Display device and method for generating large field of view

Abstract

The invention relates to a display device for representing two-dimensional and / or three-dimensional objects or scenes. The display device comprises at least one illumination device for substantially emitting coherent light, at least one spatial light modulation device for modulating the incident light and at least one optical system. The at least one optical system is provided for multiple imaging of the at least one spatial light modulation device and for generating a virtual viewing window depending on the number of images of the at least one spatial light modulation device. The individual images of the at least one spatial light modulation device are combined with each other as segments and form a field of view. The field of view comprises at least one high-resolution holographic segment and at least one low-resolution holographic segment.

Description

[0001] This invention relates to a display device for representing two-dimensional and / or three-dimensional objects or scenes. Furthermore, this invention also relates to a method for generating a large field of view using such a display device.

[0002] In two-dimensional or three-dimensional displays or display devices, generating a large field of view or wide viewing angle is particularly advantageous for good user convenience.

[0003] However, in holographic displays, a large field of view typically requires a very large number of pixels in the spatial light modulation device, or alternatively, a very high frame rate of the spatial light modulation device when different regions of the field of view are intended to be represented in chronological order.

[0004] For display devices or displays related to the representation of objects or scenes, they generate virtual viewing windows through which the represented scene or object can be observed. This means that, for example, to generate a 7mm virtual viewing window or visible area for blue light with a wavelength of 460nm, approximately 250 complex-valued pixels per degree of field of view or viewing angle are required, for example, in a spatial light modulation device. Even using a spatial light modulation device with high resolution of 4000×2000 pixels and only phase modulation, and assuming that every two phase pixels are combined to form a complex-valued macro-pixel, there are still approximately 2000×2000 complex-valued macro-pixels, and only a vertical 8 degrees × horizontal 8 degrees of field of view can be generated.

[0005] Holographic display devices are particularly based on the diffraction effect at the pixel aperture of spatial light modulation devices and the interference of coherent light emitted by a light source. However, some important conditions for using geometric optics can be formulated and defined for holographic display devices that generate virtual viewing windows.

[0006] On the one hand, the path of the illumination beam in the display device is important in this case. It is used, among other things, to generate a virtual viewing window. The spatial light modulation device is illuminated by an illumination device containing at least one real or virtual light source. Then, light from different pixels of the spatial light modulator must be directed into the virtual viewing window, respectively. For this purpose, at least one light source of the illumination device illuminating the spatial light modulation device is typically imaged onto the observer plane containing the virtual viewing window. This imaging of the light source is, for example, performed at the center of the virtual viewing window. In the case of illuminating the spatial light modulation device with a plane wave corresponding to a light source at infinity, light emitted perpendicularly from different pixels of the spatial light modulation device is focused into the center of the virtual viewing window. Then, light emitted non-perpendicularly from different pixels of the spatial light modulation device, but at the same diffraction angle, is also focused at the same position in the virtual viewing window. However, in general, the virtual viewing window can also be laterally shifted relative to the image of at least one light source; for example, the position of the image of at least one light source can coincide with the left or right edge of the viewing window.

[0007] On the other hand, besides direct-view displays, the imaging beam path is crucial in holographic display devices. In head-mounted displays (HMDs), small spatial light modulation devices generate an overall magnified image. This is typically a virtual image, seen by the viewer at a distance greater than the spatial light modulation device itself. Individual pixels of the spatial light modulation device are usually magnified for imaging.

[0008] A holographic direct-view display that generates a virtual viewing window has an illumination beam path. The display includes an illumination device with at least one light source. For example, the illumination device is configured as a backlight that generates a collimated plane wavefront that illuminates a spatial light modulation device. The collimated wavefront corresponds to a virtual light source that illuminates the spatial light modulation device from infinity. However, a diverging or converging wavefront can also be used to illuminate the spatial light modulation device, corresponding to a real or virtual light source at a finite distance in front of or behind the spatial light modulation device. A field lens focuses the light from the spatial light modulation device onto the location of the virtual viewing window. If a hologram is not written into the spatial light modulation device, a periodic repetition of the image of the light source and images of higher diffraction orders is formed in the observer plane. If a suitable hologram is written into the spatial light modulation device, a virtual viewing window is formed near the zeroth diffraction order. This is described below as the virtual viewing window being located in the plane of the light source image. In a holographic direct-view display, the field lens that generates the light source image is typically located near the spatial light modulation device. An observer sees the spatial light modulation device at its actual distance, but no imaging of the spatial light modulation device occurs. Therefore, there is no imaging beam path.

[0009] In other holographic display devices (e.g., head-mounted displays (HMDs), head-up displays (HUDs), or other projection displays), an additional imaging beam path may be provided, as already briefly mentioned. In these display devices, a real or virtual image of the spatial light modulation device is generated, which the observer sees. Furthermore, the illumination beam path used to generate the virtual viewing window is important. Therefore, the beam path, the illumination beam path, and the imaging beam path are all important in this case.

[0010] Similarly, in other display devices (e.g., stereoscopic displays), there may be both an imaging beam path and an illumination beam path. A stereoscopic display device for generating an optimal light spot may, for example, include an optical arrangement similar to that of the holographic display device, namely a spatial light modulation device and collimated illumination by a field lens, but may also have additional components, such as a scattering element with a defined scattering angle. If the scattering element is removed from the display device, the field lens will thus generate a light source image in the plane of the optimal light spot. By using the scattering element, light is correspondingly distributed on an expanded optimal light spot that is narrower than the observer's interpupillary distance. However, the illumination beam path is important so that a complete stereoscopic image can be seen without vignetting. In this case, the three-dimensional stereoscopic display device may also have an imaging beam path, which the spatial light modulation device uses to image at a specific distance from the observer.

[0011] In holographic display devices, the typical size of sub-holograms of a hologram calculated from a three-dimensional scene depends on the position of the three-dimensional scene in space relative to the plane or image plane of the spatial light modulation device. For example, when the scene is located in front of the plane or image plane of the spatial light modulation device from the observer's perspective, a sub-hologram with a large size is produced. However, large sub-holograms increase the computational workload during hologram calculation. A method is disclosed in the applicant's patent document WO2016 / 156287A1, which reduces the computational workload by arithmetically introducing a virtual plane of the spatial light modulation device. However, as an alternative, it is also desirable to select the optical system in such a way that the image plane of the spatial light modulation device is formed in an advantageous position, thus allowing the calculation of holograms with small sub-holograms.

[0012] In an optional configuration of the holographic display device that generates a virtual viewing window, imaging from the spatial light modulation device into the virtual observer plane can also be implemented. For this purpose, if a physical screen is not available, a screen of the type used for holographic representation of the 3D scene, or alternatively a reference plane, is provided in the Fourier plane of the spatial light modulation device (i.e., the image plane of the light source). Therefore, in this display device, there are also imaging beam paths and illumination beam paths. However, the importance of the hologram plane and the observer plane is interchanged. The virtual viewing window is then located in the image plane of the spatial light modulation device and is therefore associated with the imaging beam path. The hologram, or the reference plane used to calculate the hologram from the 3D scene, is located in the Fourier plane of the spatial light modulation device and is therefore associated with the illumination beam path.

[0013] If a properly calculated hologram is written into a spatial light modulation device and the display device includes an illumination device that generates sufficiently coherent light, a two-dimensional image is generated in the Fourier plane of the spatial light modulation device by the Fourier transform of the hologram. Additional scattering elements can be located in this plane. If an image of the spatial light modulation device is generated in the observer plane without scattering elements, an optimal light spot will be formed instead of using scattering elements. In this case, the size of the optimal light spot depends on the scattering angle of the scattering elements. This arrangement can be used, for example, in a head-up display (HUD).

[0014] The following explanation is primarily intended to address the case where a virtual viewing window or optimal spot exists in the plane of the light source image. However, the statements made can also be applied to embodiments in which the spatial light modulation device is imaged into a virtual viewing window by corresponding interchanges of the planes and Fourier planes of the imaging beam path and the illumination beam path or the spatial light modulation device. Therefore, the invention is not limited to the case of having a virtual viewing window or optimal spot in the plane of the light source image.

[0015] WO 2012 / 062681 A1 discloses a holographic display with a virtual viewing window. A segmented representation of the field of view is described. This field of view can be expanded by representing multiple segments of the field of view in temporal order using a spatial light modulator and a suitable optical system. A scene or object can be represented within this segmented field of view, which is then visible from the virtual viewing window. However, the temporal generation of the individual segments increases the frame rate requirements on the spatial light modulation device.

[0016] At the center of the retina in the fovea of ​​the human eye, humans can typically achieve a visible angular resolution of 1 arcminute. For example, the letter "E," when its size is 5 arcminutes, is perceived by a person with 100% vision. The three bars (dark areas) of the letter "E" each occupy one arcminute, and the two spaces in the middle of the letter "E" (bright areas) each occupy one arcminute. Therefore, a resolution of 60 pixels per degree of visual field, or a resolution of 30 cycles per degree of visual field (each cycle containing adjacent black and white dots respectively), corresponds to human resolving power. However, in the peripheral regions of the retina, the resolution is much lower.

[0017] Therefore, the resolution of the human retina is only high within a small angular range. For example, this fact has been used in "retinal concavity rendering," a graphics rendering technique that uses an eye-tracking system to reduce the workload during rendering by lowering the image quality in the peripheral field of view. This means that computation is performed at full resolution only in the central region of the image, while regions at the edges are computed at low resolution. Thus, this implies that a representation of a scene is computed at high resolution only if the observer's eye is fixed at that instant, and at a lower resolution outside the central field of view.

[0018] For this purpose, for example, eye tracking can be used to detect where an observer is looking. This "retinal concave rendering" can also be used for holographic calculations. However, it only significantly affects the required computational power, without affecting the number of pixels or the required frame rate of the spatial light modulation device used.

[0019] For example, WO 2012 / 062681 A1 also describes the merging of holographic and stereoscopic representations in a holographic head-mounted display (HMD) with segmented or tiled representations of a portion of a viewpoint or field of view. In this case, tiling of the field of view in the holographic HMD is referred to as segmented multiple imaging, where, in one embodiment, a portion of the segment is generated holographically and another portion of the segment is generated stereoscopically. In this regard, the following is disclosed: “Improved embodiments—segmenting image content temporally and / or spatially in an extended observer space—represent a combination of incoherent 2D representations and / or stereoscopic 3D representations with dynamically encoded at least partially coherent holographic 3D representations in a variable solid angle. For example, in a simple embodiment—for the sake of simplification, only the vertical observer angle will be considered in this case—a central angle range of (0 to ±13)°, i.e., 26°, (which corresponds to the central segment of the SLM in the field prism plane) is generated by dynamically encoded holographic 3D. The range of +13 to +39° above and below the central angle range…” Angle ranges of ° and -13 to -39° can be generated using 2D or 3D stereoscopic representation. The principle is that in a natural environment, a user can only see a limited solid angle with high resolution and a highly perceptible 3D impression. If the user has access to a very large solid angle, then features with high resolution and a highly perceptible 3D impression exist only in sub-regions of the overall solid angle. This is the area where the user can focus their attention. Since this area can move in space as the user's eyes move, it is also advantageous to move the spatial area represented with strong focus and 3D features. For this purpose, detection of eye position and / or gaze direction will be provided.

[0020] One problem with stereoscopic 3D representation is the convergence-accommodation conflict. This conflict occurs particularly in stereoscopic display devices or monitors when an observer focuses their attention on the display surface or the surface of a spatial light modulation device in order to perceive it clearly. The difference between two stereoscopic images suggests that a 3D object should be seen in front of or behind the display surface. In this case, the eye focuses on the viewing distance of these objects from the display surface. The object is thus fixed and should be perceived clearly. However, the object is not actually located at a certain distance from the display surface, so the observer no longer sees it clearly when it is fixed. Therefore, observers often experience headaches or other kinds of discomfort when viewing stereoscopic scenes or objects.

[0021] However, these negative effects can be overcome when using holographic display devices or displays.

[0022] Because perceptible depth resolution decreases with decreasing lateral resolution, convergence-accommodation conflict occurs most maximally in those scene regions perceived at high resolution by the observer in the central region of the fovea. Even outside the central region of the fovea, the eye can still perceive depth, but with lower depth resolution. However, in the peripheral field of view far from the center of the fovea, only two-dimensional vision remains feasible.

