An optical waveguide and waveguide display device

Abstract

The utility model discloses an optical waveguide, optical waveguide includes: optical waveguide main part, entrance pupil grating, pupil dilatation grating and exit pupil grating, optical waveguide main part includes entrance pupil area, pupil dilatation area and exit pupil area, and entrance pupil area and pupil dilatation area are interval setting, pupil dilatation grating sets up in pupil dilatation area, exit pupil grating sets up in exit pupil area, entrance pupil grating sets up in entrance pupil area, and entrance pupil grating is used for coupling into the light ray in optical waveguide main part and carries out total reflection conduction and passes through exit pupil grating and couples out, pupil dilatation grating sets up in one side of optical waveguide main part, and exit pupil grating sets up in the other side of optical waveguide main part, and the projection area of pupil dilatation grating to the projection area of optical waveguide main part of exit pupil grating at least partial overlap. Thus, pupil dilatation grating and exit pupil grating overlap design in common area, make the light ray complete pupil dilatation and exit pupil coupling out operation in the propagation path simultaneously, thereby compress the volume of optical waveguide system, improve light efficiency utilization rate, and then improve the display quality of image.

Description

Technical Field

[0001] This utility model relates to the field of enhanced display technology, and in particular to an optical waveguide. Background Technology

[0002] Augmented Reality (AR) display systems have received widespread attention in recent years as an important carrier of next-generation human-computer interaction. Among them, AR display solutions based on diffraction waveguides have become one of the mainstream AR optical architectures due to their advantages such as compact structure, large field of view, and high transparency.

[0003] In diffractive waveguide systems, light output from a microdisplay is typically coupled into the waveguide using an input grating, then expanded using an exit pupil expander to cover a wider field of view, and finally coupled out using an exit pupil expander for human observation. The exit pupil expander and exit pupil expander are key factors affecting the uniformity of the emitted light and image quality.

[0004] However, in existing technologies, the pupil dilator grating and exit pupil grating are mostly arranged in separate regions, that is, two grating functional modules are set in different spatial regions. Although this structure is relatively simple in manufacturing process, the uneven concentration of light flux in the exit pupil region after pupil dilation can easily cause uneven brightness distribution in the field of view, with some areas being too bright or too dark, resulting in uneven light energy distribution and diffraction path interference, which affects the final image quality. Therefore, it is urgent to improve this technology. Utility Model Content

[0005] The main purpose of this invention is to propose an optical waveguide that solves the problems of uneven light energy distribution and low imaging quality in related technologies.

[0006] To achieve the above objectives, this utility model proposes an optical waveguide, which includes: An optical waveguide body, the optical waveguide body including an entrance pupil region, a dilation pupil region and an exit pupil region, the entrance pupil region and the dilation pupil region being arranged at intervals; A pupil-expanding grating is disposed within the pupil-expanding area; An exit pupil grating is disposed within the exit pupil area; An entrance pupil grating is disposed in the entrance pupil region. The entrance pupil grating is used to couple light into the optical waveguide body for total internal reflection and conduction, and then couple it out through the exit pupil grating. The pupil grating is disposed on one side of the optical waveguide body, and the exit pupil grating is disposed on the other side of the optical waveguide body. The projection area of ​​the pupil grating onto the optical waveguide body overlaps at least partially with the projection area of ​​the exit pupil grating onto the optical waveguide body. The difference between the maximum duty cycle and the minimum duty cycle of the exit pupil grating in the exit pupil area is greater than or equal to 10%.

[0007] In some embodiments, the projection area of ​​the pupil grating onto the optical waveguide body covers the projection area of ​​the exit pupil grating onto the optical waveguide body.

[0008] In some embodiments, the duty cycle range consisting of the maximum and minimum duty cycles of the exit pupil grating in the exit pupil region is any range between [0%, 100%].

[0009] In some embodiments, the duty cycle of the exit pupil grating gradually changes in the exit pupil region.

[0010] In some embodiments, the gradual change direction of the duty cycle of the exit pupil grating is opposite to the optical path propagation direction in the optical waveguide body.

[0011] In some embodiments, the gradual change is one of a linear change, a nonlinear change, or a piecewise change.

