Diffractive waveguide optical elements and near-eye display devices

Abstract

This invention provides a diffractive waveguide optical element and a near-eye display device, relating to the field of augmented reality applications. It includes a waveguide and an input diffraction grating, an output diffraction grating, and a steering assembly disposed on the waveguide. The input diffraction grating receives image light from a microdisplay and couples the image light into the waveguide. The output diffraction grating couples the image light out of the waveguide. The steering assembly adjusts the image light transmitted out of the output diffraction grating region, and the adjusted image light is re-injected into the output diffraction grating. Through the steering assembly, the diffractive waveguide optical element of this invention can utilize the light transmitted out of the output diffraction grating region, and after being redirected, re-inject into the output diffraction grating, thereby improving the contrast of the augmented reality image coupled from the output diffraction grating towards the viewer, and improving the uniformity and energy utilization of the diffraction waveguide's pupil.

Description

Technical Field

[0001] This invention relates to the field of augmented reality application technology, and more particularly to diffractive waveguide optical elements and near-eye display devices. Background Technology

[0002] Augmented Reality (AR) technology is a technology that integrates computer-generated virtual information with the real world. AR near-eye display devices, exemplified by AR glasses, transmit images from a microdisplay to the human eye through a series of optical imaging elements. Their perspective properties allow real-world objects to simultaneously appear in the eye, greatly enhancing the immersive experience. With the rapid development of AR technology, AR products have been widely applied in fields such as gaming, military, education, healthcare, and retail.

[0003] Optical imaging elements are used for light transmission and imaging, and are crucial for AR glasses. Currently, relatively mature optical imaging solutions mainly include prisms, freeform surfaces, off-axis holographic lenses, arrayed waveguides, volume holographic grating waveguides, and diffraction grating waveguides. Prism and freeform surface optical solutions are relatively large, resulting in poor wearability; holographic lens optical solutions are small in size and have a large field of view, but a small range of eye movement; arrayed waveguide optical solutions achieve image output and pupil enlargement through the stacking of semi-transparent and semi-reflective films, but their manufacturing process is complex, resulting in low production yield and high cost; volume holographic grating waveguides achieve light coupling and coupling by forming periodic refractive index changes on the holographic material through double-beam interference exposure, but have a small field of view and poor stability; diffraction grating waveguides mainly utilize photolithography to create surface relief gratings on the waveguide surface to achieve image coupling and coupling, have a large field of view, are lightweight, and their manufacturing process is compatible with mature semiconductor manufacturing technologies, resulting in high mass production yield. Therefore, diffraction grating waveguides are a popular optical imaging solution for AR displays, but they still face many challenges, such as improving exit pupil uniformity and energy efficiency, which are urgent problems to be solved. Summary of the Invention

[0004] This invention provides a diffractive waveguide optical element and a near-eye display device to solve the defects of uneven exit pupil and low energy utilization in the prior art.

[0005] This invention provides a diffractive waveguide optical element, comprising: a waveguide and an input diffraction grating, an output diffraction grating, and a steering combination element disposed on the waveguide; the input diffraction grating receives image light from a microdisplay and couples the image light into the waveguide; the image light propagates within the waveguide by total internal reflection; the output diffraction grating couples the image light out of the waveguide; the steering combination element adjusts the image light propagating out of the output diffraction grating region, and the adjusted image light is re-injected into the output diffraction grating.

[0006] According to the present invention, a diffractive waveguide optical element includes a steering assembly comprising a first steering element, a second steering element, a third steering element, a fourth steering element, a fifth steering element, and a sixth steering element. The first, third, fourth, and sixth steering elements receive image light rays and re-incidentally output the redirected image light rays to the diffraction grating. The image light rays in the first and fourth steering elements propagate along a first or second direction, while the image light rays in the third and sixth steering elements propagate along a third or fourth direction. The second and fifth steering elements redirect the image light rays in the first direction to image light rays in the third direction and convert the image light rays in the fourth direction into image light rays in the second direction. The first and second directions are opposite, and the third and fourth directions are opposite.

[0007] According to a diffractive waveguide optical element provided by the present invention, a first steering element receives image light rays passing through an output diffraction grating and propagates the image light rays along a first direction to a second steering element; the second steering element adjusts the image light rays to be incident on a third steering element along a third direction; the third steering element adjusts the image light rays to be re-incidentally incident on the diffraction grating; the third steering element receives image light rays passing through an output diffraction grating and propagates the image light rays along a fourth direction to a second steering element; the second steering element adjusts the image light rays to be incident on a second direction to a first steering element; the first steering element adjusts the image light rays to be re-incidentally incident on the output diffraction grating; a fourth steering element receives image light rays passing through an output diffraction grating and propagates the image light rays along a first direction to a fifth steering element; the fifth steering element adjusts the image light rays to be incident on a sixth steering element along a fourth direction; the sixth steering element adjusts the image light rays to be re-incidentally incident on the output diffraction grating; the sixth steering element receives image light rays passing through an output diffraction grating and propagates the image light rays along a third direction to a fifth steering element; the fifth steering element adjusts the image light rays to be incident on a fourth steering element along a second direction; the fourth steering element adjusts the image light rays to be re-incidentally incident on the output diffraction grating.