[0023] If the region of the 3D scene in the eye's line of sight (which thus impacts the retina at the center of the fovea) is holographically represented, and the region of the viewpoint perceived from the center of the fovea at a lower resolution is stereoscopically represented, then potential convergence-accommodation conflicts are reduced compared to a purely stereoscopic representation. However, convergence-accommodation conflicts can only be completely avoided if the holographic portion of the viewpoint or field of view is large enough that the stereoscopic representation occurs only within the viewpoint region without depth information. For this purpose, the viewpoint region that must be holographically represented is approximately 30 degrees, and thus resembles the holographic region of the numerical example of 26 degrees specified in WO2012 / 062681 A1. As already described, a spatial light modulator, for example, with 2000 × 2000 complex-valued macropixels in a single segment, will approximately generate a field of view of only 8 degrees × 8 degrees vertically.

[0024] In particular, WO 2012 / 062681 A1 describes the possibility of using two different light modulators to generate stereoscopic and holographic segments.

[0025] WO 2018 / 146326 A2 describes a holographic head-mounted display that uses a curved light guide device, which also allows for the combination of holographic segments and stereoscopic segments generated by the same spatial light modulation device or by two different spatial light modulation devices. By tracing the viewpoint or field of view of at least one holographic segment to the observer's line of sight, and by generating a large viewpoint or field of view, in the case of stereoscopic segments, an overall large viewpoint or field of view is generated, which is achieved with lower requirements on the spatial light modulation device compared to conventional pure holographic representations.

[0026] However, WO 2018 / 146326 A2 may have the following drawbacks: if the entire angular range of the human eye, which still has significant depth resolution, is intended to be represented holographically in a conventional manner in order to completely avoid possible convergence-discontinuity conflicts, then a relatively large number of pixels in the spatial light modulation device or a relatively large number of time-sequentially generated segments are still required.

[0027] The numerical example in WO 2012 / 062681 A1 mentions, for example, a central angle range of 26° vertically, which is holographically represented. In the example mentioned with 250 pixels per degree, this would correspond to approximately 6500 complex-valued macropixels in a spatial light modulation apparatus, or approximately three to four sequentially represented segments in a spatial light modulation apparatus with 2000 complex-valued macropixels. For a viewing angle or field of view of 26 degrees vertically × 26 degrees horizontally, this would correspondingly provide 9 to 16 segments. This would correspond to a very high computational and representational workload.

[0028] Therefore, the object of the present invention is to provide a display device capable of generating a large field of view in a simple manner without requiring high computational power or time. Preferably, this is intended to be achieved in conjunction with segmented imaging of a spatial light modulation device. In particular, it is intended to provide a display device that is better suited than the display device of WO 2018 / 146326 A2 to reduce the lateral resolution of the human retina with reduced but still maintained depth resolution, and to help further reduce the pixel count or frame rate requirements in spatial light modulation devices and further improve user convenience in the display device or display.

[0029] According to the present invention, this objective is achieved by a display device having the features of claim 1.

[0030] According to the present invention, a display device is provided that is particularly suitable for near-eye displays, and especially for head-mounted displays in this context, but its use is not intended to be limited to these displays or display devices. This display device can also be used, for example, in future head-up displays that have a larger field of view than commercially available head-up displays to date.

[0031] The display device according to the invention for representing two-dimensional and / or three-dimensional objects or scenes comprises at least one illumination device for sufficiently emitting coherent light, at least one spatial light modulation device for modulating incident light, and at least one optical system. The at least one optical system is provided for multiple imaging of the at least one spatial light modulation device and for generating a virtual viewing window based on the number of images from the at least one spatial light modulation device. The individual images from the at least one spatial light modulation device are combined as segments to form a field of view. This field of view comprises at least one high-resolution holographic segment and at least one low-resolution holographic segment.

[0032] Therefore, according to the present invention, in order to generate a large viewing angle or large field of view by using a segmented representation of the field of view, a combination of at least one high-resolution holographic segment and at least one low-resolution holographic segment is provided. In this way, compared with display devices known in the prior art, a reduced number of pixels and / or a reduced frame rate can be used in the spatial light modulation device of the holographic display device. Furthermore, by segmenting and representing the field of view, a large field of view can be generated by combining the individual segments with each other, within which an observer can observe a three-dimensional scene or object. For this purpose, the observer observes the three-dimensional scene through a virtual viewing window. This means that a virtual viewing window is generated during each individual segment of generating the large field of view, and all viewing windows for the observer's eye are intended to be formed at one location in the observer's plane and superimposed on each other.

[0033] One or more segments of the field of view of a 3D scene (which are intended to be located in the direction of the observer's eye's line of sight, or can be found there after the entire field of view has been generated, and thus impact the retina at the center of the fovea) are generated and represented holographically at high resolution, i.e., with very high resolution. In the context of this application, a segment is referred to as high resolution when the resolution (i.e., object points per degree of the field of view, determined by a virtual viewing window) almost reaches or fully reaches or exceeds the observer's eye resolution of 60 pixels / object points per degree of the field of view at the center of the retina, particularly when the resolution is greater than or equal to 50 pixels / object points per degree of the field of view. The same applies when the desired resolution of a high-resolution holographic segment almost reaches but does not fully reach the eye resolution, i.e., 50 pixels / object points per degree of the field of view.

[0034] However, one or more of the aforementioned segments of the same 3D scene's field of view (which are not intended to be located in the direction of the observer's eye's line of sight, or can be found there after the entire field of view is generated, and thus impact the retina but not at the center of the fovea) are generated and represented holographically at low resolution, i.e., have low resolution. In the context of this application, a segment is referred to as low resolution when the resolution (i.e., the number of object points per degree of field of view, which is determined by the virtual viewing window) drops significantly below the resolution of the observer's eye, particularly when the resolution is less than or equal to 40 pixels / object point per degree of field of view (e.g., in the range between 40 pixels / object point per degree of field of view and less than 5 pixels / object point per degree of field of view, but not intended to be limited to this lower value of 5 pixels / object point).

[0035] For example, a large field of view or wide viewing angle of 50 degrees horizontally by 50 degrees vertically can be generated by combining a high-resolution holographic fragment of approximately 8 × 8 degrees with a low-resolution holographic fragment of approximately 50 × 50 degrees. The high-resolution holographic fragment is then positioned within the low-resolution holographic fragment. The size of the viewing angle of the fragment is not limited to the values ​​exemplified. For example, the horizontal and vertical viewing angles of the fragment can be different. At least one low-resolution holographic fragment can also have a size of, for example, 60 × 30 degrees. The high-resolution holographic fragment can have a maximum viewing angle of approximately 10 × 10 degrees. The low-resolution holographic fragment can have a maximum viewing angle of approximately 100 × 100 degrees.

[0036] Using the display device according to the invention, a more realistic depth representation of reconstructed object points can be advantageously achieved compared to the generation of stereoscopic fragments of objects in a three-dimensional scene not located in the direction of the observer's eye's line of sight, or even the generation of at least one low-resolution holographic fragment. In this way, since the viewpoint or field of view is generated only holographically, possible convergence-accommodation conflicts are largely reduced or completely avoided.

[0037] Other advantageous configurations and improvements of the invention can be found in the other dependent claims.

[0038] In a particularly advantageous configuration of the invention, at least one optical system may be provided for use in conjunction with the generation of at least one high-resolution holographic segment to generate at least one virtual viewing window, the size of which is equal to or larger than the size of the pupil of the observer's eye in the field of view of the object or scene being viewed.

[0039] The typical pupil size of the human eye ranges from about 2.5 mm to 6 mm. Preferably, the size of at least one virtual viewing window of at least one high-resolution holographic segment can be selected from the range of about 6 mm to about 15 mm.

[0040] In another particularly advantageous embodiment of the invention, at least one optical system may be provided for use in conjunction with the generation of at least one low-resolution holographic segment to generate at least one virtual viewing window, the size of which is smaller than the size of the pupil of the observer's eye when viewing an object or scene in the field of view.

[0041] In this configuration, the low-resolution holographic fragment is generated via a virtual viewing window smaller than the observer's pupil. Preferably, the size of at least one virtual viewing window for at least one low-resolution holographic fragment is selected within the range of about 0.5 mm to about 2 mm.

[0042] Advantageously, not only the computational workload of the hologram to be encoded into the spatial light modulation device, but also the required number of pixels of the spatial light modulation device for generating a specific viewpoint, is reduced by using low-resolution holographic segments with a virtual viewing window smaller than the observer's pupil.

[0043] For multiple low-resolution holographic segments and / or multiple high-resolution holographic segments, including virtual viewing windows of different sizes can also be advantageous.

[0044] Therefore, multiple high-resolution holographic segments can be used, but in particular, multiple low-resolution holographic segments with virtual viewing windows of different sizes can also be used. For example, low-resolution holographic segments with virtual viewing windows of about 0.5 mm and low-resolution holographic segments with virtual viewing windows of about 2 mm can be provided and generated. However, in principle, multiple high-resolution holographic segments with virtual viewing windows of different sizes can also be used in the observer plane. The size of the individual virtual viewing windows used for high-resolution holographic segments is advantageously located in the range of about 6 mm to about 15 mm.

[0045] Furthermore, multiple low-resolution holographic fragments with virtual viewing windows of different sizes can also be combined with multiple high-resolution holographic fragments with virtual viewing windows of different sizes and provided together.

[0046] By adjusting the size of the virtual viewing window, different pixel values ​​are obtained for each high-resolution holographic fragment and for each low-resolution holographic fragment, respectively, for each degree of field of view required by the spatial light modulation device.

[0047] An optical system with a suitable configuration for imaging at least one spatial light modulation device can appropriately define, select, and adjust the number of pixels per degree of field of view. In this case, the optical system should provide a correspondingly defined distance in the observer plane from the image of the spatial light modulation device to the virtual observation window, as well as a predetermined magnification of the image of the spatial light modulation device.

[0048] It is advantageous to provide, at the same location, a virtual observation window for generating at least one low-resolution holographic fragment in the observer plane and a virtual observation window for generating at least one high-resolution holographic fragment.

[0049] In addition, a virtual viewing window for at least one low-resolution holographic segment may be provided that at least partially overlaps with a virtual viewing window for at least one high-resolution holographic segment.

[0050] In one embodiment of the invention, different spatial light modulation devices can be used to generate at least one high-resolution holographic segment and at least one low-resolution holographic segment. For this purpose, at least two spatial light modulation devices can be provided, one for generating at least one high-resolution holographic segment and the other for generating at least one low-resolution holographic segment.

[0051] In this configuration, a spatial light modulation device for generating at least one high-resolution holographic segment and another spatial light modulation device for generating at least one low-resolution holographic segment can be configured differently. For example, the two spatial light modulation devices can contain pixels of different sizes, different numbers of pixels, or different aspect ratios. The spatial light modulation device for generating at least one high-resolution holographic segment can, for example, contain a square arrangement of 2000×2000 complex-valued pixels to generate an 8×8-degree viewing angle. The spatial light modulation device for generating at least one low-resolution holographic segment can, for example, contain a rectangular arrangement of 1000×500 complex-valued pixels with an aspect ratio of 2:1 and generate a 60×30-degree viewing angle.

[0052] In an alternative preferred embodiment, the same spatial light modulation device is used for at least one high-resolution holographic segment and at least one low-resolution holographic segment.

[0053] According to another advantageous configuration of the invention, the optical system may include at least one switchable or controllable element.

[0054] The optical system is configured to include at least one switchable or controllable element or component. Using at least one switchable or controllable element in the optical system, the size of the virtual viewing window to be generated can be selected and adjusted during the generation of a corresponding high-resolution or low-resolution holographic segment, or the number of pixels per degree of field of view. In this way, the generation of at least one high-resolution holographic segment or at least one low-resolution holographic segment can be selected using simple means. For this purpose, at least one switchable or controllable element can be switched or controlled according to whether a high-resolution or low-resolution holographic segment is to be generated.

[0055] In a particularly advantageous configuration of the invention, the optical system may include two switchable or controllable optical elements, the first switchable or controllable optical element being switchable or controllable to generate at least one high-resolution holographic segment, and the second switchable or controllable optical element being switchable or controllable to generate at least one low-resolution holographic segment.

[0056] At least one switchable or controllable element in at least one optical system can be configured as a lens element, mirror element, or grating element that deflects incident light differently depending on the switching state. The lens element can optionally be configured as refractive or diffractive. At least one switchable or controllable element in the optical system can also be configured as a polarization switch in combination with a passive polarization selection element (e.g., a polarization selection lens element or a linear grating polarizer) acting as a polarization selection mirror, or an active grating element that deflects light differently according to the polarization state. Viewed from the direction of light propagation, the at least one switchable or controllable element can be arranged in the beam path of the display device according to the invention, between at least one spatial light modulation device and an observer plane, wherein at least one virtual viewing window and the observer's eye are located in the observer plane.

