Optical waveguide element, method for preparing an optical waveguide element and optical arrangement

Abstract

An optical waveguide element (10) is proposed that provides optical isolation of the waveguide element in a stacked optical arrangement. The waveguide element has a first surface (12) and a second surface (14) opposite the first surface (12), an input coupling region (16) configured to couple image light into the waveguide element (10), and a viewing region (22) comprising an output coupling region (20) configured to couple the image light propagated in the optical waveguide element (10) out of the waveguide element (10).To provide optical isolation, at least one of the first surface (12) and the second surface (14) has a reflective coating (26, 26') applied in a circumferential region (24) of the at least one of the first and second surfaces (12, 14) outside the viewing area (22) and outside the coupling area (16).

Description

[0001] The invention relates to an optical waveguide element for a stacked optical arrangement. The invention further relates to a corresponding method for preparing an optical waveguide element, and further to a corresponding optical arrangement comprising an optical waveguide element.

[0002] Smart glasses or data glasses can feature head-mounted displays, such as waveguide-based displays, to project virtual images to one or more eyes of a viewer, but they must also function as ophthalmic glasses, i.e., correct the viewer's vision according to an ophthalmic prescription. For this purpose, head-mounted displays can incorporate an ophthalmic or prescription lens (so-called Rx lens) in a stacked arrangement with a waveguide in front of and / or behind the waveguide. Smart glasses or data glasses equipped with one or more ophthalmic or prescription lenses can be referred to as Rx-enabled smart glasses or data glasses.

[0003] In general, a waveguide, for example a planar waveguide, is designed to guide virtual image light, provided by an image sensor, to an output coupling structure via total internal reflection (TIR). At this point, the image light is coupled from the waveguide to an eyebox, directed towards the eye or eyes of the viewer. In spectacles, the waveguide must therefore be subjected to conditions that do not impair the TIR of light rays within the waveguide between its surfaces designated for reflection; that is, the surfaces of the waveguide designated for reflection must be optically isolated. This can be achieved, for example, by a sufficiently large change in the refractive index or reflectivity of the surfaces designated for reflection.

[0004] It is known to create an air or vacuum gap around the surfaces of the waveguide intended for reflection, i.e., around a waveguide portion of the waveguide, to allow the TIR of the image light within the waveguide portion by arranging separators between adjacent surfaces of the waveguide and optical components surrounding it, e.g., an Rx lens stacked with the waveguide, as described in US 11,243,398 B2. US 11,243,398 B2 also addresses the problem of TIR violations in areas where separators overlap the waveguide portion. This problem frequently occurs because the separators may be (and usually are) made of a material with a refractive index close to or equal to that of the waveguide.WO 2024 / 008593 A1 discloses that the separating agents have an adhesive layer, which makes the fabrication of the stacked optical arrangement consisting of a waveguide and a lens simpler and less expensive. The disadvantage of the latter solution is a violation of the TIR in the region of the adhesive-waveguide interface. US 11,243,398 B2 solves this problem by means of a specific, more complex design of the separating agents, which are configured as a perimeter sealing arrangement between adjacent surfaces of a waveguide and a lens, and which have a section that exhibits locally reduced optical coupling compared to the rest of the sealing arrangement in order to preserve the TIR within the waveguide. This section may include a mirror film as an optical isolating agent, which is applied to the waveguide surface and a sealing-waveguide interface.Such optical isolation, known from US 11 243 398 B2, appears to be effective, but its local application as part of the sealing and separating arrangement makes the entire manufacturing process more complex and essentially eliminates the advantages of simple adhesive release agents as disclosed in WO 2024 / 008 593 A1.

[0005] Therefore, there is a need for a simple and effective technique to provide optical isolation of the adhesive-waveguide and / or separating agent-waveguide interface in stacked optical arrangements, e.g., a stack of a waveguide and a lens.

[0006] It is an object of the present invention to provide an optical waveguide element for a stacked optical arrangement which eliminates the disadvantages of the prior art described above and enables optical isolation of the optical waveguide element for a stacked optical arrangement in a simple and effective technique.

