Optical waveguide and augmented reality display device

Abstract

The present invention discloses an optical waveguide including a waveguide substrate. The waveguide substrate is provided with a coupling-in region and a coupling-out region. A coupling-in grating is provided in the coupling-in region. The coupling-out region includes a first coupling-out region and a second coupling-out region. A first coupling-out grating is provided in the first coupling-out region. A second coupling-out grating is provided in the second coupling-out region. The coupling-in grating and the second coupling-out grating are one-dimensional gratings. The first coupling-out grating is a two-dimensional grating. With the above configuration, the optical waveguide improves the overall utilization efficiency and maximally expands the range of pupil emergence. The present invention also provides a kind of augmented reality display device.

Description

Technical Field

[0001] The present invention relates to the field of augmented reality display technology, and particularly to optical waveguides and augmented reality display devices.

Background Art

[0002] Augmented Reality (AR) technology is a new technology that not only displays real-world information but also virtual-world information simultaneously, enabling the two types of information to complement and seamlessly integrate with each other. In visual augmented reality, users can use a helmet display to recombine the real world and computer graphics, and then see the real world surrounding it.

[0003] Due to its total internal reflection optical properties, ultra-thin profile, and surface-processable structure, optical waveguides are widely applied in the field of augmented reality. Augmented reality displays based on optical waveguides have become the mainstream display technology in the current industry. For example, Microsoft's HoloLens constitutes a display window based on butterfly-type pupil expansion conduction and features a large-field-of-view augmented reality display. The augmented reality glasses developed by Magic Leap in the United States achieve color display through a combination of multiple sheets based on the optical waveguide design of second-order one-way conduction.

[0004] Augmented reality displays using optical waveguides can be applied not only in the field of near-eye displays but also in in-vehicle head-up displays. Currently, mainstream head-up displays are based on the principle of geometric optical space reflection and have drawbacks such as a large front body volume, a short virtual image viewing distance, and a narrow eye movement range. Augmented reality head-up displays based on optical waveguides can increase the surface area of the optical waveguide, thereby realizing advantages such as a small front body volume, a long virtual image viewing distance, a wide eye movement range, and a large viewing angle, making it a key display technology for smart driving and human-vehicle interaction.

[0005] The grating waveguide structure using coupling-in - conversion - coupling-out, which is commonly used in the prior art, as shown in FIG. 1, includes a waveguide substrate 1, a coupling-in region 2, a conversion region 3, and a coupling-out region 4 provided on the waveguide substrate 1. Gratings are provided in the coupling-in region 2, the conversion region 3, and the coupling-out region 4. Image light is incident from the coupling-in region 2 and diffracted in the coupling-in region 2. The light rays that satisfy the total reflection condition are conducted to the conversion region 3 by total reflection within the waveguide substrate 1. The light rays interact with the gratings in the conversion region 3 to realize the bending of the optical path. The bent light rays are continuously conducted to the coupling-out region 4 by the total reflection conduction method, and finally coupled to the human eye by the coupling-out region 4 to realize virtual imaging. In the above process, the light rays are extended and expanded in the x-axis direction by being conducted from the coupling-in region 2 to the conversion region 3, and extended and expanded in the y-axis direction by being conducted from the conversion region 3 to the coupling-out region 4. Thereby, the visual field expansion (pupil dilation) in the two-dimensional space is realized. However, in the prior art, there are islands in the design of the coupling-in region 2, the conversion region 3, and the coupling-out region 4 for conducting light rays in terms of visual field expansion and coupling. There is a lot of waste in the light ray conduction process, the overall coupling efficiency is low, and the limit of the pupil dilation range is large.

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide an optical waveguide that can maximize the expansion of the pupil exit range while improving the overall utilization efficiency.

