An optical waveguide arrangement with improved capacity

Abstract

According to an example of the invention, an optical waveguide configuration is provided herein, comprising an input coupling structure and an optical waveguide, the input coupling structure being configured to diffract an incident light signal having spectral characteristics in the visible spectrum into a first variant of the light signal having a first polarization and a second variant of the light signal having a second polarization, wherein the first polarization is at least partially orthogonal to the second polarization, and the input coupling structure being further configured to diffractically couple the first and second variants of the light signal into the optical waveguide, and the optical waveguide being configured to deliver the first variant of the light signal having the first polarization and the second variant of the light signal having the second polarization to an eye to produce a waveguide-based display.

Description

Technical Field

[0001] The embodiments of the present invention relate to an optical waveguide configuration. Prior Technology

[0002] Optical waveguides are capable of transmitting optical frequency light. Optical or visible frequency refers to light with wavelengths between approximately 400 and 700 nanometers. Optical waveguides have been used in displays, where light from an optical field can be delivered to the appropriate location using one or more waveguides to be emitted to the user's eyes or multiple eyes.

[0003] Head-mounted displays (HMDs) and head-up displays (HUDs) can be implemented using optical waveguide technology, for example, in augmented reality or virtual reality applications. In augmented reality, the user sees the real world with supplementary indicators overlaid on it. In virtual reality, the user is deprived of their view of the real world and instead has a view of a software-defined scene.

[0004] Typically, enhancements related to optical waveguide technology are needed. More specifically, increasing the capacity of optical waveguide configurations would be useful. Summary of the Invention

[0005] Based on certain patterns, the targets of independent items are provided. Some implementation methods are defined in the appendices.

[0006] According to a first aspect of the invention, an optical waveguide configuration is provided herein, comprising an input coupling structure and an optical waveguide, the input coupling structure being configured to diffract an incident light signal having spectral characteristics in the visible spectrum into a first version of the light signal having a first polarization and a second version of the light signal having a second polarization, wherein the first polarization is at least partially orthogonal to the second polarization, and the input coupling structure being further configured to diffractically couple the first and second versions of the light signal into the optical waveguide, and the optical waveguide being configured to deliver the first version of the light signal having the first polarization and the second version of the light signal having the second polarization to an eye to produce a waveguide-based display.

[0007] Example implementations of the first-state sample may include at least one feature from the following bulleted list or any combination of the following features: ● When the first and second variants of the optical signal propagate from the input coupling region to the output coupling region, the relative change in intensity of the first variant of the optical signal is the same as or substantially the same as the relative change in intensity of the second variant of the optical signal; ● The optical waveguide configuration further includes an outgoing coupling structure configured to compensate for rotation of the polarization states of the first variant and the second variant of the optical signal, the rotation occurring when the first variant and the second variant of the optical signal are transmitted in the optical waveguide; ● [ ] This spectral characteristic is characterized by clear spectral peaks at specific wavelengths in the visible spectrum; ● The first and second variants of the optical signal have the spectral characteristics of the visible spectrum; ● The first and second variants of the optical signal overlap at least partially in space and in terms of their wave vectors and wavelengths when propagating in the optical waveguide; ● The coupling structure is configured to guide the first variant of the optical signal to a first position in the wave vector ring and to guide the second variant of the optical signal to a second position in the wave vector ring; ● The waveguide is made of glass, plastic, or any other suitable waveguide material having a refractive index of at least 1.4, such as at least 1.7, preferably at least 2.0; ● When the first variant and the second variant of the optical signal are transmitted in the optical waveguide, the relative change in the intensity of the first variant of the optical signal is the same as the relative change in the intensity of the second variant of the optical signal; ● The optical waveguide configuration includes an outgoing coupling structure configured to produce a combined image for an observer from the first and second variants of the optical signal; ● The first and second polarizations are partially orthogonal to each other, preferably completely orthogonal; ● The optical waveguide configuration further includes at least one processor configured to produce an optical signal with a known polarization distribution that spans the image represented by the optical signal.

