Optical device comprising an optical waveguide and an optical module for suppressing stray light, display device comprising such an optical device, and method for producing an optical module of such an optical device
Patent Information
- Application Number
- PCT/EP2026/056527
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-11
- Filing Date
- 2026-03-10
- Publication Date
- 2026-09-17
Smart Images
Figure EP2026056527_17092026_PF_FP_ABST
Abstract
Description
[0001] patent attorneys
[0002] GEYER, FEHNERS & PARTNER
[0003] Munich - Jena
[0004] tooz technologies GmbH
[0005] Attorney's file: PAT 4377 / 062-PCT
[0006] Optical device with an optical waveguide and an optical module for suppressing stray light, display device with such an optical device, and manufacturing method for an optical module of such an optical device.
[0007] The present invention relates to an optical device with an optical waveguide and an optical module for suppressing stray light, a display device with such an optical device, and a manufacturing method for an optical module of such an optical device.
[0008] Unwanted light, or stray light, is typically suppressed in optical systems by appropriately positioned and dimensioned apertures. A good example of this is Köhler illumination, which has long been used in light microscopes. With Köhler illumination, both the illuminated field and the illumination aperture can be adjusted as needed using apertures. Even unwanted stray light paths in more complex systems can be eliminated by appropriately positioned apertures.
[0009] This requires that the system's design allows for the appropriate arrangement of the necessary apertures.
[0010] One system where this is not possible is a so-called smart spectacle lens, or a lens for a display device that is placed on the user's head and generates an image. The smart spectacle lens functions optically like a classic magnifying glass. A small object (image source) is projected onto the user's retina by the combined action of the smart spectacle lens and the user's eye lens in such a way that the user can perceive a sufficiently magnified image at an apparent distance equal to or greater than their clear vision distance. The smart spectacle lens must therefore fulfill not only an imaging function but also a light-guiding function.
[0011] The latter results from the fact that the image sensor is most sensibly integrated laterally into the temple of the glasses, but the viewing direction to the data display can only deviate from the "horizontal-straight ahead" viewing direction by limited angles (e.g. 12° horizontal, 8° vertical).
[0012] This means that, unlike with classic conventional systems, in addition to the refraction at the entry and exit surfaces of the spectacle lens, patent attorneys
[0013] GEYER, FEHNERS & PARTNER
[0014] Munich - Jena
[0015] 2. One or more reflections must occur at planar, curved, and / or freeform surfaces of the spectacle lens. The imaging effect of the spectacle lens is therefore not concentrated on a few surfaces adapted to the image (e.g., spherical), but is distributed across several surfaces along the light path, which are often curved (e.g., spherical).
[0016] Freeform surfaces). In addition, the surfaces involved in the light guidance or imaging are strongly inclined against the main beam directions.
[0017] The consequence is that there is no suitable position between the image sensor and the eye where an aperture could be placed to suppress unwanted light. Furthermore, an aperture positioned in the light path would lie in front of the eye of the glasses wearer, thereby undesirably impairing their primary line of sight.
[0018] Since the angular spectrum generated and coupled in by the image sensor is significantly larger than the angular spectrum required for image generation, the geometry of the data spectacle lens results in various unwanted light paths in addition to the useful light channel, which can ultimately lead to a superimposition of the image with unwanted background light.
[0019] From EP 3911 979 B1, a display device that can be placed on a user's head and generates an image is known, which has an angle filter with, for example, two or three prisms for suppressing stray light. These prisms are configured to reject light at predetermined angles, e.g., high angles, by total internal reflection. A compact design is not achieved, particularly with three prisms. From US 2021 / 0247610 A1, a display device that can be placed on a user's head and generates an image is known, which has one or more transmissive angle-sectional layers for suppressing stray light.
[0020] Based on this, the object of the invention is to provide an optical device with an optical module and an optical waveguide with which the difficulties described above can be overcome as completely as possible. Furthermore, a display device with such an optical device and a method for manufacturing an optical module for suppressing stray light in such an optical device are to be provided.
[0021] The invention is defined in independent claims 1, 16 and 17. Advantageous embodiments are specified in the dependent claims.
[0022] An optical device is provided, comprising an optical module and an optical waveguide downstream of the optical module, the waveguide having an entrance section and a spaced-apart exit section, wherein the optical module directs the supplied useful light to the entrance section, through which it is coupled into the optical waveguide. The patent attorneys
[0023] GEYER, FEHNERS & PARTNER
[0024] Munich - Jena
[0025] 3. The coupled useful light is guided by at least one reflection to the exit section, through which the useful light exits the optical waveguide. The optical module is designed for stray light suppression to prevent unwanted first stray light, which is also supplied to the optical module due to the supply of the useful light, from striking the entrance section. For this purpose, the optical module has a continuous first surface with locally varying light-guiding properties depending on the point of incidence and the angle of incidence onto the first surface. The first surface is arranged such that both the useful light and the first stray light strike it, and the angles of incidence of the light rays of the useful light onto the first surface differ from the angles of incidence of the light rays of the first stray light onto the first surface.
[0026] and wherein the first surface is designed such that at least part of the light rays of the useful light hits the entrance section and at least part of the light rays of the first disturbance light does not hit the entrance section.
[0027] In particular, the locally varying light-guiding properties of the connected first surface can be characterized by the fact that light rays propagating along a first direction (and thus preferably parallel light rays) and striking the first surface, depending on the point of impact on the first surface
[0028] - propagate through the first surface in such a way (especially by transmitting and / or being diffracted) that their further directions of propagation differ,
[0029] - propagate through the first surface (especially transmit and / or be diffracted) or be reflected by means of the first surface, so that their further propagation directions differ, or
[0030] - are reflected by the first surface in such a way that their further directions of propagation differ.
[0031] The continuous first surface is therefore not constant in its light-guiding properties over the entire surface, but has at least two (or more) areas that guide (propagate or reflect) two parallel light rays, one of which hits one area and the other the other area, in such a way that the further directions of propagation of the two light rays differ.
[0032] The contiguous first surface can have one or more areas, each with constant light-guiding properties that differ from area to area. Alternatively, at least one area itself can have a locally varying light-guiding property. Additionally or alternatively, the entire patent holders
[0033] GEYER, FEHNERS & PARTNER
[0034] Munich - Jena
[0035] 4 contiguous first surfaces exhibit a locally varying light-guiding property (preferably without areas with locally constant light-guiding properties).
[0036] This allows disruptive and unwanted effects that would be caused by the first stray light, such as unintentional double images, blurring, ghosting, etc., to be effectively suppressed or significantly reduced.
