Diffractive optical waveguide and near-eye display device
By combining two-dimensional and one-dimensional grating structures in the coupling region of the diffractive waveguide, the shortcomings of flexibility and rainbow problems in the prior art are solved, and the effects of adapting to custom shapes and mitigating rainbow are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI NORTH OCEAN TECH CO LTD
- Filing Date
- 2025-05-16
- Publication Date
- 2026-06-05
AI Technical Summary
Existing diffractive waveguides are insufficient in terms of flexibility in adapting to various custom shapes and mitigating the rainbow problem. Two-dimensional grating architectures are highly flexible but suffer from severe rainbow problems, while one-dimensional grating architectures have limited design flexibility.
The coupling region of the diffractive waveguide is divided into at least two sub-regions, one of which is a two-dimensional grating structure and the other is a one-dimensional grating structure. By combining the advantages of the two grating structures, it can adapt to various custom shapes and alleviate the rainbow problem.
It effectively mitigates the rainbow effect while adapting to various custom shapes, thus improving the flexibility and image quality of display devices.
Smart Images
Figure CN224328256U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of augmented reality, and more particularly to a diffractive waveguide and near-eye display device. Background Technology
[0002] Augmented reality is a technology that blends the real world with virtual information. Augmented reality display systems typically include micro-projectors and optical displays. The micro-projectors provide virtual display content for the augmented reality display system, which is then projected onto the viewer's eyes through the optical displays. The optical displays are usually transparent optical components, so that users can also see the real world through the optical displays at the same time.
[0003] Existing diffractive waveguides include one-dimensional and two-dimensional grating architectures. One-dimensional grating architectures typically have limited design flexibility due to waveguide shape, resulting in limited versatility. Two-dimensional grating architectures offer greater flexibility and are more suitable for various custom waveguide shapes currently available on the market; however, the inherent characteristics of multi-level diffraction in two-dimensional gratings lead to a relatively severe rainbow problem. There is an urgent need for a diffractive waveguide that can be flexibly adapted to various custom shapes while mitigating the rainbow problem. Utility Model Content
[0004] This application provides a diffractive waveguide and a near-eye display device, wherein the coupling region of the diffractive waveguide is divided into at least two sub-regions, one of which has a two-dimensional grating structure and the other has a one-dimensional grating structure. This cleverly combines the advantages of the two grating structures, which can be flexibly applied to various custom shapes currently on the market, and can also alleviate the rainbow problem.
[0005] This application provides a diffractive waveguide, comprising: a waveguide substrate, the waveguide substrate including at least an insertion region, a first output region, and a second output region, the first output region and the second output region being used to correspond to the left and right eyes of a human eye, respectively; the first output region, the insertion region, and the second output region being arranged sequentially in a first direction; the first output region and the second output region being divided into at least two sub-regions in a second direction; one of the sub-regions of the first output region and the second output region is a two-dimensional grating structure, and the sub-region farthest from the insertion region is a one-dimensional grating structure; the first direction is orthogonal to the second direction.
[0006] In practice, the first coupling region and the second coupling region are divided into three sub-regions in the second direction, with the middle sub-region containing a two-dimensional grating structure and the other two sub-regions containing a one-dimensional grating structure.
[0007] Implementably, the size of the first coupling region and / or the second coupling region in the first direction ranges from 20 to 24 mm; and / or, the size of the first coupling region and / or the second coupling region in the second direction ranges from 14 to 16 mm.
[0008] In practice, the region containing the two-dimensional grating structure in the first and / or second coupling regions is located between the optical paths of the boundary field rays after they are coupled into the waveguide substrate through the coupling region, so that the coupling energy of the two-dimensional grating structure is less than the pupil expansion energy of the two-dimensional grating structure, and the coupling energy of the two-dimensional grating structure is less than the coupling energy of the one-dimensional grating structure.
[0009] In practice, the ratio of the coupling energy of the two-dimensional grating structure to the pupil dilation energy is less than 1 / 3, and the ratio of the coupling energy of the two-dimensional grating structure to the coupling energy of the one-dimensional grating structure is less than 1 / 3.
[0010] In practice, the area containing the two-dimensional grating structure in the first and / or second coupling regions has a size range of 3-6 mm in the second direction.
