Holographic light-field display system

Abstract

The invention relates to a holographic display system comprising a waveguide, an optical in-coupling element and an optical out-coupling element. The in-coupling element is designed to deflect light incident on the in-coupling element to the optical out-coupling element via the waveguide. Moreover, the out-coupling element is designed to interact with at least one controllable light source in such a way that, when the in-coupling element is illuminated with a controllable light signal from the at least one light source, an image is generated based at least in part on the light signal.

Description

[0001] Holographic light field display system

[0002] 1. Technical area

[0003] The present invention relates to holographic display systems with input and output coupling elements, in particular for creating (holographic) images, wherein the output coupling element is designed to interact with at least one controllable light source in such a way that it generates the (holographic) image at least partially based on the light signal.

[0004] 2. State of the art

[0005] Conventional 3D display systems are preferably based on devices that allow light to be redirected in such a way that, for example, light beams can be focused and / or dispersed in a controlled manner, so that the user or viewer of the display system receives the impression of a 3D image.

[0006] Microlenses, for example, are suitable for this purpose, e.g. in a so-called “micro lens array” (MLA), as shown in Fig. 1a and described herein. In such systems, the MLA is typically illuminated from the side opposite the viewer (back), for which purpose several light sources can be mounted, for example, under each microlens of the MLA. However, illumination from the back of the MLA leads to considerable complications, which can lead to, for example, poorer image quality, increased labor effort and high costs for corresponding systems. In conventional MLA-based display systems, the number of light sources determines the number of different angular views generated by such a display system - i.e., the angular resolution of the system. On the other hand, the size of the MLA lenses determines the spatial resolution of the display system.Due to these two limitations, the spatial and angular resolution of current MLA-based display systems can be limited by the size of the MLA lenses and the pixel size of the light-emitting displays used as light sources. In other examples, holograms can be used to generate the 3D image. For example, if reflection holograms are used, the holograms can be illuminated from the same side as the viewer's view of the display system, as shown in Fig. 1b.While such an embodiment simplifies combinations with 2D screens, the positioning of the light source for illuminating the holograms can be disadvantageous, as the following disadvantages can arise, for example: Firstly, the light source can take up space that the viewer needs to interact with the display system, for example, to perform (control) gestures and / or to operate a touchscreen of the display system. Secondly, the light source can block the viewer's view of the display system from certain viewing directions. Thirdly, for many embodiments, it can be fundamentally disadvantageous to rely on an element mounted in front of a screen. For example, in handheld devices such as mobile phones, this can be perceived by the user as visually unsightly and / or disturbing. In the case of transmission holograms, analogous disadvantages arise as described herein with regard to MLA.Each of these exemplary disadvantages, individually and especially in combination with each other, currently limits the possibilities of using holograms for 3D display systems and exploiting their advantageous properties when viewed in isolation.

[0007] DE 10 2012 100 206 Ai relates to an optical device for directing illumination light onto a pixel matrix and / or onto a controllable spatial light modulator of a display, in particular a stereoscopic or holographic 3D display. The optical device comprises a light-guiding layer configured as an optical waveguide, in which the illumination light is guided between two substantially opposing, planar reflection means. The optical device is characterized in that at least one of the reflection means comprises a reflection grating or a dielectric mirror.

[0008] DE 10 2021108 339 Ai relates to a light field display. The light field display comprises a plurality of display units for generating image content and an optical system for generating a light field from the image content. The display units each comprise at least one light source and a microscanner. DE 10 2021108 339 Ai also relates to a method, a computer program with instructions, and a device for calibrating such a light field display.

[0009] DE 10 2017217193 Ai relates to a display device, in particular for a vehicle, with at least one pane, with at least one volume hologram arranged at least within a transparent partial region of the pane, and with at least one light source, by means of which light can be coupled into the volume hologram, from which light can be generated by means of the volume hologram at least one image which appears three-dimensional to a human observer, wherein at least one camera device having at least one light-sensitive image sensor, the optics of which, by means of which images can be captured by means of the image sensor, is formed at least partially by the partial region.

[0010] The present invention is therefore based on the object of at least partially improving corresponding display systems and associated methods.

[0011] 3. Summary of the invention

[0012] This task is at least partially solved by the aspects described herein.

[0013] A first aspect relates to a holographic (light field) display system comprising a waveguide, an optical input coupling element (EE), and an optical output coupling element (AE). The EE is configured to redirect light incident on the EE via the waveguide to the optical AE. The optical AE is configured to interact with at least one controllable light source such that, upon illumination of the EE with a controllable light signal from the at least one light source, it generates an image based at least partially on the light signal.

[0014] This brings with it a number of advantages which are based on the advantageous interaction of the elements used in the display system: Essentially, the combination of EE, waveguide and AE enables light to be applied to the EE, deflected by it and passed within the waveguide to the optical AE, which is designed to generate the image. The inventors have thus succeeded in being able to position the location at which the illumination is coupled into the display system, i.e. the location of the EE, and the location at which the illumination is coupled out in order to generate the (3D) image, i.e. the location of the AE, essentially freely relative to one another, without impairing the functional interaction of the aforementioned elements. In this way, the disadvantages mentioned here which typically arise in connection with the positioning of the light source can be at least partially avoided. The generated 3D image orThe holographic image can correspond to a virtual object in space, which can be perceived by a viewer as a 3D object.

[0015] Furthermore, as described herein, the waveguide can be configured such that the integration of a 2D screen as described herein is possible without restricting the functionality of the display system. For this purpose, the waveguide can be configured, for example, in the form of a flat or curved plane or disk. In such exemplary embodiments, for example, the EE can be placed at a location in the imaging system that lies outside the area intended for outputting the image to the viewer. From there, the illumination can reach the AE, for example via total internal reflection within the waveguide, for example in a direction substantially perpendicular to the viewer's line of sight or parallel to the surface of the 2D screen.

[0016] The light signal may have one or more wavelengths (e.g., in the form of a discrete or continuous spectrum). Preferably, the one or more wavelengths may be in the visible spectral range, e.g., between 300 nm and 900 nm.

[0017] For example, a hologram or a holographic optical element (HOE) can be provided as the EE and / or AE. Furthermore, it is possible for the EE and / or AE to comprise a transmissive and / or reflective relief grating. The EE can further comprise a mirror surface, a prism, and / or a reflective or transmissive Fresnel structure. These variants can be provided as an alternative to the EE and / or AE or in addition to the EE and / or AE.

[0018] Typically, the EE and / or the AE and the waveguide are coordinated in such a way that the EE, taking into account its relative positioning to the waveguide and / or the AE, is configured to redirect the light signal to the AE. This can include, among other things, a distance between EE and AE in a waveguide plane of the waveguide, a relative tilt of the EE and AE in the waveguide plane, a thickness of the waveguide and / or other parameters relating to the relative positioning of the EE, the AE and / or the waveguide. For example, the EE and the AE can be spaced apart from one another in one direction, which direction can lie, for example, in the plane of the waveguide.

[0019] The waveguide can, for example, comprise or consist of glass and / or plastic. It can, for example, be a single piece or have a multi-layer structure. The waveguide can, for example, be substantially transparent (e.g., 90%, 95%, 99% transmission or more) to visible light (e.g., in the range of 300 nm - 900 nm), so that, for example, a 2D screen can be placed behind the waveguide in the direction of observation of a viewer, so that the viewer can, for example, be shown a combination of a 2D image (from the 2D screen) and a 3D image (from the holographic display system or its AE).

[0020] The at least one light source may, for example, comprise one or more projectors configured to apply the light signal at least partially to the EE.

[0021] The light signal can contain image information, so that the image information is made visible / accessible to a viewer in the form of an image generated by the AE when the AE at least partially couples out the light signal. The interaction of the AE with the at least one controllable light source can, for example, comprise generating a first image for a first light signal and generating a second image for a second light signal, wherein the first and second images can be different. The first and second light signals can, for example, differ in which part of the at least one light source (or which light source if there is more than one light source) and / or at which angle (or in which spatial direction) the light signal is emitted. In an exemplary embodiment, the holographic display system comprises the at least one controllable light source for emitting the controllable light signal.

[0022] As an integral part of the holographic display system, the controllable light source including its controllable light signal can be advantageously adapted to the geometry of the display system described herein and / or the elements of the display system, which can improve the image quality.

[0023] In exemplary embodiments, the holographic display system can comprise an AE, which in turn comprises a plurality of predetermined AE regions. Furthermore, the controllable light signal can comprise a plurality of controllable light points. The at least one light source can be configured, for example, such that at least one light point, preferably a plurality of light points with different wavelengths, can be directed onto each predetermined AE region.