[0037] Here, (e.g., first) stray light refers in particular to the light which, after passing through the optical fiber, leads to the aforementioned undesirable effects, such as scattered light.
[0038] The locally varying light-guiding properties of the first surface can be designed to increase the amount of useful light hitting the entrance section and / or to decrease the amount of first ambient light hitting the entrance section.
[0039] The first surface can be designed such that either
[0040] a) which propagates at least a part of the light rays of the useful light through the first surface in such a way that it hits the entrance section, and which reflects at least a part of the light rays of the first interfering light by means of the first surface in such a way that it does not hit the entrance section,
[0041] or
[0042] b) that at least part of the light rays of the useful light is reflected by means of the first surface in such a way that it hits the entrance section, and that at least part of the light rays of the first interfering light is propagated through the first surface in such a way that it does not hit the entrance section.
[0043] In the optical device, the first stray light can propagate along a first stray light path, and the optical module can further comprise a second continuous surface with light-guiding properties depending on the angle of incidence onto the second surface, which is arranged such that light rays of the useful light and light rays of an unwanted second stray light, which is also supplied to the optical module with the useful light and propagates along a second stray light path that differs from the first stray light path, meet on it, wherein the angles of incidence of the light rays of the useful light on the second surface differ from the angles of incidence of the light rays of the second stray light on the second surface, and wherein the second surface is designed such that at least a portion of the light rays of the useful light is steered by the second surface so that it strikes the entrance section.while at least part of the light rays of the second interfering light is deflected by the second surface in such a way that it does not strike the entrance section. Patent attorneys,
[0044] GEYER, FEHNERS & PARTNER
[0045] Munich - Jena
[0046] 5
[0047] The first and second surfaces can be arranged non-parallel to each other.
[0048] The light-guiding properties of the second surface can vary locally and depend on the point of incidence on the second surface. In particular, the locally varying light-guiding properties of the second surface can be designed to increase the amount of useful light reaching the entrance section and / or decrease the amount of second ambient light reaching the entrance section.
[0049] The first surface can be curved. In particular, the first surface can be spherical, aspherical, toric, conical, pyramidal, and / or freeform. The first surface can additionally, alternatively, or with multiple (planar and curved, planar, or curved) sub-surfaces. Preferably, the sub-surfaces are inclined relative to each other.
[0050] The first surface can be realized by an air gap, by an interface between two materials with different refractive indices, by a layer of angle-selective material, and / or by multiple layers of angle-selective material. The first surface can also be realized by an interference layer system. The interference layer system can consist of at least two different materials with different refractive indices.
[0051] In particular, the interference layer system can contain two, three, four, five, or more different materials. The refractive indices of the materials can range from 1.4 to 2.5 at a wavelength of 546 nm.
[0052] The optical module can comprise at least two optical bodies made of glass and / or plastic, with the first surface located between them. The optical module can be designed as a prism element and, in particular, as a so-called TIR prism (total internal reflection).
[0053] The first surface can be designed as an inner surface of the optical module.
[0054] The optical module can have at least two prisms, between which the first surface lies.
[0055] The second surface can be curved. In particular, the second surface can be spherical, aspherical, toric, conical, pyramidal, and / or freeform. The second surface can additionally, alternatively, or with multiple (planar and curved, planar, or curved) sub-surfaces. Preferably, the sub-surfaces are inclined relative to each other. Patent Attorneys
[0056] GEYER, FEHNERS & PARTNER
[0057] Munich - Jena
[0058] 6
[0059] The second surface can be realized by an air gap, by an interface between two materials with different refractive indices, by an angle-selective layer material, and / or by multiple layers of angle-selective material. The second surface can also be realized by an interference layer system. The interference layer system can be composed of at least two different materials with different refractive indices. In particular, the interference layer system can comprise two, three, four, five, or more different materials. The refractive indices of the materials can be in the range of 1.4 to 2.5 at a wavelength of 546 nm.
[0060] The optical module can comprise at least two optical bodies made of glass and / or plastic, between which the v-surface lies. The optical module can be designed as a prism element and, in particular, as a so-called TIR prism (total internal reflection).
[0061] The second surface can be designed as an inner surface of the optical module.
[0062] The optical module can have at least two prisms, between which the second surface lies.
[0063] The optical module can have at least two optical bodies made of glass and / or plastic, between which the second surface is located.
[0064] The second surface can be designed as an inner surface of the optical module.
[0065] The first and second inner surfaces can each be cone-shaped or pyramid-shaped, with the first and second surfaces being arranged so that the tips of the first and second surfaces face each other.
[0066] In the optical device, the useful light can be supplied to the optical module via a first interface, wherein the first interface is planar, curved and / or may have several flat or curved sub-surfaces that are inclined and / or offset from each other.
[0067] The optical module may have a light-absorbing layer or coating arranged such that at least some of the unwanted stray light strikes it. Patent attorneys
[0068] GEYER, FEHNERS & PARTNER
[0069] Munich - Jena
[0070] 7 The optical module may have at least one light-absorbing mask that defines an aperture through which the useful light is supplied to the optical module, through which the useful light is propagated within the optical module and / or through which the useful light exits the optical module.
[0071] The optical waveguide can be designed as a spectacle lens for a display device that can be placed on a user's head and generates an image, or as part of a spectacle lens for a display device that can be placed on a user's head and generates an image.
[0072] The optical module can be cemented to the optical waveguide.
[0073] The optical module can be made of glass and / or plastic.
[0074] The optical waveguide can be single-layered or multi-layered. If it is multi-layered, the individual layers are connected to each other (preferably across their entire surface).
[0075] The optical waveguide can have one or two reflective surfaces at which the useful light is reflected to be guided from the entrance section to the exit section.
[0076] The reflective surface(s) of the optical waveguide can be located at a material interface with another shell, at a material interface with the environment, and / or within a shell. Additionally or alternatively, it can be a material interface (preferably with the environment) where total internal reflection occurs.
[0077] The optical waveguide and / or each shell can be configured as a plane-parallel plate or as an optical waveguide / shell with at least one curved interface / side. The facing sides of two shells connected to each other (e.g., by means of an adhesive layer) can preferably have complementary curvatures.
[0078] Each of the bowls can be made of glass and / or plastic.
[0079] The optical waveguide can have a deflection section that deflects the useful light so that it exits the optical waveguide via the exit section. The deflection section and the exit section can be spatially separate sections. However, it is also possible for the deflection section and the exit section to coincide spatially, for example, if the deflection section is designed as a surface grating. Patent attorneys
[0080] GEYER, FEHNERS & PARTNER
[0081] Munich - Jena
[0082] 8. The deflection section can be reflective, semi-reflective, refractive, and / or diffractive. In particular, it can have one or more deflection elements.
