MANUFACTURING METHOD, DEVICE AND HOLOGRAM PLATE

Abstract

In one embodiment, the method serves to produce a holographic plate (2) and comprises: - Providing a recording geometry optic (4), - Providing a photopolymer (3), and - simultaneous illumination of the photopolymer (3) with a first laser beam (L1) and a second laser beam (L2), thereby generating a holographic pattern (22) in the photopolymer (3), wherein - only the first laser beam bundle (L1) passes through the recording geometry optics (4), - a light entry surface (43) of the recording geometry optics (4) for the first laser beam bundle (L1) points away from the photopolymer (3) and a light exit surface (44) of the recording geometry optics (4) is facing the photopolymer (3), - the recording geometry optics (4) comprises a lens array (41) that divides the first laser beam bundle (L1) into a plurality of partial beam bundles (LS), and - each of the partial beam bundles (LS) illuminates the largest part of the sample area (20).

Description

[0001] A method for producing a holographic plate, a device for carrying out such a method, and a fanning hologram plate are described.

[0002] Publication US 2011 / 0 200 918 A1 refers to a light-sensitive composition for recording volume holograms.

[0003] The publication by G. Kopitkovas et al., “Fabrication of beam homogenizers in quartz by laser micromachining” in Journal of Photochemistry and Photobiology A: Chemistry, Volume 166, Numbers 1 to 3, August 12, 2004, pages 135 to 140, refers to a manufacturing process for producing a sample.

[0004] One problem to be solved is the provision of a holographic plate for a portable augmented reality (AR) display, such as a head-mounted AR display, with improved field of view quality.

[0005] This problem is solved, inter alia, by a method, a device, and a fanning hologram plate according to the independent claims. Exemplary further developments are the subject of the dependent claims.

[0006] In the method described here, for example, a scanning geometry optic is used to manufacture the fanning hologram plate, which includes a lens array. Using the lens array, a first laser beam is split into a multitude of partial beams, with each partial beam illuminating a sample area of ​​the fanning hologram plate completely or almost completely. This allows high image quality to be achieved in the display with the fanning hologram plate across the entire field of view (FoV).

[0007] According to at least one embodiment, the method includes the step of providing a photopolymer. The photopolymer is photosensitive, particularly when illuminated with near-ultraviolet, visible, and / or near-infrared radiation. Near-ultraviolet refers to the spectral range between 320 nm and 419 nm, visible radiation refers to the spectral range between 420 nm and 780 nm, and near-infrared radiation refers to the spectral range between 781 nm and 1.3 µm. For example, the photopolymer is configured to change its refractive index upon exposure. Some possible photopolymers are described, for example, in US 2011 / 0200918 A1, see in particular paragraphs 35 to 57; the disclosure of that document is incorporated by cross-reference.

[0008] According to at least one embodiment, the method includes the step of providing a recording geometry optic.

[0009] For example, the imaging geometry optics are a transmission optic. Alternatively, the imaging geometry optics can also be a reflection optic or a combination of transmission and reflection optics. For example, the imaging geometry optics are designed for near-ultraviolet radiation, visible light, and / or near-infrared radiation.

[0010] According to at least one embodiment, the method comprises the step of simultaneously illuminating the photopolymer with a first laser beam and a second laser beam. This type of illumination causes the first and second laser beams to interfere with the photopolymer, resulting in an intensity pattern. Based on this intensity pattern, for example, a local refractive index and / or a crosslinking rate in the photopolymer is determined.

[0011] This exposure process creates a holographic pattern in a patterned area of ​​the photopolymer; the illuminated photopolymer forms the holographic plate. It is possible that the photopolymer requires post-processing after exposure with the first and second laser beams, for example, curing. This can be done thermally, for example, by heating the photopolymer, or by exposing the photopolymer to near-infrared radiation, such as laser radiation. The latter, however, preferably has no significant effect on the holographic pattern, although slight shrinkage may occur; for example, the shrinkage rate due to heating is less than 5% or less than 2%. This shrinkage rate can be taken into account when designing the interference pattern with the first and second laser beams.

[0012] According to at least one embodiment, only the first laser beam passes through the receiving optics. Therefore, the second laser beam does not need to interact optically with the receiving optics. "Passing through" refers to the optical interaction, that is, the beam shaping and / or deflection. In a transmission optic, the first laser beam can actually be transmitted through the receiving optics; in a reflection optic, "passing through" means that the first laser beam is reflected at least once by the receiving optics.

[0013] According to at least one embodiment, a light-entry surface of the receiving geometry optics for the first laser beam faces away from the photopolymer, and a light-emission surface of the receiving geometry optics faces the photopolymer. It is possible that the light-entry surface and the light-emission surface are the only optically active surfaces of the receiving geometry optics. These surfaces can be refracting or reflective, or a mixture thereof. It is possible that these surfaces are the only optically relevant surfaces of the receiving geometry optics. Alternatively, there can be one or more optically relevant intermediate surfaces between the light-entry surface and the light-emission surface, for example, additional refracting surfaces for shaping the first laser beam.

