Optical Waveguide and Augmented Reality Display Devices

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 in particular to optical wave guides and augmented reality display devices. [Background technology]

[0002] Augmented reality (AR) technology is a new technology that seamlessly integrates real-world and virtual-world information by simultaneously displaying both real-world and virtual-world information, allowing the two pieces of information to complement each other and be overlaid. In AR visualization, users can use a helmet display to recombine the real world with computer-generated images, allowing them to see the real world surrounding them.

[0003] Optical waveguides are widely used in the field of augmented reality due to their total internal reflection optical properties, ultra-thin structure, and surface-machinable structure. Augmented reality displays based on optical waveguides have become the mainstream display technology in the industry today. For example, the HoloLens developed by Microsoft uses a butterfly-shaped pupil conduction-based display window to provide a large-field-of-view augmented reality display. The augmented reality glasses developed by the American company Magic Leap are based on a two-dimensional unidirectional conduction optical waveguide design and combine multiple lenses to achieve a color display.

[0004] Augmented reality display using optical waveguides can be applied not only to near-sighted displays but also to in-vehicle head-up displays. Currently, mainstream head-up displays are based on the principle of geometric optics spatial reflection, which has drawbacks such as a large frontal volume, a short virtual image viewing distance, and a narrow eye movement range. Augmented reality head-up displays based on optical waveguides can achieve the advantages of a small frontal volume, a long virtual image viewing distance, a wide eye movement range, and a large viewing angle by increasing the surface area of ​​the optical waveguide, making them a key display technology for smart driving and human-vehicle interaction.

[0005] A commonly used grating waveguide structure using coupling-in-conversion-coupling-out, as shown in FIG. 1, includes a waveguide substrate 1 and a coupling-in region 2, a conversion region 3, and a coupling-out region 4 disposed 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 enters the coupling-in region 2 and is diffracted within the coupling-in region 2. The light satisfying the total internal reflection condition is transmitted to the conversion region 3 by total internal reflection within the waveguide substrate 1. The light interacts with the grating in the conversion region 3 to bend its optical path. The bent light is then transmitted to the coupling-out region 4 by total internal reflection and conduction, and finally coupled into the human eye by the coupling-out region 4 to realize virtual imaging. In the above process, the light is transmitted from the coupling-in region 2 to the conversion region 3, thereby achieving extension and expansion in the x-axis direction, and from the conversion region 3 to the coupling-out region 4, thereby achieving extension and expansion in the y-axis direction. This achieves two-dimensional spatial field of view expansion (pupil expansion). However, in the prior art, the coupling-in region 2, the conversion region 3, and the coupling-out region 4 for transmitting light rays have isolated islands in the design of field of view expansion and coupling, resulting in a lot of waste in the light transmission process, low overall coupling efficiency, and a large limit to the pupil expansion range. Summary of the Invention [Problem to be solved by the invention]

[0006] It is an object of the present invention to provide an optical waveguide that can maximize the range of pupil emission while improving overall utilization efficiency. [Means for solving the problem]

[0007] An optical waveguide according to the present invention includes a waveguide substrate, the waveguide substrate being provided with a coupling-in region and a coupling-out region, the coupling-in region being provided with a coupling-in grating, the coupling-out region being provided with a first coupling-out region and a second coupling-out region, the first coupling-out region being provided with a first coupling-out grating, and the second coupling-out region being provided with a second coupling-out grating; 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 disposed on both sides of the first coupling-out region.

[0010] Furthermore, the grating orientation of the coupling 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 that are arranged to cross each other; 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 between 90° and 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 coupling-in region has the same width as the first coupling-out region and is 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 first sub-region, the second sub-region, and the first coupling-out region have the same length.

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

[0015] Furthermore, the first coupling-out grating is a nano-grating structure, and the coupling-in grating and the second coupling-out grating are nano-wire structures.