[0024] If predetermined AE regions of the AE can be targeted or controlled, higher-quality images can be produced. In principle, image quality can improve if the precision of this control increases. The predetermined AE regions can be predetermined, for example, by structural properties of the AE.

[0025] A light spot can be understood herein as a light intensity distribution generated by applying the light signal to the AE and / or to a predetermined AE region. Such a light spot can, for example, have a substantially 2D Gaussian distribution, but can alternatively also include distributions of any shape deviating from this.

[0026] For example, the AE regions can be arranged periodically on the AE, preferably in a two-dimensional grid.

[0027] In principle, the image perceived by the observer from a given viewing direction can be composed of contributions from the various AE regions. If the AE regions are arranged periodically, the image quality can be kept spatially constant (high).

[0028] In the example of an arrangement of AE regions in a two-dimensional grid, for example, a geometric center of gravity can be determined for each AE region. The geometric centers of gravity and / or other characteristic points of the AE regions can, for example, be arranged for the same or different AE regions in a two-dimensional grid as follows: Their position can be determined in a predetermined (flat or curved) plane, for example the plane of the waveguide, by the vector (x, y) = m • (x x , y x ) + n2• (x2, y2), where m and n2 can be integers and / or (x x , y x) and (x2, y2) may not be parallel and may represent the basis vectors of the lattice. For example, the (finite) two-dimensional lattice may comprise at least one repetition in a first direction (e.g., along (xi, yd)) and / or at least one repetition in a second direction (e.g., along (x2, y2)).

[0029] The periodicity described herein typically extends only over a limited spatial area. In some examples, at least two of the AE regions are identically shaped, and in some examples, even (almost) all of the AE regions are identically shaped. In such examples, the same AE regions may represent the unit cells of the lattice. Typical lattices may, for example, include square, rectangular, parallelogram-shaped, triangular, and / or hexagonal unit cells and / or AE regions.

[0030] For example, at least one of the predetermined AE areas can be configured to receive a plurality of light points at different positions and / or at different angles of incidence, so that they are coupled out with different angles of reflection depending on the position and / or the angle of incidence.

[0031] The at least one light source can, for example, be configured so that a sub-area of ​​an AE area can be targeted. For example, at least one light point, preferably several light points with different wavelengths, can be directed onto a sub-area of ​​an AE area, e.g., a hill.

[0032] For example, the at least one predetermined AE range may enable angles of emergence that can substantially span an angle of view of the display system, and wherein the at least one predetermined AE range may be a local range of the AE.

[0033] If several angles of reflection are enabled in this form, the corresponding AE area can be seen by the viewer from different viewing directions, so that the viewer can perceive a 3D image, which can, for example, improve the quality of the image.

[0034] The field of view of the display system can encompass all the angles of reflection that can be realized by the AE areas of the display system. Essentially, the field of view can encompass a spatial area on the viewer side of the display system. If the viewer is within the field of view, light from the display system reaches the viewer, allowing them to perceive the display. If the viewer is outside the field of view, no light from the display system reaches the viewer, meaning they cannot perceive the display.

[0035] The angle of reflection can be understood here as the angle of reflection of the light emitted from the AE or the corresponding AE region. The angle of reflection can, for example, correspond to the angle between the axis of the propagation direction of the emitted light and an axis that is perpendicular to the AE or the AE region, e.g., at the location of the geometric center of gravity of the AE region.

[0036] A local area of ​​the AE can be understood herein, for example, as a locally limited, contiguous area of ​​the AE, as explained in the following example: In an exemplary embodiment, the AE can comprise a rectangular area with a height H and a width B. If, for example, H = 67 mm, B = 120 mm and the AE comprises several AE areas, e.g. humps, with an area of ​​1 mm by 1 mm, then the AE comprises 67 by 120, i.e. 8040 local AE areas, where the 8040 local AE areas each correspond to a hump with an area of ​​1 mm by 1 mm. At least one of these local AE areas, but preferably several or even (almost) all of these local AE areas, can enable angles of reflection to generate the image visible to a viewer in the entire field of view (or in part thereof) of the display system, so that the desired 3D impression can be created for the viewer.

[0037] In exemplary embodiments of the holographic display system, the at least one predetermined AE range may enable the angles of emergence for at least two wavelengths.

[0038] This can be particularly advantageous for images in two or more colors, which can increase the variety of images that can be displayed and thus increase image variety and quality.

[0039] In exemplary embodiments, the at least one predetermined AE region may comprise a plurality of AE pixels, which may be configured to couple out a light spot with a predetermined angle of incidence at a predetermined angle of reflection, wherein preferably the number of AE pixels may correspond to the number of possible different angles of reflection of the AE region.

[0040] This can improve the image quality, e.g. with regard to the different viewing directions of a viewer.

[0041] Essentially, the viewer can thus see a corresponding view of the (holographic) image from their viewing direction, the spatial resolution of which can be defined by the number of AE areas. In this example, the number of AE pixels per AE area determines the number of different views of the image that can be generated from different viewing directions, e.g., a moving viewer, and thus determines the angular resolution of the display system. An AE area can, for example, comprise at least one “hogel.” A hogel can, for example, comprise a computer-generated hologram that comprises a predetermined number of AE pixels described herein. If, in one example, the AE is composed of a plurality of hogels, a hogel, through its predetermined number of AE pixels, determines a finite number of distinguishable views of the image generated by the AE of the display system from different viewing directions of a viewer.A periodic arrangement of AE regions, e.g., Högels, preferably in a two-dimensional grid, can be used to create an image. This can be based, for example, on one or more light signals coupled from the AE comprising several AE regions, e.g., Högels.

[0042] In one example, each AE area can have 16 by 16 sub-areas, e.g. AE pixels, each of which can be configured to couple out light with a specific angle of reflection. In the above example of a display system with a rectangular AE with H = 67 mm, W = 120 mm and 8040 local AE areas (with a square area of ​​1 mm by 1 mm), this would result in sub-areas (e.g. AE pixels) with an area of ​​62.5 pm by 62.5 pm, each of which can be assigned to a viewing direction of the associated AE area. This concept can be applied analogously to other embodiments, e.g. to display systems with other AE, AE areas and / or sub-areas (e.g. AE pixels) with regard to their number, shape and / or dimensions, etc.

[0043] In an exemplary holographic display system, a first of the plurality of AE pixels (e.g., of a specific AE region) may be transparent to light of a first predetermined angle of incidence and output light of a second predetermined angle of incidence. A second of the plurality of AE pixels (e.g., of the same specific AE region) may output light of the first predetermined angle of incidence and preferably be transparent to light of the second predetermined angle of incidence.

[0044] This eliminates the need to selectively direct a light spot onto (only) one AE pixel to generate light with a specific angle of incidence at an AE area. Instead, the entire AE area can be illuminated, for example, with light from the first predetermined angle of incidence, to which only the second AE pixel "responds." This allows the AE areas, such as the Hogel, to be reduced in size, which can result in a higher resolution of the generated image.

[0045] The image information contained in the light signal can, for example, be applied to the EE or a part thereof where coupling and / or deflection takes place. The EE can be configured to couple the light signal from different light sources into the waveguide at different angles. This can, for example, depend on the direction from which the light signal hits the EE and / or the point on the EE where the light signal hits. In such examples, the coupled-in light can propagate at different azimuthal angles (αp; as described herein) in the waveguide and strike the AE. The AE can, for example, couple out the deflected light signal depending on the angle, e.g. as a function of αp. In this way, for example, the 3D image can be generated at least partially based on the angle αp of the respective light signal.

[0046] For example, the at least one predetermined AE region may comprise at least 14400 AE pixels, preferably at least 28800 AE pixels, more preferably at least 57600 AE pixels, or most preferably at least 307200 AE pixels.

[0047] These exemplary AE pixel counts have been found to be advantageous for a viewer in that they allow high-quality images to be produced over an acceptable range of viewing angles with an acceptable number of possible viewing directions.

[0048] In some examples, the at least one light source may be configured to provide at least one light point for each AE pixel, preferably a plurality of light points, e.g., with different wavelengths.

[0049] If at least one light point is provided for each AE pixel, its functionality can be utilized for each AE pixel. If this is possible for more than one color, this applies to each of the respective colors, enabling the aforementioned advantage for color images. For example, the at least one light source can be configured to provide a plurality of light points, each light point being configured to impinge on a predetermined AE area at a predetermined angle of incidence.

