WO2023246581A1 - 衍射光波导 - Google Patents

衍射光波导 Download PDF

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Publication number
WO2023246581A1
WO2023246581A1 PCT/CN2023/100161 CN2023100161W WO2023246581A1 WO 2023246581 A1 WO2023246581 A1 WO 2023246581A1 CN 2023100161 W CN2023100161 W CN 2023100161W WO 2023246581 A1 WO2023246581 A1 WO 2023246581A1
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WIPO (PCT)
Prior art keywords
grating
area
region
filled
filling
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PCT/CN2023/100161
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English (en)
French (fr)
Inventor
黄河
张雅琴
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上海鲲游科技有限公司
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Publication of WO2023246581A1 publication Critical patent/WO2023246581A1/zh

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    • 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
    • G02B27/017—Head mounted
    • G02B27/0172—Head mounted characterised by optical features
    • 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
    • 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
    • G02B27/017—Head mounted
    • G02B2027/0178—Eyeglass type

Definitions

  • Embodiments of the present application relate to the field of display technology, for example, to a diffractive optical waveguide.
  • Augmented reality as a technology that "seamlessly" integrates virtual world information and real world information, superimposes virtual content and the real environment provided through a micro-projection system onto the same picture or space to exist simultaneously, allowing users to obtain both virtual and real world information.
  • Reality fusion experience as a technology that "seamlessly" integrates virtual world information and real world information, superimposes virtual content and the real environment provided through a micro-projection system onto the same picture or space to exist simultaneously, allowing users to obtain both virtual and real world information.
  • Figure 1 is a common grating layout of a diffraction optical waveguide in the related art. After the image beam S emitted from the image source is coupled into the optical waveguide substrate 12 through the coupling grating 11, it expands in one dimension through the turning grating 13 and turns to the coupling. The outgoing grating 14 is expanded again in another dimension by the outcoupling grating 14 and coupled out into the human eye.
  • this grating layout forms a single light transmission channel, which limits the angle of the outcoupled beam to the total internal reflection requirement of the waveguide glass sheet in one propagation direction, making it impossible to obtain a larger field of view.
  • Embodiments of the present application provide a diffraction optical waveguide and a preparation method thereof.
  • the image beam can obtain beams in multiple directions after being coupled in, forming multiple beams in the waveguide substrate. or, after the image beam is coupled into the optical waveguide, it forms a propagation beam propagating along multiple paths through diffraction. Different paths can carry image information of different field angles, and finally converge to the second grating area.
  • the output can increase the field of view of the diffractive optical waveguide, and can also improve the uniform distribution of the propagating light beams in multiple paths, effectively improving the visual imaging effect of the diffractive optical waveguide.
  • Embodiments of the present application provide a diffractive optical waveguide, including a waveguide substrate and a first grating region and a second grating region located on the surface of the waveguide substrate; the grating structure in the first grating region is configured to be at least one of the following : Coupling the image beam emitted from the image source into the waveguide base to form a propagation beam that propagates in different directions; diffracting the image beam coupled into the waveguide substrate to form a propagation beam that propagates in different directions; within the second grating area A grating structure configured to diffract the propagating beam to form an output beam.
  • Embodiments of the present application also provide a method for preparing a diffractive optical waveguide, which includes: providing a waveguide substrate; forming a first grating structure in the first grating area of the waveguide substrate, and forming a second grating structure in the second grating area;
  • the first grating structure is configured to at least one of the following: couple the image beam emitted from the image source into the waveguide substrate to form a propagation beam that propagates in different directions; diffract the image beam coupled into the waveguide substrate to form a propagation beam along the waveguide substrate. Propagation beams propagating in different directions; the second grating structure is configured to diffract the propagation beams to form an output beam.
  • Figure 1 is a schematic structural diagram of a diffractive optical waveguide in the related art
  • Figure 2 is a schematic plan view of a diffractive optical waveguide provided by an embodiment of the present application.
  • Figure 3 is a schematic plan view of another diffractive optical waveguide provided by an embodiment of the present application.
  • Figure 4 is a schematic plan view of another diffractive optical waveguide provided by an embodiment of the present application.
  • Figure 5 is a longitudinal cross-sectional view of a filled grating structure provided by an embodiment of the present application.
  • Figure 6 is a longitudinal cross-sectional view of another filled grating structure provided by an embodiment of the present application.
  • Figure 7 is a schematic diagram of the relationship between the diffraction efficiency and the field of view angle of the filled grating structure provided by the embodiment of the present application under the incident light of different wavelengths;
  • Figure 8 is a longitudinal cross-sectional view of another filled grating structure provided by an embodiment of the present application.
  • Figure 9 is a longitudinal cross-sectional view of another filled grating structure provided by an embodiment of the present application.
  • Figure 10 is a schematic diagram of the relationship between the diffraction efficiency and the field of view angle of the filled grating structure provided by this application for the embodiment of this application;
  • Figure 11 is a left side view of a diffractive optical waveguide provided by the embodiment of Figure 2;
  • Figure 12 is a left view of another diffractive optical waveguide provided by the embodiment of Figure 2;
  • Figure 13 is a left view of another diffractive optical waveguide provided by the embodiment of Figure 2;
  • Figure 14 is the (K space) wave vector space diagram of the image beam in Figure 2;
  • Figure 15 is a left view of a diffractive optical waveguide provided by the embodiment of Figure 3;
  • Figure 16 is a left view of another diffractive optical waveguide provided by the embodiment of Figure 3;
  • Figure 17 is a modification of the diffractive optical waveguide provided by the embodiment of Figure 3;
  • Figure 18 is a left view of another diffraction optical waveguide provided by the embodiment of Figure 3;
  • Figure 19 is the (K space) wave vector space diagram of the image beam in Figure 3;
  • Figure 20 is a schematic diagram of zoned modulation of the refractive index of a filling layer provided by an embodiment of the present application.
  • Figure 21 is a schematic diagram of a tooth-shaped structure of a grating substrate provided by an embodiment of the present application.
  • Figure 22 is a schematic diagram of the preparation process of a grating substrate filled with a grating structure provided by an embodiment of the present application;
  • Figure 23 is a schematic diagram of the preparation process of the filling layer of the filling grating structure provided by the embodiment of the present application.
  • Figure 24 is a schematic diagram of the preparation process of the multi-layer filled grating layer provided by the embodiment of the present application.
  • Embodiments of the present application provide a diffraction optical waveguide, including a waveguide substrate and a first grating region and a second grating region located on the surface of the waveguide substrate; the grating structure in the first grating region is configured to couple the image beam emitted from the image source into The waveguide substrate forms propagation beams that propagate in different directions; and/or, the image beam configured to diffractionally couple into the waveguide substrate forms propagation beams that propagate in different directions; the grating structure in the second grating region is configured to diffract the propagation beam to form an output beam.
  • the waveguide substrate provided by the present application includes a first grating region and a second grating region, wherein the first grating region includes a coupling grating region, and the second grating region includes a coupling out grating region.
  • the first grating area further includes an extended grating area.
  • the image source projects toward the coupling grating area.
  • the grating structure of the coupling grating area couples the image beam projected by the image source into the waveguide base to form a propagation beam.
  • the propagation beam propagates to the outcoupling grating area by total reflection in the waveguide base.
  • the propagating light beam propagates to the extended grating region and then to the outcoupling grating region by total reflection within the waveguide substrate.
  • the first grating area and/or the second grating area are disposed on at least one of the surfaces where the propagation beam is propagated by total reflection, and the grating structure of the first grating area is designed so that the first grating area is coupled into the grating area.
  • the grating structure can couple the image beam emitted from the image source into the waveguide substrate to form a propagation beam propagating in different directions; and/or, the grating structure of the extended grating region in the first grating region can diffract the image beam coupled into the waveguide substrate to form an edge.
  • Propagation beams propagating in different directions carry image information of different field of view ranges through propagation beams propagating in different directions.
  • the field of view (Field of View, FOV) can be spliced and expanded in the K domain. , to achieve the function of increasing the field of view. Taking RI1.9 as an example, FOV of 70 degrees or even larger can be achieved through field of view stitching.
  • FIG. 2 is a schematic planar structure diagram of a diffractive optical waveguide provided by an embodiment of the present application;
  • the diffractive optical waveguide includes a waveguide substrate 400 and a first grating area 1 and a second grating area 2 located on the surface of the waveguide substrate 400;
  • the grating structure 100 in a grating area 1 is configured to couple the image beam emitted from the image source into the waveguide substrate 400 to form a propagation beam S1 that propagates in three different directions.
  • FIG. 3 is a schematic plan view of another diffractive optical waveguide provided by an embodiment of the present application
  • FIG. 4 shows three deformations of the diffractive optical waveguide shown in FIG. 3
  • the diffraction optical waveguide provided by the embodiment of the present application includes a waveguide substrate 400 and a first grating area 1 and a second grating area 2 located on the surface of the waveguide substrate 400; a grating structure in the first grating area 1 (21, 22, 23)
  • the image beam is configured to be diffractively coupled into the waveguide substrate 400 to form a propagating beam propagating in different directions.
  • the diffractive optical waveguide includes a waveguide substrate 400.
  • the material of the waveguide substrate 400 can be optical glass or resin, and the thickness is between 0.5mm and 3mm.
  • the length of the waveguide substrate 400 can be determined according to the actual situation. The scene needs to be set.
  • the waveguide substrate 400 has a first surface M1 and a second surface M2 that are parallel to each other (not shown in the figure).
  • a first surface M1 and/or a second surface M2 of the waveguide substrate 400 may be provided.
  • Figures 2 to 4 only show that the first grating area 1 and the second grating area 2 are provided on the first surface M1 of the waveguide substrate 400.
  • the grating structure in area 2 may be a one-dimensional grating and/or a two-dimensional grating.
  • the sum of the grating vectors of the diffraction gratings through which the image beam is coupled from the first grating region 1 into the waveguide substrate 400 to the time when it is coupled out of the waveguide substrate 400 from the second grating region 2 is basically zero, ensuring that the image beam coupled into the waveguide substrate can be substantially zero. Dispersively coupled out of the waveguide substrate 400 into the user's eyes.
  • Embodiments of the present application also provide a filled grating structure.
  • the filled grating structure includes at least one filled grating layer.
  • the filled grating layer includes a grating base and a filling layer.
  • the filling layer is configured to fill the gap between the grating bases and fill the grating structure.
  • the side away from the waveguide substrate forms a flat and smooth surface; the refractive index of the grating substrate and the filling layer are different. Since the filling layer forms a flat and smooth surface after filling the grating substrate, the filling grating layer can be continuously stacked on it to form a grating structure of multiple stacked filling grating layers.
  • the layer height of the filling layer is greater than or equal to the grating depth of the grating base, the base structure of the grating base is aligned between adjacent filling grating layers, and the depth of the grating is selectively set based on the different layer heights of the filling layer to improve specific viewing. Diffraction efficiency at field angle.
  • the layer height of the filling layer is equal to the grating depth of the grating substrate.
  • the base structures in the grating substrates between adjacent filled grating layers are connected end to end to form a continuous grating structure. There is no filling layer at the end-to-end connections of multiple grating substrates. Control the tilt angle of multiple grating units in each filled grating layer to regulate diffraction efficiency and uniformity.
  • the multi-layer grating substrate forms multiple independent grating structural units. Adjacent grating structural units do not include residual layers, thereby forming independent units.
  • This structure can prevent the existence of residual layers from affecting diffraction efficiency and uniformity; at the same time, it can A layer of material is deposited or sputtered on each filled grating layer.
  • the material can be organic materials or transparent inorganic materials to improve the uniformity and diffraction efficiency of the entire grating layer. Of course, part or all of the grating layers can be selected to undergo the same process. Processing is not limited here.
  • FIG. 5 is a longitudinal cross-sectional view of a filled grating structure provided by an embodiment of the present application.
  • the filled grating structure includes a filled grating layer.
  • the filled grating layer includes a grating base 511 and a filling layer 512.
  • the grating base 511 is a conventional surface relief grating, and the filling layer is configured to fill the gaps between the grating bases and in the
  • the side of the filled grating structure 50 away from the waveguide substrate 400 forms a flat and smooth surface, and the refractive index n2 of the filled layer may be higher or lower than the refractive index n1 of the grating substrate.
  • FIG. 7 shows the relationship between diffraction efficiency and incident angle of a filled grating structure at different incident wavelengths in one embodiment.
  • the incident light wavelengths are 465nm, 525nm, and 625nm respectively.
  • the structure of the grating substrate is a trapezoid.
  • the left inclination angle of the trapezoid is 66°
  • the right inclination angle of the trapezoid is 113°
  • the grating period is 420nm
  • the grating depth is 597nm
  • the grating substrate has a
  • the material is TiO 2 (refractive index 2.30)
  • the filling layer material is epoxy resin (refractive index 1.48).
  • Figure 8 is a longitudinal cross-sectional view of another filled grating structure provided by an embodiment of the present application; the filled grating structure includes two filled grating layers;
  • Figure 9 is another filled grating structure provided by an embodiment of the present application.
  • the vertical cross-sectional view shows that the filled grating structure includes three filled grating layers.
  • the filling grating structure 50 may also include more filling grating layers.
  • the parameters of the grating substrates filled with different grating layers can be different. As shown in Figure 8, the grating tooth shapes of the grating substrates filled with two grating layers are different.
  • the cross-sections of the teeth can be rectangular, rhombus, triangular, etc.; multiple A filling layer is formed between the grating layers; the grating substrate is formed of multiple independent grating structural units, and the multiple grating structural units are connected without a residual layer of grating material to form independent units.
  • the grating tooth shapes of the grating bases of the three filled grating layers are the same and connected end to end to form a continuous grating structure. There is no filling layer at the end to end connections and they are directly connected. However, the inclination angle of each filled grating layer is different. By controlling The tilt angle of each grating structure achieves light field modulation.