[0083] In particular, the deflection section can have a single reflective or semi-reflective deflection element or several reflective and / or semi-reflective deflection elements arranged side by side. With several reflective or semi-reflective deflection elements arranged side by side, a desired deflection function and, if necessary, a certain imaging function of the deflection section can be realized, for example, in a Fresnel-like manner (this can, of course, also be achieved with a single reflective or semi-reflective deflection element). The reflective or semi-reflective deflection elements can be reflective or semi-reflective surface sections, which can also be referred to as reflective or semi-reflective facets. The reflective or semi-reflective surface sections can each be planar. However, it is also possible for the reflective or semi-reflective surfaces to be...The partially reflective surface sections themselves are curved (for example, spherically or aspherically curved, or freeform). Similarly, the single reflective or partially reflective deflecting element can be flat or curved (for example, spherically or aspherically curved, or freeform).
[0084] The reflectivity of the respective reflective deflection elements (or the single reflective deflection element) can, for example, range from 2% to 100% (including the limits of this range). Thus, the reflective deflection elements can be partially reflective or fully reflective.
[0085] The optical waveguide can, in particular, have a curved back side and / or a curved front side. The entry section can be located in the back side.
[0086] A display device is provided comprising a holding device that can be placed on the user's head, an image generation module attached to the holding device which generates an image, and an optical device according to the invention (including all further developments) attached to the holding device, wherein the generated image is supplied as useful light from the image generation module to the optical module, the optical module supplies the useful light to the entrance section of the optical waveguide, suppressing unwanted stray light, and wherein, when the holding device is placed on the head, the optical waveguide projects the useful light from the exit section into one of the user's eyes, so that the user can perceive it as a virtual image.
[0087] The image generation module can produce a monochrome image or a multi-colored image. Patent attorneys
[0088] GEYER, FEHNERS & PARTNER
[0089] Munich - Jena
[0090] 9 The display device may include a control unit that controls the image generation module. In particular, the control unit may control the image generation module based on supplied image data.
[0091] The image generation module and / or an image sensor unit of the image generation module may, in particular, comprise a planar image sensor, such as an LCD module, an LCoS module, an OLED module, a pLED, or a tilting mirror matrix. Each image sensor may have a plurality of pixels, which may be arranged, for example, in rows and columns. Each image sensor may, for example, be self-illuminating or non-self-illuminating.
[0092] Each image sensor can preferentially produce a monochromatic image, while different image sensors can produce monochromatic images with different wavelengths.
[0093] The image generation module can, for example, comprise a polychromatic image source, a combination of two or more monochromatic image sources, or a combination of a duochromatic and a monochromatic image source. Typical configurations of such image generation modules with multiple image sources include a superposition unit that combines the light beams of the multiple image sources into a single, common light beam. Such a superposition unit can be implemented, for example, as a beam splitter cube (also called an X-cube) or as a so-called rod combiner, both of which are known to those skilled in the art.
[0094] Since the diverting section should be as invisible as possible and should also have as little impact as possible on the light reaching the viewer's eye from the surroundings, diverting sections with high transmission and, consequently, low reflectivity for the light beam(s) of the at least two-color image are generally preferred. Typical values for the reflection-to-transmission ratio are 50%, 30%, 10%, or 2%, distributed evenly across the visible wavelength range.
[0095] Furthermore, a method for manufacturing an optical module for suppressing stray light in an optical device for a head-worn display device is provided, wherein the optical device comprises an optical waveguide for guiding useful light from an inlet section to an outlet section by means of at least one reflection, wherein the optical waveguide is arranged downstream of the optical module, which is designed to receive the useful light and supply it to the inlet section, while unwanted stray light is suppressed by first deflecting stray light, which is also due to the optical module.
[0096] GEYER, FEHNERS & PARTNER
[0097] Munich - Jena
[0098] 10. The supply of useful light is directed in such a way that it does not hit the entrance section.
[0099] the procedure comprises the following steps:
[0100] a) Creating a digital model of the optical device that models the supply of useful light into the optical module and from the optical module to the entrance section of the optical waveguide, the guiding of the useful light through the optical waveguide to the exit section and a projection of the useful light from the exit section into an exit pupil,
[0101] b) Determining a first region of the optical module in the digital model in which the propagation directions of light rays of the useful light and light rays of the first background light differ from each other,
[0102] c) Extending the digital model by a connected first surface with light-directing properties depending on an angle of incidence of light on the first surface, which is arranged in the specified first region such that, due to angles of incidence of the light rays of the useful light on the first surface that differ from angles of incidence of the light rays of the first extraneous light on the first surface, at least a part of the light rays of the useful light is directed by the first surface so that it strikes the entrance section, while at least a part of the light rays of the first extraneous light is directed by the first surface so that it does not strike the entrance section.
[0103] d) Optimization of the light-guiding properties of the first surface in the digital model by determining local variations of the light-guiding properties as a function of the angle of incidence and the point of impact of the light on the first surface in order to increase the amount of useful light reaching the entrance section and / or to decrease the amount of first stray light reaching the entrance section.
[0104] e) Manufacturing the optical module with the first surface that has the locally varying light-guiding properties according to step d).
[0105] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations given, but also in other combinations or on their own, without leaving the scope of the present invention.
[0106] The invention is explained in more detail below with reference to exemplary embodiments and the accompanying drawings, which also disclose essential features of the invention. These exemplary embodiments serve only for illustration and are not to be interpreted as limiting. For example, a description of an exemplary embodiment with a plurality of elements or components is not to be interpreted as meaning that all of these elements or components are necessary for implementation. Rather, other exemplary embodiments may also include alternative elements and components.