[0011] In practice, the area of the region containing the two-dimensional grating structure in the first coupling region accounts for 1 / 5 to 1 / 3 of the area of the first coupling region; the area of the region containing the two-dimensional grating structure in the second coupling region accounts for 1 / 5 to 1 / 3 of the area of the second coupling region.
[0012] In practice, the distance between the center position of the first coupling-out region and the center position of the coupling-in region in the first direction is 28-34 mm; and / or, the distance between the center position of the first coupling-out region and the center position of the coupling-in region in the second direction is 5-10 mm.
[0013] Implementably, the grating structure within the coupling region is symmetrical about the central axis of the coupling region in a second direction.
[0014] In practice, both the first and second coupling regions are polygons.
[0015] This application also provides a near-eye display device, which includes a diffractive waveguide and an optomechanic as described in any of the preceding claims.
[0016] This application provides a diffractive waveguide and a near-eye display device, wherein the diffractive waveguide includes at least an input region, a first output region, and a second output region. The first output region and the second output region are respectively used for the left and right eyes of the human eye, and the first output region, the input region, and the second output region are arranged sequentially in a first direction. In particular, the first output region and the second output region are divided into at least two sub-regions in a second direction, and one of these sub-regions is a two-dimensional grating structure, while the sub-region farthest from the input region is a one-dimensional grating structure. By combining the one-dimensional grating structure and the two-dimensional grating structure, the flexibility of two-dimensional pupil expansion provided by the two-dimensional grating structure can be utilized to adapt to various custom waveguide shapes currently available on the market, while the rainbow problem can be alleviated by using the one-dimensional grating structure. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 A schematic diagram of a diffractive waveguide provided in an embodiment of this application;
[0019] Figure 2 This is a schematic diagram of another diffractive waveguide structure provided in an embodiment of this application;
[0020] Figure 3 This is a schematic diagram of another diffractive waveguide structure provided in an embodiment of this application;
[0021] Figure 4 This is a schematic diagram of another diffractive waveguide structure provided in an embodiment of this application;
[0022] Figure 5 This is a schematic diagram of another diffractive waveguide structure provided in an embodiment of this application;
[0023] Figure 6 This is a schematic diagram of another diffractive waveguide structure provided in an embodiment of this application;
[0024] Attached image labels:
[0025] 100: Diffractive waveguide;
[0026] 110: Coupled region;
[0027] 120: First coupling region;
[0028] 130: Second coupling region. Detailed Implementation
[0029] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0030] The technical solution of this application will be described in detail below with reference to specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.
[0031] This application provides a diffractive optical waveguide, which includes a waveguide substrate. The waveguide substrate includes at least an insertion region, a first output region, and a second output region. The first output region and the second output region are respectively used to correspond to the left and right eyes of a human eye. The first output region, the insertion region, and the second output region are arranged sequentially in a first direction. The first output region and the second output region are divided into at least two sub-regions in a second direction. One of the sub-regions of the first output region and the second output region is a two-dimensional grating structure, and the sub-region farthest from the insertion region is a one-dimensional grating structure. The first direction and the second direction are orthogonal.
[0032] Specifically, the diffractive waveguide provided in this application is used for binocular display. After the image light emitted from the optomechanism is incident on the coupling region, a portion of the image light is coupled into the waveguide substrate by the coupling structure in the coupling region and transmitted by total internal reflection towards the first coupling region. This portion of the image light is coupled out through the coupling structure after reaching the first coupling region and enters the left eye. A portion of the image light is coupled into the waveguide substrate by the coupling structure in the coupling region and transmitted by total internal reflection towards the second coupling region. This portion of the image light is coupled out through the coupling structure after reaching the second coupling region and enters the right eye. In this way, binocular display is achieved through an optomechanism.
[0033] In practice, the optical engine is used to project light carrying image information within a predetermined field of view. In this application, the optical engine can be of different types, such as uLED, LCOS, DLP, LBS, and OLED. The waveguide substrate is used for total internal reflection transmission of the image light. In this application, the waveguide substrate can be made of materials with good optical properties, such as resin, glass, or silicon carbide. The coupling-in and coupling-out structures are used to diffract the light to guide its transmission; in this application, the coupling-in and coupling-out structures can be diffractive optical elements such as diffraction gratings.