  • the refractive index of the filling layers of different layer-filled grating layers can be the same or different, selected according to the modulation efficiency or uniformity.
  • the grating tooth shape of each layer is the same, but of course it can be different.
  • the multi-layer grating tooth shape is selected to be defined based on different modulation requirements.
  • a material layer can be provided on each filled grating layer.
  • the material can be organic materials or transparent inorganic materials to improve the uniformity and diffraction efficiency of the entire grating layer.
  • the filled grating structure provided in this application is formed by covering a filling layer on a grating substrate.
  • the grating substrate and the filling layer are the interface, and the refractive index of the filling layer is adjustable. Parameters can be used to reduce the refractive index difference between the grating base and the filling layer and increase the depth of the grating base to increase the number of interactions between light and the filling grating structure, thereby greatly improving the diffraction efficiency of the filling grating structure.
  • the filled grating structure provided in this application produces high diffraction efficiency in a manner similar to that of a volume grating, and the diffraction efficiency far exceeds that of conventional surface relief gratings.
  • the filled grating structure provided by this application can be similar to a conventional surface relief grating by optimizing the grating-related parameters such as inclination, depth, shape, and duty cycle to create a structure different from the volume with a large refractive index difference.
  • the narrow-band FOV of the grating avoids the problems of inflexible modulation and small diffraction angle range of volume gratings.
  • the filled grating structure provided in this application is not in direct contact with the air.
  • the filled grating structure provided by this application has the advantages of high diffraction efficiency and wide angular response bandwidth.
  • the filling grating layer can be continuously superimposed on it to form a multi-layer structure, which greatly improves the degree of design freedom, and different tilt angles or shapes can enhance certain aspects.
  • the efficiency of the specific field of view of each color beam is to meet the design functions of each grating functional area (such as coupling area, expansion area, outcoupling area, etc.) of the diffractive optical waveguide, and this is the current conventional single-layer (air Gap type) functions that surface relief gratings cannot achieve.
  • a material layer can also be formed on each filled grating layer (both light-transmitting organic materials and inorganic materials can be used) to improve the uniformity and diffraction efficiency of the entire grating layer.
  • the 0th order diffraction is the transmitted beam, and the energy of the beam that is not diffracted is directly transmitted and wasted.
  • Most of the current surface relief gratings use tilted gratings to improve the diffraction efficiency on one side, but the beam propagates in a single direction. In order to output the uniformity of the beam at all angles across the full width of the image, a better effect is that the beam can propagate to the coupling grating from multiple angles to obtain higher efficiency and more uniform image output.
  • the superposition of multiple layers of filled gratings can give full play to its advantages: the filled grating layer located below can reuse the 0th-order diffracted beam transmitted by the upper layer (that is, the energy that was originally wasted), and the filled grating layers of different layers can also Using different grating directions, it is flexibly designed to transmit the beam in different directions to subsequent grating areas.
  • the superposition of multi-layer filled grating layers can also be used for color balance. Through the multi-layer filled grating layers, all three color wavelengths are coupled into the waveguide substrate, which not only improves energy efficiency, but also improves the brightness uniformity of the image (guiding the beam to Illuminating dark corner areas), greatly improving design flexibility and image quality.
  • the uniformity mentioned in this application includes that the full image and uniform brightness can be seen when viewing the output image at various viewing angles in the movable eye socket; and in the scene of color beam projection, in the movable eye socket, When viewing the output image at various viewing angles, the full image and uniform brightness can be seen for each color image.
  • the diffraction efficiency of the filled grating structure is a curve with the field angle as a variable, and multiple field angles have corresponding diffraction efficiency.
  • the unused part is transmitted to the lower filled grating structure.
  • the lower filled grating structure can continue to utilize the light beam, which can further improve the diffraction efficiency.
  • Figure 10 is a graph showing the relationship between the diffraction efficiency and the incident angle of a filled grating structure provided by an embodiment of the present application. An example is given below. As shown in FIG. 8 , the incident light wavelength of the image beam emitted from the image source is 532nm.
  • the filled grating structure is two filled grating layers. The grating periods are both 360nm.
  • the first layer is coupled into the filled grating layer 101
  • the base structure of the grating base is triangular teeth
  • the material of the grating base is acrylic resin with a refractive index of 1.9
  • the material of the filling layer is epoxy resin with a refractive index of 1.5
  • the triangle hypotenuse angle is 50.6°
  • the grating depth is 4.4 ⁇ m
  • the base structure of the grating base of the second layer coupled to the filled grating layer 102 is a trapezoid.
  • the material of the grating base is TiO 2
  • the filling material of the filling layer is SiO 2 .
  • the trapezoid has a left inclination angle of 62°, a right inclination angle of 125°, and a grating depth of 364 nm. .
  • a diffraction efficiency of 63 to 87% can be obtained in a large field of view range of -23° to 10°.
  • the filled grating structure provided by this application has many types of adjustable parameters, great flexibility, and high degree of freedom. By modulating these parameters, the efficiency and uniformity of different field angles of light beams of different colors at different positions can be adjusted to meet the needs of Multiple grating functional areas (such as coupling in, expansion, coupling out, etc.) of the diffractive optical waveguide are designed to function, which is a function that cannot be achieved by a single-layer surface relief grating (air gap type).
  • the grating substrate of the filled grating structure 50 is not in direct contact with the air.
  • the filling layer plays a role in protecting the grating substrate. No additional protective sheet is needed to protect the grating substrate. In this way, when the diffractive optical waveguide including the filled grating structure is used in wearable devices , reducing the weight, allowing the waveguide plate including the filled grating structure to be used directly as a single piece. Wearable devices using the filled grating structure provided by this application have the advantages of high diffraction efficiency and wide angular response bandwidth, and meet the market requirements for wearable products that are lightweight and easy to wear.
  • the grating structure of the first grating area and/or the grating structure of the second grating area can be a conventional surface relief grating, or the filled grating provided by the present application can be used. structure, and the grating structure can be a one-dimensional structure or a two-dimensional structure.
  • the grating layout method of applying the filled grating structure to the diffractive optical waveguide shown in Figure 2 is described below.
  • Figure 11 is a left side view of a diffraction optical waveguide provided by the embodiment of Figure 2.
  • the first grating area includes a coupling grating area 100 and an extended grating area 200 .
  • the grating structure of the coupling grating area 100 is a filled grating structure 50 .
  • the filled grating structure 50 It includes at least two stacked coupling filling grating layers; the two coupling filling grating layers are configured to couple the image beam emitted by the image source into the waveguide substrate 400 and form a transmission beam propagating in different directions; and the grating structure is configured to extend the grating area.
  • the coupling-in fill grating layer may be a one-dimensional optical structure.
  • the grating structure of the coupling grating area is a filled grating structure 50.
  • the filled grating structure 50 includes a coupling filling grating layer, and the coupling filling grating layer is a two-dimensional grating structure.
  • the transmission beams propagating in different directions can carry image information of different field angle ranges respectively. The union of these different field angle ranges is the full field of view range, and the multiple propagation beams finally converge to the second grating area for coupling out.
  • the image beams in the entire field of view range can be effectively coupled out.
  • the diffraction optical waveguide can not only expand the field of view angle through field of view splicing, but also ensure that the image beam of the full field of view is effectively coupled out without any field of view loss.
  • FIG. 11 shows that the grating structure of the coupling grating region 100 is formed by stacking the coupling filling grating layer 101 and the coupling filling grating layer 102 (in other implementations, the grating structure of the coupling grating region 100 may include more layers. of coupling fill grating layer).
  • the coupling-filled grating layer 101 couples part of the image beam into the optical waveguide and propagates along the first direction, coupling into the 0th-order diffracted light generated by the diffraction of the filling grating layer 101 Transmitted into the next layer of coupling-filled grating layer (coupling-filled grating layer 102), the image beam can be diffracted and coupled into the optical waveguide again and propagated along the second direction. This not only improves the efficiency of light energy utilization, but also generates separation along the optical waveguide.
  • the light beam propagates in at least two directions and propagates to the subsequent grating area, which is beneficial to coupling out the full width of the image and modulating the brightness uniformity.
  • the grating structure of the coupling grating region 100 includes more coupling filling grating layers, the light energy utilization efficiency can be further improved, and the flexibility of modulation of brightness uniformity is also higher.
  • FIG. 12 is a left view of another diffractive optical waveguide provided by the embodiment of FIG. 2;
  • FIG. 13 is a left view of another diffractive optical waveguide provided by the embodiment of FIG. 2.
  • the filled grating structure 50 of the grating structure of the coupling grating region includes a three-layer stacked one-dimensional coupling filled grating.
  • the image beam is coupled into the waveguide substrate 400 and forms propagation beams that propagate along the first direction (D1), the second direction (D2) and the third direction (D3) respectively; the third direction is from the first grating area 1 to the second grating.
  • the direction of area 2 (the third direction is the negative direction of the Y-axis in Figure 2), the propagating light beam S1 along the third direction is directly transmitted to the second grating area 2, the angle between the first direction, the second direction and the third direction All are acute angles, and the first direction, the second direction and the third direction are located in the same plane.
  • the extended grating area 200 includes a first extended grating area 210 and a second extended grating area 220.
  • the first extended grating area 210 is configured to diffract the transmission light beam propagating along the first direction, so that the transmission light beam propagating along the first direction is partially deflected to the second direction.
  • the second grating area 2 propagates; the second extended grating area 220 is configured to diffract the transmission light beam propagating along the second direction, so that the transmission light beam propagating along the second direction is partially deflected and propagates toward the second grating area 2 .
  • the transmission direction can be flexibly arranged through grating direction modulation for multiple area distribution of the output image, thereby obtaining a wide angle of the output image and high efficiency of full energy utilization.
  • the grating structure of the first expanded grating region 210 and the grating structure of the second expanded grating region 220 may adopt a filling grating layer, wherein the filling grating layer may be a one-dimensional grating or a two-dimensional grating.
  • the first extended grating area 210 and the second extended grating area 220 can be further divided, and then the grating is extended. At this time, more light beams can eventually propagate towards the second grating area to avoid energy waste.
  • the first A extended grating area 211 and the first B extended grating area 212 are arranged sequentially on the path of the transmission beam propagating along the first direction
  • the second A extended grating area 221 and the second B extended grating area 222 are arranged sequentially on the path of the transmission beam propagating along the first direction.
  • the first extended grating area 211 diffracts the propagation light beam S1 propagating in the first direction, so that part of the propagation light beam propagating in the first direction is deflected and propagates to the second grating area 2, forming a first At this time, part of the propagating beam S21 continues to propagate in the first direction; the first B extended grating area 212 diffracts the propagating light beam that continues to propagate in the first direction, causing part of the propagating light beam that continues to propagate in the first direction to deflect The second grating area 2 propagates to form a second transmission beam S22.
  • the second extended grating area 221 diffracts the propagating light beam propagating along the second direction, causing part of the propagating light beam propagating along the second direction to deflect to the second grating area 2 to form the third propagating light beam S23. At this time, there is still part of the propagating light beam.
  • the second B expanded grating area 222 diffracts the propagation beam that continues to propagate in the second direction, causing part of the propagation beam that continues to propagate in the second direction to deflect to the second grating area 2 to form a fourth propagation beam. S24.
  • the propagating light beam S1 along the third direction is directly transmitted to the second grating area 2 .
  • the second grating area 2 obtains propagation beams from five directions, so that the transmission beam can cover the entire second grating area more evenly to obtain a more uniform output image brightness.
  • the first A extended grating area 211 and the second A extended grating area 221 are symmetrically arranged relative to the coupling grating area 100
  • the first B extended grating area 212 and the second B extended grating area 222 are arranged relative to the coupling grating area.
  • 100 symmetrical settings By arranging a symmetrical structure, the first propagation beam S21 and the third propagation beam S23 are symmetrically propagated to the second grating region 2 relative to the coupling grating region 100
  • the second propagation beam S22 and the fourth propagation beam S24 are symmetrically propagated relative to the coupling grating region 100.
  • 100 symmetrically propagates to the second grating area 2, further improving the uniformity distribution of the multi-path propagation beam and obtaining uniform output image brightness.
  • the filled grating structure 50 of the grating structure of the second grating region includes three stacked coupling filling grating layers (301, 302, 303); the three coupling filling grating layers are all one-dimensional grating structures, and the three coupling filling grating layers are one-dimensional grating structures.
  • the outcoupling filled grating layers (301, 302, 303) are configured to couple out the waveguide substrate 400 propagating light beams transmitted from different directions to the second grating region.
  • the filled grating structure 50 of the grating structure of the second grating region includes a coupling out filling grating layer, and the coupling out filling grating layer is a two-dimensional grating structure.
  • Figure 14 is a (K space) wave vector space diagram of the image beam of the diffracted optical waveguide shown in Figure 2.
  • the grating vectors coupled into the grating area 100 are K101, K102, K103, and the grating vector of the first extended grating area 211 is K211, the grating vector of the first B extended grating area 212 is K212, the grating vector of the second B extended grating area 221 is K221, the grating vector of the second B extended grating area 222 is K222, and the second grating area 2/300
  • the raster vectors are K301, K302, and K303.
  • Coupling out of the waveguide substrate 400 enters the user's eye.
  • the directions of K101, K102, and K103 are the first direction, the second direction, and the third direction respectively.
  • the angle between the first direction and the third direction is -60°
  • the angle between the second direction and the third direction is -60°.
  • the angle between the third direction and the third direction is 60°; the angle between the direction of K211 and the third direction is 60°; the direction of K212 is perpendicular to the third direction; the angle between the direction of K221 and the third direction is -60°; the direction of K222 Perpendicular to the third direction; the directions of K301, K302, and K303 are the opposite direction of the first direction, the opposite direction of the second direction, and the opposite direction of the third direction respectively.
  • the grating vector direction here is the direction that makes a major contribution to beam propagation and coupling.
  • the grating vector directions of multiple grating structures also include the opposite direction of the grating vector direction of the grating structure listed above, such as , the direction of K301 also includes the first direction.
