Optical arrangement and method for producing same, and head-mounted display

Abstract

The invention relates to an optical arrangement for a head-mounted display (200), which optical arrangement comprises an optical waveguide (8) having at least one Fresnel element (1) arranged in the optical waveguide, wherein the Fresnel element (1) has a Fresnel structure, which comprises a plurality of active surface segments (3, 3a, 3b, 3c) and a plurality of passive surface segments (5, 5a, 5b, 5c), wherein the passive surface segments (5, 5a, 5b, 5c) are arranged in a step-like manner between the active surface segments (3, 3a, 3b, 3c) and connect them to one another. The Fresnel structure is coated such that the active surface segments (3, 3a, 3b, 3c) have a first reflective coating (4) and the passive surface segments (5, 5a, 5b, 5c) have a second reflective coating (6), wherein the first reflective coating (4) and the second reflective coating (6) each comprise a number of layers (7, 7a, 7b, 7c, 7d, 7e, 7f) made of the same material and arranged in the same order such that the first reflective coating (4) and the second reflective coating (6) differ from one another only with respect to the thickness of the individual layers (7, 7a, 7b, 7c, 7d, 7e, 7f), wherein the coated Fresnel structure is arranged in the optical waveguide (8) such that display-emitted light which impinges on the Fresnel structure and is incident on a passive surface segment (5, 5a, 5b, 5c) after transmission through an active surface segment (3, 3a, 3b, 3c) is reflected in such a way that it is not incident on an active surface segment (3, 3a, 3b, 3c) again.

Description

[0001] 1 PATERI S

[0002] Applicant: tooz technologies GmbH, 73430 Aalen

[0003] Our reference number: Z50376-WO bzi / ehä

[0004] Optical arrangement and methods for its manufacture as well as head-mounted display

[0005] The invention relates to an optical arrangement for a head-mounted display, a spectacle lens, a head-mounted display and a method for manufacturing an optical arrangement.

[0006] A head-mounted display (HMD), i.e., a display device that can be arranged on or at the head of a user, allows, in a view-through version, a combination of an electronically generated image with the image of the environment directly perceived by the user. Smart glasses represent a head-mounted display in the form of eyeglasses, i.e., with lenses held by a frame. Examples of smart glasses are described, for instance, in documents DE 10 2013 207 257 A1, DE 10 2013 223 963 A1, DE 10 2013 223 964 B3, DE 10 2015 117 557 A1, DE 10 2016 124 538 A1, US 2006 / 0 126 181 A1, US 2010 / 0220295 A1, and US 2012 / 0 002 294 A1.

[0007] The electronically generated virtual image is formed from a source image displayed on an image source, e.g., a display. For this purpose, an imaging optic with an optical waveguide is used, the optical waveguide being arranged between an input element for coupling an imaging beam path emanating from the image source or display and an output element for coupling the imaging beam path towards the user's eye or an eyebox. The input and output elements can be components of the Z50376-WO 2 PATERI S

[0008] optical waveguides. The eyebox is a spatial area from which an electronically generated virtual image can be visually perceived as a virtual representation.

[0009] In HMDs designed for viewing through the field of view, the output element also serves to combine the beam path of the electronically generated image, i.e., the beam path of the virtual image, with a direct image of the surroundings, i.e., the beam path of the real image. In this case, the output element is also referred to as a combiner. The output element can, for example, comprise a Fresnel structure consisting of a plurality of surface segments or facets, of which a plurality of active surface segments or facets are designed for beam shaping, and a plurality of passive surface segments or facets are arranged in steps between the active surface segments and geometrically connect them. In one exemplary variant, the active surface segments, or a subset thereof, can be arranged parallel to each other.

[0010] It is known that the active or effective surface segments of a Fresnel structure are sub-surfaces of a continuous surface or can be combined to form a continuous surface, and that the passive or inactive surface segments, which can also be referred to as shadow surfaces, represent the step discontinuities between the individual active surface segments and connect adjacent active surface segments. It is further known that a Fresnel structure can deviate from the classical concept of being derived from a single continuous surface. In this case, it is a Fresnel-like structure that exhibits one or more active surface segments that do not correspond to a single continuous surface but rather encompass or correspond to one or more continuous surfaces.Such deviations may be caused by tolerances or inaccuracies during the manufacturing process of the Fresnel structure or may be intentionally introduced to achieve desired structural properties. The present invention, Z50376-WO 3 PATERI S, is not limited to the classical concept of a Fresnel structure but is also applicable to Fresnel-like structures and offers the same advantages. For this reason, the terms "Fresnel" and "Fresnel-like" are used interchangeably below to describe the above concept of Fresnel structures and Fresnel-like structures and are to be understood as synonymous. When Fresnel structures are mentioned, this also includes Fresnel-like structures.

[0011] The described Fresnel or Fresnel-like structures can be used both as coupling elements for coupling a beam path from a display or image sensor into an optical waveguide and as coupling elements for coupling a beam path out of the optical waveguide. Therefore, in the following, the terms "optical arrangement" and "optical arrangement with Fresnel element or Fresnel structure" are understood to refer to arrangements or elements of an optical waveguide suitable or intended for both coupling in and out.

[0012] Active surface areas or facets of a Fresnel structure in an optical arrangement can be provided with a partially reflective and partially transparent coating, with the reflectance typically set between 3% and 50% so that externally incident light can pass through the Fresnel structure and, together with the imaging beam path, project the virtual image towards the eye or eyebox, thus making the environment perceptible with the superimposed virtual image. However, 100% full reflectivity of the Fresnel facets is also possible, for example for virtual reality displays (VR displays), but is usually undesirable because it would prevent the view through the Fresnel structure, as required for augmented reality displays (AR displays) or mixed reality displays (MR displays). The present invention is primarily intended for use in AR or MR displays.It is therefore assumed that the surface segments or facets of the Fresnel structure are partially designed to be reflective.

[0013] According to the state of the art, when designing the partially reflective coating of Fresnel structures, the reflective effect of the active Z50376-WO 4 PATERI S

[0014] Surface segments for coupling out an imaging beam path of a pre-recorded virtual image towards a user's eye or towards an eyebox are currently the only target parameter. This means that the semi-reflective coating is designed to reflect the desired radiation fraction for a given wavelength, e.g., for red, green, or blue light, or a given or defined wavelength range of the electromagnetic radiation of the imaging beam path and / or a specific angle of incidence of the light rays on the coated surface, e.g., from 5° to 45°.

[0015] To eliminate the prismatic effect of the Fresnel structure, which interferes with viewing, the state of the art involves filling the Fresnel structure with a filler material or substrate whose refractive index is matched to that of the base material or substrate (e.g., base glass) of the optical fiber on which the Fresnel structure is mounted. The filler material covers the facets of the Fresnel structure and encapsulates them within the optical fiber. Ensuring the most precise possible match between the refractive indices of the base substrate and the filler material presents a particular challenge. Matching to the third or fourth decimal place or better leaves little room for material variations in the base substrate and / or filler material.

