WO2023040491A1 - 光学结构和光学装置 - Google Patents

光学结构和光学装置 Download PDF

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Publication number
WO2023040491A1
WO2023040491A1 PCT/CN2022/109685 CN2022109685W WO2023040491A1 WO 2023040491 A1 WO2023040491 A1 WO 2023040491A1 CN 2022109685 W CN2022109685 W CN 2022109685W WO 2023040491 A1 WO2023040491 A1 WO 2023040491A1
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Prior art keywords
grating
outcoupling
sub
outcoupling grating
light
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PCT/CN2022/109685
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English (en)
French (fr)
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蒋楚豪
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Oppo广东移动通信有限公司
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Publication of WO2023040491A1 publication Critical patent/WO2023040491A1/zh

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B6/122—Basic optical elements, e.g. light-guiding paths
    • G02B6/124—Geodesic lenses or integrated gratings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/0101—Head-up displays characterised by optical features

Definitions

  • the present application relates to the field of optical technology, in particular to an optical structure and an optical device.
  • Optical devices such as augmented reality (Augmented Reality, abbreviated as AR) devices and virtual reality (Virtual Reality, abbreviated as VR) devices can display images through respective display devices.
  • AR Augmented Reality
  • VR Virtual Reality
  • Technologies related to AR devices and/or VR devices are increasingly used in various fields, such as military, medical, construction, education, engineering, film and television, entertainment and other fields.
  • AR glasses are one of the main implementations of AR devices. Its near-eye display system uses a series of optical imaging elements to form a distant virtual image from the pixels on the display device and projects it into the human eye. AR glasses products need to meet the requirements of see-through, not only to see the real external world, but also to see virtual information, so the imaging system cannot block the line of sight. For example, add one or a group of optical combiners to integrate virtual information and real scenes in the form of "stacking".
  • AR glasses have many optical realization schemes such as catadioptric reflection, reflective waveguide, one-dimensional diffractive waveguide, two-dimensional diffractive waveguide, holographic optical waveguide, etc.
  • two-dimensional diffractive waveguide Two-dimensional Diffractive Waveguide, abbreviated as TDDW
  • TDDW two-dimensional diffractive waveguide
  • the coupling grating of the general TDDW structure couples the light from the projection light machine into the waveguide, and the light coupled into the waveguide advances towards the outcoupling grating through total internal reflection, and after reaching the outcoupling grating, it is diffracted and divided into A pupil-dilated ray traveling left versus a pupil-dilated ray traveling right. Every time the light interacts with the outcoupling grating, a part of the energy will be coupled out to the human eye, so that the user can see the picture of the projection light machine.
  • the component generated by the light of the edge field of view passing through the outcoupling grating includes a component transmitted along the propagation direction of the light of the field of view. The light of the edge of view angle will pass through different outcoupling the grating, resulting in low diffraction efficiency.
  • Embodiments of the present application provide an optical structure and an optical device, which improve the diffraction efficiency of the optical structure.
  • An embodiment of the present application provides an optical structure, which includes:
  • the third outcoupling grating is arranged on the waveguide, the third outcoupling grating is located between the first outcoupling grating and the second outcoupling grating, and the incoupling grating is located between the first outcoupling grating,
  • the second outcoupling grating and the third outcoupling grating are on the same side;
  • the light emitted by the in-coupling grating is incident on the third out-coupling grating through the waveguide, and interacts with the third out-coupling grating to generate a first component of the light along the outgoing direction of the light, so The first light component remains within the range of the third outcoupling grating and will not be transmitted to the first outcoupling grating or the second outcoupling grating.
  • the embodiment of the present application also provides an optical device, which includes:
  • a light projector configured to provide augmented reality or virtual reality images
  • FIG. 1 is a schematic structural diagram of an optical structure provided by an embodiment of the present application.
  • Fig. 2 is a perspective view of an optical structure provided by an embodiment of the present application.
  • FIG. 3 is a schematic diagram of transmission of light in the central field of view in an optical structure provided by an embodiment of the present application.
  • FIG. 4 is a schematic diagram of the transmission of light in the peripheral field of view in the optical structure provided by the embodiment of the present application.
  • FIG. 5 is a schematic diagram of the principle of the light transmission process of the optical structure provided in the embodiment of the present application in k-space.
  • FIG. 6 is a schematic diagram of transmission of light in the central field of view in an optical structure along a plane provided by an embodiment of the present application.
  • FIG. 7 is a schematic diagram of transmission of light in a peripheral field of view in an optical structure along a plane provided by an embodiment of the present application.
  • FIG. 8 is a schematic diagram of an application scenario of an optical structure according to an embodiment of the present application.
  • FIG. 9 is a schematic diagram of a grating vector of a first outcoupling grating according to an embodiment of the present application.
  • FIG. 10 is a schematic diagram of an optical structure provided by an embodiment of the present application and a partial structure of a first outcoupling grating in the optical structure.
  • FIG. 11 is a schematic diagram of a partial structure of the first outcoupling grating in the optical structure provided by the embodiment of the present application.
  • FIG. 12 is a schematic diagram of a partial structure of the first outcoupling grating in the optical structure provided by the embodiment of the present application.
  • FIG. 13 is a schematic diagram of a partial structure of the first outcoupling grating in the optical structure provided by the embodiment of the present application.
  • FIG. 14 is a schematic diagram of a partial structure of the first outcoupling grating in the optical structure provided by the embodiment of the present application.
  • FIG. 15 is a schematic diagram of a partial structure of the first outcoupling grating in the optical structure provided by the embodiment of the present application.
  • FIG. 16 is a schematic diagram of an optical structure provided by an embodiment of the present application.
  • FIG. 17 is a schematic diagram of an optical structure provided by an embodiment of the present application.
  • FIG. 18 is a schematic diagram of an optical structure provided by an embodiment of the present application.
  • FIG. 19 is a schematic diagram of an optical structure provided by an embodiment of the present application.
  • FIG. 20 is a schematic diagram of an optical structure provided by an embodiment of the present application.
  • FIG. 21 is a schematic diagram of an optical structure provided by an embodiment of the present application.
  • FIG. 22 is a schematic diagram of an optical structure provided by an embodiment of the present application.
  • FIG. 23 is a schematic diagram of an optical structure provided by an embodiment of the present application.
  • FIG. 24 is a schematic diagram of an optical structure provided by an embodiment of the present application.
  • FIG. 1 is a schematic structural diagram of an optical structure provided by an embodiment of the present application, and shows a reference system (x, y, z).
  • the optical structure 200 includes a waveguide 250 , an incoupling grating 240 disposed on the waveguide, and a plurality of outcoupling gratings (the outcoupling grating 210 , the outcoupling grating 220 and the outcoupling grating 230 ).
  • the waveguide 260 of the optical structure 200 , the coupling-in grating 240 and the plurality of coupling-out gratings are all arranged on the x-y plane.
  • the waveguide 250 serves as a carrier of the optical structure 200 .
  • the waveguide 250 is capable of conducting optical signals, such as by total internal reflection.
  • the waveguide 250 may have two oppositely disposed surfaces, such as including oppositely disposed first and second surfaces 252 . Wherein, the second surface is set opposite to the first surface 252 , which is blocked and not shown in the view of FIG. 1 .
  • the coupling-in grating 240 is disposed on one surface of the waveguide 250 , such as the first surface 252 .
  • the coupling-in grating 240 can receive an optical signal (also referred to as light) from a projector (not shown in the figure), and couple the optical signal into the waveguide 250 .
  • the waveguide 250 can conduct the optical signal after receiving the optical signal coupled in from the coupling grating 240 .
  • the coupling-in grating 240 may be any one of a blazed grating, a rectangular grating and an oblique grating.
  • the coupling-in grating 240 may be a one-dimensional grating.
  • the plurality of outcoupling gratings may include a first outcoupling grating 210 , a second outcoupling grating 220 and a third outcoupling grating 230 .
  • the first outcoupling grating 210 , the second outcoupling grating 220 and the third outcoupling grating 230 are all disposed on the waveguide 250 , and the third outcoupling grating 230 is located between the first outcoupling grating 210 and the second outcoupling grating 220 .
  • the first outcoupling grating 210 , the second outcoupling grating 220 and the third outcoupling grating 230 are disposed on the same surface of the waveguide 250 , such as the first surface 252 . It should be noted that the first outcoupling grating 210 , the second outcoupling grating 220 and the third outcoupling grating 230 may also be disposed on the other side of the waveguide 250 , that is, the second surface opposite to the first surface.
  • one of the first outcoupling grating 210, the second outcoupling grating 220, and the third outcoupling grating 230 may be disposed on one side of the waveguide 250 such as the first surface 252, while the first outcoupling grating
  • the other two of the out-coupling grating 210 , the second out-coupling grating 220 and the third out-coupling grating 230 may be disposed on the other surface and the second surface of the waveguide 250 .
  • any combination of the in-coupling grating 240 , the first out-coupling grating 210 , the second out-coupling grating 220 and the third out-coupling grating 230 on any side of the waveguide 250 is considered in the embodiment of the present application. within the scope of protection.
  • the coupling-in grating 240 can be disposed on the same side of the first coupling-out grating 210, the second coupling-out grating 220, and the third coupling-out grating 230, and the coupling-in grating 240 and the third coupling-out grating 230 are arranged side by side.
  • the shapes of the first outcoupling grating 210 and the second outcoupling grating 220 are the same, and the first outcoupling grating 210 and the second outcoupling grating 220 are arranged symmetrically with respect to the third outcoupling grating 230, which can also be understood as The first outcoupling grating 210 and the second outcoupling grating 220 are arranged as mirror images with respect to the third outcoupling grating 230 . It should be noted that the shapes of the first outcoupling grating 210 and the second outcoupling grating 220 may also be different, or they may not be arranged symmetrically with respect to the third outcoupling grating 230 .
  • the waveguide 250 can make the optical signal coupled in by the in-coupling grating 240 go toward the first out-coupling grating 210, the second out-coupling grating 220 and the third out-coupling grating 230 through total internal reflection, and reach the first out-coupling grating 210 , the second outcoupling grating 220 and the third outcoupling grating 230 will be divided into several parts by diffraction and transmitted toward multiple directions. Part of the optical signal is coupled out to the human eye, allowing the user to see the picture of the projector light machine.
  • FIG. 2 is a perspective view of the optical structure provided by the embodiment of the present application, and FIG. 2 shows the optical signal transmission after the light incident in the central field of view is diffracted, and shows the reference system (x, y, z ).
  • the in-coupling grating 240 After the central field of view light is incident on the in-coupling grating 240 , the in-coupling grating 240 transmits the light 201 toward the third out-coupling grating 230 through the waveguide 250 .
  • the light 201 is split into four light beams by diffraction, namely the light 2011 , the light 2012 , the light 2013 and the light 2014 .
  • the ray 2011 travels along the original path of the ray 201 .
  • the light 201 is split into 4 beams of light after interacting with the third outcoupling grating 230 and is diffracted.
  • the light 2011 will interact with the third outcoupling grating 230 multiple times during the process of advancing along the original path of the light 201, each time The effects are split into 4 beams of light after diffraction. That is, light 2011 interacts with the third outcoupling grating 230 for many times during the process of advancing along the original path of light 201. Proceeding along the original path of ray 201 is shown as a ray. Every time the light 2011 interacts with the third outcoupling grating 230 once, the energy of the light traveling along the original path will decrease.
  • the light 2012 is directly coupled out from the third outcoupling grating 230 , it can be understood that the light 2012 is coupled out towards the positive direction of z based on the x-y plane. In the embodiment of the present application, all the light directly coupled out from the third outcoupling grating 230 is defined as the light 2012 . It can be understood that the energies of different light rays directly coupled out from different positions of the third outcoupling grating 230 are different.
  • the light 2013 After interacting with the first outcoupling grating 210, the light 2013 is split into two beams of light by diffraction, namely light 2013A and light 2013B.
  • the light 2013A is directly coupled out from the first outcoupling grating 210 , it can be understood that the light 2013A is coupled out towards the positive direction of z based on the x-y plane.
  • the ray 2013B travels along the original path of the ray 2013 .
  • the light propagating from the third outcoupling grating 230 toward the first outcoupling grating 210 is defined as light 2013, and there are multiple light rays 2013, and each light 2013 interacts with the first outcoupling grating 210 and is diffracted Multiple rays 2013A and multiple rays 2013B are split. It can be understood that different light rays 2013 have different energies, different light rays 2013A have different energies, and different light rays 2013B have different energies.
  • the light 2014 After interacting with the second outcoupling grating 220, the light 2014 is split into two beams of light by diffraction, namely the light 2014A and the light 2014B.
  • the light 2014A is directly coupled out from the second outcoupling grating 210. It can be understood that the light 2014A is based on the x-y plane Coupled out towards the positive z direction.
  • the ray 2014B travels along the original path of the ray 2014 .
  • the light propagating from the third outcoupling grating 230 toward the second outcoupling grating 220 is defined as light 2014, and there are multiple light rays 2014, and each light 2014 interacts with the second outcoupling grating 220 and is diffracted Multiple rays 2014A and multiple rays 2014B are split. It can be understood that different light rays 2014 have different energies, different light rays 2014A have different energies, and different light rays 2014B have different energies.
  • the light coupled out based on the positive direction of the x-y plane towards z will be incident on human eyes, allowing the user to see the picture of the projection light machine.
  • the light 2012 coupled out from the third outcoupling grating 230 toward the positive direction of z will enter the human eye, and from the first outcoupling grating 210 toward the positive direction of z
  • the outcoupled light 2013A will enter the human eye, and the outcoupled light 2014A from the second outcoupling grating 220 toward the positive direction of z will enter the human eye.
  • the light 2011 , the light 2012 , the light 2013 , and the light 2014 shown in FIG. 2 are exemplary, and the number of light coupled out by the optical structure 200 is not limited. Or it can be understood that FIG. 2 shows a part of the light when the optical structure 200 of the embodiment of the present application couples out the light, and the rest of the light is not shown.
  • Fig. 3 is a schematic diagram of transmission of central field of view light in the optical structure provided by the embodiment of the present application
  • Fig. 4 is a schematic diagram of transmission of edge field of view light in the optical structure provided by the embodiment of the present application.
