Pupil-expanding waveguides and display devices

Abstract

This utility model discloses a pupil-expanding optical waveguide and display device. The pupil-expanding optical waveguide includes a waveguide body, an insertion region, an intermediate region, and an exit region. The intermediate region is used to expand the pupil of light rays inserted into the waveguide body at least in a first direction. The pupil-expanding optical waveguide is configured such that: a portion of the light rays inserted from the insertion region are diffracted in the intermediate region and then propagate to the exit region; another portion of the light rays inserted from the insertion region are transmitted through the intermediate region and then propagate to the exit region. The exit region is used to expand the pupil of at least a portion of the light rays diffracted through the intermediate region and at least a portion of the light rays transmitted through the intermediate region at least in a second direction and exit the waveguide body. The first direction and the second direction are arranged at an angle. The insertion region has a first center line, and the exit region has a second center line, which are collinear. This utility model can fully utilize transmitted light, thus helping to improve light utilization efficiency.

Description

Technical Field

[0001] This utility model relates to the field of augmented reality technology, and in particular to a pupil-expanding optical waveguide and display device. Background Technology

[0002] Existing diffractive waveguide architectures are mainly one-dimensional folding structures and two-dimensional grating structures. Both of these architectures are far less efficient than near-eye display solutions such as freeform surface optics and geometric waveguides. Specifically, the one-dimensional folding structure mainly includes a coupling region, a folding region, and a coupling-out region. Light energy is lost in all three regions, with a significant portion of the light not being coupled out. In the two-dimensional grating structure, due to the low non-zero order diffraction efficiency of the grating, although more light energy reaches the coupling-out region, a large proportion of the light energy is directly reflected internally through the coupling-out grating region and lost at the waveguide edge. Therefore, using these two architectures for pupil expansion is inefficient and affects the final display brightness. Utility Model Content

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a pupil-expanding optical waveguide that can improve light utilization.

[0004] This invention also proposes a display device that utilizes the aforementioned pupil-expanding waveguide.

[0005] According to the first embodiment of the present invention, the pupil-expanding optical waveguide includes a waveguide body and a coupling-in region, an intermediate region, and a coupling-out region disposed on the waveguide body. The coupling-in region is used to couple light into the waveguide body; the intermediate region is used to expand the pupil of the light coupled into the waveguide body at least in a first direction. The pupil-expanding waveguide is configured such that: a portion of the light rays coupled in from the coupling region are diffracted in the intermediate region and then propagate to the coupling-out region; another portion of the light rays coupled in from the coupling region are transmitted through the intermediate region and then propagate to the coupling-out region; the coupling-out region is used to expand the pupil of at least a portion of the light rays diffracted through the intermediate region and at least a portion of the light rays transmitted through the intermediate region at least in a second direction and couple them out of the waveguide body; the first direction and the second direction are set at an angle. The coupling-in region has a first centerline, the coupling-out region has a second centerline, the first centerline and the second centerline are collinear; and / or, the intermediate region is located between the coupling-in region and the coupling-out region.

[0006] The pupil-expanding optical waveguide according to the embodiments of this utility model has at least the following beneficial effects: This invention, by aligning the axes of symmetry of the input and output regions, allows the light transmitted through the intermediate region to be coupled out to a greater extent within the visual range of the human eye, thereby making full use of the transmitted light and improving light utilization. At the same time, by setting the intermediate and output regions to cooperate in two-dimensional pupil dilation, the final pupil dilation effect can be guaranteed.

[0007] In other embodiments of this utility model, the intermediate region has a third center line, and the first center line is collinear with the third center line.

[0008] In other embodiments of this utility model, the intermediate region includes a first intermediate grating region and a second intermediate grating region symmetrically arranged along the third center line. The pupil-expanding waveguide is configured such that a portion of the light rays coupled from the coupling region are diffracted in the first intermediate grating region and the second intermediate grating region to expand the pupil, and in the direction perpendicular to the third center line, the pupil-expanding directions of the light rays in the first intermediate grating region and the second intermediate grating region are opposite.

[0009] In other embodiments of this utility model, the coupling-out region includes a single coupling-out grating region, and the pupil-expanding waveguide is configured such that: a portion of the light rays coupled in from the coupling-in region are diffracted in the intermediate region and then propagate to the single coupling-out grating region; another portion of the light rays coupled in from the coupling-in region are transmitted through the intermediate region and then propagate to the single coupling-out grating region; the single coupling-out grating region is used to couple at least a portion of the light rays incident thereon out of the waveguide body.

