400 in which the scene to be reconstructed is coded, generated with the aid of a beam combination optics 410 a wavefront spatially modulated in amplitude and phase 450 , By a switchable or controllable polarizer 591 , which may be formed, for example, as a switchable or controllable retarder plate, becomes the light of the wavefront 450 optional right or left circular polarized on the subsequent polarization grid 593 directed. The polarization grid 593 In accordance with the direction of polarization of the incident light with high diffraction efficiency, the light diffracts into either the +1 or -1 order of diffraction. Between the switchable polarizer 591 and the polarization grating 593 can be a volume hologram 592 are arranged, which diffracts the light passing through the switchable or controllable polarization-changing element locally in such a direction that they have a suitable angle of incidence for the polarization grating 593 represents.

A polarization-altering element 594 , which can also be formed switchable or controllable, can behind the polarization grid 593 be arranged to suppress light which is not deflected into the desired diffraction order.

A subsequent light influencing agent 600 For continuous or fine-level light deflection, the light directs the modulated wavefront 450 to the eyes of the beholder so that they can perceive the reconstructed 3D scene.

The arrangement may contain further passive or active polarization-influencing elements in order to set the required polarization direction for subsequent polarization-dependent elements or to convert linearly polarized light into circularly polarized light or vice versa.

In the exemplary embodiment is a passive polarization grating 593 whose grating period varies locally continuously or in steps. As a result, z. B. a field lens function can be realized. At neutral position of the light influencing agent 600 Depending on the position of the switchable or controllable polarization-influencing elements 591 respectively. 594 the light of the wavefront 450 to one of the two visibility areas 1001 or 1002 directed. One or both switchable or controllable polarization-influencing elements 591 respectively. 594 may also be locally structured and separately controllable in one or two directions to compensate for influences of the transmission angle and / or the instantaneous wavelength range of the transmitted light.

It can also polarization grating 593 be used with uniform lattice constant. These direct that light of the modulated wavefront 450 depending on the position of the polarization-altering element 591 in one of two directions, defined by the +1 and -1 order of diffraction. The field lens function can then be achieved by additional passive and / or active optical elements, such as volume gratings.

By locally controllable polarization-changing elements 591 . 594 can be stacked, which consists of such elements 591 . 594 and passive polarization gratings 593 exist, the influence of the deflection angle of elements 591 . 593 . 594 the stacking planes arranged in front of the beam path in the wavelength-dependent manner on the polarization change in the respective polarization-influencing element 591 . 594 compensate. Polarization-influencing elements 594 and 591 which follow each other and belong to different adjacent stack levels can also be combined in a common controllable polarization-influencing element.

Such stacks can be used to create more than two focus areas or deflection directions. Preferably, the polarization gratings have 593 in the stack levels at the same horizontal and vertical position different lattice constants and thus different diffraction angles in order to achieve a total of even and as fine as possible gradations, so that double focus areas are avoided.

Through the use of polarization gratings 593 with controllable grating period, the number of layers in such a stack can be kept small.

With switchable polarization gratings 593 In addition, the zeroth diffraction order can be used.

By a suitable combination of the layer thickness and thus the optical retardation and the angle of rotation of the liquid crystal molecules polarizing grating 593 which have nearly a diffraction efficiency of 100% for a wide wavelength range. There may also be stacks of switchable polarizing gratings 593 be used, in which each element is optimized for a different wavelength range.

Thus, in a color multiplex operation only the optimized for the current spectral range grating can be activated.

Instead of a phase modulator 400 and a beam combining optics 410 It is also possible to use a complex-valued light modulator. Likewise, the use of a reflective modulator in conjunction with a front lighting is possible.

In the exemplary embodiments listed, it is also possible to use light modulators which generate the coded hologram via a scanning device or which contain a plurality of light modulators. Likewise, a holographic or autostereoscopic display may also include a plurality of separate light modulating devices that collectively reconstruct a 3D scene or create a stereoscopic image.

The control of all active components can be done in all examples by a system control based on the determined by an eye position detection system positions of the observer's eyes, wherein z. B. image errors of optical components, temperature influences and local deviations of the wavefront shape due to brightness variations in the lighting device 300 and modulation errors in the light modulator 400 be considered and compensated as far as possible. If necessary, such errors can be determined by calibration measurements or actively measured in real time.

Finally, it should be particularly noted that the embodiments discussed above are merely for the purpose of describing the claimed teaching, but do not limit it to the exemplary embodiments.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10353439 B4 [0004]
• DE 102008054438 A1 [0012]
• DE 102009028626 A1 [0013]
• DE 102009044910 [0036]
• EP 1579249 B1 [0062]
• DE 19700162 B4 [0074]
• DE 19704740 B4 [0074]
• WO 03015424 A2 [0079]
• WO 2007/007285 A2 [0083]
• WO 2008/130561 A1 [0093]
• US 6188462 B1 [0094]
• US 5576880 [0097]
• US Pat. No. 3,980,389 [0097]

Cited non-patent literature

• H. Kogelnik, "Coupled Wave Theory for Thick Hologram Gratings", Bell Syst. Techn. J. 48 (1969) 2909-2947 [0069]

Claims (20)