  • the in-coupling grating 240 transmits the out-coupling light 201 through the waveguide 250 to the third out-coupling grating 230, and interacts with the third out-coupling grating 230 to split a plurality of light rays such as light 2011, light 2012, light 2013 and light 2014 , where the transmission directions of the light 2011, the light 2012, the light 2013 and the light 2014 can refer to FIG. 2 and related contents, and will not be repeated here.
  • the ray 2012 is replaced by a dot.
  • the light 2013 reacts with the first outcoupling grating 210 to split into multiple light rays, such as light 2013A and light 2013B.
  • the ray 2013A is replaced by a dot in the x-y plane.
  • the light 2014 interacts with the second outcoupling grating 220 to split into multiple light rays such as the light 2014A and the light 2014B.
  • the light 2014A and the light 2014B can refer to FIG. 2 and related content, and will not be repeated here.
  • each dot represents a light that interacts with a light that is coupled out of the grating, and that the light represented by the dot can enter the human eye.
  • FIG. 3 and FIG. 4 show that each outcoupling grating can couple out multiple light rays along the positive direction of the z-axis.
  • FIG. 5 is a schematic diagram of the light transmission process of the optical structure provided by the embodiment of the present application in k-space, and shows the reference system (kx, ky, kz).
  • the two circle radii shown in Figure 5 are the ambient refractive index and the waveguide plate refractive index respectively, wherein the radius of the small circle is the radius of the inner circle is the ambient refractive index, and the radius of the large circle is the radius of the outer circle is the waveguide refractive index.
  • Rectangles represent the field of view (FOV), and each rectangle represents a field of view. Rectangles at different positions represent different states of light in the field of view. For example, the rectangle in the center of the ring represents the field of view.
  • the rectangle inside the circle represents the field of view light through the grating (the first outcoupling grating 210, the second outcoupling grating 220 and the outcoupling grating 240) After coupling, it propagates in the waveguide 240 .
  • the field of view is within the small circle, it means that light can be coupled out of the waveguide 250, if the field of view is within a circle, it means that the light propagates in the waveguide 250, and if the field of view is outside the large circle, it means that the light does not actually exist.
  • the light 201 changes to six different positions around its k-space through the six diffraction components k22 of the third out-coupling grating 230, among which the light 2013 ,
  • Light 2014 is still in the ring, which means that they will propagate through total internal reflection to the left and right along the kx axis respectively, and become pupil dilating rays.
  • Another part of the light will be translated upwards through diffraction, and coincide with the original incident image, which means that they (such as light 2012) will be directly coupled out.
  • the area where the optical structure 200 is coupled out and incident to the human eye is defined as an eyebox (Eyebox) 260 . That is, the light that is located in the eye box 260 and coupled out along the positive direction of the z-axis will enter the human eye.
  • Eyebox the area where the optical structure 200 is coupled out and incident to the human eye
  • the eye box will be described below.
  • FIG. 6 is a schematic diagram of the transmission of the central field of view light in the optical structure along a plane provided by the embodiment of the present application
  • Fig. 7 is the transmission of the peripheral field of view light in the optical structure along a plane provided by the embodiment of the present application
  • FIG. 8 is a schematic diagram of an application scenario of the optical structure of the embodiment of the present application.
  • the angle between the incident field of view and the z-axis in the y-z plane ranges from -a° to a°, that is, the angle range between the incident maximum field of view F2 and the z-axis in the y-z plane is a°, and the incident minimum field of view F1 is on the y-z plane
  • the angle range between the inner and the z-axis is -a°.
  • the distance (eyerelief) from the human eye to the waveguide 250 is b, that is, the distance from the Eyebox plane or the observation plane of the human eye to the waveguide 250 is b.
  • A is the minimum length of the first outcoupling grating 210 in the y-axis direction, and A may also be the minimum length of the second outcoupling grating 210 in the y-axis direction. It should be noted that, in the embodiment of the present application, the minimum length of the first outcoupling grating 210 in the y-axis direction is the same as the minimum length of the second outcoupling grating 220 in the y-axis direction.
  • the center of the eye box 260 may coincide with the center of the third outcoupling grating 230 .
  • the central field of view light when the central field of view light is incident on the optical structure 200 , the light coupled out by the first outcoupling grating 210 , the second outcoupling grating 220 and the third outcoupling grating 230 such as Part of the light 2012 , the light 2013A and the light 2014A will be inside the eye box 260 , that is, will be injected into the human eye.
  • the exit pupil uniformity of the peripheral field of view is significantly worse than that of the central field of view, which means that when viewing the projection light machine picture at some Eyebox positions, the brightness difference between the central field of view and the peripheral field of view The gap will be relatively large, causing users to watch uncomfortable.
  • the first outcoupling grating 210 defined based on this embodiment of the present application adopts a two-dimensional grating structure, and has a plurality of first gratings, and each grid has an asymmetric shape, so that the first outcoupling grating 210
  • the efficiency of light propagating in one direction is higher than the efficiency of light propagating in the second direction of the first outcoupling grating 210 .
  • the energy of the wasted part of the light coupled out by the first outcoupling grating 210 is smaller than that of other light, so that the exit pupil brightness and exit pupil uniformity of each field of view can be improved, and the energy gap of each field of view can be reduced. difference between.
  • the brightness and uniformity of the exit pupil of the peripheral field of view can be improved, and the difference between the energy of the peripheral field of view and the energy of the central field of view can be reduced.
  • the optical structure 200 is applied to a head-mounted display product such as AR, it can suppress the iridescent effect of sunlight and improve the image quality of the product.
  • the first direction is a direction in which the first outcoupling grating 210 faces the second outcoupling grating 220 , such as the negative direction of the x-axis shown in FIG. 1 .
  • the second direction is a direction in which the second outcoupling grating 220 faces the first outcoupling grating 210 , such as the positive direction of the x-axis shown in FIG. 1 .
  • the first direction and the second direction are opposite.
  • FIG. 9 is a grating vector schematic diagram of the first outcoupling grating according to the embodiment of the present application.
  • the first outcoupling grating 210 has a multi-level diffraction vector, including (1,1), (1,0), (0,1), (0,-1), (-1,0), (-1,- 1).
  • the diffraction efficiencies of the (1,0) and (-1,0) orders in the first outcoupling grating 210 are obviously higher than the (0,1) and (0,-1) orders, when the light 201
  • the light 2014B is produced by the (-1, 0) order diffraction of the first outcoupling grating 210
  • the light 2013B is produced by the (0, 1) order diffraction of the first outcoupling grating 210
  • the resulting light ray 2014B is therefore much more efficient traveling to the left (first direction) in the illustration than ray 2013B is traveling to the right (second direction) in the illustration.
  • the asymmetric shape adopted by the first grating 212 in the embodiment of the present application can make the light efficiency of the first outcoupling grating 210 propagating in the first direction higher than the light propagating efficiency of the first outcoupling grating 210 in the second direction.
  • the following description will be made in conjunction with the schematic diagram of the first outcoupling grating 210 .
  • Figure 10 is a schematic diagram of the optical structure provided by the embodiment of the present application and a partial structure of the first outcoupling grating in the optical structure
  • Figure 11 is a schematic diagram of the first outcoupling grating in the optical structure provided by the embodiment of the present application
  • Fig. 12 is a schematic diagram of a partial structure of the first outcoupling grating in the optical structure provided in the embodiment of the present application
  • Fig. 13 is a schematic diagram of a partial structure of the first outcoupling grating in the optical structure provided in the embodiment of the present application.
  • the local structure M of the first outcoupling grating 210 shown in FIG. 10 is defined as the first part M. That is, the plurality of first gratings 212 in the first part M are part of the first gratings 212 of the first outcoupling grating 210 .
  • All the first gratings 212 of the plurality of first gratings 212 of the first outcoupling grating 210 may have approximately the same shape.
  • each first grid 212 has four vertices such as a vertex c, a vertex d, a vertex e, and a vertex f, and the four vertices may form a first diagonal line ce and a second diagonal line df.
  • the length of the first diagonal line ce is greater than the length of the second diagonal line df, and the angle ⁇ acx between the first diagonal line ac and the third outcoupling grating 230 in the third direction is an acute angle, and the second diagonal line bd and The included angle ⁇ acy of the third outcoupling grating in the third direction is an obtuse angle.
  • the third direction is the direction in which the third outcoupling grating 230 faces the incoupling grating 240 .
  • the first grids 212 of the same shape are arranged periodically in a hexagonal lattice on the x-y plane, which has two periodic directions, which are respectively the periodic direction a and the periodic direction b, and the periodic direction There is an angle of 30° between a and the periodic direction b.
  • the period direction a is parallel to the y-axis
  • the distance between the two first gratings 212 along the period direction a is Pa
  • the period direction b forms an angle of 30° with the y-axis
  • the distance between cells 212 is Pb.
  • Pa may be 0.4 ⁇ m to 3 ⁇ m
  • Pb may be 0.2 ⁇ m to 2 ⁇ m.
  • the asymmetric shape adopted by the first grid 212 in the embodiment of the present application can also be understood as that the first grid 212 is an asymmetrical shape of each first grid 212 with respect to the x-axis and the y-axis.
  • the diagonal ce is always longer than the second diagonal df, and the angle ⁇ acy between the first diagonal ce and the positive direction of the y-axis is an obtuse angle, and the angle ⁇ acx between the first diagonal ce and the positive direction of the x-axis is an acute angle.
  • the first outcoupling grating 210 has multiple groups of grating groups 211, each group of grating groups 211 includes a plurality of first gratings 212, and each first grating 212 in each group of grating groups 211 and its adjacent
  • the first grids 212 intersect each other, and the grid groups 211 are spaced apart from each other.
  • each grid group 211 is parallel to each other.
  • Each first grid in each grid group 211 is arranged along the sixth direction. It can also be understood that the upper right and lower left of each first grid 212 intersect with the next first grid 212 adjacent in the oblique direction.
  • the sixth direction is a direction in which the seventh direction is rotated 30 degrees clockwise, and the seventh direction is a direction in which the third outcoupling grating 230 faces the incoupling grating 240 . It should be noted that the seventh direction can also be understood as the positive direction of Pa, that is, the sixth direction is the direction of Pb1.
  • the number of vertices of the first grid 211 is not limited to four, for example, the first grid includes at least five vertices, that is, the first grid 211 may have 5 or more vertices. In the embodiment of the present application, five vertices are taken as an example for illustration.
  • FIG. 14 is a schematic diagram of a partial structure of the first outcoupling grating in the optical structure provided by the embodiment of the present application.
  • the vertices of the first grating 212 include two vertices (vertex c and vertex d) close to the third outcoupling grating 230 and two vertices (vertex e and vertex f) away from the third outcoupling grating 230, and two vertices (vertex e and vertex f) away from the third outcoupling grating 230, near the third outcoupling grating
  • Two vertices (vertex c and vertex d) of the output grating 230 and two vertices (vertex e and vertex f) away from the third outcoupling grating 230 can form the third diagonal line ce and the fourth diagonal line df.
  • the length of the three diagonals ce is greater than the length of the fourth diagonal df, and the angle between the third diagonal ce and the third outcoupling grating 230 in the fourth direction is an acute angle, and the fourth diagonal df and the third The included angle of the outcoupling grating 230 in the fourth direction is an obtuse angle.
  • the fourth direction is the direction in which the third outcoupling grating 230 faces the incoupling grating 240 . That is, the fourth direction can be understood as the third direction.
  • the third diagonal line ce and the fourth diagonal line df can refer to the third diagonal line ce and the fourth diagonal line df shown in FIG. 11 to FIG. 13 , which will not be repeated here.
  • the first grid 212 and the grid group 211 can refer to the first grid 212 and the grid group 211 shown in FIG. 11 to FIG. 13 , which will not be repeated here.
  • the number of vertices of the first grid 211 is not limited to four, five or more than five.
  • the first grid includes three vertices, that is, the first grid 211 may have three vertices. number.
  • FIG. 15 is a schematic diagram of a partial structure of the first outcoupling grating in the optical structure provided by the embodiment of the present application.
  • the vertices of the first grid 212 include close to vertex c, vertex d and vertex e, and vertex c, vertex d and vertex e are connected to each other to form the first vertex connection side cd, the second vertex connection side de and the third vertex connection side ce,
  • the first vertex connection side cd is close to the third outcoupling grating 230, the second vertex connection side de is far away from the third outcoupling grating 230, the length of the first vertex connection side cd is greater than the length of the second vertex connection side de, and the second vertex connection side de
  • An included angle between a vertex connecting side cd and the third outcoupling grating 230 in the fifth direction is an acute angle, and an included angle between a second vertex connecting side de and the third outcoupling grating 230
  • the fifth direction is a direction in which the third outcoupling grating 230 faces the incoupling grating 240 . That is, the fifth direction can be understood as the third direction.
  • the first vertex connecting side cd and the second vertex connecting side de can refer to the third diagonal line ce and the fourth diagonal line df shown in FIG. 11 to FIG. 13 , which will not be repeated here.
  • the first grid 212 and the grid group 211 can refer to the first grid 212 and the grid group 211 shown in FIG. 11 to FIG. 13 , which will not be repeated here.
  • the shapes of the first outcoupling grating 210 and the second outcoupling grating 220 are the same, and the first outcoupling grating 210 and the second outcoupling grating 220 are arranged symmetrically with respect to the third outcoupling grating 230, which can also be understood as
  • the first outcoupling grating 210 and the second outcoupling grating 220 are arranged as mirror images with respect to the third outcoupling grating 230 . That is, the plurality of gratings in the second outcoupling grating 220 are all two-dimensional gratings, and the shape and arrangement of the grid structure of each two-dimensional grating are the same as those of the first grating 212.
  • the second outcoupling grating 220 is a two-dimensional grating having a plurality of second gratings, and all the second gratings in the second outcoupling grating 220 have the same shape as all the first gratings in the first outcoupling grating 210 , and the arrangement is the same.
  • the specific shape and arrangement can refer to FIG. 11 to FIG. 15 , which will not be repeated here.