[0007] A further object of the present invention is to provide a corresponding method for preparing such an optical waveguide element.

[0008] A further object of the present invention is to provide a corresponding stacked optical arrangement comprising such an optical waveguide element and at least one further optical component.

[0009] According to a first aspect of the invention, an optical waveguide element for a stacked optical arrangement is provided, comprising a first surface and a second surface opposite the first surface, an input region configured to couple image light into the waveguide element, and a viewing region comprising an output region configured to couple the image light propagated in the optical waveguide out of the waveguide, wherein at least one of the first surface and the second surface has a reflective coating applied in a circumferential region of the at least one of the first and second surfaces outside the viewing region and outside the input region.

[0010] According to the invention, an optical waveguide element is provided which has a reflective coating, in particular a highly reflective coating, also referred to as a mirror coating, on at least one of its first and second surfaces, which is intended for reflecting the image light propagating in the waveguide element, wherein the reflective coating is applied in a circumferential region of the waveguide element, wherein the coupling region and the viewing region, including the coupling region, are not coated with the reflective coating. In contrast to the prior art, the reflective coating is part of the optical waveguide element itself, i.e., the reflective or mirror coating is not applied when separating agents are created, e.g., to provide an air gap during the assembly of a stacked optical arrangement, since the mirror coating is not part of the separating agents.The mirror coating is applied during the manufacturing of the waveguide or as an additional surface treatment of the waveguide before the stacked optical assembly is assembled. Because the coating is part of the optical waveguide element itself—that is, the mirror coating is created before and independently of any assembly processes of a stacked optical assembly—it allows the use of significantly simpler and more cost-effective coating techniques.

[0011] In other words, the mirror coating creates a preparation of a universal, pre-insulated waveguide element for a stacked optical arrangement that is compatible with any assembly techniques and any means of creating air gaps in optical arrangements.

[0012] Since the mirror coating is applied to a circumferential area of ​​the first and / or second surface outside the viewing area and outside the coupling area, it is not necessary to provide the reflective coating with any transparency. Furthermore, the coating does not impair the transparency function within the viewing area of, for example, eyeglasses, and a slight lack of transparency at the edges will either be imperceptible or cause no significant discomfort to a viewer. In addition, the mirror coating on the circumference of the waveguide will prevent the unintentional coupling of any external / parasitic light into the waveguide, thereby further reducing stray light and improving the quality of the projected virtual image.

[0013] In one embodiment, the reflective coating extends along the entire circumferential length of at least one of the first and second surfaces of the waveguide element.

[0014] This embodiment is advantageous because the mirror coating along the entire circumference of the waveguide prevents unintentional coupling of any external / parasitic light from any direction into the waveguide, thus further improving the quality of the projected virtual image. Furthermore, if the waveguide element is combined with an optical component, such as a lens bonded to the waveguide element, and / or if the optical arrangement is sealed along its entire circumference, the reflective coating maintains the TIR conditions along the entire circumference of the optical arrangement.The same applies if separating agents (which may also be referred to as spacer structures) are present in the optical arrangement to provide a gap between the waveguide element and the optical component, extending along the entire circumferential length of the optical arrangement.

[0015] In this respect and in a further embodiment, the at least one of the first and second surfaces can have the reflective coating in a region of the at least one of the first and second surfaces which is configured for bonding the waveguide to another optical component of the stacked optical arrangement, e.g. a lens, and / or wherein the at least one of the first and second surfaces can have the reflective coating in a region of the at least one of the first and second surfaces which is configured for separating the waveguide from the other optical component in order to provide a gap between the waveguide and the other optical component.

[0016] Materials used for bonding, sealing, and / or release agents typically have a refractive index similar to that of the waveguide element material, which could lead to image light coupling into the bonding material, sealing material, and / or release agent material. The reflective coating of the waveguide element according to the invention ensures the prevention of light loss in these areas of the optical waveguide element.

