Optical waveguide and augmented reality device

Abstract

The application discloses an optical waveguide and an augmented reality device. The optical waveguide is used for conducting image light. The optical waveguide is provided with a coupling-in region, a first turning region and a coupling-out region. First sub-light rays in the image light are directly conducted to the coupling-out region for pupil expansion and coupling-out after being coupled in through the coupling-in region. The first sub-light rays form a plurality of first pupil expansion light spots in the coupling-out region. Second sub-light rays in the image light are conducted to the coupling-out region for pupil expansion and coupling-out after being coupled in through the coupling-in region and passing through the first turning region. The second sub-light rays form a plurality of second pupil expansion light spots in the coupling-out region. The plurality of second pupil expansion light spots and the plurality of first pupil expansion light spots are staggered, which can further improve the uniformity of the image brightness after pupil expansion, so as to ensure the display effect of the augmented reality device provided with the optical waveguide.

Description

Technical Field

[0001] This application relates to the field of augmented reality technology, and more specifically, to an optical waveguide and an augmented reality device. Background Technology

[0002] Augmented Reality (AR) devices are devices that blend virtual information with the real world. Using hardware components such as cameras, sensors, and displays, they precisely overlay virtual elements such as images, videos, and 3D models generated by processors onto the real scene in the user's field of vision, thereby creating a more immersive augmented reality experience that blends the virtual and the real.

[0003] However, existing AR devices suffer from a small exit pupil size in their optical engines. In this case, after the optical waveguide replicates and expands the exit pupil of the optical engine, there are large gaps between adjacent replicated light spots, resulting in poor uniformity of image brightness after pupil expansion, which in turn affects the user's viewing experience. Utility Model Content

[0004] This application provides an optical waveguide and an augmented reality device to improve the brightness uniformity of the emitted light from the optical waveguide.

[0005] According to a first aspect of this application, an embodiment of this application provides an optical waveguide for transmitting image light rays. The optical waveguide includes an insertion region, a first deflection region, and an exit region. A first sub-ray ray in the image light ray is coupled into the insertion region, then directly transmitted to the exit region for pupil dilation and exit; wherein the first sub-ray ray forms multiple first pupil dilation spots in the exit region. A second sub-ray ray in the image light ray is coupled into the insertion region, then transmitted through the first deflection region to the exit region for pupil dilation and exit; wherein the second sub-ray ray forms multiple second pupil dilation spots in the exit region, and the multiple second pupil dilation spots and multiple first pupil dilation spots are arranged alternately.

[0006] In some possible embodiments, the propagation step size of the first sub-ray and the propagation step size of the second sub-ray from the first deflection region to the coupling region are different; wherein, the propagation step size refers to the distance between the two light spots formed on the same waveguide surface after the sub-ray undergoes two total internal reflections in the optical waveguide.

[0007] In some possible embodiments, the center of the second pupil dilation spot does not coincide with the center of the first pupil dilation spot.

[0008] In some possible embodiments, the optical waveguide includes a first coupling grating disposed in the coupling region and a first coupling grating disposed in the coupling region. The image light rays are diffracted by the first coupling grating to form a first sub-ray and a second sub-ray respectively, and the first sub-ray and the second sub-ray have different propagation directions in the optical waveguide; wherein the first coupling grating and the first coupling grating are both two-dimensional gratings.

[0009] In some possible embodiments, the optical waveguide is further provided with a second deflection region. After the image light is diffracted by the first coupling grating, it forms a third sub-ray. The propagation directions of the first sub-ray, the second sub-ray, and the third sub-ray in the optical waveguide are different. The third sub-ray is conducted through the second deflection region to the coupling region for pupil expansion and coupling out. The third sub-ray forms multiple third pupil-expanding spots in the coupling region. The multiple third pupil-expanding spots, multiple second pupil-expanding spots, and multiple first pupil-expanding spots are arranged alternately.

[0010] In some possible embodiments, the optical waveguide includes a waveguide substrate having a first surface and a second surface facing away from each other. The waveguide also includes a second and a third coupling grating disposed in the coupling region, and a second and a third coupling grating disposed in the coupling region. The projection of the second coupling grating onto the thickness direction of the waveguide substrate coincides with the projection of the third coupling grating onto the thickness direction of the waveguide substrate, and the projection of the second and third coupling grating onto the thickness direction of the waveguide substrate also coincides with the projection of the third coupling grating. The second and second coupling gratings are disposed on the first surface, and the third coupling grating is disposed on the second surface. Image rays are diffracted sequentially through the second and third coupling gratings to form a first sub-ray, and the image rays are diffracted through the second coupling grating to form a second sub-ray. The second, third, second, and third coupling gratings are all one-dimensional gratings.

[0011] In some possible embodiments, the optical waveguide is further provided with a second deflection region. After the image light is diffracted by the third coupling grating, it forms a third sub-ray. The third sub-ray is transmitted through the second deflection region to the coupling out region for pupil expansion and coupling out. The propagation directions of the first sub-ray, the second sub-ray, and the third sub-ray in the optical waveguide are different. During the coupling process of the second and third sub-rays into the optical waveguide, the third coupling grating does not diffract the second sub-ray, and the second coupling grating does not diffract the third sub-ray.