  • the third outcoupling grating 230 is a two-dimensional grating with a plurality of third gratings, and the third grating is a symmetrical shape, such as a two-dimensional grating with a left-right symmetrical shape, so that the light propagating to the left does not propagate to the right
  • the efficiency of light rays is relatively large, which is beneficial to increase the size of the eye box 260 with a peripheral field of view.
  • the third grating may be arranged in a hexagonal lattice, and the grating vector may refer to FIG. 9 , and its (1, 1) order diffraction vector is parallel to the y-axis.
  • the third grid can be any shape that is symmetrical along the y axis, such as a circle, a positive direction, a rhombus, a hexagon, an octagon, and the like.
  • the area of the third outcoupling grating 230 may be rectangular, for example, the lateral width in the x-axis direction may be 1 mm to 15 mm, and the vertical width in the y-axis direction may be 20 mm-35 mm.
  • the grating periods of the first outcoupling grating 210, the second outcoupling grating 220, and the third outcoupling grating 230 are equal, and the first outcoupling grating 210, the second outcoupling grating 220 And any one of the third outcoupling grating 230 and the waveguide 250 has a refractive index of 1.5-3.
  • the grating period of the in-coupling grating 240 is half of the grating period of any one of the first out-coupling grating 210 , the second out-coupling grating 220 and the third out-coupling grating 230 in a direction perpendicular to the first direction.
  • the grating period of the in-coupling grating 240 is half of the grating period in the y-axis direction of any one of the first out-coupling grating 210 , the second out-coupling grating 220 and the third out-coupling grating 230 .
  • the materials of the in-coupling grating 240 , the first out-coupling grating 210 , the second out-coupling grating 220 and the third out-coupling grating 230 can be silicon, plastic, glass, polymer or some combination of the above materials.
  • the display brightness at each position in the Eyebox260 is determined by the intensity of the outcoupled light at that position, so the intensity of the light 2012, light 2013A, and light 2014A directly determines the display quality of the Eyebox260.
  • the intensity of the light 2012 is much weaker than that of the light 2013A and the light 2014A, resulting in an obvious dark area in the Eyebox 260 corresponding to the light 2012, which will greatly affect the user experience of consumers.
  • the embodiment of the present application proposes an optical structure to improve the light coupling efficiency of the third outcoupling grating 230 while not bringing the difference in intensity between the light rays 2012, such as the optical structure 200 of the embodiment of the present application to combine the third outcoupling grating 230
  • the output grating 230 is divided into multiple areas along the y-axis, and the efficiency of different areas along the y-axis is gradually improved, so that although the chief ray 201 will attenuate during the propagation process, it can make the 2012 or even subsequent out-coupled light beams correspondingly coupled
  • the efficiency of the out-coupling grating is gradually increased, so that although the main light 201 attenuates faster due to the improvement of the efficiency of the third out-coupling grating 230, the energy difference between the light 2012 and even the subsequent out-coupling light can be reduced, so that the light 2012 The energy is closer to the light 2013A and the light 2014A while the intensity difference between the light 2012 is reduced, and finally the brightness and brightness
  • the embodiment of the present application introduces the technology of dividing the third outcoupling grating 230 into multiple gratings, which solves the above-mentioned problems and greatly improves the energy and brightness uniformity of the Eyebox260, so that the embodiment of the present application has It has great implementation significance, and it is a diffractive waveguide structure with excellent performance.
  • the third outcoupling grating 230 includes at least two sub-outcoupling gratings, the junction of two adjacent sub-outcoupling gratings is located in the eye box 260 of the optical structure 200, away from the diffraction of the sub-outcoupling grating 240
  • the efficiency is greater than the diffraction efficiency of the sub-outcoupling gratings close to the incoupling grating 240 . Therefore, the overall energy of the outcoupling light from the third outcoupling grating 230 can be substantially the same, or it can be understood that the energy of the outcoupling light from each sub-coupling grating 230 of the third outcoupling grating 230 is roughly the same. And it will not affect the intensity of light coupled out by the third outcoupling grating 230 . A detailed description will be given below in conjunction with the diagrams.
  • the grating depth of the sub-outcoupling grating far away from the in-coupling grating 240 is greater than the grating depth of the sub-outcoupling grating close to the in-coupling grating 240, so that the sub-outcoupling grating far away from the in-coupling grating 240 can be realized.
  • the diffraction efficiency of the outcoupling grating is greater than that of the sub-outcoupling gratings close to the incoupling grating 240 . That is, the deeper the grating of the optical structure 200 defined in an optional implementation manner of the present application, the higher its diffraction efficiency.
  • FIG. 16 is a schematic diagram of the optical structure provided by the embodiment of the present application
  • FIG. 17 is a schematic diagram of the optical structure provided by the embodiment of the present application.
  • the third outcoupling grating 230 of the optical structure 200 may include three outcoupling sub-gratings, at least a part of each outcoupling sub-grating is located in the eye box 260 .
  • the third outcoupling grating 230 includes a part of the first sub outcoupling grating 231 located on one side of the eye box 260, a part of the second sub outcoupling grating 232 located on the other side of the eye box 260, and a third sub outcoupling grating completely located in the eye box 260.
  • the sub-coupling grating 233 is a schematic diagram of the optical structure provided by the embodiment of the present application
  • FIG. 17 is a schematic diagram of the optical structure provided by the embodiment of the present application.
  • the third outcoupling grating 230 of the optical structure 200 may include three
  • the length of the first sub-outcoupling grating 231 along the arrangement direction of all the sub-outcoupling gratings is greater than the length of the third sub-outcoupling grating 233 in the eye box 260 along the arrangement direction of all the sub-outcoupling gratings. Or it can be understood that the length of the first sub-outcoupling grating 231 along the y-axis direction is greater than the length of the third sub-outcoupling grating 233 located in the eye box 260 along the y-axis direction.
  • the length of the second sub-outcoupling grating 232 along the arrangement direction of all the sub-outcoupling gratings is greater than the length of the third sub-outcoupling grating 233 in the eye box 260 along the arrangement direction of all the sub-outcoupling gratings. Or it can be understood that the length of the second sub-outcoupling grating 232 along the y-axis direction is greater than the length of the third sub-outcoupling grating 233 located in the eye box 260 along the y-axis direction.
  • the length of the second out-coupling sub-grating 232 along the arrangement direction of all the out-coupling sub-gratings may be the same as the length of the first out-coupling sub-grating 231 along the direction in which all the out-coupling sub-gratings are arranged.
  • the first sub-outcoupling grating 231 and the second sub-outcoupling grating 232 may be arranged symmetrically with respect to the third sub-outcoupling grating 233 . It should be noted that the lengths of the first sub-outcoupling grating 231 and the second sub-outcoupling grating 232 along the arrangement directions of all the sub-outcoupling gratings may also be unequal.
  • the length of the first sub-outcoupling grating 231 along the arrangement direction of all the sub-outcoupling gratings and the length of the second sub-outcoupling grating 232 along the arrangement direction of all the sub-outcoupling gratings are larger than the third sub-outcoupling grating 233 The length along the arrangement direction of all sub-outcoupling gratings.
  • the ratio of the length of the first sub-outcoupling grating 231 along the direction in which all sub-outcoupling gratings are arranged to the length of all sub-outcoupling gratings is P1, that is, the first sub-outcoupling grating 231
  • the ratio of the length along the y-axis direction to the length of the third outcoupling grating 230 along the y-axis direction is P1.
  • the ratio of the length of the third sub-outcoupling grating 233 along the arrangement direction of all sub-outcoupling gratings to the length of the arrangement direction of all sub-outcoupling gratings is P2, that is, the length of the third sub-outcoupling grating 233 along the y-axis direction is the same as that of the third sub-outcoupling grating 233 along the y-axis direction
  • the length ratio of the outcoupling grating 230 along the y-axis direction is P2.
  • P1 is greater than or equal to 30%, and P1 is less than or equal to 45%, and P2 is greater than or equal to 10%, and P2 is less than 30%.
  • the part of the first sub-outcoupling grating 231 inside the eye box 260 is the same size as the part of the second sub-outcoupling grating 232 inside the eye box 260 .
  • the junction of the sub-outcoupling gratings of the third outcoupling grating 230 is within the range of B/2 above and below the center of the third outcoupling grating 230 .
  • a sub-outcoupling grating closest to the in-coupling grating 240 such as the first sub-outcoupling grating 231
  • a sub-outcoupling grating farthest from the in-coupling grating 240 such as the second sub-outcoupling grating
  • the diffraction efficiencies of all sub-outcoupling gratings increase proportionally. It can also be understood that the diffraction efficiencies of all sub-outcoupling gratings along the positive direction of the y-axis increase proportionally.
  • the diffraction efficiency of the third sub-outcoupling grating 233 is n times that of the first sub-outcoupling grating 231 , where n is greater than 1.
  • the diffraction efficiency of the second sub-outcoupling grating 232 is n times that of the third sub-outcoupling grating 233 . Therefore, it can be ensured that the energy of the light coupled out by each sub-diffraction grating has little difference.
  • the division of the third outcoupling grating 230 into three regions shown in FIG. 16 and FIG. 17 is only exemplary and does not constitute a limitation on the number of regions of the third outcoupling grating 230 .
  • the third out-coupling grating 230 may include two out-coupling sub-gratings, four out-coupling sub-gratings, five out-coupling sub-gratings and so on. A larger number of sub-coupling gratings will not be described one by one here.
  • the number of sub-outcoupling gratings of the third outcoupling grating 230 is greater than three such as four or five, it still satisfies the requirement that two adjacent outcoupling gratings of the third outcoupling grating 230
  • the junction of the two out-coupling gratings is located in the eye box 260 of the optical structure 200 , and the diffraction efficiency of the out-coupling sub-grating far away from the in-coupling grating 240 is greater than the diffraction efficiency of the out-coupling sub-grating close to the in-coupling grating 240 .
  • the overall energy of the outcoupling light from the third outcoupling grating 230 may be substantially the same, or it may be understood that the energy of outcoupling light from each sub-coupling grating of the third outcoupling grating 230 is approximately the same. And it will not affect the intensity of light coupled out by the third outcoupling grating 230 .
  • the third outcoupling grating 230 includes an outcoupling grating partially positioned on one side of the eye box 260, a sub outcoupling grating partially positioned on the other side of the eye box 260, and two or more sub-coupling gratings completely positioned in the eye box 260. sub-coupling grating.
  • the sum of the lengths of all sub-outcoupling gratings completely located in the eye box 260 along the arrangement direction of all sub-outcoupling gratings of the third outcoupling grating 230 is less than that of any sub-outcoupling grating partially located outside the eye box 260 along the length of the third outcoupling grating.
  • FIG. 18 is a schematic diagram of an optical structure provided by an embodiment of the present application.
  • Fig. 18 shows that the third outcoupling grating 230 includes four sub outcoupling gratings, which are respectively a first sub outcoupling grating 231, a second sub outcoupling grating 232, a third sub outcoupling grating 233 and a fourth sub outcoupling grating 234,
  • the first sub-outcoupling grating 231 and the second sub-outcoupling grating 232 can refer to the above content and will not be repeated here.
  • Both the third sub-outcoupling grating 233 and the fourth sub-outcoupling grating are located in the eye box 260 .
  • FIG. 19 is a schematic diagram of an optical structure provided by an embodiment of the present application.
  • Fig. 19 shows that the third outcoupling grating 230 includes five sub outcoupling gratings, which are respectively the first sub outcoupling grating 231, the second sub outcoupling grating 232, the third sub outcoupling grating 233, the fourth sub outcoupling grating 234 and the outcoupling sub grating 234.
  • the fifth sub-outcoupling grating 235 wherein the first sub-outcoupling grating 231 and the second sub-outcoupling grating 232 can refer to the above content and will not be repeated here.
  • the third sub-outcoupling grating 233 , the fourth sub-outcoupling grating and the fifth sub-outcoupling grating are all located in the eye box 260 .
  • the intensity of the light 2012, the light 2013A, and the light 2014A directly determines the display quality of the Eyebox 260, but in practical applications the intensity of the light 2012 is much weaker than that of the light 2013A and the light 2014A.
  • the third outcoupling grating 230 capable of outcoupling the light 2012 is arranged in different regions, which can make the energy of the light 2012 closer to the light 2013A and the light 2014A while reducing the intensity difference between the light 2012, finally making the The brightness and brightness uniformity of Eyebox260 have been improved at the same time, and the energy and brightness uniformity of Eyebox260 have been greatly improved. In practical applications, the energy of the light 2013A and the light 2014A will also be lost along with the propagation of the light.
  • the first outcoupling grating 210 and the second outcoupling grating 220 are also arranged in regions. A detailed description will be given below in conjunction with the diagrams.
  • FIG. 20 is a schematic diagram of an optical structure provided by an embodiment of the present application.
  • the first outcoupling grating 210 , the second outcoupling grating 220 and the third outcoupling grating 230 in the optical structure 200 shown in FIG. 20 are equally divided into areas.
  • the sub-area arrangement of the third outcoupling grating 230 can refer to FIG. 16 to FIG. 19 , which will not be repeated here.
  • the first outcoupling grating 210 includes at least two sub outcoupling gratings, the number of sub outcoupling gratings in the first outcoupling grating 210 is the same as the number of outcoupling sub gratings in the third outcoupling grating 230 such as three. And the junction of two adjacent sub-outcoupling gratings in the first outcoupling grating 210 is located in the eye box 260 of the optical structure 200 . In the first outcoupling grating 210 , the diffraction efficiency of the outcoupling sub-grating far away from the incoupling grating 240 is greater than the diffraction efficiency of the outcoupling sub-grating close to the incoupling grating 240 .
  • the overall energy of the light coupled out by the first outcoupling grating 210 may be substantially the same, or it may be understood that the energy of the light coupled out by each sub-coupling grating 210 of the first outcoupling grating 210 is approximately the same. And it will not affect the intensity of light coupled out by the first outcoupling grating 210 .
  • the first out-coupling grating 210 includes a first out-coupling sub-grating 211 , a second out-coupling sub-grating 212 and a third out-coupling sub-grating 213 .