[0012] In some embodiments, the exit pupil grating is one of a surface relief grating, a phase grating, an amplitude grating, or a holographic grating.

[0013] In some embodiments, the material of the optical waveguide body includes one of optical plastic and glass.

[0014] This utility model also provides a waveguide display device, which includes a device body and an optical waveguide as described above, wherein the optical waveguide is mounted on the device body.

[0015] The beneficial effects of this utility model's technical solution are as follows: This invention relates to an optical waveguide with a pupil expansion region on one side of the main body and an exit pupil region on the other side. The projection area of ​​the pupil expansion grating onto the main body overlaps at least partially with the projection area of ​​the exit pupil grating. This overlapping design allows light to synchronously complete pupil expansion and exit pupil coupling operations in the propagation path, thereby reducing the volume of the optical waveguide system and improving light efficiency. Furthermore, the difference between the maximum and minimum duty cycles of the exit pupil grating in the exit pupil region is greater than or equal to 10%, which makes the energy distribution of the output image more uniform, thus improving the display quality of the image. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of an embodiment of the optical waveguide of this utility model; Figure 2 for Figure 1 Side view of the pupil dilation area and pupil exit area; Figure 3 This is a schematic diagram of another embodiment of the optical waveguide of this utility model; Figure 4 for Figure 2 A side view of the pupil dilation area and the pupil exit area.

[0017] Explanation of icon numbers: 100, Optical waveguide body; 200, Entrance pupil region; 210, Entrance pupil grating; 300, Dilated pupil region; 310, Dilated pupil grating; 400, Exit pupil region; 410, Exit pupil grating. Detailed Implementation

[0018] The solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this utility model. In addition, the descriptions involving "first," "second," etc., in this utility model are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0019] To address the technical deficiencies in related technologies, this utility model provides an optical waveguide. Please refer to [link / reference]. Figure 1 and Figure 2 The optical waveguide includes: an optical waveguide body 100, a pupil dilator grating 310, an exit pupil grating 410, and an entrance pupil grating. The optical waveguide body 100 includes an entrance pupil region 200, a pupil dilator region 300, and an exit pupil region 400, wherein the entrance pupil region 200 and the pupil dilator region 300 are spaced apart; the pupil dilator grating 310 is disposed within the pupil dilator region 300; the exit pupil grating 410 is disposed within the exit pupil region 400; and the entrance pupil grating 210 is disposed within the entrance pupil region 400. 200, the entrance pupil grating 210 is used to couple light into the optical waveguide body 100 for total internal reflection and conduction and couple out through the exit pupil grating 410; wherein, the expanding pupil grating 310 is disposed on one side of the optical waveguide body 100, the exit pupil grating 410 is disposed on the other side of the optical waveguide body 100, and the projection area of ​​the expanding pupil grating 310 onto the optical waveguide body 100 at least partially overlaps with the projection area of ​​the exit pupil grating 410 onto the optical waveguide body 100.

[0020] Compared to the layout limitation of traditional designs where the two functional areas must be physically separated, in this embodiment, the projection areas of the exit pupil area 400 and the expansion pupil area 300 at least partially overlap. The design of functional area reuse can greatly save space on the optical waveguide body 100, enabling greater optical functions to be achieved on the same waveguide area, or laying a solid foundation for realizing thinner and smaller AR devices (such as glasses).

[0021] By integrating the pupil grating 310 and the exit pupil grating 410 into the same area and designing them as a single unit, such as by adopting collaborative strategies such as different periods and diffraction order separation, compared with two separate grating modules, the unnecessary diffraction and stray light caused by multiple optical path reversals and intersections can be reduced, which helps to improve the contrast and sharpness of the final image.

[0022] Furthermore, in this embodiment, the difference between the maximum and minimum duty cycles of the exit pupil grating 410 in the exit pupil region 400 is greater than or equal to 10%. Duty cycle refers to the ratio of the width of the exit pupil grating 410 to the width of the entire grating period. A duty cycle variation of less than 10% may result in a very slight change in diffraction efficiency, making it difficult to compensate for the significant spatial attenuation of optical energy in a real optical waveguide. A difference greater than or equal to 10% limits the modulation range; a difference between the maximum and minimum duty cycles greater than or equal to 10% allows for a more uniform energy distribution in the output image.