[0016] The adjustment of the refractive indices is important not only for transparency but also, and perhaps more importantly, for the image quality of the projected image. Light rays striking the partially reflective coating of the active facets are proportionally diverted towards each eye of the user, according to the reflectance. The remaining, non-reflected portion of the light rays passes through filler material after passing through an active facet, can pass through an adjacent, non-reflectively coated passive facet, and, depending on the geometry of the Fresnel structure and the angle of incidence of the imaging light rays, strikes a greater or lesser portion of the next active facet.In this case, depending on the difference in refractive indices and the geometry of the Fresnel structure, the light beam is repeatedly deflected and split by the next active facet depending on the wavelength of the light, which can lead to unwanted double images and color fringes in the resulting virtual image projected into the eye.

[0017] Against this background, the object of the invention is to provide an optical arrangement for a head-mounted display, a spectacle lens, and a head-mounted display, thereby improving image quality. It would be desirable to reduce or at least partially eliminate the aforementioned disadvantages. A further object is to provide a manufacturing method for such an optical arrangement.

[0018] These problems are solved by the subject matter of the independent claims. The dependent claims relate to embodiments of these solutions according to the invention.

[0019] A fundamental concept of the invention is to additionally and intentionally take into account the reflective effect on the passive surface segments or facets in an optical arrangement for an optical waveguide during the design of the optical design, in particular the optical arrangement, the Fresnel structure including the geometry and positioning of the Fresnel structure within the optical waveguide, as well as the coating thereof, in such a way that the radiation of the imaging beam path striking a passive surface segment is reflected after passing through one of the active surface segments in such a way that it does not strike an active surface segment again, or at least strikes an active surface segment to a lesser extent, i.e., strikes an edge region with less effect, and consequently is not reflected as scattered light towards the eye of a user or an eyebox.The present invention proposes to design a reflective coating for the Fresnel structure together with or based on the geometry of the Fresnel structure. By means of the present invention, the Fresnel structure can be coated in a single coating sequence of a coating process such that the active surface segments have a first reflective coating and the passive surface segments have a second reflective coating, wherein the first reflective coating and the second reflective coating differ only with respect to the thickness of the individual Z50376-WO 6 PATERI S.

[0020] Layers of the respective coating material can be distinguished from one another. For example, coating layers with specific, predefined properties, such as partially reflective coatings with specific sequences of individual layers of coating materials with predefined layer thicknesses, can be designed together with or based on the geometry of the Fresnel structure to achieve a desired reflectivity (e.g., 3%, 10%, 50%, etc.) for target wavelengths and angles of incidence of the incident light.The aim is to provide the light from the imaging beam path of the virtual image to the active surface segments and simultaneously to cause total internal reflection or at least an increased reflectance of the light from the imaging beam path of the virtual image at the passive surface segments when light from the imaging beam path of the virtual image strikes a passive surface segment after passing through or penetrating an active surface segment. Furthermore, the geometric positioning of the passive surface segments, preferably at a larger angle of incidence for incident light from the imaging beam path than that provided for the active surface segments, causes light from the imaging beam path to be reflected away from the active surface segments to avoid repeated reflections.

[0021] A first aspect of the invention relates to an optical arrangement for a head-mounted display, which comprises an optical waveguide with at least one Fresnel element arranged in the optical waveguide, wherein the Fresnel element has a Fresnel structure comprising a plurality of active surface segments or facets and a plurality of passive surface segments or facets, wherein the passive surface segments are arranged in a step-like fashion between the active surface segments and connect them to one another, in other words, geometrically connect them to one another. The Fresnel structure is coated such that the active surface segments have a first reflective coating and the passive surface segments have a second reflective coating.The first reflective coating and the second reflective coating each comprise a number, i.e., at least one or more, preferably a plurality, of layers, i.e., individual Z50376-WO 7 PATERI S or individual layer layers, made of the same material and arranged in the same sequence, such that the first reflective coating and the second reflective coating differ from each other only with respect to the thickness of the individual layers. The first reflective coating and the second reflective coating can consist of the aforementioned layers.

[0022] The coated Fresnel structure is arranged in the optical waveguide in such a way that light from a display, in other words an imaging beam from the optical waveguide or from the display, which after transmission through an active surface segment hits a passive surface segment, is reflected in such a way that it does not hit an active surface segment again, i.e. in other words, it is reflected in a direction away from the active surface segments.

[0023] The first reflective coating is designed for the partial reflection of electromagnetic radiation, such as incident light from a display, with wavelengths within a predefined wavelength range. This predefined wavelength range can correspond to, but is not limited to, the visible light wavelength range. It is also possible to define or specify the wavelength range within and / or at least partially outside the visible spectrum, for example, to restrict the predefined wavelength range to a specific color or to cover the infrared (IR) range, which can be used in eye-tracking functions in head-mounted displays. In principle, the design and functionality of the first reflective coating of the Fresnel structure can correspond to solutions known from the prior art.

[0024] As is known for Fresnel and Fresnel-like structures, the active surface segments are connected by means of the passive surface segments. In contrast to the prior art, the passive surface segments in the present invention have a second reflective coating which is designed to partially or completely reflect electromagnetic radiation with a predefined wavelength, and which differs from the first reflective coating only in the thicknesses of the individual layers of the coating material or materials. Preferably, the thickness of each individual layer of the first reflective coating is greater than the thickness of the corresponding individual layer of the second reflective coating.However, the thickness of each individual layer of the first reflective coating can also be smaller than the thickness of the corresponding individual layer of the second reflective coating.

[0025] Partially reflective means that the reflectance R of a surface segment or facet is less than 0% < R < 100% and its transmittance TT is greater than 0%. In other words, electromagnetic radiation of a certain wavelength striking a partially reflective facet is partially reflected by it and partially transmitted through it.

[0026] In general, reflectance and transmittance are independent of which side of the coating the radiation hits, i.e., whether the radiation hits the coated surface from one side or the other.

[0027] The visible wavelength range encompasses wavelengths between 390 nm and 780 nm. In various embodiments, the first and second reflective coatings exhibit the described partial reflectance in at least one or more sub-ranges of the visible wavelength range, for example, in the blue wavelength range between approximately 420 nm and 490 nm, in the green wavelength range between approximately 490 nm and 575 nm, and / or in the red wavelength range between approximately 650 nm and 780 nm. Optionally, the described reflectance can also be present across the entire wavelength range of visible light or outside the visible spectrum. The first and second reflective coatings can preferably be optically effective in the same predefined wavelength range.

[0028] By means of the proposed optical arrangement with a Fresnel element or Fresnel-like element, hereinafter referred to as a Fresnel element for simplicity, it is achieved that any of the passive Z50376-WO 9 PATERI S

[0029] Electromagnetic radiation from an imaging beam path, i.e., coming from a display, with a predefined or predetermined wavelength range (hereinafter referred to simply as radiation), incident on surface segments of the Fresnel structure, is not transmitted, or only to a lesser extent, compared to passive surface segments of the Fresnel structure without a second reflective coating, and is allowed to pass through to adjacent active surface segments. If the Fresnel structure is used for imaging optics to project a virtual image from a source image displayed on an image sensor into an eyebox, e.g., in a head-mounted display, the negative impact on image quality resulting from the repeated transmission of the radiation from the imaging beam path to an active surface segment and then the repeated reflection of this radiation from the same active surface segment, e.g.,unwanted double images and color fringes, as described above, are reduced, resulting in an overall improved image quality of the head-mounted display.