  • the first sub-out-coupling grating 211 can refer to the first sub-out-coupling grating 231
  • the second sub-out-coupling grating 212 can refer to the third sub-out-coupling grating 233
  • the third sub-out-coupling grating 213 can refer to the second
  • the sub-coupling grating 232 is omitted here.
  • the number of sub-regions of the first outcoupling grating 210 and the number of subregions of the third outcoupling grating 230 are both greater than three, referring to FIG. 18 and FIG. 19 , in the first sub-outcoupling grating 211 and the third sub-coupling grating 213 are arranged with 2 sub-coupling gratings, 3 sub-coupling gratings or more sub-coupling gratings, and their arrangement is the same as that of the third sub-coupling grating 230 The arrangements are the same, and will not be repeated here.
  • the second outcoupling grating 220 includes at least two sub outcoupling gratings, the number of sub outcoupling gratings in the second outcoupling grating 220 is the same as the number of outcoupling sub gratings in the third outcoupling grating 230 such as three. And the junction of two adjacent sub-outcoupling gratings in the second outcoupling grating 220 is located in the eye box 260 of the optical structure 200 .
  • the diffraction efficiency of the sub-outcoupling gratings in the second outcoupling grating 220 far away from the in-coupling grating 240 is greater than the diffraction efficiency of the sub-outcoupling gratings close to the in-coupling grating 240 . Therefore, the overall energy of the light coupled out by the second outcoupling grating 220 may be substantially the same, or it may be understood that the energy of the light coupled out by each sub-coupling grating of the second outcoupling grating 220 is approximately the same. And it will not affect the intensity of light coupled out by the second outcoupling grating 220 .
  • the second out-coupling grating 210 includes a first out-coupling sub-grating 221 , a second out-coupling sub-grating 222 and a third out-coupling sub-grating 223 .
  • the first sub-out-coupling grating 221 can refer to the first sub-out-coupling grating 231
  • the second sub-out-coupling grating 222 can refer to the third sub-out-coupling grating 233
  • the third sub-out-coupling grating 223 can refer to the second
  • the sub-coupling grating 232 is omitted here.
  • first outcoupling grating 210 the second outcoupling grating 220, and the third outcoupling grating 230 is arranged in a sub-regional manner, which is also implemented in this application. within the bounds of the example. It is also within the scope defined by the embodiment of the present application that only two of the first outcoupling grating 210 , the second outcoupling grating 220 and the third outcoupling grating 230 are arranged in a region-by-region manner.
  • the first outcoupling grating 210, the second outcoupling grating 220 and the third outcoupling grating 230 can all be two-dimensional gratings, such as shown in FIGS. 1 to 15 The content will not be repeated here. It should be noted that when the third outcoupling grating 230 includes a plurality of sub outcoupling gratings, the first outcoupling grating 210 and the second outcoupling grating 220 may also adopt other grating structures such as one-dimensional gratings.
  • the third outcoupling grating 230 is two-dimensional grating
  • the incoupling grating 240 is one-dimensional grating
  • the grating periods of the out-coupling grating 220 and the in-coupling grating 240 are equal, and the grating period of the third out-coupling grating 230 along the arrangement direction of all the sub-coupling gratings of the third out-coupling grating 230 is equal to that of the first out-coupling grating 210 and the second out-coupling grating. Twice the grating period of any one of the output grating 220 and the in-coupling grating 240 .
  • FIG. 21 is a schematic diagram of an optical structure provided by an embodiment of the present application.
  • the optical structure 300 shown in FIG. 21 includes an in-coupling grating 340 , a first out-coupling grating 320 , a second out-coupling grating 320 , a third out-coupling grating 330 and a waveguide 350 .
  • the coupling-in grating 340, the first coupling-out grating 320, the second coupling-out grating 320, and the third coupling-out grating 330 are all arranged on the waveguide 340, and the coupling-in grating 340, the first coupling-out grating 320, and the second coupling-out grating 320 Any one of the third outcoupling grating 330 can be arranged on any side of the waveguide 350, such as the incoupling grating 340, the first outcoupling grating 320, the second outcoupling grating 320, and the third outcoupling grating 330 are all arranged on the waveguide The first face 352 of the body 350.
  • waveguide 350 reference may be made to the waveguide 250, which will not be repeated here.
  • waveguide 250 reference may be made to the waveguide 250, which will not be repeated here.
  • coupling-in grating 340 reference may be made to the coupling-in grating 240, which will not be repeated here.
  • FIG. 22 is a schematic diagram of an optical structure provided by an embodiment of the present application.
  • the light transmitted through the third outcoupling grating 330 such as the light at the edge field angle, is kept within the range of the third outcoupling grating 330 and will not be transmitted to the third outcoupling grating 330 .
  • a component of the out-coupling grating 310 or the second out-coupling grating 320 is kept within the range of the third outcoupling grating 330 and will not be transmitted to the third outcoupling grating 330 .
  • light 301 at the edge field of view emitted by the in-coupling grating 340 is incident on the third out-coupling grating 330 through the waveguide 350, and interacts with the third out-coupling grating 330 to generate light rays 301 along the outgoing direction of the optics 301.
  • a component 304 , the first component 304 of the light remains within the range of the third outcoupling grating 330 and will not be transmitted to the first outcoupling grating 310 or the second outcoupling grating 320 .
  • the third outcoupling grating 330 acts on the edge field angle light 301
  • other light components such as the second component of light traveling along the z-axis direction and the third light component traveling along the positive direction of the x-axis.
  • Component the fourth component of light traveling in the opposite direction of the x-axis.
  • the first light component 304 will interact with the third outcoupling grating 320 multiple times to form multiple light components.
  • the third outcoupling grating 330 may include a first side 3301 and a second side 3302 , the first side 3301 is away from the incoupling grating 340 , and the second side 3302 is close to the incoupling grating 340 , the first side 3301 and the second side 3302 are disposed opposite to each other.
  • the length of the first side 3301 along the arrangement direction of the first outcoupling grating 320 , the second outcoupling grating 320 and the third outcoupling grating 330 is longer than that of the second side 3302 along the direction of the first outcoupling grating 320 and the second outcoupling grating 320 .
  • the length in the arrangement direction of the third outcoupling grating 330 is greater than 10 mm, and the length of the second side 3302 is greater than 4 mm.
  • FIG. 23 is a schematic diagram of an optical structure provided by an embodiment of the present application. Assuming that the light 301 incident on the in-coupling grating 340 is at an angle a between the x-z plane and the z-axis, and is at an angle b between the y-z plane and the z-axis, then the first light component 304 of the incident light after being coupled through the in-coupling grating 340 The light vectors in the x-direction and y-direction are:
  • the length E of the first side 3301 of the third outcoupling grating 330 needs to satisfy the following relationship:
  • the embodiment of the present application can ensure that the first light component 304 of the incident light can be kept within the range of the third outcoupling grating 330 .
  • the width of the third outcoupling grating 330 gradually decreases from the first side 3301 to the second side 3302 . That is, the width of the third outcoupling grating 330 gradually increases from the second side 3302 to the first side 3301 .
  • the width of the third outcoupling grating 330 is the length of the third outcoupling grating 330 along the arrangement direction of the first outcoupling grating 310 , the third outcoupling grating 330 and the second outcoupling grating 320 . such as the length along the x-axis.
  • the third outcoupling grating 330 has an isosceles trapezoidal structure as a whole.
  • the shape of the third outcoupling grating 330 in the embodiment of the present application is not limited, as long as the third outcoupling grating 330 satisfies that the length of the first side 3301 is greater than the length of the second side 3302, the third outcoupling grating All shapes of 330 are within the protection scope of the embodiment of the present application.
  • the third outcoupling grating 330 may further include a third side 3303 and a fourth side 3304 .
  • the third side 3303 and the fourth side 3304 are arranged opposite to each other. It can be understood that the third side 3303 and the fourth side 3304 are located on opposite sides of the third outcoupling grating 330, and the first side 3301 and the second side 3302 are located at opposite ends of the third outcoupling grating 330 .
  • the third side 3303 is connected with the first side 3301 and the second side 3302 , such as the third side 3303 connects one end of the first side 3301 and one end of the second side 3302 .
  • the fourth side 3304 is connected with the first side 3301 and the second side 3302 , such as the fourth side 3304 connects the other end of the first side 3301 and the other end of the second side 3302 .
  • the third side 3303 and the fourth side 3304 are arranged axisymmetrically with respect to the first side 3301 and the second side 3302 .
  • the distance between the first side 3301 and the second side 3302 may be 20 mm to 35 mm.
  • the third outcoupling grating 330 is a two-dimensional grating with a square lattice structure. It is possible to make the first outcoupling grating 310, the second outcoupling grating 320 and the third outcoupling grating 330 close to the side edge of the outcoupling grating 340 without pupil expansion area, such as the first outcoupling grating 310, the second outcoupling grating 320 And the edge of the third outcoupling grating 330 close to the incoupling grating 340 is flush, and it will have an effect when it receives light incoupling.
  • the ineffective grating area (that is, the pupil expansion area) will be saved, and the overall effective outcoupling grating area of the optical structure 300 can be increased, and the utilization rate of the grating area is higher. Improve the overall efficiency of the diffractive waveguide.
  • the third outcoupling grating 330 may also be a two-dimensional grating with a hexagonal lattice structure.
  • the first outcoupling grating 310 and the second outcoupling grating 320 are both one-dimensional gratings.
  • the first outcoupling grating 310 and the second outcoupling grating 320 are symmetrically arranged with respect to the third outcoupling grating 330 .
  • the third outcoupling grating 330 includes at least two sub-outcoupling gratings, the junction of two adjacent sub-outcoupling gratings is located in the eye box of the optical structure 300, and the diffraction efficiency of the sub-outcoupling grating far away from the in-coupling grating 340 Greater than the diffraction efficiency of the sub-outcoupling grating close to the incoupling grating 340 . Therefore, the overall energy of the outcoupling light from the third outcoupling grating 330 may be substantially the same, or it may be understood that the energy of the outcoupling light from each sub-coupling grating 330 of the third outcoupling grating 330 is approximately the same. And it will not affect the intensity of light coupled out by the third outcoupling grating 330 . A detailed description will be given below in conjunction with the diagrams.
  • the grating depth of the sub-outcoupling grating far away from the in-coupling grating 340 is greater than the grating depth of the sub-outcoupling grating close to the in-coupling grating 340, so that the sub-outcoupling grating far away from the in-coupling grating 340 can be realized.
  • the diffraction efficiency of the outcoupling grating is greater than that of the sub-outcoupling gratings close to the incoupling grating 340 . That is, the deeper the grating of the optical structure 300 defined in an optional implementation manner of the present application, the higher its diffraction efficiency.
  • FIG. 24 is a schematic diagram of an optical structure provided by an embodiment of the present application.
  • the third out-coupling grating 330 includes three out-coupling sub-gratings, respectively a first out-coupling sub-grating 331 , a second out-coupling sub-grating 332 , and a third out-coupling sub-grating 333 . At least a portion of each sub-outcoupling grating is located within eye box 260 .
  • the third outcoupling grating 330 includes a part of the first sub outcoupling grating 231 located on one side of the eye box, a part of the second sub outcoupling grating 332 located on the other side of the eye box, and a third sub outcoupling grating completely located in the eye box.
  • Grating 333 includes a part of the first sub outcoupling grating 231 located on one side of the eye box, a part of the second sub outcoupling grating 332 located on the other side of the eye box, and a third sub outcoupling grating completely located in the eye box.
  • the relationship between the first sub-out-coupling grating 331, the second sub-out-coupling grating 332, and the third sub-out-coupling grating 333 can be referred to the first sub-outcoupling grating 231, the second sub-out-coupling grating 232, the third sub-coupling grating
  • the outcoupling grating 233 is omitted here.
  • the diffraction efficiencies of all sub-outcoupling gratings increase proportionally. It can also be understood that the diffraction efficiencies of all sub-outcoupling gratings along the positive direction of the y-axis increase proportionally.
  • the diffraction efficiency of the third sub-outcoupling grating 333 is n times that of the first sub-outcoupling grating 331 , where n is greater than 1.
  • the diffraction efficiency of the second sub-outcoupling grating 332 is n times that of the third sub-outcoupling grating 333. Therefore, it can be ensured that the energy of the light coupled out by each sub-diffraction grating has little difference.
  • the division of the third outcoupling grating 330 into three regions shown in FIG. 24 is only exemplary and does not limit the number of regions of the third outcoupling grating 330 .
  • the third out-coupling grating 330 may include two out-coupling sub-gratings, four out-coupling sub-gratings, five out-coupling sub-gratings and so on. A larger number of sub-coupling gratings will not be described one by one here.
  • the number of sub-outcoupling gratings of the third outcoupling grating 330 is greater than three such as four or five, it still satisfies the requirement that two adjacent outcoupling gratings of the third outcoupling grating 330
  • the junction of the two out-coupling gratings is located in the eye box of the optical structure 300 , and the diffraction efficiency of the out-coupling sub-grating far away from the in-coupling grating 340 is greater than the diffraction efficiency of the out-coupling sub-grating close to the in-coupling grating 340 .
  • the overall energy of the outcoupling light from the third outcoupling grating 330 may be approximately the same, or it may be understood that the energy of the outcoupling light from each sub-coupling grating 330 of the third outcoupling grating 330 is approximately the same. And it will not affect the intensity of light coupled out by the third outcoupling grating 330 .
  • the third outcoupling grating 330 includes an outcoupling grating partially located on one side of the eye box, a sub outcoupling grating partially located on the other side of the eye box, and two or more sub outcoupling gratings completely located in the eye box. raster.
  • the sum of the lengths of all sub-outcoupling gratings completely located inside the eye box along the arrangement direction of all sub-outcoupling gratings of the third out-coupling grating 330 is less than that of any sub-outcoupling grating partially located outside the eye box along the length of the third out-coupling grating. All the sub-couplings of 330 have the length in the arrangement direction of the grating. It can also be understood that the sum of the lengths along the y-axis direction of all sub-outcoupling gratings completely located inside the eye box is smaller than the length along the y-axis direction of any sub-outcoupling grating partially located outside the eye box. For details, reference may be made to the above content such as FIG. 18 and FIG. 19 , which will not be repeated here.