[0010] In other embodiments of this utility model, the coupling region includes a coupling grating region, which is used to couple light rays into the waveguide body; The pupil-expanding waveguide satisfies the following settings: K1=K3, where K1 is the K vector of the coupled-in grating region and K3 is the K vector of the single coupled-out grating region.

[0011] In other embodiments of this utility model, a portion of the light rays coupled in from the coupling region undergoes an even number of diffractions in the intermediate region and then propagates to the single coupling grating region to form a first ray. Another portion of the light rays coupled in from the coupling region passes through the intermediate region and then propagates to the single coupling grating region to form a second ray. At least a portion of the first ray and the second ray are coupled out in the single coupling grating region.

[0012] In other embodiments of this utility model, the coupling region includes a first coupling grating region and a second coupling grating region, and the pupil-expanding waveguide is configured such that light rays that transmit through the intermediate region and propagate to the first coupling grating region can propagate from the first coupling grating region to the second coupling grating region and be coupled out from the second coupling grating region; and light rays that transmit through the intermediate region and propagate to the second coupling grating region can propagate from the second coupling grating region to the first coupling grating region and be coupled out from the first coupling grating region.

[0013] In other embodiments of this utility model, the pupil-expanding waveguide is configured such that, among the light rays diffracted in the intermediate region, light rays that have undergone an even number of diffractions and propagate to the first coupling grating region can propagate from the first coupling grating region to the second coupling grating region and be coupled out from the second coupling grating region; and light rays that have undergone an even number of diffractions and propagate to the second coupling grating region can propagate from the second coupling grating region to the first coupling grating region and be coupled out from the first coupling grating region. And / or, the pupil-expanding waveguide is configured such that, among the light rays diffracted in the intermediate region, light rays that have undergone an odd number of diffractions and propagated to the first coupling grating region can be coupled out from the first coupling grating region, and light rays that have undergone an odd number of diffractions and propagated to the second coupling grating region can be coupled out from the second coupling grating region.

[0014] In other embodiments of this utility model, the coupling region includes a coupling grating region, which is used to couple light rays into the waveguide body; The pupil-expanding waveguide satisfies the following configuration: K1+K 31 +K 32 =0, K1 is the K vector of the coupled grating region, K 31 K is the K vector of the first coupled grating region, K 32 The K vector represents the second coupled grating region; the first coupled grating region and the second coupled grating region are symmetrical along the second centerline.

[0015] In other embodiments of this utility model, the pupil-expanding waveguide satisfies the following configuration: K 31 =K 22 K 32 =K 21 K 31 K is the K vector of the first coupled grating region, K 32 K is the K vector of the second coupled grating region, K 21 K is the K vector of the first intermediate grating region, K 22is the K vector of the second intermediate grating region.

[0016] The display device according to the second embodiment of the present invention includes: A light source assembly, wherein the exit pupil size of the light source assembly is less than or equal to 1.5 mm; The aforementioned pupil-expanding optical waveguide; Display waveguide; Specifically, the light emitted from the light source component is coupled into the coupling region of the pupil-expanding waveguide and coupled out from the coupling region. The light coupled out from the coupling region is coupled into the display waveguide and coupled out from the display waveguide into the user's eye region.

[0017] In other embodiments of this utility model, the light source assembly includes a laser light source and a microelectromechanical system (MEMS) reflector. The laser light source is used to emit laser light, and the MEMS reflector is used to reflect the laser light to form the light beam.

[0018] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a schematic diagram of the pupil-expanding optical waveguide in an embodiment of the present invention; Figure 2 A schematic diagram of the K-vector circle for light rays propagating in an optical waveguide; Figure 3 This is a schematic diagram of the pupil-expanding optical waveguide in another embodiment of the present invention; Figure 4 A schematic diagram of the K-vector circle for light rays propagating in an optical waveguide; Figure 5 This is a schematic diagram of the display device in an embodiment of the present utility model.

