Waveguide element
By designing a light pupil dilation region with specific parameter relationships and structures in the waveguide element, the problem of uneven image energy distribution is solved, and more uniform image expansion and screen display is achieved.
Patent Information
- Application Number
- CN202411701999.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-12-08
- Filing Date
- 2024-11-26
- Publication Date
- 2025-01-07
AI Technical Summary
In augmented reality displays, waveguide elements based on diffraction optical elements lead to uneven distribution of image energy during image expansion, especially the farther the image input position, the more serious the image energy decay, affecting the uniformity of the picture.
Design a waveguide element whose optical pupil dilated region has at least two partitions. The angle between the boundary of the partition and the horizontal line is specially calculated to meet specific parameter relationships, including incident light wavelength, viewing angle, refractive index of the substrate and optical coupling. The grating vector direction and period distance, grating height and fill ratio of the region increase and decrease from the optical coupling in the region to the optical coupling out region. The grating period distance is in the range of 300 nanometers to 1200 nanometers, and the refractive index of the substrate and grating is within a specific range. , the viewing angle and incident light wavelength range are in the range of 400 nanometers to 700 nanometers.
Through this design, energy is distributed more evenly when dilating the pupil, improving the uniformity of the picture and enhancing the image display effect.
Smart Images
Figure CN119270418A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a waveguide element. Background Art
[0002] In augmented reality (AR) displays, one of the important technologies is to expand the image using waveguide elements based on diffractive optical elements. Whether expanding the image in one or two dimensions, it helps to make the device more comfortable to wear.
[0003] However, image expansion involves distributing the energy of the image in two-dimensional space. The farther away from the image input, the more serious the decay of the image energy, thus affecting the uniformity of the image. Summary of the invention
[0004] A technical embodiment of the present disclosure is a waveguide element.
[0005] According to one embodiment of the present disclosure, a waveguide element includes a substrate and a grating structure. The grating structure is located on the substrate to form a light coupling-in region, a light coupling-out region and a light pupil expansion region, wherein the light pupil expansion region optically couples the light coupling-in region and the light coupling-out region, the light pupil expansion region is configured to receive light from the light coupling-in region and diffract light toward the light coupling-out region to expand the pupil, the light pupil expansion region has at least two partitions, and the boundary of the partition of the light pupil expansion region has an angle φ with the horizontal line, satisfying Among them, α1=(-λsinψ+αd) / nd, β1=(λcosψ+βd) / nd, α=sin(θ)×cosψ, β=sin(θ)×sinψ, λ is the wavelength of incident light, θ is the viewing angle, n is the refractive index of the substrate, ψ is the grating vector direction of the light coupling area, and d is the grating period distance of the light coupling area.
[0006] In one embodiment of the present disclosure, an angle φ between a boundary of a subarea of the optical pupil expansion area and a horizontal line has an offset, and the offset is less than or equal to 10 degrees.
[0007] In one embodiment of the present disclosure, the grating structure includes a plurality of gratings, and the gratings of the partitions of the light expansion pupil area each have a grating height, and the grating height increases from the partition closest to the light coupling area to the partition farthest from the light coupling area.
[0008] In one embodiment of the present disclosure, the grating height is in the range of 10 nanometers to 300 nanometers.
[0009] In one embodiment of the present disclosure, each of the subareas of the light expansion pupil area has a filling ratio, and the filling ratio decreases from the subarea closest to the light coupling-in area to the subarea farthest from the light coupling-in area.
[0010] In one embodiment of the present disclosure, the grating structure includes a plurality of gratings, the gratings in the light expansion pupil region and the horizontal surface of the substrate have tilt angles respectively, and the tilt angles decrease from the partition closest to the light coupling region to the partition farthest from the light coupling region.
[0011] In one embodiment of the present disclosure, the grating period distance is in the range of 300 nanometers to 1200 nanometers.
[0012] In one embodiment of the present disclosure, the refractive index of the substrate is in the range of 1.5 to 2.5, and the refractive index of the grating structure is in the range of 1.2 to 2.5.