  • the image beam emitted from the image source may be a monochromatic image beam or a color image beam (such as red, green, and blue (RGB) three-color image beam).
  • the filling grating structure 50 of the coupling grating area includes three stacked coupling filling grating layers; the three coupling filling grating layers are configured to convert the first waveband, the second waveband and the third waveband emitted by the image source.
  • the image beams are respectively coupled into the waveguide substrate 400 and form a transmission beam; the central wavelength of the first wave band is ⁇ 1, the central wavelength of the second wave band is ⁇ 2, the central wavelength of the second wave band is ⁇ 3, ⁇ 1> ⁇ 2> ⁇ 3; for example,
  • the first band is the red light band
  • the second band is the green light band
  • the third band is the blue light band.
  • two of the three coupling filled grating layers are configured to couple the image beam emitted by the image source into the waveguide substrate 400 and form a propagation beam
  • the other filled grating layer is configured to couple the aforementioned two filling grating layers. To compensate for insufficient coupling or missing bands of the layer.
  • the filled grating structure 50 coupled into the grating area may include more or less filled grating layers, each layer having a different tooth shape.
  • the parameters of the multiple coupled filled grating layers By modulating the parameters of the multiple coupled filled grating layers, one or more layers will cooperate to Image beams of multiple wavelengths or even full-band wavelengths are coupled into the waveguide substrate.
  • Figure 15 is a left view of a diffractive optical waveguide provided by the embodiment of Figure 3;
  • Figure 16 is a left view of another diffractive optical waveguide provided by the embodiment of Figure 3;
  • Figure 17 is another diffractive optical waveguide provided by the embodiment of Figure 3 A modification of the optical waveguide.
  • Figure 18 is a left view of another diffraction optical waveguide provided by the embodiment of Figure 3.
  • the first grating area 1 includes a coupling grating area 10 and an extended grating area 20 .
  • the extended grating area 20 includes at least two sub-areas. All include at least one extended fill grating layer.
  • the extended filling grating layer in different sub-regions can partially deflect the image beams in different viewing angle ranges coupled into the waveguide substrate 400 to propagate to the second grating region 2 .
  • multiple partial fields of view can cover the entire outcoupling grating area 30 more evenly.
  • Propagation beams propagating in different directions can carry image information of different field of view ranges respectively.
  • the union of these different field of view ranges is the full field of view range, and when multiple propagation beams finally converge to the second grating area for coupling out , the image beams in the entire field of view range can be effectively coupled out.
  • the diffractive optical waveguide can not only expand the field of view angle through field of view splicing, but also ensure effective coupling out of the entire field of view without missing the field of view.
  • the second grating area 2 includes an out-coupling grating area 30 , wherein the extended grating area 20 may be connected to the in-coupling grating area 10 and the out-coupling grating area 30 or not. Connected; the image source projection methods are different.
  • the coupling grating area 10 can be located on the central axis of the coupling grating area 30 or on one side of the central axis. More arrangement methods are not listed one by one.
  • the extended grating area 20 includes a first sub-area 21 and a second sub-area 22 .
  • the first sub-area 21 and the second sub-area 22 are respectively located on the upper surface M1 of the waveguide substrate 400 . and the lower surface M2 and there is an overlapping area, the first sub-region 21 and the second sub-region 22 each include at least one extended filling grating layer, and the extended filling grating layers in different sub-regions are configured to couple different elements into the waveguide substrate 400.
  • the image beam in the field of view range is partially deflected and propagated to the second grating area 2 .
  • the overlapping area is equivalent to area 23 in Figure 3.
  • the extended grating region 20 when the extended grating region 20 includes two sub-regions, the two sub-regions may not have overlapping regions, and the two sub-regions are located on at least one of the upper surface M1 and the lower surface M2 of the waveguide substrate 400 .
  • one layer of filled extended grating or multiple layers of filled extended grating can be set according to performance requirements.
  • the extended grating area 20 also includes a third sub-area 23, and the third sub-area 23 is located in the first sub-area. 21 and the second sub-region 22; both the first sub-region 21 and the second sub-region 22 include an extended fill grating layer, and the third sub-region 23 includes three stacked expanded fill grating layers (231, 232 , 233); the extended filling grating layer of the first sub-region 21 and the second sub-region 22 is configured to partially deflect the image beams in different field angle ranges along different directions to the second grating region 2 for propagation; the third sub-region The extended filling grating layer 23 is configured to expand the image beams in different field of view ranges to both sides and then deflect them to the second grating area 2 for propagation, ultimately allowing multiple partial fields of view to more evenly cover the entire second grating. Area 2.
  • the expanded grating area 20 When the expanded grating area 20 expands the beam, it can be divided into three parts of the field of view for expansion and propagation. After a part of the field of view is coupled into the waveguide substrate 400 through the coupling grating area 10, it propagates along the direction of the first path P1, and then passes through the first Part of the sub-region 21 is deflected to one side of the out-coupling grating region 30; a part of the field of view, after being coupled into the waveguide substrate 400 through the coupling-in grating region 10, propagates along the direction of the first path P2, and then passes through part of the second sub-region 22 Deflect to one side of the coupling-out grating area 30; a part of the field of view simultaneously expands to both sides through the third sub-region 23 and proceeds to the coupling-out grating area 30.
  • the grating area 30 adopts the grating arrangement as shown in Figures 3 and 4, and has a large image field of view (FOV).
  • FOV image field of view
  • the intersection of any two of the three partial fields of view does not need to be empty, and the union of the three partial fields of view is the full field of view to ensure that the light beams in the entire field of view can be effectively coupled out.
  • the coupling grating region 10 includes a coupling filling grating layer 11 , and the coupling filling grating layer 11 is configured to couple the image beam emitted from the image source into the waveguide substrate 400 ;
  • the second grating region 2 includes Three stacked outcoupling filled grating layers (31, 32, 33), the three outcoupling filled grating layers are configured to couple propagating light beams transmitted from different directions to the second grating region out of the waveguide substrate 400.
  • Figure 19 is a (K space) wave vector space diagram of the image beam in Figure 3.
  • the grating vector coupled into the grating area 10 is K10
  • the grating vector of the first sub-area 21 is K21
  • the grating vector of the second sub-area 22 is K22
  • the grating vector of the third sub-area 23 is K231, K232, K233
  • the raster vectors of the raster area 30 are K31, K32, and K33.
  • (a) in Figure 19 is a (K-space) wave vector space diagram of the image beam in Figure 3 coupled into the waveguide substrate
  • (b) in Figure 19 is a (K-space) diagram of the image beam in Figure 3 propagating and coupling out of the waveguide substrate.
  • Wavevector space diagram by rationally designing the grating periods and grating vector directions of multiple filled grating layers in the coupling grating area 10, the extended grating area 20 and the outcoupling grating area 30, the image beam passes through from coupling in to coupling out
  • the vector sum of the diffracted grating vectors is zero, ensuring that the image beam emitted from the image source can be coupled out of the waveguide substrate 400 and enter the user's eyes with substantially no dispersion.
  • the direction of K10 is the third direction
  • the third direction is the direction from the first grating area 1 to the second grating area 2
  • the angle between the direction of K21 and the opposite direction of the third direction is 60°
  • the angle between the K22 direction and the opposite direction of the third direction is -60°
  • the vector directions of K231, K232, and K233 are the directions where the angles between the opposite direction of the third direction are -60°, 0, and 60° respectively.
  • the grating vector of the decoupled filled grating layer is the same as the grating vector of the extended filled grating layer in the third sub-region.
  • the light beam with the field of view DIR1 is coupled into the waveguide substrate through the action of K10, then propagates through total reflection in the waveguide substrate at the angle DIR2, travels to the first sub-region 21, is deflected to the right by the action of K21, and travels in the waveguide substrate at the angle DIR3. Total reflection propagates, travels to the coupling grating area 30, and is effectively coupled out through the action of K231. Another part of the beam propagates total reflection in the waveguide substrate at an angle DIR2. After traveling out of the grating area 30, it is diffracted by K231 into a beam with an angle DIR4. According to the K domain diagram, it can be seen that this part of the beam cannot be fully reflected in the waveguide substrate.
  • the grating structure on the waveguide surface can be spliced and expanded in the K domain through reasonable grating period and grating direction design to achieve the function of increasing the field of view.
  • the structure shown in Figure 2 can also realize the splicing expansion of the field of view angle.
  • the coupling-filled grating layer can couple multiple wavelengths or even full-band image beams into the waveguide substrate.
  • the number of coupling-filled grating layers can also be increased, and multiple coupling-filled grating layers cooperate to couple image beams of multiple wavelengths or even full-wavelength bands into the waveguide substrate.
  • the coupling grating region 10 includes at least two coupling filling grating layers (11, 12). The two coupling filling grating layers are cooperatively configured to couple multiple wavelengths or even full-band image beams into the waveguide substrate.
  • the added coupling filled grating layer can be in another grating vector direction, so that multiple coupling propagation directions can be obtained, similar to the coupling grating structure shown in Figure 2.
  • the filled grating structure is applied to the grating layout of a specific diffractive optical waveguide.
  • the coupling stage multiple filled grating layers with different grating directions are used to couple the image beam emitted from the image source into the waveguide substrate. Later, it propagates in different directions; in the expansion stage, multi-region, single-layer or multi-layer filled grating layers with different grating directions are used to expand and transmit the image beam coupled into the waveguide substrate in different directions; it not only improves the utilization rate of light energy, It also improves the brightness uniformity of the entire image by propagating the beam from multiple directions to subsequent gratings, and can widen the band of the image beam coupled into the waveguide substrate.
  • the splicing of field of view angles obtains a wider range of field of view angles.
  • using a filled grating structure in the coupling area can also broaden the band of the image beam coupled into the waveguide substrate to a certain extent.
  • filled grating structures provide greater modulation flexibility when optimizing performance when applied to different functional areas. Not only the grating substrate but also the filling layer can be modulated.
  • the coupling efficiency of the image beam into the waveguide substrate can be increased through modulation, and the waveband of the image beam coupled into the waveguide substrate can be broadened.
  • the beam propagation attenuation can be compensated through modulation, and the uniformity of the pupil expansion and outcoupling image can be improved.
  • the parameter modulation of the filled grating structure includes the parameter modulation of the grating substrate and the parameter modulation of the filling layer.
  • the parameter of the filled grating structure 50 coupled into the grating area 10/100 is a first modulation variable, which is modulated to increase the coupling efficiency of the image beam emitted from the image source into the waveguide substrate 400 .
  • the parameters of the filling grating structure of the extended grating area 20/200 and the outcoupling grating area 30/300 are the second modulation variables.
  • the second modulation variable is modulated to modulate the grating diffraction efficiency to improve the observer's multiple movements in the orbit. The brightness uniformity of the image frame observed at the observable angle.
  • the first modulation variable includes, but is not limited to, the refractive index, tooth shape, tilt angle, period, duty cycle and depth of the grating substrate of the filled grating structure coupled into the grating area 10/100 and the refractive index of the filling layer.
  • modulating the first modulation variable may be modulating at least one of the aforementioned parameters.
  • modulating the first modulation variable may be modulating at least one of the foregoing parameters of at least one filled grating layer.
  • the first modulation variable is also modulated to broaden the coupling band of the image beam emitted from the image source into the waveguide substrate 400 to achieve full-color coupling.
  • the second modulation parameters include, but are not limited to, the refractive index, tooth shape, tilt angle, period, duty cycle and depth of the grating substrate of the expanded grating area 20/200 and the filled grating structure coupling out the grating area 30/300, and The refractive index of the filling layer; the second modulation parameter is modulated so that the diffraction efficiency along the beam propagation direction in the same functional area gradually increases; wherein the modulation of the second modulation parameter includes the modulation of the same filling grating layer in the same functional area Zone modulation.
  • the parameter modulation in the extended grating area and the out-coupling grating area not only includes parameter modulation similar to the in-coupling grating area, but also includes zone modulation of the same filled grating layer in the same functional area.
  • Zoned modulation includes zoned modulation of the grating substrate and zoned modulation of the filling layer, that is, zoned in the extended grating area and the outcoupling grating area, grating substrates with different parameters are used in different areas, and materials with different refractive index are used as filling layer to produce modulation.
  • Figure 20 shows a schematic diagram of the zonal modulation of the filling layer of the filling grating structure in the extended grating region in one embodiment. It can be seen from this figure that a material with a smaller relative refractive index difference is selected as the filling layer in the area close to the coupling grating area 10 to obtain a relatively low diffraction efficiency, while the refractive index is selected in the area far away from the grating area 10 Materials with large rate differences are used as filling layers to obtain relatively high diffraction efficiency. As the beam propagates, the diffraction efficiency is gradually increased to modulate the uniformity of the intensity of the beam propagating in the waveguide.
  • the diffraction efficiency can be gradually improved as the light beam propagates through the duty cycle or depth gradient modulation of the extended grating area 20/200 and the base grating outcoupling the grating area 30/300.
  • the absolute value of the refractive index difference between the refractive index n1 of the grating substrate and the refractive index n2 of the filling layer gradually decreases, the depth h of the grating substrate obtained after optimization will be larger, and the resulting diffraction efficiency will be higher.
  • the corresponding incident angle range will decrease; and when the absolute value of the refractive index difference between the refractive index n1 of the grating substrate and the refractive index n2 of the filling layer gradually increases, the depth h of the grating substrate obtained after optimization will be smaller, and the obtained The diffraction efficiency will decrease, and the corresponding incident angle range of the beam will increase; and after the duty cycle F of the grating substrate deviates from the optimized optimal value, the diffraction efficiency of the grating will gradually decrease, and the optimal incident angle range will drift, and the grating substrate
  • the slope angle ⁇ is optimized according to the application wavelength and angle.
  • the waveguide can be effectively modulated. uniformity of intensity of the propagating beam.