[0008] According to the present invention, a diffractive waveguide optical element is provided, wherein the first steering element is a first steering grating, the second steering element is a second steering grating, the third steering element is a third steering grating, the fourth steering element is a fourth steering grating, the fifth steering element is a fifth steering grating, and the sixth steering element is a sixth steering grating.

[0009] According to the present invention, a diffractive waveguide optical element includes a first steering grating comprising an oriented groove at a first preset angle to the vertical axis, a second steering grating comprising an oriented groove at a second preset angle to the vertical axis, a third steering grating comprising an oriented groove at a third preset angle to the vertical axis, a fourth steering grating comprising an oriented groove at a fourth preset angle to the vertical axis, a fifth steering grating comprising an oriented groove at a fifth preset angle to the vertical axis, and a sixth steering grating comprising an oriented groove at a sixth preset angle to the vertical axis.

[0010] According to the present invention, a diffractive waveguide optical element is provided, wherein the output diffraction grating includes a first diffraction grating and a second diffraction grating that overlap each other. The first diffraction grating includes a plurality of diffraction optical structures, and the diffraction optical structures of the first diffraction grating are oriented at a seventh preset angle with the vertical axis. The second diffraction grating includes a plurality of diffraction optical structures, and the diffraction optical structures of the second diffraction grating are oriented at an eighth preset angle with the vertical axis.

[0011] According to the present invention, the sum of the first preset angle and the fourth preset angle is zero, the sum of the second preset angle and the fifth preset angle is zero, the sum of the third preset angle and the sixth preset angle is zero, and the sum of the seventh preset angle and the eighth preset angle is zero.

[0012] According to the present invention, a diffractive waveguide optical element has a first preset angle of -30°, a second preset angle of +45°, a third preset angle of -45°, a fourth preset angle of +30°, a fifth preset angle of -45°, a sixth preset angle of +45°, a seventh preset angle of -30°, and an eighth preset angle of +30°.

[0013] According to the present invention, a diffractive waveguide optical element has a first preset angle of -45°, a second preset angle of +45°, a third preset angle of -45°, a fourth preset angle of +45°, a fifth preset angle of -45°, a sixth preset angle of +45°, a seventh preset angle of 0°, and an eighth preset angle of 90°.

[0014] According to the present invention, a diffractive waveguide optical element is provided in which a portion of the image light coupled to the human eye for imaging passes through an input diffraction grating, an output diffraction grating, and a steering combination element. The grating vectors of the input diffraction grating, the output diffraction grating, and the steering combination element are combined to generate a composite vector with a magnitude of zero.

[0015] The present invention also provides a near-eye display device, including a microdisplay and the above-mentioned diffractive waveguide optical element; the microdisplay outputs image light.

[0016] The present invention provides a diffractive waveguide optical element and a near-eye display device, comprising a waveguide and an input diffraction grating, an output diffraction grating, and a steering combination element disposed on the waveguide; the input diffraction grating receives image light from a microdisplay and couples the image light into the waveguide; the image light propagates within the waveguide by total internal reflection; the output diffraction grating couples out the image light propagating within the waveguide by total internal reflection; the steering combination element adjusts the image light transmitted out of the output diffraction grating region, and the adjusted image light re-enters the output diffraction grating; through the above method, the diffractive waveguide optical element of the present invention can change the direction of light transmitted out of the output diffraction grating region by means of the steering combination element, and after the light is redirected, it re-enters the output diffraction grating, thereby improving the contrast of the augmented reality image coupled out of the output diffraction grating towards the viewer, and improving the uniformity and energy utilization of the diffraction waveguide pupil. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of an embodiment of a diffractive waveguide optical element in related technologies;

[0019] Figure 2 yes Figure 1 A schematic diagram of a set of grating vector combinations for a diffractive waveguide optical element;

[0020] Figure 3 This is a schematic diagram of the structure of an embodiment of the diffractive waveguide optical element of the present invention;

[0021] Figure 4 yes Figure 3 A schematic diagram of a set of grating vector combinations for a diffractive waveguide optical element;

[0022] Figure 5 yes Figure 3 A schematic diagram of another set of grating vector combinations for the diffractive waveguide optical element shown;

[0023] Figure 6 This is a schematic diagram of another embodiment of the diffractive waveguide optical element of the present invention;

[0024] Figure 7 yes Figure 6 A schematic diagram of a set of grating vector combinations for a diffractive waveguide optical element;

[0025] Figure 8 yes Figure 6 A schematic diagram of another set of grating vector combinations for the diffractive waveguide optical element shown. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0027] Please see Figure 1 , Figure 1 This is a schematic diagram of an embodiment of a diffractive waveguide optical element in related technologies; an input diffraction grating 11 and an output diffraction grating 12 are disposed on the surface of the waveguide 10. The groove of the input diffraction grating 11 is located at... Figure 1 It extends in a direction parallel to the x-axis in the Cartesian coordinate system. The output diffraction grating 12 is a pair of intersecting gratings, including a first diffraction grating and a second diffraction grating that overlap each other in or on the waveguide 10.

[0028] The first diffraction grating has a row of diffraction optical structures oriented at -30° to the y-axis, and the second diffraction grating has a row of diffraction optical structures oriented at +30° to the y-axis.

[0029] The first diffraction grating receives light from the input diffraction grating 11 and diffracts it into orders extending in a direction at an angle of +120° to the y-axis. These orders can be diffracted by the second diffraction grating, which is orthogonal to the diffraction orders extending at an angle of +120° to the y-axis, such that the second diffraction grating can provide output orders toward the viewer.