[0016] The present invention also provides an augmented reality display device including an optical wave guide as described above. [Effects of the Invention]

[0017] The optical waveguide provided by the present invention has a one-dimensional coupling grating disposed in the coupling region of the waveguide substrate, and a coupling-out region including a first coupling-out region and a second coupling-out region, with a two-dimensional first coupling-out grating disposed in the first coupling-out region and a one-dimensional second coupling-out grating disposed in the second coupling-out region. The optical waveguide of the present invention couples in through the one-dimensional grating and couples out through the mixed grating, and light rays undergo pupil-expanding conduction in the optical waveguide in the form of a point-expanding surface. Compared with conventional optical waveguide augmented reality display schemes, the optical waveguide of the present invention does not require a conversion grating and has features such as high bandwidth, high interconnectivity, and inherent parallel processing. Continuously input light rays form a neural network interconnection conduction, and couple out while expanding the pupil from a point to a surface. This improves overall utilization efficiency and maximizes the pupil area. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram of a grating waveguide structure using coupling-in-transition-coupling-out modes, as commonly used in the prior art. [Figure 2] 1 is a structural schematic diagram of an optical waveguide according to a preferred embodiment of the present invention; [Figure 3] 1 is a schematic diagram illustrating ray conduction of an optical waveguiding according to a preferred embodiment of the present invention; [Figure 4] 2 is a schematic diagram illustrating another light conduction aspect of an optical waveguiding according to a preferred embodiment of the present invention; FIG. [Figure 5a] 1 is a schematic diagram of a combination of an image light source incidence and human observation of an optical wave guide according to a preferred embodiment of the present invention; [Figure 5b] 1 is a schematic diagram of a combination of an image light source incidence and human observation of an optical wave guide according to a preferred embodiment of the present invention; [Figure 5c]1 is a schematic diagram of a combination of an image light source incidence and human observation of an optical wave guide according to a preferred embodiment of the present invention; [Figure 5d] 1 is a schematic diagram of a combination of an image light source incidence and human observation of an optical wave guide according to a preferred embodiment of the present invention; [Figure 6] 1 is a simulation diagram of coupling when an incident ray enters a coupling-in region of an optical waveguide for a preferred embodiment of the present invention; [Figure 7] FIG. 7 is a schematic diagram illustrating how the diffracted light generated in FIG. 6 propagates in an optical waveguide. [Figure 8] FIG. 8 is a diffraction simulation diagram of FIG. 7. [Figure 9] 1 is a schematic diagram of light conduction in the first coupling-out region. FIG. [Figure 10] FIG. 10 is a scanning electron microscope view of the first coupling-out region. [Figure 11] This is a trend diagram of the diffracted light at an azimuth angle of 270° marked by the black frame B in FIG. 8, within the range of 0.1 to 1.1 duty ratio and 50 nm to 600 nm depth. [Figure 12] FIG. 4 is a structural schematic diagram of an optical waveguide according to another embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0019] Specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings and examples. The following examples are intended to illustrate the present invention but are not intended to limit the scope of the present invention.

[0020] FIG. 2 is a structural schematic diagram of an optical waveguide according to a preferred embodiment of the present invention. As shown in FIG. 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 high transmittance in the wavelength range of visible light and may be made of a material such as glass or 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 disposed 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 mixed grating, with a two-dimensional grating located in the center and one-dimensional gratings located on both sides. The one-dimensional grating is composed of multiple one-dimensional grating units and has a grating orientation in one direction. The two-dimensional grating is composed of multiple two-dimensional grating units. The multiple 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 units of the nano-lattice structure may have any regular or irregular shape, such as a cylinder, a rectangular pillar, or a trapezoidal pillar, and may be periodically arranged. The coupling out grating 21 and the second coupling out grating 42 are nanowire structures. The nanowire structures are linear structures and may be regular rectangular or irregular, and may also be periodically arranged. 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 grating 21 has one grating orientation (i.e., the channel direction of the grating). In this embodiment, the grating orientation of the coupling grating 21 coincides with the x-direction, i.e., coincides with the width direction of the waveguide substrate 10.

[0027] The first coupling-out grating 41 has two grating orientations arranged crosswise, 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 widths in the x direction of the first sub-region 321 and the second sub-region 322 are smaller than or equal to the width in the x direction of the first coupling-out region 31. 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 located at the same position.