  • the incident light wavelength is 625 nm
  • the structure of the grating substrate is a helical tooth
  • the grating bevel angle is 58.8°
  • the grating period is 450 nm
  • the depth is 3.12 ⁇ m
  • the material of the grating substrate has a refractive index of 1.8
  • Acrylic resin the material of the filling layer is epoxy resin with a refractive index of 1.45.
  • Figure 21 is a schematic diagram of a tooth-shaped structure of a grating substrate provided by an embodiment of the present application.
  • the tooth structure of the grating substrate includes but is not limited to at least one of a straight tooth structure, a helical tooth structure, a trapezoidal structure, a triangular structure, and a step structure.
  • At least one of a straight tooth structure, a helical tooth structure, a trapezoidal structure, a triangular structure, and a step structure can be selected according to the requirements.
  • a helical tooth structure in the coupling grating area can improve the coupling efficiency; using a straight tooth structure or a small-angle helical tooth structure in the extended grating area can balance the uniformity of diffraction efficiency in the entire area.
  • the structure of the grating substrate includes a one-dimensional convex strip grating structure, a two-dimensional cross convex strip grating structure, and a two-dimensional cross strip recessed female grating structure.
  • the structure of the grating substrate can be prepared using a variety of etching processes.
  • a one-dimensional convex strip grating structure, a two-dimensional cross convex strip grating structure, and a two-dimensional cross strip recessed female grating structure are covered with a filling layer to form a filling.
  • the grating structure has a simple preparation process and is easy to implement.
  • the materials of the grating substrate and the filling layer include organic materials and transparent inorganic materials.
  • the material of the grating substrate and filling layer can be organic materials such as epoxy resin and acrylic, or transparent inorganic materials such as a-Si, TiO 2 , Nb 2 O 5 , SiN, SiO 2 , MgF 2 and other transparent inorganic materials.
  • the refractive index difference range of the grating substrate and the filling layer is ⁇ n, 0.01 ⁇ n ⁇ 1.4. Properly setting the refractive index difference range between the grating substrate and the filling layer can improve the diffraction efficiency of the filled grating structure.
  • the working mode of the filled grating structure includes a transmission grating mode and a reflection grating mode.
  • the filled grating structure can be a transmission grating or a reflection grating.
  • Full-frame brightness uniformity improves picture brightness uniformity at multiple viewing angles; on the other hand, multiple filled grating layers can be coupled into light beams of different bands respectively, and the superposition of multiple filled grating layers can be used for RGB three-color
  • the balance provides the design flexibility of a full-color single-chip AR waveguide, and when realizing full-color display, it can also improve the brightness uniformity of multiple color pictures at multiple allowed viewing angles; on the other hand, multi-layer filled gratings
  • the superposition of layers allows the 0th-order diffracted light to be diffracted and utilized again, increasing the utilization rate of light energy.
  • each filled grating layer can be modulated for grating efficiency, which can further improve the flexibility of grating efficiency modulation and obtain higher diffraction. efficiency and a wider field of view.
  • embodiments of the present application also provide a design method of a diffractive optical waveguide, which is used to design the diffractive optical waveguide provided in the above embodiments.
  • the design method includes the following steps.
  • the diffracted light wave produced by the design method of a diffractive optical waveguide provided in the embodiment of the present application has the structure provided in the above embodiment.
  • the processing of the grating substrate different processing paths can be formed for different grating substrate materials.
  • this application adopts the imprinting path for processing.
  • the base coated with curing glue is imprinted, cured, and demoulded to obtain a grating consistent with the motherboard structure.
  • Base structure For TiO 2 , SiO 2 , MgF 2 and other materials, the required grating material can be coated on the base sheet, and then the base sheet is spin-coated with photoresist, developed, masked, etched, and finally the grating base structure is obtained.
  • the conventional coating path which is mainly filled with the designed conventional optical coating materials, such as Au, Ag, Al, MgO, SiO 2 , MgF 2 , CaF 2 , etc., the processes used are evaporation and sputtering.
  • Another path is to use cured material for filling.
  • the first grating structure and/or the second grating structure includes a filled grating structure
  • the filled grating structure includes a multi-layer stacked filled grating layer
  • the multi-layer stacked filled grating layer is formed by a multi-layer stacked filled grating layer. Obtained by aligning and superposing a single layer of filled grating layers. As shown in FIG. 24 , after each filled grating layer is prepared, alignment is performed and the next filled grating layer is prepared thereon.
  • the processing difficulty will increase with the increase of the design depth, and it will also cause limitations in the field of view range.
  • the filled grating structure can be composed of multiple layers of base gratings of different shapes and filling materials. By superimposing multiple layers of filled gratings, the flexibility of grating efficiency modulation can be further improved, resulting in higher diffraction efficiency and a wider field of view range. . As shown in Figure 8 and Figure 10, by superimposing two layers of filled gratings, a diffraction efficiency of 63 to 87% can be obtained in a large field of view range of -23° to 10°.
  • the difficulty of single master processing is also reduced, and structural sidewalls similar to curved surfaces can be realized, as well as structural shapes that are difficult to process with conventional semiconductor processes, and more complex grating functions can be realized. Further expand the field of view.
  • the processing of multi-layer filled grating structures can rely on the combination of the base grating production path and the filling material path introduced above. After completing the filling structure of one layer, the upper grating structure is covered on its surface through high-precision alignment, thereby giving the design and production processes provide great flexibility.
