CN115808732A - Two-dimensional diffraction grating, two-dimensional diffraction optical waveguide, and near-eye display device - Google Patents
Two-dimensional diffraction grating, two-dimensional diffraction optical waveguide, and near-eye display device Download PDFInfo
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Abstract
The invention provides a two-dimensional diffraction grating, a two-dimensional diffraction optical waveguide and near-to-eye display equipment, and relates to the technical field of optical waveguide display. The two-dimensional diffraction grating includes: the optical structures are in open circular ring shapes, the inner diameters of the optical structures are the same, and the outer diameters of the optical structures are the same; the optical structures are respectively arranged in a first direction and a second direction at equal intervals, and an included angle between the first direction and the second direction is larger than 20 degrees and smaller than 160 degrees. According to the two-dimensional diffraction grating, the two-dimensional diffraction optical waveguide and the near-to-eye display device, the optical structures with the plurality of opening circular rings are adopted, and the rotating angles and the opening angles of the optical structures are adjusted, so that the exit pupil uniformity of the two-dimensional diffraction optical waveguide can be improved, and the processing difficulty of the two-dimensional diffraction optical waveguide can be reduced.
Description
Technical Field
The invention relates to the technical field of optical waveguides, in particular to a two-dimensional diffraction grating, a two-dimensional diffraction optical waveguide and near-to-eye display equipment.
Background
Augmented Reality (AR) technology is a technology that fuses computer-generated virtual information with the real world. The AR near-to-eye display device represented by AR glasses transfers the picture of the microdisplay to the human eye through a series of optical imaging elements, and the perspective characteristic of the AR near-to-eye display device enables real scenery to be simultaneously reflected to the human eye, so that the real experience is greatly enhanced. The existing relatively mature optical imaging scheme mainly comprises a prism, a free-form surface, an off-axis holographic lens, an array waveguide, a volume holographic grating waveguide, a diffraction grating waveguide and the like. The diffraction grating waveguide mainly utilizes photoetching technology to manufacture surface relief gratings on the surface of the waveguide to realize the coupling-in and coupling-out of images, the field angle is large, the waveguide weight is light, the process is compatible with the mature manufacturing technology in the semiconductor industry, and the yield of batch production is high. Therefore, a diffraction grating waveguide is a favored AR display optical imaging solution.
The two-dimensional diffraction grating waveguide adopts two areas, namely a one-dimensional coupling-in grating and a two-dimensional coupling-out grating, and the coupling-out grating area has the functions of expanding and coupling out at the same time, but the exit pupil uniformity and the field uniformity of the two-dimensional diffraction grating waveguide are a great challenge. In the process of the light beam propagating in the coupling-out grating region, part of the light is continuously expanded and coupled out, so that the intensity of the light beam passing through the coupling-out grating is continuously reduced in the direction away from the coupling-in grating, the light-emitting efficiency of the coupling-out grating is higher on one side close to the coupling-in grating and lower on the other side away from the coupling-in grating, and finally the exit pupil non-uniformity is caused.
In the related art, the coupling-out grating area is partitioned, grating periods of different areas are the same, and grating parameters (such as height or structural size) are different, so that coupling-out efficiency of different areas is adjusted, and uniform light emission of the whole coupling-out grating area is achieved. However, this method makes different areas adopt different grating parameters, which increases the difficulty of processing and increases the processing cost.
Disclosure of Invention
The invention provides a two-dimensional diffraction grating, a two-dimensional diffraction optical waveguide and near-to-eye display equipment, which are used for solving the problems that the exit pupil of the diffraction optical waveguide is not uniform or the processing difficulty of the two-dimensional diffraction grating is high in the prior art.
The present invention provides a two-dimensional diffraction grating comprising: the optical structures are in open circular ring shapes, the inner diameters of the optical structures are the same, and the outer diameters of the optical structures are the same;
the optical structures are respectively arranged in a first direction and a second direction at equal intervals, and an included angle between the first direction and the second direction is larger than 20 degrees and smaller than 160 degrees.
In some embodiments, different rotation angles of the optical structure correspond to different diffraction efficiencies, and the rotation angle is an included angle between a symmetry line of the optical structure and a horizontal direction.
In some embodiments, at least two of the optical structures correspond to different rotation angles, respectively.
In some embodiments, different opening angles of the optical structure correspond to different diffraction efficiencies;
the field angle is an included angle between the geometric center of the optical structure and a connecting line at two ends of the opening of the optical structure.
In some embodiments, at least two of the optical structures each correspond to a different opening angle.
