Diffraction optical waveguide module and AR device

Abstract

The invention relates to the technical field of optical equipment, and discloses a diffraction optical waveguide module and an AR device. The diffractive optical waveguide module comprises a diffractive optical waveguide substrate, and a coupling-in grating region, a turning grating region and a coupling-out grating region which are sequentially arranged on the diffractive optical waveguide substrate along a first linear direction; the coupling-in grating region is arranged in the upper half region of the diffractive optical waveguide substrate and is close to the side edge of the upper end part of the turning grating region; wherein the turning grating area is a one-dimensional grating. According to the diffraction optical waveguide module, efficient pupil expansion and diffraction efficiency of the turning grating area are achieved, the lighting effect of the whole diffraction optical waveguide is improved, and therefore the problems of imaging definition, image brightness, rainbow lines and the like in the prior art are solved.

Description

Technical Field

[0001] The present application belongs to the technical field of optical equipment, and specifically relates to a diffraction optical waveguide module and an AR device. Background Art

[0002] With the rapid development of augmented reality (AR) technology, AR display devices such as AR glasses are becoming increasingly popular. In these devices, optical waveguide structures are key components for image display. Existing optical waveguide structure solutions primarily include surface relief, volume holography, and arrayed waveguides.

[0003] The traditional optical waveguide structure combines refractive and diffractive hybrid optical waveguides, that is, it simultaneously adopts the two optical technology routes of "geometric array optical waveguide" and "diffraction optical waveguide". The geometric optical surfaces of the "geometric array optical waveguide" are used in both the coupling-in area and the coupling-out area. To compensate for the shortcoming of the small exit pupil of the geometric array optical waveguide, it is necessary to add a turning diffraction grating area to the geometric array optical waveguide, which makes the structural layout more complex and the cost high.

[0004] To improve pupil dilation and reduce costs, diffraction waveguide technology is currently being used. Diffraction waveguide technology is favored by the market for its large exit pupil, light weight, near-realistic eyewear form, and high mass production capabilities, resulting in widespread acceptance. Diffraction waveguide technology represents a fundamentally different optical technology from the traditional hybrid refractive and diffraction waveguide technology. However, several challenges remain. These include reduced contrast (impaired image clarity) caused by local defects accidentally introduced during large-scale fabrication of the diffraction microstructures; low overall optical efficiency resulting in low display brightness (dim when viewed outdoors during daylight); and rainbow patterns caused by ambient light transmission within the diffraction waveguide. These issues negatively impact the use of diffraction waveguides, severely impacting the user experience. Summary of the Invention

[0005] The purpose of this application is to provide a diffraction light waveguide module and an AR device to solve the problems of imaging clarity, picture brightness and rainbow patterns existing in the existing diffraction light waveguide technology.

[0006] To achieve the above-mentioned object, the present application provides a diffraction optical waveguide module in a first aspect, comprising a diffraction optical waveguide substrate and an incoupling grating region, a turning grating region, and an outcoupling grating region sequentially arranged on the diffraction optical waveguide substrate along a first straight line direction; The coupling-in grating region is arranged in the upper half of the diffraction optical waveguide substrate and close to the side edge of the upper end of the turning grating region; Wherein, the turning grating region is a one-dimensional grating.

[0007] In some embodiments, the coupling-in grating region has a first grating vector, the turning grating region has a second grating vector, and the coupling-out grating region has a third grating vector; The first grating vector, the second grating vector, and the third grating vector may form a grating vector pattern of a quadrilateral structure after translation, wherein the angle formed between the first grating vector and the second grating vector in the grating vector pattern ranges from 105° to 145°, and the angle formed between the first grating vector and the third grating vector ranges from 0° to 45°.

[0008] In some embodiments, at least one turning grating region is provided on the surface of at least one side of the diffraction optical waveguide substrate along its thickness direction; and / or All gratings in the transition grating region have the same period and the same second grating vector.

[0009] In some embodiments, at least two turning grating regions are provided on the surface of the diffraction optical waveguide substrate, and the at least two turning grating regions include a first turning region and a second turning region, the first turning region and the second turning region are arranged along a second straight line direction, and the first turning region is located above the second turning region, wherein the diffraction efficiency of the first turning region is greater than the diffraction efficiency of the second turning region; and / or The turning grating region can be divided into a plurality of sub-regions, and the grating heights and duty cycles of the plurality of sub-regions are designed to be different; And / or, at least one of the coupling-in grating region and the coupling-out grating region is a one-dimensional grating.