[0014] According to at least one embodiment, the recording geometry optics comprise a lens array that divides the first laser beam into several partial beams. The term "lens array" can refer to refracting lenses, but also to an array of mirrors. Since a lens array is optically equivalent to a mirror array in this respect, only the term "lens array" will be used in the following, although a mirror array could also be meant.

[0015] For example, the number of partial beams is at least five, or at least ten, or at least 20, or at least 50. Alternatively or additionally, the number of partial beams is at most 10. 4 or at most 10 3 or at most 200 or at most 64.

[0016] According to at least one embodiment, each of the partial beams illuminates the greater part or all of the pattern area. For example, this means that at least 50%, 70%, 85%, 95%, or 98% of the pattern area is illuminated by each of the multiple partial beams. Therefore, each or most of the partial beams may partially or completely overlap with all or most of the other partial beams. "Greatest part" may mean at least 60% or at least 90%.

[0017] In at least one embodiment, the method serves to produce a holographic plate and comprises the following steps, for example in the order given: - Providing a recording geometry optic, - Providing a photopolymer, and - simultaneous exposure of the photopolymer with a first laser beam and a second laser beam, thereby generating a holographic pattern in a pattern area of ​​the photopolymer, wherein the exposed photopolymer forms the holographic plate, wherein - only the first laser beam passes through the recording geometry optics, - a light entry surface of the recording geometry optics for the first laser beam beam is facing away from the photopolymer and a light exit surface of the recording geometry optics is facing towards the photopolymer, - the recording geometry optics comprise a lens array that splits the first laser beam into several partial beams, and - each of the partial beam bundles exposes most of the pattern area; optionally, each of the partial beam bundles has a focal point between the pattern area and the light entry surface, a secondary optical element is a converging lens and is located in a plane of the focal points of the partial beam bundles, and the lens array is composed of a multitude of spherical lenses.

[0018] Therefore, the method described here serves, for example, to improve the overlap of subpupillary images in a multi-fan hologram. The hologram is used, for example, as an AR pancake combiner and can be used in a near-eye display for AR or virtual reality (VR).

[0019] One technical problem solved by this method is the avoidance of missing portions of the field of view in each partial pupil of a viewing area, also known as the eyebox. Such missing portions can be caused by the recording geometry of the optics. When a lens array is used to generate the partial pupils, each lens forms a point, each of which represents a point-to-point hologram to be recorded. In a basic configuration, each of these points is identical, with the light beams from the spatially separated points propagating at the same angular extent. However, on the holographic material, these beams do not completely overlap unless very careful procedures are followed. Consequently, only those parts of the hologram, and therefore the image, where the light from the multiplexed points completely overlaps, transmit the image information to all partial pupils.Outside the center of the image, the information is only passed on to some of the final partial pupils.

[0020] Especially with displays positioned close to the eye, such as those supporting three-dimensional (3D), AR, and VR representations, the size of the eyebox is a key factor for the user experience. The eyebox refers specifically to the volume within which the eye, when positioned, has an acceptable view of the image.

[0021] For example, the technical features used here to solve this problem include using a series of optical components to create spatially separated point sources and converge their light onto the same area of ​​the hologram for recording. This can be done in various ways.

[0022] For example, some embodiments use a lens array to generate the point sources, followed by a large lens with a positive power field to converge the light rays onto the hologram at the desired distance. Other embodiments employ a single double-sided optical element, comprising a single high-power lens on one side and a lens array on the other; compared to the aforementioned embodiments, this solution requires only a single optical element. Still other embodiments employ a single element in which only one side is optically shaped and the other side is flat; in this case, the lenses are shaped to both bundle and focus the light; these lenses could be considered free-form.In comparison to the aforementioned embodiments, the latter offer a single element in which only one side is optically active, thus improving holographic recording because fewer surfaces reflect and scatter, and such elements may also be less expensive or more accurate to manufacture because they are optically one-sided.

[0023] As already mentioned, the converging partial beam bundles enable each point of the hologram, and thus the image, to be transmitted to all partial pupils of the eyebox.

[0024] According to at least one embodiment, each of the partial beams has a focal point between the photopolymer, i.e., the pattern area, and the light-entry surface. The focal point is not necessarily a focal point of the respective partial beam, i.e., a focal spot with a beam waist whose diameter is determined by its wavelength and its overall angular extent. For example, the focal point is located in a cross-section of the respective partial beam where the beam in question has its minimum diameter, in particular a minimum full-width diameter at half the height of the maximum, FWHM. Thus, part of the power of the partial beam is located outside the FWHM diameter.

[0025] According to at least one embodiment, each of the partial beams illuminates at least 98% or the entire pattern area. Thus, each of the partial beams overlaps completely or almost completely with all other partial beams. "Almost completely" can mean that the overlap is at least 90% or at least 98% of the area of ​​the smaller of the two overlapping partial beams.

[0026] According to at least one embodiment, the light-entry surface is convexly shaped. That is, the light-entry surface has a converging effect.