[0012] In some possible embodiments, the optical waveguide includes a waveguide substrate having a first surface and a second surface facing away from each other. The waveguide also includes a fourth and a fifth coupling grating disposed in the coupling region, a first folding grating disposed in the first folding region, and a fourth and a fifth coupling grating disposed in the coupling region. The projection of the fourth coupling grating onto the thickness direction of the waveguide substrate coincides with that of the fifth coupling grating, and the projection of the fourth coupling grating onto the thickness direction of the waveguide substrate coincides with that of the fifth coupling grating. The fourth coupling grating, the first folding grating, and the fourth coupling grating are disposed on the first surface, and the sum of their grating vectors is 0. The fifth coupling grating and the fifth coupling grating are disposed on the second surface, and their grating orientation and grating period are the same.

[0013] According to a second aspect of this application, an embodiment of this application provides an augmented reality device, which includes an optical engine module and the aforementioned optical waveguide. The optical engine module is used to generate image light rays, and the exit pupil size of the optical engine module is less than or equal to 1 mm. The optical waveguide is used to conduct image light rays, and the image light rays coupled out through the optical waveguide are incident on the user's eye area.

[0014] In some possible embodiments, the optomechanical module includes a laser and a microelectromechanical system (MEMS) mirror; wherein the laser is used to generate laser light; and the MEMS mirror is used to reflect the laser light to form image rays; or, the optomechanical module includes an optical modulation chip, which is used to form image rays; wherein the optical modulation chip is a silicon-based liquid crystal chip or a digital micromirror chip.

[0015] This application provides an optical waveguide and an augmented reality device. The optical waveguide has an insertion region, a first deflection region, and an exit region. A first sub-ray in the image light is coupled into the insertion region, then directly transmitted to the exit region for pupil dilation and exit. A second sub-ray in the image light is coupled into the insertion region, then transmitted through the first deflection region to the exit region for pupil dilation and exit.

[0016] Therefore, after the image light rays are coupled into the optical waveguide, there are at least two propagation paths. The light rays on one propagation path (i.e., the first sub-ray) will be directly transmitted to the coupling region, and the light rays on the other propagation path (i.e., the second sub-ray) will be transmitted to the first turning region, where one-dimensional pupil expansion and turning are achieved before being transmitted to the coupling region.

[0017] Furthermore, when the first sub-ray and the second sub-ray are expanded and coupled out in the coupling region, the multiple first expanded pupil spots and multiple second expanded pupil spots formed in the coupling region are staggered. That is, the multiple first expanded pupil spots can fill the gaps between the multiple second expanded pupil spots, and the multiple second expanded pupil spots can also fill the gaps between the multiple first expanded pupil spots, thereby improving the uniformity of the image brightness after pupil expansion, so as to ensure the display effect of the augmented reality device equipped with the optical waveguide. Attached Figure Description

[0018] 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.

[0019] Figure 1 This is a schematic diagram of the augmented reality device provided in the embodiments of this application.

[0020] Figure 2 yes Figure 1 The diagram shows a schematic of the optical path structure of an augmented reality device.

[0021] Figure 3 yes Figure 2 The diagram shows a structural schematic of an optical waveguide in an augmented reality device.

[0022] Figure 4 These are simulation effect diagrams provided in the embodiments of this application.

[0023] Figure 5 yes Figure 2 The diagram shows another structural schematic of the optical waveguide in the augmented reality device.

[0024] Figure 6 yes Figure 5 The K-vector circle diagram of the optical waveguide is shown.

[0025] Figure 7 yes Figure 2 The diagram shows another structural schematic of an optical waveguide in an augmented reality device.

[0026] Figure 8 yes Figure 2 The diagram shows another structural schematic of an optical waveguide in an augmented reality device.

[0027] Labeling Explanation: 100, Augmented Reality Device; L, Image Ray; L1, First Sub-ray; L2, Second Sub-ray; K1, First Pupil Dip; K2, Second Pupil Dip; 20, Optomechanical Module; 210, Laser; 230, Collimating Lens; 250, Microelectromechanical System Mirror; 300, Optical Waveguide; 301, First Surface; 303, Second Surface; 302, Coupling Region; 304, First Folding Region; 306 308. Second folded region; 310. First input grating; 320. First output grating; 330. First folded grating; 340. Second folded grating; 350. Second input grating; 352. Third input grating; 360. Second output grating; 362. Third output grating; 370. Fourth input grating; 372. Fifth input grating; 380. Fourth output grating; 382. Fifth output grating. Detailed Implementation

[0028] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative effort are within the scope of protection of the present application.

[0029] In related technologies, when laser beam scanning (LBS) technology is used in the optical engine of AR devices, the spot size of the emitted beam is relatively small due to the size limitations of the reflectors. When paired with a large field of view and a high refractive index optical waveguide, the total internal reflection angle of the emitted beam varies depending on the field of view as it enters the waveguide through the coupling grating. Specifically, with a large field of view, the total internal reflection angle within the waveguide is also large. This results in an excessively long interval between two adjacent light spots after pupil dilation. Consequently, when the light exits from the coupling grating, it exceeds the receiving range of the human pupil, and the image information it carries cannot be received by the human eye. This leads to a discontinuous image captured by the human eye, exhibiting obvious bright and dark stripes.

[0030] To address the aforementioned technical issues, related technologies utilize additional relay lenses to enlarge the scanning spot size, thus mitigating the pupil discontinuity problem in LBS optical engines. However, this approach has obvious drawbacks: while enlarging the spot size, the relay lens also proportionally reduces the scanning angle of the reflecting mirror, resulting in a smaller field of view for the image source. Furthermore, the lens group introduced by the relay lens significantly increases the overall size of the optical engine.