[0030] Similarly, the second diffraction grating receives light from the input diffraction grating 11 and diffracts it into orders extending at a -120° angle to the y-axis. These orders can be diffracted by the first diffraction grating, which is orthogonal to the diffraction orders extending at a -120° angle to the y-axis, such that the first diffraction grating can provide an output order toward the viewer. The diffraction efficiencies of the first and second diffraction gratings within the output diffraction grating 12 are selected to allow light to simultaneously propagate in two dimensions while providing an output order toward the viewer as an augmented reality image.

[0031] Light trapped within waveguide 10 by total internal reflection interacts multiple times with the output diffraction grating 12. In each interaction with the output diffraction grating 12, the light is either diffracted and coupled out of waveguide 10 toward the viewer, or the light continues to propagate in its original direction and moves away from the input diffraction grating 11 without diffraction. The ratio of diffracted light to non-diffracted light is determined by the diffraction efficiency of the output diffraction grating 12.

[0032] If the efficiency of the output diffraction grating 12 remains constant, the brightness of the light decreases sequentially in the negative y-direction, positive x-direction, and negative x-direction. This is because as light propagates within the waveguide, less and less light is captured through total internal reflection, resulting in different brightness levels of the augmented reality image seen by the viewer at different positions in the x-direction and negative y-direction, creating exit pupil inhomogeneity. A certain proportion of light continues to propagate along the negative y-direction, positive x-direction, and negative x-direction under total internal reflection; this light is typically scattered by the waveguide edges. The scattered light may undesirably return towards the output diffraction grating 12, generating background light and reducing the contrast of the augmented reality image coupled from the output diffraction grating 12 towards the viewer.

[0033] Specifically, there are many possible optical paths within the output diffraction grating 12, but this can be simplified by considering the four optical paths of light when the light first interacts with the output diffraction grating 12 after it has been diffracted by the input diffraction grating 11.

[0034] First optical path: The light is not diffracted and continues to propagate in the negative y direction, and is captured in waveguide 10 by total internal reflection.

[0035] Second optical path: Light is diffracted by a first diffraction grating having a groove at an angle of -30° to the y-axis, causing the light to extend in a direction at an angle of +120° to the y-axis.

[0036] Third optical path: Light is diffracted by a second diffraction grating with a groove at an angle of +30° to the y-axis, causing the light to extend in a direction at -120° to the y-axis.

[0037] Fourth optical path: Light is diffracted by the superposition of a first diffraction grating and a second diffraction grating with an effective groove parallel to the x-axis (equivalent to being diffracted by a third diffraction grating), so that the light is directly coupled out of waveguide 10 toward the viewer.

[0038] Each diffraction grating includes a grating vector in the plane of its grooves. The grating vector has a direction perpendicular to the groove and a magnitude inversely proportional to the spacing between the grooves. The direction of the grating vector is determined by the polarity of the diffraction order of light. The superposition of the grating vectors of the first and second diffraction gratings can be considered as the grating vector of the third diffraction grating. The grating vector of the third diffraction grating forms a 60° angle with the grating vectors of the first and second diffraction gratings, and is parallel to the grating vector of the input diffraction grating.

[0039] Combination Figure 2 , Figure 2 yes Figure 1 A schematic diagram of a set of grating vector combinations for a diffractive waveguide optical element; Figure 2 The grating vectors of the diffraction interaction along the second and third optical paths are shown.

[0040] The second and third optical paths are mirror images of each other.

[0041] For the second optical path, light is sequentially input into diffraction grating 11 to generate grating vector 110, light is diffried by a first diffraction grating having a groove at a -30° angle to the y-axis to generate grating vector 121, light is diffried by a second diffraction grating to generate grating vector 122, and the individual grating vectors 110, 121 and 122 are added together to generate a composite vector with a magnitude of zero, indicating that the sequence of diffraction interactions can provide a coupling stage toward the viewer with minimal angular aberration and chromatic aberration.

[0042] For the third optical path, light is sequentially diffracted by diffraction grating 11 to produce grating vector 110, diffracted by a second diffraction grating with a groove at a +30° angle to the y-axis to produce grating vector 122, and diffracted by a first diffraction grating to produce grating vector 121. The individual grating vectors 110, 122, and 121 are added together to produce a composite vector with a magnitude of zero, indicating that the sequence of diffraction interactions can also provide a coupling stage toward the viewer with minimal angular and chromatic aberrations.

[0043] However, as can be seen from the above analysis, in the diffraction waveguide optical elements of the related technology, total internal reflection of light in the directions of +120° and -120° with the y-axis extends the output diffraction grating region, and total internal reflection of light in the negative y-direction extends the output diffraction grating region, which will cause light energy waste.

[0044] Based on this, the present invention provides a diffractive waveguide optical element, please refer to [link / reference]. Figure 3 , Figure 3 This is a schematic diagram of a structure of an embodiment of the diffractive waveguide optical element of the present invention. In this embodiment, the diffractive waveguide optical element includes: a waveguide 20, an input diffraction grating 21, an output diffraction grating 22, and a steering combination element.

[0045] The input diffraction grating 21 is set on the waveguide 20 to receive image light from the microdisplay and couple the image light into the waveguide 20 so that the image light propagates in the waveguide 20 in a total internal reflection manner; wherein, the image light can be understood as the incident light carrying image information.