[0008] According to a second aspect of the present invention, an optical product is provided, comprising the optical waveguide configuration and a light source adapted to guide the optical signal to the ingress coupling structure.

[0009] According to a third aspect of the present invention, a personal display device, such as a head-mounted display or head-up display, is provided, which includes a light waveguide configuration and / or optical products. Simple Explanation of the Diagram

[0010] [Figure 1] illustrates an example system according to at least some embodiments of the present invention;

[0011] [Figure 2] illustrates a first exemplary wave vector diagram in the (kx, ky) plane according to at least some embodiments of the present invention;

[0012] [Figure 3] illustrates a second exemplary wave vector diagram in the (kx, ky) plane according to at least some embodiments of the present invention. Implementation

[0013] Embodiments of the present invention relate to an optical waveguide configuration. The optical waveguide configuration may include an optical waveguide and an in-coupling structure for coupling an image into the waveguide, such as an in-coupling grating configured to diffractically couple an optical signal. The in-coupling structure may also be configured to split the image-related optical signal into a first optical signal and a second optical signal. The first and second optical signals may have a first polarization and a second polarization, respectively. Using different polarizations, such as vertical and horizontal polarization or clockwise and counterclockwise polarization, the first and second optical signals can be distinguished, even if the optical signals have the same or substantially the same spectral characteristics in the visible spectrum, such as wavelength, have the same or substantially the same propagation angle, and occupy the same or substantially the same spatial position in the out-coupling region of the waveguide. Therefore, the waveguide capacity can be doubled because, for example, two red light signals can be transmitted through the same or nearly the same path within the waveguide, thus allowing the transmission of two portions of an image with a waveguide geometry that, in conventional designs, only has the capacity of one of those portions, by using independent polarization states to transmit portions of the image.

[0014] Figure 1 illustrates an example system according to at least some embodiments of the present invention. The system may include a set of light sources 140. Light sources 140 may include, for example, lasers or light-emitting diodes, LEDs, light sources, wherein laser sources have the advantage of being more strictly monochromatic than LEDs. Light sources 140, together with other optical components (e.g., MEMS mirrors 130), form an optical system that can be configured to generate a light field in angular space. An image is encoded in the light field. The light field is schematically illustrated as field 100 in Figure 1. In some embodiments, a physical main display may display an image of the light field 100, while in other embodiments, the system may not include a physical main display and the image may only be encoded in a light field distributed in angular space. Optical signals 104 from the light field 100 may be transmitted directly or by means of a light guide 102 including, for example, mirrors and / or lenses, to a waveguide 110 to produce a waveguide-based display. The light guide 102 is optional in a certain sense and may be absent depending on the details of a particular embodiment. In other words, the light guide 102 is not present in all embodiments.

[0015] The optical signal 104 from the light source 140 can be guided to the ingress coupling structure 103, such as a partially reflecting mirror, a surface relief grating, or other diffraction structure. For example, the ingress coupling structure 103 may include one or more ingress coupling gratings and / or prisms. The ingress coupling structure 103 can be configured to guide the light 104 into the optical waveguide 110. That is, the ingress coupling structure 103 can diffractically couple an image into the optical waveguide 110. As shown in FIG1, in some embodiments, the ingress coupling structure 103 may be, for example, on or near the surface of the optical waveguide 110. However, in some embodiments, the optical waveguide 110 may include the ingress coupling structure 103.

[0016] In some embodiments, there may be no ingress coupling element, and in such cases, for example, the optical signal 104 may be introduced into the optical waveguide 110 by directly irradiating the side surface of the optical waveguide 110.