[0030] According to various design variants, the reflectance or reflectance for electromagnetic radiation incident on the second reflective coating with a wavelength in the visible wavelength range can be greater than the reflectance or reflectance for electromagnetic radiation incident on the first reflective coating with the same wavelength.

[0031] This means that, if any radiation passes through the second reflective coating to the next active surface segment, only a small proportion will be allowed to pass through and negatively affect the image quality.

[0032] In addition to the wavelength of the radiation to be reflected, the chemical composition, and the structure of the reflective coatings, the reflectance is also influenced by the angle of incidence at which the radiation to be reflected strikes the reflective coating. A higher reflectance at the second reflective coating for the same wavelength can therefore be achieved by changing the angle of incidence, in particular by increasing the angle of incidence, and / or by changing the structure of the second reflective coating compared to the first.

[0033] The angle of incidence is defined here as the smaller of the two angles formed by the incident ray and the normal erected on the plane of incidence, e.g., the surface of the coating. The term angle of reflection refers, correspondingly, to the smaller of the two angles formed by the reflected ray and the normal.

[0034] Since the angle of incidence depends on the orientation of the passive surface segment relative to the adjacent active surface segments, the angle of incidence can be influenced accordingly. A suitable angle of incidence, which can lead to a higher reflectance of the radiation at the second reflective coating compared to the first reflective coating, can result from an essentially perpendicular orientation of the active and passive surface segments to each other.

[0035] In an advantageous embodiment, the coated Fresnel structure within the optical waveguide is arranged such that the angle of incidence of the incident light or beam from a display onto an active surface segment is smaller than the angle of incidence of the light onto a passive surface segment after transmission through the active surface segment. This allows the light reflected from the passive surface segment to be directed away from the active surface segments.

[0036] In another embodiment, the optical waveguide comprises a base substrate or element on which the Fresnel structure is arranged, and a filler substrate or element that covers the Fresnel structure and encapsulates it within the optical waveguide, i.e., in other words, encloses, surrounds, or encloses it. It is arranged in a beam path such that incident light or beam from a display passes through the base substrate before striking an active surface segment and passes through the filler substrate after transmission through the active surface segment and before striking a passive surface segment. The base substrate and the filler substrate each have a refractive index Z50376-WO 11 PATERI S, and the refractive indices differ from each other by less than 0.01, preferably less than 0.005.This allows the coated Fresnel structure to be protected against environmental influences, especially against mechanical impact, while simultaneously achieving a flat surface for the optical arrangement.

[0037] Optionally, the Fresnel element can be designed such that the passive surface segments have a higher reflectance for light transmitted through the active surface segments than the active surface segments do for light incident directly onto them. This effectively directs light reflected by the passive surface segments away from the active surface segments.

[0038] The reflectance for electromagnetic radiation incident on the first reflective coating with a wavelength in the visible range can be between 3% and 50%, for example, between 10% and 15%. Such a reflectance allows for very good perception of the surroundings while simultaneously ensuring good visibility of the reflected virtual image.

[0039] The reflectance of electromagnetic radiation incident on the second reflective coating with a wavelength in the visible range can be greater than 30%, for example, greater than 40%, greater than 60%, or greater than 80%. Such a reflectance means that only a small fraction of the radiation passes through the second reflective coating to the next active surface segment, where it can negatively affect image quality. Optionally, the second reflective coating can be designed to cause total internal reflection and / or (partial) cancellation of the incident electromagnetic radiation.

[0040] According to further design specifications, the first and / or the second reflective coating can have several individual layers.

[0041] The individual layers can differ, for example, in their qualitative and / or quantitative chemical composition. Z50376-WO 12 PATERI S

[0042] Composition, e.g., mixed layers with different proportions of the individual components, and / or different chemical modifications, distinguish them from one another, including the possibility of gradient index layers (GRIN layer).

[0043] By having the first and / or second reflective coatings comprise a layer system of multiple individual layers, the respective coating properties can be precisely controlled, allowing for the precise realization of a desired optical property with minimal undesirable side effects. For example, the wavelength range in which the coating is optically active can be defined by the targeted selection and sequence of coating materials.

[0044] The multiple layers of the first reflective coating and the second reflective coating have the same layer sequence. This means that the first reflective coating and the second reflective coating each have a layer system consisting of several individual layers, where the individual layers can have the same qualitative and quantitative chemical composition as well as the same chemical modification. In other words, the first reflective coating and the second reflective coating can be identical with respect to their components and differ only in the thickness of the individual layers.

[0045] Using the same layer sequence simplifies the production of the first and second reflective coatings, as the same materials and coating processes can be used. Furthermore, this allows the first and second reflective coatings to be produced simultaneously, thus reducing production time and significantly simplifying the manufacturing process.

[0046] With the same layer sequence, at least one of the multiple layers of the first reflective coating and the second reflective coating Z50376-WO 13 PATERI S within the layer sequence will always have a different layer thickness. Optionally, all layers can have a different layer thickness. The layer thickness is measured perpendicular to the substrate, i.e., perpendicular to the surface of the active or passive area segment. It is also possible to select coating parameters, e.g., the coating direction, such that the total layer thickness of the first and second reflective coatings and / or the layer thickness of the corresponding individual layers increase proportionally to each other.

[0047] By using different layer thicknesses, the properties of the first reflective coating and the second reflective coating can be designed differently while maintaining the aforementioned advantages of the same layer sequence.

[0048] For example, a passive surface segment can be designed in such a way that it does not act as a continuous mirror and no clearly recognizable image is formed. This prevents the virtual image from being detected from the outside through the coupling via the passive surface segments. Unwanted perception of the virtual image in the environment can thus be prevented.

[0049] For some applications, however, it may be desirable to design the second reflective coating in such a way that electromagnetic radiation reflected from the second reflective coating is focused and reflected back, so that the virtual image is also perceptible from the outer surface opposite the eye. This can be achieved by appropriately adjusting the geometry and coating of the passive surface segments.

[0050] According to further specifications, one or more of the individual layers of the first reflective coating and the second reflective coating can consist of silicon dioxide (SiO2) and / or trititanium pentoxide (TisOs) as the coating material. The aforementioned materials can be easily applied to the active and passive surface segments by thermal evaporation. Z50376-WO 14 PATERI S

[0051] Other suitable materials include aluminum trioxide (AL2O3), zirconium dioxide (ZrO2), magnesium fluoride (MgF), tantalum trioxide (TaOs), etc. The selection of coating materials depends on the desired properties of the first and second reflective coatings.

[0052] Another aspect of the invention relates to a spectacle lens for a head-mounted display, in particular a spectacle lens of a head-mounted display, which comprises an optical arrangement according to the above description.

[0053] All statements regarding the proposed optical arrangement can be applied analogously to the proposed spectacle lens. The advantages mentioned above with regard to the optical arrangement are correspondingly associated with the spectacle lens.