  • the optical structure 200 and the optical structure 300 defined in the above embodiments of the present application can all be applied in an optical device, and the optical device can include a projector and any optical structure above, such as any optical structure 200 or any optical structure.
  • the optical device may be an augmented reality device or a virtual reality device.

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Abstract

一种光学结构和光学装置，包括波导体和设于其上的耦入光栅、第一耦出光栅、第二耦出光栅和第三耦出光栅；第三耦出光栅位于第一、第二耦出光栅之间，耦入光栅位于第一、第二、第三耦出光栅同一侧；耦入光栅发射的光线经波导体入射到第三耦出光栅，以产生保持在第三耦出光栅范围内的光线第一分量。提高了光学结构的衍射效率。

Description

光学结构和光学装置
本申请要求于2021年09月16日提交中国专利局、申请号为202111089009.0、申请名称为“光学结构和光学装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及光学技术领域，尤其涉及一种光学结构和光学装置。
背景技术
光学装置诸如增强现实(Augmented Reality，缩写为AR)装置、虚拟现实(Virtual Reality，缩写为VR)装置可以通过各自的显示器件显示图像。AR装置和/或VR装置相关技术越来越多地应用于各个领域，诸如广泛应用到军事、医疗、建筑、教育、工程、影视、娱乐等领域。
其中，AR眼镜是AR装置的主要实现方式之一，它的近眼显示系统是将显示器件上的像素，通过一系列光学成像元件形成远处的虚像并投射到人眼中。AR眼镜产品需要满足透视(See-through)需求，既要看到真实的外部世界，也要看到虚拟信息，所以成像系统不能挡在视线前方。比如增加一个或一组光学组合器，通过“层叠”的形式，将虚拟信息和真实场景融为一体。
相关技术中，AR眼镜有着折反射、反射光波导、一维衍射光波导、二维衍射光波导、全息光波导等众多光学实现方案，其中二维衍射光波导(Two-dimensional Diffractive Waveguide，缩写为TDDW)轻薄和外界光线的高穿透特性，色彩还原性好，FOV大等特点被认为是最有前景的消费级AR眼镜光学方案。
相关技术中，一般TDDW架构的耦入光栅将来自投影光机的光线耦入波导，被耦入波导的光线经全内反射朝耦出光栅前进，在到达耦出光栅后会经衍射被分为向左传播的扩瞳光线与向右传播的扩瞳光线。光线在每次与耦出光栅作用时会将一部分能量耦出到人眼中，使用户看到投影光机的画面。当边缘视场光线入射时，边缘视场角光线经过耦出光栅所产生的分量包括一沿该视场角光线传播方向传输的分量，该边缘视场角光线在实际传播过程中会经过不同的耦出光栅，导致衍射效率低。
发明内容
本申请实施例提供一种光学结构和光学装置，提高光学结构的衍射效率。
本申请实施例提供一种光学结构，其包括：
波导体；
耦入光栅，设置于所述波导体；
第一耦出光栅，设置于所述波导体；
第二耦出光栅，设置于所述波导体；和
第三耦出光栅，设置于所述波导体，所述第三耦出光栅位于所述第一耦出光栅和第二耦出光栅之间， 且所述耦入光栅位于第一耦出光栅、第二耦出光栅及第三耦出光栅同一侧；
由所述耦入光栅发射出来的光线经所述波导体入射到所述第三耦出光栅，并与所述第三耦出光栅作用产生包括沿所述光线出射方向的光线第一分量，所述光线第一分量保持在所述第三耦出光栅范围内、而不会传导至所述第一耦出光栅或所述第二耦出光栅。
本申请实施例还提供一种光学装置，其包括：
投影光器，所述投影光器被配置为提供增强现实或虚拟现实图像；和
如上任一项所述的光学结构。
附图说明
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍。
图1为本申请实施例提供的光学结构的结构示意图。
图2为本申请实施例提供的光学结构的立体图。
图3为本申请实施例提供的中心视场光线在光学结构中传输的示意图。
图4为本申请实施例提供的边缘视场光线在光学结构中传输的示意图。
图5为本申请实施例提供的光学结构光线传输过程在k空间的原理示意图。
图6为本申请实施例提供的中心视场光线在光学结构沿一平面传输的示意图。
图7为本申请实施例提供的边缘视场光线在光学结构沿一平面传输的示意图。
图8为本申请实施例光学结构的应用场景示意图。
图9为本申请实施例第一耦出光栅的光栅矢量示意图。
图10为本申请实施例提供的光学结构以及光学结构中第一耦出光栅的局部结构示意图。
图11为本申请实施例提供的光学结构中第一耦出光栅的局部结构示意图。
图12为本申请实施例提供的光学结构中第一耦出光栅的局部结构示意图。
图13为本申请实施例提供的光学结构中第一耦出光栅的局部结构示意图。
图14为本申请实施例提供的光学结构中第一耦出光栅的局部结构示意图。
图15为本申请实施例提供的光学结构中第一耦出光栅的局部结构示意图。
图16为本申请实施例提供的光学结构的示意图。
图17为本申请实施例提供的光学结构的示意图。
图18为本申请实施例提供的光学结构的示意图。
图19为本申请实施例提供的光学结构的示意图。
图20为本申请实施例提供的光学结构的示意图。
图21为本申请实施例提供的光学结构的示意图。
图22为本申请实施例提供的光学结构的示意图。
图23为本申请实施例提供的光学结构的示意图。
图24为本申请实施例提供的光学结构的示意图。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述。显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域技术人员在没有付出创造性劳动前提下所获得的所有其他实施例，都属于本申请的保护范围。
请参阅图1，图1为本申请实施例提供的光学结构的结构示意图，并示出了参考系(x，y，z)。光学结构200包括波导体250、设置于该波导体上的耦入光栅240以及多个耦出光栅(耦出光栅210、耦出光栅220以及耦出光栅230)。其中，光学结构200的波导体260、耦入光栅240以及多个耦出光栅(耦出光栅210、耦出光栅220以及耦出光栅230)均是在x-y平面排布。
其中，波导体250作为光学结构200的载体。波导体250能够传导光信号，诸如通过内部全反射的方式传导光信号。波导体250可以具有两个相反设置的表面，诸如包括相反设置的第一表面252和第二表面。其中，第二表面与第一表面252相反设置，在图一的视图中被遮挡住而未展示出。
其中，耦入光栅240设置于波导体250的其中一个表面，诸如第一表面252。耦入光栅240可以接收来自投影光机(图中未示出)发出的光信号(也可以称为光线)，并将该光信号耦入波导体250。波导体250在接收到来自耦入光栅240耦入的光信号后可以传导该光信号。
耦入光栅240可以为闪耀光栅、矩形光栅以及倾斜光栅中的任一种。耦入光栅240可以采用一维光栅。
多个耦出光栅可以包括第一耦出光栅210、第二耦出光栅220以及第三耦出光栅230。第一耦出光栅210、第二耦出光栅220以及第三耦出光栅230均设置于波导体250，第三耦出光栅230位于第一耦出光栅210和第二耦出光栅220之间。在一些实施方式中，第一耦出光栅210、第二耦出光栅220以及第三耦出光栅230设置于波导体250的同一面，诸如第一表面252。需要说明的是，第一耦出光栅210、第二耦出光栅220以及第三耦出光栅230也可以均设置于波导体250的另一面，即与第一表面相反的第二表面。
在其他一些实施方式中，第一耦出光栅210、第二耦出光栅220以及第三耦出光栅230中的其中一个可以设置于波导体250的其中一面诸如第一表面252，而第一耦出光栅210、第二耦出光栅220以及第三耦出光栅230中的另外两个可以设置于波导体250的另一面及第二表面。可以理解的是，耦入光栅240、第一耦出光栅210、第二耦出光栅220以及第三耦出光栅230四者任一组合设置于波导体250的任何一面均在本申请实施例的保护范围内。
本申请实施例耦入光栅240可以设置于第一耦出光栅210、第二耦出光栅220以及第三耦出光栅 230的同一侧，且耦入光栅240和第三耦出光栅230并排排列。本申请实施例第一耦出光栅210和第二耦出光栅220的形状相同，且第一耦出光栅210和第二耦出光栅220相对于第三耦出光栅230对称设置，也可以理解为第一耦出光栅210、第二耦出光栅220相对于第三耦出光栅230镜像设置。需要说明的是，第一耦出光栅210和第二耦出光栅220的形状也可以不相同，或者不相对于第三耦出光栅230对称设置。
其中波导体250可以将耦入光栅240所耦入的光信号经过全内反射朝第一耦出光栅210、第二耦出光栅220以及第三耦出光栅230前进，在到达第一耦出光栅210、第二耦出光栅220以及第三耦出光栅230后会经衍射被分为几部分朝向多个方向传导。其中一部分光信号耦出到达人眼中，使用户看到投影光机的画面。
请参阅图2，图2为本申请实施例提供的光学结构的立体图，且图2示出了中心视场光线入射经过衍射后光信号传输情况，并示出了参考系(x，y，z)。中心视场光线入射到耦入光栅240后，耦入光栅240经过波导体250朝向第三耦出光栅230传输光线201。光线201在与第三耦出光栅230作用后经衍射被分裂为4束光线，分别为光线2011、光线2012、光线2013和光线2014。
光线2011沿光线201的原路前进。可以理解的是，光线201在与第三耦出光栅230作用经衍射后被分裂为4束光线，光线2011沿光线201原路前进过程中会多次与第三耦出光栅230作用，每次作用均经衍射后被分裂为4束光线。即光线2011沿光线201原路前进过程中多次与第三耦出光栅230作用经衍射后分裂出多条光线2013、多条光线2014、多条光线2014和多条2011，由于多条2011均沿光线201的原路前进而展示出为一条光线。光线2011每与第三耦出光栅230作用一次，再沿原路前进的光线能量会下降。
光线2012直接从第三耦出光栅230耦出，可理解为光线2012基于x-y平面朝向z的正方向耦出。本申请实施例将直接从第三耦出光栅230耦出的光线全部定义为光线2012。可以理解的是，从第三耦出光栅230不同位置所直接耦出的不同光线的能量是不同的。
光线2013在与第一耦出光栅210作用后经衍射被分裂为2束光线，分别为光线2013A和光线2013B。光线2013A直接从第一耦出光栅210耦出，可理解为光线2013A基于x-y平面朝向z的正方向耦出。光线2013B沿光线2013的原路前进。本申请实施例将从第三耦出光栅230朝向第一耦出光栅210传播的光线定义为光线2013，光线2013具有多条，每一条光线2013均与第一耦出光栅210作用后经衍射被分裂出多条光线2013A和多条光线2013B。可以理解的是，不同的光线2013的能量不同，不同的光线2013A的能量不同，不同的光线2013B的能量不同。
光线2014在与第二耦出光栅220作用后经衍射被分裂为2束光线，分别为光线2014A和光线2014B，光线2014A直接从第二耦出光栅210耦出，可理解为光线2014A基于x-y平面朝向z的正方向耦出。光线2014B沿光线2014的原路前进。本申请实施例将从第三耦出光栅230朝向第二耦出光栅220传播的光线定义为光线2014，光线2014具有多条，每一条光线2014均与第二耦出光栅220作用后经衍射被分裂出多条光线2014A和多条光线2014B。可以理解的是，不同的光线2014的能量不同，不同 的光线2014A的能量不同，不同的光线2014B的能量不同。
基于x-y平面朝向z的正方向耦出的光线会入射到人眼中，使用户看到投影光机的画面。请继续参阅图2，如图2所示的示例中从第三耦出光栅230朝向z的正方向耦出的光线2012会射入到人眼中，从第一耦出光栅210朝向z的正方向耦出的光线2013A会射入到人眼中，从第二耦出光栅220朝向z的正方向耦出的光线2014A会射入到人眼中。
需要说明的是，图2所示出的光线2011、光线2012、光线2013、光线2014是示例性的，并没有对光学结构200耦出光线的条数进行限制。或者可以理解为图2示出了本申请实施例光学结构200在耦出光线时的一部分光线，其余光线未示出。
请参阅图3和图4，图3为本申请实施例提供的中心视场光线在光学结构中传输的示意图，图4为本申请实施例提供的边缘视场光线在光学结构中传输的示意图。耦入光栅240将其耦出的光线201通过波导体250传输到第三耦出光栅230，与第三耦出光栅230发生作用分裂出多条光线诸如光线2011、光线2012、光线2013和光线2014，其中光线2011、光线2012、光线2013和光线2014的传输方向可以参阅图2及相关内容，在此不再赘述。需要说明的是，在x-y平面内光线2012用圆点替代。光线2013与第一耦出光栅210发生作用分裂出多条光线诸如光线2013A和光线2013B，光线2013A和光线2013B可以参阅图2及相关内容，在此不再赘述。需要说明的是，在x-y平面内光线2013A用圆点替代。光线2014与第二耦出光栅220发生作用分裂出多条光线诸如光线2014A和光线2014B，光线2014A和光线2014B可以参阅图2及相关内容，在此不再赘述。需要说明的是，在x-y平面内光线2014A用圆点替代。从图3和图4示意可知，每个圆点表示一光线与一耦出光栅发生作用的光线，且圆点所表示的光线可以入射到人眼中。