[0017] In waveguide 110, optical signal 104 can advance by repeated reflections inside the waveguide, interacting with element 112a until it interacts with element 112, causing it to deflect from waveguide 110 into the air and towards eye 120 as optical signal 114 for producing an image. Elements 112a and 112 can be located on either side or both sides of the optical waveguide 110, where one side of the optical waveguide 110 refers to the side facing eye 120 or the "outer world" side. For example, elements 112a and 112a may include partially reflective mirrors, surface relief gratings, or other diffraction structures. For example, element 112a can be configured to propagate light field 100 within waveguide 110, thereby correctly producing an image for the waveguide display. Light from different angular aspects of light field 100 will interact with element 112, such that optical signal 114 will produce the image encoded in light field 100 on the retina of eye 120.

[0018] Element 112 allows the light signal 104 to exit the waveguide 110 at multiple exit locations. Therefore, the user perceives the image encoded in the light field 100 in front of his eyes 120. Since the waveguide 110 can be at least partially transparent, for example, in the case of a head-mounted display based on the waveguide 110, the user can also advantageously see his real-life environment through the waveguide 110. Due to the action of element 112, light is released from the waveguide 110; that is, element 112 can be referred to as an output coupling element or structure.

[0019] The example system illustrated in Figure 1 includes three light sources 140, and at least one processor 150 can be configured to control the light sources 140. This disclosure is an example not limited to this, and there may be fewer or more than three light sources 140. The light sources 140 can be considered monochromatic because they can produce narrow spectral bands with a single peak wavelength, as in lasers, or their spectral bands can be wider, as in LEDs. Light sources with more complex spectral distributions are also possible.

[0020] To produce a color image encoded in a light field 100 in angular space, a light source 140 can be controlled, for example, by a processor 150 in a programmed manner. In the presence of a mirror 130, the light source 140 and the mirror 130 can be synchronized with each other, such that light from the light source 140 illuminates specific angular regions of the angular space 100 in a controlled manner, thereby producing a representation of a color image that reproduces a still or moving input image received from an external source (e.g., a virtual reality or augmented reality computer). For example, the still or moving image received from the external source may include a digital image or a digital video feed. Therefore, the image encoded in the light field 100 can be configured by providing an appropriately selected input image.

[0021] To produce a specific color in a given aspect of the angular space of the light field 100, for example, this given aspect in the angular space can be illuminated by a set of at least three light sources 140. When light from the given aspect of the angular space of the light field 100 travels in the waveguide 110 to element 112 (possibly through element 112a), the specific color is then reproduced by the light signal 114, wherein the specific color exists at an angle corresponding to the given aspect in the angular space 100.

[0022] Embodiments of the present invention aim to increase the capacity of the optical waveguide 110. This enhanced optical waveguide can be used, for example, in head-mounted displays (HMDs) and head-up displays (HUDs), which can be implemented using optical waveguide technology, for example, for augmented reality or virtual reality applications. The human eye (retina) is almost insensitive to polarization, meaning that under normal viewing conditions, it is generally unable to distinguish different polarization states (Haidinger's brush indicates that humans can weakly detect polarization states under ideal conditions, but this effect is irrelevant to the display purpose). For example, this insensitivity can be used in smartphone displays, which may exhibit a "rainbow" effect when viewed through a polarizer.

[0023] According to embodiments of the present invention, two optical signals can be transmitted independently of each other via a waveguide, provided that they correspond to two orthogonal polarization states or at least partially orthogonal polarization states when they enter the waveguide 110. The device causing the different polarization states may or may not be part of the waveguide's in-line coupling configuration. In some example embodiments, the in-line coupling grating 103 is designed to produce two optical signals having orthogonal polarization or at least partially mutually orthogonal polarization. In some example embodiments, the optical signals incident on the in-line coupling grating 103 may already include first and second orthogonally polarized signals.

[0024] For example, the first optical signal can be clockwise polarized and the second optical signal can be counterclockwise polarized, but more complex configurations are also possible. The waveguide 110 can be designed (optimized) so that its effect on the optical field intensity (the variation in the total optical field intensity between the input coupling region and any particular output coupling region) is (almost) polarization insensitive. This can be ensured by requiring all optical field-waveguide interactions to be polarization insensitive, but more practically, it is only required that the entire end-to-end channel be polarization insensitive. In practice, this is an extension of the typical requirement that the intensity of all wavelengths of interest is mapped in the same way (color uniformity) to each output coupling region / structure and each propagation angle of interest, and also includes uniformity across polarization states.