Means for Solving the Problems

[0007] The optical waveguide according to the present invention includes a waveguide substrate. A coupling-in region and a coupling-out region are provided in the waveguide substrate. A coupling-in grating is provided in the coupling-in region. The coupling-out region includes a first coupling-out region and a second coupling-out region. A first coupling-out grating is provided in the first coupling-out region, and a second coupling-out grating is provided in the second coupling-out region. The coupling-in grating and the second coupling-out grating are one-dimensional gratings, and the first coupling-out grating is a two-dimensional grating.

[0008] Furthermore, the second coupling-out region includes a first sub-region and a second sub-region. The second coupling-out grating includes a first sub-grating and a second sub-grating. The first sub-grating is provided in the first sub-region, and the second sub-grating is provided in the second sub-region.

[0009] Furthermore, the first sub-region and the second sub-region are symmetrically provided on both sides of the first coupling-out region.

[0010] Furthermore, the grating orientation of the coupling-in grating coincides with the width direction of the waveguide substrate. The first coupling-out grating includes a first grating orientation M and a second grating orientation N arranged in an intersecting manner. The grating orientation of the first sub-grating is the same as the first grating orientation M, and the grating orientation of the second sub-grating is the same as the second grating orientation N.

[0011] Furthermore, the angle between the first grating orientation M and the second grating orientation N is 90° to 160°.

[0012] Furthermore, the coupling-in region, the first coupling-out region, the first sub-region, and the second sub-region are all rectangular, the width of the coupling-in region is the same as the width of the first coupling-out region and they are located at the same position in the width direction of the waveguide substrate, the widths of the first sub-region and the second sub-region are smaller than or equal to the width of the first coupling-out region, the lengths of the first sub-region, the second sub-region, and the first coupling-out region are equal to each other.

[0013] Furthermore, the first coupling-out region is divided into a plurality of regions from the direction close to the coupling-in region to the direction away from the coupling-in region, and the gratings in the plurality of regions have different depths and duty ratios, the first sub-region is divided into a plurality of regions from the direction close to the first coupling-out region to the direction away from the first coupling-out region, and the gratings in the plurality of regions have different depths and duty ratios, the second sub-region is divided into a plurality of regions from the direction close to the first coupling-out region to the direction away from the first coupling-out region, and the gratings in the plurality of regions have different depths and duty ratios.

[0014] Furthermore, the coupling-in grating, the first coupling-out grating, and the second coupling-out grating are located on the surfaces on the same side of the waveguide substrate.

[0015] Furthermore, the first coupling-out grating has a nano-grid structure, and the coupling-in grating and the second coupling-out grating have a nanowire structure.

[0016] The present invention also provides an augmented reality display device including the optical waveguide described above.

Advantages of the Invention

[0017] The optical waveguide provided by the present invention installs a one-dimensional coupling grating in the coupling region of the waveguide substrate. The coupling-out region includes a first coupling-out region and a second coupling-out region. A two-dimensional first coupling-out grating is provided in the first coupling-out region, and a one-dimensional second coupling-out grating is provided in the second coupling-out region. For the optical waveguide of the present invention, coupling-in is performed with a one-dimensional grating, and coupling-out is performed with a hybrid grating. Light rays perform pupil expansion conduction in the form of point-to-plane in the optical waveguide. Compared with the conventional optical waveguide expansion augmented reality display scheme, the optical waveguide of the present invention does not need to install a conversion grating, and has characteristics such as high bandwidth, high interconnectivity, and inherent parallel processing. It forms the conduction of neural network interconnectivity for continuously input light rays, and performs coupling-out while expanding the pupil from point to plane. Thereby, the overall utilization efficiency can be improved, and the range of exiting the pupil can be maximally expanded.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

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Figure 5a

Figure 5b

Figure 5c

Figure 5d

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Figure 8

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Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0019] Hereinafter, in accordance with the drawings and examples, specific embodiments of the present invention will be described in more detail. The following examples are for explaining the present invention, but not for limiting the scope of the present invention.