[0027] According to at least one embodiment, the light-entry surface is planar. Therefore, the light-entry surface cannot refract the first laser beam, or only to a negligible extent. For example, the first laser beam is a parallel bundle of rays that strike the light-entry surface perpendicularly.

[0028] According to at least one embodiment, the lens array is located at the light-emitting surface. Alternatively, the lens array could also be located at the light-intake surface, or the lens array could be distributed such that the light-intake surface and the light-emitting surface together form the lens array.

[0029] According to at least one embodiment, an optical axis of the light-emitting surface and / or the recording geometry optics is oriented perpendicular to the photopolymer, i.e., to the pattern area. Therefore, the lens array can be arranged parallel to the photopolymer and / or the pattern area. This can also mean that the optical axis of the light-emitting surface and / or the recording geometry optics and an optical axis of the pattern area are parallel to each other, congruent, or identical; in this case, for example, the pattern area and / or the photopolymer and / or the holographic plate can be curved.

[0030] According to at least one embodiment, the lens array comprises a plurality of spherical lenses. Alternatively, the lens array can be composed of a plurality of parabolic, elliptical, or cylindrical lenses. Thus, a cross-sectional area of ​​the lenses in the lens array, viewed through an optical axis of the respective lens, corresponds to a portion of a circle, parabola, ellipse, or cylinder. Alternatively or additionally, this can also mean that the lenses have at least two different planes of mirror symmetry.

[0031] According to at least one embodiment, the lens array comprises a plurality of freeform lenses. This means, for example, that the surface of the lenses in the lens array, viewed in cross-section through the optical axis of the respective lens, does not correspond to a part of a circle, parabola, ellipse, or cylinder. Alternatively or additionally, this can also mean that the lenses have only one or no plane of mirror symmetry. In any cross-section through a center point of the respective lens, the lenses can be asymmetric.

[0032] It is possible that the lens array combines freeform lenses and lenses with at least two different mirror symmetry planes.

[0033] According to at least one embodiment, the focal points of the partial beams are located between the light-emitting surface and the photopolymer. Thus, the focal points are located between the imaging geometry optics and the pattern area.

[0034] According to at least one embodiment, the recording geometry optics consist of a single optical element. That is, the only optically relevant surface(s) of the recording geometry optics can be the light entry surface and / or the light exit surface.

[0035] According to at least one embodiment, the recording geometry optics are composed of a plurality of individual optical elements. For example, the recording geometry optics are formed from at most five, or at most three, or at most two optically relevant elements, such as lenses.

[0036] According to at least one embodiment, the recording geometry optics are composed of a primary optical element and a secondary optical element. The recording geometry optics are therefore formed from exactly two optical elements.

[0037] According to at least one embodiment, the primary optical element carries the light-entry surface and the lens array. The secondary optical element is located between the primary optical element and the photopolymer.

[0038] According to at least one embodiment, the secondary optical element is a converging lens. For example, the secondary optical element is a plano-convex or biconvex lens.

[0039] According to at least one embodiment, the secondary optical element is located in a surface, such as a plane, containing the focal points of the partial beams. This means, for example, that a principal plane of the secondary optical element, or a surface of the secondary optical element facing the first optical element or the light-emitting surface, lies within the surface of the focal points. The surface of the focal points, which is preferably a plane, can be a virtual surface.

[0040] According to at least one embodiment, the diameter of the pattern area is at least 1 cm or at least 2 cm. Alternatively or additionally, this diameter is at most 10 cm or at most 6 cm.

[0041] According to at least one embodiment, the feature size of the holographic pattern is at least 0.1 µm or at least 0.2 µm. Alternatively or additionally, this feature size is at most 0.7 µm, at most 0.4 µm, or at most 0.3 µm. The feature size refers, for example, to a minimum distance between maxima and minima of a refractive index and / or a geometric structuring of the holographic pattern within the pattern area.

[0042] According to at least one embodiment, the first laser beam and / or the second laser beam each have a wavelength of maximum intensity between 350 nm and 870 nm inclusive. Alternatively, the first laser beam and / or the second laser beam are near-ultraviolet and / or near-infrared radiation.

[0043] According to at least one embodiment, the finished holographic plate is a volume-phase hologram plate, or VPH plate for short. Therefore, the finished holographic plate comprises a pattern of low- and high-refractive-index regions, specifically within a volume of the holographic plate. For example, the holographic plate is designed for visible light, such as blue, green, and red light. For example, blue light refers to wavelengths between 440 nm and 485 nm, green light to wavelengths between 520 nm and 555 nm, and red light to wavelengths between 600 nm and 685 nm.

[0044] Additionally, a device is specified. Using this device, a holographic plate is produced in a manner described in connection with at least one of the embodiments mentioned above. Features of the device are therefore also disclosed for the method, and vice versa.

[0045] In at least one embodiment, the device comprises means for carrying out the above-mentioned method, for example the recording geometry optics, a first laser for generating the first laser beam bundle, a second laser for generating the second laser beam bundle and a support arrangement for handling the photopolymer and thus the holographic plate.