In some embodiments, the adjustment range of the opening angle is equal to or greater than 20 ° and equal to or less than 100 °.
In some embodiments, at least two of the optical structures correspond to different opening angles and different rotation angles, respectively.
In some embodiments, the distance between the geometric centers of the optical structures adjacent to each other in the first direction is 200nm to 2 μm, and the distance between the geometric centers of the optical structures adjacent to each other in the second direction is 200nm to 2 μm.
The present invention also provides a two-dimensional diffractive optical waveguide comprising: the optical structure comprises a waveguide substrate, a one-dimensional coupling-in grating and the two-dimensional diffraction grating, wherein the one-dimensional coupling-in grating is arranged on the surface of the waveguide substrate;
the one-dimensional coupling grating is used for coupling incident light carrying image information into the waveguide; the two-dimensional diffraction grating is used for coupling out the diffracted light which comes from the one-dimensional coupling-in grating and is guided in the waveguide in a total reflection mode to the human eye for imaging while diffracting and expanding the diffracted light along two directions.
The invention also provides a near-eye display device comprising a two-dimensional diffractive optical waveguide as described above.
According to the two-dimensional diffraction grating, the two-dimensional diffraction optical waveguide and the near-to-eye display device, the optical structures with the plurality of opening circular rings are adopted, and the rotating angle and the opening angle of each optical structure are adjusted, so that the processing difficulty of the two-dimensional diffraction grating can be reduced, diffracted light can be effectively expanded along the horizontal direction and the vertical direction, and the exit pupil uniformity of the two-dimensional diffraction optical waveguide is improved.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of a two-dimensional diffraction grating provided by the present invention;
FIG. 2 is a schematic diagram showing the variation of diffraction efficiency of different diffraction orders of a two-dimensional diffraction grating provided by the present invention;
FIG. 3 is a second schematic diagram showing the variation of diffraction efficiency of different diffraction orders of the two-dimensional diffraction grating provided by the present invention;
FIG. 4 is a third schematic diagram illustrating the variation of diffraction efficiency of different diffraction orders of the two-dimensional diffraction grating provided by the present invention;
FIG. 5 is one of the structural schematic diagrams of a two-dimensional diffractive optical waveguide provided by the present invention;
FIG. 6 is a schematic view of the opening angle of the optical structure of the two-dimensional diffraction grating provided by the present invention;
FIG. 7 is a fourth schematic diagram illustrating the variation of diffraction efficiency of different diffraction orders of the two-dimensional diffraction grating provided by the present invention;
fig. 8 is a second schematic structural diagram of a two-dimensional diffractive optical waveguide provided by the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention and are not to be construed as limiting the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The two-dimensional diffraction grating, the two-dimensional diffraction optical waveguide, and the near-eye display device provided in the embodiments of the present invention are described below with reference to the accompanying drawings by specific embodiments and application scenarios thereof.
Fig. 1 is a schematic structural diagram of a two-dimensional diffraction grating provided by the present invention.
Referring to fig. 1, the two-dimensional diffraction grating provided by the present invention includes: the optical structures 10 are in open circular ring shapes, the inner diameters of the optical structures 10 are the same, and the outer diameters of the optical structures 10 are the same;
the plurality of optical structures 10 are respectively arranged at equal intervals in a first direction and a second direction, and an included angle between the first direction and the second direction is greater than 20 ° and less than 160 °.
In a practical implementation, the optical structure 10 is in the shape of an open circular ring, which may be, for example, a C-ring, a semicircular ring, or other arc-shaped rings with different central angles.
The inner diameter of each optical structure 10 is the same and the outer diameter of each optical structure 10 is the same. The inner diameter refers to the inner diameter of the split ring and the outer diameter refers to the outer diameter of the split ring.
The structural parameters of the split ring include the rotation angle and the opening angle in addition to the inner diameter and the outer diameter. The rotation angle is used to indicate the opening orientation, i.e. the final orientation of the ring opening. The opening angle is used for indicating the opening size of the opening circular ring, for example: if the opening angle is 180 degrees, the ring is semicircular.
In practical implementation, the plurality of optical structures are arranged at equal intervals in the first direction and the second direction, respectively, to form a two-dimensional array arrangement, so that a grating in the first direction and a grating in the second direction can be obtained. The first direction and the second direction are two-dimensional different directions, and an included angle between the first direction and the second direction is greater than 20 ° and less than 160 °, which is not limited herein.