[0031] Furthermore, related technology CN220357269U also provides a solution to alleviate the pupil expansion discontinuity problem of LBS optical engines. It divides the coupling region of the optical waveguide into two discrete coupling sub-regions and propagates light from different coupling sub-regions to different turning regions to achieve multiple different light outputs. However, this solution has the following drawbacks: it requires dividing the coupling region into two areas, resulting in a halving of the light spot size in the coupling sub-regions, thus worsening the pupil expansion density.

[0032] Based on this, this application proposes a novel optical waveguide architecture. Compared to solutions that require additional relay lenses, this application only changes the structure of the optical waveguide itself, thus solving the pupil discontinuity problem of the optical mechanism without the need for relay lenses, enabling miniaturized design of the optical mechanism. Compared to the technical solution in CN220357269U, this application does not require dividing the coupling region into two separate coupling sub-regions, and the spot size of the coupled optical waveguide is not halved, ensuring that the pupil density of the optical waveguide is not degraded.

[0033] Please see Figure 1 This application provides an augmented reality device 100, which is a device capable of combining virtual information with the real world. It uses computer technology, sensors, display devices, and other means to overlay virtual images, text, audio, and other information onto the real scene seen by the user in real time, thereby enhancing the user's perception and interaction with the real world. Specifically, the augmented reality device 100 can be AR glasses, AR headsets, AR helmets, etc. In the following description, AR glasses are used as an example of the augmented reality device 100.

[0034] Please see Figure 2 The augmented reality device 100 may include an optical engine module 20 and an optical waveguide 300. The optical engine module 20 generates image rays L, which are rays carrying image information. The optical waveguide 300 is located on the optical path of the image rays L and is used to conduct the image rays L. Specifically, in this embodiment, the optical waveguide 300 can serve as the eyeglass waveguide in AR glasses, and the light coupled out of it can enter the user's pupil area, allowing the user to see the image information generated by the AR glasses. That is, when the image rays L enter the user's eyes, the user can see the real world superimposed with image information through the augmented reality device 100, thereby creating an augmented reality experience that blends the virtual and real worlds.

[0035] Specifically, the exit pupil size of the optical engine module 20 is less than or equal to 1 mm. For example, the exit pupil size of the optical engine module 20 can be 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 1 mm, etc. Therefore, this embodiment uses an optical engine module 20 with a small exit pupil size, which can reduce the overall size of the optical engine module 20 and facilitate the miniaturization design of the augmented reality device 100, thereby improving the user's wearing comfort.

[0036] As an example, the optomechanical module 20 can be a laser beam scanning (LBS) optomechanical system, which has advantages such as small size, high contrast, wide color gamut, and low power consumption. Figure 2 In the illustrated embodiment, the optomechanical module 20 may include a laser 210 and a microelectromechanical system (MEMS) mirror 250. The laser 210 is used to generate laser light. Specifically, the laser light can be monochromatic light or a mixture of RGB three-color laser light in the time domain. Exemplarily, the laser 210 may be an RGB three-color laser, a diode laser, a vertical-cavity surface-emitting laser (VCSEL), an integrated photonic laser, etc., and this embodiment does not impose specific limitations.

[0037] The microelectro-mechanical system (MEMS) mirror 250 is used to reflect laser light to form image rays L. Specifically, the MEMS mirror 250 can precisely deflect the laser light by tilting the mirror surface to form image rays L.

[0038] The deflection control of the microelectromechanical system (MEMS) mirror 250 is achieved by an electronic control system calculating and controlling the deflection angle and speed of the MEMS mirror 250 based on the information of the image to be displayed. Specifically, by rapidly switching the deflection angle of the mirror, the electronic control system can form multiple pixels on the imaging plane, and these pixels can be combined to form a complete image within the visual persistence time of the human eye. For example, the MEMS mirror 250 can be an electrostatically driven MEMS mirror, a piezoelectrically driven MEMS mirror, an electromagnetically driven MEMS mirror, etc., and this embodiment does not impose a specific limitation.

[0039] exist Figure 2 In the illustrated embodiment, the optomechanical module 20 may further include a collimating lens 230, which is disposed between the laser 210 and the microelectromechanical system (MEMS) mirror 250 and located in the optical path of the laser. Specifically, the collimating lens 230 is used to collimate the laser emitted from the laser 210 before it is incident on the MEMS mirror 250, that is, to adjust the laser emitted from the laser 210 into parallel light.

[0040] On the one hand, the laser can form a smaller, more uniform spot on the microelectromechanical system (MEMS) mirror 250 to improve image resolution and display brightness. On the other hand, optical distortion can be reduced by adjusting the parallelism of the beam, making the image clearer and more accurate. Exemplarily, the collimating lens 230 can be a convex lens, such as a plano-convex lens, biconvex lens, etc. The number of collimating lenses 230 can be one or more, and this embodiment does not specifically limit the number.

[0041] As another example, the optical engine module 20 may be an optical engine including an optical modulation chip (not shown in the figure) used to form image rays L.

[0042] In some possible embodiments, the light modulation chip can be a passively emitting light modulation chip, meaning that the light modulation chip needs to provide an additional light source for illumination. Exemplarily, the light modulation chip can be a Liquid Crystal on Silicon (LCoS) chip or a Digital Micromirror Device (DMD) chip. In other possible embodiments, the light modulation chip can be an actively emitting light modulation chip, such as a micro LED chip; this embodiment is not specifically limited to this.

[0043] In some possible embodiments, the optomechanical module 20 may further include an imaging lens (not shown in the figure). The imaging lens is disposed in the optical path of the image light ray L emitted from the optical modulation chip, and is used to adjust the focal length and field of view of the image light ray L, and optimize optical performance (e.g., reduce distortion, improve contrast and brightness, control dispersion, etc.). Specifically, the imaging lens may include one or more lenses, wherein the lenses may be convex lenses or concave lenses; the lenses may be spherical lenses or aspherical lenses, and this embodiment does not make specific limitations.