[0046] An output diffraction grating 22 is disposed on the waveguide 20 to couple out the image light rays that propagate in the waveguide by total internal reflection.

[0047] The steering combination element is set on waveguide 20 to adjust the image light transmitted out of the output diffraction grating region, and the adjusted image light is re-injected into the output diffraction grating.

[0048] This embodiment utilizes a steering combination element to guide the image light from the output diffraction grating region. After the light is redirected, it is re-injected into the output diffraction grating, improving energy utilization and thus enhancing the contrast of the augmented reality image coupled from the output diffraction grating toward the viewer, thereby improving the exit pupil uniformity of the diffraction waveguide optical element.

[0049] The input diffraction grating 21, the output diffraction grating 22, and the steering combination element can be disposed on the surface of the waveguide 20. The image light from the microdisplay is diffracted by the input diffraction grating and coupled into the waveguide 20. The image light coupled into the waveguide 20 can travel toward the output diffraction grating through total internal reflection.

[0050] Optionally, the input diffraction grating 21 can be a one-dimensional blazed grating or a tilted grating. The input diffraction grating 21 preferentially diffracts image light in the direction of the output diffraction grating 22. The grooves of the input diffraction grating 21 extend in a direction parallel to the x-axis in the Cartesian coordinate system, such as... Figure 3 As shown.

[0051] It should be noted that the Cartesian coordinate system in this embodiment is a Cartesian rectangular coordinate system with two mutually perpendicular number axes. It can be understood as a coordinate system established with the horizontal direction as the x-axis and the vertical direction as the y-axis, where the z-axis is perpendicular to both the x-axis and the y-axis.

[0052] The output diffraction grating 22 is a pair of intersecting gratings, including a first diffraction grating and a second diffraction grating that overlap each other on the surface of the waveguide 20. Both the first diffraction grating and the second diffraction grating are arranged with oriented rows of diffraction optical structures.

[0053] In some embodiments, the steering assembly includes a first steering element, a second steering element, a third steering element, a fourth steering element, a fifth steering element, and a sixth steering element.

[0054] The first, third, fourth, and sixth steering elements receive the image light rays and re-inject the redirected image light rays into the output diffraction grating.

[0055] In this configuration, the image rays in the first and fourth steering elements propagate along either the first or second direction, while the image rays in the third and sixth steering elements propagate along either the third or fourth direction. The second and fifth steering elements redirect the image rays in the first direction to the third direction and redirect the image rays in the fourth direction to the second direction. The first and second directions are opposite, as are the third and fourth directions.

[0056] Optionally, the first direction can be the negative y-axis direction, the second direction can be the positive y-axis direction, the third direction can be the negative x-axis direction, and the fourth direction can be the positive x-axis direction.

[0057] When the diffractive waveguide optical element is working, the steering assembly can be used in conjunction with the output diffraction grating to receive image light that cannot be coupled out to the human eye for imaging. After being deflected, the light is re-injected into the output diffraction grating, improving energy utilization. Specifically, the six steering elements in the steering assembly work together as follows:

[0058] The first steering element receives the image light rays passing through the output diffraction grating and propagates the image light rays along the first direction to the second steering element. The second steering element turns the direction of the image light rays to a third direction so that the image light rays are incident on the third steering element along the third direction. The third steering element re-incidentates the image light rays toward the output diffraction grating.

[0059] The third steering element receives the image light rays passing through the output diffraction grating and propagates the image light rays along the fourth direction to the second steering element. The second steering element turns the direction of the image light rays to the second direction so that the image light rays are incident on the first steering element along the second direction. The first steering element then redirects the image light rays toward the output diffraction grating.

[0060] The fourth steering element receives the image light rays passing through the output diffraction grating and propagates the image light rays along the first direction to the fifth steering element. The fifth steering element turns the direction of the image light rays to the fourth direction so that the image light rays are incident on the sixth steering element along the fourth direction. The sixth steering element re-incidentates the image light rays toward the output diffraction grating.

[0061] The sixth steering element receives the image light rays passing through the output diffraction grating and propagates the image light rays along a third direction to the fifth steering element. The fifth steering element turns the direction of the image light rays to a second direction so that the image light rays are incident on the fourth steering element along the second direction. The fourth steering element re-incidentates the image light rays toward the output diffraction grating.

[0062] Optionally, the first steering element is a first steering grating, the second steering element is a second steering grating, the third steering element is a third steering grating, the fourth steering element is a fourth steering grating, the fifth steering element is a fifth steering grating, and the sixth steering element is a sixth steering grating. The following detailed example illustrates the use of steering gratings as the steering element.

[0063] It should be noted that using a steering grating as the steering element is only one embodiment of the present invention. In other embodiments, the steering element can be other structures, such as the second and fifth steering elements being mirrors. Those skilled in the art can select the steering element according to the actual situation, which will not be elaborated here.

[0064] Optionally, the first to sixth steering gratings can be an integrated connected configuration, or each can be an independent configuration, or they can be partially connected and partially independent configurations.

[0065] like Figure 3 As shown, the first, second, fourth, and fifth steering gratings are independently configured and not connected to each other; the third and sixth steering gratings are connected.