[0020] Figure label: The waveguide includes a pupil-expanding waveguide 100, a coupling region 110, a coupling grating region 111, an intermediate region 120, a first intermediate grating region 121, a second intermediate grating region 122, a coupling out region 130, a first coupling out grating region 131, a second coupling out grating region 132, a single coupling out grating region 133, and a waveguide body 140. Display waveguide 200, secondary coupling-in region 210, and secondary coupling-out region 220; Even-order diffraction ray L1, odd-order diffraction ray L2. Detailed Implementation

[0021] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0022] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0023] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0024] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0025] In the description of this utility model, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0026] Reference Figure 1The diagram shows a schematic of the pupil-expanding waveguide 100 in the first embodiment of the present invention. The straight lines with arrows in the diagram indicate the direction of light propagation. The pupil-expanding waveguide 100 includes a waveguide body 140, an insertion region 110, an intermediate region 120, and an output region 130. The insertion region 110, intermediate region 120, and output region 130 are all disposed on the waveguide body 140. For example, the insertion region 110, intermediate region 120, and output region 130 are all disposed on the same side of the waveguide body 140. The insertion region 110, intermediate region 120, and output region 130 can be grating structures, which will be specifically described in subsequent embodiments.

[0027] The coupling region 110 is used for light to couple into the waveguide body 140. After coupling into the waveguide body 140 from the coupling region 110, the light propagates towards the intermediate region 120. The intermediate region 120 is disposed between the coupling region 110 and the coupling out region 130, and is used to expand the pupil of the light entering the waveguide body 140 at least in a first direction. The coupling out region 130 is used to expand the pupil of at least a portion of the light diffracted by the intermediate region 120 and at least a portion of the light transmitted through the intermediate region 120 at least in a second direction and couple it out of the waveguide body 140, wherein the first direction and the second direction are arranged at an angle, more specifically, the first direction and the second direction are perpendicular. In this way, the pupil-expanding optical waveguide can realize two-dimensional pupil expansion, and when used in conjunction with a display waveguide, it can effectively alleviate the problem of discontinuity in pupil expansion in the display waveguide.

[0028] Reference Figure 1 The coupling region 110 has a first centerline. For ease of understanding, the first centerline is defined as follows: the first centerline is a first arrangement direction parallel to the coupling region 110 to the coupling region 130 (e.g., Figure 1 The centerline (in the left-right direction) of the coupling region 110, if the coupling region 110 has a symmetrical structure, it can be symmetrically arranged with the first centerline as the axis of symmetry; if the coupling region 110 has an asymmetrical structure, the first centerline passes through the coupling region 110 in the second arrangement direction (perpendicular to the first arrangement direction, for example...). Figure 1 The center of the vertical direction.

[0029] The coupling region 130 has a second center line, and the first center line and the second center line are collinear. During the diffraction process, the brightness of light gradually decreases, so the brightness of the zeroth-order diffracted light is the highest. In this embodiment, by setting the first center line and the second center line to be collinear, the zeroth-order diffracted light transmitted through the intermediate region 120 can be coupled out from a relatively central position in the coupling region 130, which is convenient for human eyes to receive and thus improves the utilization rate of light.

[0030] In this embodiment, the pupil-expanding waveguide 100 is configured such that a portion of the light coupled in from the coupling region 110 is diffracted in the intermediate region 120 and then propagates to the coupling out region 130, and another portion of the light coupled in from the coupling region 110 is transmitted through the intermediate region 120 and then propagates to the coupling out region 130. That is, in this embodiment, the coupling out region 130 can not only couple out non-zero order diffracted light, but also couple out zero order diffracted light, thereby making full use of the light transmitted through the intermediate region 120 and helping to improve the light utilization rate.

[0031] Based on the first embodiment, in some embodiments of this utility model, the intermediate region 120 has a third center line, as shown in the reference. Figure 1 The first center line and the third center line are collinear. Thus, when light propagates from the coupling region 110 to the intermediate region 120, it can diffract and expand from the center along the second arrangement direction (i.e., the aforementioned first direction), achieving a more uniform pupil expansion effect and reducing the non-uniformity of light in the coupling region. For example, when the intermediate region 120 includes a subsequent first intermediate grating region 121 and a second intermediate grating region 122, the first intermediate grating region 121 and the second intermediate grating region 122 are separated by the third center line. In one specific embodiment, the intermediate region is located between the coupling region and the coupling region.

[0032] When the first center line and the third center line are collinear, in some embodiments of this utility model, refer to Figure 1 The intermediate region 120 includes a first intermediate grating region 121 and a second intermediate grating region 122 symmetrically arranged along the third center line. The first intermediate grating region 121 and the second intermediate grating region 122 are arranged side by side. For example, the two are arranged side by side along the aforementioned second arrangement direction.