[0020] Figure 2 is a schematic diagram of the structure of an optical waveguide according to a preferred embodiment of the present invention. As shown in Figure 2, the optical waveguide according to this embodiment includes a waveguide substrate 10. The waveguide substrate 10 is provided with a coupling-in region 20 and a coupling-out region 30. The coupling-in region 20 is provided with a coupling-in grating 21. The coupling-out region 30 is provided with a coupling-out grating. The coupling-out region 30 includes a first coupling-out region 31 and a second coupling-out region 32. The first coupling-out region 31 is provided with a first coupling-out grating 41. The second coupling-out region 32 is provided with a second coupling-out grating 42.

[0021] The waveguide substrate 10 has a high transmittance within the wavelength range of visible light and may be made of materials such as glass and resin.

[0022] Specifically, the second coupling-out region 32 includes a first sub-region 321 and a second sub-region 322. The second coupling-out grating 42 includes a first sub-grating 421 provided in the first sub-region 321 and a second sub-grating 422 provided in the second sub-region 322.

[0023] Furthermore, the first sub-region 321 and the second sub-region 322 are symmetrically provided on both sides of the first coupling-out region 31.

[0024] In this embodiment, the first coupling-out grating 41 is a two-dimensional grating, and the coupling-in grating 21 and the second coupling-out grating 42 are one-dimensional gratings. That is, the grating in the coupling-out region 30 is a hybrid grating, with the two-dimensional grating located in the center and the one-dimensional gratings located on both the left and right sides. The one-dimensional grating is composed of a plurality of one-dimensional grating units and has a grating orientation in one direction. The two-dimensional grating is composed of a plurality of two-dimensional grating units. The plurality of two-dimensional grating units have a grating orientation in two directions and are arranged in an array.

[0025] Furthermore, the first coupling-out grating 41 is a nano lattice structure. The single unit of the nano lattice structure can be any regular or irregular shape such as a cylinder, a prism, or a trapezoidal prism, and may be arranged periodically. The coupling-in grating 21 and the second coupling-out grating 42 are nano wire structures. The nano wire structure is a linear structure and may be a regular rectangle or an irregular shape, and is also arranged periodically. They can be manufactured using holographic interference technology, lithography technology, or nanoimprint technology.

[0026] Furthermore, the x-direction is defined as the width direction of the waveguide substrate 10 in the figure, the y-direction is defined as the length direction of the waveguide substrate 10 in the figure, and the z-direction is defined as the thickness direction of the waveguide substrate 10. Here, the coupling-in grating 21 has one grating orientation (i.e., the channel direction of the grating). In this embodiment, the grating orientation of the coupling-in grating 21 coincides with the x-direction, that is, it coincides with the width direction of the waveguide substrate 10.

[0027] The first coupling-out grating 41 has two grating orientations arranged in an intersecting manner, and includes a first grating orientation M and a second grating orientation N. In this embodiment, the grating orientation of the first sub-grating 421 is the same as the first grating orientation M. The grating orientation of the second sub-grating 422 is the same as the second grating orientation N.

[0028] Furthermore, the orientation angle of the first coupling-out grating 41 (i.e., the angle between the first grating orientation M and the second grating orientation N) is 90° to 160°. Specifically, for example, an angle of 150° is formed between the first grating orientation M and the x-direction, and an angle of 30° is formed between the second grating orientation N and the x-direction.

[0029] Furthermore, the coupling-in region 20, the first coupling-out region 31, the first sub-region 321, and the second sub-region 322 are all rectangular. The coupling-in region 20 has the same width as the first coupling-out region 31 and is located at the same position as the first coupling-out region 31 in the width direction (x-direction) of the waveguide substrate 10. However, in the y-direction, the first coupling-out region 31 is located below the coupling-in region 20. The width of the first sub-region 321 and the second sub-region 322 in the x-direction is smaller than or equal to the width of the first coupling-out region 31 in the x-direction. The first sub-region 321, the second sub-region 322, and the first coupling-out region 31 have the same height in the y-direction and are at the same position.