[0017] In a further embodiment, the first surface of the waveguide element can have a first reflective coating in a circumferential region of the first surface outside the viewing area and outside the coupling area, and a second surface of the waveguide element can have a second reflective coating in a circumferential region of the second surface outside the viewing area.

[0018] This embodiment is advantageous when the optical waveguide element is provided for a stacked optical arrangement in which an optical component is bonded to both the first and second surfaces of the optical waveguide element, such as a first lens bonded to the first surface of the waveguide element and a second lens bonded to the second surface of the waveguide element. The reflective coatings on both the first and second surfaces of the waveguide element ensure the maintenance of TIR conditions on both surfaces.

[0019] In conjunction with the previously mentioned embodiment, a further embodiment provides that the first reflective coating of the first surface of the waveguide element and a second reflective coating of the second surface of the waveguide element extend along the entire circumferential length of the first and second surfaces.

[0020] The advantage of this embodiment is the same as that described above, when a reflective coating is provided only on one of the first and second surfaces of the waveguide element.

[0021] According to a further aspect of the present invention, a method for preparing an optical waveguide element for a stacked optical arrangement is provided, comprising: Providing the optical waveguide element with a first surface and a second surface opposite the first surface, an input coupling area configured to couple image light into the waveguide element, and a viewing area including an output coupling area configured to couple the image light propagated in the optical waveguide element out of the waveguide element. Applying a reflective coating to at least one of the first and second surfaces in a circumferential region of the at least one of the first and second surfaces outside the viewing area and outside the coupling area.

[0022] As described above, the reflective coating, particularly a highly reflective coating also known as a mirror coating, can be applied during waveguide fabrication or as an additional surface treatment of the waveguide before assembling the optical waveguide element with an optical component to form a stacked optical assembly. This means the mirror coating is not applied when a release agent is created to provide an air gap during the assembly of a stacked optical assembly, as the reflective coating is not part of the release agent. Because the reflective coating is created before and independently of any assembly process of a stacked optical assembly, it allows for the use of much simpler and more cost-effective coating techniques.Furthermore, the proposed mirror coating can be effectively used in combination with any techniques and means for assembling a stacked optical arrangement, as well as any techniques and means for creating and maintaining an air gap in the stacked optical arrangements; that is, it is compatible with any type of release agent, bonding agent, or sealing agent, whether known or to be developed in the future. As such, the proposed mirror coating enables the preparation of a universal, pre-insulated waveguide element for a stacked optical arrangement that is compatible with any assembly techniques and any means for creating air gaps in optical arrangements.

[0023] In one embodiment, the application of the reflective coating involves applying the reflective coating along the entire circumferential length of at least one of the first and second surfaces.

[0024] In a further embodiment, the application of the reflective coating comprises the application of the reflective coating in a region of at least one of the first and second surfaces, which is configured for bonding the waveguide element to a further optical component of the stacked optical arrangement, and / or wherein the reflective coating is applied in a region of at least one of the first and second surfaces of the waveguide element, which is configured for separating the waveguide element from the further optical component in order to provide a gap between the waveguide element and the further optical component.

[0025] In a further embodiment, the application of the reflective coating can comprise the application of a first reflective coating on the first surface of the waveguide element in a circumferential region of the first surface outside the viewing area and outside the coupling area, and the application of a second reflective coating on the second surface of the waveguide element in a circumferential region of the second surface outside the viewing area.

[0026] In the context of the previous embodiment and in a further embodiment, the application of the reflective coating can comprise the application of the first reflective coating along the entire circumferential length of the first surface of the waveguide element and the application of the second reflective coating along the entire circumferential length of the second surface of the waveguide element.

[0027] The embodiments of the method according to the invention described above have the same advantages as the corresponding embodiments of the waveguide element according to the invention.