[0013] In one embodiment of the present disclosure, the viewing angle is in the range of 0 degrees to 90 degrees.
[0014] In one embodiment of the present disclosure, the wavelength of the incident light is in the range of 400 nanometers to 700 nanometers.
[0015] In the above-mentioned embodiment of the present disclosure, since the light pupil expansion area has at least two partitions, and the angle between the boundaries of these partitions and the horizontal line is specially calculated, this angle is related to parameters such as the wavelength of the incident light, the viewing angle, the refractive index of the substrate, the grating vector direction of the light coupling area, and the grating period distance of the light coupling area. Therefore, the energy can be distributed more evenly when the pupil is expanded, thereby improving the uniformity of the picture. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] When read together with the accompanying drawings, the embodiments of the present disclosure can be best understood from the following embodiments. Note that according to standard practice in this industry, various features are not drawn to scale. In fact, the size of various features may be arbitrarily increased or reduced for clarity of discussion.
[0017] Figure 1 A top view of a waveguide element according to an embodiment of the present disclosure is shown.
[0018] Figure 2 A side view of a waveguide element and a light source according to an embodiment of the present disclosure is shown.
[0019] Figure 3 Show Figure 1 A partial enlarged top view of the light coupling area of the waveguide element.
[0020] Figure 4 Show Figure 1 A partial enlarged top view of the optical pupil expansion area of the waveguide element.
[0021] Figure 5 and Figure 6 Show Figure 1 A local enlarged cross-sectional view of the grating structure of the waveguide element.
[0022] Figure 7 A top view of a waveguide element and a light source according to another embodiment of the present disclosure is shown.
[0023] Figure 8 A top view showing a waveguide element and a light source according to yet another embodiment of the present disclosure is shown.
[0024] Description of reference numerals:
[0025] 100,100a,100b:Waveguide components
[0026] 110: Substrate
[0027] 120,120a,120b: grating structure
[0028] 122: Optical coupling area
[0029] 124,124a,124b: Optical pupil expansion area
[0030] 125a,125b,125c,125d,125e: Partition
[0031] 126: Optocoupler out of area
[0032] 200: Light source
[0033] φ: Angle
[0034] ψ: vector direction
[0035] d: period distance
[0036] H: Height
[0037] W: Width
[0038] θ: viewing angle
[0039] θ1: Tilt angle
[0040] θ2: Angle DETAILED DESCRIPTION
[0041] The following disclosed embodiments provide many different embodiments, or examples, for implementing the different features of the subject matter provided. Specific examples of components and arrangements are described below to simplify the disclosure. Of course, these examples are only examples and are not intended to be limiting. In addition, the disclosure may repeat element symbols and / or letters in each example. This repetition is used for the purpose of simplicity and clarity, and does not itself specify the relationship between the various embodiments and / or configurations discussed.
[0042] Spatially relative terms such as "below," "beneath," "lower," "above," "upper," and the like may be used herein for descriptive purposes to describe the relationship of one element or feature to another element or feature as illustrated in the accompanying drawings. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation illustrated in the accompanying drawings. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein should likewise be interpreted accordingly.
[0043] Figure 1 FIG. 1 is a top view of a waveguide element 100 according to an embodiment of the present disclosure. Figure 1 A waveguide element 100 includes a substrate 110 and a grating structure 120. The grating structure 120 is located on the substrate 110 to form a light coupling-in region 122, a light pupil expansion region 124, and a light coupling-out region 126, wherein the light pupil expansion region 124 optically couples the light coupling-in region 122 and the light coupling-out region 126. In this embodiment, the light coupling-in region 122 is located at the upper right corner of the waveguide element 100, the light coupling-out region 126 is located at the upper left corner of the waveguide element 100, and the light pupil expansion region 124 is located at the middle and lower part of the waveguide element 100.