[0025] It can be proven, for example, using polarization identity in so-called Hilbert space, that polarization-independent mapping of intensity is sufficient to maintain the orthogonality of polarization states from the input coupling grating to any particular output coupling grating. However, the polarization states rotate with propagation inside the waveguide, depending on the wavelength, propagation angle, and output coupling position, and this rotation must be generated by the output coupling grating in order to correctly combine parts of the image. Therefore, the rotation of the polarization states must be modeled and incorporated into the waveguide design process (optimization).

[0026] Figure 2 illustrates a first exemplary wave vector diagram in the (kx, ky) plane according to at least some embodiments of the present invention. For example, the first exemplary wave vector diagram can represent the wave vector diagram of the optical waveguide 110 of Figure 1. Figure 2 shows how the normalized wave vector components of the pixels representing the image rectangle 200 (note that although the image shape can be arbitrary, the rectangle is used for illustrative purposes; furthermore, an image that is rectangular to the observer actually has a pincushion shape in the wave vector diagram), i.e., how the optical signal 104 of Figure 1 (marked by the black dots in Figure 2) moves relative to their original positions (input / output states) inside the inner circle when the light field interacts with the grating in the waveguide. The optical signal 104 may have spectral characteristics in the visible spectrum, such as a clear spectral peak at a specific wavelength. The optical signal 104 may, for example, have wavelengths of primary colors (blue, green, red).

[0027] As shown in Figure 2, the normalized wave vector components of the pixel and the optical signal 104 corresponding to the image frame 200 (arrow 201 indicates the 2D projection of the normalized wave vector of the pixel; for simplicity, the normalized wave vector is only drawn within rectangle 200) can be shifted from the inner circle of the wave vector diagram (which represents the propagation angle of in-coupling to and out-coupling from the waveguide) to a first position 210 in the annulus of the diagram (which represents the waveguide pattern propagating inside the waveguide by total internal reflection) by the grating-induced vector 205 of the in-coupling grating (e.g., in-coupling structure 103, e.g., 110 in the waveguide of Figure 1). Then, the normalized wave vector components of the pixel can be shifted to at least one other position 220 in the diagram by the grating-induced vector 215 of the optical waveguide 110.

[0028] In some embodiments, the refractive index can be n1 = 1 (air surrounding the waveguide) and n2 = 2 (waveguide material). The annulus (between the circles of radius n1 and radius n2) can be referred to as the outer edge of the figure or simply the ring, and the region within the inner circumference n1 can be referred to as the inner circle of the figure. In the inner circle of the figure, the optical signal 104 can propagate either outside the waveguide (in the air) or inside the waveguide, while the ring corresponds only to propagation inside the waveguide. In some embodiments, the waveguide can be made of glass, plastic, or any other suitable waveguide material. In some embodiments, the refractive index of the waveguide material can be at least 1.4, or at least 1.7, or at least 2.0. The area of ​​the annular region relates to the ability of the optical waveguide 110 to transmit light of a single wavelength and a single polarization state.

[0029] Finally, the normalized wave vector components corresponding to the pixels in the image frame 200 and the light signal 104 can be shifted from position 220 in the figure back to the inner circle by the grating-induced vector 225 of the out-coupled grating or general structure (e.g., the out-coupled element 112 in Figure 1) (which allows the light field to escape from the waveguide).

[0030] The challenge addressed by this invention is that when an image is brought to the optical waveguide 110, the image size and resolution are limited by the waveguide capacity (i.e., it is not possible to arbitrarily increase the image size or resolution). Resolution is limited by the number of identifiable angular directions inside the waveguide, which is related to the waveguide thickness; however, we are interested here in the limitation of image size (the angular range of the image), which is related to the difference in refractive index between the waveguide and the surrounding material.