[0028] In a further aspect of the present invention, a stacked optical arrangement is provided, comprising an optical waveguide element according to the first aspect and at least one optical component, wherein the at least one optical component is connected, directly or by means of an adhesive layer, to which at least one of the first and second surfaces of the waveguide element is connected in the circumferential region having the reflective coating.

[0029] In one embodiment of the stacked optical arrangement according to the invention, the optical arrangement can have a gap between the optical component and at least one of the first and second surfaces of the waveguide element within the viewing area.

[0030] The gap can be filled with natural air, but it can equally be filled with any gaseous fluid other than natural air. The pressure in the air gap can be very low, such that it can also be considered a vacuum gap. In another embodiment, the air gap can be filled with a low-index material that ensures the condition of total reflection as provided by an air or vacuum gap, whereby the low-index material itself may, but need not, exhibit certain adhesive properties.

[0031] In a further embodiment of the stacked optical arrangement according to the invention, the optical component can be connected to the first surface of the waveguide element, and the optical arrangement can further comprise a further optical component which is connected, directly or by means of an adhesive layer, to the second surface of the waveguide element in the circumferential region which has the reflective coating.

[0032] In a further embodiment, in the context of the previous embodiment, the stacked optical arrangement can have a gap between the further optical component and the second surface of the waveguide element within the viewing area.

[0033] In a further embodiment of the stacked optical arrangement according to the invention, the at least one optical component can be a lens, such as a prescription lens (Rx lens). The further optical component, if present, can also be an Rx lens.

[0034] It should be apparent to those skilled in the art that the stacked optical arrangement according to the invention can have the corresponding embodiments and can provide the same advantages as described above with reference to the waveguide element according to the invention.

[0035] Further features and advantages of the invention will become apparent from the following description and the accompanying drawings.

[0036] Exemplary embodiments of the invention are shown in the drawings and are described below with reference to the drawings. The drawings show: Fig. 1 schematically a top view of a surface of an optical waveguide element for a stacked optical arrangement according to an embodiment of the present invention; Fig. 2 schematically the top view of a surface of an optical waveguide element for a stacked optical arrangement according to a further embodiment of the present invention; Fig. 3 schematically a cross-section of an optical arrangement according to an embodiment of the present invention, which has an optical waveguide element according to an embodiment of the present invention; Fig. 4 an enlarged view of section A of the optical arrangement in Fig. 3; Fig. 5A schematically shows a cross-section of an optical waveguide element according to an embodiment in order to illustrate a method for preparing the optical waveguide for a stacked optical arrangement; Fig. 5B schematically shows a stage of manufacturing the stacked optical arrangement with the optical waveguide element of Fig. 5A; Fig. 5C schematically shows another stage in the fabrication of the stacked optical arrangement with the optical waveguide element of Fig. 5A; and Fig. 5D a final stage of manufacturing a stacked optical arrangement with the optical waveguide element of Fig. 5A.

[0037] Fig. Figure 1 schematically shows a top view of an optical waveguide element designated by reference numeral 10, according to an embodiment of the present invention. The optical waveguide element 10 is configured for a stacked optical arrangement, as shown below with reference to Fig. 3, Fig. 4 to Fig. 5 will be described. A stacked optical arrangement comprising the optical waveguide element 10 can be used in a head-mounted display, e.g., in data glasses. As such, and as described in Fig. As shown in Figure 1, the optical waveguide element can have a contour or shape similar to a spectacle lens.

[0038] With additional reference to Fig. 3 and Fig. Figure 4 shows that the optical waveguide element has a first surface 12 and an opposing second surface 14. Both surfaces 12 and 14 can be planar surfaces.

[0039] The optical waveguide element 12 further comprises an input coupling area 16 configured to couple image light (not shown) into the waveguide element 10. The image light may be emitted from a display (not shown). Image light coupled into the optical waveguide element 10 via the input coupling area 16 propagates within the optical waveguide element 10 along a waveguide region 18 to an output coupling area 20, which is configured to couple the light propagated within the optical waveguide element 10 outwards towards an eyebox to project the image to the user's eye. Within the waveguide region 18, the image light propagates to the environment, e.g., air, via total internal reflection (TIR) ​​at interfaces of the waveguide element 10. These interfaces are provided by the surfaces 12 and 14 of the optical waveguide element 10.