  • inventions of the present application also provide an augmented reality device.
  • the augmented reality device includes a device body, an optical machine, and a diffractive optical waveguide provided by the present application.
  • the optical machine and the diffractive optical waveguide are correspondingly provided on the device.
  • the main body allows the image beam provided by the optical machine to be coupled into the waveguide substrate by the coupling grating structure of the diffractive optical waveguide, and propagates to the extended grating region and/or the coupling out grating region by total reflection in the waveguide substrate, and is coupled out of the grating.
  • the structure couples out of the waveguide substrate and is received by the user's eyes to see corresponding images.
  • the augmented reality device is implemented as a near-eye reality device
  • the device body is implemented as a spectacle frame.
  • the spectacle frame includes a beam portion and a temple portion, and the temple portion extends from at least one of the left and right sides of the beam portion.
  • the diffraction optical waveguide is correspondingly provided on the beam portion.
  • the optical engine that provides the image beam in the near-eye display device is correspondingly arranged on the side of the waveguide substrate, so that the optical engine is directly installed into the temple leg of the near-eye display device, so that the optical engine is hidden in the side projection display device.
  • the inner side of the temple helps to make the entire device appear lighter and more aesthetically pleasing.
  • the optical engine is suitable to be installed on the beam part of the device body, so that when the user wears the near-eye display device, the optical engine is correspondingly located near the user's forehead, which helps to reserve a larger area for the optical engine. Installation space.
  • the augmented reality device is implemented as a head-up display (HUD)
  • the device body is implemented as a windshield
  • the diffraction light waveguide is correspondingly disposed on the inside of the windshield, so that through the light
  • the image beam projected by the machine is transmitted through the diffraction light waveguide, projected to the windshield, and reflected inward through the windshield to enter the eyes, allowing the user to see virtual images at a longer distance.
  • the diffractive optical waveguide is correspondingly disposed inside the windshield, so that the image beam projected by the optical machine is directly received by the user's eyes to see the corresponding image after being decoupled by transmission through the diffractive optical waveguide.
  • the windshield in the augmented reality device may be, but is not limited to, implemented as a front windshield of a transportation vehicle such as an airplane or a car, and the augmented reality device may also be implemented as an augmented reality head-up display (Augmented Reality-Head Up). Display, AR-HUD).
  • augmented reality head-up display Algmented Reality-Head Up. Display, AR-HUD.
  • the diffractive optical waveguide provided by this application improves light energy utilization efficiency and coupling uniformity. It is no longer necessary to significantly increase the projection power of the optical machine in order to compensate for the low light energy utilization and provide strong image light in a large enough eye box, as is the case with vehicle-mounted HUDs equipped with ordinary diffractive optical waveguides. , making it difficult for the optical machine to dissipate heat due to its large power.
  • the augmented reality device of this application only needs to use a less powerful optical engine to form a high-contrast and high-quality virtual image in front of the windshield for users to watch.

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Abstract

本申请公开了一种衍射光波导及其制备方法，衍射光波导包括波导基底以及位于所述波导基底表面的第一光栅区域和第二光栅区域，所述第一光栅区域内的光栅结构，设置为以下至少之一：将图像源出射的图像光束耦入所述波导基底形成沿不同方向传播的传播光束；衍射耦入所述波导基底的图像光束形成沿不同方向传播的传播光束；所述第二光栅区域内的光栅结构，设置为衍射所述传播光束形成输出光束。

Description

衍射光波导
本申请要求在2022年06月24日提交中国专利局、申请号为202210729567.7的中国专利申请的优先权，该申请的全部内容通过引用结合在本申请中。
技术领域
本申请实施例涉及显示技术领域，例如涉及一种衍射光波导。
 背景技术
增强现实作为一种将虚拟世界信息与真实世界信息“无缝”集成的技术，是将通过微型投影***提供的虚拟内容与真实环境叠加到同一个画面或空间以同时存在，使用户获得虚拟与现实融合的体验。
图1是相关技术中的一种常见衍射光波导的光栅布局方式，图像源出射的图像光束S经过耦入光栅11耦入光波导基底12后，经转折光栅13在一个维度上扩展并转向耦出光栅14，由耦出光栅14在另一个维度再次扩展并耦出进入人眼。
但是，这种光栅布局方式形成单一的光传输通道，使得耦出光束的角度受限于一个传播方向的波导玻璃片的全内反射要求，无法获得较大的视场角度。
发明内容
本申请实施例提供一种衍射光波导及其制备方法，通过对第一光栅区域内的光栅结构进行设计，使得图像光束在耦入后便能得到多个方向的光束，在波导基底内形成多条传播路径；或者，在图像光束在耦入光波导后，通过衍射形成沿多条路径传播的传播光束，不同路径可分别携带不同视场角的图像信息，最终均汇聚到第二光栅区域进行输出，可增大衍射光波导的视场角，而且还能提高多条路径的传播光束的均匀性分布，有效提高衍射光波导的视觉成像效果。
本申请实施例提供了一种衍射光波导，包括波导基底以及位于所述波导基底表面的第一光栅区域和第二光栅区域；所述第一光栅区域内的光栅结构，设置为以下至少之一：将图像源出射的图像光束耦入所述波导基底形成沿不同方向传播的传播光束；衍射耦入所述波导基底的图像光束形成沿不同方向传播的传播光束；所述第二光栅区域内的光栅结构，设置为衍射所述传播光束形成输出光束。
本申请实施例还提供了一种衍射光波导的制备方法，包括：提供波导基底；在所述波导基底的第一光栅区域形成第一光栅结构，以及在第二光栅区域形成第二光栅结构；其中，所述第一光栅结构，设置为以下至少之一：将图像源出射的图像光束耦入所述波导基底形成沿不同方向传播的传播光束；衍射耦入所述波导基底的图像光束形成沿不同方向传播的传播光束；所述第二光栅结构设置为衍射所述传播光束形成输出光束。
 附图说明
图1为相关技术中的一种衍射光波导的结构示意图；
图2为本申请实施例提供的一种衍射光波导的平面结构示意图；
图3为本申请实施例提供的另一种衍射光波导的平面结构示意图；
图4为本申请实施例提供的另一种衍射光波导的平面结构示意图；
图5为本申请实施例提供的一种填充光栅结构的纵剖面图；
图6为本申请实施例提供的另一种填充光栅结构的纵剖面图；
图7为本申请实施例提供的填充光栅结构在不同波长光入射下衍射效率与视场角的关系示意图；
图8为本申请实施例提供的另一种填充光栅结构的纵剖面图；
图9为本申请实施例提供的另一种填充光栅结构的纵剖面图；
图10为本申请为本申请实施例提供的填充光栅结构衍射效率与视场角的关系示意图；
图11是图2实施例提供的一种衍射光波导的左视图；
图12是图2实施例提供的另一种衍射光波导的左视图；
图13是图2实施例提供的另一种衍射光波导的左视图；
图14为图2中图像光束的(K空间)波矢空间图；
图15是图3实施例提供的一种衍射光波导的左视图；
图16是图3实施例提供的另一种衍射光波导的左视图；
图17是图3实施例提供的衍射光波导的变形；
图18是图3实施例提供的另一种衍射光波导的左视图；
图19为图3中图像光束的(K空间)波矢空间图；
图20为本申请实施例提供的一种填充层折射率分区调制的示意图；
图21为本申请实施例提供的一种光栅基底的齿形结构的示意图；
图22为本申请实施例提供的填充光栅结构的光栅基底的制备流程示意图；
图23为本申请实施例提供的填充光栅结构的填充层的制备流程示意图；
图24为本申请实施例提供的多层填充光栅层的制备流程示意图。
 具体实施方式
以下将结合本申请实施例中的附图，通过具体实施方式，描述本申请的技术方案。
本申请实施例提供一种衍射光波导，包括波导基底以及位于波导基底表面的第一光栅区域和第二光栅区域；第一光栅区域内的光栅结构，设置为将图像源出射的图像光束耦入波导基底形成沿不同方向传播的传播光束；和/或，设置为衍射耦入波导基底的图像光束形成沿不同方向传播的传播光束；第二光栅区域内的光栅结构，设置为衍射传播光束形成输出光束。
本申请提供的波导基底包括第一光栅区域和第二光栅区域，其中第一光栅区域包括耦入光栅区域，第二光栅区域包括耦出光栅区域。在一些实施例中，第一光栅区域还包括扩展光栅区域。图像源朝向耦入光栅区域投射，耦入光栅区域的光栅结构将图像源投射的图像光束耦入波导基底形成传播光束，传播光束在波导基底内全反射地传播至耦出光栅区域。在一些实施例中，传播光束在波导基底内全反射地传播至扩展光栅区域再传播至耦出光栅区域。
第一光栅区域和/或第二光栅区域设置于传播光束全反射传播所在表面中的至少一个表面，并通过对第一光栅区域的光栅结构进行设计，使得第一光栅区域内耦入光栅区域的光栅结构能够将图像源出射的图像光束耦入波导基底形成沿不同方向传播的传播光束；和/或，使得第一光栅区域内扩展光栅区域的光栅结构能够衍射耦入波导基底的图像光束形成沿不同方向传播的传播光束，通过不同方向传播的传播光束携带不同视场角范围的图像信息，再结合合理的光栅参数设计，使得视场角(Field of View，FOV)在K域上得以拼接扩展，以实现增大视场角的功能。以RI1.9为例，通过视场角拼接可实现70度甚至更大的FOV。
示例性地，图2为本申请实施例提供的一种衍射光波导的平面结构示意图；衍射光波导包括波导基底400以及位于波导基底400表面的第一光栅区域1和第二光栅区域2；第一光栅区域1内的光栅结构100，设置为将图像源出射的图像光束耦入波导基底400形成沿三个不同方向传播的传播光束S1。
示例性地，图3为本申请实施例提供的另一种衍射光波导的平面结构示意图；图4为图3所示的衍射光波导的三种变形。结合图3和图4所示，本申请实施例提供的衍射光波导包括波导基底400以及位于波导基底400表面的第一光栅区域1和第二光栅区域2；第一光栅区域1内的光栅结构(21、22、23)设置为衍射耦入波导基底400的图像光束形成沿不同方向传播的传播光束。