图3和图4示出了每个耦出光栅均可以耦出多条沿z轴正方向的光线。
需要说明的是，图3和图4中圆点所表示的光线仅有一部分会被射入到人眼。
请参阅图5，图5为本申请实施例提供的光学结构光线传输过程在k空间的原理示意图，并示出了参考系(kx，ky，kz)。图5所示两个圆半径分别是环境折射率和波导片折射率，其中小圆半径即位于内圈圆形半径为环境折射率，大圆半径即外圈半径为波导折射率。矩形表示视场(FOV)，每一个矩形均表示一个视场，不同位置的矩形表示视场光线的不同状态，比如圆环中心矩形代表视场从投影光器向波导体250入射或者耦出光线(光线2012、光线2013A、光线2014A)，圆环内(即两个圆形之间)矩形代表视场光线经光栅(第一耦出光栅210、第二耦出光栅220和耦入光栅240)耦合后在波导体240内传播。如果视场位于小圆内则表示光线可以耦出波导体250，如果视场位于圆环中则表示光线在波导体250内传播，而视场位于大圆外则意味着光线实际上并不存在。在坐标原点视场经过耦入光栅240衍射k1耦入进波导体250，随后光线201经第三耦出光栅230的6个衍射分量k22变化到它k空间周围的6个不同位置，其中光线2013、光线2014还在圆环之中，代表它们会沿着kx轴分别向左与向右全内反射传播，成为扩瞳光线。还有一部分光线会经衍射向上平移，与原入射图像重合，代表它们(诸 如光线2012)会直接耦出。剩下3个位置均在圆环之外，代表这3个衍射分量并不存在。光线201并不是所有的能量都被衍射了，相反，它还会保留大部分的能量不变，这代表还有大部分能量继续沿着光线201的传播方向进行全内反射传播。
本申请实施例将光学结构200耦出并射入到人眼所在的区域定义为眼盒(Eyebox)260。即位于眼盒260内的且沿z轴正方向耦出的光线会射入到人眼。
下面对眼盒进行说明。
请参阅图6至图8，图6为本申请实施例提供的中心视场光线在光学结构沿一平面传输的示意图，图7为本申请实施例提供的边缘视场光线在光学结构沿一平面传输的示意图，图8为本申请实施例光学结构的应用场景示意图。假设入射视场在y-z平面内与z轴夹角范围为-a°到a°，即入射最大视场F2在y-z平面内与z轴夹角范围为a°，入射最小视场F1在y-z平面内与z轴夹角范围为-a°。人眼到波导体250的距离(eyerelief)为b，即Eyebox平面或者说人眼观察平面到波导体250的距离为b。那么眼盒260在y轴方向上的长度为B，其中B＝A-2b*tan(a)。
其中A为第一耦出光栅210在y轴方向上的最小长度，A也可以为第二耦出光栅210在y轴方向上的最小长度。需要说明的是，本申请实施例第一耦出光栅210在y轴方向上的最小长度和第二耦出光栅220在y轴方向上的最小长度相同。
本申请一种可选实施例中，眼盒260的中心可以与第三耦出光栅230的中心重合。
请继续参阅图2、图3和图6，当中心视场光线入射到光学结构200时，第一耦出光栅210、第二耦出光栅220和第三耦出光栅230所耦出的光线诸如光线2012、光线2013A和光线2014A均有一部分会在眼盒260内，即会射入到人眼中。
请继续参阅图4和图7，当边缘视场光线入射到光学结构200时，只有第二耦出光栅220和第三耦出光栅230所耦出的光线2012和光线2014A的一部分会在眼盒260内，而第一耦出光栅210所耦出的光线诸如光线2013A基本全部不在眼盒260内。换言之，第二耦出光栅220和第三耦出光栅230所耦出的光线的能量被利用到，第一耦出光栅210所耦出的光线的能量被浪费掉，往往会造成边缘视场的出瞳均匀性较差。
而且在相关技术中的波导架构下，边缘视场的出瞳均匀性是明显差于中心视场的，这代表在某些Eyebox位置观看投影光机画面时，中心视场与边缘视场亮度的差距会比较大，造成用户观看不适。
基于此本申请实施例所界定的第一耦出光栅210采用二维光栅结构，并具有多个第一栅格，且每个栅格为非对称形状，从而使得第一耦出光栅210在第一方向传播的光线效率高于第一耦出光栅210在第二方向传播的光线效率。使得第一耦出光栅210所耦出光线中被浪费掉的部分的能量相对于其他光线的能量小，进而就可以提高各视场的出瞳亮度与出瞳均匀性，缩小各视场能量之间的差异。诸如可以提高边缘视场的出瞳亮度与出瞳均匀性，缩小边缘视场能量和中心视场能量之间的差异。尤其是当该光学结构200应用到头戴显示产品诸如AR中时可以提升抑制太阳光的彩虹纹效应，提升该产品的画质。
其中第一方向为第一耦出光栅210朝向第二耦出光栅220的方向，诸如图1所示x轴的负方向。第二方向为第二耦出光栅220朝向第一耦出光栅210的方向，诸如图1所示x轴的正方向。本申请实施例第一方向和第二方向相反。
请参阅图9，图9为本申请实施例第一耦出光栅的光栅矢量示意图。第一耦出光栅210具有多级衍射矢量，包括(1，1)，(1，0)，(0，1)，(0，-1)，(-1，0)，(-1，-1)。第一耦出光栅210衍射各级次中的(1，0)级与(-1，0)级衍射效率会明显高于(0，1)级与(0，-1)级，当光线201入射到第一耦出光栅210时，光线2014B是由第一耦出光栅210的(-1，0)级衍射所产生，光线2013B是由第一耦出光栅210的(0，1)级衍射所产生，因此，其向图示中的左(第一方向)传播的光线2014B效率大大高于向图示中的右(第二方向)传播的光线2013B。
为了详细说明本申请实施例第一栅格212采用的非对称形状能够使得第一耦出光栅210在第一方向传播的光线效率高于第一耦出光栅210在第二方向传播的光线效率。下面结合第一耦出光栅210的示意图进行描述。
请参阅图10至图13，图10为本申请实施例提供的光学结构以及光学结构中第一耦出光栅的局部结构示意图，图11为本申请实施例提供的光学结构中第一耦出光栅的局部结构示意图，图12为本申请实施例提供的光学结构中第一耦出光栅的局部结构示意图，图13为本申请实施例提供的光学结构中第一耦出光栅的局部结构示意图。其中图10示出的第一耦出光栅210的局部结构M定义为第一部分M。即第一部分M中的多个第一栅格212为第一耦出光栅210的一部分第一栅格212。
第一耦出光栅210的多个第一栅格212中的所有第一栅格212的形状可以大致相同。比如每一第一栅格212均具有四个顶点诸如顶点c、顶点d、顶点e、顶点f，该四个顶点可以形成第一对角线ce和第二对角线df。第一对角线ce的长度大于第二对角线df的长度，且第一对角线ac与第三耦出光栅230在第三方向的夹角θacx为锐角，第二对角线bd与第三耦出光栅在第三方向的夹角θacy为钝角。
其中第三方向为第三耦出光栅230朝向耦入光栅240的方向。
本申请一种可选实施例中，相同形状的第一栅格212在x-y平面上成六方晶格周期性排布，其具有两个周期方向，分别为周期方向a与周期方向b，周期方向a与周期方向b之间成30°夹角。其中周期方向a与y轴平行，沿周期方向a的两个第一栅格212之间的距离为Pa，周期方向b与y轴成30°夹角，沿周期方向b的两个第一栅格212之间的距离为Pb。Pa可以为0.4μm至3μm，Pb可以为0.2μm至2μm。Pa与Pb需满足关系式：Pa＝Pb/2cos(30°)。
本申请实施例第一栅格212采用的非对称形状还可以理解为第一栅格212为各个第一栅格212关于x轴与y轴均不对称的形状，第一栅格212的第一对角线ce总是比第二对角线df要长，且第一对角线ce与y轴正方向夹角θacy为钝角，与x轴正方向夹角θacx为锐角。
第一耦出光栅210具有多组栅格组211，每一组栅格组211包括多个第一栅格212，且每一组栅格组211中的各个第一栅格212与其相邻的第一栅格212相交，各组栅格组211相互间隔。本申请一种 可选实施例中，各组栅格组211相互平行。每一组栅格组211中的各个第一栅格沿第六方向排布。还可以理解为每个第一栅格212右上与左下均与斜方向上临近的下一个第一栅格212相交。
其中第六方向为第七方向沿顺时针方向旋转30度的方向，其中第七方向为第三耦出光栅230朝向耦入光栅240的方向。需要说明的是，第七方向也可以理解为Pa的正方向，即第六方向为Pb1的方向。
需要说明的是，第一栅格211的顶点个数并不限于四个，诸如第一栅格包括至少五个顶点，即第一栅格211可以具有5个及以上的顶点个数。本申请实施例以5个顶点为例进行说明。
请参阅图14，图14为本申请实施例提供的光学结构中第一耦出光栅的局部结构示意图。第一栅格212的顶点包括靠近第三耦出光栅230的两个顶点(顶点c和顶点d)以及远离第三耦出光栅230的两个顶点(顶点e和顶点f)，靠近第三耦出光栅230的两个顶点(顶点c和顶点d)以及远离第三耦出光栅230的两个顶点(顶点e和顶点f)能够形成第三对角线ce和第四对角线df，第三对角线ce的长度大于第四对角线df的长度，且第三对角线ce与第三耦出光栅230在第四方向的夹角为锐角，第四对角线df与第三耦出光栅230在第四方向的夹角为钝角。
其中第四方向为第三耦出光栅230朝向耦入光栅240的方向。即第四方向可以理解为第三方向。其中第三对角线ce和第四对角线df可以参阅图11至图13所示的第三对角线ce和第四对角线df，在此不再赘述。其中第一栅格212以及栅格组211均可参阅图11至图13所示的第一栅格212以及栅格组211，在此不再赘述。
需要说明的是，第一栅格211的顶点个数并不限于四个、五个以及多于五个，诸如第一栅格包括三个顶点，即第一栅格211可以具有三个顶点个数。
请参阅图15，图15为本申请实施例提供的光学结构中第一耦出光栅的局部结构示意图。第一栅格212的顶点包括靠近顶点c、顶点d和顶点e，顶点c、顶点d和顶点e相互连接形成第一顶点连接边cd、第二顶点连接边de和第三顶点连接边ce，第一顶点连接边cd靠近所述第三耦出光栅230，第二顶点连接边de远离第三耦出光栅230，第一顶点连接边cd的长度大于第二顶点连接边de的长度，且第一顶点连接边cd与第三耦出光栅230在第五方向的夹角为锐角，第二顶点连接边de与第三耦出光栅230在第五方向的夹角为钝角。
其中第五方向为第三耦出光栅230朝向耦入光栅240的方向。即第五方向可以理解为第三方向。其中第一顶点连接边cd和第二顶点连接边de可以参阅图11至图13所示的第三对角线ce和第四对角线df，在此不再赘述。其中第一栅格212以及栅格组211均可参阅图11至图13所示的第一栅格212以及栅格组211，在此不再赘述。
本申请实施例第一耦出光栅210和第二耦出光栅220的形状相同，且第一耦出光栅210和第二耦出光栅220相对于第三耦出光栅230对称设置，也可以理解为第一耦出光栅210、第二耦出光栅220相对于第三耦出光栅230镜像设置。即第二耦出光栅220中的多个栅格均是二维光栅，每一个二维光栅的 栅格结构的形状及排布均与第一栅格212相同。诸如第二耦出光栅220为具有多个第二栅格的二维光栅，第二耦出光栅220中的所有第二栅格与第一耦出光栅210中的所有第一栅格的形状相同、以及排布相同。具体形状及排布方式可以参阅图11至图15，在此不再赘述。
其中第三耦出光栅230为具有多个第三栅格的二维光栅，第三栅格为对称形状，诸如为左右对称形状的二维光栅，以至于其向左传播的光线与其向右传播的光线的效率相对，有利于加大边缘视场角的眼盒260的大小。第三栅格可以成六方晶格排布，光栅矢量可以参阅图9，其(1，1)级衍射矢量与y轴平行。第三栅格可以为沿y轴对称的任意形状，诸如圆形、正方向、菱形、六边形、八边形等。第三耦出光栅230的区域可以为矩形，比如在x轴方向的横向宽度可以为1mm至15mm，在y轴方向上的纵向宽度可以为20mm-35mm。
本申请一种可选实施方式中，第一耦出光栅210、第二耦出光栅220及第三耦出光栅230三者的光栅周期相等，第一耦出光栅210、第二耦出光栅220及第三耦出光栅230任一者与波导体250的折射率为1.5-3。耦入光栅240的光栅周期是第一耦出光栅210、第二耦出光栅220及第三耦出光栅230三者中任一者在与第一方向相互垂直方向光栅周期的二分之一。或者说耦入光栅240的光栅周期是第一耦出光栅210、第二耦出光栅220及第三耦出光栅230三者中任一者在y轴方向光栅周期的二分之一。
其中耦入光栅240、第一耦出光栅210、第二耦出光栅220及第三耦出光栅230的材料均可以是硅、塑料、玻璃、聚合物或上述材料的某种组合。
请继续参阅图2，Eyebox260内各位置处的显示亮度由该位置的耦出光线强度决定，所以光线2012、光线2013A、光线2014A的强度直接决定了Eyebox260的显示质量。而在实际应用中光线2012的强度大幅弱于光线2013A和光线2014A，进而导致Eyebox260中对应光线2012的位置呈现了明显的暗区，这会极大的影响消费者的使用体验。光线2012的强度弱于光线2013A和光线2014A的原因在于，第三耦出光栅230的耦出效率不可设置过大，否则主光线201在传播过程中会衰减过快，过快衰减的光线201会导致光线2012之间的光线强度差异，最终会造成更严重的Eyebox260的亮度不均匀。