[0034] For example, refer to Figure 1Taking a spatial rectangular coordinate system as an example, the coupling plane of the diffractive waveguide 100 is taken as the XOY plane, with the first direction being the X-axis and the second direction being the Y-axis. The diffractive waveguide 100 includes a coupling region 110, a first coupling region 120, and a second coupling region 130. The first coupling region 120, the coupling region 110, and the second coupling region 130 are arranged sequentially along the X-axis.
[0035] Further, refer to Figure 1 As can be seen, the first output region 120 is divided into two sub-regions. In these two sub-regions, the sub-region closer to the input region 110 is set with a two-dimensional grating structure, and the other sub-region is set with a one-dimensional grating structure. The second output region 130 is also divided into two sub-regions. Correspondingly, the sub-region closer to the input region 110 is set with a two-dimensional grating structure, and the other sub-region is set with a one-dimensional grating structure.
[0036] In practice, the first and second coupling regions are divided into three sub-regions in the second direction, with the middle sub-region containing a two-dimensional grating structure and the other two sub-regions containing a one-dimensional grating structure.
[0037] For example, refer to Figure 2 The first coupling region 120 is divided into three sub-regions. In these three sub-regions, the middle sub-region is configured with a two-dimensional grating structure, and the other two sub-regions are configured with one-dimensional grating structures. The second coupling region 130 is also divided into three sub-regions. Accordingly, the middle sub-region is configured with a two-dimensional grating structure, and the other two sub-regions are configured with one-dimensional grating structures.
[0038] In practice, the first and second coupling regions can be further divided into more sub-regions, some of which are configured with two-dimensional grating structures, and some with one-dimensional grating structures. The location, size, and area of the region containing the two-dimensional grating structure can be designed according to specific performance requirements.
[0039] Implementable, see reference Figure 1-4 The boundary lines between sub-regions can be straight lines, polylines, curves, or combinations of these types of line segments. Boundary lines can be set parallel or non-parallel.
[0040] In this application, a coupling grating is designed by combining one-dimensional and two-dimensional grating structures. On the one hand, the flexibility of setting two-dimensional grating structures in part of the coupling region to expand the pupil in two dimensions can be utilized to adapt to various custom waveguide shapes currently available on the market. On the other hand, by setting one-dimensional grating structures in part of the coupling region, the complex and diverse rainbow problem caused by using two-dimensional grating structures in the entire coupling region can be avoided, thereby alleviating the rainbow problem.
[0041] Furthermore, to better mitigate the rainbow problem, this application also makes a special design regarding the position of the two-dimensional grating structure within the coupling region. Specifically, in the diffractive waveguide provided by this application, the region containing the two-dimensional grating structure in the first and / or second coupling regions is located between the optical paths of the boundary field rays after they are coupled into the waveguide substrate through the coupling region, in the initial transmission direction. This ensures that the coupling energy of the two-dimensional grating structure is less than the pupil expansion energy of the two-dimensional grating structure, and that the coupling energy of the two-dimensional grating structure is less than the coupling energy of the one-dimensional grating structure.
[0042] It is understandable that, since two-dimensional grating structures have more diffraction orders and directions than one-dimensional grating structures, the rainbow problem produced by two-dimensional grating structures is more complex and diverse than that of one-dimensional grating structures. Because the light rays emitted from the optomechanical system generally have a certain field of view, the propagation direction of the light rays after entering the waveguide substrate varies depending on the field of view. In this application, the region traversed by the light rays is defined by the optical path along the initial propagation direction after the boundary field of view is coupled into the waveguide substrate via the coupling region. Therefore, when designing the position of the two-dimensional grating structure in the coupling region, it can be designed to be located between the optical paths along the initial propagation direction of the light rays from the boundary field of view after coupling into the waveguide substrate via the coupling region. This allows the two-dimensional grating structure to perform more of the pupil-expanding function, while the one-dimensional grating structure performs more of the coupling function. In this way, when the human eye observes the display image, it focuses more on the imaging area of the one-dimensional grating structure, which can reduce the rainbow generated by the two-dimensional grating structure from entering the human eye's field of view to a certain extent, thereby alleviating the rainbow problem.