[0010] In some embodiments, the turning grating region is a polygonal structure; The turning grating region includes a first side and a second side located in the first straight line direction, the first side is close to the coupling-in grating region, and the second side is close to the coupling-out grating region; The turning grating area also includes a third side and a fourth side located in the second straight line direction, the third side is located in the upper half of the diffraction light waveguide substrate, and the fourth side is located in the lower half of the diffraction light waveguide substrate; wherein the first straight line direction is perpendicular to the second straight line direction.

[0011] In some embodiments, the distance between the ends of the first side and the second side located in the upper half of the diffractive optical waveguide substrate is Dh, and the following conditions are met:

[0012] Wherein, Thi is the thickness of the diffraction optical waveguide substrate, n is the refractive index of the material, is the period of the grating in the coupling grating region, λ is the wavelength of the diffracted light, and HFOV is the lateral field angle of the image.

[0013] In some embodiments, the distance between the ends of the first side and the second side located in the lower half of the diffractive optical waveguide substrate is Dv, and the following conditions are met:

[0014] Wherein, Dh is the distance between the ends of the first side and the second side located in the upper half of the diffraction optical waveguide substrate, n is the refractive index of the material, is the period of the grating in the coupling grating region, λ is the wavelength of the diffracted light, and VFOV is the longitudinal field angle of the image.

[0015] In some embodiments, the maximum length from the third side to the fourth side is H, and satisfies the following conditions:

[0016] Where, Thi is the thickness of the diffraction waveguide substrate, n is the refractive index of the material, is the period of the grating in the coupling grating region, λ is the wavelength of the diffracted light, and VFOV is the longitudinal field angle of the image.

[0017] In some embodiments, the longitudinal length of the first side is d1, the width of the fourth side is d2, and d1 and d2 respectively meet the following conditions: ,

[0018] Wherein, H is the maximum length from the third side to the fourth side, and Dv is the distance between the ends of the first side and the second side located in the lower half of the diffractive optical waveguide substrate; And / or, an oblique side edge is further provided between the fourth side edge and the first side edge.

[0019] The second aspect of the present application further provides an AR device, comprising the diffraction optical waveguide module provided according to the first aspect.

[0020] Compared with the prior art, the diffraction optical waveguide module and AR device provided in this embodiment have at least the following beneficial effects: The diffraction waveguide module provided by the present application is based on the optical technology route of the diffraction waveguide, wherein the coupling-in grating area, the turning grating area and the coupling-out grating area are arranged in sequence in a first straight line direction on the diffraction waveguide substrate, and the coupling-in grating area is arranged in the upper half of the diffraction waveguide substrate and close to the side edge of the upper end of the turning grating area; wherein, after the light enters the coupling-in grating area, it can continue to transmit forward and downward, enter the turning grating area for uniform pupil expansion, and the pupil-expanded light emitted from the turning grating area can cover the entire coupling-out grating area from top to bottom, and The turning grating area is placed between the coupling-in grating area and the coupling-out grating area, so that the coupling-in grating area, the turning grating area and the coupling-out grating area do not need to be arranged symmetrically along the X-axis. At the same time, the turning grating area adopts a one-dimensional grating, which can ensure that the light path of the light coupled into the grating area after entering the turning grating area continues to propagate forward while splitting and propagating downward. In this way, while reducing costs, efficient pupil expansion and diffraction efficiency of the turning grating area can be achieved, and the light efficiency of the entire diffraction light waveguide can be improved, thereby solving the problems of imaging clarity, picture brightness and rainbow patterns in the existing technology.

[0021] Furthermore, the coupling-in grating region, the turning grating region and the coupling-out grating region have a more reasonable structural layout and a simpler structure, which can meet the requirements of free cutting of different small sizes.

[0022] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without inventive work. In the drawings: Figure 1 A schematic structural diagram of the first diffraction optical waveguide module provided in an embodiment of the present application; Figure 2 for Figure 1 Schematic diagrams of three different structures of diffractive optical waveguide modules (a), (b), and (c) derived from the diffractive optical waveguide module shown; Figure 3 A schematic structural diagram of a second diffraction optical waveguide module provided in an embodiment of the present application; Figure 4 A grating vector diagram of a quadrilateral structure formed by translating the first grating vector, the second grating vector, and the third grating vector in a diffraction optical waveguide module is provided for an embodiment of the present application; Figure 5A schematic structural diagram of a third diffraction optical waveguide module provided in an embodiment of the present application; Figure 6 for Figure 5 A schematic structural diagram of the turning grating region in the diffraction optical waveguide module shown; Figure 7 Schematic diagram comparing the transmission and pupil expansion of marginal light in the traditional optical waveguide module (a) provided in an embodiment of the present application and the diffraction optical waveguide module (b) provided in this embodiment.