The two-dimensional diffraction grating is formed by intersecting and arranging gratings in two directions, and the included angle between the first direction and the second direction can be 60 degrees in general.
In some embodiments, the distance between the geometric centers of the optical structures adjacent to each other in the first direction is 200nm to 2 μm, and the distance between the geometric centers of the optical structures adjacent to each other in the second direction is 200nm to 2 μm.
It can be understood that the period ranges of the two-dimensional diffraction grating in the horizontal direction and the vertical direction are respectively 200nm to 2 μm.
In practical implementation, as shown in fig. 1, the optical structure 10 may be a C-shaped grating unit structure, and a plurality of C-shaped grating unit structures are arrayed along two directions to form a two-dimensional diffraction grating. The inner diameter of each C-shaped grating unit structure is the same, and the outer diameter of each C-shaped grating unit structure is the same.
Fig. 2 is one of schematic diagrams illustrating the variation of diffraction efficiency of different diffraction orders of the two-dimensional diffraction grating provided by the present invention. The two-dimensional diffraction grating provided by the invention can expand incident light mainly along three directions.
As shown in fig. 2, includes three diffraction orders, (0, 0), (-1, 1), and (1, 1). The efficiencies of the three diffraction orders at an incident angle of 52 deg. were 88%, 2.01%, and 1.69%, respectively, indicating that the diffracted light can be efficiently expanded in the horizontal and vertical directions. In addition, the light of (0, 2) diffraction order exits perpendicular to the plane where the grating is located and enters the human eye for imaging, and the efficiency of (0, 2) diffraction order is 0.06%, which shows that the (0, 2) diffraction order can be coupled out of the diffraction waveguide with very low diffraction efficiency and enter the human eye for imaging, so that more light energy can be expanded in the diffraction waveguide to form the exit pupil, and the uniformity of the exit pupil of the diffraction waveguide is better.
Fig. 3 is a second schematic diagram illustrating the variation of diffraction efficiency of different diffraction orders of the two-dimensional diffraction grating provided by the present invention.
As shown in FIG. 3, FIG. 3 shows that the diffraction efficiencies of the (0, 0), (-1, 1), (1, 1) and (0, 2) orders vary with the angle of incidence, with angles of incidence ranging from 40 DEG to 80 DEG, the diffraction efficiencies of the (0, 2) orders varying from 0.01% to 0.08%, while the diffraction efficiencies of the (-1, 1) and (1, 1) orders varying from 0.25% to 3.4% and 0.33% to 1.85%, respectively, and the diffraction efficiencies of the (0, 0) orders varying from 87.7% to 97%, indicating that, with varying angles of incidence, both the (0, 2) diffraction orders can couple out of the diffractive waveguide into the human eye with very low diffraction efficiency, while both the (-1, 1) and (1, 1) diffraction orders can be propagated in the waveguide in the horizontal direction with high diffraction efficiency, and that also the (0, 0) diffraction orders can be propagated in the waveguide in the vertical direction with high diffraction efficiency, resulting in greater uniformity of the diffracted light energy being propagated out of the waveguide.
The two-dimensional diffraction grating provided by the invention adopts a plurality of open ring-shaped optical structures, the grating structure is simple, the diffracted light can be effectively expanded along the horizontal direction and the vertical direction, and the exit pupil uniformity of the two-dimensional diffraction optical waveguide is improved.
In some embodiments, different angles of rotation of the optical structure 10, which is the angle between the line of symmetry of the optical structure 10 and the horizontal direction, correspond to different diffraction efficiencies.
In practical implementations, the optical structures 10 are open circular rings, and the plurality of optical structures 10 may have the same or different opening orientations, and the different opening orientations indicate that the optical structures 10 have different rotation angles.
The rotation angle of the optical structure 10 may be considered to be 0 ° when the symmetry line of the optical structure 10 coincides with the horizontal direction. The rotation angle is positive when the symmetry line rotates clockwise, and the rotation angle is negative when the symmetry line rotates counterclockwise.
In the embodiment of the present invention, the rotation angle of each optical structure 10 may be preset according to actual requirements of a user, and is not limited in detail herein.
In practical implementation, it is found through a lot of calculations that the diffraction efficiencies of the (0, 0), (-1, 1), (1, 1) and (0, 2) orders can be changed by only changing the rotation angle of the optical structure 10 without changing other structural parameters of the optical structure 10, thereby changing the exit pupil uniformity of the diffractive waveguide.
Fig. 4 is a third schematic diagram illustrating the variation of diffraction efficiency of different diffraction orders of the two-dimensional diffraction grating provided by the present invention.