[0046] Additionally, a fanning hologram plate is specified. The fanning hologram plate is produced using the method and / or a device as described in connection with at least one of the embodiments mentioned above. Features of the fanning hologram plate are therefore disclosed for both the method and the device, and vice versa.

[0047] In at least one embodiment, the fanning hologram plate comprises - a holographic plate, which is a volume phase hologram plate, which has a holographic pattern in a pattern area, - a polarization-dependent mirror onto which the holographic plate is applied, and - a delay plate comprising a quarter-wave plate or configured to act as such, wherein the polarization-dependent mirror is arranged between the holographic plate and the delay plate, wherein - the fanning hologram plate is set up for augmented reality and / or virtual reality glasses, - the holographic pattern includes a multiple fan-out hologram, - the diameter of the pattern area as seen from above on the holographic plate is between 1 cm and 6 cm inclusive, and the structure size of the holographic pattern is between 0.2 µm and 0.7 µm inclusive, and - the holographic pattern is provided for a multitude of subpupils, with each subpupil being configured for a full or near-full field of view.

[0048] A method, a device, and a fanning hologram plate described herein will be explained in more detail below with reference to exemplary embodiments and the drawings. Elements that are identical in the individual figures are marked with the same reference numerals. However, the relationships between the elements are not shown to scale; rather, individual elements may be exaggerated for clarity.

[0049] In the characters: Fig. Figure 1 is a schematic block diagram of an embodiment of a method described herein for the production of fanning hologram plates, Fig. Figure 2 is a schematic sectional view of an embodiment of a device for manufacturing the fanning hologram plates described here. Fig. Figure 3 is a schematic cross-sectional view of a process step of a modification of a process for manufacturing a hologram plate. Fig. Figures 4 to 7 are schematic sectional views of process steps of exemplary embodiments of processes for the production of fanning hologram plates described here. Fig. 8 and Fig. Figure 9 shows schematic sectional views of exemplary embodiments of the fanning hologram plates described here. Fig. Figure 10 is a schematic perspective view of an application of an embodiment of a fanning hologram plate described herein, Fig. Figure 11 is a schematic perspective view of an embodiment of a portable augmented reality display with a fanning hologram plate described herein, and Fig. 12 and Fig. Figure 13 are schematic sectional views of exemplary embodiments of portable augmented reality displays with the fanning hologram plates described here.

[0050] Fig. Figure 1 schematically shows an exemplary method for the production of holographic plates.

[0051] In process step S1, a recording geometry optic 4 is provided. Optionally, process step S1 can include the provision of a device 1 that comprises all necessary fixed equipment for carrying out the process.

[0052] Then, in process step S2, a photopolymer 3 is provided. For example, the photopolymer 3 is placed in the device 1 and adjusted if necessary.

[0053] In the subsequent process step S3, the photopolymer 3 is illuminated simultaneously with a first laser beam L1 and a second laser beam L2, see for example also below. Fig. 2. This creates a holographic pattern 22 in a pattern area 20 of the photopolymer 3.

[0054] For example, after final processing, the exposed photopolymer 3 yields the holographic plate 2. This final processing can be carried out, for example, by thermal and / or chemical treatment. This final processing is not shown in the figures.

[0055] In Fig. Section 2 explains process step S3 and device 1 in more detail. Device 1 comprises a first laser 81 and a second laser 82 to generate the first laser beam L1 and the second laser beam L2. The lasers 81 and 82 can have the same wavelength of maximum intensity or different wavelengths of maximum intensity. In the case of a single wavelength of maximum intensity, it is possible to use a common laser source for both beams L1 and L2, which are guided along optically different paths.

[0056] For handling the photopolymer 3 and the resulting holographic plate 2, which is, for example, a volume-phase hologram plate, the device 1 includes a support arrangement 83. The support arrangement 83 allows the photopolymer 3 and the resulting holographic plate 2 to be inserted, precisely positioned, completed, and / or removed from the device 1. The support arrangement 83 can include holders, motors, conveyor belts, or the like, which are not shown. A top surface 30 of the photopolymer 3 faces away from the support arrangement 83.

[0057] The recording geometry optics 4 is in Fig. 2 is represented as an abstract component. However, the receiving geometry optics 4 comprises a light entry surface 43 facing away from the photopolymer 3 and an opposite light exit surface 44 facing the photopolymer 3. For example, an optical axis A of the receiving geometry optics 4 is oriented perpendicular to the photopolymer 3.

[0058] The first laser beam L1, consisting of parallel beams and parallel to the optical axis A, strikes the light-entry surface 43. The first laser beam L1 illuminates the light-entry surface 43 extensively. That is, the light-entry surface 43 is practically completely illuminated by the first laser beam L1. The second laser beam L2 propagates at a distance from the receiving optics 4 and is not optically controlled by the receiving optics 4. The second laser beam L2 can thus directly and completely illuminate a sample area 20 of the photopolymer 3. For example, the sample area 20 has a diameter D, which can be approximately one inch.