[0044] In this embodiment, the optical waveguide 300 is disposed on the optical path of the image light ray L emitted from the optomechanical module 20. It is used to conduct the image light ray L so that it can be smoothly transmitted to the user's pupil area. Please refer to [link to relevant documentation]. Figure 3 The optical waveguide 300 is provided with an insertion region 302, a first deflection region 304, and an exit region 306. The first sub-ray L1 in the image ray L is coupled into the insertion region 302 and then directly transmitted to the exit region 306 for pupil dilation and exit. The first sub-ray L1 forms multiple first pupil-dilated light spots K1 in the exit region 306. "Direct transmission" here means that during the transmission of the first sub-ray L1, it does not pass through the first deflection region 304 or other deflection regions, but undergoes multiple total internal reflections before directly passing through the exit region 306 for pupil dilation and exit.

[0045] The second sub-ray L2 in the image ray L is coupled into the coupling region 302, and then transmitted to the coupling region 306 through the first turning region 304 for pupil dilation and coupling out; wherein, the second sub-ray L2 forms multiple second pupil dilation spots K2 in the coupling region 306, and the multiple second pupil dilation spots K2 and multiple first pupil dilation spots K1 are arranged alternately.

[0046] In some possible embodiments, the plurality of first pupil-expanding spots K1 can be arranged in an M*N array, and the plurality of second pupil-expanding spots K2 can be arranged in an M*N array. The center of at least a portion of the second pupil-expanding spots K2 and the center of at least a portion of the first pupil-expanding spots K1 do not coincide, ensuring that at least a portion of the second pupil-expanding spots K2 and at least a portion of the first pupil-expanding spots K1 are staggered and interleaved, thereby improving the uniformity of the image brightness coupled out at the coupling region 306.

[0047] Therefore, after the image ray L is coupled into the optical waveguide 300, there are at least two propagation paths. The ray on one propagation path (i.e., the first sub-ray L1) will be directly transmitted to the coupling region 306, and the ray on the other propagation path (i.e., the second sub-ray L2) will be transmitted to the first turning region 304, and after one-dimensional pupil expansion and turning in the first turning region 304, it will be transmitted to the coupling region 306.

[0048] Furthermore, when the first sub-ray L1 and the second sub-ray L2 expand their pupils and couple out in the coupling region 306, the multiple first pupil-expanding light spots K1 and multiple second pupil-expanding light spots K2 formed on the coupling region 306 are arranged in an alternating manner. That is, the multiple first pupil-expanding light spots K1 can fill the gaps between the multiple second pupil-expanding light spots K2, and the multiple second pupil-expanding light spots K2 can also fill the gaps between the multiple first pupil-expanding light spots K1, thereby improving the uniformity of the image brightness after pupil expansion, so as to ensure the display effect of the augmented reality device 100 equipped with the optical waveguide 300.

[0049] Please see Figure 4 The diagram shows a simulation of the effect when the pupil diameter d of the image ray L is 0.75 mm. Here, "the pupil diameter of the image ray L" can also be understood as the exit pupil size of the optomechanical module 20.

[0050] exist Figure 4 In region (a), a schematic diagram of the light spot after pupil expansion is replicated via an optical waveguide in an augmented reality device of the relevant technology is shown. It is easy to see that, with a pupil diameter of 0.75 mm, there is a large gap between adjacent replicated light spots, resulting in a relatively sparse distribution of light spots received on the pupil surface of the human eye under a smaller pupil diameter.

[0051] exist Figure 4(b) shows a schematic diagram of the light spot distribution on the pupil surface of the human eye when the pupil diameter d is 0.75 mm. It is easy to see that when the pupil diameter is 0.75 mm, the low saturation of the light spot on the pupil surface will result in uneven brightness distribution in the image perceived by the human eye. For example, it will produce striped defects and the "screen door" effect, thus affecting the user's viewing experience.

[0052] It should be noted that in related technologies, in order to solve the problem that the small pupil diameter of the image ray L leads to poor uniformity of image brightness after pupil expansion, an additional pupil expansion device (e.g., a pupil expansion optical waveguide) is usually set between the optical engine module 20 and the optical waveguide 300. The pupil expansion device is used to expand the exit pupil size of the optical engine module 20 to improve the uniformity of image brightness.

[0053] In this application, no additional pupil-expanding device is needed. By improving the light propagation scheme inside the optical waveguide 300, the problem of discontinuous pupil expansion in small exit pupil optical engines can be alleviated. On the one hand, since no additional pupil-expanding device is required, the hardware cost of the augmented reality device 100 can be reduced, and it is beneficial to achieve a miniaturized design of the augmented reality device 100. On the other hand, the brightness of the light emitted from the optical waveguide 300 in this embodiment is not significantly lost, which can ensure the display effect of the augmented reality device 100 while improving the uniformity of image brightness after pupil expansion.

[0054] The specific implementation of the optical waveguide 300 is described below.

[0055] In this embodiment, the optical waveguide 300 is a glasses optical waveguide, which is disposed in the optical path of the image light L emitted from the optomechanical module 20. The image light L coupled out through the optical waveguide 300 is incident on the user's eye area. That is, when the user wears the augmented reality device 100, the optical waveguide 300 is used to guide the image light L to the user's eye position. Exemplarily, the optical waveguide 300 can be a diffractive optical waveguide, such as a surface relief grating waveguide, a holographic grating waveguide, etc., and this embodiment does not specifically limit it.