[0057] Advantageously, the hologram in the form of a single disparity code can also be written into at least one spatial light modulation device to generate at least one high-resolution holographic segment and at least one low-resolution holographic segment.

[0058] Alternatively, a hologram encoded in single disparity can be written into at least one spatial light modulation device for a holographic segment (however, particularly for at least one low-resolution holographic segment). In this way, a virtual viewing window is generated in one dimension or direction (i.e., in the encoding direction of the hologram in the spatial light modulation device), and an optimal spot is generated in a dimension or direction perpendicular to it (i.e., in the non-encoding direction of the hologram). Therefore, it is feasible that the size of the optimal spot can be larger than the typical pupil of an observer for at least one low-resolution holographic segment. For example, the area of ​​the optimal spot in the observer's plane can have a range of approximately 10 mm, while the area of ​​the virtual viewing window can have a range of approximately 1 mm.

[0059] If the same spatial light modulation device is used to generate low-resolution holographic fragments and to generate high-resolution holographic fragments, these fragments are generated in chronological order (i.e., sequentially).

[0060] However, if two spatial light modulation devices are used, namely one spatial light modulation device for generating at least one low-resolution holographic fragment and another spatial light modulation device for generating at least one high-resolution holographic fragment, the fragments can be generated in parallel (i.e., simultaneously).

[0061] In an alternative advantageous configuration of the invention, it can be provided that a hologram in the form of full parallax coding can be written into at least one spatial light modulation device to generate at least one high-resolution holographic segment, and that a hologram in the form of single parallax coding can be written into at least one spatial light modulation device to generate at least one low-resolution holographic segment.

[0062] Therefore, full disparity coding of a hologram is used to generate at least one high-resolution holographic segment, and single disparity coding of a hologram is used to generate at least one low-resolution holographic segment.

[0063] In the same case, the same spatial light modulation device can be used to generate low-resolution holographic fragments and to generate high-resolution holographic fragments, although these fragments can be written into the spatial light modulation device with different codes and then generated in chronological order.

[0064] However, it is also feasible to use two spatial light modulation devices, namely one spatial light modulation device for generating at least one low-resolution holographic segment and another spatial light modulator for generating at least one high-resolution holographic segment, with the hologram written into the two spatial light modulation devices respectively by different codes and then these segments are generated simultaneously.

[0065] Furthermore, at least one filter device can be advantageously provided for eliminating higher diffraction orders present in the observer plane.

[0066] Specifically, for at least one low-resolution holographic segment, it is possible to filter out higher diffraction-order light so that this light cannot reach the observer's pupil in the field of view of the 3D scene. This avoids unwanted double images of the holographic reconstruction or the holographic reconstruction of the scene or object visible to the eye. However, it is also possible to filter out all or only specific higher diffraction-order light using the same or additional filter device for at least one high-resolution holographic segment. For a virtual viewing window larger than the typical size of the pupil of at least one high-resolution holographic segment, this light generally does not directly impact the eye. However, filtering can reduce unwanted interference effects that may occur in the optical system, such as unwanted reflections at the lens surface. Alternatively, filtering facilitates the use of optical elements (e.g., volumetric gratings) with only a specific angle of reception.

[0067] An eye-tracking device and at least one tracking device can be advantageously provided in the display device according to the invention. In this case, the eye-tracking device can be provided for detecting the position of the pupil in the eye and tracking the gaze of the observer as they observe an object or scene.

[0068] At least one tracking device may be provided with a virtual viewing window for following the at least one high-resolution holographic segment and / or a virtual viewing window for following at least one low-resolution holographic segment, and may therefore be specifically configured as a viewing window tracking device.

[0069] Furthermore, at least one device can be provided for adjusting the position, i.e. the distance from the visual observation window of the image of at least one spatial light modulation device, or adjusting at least one high-resolution holographic segment and / or at least one low-resolution holographic segment to the position of the observer's eye focal point and the direction of the line of sight (here, the range of the observation angle in the field of view) as determined by the eye-tracking device, and thus can be specifically configured as an eye-tracking device.

[0070] Furthermore, it is feasible and even preferred that the display device according to the invention includes two tracking devices, namely an observation window tracking device and an eye tracking device.

[0071] In a gaze-tracking device, for example, at least one diffraction grating with a variable grating period can be used, as described in WO2010 / 149587 A2. For example, by incorporating a lens function into at least one diffraction grating, the distance from the image of at least one spatial light modulation device to the virtual viewing window can be shifted. For example, by incorporating a prism function into at least one diffraction grating, the viewing angle range of at least one high-resolution holographic segment and / or at least one low-resolution holographic segment in the field of view can be shifted.

[0072] The eye-tracking device can be arranged in the display device according to the invention, for example, in the Fourier plane of the spatial light modulation device. However, the invention is not intended to be limited to this position of the eye-tracking device in the display device, and therefore other positions in the display device are also feasible.

[0073] Preferably, observer tracking is performed via an observation window tracking device by having virtual observation windows for both at least one high-resolution holographic segment and at least one low-resolution holographic segment follow the observer's eye position in the three-dimensional scene as the eye or observer moves to different positions. This tracking of the individual segments of the field of view can be performed in various ways. For example, as described, for instance, in WO 2018 / 037077 A2, multiple diffraction orders can be used for at least one high-resolution holographic segment, and the displacement of the virtual observation window can be utilized by encoding prism terms and prism functions into at least one spatial light modulation device within these diffraction orders. For example, in different configurations, such as those described in WO 2010 / 149587 A2, a diffraction grating with a variable grating period can also be used.

[0074] For example, at least one diffraction grating for tracking a virtual viewing window can be arranged in the image plane of at least one spatial light modulation device. However, the invention is not intended to be limited to this location, but other locations are equally feasible.

[0075] However, in another embodiment of the invention, at least two diffraction gratings may also be used to perform a combination of observation window tracking and line-of-sight tracking.

[0076] However, this invention is not intended to be limited to a particular type of tracking.

[0077] In another particularly advantageous embodiment of the invention, the field of view may include at least one high-resolution holographic segment, at least one low-resolution holographic segment, and at least one stereoscopic segment.

[0078] At least one high-resolution holographic segment and at least one low-resolution holographic segment can therefore be combined with at least one stereoscopic segment within the field of view. This means that, in addition to at least one high-resolution holographic segment and at least one low-resolution holographic segment, at least one stereoscopic segment is generated. This at least one stereoscopic segment is generated in a lateral region of the field of view, in which the observer perceives the represented scene only at low resolution and with a greatly reduced or even non-existent depth resolution, i.e., with little or no three-dimensional impression of the scene or objects. This at least one stereoscopic segment is configured as a fixed segment within the field of view. This means that the stereoscopic segment will not be displaced to different positions within the field of view by a tracking device.

[0079] For example, a large field of view or wide viewing angle of 120 degrees horizontally and 50 degrees vertically can be generated by combining a high-resolution holographic segment with a size of approximately 8×8 degrees, a low-resolution holographic segment with a size of approximately 50×50 degrees, and a fixed and therefore immovable stereoscopic segment with a size of approximately 120×50 degrees. The high-resolution holographic segment can be moved within the field of view in the horizontal direction and / or in the vertical direction within a range of approximately ±25 degrees using at least one eye-tracking device. The low-resolution holographic segment can also be moved within the field of view in the horizontal direction within a range of approximately ±25 degrees, but is set to be fixed in the vertical direction, i.e., immovable.

[0080] Then at least one high-resolution holographic fragment is located inside the generated and represented low-resolution holographic fragment. This involves the overall representation of these two fragments used to generate a large field of view.

[0081] If at least one additional stereoscopic segment is generated and the field of view is further expanded in this manner, then at least one high-resolution holographic segment and at least one low-resolution holographic segment are located inside the additionally generated and represented stereoscopic segment.

[0082] Therefore, it may be advantageous to arrange at least one high-resolution holographic segment, at least one low-resolution holographic segment, and at least one stereoscopic segment in a partially or completely overlapping manner within the field of view.

[0083] The individual segments (i.e., low-resolution holographic segments and high-resolution holographic segments, and, if further stereoscopic segments are intended to be generated) may optionally partially or completely overlap with each other in the field of view. In particular, segments generated as smaller sizes may be completely contained within segments generated as larger sizes and may be shifted by a tracking device. This applies to both high-resolution and low-resolution holographic segments, and, where applicable, stereoscopic segments.

[0084] Furthermore, in an advantageous configuration of the invention, at least one light guide device can be provided, comprising a light guide, at least one optical coupling device, and at least one optical decoupling device, wherein light propagates inside the light guide by reflection at the boundary surface of the light guide, and after the light undergoes a predetermined number of reflections at the boundary surface of the light guide, the light is decoupled from the light guide by the optical decoupling device.

[0085] Furthermore, the optical structure of the display device according to the invention may, for example, include a light guide device. In this case, at least one high-resolution holographic segment can be generated and shifted in a manner described in WO 2018 / 146326 A2. Low-resolution holographic segments can be generated, for example, by using the same light guide device but optionally utilizing separate optical coupling devices entering the light guide and optical decoupling devices exiting the light guide, in a manner similar to that described for stereoscopic segments in WO 2018 / 146326 A2.

[0086] Similarly, during the generation of at least one high-resolution holographic segment and at least one low-resolution holographic segment, light then propagates within the optical guide of the optical guide device by reflection at the boundary surface of the optical guide. After a predetermined number of reflections at the boundary surface of the optical guide, the light is decoupled from the optical guide or the optical guide device for each individual segment by an optical decoupling device. The number of reflections may be the same for different segments. In other embodiments, the number of reflections may also be adjusted to be different. For example, for a high-resolution holographic segment, it may be decoupled from the optical guide of the optical guide device after a different or other number of reflections compared to a low-resolution holographic segment. For more than one high-resolution holographic segment or more than one low-resolution holographic segment, decoupling of each high-resolution holographic segment or each low-resolution holographic segment may also be performed after different numbers of reflections.

[0087] For example, the observer angle range of at least one high-resolution holographic segment can be adapted to the observer's line of sight by adjusting the number of reflections in a manner modified for the at least one segment.

[0088] Therefore, at least one optical system and at least one light guide can be advantageously provided for generating at least one high-resolution holographic segment and at least one low-resolution holographic segment, and for generating at least one stereoscopic segment when needed, wherein the high-resolution holographic segment, the low-resolution holographic segment and the stereoscopic segment when needed together form a field of view in which a three-dimensional scene or three-dimensional object can be represented.

[0089] Even if at least one light guide device is provided in the display device according to the invention, imaging of at least one spatial light modulator can be provided by means of at least one light guide device and at least one optical system.

[0090] Furthermore, it may be advantageous to provide a light source image of at least one light source disposed in at least one illumination device in the optical path via an optical system before coupling the light into the light guide device.

[0091] In this case, especially for at least one low-resolution holographic segment, at least one optical coupling device is preferably located in or around the position of the light source image.

[0092] Therefore, according to the present invention, light is coupled into the light guide of the light guide device at or near the location of the light source image.

[0093] Advantageously, the optical system may also include two cylindrical optical elements arranged in a cross configuration relative to each other.

[0094] Furthermore, it is advantageous to provide an optical system for generating a linear or one-dimensional light source image in the optical path before coupling the light into the light guide device.

[0095] In this way, particularly for at least one low-resolution holographic segment, two cylindrical optical elements can be configured as cylindrical lens elements with different focal lengths in the horizontal and vertical directions, for example, generating a focal point only in the horizontal direction at the location where the light is coupled into the light guide device. Therefore, a linear or one-dimensional light source image is generated in the region of the light coupling device where the light is coupled into the light guide device. In the other direction, according to the example vertical direction, no light source image is generated until the light is decoupled from the light guide device.

[0096] When a hologram is provided to a preferred single-parallax encoding in at least one spatial light modulation device, an optimal light spot is generated in the beam path in the non-encoding direction of the hologram after the light is decoupled from the optical guide of the optical guide device. A virtual observer region is generated in the encoding direction of the hologram and in the light direction after the at least one optical guide device, in the Fourier plane or image plane of the at least one spatial light modulation device. Therefore, a virtual observer region is provided in the Fourier plane of the spatial light modulation device in the encoding direction of the hologram. In this case, when no hologram is written or encoded into the spatial light modulation device, the plane forming the Fourier transform of the hologram also corresponds to the plane of the light source image. In this case, the image of the light source is generated after the light is decoupled from the optical guide at a defined distance from the optical guide. In other words, a light source image of at least one light source of at least one illumination device can be generated in the optical path after the light is decoupled from at least one optical guide device in the encoding direction at the location of the virtual observer region. This means that a virtual observer image or virtual observation window can be generated in the plane of the light source image or in the plane of the image of the spatial light modulation device.