[0030] FIG. 3 is a schematic diagram showing the ray conduction of an optical waveguide according to a preferred embodiment of the present invention. FIG. 4 is a schematic diagram showing another ray conduction mode of the optical waveguide according to a preferred embodiment of the present invention. Referring to FIGS. 3 and 4 together, when the image ray is coupled by the coupling-in region 20 and conducted to the coupling-out region 30, first, it enters the first coupling-out region 31 in the middle of the coupling-out region 30. The first coupling-out grating 41 of the first coupling-out region 31 has a nano-grating structure. The light coupled in and conducted enters obliquely into the first coupling-out grating 41 at a certain angle. The first coupling-out grating 41 includes rays that diffuse in multiple directions within the optical waveguide, including coupling-out to the left, coupling-out to the right, and coupling-out at the center. In the process of the ray being coupled out and conducted in the first coupling-out region 31, it continuously performs multi-directional diffusion in a specific direction, realizing the function of conducting while expanding the pupil. Also, the conduction light coupled out to the left and right is coupled out while conducting in the original direction. Therefore, the optical waveguide of the present invention includes coupling-out at the center and coupling-out on both the left and right sides.

[0031] Furthermore, the coupling-in grating 21, the first coupling-out grating 41, and the second coupling-out grating 42 are located on the surface of the same side of the waveguide substrate 10, but are not limited thereto. As shown in FIGS. 5a to 5d, for the optical waveguide, when the image light source 40 is incident from the structural surface (the surface provided with the coupling-in grating 21 and the coupling-out grating) and the human eye 50 observes from the non-structural surface on the other side (the surface without the grating), or when the image light source 40 is incident from the non-structural surface and the human eye 50 is located on the same side as the image light source 40, or when the image light source 40 is incident from the structural surface and the human eye 50 is located on the same side as the image light source 40, or when the image light source 40 is incident from the non-structural surface and the human eye 50 observes from the structural surface.

[0032] FIG. 6 is a simulation diagram of coupling when an incident light beam is incident on the coupling-in region of the optical waveguide of a preferred embodiment of the present invention. FIG. 7 is a schematic diagram showing a mode in which the diffracted light generated in FIG. 6 is conducted in the optical waveguide. As can be seen by referring to FIGS. 6 and 7 together, the coupling-in grating 21 of the coupling-in region 20 has a one-dimensional nanowire structure when light is incident on the coupling-in region 20 from air, and has positive and negative single-stage diffraction. When the incident wave is a light beam of 520 nm and is normally incident (i.e., perpendicularly incident) on the coupling-in region 20, among the generated diffracted light beams, the diffracted light beam perpendicular to the grating orientation of the coupling-in grating 21 is conducted to the coupling-out region 30.

[0033] FIG. 8 is a diffraction simulation diagram of FIG. 7. As shown in FIG. 8, in FIG. 7, the light beam that is coupled in and diffracted is coupled out. At this time, light beams mainly at azimuth angles of 210°, 270°, and 330° are generated. Here, the light beam at the azimuth angle of 210° continues to be conducted and is coupled out from the left, the light beam at the azimuth angle of 270° continues to be conducted and is coupled out from the center, and the light beam at the azimuth angle of 330° continues to be conducted and is coupled out from the right.

[0034] FIG. 9 further shows a schematic diagram of light beam conduction in the first coupling-out region. As shown in FIG. 9, the light passing through point A1 generates light beams A2, A6, and A4. The A2 light beam continues to be conducted, touches the next nanogrid, and generates light beams A12, A3, and A7. The A6 light beam is conducted and generates light beams A7, A9, and A8. Repeating in this way, diffracted clusters can be formed that are scaled in the 210° direction, 270° direction, and 330° direction. Also, the 210° direction and the 330° direction correspond to the left coupling-out and right coupling-out regions. The scanning electron microscope image of the first coupling-out region 31 is as shown in FIG. 10.