[0044] The light pupil expansion area 124 is configured to receive light from the light coupling-in area 122 and diffract the light toward the light coupling-out area 126 to expand the pupil. Figure 1 In the embodiment, the pupil expansion area 124 has five subareas 125a, 125b, 125c, 125d, and 125e, and the boundaries of the subareas 125a, 125b, 125c, 125d, and 125e of the pupil expansion area 124 have an angle φ with the horizontal line, satisfying Wherein, α1=(-λsinψ+αd) / nd, β1=(λcosψ+βd) / nd, α=sin(θ)×cosψ, β=sin(θ)×sinψ, λ is the wavelength of incident light, θ is the viewing angle, n is the refractive index of the substrate 110, ψ is the direction of the grating vector of the light coupling region 122, and d is the grating period distance of the light coupling region 122. The parameters (incident light wavelength, viewing angle, refractive index of the substrate, grating vector direction of the light coupling region, grating period distance of the light coupling region) are determined by the various parts of the waveguide element 100 and the light source used (which will be Figure 2 Details) decision.
[0045] Figure 2 FIG. 2 shows a side view of a waveguide element 100 and a light source 200 according to an embodiment of the present disclosure. Figure 1 and Figure 2When the waveguide element 100 is used to receive an image from the light source 200, the wavelength and the viewing angle (Field of View) of the image are determined by the light source 200. In terms of color display, it can be understood that in order to display images of different colors, the wavelength of the incident light will not be a fixed value, but a range. For example, in some embodiments, the wavelength of the incident light is in the range of 400 nanometers to 700 nanometers. Such a design will cause the calculated angle φ to also be a range, so it can be understood that the angle φ between the boundaries of the subareas 125a, 125b, 125c, 125d, and 125e of the light expansion pupil area 124 and the horizontal line has an offset, and this offset is less than or equal to 10 degrees. In addition, in some embodiments, the viewing angle θ of the incident light is in the range of 0 degrees to 90 degrees. The viewing angle θ is also a design parameter, because the light emitted by the light source 200 must enter the light coupling area 122, and the light coupling area 122 will transmit the light to the light expansion pupil area 124 optically coupled with the light coupling area 122. In addition, the refractive index of the substrate 110 also determines the angle φ. In some embodiments, the refractive index of the substrate 110 is in the range of 1.5 to 2.5. In the following description, the light coupling region 122 of the grating structure 120 will be described in detail.
[0046] Figure 3 Show Figure 1 FIG. 1 is a partial enlarged top view of the light coupling region 122 of the waveguide element 100. Figure 3 When determining the angle φ between the boundary of the subareas 125a, 125b, 125c, 125d, and 125e of the light expansion pupil area 124 and the horizontal line, there are two parameters determined by the light coupling-in area 122, namely, the grating vector direction ψ of the light coupling-in area 122 and the grating period distance d of the light coupling-in area 122. Here, the grating vector direction ψ is the angle between the extension direction of the slits of the grating and the horizontal line, and the horizontal line is the same as or parallel to the horizontal line described by the above angle φ, and the period distance d refers to the distance that the grating repeats once. In some embodiments, the grating period distance d is in the range of 300 nanometers to 1200 nanometers. In addition, in some embodiments, the grating vector direction ψ is in the range of 0 degrees to 360 degrees. Different from the above-mentioned wavelength of the incident light, the grating vector direction ψ and the grating period distance d of the light coupling-in area 122 will be fixed values after the design of the light coupling-in area 122 is completed. In the following description, the optical pupil expansion region 124 of the grating structure 120 will be described in detail.
[0047] Figure 4 Show Figure 1 A partial enlarged top view of the optical pupil expansion region 124 of the waveguide element 100 is shown. Figure 5 and Figure 6 Show Figure 1 FIG. 1 is a partially enlarged cross-sectional view of the partitions 125a and 125b in the grating structure 120 of the waveguide element 100. Figure 4 , Figure 5 and Figure 6 When partitioning, there are several ways to separate each partition 125a, 125b, 125c, 125d, 125e so that each partition 125a, 125b, 125c, 125d, 125e has different optical properties. The angle φ between the boundary of the partitions 125a, 125b, 125c, 125d, 125e and the horizontal line is different from the angle θ2 between the grating and the horizontal line. They are two independent parameters and are described first. In some embodiments, the gratings of the partitions 125a, 125b, 125c, 125d, 125e of the light expansion pupil area 124 each have a grating height H, and the grating height H increases from the partition 125a closest to the light coupling area 122 to the partition 125e farthest from the light coupling area 122.