[0056] Specifically, when propagating within the optical waveguide 300, the propagation step size of the first sub-ray L1 and the second sub-ray L2 from the first deflection region 304 to the coupling region 306 are different. Since the first sub-ray L1 is directly propagated to the coupling region 306, the "propagation step size of the first sub-ray L1" is the same as the propagation step size of the first sub-ray L1 from the coupling region 302 to the coupling region 306. Here, the propagation step size refers to the distance between the two light spots formed on the same waveguide surface after the sub-ray undergoes two total internal reflections within the optical waveguide 300. Specifically, the light spots can be approximately circular, and the "distance between the two light spots" can be the distance between the centers (centers) of the two light spots. Therefore, when the first sub-ray L1 and the second sub-ray L2 propagate to the coupling region 306, because their propagation step sizes are different, the first dilated pupil light spots K1 and the second dilated pupil light spots K2 formed respectively can be staggered instead of overlapping.

[0057] As an example, please refer again. Figure 3 The optical waveguide 300 may include a first coupling grating 310 disposed in the coupling region 302 and a first coupling grating 320 disposed in the coupling region 306. The image light L is diffracted by the first coupling grating 310 to form a first sub-ray L1 and a second sub-ray L2, respectively, and the first sub-ray L1 and the second sub-ray L2 have different propagation directions in the optical waveguide 300. Both the first coupling grating 310 and the first coupling grating 320 are two-dimensional gratings.

[0058] Specifically, the first coupling grating 320 can be located on the side of the optical waveguide 300 facing the optical-mechanical module 20, or on the side of the optical waveguide 300 away from the optical-mechanical module 20; the first coupling grating 320 can be located on the side of the optical waveguide 300 facing the optical-mechanical module 20, or on the side of the optical waveguide 300 away from the optical-mechanical module 20, and this embodiment does not limit this.

[0059] exist Figure 3 In the illustrated embodiment, the optical waveguide 300 may further include a first folding grating 330 disposed in the first folding region 304. The first folding grating 330 is a one-dimensional grating to achieve one-dimensional pupil expansion and folding of the second sub-ray L2 in one direction. Further, the folded second sub-ray L2 propagates to the coupling region 306, where the first coupling grating 320 performs one-dimensional pupil expansion and coupling of the second sub-ray L2 in another direction. For the first sub-ray L1, the first coupling grating 320 directly performs two-dimensional pupil expansion and coupling of the first sub-ray L1.

[0060] Please see Figure 5The optical waveguide 300 may also have a second turning region 308. After the image light L is diffracted by the first coupling grating 310, it forms a third sub-ray L3. The propagation directions of the first sub-ray L1, the second sub-ray L2, and the third sub-ray L3 within the optical waveguide 300 are different, and their propagation step sizes are also different. Specifically, the propagation step size of the first sub-ray L1, the propagation step size of the second sub-ray L2 from the first turning region 304 to the coupling region 306, and the propagation step size of the third sub-ray L3 from the second turning region 308 to the coupling region 306 are all different. For a description of the propagation step size, please refer to the relevant content above in the instruction manual; it will not be elaborated upon here.

[0061] In this embodiment, the third sub-ray L3 is conducted through the second folding region 308 to the coupling region 306 for pupil expansion and coupling out. Specifically, the third sub-ray L3 forms multiple third pupil-expanding spots (not shown in the figure) in the coupling region 306, and the multiple third pupil-expanding spots, multiple second pupil-expanding spots K2, and multiple first pupil-expanding spots K1 are arranged alternately. Therefore, this embodiment adopts a waveguide design with double folding regions, which can further improve the uniformity of image brightness coupled out at the coupling region 306, thereby ensuring the enhanced display effect of the display device 100. Specifically, the optical waveguide 300 in this embodiment has three pupil-expanding paths, which can significantly increase the pupil-expanding density and improve the waveguide efficiency of the optical waveguide 300.

[0062] exist Figure 5 In the illustrated embodiment, the optical waveguide 300 may further include a second deflection grating 340 disposed in the second deflection region 308. The second deflection grating 340 is a one-dimensional grating to achieve one-dimensional pupil expansion and deflection of the third sub-ray L3 in one direction. Further, the deflected third sub-ray L3 propagates to the coupling region 306, where the first coupling grating 320 performs one-dimensional pupil expansion and coupling of the third sub-ray L3 in another direction.

[0063] Please see Figure 6 , Figure 6 for Figure 5 The k-vector diagram of the optical waveguide 300 is shown. In the coupling region 302, the k-vector of the first coupling grating 310 includes... , and ,in Assume the k-vector of the image ray L coupled into the optical waveguide 300 is... Then the k-vector of the ray propagating to the second turning region 308 (that is, the third sub-ray L3) is: Assuming the refractive index of the optical waveguide 300 is n and its thickness is d, then The corresponding propagation step size is ,in, .

[0064] Similarly, the propagation step size of the third sub-ray L3 from the second deflection region 308 to the coupling region 306 can be obtained from the k-vector. Specifically, the grating k-vector of the second deflection grating 340 is: Therefore, the k-vector of the third sub-ray L3 propagating from the second turning region 308 to the coupling region 306 is: The corresponding propagation step size can be calculated as follows: I won't go into too much detail here.