[0054] The spectacle lens can comprise at least one coupling section with, for example, a coupling structure for coupling an imaging beam path originating from the image sensor or display, and an output coupling section for coupling the imaging beam path towards the user's eye or an eyebox. A fiber optic section with a fiber optic cable can be arranged between the coupling section and the output coupling section, the fiber optic cable being configured to guide the imaging beam path from the coupling section to the output coupling section by means of reflections, preferably total resections.

[0055] The outcoupling section and / or the incoupling section comprise an optical arrangement according to the above description, so that the aforementioned advantages of the optical arrangement can be achieved by coupling in and / or out of the imaging beam path.

[0056] The proposed optical arrangement can be integrated into a spectacle lens, i.e., form at least part of the spectacle lens. For example, the spectacle lens can have a base body, e.g., made of glass or a plastic material, such as polycarbonate, in which the optical arrangement is integrated or in which the optical arrangement is formed. The base body can comprise an inner surface facing the user's eye or the eyebox and an outer surface facing away from the eye (Z50376-WO 15 PATERI S), wherein the imaging beam path is coupled between the inner and outer surfaces by means of the coupling section and then guided by reflection at at least one reflective section of the inner and / or outer surface to the coupling section by means of the optical waveguide section, and coupled out from there in the direction of the eye or the eyebox.

[0057] Another aspect of the invention relates to a head-mounted display, optionally with an image sensor for displaying a source image. The head-mounted display comprises an optical arrangement or a lens as described above. A virtual image is formed from the source image displayed on the image sensor by means of the head-mounted display.

[0058] All statements regarding the proposed optical arrangement and the proposed spectacle lens can be applied analogously to the proposed head-mounted display. The advantages mentioned above with regard to the optical arrangement and the spectacle lens are correspondingly associated with the head-mounted display.

[0059] The head-mounted display can, for example, be designed as smart glasses. In this case, one or two lenses of the smart glasses can be designed according to the above description of the spectacle lens.

[0060] Another aspect of the invention relates to a method for manufacturing an optical arrangement for a head-mounted display, wherein the optical arrangement is configured according to the preceding description. The proposed method comprises the following steps:

[0061] - Providing a Fresnel structure on a substrate of an optical waveguide, wherein the Fresnel structure comprises a plurality of active surface segments and a plurality of passive surface segments, wherein the passive surface segments are arranged in a step-like fashion between the active surface segments and connect them together,

[0062] - Coating the Fresnel structure by simultaneously applying material by depositing coating materials from a Z50376-WO 16 PATERI S

[0063] Gas phase onto the active surface segments and the passive surface segments, such that a first reflective coating is formed on the active surface segments and a second reflective coating is formed on the passive surface segments, wherein the first reflective coating and the second reflective coating each comprise a number, preferably a plurality, of layers, i.e. individual layer layers, made of the same material and arranged in the same sequence, such that the first reflective coating and the second reflective coating differ from each other only with respect to the thickness of the individual layers.

[0064] Preferably, the first reflective coating and / or the second reflective coating can be formed by physical vapor deposition of the coating materials, particularly preferably by thermal evaporation. Alternatively or additionally, other physical vapor deposition (PVD) processes, such as electron beam evaporation, laser beam evaporation, sputtering, can be used individually or in combination.

[0065] Alternatively or in addition to physical vapor deposition, chemical vapor deposition (CVD) processes can be used.

[0066] Depending on the chosen method, the coating materials can be evaporated directly, or a precursor of the coating material can be evaporated, from which the actual coating material is then formed by means of chemical reactions, such as oxidation or reduction processes. For this purpose, the coating material or the precursor of the coating material is arranged in at least one evaporation source.

[0067] The coating processes mentioned above enable the simple production of the desired optical arrangement, ensuring controlled coating and eliminating the need for complex masking. In particular, the first reflective coating and / or the second reflective coating can be made especially homogeneous, e.g., with a constant total layer thickness, which contributes to high image quality.

[0068] Optionally, the same evaporation source(s) can be used, at least partially, to form the gas phase, which simplifies the manufacturing process and makes it more cost-effective.

[0069] In contrast to the claimed method, a staggered application of the first and second reflective coatings may necessitate masking the section not to be coated to prevent unwanted coating of that section. Masks can be used for masking, but for very small structures, these masks must be correspondingly delicate and precisely positioned relative to the Fresnel element. In addition to these challenges, unwanted vapor deposition behind the mask can occur, at least at its edges, leading to uneven coating edges and thus unsatisfactory quality of the first and second reflective coatings. Furthermore, the two separate coating processes for the first and second reflective coatings significantly increase the overall process time and make the method highly complex.These disadvantages are avoided by the method according to the invention.

[0070] The first reflective coating and the second reflective coating can be formed from several layers with the same layer sequence, but at least partially different layer thicknesses. The different layer thicknesses can be adjusted by aligning the active and passive surface segments with respect to the evaporation source(s).

[0071] Since the deposition rate and thus the layer thickness is determined, in addition to parameters of the coating device, by the orientation of the surface or sections to be coated relative to the evaporation source, the layer thickness of the individual layers of the first reflective coating Z50376-WO 18 PATERI S and the second reflective coating can be adjusted and thus varied during simultaneous coating by appropriately aligning the active and passive surface segments, i.e., the Fresnel elements as such, with respect to the evaporation source.

[0072] The positioning of the passive surface segments relative to the active surface segments can be used as an additional design parameter in layer design; that is, the ratio of layer thicknesses on the active and passive surface segments can be influenced by varying the position of the passive surface segments relative to the active surface segments. By specifically considering the angle-dependent deposition rates of individual layers, it may even be possible to design deposition processes whose resulting coatings, at the same relative angles of incidence of the electromagnetic radiation in the imaging beam path, lead to partial reflection on the active surface segments and total reflection on the passive surface segments.The effect that the angles of incidence of the imaging beam path on the passive surface segments are usually significantly larger than the angles of incidence on the active surface segments can also be taken into account and used to increase the difference in reflection properties between active surface segments and passive surface segments.

[0073] In an advantageous embodiment, the coated Fresnel structure is coated with a filler material, e.g., by vapor deposition, to form a filler substrate that covers and encapsulates the Fresnel structure within the optical waveguide. The base substrate and the filler substrate each have a refractive index, and the refractive indices differ from each other by less than 0.01, preferably less than 0.005. The active section coating and / or the interconnection section coating are formed by physical vapor deposition of the coating materials.

[0074] The gas phases of the coating materials can be generated by means of one or more evaporation sources. In particular, before the Z50376-WO 19 PATERI S

[0075] Coating the base substrate of the optical waveguide with the Fresnel structure to create a predetermined thickness of the individual layers of the first reflective coating and the second reflective coating in relation to the one or more evaporation source(s) being spatially, i.e. geometrically, positioned in a predetermined manner.

[0076] In another variant, the coating process can include moving the optical waveguide(s) with the Fresnel structure in a predetermined manner relative to one or more evaporation sources in order to generate the specified thickness of the individual layers, e.g., by translation and / or rotation, and / or moving the one or more evaporation sources relative to the optical waveguide with the Fresnel structure in a predetermined manner, e.g., by translation and / or rotation.