As shown in fig. 4, fig. 4 shows the diffraction efficiency changes at each order when the rotation angle of the optical structure 10 (grating unit structure) is-90 °, -45 °,0 °, 45 °, and 90 °, respectively. When the C-shaped grating unit structure 10 rotates clockwise and counterclockwise, the (0, 2) diffraction order efficiency increases, the sum of the (-1, 1) and (1, 1) diffraction order efficiencies decreases, and the (0, 0) diffraction order efficiency increases, which indicates that more light energy is directly coupled out from the diffractive waveguide, less light energy expands in the diffractive waveguide along the horizontal direction and the vertical direction, and the exit pupil uniformity of the diffractive waveguide decreases.
In some embodiments, at least two optical structures 10 each correspond to a different rotation angle.
It will be appreciated that a plurality of optical structures 10 may have the same rotation angle, i.e. the opening orientations of all optical structures 10 are the same; it is also possible to have different rotation angles, i.e. different opening orientations of all optical structures 10; the rotation angles of the partial optical structures 10 may be the same, and the rotation angles of the partial optical structures 10 may be different.
In a practical implementation, as shown in fig. 5, the two-dimensional diffraction grating 120 may include a plurality of sections arranged in pixelization. Each section contains an optical structure with a different rotation angle, which may be, for example, a plurality of C-shaped grating cell structures. The two-dimensional diffraction grating 120 is divided into a plurality of regions, and the diffraction efficiency of each region can be adjusted.
According to the two-dimensional diffraction grating provided by the invention, the diffraction efficiency is adjusted by changing the rotation angle of the optical structure, so that the exit pupil uniformity of the diffraction waveguide can be greatly improved, and the processing difficulty of the diffraction grating is not increased.
In some embodiments, different opening angles of the optical structure 10 correspond to different diffraction efficiencies;
wherein, the field angle is an included angle between the geometric center of the optical structure 10 and a connecting line of two ends of the opening of the optical structure 10.
In a practical implementation, the optical structure 10 has an adjustable opening angle. The opening angle of each optical structure 10 may be preset according to the actual requirement of the user, and is not limited in detail herein.
It will be appreciated that the size of the opening angle is related to the size of the corresponding opening of the optical structure 10. The larger the opening angle is, the larger the opening is; the smaller the opening angle, the smaller the opening. Different opening angles may correspond to different diffraction efficiencies.
As shown in FIG. 6, the opening angle is the angle between the geometric center of the optical structure 10 and the line connecting the two ends of the opening of the optical structure 10θ。
In some embodiments, the adjustment range of the opening angle is equal to or greater than 20 ° and equal to or less than 100 °.
Embodiments of the present invention may be used to vary the opening angle of the optical structure 10θTo adjust the diffraction efficiency of each diffraction order and improve the exit pupil uniformity of the diffractive waveguide. Wherein the opening angleθThe adjusting range of (1) is between 20 DEG and 100 deg.
As shown in FIG. 7, the opening angle is shown in FIG. 7θThe diffraction efficiency of each order changes at 20 °, 40 °, 60 °, 80 ° and 100 °, respectively. Opening angleθWhen the temperature is increased from 20 degrees to 100 degrees, the variation range of the diffraction efficiency of (0, 2) order is 0.06% -0.1%, the variation ranges of the diffraction efficiency of (1, 1) order and (1, 1) order are 1.36% -4.26% and 1.35% -2.63%, respectively, and the variation range of the diffraction efficiency of (0, 0) order is 87.53% -89.83%, which indicates that the field angle is wideθWhen the diffraction order (0, 2) can be coupled out of the diffraction waveguide into the human eye for imaging with very low diffraction efficiency, meanwhile, the diffraction orders (-1, 1) and (1, 1) can be expanded and conducted in the waveguide along the horizontal direction with higher diffraction efficiency, and the diffraction order (0, 0) can also be expanded and conducted in the waveguide along the vertical direction with higher diffraction efficiency, so that more light energy can be expanded in the diffraction waveguide through the exit pupil, and the uniformity of the exit pupil of the diffraction waveguide is better.
In some embodiments, at least two optical structures 10 each correspond to a different opening angle.
In practical implementation, the two-dimensional diffraction grating provided by the present invention may include a plurality of optical structures 10, each optical structure 10 may set the same opening angle, or may set different opening angles respectively, or some optical structures 10 may set the same opening angle, and some optical structures 10 may set different opening angles.