[0033] In this embodiment, the pupil-expanding waveguide 100 is configured such that a portion of the light coupled from the coupling region 110 diffracts within the first intermediate grating region 121 and the second intermediate grating region 122 to expand the pupil. Furthermore, in the direction perpendicular to the third center line (i.e., the aforementioned second arrangement direction, or the aforementioned first direction), the light's expansion directions within the first intermediate grating region 121 and the second intermediate grating region 122 are opposite, thereby achieving pupil expansion in that direction. This allows the light to expand and fill the entire coupling region 130 after passing through the intermediate region 120, resulting in a more uniform brightness display. For example, the light expands upwards when diffracting in the first intermediate grating region 121 and upwards when diffracting in the second intermediate grating region 122.

[0034] Based on the first embodiment, in some embodiments of this utility model, reference is made to Figure 1The coupling region 110 includes a coupling grating region 111, which is used to couple light rays into the waveguide body 140. The coupling grating region 111 includes a grating structure, such as a holographic grating structure, an embossed grating structure, etc.; the grating structure can be a vertical grating or a tilted grating. For example, the coupling region 110 includes a single coupling grating region 111.

[0035] Based on the first embodiment, in some embodiments of this utility model, reference is made to Figure 1 The coupling region 130 includes a single coupling grating region 133, which includes a grating structure, such as a holographic grating structure or an embossed grating structure. The grating structure can be a vertical grating or a tilted grating. Within this single coupling grating region 133, the grating period and orientation of the grating structure remain consistent.

[0036] In this embodiment, the aforementioned "part of the light coupled from the coupling region 110 is diffracted in the intermediate region 120 and then partially propagates to the coupling region 130, and another part of the light coupled from the coupling region 110 is transmitted through the intermediate region 120 and then propagates to the coupling region 130" specifically means that: part of the light coupled from the coupling region 110 is diffracted in the intermediate region 120 and then propagates to a single coupling grating region 133, and another part of the light coupled from the coupling region 110 is transmitted through the intermediate region 120 and then propagates to a single coupling grating region 133. When the diffracted or transmitted light propagates to the single coupling grating region 133, the single coupling grating region 133 is used to allow at least a portion of the light incident thereon to be coupled out of the waveguide body 140. In this embodiment, by setting a single coupling grating region 133 for light coupling out, the structure of the coupling region 130 is simplified.

[0037] Reference Figure 2 The diagram illustrates a K-vector circle representing the propagation of light rays in an optical waveguide. Specifically, the K-vector circle represents the ability of the K-vector to alter the distribution of the light wave vector. Light rays with wave vectors located within the smaller circle will be transmitted through the surface of the optical waveguide, while light rays with wave vectors located between the smaller and larger circles will undergo total internal reflection within the optical waveguide. Furthermore, the propagation direction of the light ray in the optical waveguide is related to the distribution position of the light wave vector within the K-vector circle, and the propagation direction is the direction from the center of the K-vector circle to the distribution position of the light wave vector.

[0038] Based on the foregoing, Figure 2 In the diagram, K1 is the K vector of the coupling grating region 111. It is used to move the light wave vector from the center position to the position indicated by the vector arrow, that is, to move the rectangular frame of the center region to the rectangular frame in the middle right. This represents the direction of light propagation from the coupling grating region 111 to the middle region 120. Figure 1The direction to the right is mid-level. K 21 With K 22 Let K be the K-vector of the grating structure in the middle region. When light propagates to the grating structure in the middle region and undergoes diffraction, its K-vector is superimposed. For even-order diffracted light, the rectangle located in the middle right is moved to the upper right or lower right, and eventually returns to the middle right. At this time, the vector arrow still points from the center region to the rectangle in the middle right, representing the propagation direction of even-order diffracted light from the middle region 120 to the coupling region 130. Figure 1 For even-order diffracted rays, the direction of propagation towards the coupling region 130 is the same as the direction of propagation from the coupling region 110 to the intermediate region 120. At this point, most even-order diffracted rays can reach the coupling region. For odd-order diffracted rays, the rectangle located in the middle of the right side is moved to the upper right or lower right. The vector arrow (not shown in the figure) points from the center region to the rectangle on the upper right or lower right, representing the direction of propagation of odd-order diffracted rays from the intermediate region 120 to the coupling region 130. Figure 1 The direction of the light rays diffracted to the upper right or lower right, that is, for odd-order diffracted light rays, the propagation direction towards the coupling region 130 intersects the propagation direction of the light rays from the coupling region 110 to the middle region 120. At this time, most of the odd-order diffracted light rays cannot reach the coupling region, or only a portion of the odd-order diffracted light rays reach the coupling region. K3 is the K-vector light ray of a single coupling grating region 133. When the light ray propagates to the coupling grating region 133 and diffracts, its K-vector is superimposed. After K3 is superimposed, the rectangle returns to the origin, indicating that this part of the light ray is coupled out of the coupling grating region 133.