[0097] In the non-encoding direction perpendicular to it, when a hologram is provided to a preferred single-parallax encoding in at least a spatial light modulation device, a light source image of at least one light source of at least one illumination device can be generated in the optical path at or near the coupling position in the light-entry optical guide. In other words, when no hologram is written or encoded into the spatial light modulation device, a linear light source image exists at or near the coupling position in the light-entry optical guide.

[0098] Depending on the direction in which the hologram is encoded into at least one spatial light modulation device, two cylindrical optical elements generate a horizontal or vertical light source image, which is formed at different positions in the beam path of the display device relative to the encoded and non-encoded directions. For illustrative purposes, it may be mentioned herein that the terms "horizontal (linear) light source image" and "vertical (linear) light source image" should be understood to refer, for example, a horizontal image in the form of a vertical line or a vertical image in the form of a horizontal line, which has been formed from a point light source. This is applicable when performing single parallax encoding of the hologram into the spatial light modulation device of the display device according to the invention.

[0099] The objective of the invention is also achieved by a method for generating a large field of view as described in claim 29, within which a scene or object is represented at different resolutions.

[0100] The method for generating a large field of view according to the invention is implemented by at least one illumination device, at least one spatial light modulation device, and at least one optical system, within which a scene or object is represented at different resolutions, wherein...

[0101] - At least one spatial light modulation device modulates the incident light with the desired information of the scene or object.

[0102] - At least one optical system performs multiple imaging on at least one spatial light modulation device and generates a virtual viewing window based on the number of images from at least one spatial light modulation device, wherein the individual images from at least one spatial light modulation device are combined with each other as segments to form a field of view, and at least one high-resolution holographic segment and at least one low-resolution holographic segment are generated to form a field of view.

[0103] Advantageously, the generation of at least one high-resolution holographic segment and at least one low-resolution holographic segment can be implemented by switchable or controllable elements of the optical system.

[0104] Furthermore, it is preferable to provide two switchable or controllable optical elements in the optical system, wherein in order to generate at least one high-resolution holographic segment, the first switchable or controllable optical element is switched or controlled and the second switchable or controllable optical element is not switched or controlled, and in order to generate at least one low-resolution holographic segment, the second switchable or controllable optical element is switched or controlled and the first switchable or controllable optical element is not switched or controlled.

[0105] There are now various possibilities for advantageously configuring the teachings of the invention and / or combining the described exemplary embodiments or configurations with each other. For this purpose, reference is made, on the one hand, to the patent claims which rely on the independent claims, and on the other hand, to the following description of preferred exemplary embodiments of the invention with reference to the accompanying drawings, in which generally preferred configurations of the teachings are also illustrated. In this context, the invention is described in principle according to the described exemplary embodiments, but is not intended to be limited to the latter.

[0106] In the attached diagram:

[0107] Figure 1 This diagram illustrates the field of view of the human eye.

[0108] Figure 2: A schematic diagram of a display device according to the prior art;

[0109] Figure 3 A schematic diagram of a display device according to the present invention is shown during the generation of high-resolution holographic fragments;

[0110] Figure 4 : This shows the process of generating low-resolution holographic fragments according to Figure 3 A schematic diagram of a display device according to the present invention;

[0111] Figure 5 A schematic diagram of a display device according to the present invention is shown, wherein the representation of high-resolution holographic segments and low-resolution holographic segments is related to the generation of additional stereoscopic segments;

[0112] Figure 6 A schematic diagram of an alternative display device for generating high-resolution holographic fragments according to the present invention is shown.

[0113] Figure 7 : This shows the process of generating low-resolution holographic fragments according to Figure 6 A schematic diagram of an alternative display device according to the present invention;

[0114] Figure 8 According to the alternative arrangement of the optical coupling device for generating low-resolution holographic fragments and for generating high-resolution holographic fragments. Figure 6 and 7 A schematic diagram of an alternative display device according to the present invention;

[0115] Figure 9 The diagram illustrates another alternative embodiment of the display device according to the invention, wherein a light source image is generated in the light direction prior to the light guide device; and

[0116] Figure 10 : Shows according to Figure 9 A schematic diagram of an alternative configuration for the display device.

[0117] It should be briefly mentioned that the same elements / parts / assemblies also have the same reference numerals in the accompanying drawings.

[0118] Figure 1 A schematic diagram of the human eye's field of vision is shown. This diagram is intended to help in a better understanding of the invention.

[0119] Features represented in the field of view are imaged onto the retina of the human eye. This means that the field of view represents the area where visual perception exists. The most sensitive visual perception or clearest recognition of features within the field of view is possible only within the fovea of ​​the retina. Resolution or perceptual quality regarding visual acuity, pattern recognition, and color vision decreases significantly towards the peripheral regions of the field of view. Figure 1 It can be seen that the horizontal range of the eye's field of vision is approximately 120 degrees. Figure 1 The representation is intended to relate only to one human eye. This is because the combined horizontal field of vision of both eyes is approximately 180 to 214 degrees. The field of vision within which the eye can receive a three-dimensional impression is approximately 30 degrees. Outside this 30-degree field of view, the eye can no longer perform any depth perception. Within the range of approximately 30 to approximately 60 degrees, stereoscopic vision is possible, but without depth perception.

[0120] Figure 2 illustrates the holographic display device in which the virtual viewing window is generated. In this case, a large field of view is achieved through field of view segmentation. In this case, different parts of the field of view visible from the virtual viewing window at the observer's eye position are generated sequentially in time using a spatial light modulator 200, a light deflection device 400, and a lens 500.

[0121] A spatial light modulator 200 is shown having a coherent wavefront in a temporal sequence carrying different holographic information, and light deflection devices 400 in multiple segments in at least one-dimensional planes. In this way, an image of the assembled light modulator is formed. The temporally formed segmented wavefronts are guided in the direction of the pupil by an imaging device. Using the shown segments of the spatial light modulator, a spatially visible region or field of view is generated.

[0122] To understand the exemplary embodiments described herein, the relationship between the imaging beam path and the illumination beam path, as well as the size of the virtual viewing window and the field of view in the display device, will first be explained. The display device includes an illumination device, a spatial light modulation device (hereinafter referred to as SLM), and an optical system, which, for illustrative purposes, comprises an idealized lens, i.e., a thin lens without aberrations. However, such a display device will only have a limited field of view.

[0123] Specifically, the field of view is fixed in relation to the size of the virtual viewing window, as both depend on the focal length of the display device's optical system. If the virtual viewing window is magnified, the field of view becomes smaller, and vice versa. Typically, the optical system used influences both the illumination beam path and the imaging beam path within the display device.

[0124] The optical system of a display device can typically contain not just one imaging element, but multiple imaging elements. The total focal length and principal plane of the system can then be determined using known geometric optics methods. The above description then applies accordingly to the entire system.

[0125] In the exemplary embodiments described below, a large field of view is generated by a display device. In this case, the field of view is formed by at least one high-resolution holographic segment and at least one low-resolution holographic segment. These segments are images of an SLM or images of the diffraction order in the Fourier plane of the SLM, respectively. However, if the size of the field of view makes it necessary, multiple high-resolution holographic segments and multiple low-resolution holographic segments can also be generated. This can be used when generating a large field of view because a person in a natural environment can only see and perceive a limited solid angle with high resolution and a strong three-dimensional impression. Therefore, it is feasible to represent objects in a three-dimensional scene at a lower resolution, where the observer does not directly observe or focus on the objects, but only perceives them in the background. Thus, the observer will perceive the objects in the background with a smaller three-dimensional impression. Therefore, the background of the three-dimensional scene to be represented can be generated by at least one low-resolution holographic segment, which contains multiple objects visible throughout the entire field of view.

[0126] However, objects observed or focused on by the observer, or objects in a 3D scene, should have a strong 3D impression. However, these objects only need to be represented at high resolution within a limited solid angle range of the field of view. For this purpose, at least one high-resolution holographic segment is generated by a display device. Depending on the size of the solid angle range, multiple high-resolution holographic segments can also be generated, arranged sequentially to generate that solid angle range. Within this segment generated holographically at high resolution, the 3D object of interest to the observer is reconstructed and represented. This means that at least one high-resolution holographic segment is generated within at least one low-resolution holographic segment. The high-resolution holographic segments are superimposed or overlapped with the low-resolution holographic segments. Since each segment is an image of the SLM, and therefore also an image of the pixels of the SLM, at least one high-resolution holographic segment represents an image with a high pixel density, while at least one low-resolution holographic segment represents an SLM image with a lower pixel density.

[0127] However, the present invention is not intended to be limited without exception to a combination of high-resolution holographic representation and low-resolution holographic representation. As will be shown in an exemplary embodiment, at least one high-resolution holographic segment and one low-resolution holographic segment may also be additionally combined with at least one stereoscopic segment.

[0128] The following will explain the relationship between the size of the virtual viewing window and the number of pixels required per degree of the SLM.

[0129] For an SLM with a pixel pitch of p at a distance D from a virtual viewing window vw in a holographic display device, and for light of wavelength λ, the maximum size of the virtual viewing window is vw = D * λ / p. In a holographic display device that generates an image of the SLM, such as a head-mounted display or projection display visible from the virtual viewing window, D and p are the distance from the SLM image to the virtual viewing window and the pixel pitch, respectively.

[0130] If the D / p ratio remains constant, for example, an SLM or an SLM image with a larger distance and larger pixel pitch or a pixel pitch of an SLM image can also be used to generate a virtual viewing window of the same size.

[0131] Then, a 1-degree viewing angle on the SLM corresponds to the range x = tan 1° * D. To determine the number of pixels N of the SLM within a 1-degree viewing angle, this range on the SLM is divided by the pixel pitch, which is N = x / p = tan 1°D / p. The quotient D / p also appears in this equation, so it can be replaced with N = tan 1°vw / λ. For a virtual viewing window of approximately 7 mm in size and a light wavelength of λ = 460 nm, this would result in, for example, 266 pixels for the SLM. This value decreases linearly with the size of the virtual viewing window. For a virtual viewing window of approximately 1 mm in size and the same light wavelength of λ = 460 nm, approximately 38 pixels per degree of viewing angle are required. In this case, an SLM with 2000 complex-valued pixels (two pixels form a complex-valued pixel) with an appropriately selected quotient D / p can generate a field of view or viewing angle greater than approximately 50 degrees.

[0132] The relationship between the size of the virtual viewing window and the visible resolution will now be explained.

[0133] For holographic display devices or displays that generate virtual viewing windows, the size of the virtual viewing window is typically chosen in such a way that it is at least as large as the observer's pupil. In this case, when the observer's pupil is fully within the virtual viewing window, it acts as a diffraction-limiting aperture for the light entering the eye. In principle, the visible resolution of the holographic three-dimensional (3D) scene is then limited by the diffraction limit of the eye's pupil size, and possibly by the aberrations of the eyepiece and by the distribution of photoreceptors on the retina of the eye, in the same way as the observer's perception of their natural environment.

[0134] However, holographic reconstruction can also be implemented using a virtual viewing window smaller than the observer's pupil. In this case, the aperture of the virtual observer window (which is then located within the pupil) acts as a diffraction-limiting aperture that can restrict the resolution of the perceived 3D scene.

[0135] However, the present invention is based on the insight that this limitation in resolution is only meaningful when the reconstructed scene is located directly at the center of the retina of the eye (i.e., it is imaged onto the fovea, the area representing the most sensitive visual region on the retina), and therefore exists in cases where the scene has high resolution due to a high density of photoreceptors. Therefore, according to the present invention, a holographic segment is generated or used only for the portion of the three-dimensional scene that does not impact the center of the observer's retina and where the observer's visible resolution would be reduced anyway, and this holographic segment is used to generate a virtual viewing window whose size is smaller than the observer's pupil. In this way, the number of pixels required in the spatial light modulation device can be reduced without sacrificing perceptible resolution.

[0136] Figure 3 and 4 An exemplary embodiment of a holographic display device is schematically illustrated, which generates at least one high-resolution holographic segment and at least one low-resolution holographic segment. For this purpose, the display device includes at least one SLM 1, at least one illumination device (which includes at least one light source 2), and at least one optical system 3. The optical system 3 is used to image the SLM 1. For this purpose, the optical system 3 includes at least one imaging element 4, which is configured to be passive. The imaging element 4 is arranged close to the SLM 1 and, in this case, is primarily used for imaging the SLM 1. In this case, to generate a large field of view, the SLM 1 is subjected to multiple imaging sequentially or optionally simultaneously, and in this way, multiple segments are generated that, together and combined with each other, result in a large field of view. In other words, for each holographic segment, the optical system 3 generates an intermediate image of the SLM 1. In this case, it is not important whether a high-resolution or low-resolution holographic segment is generated.