[0024] Description of Reference Numerals 100. Diffractive optical waveguide substrate; 200, coupling into the grating region; 300, turning grating area; 301, first side; 302, second side; 303, third side; 304, fourth side; 305, oblique side; 310, first sub-region; 320, second sub-region; 400, outcoupling grating region; A, first grating vector; B, second grating vector; C, third grating vector; x, first straight line direction; y, second straight line direction. DETAILED DESCRIPTION

[0025] The following describes the specific embodiments of the present application in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application and are not intended to limit the present application.

[0026] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with exemplary embodiments.

[0027] Example 1 See also Figure 1 and Figure 2 This embodiment provides a diffraction light waveguide module that can be used in AR devices to achieve large pupil expansion, improve the light efficiency of the entire diffraction light waveguide, make imaging clearer and increase picture brightness.

[0028] The diffractive optical waveguide module provided in this embodiment includes a diffractive optical waveguide substrate 100 and an incoupling grating region 200, a turning grating region 300, and an outcoupling grating region 400 sequentially arranged on the diffractive optical waveguide substrate 100 along a first linear direction x. In other words, the turning grating region 300 is arranged between the incoupling grating region 200 and the outcoupling grating region 400.

[0029] Optionally, the diffraction waveguide substrate 100 can be made of glass, resin or other optical materials.

[0030] The coupling-in grating region 200 is located in the upper half of the diffractive waveguide substrate 100, near the side edge of the upper end of the turning grating region 300. A coupling-in grating is disposed within the coupling-in grating region 200. It is understood that the coupling-in grating is used to diffract and couple light from an image source, such as a micro-projector, into the diffractive waveguide substrate 100, where it is then transmitted to the turning grating region 300 via total internal reflection within the diffractive waveguide substrate 100.

[0031] A turning grating is provided in the turning grating region 300 , and the turning grating is used to re-diffract and split the light from the coupled-in grating region 200 to achieve a pupil expansion effect. The re-diffracted light continues to propagate by total reflection in the diffraction waveguide substrate 100 .

[0032] The outcoupling grating region 400 is provided with an outcoupling grating. The light beam from the turning grating region 300, after being expanded, is diffracted by the outcoupling grating to refract the pupil and reflect the expanded pupil. The diffracted light beam refracting the pupil points to the exit pupil area, and the light beam reflecting the expanded pupil continues to propagate through total reflection within the diffraction waveguide substrate 100 to achieve another pupil expansion.

[0033] In some embodiments, the turning grating region 300 can be configured as a polygon (or similar to a polygon) and divided into several subregions, each of which is provided with a turning grating. The turning grating region 300 is used to re-diffract and split the light coupled into the grating region 200 multiple times to enhance pupil expansion.

[0034] Optionally, the polygon may be a trapezoid, a rectangle, or some irregular quadrilaterals.

[0035] In some embodiments, the outcoupling grating region 400 can be configured as a polygon (or similar to a polygon), and can be divided into several sub-regions, each of which is provided with an outcoupling grating. Thus, the light beam from the turning grating region 300, after pupil expansion, is diffracted multiple times by the outcoupling grating, resulting in both refracted and reflected pupil expansion.

[0036] The turning grating region 300 is a one-dimensional grating.

[0037] The diffraction optical waveguide module provided in this embodiment can continue to transmit forward and downward after the light enters the coupling-in grating area 200, and enter the turning grating area 300 for uniform pupil expansion. The light after pupil expansion emitted from the turning grating area 300 can cover the entire coupling-out grating area 400 from top to bottom, and the turning grating area 300 is placed between the coupling-in grating area 200 and the coupling-out grating area 400. There is no need to set the coupling-in grating area 200 to be symmetrical with the turning grating area 300 and the coupling-out grating area 400 along the Y direction (an asymmetrical setting is adopted). In other words, the coupling-in grating area 200, the turning grating area 300 and the coupling-out grating area 400 are symmetrical along the Y direction. The out-coupling grating regions 400 do not need to be arranged symmetrically along the X-axis. At the same time, the turning grating region 300 adopts a one-dimensional grating, which can ensure that the light coupled into the grating region 200 and the light path of the turning grating region 300 continue to propagate forward while being split and propagated downward. In this way, while reducing costs, the light vectors of the light are diffused and propagated multiple times inside the turning grating region 300, achieving a pupil expansion effect. In addition, due to the intensive diffusion and propagation, the utilization rate of the light is improved, thereby significantly improving the comprehensive light efficiency of the entire diffraction optical waveguide module, thereby solving the problems of imaging clarity, picture brightness and rainbow patterns in the prior art.