[0040] The output area 20 is contained within a viewing area 22 of the optical waveguide element 10. The optical waveguide element 10 is transparent within the viewing area 22, meaning that a user can see the real environment in front of the optical waveguide element 10 through the optical waveguide 10. The optical waveguide element 10 is therefore suitable for a head-mounted display of a head-mounted augmented reality device.

[0041] In an exemplary circumferential region 24 of the waveguide element 10, the optical waveguide element 10 has a reflective coating, in particular a highly reflective coating 26, which is also referred to as a mirror coating. The reflective coating 26 is in Fig. 1 illustrated by hatching. The reflective coating 26 is provided in the circumferential region 24 of the surface 12 of the waveguide element 10, but it is not provided in the viewing region 22, which is surrounded by the circumferential region 24, nor is it provided in the coupling region 16.

[0042] The area where the reflective coating is applied to the surface 12 of the optical waveguide element 10 is, in particular, an area where the TIR conditions are, for example, due to a bonding material such as an adhesive used to bond the optical waveguide element 10 to an optical component such as a lens (as in Fig. 3 and Fig. 4 shown), is used, or by separating means designed to separate the optical waveguide element 10 from an optical component bonded to the optical waveguide element 10, in order to create a gap between the optical waveguide element 10 and the optical component (as shown in Fig. 3 and Fig. 4 shown) to provide, and / or may be disturbed by a sealing material to seal the stacked optical arrangement which includes the optical waveguide element 10 and an optical component.

[0043] Fig. Figure 2 schematically shows a top view of an optical waveguide element 10 according to a further embodiment of the present invention, which is a modification of the embodiment of Fig. 1 is. While in the embodiment of Fig. 1. The reflective coating 26 extends in the circumferential region 24 along the entire circumferential length of the surface 12. In the embodiment of, the reflective coating 26, which is again illustrated by hatching, extends to the optical waveguide element 10. Fig. 2 in the circumferential region 24 only over a part of the circumferential length of the optical waveguide element 10. The section of the circumferential region 24 of the optical waveguide element 10 in the embodiment of Fig. 2 is part of the waveguide region 18, in which the TIR conditions are improved by, for example, a bonding material, such as an adhesive, used to connect the optical waveguide element 10 to an optical component, such as a lens (as in Fig. 3 and Fig. 4 shown), is used, or by separating means designed to separate the optical waveguide element 10 from an optical component bonded to the optical waveguide element 10 in order to provide a gap between the optical waveguide element 10 and the optical component (as shown in Fig. 3 and Fig. 4 shown), and / or may be disturbed by a sealing material to seal the stacked optical arrangement which includes the optical waveguide element 10 and an optical component.

[0044] Fig. Figure 3 schematically shows an embodiment of an optical arrangement 50 in a cross-section. Fig. Figure 4 shows an enlarged view of section A in Fig. 3. Elements of the optical arrangement 50 in Fig. 3 and Fig. 4, which are identical, comparable or similar to elements in the embodiments of Fig. 1 and Fig. 2 are, are with the same reference symbols as in Fig. 1 and Fig. 2 provided.

[0045] The optical arrangement 50 comprises an optical waveguide element 10, which, like the optical waveguide element 10, has a first surface 12 and a second surface 14 as described above. The optical arrangement 50 further comprises a first optical component 30 and a second optical component 32. The optical component 30 is connected to the first surface 12 of the waveguide element 10, and the second optical component 32 is connected to the second surface 14 of the optical waveguide element 10. Both optical components 30 and 32 can be configured as prescription lenses (Rx lenses), i.e., the optical components 30 and 32 have an optical power in accordance with the user's eye prescription. The optical component 30 can be a so-called push lens, and the optical component 32 can be a so-called pull lens.A pull lens serves to correct the viewer's vision, according to an ophthalmological prescription, for aberrations of the image transmitted by the optical waveguide element 10, which is perceived by the user as a virtual image. A push lens serves to correct the viewer's vision, according to an ophthalmological prescription, for aberrations of an image of an object in the real world, as seen by the user through the optical arrangement 50. In the present embodiment, the push lens 30, in combination with the pull lens 32, corrects the image of an object in the real world as seen by the user through the optical arrangement 50.