[0059] If the pattern area 20 is not circular, then the diameter D is: D = (4A / π) 1 / 2, where A is the area of ​​the pattern region 20; this applies analogously to all other diameters mentioned here. Preferably, the pattern region 20 is circular or nearly circular. “Nearly circular” can mean that the ratio of the longest chord to the shortest chord through the centroid of the pattern region 20 is at most 2, 1.5, or 1.2.

[0060] The recording geometry optics 4 comprise means for dividing the planar first laser beam L1 into a plurality of partial beams LS. For this purpose, the recording geometry optics 4 can comprise a lens array 41 or the like, which is arranged in Fig. 2 is not shown. The partial beams LS each propagate towards the top surface 30. Furthermore, each of the partial beams LS illuminates the pattern area 20 completely or almost completely. Accordingly, at the top surface 30, each of the partial beams LS overlaps with all other partial beams LS as well as with the second laser beam L2. In this way, a desired holographic pattern 22 can be generated across the entire pattern area 20.

[0061] To achieve an overlap of all partial beam bundles LS, at least some of the individual optical axes of the partial beam bundles LS are not parallel to the optical axis A of the imaging geometry optics 4 as a whole. For example, all individual optical axes of the partial beam bundles LS are inclined in the direction of the overall optical axis A; this can apply to all individual optical axes that are not adjacent to or congruent with the overall optical axis A. The individual optical axes can be the directions along which a maximum intensity of the respective partial beam bundle LS is emitted and / or can be a center line of a radiation cone of the respective partial beam bundle LS.

[0062] In contrast, the partial beam bundles LS in the Fig. In the modified version of the device shown, individual optical axes arranged parallel to each other result from a planar lens array 41 composed of two-dimensionally arranged spherical lenses 45. Therefore, the partial beam bundles LS only partially overlap.

[0063] Consequently, there is poor overlap on the VPH, resulting in missing portions of the field of view in each resulting partial pupil when the holographic plate is used in an AR / VR display, as shown below. For high image quality in an AR / VR display, overlap of all or most of the multiple beams is required so that all points of the image are displayed in all partial pupils of a viewing area. With the in Fig. 2. The method and device shown therein allow for improved image acquisition, enabling significant overlap of the partial beam bundles LS, so that the full field of view is present in all partial pupils of the visual area.

[0064] In Fig. Figure 4 shows an embodiment of the receiving optics geometry 4 in more detail. This receiving optics geometry 4 is composed of a primary optical element 47 and a secondary optical element 42. The light-intake surface 43 is located on the primary optical element 47, and the light-outtake surface 44 is located on the secondary optical element 42. Furthermore, the primary optical element 47 has a first intermediate surface 48, which is spaced apart from the light-intake surface 43, and the secondary optical element 42 has a second intermediate surface 49, which is spaced apart from the light-outtake surface 44.

[0065] For example, the primary optical element 47 is shaped as a lens array 41, wherein either the light-entry surface 43 or the first intermediate surface 48 or both can form the lenses 45 of the lens array 41. For example, the lenses 45 are spherical lenses.

[0066] For example, the secondary optical element 42 is a biconvex lens. Therefore, both the light-exiting surface 44 and the second intermediate surface 49 can be curved.

[0067] With the aid of the lenses 45, each partial beam LS has a focal point 5. All focal points 5 can lie in a common plane or approximately there. For example, this common plane is a principal plane of the secondary optical element 42, which faces the first optical element 47.

[0068] For example, the distance between the light-emitting surface 43 and the top surface 30 of the photopolymer 3 is at least 10 mm and / or at least 25% of the diameter D of the pattern area 20. Alternatively or additionally, this distance is at most 80 mm and / or at most 300% of the diameter D of the pattern area 20. It is possible that the diameter of the first laser beam L1 at the light-entry surface 43 is at least 50% and / or at most 200% of the diameter D of the pattern area 20.

[0069] Thus, according to Fig. 4 a field lens with positive refractive power, which is arranged near the focal points 5 of the lenses 45, the direction of the light without significantly increasing the optical power.

[0070] Furthermore, what is for the Fig. 1 to 3 also apply to the Fig. 4 apply, and vice versa.

[0071] In Fig. Figure 5 shows another embodiment of the recording geometry optics 4. In this case, the recording geometry optics 4 is also formed from the primary and secondary optical elements 42, 47, as in Figure 5. Fig. 4. According to Fig. In the second intermediate surface 49, only the light-entry surface 43 is equipped with the lens array 41, and the first intermediate surface 48 is planar. The secondary optical element 47 is a plano-convex lens, in which the second intermediate surface 49 is curved and the light-exit surface 44 is flat. The focal points 5 are located near the second intermediate surface 49, for example, at a distance of at most 0.1 D or at most 0.05 D. It is possible that the focal points 5 are located on a convex surface, and it is possible that the convex surface and the second intermediate surface 49 have the same type of curvature, that is, positive or negative curvature, while the absolute value of the radius of curvature of the second intermediate surface 49 may be smaller than that of the convex surface.

[0072] Furthermore, what is for the Fig. 1 to 4 also apply to Fig. 5 apply, and vice versa.