[0038] See also Figure 7 ,like Figure 7 (a) illustrates the transmission and pupil expansion of edge light in a traditional layout structure. In the trapezoidal turning area, the pupil expansion times of the upper and lower light rays generally do not exceed 5 times. At this time, if the exit pupil is expanded, it will lead to insufficient light, and the effective light will not be evenly distributed in the exit pupil. Therefore, the exit pupil is relatively small under limited size. Figure 7 (b) illustrates the transmission and pupil expansion of two edge rays of the layout structure of this application. Figure 7 The light indicated by the arrow in Figure (b) undergoes four pupil expansions. Because the vectors in the turning grating area 300 of this design are recycled twice, the number of pupil expansions for the same area is more than three times that of the conventional layout on the left. This allows for a larger exit pupil while ensuring uniform light.

[0039] Furthermore, the coupling-in grating region 200 , the turning grating region 300 and the coupling-out grating region 400 have a more reasonable structural layout and a simpler structure, and can be freely cut to different small sizes.

[0040] Furthermore, the coupling-in grating region 200 and the coupling-out grating region 400 may be one-dimensional gratings or two-dimensional gratings.

[0041] Example 2 See also Figure 1 and Figure 2This embodiment provides a diffraction optical waveguide module that can be used in AR devices. This embodiment is an improvement based on the technology of the above embodiment 1. Compared with the above embodiment 1, the difference is: In this embodiment, the in-coupling grating region 200, the turning grating region 300, and the out-coupling grating region 400 can be arranged horizontally from left to right (in the first linear direction x) on the diffractive waveguide substrate 100 to meet the left-eye display requirements. Alternatively, they can be arranged horizontally from right to left to meet the right-eye display requirements.

[0042] The coupling-in grating region 200 , the turning grating region 300 and the coupling-out grating region 400 are arranged very compactly, so that they can be cut into a small-sized eyeglass lens shape.

[0043] The coupling-in grating arranged in the coupling-in grating area 200 has a first grating vector A, which can diffract and couple light from a micro-projector or other light source into the optical waveguide substrate. For example, one beam of diffracted light is coupled into the diffraction optical waveguide substrate 100, undergoes total reflection inside the diffraction optical waveguide substrate 100 and is transmitted forward to the turning grating area 300.

[0044] The turning grating region 300 is a one-dimensional diffraction grating having a second grating vector B.

[0045] The outcoupling grating region 400 is a polygon, preferably a rectangle, and has a third grating vector C that forms a certain angle with the second grating vector B. The pupil-expanded light beam from the turning grating region 300 enters the outcoupling grating region 400. The light beam is diffracted by the outcoupling grating on the surface of the outcoupling grating region 400 into multiple diffracted light beams. One effective diffracted light beam maintains the original total internal reflection propagation mode of the incident light and continues forward to be totally reflected within the diffraction waveguide substrate 100. The other effective diffracted light beam is coupled out of the optical waveguide and emitted toward the eyebox of the AR device.

[0046] Please also refer to Figure 4 In this embodiment, the first grating vector A, the second grating vector B, and the third grating vector C can form a grating vector image of a quadrilateral structure after translation, so that the grating vector image is a closed figure.

[0047] It is understandable that the purpose of forming a grating vector diagram with a quadrilateral structure is to make the positions of the turning grating area 300 and the coupling grating area 400 of the diffraction optical waveguide module more flexible, thereby allowing a higher degree of freedom in the design of the appearance of the eyeglass lenses in the AR device; it can greatly improve the current industry problem of severe rainbow patterns in diffraction optical waveguides, or even completely improve it; in addition, on this basis, by slightly adjusting the details of the grating parameters, it can be used to realize the free design of the diffraction optical waveguide coupling image to the human eye angle, thereby improving the use experience of the optical waveguide and enhancing the user experience.