[0030] FIG. 3 is a schematic diagram illustrating the light conduction of an optical waveguide according to a preferred embodiment of the present invention. FIG. 4 is a schematic diagram illustrating another light conduction mode of an optical waveguide according to a preferred embodiment of the present invention. Referring to FIGS. 3 and 4 together, when image light is coupled by the coupling-in region 20 and transmitted to the coupling-out region 30, it first enters the first coupling-out region 31 located in the middle of the coupling-out region 30. The first coupling-out grating 41 in the first coupling-out region 31 has a nano-grating structure. The coupled-in and transmitted light enters the first coupling-out grating 41 obliquely at a certain angle. The first coupling-out grating 41 accommodates light beams that diffuse in multiple directions within the optical waveguide, including left-to-right coupling-out, right-to-left coupling-out, and central coupling-out. During the process of light beams being coupled out and transmitted in the first coupling-out region 31, multidirectional diffusion in a specific direction is constantly performed, achieving the function of transmitting light while widening the pupil. Furthermore, the transmitted light coupled out to the left and right is coupled out while being transmitted in the original direction. Therefore, the optical waveguide of the present invention has a central coupling-out and left and right side coupling-outs.

[0031] Furthermore, the coupling-in grating 21, the first coupling-out grating 41, and the second coupling-out grating 42 are located on the same surface of the waveguide substrate 10, but are not limited to this. As shown in Figures 5a to 5d, optical waveguiding includes cases where the image light source 40 is incident from the structured surface (the surface on which the coupling-in grating 21 and the coupling-out grating are provided) and the eye 50 observes from the other non-structured surface (the surface on which no grating is provided), or where the image light source 40 is incident from the non-structured surface and the eye 50 is located on the same side as the image light source 40, or where the image light source 40 is incident from the structured surface and the eye 50 is located on the same side as the image light source 40, or where the image light source 40 is incident from the non-structured surface and the eye 50 observes from the structured 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 how the diffracted light generated in FIG. 6 is propagated through the optical waveguide. Referring to FIGS. 6 and 7 together, it can be seen that the coupling grating 21 in the coupling-in region 20 has a one-dimensional nanowire structure and exhibits a single step of positive and negative diffraction when light enters the coupling-in region 20 from air. When the incident light is 520 nm light and is orthogonally incident (i.e., perpendicularly incident) on the coupling-in region 20, the diffracted light beams generated that are perpendicular to the grating orientation of the coupling grating 21 are propagated to the coupling-out region 30.

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

[0034] FIG. 9 further illustrates a schematic diagram of light conduction in the first coupling-out region. As shown in FIG. 9, light passing through point A1 generates beams A2, A6, and A4. The A2 beam continues to be conducted and encounters the next nanolattice, generating beams A12, A3, and A7. The A6 beam is conducted to generate beams A7, A9, and A8. Repeating this process, diffraction clusters scaled in the 210°, 270°, and 330° directions can be formed. The 210° and 330° directions correspond to the left and right coupling-out regions. A scanning electron microscope image of the first coupling-out region 31 is shown in FIG. 10.

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

[0036] To ensure uniformity of the coupling-out beam throughout the coupling-out region 30, the structure of the coupling-out region 30 needs to be controlled. FIG. 12 is a schematic diagram of the structure of an optical waveguide according to another embodiment of the present invention. As shown in FIG. 12, the structure of the optical waveguide can be designed throughout the coupling-out region 30 based on different duty ratios and different depths of conduction efficiency. For example, by modulating the depth and shape of each region, the uniformity of the coupling-out beam intensity within each region can be improved.

[0037] Specifically, the first coupling-out region 31 is divided into multiple regions from a direction closer to the coupling-in region 20 to a direction away from the coupling-in region 20 (from top to bottom in the y direction). The gratings in the multiple regions have different depths and duty ratios. For example, the first coupling-out region 31 can be divided into five regions, C1, C2, C3, C4, and C5. Here, the depths from C1 to C5 gradually increase and / or the duty ratios from C1 to C5 gradually decrease.