[0043] For example, refer to Figure 3 As can be seen, the first coupling region 120 is divided into two sub-regions. Within these two sub-regions, a two-dimensional grating structure is set in the sub-region closer to the coupling region 110, and a one-dimensional grating structure is set in the other sub-region. The second coupling region 130 is also divided into two sub-regions; correspondingly, a two-dimensional grating structure is set in the sub-region closer to the coupling region 110, and a one-dimensional grating structure is set in the other sub-region. The optical path of the boundary field-of-view rays after coupling into the waveguide substrate through the coupling region in the initial propagation direction is shown by the red dashed lines. It can be seen that the area where the two-dimensional grating structure is located is between the two red dashed lines.
[0044] For example, refer to Figure 4As can be seen, the first coupling region 120 is divided into three sub-regions. Within these three sub-regions, a two-dimensional grating structure is set in the middle sub-region, while the other two sub-regions are set into one-dimensional grating structures. The second coupling region 130 is also divided into three sub-regions; correspondingly, a two-dimensional grating structure is set in the middle sub-region, while the other two sub-regions are set into one-dimensional grating structures. The optical path of the boundary field-of-view rays after coupling into the waveguide substrate through the coupling region is shown by the red dashed lines. It can be seen that the area containing the two-dimensional grating structure is between the two red dashed lines.
[0045] In practice, the ratio of the coupling energy to the pupil dilation energy of the two-dimensional grating structure is less than 1 / 3, and the ratio of the coupling energy of the two-dimensional grating structure to the coupling energy of the one-dimensional grating structure is less than 1 / 3.
[0046] Implementably, the area containing the two-dimensional grating structure in the first and / or second coupling regions has a size ranging from 3 to 6 mm in the second direction.
[0047] In practice, the area of the region containing the two-dimensional grating structure in the first coupling region accounts for 1 / 5 to 1 / 3 of the total area of the first coupling region; the area of the region containing the two-dimensional grating structure in the second coupling region accounts for 1 / 5 to 1 / 3 of the total area of the second coupling region.
[0048] All of these implementation methods can, to a certain extent, allow the two-dimensional grating structure to perform more of the pupil expansion function and the one-dimensional grating structure to perform more of the coupling function, thereby alleviating the rainbow problem.
[0049] In practice, the distance between the center of the first eliminating region and the center of the eliminating region in the first direction ranges from 28 to 34 mm. Generally, the distance between the center of the first eliminating region and the center of the second eliminating region in the first direction is adapted to the human interpupillary distance. When the first eliminating region and the second eliminating region are mirror-symmetrical about the eliminating region, the distance between the center of the first eliminating region and the center of the eliminating region in the first direction is approximately half the interpupillary distance. It is understood that different people have different interpupillary distances, so a suitable range should be selected.
[0050] In practice, the distance between the center of the first coupling region and the center of the coupling region in the second direction is 5-10 mm.
[0051] In practice, both the first and second coupling regions are polygons.
[0052] For example, the first and second coupling regions can be quadrilaterals. (See reference...) Figures 1-6The first coupling region 120 and the second coupling region 130 are right trapezoids. The size of these two coupling regions in the first direction gradually decreases as they move away from the coupling region 110. This part of the region with the change in size is the pre-dilation pupil region of the coupling, which is beneficial to improving the coupling uniformity of the coupling region.
[0053] In some embodiments, the first and second coupling regions are mirror-symmetrical about the coupling region. In symmetrical design scenarios, this reduces computational overhead, improves efficiency, and shortens the development cycle. Alternatively, in another embodiment, the coupling region can be positioned close to either the first or second coupling region. The line connecting the centers of the first and second coupling regions is generally horizontal to avoid differences between the images for the left and right eyes.