基于此，本申请实施例提出一种光学结构以在提高第三耦出光栅230耦出光线效率的同时不带来光线2012之间的强度差异，诸如本申请实施例光学结构200将第三耦出光栅230沿y轴分为多块区域，不同的区域之间沿y轴效率逐渐提高，这样虽然主光线201在传播过程中会衰减，但可使2012甚至更加后续的耦出光线相应的耦出光栅的效率逐步提高，这样虽然主光线201因第三耦出光栅230效率的提高从而加速衰减，但光线2012甚至更加后续的耦出光线之间能量差异可得到减小，从而使得光线2012的能量更加接近光线2013A和光线2014A的同时光线2012之间的强度差异减小，最终使得Eyebox260的亮度与亮度均匀性同时得到提高，Eyebox260能量与亮度均匀性均得到了大幅改进。综上所述，本申请实施例引入将第三耦出光栅230分区为多块光栅的技术，解决了上述问题，使得Eyebox260能量与亮度均匀性均得到了大幅改进，这样本申请实施例就具有了较大的实施意义，是一种性能优良的衍射波导架构。
本申请实施例第三耦出光栅230包括至少两个子耦出光栅，相邻两个子耦出光栅的交界处位于光学结构200的眼盒260内，远离耦入光栅240的子耦出光栅的衍射效率大于靠近耦入光栅240的子耦出光栅的衍射效率。从而可以使得第三耦出光栅230所耦出光线的整体能量大致相同，或者理解为第三耦出光栅230的各个子耦出光栅所耦出光线的能量大致相同。且不会影响第三耦出光栅230所耦出光线的强度。下面结合图示进行详细说明。
本申请实施例一种可选实施方式中，远离耦入光栅240的子耦出光栅的光栅深度大于靠近耦入光栅240的子耦出光栅的光栅深度，从而可以实现远离耦入光栅240的子耦出光栅的衍射效率大于靠近耦入光栅240的子耦出光栅的衍射效率。即本申请一种可选实施方式界定出的光学结构200的光栅越深，其衍射效率越高。
请参阅16和图17，图16为本申请实施例提供的光学结构的示意图，图17为本申请实施例提供的光学结构的示意图。光学结构200的第三耦出光栅230可以包括三个子耦出光栅，每一个子耦出光栅的至少一部分位于眼盒260内。诸如第三耦出光栅230包括一部分位于眼盒260一侧的第一子耦出光栅231、一部分位于眼盒260另一侧的第二子耦出光栅232以及完全位于眼盒260内的第三子耦出光栅233。
第一子耦出光栅231沿所有子耦出光栅排布方向的长度大于位于眼盒260内第三子耦出光栅233沿所有子耦出光栅排布方向的长度。或者理解为第一子耦出光栅231沿y轴方向的长度大于位于眼盒260内第三子耦出光栅233沿y轴方向的长度。
第二子耦出光栅232沿所有子耦出光栅排布方向的长度大于位于眼盒260内第三子耦出光栅233沿所有子耦出光栅排布方向的长度。或者理解为第二子耦出光栅232沿y轴方向的长度大于位于眼盒260内第三子耦出光栅233沿y轴方向的长度。
本申请一种可选实施方式中，第二子耦出光栅232沿所有子耦出光栅排布方向的长度可以与第一子耦出光栅231沿所有子耦出光栅排布方向的长度。第一子耦出光栅231和第二子耦出光栅232可以相对于第三子耦出光栅233对称设置。需要说明的是，第一子耦出光栅231和第二子耦出光栅232沿所有子耦出光栅排布方向的长度也可以不相等。
本申请实施例第一子耦出光栅231沿所有子耦出光栅排布方向的长度以及第二子耦出光栅232沿所有子耦出光栅排布方向的长度均大于第三子耦出光栅233沿所有子耦出光栅排布方向的长度。本申请一种可选实施方式中，第一子耦出光栅231沿所有子耦出光栅排布方向的长度与所有子耦出光栅排布的长度比例为P1，即第一子耦出光栅231沿y轴方向的长度与第三耦出光栅230沿y轴方向的长度比例为P1。第三子耦出光栅233沿所有子耦出光栅排布方向的长度与所有子耦出光栅排布方向的长度比例为P2，即第三子耦出光栅233沿y轴方向的长度与第三耦出光栅230沿y轴方向的长度比例为P2。P1大于或等于30％、且P1小于或等于45％，P2大于或等于10％、且P2小于30％。
本申请一种可选实施方式中，第一子耦出光栅231位于眼盒260内的部分与第二子耦出光栅232位于眼盒260内的部分尺寸相同。结合图5和图6，第三耦出光栅230的子耦出光栅的交界位于第三耦 出光栅230中心上下B/2的范围之内。
本申请一种可选实施方式中，从最靠近耦入光栅240的一个子耦出光栅诸如第一子耦出光栅231至最远离耦入光栅240的一个子耦出光栅诸如第二子耦出光栅232的方向所有子耦出光栅的衍射效率等比例增加。也可以理解为沿y轴正方向所有子耦出光栅的衍射效率等比例增加。比如第三子耦出光栅233的衍射效率是第一子耦出光栅231的n倍，n大于1。第二子耦出光栅232的衍射效率是第三子耦出光栅233的n倍。从而可以保证各个子衍射光栅所耦出光线的能量相差不大。
需要说明的是，图16和图17所示出的第三耦出光栅230分为三个区域结构仅为示例性的，并不构成对第三耦出光栅230分区域个数的限制。比如第三耦出光栅230可以包括两个子耦出光栅、四个子耦出光栅、五个子耦出光栅等等。更多个数的子耦出光栅在此不再一一说明。
还需要说明的是，当第三耦出光栅230的子耦出光栅的个数大于三个诸如四个、五个时，仍然满足第三耦出光栅230的所有子耦出光栅中相邻两个子耦出光栅的交界处位于光学结构200的眼盒260内，远离耦入光栅240的子耦出光栅的衍射效率大于靠近耦入光栅240的子耦出光栅的衍射效率。同样可以使得第三耦出光栅230所耦出光线的整体能量大致相同，或者理解为第三耦出光栅230的各个子耦出光栅所耦出光线的能量大致相同。且不会影响第三耦出光栅230所耦出光线的强度。
当第三耦出光栅230的子耦出光栅的个数大于三个诸如四个、五个时。第三耦出光栅230的所有子光栅至少一部分可以位于眼盒260内。即第三耦出光栅230包括一部分位于眼盒260一侧的一个耦出光栅、一部分位于眼盒260另一侧的一个子耦出光栅以及完全位于眼盒260内的两个或两个以上的子耦出光栅。完全位于眼盒260内的所有子耦出光栅沿第三耦出光栅230的所有子耦出光栅排布方向的长度之和小于任一个一部分位于眼盒260外的子耦出光栅沿第三耦出光栅230的所有子耦出光栅排布方向的长度。也可以理解为完全位于眼盒260内的所有子耦出光栅沿y轴方向的长度之和小于任一个一部分位于眼盒260外的子耦出光栅沿y轴方向的长度。
与图16和图17相比，第三耦出光栅230完全位于眼盒260内的至少两个子耦出光栅沿y轴方向的长度之和与第三耦出光栅230沿y轴方向的长度比例为P2。其余特征可以参阅图16和图17，在此不再赘述。
请参阅图18，图18为本申请实施例提供的光学结构的示意图。图18示意出第三耦出光栅230包括四个子耦出光栅分别为第一子耦出光栅231、第二子耦出光栅232、第三子耦出光栅233和第四子耦出光栅234，其中第一子耦出光栅231和第二子耦出光栅232可以参阅以上内容在此不再赘述。第三子耦出光栅233和第四子耦出光栅均位于眼盒260内。
请参阅图19，图19为本申请实施例提供的光学结构的示意图。图19示意出第三耦出光栅230包括五个子耦出光栅分别为第一子耦出光栅231、第二子耦出光栅232、第三子耦出光栅233、第四子耦出光栅234和第五子耦出光栅235，其中第一子耦出光栅231和第二子耦出光栅232可以参阅以上内容在此不再赘述。第三子耦出光栅233、第四子耦出光栅和第五子耦出光栅均位于眼盒260内。
考虑到光线2012、光线2013A、光线2014A的强度直接决定了Eyebox260的显示质量，而在实际应用中光线2012的强度大幅弱于光线2013A和光线2014A。本申请一些实施例中将能够耦出光线2012的第三耦出光栅230分区域设置，能够使得光线2012的能量更加接近光线2013A和光线2014A的同时光线2012之间的强度差异减小，最终使得Eyebox260的亮度与亮度均匀性同时得到提高，Eyebox260能量与亮度均匀性均得到了大幅改进。实际应用中光线2013A和光线2014A随光线的传播其能量也会有所损失。为了能够使得Eyebox260的亮度与亮度均匀性均可以得到进一步提高。本申请一些可选实施方式中，将第一耦出光栅210以及第二耦出光栅220也分区域设置。下面结合图示进行详细说明。
请参阅图20，图20为本申请实施例提供的光学结构的示意图。图20所示光学结构200中的第一耦出光栅210、第二耦出光栅220及第三耦出光栅230均分区域设置。其中第三耦出光栅230的分区域设置可参阅图16至图19，在此不再赘述。
其中第一耦出光栅210包括至少两个子耦出光栅，第一耦出光栅210的子耦出光栅的个数与第三耦出光栅230的子耦出光栅的个数相同诸如都三个。且第一耦出光栅210中相邻两个子耦出光栅的交界处位于光学结构200的眼盒260内。第一耦出光栅210中远离耦入光栅240的子耦出光栅的衍射效率大于靠近耦入光栅240的子耦出光栅的衍射效率。从而可以使得第一耦出光栅210所耦出光线的整体能量大致相同，或者理解为第一耦出光栅210的各个子耦出光栅所耦出光线的能量大致相同。且不会影响第一耦出光栅210所耦出光线的强度。
图20所示第一耦出光栅210的子耦出光栅以三个为例进行说明。第一耦出光栅210包括第一子耦出光栅211、第二子耦出光栅212和第三子耦出光栅213。需要说明的是，第一子耦出光栅211可以参阅第一子耦出光栅231，第二子耦出光栅212可以参阅第三子耦出光栅233，第三子耦出光栅213可以参阅第二子耦出光栅232，在此不再赘述。需要说明的是，当第一耦出光栅210的分区域个数和第三耦出光栅230的分区域个数均大于三个时，可以参阅图18和图19，在第一子耦出光栅211和第三子耦出光栅213之间排布2个子耦出光栅、3个子耦出光栅或更多个子耦出光栅，且其排布方式与第三耦出光栅230的子耦出光栅的排布方式相同，在此不再赘述。
其中第二耦出光栅220包括至少两个子耦出光栅，第二耦出光栅220的子耦出光栅的个数与第三耦出光栅230的子耦出光栅的个数相同诸如都三个。且第二耦出光栅220中相邻两个子耦出光栅的交界处位于光学结构200的眼盒260内。第二耦出光栅220中远离耦入光栅240的子耦出光栅的衍射效率大于靠近耦入光栅240的子耦出光栅的衍射效率。从而可以使得第二耦出光栅220所耦出光线的整体能量大致相同，或者理解为第二耦出光栅220的各个子耦出光栅所耦出光线的能量大致相同。且不会影响第二耦出光栅220所耦出光线的强度。
图20所示第二耦出光栅220的子耦出光栅以三个为例进行说明。第二耦出光栅210包括第一子耦出光栅221、第二子耦出光栅222和第三子耦出光栅223。需要说明的是，第一子耦出光栅221可以 参阅第一子耦出光栅231，第二子耦出光栅222可以参阅第三子耦出光栅233，第三子耦出光栅223可以参阅第二子耦出光栅232，在此不再赘述。需要说明的是，当第二耦出光栅220的分区域个数和第三耦出光栅230的分区域个数均大于三个时，可以参阅图18和图19，在第一子耦出光栅221和第三子耦出光栅223之间排布2个子耦出光栅、3个子耦出光栅或更多个子耦出光栅，且其排布方式与第三耦出光栅230的子耦出光栅的排布方式相同，在此不再赘述。
可以理解的是，本申请其他一些实施方式中，仅将第一耦出光栅210、第二耦出光栅220和第三耦出光栅230的任一者采用分区域的方式设置也在本申请实施例所界定的范围内。以及仅将第一耦出光栅210、第二耦出光栅220和第三耦出光栅230中的其中两者采用分区域的方式设置也在本申请实施例所界定的范围内。
当第三耦出光栅230包括多个子耦出光栅时，第一耦出光栅210、第二耦出光栅220以及第三耦出光栅230均可以为二维光栅，诸如图1至图15所示内容，在此不再赘述。需要说明的是，当第三耦出光栅230包括多个子耦出光栅时，第一耦出光栅210和第二耦出光栅220也可以采用其它光栅结构诸如一维光栅。当第一耦出光栅210和第二耦出光栅220采用一维光栅时，第三耦出光栅230采用二维光栅，耦入光栅240采用一维光栅，第一耦出光栅210、第二耦出光栅220和耦入光栅240的光栅周期相等，且第三耦出光栅230在沿第三耦出光栅230所有子耦出光栅排布方向的光栅周期是第一耦出光栅210、第二耦出光栅220和耦入光栅240三者中任一者光栅周期的两倍。
请参阅图21，图21为本申请实施例提供的光学结构的示意图。图21所示光学结构300包括耦入光栅340、第一耦出光栅320、第二耦出光栅320、第三耦出光栅330以及波导体350。耦入光栅340、第一耦出光栅320、第二耦出光栅320、第三耦出光栅330均设置于波导体340，耦入光栅340、第一耦出光栅320、第二耦出光栅320、第三耦出光栅330任一者可以设置于波导体350的任一面，诸如耦入光栅340、第一耦出光栅320、第二耦出光栅320、第三耦出光栅330均设置于波导体350的第一面352。
其中波导体350可以参阅波导体250，在此不再赘述。其中耦入光栅340可以参阅耦入光栅240，在此不再赘述。
请参阅图22，图22为本申请实施例提供的光学结构的示意图。结合图21，本申请实施例所提供的光学结构300，经第三耦出光栅330传导的光线诸如边缘视场角光线，包括保持在第三耦出光栅330范围内、而不会传导至第一耦出光栅310或第二耦出光栅320的分量。
举例来说，耦入光栅340发射出来边缘视场角光线301，经过波导体350入射到第三耦出光栅330，并与第三耦出光栅330作用产生包括沿该光学301出射方向的光线第一分量304，该光线第一分量304保持在第三耦出光栅330范围内、而不会传导至第一耦出光栅310或第二耦出光栅320。