[0065] Therefore, the displacement of the center of the third pupil spot in the coupling region 306 relative to the coupling region 302 satisfies Where m and n are integers. Similarly, for the second expanding pupil spot along the propagation path of the first turning region 304 and the coupling region 306, its relative displacement satisfies Where m and n are integers. and These correspond to the propagation step lengths of the second sub-ray L2 from the coupling region 302 to the first turning region 304 and from the first turning region 304 to the coupling region 306, respectively.

[0066] Furthermore, for the first expanded pupil spot that propagates directly along the propagation path from the coupling region 302 to the coupling region 306, its relative displacement satisfies Where l, m, and n are integers. The propagation step size of the first sub-ray L1 along the path from the coupling region 302 to the coupling region 306.

[0067] It is easy to understand that, in order for all three propagation paths to satisfy the k-vector closure condition, and for their k-vector to be the same as that of the first coupling grating 310, this waveguide architecture also requires... .when and At that time, propagation step length At this point, the centers of the light spots from the three different propagation paths do not coincide, allowing for complementary light spots. It is important to note that... Figure 6 The grating k-vector in the diagram is only one possible schematic representation. and The only requirement is that either the orientation or the length of the grating is different.

[0068] As another example, the optical waveguide 300 may include a waveguide substrate (not shown in the figure) that serves to fix and support a grating (e.g., a coupling-in grating, a coupling-out grating). For example, the grating may be fixed to the surface of the waveguide substrate. Alternatively, the grating may be fabricated on the surface of the waveguide substrate using photolithography (electron beam lithography, interference lithography, etc.) or nanoimprint lithography.

[0069] Specifically, the waveguide substrate has a first surface 301 and a second surface 303 that are opposite to each other. The optical waveguide 300 may further include a second coupling grating 350 and a third coupling grating 352 disposed in the coupling region 302, and a second coupling grating 360 and a third coupling grating 362 disposed in the coupling region 306. The projection of the second coupling grating 350 onto the thickness direction of the waveguide substrate coincides with the projection of the third coupling grating 352, and the projection of the second coupling grating 360 onto the thickness direction of the waveguide substrate coincides with the projection of the third coupling grating 362.

[0070] Please refer to it again. Figure 2 The first surface 301 is the side of the optical waveguide 300 facing the optical-mechanical module 20, and the second surface 303 is the side of the optical waveguide 300 away from the optical-mechanical module 20. Of course, in other possible examples, the second surface 303 can be the side of the optical waveguide 300 facing the optical-mechanical module 20, and the first surface 301 can be the side of the optical waveguide 300 away from the optical-mechanical module 20.

[0071] Please see Figure 7 ,exist Figure 7 (a) shows the grating arrangement of the first surface 301, with the second coupled-in grating 350 and the second coupled-out grating 360 disposed on the first surface 301. Figure 7 (b) shows the grating arrangement of the second surface 303, where a third coupling grating 352 and a third coupling grating 362 are disposed. The image ray L is diffracted sequentially by the second coupling grating 350 and the third coupling grating 352 to form a first sub-ray L1, and the image ray L is diffracted by the second coupling grating 350 to form a second sub-ray L2. Specifically, the second coupling grating 350, the third coupling grating 352, the second coupling grating 360, and the third coupling grating 362 are all one-dimensional gratings.

[0072] Therefore, compared to Figure 5 In the example shown, a "double-sided processing" method is used to form two one-dimensional gratings in the coupling region 302 and the coupling region 306 respectively, instead of Figure 5 The scheme of using the first coupling grating 310 and the first coupling grating 320 (both two-dimensional gratings) can reduce the processing cost of the optical waveguide 300.

[0073] Specifically, the second input grating 350 and the third input grating 352 have different grating orientations, and the second output grating 360 and the third output grating 362 have different grating orientations. As one possible embodiment, the second input grating 350 and the third output grating 362 have the same grating orientation and grating period, and the third input grating 352 and the second output grating 360 have the same grating orientation and grating period. As another possible embodiment, the second input grating 350 and the second output grating 360 have the same grating orientation and grating period, and the third input grating 352 and the third output grating 362 have the same grating orientation and grating period.

[0074] In some possible embodiments, the optical waveguide 300 may further include a second deflection region 308. The image ray L, after diffraction by the third coupling grating 352, forms a third sub-ray L3. The third sub-ray L3 is then propagated through the second deflection region 308 to the coupling out region 306 for pupil expansion and coupling out. The propagation directions of the first sub-ray L1, the second sub-ray L2, and the third sub-ray L3 within the optical waveguide 300 are different. Specifically, during the coupling process of the second sub-ray L2 and the third sub-ray L3 into the optical waveguide 300, the third coupling grating 352 does not diffract the second sub-ray L2, and the second coupling grating 350 does not diffract the third sub-ray L3.

[0075] The propagation paths of the first sub-ray L1, the second sub-ray L2, and the third sub-ray L3 are described here. The propagation path of the first sub-ray L1 is as follows: after being diffracted by the second coupling grating 350 and the third coupling grating 352, the ray directly propagates to the coupling region 306, and then is diffracted once each by the second coupling grating 360 and the third coupling grating 362 before being coupled out to the outside. Specifically, to satisfy the k-vector closure requirement, this propagation path requires: The grating vector of the second coupling grating 350 is... The grating vector of the third coupling grating 352 is The grating vector of the second coupled grating 360 is The grating vector of the third output grating 362 is .

[0076] The propagation path of the second sub-ray L2 is as follows: the ray propagates to the first turning region 304 after diffraction only through the second coupling grating 350, then to the coupling region 306, and finally exits to the outside world after diffraction only through the second coupling grating 360. Specifically, in order to satisfy the k-vector closure, this propagation path requires that the grating vector of the first turning grating 330 is: .