[0054] Further implementably, the coupling grating structure within the coupling region is mirror-symmetrical about the central axis of the coupling region. Specifically, the coupling grating structure within the coupling region can adopt a symmetrical toothed structure, such as a straight toothed structure or an isosceles trapezoidal structure. In this case, of the diffracted light propagating towards the first coupling region and the diffracted light propagating towards the second coupling region, one is a -1st order diffracted light and the other is a +1st order diffracted light. The diffraction characteristics of the symmetrical toothed grating structure are such that the ±1st order diffraction efficiencies are equal, which helps to ensure the consistency of the display effect for the left and right eyes. Moreover, this embodiment utilizes the ±1st order diffraction of the coupling grating structure, effectively improving the light energy utilization rate.
[0055] Alternatively, the coupling grating structure can be a one-dimensional grating structure, including a first coupling grating and a second coupling grating with different grating vector directions.
[0056] Specifically, the coupling grating in the coupling region adopts a one-dimensional grating with two grating vectors forming an angle. At this time, the grating structure can be an asymmetric structure such as a blazed grating or a helical tooth grating. It can achieve high coupling efficiency while increasing the waveguide shape freedom because the relative position of the grating can be selected more often.
[0057] Implementably, the dimensions of the first coupling region and / or the second coupling region in the first direction range from 20 to 24 mm; and / or the dimensions of the first coupling region and / or the second coupling region in the second direction range from 14 to 16 mm.
[0058] In addition, embodiments of this application also provide a near-eye display device, including a diffractive waveguide and an optomechanic as described in any of the foregoing.
[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.
Claims
1. A diffractive optical waveguide, characterized in that, The diffractive waveguide includes a waveguide substrate, which includes at least an insertion region, a first output region, and a second output region. The first output region and the second output region are respectively used to correspond to the left and right eyes of a human eye. The first output region, the insertion region, and the second output region are arranged sequentially in a first direction. The first output region and the second output region are divided into at least two sub-regions in a second direction. One of the sub-regions of the first output region and the second output region is a two-dimensional grating structure, and the sub-region farthest from the insertion region is a one-dimensional grating structure. The first direction is orthogonal to the second direction.
2. The diffractive waveguide according to claim 1, characterized in that, The first coupling region and the second coupling region are divided into three sub-regions in the second direction. The middle sub-region has a two-dimensional grating structure, and the other two sub-regions have a one-dimensional grating structure.
3. The diffractive waveguide according to claim 2, characterized in that, The regions where the two-dimensional grating structures are located in the first and / or the second coupling regions are situated between the optical paths of the boundary field rays after they are coupled into the waveguide substrate through the coupling region, in the initial transmission direction, so that the coupling energy of the two-dimensional grating structure is less than the pupil expansion energy of the two-dimensional grating structure, and the coupling energy of the two-dimensional grating structure is less than the coupling energy of the one-dimensional grating structure.
4. The diffractive waveguide according to claim 3, characterized in that, The ratio of the coupling energy of the two-dimensional grating structure to the pupil dilation energy is less than 1 / 3, and the ratio of the coupling energy of the two-dimensional grating structure to the coupling energy of the one-dimensional grating structure is less than 1 / 3.
5. The diffractive waveguide according to claim 3, characterized in that, The size of the area containing the two-dimensional grating structure in the first and / or second coupling regions in the second direction ranges from 3 to 6 mm.
6. The diffractive waveguide according to claim 3, characterized in that, The area of the region containing the two-dimensional grating structure in the first coupling region accounts for 1 / 5 to 1 / 3 of the total area of the first coupling region; the area of the region containing the two-dimensional grating structure in the second coupling region accounts for 1 / 5 to 1 / 3 of the total area of the second coupling region.
7. The diffractive waveguide according to claim 1, characterized in that, The size of the first coupling region and / or the second coupling region in the first direction ranges from 20 to 24 mm; and / or the size of the first coupling region and / or the second coupling region in the second direction ranges from 14 to 16 mm.
8. The diffractive waveguide according to claim 1, characterized in that, The distance between the center of the first coupling region and the center of the coupling region in the first direction is 28-34 mm; and / or, the distance between the center of the first coupling region and the center of the coupling region in the second direction is 5-10 mm.
9. The diffractive waveguide according to claim 1, characterized in that, The grating structure within the coupling region is symmetrical about the central axis of the coupling region in the second direction; both the first and second coupling regions are polygons.
10. A near-eye display device, characterized in that, The near-eye display device includes a diffractive waveguide and an optomechanic as described in any one of claims 1-9.