[0039] In this embodiment, the pupil-expanding waveguide 100 satisfies the following setting: K1=K3. For light rays passing through the intermediate region 120, their propagation direction is not affected by the intermediate region 120. Therefore, when the K vector of the coupling-in grating region 111 and the single coupling-out grating region 133 is designed to satisfy the above setting, the effect of light rays passing through the intermediate region 120 being coupled out from the single coupling-out grating region 133 can be achieved. At the same time, since the propagation direction of even-order diffracted light rays is also consistent with the propagation direction of light rays passing through the intermediate region 120, even-order light rays can also be coupled out from the single coupling-out grating region 133.

[0040] When the pupil-expanding waveguide 100 satisfies K1=K3, in some embodiments of this utility model, a portion of the light rays coupled from the coupling region 110 undergoes an even number of diffractions in the intermediate region 120 and then propagates to a single coupling-out grating region 133 to form a first ray. Another portion of the light rays coupled from the coupling region 110 is transmitted through the intermediate region 120 and then propagates to a single coupling-out grating region 133 to form a second ray. As mentioned above, at least a portion of the first ray and the second ray can be coupled out in the single coupling-out grating region 133, thereby making full use of the light transmitted through the intermediate region 120 and helping to improve the light utilization rate.

[0041] When the intermediate region 120 includes a first intermediate grating region 121 and a second intermediate grating region 122 symmetrically arranged along the third center line, in some embodiments of the present invention, refer to Figure 3 The coupling region 130 includes a first coupling grating region 131 and a second coupling grating region 132, both of which include grating structures. The first coupling grating region 131 and the second coupling grating region 132 are distributed side by side. For example, the first coupling grating region 131 and the second coupling grating region 132 are distributed along the aforementioned second arrangement direction.

[0042] In this embodiment, the pupil-expanding waveguide is configured such that light rays that transmit through the intermediate region 120 and propagate to the first coupling grating region 131 can propagate from the first coupling grating region 131 to the second coupling grating region 132 and be coupled out from the second coupling grating region 132; and light rays that transmit through the intermediate region 120 and propagate to the second coupling grating region 132 can propagate from the second coupling grating region 132 to the first coupling grating region 131 and be coupled out from the first coupling grating region 131. That is, for the light rays transmitted through the intermediate region 120, part of them will propagate to the first coupling grating region 131, and the other part will propagate to the second coupling grating region 132. For the transmitted light rays that propagate to the first coupling grating region 131, they will not be directly coupled out of the first coupling grating region 131, but will be deflected by the grating structure of the first coupling grating region 131 to the second coupling grating region 132 for coupling out. Similarly, for the transmitted light rays that propagate to the second coupling grating region 132, they will not be directly coupled out of the second coupling grating region 132, but will be deflected by the grating structure of the second coupling grating region 132 to the first coupling grating region 131 for coupling out.

[0043] When the coupling region 130 includes a first coupling grating region 131 and a second coupling grating region 132, in some embodiments of the present invention, the pupil-expanding waveguide 100 is configured such that: among the light rays diffracted in the intermediate region 120, light rays that have undergone an even number of diffractions and propagate to the first coupling grating region 131 propagate from the first coupling grating region 131 to the second coupling grating region 132 and are coupled out from the second coupling grating region 132; and light rays that have undergone an even number of diffractions and propagate to the second coupling grating region 132 propagate from the second coupling grating region 132 to the first coupling grating region 131 and are coupled out from the first coupling grating region 131. That is, for light rays that have undergone even-numbered diffraction, their coupling path is similar to that of light rays that have been transmitted through the intermediate region 120. For even-numbered diffracted light rays L1 that propagate to the first coupling grating region 131, they will not be directly coupled out of the first coupling grating region 131, but will be deflected by the grating structure of the first coupling grating region 131 to the second coupling grating region 132 for coupling out. Similarly, for even-numbered diffracted light rays L1 that propagate to the second coupling grating region 132, they will not be directly coupled out of the second coupling grating region 132, but will be deflected by the grating structure of the second coupling grating region 132 to the first coupling grating region 131 for coupling out.