示例性地，结合图2-图4所示，衍射光波导包括波导基底400，波导基底400的材料可以是光学玻璃或者树脂，厚度在0.5mm—3mm之间，波导基底400的长度可根据实际场景的需要设置。沿图中Z方向，波导基底400具有相互平行的第一表面M1和第二表面M2(图中未示出)，可以在波导基底400的第一表面M1和/或第二表面M2设置第一光栅区域1和第二光栅区域2，图2-图4仅示出了在波导基底400的第一表面M1设置第一光栅区域1和第二光栅区域2，第一光栅区域1与第二光栅区域2内的光栅结构可以是一维光栅和/或二维光栅。
设置图像光束自从第一光栅区域1耦入波导基底400至从第二光栅区域2耦出波导基底400所经过衍射光栅的光栅矢量之和基本为零，确保耦入波导基底的图像光束能够基本无色散地耦出波导基底400进入用户眼睛。
本申请实施例还提供了一种填充光栅结构，填充光栅结构包括至少一层填充光栅层；填充光栅层包括光栅基底和填充层，填充层设置为填充光栅基底之间的间隙并在填充光栅结构远离波导基底的一侧形成平整光滑的表面；光栅基底和填充层的折射率不同。由于填充层在填充光栅基底后形成平整光滑的表面，其上可以继续叠加填充光栅层，形成多层堆叠的填充光栅层的光栅结构。
可实施地，填充层的层高大于或者等于光栅基底的光栅深度，相邻填充光栅层之间光栅基底中基底结构对齐，基于填充层的层高不同而选择性设置光栅的深度，改善特定视场角的衍射效率。
可实施地，填充层的层高等于光栅基底的光栅深度，相邻填充光栅层之间光栅基底中基底结构首尾相连，形成连续的光栅结构，多个光栅基底首尾连接处无填充层。控制每个填充光栅层中多个光栅单元的倾斜角度，进而调控衍射效率和均匀性。
多层光栅基底形成独立的多个光栅结构单元，相邻光栅结构单元不包括残留层，进而形成独立的单元，该结构能够防止残留层的存在对衍射效率和均匀性的影响；同时，可在每一层填充光栅层上沉积或溅射一层材料层，材料可为有机材料和透明无机材料，以改善整个光栅层的均匀性和衍射效率，当然，可选择部分或全部光栅层做相同工艺处理，在此不做限定。
示例性地，图5为本申请实施例提供的一种填充光栅结构的纵剖面图。参考图5，该填充光栅结构包括一层填充光栅层，填充光栅层包括光栅基底511和填充层512，光栅基底511为常规的表面浮雕光栅，填充层设置为填充光栅基底之间的间隙并在填充光栅结构50远离波导基底400的一侧形成平整光滑的表面，填充层的折射率n2可以高于或者低于光栅基底的折射率n1。
在填充光栅结构下，对基底光栅的参数以及填充层的折射率进行调制优化，使得填充光栅结构能够对多个波长均有较高的衍射效率。图7示出了一个实施例中一种填充光栅结构在不同入射波长下的衍射效率和入射角的关系图。该实施例中，入射光波长分别为465nm，525nm，625nm，光栅基底的结构为梯形，梯形左倾角为66°，梯形右倾角为113°，光栅周期为420nm，光栅深度为597nm，光栅基底的材料为TiO2(折射率为2.30)，填充层的材料为环氧树脂(折射率为1.48)，参考图7可以看到，在-23°～7°的入射角范围内，三种颜色的入射波长的衍射效率都高于50％。对于这样的大视场角、高效率的填充光栅结构，通过结合其他参数的调制后，可以应用于单片全彩型增强现实(Augmented Reality，AR)光波导。
示例性的，图8为本申请实施例提供的另一种填充光栅结构的纵剖面图；该填充光栅结构包括两层填充光栅层；图9为本申请实施例提供的另一种填充光栅结构的纵剖面图，该填充光栅结构包括三层填充光栅层。作为一种可行的实施方式，填充光栅结构50还可以包括更多层填充光栅层。不同层填充光栅层的光栅基底的参数可以不同，如图8所示，两层填充光栅层的光栅基底的光栅齿形不同，齿的横截面可为矩形、菱形、三角形等多种；多个光栅层之间形成填充层；光栅基底由多个独立的光栅结构单元形成，且多个光栅结构单元之间无光栅材料残留层连接而形成独立的单元。如图9所示，三层填充光栅层的光栅基底的光栅齿形相同且首尾相连形成连续光栅结构，首尾相连处无填充层而直接连接，但每层填充光栅层的倾斜角度不同，通过控制每层光栅结构的倾斜角度实现光场调制。此外，不同层填充光栅层的填充层的折射率可相同或不同，根据调制效率或均匀性进行选择。如图9所示的每层光栅齿形相同，当然可不同，基于不同的调制要求而选择限定多层光栅齿形。对于图8、9所示的结构，可在每层填充光栅层上设置一层材料层，材料可为有机材料和透明无机材料，以改善整个光栅层的均匀性和衍射效率。
相较于常规的表面浮雕光栅和体光栅，本申请所提供的填充光栅结构是通过在光栅基底上覆盖填充层形成的，光栅基底与填充层为界面，而填充层的折射率是可调节的参数，可以通过降低光栅基底与填充层之间的折射率差值，增大光栅基底的深度，以增加光线与填充光栅结构之间的相互作用次数，从而大幅提高填充光栅结构的衍射效率。此时本申请所提供的填充光栅结构产生高衍射效率的方式与体光栅相近，衍射效率远超常规的表面浮雕型光栅。而且，本申请所提供的填充光栅结构又能类似常规的表面浮雕型光栅通过对倾角、深度、形状、占空比等光栅相关参数进行优化，以较大的折射率差值来产生不同于体光栅的窄带FOV，规避了体光栅调制不灵活，衍射角度范围较小的问题。另外，本申请所提供的填充光栅结构不直接与空气接触，相较于常规的表面浮雕型光栅无需额外增加保护片保护光栅结构不被污染与破坏，进一步缩小体积。可见，本申请提供的填充光栅结构兼具高衍射效率和较宽的角度响应带宽的优势。
其次，特别突出地，由于填充层形成平整光滑的表面，可在其上继续叠加填充光栅层，形成多层结构，极大提高了设计自由度，而其中不同的倾斜角度或形状，可以提升某个颜色光束的特定视场角的效率，以满足衍射光波导的各光栅功能区域(比如，耦入区域、扩展区域、耦出区域等)的设计功能，而这是目前常规的单层(空气隙类型)表面浮雕光栅所不能实现的功能。当然，还可在每一层填充光栅层上形成一层材料层，(透光的有机材料和无机材料均可)，以改善整个光栅层的均匀性和衍射效率。
再次，对于单层光栅层(表面浮雕光栅或填充光栅结构)，在衍射时，0级衍射是透射光束，没有被衍射的光束能量直接透射而被浪费。目前的表面浮雕光栅，大都采用倾斜光栅来提高一侧的衍射效率，但是该光束是单个方向传播的。而为了输出图像全幅面各个角度光束的均匀性，更好的效果是光束能够从多个角度传播至耦出光栅，以获得更高的效率以及更均匀的图像输出。这样，多层填充光栅的叠合就可以充分发挥优势：位置在下的填充光栅层能再次利用上层透过的0级衍射光束(即原来被浪费的能量)，而且不同层的填充光栅层还可以采用不同的光栅方向，灵活设计为将光束沿不同方向传输至后续光栅区域。此外，多层填充光栅层叠加还可用于色彩的均衡，通过多层填充光栅层协同将三色波长均耦入波导基底，不仅提高能量使用效率，而且能够提高图像的亮度均匀性(引导光束去照亮暗角区域)，大幅度提高设计灵活性和图像质量。
需要说明的是，本申请所提及的均匀性包括在动眼眶内的各个可观看角度下观看输出图像均能看到全幅图像且亮度均匀；以及在彩色光束投射的场景下，在动眼眶内的各个可观看角度下观看输出图像时，对于每个颜色图像能看到全幅图像且亮度均匀。光束入射到本申请提供的填充光栅结构产生衍射时，由于光束通常具有一定的视场角范围，填充光栅结构的衍射效率是以视场角为变量的曲线，多个视场角均有对应的衍射效率。对于多层叠加的填充光栅结构，上层填充光栅结构对光束利用后，未被利用的部分透射到下层填充光栅结构，此时下层填充光栅结构便能继续利用光束，可以进一步提高衍射效率。
图10为本申请实施例提供的一种填充光栅结构的衍射效率和入射角的关系图。下面列举一个实施例，结合图8所示，图像源出射的图像光束的入射光波长为532nm，填充光栅结构为两层填充光栅层，光栅周期均为360nm，第一层耦入填充光栅层101的光栅基底的基底结构为三角齿，光栅基底的材料为折射率为1.9的丙烯酸树脂，填充层的材料为折射率为1.5的环氧树脂，三角形斜边角为50.6°，光栅深度为4.4μm；第二层耦入填充光栅层102的光栅基底的基底结构为梯形，光栅基底的材料为TiO2，填充层的填充材料为SiO2，梯形左倾角62°，右边倾角125°，光栅深度364nm。通过两层耦入填充光栅层叠加，如图10所示，可以在-23°～10°的大视场角范围内均获得63～87％的衍射效率。
本申请提供的填充光栅结构，可调参数种类多、灵活性大、自由度高，通过对这些参数的调制，可调控不同颜色光束的不同视场角在不同位置的效率及均匀性，以满足衍射光波导的多个光栅功能区域(比如，耦入、扩展、耦出等)设计功能，而这是单层表面浮雕光栅(空气隙类型)所不能实现的功能。
填充光栅结构50的光栅基底不直接与空气接触，填充层起到保护光栅基底的作用，不需要额外保护片用以保护光栅基底，这样在包括填充光栅结构的衍射光波导用于可穿戴设备时，减低了重量，使得包括填充光栅结构的波导片可单片直接使用。采用本申请提供的填充光栅结构的可穿戴设备兼具高衍射效率和较宽角度响应带宽的优势，满足可穿戴型产品轻便易佩戴的市场要求。
需要说明的是，本申请提供的一种衍射光波导，其第一光栅区域的光栅结构和/或第二光栅区域的光栅结构可以采用常规的表面浮雕光栅，也可以采用本申请提供的填充光栅结构，且光栅结构可以是一维结构也可以是二维结构。以下针对将填充光栅结构应用于图2所示的衍射光波导的光栅布局方式进行阐述。
图11是图2实施例提供的一种衍射光波导的左视图。结合图2、图5和图11所示，可选的，第一光栅区域包括耦入光栅区域100和扩展光栅区域200，耦入光栅区域100的光栅结构为填充光栅结构50，填充光栅结构50包括至少两层堆叠的耦入填充光栅层；两层耦入填充光栅层设置为将图像源发出的图像光束耦入波导基底400并形成沿不同方向传播的传输光束；扩展光栅区域的光栅结构设置为衍射传输光束，使得传输光束部分偏转向第二光栅区域2传播。耦入填充光栅层可以是一维光结构。可选的，耦入光栅区域的光栅结构为填充光栅结构50，填充光栅结构50包括一层耦入填充光栅层，该耦入填充光栅层为二维光栅结构。沿不同方向传播的传输光束可以分别携带不同视场角范围的图像信息，这些不同视场角范围的并集为全视场角范围，而且多条传播光束最终汇聚至第二光栅区域耦出时，全视场角范围的图像光束均能有效耦出。这样，衍射光波导既能通过视场拼接扩大视场角，也能保证全视场的图像光束有效耦出不存在视场缺失。
图11示出了耦入光栅区域100的光栅结构由耦入填充光栅层101和耦入填充光栅层102堆叠形成(在其他可实施方式中，耦入光栅区域100的光栅结构可以包括更多层的耦入填充光栅层)。当多层耦入填充光栅层的光栅矢量方向不一样时，耦入填充光栅层101将部分图像光束耦入光波导并沿第一方向传播，耦入填充光栅层101衍射产生的0级衍射光透射进入下一层耦入填充光栅层(耦入填充光栅层102)，图像光束能再次被衍射耦入光波导并沿第二方向传播，这样不仅能提高光能利用效率，还能产生分别沿至少两个方向传播的光束并传播至后续的光栅区域，有利于耦出图像全幅面以及亮度均匀性的调制。
需要说明的是，在耦入光栅区域100的光栅结构包括更多层的耦入填充光栅层时，光能利用效率能够进一步提高，亮度均匀性的调制的灵活性也更高。
图12是图2实施例提供的另一种衍射光波导的左视图；图13是图2实施例提供的另一种衍射光波导的左视图。作为一种可行的实施方式，结合图2、图5、图12和图13所示，可选的，耦入光栅区域的光栅结构的填充光栅结构50包括三层堆叠的一维耦入填充光栅层(101、102、103)；三层耦入填充光栅层(101、102、103)的光栅矢量方向不同，三层耦入填充光栅层(101、102、103)设置为将图像源发出的图像光束耦入波导基底400并形成分别沿第一方向(D1)、第二方向(D2)和第三方向(D3)传播的传播光束；第三方向为从第一光栅区域1指向第二光栅区域2的方向(在图2中第三方向为Y轴负方向)，沿第三方向的传播光束S1直接传输至第二光栅区域2，第一方向和第二方向与第三方向的夹角均为锐角，第一方向、第二方向和第三方向位于同一平面内。
扩展光栅区域200包括第一扩展光栅区域210和第二扩展光栅区域220，第一扩展光栅区域210设置为衍射沿第一方向传播的传输光束，使得沿第一方向传播的传输光束部分偏转向第二光栅区域2传播；第二扩展光栅区域220设置为衍射沿第二方向传播的传输光束，使得沿第二方向传播的传输光束部分偏转向第二光栅区域2传播。在本实施例中，传输方向可以通过光栅方向调制来灵活布置，用于输出图像的多个区域分布，从而获得输出图像的广角和能量充分利用的高效率。第一扩展光栅区域210的光栅结构和第二扩展光栅区域220的光栅结构可以采用一层填充光栅层，其中，一层填充光栅层可以是一维光栅或者二维光栅。通过设置第一扩展光栅区域210和第二扩展光栅区域220，可分别对沿不同方向传播的传输光束进行扩展并使其部分转向第二光栅区域传播以耦出波导基底进入人眼。
在上述实施例的基础上，继续结合图2、图5、图12和图13所示，可选的，可以继续划分第一扩展光栅区域210和第二扩展光栅区域220，在对光栅进行扩展时能使得更多的光束最终朝向第二光栅区域传播，避免能量浪费。设置第一甲扩展光栅区域211和第一乙扩展光栅区域212依次位于沿第一方向传播的传输光束的路径上，设置第二甲扩展光栅区域221和第二乙扩展光栅区域222依次位于沿第二方向传播的传输光束的路径上，第一甲扩展光栅区域211衍射沿第一方向传播的传播光束S1，使得沿第一方向传播的传播光束部分偏转向第二光栅区域2传播，形成第一传播光束S21，此时还有部分传播光束继续沿第一方向传播；第一乙扩展光栅区域212则衍射继续沿第一方向传播的传播光束，使得继续沿第一方向传播的传播光束部分偏转向第二光栅区域2传播，形成第二传输光束S22。第二甲扩展光栅区域221衍射沿第二方向传播的传播光束，使得沿第二方向传播的传播光束部分偏转向第二光栅区域2传播，形成第三传输光束S23，此时还有部分传播光束继续沿第二方向传播；第二乙扩展光栅区域222衍射继续沿第二方向传播的传播光束，使得继续沿第二方向传播的传播光束部分偏转向第二光栅区域2传播，形成第四传播光束S24。图像源出射的图像光束经耦入光栅区域耦入波导基底400后，沿第三方向的传播光束S1直接传输至第二光栅区域2。这样，第二光栅区域2获得来自五个方向的传播光束，使得传输光束可以更均匀地覆盖整个第二光栅区域，以获得更均匀的输出图像亮度。
可选的，第一甲扩展光栅区域211与第二甲扩展光栅区域221相对于耦入光栅区域100对称设置，第一乙扩展光栅区域212与第二乙扩展光栅区域222相对于耦入光栅区域100对称设置。通过设置对称结构，使得第一传播光束S21和第三传播光束S23相对于耦入光栅区域100对称传播至第二光栅区域2，第二传播光束S22和第四传播光束S24相对于耦入光栅区域100对称传播至第二光栅区域2，进一步提高多路径传播光束的均匀性分布，获得均匀的输出图像亮度。
可选的，第二光栅区域的光栅结构的填充光栅结构50包括三层堆叠的耦出填充光栅层(301、302、303)；三层耦出填充光栅层均为一维光栅结构，三层耦出填充光栅层(301、302、303)设置为将从不同方向传输至第二光栅区域的传播光束耦出波导基底400。可选的，第二光栅区域的光栅结构的填充光栅结构50包括一层耦出填充光栅层，该耦出填充光栅层为二维光栅结构。
图14为图2所示的衍射光波导的图像光束的(K空间)波矢空间图，假设耦入光栅区域100的光栅矢量为K101、K102、K103，第一甲扩展光栅区域211的光栅矢量为K211，第一乙扩展光栅区域212的光栅矢量为K212，第二甲扩展光栅区域221的光栅矢量为K221，第二乙扩展光栅区域222的光栅矢量为K222，第二光栅区域2/300的光栅矢量为K301、K302、K303。图14中(a)为沿第一方向传播的图像光束的(K空间)波矢空间图，图14中(b)为沿第二方向传播的图像光束的(K空间)波矢空间图；图14中(c)为沿第三方向传播的图像光束的(K空间)波矢空间图，通过合理设计耦入光栅区域100的多个耦入填充光栅层以及第二光栅区域2/300内的多个耦出填充光栅层的光栅周期和光栅矢量方向，使得图像光束从耦入到耦出所经过衍射的光栅矢量的矢量之和为零，确保耦入波导基底的图像光束能够基本无色散地耦出波导基底400进入用户眼睛。例如，结合图2和图13，K101、K102、K103的方向分别为第一方向、第二方向和第三方向，其中第一方向与第三方向的夹角为-60°，第二方向与第三方向的夹角为60°；K211的方向与第三方向的夹角为60°，K212方向垂直于第三方向，K221的方向与第三方向的夹角为-60°，K222的方向垂直于第三方向；K301、K302、K303的方向分别为第一方向的反方向、第二方向的反方向和第三方向的反方向。需要说明的是，这里的光栅矢量方向是对光束传播和耦出做出主要贡献的方向，多个光栅结构的光栅矢量方向还包括前文列出的该光栅结构的光栅矢量方向的反方向，比如，K301的方向还包括第一方向。