[0023] Through the above technical solution, the optical waveguide of this utility model sets an enlarged pupil region 300 on one side of the optical waveguide body 100 and an exit pupil region 400 on the other side of the optical waveguide body 100. The projection area of ​​the enlarged pupil grating 310 onto the optical waveguide body 100 and the projection area of ​​the exit pupil grating 410 onto the optical waveguide body 100 overlap at least partially. This co-overlapping design of the enlarged pupil grating 310 and the exit pupil grating 410 allows light to simultaneously complete the enlarged pupil and exit pupil coupling operations in the propagation path, thereby compressing the volume of the optical waveguide system and improving the light efficiency. Furthermore, the difference between the maximum and minimum duty cycles of the exit pupil grating in the exit pupil region is greater than or equal to 10%, which makes the energy distribution of the output image more uniform, thereby improving the display quality of the image.

[0024] In some embodiments, the projection area of ​​the pupil grating 310 onto the optical waveguide body 100 covers the projection area of ​​the exit pupil grating 410 onto the optical waveguide body 100. With this configuration, the entire working area of ​​the exit pupil grating 410 is within the pupil light field, enabling the exit pupil grating 410 to continuously and without blind spots perform its energy distribution function throughout the entire exit pupil region 400, laying the foundation for achieving perfect brightness uniformity.

[0025] In some embodiments, the duty cycle range of the exit pupil grating 410 in the exit pupil region 400, consisting of the maximum and minimum duty cycles, is any range between [0%, 100%]. A change in duty cycle from 0% to 100% means that the diffraction efficiency can be adjusted from almost zero to near its maximum value. This allows users to select the most effective duty cycle control range for different waveguide materials and different system optical path architectures; for example, it could be [0%, 60%], [40%, 60%], or any other range between [0%, 100%] to achieve optimal brightness uniformity, making it a highly versatile solution.

[0026] In this embodiment, the duty cycle of the exit pupil grating 410 gradually varies within the exit pupil region 400. By setting the exit pupil grating 410 and the expanding pupil grating 310 in a shared area and employing a gradually changing duty cycle design, precise spatial control of the emitted light energy is achieved. In traditional segmented designs, light naturally attenuates due to varying path lengths as it propagates within the waveguide, resulting in uneven emitted light energy. The structure of the exit pupil grating 410 with a gradually changing duty cycle within the exit pupil region 400 serves as a built-in compensation mechanism. This reduces the diffraction efficiency of the grating in areas with higher energy and increases it in areas with lower energy, thereby ensuring that the human eye receives a highly uniform image of brightness throughout the entire exit pupil range, significantly improving the visual experience.

[0027] In other embodiments, please refer to Figure 3 and Figure 4 The direction of the gradual change in duty cycle of the exit pupil grating 410 is opposite to the direction of optical path propagation in the optical waveguide body 100. This embodiment provides another optical design possibility to meet different optomechanical engine layouts and product design requirements, demonstrating the versatility and adaptability of the optical waveguide of this invention.

[0028] In some embodiments, the gradual change is one of a linear change, a nonlinear change, or a piecewise change.

[0029] In this embodiment, multiple functional relationships for energy compensation are provided, giving the design greater freedom. The gradual change of the exit pupil grating 410 can be one of linear, nonlinear, or piecewise changes.

[0030] Among them, the duty cycle of the exit pupil grating 410 changes linearly relative to the expanding pupil grating 310 (e.g., 60%-50%-40%-30%...), which is easy to design and manufacture and can meet most uniformity compensation requirements. When the duty cycle of the exit pupil grating 410 changes non-linearly (e.g., 60%-55%-45%-30%-10%...), it can more accurately match the complex energy attenuation curve in the optical waveguide and achieve more extreme uniformity optimization. When the duty cycle of the exit pupil grating 410 changes in a piecewise manner (e.g., 60%-60%-50%-50%-40%-40%...), different change rates can be used in different segments, which provides the possibility of dealing with specific optical problems or realizing customized brightness distribution.