[0066] In some embodiments, the first steering grating includes an oriented groove at a first preset angle to the vertical axis, the second steering grating includes an oriented groove at a second preset angle to the vertical axis, the third steering grating includes an oriented groove at a third preset angle to the vertical axis, the fourth steering grating includes an oriented groove at a fourth preset angle to the vertical axis, the fifth steering grating includes an oriented groove at a fifth preset angle to the vertical axis, and the sixth steering grating includes an oriented groove at a sixth preset angle to the vertical axis.

[0067] The output diffraction grating 22 includes a first diffraction grating and a second diffraction grating that overlap each other. The first diffraction grating is arranged with diffraction optical structures that are oriented in a row at a seventh preset angle to the vertical axis, and the second diffraction grating is arranged with optical structures that are oriented in a row at an eighth preset angle to the vertical axis.

[0068] In this embodiment, some of the image light rays passing through the output diffraction grating can be directly coupled to the human eye for imaging, while some of the image light rays passing through the output diffraction grating need to pass through the deflection combination element and be re-intruded into the output diffraction grating before they can be coupled to the human eye for imaging, thereby achieving efficient use of energy.

[0069] Therefore, some of the image rays coupled to the human eye need to pass through the input diffraction grating, the output diffraction grating, and the steering combination element. The grating vectors of the input diffraction grating, the output diffraction grating, and the steering combination element are combined to produce a composite vector with a magnitude of zero.

[0070] Therefore, the sizes of the first preset angle to the eighth preset angle need to be set so that the sum of the first preset angle and the fourth preset angle is zero, the sum of the second preset angle and the fifth preset angle is zero, the sum of the third preset angle and the sixth preset angle is zero, and the sum of the seventh preset angle and the eighth preset angle is zero.

[0071] In some embodiments, the preset angles of the diffractive waveguide optical element can be set as follows: a first preset angle of -30°, a second preset angle of +45°, a third preset angle of -45°, a fourth preset angle of +30°, a fifth preset angle of -45°, a sixth preset angle of +45°, a seventh preset angle of -30°, and an eighth preset angle of +30°. Figure 3 As shown.

[0072] It should be noted that, in this embodiment, a positive angle refers to the angle obtained clockwise from the vertical axis to the horizontal axis, and a negative angle refers to the angle obtained counterclockwise from the vertical axis to the horizontal axis.

[0073] The first steering grating 23 has an oriented groove at a -30° angle to the y-axis, the second steering grating 24 has an oriented groove at a +45° angle to the y-axis, the third steering grating 25 has an oriented groove at a -45° angle to the y-axis, the fourth steering grating 26 has an oriented groove at a +30° angle to the y-axis, the fifth steering grating 27 has an oriented groove at a -45° angle to the y-axis, and the sixth steering grating 28 has an oriented groove at a +45° angle to the y-axis.

[0074] By setting the grooves in the steering grating to a specific angle, image light can be guided to propagate along a specific optical path within the steering grating.

[0075] There are also many possible optical paths within the output diffraction grating 22, but this can be simplified by considering the six optical paths of light as it interacts with the output diffraction grating 22 after the image light has been diffracted by the input diffraction grating.

[0076] First optical path: The image light rays are not diffracted and continue to propagate in the negative y direction, and are captured in waveguide 20 by total internal reflection.

[0077] Second optical path: The image light is diffracted by a first diffraction grating with a groove at a -30° angle to the y-axis, causing the image light to extend in a direction at a +120° angle to the y-axis and propagate toward the first steering grating 23. After encountering the first steering grating 23, the image light is diffracted and propagates toward the second steering grating 24. After encountering the second steering grating 24, the image light is diffracted and propagates toward the third steering grating 25. After encountering the third steering grating 25, the image light is diffracted and propagates toward the output diffraction grating 22. After encountering the output diffraction grating 22, the image light is diffracted by the superposition of the first and second diffraction gratings with effective grooves parallel to the x-axis (equivalent to being diffracted by the third diffraction grating), causing the image light to couple out of the waveguide 20 toward the viewer.

[0078] Third optical path: The image light is diffracted by a first diffraction grating with a groove at a -30° angle to the y-axis, causing the image light to extend in a direction at a +120° angle to the y-axis. Then, the image light is diffracted again by the first diffraction grating, causing the image light to extend in a direction at a +180° angle to the y-axis and propagate toward the third steering grating 25. After encountering the third steering grating 25, the image light is diffracted and propagates toward the second steering grating 24. After encountering the second steering grating 24, the image light is diffracted and propagates toward the first steering grating 23. After encountering the first steering grating 23, the image light is diffracted and propagates toward the output diffraction grating 22. After encountering the output diffraction grating 22, the image light is diffracted by a second diffraction grating with a groove at a +30° angle to the y-axis, causing the image light to couple out toward the viewer from the waveguide 20.

[0079] Fourth optical path: The image light is diffracted by the second diffraction grating with a groove at a +30° angle to the y-axis, causing the image light to extend in a direction at a -120° angle to the y-axis and propagate toward the fourth steering grating 26. After encountering the fourth steering grating 26, the image light is diffracted and propagates toward the fifth steering grating 27. After encountering the fifth steering grating 27, the image light is diffracted and propagates toward the sixth steering grating 28. After encountering the sixth steering grating 28, the image light is diffracted and propagates toward the output diffraction grating 22. After encountering the output diffraction grating 22, the image light is diffracted by the superposition of the first and second diffraction gratings with effective grooves parallel to the x-axis (equivalent to being diffracted by the third diffraction grating), causing the image light to couple out of the waveguide 20 toward the viewer.