[0031] Specifically, the capacity of a waveguide is the area of ​​the annular region in the diagram. This capacity can be divided into two parts: the spatial extent (in the diagram) (corresponding to the propagation direction (pixels)) and its resolution (corresponding to the number of distinguishable pixels). Here, we will only use this term when referring to the former. Since the position within the annular region also represents the propagation direction inside the waveguide, not all capacity can be (directly) utilized when an image needs to be relayed from one part of the waveguide (the in-coupling region) to another part (the out-coupling region / structure). That is, although backtracking is an option, the main propagation direction must still be from the in-coupling region towards the out-coupling region / structure.

[0032] Furthermore, when using gratings to guide light in a waveguide, the image region can be shifted within the image, but cannot be scaled or rotated, and the shift distance depends on the difficult-to-control wavelength. Therefore, it is often necessary to segment the image region, for example, when a large field-of-view image needs to be transmitted via a waveguide. Since different parts of the image cannot be transmitted through the same area in the ring, as this would cause crosstalk in the image, it is challenging to propagate different parts of the image from the input coupling region to the output coupling region, let alone do so in a way that results in uniform image intensity.

[0033] Embodiments of the present invention attempt to alleviate this challenge by doubling the capacity of the waveguide using orthogonal or at least partially orthogonal polarization states. Specifically, each position in the loop and the direction of propagation can contain two parts of the image. For example, the image can be divided into two parts, with a first polarization used to transmit the first half of the image (e.g., left-hand pixels) and a second polarization used to transmit the second half of the image (e.g., right-hand pixels). The image can also be divided into first and second polarizations in other ways, for example, by selecting pixels in odd-numbered columns to the first half of the image and pixels in even-numbered columns to the second half.

[0034] We note that although some images may overlap at different locations in the waveguide in the wave vector diagram, the design principle here is that as long as the overlapping parts of the images have orthogonal polarization states, a portion of the image can be recovered separately at the out-coupled point when the relative intensity change between the in-coupled and out-coupled points is the same for all polarization states (any two orthogonal states).

[0035] Specifically, during waveguide propagation, it is not necessary to explicitly require that the overlapping portions of the image have orthogonal polarization, even if they occupy overlapping areas in the wave vector diagram. Different polarization states of the portions of the image can be generated, for example, at the light source or within the coupling (pre-coupling, in-coupling region, or using multiple gratings).

[0036] Figure 3 illustrates a second exemplary wave vector diagram in the (kx, ky) plane according to at least some embodiments of the present invention. For example, the second exemplary wave vector diagram can show the wave vector diagram of the optical waveguide 110 of Figure 1. Similar to Figure 2, Figure 3 shows how the normalized wave vector components corresponding to the positions of pixels and image points of image frame 200 (i.e., the optical signal 104 of Figure 1 (marked by black dots)) move relative to the ring under grating interaction.

[0037] More specifically, Figure 3 illustrates how the grating-induced vectors 205a and 205b of the ingress coupling grating (as shown in ingress coupling structure 103 in Figure 1) shift (diffuse) the normalized wave vector components of the pixels of the image frame 200 from the inner circle of the figure (fields propagating outside and inside the waveguide 110) to first positions 210a and second positions 210b, respectively, within the annular region (waveguide pattern in waveguide 110). The ingress coupling grating can be configured to diffract the incident light signal 104 into a first variant 104a of the light signal 104 with a first polarization and a second variant 104b of the light signal 104 with a second polarization.

[0038] The coupling grating can be further configured to diffractically couple the first variant 104a and the second variant 104b of the optical signal 104 into the optical waveguide 110. The first variant 104a and the second variant 104b of the optical signal 104 can be on top of each other in the wave vector diagram, i.e., the positions of the first variant 104a and the second variant 104b of the optical signal 104 can at least partially overlap. Due to the use of orthogonal polarization states, or at least partially orthogonal polarization states, the first variant 104a and the second variant 104b of the optical signal 104 can be separated when the coupled signal exits from the waveguide.