[0077] The invention is explained below by way of example with reference to the accompanying figures and preferred embodiments. The figures show:

[0078] Figure 1 shows a schematic representation of an exemplary head-mounted display in the form of data glasses;

[0079] Figure 2 shows a schematic representation of an exemplary imaging optic;

[0080] Figure 3 shows a schematic representation of a Fresnel element according to the prior art;

[0081] Figure 4 shows a schematic representation of an exemplary Fresnel element of an optical arrangement according to the invention;

[0082] Figure 5a shows a schematic representation of a first reflective coating; Z50376-WO 20 PATERI S

[0083] Figure 5b shows a diagram illustrating the reflectance as a function of wavelength for the first reflective coating from Fig. 5a;

[0084] Figure 6a shows a schematic representation of a second reflective

[0085] Coating;

[0086] Figure 6b is a diagram illustrating the reflectance in

[0087] Dependence on the wavelength for the second reflective coating from Fig. 6a; and

[0088] Figure 7 shows an exemplary flowchart of a method according to the invention for producing an optical arrangement according to the invention.

[0089] The examples explained below refer to the accompanying drawings, which form part of the examples and in which specific embodiments in which the invention can be implemented are shown for illustrative purposes.

[0090] It is understood that other embodiments may be used and structural or logical modifications made without deviating from the scope of protection of the present invention. Features of the various exemplary embodiments described herein may be combined with one another unless specifically stated otherwise. The following detailed description is therefore not to be understood as restrictive, and the scope of protection of the present invention is defined by the appended claims. In the figures, identical or similar elements are designated with identical reference numerals where appropriate.

[0091] Figure 1 shows a head-mounted display 200, configured as smart glasses. The smart glasses comprise a frame 21, into which two lenses 100a and 100b are fitted. Displays as image transmitters 2 (not shown in Figure 1) are arranged in the temples 22a, 22b, on which source images for projection into an eyebox, e.g., onto the retina of one eye of the user of the smart glasses, are projected by means of an imaging optic Z50376-WO 21 PATERI S

[0092] Figures 10a and 10b are shown. In the illustrated embodiment, each of the spectacle lenses 100a and 100b has an imaging optic 10a, 10b with an output coupling structure 14a, 14b designed as a Fresnel element 1 with a Fresnel structure integrated into it. In other words, the Fresnel element comprises a Fresnel structure. However, the imaging optic 10a, 10b can also include optical elements outside the spectacle lenses 100a, 100b. Such elements can, for example, be arranged between the temples 22a, 22b and the spectacle lenses 100a, 100b. The imaging optic 10a, 10b integrated into the spectacle lenses 100a, 100b can be laterally inverted, but otherwise identical in design. Of course, only one of the spectacle lenses 100a, 100b can be designed to form a virtual image, i.e., have a corresponding imaging optic 10a, 10b.

[0093] The essential optical elements of an imaging optic 10 are shown in Figure 2. Each imaging optic 10 is associated with an image transmitter 2, e.g., in the form of a polychromatic display, on which an output image can be displayed. The imaging optic 10 comprises an optical waveguide 8, which has an optical waveguide entry surface 9 with an input structure, which can be configured, e.g., as a diffraction grating or Fresnel structure, or formed by holographic optical elements, and an optical waveguide exit surface 11. An imaging beam path 12 originating from the output image displayed on the image transmitter 2 enters the optical waveguide 8 via the optical waveguide entry surface 9 and is reflected multiple times at a number of reflective surfaces 13a to 13f. These reflections then direct the beam to an output coupling structure 14.With the aid of the output coupling structure 14, which in turn can be configured as a Fresnel element 1 with a Fresnel structure, the imaging beam path 12 is coupled through the optical waveguide exit surface 11 towards an eyebox, in particular onto the eye lens 15, and finally focused from there onto the retina 16 of the eye. The output coupling structure 14 is arranged within the optical waveguide 8, either closer to the side of the optical waveguide 8 facing away from the eye lens 15 or closer to the side of the optical waveguide 8 facing the eye lens 15. Z50376-WO 22 PATERI S.

[0094] In the embodiment shown in Figure 2, the reflective surfaces 13a and 13c to 13f are located on the inner surface of the spectacle lens 100 facing the eye lens 15 and on the outer surface of the respective spectacle lens 100 facing away from the eye lens 15. The geometry and arrangement of the reflective surfaces 13a to 13f are chosen such that total internal reflection occurs at the interface between the respective spectacle lens 100 and the surrounding medium, usually air, at the reflective surfaces 13c, 13d, 13e, and 13f. The condition for the occurrence of total internal reflection is known to those skilled in the art and will not be explained further here. Since the total internal reflection takes place inside the spectacle lens 100, it is also called internal total internal reflection.Because the optical waveguide inside the spectacle lens 100 is therefore caused by total internal reflection and the output coupling structure 14 is partially reflective and partially transparent, the view of the surroundings is not obstructed or only minimally obstructed. In particular, the obstruction of the view of the surroundings can be minimized by suitable designs of the output coupling structure 14. However, an optical waveguide 8 can also be designed so that the optical waveguide does not cause total internal reflection. In this case, the optical waveguide 8 has reflective coatings, whereby the coatings are selected to be angle-selective and thus block as little light as possible from the surroundings passing through the optical waveguide 8.

[0095] Figure 3 shows a prior art Fresnel structure 1, which can be used, for example, as a coupling structure 14 in a head-mounted display 200. In this respect, Figure 3 can be understood as an enlargement of the coupling structure 14 of Figure 2.

[0096] The Fresnel element 1 has a base body or substrate 17, which is bounded, among other things, by a plurality of inclined, partially reflective surfaces, the active surface segments 3a, 3b, 3c, which form a sawtooth-like structure in profile. Figure 3 shows only three active surface segments 3a, 3b, 3c as an example. Of course, as any expert knows, the Fresnel element 1 can have a different number of active surface segments depending on the imaging optics design.

[0097] The active surface segments 3a, 3b, 3c are connected to each other by means of passive surface segments 5a, 5b, which also represent outer boundary surfaces of the base body 17. In the representation according to Figure 3, the active surface segments 3a, 3b, 3c are arranged essentially parallel to each other and perpendicular to the passive surface segments 5a, 5b connecting them. The angle of inclination α of the passive surface segments 5a, 5b with respect to the dotted reference line is approximately 45°. Due to the segmentation, the coupling structure 14 can be designed with a shallow depth, thus enabling its integration into the spectacle lens 100.

[0098] Optionally, the area connecting active surface segments 3a, 3b, 3c and passive surface segments 5a, 5b can be minimally rounded, i.e., a rounding area 25 can be present, typically with dimensions in the range of 20 micrometers. The rounding can be caused by manufacturing tolerances or defects, or it can be intentionally created, for example, to simplify the manufacturing process or to deflect unwanted light, such as stray light, away from the eyebox.

[0099] A partially reflective coating, the first reflective coating 4, is arranged on the active surface segments 3a, 3b, 3c. It should be noted that the figures are not to scale and, for example, the first reflective coating 4 is depicted as exaggeratedly thick compared to the dimensions of the active surface segments 3a, 3b, 3c. In the exemplary embodiment, the first reflective coating 4 reflects between 10% and 15% of the electromagnetic radiation of the imaging beam path 12, while the remaining portion of the electromagnetic radiation of the imaging beam path 12 is essentially transmitted through the first reflective coating 4. This partial transparency is necessary to allow ambient light to pass through the active surface segments 3a, 3b, 3c towards the eye or eyebox, so that the formed virtual image of the environment is superimposed.To eliminate the prismatic effect of the Fresnel element, which interferes with viewing, the Fresnel element 1 is fitted with a Z50376-WO 24 PATERI S.