[0073] In the exemplary embodiment of the Fig. 6 The receiving geometry optics 4 is a single optical element. Therefore, there are no intermediate surfaces between the light entry surface 43 and the light exit surface 44, so that reflections or disturbances at such surfaces can be avoided.

[0074] For example, the light-entry surface 43 is convex and the light-emission surface 44 carries the lens array 41. In this configuration, it is possible that the lens array 41 is composed of spherical lenses 45. As shown in the Fig. 4 and Fig. 5. The individual optical axes of the lenses 45 can be aligned parallel to each other and parallel to the overall optical axis A. Since the radiation of the first laser beam L1 strikes the lenses 45 in slightly different directions due to the curved light entry surface 43, the partial beams LS propagate in different directions.

[0075] Furthermore, what is for the Fig. 1 to 5 also apply to the Fig. 6 apply, and vice versa.

[0076] According to Fig. 7, the recording geometry optics 4 is also a single optical element, as in Fig. 6. However, the light-entry surface 43 is planar, and the light-entry surface 44 comprises the lens array 41. The lenses 46 are freeform lenses. Unlike the previous embodiments, there are no separate optical surfaces for defining the directions of the partial beams LS and for focusing the partial beams LS; instead, the lenses 46 on the single optically active surface 44 serve both to define the directions of the partial beams LS and to focus the partial beams LS.

[0077] Here too, the partial beam bundles LS have focal points 5 between the light-emitting surface 44 and the photopolymer 3. For example, as in Fig. 6, the focal points 5 are closer to the light-emitting surface 44 than to the photopolymer 3. Furthermore, in Fig. 7 to recognize that the focal points 5 do not have to be exact, but can also be blurred.

[0078] Furthermore, what is important for the Fig. 1 to 6 also apply to Fig. 7 apply, and vice versa.

[0079] In the Fig. Figures 4 to 7 show the imaging geometry optics 4 as refractive optics. However, it is also possible that all these imaging geometry optics 4 could be implemented analogously as reflection optics.

[0080] In the Fig. 8 and Fig. Figure 9 shows fanning hologram plates 10 with the finished holographic plate 2. Optionally, the fanning hologram plates 10 include a polarization-dependent mirror 54 and a delay plate 56, with the holographic plate 2 located at the polarization-dependent mirror 54. The components 54 and 56 can form a support 55 for the holographic plate 2.

[0081] According to Fig. 8. Holographic plate 2 is a volume-phase hologram plate, or VPH plate for short. Holographic plate 2 thus comprises a multitude of areas with low and high refractive indices, symbolized by a pattern of lines. These refractive index modulations result in the holographic pattern 22. For example, one feature size of holographic pattern 22 is approximately 0.2 µm. According to Fig. 9 the holographic pattern 22 is realized through a surface structure.

[0082] Both types of holographic patterns 22, as seen in the Fig. 8 and Fig. The examples shown in 9 can be applied to all embodiments of the holographic plate 2.

[0083] Furthermore, the following applies to the Fig. 8 and Fig. 9 the same as for the Fig. 1 to 7, and vice versa.

[0084] The optical function of holographic plate 2 is in Fig. Figure 10 is described in more detail. The holographic plate 2 is designed such that it selectively scatters or fans out incident light depending on the angle of incidence. In particular, the holographic plate 2 is designed such that it scatters or fans out image light I at higher angles of incidence, but allows ambient light from an opposite direction to pass through without scattering or fanning it. This can be achieved by the holographic pattern 22 of the holographic plate 2.

[0085] In Fig. Figure 11 shows a portable AR display 7. The display 7 comprises a support frame 71 with a central axis A7 and an optical system in the form of an axis-offset retinal scanning display mounted on the support frame 71. The optical system includes an image generator in the form of a scanning laser projector 72, which emits the image light I, and an eyepiece 73. The projector 72 is mounted offset from the central axis A7.

[0086] When the support frame 71 is mounted on a user's head and the eyepiece 73 is within the user's field of vision, the eyepiece 73 transmits ambient light from a scene located in front of the eyepiece 73, through the eyepiece 73, to the user's eye 75, which is located behind the eyepiece 73. The projector 72 projects the linearly polarized image light I, which defines an image, over the eyepiece 73 toward the user's eye 75. The linearly polarized image light I can comprise one or more wavelengths, such as one or more of the red, green, or blue wavelengths.

[0087] The eyepiece 73 reproduces the image defined by the projected image light I multiple times at a multitude of positions in a plane 74 at the user's eye 75 in order to extend the viewing area of ​​the portable AR display 7.

[0088] Fig. Figure 12 shows the optical system used, which reproduces an image defined by three different linearly polarized principal rays forming the image light I at three different positions in the plane 74 at the eye of a user 75 in order to create an extended field of view for each principal ray of the projected image light I.