[0077] The propagation path of the third sub-ray L3 is as follows: the ray propagates to the second turning region 308 after diffraction only through the third coupling grating 352, then to the coupling region 306, and finally exits to the outside world after diffraction only through the third coupling grating 362. Specifically, in order to satisfy the k-vector closure, this propagation path requires that the grating vector of the second turning grating 340 is: .

[0078] It is easy to understand that, because the second coupling grating 350 and the third coupling grating 352 diffract the first sub-ray L1, the final propagation direction of the first sub-ray L1 within the optical waveguide 300 is the sum of the grating vectors corresponding to the two coupling gratings. When the grating vectors of the second coupling grating 350 and the third coupling grating 352 are different, it can be ensured that the propagation directions of the first sub-ray L1 are different from those of the second sub-ray L2 and the third sub-ray L3, thus ensuring the independent propagation of the three sub-rays.

[0079] exist Figure 7 In the illustrated embodiment, both the first folding region 304 and the second folding region 308 are disposed on the first surface 301. In other possible embodiments, the first folding region 304 may be disposed on the second surface 303, or the second folding region 308 may be disposed on the second surface 303; this embodiment does not specifically limit this.

[0080] As another example, the optical waveguide 300 may include a waveguide substrate (not shown in the figure) having a first surface 301 and a second surface 303 facing away from each other. The optical waveguide 300 may also include a fourth coupling grating 370 and a fifth coupling grating 372 disposed in the coupling region 302, a first folding grating 330 disposed in the first folding region 304, and a fourth coupling grating 380 and a fifth coupling grating 382 disposed in the coupling region 306. The projection of the fourth coupling grating 370 onto the thickness direction of the waveguide substrate coincides with the fifth coupling grating 372, and the projection of the fourth coupling grating 380 onto the thickness direction of the waveguide substrate coincides with the fifth coupling grating 382.

[0081] Please see Figure 8 ,exist Figure 8(a) The region shows the grating arrangement of the first surface 301. The fourth coupling grating 370, the first folding grating 330 and the fourth coupling grating 380 are disposed on the first surface 301, and the sum of the grating vectors of the fourth coupling grating 370, the first folding grating 330 and the fourth coupling grating 380 is 0. That is to say, the fourth coupling grating 370, the first folding grating 330 and the fourth coupling grating 380 can form a conventional one-dimensional folding structure. The grating vectors of the three satisfy a closed relationship so that the second sub-ray L2 can sequentially pass through the coupling region 302, the first folding region 304 and the coupling region 306 to complete the pupil expansion and coupling of the light spot.

[0082] exist Figure 8 (b) shows the grating arrangement of the second surface 303. The fifth coupling grating 372 and the fifth coupling grating 382 are disposed on the second surface 303, and the grating orientation and grating period of the fifth coupling grating 372 and the fifth coupling grating 382 are the same. That is to say, the grating vectors of the fifth coupling grating 372 and the fifth coupling grating 382 also satisfy the closed relationship, so that the first sub-ray L1 can be coupled out after being directly diffracted and transmitted to the coupling out region 306 via the coupling region 302. At the same time, this part of the light will also illuminate the fourth coupling grating 370, and after being diffracted and propagated by the fourth coupling grating 370, the two-dimensional pupil expansion and coupling out of the first sub-ray L1 are finally realized.

[0083] This application provides an optical waveguide 300 and an augmented reality device 100 configured with the optical waveguide 300. The optical waveguide 300 has a coupling-in region 302, a first deflection region 304, and a coupling-out region 306. A first sub-ray L1 in an image ray L is coupled into the image ray L via the coupling-in region 302, then directly transmitted to the coupling-out region 306 for pupil dilation and coupling out. The first sub-ray L1 forms multiple first pupil dilation spots K1 in the coupling-out region 306. A second sub-ray L2 in an image ray L is coupled into the image ray L via the coupling-in region 302, then transmitted to the coupling-out region 306 via the first deflection region 304 for pupil dilation and coupling out. The second sub-ray L2 forms multiple second pupil dilation spots K2 in the coupling-out region 306, and the multiple second pupil dilation spots K2 and the multiple first pupil dilation spots K1 are arranged alternately.

[0084] Therefore, after the image ray L is coupled into the optical waveguide 300, there are at least two propagation paths. The ray on one propagation path (i.e., the first sub-ray L1) will be directly transmitted to the coupling region 306, and the ray on the other propagation path (i.e., the second sub-ray L2) will be transmitted to the first turning region 304, and after one-dimensional pupil expansion and turning in the first turning region 304, it will be transmitted to the coupling region 306.

[0085] Furthermore, when the first sub-ray L1 and the second sub-ray L2 expand their pupils and couple out in the coupling region 306, the multiple first pupil-expanding light spots K1 and multiple second pupil-expanding light spots K2 formed on the coupling region 306 are arranged in an alternating manner. That is, the multiple first pupil-expanding light spots K1 can fill the gaps between the multiple second pupil-expanding light spots K2, and the multiple second pupil-expanding light spots K2 can also fill the gaps between the multiple first pupil-expanding light spots K1, thereby improving the uniformity of the image brightness after pupil expansion, so as to ensure the display effect of the augmented reality device 100 equipped with the optical waveguide 300.

[0086] In this application specification, certain terms are used to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. The specification and claims do not distinguish components based on differences in name, but rather on differences in function. The term "comprising" throughout the specification and claims is an open-ended term and should be interpreted as "including but not limited to"; "generally" means that those skilled in the art can solve the technical problem within a certain margin of error and basically achieve the technical effect.