[0046] It is understood that in other embodiments of the present invention the optical arrangement 50 may comprise only the optical component 30 or only the optical component 32.

[0047] The optical arrangement 50 has a bonding structure 34 for bonding the optical component 30 to the optical waveguide element 10. The bonding structure 34 can be an adhesive. The optical arrangement 50 further has a separating structure 36 to provide a gap 35 between the optical component 30 and the optical waveguide element 10. The gap 35 maintains the TIR conditions for the image light propagating in the optical waveguide element 10 within the viewing area 22. In the present embodiment, the separating structure 36 is formed monolithically with the optical component 30, for example, it was formed during the molding of the component 30. In other embodiments, the separating structure 36 can be produced as a separate part from the component 30.

[0048] The bond structure 34 and / or the separation structure 36 can also serve as a sealing structure to seal the stacked optical arrangement 50 against the environment.

[0049] The optical waveguide element 10 is provided with a reflective coating 26 in a circumferential region of the optical waveguide element 10, wherein the reflective coating 26 is provided in the region of the bond structure 34 and in the region of the separation structure 36. The reflective coating 26 is applied to the surface 12 of the waveguide element 10. According to the teachings of the present invention, the reflective coating 26 is applied to the surface 12 before the optical waveguide element 10 is assembled with the optical component 32. The reflective coating 26 can be applied to the optical waveguide element 10 during the fabrication of the optical waveguide element 10 or as an additional surface treatment immediately before the assembly of the stacked arrangement of the optical component 30 and the optical waveguide element 10.

[0050] The reflective coating 26 is provided in the circumferential region of the optical waveguide element 10 outside the viewing area 22 of the optical waveguide element 10 as described above. Depending on whether the image light from the display (not shown) enters the coupling area 16 through the first surface 12 or through the second surface 14 of the optical waveguide element 10, the opposite surface is preferably coated with the reflective coating 26. That is, if the image light enters the coupling area 16 through surface 12, surface 14 can be coated with the reflective coating, and vice versa.

[0051] A similar bond structure 34' and a similar separation structure 36' are provided in the optical arrangement 50 between the optical component 32 and the optical waveguide element 10, with reference to the above description of the bond structure 34, the separation structure 36, and the gap 35. Corresponding elements are identified by reference numerals supplemented with a dash. The optical waveguide element 10 accordingly has a reflective coating 26' on the surface 14 in the circumferential region of the surface 14 of the waveguide element 10, with reference to the above description of the reflective coating 26 on the surface 12.

[0052] The reflective coatings 26 and 26' can extend over the entire circumferential length of the first surface 12 and the second surface 14, respectively.

[0053] The following is an exemplary embodiment for preparing an optical waveguide element, such as the waveguide element 10 in Fig. 1-4, for a stacked optical arrangement, such as the stacked optical arrangement 50, and the assembly of the optical stack after preparation of the optical waveguide element 10 is described.

[0054] According to one embodiment of the method for preparing an optical waveguide element, the optical waveguide element 10 is provided with a first surface 12 and a second surface 14 opposite the first surface 12, a coupling area 16 ( Fig. 1), which is designed to couple image light into the waveguide element 10, and a viewing area 22 ( Fig. 1) including a coupling area 20 ( Fig. 1), which is configured to couple the image light propagated in the optical waveguide element 10 out of the waveguide element 10. The method for preparing the optical waveguide element 10 comprises applying a reflective coating 26 to at least one of the first and second surfaces 12, 14, in the present embodiment to the surface 12 of the optical waveguide element 10. The reflective coating is applied in a circumferential region 24 of the surface 12 of the waveguide element 10 outside the viewing area 22 and outside the coupling area 16 (as shown in Fig. 1 and Fig. 2 shown). The application of the reflective coating can involve applying a metal layer, e.g. a silver layer, to the surface 12 of the waveguide element 10 in a circumferential region thereof.