According to the two-dimensional diffraction grating provided by the invention, the diffraction efficiency is adjusted by changing the field angle of the optical structure, so that the exit pupil uniformity of the diffraction waveguide can be greatly improved, and the processing difficulty of the diffraction grating is not increased.
In some embodiments, at least two optical structures 10 correspond to different opening angles and different rotation angles, respectively.
In practical implementation, the opening angle or the rotation angle of one or more optical structures 10 may be changed simultaneously according to practical requirements, and is not limited specifically, and at least two optical structures 10 may exist, which correspond to different opening angles and different rotation angles respectively.
As shown in fig. 8, the two-dimensional diffraction grating 220 includes a plurality of divided regions arranged in a pixelized manner, and the plurality of divided regions respectively include the optical structures 10 having different rotation angles and different field angles, and may be, for example, a plurality of C-shaped grating unit structures. By dividing the two-dimensional diffraction grating 220 into a plurality of regions, the diffraction efficiency of each region is adjusted at the same time.
According to the two-dimensional diffraction grating provided by the invention, the diffraction efficiency of the two-dimensional diffraction grating can be adjusted by changing the rotation angle of the optical structure or adjusting the field angle of the optical structure, so that the exit pupil uniformity of the two-dimensional diffraction optical waveguide is improved, and meanwhile, the two-dimensional diffraction grating formed by a plurality of optical structures is simple in structure, so that the processing difficulty of the two-dimensional diffraction grating is reduced.
Based on the same inventive concept, the invention also provides a two-dimensional diffraction light waveguide, which comprises a waveguide substrate, a one-dimensional coupling-in grating arranged on the surface of the waveguide substrate, and the two-dimensional diffraction grating in the embodiment, wherein the two-dimensional diffraction grating comprises a plurality of regions arranged in a pixelization manner, and each region is provided with an optical structure;
the one-dimensional coupling grating is used for coupling incident light carrying image information into the waveguide; the two-dimensional diffraction grating is used for coupling out diffracted light which is from the one-dimensional coupling-in grating and is conducted in a total reflection mode in the waveguide to human eyes for imaging while diffracting and expanding the diffracted light in two directions.
It should be noted that the two-dimensional diffractive light waveguide is generally composed of a waveguide substrate and a one-dimensional incoupling grating and the two-dimensional diffractive grating in the above-described embodiments, which are located on the surface of the waveguide substrate. The two-dimensional diffraction grating is a two-dimensional coupling-out grating.
The one-dimensional coupling-in grating and the two-dimensional coupling-out grating can be surface relief gratings, volume holographic gratings or super surface gratings.
The one-dimensional incoupling grating couples incident light carrying image information into the diffraction waveguide, and is generally a rectangular grating, an inclined grating, or a blazed grating. The waveguide guides the coupled-in light in a total reflection manner. The two-dimensional coupling-out grating diffracts and expands diffracted light which comes from the one-dimensional coupling-in grating and is transmitted in a total reflection mode in the waveguide along two directions and simultaneously couples out the diffracted light to human eyes for imaging, the two-dimensional coupling-out grating is arranged in an array form along two directions by an open circular optical unit structure, and the included angle between the two directions can be 20-160 degrees and is generally 60 degrees. When the diffracted light from the one-dimensional incoupling grating is conducted to the two-dimensional outcoupling grating region and is incident on the two-dimensional outcoupling grating, the diffracted light will again undergo multiple simultaneous diffractions. The diffracted light can be diffracted to the zeroth order, which does not change the propagation direction of the diffracted light; the diffracted light can also be coupled out of the waveguide (i.e., diffracted light that enters the human eye directly), into the human eye for imaging.
As shown in fig. 5, the two-dimensional diffractive optical waveguide 100 includes a one-dimensional in-coupling grating 110 and a two-dimensional diffractive grating 120 in the above-mentioned embodiment, i.e., a two-dimensional out-coupling grating. The two-dimensional diffraction grating 120 may include a plurality of sections arranged in pixelization. Each section contains the optical structure in the above embodiments, which may be, for example, a plurality of C-shaped grating cell structures. In a practical implementation, the plurality of segments may each contain optical structures of different rotation angles. By dividing the two-dimensional outcoupling grating 120 into a plurality of regions and adjusting the diffraction efficiency of each region at the same time, the present invention can greatly improve the exit pupil uniformity of the diffractive waveguide without increasing the processing difficulty of the diffractive waveguide.