[0048] Optionally, the raster vector image of the quadrilateral structure may be a rectangle, a rhombus, or a parallelogram.

[0049] Furthermore, in the grating vector diagram, the angle formed between the first grating vector A and the second grating vector B ranges from 105° to 145°. Within this range, the direction of the light diffracted from the turning grating area 300 to the outcoupling grating area 400 can be changed more flexibly, making the setting position of the outcoupling grating area 400 more flexible and increasing the design freedom.

[0050] In some embodiments, the angle formed between the first grating vector A and the second grating vector B ranges from 105° to 135°. In other embodiments, the angle formed between the first grating vector A and the second grating vector B ranges from 110° to 130°, further ensuring its flexible design freedom.

[0051] Optionally, the angle formed between the first grating vector A and the second grating vector B may be 112°, 114.5°, 115°, 116.7°, 118°, 119.4°, 120°, 122.6°, 123°, 125.5°, 126°, 128.2°, 129°, or 129.6°. It should be understood that the above is merely an example and is not intended to limit the scope of protection of this application.

[0052] The angle formed between the first grating vector A and the third grating vector C ranges from 0° to 45°. Within this range, on the one hand, it is to enable the K domain constructed by all grating vectors to form a closed shape, corresponding to the angle range between vectors A and B; on the other hand, it is to allow the light emitted from the out-coupling grating area 400 to form some adjustable angles with the light coupled into the grating area 200, thereby enhancing the flexibility of the design and appropriately reducing the rainbow effect.

[0053] In some embodiments, the angle formed between the first grating vector A and the third grating vector C ranges from 3° to 45°. In other embodiments, the angle formed between the first grating vector A and the third grating vector C ranges from 5° to 42°. This further enhances design flexibility and optimizes the rainbow effect.

[0054] Optionally, the angle formed between the first grating vector A and the third grating vector C may be 6°, 8°, 9°, 9.8°, 10.5°, 14.6°, 15°, 17°, 19°, 20.5°, 24°, 28°, 30°, 33°, 35°, 36.9°, 38.2°, 40°, or 41.6°. It should be understood that the above is merely an example and is not intended to limit the scope of protection of this application.

[0055] In some embodiments, at least one turning grating region 300 is provided on at least one side of the surface of the diffractive light waveguide substrate 100 along its thickness direction. That is, the diffractive light waveguide substrate 100 may have a turning grating region 300 provided on one side of its thickness direction, while the other side may not have a turning grating region 300, or both sides may have turning grating regions 300. This increases the number of times light diffuses and propagates within the turning grating region 300, thereby increasing the number of pupil expansions and improving light utilization.

[0056] In other embodiments, at least two turning grating regions 300 are provided on the surface of the diffractive optical waveguide substrate 100. The at least two turning grating regions 300 include a first turning region and a second turning region. The first turning region and the second turning region are arranged along the second linear direction y, with the first turning region located above the second turning region. The diffraction efficiency of the first turning region is greater than that of the second turning region. In this manner, the first turning region is configured as a grating region with high diffraction efficiency.

[0057] It should be noted that when the turning grating region 300 has only one turning region, after the light transmitted from the coupling-in grating region 200 enters the turning grating region 300, some of the light will not enter the coupling-out grating region 400, thereby causing a waste of light energy. However, the turning grating region 300 is set as the first turning region and the second turning region, and the first turning region is set as a grating region with high diffraction efficiency. In this way, the light transmitted from the coupling-in grating region 200 will first enter the first turning region, and the first turning region will allow all the light to turn downward and enter the second turning region, and then enter the coupling-out grating region 400 as a whole, effectively avoiding the waste of light energy and improving the overall efficiency. In addition, the first turning region can use a separate one-dimensional grating to improve the diffraction efficiency of the light propagating to the second turning region, so that the second turning region plays the main role of pupil expansion.

[0058] Optionally, the first turning region and the second turning region have the same grating period and the same second grating vector B. The difference between the first turning region and the second turning region is that the grating height and duty cycle are designed to be different.

[0059] like Figure 3 As shown, in some further embodiments, the turning grating region 300 can be divided into multiple sub-regions, each of which has a different grating height and duty cycle. The multiple sub-regions can be arranged along the second linear direction y. The multiple sub-regions are used to achieve a more rational distribution of the pupil-expanded beam energy. The pupil-expanded beam is still totally reflected within the diffractive optical waveguide substrate 100, with the effective pupil-expanded beam being transmitted toward the outcoupling grating region 400.