[0137] Furthermore, the optical system 3 includes at least one switchable or controllable element. According to... Figure 3 and 4 In this exemplary embodiment, the optical system 3 includes two switchable or controllable elements 5 and 6. In this case, the switchable or controllable elements 5 and 6 are configured as lens elements, although other switchable or controllable elements, such as switchable mirrors, can also be used, which deflect light from different segments to different optical elements (e.g., different lenses). Instead of switchable lens elements that are turned on and off, an optical system similar to a zoom lens can also be used, in which the focal length is changed by mechanically altering the distance between the lens elements, so as to adjust different focal lengths for each segment.

[0138] These switchable or controllable elements 5 and 6 are arranged in the beam path between SLM 1 and the observer plane 7, although this arrangement is not mandatory. One of these switchable or controllable elements may also be arranged in the light direction before SLM 1. These two switchable or controllable elements 5 and 6 adjust the quotient D / p, which is a large difference between the distance D from the SLM to the image on the observer plane 7 and the pixel pitch p of the image of the SLM 1, in order to change the size of the virtual observation window and the size of the field of view. Through this adjustment of the quotient D / p, the size of the virtual observation window 8 to be generated in the observer plane 7, as well as the size of the viewing angle or field of view, can be changed according to the switching state of the switchable or controllable elements 5 and 6.

[0139] Figure 3 A display device in mode for generating high-resolution holographic fragments is shown. In this case, the beam path between the SLM 1 and the observer plane 7 for the high-resolution holographic fragment is specifically shown in the figure. The illumination device includes a light source 2 for illuminating the SLM 1 with sufficiently coherent light. According to... Figure 3 and 4 In this exemplary embodiment, the illumination of SLM 1 is the same for both high-resolution and low-resolution holographic fragments. This means that the same light source is used to generate both fragments. Of course, two light sources can also be used for the two holographic fragments to be generated. These two light sources can also be configured differently. However, it is important that both light sources emit sufficiently coherent light.

[0140] Two switchable or controllable elements, 5 and 6, can respectively enter an ON state and an OFF state. Therefore, they are configured so that they can be turned on and off, or controlled in different states. To generate according to... Figure 3 To generate a high-resolution holographic segment, the first switchable or controllable element 5 is switched to the ON state, and the second switchable or controllable element 6 is switched to the OFF state. This means that the first switchable or controllable element 5 thus affects the light impacting it, while the second switchable or controllable element 6 has no effect; that is, the incident light is unaffected by the switchable or controllable element 6 during its propagation. To generate the high-resolution holographic segment, light emitted from the light source 2 of the illumination device impacts the SLM1 and is modulated according to information from the three-dimensional scene. Then, an image 9 of the SLM1 is generated by means of the optical system 3 (i.e., by means of the imaging element 4 and the first switchable or controllable element 5), through which the segment of the field of view is provided. Figure 3The optical path from three pixels P1, P2, and P3 of SLM1 through the image 9 of SLM1 generated by optical system 3 to the observer plane 7 is shown, the image being formed after the first switchable or controllable element 5. In this case, one pixel P2 is located in the middle of SLM1, and the other two pixels P1 and P3 are located at the upper and lower edges of SLM1, respectively. For each pixel, a beam is shown with an aperture angle corresponding to the diffraction angle of the pixel's diffraction order. In the filter plane 11 between SLM1 and the first switchable or controllable element 5, for example, higher diffraction orders can be filtered out. The image 9 of SLM1 is then generated in the beam path after the first switchable or controllable element 5. The beam then continues from the image 9 of SLM1 in the direction of the observer plane 7. In this observer plane 7, the beam profiles of the individual pixels P1, P2, and P3 are superimposed, and a virtual observation window 8 is formed in this observer plane 7 during the generation of a high-resolution holographic fragment. Through the virtual observation window 8, when the observer's eye is located in the observer plane 7 within the area of ​​the virtual observation window 8, the observer can observe the three-dimensional scene or object generated in the field of view.

[0141] The total diameter of these light beam profiles (originating from pixels P1, P2, and P3) at their superposition location in the observer plane 7 defines the extent of the generated virtual observation window 8. This virtual observation window 8 can be... Figure 3 This is seen through the thick gray line in the observer plane 7. Clearly, the central beams from the individual pixels P1, P2, and P3 of SLM 1 arrive at the center of the virtual observation window 8 at different angles. The angular difference between the central beams from the edge pixels P1 and P3 of SLM 1 gives the viewing angle or field of view of the generated high-resolution holographic fragment. In the case of a high-resolution holographic fragment, the generated field of view is... Figure 3 Provided by reference numeral 10 in the figure, and defined by the image 9 of two outer pixels P1 and P3 from SLM 1 and the black line extending to the middle 8 of the virtual viewing window.

[0142] In this scenario, an observer whose eye is within the virtual viewing window 8 will see the image of SLM 1 at a distance from the virtual viewing window 8, as generated by the first switchable or controllable element 5. The holographic 3D scene of various object points in front of and behind the image 9 to be generated in SLM 1 can be written or encoded into SLM 1.

[0143] The resolution of a 3D scene is angular resolution, which is given by the number of pixels per field of view / viewpoint in one dimension or direction of the SLM. For example, a 5-degree field of view / viewpoint with 2000 pixels gives a resolution of 400 pixels per degree of view.

[0144] During the generation of the high-resolution holographic fragment, a large virtual viewing window was generated, larger than the observer's pupil, i.e., its range was greater than approximately 6 mm. However, the generated field of view was limited in size to a few degrees, i.e., no greater than approximately 10 degrees.

[0145] Figure 4 This shows the process of generating low-resolution holographic fragments according to... Figure 3 The display device. In this case, according to and according to Figure 3 The same principle is used to generate low-resolution holographic fragments. This means that, in the same case, the imaging or image of SLM 1, and thus the fragments and virtual observer window, are generated through the illumination device, SLM 1, and optical system 3. In this case, Figure 4 The beam path during the generation of the low-resolution holographic segment is shown. For this purpose, the first switchable or controllable element 5 is switched to the OFF state, while the second switchable or controllable element 6 is switched to the ON state, so that only the second switchable or controllable element 6 affects the light. Light emitted from the light source 2 of the illumination device impacts the SLM 1 and modulates it according to information from the three-dimensional scene. Then, an image 9 of the SLM 1 is generated by means of the optical system 3 (i.e., by means of the imaging element 4 and the second switchable or controllable element 5), through which a segment of the field of view is provided. Figure 3 As shown, the image 9 of SLM 1 is no longer formed in the light direction after the first switchable or controllable element 5, but only after the second switchable or controllable element 6. Clearly, the image 9 of SLM 1 is formed near the observer plane 7, and, however, according to... Figure 3 Compared to image 9, it has a different magnification and a different distance from the observer plane 7. A virtual viewing window 8 is also formed in the observer plane 7 during the generation of the low-resolution holographic fragment. Through this virtual viewing window 8, when the observer's eye is located in the region of the virtual viewing window 8 within the observer plane 7, the observer can observe the 3D-generated scene or object in the field of view 12. However, this part of the scene or object is compared to... Figure 3 The generated and represented scenes are partially represented at lower resolutions.

[0146] The aperture angles of the beams from each pixel P1, P2, and P3 again correspond to, as shown in the figure. Figure 3The diffraction angle of the pixels is shown. In this case, due to other switching states of the switchable or controllable elements 5 and 6, the total diameter of the beam in the observer plane 7 forming the virtual observation window 8 (which comes from pixels P1, P2, and P3 of SLM 1) is now only a small range at the superposition position in the beam path. In this way, only a small observation window 8 is generated. When generating low-resolution holographic segments, the size of the virtual observation window 8 is less than about 2 mm. However, as can be... Figure 4 As can be seen, the beams from pixels P1, P2, and P3 of SLM 1 are more... Figure 3 A much larger, different angle reaches the observer plane 7, and then reaches the virtual observation window 8 there. This is in Figure 4 This is further illustrated by the black lines at the edge pixels P1 and P3 of the image 11 from the middle of the SLM 1 in the virtual viewing window 8. This generates a large angular range to provide a large field of view 12 or a wide viewing angle.

[0147] An image of SLM 1 is generated via a second switchable or controllable element 6, which in this case is close to the observer plane 7. However, a 3D scene with object points located at arbitrary distances from the observer plane 7 can again be written or encoded into SLM 1.

[0148] The resolution of the 3D scene in at least one low-resolution holographic fragment is again determined by the number of SLM pixels per field of view or viewpoint in one dimension or direction. For example, if a 66-degree field of view is generated using 2000 pixels, the resolution is 30 pixels per degree of field of view. Again, these are intended to be exemplary values ​​only.

[0149] After its generation, according to Figure 3 The generation and representation of at least one high-resolution holographic fragment then at least partially located according to Figure 4 The generation and representation of low-resolution holographic fragments. To obtain a large field of view, where interference from convergence-modulation conflicts can be completely avoided, multiple or a large number of high-resolution holographic fragments and multiple or a large number of low-resolution holographic fragments can be generated. Then, based on the... Figure 3 and 4 The same principle is used to generate these holographic fragments. Generation can be performed chronologically or optionally simultaneously (in parallel).

[0150] When needed, such as when an observer in a 3D scene shifts focus from one object to another, or when the observer moves to a different location or simply moves their head, at least one high-resolution holographic segment and at least one low-resolution holographic segment can be shifted to different locations in the field of view using a tracking device. For this purpose, a virtual viewing window generated in relation to the holographic segment to be shifted follows to the corresponding new position in the observer's plane. In this case, the gaze tracking device detects and tracks the observer's gaze as they observe the object or scene. The tracking device also adapts the position of the SLM image, or the position of at least one high-resolution holographic segment and / or at least one low-resolution holographic segment, to the focal position of the observer's eye, as determined by the gaze tracking device.

[0151] According to Figure 3 and 4 In the case of the embodiments shown, a simple structure of the display device is illustrated, wherein the optical system includes switchable or controllable elements, making it possible and achievable to generate at least one high-resolution holographic segment and at least one low-resolution holographic segment.

[0152] Figure 5 Another display device is shown, which generates at least one stereoscopic segment in addition to at least one high-resolution holographic segment and at least one low-resolution holographic segment. In this way, the field of view can be further increased. The segments can be at least partially superimposed or overlapped. In this case, at least one high-resolution holographic segment is at least partially superimposed on at least one low-resolution holographic segment, and these two holographic segments are superimposed on the stereoscopic segment and are entirely located within the stereoscopic segment. Therefore, the lateral region of the field of view is formed by at least one stereoscopic segment. Then, within this stereoscopic segment, an area representing a three-dimensional scene is seen by the observer without focus or three-dimensional perception, but in any case, only at low resolution and without depth perception.

[0153] In other words, the at least one high-resolution holographic fragment is then located inside the low-resolution holographic fragment that is generated and represented. This involves, according to... Figure 3 and 4 The display device typically represents these two segments when generating a large field of view. However, if at least one additional stereoscopic segment is generated and the field of view is thus further increased, then at least one high-resolution holographic segment and at least one low-resolution holographic segment are located inside the additionally generated and represented stereoscopic segment.

[0154] Figure 5 A display device for generating additional stereoscopic segments is shown, according to Figure 3 and 4 The display device then according to Figure 5 Configuration. Figure 5Therefore, it is shown that according to Figure 3 and 4 The aforementioned improvement to the display device.

[0155] like Figure 3 and 4 As can be seen, the display device includes the same illumination device 2, the same SLM 1, and the same optical system 3. The imaging element 4, located near the SLM 1, is now configured to be switchable or controllable. Figure 3 and 4 As shown, a filter plane 11 is also provided. The filter plane 11 can be configured, for example, as a switchable aperture or stop, although in this case it is turned off so that no filtering occurs in the plane 11. Furthermore, the optical system 3 also includes additional switchable imaging elements 12 and 13 and a switchable diffuser 14. Beams from three pixels P1, P2, and P3 are shown again.

[0156] Using this display device, high-resolution holographic segments and low-resolution holographic segments can also be displayed in conjunction with... Figure 3 and 4 The same method is used to generate these holographic fragments. In order to generate these holographic fragments, the additional switchable imaging elements 12, 13 and diffuser 14 are turned off, and the imaging element 4 near SLM 1 (which is configured to be switchable in this case) is turned on.