[0050] This can be particularly advantageous because the AE can typically be configured to couple out light depending on the angle of incidence.

[0051] An exemplary holographic display system may further comprise an optical element arranged between the at least one light source and the EE for influencing the propagation of the light signal.

[0052] The optical element for influencing the propagation of the light signal can, for example, comprise one or more lenses, an MLA, an acousto-optical deflector (AOD), an acousto-optical modulator (AOM), one or more apertures, a hologram, a grating, a surface light modulator (such as a digital micromirror device (DMD)) and / or combinations thereof and / or can optionally be integrated into the at least one light source. The optical element for influencing the propagation of the light signal can, for example, be temporally switchable, so that the propagation of the light signal is influenced in a first way at a first point in time and in a second way at a point in time, wherein the first way can be different from the second way. For example, the optical element for influencing the propagation of the light signal can be configured at the first point in time to direct a light spot onto a first AE area and / or a sub-area thereof (e.g.a first AE pixel) and at a second time to a second AE area and / or a sub-area thereof (e.g. a second AE pixel), wherein the first AE area and the second area, and thus also their respective sub-areas, may be different.

[0053] In exemplary embodiments, the EE can be configured to redirect the light signal to the AE at least partially via internal reflection within the waveguide. This can be particularly advantageous for minimizing losses on the optical path between the EE and the AE, allowing high light intensities to be applied to the AE, which can particularly improve the brightness and image quality of the generated image.

[0054] The reflections can include, for example, total internal reflections at the front and / or back of the waveguide. However, it is also possible that reflective and / or partially reflective layers and / or coatings are provided for this purpose.

[0055] The EE may, for example, comprise a holographic optical EE and / or the AE may, for example, comprise a holographic optical AE.

[0056] This can make it possible to match the EE particularly well to the AE, allowing high efficiencies in the transmission of the light signal through the display system to be achieved. Fundamentally, HOEs are particularly well-suited for display systems according to the invention because, for example, they can be present as thin layers, which results in advantageously low installation space requirements. This can be particularly advantageous in handheld devices such as mobile phones. These advantages apply to both EE and AE.

[0057] The holographic optical EE and / or the holographic optical AE can be generated, for example, using conventional methods for producing holograms. These methods can, for example, proceed as follows: To produce a hologram, two (coherent) light sources can be used: a first exposure and a second exposure can be superimposed on a medium and interfere there, so that the intensity distribution of the two superimposed waves is a function of the phase difference between the two waves. This creates an interference pattern corresponding to the phase information. The medium can, for example, comprise a photographic plate that chemically reacts, e.g., by blackening, to the intensity distribution on the photographic plate resulting from the interference of the first and second exposure, so that the interference pattern is inscribed in the photographic plate, creating a hologram.Blackening can occur at sites of constructive interference, while no blackening occurs at sites of destructive interference. If the hologram thus inscribed is illuminated with a reference wave identical to the first exposure, the original wave field is reconstructed from the interference pattern stored in the hologram. That is, the pattern written into the medium diffracts the light of the reference wave so that its beam direction corresponds to the direction of the light from the second exposure.

[0058] The EE can, for example, be configured to redirect a first light spot of the light signal, which can be applied to a first predetermined zone of the EE and / or can be applied to the EE at a first predetermined angle, to a first predetermined zone of the AE and to redirect a second light spot of the light signal, which can be applied to a second predetermined zone of the EE and / or can be applied to the EE at a second predetermined angle, to a second predetermined zone of the AE.

[0059] This can provide a beneficial mechanism for redirecting the light signal from the light source to the AE. This can optimize transmission efficiencies within the display system and thus improve image quality.

[0060] The first and / or second zone of the AE can comprise one or more AE areas and / or one or more AE pixels.

[0061] In exemplary embodiments, the EE and / or the AE may comprise an RGB hologram.

[0062] This can lead to an improvement in the quality of color images, especially when properly coordinated with the light source. Color images can be defined as images with at least two different colors.

[0063] The EE and / or AE can, for example, comprise an RGB hologram, which can be described, for example, by means of corresponding RGB exposure. Furthermore, the corresponding RGB exposure can correspond to the colors of the RGB light signal, e.g. insofar as the wavelengths of the light signal at least partially coincide with the wavelengths of the RGB exposure and / or with the wavelengths of the diffraction efficiency maxima of the EE and / or the AE (defined by a wavelength at which the light is most efficiently coupled in or out of the EE and / or AE) (e.g. insofar as the wavelength maxima of the RGB exposure or the wavelengths of the diffraction efficiency maxima and the light signal differ from one another by 10 nm or less). For example, “red” (R) can lie in the spectral range from 635 nm to 770 nm, “green” (G) in the spectral range from 520 nm to 565 nm, and / or “blue” (B) in the spectral range from 450 nm to 500 nm. The diffraction efficiency maxima can beby shrinkage and / or expansion relative to the exposure wavelengths. Shrinkage and / or expansion can typically occur, for example, when fixing a hologram (intentionally or unintentionally).

[0064] The EE and / or the AE may comprise a reflection hologram, a transmission hologram, a volume hologram and / or a surface hologram.

[0065] The hologram types mentioned have proven to be particularly efficient and suitable with regard to the installation space requirements.

[0066] For example, a reflection hologram can be a volume hologram or a surface hologram and / or a transmission hologram can be a volume hologram or a surface hologram.

[0067] In exemplary embodiments, the waveguide may have a first and a second surface, which may be substantially opposite one another and / or may preferably extend substantially at least partially parallel to one another.

[0068] Such waveguides include, for example, thin or thick discs, where a disc can be understood as an object that extends (spatially limited) in a flat or curved plane. Such a geometry is not only advantageous for optimizing the use of the waveguide for total internal reflection of the undirected light signal, but the typically flat geometry also makes the display system particularly compatible with many preferred application areas:

[0069] The waveguide (or the described display system) can, for example, be designed or further developed so that it is provided as a functionalized pane (or as a display system) for a vehicle. The vehicle can be a motor vehicle, a truck, an aircraft, a motorized or non-motorized vehicle, or any other vehicle. The pane can be any pane of the vehicle, such as the windshield, a side window, or a rear window. In particular, multiple panes (or display systems) can be provided for a vehicle. Furthermore, a vehicle can be provided with one or more such functionalized panes (or with one or more display systems). Likewise, the waveguide can be applied to conventional 2D screens, for example, televisions, computer screens, screens of handheld devices such as mobile phones, tablets, etc.and / or wearable devices such as watches, glasses, etc.

[0070] The examples mentioned here can have flat and / or at least partially curved surfaces, which can correspond to those used, for example, for the surfaces of a screen, the cover glass of a watch, the lens of a pair of glasses, etc. All of these surfaces can, for example, extend essentially in a two-dimensional (possibly curved) plane and have a thickness perpendicular to the surface that is typically less than the extension of the surface in the two-dimensional plane, wherein the thickness can be essentially constant or at least partially varying.

[0071] Thus, one or more layers forming the surface of, for example, a screen, cover glass and / or spectacle lens can function as a waveguide according to the present invention and / or serve to attach such a waveguide as a separate element. The EE and / or the AE can then be attached to the waveguide, for example. In such examples, the surface does not have to be the outermost layer, but can be provided with one or more further layers (e.g. to protect the surface). In the example of an LED screen, for example, a glass substrate can form the surface (optionally provided with one or more protective layers) that is attached above the LEDs. The glass substrate can form the waveguide to which the EE and / or the AE are attached so that they can interact as described herein.This can be used to create the following overlay for the viewer: The conventional LED screen can display a two-dimensional image, as is known for televisions, computer screens, handheld devices such as mobile phones, tablets, etc. and / or wearable devices such as wristwatches, which the viewer can see through the glass substrate. In addition, a holographic display system as described herein (based on the EE, AE and / or the glass substrate as a waveguide) can create an additional holographic image which the viewer can perceive as superimposed on the two-dimensional image. In the example of spectacles, for example, one or more of the lenses can be provided with a holographic display system, whereby, for example, the lens can act as a waveguide and / or whereby a waveguide can be attached to the lens (e.g. flat).In this example, the image of the wearer's surroundings perceived through the lenses can be overlaid with a holographic image presented by the holographic display system, allowing, for example, seemingly three-dimensional objects to be projected into the wearer's surroundings. The same can be applied to windows (e.g., a vehicle).

[0072] For example, the EE and / or the AE can be attached to the first and / or second surface of the waveguide, respectively.