[0087] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "inside", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the purpose of simplifying the description of this application and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0088] In this application, unless otherwise expressly specified or limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or merely surface contact. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0089] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0090] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0091] 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 of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. An optical waveguide, characterized in that, The optical waveguide, used for transmitting image light, is provided with an input region, a first folding region, and an output region. The first sub-ray in the image light is coupled into the coupling region, then directly transmitted to the coupling out region for pupil dilation and coupling out; wherein, the first sub-ray forms multiple first pupil dilation spots in the coupling out region; The second sub-ray in the image light is coupled into the coupling region, then transmitted through the first deflection region to the coupling out region for pupil dilation and coupling out; wherein, the second sub-ray forms multiple second pupil dilation spots in the coupling out region, and the multiple second pupil dilation spots and the multiple first pupil dilation spots are arranged alternately.

2. The optical waveguide according to claim 1, characterized in that, The propagation step size of the first sub-ray and the propagation step size of the second sub-ray from the first deflection region to the coupling region are different; The propagation step length refers to the distance between two light spots formed on the same waveguide surface after the sub-ray undergoes two total internal reflections within the optical waveguide.

3. The optical waveguide according to claim 1, characterized in that, At least some of the centers of the second pupil-expanding light spots do not coincide with the centers of the first pupil-expanding light spots.

4. The optical waveguide according to any one of claims 1 to 3, characterized in that, The optical waveguide includes a first coupling grating disposed in the coupling region and a first coupling grating disposed in the coupling region. The image light rays are diffracted by the first coupling grating to form the first sub-ray and the second sub-ray respectively, and the propagation directions of the first sub-ray and the second sub-ray are different in the optical waveguide. Both the first coupling-in grating and the first coupling-out grating are two-dimensional gratings.

5. The optical waveguide according to claim 4, characterized in that, The optical waveguide is also provided with a second turning region. The image light rays are diffracted by the first coupling grating to form a third sub-ray rays. The propagation directions of the first sub-ray rays, the second sub-ray rays, and the third sub-ray rays in the optical waveguide are different. The third sub-ray beam is transmitted through the second deflection region to the coupling region for pupil dilation and coupling out; wherein the third sub-ray beam forms multiple third pupil dilation spots in the coupling region, and the multiple third pupil dilation spots, multiple second pupil dilation spots and multiple first pupil dilation spots are arranged alternately with each other.

6. The optical waveguide according to any one of claims 1 to 3, characterized in that, The optical waveguide includes a waveguide substrate having a first surface and a second surface facing away from each other. The optical waveguide also includes a second coupling grating and a third coupling grating disposed in the coupling region, and a second coupling grating and a third coupling grating disposed in the coupling region. The projection of the second coupling grating in the thickness direction of the waveguide substrate coincides with the projection of the third coupling grating in the thickness direction of the waveguide substrate. The second coupling grating and the second coupling grating are disposed on the first surface, and the third coupling grating and the third coupling grating are disposed on the second surface; the image light rays are diffracted sequentially through the second coupling grating and the third coupling grating to form the first sub-ray rays, and the image light rays are diffracted through the second coupling grating to form the second sub-ray rays; Wherein, the second coupling grating, the third coupling grating, the second coupling grating, and the third coupling grating are all one-dimensional gratings.

7. The optical waveguide according to claim 6, characterized in that, The optical waveguide is further provided with a second turning region. The image light rays are diffracted by the third coupling grating to form a third sub-ray. The third sub-ray is conducted through the second turning region to the coupling region for pupil expansion and coupling out. The propagation directions of the first sub-ray, the second sub-ray, and the third sub-ray in the optical waveguide are different. During the coupling process of the second sub-ray and the third sub-ray into the optical waveguide, the third coupling grating does not diffract the second sub-ray, and the second coupling grating does not diffract the third sub-ray.

8. The optical waveguide according to any one of claims 1 to 3, characterized in that, The optical waveguide includes a waveguide substrate having a first surface and a second surface facing away from each other. The optical waveguide also includes a fourth and a fifth coupling grating disposed in the coupling region, a first folding grating disposed in the first folding region, and a fourth and a fifth coupling grating disposed in the coupling region. The projection of the fourth coupling grating in the thickness direction of the waveguide substrate coincides with the fifth coupling grating, and the projection of the fourth coupling grating in the thickness direction of the waveguide substrate coincides with the fifth coupling grating. The fourth coupling grating, the first folded grating, and the fourth coupling grating are disposed on the first surface, and the sum of the grating vectors of the fourth coupling grating, the first folded grating, and the fourth coupling grating is 0; The fifth input grating and the fifth output grating are disposed on the second surface, and the grating orientation and grating period of the fifth input grating and the fifth output grating are the same.

9. An augmented reality device, characterized in that, include: An optical-mechanical module for generating image rays; wherein the exit pupil size of the optical-mechanical module is less than or equal to 1 mm; and The optical waveguide according to any one of claims 1 to 8, wherein the optical waveguide is used to conduct the image light; wherein the image light coupled out through the optical waveguide is incident on the user's eye region.

10. The augmented reality device according to claim 9, characterized in that, The optomechanical module includes a laser and a microelectromechanical system (MEMS) mirror; wherein the laser is used to generate laser light; and the MEMS mirror is used to reflect the laser light to form the image light rays; or, The optomechanical module includes an optical modulation chip, which is used to form the image light rays; wherein the optical modulation chip is a silicon-based liquid crystal chip or a digital micromirror chip.

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