[0157] To generate at least one stereo segment, imaging element 4 and the two switchable or controllable elements 5 and 6 are turned off, i.e., they are in the OFF state. Conversely, the two additional switchable imaging elements 12 and 13 and the diffuser 14 are turned on, i.e., they are in the ON state. With the assistance of imaging element 12, an enlarged intermediate image of SLM1 is generated at the location of imaging element 13 and the switchable diffuser 14. In this case, diffuser 14 is turned on and thus increases the angular range of light from each pixel of SLM 1.

[0158] Using an additional imaging element 15 (however, it is not configured to be switchable or controllable), the SLM 1 is then imaged at a distance, and an optimal spot 16 is generated in the observer plane 7. However, for clear reasons, the image of the SLM 1 generated at a distance cannot be displayed in the observer plane 7. Figure 5 As shown in the diagram. However, in the observer plane 7, there are approximately parallel ray beams originating from the individual pixels P1, P2, and P3 of SLM 1, which overlap each other to form an optimal spot 16. The stereoscopic segment generated in this way, and thus the resulting field of view 17, is larger in this exemplary embodiment than in the diagram. Figure 4 The field of view is generated by low-resolution holographic fragments.

[0159] For example, in a digital example, a stereo segment would generate a field of view of approximately 133 degrees. For an SLM with 2000 pixels, this corresponds, for example, to a resolution of approximately 15 pixels per degree.

[0160] In this configuration, the at least one stereoscopic segment is positioned fixed within the field of view. This means that the stereoscopic segment will not be displaced to different locations within the field of view by the tracking device.

[0161] High-resolution holographic segments can, for example, have a size of 8×8 degrees, and low-resolution holographic segments can, for example, have a size of 50×50 degrees. Furthermore, stereoscopic segments can have a size of, for example, 120×50 degrees. In this way, a large field of view or wide viewing angle of 120 degrees horizontally and 50 degrees vertically can be generated and realized. In this case, the high-resolution holographic segment can be shifted within the field of view in the horizontal direction and / or in the vertical direction within a range of ±25 degrees by a tracking device. The low-resolution holographic segment can also be shifted within the field of view in the horizontal direction within a range of approximately ±25°, but is set to be fixed in the vertical direction, i.e., not intended to be shifted.

[0162] However, the present invention is not limited to a fixed position for the stereoscopic segment. In other embodiments, the stereoscopic segment may be additionally shifted within the field of view.

[0163] However, if a stereoscopic representation is generated in addition to the holographic representation, then generating a single stereoscopic segment using only the display device is sufficient. This single stereoscopic segment may already generate a large field of view. If at least one stereoscopic segment is generated in a display device for the observer's left eye and in a separate display device for the same observer's right eye, a stereoscopic scene can be represented in three dimensions in the conventional manner of stereoscopic vision by displaying parallax information between the left and right visual fields. Due to the parallax information, the observer can perceive a depth impression even within angular ranges where the focus information of the eyepiece is unavailable. The field of view of a peripheral person also includes areas where information is only visible to one eye, see... Figure 1 In this context, the term stereo segment is often also used to generate segments with such a large field of view that a portion of them is only visible to one eye. The stereo segments for the left and right eyes will then partially, but not completely, overlap.

[0164] The generation of stereoscopic segments is not limited to, for example Figure 5 The configuration of the display device is shown. Since the generation of stereoscopic segments does not require coherent light and can be generated using amplitude SLM, different SLMs and different light sources can typically be used, for example, to generate holographic and stereoscopic segments. These beam paths of holographic and stereoscopic segments can be superimposed, for example, by means of beam splitter elements or mirrors.

[0165] Figure 6 It shows Figure 3 , 4 An alternative display device for 5, which can generate at least one high-resolution holographic segment and at least one low-resolution holographic segment.

[0166] In holographic display devices such as HMDs, imaging of the SLM (Single Lens Model) is typically performed. In the case of segmented multiple imaging of the SLM, an image of the SLM is formed separately in each segment. However, imaging of the SLM at a predetermined distance depends on the specific focal length of the imaging elements used in the optical system and the specific distance of the SLM from these imaging elements. In particular, the imaging beam path and the illumination beam path in the display device are typically not independent of each other. The necessary adjustments to the illumination beam path may sometimes also require changes to the imaging beam path.

[0167] In one configuration of a display device having a planar or flat light guide and at least one imaging element (e.g., a lens element), before coupling light into the light guide, it is necessary, for example, to change the focal length of the at least one imaging element in order to adjust the same position of the virtual viewing window for different segments of multiple imaging of the SLM. If the distance between the SLM and the imaging element is fixed, the imaging position of the SLM changes when the focal length of the imaging element is changed. In the case of segmented multiple imaging of the SLM, a different image plane of the SLM will therefore be formed for each segment.

[0168] In holographic display devices, it is not absolutely necessary for all segments of multiple imaging to have a common image plane. A 3D scene can also be represented continuously at the boundaries of segments with different image planes of an SLM, for example, by adapting the focal length of the sub-holograms of the hologram to the SLM in each segment. However, on the other hand, holographic calculation is simplified when the image planes of the SLM are at least similar for all segments to be generated, i.e., differing by only a few centimeters rather than meters.

[0169] In order to generate high-resolution holographic fragments, according to Figure 6The display device also includes a light guide device 24 in addition to at least one SLM 21, an illumination device having at least one light source 22 illuminating the SLM 21, and an optical system 23. The light guide device 24 includes a light guide configured as curved, two optical coupling devices 25 and 25', and an optical decoupling device 26. One optical coupling device 25 may, for example, include at least one grating element. The other optical coupling device 25' may, for example, include a mirror element for coupling light into the light guide, in which case the mirror element may be configured as a reflective, angled surface arranged in the light guide. The mirror element may also, for example, be configured as a reflective linear grating polarizer, thereby coupling light with only a specific polarization direction into the light guide through the optical coupling device 25'. In this case, the optical decoupling device 26 may include a grating element. The grating element may have a grating period that varies with the light incident position, so as to allow light from the light guide device 24 to be decoupled perpendicularly to the surface of the light guide at each light incident position. In addition to imaging element 27, optical system 23 includes at least one switchable or controllable element in the optical direction following SLM 21. In this exemplary embodiment, the optical system includes at least one switchable or controllable element, indicated herein by reference numeral 28. The at least one switchable or controllable element can be, for example, a lens element whose focal length can be changed by actuation. Alternatively, the switchable or controllable element can also be configured, for example, as a lens system whose total focal length can be changed, for example, as a zoom objective, by changing the distance between the individual lens elements. For example, the switchable or controllable element can also be configured as two diffraction gratings arranged perpendicularly to each other, having controllable and adjustable grating periods in which different lens functions can be programmed. Furthermore, the switchable or controllable element can also be configured, for example, as two lens elements that can be turned on or off. Additionally, a polarization switch 33 can be provided. Optical system 23 generates an intermediate image 30 of light source 22, and thus also generates an intermediate image of the virtual viewing window 29 to be generated. Furthermore, the intermediate image of the virtual viewing window and the intermediate image 30 of the light source 22 are imaged onto the actual virtual viewing window 29 or the observer plane via at least one switchable or controllable element 28. A light guide device 24 located in the display device is arranged in the beam path after the virtual viewing window 29 and the intermediate image 30 of at least one switchable or controllable element 28. This device includes an imaging element 27, and in addition, at least one switchable or controllable element 28 also generates an image of the SLM 21. At least one switchable or controllable element 28 (which images the intermediate image of the virtual observer window or the intermediate image 30 of the light source 22) also contributes to the imaging of the SLM 21. By appropriately selecting the focal length of the imaging element 27 and at least one switchable or controllable element 28, an image of the SLM 21 is formed within the light guide of the light guide device 24.

[0170] It can also be seen that after passing through the optical system 23, the light enters the light guide device 24 through the optical coupling device 25, propagates in the light guide by means of total internal reflection, and is then coupled out by the optical decoupling device 26. In this regard, multiple beams from multiple pixels of the SLM 21 are shown. For each pixel of the SLM 21, in this case, a focal point is formed inside the light guide of the light guide device 24 by means of the optical system 23. This means that the image of the SLM 21 is formed inside the light guide of the light guide device 24.

[0171] The focal length of at least one switchable or controllable element 28 is selected in such a way that a virtual observation window 29 is formed after light is coupled out of the light guide device 24.

[0172] In order to utilize according to Figure 6 The display device generates a high-resolution holographic segment, correspondingly switching or driving at least one switchable or controllable element 28 to a defined driving state. If the at least one switchable or controllable element is, for example, a lens element with a variable focal length, the defined driving state corresponds to a defined focal length that is adjusted. If the at least one switchable or controllable element is configured as a diffraction grating, specific lens functions can also be written into the diffraction grating. If the at least one switchable or controllable element is configured as two lens elements that can be turned on / off, then... Figure 3 Similarly, one of the two switchable lens elements will be switched to the ON state, and the other switchable lens element will be switched to the OFF state. Furthermore, the optical coupling device 25' must be configured to be switchable. Therefore, incident light can be coupled into the optical guide of the optical guide device 24 through one optical coupling device 25, whereby the light must pass through the other optical coupling device 25' before being coupled in. Therefore, in the current case, the optical coupling device 25' must be turned off.

[0173] The optical coupling device 25' itself should be configured to be switchable, or a separate switching should be performed by another element that couples light into or out of the optical coupling device 25'. If the optical coupling device 25' is configured, for example, as a reflective wire grid polarizer (which reflects and then couples light in one polarization direction and transmits and therefore does not couple light in the opposite polarization direction), the separate switching element could be, for example, a polarization switch 33.

[0174] If the optical coupling device 25' transmits light, the light impacts and is coupled to another optical coupling device 25 located behind it.

[0175] As an alternative, for example, the optical coupling device 25' can also be configured as a conventional mirror element, and at least one switchable or tiltable mirror element can be arranged in the optical path between the SLM and the optical coupling device, which guides light into the optical coupling device 25' to couple the light, or guides light through the optical coupling device 25 to prevent the light from being coupled. For example, two optical coupling devices 25 and 25' can also be arranged adjacent to each other and not sequentially in the light guide, in which case at least one switchable or tiltable mirror element can guide light into the optical coupling device 25 or the optical coupling device 25'.

[0176] In order to generate the high-resolution holographic fragment as described above, the optical coupling device 25' is turned off so that light passes through the optical coupling device 25' and is coupled into the light guide through the optical coupling device 25 located behind it.

[0177] To generate a high-resolution holographic fragment, light emitted from the light source 22 of the illumination device impacts the SLM 21 and modulates it according to information from the three-dimensional scene. An image of the SLM 21 is then generated using the optical system 23, specifically the imaging element 27 and the first switchable or controllable element, through which a high-resolution holographic fragment of the field of view 31 can be provided. The image of the SLM 21 formed after the first switchable or controllable element is formed within the light guide device 24. A virtual viewing window 29 is formed in the observer plane during the generation of the high-resolution holographic fragment. Through this virtual viewing window 29, when the observer's eye is located in the observer plane within the area of ​​the virtual viewing window 29, the observer can observe the three-dimensionally generated scene or object in the field of view 31.

[0178] In this way, multiple high-resolution holographic segments can also be generated, which can be combined to increase the high-resolution viewing angle across the entire field of view. For example, to generate multiple high-resolution holographic segments, the number of reflections in the light guide can be adjusted differently for each segment.

[0179] Using according to Figure 6 This display device can also generate at least one low-resolution holographic segment to further increase the field of view. This process will combine... Figure 7 Please provide an explanation.

[0180] Figure 7 The display device shown corresponds in structure to that according to Figure 6 The structure of the display device is such that the same display device used to generate high-resolution holographic fragments is used to generate low-resolution holographic fragments. Therefore, Figure 7The display device shown again includes an illumination device with at least one light source 22, an SLM 21, an optical system 23, and a light guide device 24. The light guide device 24 again includes the same light guide, two optical coupling devices 25 and 25', and an optical decoupling device 26. The light guide is configured to be curved. Also in this case, the optical coupling device 25' may include a mirror element for coupling light into the light guide, in which case the mirror element may be configured to present reflection and be arranged on an inclined surface in the light guide. However, compared to... Figure 6 Instead, the optical coupling device 25' is now switched on, allowing light to couple into the light guide at that location. Therefore, no light impacts the subsequent optical coupling device 25.