[0073] The first and second surfaces of the waveguide represent suitable locations for the attachment of the EE and / or the AE. Thus, in addition to its function of transmitting the redirected light signal to the AE, the waveguide can also serve to stabilize the system by providing a stable (common) base for the EE and the AE.

[0074] The EE and / or the AE may each be attached to one or more of the surfaces, for example, and / or directly inscribed thereon. Alternatively or additionally, the EE and / or the AE may be located at least partially within the waveguide. In one example, the holographic display system may further comprise a detector configured to detect a user's gesture in the image and / or an area surrounding the image.

[0075] This can enable particularly natural operation for the user.

[0076] The environment of the image can be limited, for example, by a first and / or a second distance from the display system, e.g., in the perpendicular direction (e.g., the exit normal of an AE) from the AE in the direction of the observer. The first distance can be, for example, between 1 cm and 10 cm. The environment can therefore extend, for example, into the space at least 1 to 10 cm away from the AE. The second distance can be, for example, 50 cm, 100 cm, or more. Thus, the said environment can be limited, for example, by two (e.g., mutually parallel) planes. Laterally to this, the environment can be limited, for example, by a field of view of the AE that opens essentially conically from the AE, i.e., for example, by the maximum opening angle of the field of view of the AE within which the AE can couple out light. This can be, for example, 15°, 30°, 45°, 60°, 75°. 0or more relative to the perpendicular direction from the AE toward the viewer. This allows the display system to detect, for example, contactless gestures for which a user does not have to touch the display system, but can, for example, "touch" the (disembodied) image and / or its surroundings and thus trigger a response from the display system, e.g., provide an input to control the display system.

[0077] In a preferred embodiment, a gesture can be detected when the viewer or user brings a body part (e.g. their hand) and / or a control element, such as a remote control, a joystick and / or a mobile phone, to the spatial position or close to the spatial position at which the 3D image is displayed. The display system can then, for example, be configured to perform an action based at least partially on the gesture and / or the displayed image. In one example, the 3D image could display a first text "Yes" and a second text "No" as a 3D image. If the user touches the text "Yes" with a gesture, e.g. by moving their hand to the spatial position of the text "Yes", an option can be confirmed. If, on the other hand, they select the text "No", for example, the corresponding option could be closed, ended and / or canceled.“Touching” the image may include a gesture in the image and / or in the area surrounding the image.

[0078] For example, a detector and / or an associated control of the display of the display system can be configured as in US 2009 / 0237763 Ai, WO 2023 / 052465 Ai and / or US 2012 / 0050181 Ai.

[0079] The detector may, for example, comprise a light sensor.

[0080] Such a light sensor can, for example, detect a distance (e.g., of a hand performing a gesture) from the display system in the direction perpendicular from the AE to the viewer and / or a positioning (e.g., of a hand performing a gesture) in a plane perpendicular to this direction. Such a light sensor may be particularly suitable for reliably implementing this functionality.

[0081] For example, the detector may be configured to detect light from the generated image.

[0082] For example, the light sensor can detect light deflected, reflected, scattered and / or emitted by a user's hand. This deflected, reflected, scattered and / or emitted light allows conclusions to be drawn (e.g., at least partially based on the color and / or intensity of the reflected light) as to which part of the displayed image an object performing a gesture, e.g., a user's hand, is located in. If the object, e.g., a user's hand, is located in an image area (predominantly) of a first color (e.g., red), the detector can, for example, detect light of the first color (e.g., red) and / or if, for example, a user's hand is located in an image area (predominantly) of a second color (e.g., green), the detector can, for example, detect light of the second color (e.g., green).

[0083] In an exemplary embodiment, the holographic display system can be configured to change the image at least partially based on the gesture. This can enable particularly natural operation for the user, allowing quick and easy interaction with the display system, in particular interactive control of the display system.

[0084] In one example, the AE may comprise a first means configured to at least partially decouple light coupled into the waveguide by the EE from the waveguide, and a second means comprising an MLA and / or acting like an MLA comprising a plurality of predetermined AE regions. The AE and / or the second means of the AE may be at least partially generated by printing, in particular inkjet printing. For example, the lenses of the MLA may correspond to the AE regions and be generated by printing, in particular inkjet printing.

[0085] Inkjet printing can be carried out, for example, as described in Williams, George M., et al. “Three-dimensional gradient index microlens arrays for light-field and holographic imaging and displays.” Applied Optics 62.14 (2023): 3710-3723. Inkjet printing represents a particularly efficient and cost-effective way to reproducibly produce MLAs in high quality. This enables high image quality of the display system to be achieved. It can be particularly advantageous to arrange the first means, for example, between the waveguide and the second means of the AE, for example in embodiments in which the first and second means of the AE comprise thin layers that extend essentially flat and parallel to the waveguide surface to which the AE is attached.

[0086] Likewise, EE and / or AE can also be produced by inkjet printing without division into first and second means.

[0087] Another aspect relates to a method for creating a holographic image, the method comprising: illuminating an optical EE with at least one controllable light source, the EE being configured to at least partially redirect the light signal into a waveguide and to a holographic optical AE, and the illumination being performed such that a holographic image is generated by the AE, based at least partially on the light signal. The method has the advantages described herein with respect to the display system.

[0088] A further aspect relates to a method for producing a holographic display system (e.g. as described herein), the method comprising: providing a waveguide, generating an optical EE on the waveguide, which is configured to redirect light incident on the EE at least partially within the waveguide, and generating an optical AE on the waveguide, which is configured to cooperate with at least one controllable light source such that, upon illumination of the EE with a controllable light signal from the at least one light source, it generates an image based at least partially on the light signal, wherein generating the EE and / or the AE comprises printing (e.g. as described herein) and in particular inkjet printing of the EE and / or the AE.

[0089] Method steps described herein may also be implemented as functionalities of the display system and / or its components, and vice versa. Corresponding computer programs may also be provided that contain instructions for executing the functionalities described herein.

[0090] 4. Description of the characters

[0091] Fig. la shows a schematic of a display system with a “micro lens array” for generating a 3D image.

[0092] Fig. ib shows schematically a display system with several holographic optical elements illuminated by a light source on the side of a viewer.

[0093] Fig. 2 shows a schematic view of a display system with an input coupling element, a waveguide and an output coupling element, wherein the input coupling element is illuminated by a light source.

[0094] Fig. 3a schematically shows how light is coupled out of a waveguide with a reflection hologram attached as an outcoupling element on its outcoupling side. Fig. 3b schematically shows how light is coupled out of a waveguide with a transmission hologram attached as an outcoupling element on its outcoupling side.

[0095] Fig. 3c shows schematically how light is coupled out of a waveguide on whose side opposite the outcoupling side a transmission hologram is attached as an outcoupling element.

[0096] Fig. 3d shows schematically how light is coupled out of a waveguide on whose side opposite the outcoupling side a reflection hologram is attached as an outcoupling element.

[0097] Fig. 4 shows a side view of a first exemplary display system in the xz plane and a front view in the yz plane, wherein the output coupling element is exposed in an angle-dependent manner.

[0098] Fig. 5a shows a side view of a second exemplary display system in the xz plane and a front view in the yz plane, wherein the light signal is influenced by an optional optical element between the light source and the coupling element in such a way that specific sub-areas of the coupling element areas are illuminated.

[0099] Fig. 5b shows a side view of a second exemplary display system in the xz plane and a front view in the yz plane, wherein the input coupling element is configured to apply the light signal from different light sources to different horizontal groups of output coupling element areas.

[0100] Fig. 5c shows a side view of a second exemplary display system in the xz plane and a front view in the yz plane, wherein the input coupling element is configured to apply the light signal from different light sources to different vertical groups of output coupling element regions. Fig. 5d shows a side view of a second exemplary display system in the xz plane and a front view in the yz plane, wherein the input coupling element is configured to apply the light signal from different light sources arranged in a 2D matrix to different output coupling element regions.

[0101] Fig. 5e shows a side view of a second exemplary display system in the xz plane and a front view in the yz plane, wherein the light signal is influenced by an optical element between the light source and the coupling element in a time-dependent manner such that specific coupling element areas are illuminated.

[0102] 5. Detailed description of preferred embodiments

[0103] Fig. 1a schematically shows a display system with an MLA 1300 with a focal plane 1400 for generating a 3D image B1, B2. In the representation of Fig. 1a, the three vertical points illustrate that the display system can comprise additional elements, so that the system can be extended further in the vertical direction.