[0080] Fifth optical path: The image light is diffracted by a second diffraction grating with a groove at a +30° angle to the y-axis, causing the image light to extend in a direction at a -120° angle to the y-axis. Then, the image light is diffracted again by the second diffraction grating, causing the image light to extend in a direction at a -180° angle to the y-axis and propagate toward the sixth steering grating 28. After encountering the sixth steering grating 28, the image light is diffracted and propagates toward the fifth steering grating 27. After encountering the fifth steering grating 27, the image light is diffracted and propagates toward the fourth steering grating 26. After encountering the fourth steering grating 26, the image light is diffracted and propagates toward the output diffraction grating 22. After encountering the output diffraction grating 22, the image light is diffracted by a first diffraction grating with a groove at a -30° angle to the y-axis, causing the image light to couple out toward the viewer from the waveguide 20.

[0081] Sixth optical path: The image light is diffracted by the superposition of the first and second diffraction gratings with effective grooves parallel to the x-axis (equivalent to being diffracted by the third diffraction grating), so that the image light is directly coupled out of the waveguide 20 towards the viewer.

[0082] Please see Figure 4 , Figure 4 yes Figure 3 A schematic diagram of a set of grating vector combinations for a diffractive waveguide optical element; Figure 4 The grating vectors of the diffraction interaction along the second and third optical paths are shown.

[0083] For the second optical path (i.e., path 2 shown in the figure), the image light rays are sequentially diffracted by the diffraction grating 21 to generate grating vector 210, the image light rays are diffracted by the first diffraction grating having a groove at a -30° angle to the y-axis to generate grating vector 221, the image light rays are diffracted by the first steering grating 23 to generate grating vector 230, the image light rays are diffracted by the second steering grating 24 to generate grating vector 240, the image light rays are diffracted by the third steering grating 25 to generate grating vector 250, and the image light rays are diffracted by the third diffraction grating to generate grating vector 223.

[0084] The individual grating vectors 210, 221, 230, 240, 250, and 223 are added together to produce a composite vector of magnitude zero, indicating that the sequence of diffraction interactions can provide a coupling stage toward the viewer with minimal angular and chromatic aberration.

[0085] For the third optical path (i.e., path 3 shown in the figure), the image light rays are sequentially input into the diffraction grating 21 to generate grating vector 210, the image light rays are diffracted by the first diffraction grating with a groove at a -30° angle to the y-axis to generate grating vector 221, the image light rays are diffracted by the third steering grating 25 to generate grating vector 250, the image light rays are diffracted by the second steering grating 24 to generate grating vector 240, the image light rays are diffracted by the first steering grating 23 to generate grating vector 230, and the image light rays are diffracted by the second diffraction grating with a groove at a +30° angle to the y-axis to generate grating vector 222.

[0086] The individual grating vectors 210, 221, 250, 240, 230, and 222 are added together to produce a composite vector of magnitude zero, indicating that the sequence of diffraction interactions can provide a coupling stage toward the viewer with minimal angular and chromatic aberration.

[0087] Please see Figure 5 , Figure 5 The diffraction interaction grating vectors along the fourth and fifth optical paths are shown. The individual grating vectors are added together to produce a composite vector with a magnitude of zero, indicating that the sequence of diffraction interactions can provide a coupling stage toward the viewer with minimal angular and chromatic aberration.

[0088] The fourth optical path (i.e., path 4 in the diagram) is a mirror image of the second optical path, and the fifth optical path (i.e., path 5 in the diagram) is a mirror image of the third optical path. These will not be elaborated further here.

[0089] Compared with diffractive waveguide optical elements of related technologies, the steering combination element of this embodiment can utilize the image light transmitted out of the output diffraction grating region, so that the image light is redirected and re-intruded into the output diffraction grating, reducing energy loss; in addition, the image light after being redirected by the steering combination element does not return along the original path, that is, the optical path of the image light from the output diffraction grating to the steering combination element and the optical path from the steering combination element to the output diffraction grating do not overlap.

[0090] In some embodiments, the preset angles of the diffractive waveguide optical element can also be set as follows: a first preset angle of -45°, a second preset angle of +45°, a third preset angle of -45°, a fourth preset angle of +45°, a fifth preset angle of -45°, a sixth preset angle of +45°, a seventh preset angle of 0°, and an eighth preset angle of 90°. Figure 6 As shown, Figure 6 This is a schematic diagram of another embodiment of the diffractive waveguide optical element of the present invention.

[0091] Specifically, an input diffraction grating 31 and an output diffraction grating 32 are disposed on the surface of the waveguide 30. The output diffraction grating 32 is a pair of vertically intersecting gratings, that is, the angle between the first diffraction grating and the second diffraction grating is 90°. The diffraction waveguide optical element also includes a first steering grating 33, a second steering grating 34, a third steering grating 35, a fourth steering grating 36, a fifth steering grating 37, and a sixth steering grating 38.

[0092] The first steering grating 33 has an oriented groove at a -45° angle to the y-axis, the second steering grating 34 has an oriented groove at a +45° angle to the y-axis, the third steering grating 35 has an oriented groove at a -45° angle to the y-axis, the fourth steering grating 36 has an oriented groove at a +45° angle to the y-axis, the fifth steering grating 37 has an oriented groove at a -45° angle to the y-axis, and the sixth steering grating 38 has an oriented groove at a +45° angle to the y-axis.