[0107] GEYER, FEHNERS & PARTNER
[0108] Munich - Jena
[0109] Figure 11 contains fewer elements or components, or additional elements or components. Elements or components from different embodiments can be combined unless otherwise specified. Modifications and variations described for one embodiment may also be applicable to other embodiments. To avoid repetition, identical or corresponding elements in different figures are designated with the same reference numerals and are not explained multiple times. The figures show:
[0110] Fig. 1 is a schematic perspective representation of an embodiment of the display device according to the invention;
[0111] Fig. 2 shows an enlarged schematic partial sectional view of the optical device 16 including a schematic representation of the first image generation module 5 according to Fig. 1;
[0112] Fig. 3 shows an enlarged schematic partial sectional view of the optical device 16 including the first image-generating element 8 to illustrate the useful light path 19;
[0113] Fig. 4 shows an enlarged schematic partial sectional view of the optical device 16 including the first image-generating element 8 to illustrate the first stray light path 20, assuming that the first optical module 9 has no air gap 24, 25;
[0114] Fig. 5 shows an enlarged schematic partial sectional view of the optical device 16 including the first image-generating element 8 to illustrate the second stray light path 22, assuming that the first optical module 9 has no air gap 24, 25;
[0115] Fig. 6 shows an enlarged schematic partial sectional view of the optical device 16 including the first image-generating element 8 to illustrate the useful light path 19 as well as the first and second stray light paths 20, 22, particularly in the first optical module 9, assuming that the first optical module 9 has no air gap 24, 25;
[0116] Fig. 7 shows an enlarged schematic partial sectional view of the optical device 16 including the first image-generating element 8, in which the effect of the two air gaps 24, 25 in the first optical module 9 is shown;
[0117] Fig. 8 shows an enlarged schematic partial sectional view of the first optical module 9 of the display device 1 of Figure 1 to describe the separation of useful light L1 and stray light 21, 23;
[0118] Fig. 9 an enlarged schematic partial sectional view of the first optical module 9 according to a further embodiment to describe the separation of useful light L1 and stray light 21, 23; patent attorneys
[0119] GEYER, FEHNERS & PARTNER
[0120] Munich - Jena
[0121] 12 Fig. 10 an enlarged schematic partial sectional view of the first optical module 9 according to a further embodiment to describe the separation of useful light L1 and stray light 21, 23;
[0122] Fig. 11 shows an enlarged perspective view of the first optical module 9 according to a further embodiment to describe the separation of useful light L1 and stray light 21, 23;
[0123] Fig. 12 shows an enlarged schematic partial sectional view of the first optical module 9 according to a further embodiment to describe the separation of useful light L1 and stray light 21, 23;
[0124] Fig. 13 shows an enlarged schematic partial sectional view of the optical device 16 including the first image-generating element 8 to illustrate a non-inventive blocking of the two stray light paths 20, 22 in the first spectacle lens;
[0125] Fig. 14 shows an enlarged schematic partial sectional view of the optical device 16 including the first image-generating element 8 according to a further embodiment in which the first path of stray light 20 is blocked by means of the air gap 24;
[0126] Fig. 15 shows an enlarged schematic partial sectional view of the optical device 16 including the first image-generating element 8 according to a further embodiment in which the second path of stray light 22 is blocked by means of the air gap 25;
[0127] Fig. 16 shows an enlarged schematic partial sectional view of the optical device 16 including a schematic representation of the first image generation module 5 according to a further embodiment of the invention, and
[0128] Fig. 17 shows a flowchart describing a method for manufacturing a first optical module 9.
[0129] In the embodiment shown in Fig. 1, the display device 1 according to the invention comprises a holding device 2 that can be placed on the user's head and which may, for example, be designed in the manner of a conventional eyeglass frame, as well as a first and a second lens 3, 4, which are attached to the holding device 2. The first lens 3 and / or the second lens 4 can each be designed as a lens according to the invention. The holding device 2 with the lenses 3, 4 can, for example, be designed as sports glasses, sunglasses, and / or glasses for correcting a visual impairment, wherein a virtual image can be projected into the user's field of vision via the first lens 3, which may also be referred to as a multifunctional lens or optical fiber, as described below. Patent Attorneys
[0130] GEYER, FEHNERS & PARTNER
[0131] Munich - Jena
[0132] 13 The display device 1 includes a first image generation module 5, which can be arranged in the area of the right temple of the holding device 2, as shown schematically in Fig. 1.
[0133] The first image generation module 5 can include a first image transmitter unit 7 for generating a first image, as schematically illustrated in Fig. 2. For this purpose, the first image transmitter unit 7 comprises a first planar image generation element 8, to which a first optical module 9 is subordinate. The first planar image generation element 8 can, for example, comprise an OLED element, an LCD element, an LCoS element, a pLED, or a tilting mirror matrix, each comprising a plurality of pixels arranged, for example, in rows and columns. A single light beam L1 is schematically depicted as a representative of the light beams emitted by the first planar image generation element 8. The first optical module 9 and the first spectacle lens 3 together form an optical device V.
[0134] Between the first image-generating element 8 and the first optical module 9, a first image-transmitting optic 40, shown as part of the first image-transmitting unit 7, may, but does not have to, be arranged. The first image-transmitting optic 40 preferably has an optical imaging property.
[0135] As can be further seen in Fig. 2, a control unit S with, for example, a processor P and a memory M is provided for controlling the first image generation module 5. The control unit S, which can, for example, be arranged on the holding device 2, controls the first image generation module 5, and in particular the first image generation element 8, depending on the supplied image data, such that a first image is generated according to the image data. The light beams L1 emitted by the first image generation element 8 enter the first optical module 9 via a first surface 41, pass through the first optical module 9, exit the first optical module 9 via a second surface 42, and then enter the first spectacle lens 3. The area at which the light beams enter the first spectacle lens 3 can also be referred to as the entry surface 10 or entry section 10.
[0136] The first spectacle lens 3 has, in addition to the entrance surface 10, a (here curved) deflecting surface 11 that deflects the light beams L1 in a first direction (here the y-direction) to a deflecting section 12 spaced apart in the first direction, such that the light beams L1 are guided to the first deflecting section 12 by one or more reflections at a front surface 13 and / or by one or more reflections at a back surface 14 of the first spectacle lens 3. The reflection(s) at the front and / or back surface can be, for example, total internal reflection, reflection at a reflective layer (not shown), and / or reflection at reflective coatings (not shown). Patent attorneys
[0137] GEYER, FEHNERS & PARTNER
[0138] Munich - Jena
[0139] 14
[0140] The first deflection section 12, which here has several partially reflective deflection elements 12', then deflects the light beams L1 such that the deflected light beams L1 exit the first lens 3 via the back surface 14, thus creating a virtual image that the user can perceive with their eye A. The area through which the light beams L1 exit can also be referred to as the exit section 15 or exit surface 15.
[0141] Thus, in the first spectacle lens 3 there is a first light guiding channel 21 which extends along the first direction from the entry section 10 to the first deflection section 12.
[0142] Thus, the first spectacle lens 3 is an embodiment of an optical waveguide 3, which has an entry section 10 and an exit section 15 spaced apart from it, and which guides useful light L1 coupled in via the entry section 10 by means of at least one reflection to the exit section 15, through which the useful light L1 exits the optical waveguide 3.