[0104] The MLA comprises a plurality of lenses 1310, 1320, 1330, 1340 which can be illuminated by the light source 1100, the illumination being in the form of a light signal containing the image information for the image Bi, B2.

[0105] The light source 1100 of the embodiment of Fig. 1a comprises a plurality of individual light sources 1110, 1120, 1130, 1140, each of which may comprise ten vertically spaced-apart devices for emitting a light signal (e.g., LEDs). In the example of Fig. 1a, the emitting devices 1111, 1112 of the first light source 1110, the emitting devices 1123, 1126 of the second light source 1120, the emitting devices 1135, 11310 of the third light source 1130, and the emitting device 1149 of the fourth light source 1140 are activated so that they emit a light signal (e.g., a light point each). The other emitting devices (and their light points) are not active in the example of Fig. 1a, but can be activated at a different time, just as the active emitting devices can be deactivated at a different time. The embodiment of Fig.1a further comprises an optical element 1200 for influencing the propagation of the light signal, as described herein.

[0106] Each light point of the light signal of Fig. 1a has an associated predetermined location on the MLA 1300 and thus a predetermined angle of reflection, so that the image Bi, B2 is generated based thereon.

[0107] Fig. 1a thus shows a display system without waveguides, EE and AE and can thus only be operated via illumination from the rear (in Fig. 1a from the left), which illustrates that such embodiments can entail the disadvantages described herein.

[0108] The light source 1100 and the optical element 1200 can be used in display systems according to the invention as described with reference to Fig. 1a. The display system according to the invention allows the light source 1100 (from the perspective of a viewer of the display system) to no longer have to be arranged behind the AE or the MLA.

[0109] Fig. 1b schematically shows a display system with a plurality of holographic optical elements 1310, 1320, 1330, which together form a holographic optical screen 1300 illuminated by a light source 1100 on the viewer side. The light source 1100 comprises a plurality of individual light sources 1110, 1120, 1130 and is configured essentially the same as the light source 1100 described with reference to Fig. 1a. In the example of Fig. 1b, the emitting elements 1116, 11110, 1124, 1127, 1132, 1134 are active to generate the image B1, B2.

[0110] The light source 1100, including the optical element 1200, in the example shown, is configured to illuminate the holographic optical screen 1300 from the side of the viewer (from the bottom right in Fig. 1b). The holographic optical elements 1310, 1320, 1330 of the embodiment of Fig. 1b are reflection holograms that generate the image B1, B2 on the right side of the holographic optical elements 1310, 1320, 1330, i.e., on the side from which the exposure also hits the holographic optical elements 1310, 1320, 1330.

[0111] The embodiment shown in Fig. 1b does not include an EE or a waveguide, so it may involve the disadvantages described herein. Nevertheless, Fig. 1b can serve to illustrate how holographic optical elements 1310, 1320, 1330 can generate a (holographic) image Bi, B2.

[0112] Fig. 2 schematically shows a display system 10 with an EE 20, a waveguide 30, and an AE 40, wherein the EE 20 is illuminated by a light source 50. The waveguide 30 can comprise the EE 20 and the AE 40.

[0113] Other examples may include display systems 10 having an EE 20, a waveguide 30, and an AE 40, where the EE 20 may be illuminated by two or more light sources.

[0114] Essentially, the one or more light sources of Fig. 2, or of the display systems 10 described herein, can be designed like the light source 1100 of Fig. 1 and Fig. 2, that is to say, for example, can comprise a plurality of individual light sources 1110, 1120, 1130, 1140, which can each comprise a plurality of spaced-apart devices (e.g. LEDs) for emitting a light signal (e.g. a light spot), which can be used analogously to that described with reference to Figs. 1 and 2 to generate the holographic image.

[0115] The waveguide 30 comprises a front side 31 and a back side 32, which run substantially parallel to one another and each have a rectangular shape extending in the vertical direction. In other examples, other shapes are also possible. Thus, the waveguide 30 is substantially cuboid-shaped, wherein the distance between the front side 31 and the back side 32 can be less than the length and / or width of the front side 31 and / or the back side 32. Other waveguide geometries, e.g., wedge-shaped and / or curved waveguides 30, are also applicable to the concept shown in Fig. 2. The light signal applied to the EE 20 is redirected by the EE 20 and, as shown by the two bold black vertical arrows, at least partially transmitted within the waveguide 30, e.g., by reflection at the front side 31 and / or the back side 32, to at least a portion of the AE 40.

[0116] In the example of Fig. 2, the AE 40 comprises five by five (i.e., 25) AE regions arranged in a periodic two-dimensional grid in the yz-plane, one AE region 41 of which is highlighted for illustrative purposes. In the example of Fig. 2, the light signal is redirected from the EE 20 to the AE 40 such that the different AE regions decouple the incident light at different angles, thereby generating the image Bi, B2. In principle, the image can be generated such that the light decoupled from the AE 40 intersects at different points in space, whereby these points in space can be essentially freely controlled with regard to their distance from the AE 40 and their positioning parallel to the AE 40.

[0117] Preferably, the coupling and / or decoupling elements described herein comprise HOEs, the basic functionality of which is illustrated by way of example in Figs. 3a-3d: The light signal coupled into the waveguide 30, represented by the black arrows, is guided in the waveguide 30 by total internal reflection at the sides of the waveguide 30 to the AE 40. The waveguide can be provided at its end face (shown on the right in Figs. 3a-3d) with an absorber 60 configured to absorb the portion of the light signal not coupled out by the AE 40.

[0118] Fig. 3a shows a schematic diagram of how light is coupled out of a waveguide 30, on the output side of which a reflection hologram is attached as an AE 40. In this example, the AE 40 is transparent to the light incident on the AE 40 from the waveguide 30, so that it can enter the AE through the underside of the AE 40, pass through it, and is only reflected at the top of the AE 40. If the light signal then hits the underside of the AE 40 from above, the AE 40 couples the light signal upwards in accordance with its function as a reflection hologram. Fig. 3b shows a schematic diagram of how light is coupled out of a waveguide 30, on the output side of which a transmission hologram is attached as an AE 40. In this example, the AE 40 couples the light signal upwards in accordance with its function as a transmission hologram when the light signal then hits the underside of the AE 40 from below.

[0119] Fig. 3c schematically shows how light is coupled out of a waveguide 30, on the side of which a transmission hologram is mounted as an AE 40 opposite the output side. In this example, the AE 40 is transparent to the light impinging on the AE 40 from the waveguide 30, allowing it to enter the AE 40 through the top of the AE 40, pass through it, and be reflected at the bottom of the AE 40. When the light signal then strikes the top of the AE 40 from above, the AE 40 couples the light signal upwards according to its function as a transmission hologram.

[0120] Fig. 3d schematically shows how light is coupled out of a waveguide 30, on the side opposite the output side of which a reflection hologram is mounted as AE 40. In this example, the AE 40 couples the light signal upward according to its function as a reflection hologram when the light signal then strikes the top side of the AE 40 from above.

[0121] The AE 40 can alternatively be mounted inside the waveguide 30 to the bottom or top, e.g. from the inside on the bottom or top or completely inside the waveguide 30. The AE 40 can also be written directly into the waveguide, e.g. as a relief hologram, and thus be an integral part of its interior, its top and / or its bottom.

[0122] The aspects described with reference to Fig. 3a-3d can be transferred analogously to the AE and / or the EE of display systems described herein.

[0123] Fig. 4-50 show exemplary display systems that essentially have the same basic structure: They comprise an EE 20, a waveguide 30, and an AE 40, where the AE 40 comprises five by five (i.e., 25) AE regions arranged in a periodic two-dimensional grid in the yz-plane and shown as squares. The EE 20 is shown in Fig. 4-56 to redirect the light signal from at least one light source so that it is coupled into the waveguide 30 and from there, possibly via total internal reflection, reaches the AE 40. The central part of the waveguide 30 in the z-direction is not shown for the sake of clarity, as indicated by the three dots in the side view in the xz-plane.

[0124] The details of the respective embodiments of Fig. 4-50 are explained below:

[0125] Essentially, the one or more light sources of Fig. 4-50 can be configured like the light source 1100 of Fig. 1a, 1b and Fig. 2, i.e., for example, comprise a plurality of individual light sources 1110, 1120, 1130, 1140, each of which can comprise a plurality of spaced-apart devices (e.g., LEDs) for emitting a light signal (e.g., a light spot). The light source of Fig. 4-50 can accordingly be configured to apply the controllable light signal emitted by it and / or the light spots to the EE 20 and / or the AE 40 (and / or to one or more AE regions and / or to one or more AE pixels) in such a way that the desired 3D image is generated. The generated image described herein can, in particular, be temporally variable by emitting different light signals at different times, e.g.,by reversibly activating and / or deactivating (LEDs) one or more light sources (and / or individual light points). The EE of the embodiments of Figs. 4-50 can have substantially analogous properties to the AE. In principle, the EE and / or the AE of the embodiments of Figs. 4-5e can comprise, for example, an MLA. The aspects of the embodiments of Figs. 4-50 described herein can be combined with one another.