[0093] There are also many possible optical paths within the output diffraction grating 32, but this can be simplified by considering the six optical paths of light when the light interacts with the output diffraction grating 32 after the light has been diffracted by the input diffraction grating 31.

[0094] First optical path: The image light rays are not diffracted and continue to propagate in the negative y direction, and are captured in waveguide 30 by total internal reflection.

[0095] Second optical path: The image light is diffracted by a first diffraction grating with a groove parallel to the y-axis, causing the image light to extend in a direction at +90° to the y-axis and propagate toward the first steering grating 33. After encountering the first steering grating 33, the image light is diffracted and propagates toward the second steering grating 34. After encountering the second steering grating 34, the image light is diffracted and propagates toward the third steering grating 35. After encountering the third steering grating 35, the image light is diffracted and propagates toward the output diffraction grating 32. After encountering the output diffraction grating 32, the image light is diffracted by a second diffraction grating with a groove parallel to the x-axis, causing the image light to couple out toward the viewer from the waveguide 30.

[0096] Third optical path: The image light is diffracted by a first diffraction grating with a groove parallel to the y-axis, causing the image light to extend in a direction at +90° to the y-axis. Then, the image light is diffracted by a second diffraction grating with a groove parallel to the x-axis, causing the image light to extend in a direction at +180° to the y-axis and propagate toward the third steering grating 35. After encountering the third steering grating 35, the image light is diffracted and propagates toward the second steering grating 34. After encountering the second steering grating 34, the image light is diffracted and propagates toward the first steering grating 33. After encountering the first steering grating 33, the image light is diffracted and propagates toward the output diffraction grating 32. After encountering the output diffraction grating 32, the image light is diffracted by the first diffraction grating with a groove parallel to the y-axis, causing the image light to couple out toward the viewer from the waveguide 30.

[0097] Fourth optical path: The image light is diffracted by a first diffraction grating with a groove parallel to the y-axis, causing the image light to extend in a direction at -90° to the y-axis and propagate toward the fourth steering grating 36. After encountering the fourth steering grating 36, the image light is diffracted and propagates toward the fifth steering grating 37. After encountering the fifth steering grating 37, the image light is diffracted and propagates toward the sixth steering grating 38. After encountering the sixth steering grating 38, the image light is diffracted and propagates toward the output diffraction grating 32. After encountering the output diffraction grating 32, the image light is diffracted by a second diffraction grating with a groove parallel to the x-axis, causing the image light to couple out toward the viewer from the waveguide 30.

[0098] Fifth optical path: The image light is diffracted by a first diffraction grating with a groove parallel to the y-axis, causing the image light to extend in a direction at -90° to the y-axis. Then, the image light is diffracted by a second diffraction grating with a groove parallel to the x-axis, causing the image light to extend in a direction at -180° to the y-axis and propagate toward the sixth steering grating 38. After encountering the sixth steering grating 38, the image light is diffracted and propagates toward the fifth steering grating 37. After encountering the fifth steering grating 37, the image light is diffracted and propagates toward the fourth steering grating 36. After encountering the fourth steering grating 36, the image light is diffracted and propagates toward the output diffraction grating 32. After encountering the output diffraction grating 32, the image light is diffracted by a first diffraction grating with a groove parallel to the y-axis, causing the image light to couple out of the waveguide 30 toward the viewer.

[0099] Sixth optical path: The image light is diffracted by a second diffraction grating with a groove parallel to the x-axis, so that the image light is directly coupled out of the waveguide 30 toward the viewer.

[0100] Please see Figure 7 and Figure 8 , Figure 7 and Figure 8 yes Figure 6The diagram shows a combination of two sets of grating vectors for a diffractive waveguide optical element.

[0101] Figure 7 The grating vectors of the diffraction interaction along the second and third optical paths are shown. Figure 8 The grating vectors of the diffraction interaction along the fourth and fifth optical paths are shown.

[0102] The fourth optical path (i.e., path 4 in the diagram) is a mirror image of the second optical path (i.e., path 2 in the diagram), and the fifth optical path (i.e., path 5 in the diagram) is a mirror image of the third optical path (i.e., path 3 in the diagram).

[0103] The individual grating vectors are added together to produce a composite vector of size zero, representing a sequence of diffraction interactions that can provide a coupling stage toward the viewer with minimal angular and chromatic aberration.

[0104] Furthermore, the present invention also provides a near-eye display device, including a microdisplay and the aforementioned diffractive waveguide optical element; the microdisplay outputs image light. Details will not be elaborated here; please refer to the above embodiments for specific information.

[0105] The present invention provides a diffractive waveguide optical element and a near-eye display device, comprising a waveguide and an input diffraction grating, an output diffraction grating, and a steering combination element disposed on the waveguide. The input diffraction grating receives image light from a microdisplay and couples the image light into the waveguide, causing the image light to propagate within the waveguide by total internal reflection. The output diffraction grating couples out the image light propagating within the waveguide by total internal reflection. The steering combination element adjusts the image light transmitted out of the output diffraction grating region, and the adjusted image light is re-injected into the output diffraction grating. Through this method, the diffractive waveguide optical element of the present invention, via the steering combination element, can utilize the light transmitted out of the output diffraction grating region, and after light deflection, re-inject into the output diffraction grating, thereby improving the contrast of the augmented reality image coupled from the output diffraction grating towards the viewer and improving the uniformity of the diffraction waveguide's pupil.