[0048] Furthermore, in some embodiments, each of the sub-regions 125a, 125b, 125c, 125d, and 125e of the light expansion pupil region 124 has a filling ratio, and the filling ratio decreases from the sub-region 125a closest to the light coupling region 122 to the sub-region 125e farthest from the light coupling region 122. The so-called "filling ratio" herein refers to the grating width W divided by the grating period distance d, which means that the wider the line width of the grating, the higher the filling ratio. Furthermore, in some embodiments, the grating structure 120 includes a plurality of gratings, and the gratings of the light expansion pupil region 124 have a tilt angle θ1 with the horizontal surface of the substrate 110, respectively, and the tilt angle θ1 decreases from the sub-region 125a closest to the light coupling region 122 to the sub-region 125e farthest from the light coupling region 122. Such a design makes the refractive index distribution of each of the subareas 125a, 125b, 125c, 125d, 125e of the light expansion pupil area 124 discontinuous, so that the energy of the incident light can be released in batches to the light outcoupling area 126. In some embodiments, the refractive index of the grating structure 120 is in the range of 1.2 to 2.5.
[0049] Since the light pupil expansion area 124 has partitions 125a, 125b, 125c, 125d, and 125e, and the angles between the boundaries of these partitions 125a, 125b, 125c, 125d, and 125e and the horizontal line are specially calculated, and this angle is related to parameters such as the wavelength of incident light, the viewing angle θ, the refractive index of the substrate 110, the grating vector direction ψ of the light coupling-in area 122, and the grating period distance d of the light coupling-in area 122, the energy can be distributed more evenly when the pupil is expanded, thereby improving the uniformity of the picture.
[0050] Figure 7 FIG. 2 is a top view of a waveguide element 100a and a light source 200 according to another embodiment of the present disclosure. Figure 7A waveguide element 100a includes a substrate 110 and a grating structure 120a. The grating structure 120a is located on the substrate 110 to form a light coupling-in region 122, a light coupling-out region 126 and a light pupil expansion region 124a, wherein the light pupil expansion region 124a optically couples the light coupling-in region 122 and the light coupling-out region 126. Figure 1 The difference between the embodiment of the present invention and the embodiment of the present invention lies in the arrangement of the positions of the light outcoupling area 126 and the light pupil expansion area 124a of the grating structure 120a. The light outcoupling area 126 is located at the lower left corner and the lower middle of the waveguide element 100a, and the light pupil expansion area 124a is located at the upper left corner and the upper middle of the waveguide element 100a. In addition, the light source 200 of this embodiment is a single wavelength light source with a fixed wavelength of 550 nanometers. The wavelength and other parameters are shown in Table 1:
[0051] parameter Numeric Incident light wavelength 550 nm Viewing angle 40 degrees Substrate refractive index 1.89 Grating vector direction in the light coupling region 90 degrees Grating period distance in the light coupling region 300 nm Angle φ(calculated) -19.3 degrees
[0052] Table 1
[0053] In this embodiment, the sub-areas 125a, 125b, 125c, 125d, and 125e of the pupil expansion area 124a are distinguished by the grating height H of the grating in each sub-area 125a, 125b, 125c, 125d, and 125e. In this embodiment, the grating heights of the five sub-areas 125a, 125b, 125c, 125d, and 125e are 5 nanometers, 15 nanometers, 60 nanometers, 90 nanometers, and 120 nanometers, respectively.