[0126] Fig. 4 shows a side view of a first exemplary display system in the xz plane and a front view in the yz plane, wherein the AE 40 is exposed depending on the angle. In the example of Fig. 4, the AE 40 comprises several AE regions (shown as gray squares), each of which in turn can comprise several AE pixels (not shown). The display system can have several light sources, of which three light sources 50a, 50b, 50c are shown as examples. The three points between light source 50a and light source 50b and between light source 50b and light source 50c represent that further light sources (not shown) can be present in between. The light sources 50a, 50b, 50c each apply their respective light signal to the EE 20 or a (predetermined) zone thereof. The EE 20 then redirects the light signal from the light sources 50a, 50b, 50c at respective azimuthal angles (in the yz-plane) cpa, cpb, cpc into the waveguide 30 and to the AE 40.

[0127] It can thus generally be provided that one or more (separate) light sources 50a, 50b, 50c are provided, the light signals of which impinge on the EE 20. The light signals from the light sources can each impinge on the EE 20 with a predetermined aperture angle and a predetermined directional vector. The directional vectors of the light signals from different light sources can preferably be different from one another. The aperture angles, however, can be the same and / or different. The light signals from different light sources can each illuminate predetermined zones of the EE 20 that at least partially overlap.

[0128] The EE 20 can be configured to collimate the respective light signals so that they impinge on the AE 40 at a fixed azimuthal angle cpa, cpb, cpc. The azimuthal angles cpa, cpb, cpc of the light signals can be different from one another. In the exemplary illustration in Fig. 4, the EE 20 redirects the light signal applied by the respective light source 50a, 50b, 50c at a predetermined angle (e.g., aperture angle and / or directional vector) onto the EE 20 and / or a zone of the EE 20 at an azimuthal angle cpa, cpb, cpc within the waveguide 30 that depends on the predetermined angle and / or the zone, wherein the predetermined angle and / or the zone of the EE 20 to which the light signal is applied can be the same or different for different light sources 50a, 50b, 50c.

[0129] In the example according to Fig. 4, the deflected light signal from light source 50a impinges on the AE 40 at an azimuthal angle cpa, the deflected light signal from light source 50b impinges on the AE 40 at an azimuthal angle cpb, and the deflected light signal from light source 50c impinges on the AE 40 at an azimuthal angle cpc. In the example of Fig. 4, each of the light sources 50a, 50b, 50c can thus be assigned an azimuthal angle cpa, cpb, cpc, along which the deflected light signal from the respective light source 50a, 50b, 50c propagates in the waveguide plane. The azimuthal angle cpa of a first exemplary light source 50a can be different from the azimuthal angle cpb of a second exemplary light source 50b (as shown in Fig. 4). In the example of Fig. 4, the light signals of the light sources 50a, 50b, 50c can be applied to at least partially superimposed zones of the AE 40, so that, for example,at least two light points from different light sources 50a, 50b, 50c can be directed at at least one AE area at different azimuthal angles cpa, cpb, cpc.

[0130] The side view in the xz-plane shows that the vertical angle (in the xz-plane) 0a, 0b, 0c for the redirected light of all light sources 50a, 50b, 50c emanating from the EE 20 is the same in the embodiment of Fig. 4. In other examples, this angle may differ for the light sources 50a, 50b, 50c.

[0131] In the display system of Fig. 4, AE pixels of the AE regions of the AE 40 are configured to output light signals of different angles of incidence cpa, cpb, cpc in different directions, i.e., with different angles of reflection, as described herein. For this purpose, at least one AE region (shown as gray squares) of the exemplary embodiment can comprise a plurality of AE pixels (not shown) that, upon receiving a light spot with a predetermined angle of incidence, are configured to output said spot at a predetermined angle of reflection. For example, a plurality of (preferably all) AE regions can be constructed substantially identically with regard to their AE pixels. As described herein, each light source 50a, 50b, 50c of the exemplary embodiment can be assigned an azimuthal angle cpa, cpb, cpc. The deflected light signal hits the AE 40, an associated AE area and / or AE pixel at the corresponding angle of the respective light source 50a, 50b, 50c.As a result, a first of the plurality of AE pixels may be transparent to light of a first predetermined angle of incidence (e.g., a first light source 50a) and output light of a second predetermined angle of incidence (e.g., a second light source 50b). A second of the plurality of AE pixels, e.g., of the same AE region, may output light of the first predetermined angle of incidence and preferably be transparent to light of the second predetermined angle of incidence.

[0132] While the embodiment of Fig. 4 enables small AE areas to be realized, the efficiency of the light extraction may be reduced, e.g. because light strikes AE areas that are not configured to extract light from the corresponding angle. This may, for example, reduce the light intensity of the generated image. For example, a light spot of the first light source 50a may be configured to strike multiple AE pixels, but only one of these AE pixels is "responsive." The light spot can therefore have a larger area at the AE without this having a detrimental effect on the imaging quality, except that only part of the light spot is actually available for imaging.

[0133] If, for example, one is able to precisely control the AE pixels and / or AE areas (e.g., a light point can also be limited to an AE pixel with a relatively small area), one can, for example, dispense with the angle dependence of the AE areas described in relation to Fig. 4 and / or, analogous to the concept in Figs. 1 and 2, specifically apply individual light points, e.g., of any color, to individual AE pixels and / or AE areas. This is explained using Figs. 5a-5e as an example:

[0134] Fig. 5a shows a side view of a second exemplary display system in the xz plane and a frontal view in the yz plane, wherein the light signal is influenced by an optional optical element 70 between the light source 50 and the EE 20 such that specific subregions 41a, 41b, 41c, 41id, 41e, 41f, 41g, 41h, 41ii, e.g., AE pixels, of the AE regions 41 of the AE 40 are illuminated. In other embodiments, the optional optical element 70 can also be integrated into the light sources 50a, 50b, 50c. Essentially, the optional optical element 70 can be configured to influence the light signal (e.g., spatially and / or temporally variable) such that the light points of the light signal can be applied separately from one another and / or specifically to the AE pixels 41a, 41b, 41c, 4id, 4ie, 4if, 41g, 41h, 4ii, thus illuminating them.For this purpose, the optional optical element 70 can, for example, comprise one or more lenses and / or be designed as described herein. If the light source 50a, 50b, 50c has, for example, a plurality of LEDs (or other sources for, for example, light points), the optional optical element 70 can, for example, influence the light emitted by an LED (or another source) such that the light hits exactly one AE pixel 41a, 41b, 41c, 4id, 4ie, 4if, 41g, 41h, 4ii when the LED is switched on and no light point hits the corresponding AE pixel 41a, 41b, 41c, 4id, 4ie, 4if, 41g, 41h, 4ii when the corresponding LED is switched off. Because the optical element 70 enables such a high degree of control, the individual subregions or AE pixels 41a, 41b, 41c, 41id, 41e, 41f, 41g, 41h, 41ii can be specifically controlled. These can be configured, as described herein, to couple the light signal in different directions to generate the image.In some embodiments, one or more light sources 50a, 50b, 50c can therefore be provided, the number of light points of which corresponds to the number of AE pixels of the AE 40. In principle, the at least one light source 50a, 50b, 50c, e.g., together with the optical element 70, can be configured to provide at least one light point for each AE pixel 41a, 41b, 41c, 41id, 41e, 41f, 41g, 41h, 41i, preferably several light points with different wavelengths, wherein the light point can be provided, e.g., so precisely that the light point only strikes exactly one pixel (and e.g., no neighboring AE pixels and / or neighboring AE regions).

[0135] As in Fig. 4, the side view in the xz plane in Fig. 5a also shows that the vertical angle (in the xz plane) 0a, 0b, 0c for the redirected light from all light sources 50a, 50b, 50c is the same in the embodiment of Fig. 5a. In other examples, this angle may differ for the light sources 50a, 50b, 50c and / or the optical element 70 may be configured to direct light signals from only one light source to the different AE areas and / or AE pixels.