[0055] Applying the reflective coating 26 can be part of a surface treatment of the optical waveguide element 10 before a material layer, e.g., an adhesive, is applied to create the bonding, separation, and / or sealing structure of the optical arrangement 10. The reflective coating 26 provides optical isolation of the interface between the optical waveguide element 10 and the bonding, separation, and / or sealing structure. In other embodiments, the optical waveguide element 10 can be provided with the reflective coating 26 during its fabrication.

[0056] The optical waveguide element 10 prepared in this way can be used to assemble the stacked optical arrangement 50. Fig. Figure 5B shows an embodiment of an assembly procedure in which a separating structure 48, a bonding structure 44, and a sealing structure 46 have been applied to the surface of the reflective coating 26. The sealing structure 46 can be omitted if the sealing function is achieved by the bonding and / or separating structure 44, 48.

[0057] The structures 44, 46 and 48 can be applied to the surface of the reflective coating 26 in any suitable way, e.g. by applying these structures in liquid form, e.g. as a liquid adhesive, to the surface of the reflective coating 26.

[0058] Next, as in Fig. As shown in 5C, an optical component, such as optical component 30 in Fig. 3, as part of the optical arrangement 50. The optical component 30 is attached to the optical waveguide element 10 by applying a joining force 47, which can only be gravity, to the optical component 30, so that the optical component 30 is bonded to the optical waveguide element 10, as shown in Fig. 5D is shown. The separation structure 48 provides a gap 35 between the optical component 30 and the optical waveguide element 10.

[0059] In the case of the exemplary embodiment of Fig. 3 and Fig. 4, according to which the optical arrangement 50 additionally has the optical component 30 which is bonded to the surface 12 of the optical waveguide element 10, the optical waveguide element 10 is prepared with an additional reflective coating 26, such as the reflective coating 26', on the surface 14 in the circumferential region thereof.

[0060] As can be seen from the above description, the proposed mirror coating 26, 26' is a universal, cost-effective solution that is fully compatible with mass production and provides optical isolation of a waveguide element 10 in stacked optical arrangements to improve the quality of a projected virtual image. 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 11 243 398 B2

[0004] WO 2024 / 008593 A1

[0004]