[0100] Filling material was added to form a filling substrate 18, the refractive index of which should correspond as closely as possible to the refractive index of the material of the base substrate 17.

[0101] The following section, with reference to Figure 3, explains in more detail the path of the imaging beam 12 using the active surface segments 3b and 3c and the passive surface segment 5b as examples. This can be applied analogously to further active surface segments 3 and passive surface segments 5. The electromagnetic radiation of the imaging beam 12 first passes through the base body 17 of the Fresnel element, then strikes the active surface segment 3b and the first reflective coating 4 arranged on it at an angle of incidence β between 28.5° and 36.2°. Part of the radiation is reflected and directed as reflected radiation 19 towards the eye or the eyebox. The remaining part of the radiation passes through the first reflective coating 4 and enters the filler material 18 as transmitted radiation 20.The transmitted radiation 20 then strikes the adjacent passive surface segment 5b at the angle of incidence Y, through which it passes, and re-enters the base body 17. Due to differences in the refractive indices of the filler material or filler substrate 18 and the base substrate 17, it is deflected and splits depending on the wavelength. At the first reflective coating 4 of the next active surface segment 3c, the previously transmitted radiation 20 is again partially reflected towards the eye or the exebox. Due to the wavelength-dependent splitting, this results in undesired double images and color fringing.

[0102] The first reflective coating 4 is produced according to the prior art by depositing coating materials from a gas phase, preferably by thermal evaporation. The deposition direction 23 is selected such that layer deposition takes place exclusively on the active surface segments 3a, 3b, 3c.

[0103] Figure 4 shows a schematic representation of a proposed Fresnel element 1, modified from the prior art, of an optical arrangement for a head-mounted display. Since it is a Z50376-WO 25 PATERI S

[0104] Since this is a further development of the Fresnel element 1 known from the prior art and shown in Figure 3, only the differences compared to the prior art will be discussed below. For further details, please refer to the explanations regarding Figure 3.

[0105] To improve the imaging properties of the Fresnel element 1, it is provided not only to coat the active surface segments 3a, 3b, 3c, but also to coat the passive surface segments 5a, 5b. Consequently, a second reflective coating 6 is arranged on the passive surface segments 5a, 5b, which reflects electromagnetic radiation with a wavelength in the visible wavelength range, and optionally also in the infrared range. The reflectance R of the second reflective coating can be, for example, more than 30%, preferably more than 40%. Preferably, the second reflective coating 6 and the first reflective coating 4 are effective in the same wavelength range, so that, for example, the same electromagnetic radiation can be reflected by both the first reflective coating 4 and the second reflective coating 6.

[0106] The following section explains in more detail the mode of operation of the second reflective coating 6. As already explained with reference to Figure 3, the electromagnetic radiation of the imaging beam path 12 first passes through the base body 17 of the Fresnel element and then strikes the active surface segment 3b with the first reflective coating 4 arranged on it. Here, part of the radiation is reflected and directed as reflected radiation 19 towards the eye or the eyebox. The remaining part of the radiation passes through the first reflective coating 4 and enters the filler material 18 as transmitted radiation 20.In contrast to the prior art, however, the transmitted radiation 20 is largely prevented from reaching the base body 17 and the first reflective coating 4 of the next active surface segment 3c via the adjacent passive surface segment 5b, by reflecting at least a portion of the transmitted radiation 20 towards the filler material 18 and the environment as radiation 24 by means of the second reflective coating 6 of the passive surface segment 5b. Z50376-WO 26 PATERI S.

[0107] Preferably, the second reflective coating 6 is configured such that it has a higher reflectance R for the electromagnetic radiation of the imaging beam path 12 than the first reflective coating 4. The specific layer properties of the second reflective coating 6 and the first reflective coating 4 depend on the wavelength range of the electromagnetic radiation of the imaging beam path 12 and consequently on the initial image displayed on the image sensor 2.

[0108] The second reflective coating 6 can also be produced by depositing coating materials from a gas phase, preferably by thermal evaporation. The deposition direction 23 can be selected such that layer deposition takes place on both the active surface segments 3a, 3b, 3c and the passive surface segments 5a, 5b, thus enabling simultaneous coating of the active surface segments 3a, 3b, 3c and the passive surface segments 5a, 5b. For example, as shown in Figure 4, the deposition direction 23 can not only correspond to a specific direction, but can also encompass a deposition direction range, the extent of which

[0109] The main vapor deposition directions 23a, 23b enclose an angle of, for example, 60°. This can be achieved by means of masking devices and a corresponding positioning of the substrate relative to them. However, the present invention is not limited to this example, and other vapor deposition directions or angles are also possible.

[0110] The described Fresnel element 1 can, as already explained with reference to Figures 1 and 2, be part of an imaging optic 100 for forming a virtual image from a source image displayed on an image transmitter 2 and can accordingly be or become integrated into a spectacle lens 100 or into a head-mounted display 200, e.g. in a data glasses.

[0111] Referring to Figures 5a and 5b, as well as 6a and 6b, a specific embodiment of a first reflective coating 4 (Figures 5a and 5b) and a second reflective coating 6 (Figures 6a and 6b) is described in more detail below. Z50376-WO 27 PATERI S

[0112] Figure 5a shows a schematic representation of a first reflective coating 4 arranged on an active surface segment 3. The first reflective coating 4 consists of a layer system with six individual layers 7a to 7f, in which individual layers 7a, 7c, 7e consisting of silicon dioxide SiO₂ and individual layers 7b, 7d, 7f consisting of trititanium pentoxide TisO₂ alternate. In other words, the surface of the active surface segment 3 is initially covered with an SiO₂ layer, followed by a TisO₂ layer, followed by another SiO₂ layer, and so on.

[0113] The layer thickness of the individual layers is indicated by the letter d. In the illustrated embodiment, the total layer thickness is 1098.72 nm, where the layer thickness d of the individual layers 7a to 7f is as follows: layer 7a - 246.1 nm, layer 7b - 126.9 nm, layer 7c - 254.1 nm, layer 7d - 11.98 nm, layer 7f - 30.82 nm and layer 7f - 428.82 nm.

[0114] Figure 5b shows the reflectance R as a function of wavelength for the active section coating 4 according to Figure 5a, primarily in the wavelength range of green light between approximately 490 nm and 575 nm for angles of incidence β of 28° (curve 27) and 36° (curve 28). A reflectance R of approximately 10% is desired, marked in Figure 5b by a bar-shaped target area 26. Essentially independent of the angle of incidence β, a reflectance R within the target area 26 is achieved in the wavelength range of green light.