[0044] For example, the intermediate region 120 may include the aforementioned first intermediate grating region 121 and second intermediate grating region 122. Then, for an even-order diffracted ray L1, its propagation path is as follows: a portion of the ray couples into the coupling region 110 and propagates to the first intermediate grating region 121, then propagates from the first intermediate grating region 121 to the first output grating region 131, then propagates from the first output grating region 131 to the second output grating region 132, and another portion of the ray couples into the coupling region 110 and propagates to the second intermediate grating region 122, then propagates from the second intermediate grating region 122 to the second output grating region 132, and then propagates from the second output grating region 132 to the first output grating region 131. (Combined with...) Figure 4 Taking the even-order diffracted ray L1 propagating to the first coupling grating region 131 as an example, as mentioned above, it is superimposed with the K vector K of the first intermediate grating region 121. 21 Then, it propagates horizontally to the right to the first coupling grating region 131. The rectangular frame is moved from the center position to the middle position on the right side of the figure, where it is further superimposed with the K vector K of the first coupling grating region 131. 31 Then, the rectangular frame is moved from the middle of the right side of the figure to the lower right side. At this time, the vector arrow (not shown in the figure) points from the center area to the lower right side of the rectangular frame, which represents that the even-order diffracted light L1 propagating to the first coupling grating region 131 propagates to the second coupling grating region 132 in a direction that is tilted to the lower right.

[0045] When the coupling region 130 includes a first coupling grating region 131 and a second coupling grating region 132, in some embodiments of the present invention, the pupil-expanding waveguide 100 is configured such that, among the light rays diffracted in the intermediate region 120, light rays that have undergone odd-order diffraction and propagate to the first coupling grating region 131 can be coupled out from the first coupling grating region 131, and light rays that have undergone odd-order diffraction and propagate to the second coupling grating region 132 can be coupled out from the second coupling grating region 132. That is, for light rays that have undergone odd-order diffraction, their coupling path is different from that of light rays that transmit through the intermediate region 120. For odd-order diffracted light rays L2 that propagate to the first coupling grating region 131, they will be coupled out directly from the first coupling grating region 131. Similarly, for odd-order diffracted light rays L2 that propagate to the second coupling grating region 132, they will be coupled out directly from the second coupling grating region 132.

[0046] For example, the intermediate region 120 may include the aforementioned first intermediate grating region 121 and second intermediate grating region 122. Then, for an odd-order diffracted ray L2, its propagation path is as follows: a portion of the ray couples into the coupling region 110 and propagates to the first intermediate grating region 121, then propagates from the first intermediate grating region 121 to the first output grating region 131, and another portion of the ray couples into the coupling region 110 and propagates to the second intermediate grating region 122, then propagates from the second intermediate grating region 122 to the second output grating region 132. Combined with... Figure 4 Taking the odd-order diffracted ray L2 propagating to the first coupling grating region 131 as an example, its K-vector K superimposed on the first intermediate grating region 121... 21 Then, the rectangular frame is moved from the middle of the right side of the figure to the upper right side. At this time, the vector arrow (not shown in the figure) points from the center area to the upper right side of the rectangular frame, which represents that the odd-order diffracted light L2 propagating to the first intermediate grating region 121 propagates to the first coupling grating region 131 in a direction that is tilted to the upper right.

[0047] In other embodiments, the pupil-expanding waveguide 100 can be a combination of the above embodiments, that is, it can utilize both transmitted light and even-order diffracted light and odd-order diffracted light, thereby improving the utilization rate of light.

[0048] When the output region 130 includes the first output grating region 131 and the second output grating region 132, in some embodiments of the present invention, the input region 110 includes the input grating region 111, which is used to couple light into the waveguide body 140. The specific details can be understood with reference to the foregoing embodiments.

[0049] In this embodiment, refer to Figure 4 The pupil-expanding waveguide 100 meets the following settings: K1+K31 +K 32 =0, K1 is the K vector coupled into the grating region 111, K 31 K is the K vector of the first coupled grating region 131, K 32 The K vector is the second output grating region 132. For light rays that transmit through the intermediate region 120, their propagation direction is not affected by the intermediate region 120. Therefore, when the K vectors of the input grating region 111, the first output grating region 131, and the second output grating region 132 are designed to meet the above settings, the effect of light rays that transmit through the intermediate region 120 being coupled out from the first output grating region 131 and the second output grating region 132 can be achieved.

[0050] When the pupil-expanding waveguide 100 satisfies K1+K 31 +K 32 When =0, in some embodiments of this utility model, refer to Figure 4 The pupil-expanding waveguide 100 meets the following settings: K 31 =K 22 K 32 =K 21 K 31 K is the K vector of the first coupled grating region 131, K 32 K is the K vector of the second coupled grating region 132, K 21 K is the K vector of the first intermediate grating region 121, K 22 This is the K vector for the second intermediate grating region 122. By adopting the above setting, the coupling requirements of odd-order diffracted rays and even-order diffracted rays can be met.