[0060] It can be understood that the above-mentioned multiple sub-regions may include a first sub-region 310 and a second sub-region 320, and the first sub-region 310 and the second sub-region 320 may correspond to the above-mentioned first turning zone and second turning zone, and have the same structure and effect as the above-mentioned first turning zone and second turning zone.

[0061] In this embodiment, the polygonal area of the out-coupling grating area 400 can be divided into multiple sub-areas, and the grating heights and duty cycles of the multiple sub-areas can be designed to be different, so as to achieve a second pupil expansion of the light in the out-coupling grating area 400 and redistribute the light energy, so that the effective diffracted light energy emitted to the eye box direction is more uniform.

[0062] Optionally, at least one of the coupling-in grating region 200 and the coupling-out grating region 400 is a one-dimensional grating. It is understood that the manufacturing cost of a one-dimensional grating is lower than that of a two-dimensional grating, and the tolerance for large-scale replication is relatively large, making the one-dimensional grating more cost-effective.

[0063] Example 3 See also Figure 5 and Figure 6 This embodiment provides a diffraction optical waveguide module that can be used in AR devices. This embodiment is an improvement based on the technology of the above-mentioned embodiment 1 or embodiment 2. Compared with the above-mentioned embodiment 1 or embodiment 2, the difference is: In this embodiment, the turning grating region 300 has a polygonal structure. The turning grating region 300 includes a first side 301 and a second side 302 located in a first linear direction x. The first side 301 is adjacent to the incoupling grating region 200, and the second side 302 is adjacent to the outcoupling grating region 400. The turning grating region 300 also includes a third side 303 and a fourth side 304 located in a second linear direction y. The third side 303 is located in the upper half of the diffractive optical waveguide substrate 100, and the fourth side 304 is located in the lower half of the diffractive optical waveguide substrate 100.

[0064] An oblique side 305 (for forming a missing corner portion) is further provided between the fourth side 304 and the first side 301 , and the first straight line direction x is perpendicular to the second straight line direction y.

[0065] Furthermore, the distance between the ends of the first side 301 and the second side 302 located in the upper half of the diffractive optical waveguide substrate 100 is Dh, and the following conditions are met: (1) Wherein, Thi is the thickness of the diffraction optical waveguide substrate 100, n is the refractive index of the material, is the period of the grating coupled into the grating region 200, λ is the wavelength of the diffracted light, and HFOV is the lateral field angle of the image.

[0066] It should be noted that satisfying the relationship in the above formula (1) is conducive to ensuring that the light from the coupling grating area 200 can be fully diffracted and expanded when incident on the turning grating area 300, thereby ensuring the downward expansion of the diffracted light in the turning grating area 300.

[0067] The Dh calculated in the above formula (1) is to allow the coupled light to have at least two transverse (first linear direction x) diffraction pupil expansion times in the turning grating area 300. The calculation involves the maximum angle and the minimum angle of the incident light. These angles are calculated based on the refractive index n, wavelength, coupling grating period, and transverse image field of view HFOV. The other right-angled side of the triangle is calculated in combination with the thickness Thi of the diffraction light waveguide substrate 100 to obtain Dh.

[0068] In some embodiments, the distance between the first side 301 and the second side 302 located at the end of the lower half of the diffractive optical waveguide substrate 100 is Dv, and the following conditions are met:

[0069] Wherein, Dh is the distance between the first side 301 and the second side 302 located in the upper half of the diffraction waveguide substrate 100, n is the refractive index of the material, is the period of the grating coupled into the grating region 200, λ is the wavelength of the diffracted light, and VFOV is the longitudinal field angle of the image.

[0070] It should be noted that satisfying the relationship in formula (2) above is conducive to ensuring that the light is within the turning grating area 300 when the pupil is expanded in the longitudinal direction (the second straight line direction y), which is conducive to improving overall uniformity and reducing light energy loss.