[0039] The first polarization can be at least partially orthogonal to the second polarization, so that after the optical waveguide 110 has transmitted the first variant 104a of the optical signal 104 with the first polarization and the second variant 104b of the optical signal 104 with the second polarization to the out-coupled grating, the light rays 104a and 104b can be distinguished, which can then be combined to produce an image directed toward the eye to produce a waveguide-based display.

[0040] In one embodiment, the output coupling grating or structure is configured to produce a combined image on the retina of an observer's eye (or any other associated recording device) based on the first and second variants of the optical signal. Therefore, when image frames 220a and 220b in FIG. 3 are mapped to the inner circle of the wave vector map, they are separate. The intensity of the first variant 104a can be the same as or substantially the same as the intensity of the second variant 104b inside the inner circle (at the output), provided that their relative changes are sufficiently equal.

[0041] Typically, when an optical signal propagates inside a waveguide, it jumps within a wave vector loop (between the inner and outer circles). When it is out-coupled, it maps to the inside of the inner circle. Using orthogonal polarization or at least partially orthogonal polarization, a first variant 104a and a second variant 104b of the optical signal 104 can be separated at the out-coupling point if the intensities of the first variant 104a and the second variant 104b of the optical signal 104 change equally (or approximately equally) during waveguide propagation from the input coupling region to any out-coupling region.

[0042] When the incident light signal 104 is diffracted into a first variant 104a of the light signal 104 with a first polarization and a second variant 104b of the light signal 104 with a second polarization, the normalized wave vector component representing the pixel of the image 200 can be shifted from a first position 210a to at least one other position 220a and from a second position 210b to at least one other position 220b by the vector of the grating-induced vector 215 in FIG. 3. That is, the first variant 104a of the light signal 104 can be shifted from the first position 210a to at least one other position 220a. The second variant 104b of the light signal 104 can similarly be shifted from the second position 210b to at least one other position 220b. The other positions 220a and 220b can overlap at some point, that is, the first variant 104a and the second variant 104b of the light signal 104 can be transmitted at least partially at the same position. However, due to the use of different polarizations, the first variant 104a and the second variant 104b of the optical signal 104 can ultimately be distinguished.

[0043] Optical signal 104 can have spectral characteristics in the visible spectrum, and first variant 104a and second variant 104b of optical signal 104 can have the same visible spectral characteristics as optical signal 104. However, since the first variant 104a and the second variant 104b of optical signal 104 have different polarizations, they can be distinguished at the output coupling grating / structure. Therefore, if the rotation of the polarization state that occurs when the first variant 104a and the second variant 104b of optical signal 104 are transmitted in the optical waveguide 110 can be generated in the output coupling grating, the channel capacity of the optical waveguide 110 can be doubled.

[0044] In some implementations, the polarizations of the first variant 104a and the second variant 104b of the optical signal 104 can be mixed, but if the polarization states of the first variant 104a and the second variant 104b of the optical signal 104 are orthogonal, then the first variant 104a and the second variant 104b of the optical signal 104 can be distinguished at the output coupling grating / structure in any case.

[0045] The first variant 104a and the second variant 104b of optical signal 104 can travel along different routes before leaving, for example, if they pass through several gratings on their way from the input coupling region to the output coupling region. However, if the relative change in intensity of the first variant optical signal is equal to the relative change in intensity of the second variant optical signal when they are propagating in the optical waveguide 110, then the first and second variant optical signals can be separated at the output coupling.

[0046] In some implementations, the polarization of the first and second variants of the optical signal can be rotated while being transmitted within the optical waveguide 110. In this case, this rotation can be modeled to facilitate the design of coupling gratings that can be separated between the first and second variants of the optical signal so that they can be correctly combined for display.