[0136] Each light source 50a, 50b, 50c can, for example, be configured to apply a light spot of its light signal to one or more AE areas 41. By controlling the (controllable) light source(s) 50a, 50b, 50c and / or the optical element 70, the light spot can then be applied specifically to a group of AE 40, an AE area 41 and / or an AE pixel 41a, 41b, 41c, 41id, 41e, 41f, 41g, 41h, 41ii. As a result, for example,by the deflection by the EE 20 and the control of the light source(s) 50a, 50b, 50c and / or the optical element 70, at a first point in time, one or more first light points are applied to one or more first AE pixels of the AE 40, and at a second point in time, one or more second light points are applied to one or more second AE pixels of the AE 40, wherein the first and second one or more AE pixels differ in at least one AE pixel and / or wherein at least a first and a second light point differ in their intensity and / or color (or wavelength). Specifically, this means that the image displayed at the first point in time differs from the image displayed at the second point in time, at least partially from at least one viewing direction of the viewer.

[0137] In order to realize a corresponding control of the AE pixels and / or AE areas, a geometric relationship between light source 50a, 50b, 50c, EE 20 and / or AE 40 can be used, as shown for example in Fig. 5b-5e.

[0138] Fig. 5b shows a side view of a second exemplary display system in the xz plane and a front view in the yz plane, wherein the EE 20 is configured to apply the light signal from different light sources 50a, 50b, 50c to different horizontally (parallel to the y-axis) extending groups of AE areas 40a, 40b, 40c. In detail, the light signal from the light source 50a is applied to the group of AE areas 40a, the light signal from the light source 50b is applied to the group of AE areas 40b, and the light signal from the light source 50c is applied to the group of AE areas 40c. For this purpose (as shown in Fig. 5b), the light signal from the light sources 50a, 50b, 50c can be applied to the EE 20 or a part thereof at different angles. The EE 20 of the embodiment of Fig.5b is thus configured to redirect a first light spot of the light signal, which is applied to the EE 20 at a first predetermined angle, to a first predetermined zone of the AE 40 and to redirect a second light spot of the light signal, which is applied to the EE 20 at a second predetermined angle, to a second predetermined zone of the AE 40. Specifically, the light spots of the light source 50a can be applied, for example, to a lower, horizontally extending group of AE regions 40a, which (as in the illustrated example) can comprise, for example, five square AE regions. The light spots of the light source 50b can be applied to a middle, horizontally extending group of AE regions 40b, which (as in the illustrated example) can comprise, for example, five square AE regions. The light spots of the light source 50c can be applied to an upper, horizontally extending group of AE regions 40c, which (as in the illustrated example) can comprise, for example,five square AE areas. In Fig. 5b, the groups of AE areas 40a, 40b, and 40c are different. For example, horizontally adjacent light sources can each illuminate a group of horizontally adjacent AE areas.

[0139] For this purpose, the EE 20 is configured to couple the light signal from the light sources 50a, 50b, 50c into the waveguide 30 at different vertical angles (in the xz plane) 0a, 0b, 0c and to redirect it to the AE 40.

[0140] As the frontal view in the yz-plane shows, the azimuthal angle (in the yz-plane) cpa, cpb, cpc for the redirected light of all light sources 50a, 50b, 50c can be the same in the embodiment of Fig. 5b. In other examples, this angle can be different for the light sources 50a, 50b, 50c.

[0141] By controlling the (controllable) light source(s) (e.g. their light points) and / or an optional optical element (not shown), the illumination of the AE 40 can be variably adjusted over time and / or space. For example, at a first point in time, the light source 50a can (at least partially) illuminate the group of AE areas 40a in the bottom row of the AE 40. At a second point in time, the light source 50a can be controlled differently and / or the optional optical element can influence the light signal such that a different group of AE areas is (at least partially) illuminated (e.g. the second row from the bottom of the AE 40) and / or a different subset of the group of AE areas 40a is illuminated.

[0142] Fig. 5c shows a side view of a second exemplary display system in the xz plane and a front view in the yz plane, wherein the EE 20 is configured to apply the light signal of different light sources 50a, 50b, 50c to different vertical groups of AE areas 40a, 40b, 40c.

[0143] The side view in the xz-plane shows that the vertical angle (in the xz-plane) α, α, αc for the deflected light of all light sources 50a, 50b, 50c is the same in the embodiment of Fig. 5c. In other examples, this angle may differ for the light sources 50a, 50b, 50c. The front view in the yz-plane shows that the azimuthal angle (in the yz-plane) cpa, cpb, cpc for the deflected light of all light sources 50a, 50b, 50c is the same in the embodiment of Fig. 5c. In other examples, this angle may differ for the light sources 50a, 50b, 50c.

[0144] However, the light sources 50a, 50b, 50c illuminate different areas of the EE 20, so that the light signal from the different light sources 50a, 50b, 50c can be applied to different vertically (parallel to the z-axis) extended groups of AE areas 40a, 40b, 40c. In detail, the light signal from the light source 50a is applied to the group of AE areas 40a, the light signal from the light source 50b is applied to the group of AE areas 40b, and the light signal from the light source 50c is applied to the group of AE areas 40c. For this purpose (as shown in Fig. 5c), the light signal from the light sources 50a, 50b, 50c can be applied to different zones of the EE 20. The EE 20 of the embodiment of Fig.5c is thus configured to redirect a first light spot of the light signal, which is applied to a first predetermined zone of the EE 20, to a first predetermined zone of the AE 40 and to redirect a second light spot of the light signal, which is applied to a second predetermined zone of the EE 20, to a second predetermined zone of the AE 40. Specifically, the light spots of the light source 50a can be applied, for example, to a left, vertically extending group of AE regions 40a, which (as in the illustrated example) can comprise, for example, five square AE regions. The light spots of the light source 50b can be applied to a central, vertically extending group of AE regions 40b, which (as in the illustrated example) can comprise, for example, five square AE regions. The light spots of the light source 50c can be applied to a right, vertically extending group of AE regions 40c, which (as in the illustrated example) can comprise, for example,five square AE areas. In Fig. 5c, the groups of AE areas 40a, 40b, and 40c are different. For example, horizontally adjacent light sources can each illuminate a group of vertically adjacent AE areas.

[0145] By controlling the (controllable) light source(s) (e.g. their light points) and / or an optional optical element (not shown), the actual illumination of the AE 40 can be variably adjusted over time and / or space. For example, at a first point in time, the light source 50a can (at least partially) illuminate the group of AE areas 40a in the left column of the AE 40. At a second point in time, the light source 50a can be controlled differently and / or the optional optical element can influence the light signal such that a different group of AE areas is (at least partially) illuminated (e.g. the second column from the left of the AE 40) and / or a different subset of the group of AE areas 40a is illuminated.

[0146] Fig. 5d shows a side view of a second exemplary display system in the xz plane and a front view in the yz plane, wherein the EE 20 is configured to apply the light signal of various light sources 50a, 50b, 50c (reference numerals only for the light sources active in the example shown that emit a light signal), which are arranged in a 2D matrix, to different AE areas.

[0147] Due to the 2D arrangement of the light sources in Fig. 5d, each light source can be assigned an AE area, so that the light signal of the light source 50a is applied to the AE area 41a, the light signal of the light source 50b is applied to the AE area 41b and the light signal of the light source 50c is applied to the AE area 41c.

[0148] Essentially, the embodiments of Fig. 5b-5d show that the at least one (controllable) light source can be spatially related to the AE area, onto which the respective light source can apply a light point of its light signal. In these examples, in Fig. 5b, a group of AE areas is assigned to a light source in each row. This means that a light source illuminates a row of AE areas. In Fig. 5c, a group of AE areas is assigned to a light source in each column. This means that a light source illuminates a column of AE areas. In Fig. 5d, an AE area is assigned to a light source in each column. This means that a light source can illuminate an AE area. Within this exemplary assignment, for example, an AE area can be controlled by selecting the associated light source. A more precise control of a sub-area of ​​the respective AE area, e.g.of an AE pixel can be enabled, for example, as described herein, by controlling the (controllable) light source(s) (e.g. their light points) and / or an optical element. In detail, by controlling the (controllable) light source(s) (e.g. their light points) and / or an optional optical element (not shown), the actual illumination of the AE 40 can be adjusted in a temporally and / or spatially variably manner: For example, at a first point in time, the light source 50a can illuminate the AE area 41a (at least partially). At a second point in time, the light source 50a can be controlled differently and / or the optional optical element can influence the light signal such that a different AE area is (at least partially) illuminated (e.g. the AE area to the right of the AE area 41a) and / or a different subset of the AE area 41a is illuminated.