[0089] The eyepiece 73 comprises the fanning hologram plate 10 with the holographic plate 2, which serves as an optical spreader for fanning out the projected image light I into scattered image light. The eyepiece 73 further contains an optical combiner in the form of a "reflective pancake" that collimates the scattered image light and reflects the collimated light back through the holographic plate 2 to form collimated light that spreads into plane 74 to form the extended viewing area in plane 74.

[0090] The reflector 76 has a first or front side facing the scene and a second or rear side facing the holographic plate 2. On the front side is a circular polarizer, and on the rear side a dichroic reflective layer designed to strongly reflect in one or more narrow spectral bands, each narrow spectral band arranged around a corresponding wavelength of the image light I, but allowing light at other wavelengths of ambient light to pass through. The fanning hologram plate 10 includes the polarization-dependent mirror 54, and the delay plate 56, which comprises a quarter-wave plate or is configured to act as such.

[0091] The polarization-dependent mirror 54 and the dichroic reflective layer of the optical reflector 76 form an optical cavity, with the retardation plate 56 arranged within this optical cavity. Furthermore, the polarization-dependent mirror 54 and the optical reflector 76 are arranged such that the polarization-dependent mirror 54 is located in an optical path between the holographic plate 2 and the optical combiner 76. The retardation plate 56 and the optical combiner 76 are separated from each other, for example, by an air gap.

[0092] During operation, the ambient light incident on the front of the optical combiner 76 is effectively combined with the collimated light exiting the rear of the optical combiner 76. Specifically, the circular polarizer imparts circular polarization to the ambient light, and this circularly polarized ambient light falls upon the front of the optical combiner 76, which is defined by the dichroic reflective coating. The dichroic reflective coating allows the wavelengths of the circularly polarized ambient light that lie outside one or more narrow spectral bands, in which the dichroic reflective coating is highly reflective, to pass to the retarder plate 56.The delay plate 56 converts the circularly polarized ambient light into linearly polarized ambient light, which is aligned along a polarization transmission axis of the reflector 54, so that the reflector 54 transmits the linearly polarized ambient light in the direction of the extended viewing area.

[0093] The holographic plate 2 spreads, for example, fans or separates, the linearly polarized main beam of the image light I coming from the scanning laser projector 72 into, for example, three different directions to form three different linearly polarized beams of the spread image light I, which strike the back of the optical combiner 76. The first linear polarization of each of the beams of the spread image light is aligned along the polarization transfer axis of the polarization-dependent mirror 54, so that the mirror 54 transmits each of the linearly polarized beams of the spread image light to the delay plate 56. The delay plate 56 converts the polarization of each beam from the first linear polarization to a first circular polarization.Each beam then propagates from the retardation plate 56 to the optical reflector 76, is passed through it and then reflected at the dichroic reflective layer to form a corresponding beam of the first reflected light with a second circular polarization opposite to the first circular polarization.

[0094] Each beam of the first reflected light propagates through the reflector 76 back to the retarder plate 56. The retarder plate 56 converts the polarization of each beam into a second linear polarization, which is orthogonal to the first linear polarization and to the polarization transfer axis of the reflector 54. Accordingly, the polarization-dependent mirror 54 reflects each beam of the first reflected light back to the retarder plate 56 as a corresponding beam of the second reflected light. The retarder plate 56 then converts the polarization of each beam of the second reflected light from the second linear polarization to the second circular polarization.Each beam of the second reflected light then spreads from the retardation plate 56 to the reflector 76, is passed through it and then reflected at the dichroic reflective layer to form a corresponding beam of the third reflected light with the first circular polarization.

[0095] Each beam of the third reflected light propagates through the reflector 76 back to the retarder plate 56, which converts the polarization of each beam of the third reflected light from the first circular polarization to the first linear polarization, which is aligned parallel to the polarization transfer axis of the reflector 54. Accordingly, the reflector 54 transmits each beam of the third reflected light to form collimated light, which travels back through the holographic plate 2 as collimated light, defining the extended viewing area.

[0096] The optical combiner provides a folded optical path for the image light I. By using the optical combiner, the thickness of the eyepiece 73 can be reduced, resulting in a more compact eyepiece 73.

[0097] According to Fig. 13 is the fanning hologram plate 10, and therefore the holographic plate 2 is planar. However, it is also possible that the fanning hologram plate 10 is curved, like the reflector 76.

[0098] Furthermore, the same applies as in Fig. 12 also for Fig. 13 apply, and vice versa.

[0099] The ones related to the Fig. The holographic plates 1 to 11 shown can all be used analogously for the portable AR displays 7 of the Fig. 12 and Fig. 13 can be used.

[0100] A corresponding portable AR display 7 is also disclosed in patent application GB 2 202 622.3, the disclosure content of which is hereby included by reference.

[0101] The invention described here is not limited by the description using exemplary embodiments. Rather, the invention encompasses every new feature and also every combination of features, which in particular includes every combination of features from the claims, even if this feature or this combination itself is not expressly specified in the claims or exemplary embodiments.