[0071] Among them, the above formula (2) calculates the minimum horizontal dimension Dv below the turning grating area 300. Since the light radiates outward in a trumpet shape after turning downward, the bottom side must be wider than the top side. This tilt angle is also calculated based on the refractive index n, wavelength, coupling grating period, and vertical image field angle VFOV. After obtaining the angle, in order to ensure that the downward diffracted light has at least two horizontal pupil expansion times when it propagates horizontally again, this width is based on Dh plus the part of the angle calculated just now, forming a trapezoid. Therefore, Dv, as the horizontal length, is based on Dh and adds a part of the length. It is necessary to do it at least twice because the turning grating area 300 cannot achieve high efficiency in one go. At least twice is required to ensure high light energy utilization. This is also the reason why the above formula (1) needs to be calculated twice.

[0072] In some embodiments, the maximum length dimension from the third side 303 to the fourth side 304 is H and satisfies the following conditions: (3) Wherein, Thi is the thickness of the diffraction optical waveguide substrate 100, n is the refractive index of the material, is the period of the grating coupled into the grating region 200, λ is the wavelength of the diffracted light, and VFOV is the longitudinal field angle of the image.

[0073] It should be noted that satisfying the relationship in formula (3) above is conducive to ensuring that the number of longitudinal pupil expansions is sufficient for pupil expansion distribution of light energy, thereby improving overall uniformity and light energy utilization.

[0074] According to the calculation conditions of formula (3), the longitudinal pupil expansion of at least four times during downward transmission can be specifically calculated. The angle is again calculated from the refractive index n, wavelength, coupling grating period, and longitudinal image field of view VFOV. After obtaining the angle, the other right-angled side of the right triangle is calculated based on the thickness Thi of the diffraction waveguide base to obtain H. The downward pupil expansion of four times is to fully ensure the uniformity of the pupil expansion of the turning grating area 300 and the wide range of the coupling grating area 400. In other words, this H directly corresponds to the width of the eyebox of the outgoing light. If it is too small, it will be unreasonable and will cause the human eye to not see the entire image.

[0075] In some embodiments, the longitudinal length of the first side 301 is d1, and the width of the fourth side 304 is d2, and d1 and d2 respectively meet the following conditions: , (4) Wherein, H is the maximum length from the third side 303 to the fourth side 304 , and Dv is the distance between the ends of the first side 301 and the second side 302 located in the lower half of the diffractive optical waveguide substrate 100 .

[0076] It should be noted that when the relationship in the above formula (4) is satisfied, the grating area of the turning grating region 300 can be appropriately reduced, which is beneficial to reducing the processing amount and cost of the master while ensuring uniformity and light efficiency.

[0077] As shown in the figure, the lower left corner of the turning grating area 300 is cut off to form a missing corner. If it is not cut off, it will be a quadrilateral. The size range of the cut-off corner is given by the limit of the two sides (first side 301 and second side 302) in formula (4). The limit of the first side 301 and the fourth side 304 is cut in half. Considering that when the first side 301 and the fourth side 304 are cut in half, it just corresponds to half of the VFOV. Since the pupil diffraction efficiency of this part of the VFOV is higher than that of the right half of the VFOV, the pupil expansion times are relatively less and not too much light energy is lost. This diffraction efficiency is caused by the angle difference (this is the efficiency calculation result). After cutting, the area of the turning grating area 300 can be made smaller, saving processing cost and time. Therefore, we cannot cut off half of the lens in all cases. If the eyebox that enters the eye needs to be large, we must cut less to ensure the number of pupil expansions. If the specifications require a smaller eyebox, such as when displaying certain full-color patterns, we can cut more and reduce color deviation.

[0078] Example 4 See also Figures 1 to 7 This embodiment provides an AR device, including a diffraction optical waveguide module provided according to any one of the above-mentioned embodiments 1 to 3.

[0079] Optionally, the AR device is AR glasses, and the coupling-in grating region 200 is located near the temple of the glasses.

[0080] It should be noted that one-dimensional gratings are all stripes, with periodicity in only one direction. Two-dimensional gratings are individual grating columns, and their specific shapes can be cylinders, elliptical cylinders, cuboids, cones, tetrahedrons, etc. Two-dimensional gratings have periodicity in two directions. Therefore, the manufacturing process of two-dimensional gratings is more difficult than that of one-dimensional gratings.

[0081] In this application, unless otherwise specified, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like used to indicate orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting this application.

[0082] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0083] In this application, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0084] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0085] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A diffraction optical waveguide module, characterized in that: It comprises a diffraction light waveguide substrate (100) and an in-coupling grating region (200), a turning grating region (300), and an out-coupling grating region (400) sequentially arranged on the diffraction light waveguide substrate (100) along a first straight line direction (x); The coupling-in grating region (200) is arranged in the upper half of the diffraction light waveguide substrate (100) and close to the side edge of the upper end of the turning grating region (300); Wherein, the turning grating region (300) is a one-dimensional grating.