[0115] Figure 6a shows a schematic representation of a second reflective coating 6 arranged on a passive surface segment 5. The second reflective coating 6 consists of a layer system with six individual layers 7a to 7f, in which individual layers 7a, 7c, 7e consisting of silicon dioxide SiO₂ and individual layers 7b, 7d, 7f consisting of trititanium pentoxide TisO₂ alternate. In other words, the surface of the passive surface segment 5 is initially composed of an SiO₂ layer, followed by a TisO₂ layer, followed by another SiO₂ layer, and so on. The number of individual layers 7a to 7f and their layer sequence in the second reflective coating 6 correspond to the number of individual layers 7a to 7f and their layer sequence in the first reflective coating 4.

[0116] The layer thickness is denoted by the letter d. In the illustrated embodiment, the total layer thickness is 549.5 nm, with the layer thickness d of the individual layers 7a to 7f being as follows: layer 7a - 123.1 nm, layer 7b - 63.5 nm, layer 7c - 127.1 nm, layer 7d - 6.0 nm, layer 7d - 15.4 nm, and layer 7f - 214.4 nm. Consequently, the layer thickness d of all individual layers 7a to 7f of the second reflective coating 6 differs from the corresponding layer thickness d of the individual layers 7a to 7f of the first reflective coating 4. The layer thickness d of the individual layers 7a to 7f of the first reflective coating 4 is approximately a factor of 1.67 greater than the layer thickness d of the individual layers 7a to 7f of the second reflective coating 6.

[0117] Figure 6b shows the reflectance R as a function of wavelength for the second reflective coating 6 according to Figure 6a, primarily in the wavelength range of green light between approximately 490 nm and 575 nm for angles of incidence y of 54° (curve 30) and 62° (curve 29). The desired result is the highest possible reflectance R. Depending on the angle of incidence y, a reflectance R of approximately 40% to 45% and approximately 60% to 49% is achieved in the wavelength range of green light, with a higher reflectance being obtained at larger angles of incidence y.

[0118] The different angle of incidence y on the second reflective coating 6 compared to the angle of incidence β on the first reflective coating 4 makes it possible to achieve different reflectances R in the second reflective coating 6 and the first reflective coating 4 with the same layer sequence and the same number of individual layers 7, and thus to create a second reflective coating 6 with a higher reflectance R than that of the first reflective coating 4, as desired.

[0119] Furthermore, the reflectance R can be influenced by the layer thickness d of the individual layers and consequently adjusted by changing the layer thickness d. By changing the layer thickness d in combination with the higher angle of incidence y on the second reflective coating 6, a reflectance R up to 40% higher than that of the first reflective coating 4 can be achieved for the second reflective coating 6.

[0120] Figure 7 shows a flowchart for an exemplary method 300 for manufacturing a Fresnel element 1 of an optical arrangement according to the invention. Using method 300, for example, the Fresnel element 1 described above with reference to Figures 4 to 6b can be manufactured.

[0121] Method 300 provides for the simultaneous formation of the first reflective coating 4 and the second reflective coating 6 by means of physical vapor deposition. Specifically, both coatings 4 and 6 are produced by thermal evaporation of the coating materials, e.g., SiO2 and TisOs, provided in evaporation sources. The same evaporation sources are used for both coatings 4 and 6.

[0122] Specifically, the procedure comprises the following steps: in step S1, the provision of a Fresnel structure on a base substrate 17 of a

[0123] optical waveguide 8, wherein the Fresnel structure comprises a plurality of active surface segments 3, 3a, 3b, 3c and a plurality of passive

[0124] Area segments 5, 5a, 5b, 5c comprised, wherein the passive

[0125] Surface segments 5, 5a, 5b, 5c step-like between the active

[0126] Surface segments 3, 3a, 3b, 3c are arranged and connect them to each other; and in step S2 the coating of the Fresnel structure by simultaneously applying material by depositing coating materials from a gas phase onto the active surface segments 3, 3a, 3b, 3c and the passive surface segments 5, 5a, 5b, 5c, such that a first reflective coating 4 is formed on the active surface segments 3, 3a, 3b, 3c and a second reflective coating 6 is formed on the passive surface segments 5, 5a, 5b, 5c, wherein the first reflective coating 4 and the second reflective coating 6 each comprise or consist of a number of layers 7, 7a, 7b, 7c, 7d, 7e, 7f of the same material and arranged in the same sequence, such that the first reflective coating 4 and the second reflective coating Z50376-WO 30 PATERI S

[0127] 6 differ from each other only in terms of the thickness of the individual layers 7, 7a, 7b, 7c, 7d, 7e, 7f

[0128] To create layer systems with multiple individual layers 7, a first coating material, e.g., SiÜ2, can be alternately deposited from a first evaporation source and a second coating material, e.g., TisOs, from a second evaporation source. This enables the simultaneous formation of the first reflective coating 4 and the second reflective coating 6 from multiple layers 7 with the same layer sequence, as shown, for example, in Figures 5b and 6b.

[0129] However, in order to achieve different layer thicknesses d for the individual layers of the first reflective coating 4 and the second reflective coating 6, the active surface segments 3 and the passive surface segments 5 are positioned accordingly with respect to the evaporation sources and / or the deposition direction area of ​​the evaporation sources. For example, as shown in Fig. 4, a coating angle difference, namely an angle between the main deposition directions 23a, 23b of the deposition direction area, of, for example, 60° is set, so that the layer thicknesses d increase proportionally to each other, for example with the aforementioned proportionality factor of approximately 1.67.

[0130] Z50376-WO 31 PATERI S

[0131] Reference symbol list:

[0132] 1 Fresnel element with Fresnel structure

[0133] Imager

[0134] 3, 3a, 3b, 3c active area segment

[0135] 4 first reflective coating

[0136] 5, 5a, 5b passive area segment

[0137] 6 second reflective coating

[0138] 7, 7a to 7f Single layer

[0139] 8 optical fibers

[0140] 9 Optical fiber entry surface

[0141] 10, 10a, 10b Imaging optics

[0142] 11 optical fiber exit surface

[0143] Imaging beam path

[0144] 13a to 13f reflective surface

[0145] 14, 14a, 14b Coupling structure

[0146] 15 Eye lens

[0147] 16 Retina

[0148] 17 Base body / base substrate

[0149] 18 Filling material / Filling substrate

[0150] 19 Radiation reflected towards the eye

[0151] 20 transmitted radiation

[0152] 21 Eyeglass frames

[0153] 22a, 22b Eyeglass temples

[0154] 23 Steaming direction

[0155] 24 radiation reflected towards the environment

[0156] 25 rounding area

[0157] 26 Target area

[0158] 27 Reflectance at an angle of incidence of 28°

[0159] 28 Reflectance at an angle of incidence of 36°

[0160] 29 Reflectance at an angle of incidence of 62°

[0161] 30 Reflectance at an angle of incidence of 54°

[0162] 100, 100a, 100b spectacle lens

[0163] 200 Head Mounted Display

[0164] 300 Procedure Z50376-WO 32 PATERI S

[0165] 51 Provision of a Fresnel structure on a substrate of an optical waveguide

[0166] 52 Coating of the Fresnel structure by simultaneously applying material by depositing coating materials from a gas phase onto the active surface segments and the passive surface segments d layer thickness

[0167] R Reflectance

[0168] T transmittance a inclination angle β angle of incidence on the first reflective coating