[0181] The optical decoupling device 26 may include a grating element. This grating element may have a grating period that varies with the light incident position, allowing light to be coupled out of the light guide device 24 from a surface perpendicular to the light guide at each light incident position. Figure 7 Only one optical decoupling device 26 is shown. However, typically, the light guide may also include separate optical decoupling devices for at least one high-resolution holographic segment and at least one low-resolution holographic segment. These separate optical decoupling devices may, for example, each include at least one switchable grating element that is turned on for at least one high-resolution holographic segment and turned off for at least one low-resolution holographic segment, and vice versa. The optical decoupling device can be configured according to the embodiment in WO 2019 / 012028A1, the disclosure of which is intended to be fully incorporated herein by reference.

[0182] To increase the field of view, light emitted from the illumination device is directed onto the SLM 21, and modulated accordingly by the SLM 21 using information about the object or scene to be represented. This modulated light (which, for clarity, in this case only comes from three pixels P1, P2, and P3 of the SLM 21, and is represented by three beams in different grayscale) is focused onto the optical coupling device 25' by the optical system 23 (i.e., in this case by the imaging element 27 and at least one switchable or controllable element 28). For example, if at least one switchable or controllable element 28 is a lens element with a variable focal length, the focal length is adjusted in such a way that the focal point is formed at the position of the optical coupling device 25' (to match the focal length of the lens). Figure 6(Different values ​​in the image). In this case, the image 30 of the light source 22 is formed in the light direction before at least one switchable or controllable element 28 of the optical system, thereby forming or generating an image of the light source of the irradiation device at that location. By switching or controlling at least one switchable or controllable element 28, particularly by generating a focal point at the location of the optical coupling device 25', light from the individual pixels P1, P2, P3, ... PN of the SLM 21 impacts the light guide device 24, particularly the optical coupling device 25', at average angles, and is coupled into the light guide through the optical coupling device 25'. This is consistent with... Figure 6 There are significant differences, where, due to the corresponding different switching or control states of at least one switchable or controllable element 28, there is no focal point at the position of the optical coupling device; instead, light from all pixels P1, P2, P3, ... PN of the SLM 21 impacts the optical coupling device 25 at the same vertical angle. Therefore, by adjusting the switching or control states of at least one switchable or controllable element 28, the incident angle of light from different pixels onto the light guide device 24 is adjusted in the same way for all pixels of at least one high-resolution holographic segment but differently for all pixels of at least one low-resolution holographic segment. Combined with the different optical coupling devices 25 and 25', this results in different propagation of light in the light guide for at least one high-resolution holographic segment and at least one low-resolution holographic segment. Furthermore, by combining the optical decoupling device 26, this different propagation in the light guide can be used to obtain different sized field of view for at least one high-resolution holographic segment and at least one low-resolution holographic segment. However, in both cases, for all pixels, light is coupled out of the light guide of the light guide device 24 after the same number of reflections.

[0183] for Figure 7The low-resolution holographic segment shown in the diagram is formed by light from the individual pixels P1, P2, P3, ... PN of the SLM 21 striking the light guide device 24, and specifically the optical coupling device 25', at different angles. This determines the coupling angle spectrum of the light. Therefore, the three beams from pixels P1, P2, and P3 strike the optical coupling device 25' at different coupling angles. These three beams are coupled into the light guide via the mirror element of the optical coupling device 25', and then propagate within the light guide at different propagation angles through total internal reflection at the boundary surface of the light guide. In this case, the coupling angle spectrum is approximately 30 degrees in air and approximately 20 degrees inside the light guide. After undergoing a predetermined or predetermined number of reflections, the light in the light guide is then coupled out. In this exemplary embodiment, the coupled beams are coupled out of the light guide after undergoing four reflections each at the inner surface, outer surface, or boundary surface of the light guide via the optical decoupling device 26. Light propagating in or within the light guide device 24 is coupled perpendicularly from the light guide device 24 or the light guide relative to a local surface of the light guide, but is coupled out at different angles on average due to the curvature of the light guide relative to the virtual observation window 29. In this way, the decoupling angular spectrum of the light is defined. From Figure 7 As can be seen, after the light is decoupled from the light guide device 24, a field of view 32, defined laterally by the two outer light beams, can be observed from the focal point F of the beam in the virtual observation window 29. In this case, the generated field of view 32 has an angular range of up to 60 degrees. Therefore, it can be seen that the decoupled angular spectrum of the light is approximately twice the angular spectrum of the light coupled into the light guide. Thus, in this way, a low-resolution holographic segment can be generated, which can be used to generate a large field of view within which a low-resolution holographic segment can be generated.

[0184] In the same scenario, multiple low-resolution holographic fragments can be generated, which can be combined to increase the low-resolution field of view across the entire field of view.

[0185] Therefore, a large field of view is generated by producing at least one high-resolution holographic segment and at least one low-resolution holographic segment, which together form the field of view or the entire field of view. However, the increase in the field of view for the low-resolution holographic segment is not intended to be limited to a curved light guide as shown herein, but can also be used in the same manner in the case of a planar light guide in the light guide device.

[0186] In addition, according to Figure 6 and 7In such a display device, in addition to at least one high-resolution holographic segment and at least one low-resolution holographic segment, at least one stereoscopic segment can be generated to further increase the field of view, or to adapt the field of view generated by the display device to the field of view that an observer will perceive in their natural environment.

[0187] If a combination of stereoscopic segments and at least one holographic segment is provided, an eye-tracking device can also be provided. Using such an eye-tracking and tracking device, the position of the holographic segment in the field of view can be shifted according to the direction of the observer's eye gaze, and the depth of the SLM image can be adapted to the stereoscopic segment and optionally also to the at least one holographic segment. Therefore, in the central region of the retina, the maximum lateral resolution and the entire three-dimensional depth of the represented scene or object are obtained. Outside the central region of the retina, only a two-dimensional scene or object exists in the stereoscopic segment. However, even outside the central region of the retina, possible accommodation-convergence conflicts are avoided by at least one low-resolution holographic segment. In this case, a significant improvement in image quality is achieved when the image content or object to be represented is generated with at least one low-resolution holographic segment covering an angular range greater than the portion covered by the high-resolution holographic segment across the entire field of view.

[0188] Figure 8 It shows according to Figure 6 Or a part of the display device 7, although in this case, the optical coupling device 25' for at least one low-resolution holographic segment and the optical coupling device 25 for at least one high-resolution holographic image are not as in the light guide device 24 Figure 6 and 7 Instead of being arranged sequentially as in the previous examples, they are arranged adjacent to each other. In this exemplary embodiment, both optical coupling devices 25 and 25' include at least one grating element. In this case, at least one switchable or controllable element 28 is configured as a switchable mirror element. If at least one switchable or controllable element 28 is turned off or in an OFF state, light continues to propagate to optical coupling device 25'. If at least one switchable or controllable element 28 is turned on or in an ON state, light is correspondingly deflected to optical coupling device 25 by means of another mirror element 34. In this case, for example, static lens elements 35 and 36 are also used between at least one switchable or controllable element 28 and the corresponding optical coupling device 25 or 25' to focus light in different ways for at least one low-resolution holographic segment and at least one high-resolution holographic segment.

[0189] Of course, the present invention is not intended to be limited to a specific arrangement of the optical coupling device. In other embodiments, for example, the same optical coupling device may also be used for two holographic segments, i.e., for at least one high-resolution holographic segment and at least one low-resolution holographic segment.

[0190] Alternatively, a display device for generating high-resolution holographic segments and / or low-resolution holographic segments and / or stereoscopic segments may be used, the display device comprising at least one light guide device and, particularly in one configuration, using single parallax coding for encoding holograms into at least one SLM, such as... Figure 10 As shown.

[0191] Typically, single disparity coding can be used for either at least one high-resolution holographic segment or at least one low-resolution holographic segment. However, for example, it is also possible to use a combination where at least one high-resolution holographic segment contains full disparity coding and at least one low-resolution holographic segment contains single disparity coding.

[0192] exist Figure 9 and 10 The image shows a display device for low-resolution holographic segments, or optionally also for stereoscopic segments. Essentially, for low-resolution holographic segments, Figure 9 Corresponding to Figure 7 Different spatial views of the display device shown.

[0193] Figure 9 A display device incorporating an optical system is schematically illustrated. This optical system includes a spherical imaging element to generate a two-dimensional light source image for at least one low-resolution holographic segment or stereoscopic segment. In this way, for at least one low-resolution holographic segment or for the stereoscopic segment, a horizontal coupling angle spectrum and a vertical coupling angle spectrum of light are generated. Therefore, pixels P1...PN arranged adjacent to each other (i.e., horizontally adjacent to each other) in the SLM have different horizontal optical coupling angles. Pixels P1...PM arranged vertically adjacent to each other (i.e., vertically adjacent to each other) in the SLM have different vertical optical coupling angles.

[0194] In this configuration, the display device further includes an illumination device with at least one light source 42, an SLM 41, and an optical system 43. The optical system 43 includes a spherical imaging element 46, a field lens 45, and another imaging element 47. A light guide device 48 is arranged after the optical system 43 in the direction of light. In the case of an arrangement having at least one low-resolution holographic segment and at least one high-resolution holographic segment, for example, the spherical imaging element 46 can be configured to be switchable or controllable. Therefore, in this case, it corresponds to... Figure 6 , 7At least one controllable or switchable element 28 in 8. For low-resolution holographic segments, the spherical imaging element 46 shown here is switched or controlled in such a way that it corresponds to the function of a spherical lens element that generates a point focal point and thus a two-dimensional image of the light source at the optical coupling device 49. For example, this spherical lens function can be generated by a controllable lens element, or alternatively, it can also be generated by diffraction gratings arranged perpendicularly to each other, wherein two cylindrical lens functions of the same focal length are written into the diffraction grating.

[0195] However, the same display device can also be used, for example, to generate only a stereoscopic segment. In this case, the spherical imaging element 46 will not need to be configured to be switchable, but can instead be configured, for example, as one or a combination of multiple conventional spherical glass or plastic lens elements.

[0196] The light guide device 48 includes an optical coupling device 49 and an optical decoupling device 50. Similarly, in this case, segments of the field of view associated with the virtual viewing window 51 are generated in the observer plane by the illumination device, SLM 41, optical system 43, and light guide device 48. Optionally, multiple imaging is performed on the SLM 41 to generate multiple segments, which together form a large field of view. The generation of such segments, whether holographic or stereoscopic, in... Figure 9 and 10 None of these are critical and can be implemented according to the disclosure in WO 2018 / 146326 A2, which is fully incorporated herein. Instead, the aim is to focus on generating a light source image in the region where light is coupled to the light guide device.

[0197] To generate a two-dimensional light source image, light emitted from light source 42 of the illumination device is collimated and sent to SLM 41, then modulated using information from the scene to be reconstructed. The modulated light then impacts field lens 45, which focuses light from all pixels of SLM 41 onto a first light source image in Fourier plane 52, where a Fourier transform of the hologram encoded in SLM 41 is formed. In Fourier plane 52, where the first light source image is formed, an additional imaging device 47 is arranged, which can be configured as a lens element and may be optional. Fourier plane 52 may also optionally include an aperture, which can be used to filter the formed diffraction orders. One-dimensional and two-dimensional holograms (encoded onto pixel-level SLMs, with pixels arranged regularly) generate periodic reconstructions in the Fourier plane. To suppress or eliminate periodicity, an aperture that transmits only the desired periodic intervals or only the desired diffraction orders can be used.

[0198] Following the first light source image in the Fourier plane 52, beams of light from each pixel diverge and impact the spherical imaging element 46. The spherical imaging element 46 focuses the incident beams horizontally and vertically to generate the light source image in the optically coupled region or before the light is coupled into the light guide device 48. The optical coupling device 49 of the light guide device 48 is arranged in the region or area where the light source image is located in the display device. In this way, a two-dimensional light source image is generated. The generation of the light source image is shown in more detail in an enlarged view of the region where the light is coupled into the light guide device 48.

[0199] exist Figure 10 The image shows a display device with an optical system, which, instead of a spherical imaging element, now includes at least one cylindrical imaging element to generate a linear light source image. In this way, depending on the orientation of the linear light source image, for at least one low-resolution holographic segment or for a stereoscopic segment, only a horizontally coupled angular spectrum of light or only a vertically coupled angular spectrum of light is generated. Figure 10 The image shows a vertically linear light source. Therefore, pixels P1...PN arranged horizontally adjacent to each other in the SLM have different horizontal optical coupling angles. Pixels P1...PM arranged vertically to each other in the SLM have equal vertical optical coupling angles.