可以理解，图像源出射的图像光束可以是单色图像光束，也可以是彩色图像光束(如红绿蓝(RGB)三色图像光束)。对于彩色图像光束，耦入光栅区域的填充光栅结构50包括三层堆叠的耦入填充光栅层；三层耦入填充光栅层设置为将图像源发出的第一波段、第二波段以及第三波段的图像光束分别耦入波导基底400并形成传输光束；第一波段的中心波长为λ1，第二波段的中心波长为λ2，第二波段的中心波长为λ3，λ1>λ2>λ3；如，第一波段为红光波段，第二波段为绿光波段，第三波段为蓝光波段。或者，三层耦入填充光栅层中的其中两层填充光栅层设置为将图像源发出的图像光束耦入波导基底400并形成传播束，另外一层填充光栅层设置为对前述两层填充光栅层的耦入不足或缺失的波段进行补偿。当然，耦入光栅区域的填充光栅结构50可以包括更多或者更少的填充光栅层，每层齿形不同，通过对多层耦入填充光栅层的参数进行调制，一层或多层协同将多个波长甚至全波段的图像光束耦入波导基底。
以下针对将填充光栅结构应用于图3所示的衍射光波导的光栅布局方式进行阐述。
图15是图3实施例提供的一种衍射光波导的左视图；图16是图3实施例提供的另一种衍射光波导的左视图；图17是图3实施例提供的另一种衍射光波导的一种变形，图18是图3实施例提供的另一种衍射光波导的左视图。
结合图3-图4、图15-图17所示，可选的，第一光栅区域1包括耦入光栅区域10和扩展光栅区域20，扩展光栅区域20包括至少两个子区域，每个子区域内均包括至少一层扩展填充光栅层。不同子区域的扩展填充光栅层可将耦入波导基底400的不同视场角范围的图像光束部分偏转向第二光栅区域2传播。最终多个部分视场均可更均匀地覆盖整个耦出光栅区域30。
沿不同方向传播的传播光束可以分别携带不同视场角范围的图像信息，这些不同视场角范围的并集为全视场角范围，而且多条传播光束最终汇聚至第二光栅区域耦出时，全视场角范围的图像光束均能有效耦出。这样，衍射光波导既能通过视场拼接扩大视场角，也能保证全视场有效耦出不存在视场缺失。
结合图3-图4、图15-图18所示，第二光栅区域2包括耦出光栅区域30，其中，扩展光栅区域20与耦入光栅区域10和耦出光栅区域30可以相接或者不相接；图像源投射方式不同，耦入光栅区域10可位于耦出光栅区域30的中轴线上或者中轴线的一侧，更多的设置方式这不再一一列举。
结合图3和图17所示，可选的，扩展光栅区域20包括第一子区域21和第二子区域22，第一子区域21与第二子区域22分别位于波导基底400的上表面M1和下表面M2且存在重叠区域，第一子区域21和第二子区域22内均包括至少一层扩展填充光栅层，不同子区域的扩展填充光栅层设置为将耦入波导基底400的、不同视场角范围的图像光束，部分偏转向第二光栅区域2传播。重叠区域等效为图3中的区域23。可选地，扩展光栅区域20包括两个子区域时，这两个子区域也可不存在重叠区域，且该两个子区域位于波导基底400的上表面M1和下表面M2中的至少一面。这两个子区域内可根据性能需要设置一层填充扩展光栅或者多层填充扩展光栅。
在上述实施例的基础上，继续结合图3-图4、图15-图18所示，可选的，扩展光栅区域20还包括第三子区域23，第三子区域23位于第一子区域21和第二子区域22之间；第一子区域21和第二子区域22内均包括一层扩展填充光栅层，第三子区域23内包括三层层叠的扩展填充光栅层(231、232、233)；第一子区域21和第二子区域22的扩展填充光栅层，设置为将不同视场角范围的图像光束，沿不同方向部分偏转向第二光栅区域2传播；第三子区域23的扩展填充光栅层，设置为将不同视场角范围的图像光束向两侧扩展后再偏转向第二光栅区域2传播，最终使得多个部分视场均可更均匀地覆盖整个第二光栅区域2。
扩展光栅区域20在进行光束扩展时，可分三部分视场进行扩展传播，一部分视场经耦入光栅区域10耦入进波导基底400后，沿第一路径P1的方向传播，后经第一子区域21部分偏转向耦出光栅区域30的一侧；一部分视场，经耦入光栅区域10耦入进波导基底400后，沿第一路径P2的方向传播，后经第二子区域22部分偏转向耦出光栅区域30的一侧；一部分视场，经第三子区域23同时向两侧扩展并行进至耦出光栅区域30，最终多个部分视场均可更均匀地覆盖整个耦出光栅区域30，采用如图3-图4所示的光栅布置，具有较大图像视场角(FOV)。三部分视场中两两的交集可以不为空，且三部分视场的并集为全视场，以保证在全视场范围内的光束都能有效耦出。
作为一种可行的实施方式，耦入光栅区域10包括一层耦入填充光栅层11，耦入填充光栅层11设置为将图像源出射的图像光束耦入波导基底400；第二光栅区域2包括三层堆叠的耦出填充光栅层(31、32、33)，三层耦出填充光栅层设置为将从不同方向传输至第二光栅区域的传播光束耦出波导基底400。
图19为图3中图像光束的(K空间)波矢空间图。耦入光栅区域10的光栅矢量为K10，第一子区域21的光栅矢量为K21，第二子区域22的光栅矢量为K22，第三子区域23的光栅矢量为K231、K232、K233，耦出光栅区域30的光栅矢量为K31、K32、K33。图19中(a)为图3中图像光束耦入波导基底的(K空间)波矢空间图，图19中(b)为图3中图像光束在波导基底中传播并耦出的(K空间)波矢空间图，通过合理设计耦入光栅区域10、扩展光栅区域20和耦出光栅区域30内的多个填充光栅层的光栅周期和光栅矢量方向，使得图像光束从耦入到耦出所经过衍射的光栅矢量的矢量之和为零，确保图像源出射的图像光束能够耦出波导基底400进入用户眼睛，且基本无色散。例如，结合图3和图16，K10的方向为第三方向，第三方向为从第一光栅区域1指向第二光栅区域2的方向；K21的方向与第三方向的反方向的夹角为60°，K22方向与第三方向的反方向的夹角为-60°，K231、K232、K233的矢量方向分别为第三方向的反方向的夹角为-60°、0和60°的方向；耦出填充光栅层的光栅矢量与第三子区域内的扩展填充光栅层的光栅矢量相同。从该图中可看出经光栅矢量K21作用后一部分视场FOV1偏转向耦出光栅区域30的一侧继续在波导内全反射传播，经光栅矢量K22作用后另一部分视场FOV2偏转向耦出光栅区域30的一侧继续在波导内全反射传播，其中，FOV1∪FOV2＝FOVall，可以确保最终的输出不会存在视场角缺失。例如，视场角DIR1的光束经K10作用耦入波导基底后以角度DIR2在波导基底内全反射传播，行进至第一子区域21经K21作用后向右偏折，以角度DIR3在波导基底内全反射传播，行进至耦出光栅区域30后经K231作用有效耦出。另一部分光束以角度DIR2在波导基底内全反射传播，行进耦出光栅区域30后经K231作用衍射为具有角度DIR4的光束，根据K域图可知该部分光束已无法在波导基底内全反射。但由于该部分光束行进路径偏离该视场角对应的有效耦出光栅区域，也不影响最终性能。因此，波导表面的光栅架构可以通过合理的光栅周期和光栅方向设计使得FOV在K域上得以拼接扩展，以实现增大视场角的功能。图2所示的结构也能实现视场角拼接扩展。
在上述实施例的基础上，作为一种可行的实施方式，通过调制耦入填充光栅层的参数，可以使得耦入填充光栅层能将多个波长甚至全波段的图像光束耦入波导基底。作为一种可行的实施方式，也可以增加耦入填充光栅层的层数，多层耦入填充光栅层协同，将多个波长甚至全波段的图像光束耦入波导基底。参考图18，耦入光栅区域10内包括至少两层耦入填充光栅层(11、12)，两层耦入填充光栅层协同设置为将多个波长甚至全波段的图像光束耦入波导基底。
需要说明的是，在增加一层(或多层)光栅矢量方向相同的耦入填充光栅层时，不改变原来的光束传播方向，但耦入波导基底的图像光束的波段增宽，从而提供全彩单片AR波导。当然，增加的耦入填充光栅层可以是另外的光栅矢量方向，这样还能获得多个耦入传播方向，类似图2所示的耦入光栅结构。
综上，在本申请中，将填充光栅结构应用到具体的衍射光波导的光栅布局中，在耦入阶段采用多层不同光栅方向的填充光栅层，将图像源出射的图像光束耦入波导基底后沿不同的方向传播；在扩展阶段采用多区域、单层或多层不同光栅方向的填充光栅层，将耦入波导基底的图像光束沿不同的方向扩展传输；既提高了光能利用率，又通过将光束从多个方向传播至后续光栅提高图像全幅面亮度均匀性，而且能够加宽耦入波导基底的图像光束的波段，还能通过设计不同方向的传播光束携带不同的图像信息，通过视场角的拼接获取更大的视场角范围。而且，耦入区域采用填充光栅结构也能一定程度上加宽耦入波导基底的图像光束的波段。此外，填充光栅结构在应用于不同的功能区域时在优化性能时调制灵活度更高。不仅能调制光栅基底还能调制填充层。在应用于耦入光栅区域时，能够通过调制增大图像光束耦入波导基底的耦入效率，以及加宽图像光束耦入波导基底的波段。在应用于扩展光栅区域和/或耦出光栅区域时，能够通过调制补偿光束传播衰减，提高扩瞳、耦出图像的均匀性。
以下，在上述实施例的基础上，对填充光栅结构的参数调制进行阐述。对填充光栅结构的参数调制包括对光栅基底的参数调制和填充层的参数调制。
可选地，耦入光栅区域10/100的填充光栅结构50的参数为第一调制变量，该第一调制变量被调制用于增大图像源出射的图像光束耦入波导基底400的耦入效率。扩展光栅区域20/200和耦出光栅区域30/300的填充光栅结构的参数为第二调制变量，该第二调制变量被调制用于调制光栅衍射效率，以提高观测者在动眼眶内多个可观测角度下观测到的图像画面的亮度均匀性。
可选的，第一调制变量包括但不限于耦入光栅区域10/100的填充光栅结构的光栅基底的折射率、齿形、倾角、周期、占空比和深度以及填充层的折射率。
需要说明的是，对第一调制变量进行调制可以是对前述参数中的至少一种进行调制。在耦入光栅区域内的填充光栅结构为多层结构时，对第一调制变量进行调制可以是对至少一层填充光栅层的前述参数中的至少一种进行调制。
该第一调制变量还被调制用于增宽图像源出射的图像光束耦入波导基底400的耦入波段，实现全彩耦入。
可选的，第二调制参数包括但不限于扩展光栅区域20/200和耦出光栅区域30/300的填充光栅结构的光栅基底的折射率、齿形、倾角、周期、占空比和深度以及填充层的折射率；第二调制参数被调制使得同一功能区域内沿光束传播方向的衍射效率逐渐增大；其中，对第二调制参数的调制包括对同一功能区域内的同一层填充光栅层的分区调制。在扩展光栅区域和耦出光栅区域内的参数调制，不仅包括类似耦入光栅区域的参数调制，还包括对同一功能区域内的同一层填充光栅层的分区调制。分区调制包括光栅基底的分区调制和填充层的分区调制，也就是在扩展光栅区域和耦出光栅区域内进行分区，在不同的区域采用不同参数的光栅基底，采用不同折射率的材料用作填充层而产生调制。
可以理解的是，图像光束耦入后，随着传播能量逐渐衰减，为了均匀地扩展或者耦出光束，保障图像均匀性和避免能量浪费，可以通过对填充层进行分区调制实现。图20示出了一个实施例中扩展光栅区域内填充光栅结构的填充层分区调制的示意图。从该图中可以看出，在靠近耦入光栅区域10的区域选用的相对折射率差较小的材料用作填充层，获得相对较低的衍射效率，而在远离光栅区域10的区域选用折射率差较大的材料用作填充层，获得相对较高的衍射效率，随着光束的传播逐渐提高衍射效率，以调制波导中传播光束的强度的均匀性。
可选地，还可以通过对扩展光栅区域20/200和耦出光栅区域30/300的基底光栅的占空比或者深度渐变调制，随着光束的传播逐渐提高衍射效率。通常，当光栅基底的折射率n1与填充层的折射率n2的折射率差值绝对值逐渐减小，优化后所得的光栅基底的深度h会越大，所得到的衍射效率会越高，光束对应入射角度范围会减小；而当光栅基底的折射率n1与填充层的折射率n2的折射率差值绝对值逐渐增大，优化后所得的光栅基底的深度h会越小，所得到的衍射效率会降低，光束对应入射角度范围会增大；而光栅基底的占空比F在偏离优化最佳值后，光栅的衍射效率会逐渐降低，并且最佳入射角范围会发生漂移，光栅基底的斜角α则根据应用波长、角度进行优化。基于此，在确定光栅基底与填充层的材料后，通过优化平衡衍射效率与角度相应带宽选定光栅深度、周期以及光栅倾斜角后，再对光栅的占空比进行调制，可以达到有效调制波导中传播光束的强度的均匀性。
示例性地，在一个实施例中，入射光波长为532nm，光栅周期为400nm，光栅基底的结构为斜齿，光栅斜角为62°，光栅周期为400nm，光栅深度为1.25μm，材料为TiO2，填充层的材料为SiO2。通过调节斜齿光栅的占空比，可以调制出不同衍射效率，光栅基底占空比在55％～65％之间进行渐变调制，光栅衍射效率可在15～80％的范围调节。基于此，将该调制方式应用到衍射光波导的扩瞳光栅区域，可以提高衍射光波导的扩瞳效率及均匀性。
示例性地，在一个实施例中，入射光波长为625nm，光栅基底的结构为斜齿，光栅斜角为58.8°，光栅周期为450nm，深度为3.12μm，光栅基底的材料为折射率为1.8的丙烯酸树脂，填充层的材料为折射率为1.45的环氧树脂，通过调节斜齿光栅的占空比，可以调制出不同衍射效率。光栅基底占空比在53％～75％之间进行渐变调制，光栅衍射效率可在10～90％的范围调节。基于此，将该调制方式应用到衍射光波导的扩瞳光栅区域，可以提高衍射光波导的扩瞳效率及均匀性。
以下，在上述实施例的基础上，对填充光栅结构进行阐述。
图21为本申请实施例提供的一种光栅基底的齿形结构的示意图。在上述实施例的基础上，可选的，光栅基底的齿形结构包括但不限于直齿结构、斜齿结构、梯形结构、三角结构、台阶结构中的至少一种。
需要说明的是，衍射光波导的光栅设计中，根据需求选用直齿结构、斜齿结构、梯形结构、三角结构、台阶结构中的至少一种均可。例如，在耦入光栅区域中采用斜齿结构，可以提高耦入效率；在扩展光栅区域中采用直齿结构或者小角度斜齿结构，可以均衡整个区域衍射效率均匀性。
在上述实施例的基础上，可选的，光栅基底的结构包括一维凸起条状光栅结构、二维交叉凸起条状光栅结构、二维交叉条状的凹陷阴模光栅结构。光栅基底的结构可以采用多种刻蚀工艺制备，在一维凸起条状光栅结构、二维交叉凸起条状光栅结构、二维交叉条状的凹陷阴模光栅结构上覆盖填充层形成填充光栅结构，制备工艺简单，易实现。
在上述实施例的基础上，可选的，光栅基底与填充层的材料包括有机材料和透明无机材料。例如，光栅基底和填充层的材料可以为环氧树脂、丙烯酸类等有机材料，或者a-Si，TiO2、Nb2O5，SiN，SiO2、MgF2等透明无机材料。
在上述实施例的基础上，可选的，光栅基底与填充层的折射率差值范围为Δn，0.01≤Δn≤1.4。合理设置光栅基底与填充层的折射率差值范围，可以提高填充光栅结构的衍射效率。
在上述实施例的基础上，可选的，填充光栅结构的工作方式包括透射光栅模式和反射光栅模式。填充光栅结构可以为透射式光栅或者反射式光栅。
综上，采用相互堆叠的多层填充光栅层的光栅结构，每层填充光栅层内的光栅结构可以自由灵活设置，这样可以构建多层不同光栅方向或者不同光栅齿的倾斜方向等的立体状叠合结构，一方面可以使多层填充光栅结构分别将图像光束引导向所需特定角度的一侧，多层填充光栅层叠加便可提供沿着光波导的多个方向传播的图像光束，提高图像全幅面亮度均匀性，提高多个允许观看角度下的画面亮度均匀性；另一方面也可以使多层填充光栅层分别耦入不同波段的光束，多层填充光栅层叠加便可用于RGB三色的均衡，提供全彩单片AR波导的设计灵活性，并且在实现全彩显示时，也能够提高多个允许观看角度下的多个颜色画面的亮度均匀性；再一方面，多层填充光栅层的叠加使得0级衍射光可以被再次衍射利用，增大光能利用率，此外，每层填充光栅层可以进行光栅效率调制，这样可以进一步提高光栅效率调制的灵活性，获得更高的衍射效率以及更大的视场角范围。