[0051] Augmented Reality (AR) is a reality display technology that integrates real-world environments with virtual images. It typically comprises two components: an optical engine and an optical display screen. The optical display screen transmits the content displayed by the optical engine to the viewer's eyes, while the viewer can simultaneously see the real world through the screen, thus achieving a fusion and interactive experience between virtual images and the real world. Laser Beam Scanning (LBS) optical engines are considered a promising solution due to their simple structure, small size, high luminous efficiency, low power consumption, and wide color gamut. LBS optical engines include a laser, optical components, and a micro-opto-electro-mechanical microscope (MEMS). However, due to the size limitations of the mirrors in the MEMS assembly, the output beam of an LBS is relatively small. When paired with a waveguide with a large field of view and high refractive index, the beam spacing after pupil expansion becomes too long. This causes the light beam to exceed the range of the human pupil when it exits the coupling grating, preventing the image source it carries from being received by the human eye. This results in problems such as discontinuous images captured by the human eye and low brightness. Based on this, one design scheme exists that first pre-expands the light spot emitted from the optical engine using a pre-expanding waveguide. The pre-expanded light spot then enters the display waveguide, ensuring a continuous light spot as it couples out to the human eye. However, as mentioned earlier, the expanding waveguide suffers from low luminous efficiency. Therefore, when the light is pre-expanded via the waveguide before passing through the display waveguide, the final brightness of the light entering the human eye is relatively low. While this solves the problem of image discontinuity, it results in low display brightness and poor display quality.

[0052] Based on the aforementioned technical problems, the second embodiment of this utility model proposes a display device that can be applied to products such as AR glasses. (See reference...) Figure 5 The display device includes a light source assembly, a pupil-expanding waveguide 100 proposed in the aforementioned embodiments, and a display waveguide 200. The exit pupil size of the light source assembly is less than or equal to 1.5 mm. In one specific embodiment, the light source assembly is a laser beam scanning optical engine.

[0053] The display waveguide 200 includes a secondary coupling region 210 and a secondary coupling region 220. Light emitted from the light source assembly enters the display waveguide 200 through the coupling region 110 and exits through the coupling region 130. The light emitted from the coupling region 130 enters the display waveguide 200 through the secondary coupling region 210 and exits through the secondary coupling region 220. In this design, the pre-pupil expansion using the pupil-expanding waveguide 100 in the first embodiment, followed by the expanded light spot entering the display waveguide 200, ensures a continuous pupil-expanding light spot when it exits the display waveguide 200 to the human eye. This eliminates problems such as image loss caused by a small exit pupil. Furthermore, since the pupil-expanding waveguide 100 can efficiently utilize the transmitted light from the intermediate transmission region 120 while achieving two-dimensional pupil expansion, it improves light utilization and enhances the brightness of the image received by the human eye.

[0054] In some specific embodiments, the light source assembly includes a laser source and a micro-electro-mechanical system (MEMS) mirror. The laser source is used to emit laser light; for example, the laser source is configured as a laser beam scanning optomechanism. The MEMS mirror is used to reflect the laser light to form rays.

[0055] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A pupil-expanding optical waveguide, characterized in that, It includes a waveguide body and a coupling region, an intermediate region and a coupling out region disposed on the waveguide body. The coupling region is used to couple light into the waveguide body, and the intermediate region is used to dilate the light coupled into the waveguide body at least in a first direction. The pupil-expanding waveguide is configured such that: a portion of the light rays coupled in from the coupling region are diffracted in the intermediate region and then propagate to the coupling-out region; another portion of the light rays coupled in from the coupling region are transmitted through the intermediate region and then propagate to the coupling-out region; the coupling-out region is used to expand the pupil of at least a portion of the light rays diffracted through the intermediate region and at least a portion of the light rays transmitted through the intermediate region at least in a second direction and couple them out of the waveguide body; the first direction and the second direction are set at an angle. The coupling-in region has a first centerline, and the coupling-out region has a second centerline, wherein the first centerline and the second centerline are collinear.

2. The pupil-expanding optical waveguide according to claim 1, characterized in that, The intermediate region has a third center line, and the first center line is collinear with the third center line; and / or; the intermediate region is located between the coupling-in region and the coupling-out region.