[0200] The display device also includes an illumination device having at least one light source 62, an SLM 61, and an optical system 63. The optical system 63 includes a pair of intersecting cylindrical imaging elements 66. Figure 10 The system includes an imager 63 (shown as one element), a field lens 65, and an additional imaging element 67. A light guide 68 is arranged after the optical system 63 in the light direction. The light guide 68 includes an optical coupling device 69 and an optical decoupling device 70. Similarly, in this case, segments of the field of view associated with the virtual viewing window 71 are generated in the observer plane by the illumination device, the SLM 61, the optical system 63, and the light guide 68. Optionally, multiple imaging is performed on the SLM 61 to generate multiple segments that together form a large field of view. (See also: Regarding...) Figure 9 As already mentioned, the most important part now is not the generation of the most important segments, but the generation of a one-dimensional or linear light source image in the region where light is coupled to the light guide device.

[0201] To generate a linear light source image, light emitted from the light source 62 of the illumination device is collimated and sent to the SLM 61, and then modulated using information from the scene to be reconstructed. The modulated light then impacts the field lens 65, and the field lens 65, based on... Figure 9The first point light source image is generated again in the Fourier plane 72. In this Fourier plane 72, where the first light source image is formed, another imaging device 67 is arranged, which can be configured as a lens element and may be optional. The Fourier plane 72 may also optionally include an aperture, which can be used to filter the formed diffraction orders.

[0202] Following the first light source image in the Fourier plane 72, the beams of the individual pixels of the SLM 61 diverge and impact the paired cross-cylindrical imaging elements 66. These paired cross-cylindrical imaging elements 66 have different focal lengths in the horizontal and vertical directions, and therefore, focus is generated only in the region where the light is coupled to the light guide device 68 in the horizontal direction. Thus, a linear light source image is generated in the region of light coupling or before the light is coupled to the light guide device 68. To generate at least one high-resolution holographic segment and at least one low-resolution holographic segment, and optionally at least one stereoscopic segment, the paired cross-cylindrical imaging elements 66 can be configured to be controllable. Then, for at least one low-resolution holographic segment or for at least one stereoscopic segment, different focal lengths are adjusted by switching or driving states of the paired cross-cylindrical imaging elements 66 so that focus is generated only in the region where the light is coupled to the light guide device 68 in the horizontal direction. For at least one high-resolution holographic segment, the paired cross-cylindrical imaging elements 66 can then have different focal lengths; however, in general, the focal lengths can also be different in the horizontal and vertical directions. After light is decoupled from light guide device 68 by light decoupling device 70, another light source image is formed. Light coupling device 69 of light guide device 68 is arranged in the region or area of ​​the linear light source image in the display device. The generation of the linear light source image is shown in more detail in a magnified view of the region where light is coupled to light guide device 68.

[0203] It can be used according to Figure 9 and 10 Two display devices are used to generate a decoupling angle spectrum of light from a light guide device, which is increased compared to the coupling angle spectrum of light. The coupling angle spectrum of light is intended to represent a spectrum generated such that beams of light from individual pixels of the SLM impact the light guide device and couple at an average angle relative to the surface of the light guide device. The decoupling angle spectrum of light is intended to represent a spectrum generated such that beams of light propagating in the light guide device couple out of the light guide device at an average angle relative to the observer region, which can be understood as a virtual viewing window or as the optimal spot of light during the generation of stereoscopic segments.

[0204] In particular, Figure 9In the display device, the decoupling angle spectrum of light can be magnified both horizontally and vertically compared to the coupling angle spectrum. However, for the observer, a field of view is formed that is configured as a rhombus rather than a rectangle.

[0205] On the other hand, Figure 10 In display devices, the decoupling angle spectrum of light increases only in the horizontal direction compared to the coupling angle spectrum. This is because a large horizontal field of view is particularly important to the observer.

[0206] This display device can be combined with other known possibilities to generate an increased vertical field of view.

[0207] For example, a first light guide device rotated 90 degrees can be used, which comprises, for example, a planar, non-curved light guide. At the coupling point of the first light guide device, the light source image is generated only in the vertical direction. Using the first light guide device, the decoupling angle spectrum from the first light guide device increases in the vertical direction compared to the coupling angle spectrum. The light coupled from the first light guide device is horizontally focused by another imaging element onto the light coupling position of the second light guide device. Using the second light guide device, a decoupling angle spectrum is generated in the horizontal direction, which increases compared to the coupling angle spectrum. By combining the two light guide devices, the entire rectangular field of view is then generated.

[0208] Furthermore, combinations of embodiments or exemplary embodiments are possible. Finally, it should be particularly noted that the above exemplary embodiments are for describing the claimed teachings only, but do not limit the teachings to the exemplary embodiments.

Claims

1. A display device for representing two-dimensional and / or three-dimensional objects or scenes, comprising: - at least one illumination device for substantially emitting coherent light, - at least one spatial light modulation device for modulating the incident light, and - at least one optical system, wherein the at least one optical system is provided for multiple imaging of the at least one spatial light modulation device and for generating virtual viewing windows depending on the number of images of the at least one spatial light modulation device, wherein the individual images of the at least one spatial light modulation device are combined with each other as segments and form a field of view, wherein the field of view comprises at least one high-resolution holographic segment and at least one low-resolution holographic segment, - wherein the at least one optical system is provided for generating at least one virtual viewing window in connection with the generation of the at least one high-resolution holographic segment, the size of the virtual viewing window of the at least one high-resolution holographic segment being equal to or greater than the size of an eye pupil of an observer observing the objects or the scenes in the field of view, - wherein the at least one optical system is provided for generating at least one virtual viewing window in connection with the generation of the at least one low-resolution holographic segment, the size of the virtual viewing window of the at least one low-resolution holographic segment being smaller than the size of an eye pupil of an observer observing the objects or the scenes in the field of view; and - wherein the optical system comprises two switchable or controllable optical elements, a first switchable or controllable optical element being switchable or controllable in order to generate the at least one high-resolution holographic segment and a second switchable or controllable optical element being switchable or controllable in order to generate the at least one low-resolution holographic segment, for adjusting the different large quotient D / p of the distance D of the image of the at least one spatial light modulation device to the observer plane and the pixel pitch p of the image of the pixels of the at least one spatial light modulation device in order to change the size of the virtual viewing window and the size of the field of view.

2. The display device of claim 1, wherein the size of the at least one virtual viewing window of the at least one high-resolution holographic segment lies in the range of 6 mm to 15 mm.

3. The display device of claim 1, wherein the size of the at least one virtual viewing window of the at least one low-resolution holographic segment lies in the range of 0.5 mm to 2 mm.

4. The display device of claim 1, wherein a plurality of low-resolution holographic segments and / or a plurality of high-resolution holographic segments comprise different sizes of virtual viewing windows.

5. The display device of claim 1, wherein the generation of the virtual viewing window of the at least one low-resolution holographic segment and the generation of the virtual viewing window of the at least one high-resolution holographic segment are provided in the observer plane at the same location.

6. The display device of claim 5, wherein the virtual viewing window providing the at least one low-resolution holographic segment at least partially overlaps the virtual viewing window of the at least one high-resolution holographic segment.

7. The display device of claim 1, wherein at least two spatial light modulating devices are provided, one spatial light modulating device being provided for generating the at least one high-resolution holographic segment and another spatial light modulating device being provided for generating at least one low-resolution holographic segment.

8. The display device of claim 7, wherein the one spatial light modulating device for generating the at least one high-resolution holographic segment and the another spatial light modulating device for generating the at least one low-resolution holographic segment are differently configured.

9. The display device of claim 1, wherein a hologram in single parallax encoding is written into the at least one spatial light modulating device in order to generate the at least one high-resolution holographic segment and the at least one low-resolution holographic segment.

10. The display device of claim 1, wherein a hologram in full parallax encoding is written into the at least one spatial light modulating device in order to generate the at least one high-resolution holographic segment and a hologram in single parallax encoding is written into the at least one spatial light modulating device in order to generate the at least one low-resolution holographic segment.

11. The display device of claim 1, wherein at least one filter device is provided for eliminating higher diffraction orders present in the observer plane.

12. The display device of claim 1, wherein a line-of-sight tracking device and at least one tracking device are provided.

13. The display device of claim 12, wherein the at least one tracking device is provided for tracking the virtual viewing window of the at least one high-resolution holographic segment and / or for tracking the virtual viewing window of the at least one low-resolution holographic segment.

14. The display device of claim 12, wherein the at least one tracking device is provided for adapting the position of the image of the at least one spatial light modulating device or the position of the at least one high-resolution holographic segment and / or the at least one low-resolution holographic segment to the focal position and the line-of-sight direction of the observer's eye determined by the line-of-sight tracking device.

15. The display device of claim 12, wherein the line-of-sight tracking device is provided for detecting the pupil position in the observer's eye and for tracking the line-of-sight of the observer viewing the object or the scene.

16. The display device of claim 1, wherein the field of view comprises the at least one high-resolution holographic segment, the at least one low-resolution holographic segment and at least one stereoscopic segment.

17. The display device of claim 16, wherein the at least one high-resolution holographic segment, the at least one low-resolution holographic segment and the at least one stereoscopic segment are arranged partially or completely overlapping in the field of view.

18. Display device as claimed in claim 1, wherein at least one light guiding device is provided, which comprises a light guide, at least one light coupling device and at least one light decoupling device, the light propagating within the light guide by reflection at the boundary surfaces of the light guide and being decoupled from the light guide by the light decoupling device after a limited number of reflections of the light at the boundary surfaces of the light guide.

19. Display device as claimed in claim 18, wherein the at least one optical system and the at least one light guiding device are provided for generating at least one high resolution holographic segment and at least one low resolution holographic segment and, if required, at least one stereoscopic segment, the high resolution holographic segment, the low resolution holographic segment and, if required, the stereoscopic segment together forming a field of view within which a three-dimensional scene or a three-dimensional object can be represented.

20. Display device as claimed in claim 18 or 19, wherein the imaging of the at least one spatial light modulating device is provided by the at least one light guiding device and the at least one optical system.

21. Display device as claimed in claim 18 or 19, wherein the light source image of at least one light source arranged in the at least one illumination device is provided in the light path by the optical system before the light is coupled into the light guiding device.

22. Display device as claimed in claim 21, wherein the at least one light coupling device is arranged at or in the area of the position of the light source image.

23. Display device as claimed in claim 18 or 19, wherein the optical system comprises two cylindrical optical elements which are arranged crosswise with respect to each other.

24. Display device as claimed in claim 23, wherein the optical system is provided for generating a linear light source image in the light path before the light is coupled into the light guiding device.

25. Method for generating a large field of view within which a scene or an object is represented with different resolutions by at least one illumination device, at least one spatial light modulating device and at least one optical system, wherein: - the at least one spatial light modulating device modulates incident light with the required information of the scene or the object, - the at least one optical system multiplies the at least one spatial light modulating device and generates a virtual viewing window depending on the number of images of the at least one spatial light modulating device, the individual images of the at least one spatial light modulating device being combined as segments with each other and forming a field of view, at least one high resolution holographic segment and at least one low resolution holographic segment being generated for forming the field of view, - wherein the at least one optical system is provided for generating at least one virtual viewing window in conjunction with the generation of the at least one high resolution holographic segment, the size of the virtual viewing window of the at least one high resolution holographic segment being equal to or greater than the size of the eye pupil of an observer observing the object or the scene in the field of view. ​ ​ ​ - wherein said at least one optical system is provided for generating at least one virtual observation window in combination with generating said at least one low resolution holographic segment, the size of the virtual observation window of said at least one low resolution holographic segment being smaller than the size of an eye pupil of an observer observing said object or said scene in said field of view, and - wherein said optical system comprises two switchable or controllable optical elements, a first switchable or controllable optical element being switchable or controllable for generating said at least one high resolution holographic segment and a second switchable or controllable optical element being switchable or controllable for generating said at least one low resolution holographic segment, for adjusting the different large quotient D / p of the distance D of the image of said at least one spatial light modulating device to the plane of the observer and the pixel pitch p of the image of the pixels of said at least one spatial light modulating device for changing the size of the virtual observation window and the size of the field of view.

26. The method according to claim 25, wherein in providing two switchable or controllable optical elements in said optical system, for generating said at least one high resolution holographic segment, a first switchable or controllable optical element is switched or controlled and a second switchable or controllable optical element is not switched or controlled, for generating said at least one low resolution holographic segment, said second switchable or controllable optical element is switched or controlled and said first switchable or controllable optical element is not switched or controlled.

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