[0031] In this embodiment, the exit pupil grating 410 can be implemented using one of the following methods: surface relief grating, phase grating, amplitude grating, or holographic grating. Surface relief gratings are based on mature micro / nano fabrication processes (such as nanoimprinting, electron beam lithography, and ion etching), and their key parameters (period, duty cycle, groove depth, and contour shape) can be precisely controlled, offering advantages such as mature technology and high design and fabrication flexibility. Phase gratings have high diffraction efficiency and no energy absorption loss. Amplitude gratings have relatively simple fabrication processes. Holographic gratings can achieve complex optical functions and are easily fabricated into thin films. This means that users can choose the most suitable technology path to implement the optical waveguide based on their own technological foundation, cost budget, and performance requirements.

[0032] In some embodiments, the material of the optical waveguide body 100 includes optical plastic and glass. The specific material used for the optical waveguide body 100 can be set according to requirements.

[0033] This utility model also provides a waveguide display device, which includes a device body and an optical waveguide, with the optical waveguide mounted on the device body. This waveguide display device can be used in: AR glasses or head-mounted displays (HMDs), automotive head-up display systems (HUDs), industrial and medical AR-assisted vision systems, and transparent display terminal devices in education, cultural tourism, military, and other fields.

[0034] It should be noted that the specific structure of the optical waveguide is as described in the above embodiments. Since the waveguide display device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0035] The above description is only a part or preferred embodiment of this utility model. Neither the text nor the drawings should limit the scope of protection of this utility model. All equivalent structural transformations made using the content of this utility model specification and drawings under the overall concept of this utility model, or direct / indirect applications in other related technical fields, are included within the scope of protection of this utility model.

Claims

1. An optical waveguide, characterized by, The optical waveguide includes: An optical waveguide body (100) includes an entrance pupil region (200), a dilation pupil region (300), and an exit pupil region (400), wherein the entrance pupil region (200) and the dilation pupil region (300) are spaced apart. A pupil dilation grating (310) is disposed within the pupil dilation area (300); An exit pupil grating (410) is disposed within the exit pupil region (400); An entrance pupil grating (210) is disposed in the entrance pupil region (200). The entrance pupil grating (210) is used to couple light into the optical waveguide body (100) for total internal reflection and conduction, and couple it out through the exit pupil grating (410). The pupil grating (310) is disposed on one side of the optical waveguide body (100), and the exit pupil grating (410) is disposed on the other side of the optical waveguide body (100). The projection area of ​​the pupil grating (310) onto the optical waveguide body (100) and the projection area of ​​the exit pupil grating (410) onto the optical waveguide body (100) overlap at least partially. The difference between the maximum duty cycle and the minimum duty cycle of the exit pupil grating (410) in the exit pupil region (400) is greater than or equal to 10%.

2. The optical waveguide of claim 1, wherein, The projection area of ​​the pupil grating (310) onto the optical waveguide body (100) covers the projection area of ​​the exit pupil grating (410) onto the optical waveguide body (100).

3. The optical waveguide according to claim 1 or 2, characterized in that, The duty cycle range of the maximum and minimum duty cycles of the exit pupil grating (410) in the exit pupil region (400) is any range between [0%, 100%].

4. The optical waveguide of claim 3, wherein, The duty cycle of the exit pupil grating (410) gradually changes in the exit pupil region (400).

5. The optical waveguide of claim 3, wherein, The gradual change direction of the duty cycle of the exit pupil grating (410) is opposite to the optical path propagation direction in the optical waveguide body (100).

6. The optical waveguide of claim 4, wherein, The gradual change can be one of the following: linear change, nonlinear change, or piecewise change.

7. The optical waveguide of claim 1, wherein, The exit pupil grating (410) is one of the following: surface relief grating, phase grating, amplitude grating or holographic grating.

8. The optical waveguide of claim 1, wherein, The material of the optical waveguide body (100) includes one of optical plastic and glass.

9. A waveguide display device, comprising: The waveguide display device includes a device body and an optical waveguide according to any one of claims 1 to 8, wherein the optical waveguide is mounted on the device body.

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