[0143] The optical waveguide 3 together with the first optical module 9 forms an optical device 16 according to the invention. The first optical module 9, which is only shown schematically in Figure 2, serves to suppress stray light, as described below.
[0144] To simplify the illustration, the air gaps 24, 25 described below and shown in Figure 7 are not shown in Figure 2 and Figure 3.
[0145] Figure 3 shows a perspective view of the optical device 16, illustrating the path of the useful light L1. Due to the perspective view, the edge 17 connecting the front and back surfaces 13, 14 is visible.
[0146] Figure 3 schematically depicts all light rays (= useful light L1) required for image generation, which travel along a useful light path 19 through the optical module 9 and the first lens 3 and are coupled out of the first lens 3. The coupled-out useful light L1 travels to an exit pupil 18, which can also be called the eyebox 18. During normal use of the display device, the user's eye A is located at the position of the exit pupil 18.
[0147] Since the angular spectrum generated by the first image-generating element 8 and coupled into the first optical module 9 is significantly larger than the angular spectrum required for image generation, the geometry of the first spectacle lens 3 results in one or more different undesired light paths or patent holders in addition to the useful light path 19.
[0148] GEYER, FEHNERS & PARTNER
[0149] Munich - Jena
[0150] 15 light paths that can ultimately lead to the generated image being superimposed with unwanted stray light. This can be demonstrated through optical simulations.
[0151] Figure 4 shows the optical device 16 in perspective, as in Figure 3, with a first stray light path 20 indicated and assuming that the first optical module 9 has no air gap 24, 25. The light 21 passing through the first stray light path 20 therefore reaches the exit pupil 18 and can be referred to as the first stray light 21. Since the first lens 3 is not designed for the first stray light 21, the first stray light 21, which reaches the exit pupil 18, leads to a deteriorated image (e.g., as an unwanted double image).
[0152] The same applies to the second stray light 23 shown schematically in Figure 5, which runs through a second stray light path 22 and can reach the exit pupil 18, since it is again assumed that the first optical module 9 does not have an air gap 24, 25.
[0153] In the enlarged perspective view in Figure 6, both the useful light path 19 and the two stray light paths 20 and 22 are shown schematically, again assuming that the first optical module 9 has no air gap 24, 25.
[0154] Since the orientation of the useful light path 19 in the first optical module 9 differs from both the orientation of the first stray light path 20 and the orientation of the second stray light path 22 in the first optical module 9 (as can be seen in Figures 3-6), the first optical module 9 is designed such that it reflects the first and second stray light 21, 23 by means of total internal reflection, preventing it from entering the first lens 3. The useful light, however, is transmitted and enters the first lens 3 via the entrance section 10.
[0155] As shown in the schematic diagram in Figure 7, the first optical module 9 has a first air gap 24 at which, due to total internal reflection, the first stray light 21 is reflected so that it does not enter the first lens 3. Furthermore, the first optical module 9 has a second air gap 25 at which, due to total internal reflection, the second stray light 23 is reflected so that it does not enter the first lens 3. The useful light L1, on the other hand, is not reflected at either of the two air gaps 24, 25, but propagates further along the useful light path 19 through the first optical module 9 (as shown in Figure 3) and enters the first lens 3 via the coupling section 10. For the sake of simplicity, the useful light L1 is not shown in Figure 7.
[0156] GEYER, FEHNERS & PARTNER
[0157] Munich - Jena
[0158] 16 This selective angle-dependent reflectivity of the first and second air gap 24, 25 for the useful light L1 and the first and second stray light 21, 23 is possible due to the different orientations of useful light path 19 and stray light paths 20, 22 in the first optical module 9.
[0159] Thus, the first optical module 9 has an air gap 24, 25 inclined to match the respective stray light beam 21, 23, in order to reflect the stray light 21, 23 out of the first optical module 9 by total internal reflection, while the useful light L1 can pass through the first optical module 9. An advantage of this solution is that the unwanted stray light 21, 23 is not coupled into the first lens 3, but is filtered out beforehand.
[0160] The stray light 21, 23 reflected at the air gaps 24, 25 can, for example, strike absorbing (edge) surfaces 43, 44 of the first optical module 9 and be absorbed there. Alternatively, instead of absorption of the stray light 21, 23, it can be deflected in such a way that it does not impair the user or the useful light L1 perceptible to the user.
[0161] However, the two air gaps 24, 25 are designed such that they do not exhibit uniform angular selectivity. For example, the first air gap 24 has a flat first region 24i and an adjoining flat second region 242, with the two regions 24i and 242 being inclined to each other and thus enclosing an angle other than 180°, as shown, for example, in Fig. 8. Thus, there is a continuous first air gap 24 that exhibits locally varying light-guiding properties depending on the point of incidence and the angle of incidence onto the first air gap 24.
[0162] Figure 8 shows two light rays L11 and L12 (with solid lines) from the useful light path 19, which, due to the present optical design, are parallel to each other, with light ray L11 striking the first region 24i and light ray L12 striking the second region 242. Figure 8 also shows two light rays 211 and 212 (with dashed lines) from the first stray light 21, which, due to the present optical design, are not parallel to each other, with light ray 211 striking the first region 24i and light ray 212 striking the second region 242. The orientation of the two areas 241, 242 is chosen such that both light rays L11, LI2 propagate from the useful light path 19 through the air gap 24, whereas the two light rays 211, 212 of the first stray light 21 are reflected due to total internal reflection, so that the desired separation of useful light L1 and first stray light 21 can be ensured.If the air gap 24 in the section of the second area 242 were formed at the same inclination as the first area 24i, as shown in Figure 8 with the dashed line 24', the light beam 212 would pass through the air gap 24.
[0163] GEYER, FEHNERS & PARTNER
[0164] Munich - Jena
[0165] 17 propagate as shown by the arrow 21 ' with a dashed line. Thus, there would be a poorer separation of useful light L1 and first stray light 21.
[0166] The second air gap 25, like the first air gap 24, has a flat first region 25i and an adjoining flat second region 252, wherein the two regions 25i and 252 are inclined to each other and thus enclose an angle of non-180°, as shown, for example, in Fig. 8. This results in a continuous second air gap 25, which exhibits locally varying light-guiding properties depending on the point of incidence and the angle of incidence onto the first air gap 25. Thus, like the first air gap 24, the second air gap 25 can effectively separate the second stray light 23 from the useful light L1. For the sake of simplicity, this is not shown in Fig. 8.