Claims

[1] Optical waveguide element (10) for a stacked optical arrangement, comprising a first surface (12) and a second surface (14) opposite the first surface (12), an input coupling area (16) configured to couple image light into the waveguide element (10), and a viewing area (22) comprising an output coupling area (20) configured to couple the image light propagated in the optical waveguide element (10) out of the waveguide element (10), wherein at least one of the first surface (12) and the second surface (14) has a reflective coating (26, 26') applied in a circumferential region (24) of the at least one of the first and second surfaces (12, 14) outside the viewing area (22) and outside the input coupling area (16). [2] Optical waveguide element according to claim 1, wherein the reflective coating (26, 26') extends along the entire circumferential length of at least one of the first and second surfaces (12, 14) of the waveguide element (12, 14). [3] Optical waveguide element according to claim 1 or 2, wherein the at least one of the first and second surfaces (12, 14) has a reflective coating (26, 26') in a region of the at least one of the first and second surfaces (12, 14) which is configured for bonding the waveguide element (10) to a further optical component (30, 32) of the stacked optical arrangement, and / or wherein the at least one of the first and second surfaces (12, 14) has the reflective coating (26, 26') in a region of the at least one of the first and second surfaces (12, 14) of the waveguide element (10) which is configured for separating the waveguide element (10) from the further optical component (30, 32) in order to provide a gap (35, 35') between the waveguide element (10) and the further optical component (30, 32). [4] Optical waveguide element according to one of claims 1 to 3, wherein the first surface (12) of the waveguide element (10) has a first reflective coating (26) in a circumferential region (24) of the first surface (12) outside the viewing area (22) and outside the coupling area (16), and the second surface (14) of the waveguide element (10) has a second reflective coating (26') in a circumferential region (24) of the second surface (14) outside the viewing area (22). [5] Optical waveguide element according to claim 4, wherein the first reflective coating (26) of the first surface (12) of the waveguide element (10) and the second reflective coating (26') of the second surface (14) of the waveguide element (10) extend along the entire circumferential length of the first and second surfaces (12, 14). [6] Method for preparing an optical waveguide element (10) for a stacked optical arrangement, comprising: Providing the optical waveguide element (10) with a first surface (12) and a second surface (14) opposite the first surface (12), an input coupling area (16) configured to couple image light into the waveguide element (10), and a viewing area (22) comprising an output coupling area (20) configured to couple the image light propagated in the optical waveguide element (10) out of the waveguide element (10), Applying a reflective coating (26, 26') to at least one of the first surface (12) and the second surface (14) in a circumferential region (24) of the at least one of the first and second surfaces (12, 14) outside the viewing area (22) and outside the coupling area (16). [7] Method according to claim 6, wherein the application of the reflective coating (26, 26') comprises the application of the reflective coating (26, 26') along the entire circumferential length of at least one of the first and second surfaces (12, 14). [8] Method according to claim 6 or 7, wherein the application of the reflective coating (26, 26') comprises applying the reflective coating (26, 26') in a region of at least one of the first and second surfaces (12, 14) of the waveguide element (10) that is designed for bonding the waveguide element (10) to a further optical component (30, 32) of the stacked optical arrangement, and / or wherein the reflective coating (26, 26') is applied in a region of at least one of the first and second surfaces (12, 14) of the waveguide element (10) that is designed for separating the waveguide element (10) from the further optical component (30, 32) in order to provide a gap (35, 35') between the waveguide element (10) and the further optical component (30, 32). [9] Method according to any one of claims 6 to 8, wherein the application of the reflective coating (26, 26') comprises applying a first reflective coating (26) to the first surface (12) of the waveguide element (10) in a circumferential region (24) of the first surface (12) outside the viewing area (22) and outside the coupling area (16), and applying a second reflective coating (26') to the second surface (14) of the waveguide element (10) in a circumferential region (24) of the second surface (14) outside the viewing area (22). [10] Method according to claim 9, wherein the application of the reflective coating (26, 26') comprises applying the first reflective coating (26) along the entire circumferential length of the first surface (12) of the waveguide element (10) and applying the second reflective coating (26') along the entire circumferential length of the second surface (14) of the waveguide element (10). [11] Stacked optical arrangement comprising an optical waveguide element (10) according to any one of claims 1 to 5 and at least one optical component (30, 32), wherein the at least one optical component (30, 32) is connected directly or by means of an adhesive layer to which at least one of the first and second surfaces (12, 14) of the waveguide element (10) in the circumferential region (24) which has the reflective coating (26, 26') is connected. [12] Stacked optical arrangement according to claim 11, comprising a gap (35, 35') between the optical component (30) and the at least one of the first and second surfaces (12, 14) of the waveguide element (10) in the viewing area (22). [13] Stacked optical arrangement according to claim 11 or 12, wherein the optical component (30) is connected to the first surface (12) of the waveguide element (10), and wherein the optical arrangement (50) further comprises a further optical component (32) which is connected, directly or by means of an adhesive layer, to the second surface (14) of the waveguide element (10) in the circumferential region (24) which has the reflective coating. [14] Stacked optical arrangement according to claim 13, with a gap (35') between the further optical component (32) and the second surface (14) of the waveguide element (10) in the viewing area (22). [15] Stacked optical arrangement according to any one of claims 11 to 14, wherein the at least one optical component (30, 32) is a lens.

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