Light modulation device for a holographic or autostereoscopic display for displaying three-dimensional image information with at least one real or virtual light source ( 100 ), at least one light modulator ( 400 ) for encoding the image information to be displayed for at least one observer's eye ( 1100 ) at least one observer, a first and a second light influencing means ( 500 . 600 ) for changing the light path of the light source ( 100 ) emitted light, an eye position detection system ( 800 ) for capturing and tracking at least one eye position of the at least one observer of the image information and a system control ( 900 ) for tracking at least one visibility area ( 1000 ) of the image information based on the eye position data provided by the eye position recognition system ( 901 ) with the aid of the first and the second light influencing means ( 500 . 600 ), characterized in that the first light influencing means ( 500 ) the visibility range ( 1000 ) tracks within a viewer area the eyes of the observer in coarse steps and that the second light influencing means ( 600 ) the visibility range ( 1000 ) at least in the region of a coarse stage of the first light influencing agent ( 500 ) the eyes of the beholder ( 1100 ) finely graded or continuously tracked by means of at least one electrically controllable diffraction grating. Light modulation device according to claim 1, characterized in that in the light propagation direction the second light influencing means ( 600 ) in front of or behind the first light influencing means ( 500 ) is arranged and that the first and / or second light influencing means ( 500 . 600 ) in front of or behind the light modulator ( 400 ) is arranged. Light modulation device according to claim 1 or 2, characterized in that with the first ( 500 ) and / or the second light influencing means ( 600 ) the position of the light source ( 100 ) and / or the beam direction of the light path is changeable, wherein the position of the light source ( 100 ) is adjustable in one or in two or in three directions and the beam direction of the light path in the horizontal and / or vertical direction is adjustable. Light modulation device according to one of the preceding claims, characterized in that the first and / or the second light influencing means ( 500 . 600 ) of several. Light influencing elements is composed, with which independently of the beam direction and / or the position of the light source ( 100 ) is changeable. Light modulation device according to one of the preceding claims, characterized in that the magnitude of the change in position of the light of the light source ( 100 ) and / or the size of the beam direction change in the first and / or second light influencing means ( 500 . 600 ) depending on the location of the light on the surface of the light influencing agent ( 500 . 600 ) is changeable, so that in addition to the tracking function a field lens function fixed or variable focal length is feasible or such a field lens function is supported. Light modulation device according to one of the preceding claims, characterized in that the change in position of at least one light source ( 100 ) in the first light influencing means by a mechanical movement of the at least one light source ( 100 ) and / or modulating the intensity of multiple light sources ( 100 ) can be realized in different places. Light modulation device according to one of the preceding claims, characterized in that at least one first light influencing means ( 500 ), which influences the light diffractively and / or refractively. Light modulation device according to one of the preceding claims, characterized in that at least one first light influencing means ( 500 ) contains one or more successive diffractive gratings, which influence the direction of light by switching on or off a fixed or locally variable grating period. Light modulation device according to one of the preceding claims, characterized in that in the first light influencing means ( 500 ) a device for changing the positions of the light sources and / or their emission directions is included and that the first light influencing means at least one volume hologram ( 502 ), in which at least two angle-selective diffraction angles and / or field lens functions are inscribed, which are selectable by changing the direction of the light. Light modulation device according to claim 9, characterized in that between at least one light source and at least one volume hologram at least one horizontal and / or vertical displacement unit and / or a tilting unit is present, which controllably influences the light of the light source so that the angle of incidence and / or the impact on the volume hologram ( 502 ) is changeable. Light modulation device according to one of the preceding claims 1 to 8, characterized characterized in that at least one real or virtual light source is present, which switchably illuminates the first light influencing means with at least two closely spaced narrowband wavelength ranges and that the first light influencing means comprises at least one volume hologram ( 502 ), in which at least two wavelength-selective diffraction angles and / or field lens functions tuned to these wavelength ranges are written, which are selectable by changing the wavelengths of the light sources. Lichtmodulationsvorrichtuhg according to claims 9 or 10, characterized in that in the first light influencing means at least one volume hologram ( 502 ), in which at least two angle-selective and at least two wavelength-selective diffraction angles and / or field lens functions are inscribed. Light modulation device according to one of the preceding claims 9 to 12, characterized in that at least one of the volume holograms ( 502 ) of the first light influencing means contains at least two successively arranged volume holograms which are tuned to different entrance angles and / or wavelength ranges in order to deflect and / or focus light in different directions. A light modulating device according to any of the preceding claims 1 to 10 or 12, characterized in that the first light influencing means comprises at least one switchable retardation plate and at least one birefringent lens to change the beam direction of the light. Light modulation device according to claim 14, characterized in that at least one birefringent lens is a liquid crystal lens. Light modulation device according to one of claims 14 or 15, characterized in that at least one birefringent polarization grating ( 593 ) with a solid grating period varying over the area of the polarization grating to change the beam direction of the light. Light modulation device according to one of the preceding claims 1 to 10 or 12, characterized in that in the first light influencing means at least one birefringent polarization grating ( 593 ) having a switchable solid grating period or varying over the surface of the polarizing grating to change the beam direction of the light sources. Light modulation device according to claim 17, characterized in that the at least one birefringent switchable polarization grating ( 593 ), which has been optimized for oblique incidence of light and / or which has achromatic properties and is optimized for at least two wavelengths. Light modulation device according to one of the preceding claims, characterized in that in the second light influencing means ( 600 ) at least one changeable diffractive grating is present, with which the beam direction changes by the controllable uniform or locally variable change of a grating period of the diffractive grating is adjustable. A light modulating device according to claim 19, characterized in that at least one of the changeable diffractive gratings includes a liquid crystal layer whose locally fixed or variable grating period is changed by applying the voltage profile to an electrode structure.

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