基于同一个发明构思，本申请实施例还提供了一种衍射光波导的设计方法，用于设计上述实施例提供的衍射光波导。该设计方法包括如下步骤。
S11、提供波导基底。
S12、在波导基底的第一光栅区域形成第一光栅结构，以及在第二光栅区域形成第二光栅结构。
采用压印或者刻蚀的方式，在波导基底的第一光栅区域制备第一光栅结构，以及在第二光栅区域制备第二光栅结构。
第一光栅结构，设置为将图像源出射的图像光束耦入波导基底形成沿不同方向传播的传播光束；或者，设置为衍射耦入波导基底的图像光束形成沿不同方向传播的传播光束；第二光栅结构设置为衍射所述传播光束形成输出光束。
图像光束自从第一光栅区域耦入所述波导基底至从第二光栅区域耦出波导基底所经过衍射光栅的光栅矢量之和基本为零。
需要说明的是，本申请实施例提供的一种衍射光波导的设计方法制备得到的衍射光波具备上述实施例提供的结构。
在上述实施例的基础上，可选的，第一光栅结构和第二光栅结构包括填充光栅结构，填充光栅结构包括一层填充光栅层；填充光栅层包括光栅基底和填充层，填充层设置为填充光栅基底之间的间隙并形成平整光滑的表面；光栅基底和填充层的折射率不同。
步骤S11包括如下步骤。
S111、采用压印或者刻蚀的方式，在波导基底的第一光栅区域形成第一光栅基底，以及在第二光栅区域形成第二光栅基底。
结合图22所示，针对光栅基底的加工，对于不同的光栅基底材料可以形成不同的加工路径。针对树脂类材料，本申请采用压印路径进行加工，通过对事先加工好的母板进行翻模，对涂有固化胶的基底进行压印、固化、脱模，得到与母板结构一致的光栅基底结构。针对TiO2、SiO2、MgF2等材料，可以将所需光栅材料镀膜在基底片上，然后对基底片进行旋涂光刻胶、显影、掩膜光刻、刻蚀，最终得到光栅基底结构。
S112、采用固化或者镀膜的方式，在第一光栅基底上形成第一填充层得到填充光栅结构，以及在第二光栅基底上形成第二填充层得到填充光栅结构。
结合图23所示，针对填充层的加工，也有两条工艺路径，一条是常规的镀膜路径，主要针对设计的常规光学镀膜材料进行填充，如Au、Ag、Al、MgO、SiO2、MgF2、CaF2等，所使用的工艺为蒸发、溅射。另一条路径是使用固化材料进行填充，我们需要先对树脂进行稀释，降低树脂的粘稠度，使其能够更充分的渗透进入填充光栅的结构内部，然后对稀释后的树脂进行旋涂，令其布满整个波导片，接着对波导片进行烘烤，使稀释剂挥发，并抽真空，彻底排出光栅基底内气泡，使树脂填充更加充分，最后对树脂进行曝光固化，完成材料填充，得到填充光栅结构。本申请中涉及的固化包括热固化和紫外(Ultraviolet Curing，UV)固化。
在上述实施例的基础上，可选的，第一光栅结构和/或第二光栅结构包括填充光栅结构，填充光栅结构包括多层堆叠的填充光栅层；多层堆叠的填充光栅层通过多层单层填充光栅层对准叠加得到。结合图24所示，在每制备一层填充光栅层后，进行对准再在其上制备下一层填充光栅层。
[根据细则91更正 11.07.2023]
在优化光栅参数的过程中，可以通过加深光栅的深度来达到较高的衍射效率。比如：在入射光波长为532nm，光栅周期为400nm，光栅基底光栅结构为斜齿，材料为折射率为1.7的丙烯酸树脂，填充光栅材料结构为折射率为1.5的环氧树脂，光栅斜角为26.8°，占空比为80％的参数条件下，光栅深度为2μm时，光栅效率约为23％，光栅深度增大至6μm时，光栅效率提升至97％。但是在实际的生产工艺中，在光栅超过微米级深度后，加工难度会随设计深度的增加而增大，而且还会带来视场角范围的限制。本申请，通过多层光栅叠加来达到相应的光栅深度，能实现较佳的衍射效果。而且，填充光栅结构可以由多层不同形状基底光栅、填充材料构成，通过多层填充光栅的叠加，可以进一步提高光栅效率调制的灵活性，获得更高的衍射效率以及更大的视场角范围。结合图8和图10所示，通过两层填充光栅叠加可在-23°～10°的大视场角范围内均获得63～87％的衍射效率。
另外，通过多层填充光栅的组合，还降低了单次母版加工的难度，可以实现类似曲面的结构侧壁，以及常规半导体工艺难以加工的结构形状，得以实现更为复杂的光栅功能，可进一步扩大视场角。
多层填充光栅结构的加工可以依赖上面介绍的基底光栅制作路径以及填充材料路径的组合，在完成一层的填充结构后，通过高精度对准，将上层光栅结构覆盖在其表面，从而给设计和生产工艺提供巨大灵活性。
基于同一个发明构思，本申请实施例还提供了一种增强现实设备，增强现实设备包括设备主体、光机及本申请所提供的衍射光波导，光机和衍射光波导被对应地设置于设备主体，使得经由光机提供的图像光束被衍射光波导的耦入光栅结构耦入进波导基底，并在波导基底内全反射地传播至扩展光栅区域和/或耦出光栅区域，被耦出光栅结构耦出波导基底而被用户眼睛接收以看到对应的图像。
在一种实施方式中，增强现实设备被实现为近眼现实设备，设备主体被实施为眼镜架，眼镜架包括横梁部和镜腿部，并且镜腿部从横梁部的左右两侧中的至少一侧向后延伸，衍射光波导被对应地设置于横梁部。对于侧投显示结构，近眼显示设备中提供图像光束的光机被对应地设置于波导基底的侧上位置，以将光机直接安装至近眼显示设备的镜腿部内，使得光机被隐藏在镜腿部内，有助于使整个设备显得更加轻巧，更加贴合人的审美。对于中上投显示结构，光机适于被安装于设备主体的横梁部，使得当用户佩戴近眼显示设备时，光机对应地位于用户的额头附近，有助于为光机预留更大的安装空间。
在一种实施方式中，增强现实设备被实现为平视显示器(Head Up Display，HUD)，设备主体被实施为挡风玻璃，并且衍射光波导被对应地设置于挡风玻璃的内侧，使得经由光机投射的图像光束在经由衍射光波导的传输后，投射至挡风玻璃，并经由挡风玻璃向内反射以进入入眼，使得用户能够看到较远距离外的虚像。或者，衍射光波导被对应地设置于挡风玻璃的内部，使得经由光机投射的图像光束在经由衍射光波导的传输耦出后，直接被用户眼睛接收以看到对应的图像。可以理解的是，增强现实设备中的挡风玻璃可以但不限于被实施为诸如飞机、汽车等运输工具的前挡风玻璃，增强现实设备还被实施为增强现实平视显示器(Augmented Reality-Head Up Display，AR-HUD)。
本申请提供的衍射光波导提高了光能利用效率以及耦出均匀性。不再需要像配置有普通衍射光波导的车载HUD那样，为了弥补光能利用率较低以在足够大的眼盒内提供强度较大的图像光线，不得不大幅地增大光机的投射功率，导致光机因功率较大而难以散热。换言之，本申请的增强现实设备只需要使用功率较小的光机，就能够在挡风玻璃前形成高对比度和高质量的虚像，供用户观看。

Claims (20)

  1. 一种衍射光波导，包括波导基底以及位于所述波导基底表面的第一光栅区域和第二光栅区域；
    所述第一光栅区域内的光栅结构，设置为以下至少之一：将图像源出射的图像光束耦入所述波导基底形成沿不同方向传播的传播光束；衍射耦入所述波导基底的图像光束形成沿不同方向传播的传播光束；
    所述第二光栅区域内的光栅结构，设置为衍射所述传播光束形成输出光束。
  2. 根据权利要求1所述的衍射光波导，其中，所述第一光栅区域的光栅结构和所述第二光栅区域内的光栅结构中的至少之一包括填充光栅结构，所述填充光栅结构包括至少一层填充光栅层；所述至少一层填充光栅层中的每层填充光栅层包括光栅基底和填充层，所述填充层设置为填充所述光栅基底之间的间隙并在所述填充光栅结构远离所述波导基底的一侧形成平整光滑的表面；所述光栅基底和所述填充层的折射率不同。
  3. 根据权利要求2所述的衍射光波导，其中，所述第一光栅区域包括耦入光栅区域和扩展光栅区域，所述耦入光栅区域的光栅结构为填充光栅结构，所述填充光栅结构包括至少两层堆叠的耦入填充光栅层；
    所述至少两层耦入填充光栅层中的每层耦入填充光栅层，设置为将所述图像源发出的图像光束耦入所述波导基底并形成沿不同方向传播的传播光束；
    所述扩展光栅区域的光栅结构设置为衍射所述传输光束，使得所述传输光束部分偏转向所述第二光栅区域传播。
  4. 根据权利要求3所述的衍射光波导，其中，所述耦入光栅区域的光栅结构的填充光栅结构包括三层堆叠的耦入填充光栅层；所述三层耦入填充光栅层设置为将所述图像源发出的图像光束耦入所述波导基底并形成分别沿第一方向、第二方向和第三方向传播的传播光束；所述第三方向为从所述第一光栅区域指向所述第二光栅区域的方向，沿所述第三方向的传播光束直接传播至所述第二光栅区域，所述第一方向和所述第二方向分别与所述第三方向的夹角均为锐角，所述第一方向、所述第二方向和所述第三方向位于同一平面内；
    所述扩展光栅区域包括第一扩展光栅区域和第二扩展光栅区域，所述第一扩展光栅区域设置为衍射沿所述第一方向传播的传播光束，使得沿所述第一方向传播的传播光束部分偏转向所述第二光栅区域传播；所述第二扩展光栅区域设置为衍射沿所述第二方向传播的传播光束，使得沿所述第二方向传播的传播光束部分偏转向所述第二光栅区域传播。
  5. 根据权利要求4所述的衍射光波导，其中，所述第一扩展光栅区域包括 第一甲扩展光栅区域和第一乙扩展光栅区域；所述第二扩展光栅区域包括第二甲扩展光栅区域和第二乙扩展光栅区域；
    所述第一甲扩展光栅区域设置为衍射沿所述第一方向传播的传播光束，使得沿所述第一方向传播的传播光束部分偏转向所述第二光栅区域传播；所述第一乙扩展光栅区域设置为衍射继续沿所述第一方向传播的传播光束，使得继续沿所述第一方向传播的传播光束部分偏转向所述第二光栅区域传播；
    所述第二甲扩展光栅区域设置为衍射沿所述第二方向传播的传播光束，使得沿所述第二方向传播的传播光束部分偏转向所述第二光栅区域传播；所述第二乙扩展光栅区域设置为衍射继续沿所述第二方向传播的传播光束，使得继续沿所述第二方向传播的传播光束部分偏转向所述第二光栅区域传播。
  6. 根据权利要求3所述的衍射光波导，其中，所述耦入光栅区域的光栅结构的填充光栅结构包括三层堆叠的耦入填充光栅层；
    所述三层耦入填充光栅层设置为将所述图像源发出的第一波段的图像光束、第二波段的图像光束以及第三波段的图像光束分别耦入所述波导基底并形成传输光束；所述第一波段的图像光束的中心波长为λ1，所述第二波段的图像光束的中心波长为λ2，所述第三波段的图像光束的中心波长为λ3，λ1>λ2>λ3；或者，所述三层耦入填充光栅层中的其中两层耦入填充光栅层设置为将所述图像源发出的第一、二波段的图像光束和第二、三波段的图像光束分别耦入所述波导基底并形成传输光束，所述三层耦入填充光栅层中的另外一层设置为对所述两层耦入填充光栅层中耦入不足或缺失的波段进行补偿。
  7. 根据权利要求2所述的衍射光波导，其中，所述第一光栅区域包括耦入光栅区域和扩展光栅区域，所述扩展光栅区域包括至少两个子区域，所述至少两个子区域中的每个子区域内包括至少一层扩展填充光栅层，不同子区域的扩展填充光栅层，设置为将耦入所述波导基底的、不同视场角范围的图像光束，部分偏转向所述第二光栅区域传播。
  8. 根据权利要求7所述的衍射光波导，其中，所述扩展光栅区域包括第一子区域和第二子区域，所述第一子区域与所述第二子区域分别位于所述波导基底的上表面和下表面且存在重叠区域，所述第一子区域和所述第二子区域内均包括至少一层扩展填充光栅层，不同子区域的扩展填充光栅层，设置为将耦入所述波导基底的、不同视场角范围的图像光束，部分偏转向所述第二光栅区域传播。
  9. 根据权利要求7所述的衍射光波导，其，所述扩展光栅区域包括第一子 区域、第二子区域和第三子区域，所述第三子区域位于所述第一子区域和所述第二子区域之间；所述第一子区域和所述第二子区域内包括一层扩展填充光栅层，所述第三子区域内包括三层层叠的扩展填充光栅层；
    所述第一子区域的一层扩展填充光栅层和所述第二子区域的一层扩展填充光栅层，设置为将耦入所述波导基底的、不同视场角范围的图像光束，沿不同方向部分偏转向所述第二光栅区域传播；所述第三子区域的三层扩展填充光栅层，设置为将耦入所述波导基底的、不同视场角范围的图像光束向两侧扩展后再偏转向所述第二光栅区域传播。
  10. 根据权利要求7所述的衍射光波导，其中，所述耦入光栅区域包括至少两层耦入填充光栅层，所述两层耦入填充光栅层的光栅矢量方向相同，所述两层耦入填充光栅层设置为将所述图像源出射的多波段的图像光束耦入所述波导基底形成传播光束。
  11. 根据权利要求2-10中任一项所述的衍射光波导，其中，所述第一光栅区域包括耦入光栅区域和扩展光栅区域，所述第二光栅区域包括耦出光栅区域，所述耦入光栅区域的填充光栅结构的参数为第一调制变量，用于增大所述图像源出射的图像光束耦入所述波导基底的耦入效率；所述扩展光栅区域的填充光栅结构的参数和所述耦出光栅区域的填充光栅结构的参数均为第二调制变量，用于调制光栅衍射效率，以提高观测者在动眼眶内多个可观测角度下观测到的图像画面的均匀性。
  12. 根据权利要求11所述的衍射光波导，其中，所述第一调制变量包括所述耦入光栅区域的填充光栅结构的光栅基底的折射率、齿形、倾角、周期、占空比和深度，以及所述耦入光栅区域的填充光栅结构的填充层的折射率中的至少一种。
  13. 根据权利要求11所述的衍射光波导，其中，所述第二调制参数包括所述扩展光栅区域和所述耦出光栅区域的填充光栅结构的光栅基底的折射率、齿形、倾角、周期、占空比和深度，以及所述扩展光栅区域和所述耦出光栅区域的填充光栅结构的填充层的折射率中的至少一种；所述第二调制参数被调制使得同一功能区域内沿光束传播方向的衍射效率逐渐增大；其中，对所述填充层的折射率的调制包括对所述同一功能区域内的同一层填充层的分区调制。
  14. 根据权利要求11所述的衍射光波导，其中，所述光栅基底与所述填充层的折射率差值范围为Δn，0.01≤Δn≤1.4。
  15. 一种衍射光波导的制备方法，包括：
    提供波导基底；
    在所述波导基底的第一光栅区域形成第一光栅结构，以及在第二光栅区域形成第二光栅结构；
    其中，所述第一光栅结构，设置为以下至少之一：将图像源出射的图像光束耦入所述波导基底形成沿不同方向传播的传播光束；衍射耦入所述波导基底的图像光束形成沿不同方向传播的传播光束；所述第二光栅结构设置为衍射所述传播光束形成输出光束。
  16. 根据权利要求15所述的方法，其中，所述第一光栅结构和所述第二光栅结构均包括填充光栅结构，所述填充光栅结构包括一层填充光栅层；所述一层填充光栅层包括光栅基底和填充层，所述填充层设置为填充所述光栅基底之间的间隙并形成平整光滑的表面；所述光栅基底和所述填充层的折射率不同；
    所述在所述波导基底的第一光栅区域形成第一光栅结构，以及在第二光栅区域形成第二光栅结构，包括：
    采用压印或者刻蚀的方式，在所述波导基底的所述第一光栅区域形成第一光栅基底，以及在所述第二光栅区域形成第二光栅基底；
    采用固化或者镀膜的方式，在所述第一光栅基底上形成第一填充层得到填充光栅结构，以及在第二光栅基底上形成第二填充层得到填充光栅结构。
  17. 根据权利要求15所述的方法，其中，所述第一光栅结构和所述第二光栅结构中的至少之一包括填充光栅结构，所述填充光栅结构包括多层堆叠的填充光栅层；所述多层堆叠的填充光栅层通过多层单层填充光栅层对准叠加得到。
  18. 一种增强现实设备，包括：
    设备主体；
    光机，其中，所述光机被设置于所述设备主体，所述光机中的图像源设置为投射图像光束；以及权利要求1-14项中任一项所述的衍射光波导。
  19. 根据权利要求18所述的增强现实设备，其中，所述增强现实设备实现为近眼显示设备，其中，所述设备主体被实施为眼镜架，其中所述眼镜架包括横梁部和镜腿部，并且所述镜腿部从所述横梁部的左右两侧中的至少一侧向后延伸，其中所述衍射光波导被对应地设置于所述横梁部。
  20. 根据权利要求18所述的增强现实设备，其中，所述增强现实设备实现为抬头显示设备，所述设备主体被实施为挡风玻璃，所述衍射光波导被对应地设置于所述挡风玻璃的内部或者内侧，使得经由所述光机投射的图像光束在经由所述衍射光波导的传输后，投射至所述挡风玻璃以形成虚像。
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