As shown in fig. 8, the two-dimensional diffractive optical waveguide 200 includes a one-dimensional incoupling grating 210 and a two-dimensional diffraction grating 220 in the above embodiment, i.e., a two-dimensional outcoupling grating. The two-dimensional diffraction grating 220 may comprise a plurality of regions arranged in pixelization, each region containing the optical structure in the above-described embodiments, for example, may be a plurality of C-shaped grating unit structures. The plurality of segments each contain optical structures having different rotation angles and different opening angles. By dividing the two-dimensional coupling-out grating 220 into a plurality of regions and adjusting the diffraction efficiency of each region, the invention can greatly improve the exit pupil uniformity of the diffraction waveguide without increasing the processing difficulty of the diffraction waveguide.
According to the two-dimensional diffraction optical waveguide provided by the invention, the diffraction efficiency of the two-dimensional diffraction grating can be adjusted by adopting the plurality of open circular optical structures and changing the rotation angle of the optical structures or adjusting the field angle of the optical structures, so that the exit pupil uniformity of the two-dimensional diffraction optical waveguide is improved, and meanwhile, the two-dimensional diffraction grating formed by the plurality of optical structures has a simple structure, so that the processing difficulty of the two-dimensional diffraction grating is reduced.
Based on the same inventive concept, the invention also provides a near-eye display device comprising the two-dimensional diffraction optical waveguide. Since the near-eye display device of the present invention includes the two-dimensional diffractive optical waveguide, the near-eye display device of the present invention has similar technical effects to those of the above embodiments, and details are not repeated herein. In addition, the description of the specific principle can also refer to the introduction of the above embodiments, and is not repeated herein.
According to the technical scheme, the near-eye display device provided by the invention has the advantages that the diffraction efficiency of the two-dimensional diffraction grating can be adjusted by adopting the optical structures with a plurality of open circular rings and changing the rotation angle of the optical structures or adjusting the field angle of the optical structures, the exit pupil uniformity of the near-eye display device is improved, and meanwhile, the two-dimensional diffraction grating formed by the optical structures is simple in structure, so that the manufacturing difficulty of the near-eye display device is reduced.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A two-dimensional diffraction grating, comprising: the optical structures are in open circular ring shapes, the inner diameters of the optical structures are the same, and the outer diameters of the optical structures are the same;
the optical structures are respectively arranged in a first direction and a second direction at equal intervals, and an included angle between the first direction and the second direction is larger than 20 degrees and smaller than 160 degrees.
2. A two-dimensional diffraction grating according to claim 1, wherein different rotation angles of the optical structure correspond to different diffraction efficiencies, the rotation angles being angles between a line of symmetry of the optical structure and a horizontal direction.
3. A two-dimensional diffraction grating according to claim 2, wherein at least two of the optical structures correspond to different angles of rotation, respectively.
4. A two-dimensional diffraction grating according to claim 1, wherein different opening angles of the optical structure correspond to different diffraction efficiencies;
the field angle is an included angle between the geometric center of the optical structure and a connecting line at two ends of the opening of the optical structure.
5. A two-dimensional diffraction grating according to claim 4, wherein at least two of the optical structures each correspond to a different field angle.
6. A two-dimensional diffraction grating according to claim 4, wherein the adjustment range of the aperture angle is 20 ° or more and 100 ° or less.
7. A two-dimensional diffraction grating according to claim 4, wherein at least two of the optical structures correspond to different field angles and different angles of rotation, respectively.
8. A two-dimensional diffraction grating according to any one of claims 1 to 7,
the interval between the geometric centers of the optical structures adjacent to each other in the first direction is 200nm to 2 mu m, and the interval between the geometric centers of the optical structures adjacent to each other in the second direction is 200nm to 2 mu m.
9. A two-dimensional diffractive optical waveguide, comprising: a waveguide substrate, a one-dimensional incoupling grating arranged on a surface of the waveguide substrate and a two-dimensional diffraction grating according to any of claims 1-8, said two-dimensional diffraction grating comprising a plurality of pixelated zones, each zone being provided with said optical structure;
the one-dimensional coupling grating is used for coupling incident light carrying image information into the waveguide; the two-dimensional diffraction grating is used for coupling out the diffracted light which is from the one-dimensional coupling-in grating and is conducted in the waveguide in a total reflection mode to the human eye for imaging while diffracting and expanding the diffracted light along two directions.
10. A near-eye display device comprising the two-dimensional diffractive optical waveguide of claim 9.
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| CN116719169B (en) * | 2023-08-10 | 2024-01-05 | 北京亮亮视野科技有限公司 | Diffraction grating waveguide and augmented reality display device |
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