2. The diffraction optical waveguide module according to claim 1, wherein: The coupling-in grating region (200) has a first grating vector (A), the turning grating region (300) has a second grating vector (B), and the coupling-out grating region (400) has a third grating vector (C); The first grating vector (A), the second grating vector (B) and the third grating vector (C) can form a grating vector pattern of a quadrilateral structure after translation, and the angle formed between the first grating vector (A) and the second grating vector (B) in the grating vector pattern ranges from 105° to 145°, and the angle formed between the first grating vector (A) and the third grating vector (C) ranges from 0° to 45°.

3. The diffraction optical waveguide module according to claim 1, wherein: The diffraction light waveguide substrate (100) is provided with at least one turning grating region (300) on the surface of at least one side along the thickness direction of the diffraction light waveguide substrate (100); and / or All grating periods in the turning grating region (300) are the same and have the same second grating vector (B); And / or, at least one of the coupling-in grating region (200) and the coupling-out grating region (400) is a one-dimensional grating.

4. The diffraction optical waveguide module according to claim 1, wherein: At least two turning grating regions (300) are provided on the surface of the diffraction light waveguide substrate (100), the at least two turning grating regions (300) include a first turning region and a second turning region, the first turning region and the second turning region are arranged along a second straight line direction (y), and the first turning region is located above the second turning region, wherein the diffraction efficiency of the first turning region is greater than the diffraction efficiency of the second turning region; and / or The turning grating region (300) can be divided into a plurality of sub-regions, and the grating heights and duty cycles of the plurality of sub-regions are designed to be different.

5. The diffraction optical waveguide module according to claim 1, wherein: The turning grating area (300) is a polygonal structure; The turning grating region (300) comprises a first side edge (301) and a second side edge (302) located in the first straight line direction (x), the first side edge (301) being close to the coupling-in grating region (200), and the second side edge (302) being close to the coupling-out grating region (400); The turning grating region (300) further includes a third side (303) and a fourth side (304) located in the second straight line direction (y), the third side (303) being located in the upper half of the diffraction light waveguide substrate (100), and the fourth side (304) being located in the lower half of the diffraction light waveguide substrate (100); The first straight line direction (x) is perpendicular to the second straight line direction (y).

6. The diffraction optical waveguide module according to claim 5, characterized in that: The distance between the ends of the first side (301) and the second side (302) located in the upper half of the diffraction light waveguide substrate (100) is Dh, and the following conditions are met: Wherein, Thi is the thickness of the diffraction light waveguide substrate (100), n is the refractive index of the material, is the period of the grating coupled into the grating region (200), λ is the wavelength of the diffracted light, and HFOV is the lateral field angle of the image.

7. The diffraction optical waveguide module according to claim 5, wherein: The distance between the ends of the first side (301) and the second side (302) located in the lower half of the diffraction light waveguide substrate (100) is Dv, and the following conditions are met: Wherein, Dh is the distance between the ends of the first side (301) and the second side (302) located in the upper half of the diffraction light waveguide substrate (100), n is the refractive index of the material, is the period of the grating coupled into the grating region (200), λ is the wavelength of the diffracted light, and VFOV is the longitudinal field angle of the image.

8. The diffraction optical waveguide module according to claim 5, wherein: The maximum length dimension from the third side (303) to the fourth side (304) is H, and satisfies the following conditions: Wherein, Thi is the thickness of the diffraction optical waveguide substrate (100), n is the refractive index of the material, is the period of the grating coupled into the grating region (200), λ is the wavelength of the diffracted light, and VFOV is the longitudinal field angle of the image.

9. The diffraction optical waveguide module according to any one of claims 5 to 8, characterized in that: The longitudinal length dimension of the first side (301) is d1, and the width dimension of the fourth side (304) is d2, and d1 and d2 respectively satisfy the following conditions: , Wherein, H is the maximum length dimension from the third side (303) to the fourth side (304), and Dv is the distance between the ends of the first side (301) and the second side (302) located in the lower half of the diffraction light waveguide substrate (100); And / or, an oblique side edge (305) is further provided between the fourth side edge (304) and the first side edge (301).

10. An AR device, characterized in that: The invention comprises the diffraction optical waveguide module according to any one of claims 1 to 9.

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