[0047] For example, the polarization rotation between the ingress coupling region and a certain exit location can be modeled to see how the polarizations of the first and second optical signals rotate as they propagate through the optical waveguide. By determining how much the polarization has rotated, and while maintaining their mutual orthogonality or at least partial mutual orthogonality, a suitable outgress coupling grating behavior can be selected that can separate the first and second optical signals. That is, it may be necessary to model how two images with different polarization states propagate from the ingress coupling grating to the outgress coupling grating in order to separate parts of the images so that they can be combined back into a single image. Therefore, a polarization mapping may exist between the ingress and outgress coupling regions, and a suitable outgress coupling grating can then be selected based on this mapping.

[0048] In some embodiments, the optical waveguide configuration may include at least one processor, such as processor 150 of FIG. 1. The at least one processor may be configured to produce a known polarization distribution of the optical signal 104. That is, the polarization distribution produced by the at least one processor may such that, for example, a set of in-line coupling gratings may diffract the optical signal 104 into a first variant 104a and a second variant 104b, and these variants may be orthogonally polarized.

[0049] Alternatively or additionally, at least one processor can be configured to directly generate a given polarization state for the first variant 104a and the second variant 104b of the optical signal. Since the polarization state is two-dimensional, it is desirable to produce partial images with orthogonal polarization states. The polarization states of the two images are selected such that when the images overlap immediately after coupling in the wave vector diagram, they have orthogonal or at least partially orthogonal polarizations. This means that the polarization state of each image can be fixed across the entire image, or it can have any distribution as long as the other image has orthogonal polarization states in the overlapping region. The polarization state distribution can be the same or different for different wavelengths. In some cases, the orthogonality condition may only be partially satisfied, for example, due to design and manufacturing limitations, resulting in a corresponding decrease in system performance. As an example, at least one processor can be used directly or by enabling the use of a (pre)coupled grating for this purpose to select specific orthogonal polarization states for the right and left sides of the image.

[0050] It should be understood that the embodiments of the present invention disclosed herein are not limited to the specific structures, process steps, or materials disclosed herein, but extend to equivalents that will be recognized by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not restrictive.

[0051] Throughout this specification, the terms "an embodiment" or "an embodiment" refer to a specific feature, structure, or characteristic described in relation to that embodiment, which is included in at least one embodiment of the invention. Therefore, phrases such as "in an embodiment" or "in a embodiment" appearing throughout this specification do not necessarily refer to the same embodiment. Where numerical values ​​are mentioned using terms such as approximately or substantially, precise numerical values ​​are also disclosed.

[0052] As used herein, multiple items, structural elements, constituent elements, and / or materials may be presented in a common list for convenience. However, these lists should be understood as each member of the list being individually identified as a separate, unique member. Therefore, no single member of such a list should be construed as a de facto equivalent to any other member of the same list based solely on its performance within a common group, without the contrary indication. Furthermore, various embodiments and examples of the invention, along with alternatives to its various components, are mentioned herein. It should be understood that these embodiments, examples, and alternatives should not be construed as de facto equivalents to each other, but should be regarded as separate and autonomous representations of the invention.

[0053] Furthermore, in one or more embodiments, the described features, structures, or characteristics may be combined in any suitable manner. Numerous specific details, such as examples of length, width, shape, etc., have been provided in the foregoing description to provide a thorough understanding of embodiments of the invention. However, those skilled in the art will recognize that the invention can be practiced without one or more specific details, or using other methods, components, materials, etc. In other instances, well-known structures, materials, or operations have not been shown or described in detail to avoid obscuring aspects of the invention.

[0054] While the foregoing examples illustrate the principles of the invention in one or more specific applications, it will be apparent to those skilled in the art that numerous modifications can be made to the form, use, and details of the embodiments without exercising progressiveness and without departing from the principles and concepts of the invention. Therefore, the invention is not intended to be limited except as defined by the following claims.