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

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

[0040] The present invention relates to an augmented reality display device comprising an optical wave guide as described above.Other configurations of augmented reality display devices are well known to those skilled in the art and will not be described further here.

[0041] The optical waveguiding proposed by the present invention couples in through a one-dimensional grating and couples out through a hybrid grating, and the light beam undergoes pupil-expanding conduction in the form of a point-expanding surface in the optical waveguiding. Compared with the conventional optical waveguiding augmented reality display scheme, the optical waveguiding of the present invention does not require the installation of a conversion grating and has characteristics such as high bandwidth, high interconnectivity, and inherent parallel processing, and continuously input light beams form neural network interconnection conduction, and couple out while expanding the pupil from a point to a surface. This improves the overall utilization efficiency and maximizes the expansion of the pupil range.

[0042] In the drawings, the sizes and relative sizes of layers and regions are exaggerated for clarity. When an element such as a layer, region, or substrate is said to be "formed," "disposed," or "located" on another element, it is understood that the element may be directly disposed on the other element, or intermediate elements may be present. Conversely, when an element is referred to as being "directly formed" or "directly disposed" on another element, it is meant that no intermediate elements are present.

[0043] In this specification, unless otherwise clearly specified and limited, the terms "attached," "coupled," "connected," etc. should be understood in a broad sense. For example, elements may be connected in a fixed manner, a detachable manner, an integral manner, a mechanical manner, an electrical manner, a direct manner, an indirect manner via an intermediate medium, or an internal communication between two components. Those skilled in the art can understand the meaning of the above terms according to the specific situation.

[0044] In this specification, the orientations or positional relationships indicated by terms such as "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," "outer," "vertical," and "horizontal" are orientations or positional relationships based on the drawings, and are provided merely for the sake of clarity and convenience of explanation of technical aspects, and should not be understood as limitations on the present invention.

[0045] As used herein, sequential adjectives such as "first," "second," etc., used to describe elements are intended to distinguish between similar elements only and do not imply that the elements so described must follow a predetermined order, or temporal, spatial, chronological, or other constraints.

[0046] As used herein, unless otherwise specified, "plurality" and "some" mean two or more.

[0047] As used herein, terms such as "comprises," "including," or any variation thereof, are intended to cover a non-exclusive inclusion of the recited elements as well as other elements not expressly recited.

[0048] The above are only specific embodiments of the present invention, and the scope of protection of the present invention is not limited thereto. Anyone familiar with the art can easily think of modifications or replacements within the technical scope disclosed in the present invention. All such modifications or replacements should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be governed by the claims.

Claims

1. An optical waveguide comprising 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) 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), and the second coupling-out region (32) is provided with a second coupling-out grating (42); 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; 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 first coupling-out region (31) is divided into a plurality of regions from a direction closer to the coupling-in region (20) to a 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 a direction closer to the first coupling-out region (31) to a 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 a direction closer to the first coupling-out region (31) to a direction away from the first coupling-out region (31), and the gratings in the plurality of regions have different depths and duty ratios.

1. An optical waveguide characterized in that:

2. The first sub-region (321) and the second sub-region (322) are provided symmetrically on both sides of the first coupling-out region (31).

2. An optical waveguide according to claim 1.

3. The grating orientation of the coupling 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 that are arranged crosswise, 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; 2. An optical waveguide according to claim 1.

4. The angle between the first grating orientation M and the second grating orientation N is 90° to 160°.

4. An optical waveguide according to claim 3.

5. 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 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; 2. An optical waveguide according to claim 1.

6. The coupling-in grating (21), the first coupling-out grating (41) and the second coupling-out grating (42) are located on the same surface of the waveguide substrate (10).

2. An optical waveguide according to claim 1.

7. The first coupling-out grating (41) is a nano-lattice structure, and the coupling-in grating (21) and the second coupling-out grating (42) are nano-wire structures.

2. An optical waveguide according to claim 1.

8. The optical waveguide of claim 1, An augmented reality display device.

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