[0167] Although the first and second air gaps 24 and 25 are always mentioned here, total internal reflection naturally occurs at the material interface (transition from the optically denser medium to the optically less dense medium). This transition from the optically denser medium (= material of the optical module 9) to the optically less dense medium (= air) can also be referred to as filter surfaces 24, 25, 24i, 242, 25i, and 252.
[0168] Instead of an air gap 24, 25, a cement layer (not shown) can also be used if the refractive index of the cement is sufficiently lower than that of the surrounding material of the first optical module 9.
[0169] Figure 9 shows an embodiment in which the first air gap or the first filter surface 24 is curved. This further improves the separation of useful light and first stray light 21. The curvature of the filter surface 24 can be, for example, spherical, aspherical, toric, conical, pyramidal, and / or freeform.
[0170] Figure 10 shows an embodiment in which the first filter surface 24 has two planar filter layers 24i, 242, which have different angle-selective properties in order to provide the locally varying light-guiding properties depending on the point of incidence and the angle of incidence on the first filter surface 24. In the embodiment shown, the two filter layers 24i, 242 lie in the same plane.
[0171] The angle-selective reflecting optical layers 24i, 242 (as shown, for example, in Figure 10) can be provided instead of or further in combination with the air gap 24, 25 and / or the cement layer at the same location to similarly define the useful light path 19 by the patent attorneys
[0172] GEYER, FEHNERS & PARTNER
[0173] Munich - Jena
[0174] 18 to separate the interfering light paths 20, 22. For example, the separation efficiency of such an angle-selectively reflecting optical layer can be optimized wavelength-specifically and / or angle-specifically.
[0175] The angle-selective reflecting optical layer 24i, 242 can, for example, be configured as an interference layer system, which, for instance, has alternating thin layers with higher and lower refractive indices. In the general case, the interference layer system can consist of k optical layers Si, S2, ... Sk (k > 2) made of m materials Mi ... M m(m > 2), which differ with respect to their refractive indices Ni... Nj (j > 2), may be formed. Concrete examples of such an interference layer system are described, for example, in WO 2015 / 158833 A1, and there in particular on page 4, lines 16-30, page 9, line 34 - page 10, line 31 in conjunction with Figures 3-5, as well as on page 11, lines 5-26 in conjunction with Figures 7-10. The corresponding disclosure is hereby incorporated into the present description.
[0176] Both the first surface 41 facing the image sensor 8 and the second surface 42 facing the spectacle lens 3 or waveguide 3 can each be designed as a planar, spherical, aspherical, toric and / or freeform surface.
[0177] Figure 11 shows an embodiment in which the filter layers 24 and 25 are curved in a conical shape, with their tips 50, 51 facing each other.
[0178] In the embodiments described in connection with Figures 7 to 11, the surfaces or layers 24, 25 are not arranged parallel to each other.
[0179] In the embodiments described so far, the filter surfaces 24, 25 were inner surfaces in the first optical module 9. Figure 12 shows an embodiment in which the optical module 9 comprises a plane-parallel plate 52, which has the two planar filter layers 24i, 242 on one side.
[0180] In the embodiments described so far, the separation of the useful light L1 and the first and second interference light 21, 23 was achieved by the useful light L1 propagating through the filter surface 24, 25, whereas the interference light 21, 23 was reflected by the filter surface 24, 25. Of course, the separation can also be achieved by the useful light L1 being reflected by the filter surface 24, 25, whereas the interference light 21, 23 propagated through the filter surface 24, 25. It is also possible for both the useful light L1 and the interference light 21, 23 to propagate through the filter surface 24, 25 in such a way that they have such different directions of propagation (e.g., due to refraction) that the interference light does not reach the entrance section 10. Furthermore, both the useful light L1 and the interference light 21, 23 can be propagated by the filter surface 24, 25 in such a way that they have such different directions of propagation (e.g., due to refraction) that the interference light does not reach the entrance section 10. Furthermore, patent attorneys
[0181] GEYER, FEHNERS & PARTNER
[0182] Munich - Jena
[0183] 19 are reflected by means of the filter surface 24, 25 in such a way that they have such different directions of propagation (e.g. due to refraction) that the interfering light does not hit the entrance section 10.
[0184] A further advantage of the stray light suppression using the first optical module 9 is that there is no impairment in the main line of sight through the first lens 3. While it would be possible, as schematically shown in Figure 13, to form an absorbing surface 30 in the first lens 3 to absorb the stray light 21, 23, this would lead to an undesirable impairment in the main line of sight through the first lens 3.
[0185] Figure 14 shows an embodiment in which the first optical module 9 is designed such that only the first path of interference 20 is blocked.
[0186] Figure 15 shows an embodiment in which the first optical module 9 is designed such that only the second path of stray light 22 is blocked.
[0187] In the described embodiments, the first optical module 9 thus provides a material path (e.g., glass path) outside the first spectacle lens 3. The main function of the first optical module 9 is to provide a required material volume in which the desired air gap(s) 24, 25 and / or cement layer(s) and / or angle-selectively reflecting optical layer(s) can be positioned as desired.
[0188] The material interfaces added by the first optical module 9, through which the useful light passes, can of course also be used as additional degrees of freedom for optimizing the imaging beam path (useful light path). Providing these not only as purely planar surfaces, but also as spherical, aspherical, toric, or freeform optical surfaces, is therefore an advantageous, but not necessary, design of the first optical module 9. On the other hand, to avoid chromatic aberrations, it can also be useful to bond the first image-generating element 8 directly to a planar coupling surface (e.g., the first surface 41) of the first optical module 9.
[0189] The first optical module 9 can be manufactured from several sections for ease of production. The number of sections depends on the number and location of the air gaps to be created, and these in turn depend on the number and direction of the stray light paths to be eliminated. Patent attorneys
[0190] GEYER, FEHNERS & PARTNER
[0191] Munich - Jena
[0192] 20 For example, the first optical module 9 can have only one air gap 24, 25, as shown in Figures 9 and 10.
[0193] It is also possible to design the two air gaps 24, 25 in a tilted position relative to each other, so that the blocked disturbances or
[0194] The interference light paths 20, 22 are not deflected or coupled out in opposite directions as shown, but e.g. at approximately 90° or another suitable angle to each other.
[0195] Preferably, no more than two or three air gaps are present in the first optical module 9, which is part of the display device 1 according to the invention, designed to be placed on a user's head. The number of air gaps is essentially limited by the available installation space. More air gaps are certainly possible with optical fibers for other applications.