[0102] This patent application claims priority from German patent application 10 2022 120 907.5, the disclosure content of which is hereby incorporated by reference. Reference symbol list 1 Device 2 holographic plates (volume phase hologram (VPH) plates) 20 Sample area 22 holographic patterns 3 Photopolymer 30 Top 4. Image geometry optics 41 lens array 42 secondary optical element 43 Light entry area 44 Light emission area 45 spherical lens 46 Freeform lens 47 primary optical element 48 first intermediate surface 49 second intermediate surface 5 Focal Point 54 polarization-dependent mirrors 55 carriers 56 delay plate 7 portable augmented reality display 71 support frames 72 Scanning laser projector 73 Eyepiece (eyepiece) 74 Level at the user's eye, field of vision 75 eyes of a user 76 curved optical combiners 81 first laser 82 second laser 83 Support arrangement 9 incompletely illuminated photopolymer 10 Fanning Hologram Plate A optical axis of the recording geometry optics A7 Central axis of the support frame B. Structural size of the holographic pattern D Diameter of the sample area I Image light L1 first laser beam bundle L2 second laser beam LS partial beam bundle of the first laser beam bundle S process step QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 2011 / 0 200 918 A1 [0002, 0007] GB 2 202 622.3

[0100] DE 10 2022 120 907.5

[0102] Cited non-patent literature

[0000] G. Kopitkovas et al., “Fabrication of beam homogenizers in quartz by laser micromachining” in Journal of Photochemistry and Photobiology A: Chemistry, Volume 166, Numbers 1 to 3, 12 August 2004, pages 135 to 140

[0003]

Claims

[1] A method for producing a holographic plate (2) comprising the following steps: - Providing a recording geometry optics (4), - providing a photopolymer (3), and - simultaneously illuminating the photopolymer (3) with a first laser beam (L1) and a second laser beam (L2) and thereby generating a holographic pattern (22) in a pattern area (20) of the photopolymer (3), so that the illuminated photopolymer (3) produces the holographic plate (2), wherein - only the first laser beam (L1) passes through the recording geometry optics (4), - a light entry surface (43) of the recording geometry optics (4) for the first laser beam (L1) faces away from the photopolymer (3) and a light exit surface (44) of the recording geometry optics (4) faces the photopolymer (3), - the recording geometry optics (4) comprises a lens array (41) which divides the first laser beam (L1) into several partial beams (LS), - each of the partial beams (LS) illuminates a major part of the pattern area (20), - each of the partial beams (LS) has a focal point (5) between the pattern area (20) and the light entry surface (43), - a secondary optical element (42) is a converging lens and is arranged in a plane of the focal points (5) of the partial beams (LS), and - the lens array (41) is composed of a plurality of spherical lenses (45). [2] Method according to the preceding claim, wherein each of the partial beams (LS) illuminates the entire pattern area (20). [3] Method according to one of the preceding claims, wherein the light entry surface (43) is convex. [4] Method according to claim 1 or 2, wherein the light entry surface (43) is planar. [5] Method according to one of the preceding claims, wherein the lens array (41) is arranged on the light exit surface (44), wherein an optical axis (A) of the recording geometry optics (4) is aligned perpendicular to the photopolymer (3). [6] Method according to one of the preceding claims, wherein the focal points (5) of the partial beams (LS) are located between the light exit surface (44) and the photopolymer (3). [7] Method according to one of the preceding claims, wherein the recording geometry optics (4) is composed of a plurality of individual optical elements. [8] Method according to the preceding claim, wherein the recording geometry optics (4) is composed of a primary optical element (47) and the secondary optical element (42), wherein the primary optical element (47) carries the light entry surface (43) and the lens array (41), wherein the secondary optical element (42) is arranged between the primary optical element (47) and the photopolymer (3). [9] Method according to one of the preceding claims, wherein a diameter (D) of the pattern area (20) is between 1 cm and 6 cm inclusive, wherein a structure size (B) of the holographic pattern (22) is between 0.2 µm and 0.7 µm, wherein the first laser beam (L1) and the second laser beam (L2) each have a wavelength of maximum intensity between 350 nm and 870 nm, and wherein the finished holographic plate (2) is a volume phase hologram plate. [10] Device (1) with means for carrying out the method according to one of the preceding claims. [11] Fan-out hologram plate (10) intended for the device (1) according to the preceding claim, and comprising: - a holographic plate (2) which is a volume phase hologram plate and which contains a holographic pattern (22) in a pattern area (20), - a polarization-dependent mirror (54) to which the holographic plate (2) is applied, and - a retardation plate (56) comprising a quarter-wave plate or arranged as such, and the polarization-dependent mirror (54) is arranged between the holographic plate (2) and the retardation plate (56), wherein - the fan-out hologram plate (10) is designed for augmented reality glasses and / or virtual reality glasses, - the holographic pattern (22) comprises a multi-fan hologram, - a diameter (D) of the pattern area (20) seen in plan view of the holographic plate (2) is between 1 cm and 6 cm, - a structural size (B) of the holographic pattern (22) is between 0.2 µm and 0.7 µm, and - the holographic pattern (22) is configured for a plurality of partial pupils, each partial pupil being configured for a full field of view or for a nearly full field of view.

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