需要说明的是，边缘视场角光线301在于第三耦出光栅330作用时还会产生其他光线分量，诸如包括沿z轴方向传导的光线第二分量、沿x轴正方向传导的光线第三分量、沿x轴反方向传导的光线第四分量。该光线第一分量304在实际传导过程中，会多次与第三耦出光栅320产生作用而再形成多条光 线分量。
请继续参阅图21和图22，第三耦出光栅330可以包括第一侧边3301和第二侧边3302，第一侧边3301远离耦入光栅340，第二侧边3302靠近耦入光栅340，第一侧边3301和第二侧边3302相对设置。第一侧边3301沿第一耦出光栅320、第二耦出光栅320、第三耦出光栅330排布方向的长度大于第二侧边3302沿第一耦出光栅320、第二耦出光栅320、第三耦出光栅330排布方向的长度。以确保光线第一分量304能够保持在第三耦出光栅330的范围内。比如第一侧边3301的长度大于10毫米，第二侧边3302的长度大于4毫米。
举例来说，请参阅图23，图23为本申请实施例提供的光学结构的示意图。假设入射到耦入光栅340的光线301在x-z平面与z轴夹角为a，在y-z平面与z轴夹角为b，那么经过耦入光栅340耦入后的入射光线的光线第一分量304在x方向与y方向的光矢量分别为：
Figure PCTCN2022109685-appb-000001
Figure PCTCN2022109685-appb-000002
那么入射光线的光线第一分量304与y轴夹角为：
Figure PCTCN2022109685-appb-000003
那么第三耦出光栅330的第二侧边3302的长度B需满足如下关系：
B≥2C*tan(θ)+A
第三耦出光栅330的第一侧边3301的长度E需满足如下关系：
E≥2D*tan(θ)+A
从而本申请实施例可以保证入射光线的光线第一分量304能够保持在第三耦出光栅330的范围内。
本申请一种可选实施方式中，第三耦出光栅330的宽度从第一侧边3301至第二侧边3302逐渐减小。即第三耦出光栅330的宽度从第二侧边3302至第一侧边3301逐渐增加。其中第三耦出光栅330的宽度为第三耦出光栅330沿第一耦出光栅310、第三耦出光栅330及第二耦出光栅320排布方向的长度。诸如沿x轴方向的长度。诸如第三耦出光栅330整体呈等腰梯形结构。需要说明的是，本申请实施例第三耦出光栅330的形状并不限于，第三耦出光栅330只要满足第一侧边3301的长度大于第二侧边3302的长度，第三耦出光栅330的所有形状均在本申请实施例的保护范围内。
第三耦出光栅330还可以包括第三侧边3303和第四侧边3304。第三侧边3303和第四侧边3304相对设置，可以理解为第三侧边3303和第四侧边3304位于第三耦出光栅330的相对两侧，第一侧边3301和第二侧边3302位于第三耦出光栅330的相对两端。第三侧边3303与第一侧边3301和第二侧边3302连接，诸如第三侧边3303连接第一侧边3301的一端和第二侧边3302的一端。第四侧边3304与第一侧边3301和第二侧边3302连接，诸如第四侧边3304连接第一侧边3301的另一端和第二侧边3302 的另一端。
本申请一种可选实施方式中，第三侧边3303和第四侧边3304相对于第一侧边3301和第二侧边3302轴对称设置。
本申请一种可选实施方式中，第一侧边3301和第二侧边3302的间距可以是20毫米至35毫米。
本申请一种可选实施方式中，第三耦出光栅330为正方格子结构的二维光栅。可以使得第一耦出光栅310、第二耦出光栅320以及第三耦出光栅330靠近耦入光栅340的一侧边缘无扩瞳区域，诸如第一耦出光栅310、第二耦出光栅320以及第三耦出光栅330靠近耦入光栅340的一侧边缘齐平，在其接收到光线耦入时会产生作用。从而相比需要布置扩瞳区域的光学结构来讲，会节省无效光栅区域(即扩瞳区域)，进而可以使得光学结构300的整体有效耦出光栅面积增加，对光栅区域的利用率更高，提高衍射波导的整体效率。
需要说明的是，第三耦出光栅330也可以为六方格子结构的二维光栅。
请继续参阅图21至图23，第一耦出光栅310和第二耦出光栅320均为一维光栅。本申请一些可选实施方式中，第一耦出光栅310和第二耦出光栅320相对于第三耦出光栅330轴承对称设置。
本申请实施例第三耦出光栅330包括至少两个子耦出光栅，相邻两个子耦出光栅的交界处位于光学结构300的眼盒内，远离耦入光栅340的子耦出光栅的衍射效率大于靠近耦入光栅340的子耦出光栅的衍射效率。从而可以使得第三耦出光栅330所耦出光线的整体能量大致相同，或者理解为第三耦出光栅330的各个子耦出光栅所耦出光线的能量大致相同。且不会影响第三耦出光栅330所耦出光线的强度。下面结合图示进行详细说明。
本申请实施例一种可选实施方式中，远离耦入光栅340的子耦出光栅的光栅深度大于靠近耦入光栅340的子耦出光栅的光栅深度，从而可以实现远离耦入光栅340的子耦出光栅的衍射效率大于靠近耦入光栅340的子耦出光栅的衍射效率。即本申请一种可选实施方式界定出的光学结构300的光栅越深，其衍射效率越高。
请参阅图24，图24为本申请实施例提供的光学结构的示意图。图24示意出第三耦出光栅330包括三个子耦出光栅分别为第一子耦出光栅331、第二子耦出光栅332、第三子耦出光栅333。每一个子耦出光栅的至少一部分位于眼盒260内。诸如第三耦出光栅330包括一部分位于眼盒一侧的第一子耦出光栅231、一部分位于眼盒另一侧的第二子耦出光栅332以及完全位于眼盒内的第三子耦出光栅333。
其中，第一子耦出光栅331、第二子耦出光栅332、第三子耦出光栅333三者的关系可以参阅第一子耦出光栅231、第二子耦出光栅232、第三子耦出光栅233，在此不再赘述。
本申请一种可选实施方式中，从最靠近耦入光栅340的一个子耦出光栅诸如第一子耦出光栅331至最远离耦入光栅340的一个子耦出光栅诸如第二子耦出光栅332的方向所有子耦出光栅的衍射效率等比例增加。也可以理解为沿y轴正方向所有子耦出光栅的衍射效率等比例增加。比如第三子耦出光栅333的衍射效率是第一子耦出光栅331的n倍，n大于1。第二子耦出光栅332的衍射效率是第三子耦 出光栅333的n倍。从而可以保证各个子衍射光栅所耦出光线的能量相差不大。
需要说明的是，图24所示出的第三耦出光栅330分为三个区域结构仅为示例性的，并不构成对第三耦出光栅330分区域个数的限制。比如第三耦出光栅330可以包括两个子耦出光栅、四个子耦出光栅、五个子耦出光栅等等。更多个数的子耦出光栅在此不再一一说明。
还需要说明的是，当第三耦出光栅330的子耦出光栅的个数大于三个诸如四个、五个时，仍然满足第三耦出光栅330的所有子耦出光栅中相邻两个子耦出光栅的交界处位于光学结构300的眼盒内，远离耦入光栅340的子耦出光栅的衍射效率大于靠近耦入光栅340的子耦出光栅的衍射效率。同样可以使得第三耦出光栅330所耦出光线的整体能量大致相同，或者理解为第三耦出光栅330的各个子耦出光栅所耦出光线的能量大致相同。且不会影响第三耦出光栅330所耦出光线的强度。
当第三耦出光栅330的子耦出光栅的个数大于三个诸如四个、五个时。第三耦出光栅330的所有子光栅至少一部分可以位于眼盒内。即第三耦出光栅330包括一部分位于眼盒一侧的一个耦出光栅、一部分位于眼盒另一侧的一个子耦出光栅以及完全位于眼盒内的两个或两个以上的子耦出光栅。完全位于眼盒内的所有子耦出光栅沿第三耦出光栅330的所有子耦出光栅排布方向的长度之和小于任一个一部分位于眼盒外的子耦出光栅沿第三耦出光栅330的所有子耦出光栅排布方向的长度。也可以理解为完全位于眼盒内的所有子耦出光栅沿y轴方向的长度之和小于任一个一部分位于眼盒外的子耦出光栅沿y轴方向的长度。具体可以参阅以上内容诸如图18和图19，在此不再赘述。
本申请以上各实施例界定的光学结构200及光学结构300均可以应用于光学装置中，该光学装置可以包括投影光器和以上任一种光学结构诸如光学结构任一种光学结构200或者任一种光学结构300。该光学装置可以为增强现实装置，也可以为虚拟现实装置。
以上对本申请实施例所提供的光学结构和光学装置进行了详细介绍，本文中应用了具体个例对本申请的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本申请的方法及其核心思想；同时，对于本领域的技术人员，依据本申请的思想，在具体实施方式及应用范围上均会有改变之处，综上所述，本说明书内容不应理解为对本申请的限制。

Claims (20)

  1. 一种光学结构，其中，光学结构包括：
    波导体；
    耦入光栅，设置于所述波导体；
    第一耦出光栅，设置于所述波导体；
    第二耦出光栅，设置于所述波导体；和
    第三耦出光栅，设置于所述波导体，所述第三耦出光栅位于所述第一耦出光栅和第二耦出光栅之间，且所述耦入光栅位于第一耦出光栅、第二耦出光栅及第三耦出光栅同一侧；
    由所述耦入光栅发射出来的光线经所述波导体入射到所述第三耦出光栅，并与所述第三耦出光栅作用产生包括沿所述光线出射方向的光线第一分量，所述光线第一分量保持在所述第三耦出光栅范围内、而不会传导至所述第一耦出光栅或所述第二耦出光栅。
  2. 根据权利要求1所述的光学结构，其中，所述第三耦出光栅包括远离所述耦入光栅的第一侧边与所述第一侧边相对设置的第二侧边，所述第一侧边沿所述第一耦出光栅、第三耦出光栅及第二耦出光栅排布方向的长度大于所述第二侧边沿所述第一耦出光栅、第三耦出光栅及第二耦出光栅排布方向的长度。
  3. 根据权利要求2所述的光学结构，其中，所述第一侧边和所述第二侧边的间距在20毫米至35毫米之间。
  4. 根据权利要求2所述的光学结构，其中，所述第三耦出光栅的宽度从所述第一侧边至所述第二侧边逐渐减小，其中所述第三耦出光栅的宽度为所述第三耦出光栅沿所述第一耦出光栅、第三耦出光栅及第二耦出光栅排布方向的长度。
  5. 根据权利要求4所述的光学结构，其中，所述第三耦出光栅还包括第三侧边与所述第三侧边相对设置的第四侧边，所述第三侧边连接所述第一侧边的一端和所述第二侧边的一端，所述第四侧边连接所述第一侧边的另一端和所述第二侧边的另一端，所述第三侧边和第四侧边相对于所述第一侧边及所述第二侧边轴对称设置。
  6. 根据权利要求4所述的光学结构，其中，所述第一耦出光栅和所述第二耦出光栅相对于所述第三耦出光栅轴对称设置。
  7. 根据权利要求1至6任一项所述的光学结构，其中，所述第三耦出光栅为二维光栅。
  8. 根据权利要求7所述的光学结构，其中，所述第三耦出光栅为正方格子结构的二维光栅。
  9. 根据权利要求7所述的光学结构，其中，所述第三耦出光栅为六方格子结构的二维光栅。
  10. 根据权利要求7所述的光学结构，其中，所述第一耦出光栅和第二耦出光栅均为一维光栅。
  11. 根据权利要求1至6任一项所述的光学结构，其中，所述第三耦出光栅包括至少两个子耦出光 栅，相邻两个子耦出光栅的交界处位于所述光学结构的眼盒内，远离所述耦入光栅的子耦出光栅的衍射效率大于靠近所述耦入光栅的子耦出光栅的衍射效率。
  12. 根据权利要求11所述的光学结构，其中，远离所述耦入光栅的子耦出光栅的光栅深度大于靠近所述耦入光栅的子耦出光栅的光栅深度。
  13. 根据权利要求11所述的光学结构，其中，当所述第一耦出光栅和所述第二耦出光栅采用一维光栅时，所述第三耦出光栅采用二维光栅，所述耦入光栅采用一维光栅，所述第一耦出光栅、所述第二耦出光栅和所述耦入光栅的光栅周期相等，且所述第三耦出光栅在沿所述第三耦出光栅所有子耦出光栅排布方向的光栅周期是所述第一耦出光栅、所述第二耦出光栅和所述耦入光栅三者中任一者光栅周期的两倍。
  14. 根据权利要求11所述的光学结构，其中，所述第三耦出光栅包括至少三个子耦出光栅，所述至少三个子耦出光栅包括一部分位于所述眼盒一侧的第一子耦出光栅、一部分位于所述眼盒另一侧的第二子耦出光栅以及完全位于所述眼盒内的至少一个子耦出光栅；
    所述第一子耦出光栅的沿所有子耦出光栅排布方向的长度大于位于所述眼盒内的至少一个子耦出光栅沿所有子耦出光栅排布方向的长度之和。
  15. 根据权利要求14所述的光学结构，其中，所述第二子耦出光栅的沿所有子耦出光栅排布方向的长度大于位于所述眼盒内的至少一个子耦出光栅沿所有子耦出光栅排布方向的长度之和。
  16. 根据权利要求14所述的光学结构，其中，完全位于所述眼盒内的子耦出光栅为一个、两个或三个中的任一者，从最靠近所述耦入光栅的一个子耦出光栅至最远离所述耦入光栅的一个子耦出光栅的方向所有子耦出光栅的衍射效率等比例增加。
  17. 根据权利要求14所述的光学结构，其中，所述第一子耦出光栅和所述第二子耦出光栅相对于完全位于所述眼盒内的子耦出光栅对称设置。
  18. 根据权利要求17所述的光学结构，其中，所述第一子耦出光栅位于所述眼盒内的部分与所述第二子耦出光栅位于所述眼盒内的部分尺寸相同。
  19. 根据权利要求1所述的光学结构，其中，所述波导体包括相对设置的第一面和第二面，所述耦入光栅、第一耦出光栅、第二耦出光栅和第三耦出光栅中的任一者可以设置于所述第一面和第二面的任一面。
  20. 一种光学装置，其中，光学装置包括：
    投影光器，所述投影光器被配置为提供增强现实或虚拟现实图像；和
    如权利要求1-19任一项所述的光学结构。
PCT/CN2022/109685 2021-09-16 2022-08-02 光学结构和光学装置 WO2023040491A1 (zh)

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