[0035] It is a trend graph within the range of a duty ratio of 0.1 to 1.1 and a depth of 50 nm to 600 nm for diffracted light at an azimuth angle of 270° marked by the black frame B in FIG. 8. The purpose of FIG. 11 is to analyze the diffraction characteristics from top to bottom in the first coupling-out region 31. From FIG. 11, it can be seen that as the depth increases and the duty ratio decreases, the efficiency at an azimuth angle of 270° changes significantly from a small value.

[0036] In order to ensure the uniformity of the coupling light rays throughout the coupling-out region 30, it is necessary to control the structure of the coupling-out region 30. FIG. 12 is a schematic structural diagram of an optical waveguide according to another embodiment of the present invention. As shown in FIG. 12, based on the conduction efficiencies with different duty ratios and different depths, the structure of the entire coupling-out region 30 can be planned for the optical waveguide. For example, by modulating the depth and shape for each region, the uniformity of the light ray coupling-out intensity within each region can be enhanced.

[0037] Specifically, the first coupling-out region 31 is divided into a plurality of regions in the direction from the direction close to the coupling-in region 20 to the direction away from the coupling-in region 20 (from top to bottom in the y direction). The gratings within the plurality of regions have different depths and duty ratios. For example, the first coupling-out region 31 can be divided into five regions, namely C1, C2, C3, C4, and C5. Here, the depth from C1 to C5 gradually increases, and / or the duty ratio from C1 to C5 gradually decreases.

[0038] The first sub-region 321 is divided into a plurality of regions in the direction from the direction close to the first coupling-out region 31 to the direction away from the first coupling-out region 31 (from right to left in the x direction). The gratings within the plurality of regions have different depths and duty ratios. For example, the first sub-region 321 can be divided into three regions, namely D1, D2, and D3. Here, the depth from D1 to D3 gradually increases, and / or the duty ratio from D1 to D3 gradually decreases.

[0039] Divide the second sub-region 322 into a plurality of regions in a direction from near the first coupling-out region 31 to away from the first coupling-out region 31 (from left to right in the x-direction). The gratings within the plurality of regions have different depths and duty ratios. For example, the second sub-region 322 can be divided into three regions, namely E1, E2, and E3. Here, the depth from E1 to E3 gradually increases, and / or the duty ratio from E1 to E3 gradually decreases.

[0040] The present invention relates to an augmented reality display device including the optical waveguide described above. Other configurations of the augmented reality display device are well known to those skilled in the art and will not be described further herein.

[0041] The optical waveguide proposed by the present invention couples in with a one-dimensional grating and couples out with a hybrid grating, and the light ray performs pupil expansion conduction in the form of point-to-plane within the optical waveguide. Compared with the conventional optical waveguide augmented reality display scheme, the optical waveguide of the present invention does not need to install a conversion grating, has characteristics such as high bandwidth, high interconnectivity, and inherent parallel processing, and forms the conduction of neural network interconnectivity for the continuously input light ray, and couples out while expanding the pupil from point to plane. Thereby, the overall utilization efficiency can be improved, and the range of exiting the pupil can be maximally expanded.

[0042] In the drawings, for clarity, the dimensions and relative dimensions of the layers and regions are exaggerated. When an element such as a layer, a region, or a substrate is described as being "formed", "arranged", or "positioned" on another element, it should be understood that the element may be directly arranged on the other element, or there may be intermediate elements. Conversely, when an element is referred to as being "directly formed" or "directly arranged" on another element, it means that there are no intermediate elements.

[0043] In this specification, unless there are specific regulations and limitations, terms such as "attachment", "connection", "coupling", etc. should be understood in a broad sense. For example, between elements, it may be a fixed connection, a removable connection, an integral connection, a mechanical connection, an electrical connection, a direct connection, an indirect connection through an intermediate medium, or a communication inside two components. A person skilled in the art can understand the meaning of the above terms according to the specific situation.

[0044] In this specification, the orientation or positional relationship indicated by terms such as "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", "vertical", "horizontal", etc. is the orientation or positional relationship based on the drawings, and is only for the clarity of the technical aspect and the convenience of description, and should not be understood as a limitation to the present invention.