[0054] Figure 8 FIG. 2 is a top view showing a waveguide element 100 b and a light source 200 according to another embodiment of the present disclosure. Figure 8 , a waveguide element 100a includes a substrate 110 and a grating structure 120b. The grating structure 120 is located on the substrate 110 to form a light coupling-in region 122, a light coupling-out region 126 and a light pupil expansion region 124b, wherein the light pupil expansion region 124b optically couples the light coupling-in region 122 and the light coupling-out region 126. Figure 1 The difference between the embodiment of the present invention is that, in the present embodiment, the pupil expansion area 124b has only four subareas 125a, 125b, 125c, and 125d. In addition, the light source 200 of the present embodiment is a light source 200 that can emit multiple wavelengths. The design parameters of the present embodiment are as shown in Table 2:
[0055] parameter Numeric Incident light wavelength 460nm, 525nm, 625nm Viewing angle 30 degrees Substrate refractive index 1.817 Grating vector direction in the light coupling region 130 degrees Grating period distance in the light coupling region 350 nm Angle φ(calculated) 22 degrees (calculated at 525 nanometers) Offset 5 degrees
[0056] Table 2
[0057] In this embodiment, the sub-areas 125a, 125b, 125c, and 125d of the pupil expansion area 124b are distinguished by the grating height H of the grating in each sub-area 125a, 125b, 125c, and 125d. In this embodiment, the grating heights of the four sub-areas 125a, 125b, 125c, and 125d are 20 nanometers, 40 nanometers, 60 nanometers, and 80 nanometers, respectively.
[0058] The foregoing summarizes the features of several embodiments so that those skilled in the art can better understand the embodiments of the present disclosure. Those skilled in the art should understand that they can easily use the present disclosure as a basis for designing or modifying other processes and structures to achieve the same purpose and / or achieve the same advantages as the embodiments described herein. Those skilled in the art should also recognize that such equivalent constructions do not depart from the concept and scope of the present disclosure, and that they can make various changes, substitutions and modifications here without departing from the concept and scope of the present disclosure.
Claims
1. A waveguide element, comprising: a substrate; and A grating structure is located on the substrate to form a light coupling-in area, a light coupling-out area and a light pupil expansion area, wherein the light pupil expansion area optically couples the light coupling-in area and the light coupling-out area, and the light pupil expansion area is configured to receive light from the light coupling-in area and diffract it toward the light coupling-out area to expand the pupil, and the light pupil expansion area has at least two subareas, and the boundaries of the subareas of the light pupil expansion area have an angle φ with a horizontal line, satisfying Wherein α1=(-λsinψ+αd) / nd, β1=(λcosψ+βd) / ndα=sin(θ)×cosψ, β=sin(θ)×sinψ, λ is the wavelength of incident light, θ is a viewing angle, n is a refractive index of the substrate, ψ is a grating vector direction of the light coupling region, and d is a grating period distance of the light coupling region.
2. The waveguide element as claimed in claim 1, wherein the angle φ between the boundaries of the subareas of the optical pupil expansion area and the horizontal line has an offset, and the offset is less than or equal to 10 degrees.
3. The waveguide element as claimed in claim 1, wherein the grating structure comprises a plurality of gratings, the gratings of the partitions of the light expansion pupil region each having a grating height, and the grating heights increase from the partition closest to the light coupling region to the partition farthest from the light coupling region.
4. The waveguide device as claimed in claim 3, wherein the grating heights are in the range of 10 nm to 300 nm.
5. The waveguide device as claimed in claim 1, wherein each of the sub-regions of the light expansion pupil region has a filling ratio, and the filling ratios decrease from the sub-region closest to the light coupling region to the sub-region farthest from the light coupling region.
6. The waveguide element as claimed in claim 1, wherein the grating structure comprises a plurality of gratings, the gratings in the light expansion pupil region respectively have a tilt angle with respect to the horizontal line, and the tilt angles decrease from the partition closest to the light coupling region to the partition farthest from the light coupling region.
7. The waveguide element of claim 1, wherein the grating period distance is in the range of 300 nanometers to 1200 nanometers.
8. The waveguide element as claimed in claim 1, wherein the refractive index of the substrate is in the range of 1.5 to 2.5, and a refractive index of the grating structure is in the range of 1.2 to 2.
5.
9. The waveguide element of claim 1, wherein the viewing angle is in the range of 0 degrees to 90 degrees.
10. The waveguide element of claim 1, wherein the incident light wavelength is in the range of 400 nanometers to 700 nanometers.