[0196] In general, the first optical module 9, with or without the first image-forming element 8, can be prefabricated as an assembly and cemented onto the first spectacle lens 3 or positioned at a distance from it. In the case of cementing, it may be necessary to use a low-refractive-index cement or a decoupling coating if the contact surface is also wholly or partially part of a reflective surface for the useful light L1 transmitted in the first spectacle lens 3.
[0197] A special case is the embodiment in which a side of an air gap 24, 25 adjacent to the mountain is already part of the first spectacle lens 3 itself. This is the case, for example, with the prism element 45 in Figure 7.
[0198] The first image generation module 5 and the first spectacle lens 3 are designed such that a user wearing the display device 1 according to the invention on their head can perceive the first image generated by means of the first image generation module 5 as the first virtual image with their first eye A (here the right eye).
[0199] The first image sensor unit 7 can be configured to generate and output a monochromatic (and therefore single-color) image. However, it can also be configured to generate and output a multi-color image.
[0200] Furthermore, it is possible to provide several image generator units 7, 7' and 7" (Fig. 16) which, for example, generate and output a red, green and blue partial image, which can then be combined by means of a superposition unit 35 (for example, a color cube) to form a common patent attorney
[0201] GEYER, FEHNERS & PARTNER
[0202] Munich - Jena
[0203] 21 beam bundles L1 are superimposed, as shown for the first image generation module 5 in Fig. 16.
[0204] Depending on the reflectivity of the deflection elements 12', the user can perceive the first virtual image superimposed on the surroundings. With very high reflectivity, and especially with a reflectivity of 100%, the user can perceive only the first virtual image and not the surroundings, at least in the area of the first deflection section 12, provided a certain distance between the first deflection elements 12' is not exceeded. If this certain distance between adjacent deflection elements 12' is exceeded, ambient light can pass unhindered between them to the eye, so that even with 100% reflectivity of the deflection elements 12', a view of the surroundings is possible, effectively creating a perforated / segmented 100% mirror.
[0205] In the display device 1 according to the invention, the virtual image is projected into the user's field of vision via the first lens 3. Projection via the second lens 4 is also possible. Furthermore, the display device 1 can be designed such that information or virtual images are projected via both lenses 3 and 4. The projection can be arranged to create a three-dimensional image impression. However, this is not mandatory.
[0206] The lenses 3, 4 can have a refractive power of zero or a non-zero refractive power (particularly for correcting a refractive error). In particular, both the front surface 13 and the back surface 14 can be curved. The front surface 13 is, in particular, spherically curved. If the lens 3, 4 has a non-zero refractive power to correct a refractive error, the curvature of the back surface 14 is usually chosen accordingly to achieve the desired correction. The back surface 14 can have a curvature other than spherical.
[0207] The holding device 2 need not be designed as a spectacle-like holding device. Any other type of holding device is also possible, with which the display device 1 can be placed on and worn on the head.
[0208] Furthermore, a method for manufacturing a first optical module 9 is described, wherein the method comprises the following steps (Fig. 17):
[0209] Step S1: Creating a digital model of the optical device V, which represents the supply of the useful light L1 into the optical module 9 and from the optical module 9 to the entrance section 10 of the optical waveguide 3, the guiding of the useful light L1 through the optical waveguide 3 to the patent attorneys
[0210] GEYER, FEHNERS & PARTNER
[0211] Munich - Jena
[0212] 22 Exit section 15 and a projection of the useful light L1 from the exit section 15 into the exit pupil 18 are modeled.
[0213] Step S2: Determining a first area of the optical module 9 in the digital model in which the propagation directions of light rays of the useful light L1 and light rays of the first background light 21 , 23 differ from each other.
[0214] Step S3: Extending the digital model by a connected first surface 24, 25 with light-directing properties depending on an angle of incidence of light on the first surface 24, 25, which is arranged in the specified first region such that, due to angles of incidence of the light rays L1 of the useful light on the first surface 24, 25, which differ from angles of incidence of the light rays 21, 23 of the first ambient light on the first surface 24, 25, at least a part of the light rays L1 of the useful light is directed by the first surface 24, 25 so that it hits the entrance section 10, while at least a part of the light rays 21, 23 of the first ambient light is directed by the first surface 24, 25 so that it does not hit the entrance section 10.
[0215] Step S4: Optimization of the light guidance properties of the first surface 24, 25 in the digital model by determining local variations of the light guidance properties as a function of the angle of incidence and the point of impact of the light on the first surface in order to increase the amount of useful light hitting the entrance section 10 and / or to decrease the amount of first stray light hitting the entrance section 10.
[0216] Step S5: Manufacturing the optical module 9 with the first surface 24, 25, which has the locally varying light-guiding properties according to step S4.
[0217] Optionally, the optical module 9 produced in this way can be used to manufacture the optical device V. The optical device V produced in this way can then be used to manufacture a display device 1.
Claims
patent attorneys GEYER, FEHNERS & PARTNER Munich - Jena 23 tooz technologies GmbH Attorney's file: PAT 4377 / 062-PCT Patent claims 1. Optical device with an optical module (9) and an optical waveguide (3) downstream of the optical module (9), which has an entry section (10) and an exit section (15) spaced apart from it, wherein the optical module (9) directs the supplied useful light to the entrance section (10), via which it is coupled into the optical waveguide (3), wherein the coupled useful light (L1) is guided by means of at least one reflection to the exit section (15), through which the useful light (L1) exits the optical waveguide (3), and wherein the optical module (9) is designed for stray light suppression to prevent unwanted first stray light (21, 23), which is also supplied to the optical module (9) due to the supply of the useful light (L1), from hitting the entrance section (10), wherein the optical module (9) has a connected first surface (24, 25) with locally varying light-guiding properties depending on the point of impact and the angle of incidence on the first surface, wherein the first surface (24, 25) is arranged such that both the useful light and the first stray light strike the first surface (24, 25), where the angle of incidence of light rays (L1) of the useful light on the first surface (24, 25) differs from the angle of incidence of light rays (21, 23) of the first ambient light on the first surface (24, 25). and wherein the first surface is designed such that at least part of the light rays (L1) of the useful light hits the entrance section (10) and at least part of the light rays (21 , 23) of the first disturbance light does not hit the entrance section (10).
2. Optical device according to claim 1 , wherein the locally varying light-guiding properties of the first surface (24, 25) are designed to increase the amount of useful light (L1) that hits the entrance section (10) and / or to decrease the amount of first unwanted light that hits the entrance section (10).