[0149] Fig. 5e shows a side view of a second exemplary display system in the xz plane and a front view in the yz plane, wherein the light signal is influenced by an optical element 70 between the light source 50 and the EE 20 in a time-dependent manner so that targeted AE areas can be illuminated.

[0150] The light sources 50a, 50b, 50c can illuminate different areas of the EE 20, so that the latter can direct the light signal from the different light sources 50a, 50b, 50c onto different AE areas 41a, 1; 41a, x; 41a, N; 41b, 1; 41b, x; 41b, N; 41c, 1; 41c, x;

[0151] 41c, N (1 < x < N). In detail, the light signal from the light source 50a can be applied to the AE regions 41a, 1; 41a, x; 41a, N, the light signal from the light source 50b can be applied to the AE regions 41b, 1; 41b, x; 41b, N, and the light signal from the light source 50c can be applied to the AE regions 41c, 1; 41c, x; 41c, N.

[0152] In addition, the optical element 70 can be configured to influence the vertical angle (in the xz plane) 0a, 0b, 0c of the light signal over time such that different AE areas can be illuminated at different times: For example, at a first time, the light source 50a can illuminate the AE area 41a, 1, the light source 50b can illuminate the AE area 41b, 1 and the light source 50a can illuminate the AE area 41b, 1. At a second time, for example, the light source 50a can illuminate the AE area 41a, x, the light source 50b can illuminate the AE area 41b, x and the light source 50a can illuminate the AE area 41b, x. At a third point in time, for example, the light source 50a can illuminate the AE area 41a, N, the light source 50b can illuminate the AE area 41b, N, and the light source 50a can illuminate the AE area 41b, N. Here, 1 < x < N, so that any area of ​​the AE 40 can be illuminated. For example, in comparison to the embodiment of Fig.5d, the functionality of the display system can be enabled with fewer light sources 50a, 50b, 50c. The concept illustrated in Fig. 5e of spatially and / or temporally influencing the light signal of the light sources 50a, 50b, 50c, for example, by means of the optical element 70, can be transferred accordingly to the other embodiments described herein.

[0153] The light sources 50a, 50b, 50c of the embodiments of Figs. 5b-5e can be configured so that a light spot specifically illuminates each AE pixel. Alternatively or additionally, an optical element, such as that described with reference to the optical element 70 of Fig. 5a, can also be provided for this purpose.

Claims

Claims 1. A holographic display system (10) comprising: a waveguide (30); an optical input coupling element, EE (20); and an optical output coupling element, AE (40); wherein the EE (20) is configured to redirect light incident on the EE (20) via the waveguide (30) to the optical AE (40); and wherein the optical AE (40) is configured to cooperate with at least one controllable light source (50) such that, upon illumination of the EE (20) with a controllable light signal from the at least one light source (50), it generates an image (Bi, B2) based at least partially on the light signal.

2. Holographic display system (10) according to claim 1 with the at least one controllable light source (50) for emitting the controllable light signal.

3. Holographic display system (10) according to claim 1 or 2, wherein the AE (40) comprises a plurality of predetermined AE regions (41); wherein the controllable light signal comprises a plurality of controllable light points; and wherein the at least one light source (50) is configured such that at least one light point, preferably a plurality of light points with different wavelengths, can be directed onto each predetermined AE region (41).

4. Holographic display system (10) according to claim 3, wherein the AE areas (41) are arranged periodically on the AE (40), preferably in a two-dimensional grid.

5. Holographic display system (10) according to claim 3 or 4, wherein at least one of the predetermined AE areas (41) is configured to receive a plurality of light points at different positions and / or at different angles of incidence, so that these can be displayed in dependence on the position and / or the angle of incidence with different angles of reflection.

6. Holographic display system (10) according to claim 5, wherein the at least one predetermined AE region (41) enables angles of emergence that substantially span an image angle range of the display system (10), and wherein the at least one predetermined AE region (41) is a local region of the AE (40).

7. Holographic display system (10) according to claim 6, wherein the at least one predetermined AE range (41) enables the angles of emergence for at least two wavelengths.

8. Holographic display system (10) according to one of claims 3 - 7, wherein the at least one predetermined AE region (41) comprises a plurality of AE pixels (41a) which, upon receiving a light spot with a predetermined angle of incidence, are configured to couple said spot out at a predetermined angle of reflection, wherein preferably the number of AE pixels (41a) corresponds to the number of possible different angles of reflection of the AE region (41).

9. The holographic display system (10) of claim 8, wherein a first of the plurality of AE pixels (41a) is transparent to light of a first predetermined angle of incidence and couples out light of a second predetermined angle of incidence, and wherein a second of the plurality of AE pixels (41a) couples out light of the first predetermined angle of incidence and is preferably transparent to light of the second predetermined angle of incidence.

10. Holographic display system (10) according to claim 8 or 9, wherein the at least one predetermined AE region (41) comprises at least 14400 AE pixels (41a), preferably at least 28800 AE pixels, more preferably at least 57600 AE pixels (41a) or most preferably at least 307200 AE pixels (41a).

11. Holographic display system (10) according to one of claims 8 - 10, wherein the at least one light source (50) is configured to provide at least one light spot for each AE pixel (41a), preferably a plurality of light spots with different wavelengths.

12. Holographic display system (10) according to one of claims 3 - 11, wherein the at least one light source (50) is configured to provide a plurality of light spots, each light spot being configured to impinge on a predetermined AE area (41) at a predetermined angle of incidence.

13. Holographic display system (10) according to one of claims 1 - 12, further comprising an optical element (70) arranged between the at least one light source (50) and the EE (20) for influencing the propagation of the light signal.

14. Holographic display system (10) according to one of claims 1 - 13, wherein the EE (20) is configured to redirect the light signal at least partially via internal reflection within the waveguide (30) to the AE (40).

15. Holographic display system (10) according to one of claims 1 - 14, wherein the EE (20) comprises a holographic optical EE (20) and / or the optical AE (40) comprises a holographic optical AE (40).

16. Holographic display system (10) according to one of claims 1 - 15, wherein the EE (20) is configured to redirect a first light spot of the light signal, which is applied to a first predetermined zone of the EE (20) and / or is applied to the EE (20) at a first predetermined angle, to a first predetermined zone of the AE (40) and to redirect a second light spot of the light signal, which is applied to a second predetermined zone of the EE (20) and / or is applied to the EE (20) at a second predetermined angle, to a second predetermined zone of the AE (40). 17- Holographic display system (10) according to one of claims 1-16, wherein the EE (20) and / or the AE (40) comprises an RGB hologram.

18. Holographic display system (10) according to one of claims 1 - 17, wherein the EE (20) and / or the AE (40) comprises a reflection hologram, a transmission hologram, a volume hologram and / or an area hologram.

19. Holographic display system (10) according to one of claims 1-18, wherein the waveguide (30) has a first and a second surface (31, 32) which are substantially opposite one another and preferably extend substantially at least partially parallel to one another.

20. Holographic display system (10) according to claim 19, wherein the EE (20) and the AE (40) are each attached to the first and / or second surface (31, 32) of the waveguide (30).

21. Holographic display system (10) according to one of claims 1-20, further comprising a detector configured to detect a gesture of a user in the image (Bi, B2) and / or an environment of the image.

22. The holographic display system (10) of claim 21, wherein the detector comprises a light sensor.

23. Holographic display system (10) according to claim 21 or 22, wherein the detector is arranged to detect light of the generated image (Bi, B2).

24. Holographic display system (10) according to one of claims 21 - 23, wherein the holographic display system (10) is configured to change the image (Bi, B2) at least partially based on the gesture.

25. Holographic display system (10) according to one of claims 1 - 24, wherein the AE (40) comprises a first means arranged to be received by the EE (20) in to at least partially decouple light coupled into the waveguide (30) from the waveguide (30), and comprises a second means comprising a micro lens array comprising a plurality of predetermined AE regions (41); and wherein preferably the first means of the AE (40) and / or the second means of the AE (40) is / are at least partially produced by inkjet printing.

26. A method for creating a holographic image (Bi, B2), the method comprising: Illumination of an optical input coupling element, EE, (20) with at least one controllable light source (50); wherein the EE (20) is configured to redirect the light signal at least partially into a waveguide (30) and to an optical output coupling element, AE, (40); and wherein the illumination is carried out such that a holographic image (Bi, B2) is generated by the AE (40), at least partially based on the light signal.

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