[0169] Y angle of incidence on the second reflective surface

[0170] coating

Claims

Z50376-WO 33 PATERI S Patent claims 1. Optical arrangement for a head-mounted display (200) comprising an optical waveguide (8) with at least one Fresnel element (1) arranged in the optical waveguide, wherein the Fresnel element (1) has a Fresnel structure comprising a plurality of active surface segments (3, 3a, 3b, 3c) and a plurality of passive surface segments (5, 5a, 5b, 5c), wherein the passive surface segments (5, 5a, 5b, 5c) are arranged in a step-like fashion between the active surface segments (3, 3a, 3b, 3c) and connect them to one another, characterized in that the Fresnel structure is coated such that the active surface segments (3, 3a, 3b, 3c) have a first reflective coating (4) and the passive surface segments (5, 5a, 5b, 5c) have a second reflective coating (6), wherein the first reflective coating (4) and second reflective coating (6) each have a number of layers (7, 7a, 7b, 7c, 7d, 7e,7f) comprise of the same material and arranged in the same sequence, such that the first reflective coating (4) and the second reflective coating (6) differ from each other only in terms of the thickness of the individual layers (7, 7a, 7b, 7c, 7d, 7e, 7f), wherein the coated Fresnel structure is arranged in the optical waveguide (8) such that light from a display incident on the Fresnel structure, which after transmission through an active area segment (3, 3a, 3b, 3c) strikes a passive area segment (5, 5a, 5b, 5c), is reflected in such a way that it does not strike an active area segment (3, 3a, 3b, 3c) again.

2. Optical arrangement according to claim 1, characterized in that the thickness of each individual layer (7, 7a, 7b, 7c, 7d, 7e, 7f) of the first reflective coating (4) is greater than the thickness of the respective corresponding individual layer (7, 7a, 7b, 7c, 7d, 7e, 7f) of the second reflective coating (6). Z50376-WO 34 PATERI S 3. Optical arrangement according to claim 1, characterized in that the thickness of each individual layer (7, 7a, 7b, 7c, 7d, 7e, 7f) of the first reflective coating (4) is smaller than the thickness of the respective corresponding individual layer (7, 7a, 7b, 7c, 7d, 7e, 7f) of the second reflective coating (6).

4. Optical arrangement according to one of claims 1 to 3, characterized in that the coated Fresnel structure is arranged within the optical waveguide (8) such that an angle of incidence of the incident light of a display onto an active area segment (3, 3a, 3b, 3c) is smaller than an angle of incidence of the light onto a passive area segment (5, 5a, 5b, 5c) after transmission through the active area segment (3, 3a, 3b, 3c).

5. Optical arrangement according to one of claims 1 to 4, characterized in that the optical waveguide (8) comprises a base substrate on which the Fresnel structure is arranged, and a filler substrate which covers the Fresnel structure and encapsulates it within the optical waveguide (8) and is arranged in a beam path such that incident light from a display passes through the base substrate before it strikes an active surface segment (3, 3a, 3b, 3c) and passes through the filler substrate after transmission through the active surface segment (3, 3a, 3b, 3c) and before striking a passive surface segment (5, 5a, 5b, 5c), wherein the base substrate and the filler substrate each have a refractive index and the refractive indices differ from each other by less than 0.

01.

6. Optical arrangement according to one of claims 1 to 5, characterized in that the Fresnel element (1 ) is configured such that the passive surface segments (5, 5a, 5b, 5c) are illuminated by the active surface segments (3, Z50376-WO 35 PATERI S 3a, 3b, 3c) transmitted light has a higher reflectance than the active surface segments (3, 3a, 3b, 3c) for light directly incident on them.

7. Optical arrangement according to one of claims 1 to 6, characterized in that one or more of the individual layers (7, 7a, 7b, 7c, 7d, 7e, 7f) of the first reflective coating (4) and the second reflective coating (6) comprise silicon dioxide and / or trititanium pentoxide and / or aluminum trioxide and / or zirconium dioxide and / or magnesium fluoride and / or tantalum trioxide.

8. Spectacle lens (100, 100a, 100b) for a head-mounted display (200), characterized in that the spectacle lens (100, 100a, 100b) comprises an optical arrangement according to one of claims 1 to 7.

9. Head-mounted display (200), characterized in that the head-mounted display (200) comprises an optical arrangement according to one of claims 1 to 7 or a spectacle lens (100, 100a, 100b) according to claim 8.

10. Method (300) for manufacturing an optical arrangement for a head-mounted display (200), characterized in that the method (300) comprises the following steps: - Providing a Fresnel structure on a base substrate (17) of an optical waveguide (8), wherein the Fresnel structure comprises a plurality of active surface segments (3, 3a, 3b, 3c) and a plurality of passive surface segments (5, 5a, 5b, 5c), wherein the passive surface segments (5, 5a, 5b, 5c) are arranged in a step-like fashion between the active surface segments (3, 3a, 3b, 3c) and connect them together, Z50376-WO 36 PATERI S - Coating the Fresnel structure by simultaneously applying material by depositing coating materials from a gas phase onto the active surface segments (3, 3a, 3b, 3c) and the passive surface segments (5, 5a, 5b, 5c), such that a first reflective coating (4) is formed on the active surface segments (3, 3a, 3b, 3c) and a second reflective coating (6) is formed on the passive surface segments (5, 5a, 5b, 5c), wherein the first reflective coating (4) and the second reflective coating (6) each comprise a number of layers (7, 7a, 7b, 7c, 7d, 7e, 7f) of the same material and arranged in the same sequence, such that the first reflective coating (4) and the second reflective coating (6) differ only with respect to the thickness of the individual layers (7, 7a, 7b, 7c, 7d, 7e, 7f) differ from each other.

11. Method (300) according to claim 10, characterized in that the coated Fresnel structure is coated with a filler material to form a filler substrate (18) which covers the Fresnel structure and encapsulates it within the optical waveguide (8), wherein the base substrate (17) and the filler substrate (18) each have a refractive index and the refractive indices differ from each other by less than 0.01, wherein the first reflective coating (4) and / or the second reflective coating (6) are formed by physical vapor deposition of the coating materials.

12. Method (300) according to claim 10 or 11, characterized in that the gas phases of the coating materials are generated by means of one or more evaporation source(s).

13. Method (300) according to claim 12, characterized in that Z50376-WO 37 PATERI S before coating the base substrate (17) of the optical waveguide (8) with the Fresnel structure to generate a predetermined thickness of the individual layers (7, 7a, 7b, 7c, 7d, 7e, 7f) of the first reflective coating (4) and the second reflective coating (6) is spatially positioned in a predetermined manner with respect to the one or more evaporation source(s).

14. Method (300) according to claim 12 or 13, characterized in that the coating comprises moving the optical waveguide (8) with the Fresnel structure in a predetermined manner with respect to one or more evaporation sources in relation to the optical waveguide (8) with the Fresnel structure in order to produce the predetermined thickness of the individual layers (7, 7a, 7b, 7c, 7d, 7e, 7f) in a predetermined manner and / or moving the optical waveguide (8) with the Fresnel structure in a predetermined manner with respect to one or more evaporation sources.

Images