3. The pupil-expanding optical waveguide according to claim 2, characterized in that, The intermediate region includes a first intermediate grating region and a second intermediate grating region symmetrically arranged along the third center line. The pupil-expanding waveguide is configured such that a portion of the light rays coupled from the coupling region are diffracted in the first intermediate grating region and the second intermediate grating region to expand the pupil, and in the direction perpendicular to the third center line, the pupil-expanding directions of the light rays in the first intermediate grating region and the second intermediate grating region are opposite.

4. The pupil-expanding optical waveguide according to any one of claims 1 to 3, characterized in that, The coupling-out region includes a single coupling-out grating region. The pupil-expanding waveguide is configured such that: a portion of the light rays coupled in from the coupling-in region are diffracted in the intermediate region and then propagate to the single coupling-out grating region; another portion of the light rays coupled in from the coupling-in region are transmitted through the intermediate region and then propagate to the single coupling-out grating region; the single coupling-out grating region is used to couple at least a portion of the light rays incident thereon out of the waveguide body.

5. The pupil-expanding optical waveguide according to claim 4, characterized in that, The coupling region includes a coupling grating region, which is used to couple light rays into the waveguide body; The pupil-expanding waveguide satisfies the following settings: K1=K3, where K1 is the K vector of the coupled-in grating region and K3 is the K vector of the single coupled-out grating region.

6. The pupil-expanding optical waveguide according to claim 5, characterized in that, A portion of the light rays coupled in from the coupling region undergoes an even number of diffractions in the intermediate region and then propagates into the single coupling grating region to form a first ray. Another portion of the light rays coupled in from the coupling region passes through the intermediate region and then propagates into the single coupling grating region to form a second ray. At least a portion of the first ray and the second ray are coupled out in the single coupling grating region.

7. The pupil-expanding optical waveguide according to claim 3, characterized in that, The coupling region includes a first coupling grating region and a second coupling grating region. The pupil-expanding waveguide is configured such that light rays that transmit through the intermediate region and propagate to the first coupling grating region can propagate from the first coupling grating region to the second coupling grating region and be coupled out from the second coupling grating region; and light rays that transmit through the intermediate region and propagate to the second coupling grating region can propagate from the second coupling grating region to the first coupling grating region and be coupled out from the first coupling grating region.

8. The pupil-expanding optical waveguide according to claim 7, characterized in that, The pupil-expanding waveguide is configured such that, among the light rays diffracted in the intermediate region, light rays that have undergone an even number of diffractions and propagate to the first coupling grating region can propagate from the first coupling grating region to the second coupling grating region and be coupled out from the second coupling grating region; and light rays that have undergone an even number of diffractions and propagate to the second coupling grating region can propagate from the second coupling grating region to the first coupling grating region and be coupled out from the first coupling grating region. And / or, the pupil-expanding waveguide is configured such that, among the light rays diffracted in the intermediate region, light rays that have undergone an odd number of diffractions and propagated to the first coupling grating region can be coupled out from the first coupling grating region, and light rays that have undergone an odd number of diffractions and propagated to the second coupling grating region can be coupled out from the second coupling grating region.

9. The pupil-expanding optical waveguide according to claim 7, characterized in that, The coupling region includes a coupling grating region, which is used to couple light rays into the waveguide body; The pupil-expanding waveguide satisfies the following configuration: K1+K 31 +K 32 =0, K1 is the K vector of the coupled grating region, K 31 K is the K vector of the first coupled grating region, K 32 The K vector represents the second coupled grating region; the first coupled grating region and the second coupled grating region are symmetrical along the second centerline.

10. The pupil-expanding optical waveguide according to claim 9, characterized in that, The pupil-expanding optical waveguide satisfies the following configuration: K 31 =K 22 K 32 =K 21 K 31 K is the K vector of the first coupled grating region, K 32 K is the K vector of the second coupled grating region, K 21 K is the K vector of the first intermediate grating region, K 22 is the K vector of the second intermediate grating region.

11. A display device, characterized in that, include: A light source assembly, wherein the exit pupil size of the light source assembly is less than or equal to 1.5 mm; The pupil-expanding waveguide according to any one of claims 1 to 10; Display waveguide; Specifically, the light emitted from the light source component is coupled into the coupling region of the pupil-expanding waveguide and coupled out from the coupling region. The light coupled out from the coupling region is coupled into the display waveguide and coupled out from the display waveguide into the user's eye region.

12. The display device according to claim 11, characterized in that, The light source assembly includes a laser source and a microelectromechanical system (MEMS) reflector. The laser source emits laser light, and the MEMS reflector reflects the laser light to form the light beam.

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