[0055] The verbs “include” and “contain” are used in this document as open restrictions, neither excluding nor requiring the presence of features not listed. Unless otherwise expressly stated, the features described in the appendices may be freely combined with each other. Furthermore, it should be understood that the use of “a” or “an” in this document, i.e., the singular form, does not exclude the plural. Industrial applicability

[0056] At least some embodiments of the present invention have found industrial applications in HMDs and HUDs. List of abbreviations HMD: Head-mounted display HUD: Head-Up Display LED: Light Emitting Diode

[0057] 100: Light Field 102: Optical guide tube 103: In-line coupling structure 104:Light signal 104a: First variant 104b: Second variant 110: Waveguide 112: Components 112a: Component 114:Light signal 120: Eyes 130: Mirror 140: Light source 150: Processor 200: Image Frame 201: 2D projection of the normalized wave vector of a pixel 205: Grating Induced Vector 205a: Grating Induced Vector 205b: Grating Induced Vector 210: First position 210a: First position 210b: Second position 215: Grating Induced Vector 220: Image Frame 220a: Image frame 220b: Image frame 225: Grating Induced Vector n1: Refractive index n2: Refractive index

Claims

1. An optical waveguide configuration, comprising: - An input coupling structure configured to diffract an incident light signal having spectral characteristics in the visible spectrum into a first variant of the light signal having a first polarization and a second variant of the light signal having a second polarization, wherein the first polarization is at least partially orthogonal to the second polarization, and the input coupling structure is further configured to diffractically couple the first and second variants of the light signal into an optical waveguide; and - the optical waveguide configured to deliver the first variant of the light signal having the first polarization and the second variant of the light signal having the second polarization to an eye to produce a waveguide-based display, - wherein, as the first and second variants of the light signal propagate from the input coupling structure to the output coupling structure, the relative change in intensity of the first variant of the light signal is the same as or substantially the same as the relative change in intensity of the second variant of the light signal.

2. As in request item 1, the optical waveguide configuration, wherein, This spectral characteristic is characterized by clear spectral peaks at specific wavelengths in the visible spectrum.

3. As in request item 1, the optical waveguide configuration, wherein, The first and second variants of the optical signal have spectral characteristics in the visible spectrum.

4. As in request item 1, the optical waveguide configuration, wherein, The first and second variants of the optical signal overlap at least partially in space and in terms of their wave vectors and wavelengths when they are transmitted in the optical waveguide.

5. The optical waveguide configuration as requested in item 1, wherein, The coupling structure is configured to guide the first variant of the optical signal to a first position in the wave vector ring and to guide the second variant of the optical signal to a second position in the wave vector ring.

6. As in request item 1, the optical waveguide configuration, wherein, The waveguide is made of glass, plastic, or any other suitable waveguide material having a refractive index of at least 1.

4.

7. The optical waveguide configuration as requested in item 1, wherein, The waveguide is made of glass, plastic, or any other suitable waveguide material having a refractive index of at least 1.

7.

8. The optical waveguide configuration as requested in item 1, wherein, The waveguide is made of glass, plastic, or any other suitable waveguide material having a refractive index of at least 2.

0.

9. The optical waveguide configuration as requested in item 1, wherein, When the first variant and the second variant of the optical signal are transmitted in the optical waveguide, the relative change in intensity of the first variant of the optical signal is the same as the relative change in intensity of the second variant of the optical signal.

10. The optical waveguide configuration as requested in item 1, wherein, The optical waveguide configuration includes the outgoing coupling structure, which is configured to produce a combined image for an observer from the first and second variants of the optical signal.

11. The optical waveguide configuration as requested in item 1, wherein, The first and second polarizations are partially orthogonal to each other.

12. The optical waveguide configuration as requested in item 1, wherein, The first and second polarizations are completely orthogonal.

13. The optical waveguide configuration of claim 1 further includes at least one processor configured to produce an optical signal having a known polarization distribution that spans the image represented by the optical signal.

14. An optical product comprising an optical waveguide configuration as described in any of the preceding claims and a light source adapted to guide the optical signal to the in-coupled structure.

15. A personal display device, such as a head-mounted display or head-up display, comprising the light waveguide configuration as described in any of claims 1 to 13 and / or the optical product as described in claim 14.

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