[0045] In this specification, the sequential adjectives "first", "second", etc. used to describe elements are only for distinguishing similar elements, and do not mean that the elements so described need to follow a predetermined order, or time, space, rank, or other limitations.

[0046] In this specification, unless otherwise specified, "a plurality" and "several" mean two or more.

[0047] In this specification, terms such as "include", "comprise", or any other variations thereof are intended to cover non-exclusive inclusion that includes other elements not explicitly listed in addition to the listed elements.

[0048] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily come up with changes or substitutions within the technical scope disclosed by the present invention. All of these changes or substitutions should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the claims.

Claims

1. An optical waveguide including a waveguide substrate (10), wherein a coupling-in region (20) and a coupling-out region (30) are provided in the waveguide substrate (10), a coupling-in grating (21) is provided in the coupling-in region (20), the coupling-out region (30) includes a first coupling-out region (31) and a second coupling-out region (32), a first coupling-out grating (41) is provided in the first coupling-out region (31), and a second coupling-out grating (42) is provided in the second coupling-out region (32), wherein the coupling-in grating (21) and the second coupling-out grating (42) are one-dimensional gratings, and the first coupling-out grating (41) is a two-dimensional grating. An optical waveguide characterized by this.

2. The second coupling-out region (32) includes a first sub-region (321) and a second sub-region (322), the second coupling-out grating (42) includes a first sub-grating (421) and a second sub-grating (422), the first sub-grating (421) is provided in the first sub-region (321), and the second sub-grating (422) is provided in the second sub-region (322). The optical waveguide according to claim 1, characterized by this.

3. The first sub-region (321) and the second sub-region (322) are symmetrically provided on both sides of the first coupling-out region (31). The optical waveguide according to claim 2, characterized by this.

4. The grating orientation of the coupling-in grating (21) coincides with the width direction of the waveguide substrate (10), the first coupling-out grating (41) includes a first grating orientation M and a second grating orientation N arranged to intersect, the grating orientation of the first sub-grating (421) is the same as the first grating orientation M, and the grating orientation of the second sub-grating (422) is the same as the second grating orientation N. The optical waveguide according to claim 2, characterized by this.

5. The angle between the first grating orientation M and the second grating orientation N is 90° to 160°, and the optical waveguide according to claim 4 is characterized in that.

6. The coupling-in region (20), the first coupling-out region (31), the first sub-region (321), and the second sub-region (322) are all rectangular. The width of the coupling-in region (20) is the same as the width of the first coupling-out region (31) and is located at the same position in the width direction of the waveguide substrate (10). The widths of the first sub-region (321) and the second sub-region (322) are smaller than or equal to the width of the first coupling-out region (31). The lengths of the first sub-region (321), the second sub-region (322), and the first coupling-out region (31) are equal to each other, and the optical waveguide according to claim 2 is characterized in that.

7. The first coupling-out region (31) is divided into a plurality of regions from the direction close to the coupling-in region (20) to the direction away from the coupling-in region (20), and the gratings in the plurality of regions have different depths and duty ratios. The first sub-region (321) is divided into a plurality of regions from the direction close to the first coupling-out region (31) to the direction away from the first coupling-out region (31), and the gratings in the plurality of regions have different depths and duty ratios. The second sub-region (322) is divided into a plurality of regions from the direction close to the first coupling-out region (31) to the direction away from the first coupling-out region (31), and the gratings in the plurality of regions have different depths and duty ratios, and the optical waveguide according to claim 2 is characterized in that.

8. The coupling-in grating (21), the first coupling-out grating (41), and the second coupling-out grating (42) are located on the same side surface of the waveguide substrate (10), and the optical waveguide according to claim 1 is characterized in that.

9. The first coupling-out grating (41) has a nano-grating structure, and the coupling-in grating (21) and the second coupling-out grating (42) have a nano-wire structure, and the optical waveguide according to claim 1 is characterized in that.

10. An augmented reality display device, characterized by comprising the optical waveguide according to any one of claims 1 to 9.

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