[0106] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention 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; and these 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 the present invention.

Claims

1. A diffractive waveguide optical element, characterized in that, include: A waveguide and an input diffraction grating, an output diffraction grating, and a steering combination element disposed on the waveguide; The input diffraction grating receives image light from the microdisplay and couples the image light into the waveguide; the image light propagates within the waveguide by total internal reflection. The output diffraction grating couples out the image light rays within the waveguide; The steering combination element adjusts the image light transmitted out of the output diffraction grating region, and the adjusted image light re-enters the output diffraction grating; The image light rays, after being deflected by the deflection assembly element, do not return along the original path; the optical path of the image light rays from the output diffraction grating to the deflection assembly element and the optical path from the deflection assembly element to the output diffraction grating do not overlap. The steering assembly includes a first steering element, a second steering element, a third steering element, a fourth steering element, a fifth steering element, and a sixth steering element; The first steering element, the third steering element, the fourth steering element, and the sixth steering element receive the image light and redirect the redirected image light to the output diffraction grating. Wherein, the image light rays in the first steering element and the image light rays in the fourth steering element propagate along the first direction or the second direction, the image light rays in the third steering element and the image light rays in the sixth steering element propagate along the third direction or the fourth direction, and the second steering element and the fifth steering element turn the image light rays in the first direction into image light rays in the third direction, and convert the image light rays in the fourth direction into image light rays in the second direction; Wherein, the first direction is opposite to the second direction, and the third direction is opposite to the fourth direction; The first steering element receives the image light rays passing through the output diffraction grating and propagates the image light rays along the first direction to the second steering element; the second steering element adjusts the image light rays to be incident on the third steering element along a third direction; the third steering element adjusts the image light rays to be re-incident on the output diffraction grating; The third steering element receives the image light passing through the output diffraction grating and propagates the image light along the fourth direction to the second steering element; the second steering element adjusts the image light to be incident on the first steering element along the second direction; the first steering element adjusts the image light to be re-incident on the output diffraction grating. The fourth steering element receives the image light passing through the output diffraction grating and propagates the image light along the first direction to the fifth steering element; the fifth steering element adjusts the image light to be incident on the sixth steering element along the fourth direction; the sixth steering element adjusts the image light to be re-incident on the output diffraction grating. The sixth steering element receives the image light passing through the output diffraction grating and propagates the image light along the third direction to the fifth steering element. The fifth steering element adjusts the image light to be incident on the fourth steering element along the second direction. The fourth steering element adjusts the image light to be re-incident on the output diffraction grating.

2. The diffractive waveguide optical element according to claim 1, characterized in that, The first steering element is a first steering grating, the second steering element is a second steering grating, the third steering element is a third steering grating, the fourth steering element is a fourth steering grating, the fifth steering element is a fifth steering grating, and the sixth steering element is a sixth steering grating.

3. The diffractive waveguide optical element according to claim 2, characterized in that, The first steering grating includes an oriented groove at a first preset angle to the vertical axis; the second steering grating includes an oriented groove at a second preset angle to the vertical axis; the third steering grating includes an oriented groove at a third preset angle to the vertical axis; the fourth steering grating includes an oriented groove at a fourth preset angle to the vertical axis; the fifth steering grating includes an oriented groove at a fifth preset angle to the vertical axis; and the sixth steering grating includes an oriented groove at a sixth preset angle to the vertical axis.

4. The diffractive waveguide optical element according to claim 3, characterized in that, The output diffraction grating includes a first diffraction grating and a second diffraction grating that overlap each other. The first diffraction grating includes multiple diffraction optical structures, and the diffraction optical structures of the first diffraction grating are oriented at a seventh preset angle to the vertical axis. The second diffraction grating includes multiple diffraction optical structures, and the diffraction optical structures of the second diffraction grating are oriented at an eighth preset angle to the vertical axis.

5. The diffractive waveguide optical element according to claim 4, characterized in that, The sum of the first preset angle and the fourth preset angle is zero, the sum of the second preset angle and the fifth preset angle is zero, the sum of the third preset angle and the sixth preset angle is zero, and the sum of the seventh preset angle and the eighth preset angle is zero.

6. The diffractive waveguide optical element according to claim 5, characterized in that, The first preset angle is -30°, the second preset angle is +45°, the third preset angle is -45°, the fourth preset angle is +30°, the fifth preset angle is -45°, the sixth preset angle is +45°, the seventh preset angle is -30°, and the eighth preset angle is +30°.

7. The diffractive waveguide optical element according to claim 5, characterized in that, The first preset angle is -45°, the second preset angle is +45°, the third preset angle is -45°, the fourth preset angle is +45°, the fifth preset angle is -45°, the sixth preset angle is +45°, the seventh preset angle is 0°, and the eighth preset angle is 90°.

8. The diffractive waveguide optical element according to claim 1, characterized in that, A portion of the image light coupled to the human eye passes through the input diffraction grating, the output diffraction grating, and the steering combination element. The grating vectors of the input diffraction grating, the output diffraction grating, and the steering combination element are combined to produce a composite vector with a magnitude of zero.

9. A near-eye display device, characterized in that, It includes a microdisplay and a diffractive waveguide optical element as described in any one of claims 1-8; the microdisplay outputs image light.

Images