3. Optical device according to claim 1 or 2, wherein the first area (24, 25) is designed such that it either patent attorneys GEYER, FEHNERS & PARTNER Munich - Jena 24 a) transmits at least one part of the light rays (L1) of the useful light in such a way that it hits the entrance section (10), and reflects at least one part of the light rays (21 , 23) of the first interference light (20, 22) in such a way that it does not hit the entrance section (10), or b) reflects at least part of the light rays (L1 ) of the useful light in such a way that it hits the entrance section (10), and transmits at least part of the light rays (21 , 23) of the first interference light (20, 22) in such a way that it does not hit the entrance section (10).
4. Optical device according to one of the above claims, where the first surface (24, 25) is realized by an air gap, by an interface between two materials with different refractive indices, by a layer angle-selective material and / or by several layers of angle-selective material.
5. Optical device according to one of the above claims, in which the optical module (9) has at least two optical bodies made of glass and / or plastic, between which the first surface (24, 25) lies.
6. Optical device according to one of the above claims, where the first surface (24, 25) is designed as an inner surface (24, 25) of the optical module (9).
7. Optical device according to one of the above claims, in which the first interference light propagates along a first interference light path (20, 22) and in which the optical module (9) further has a second continuous surface (24, 25) with light-guiding properties depending on the angle of incidence on the second surface, which is arranged such that light rays of the useful light (L1) and light rays of an unwanted second interference light (21, 23), which is also supplied to the optical module (9) with the useful light (L1) and propagates along a second interference light path (20, 22) that differs from the first interference light path (20, 22), meet on it, wherein the angles of incidence of the light rays (L1) of the useful light on the second surface (24, 25) differ from the angles of incidence of the light rays (21, 23) of the second ambient light on the second surface (24, 25), and wherein the second surface (24, 25) is designed such that at least a portion of the light rays (L1) of the useful light is directed by the second surface (24, 25) so that it strikes the entrance section (10), while at least a portion of the light rays (21, 23) of the second ambient light is directed by the second surface (24, 25) so that it does not strike the entrance section (10). Patent attorneys GEYER, FEHNERS & PARTNER Munich - Jena 25 8. Optical device according to claim 7, wherein the light-guiding properties of the second surface (24, 25) vary locally and depend on the point of impact on the second surface (24, 25), and the locally varying light-guiding properties of the second surface (24, 25) are designed such that they increase the amount of useful light that hits the entrance section (10) and / or decrease the amount of the second extraneous light that hits the entrance section (10).
9. Optical device according to claim 7 or 8, where the second surface (24, 25) is curved.
10. Optical device according to one of the above claims, where the first surface (24, 25) is curved.
11. Optical device according to claim 7 or 8, in which the first and second surfaces (24, 25) are each cone-shaped or pyramid-shaped, wherein the first and second surfaces (24, 25) are arranged such that the tips of the first and second surfaces (24, 25) face each other.
12. Optical device according to one of the above claims, in which the useful light (L1) is supplied to the optical module (9) via a first interface (41), wherein the first interface (41) is planar, curved and / or has several flat or curved sub-surfaces which are inclined and / or offset relative to each other.
13. Optical device according to one of the above claims, wherein the optical module (9) has a light-absorbing layer or a light-absorbing coating arranged such that at least part of the unwanted stray light hits it.
14. Optical device according to one of the above claims, in which the optical module (9) has at least one light-absorbing mask that defines an aperture through which the useful light (L1) is supplied to the optical module (9), through which the useful light (L1) is propagated within the optical module (9) and / or through which the useful light (L1) exits the optical module (9).
15. Optical device according to one of the above claims, patent attorneys GEYER, FEHNERS & PARTNER Munich - Jena 26 in which the optical waveguide (3) is designed as a spectacle lens (3) for a display device that can be placed on the head of a user and produces an image or as part of a spectacle lens (3) for a display device that can be placed on the head of a user and produces an image.
16. Display device with a holding device (2) that can be placed on the head of a user, an image generation module (5) attached to the holding device (2) which generates an image, an optical device attached to the holding device (2) according to one of the above claims, wherein the generated image is supplied as useful light (L1) from the image generation module (5) to the optical module (9), the optical module (9) supplies the useful light (L1) to the entrance section (10) of the optical waveguide (3), whereby unwanted stray light is suppressed, and wherein the optical waveguide (3) projects the useful light (L1) from the exit section (15) into one of the user's eyes so that the user can perceive it as a virtual image when the holding device (2) is placed on the head.
17. Method for manufacturing an optical module for suppressing stray light in an optical device for a head-worn display device (2), wherein the optical device comprises an optical waveguide (3) for guiding useful light (L1) from an inlet section (10) to an outlet section (15) by means of at least one reflection, wherein the optical waveguide (3) is arranged downstream of the optical module (9) which is designed to receive the useful light (L1) and supply it to the inlet section (10), while unwanted stray light is suppressed by directing a first stray light (21, 23), which is also supplied to the optical module (9) due to the supply of the useful light (L1), so that it does not strike the inlet section (10), the procedure comprises the following steps: a) Creating a digital model of the optical device that models the supply of the useful light (L1) into the optical module (9) and from the optical module (9) to the entrance section (10) of the optical waveguide (3), the guidance of the useful light (L1) through the optical waveguide (3) to the exit section (15) and a projection of the useful light (L1) from the exit section (15) into an exit pupil (18), b) Determining a first region of the optical module (9) in the digital model in which the propagation directions of light rays of the useful light (L1) and light rays of the first extraneous light (21 , 23) differ from each other, c) Extending the digital model by a connected first surface (24, 25) with light-guiding properties depending on an angle of incidence of light on the first surface (24, 25), which is arranged in the specified first region such that, due to patent attorneys GEYER, FEHNERS & PARTNER Munich - Jena 27. Angles of incidence of the light rays (L1) of the useful light on the first surface (24, 25), which differ from angles of incidence of the light rays (21, 23) of the first extraneous light on the first surface (24, 25), at least part of the light rays (L1) of the useful light is deflected from the first surface (24, 25) in such a way that it hits the entrance section (10), while at least part of the light rays (21, 23) of the first extraneous light is deflected from the first surface (24, 25) in such a way that it does not hit the entrance section (10). d) Optimization of the light-guiding properties of the first surface (24, 25) in the digital model by determining local variations of the light-guiding properties as a function of the angle of incidence and the point of impact of the light on the first surface in order to increase the amount of useful light striking the inlet section (10) and / or to decrease the amount of first stray light striking the inlet section (10), e) Fabricating the optical module (9) with the first surface (24, 25) which has the locally varying light-guiding properties according to step d).