Optical device and display device

Abstract

The application relates to an optical device and a display device, the optical device comprising a waveguide plate, on which an entrance pupil grating unit, a left pupil expansion grating unit located on the left side of the entrance pupil grating unit, a right pupil expansion grating unit located on the right side of the entrance pupil grating unit, the left and right pupil expansion grating units being mirror-symmetrical to each other with the entrance pupil grating unit as the center, left and right exit pupil grating units located below the left and right pupil expansion grating units and also being mirror-symmetrical to each other are formed; input light is diffracted by the entrance pupil grating unit to form first left and right conducting lights, the first left conducting light is diffracted by the left pupil expansion grating unit to form second left conducting light, and the first right conducting light is diffracted by the right pupil expansion grating unit to form second right conducting light; the second left conducting light is diffracted by the left exit pupil grating unit to form left output light; and the second right conducting light is diffracted by the right exit pupil grating unit to form right output light; the directions of the input light, the left output light and the right output light are consistent. The application can realize binocular display through waveguide and can improve color uniformity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of waveguide, and particularly relates to an optical device and a display device. BACKGROUND

[0002] Near-eye display technology is one of the key technologies that must be used in current AR glasses. A near-eye display system is generally composed of an image far and an optical transmission system. The image picture emitted by the image source is transmitted to the human eye through the optical transmission system. The optical transmission system here needs to have a certain transmittance, so that the wearer can see the outside environment while seeing the image picture.

[0003] For the optical transmission system, there are many schemes in the industry, such as free-space optics, free-form surface optics, and display optical waveguide. Among them, the optical waveguide technology has obvious advantages over other optical solutions due to its large eyebox and light and thin characteristics. However, the current optical waveguide can only realize monocular display, and there are problems of high hardware cost and high power consumption to realize binocular display. SUMMARY

[0004] The application provides an optical device and a display device to solve the problem that the current optical waveguide can only realize monocular display.

[0005] To solve the above technical problems, the application provides an optical device, which comprises a waveguide plate, and the waveguide plate is formed with: an entrance pupil grating unit, through which input light diffracts to form first left and right transmission lights; a left pupil expansion grating unit located on the left side of the entrance pupil grating unit; the first left transmission light diffracts through the left pupil expansion grating unit to form second left transmission light; a right pupil expansion grating unit located on the right side of the entrance pupil grating unit; the first right transmission light diffracts through the right pupil expansion grating unit to form second right transmission light; a left exit pupil grating unit located on the lower side of the left pupil expansion grating unit; the second left transmission light diffracts through the left exit pupil grating unit to form left output light; a right exit pupil grating unit located on the lower side of the right pupil expansion grating unit; the second right transmission light diffracts through the right exit pupil grating unit to form right output light; the left and right pupil expansion grating units are mirror-symmetrically arranged on the left and right sides of the entrance pupil grating unit, and the left and right exit pupil grating units are mirror-symmetrically arranged on the left and right sides of the entrance pupil grating unit, and the directions of the input light, the left output light and the right output light are consistent.

[0006] In one embodiment, the entrance pupil grating unit is a surface grating or a holographic volume grating, the entrance pupil grating unit is circular, the diameter is 2.5mm-7mm, and the grating period of the entrance pupil grating unit is 330nm-450nm.

[0007] In one embodiment, the left pupil expansion grating unit and the right pupil expansion grating unit are both pupil expansion grating structures, and the height of the pupil expansion grating structure in the vertical direction gradually increases in the direction away from the entrance pupil grating unit; the maximum height of the pupil expansion grating structure in the vertical direction is 2-5 times the diameter of the entrance pupil grating unit, and the width in the horizontal direction is 5-10 times the diameter of the entrance pupil grating unit.

[0008] In one embodiment, the pupil expansion grating structure is divided into 5-15 sub-pupil expansion regions, and the angle between the boundary line between adjacent sub-pupil expansion regions and the horizontal direction is 20-160 degrees; in the direction away from the entrance pupil grating unit, the diffraction efficiency of each sub-pupil expansion region gradually increases, and the diffraction efficiency of the sub-pupil expansion region is 5%-95%.

[0009] In one embodiment, the left exit pupil grating unit and the right exit pupil grating unit are both exit pupil grating structures, and the exit pupil grating structure is rectangular, with a height in the vertical direction of 3-6 times the diameter of the entrance pupil grating unit and a width in the horizontal direction of 80%-95% of the width of the pupil expansion grating structure.

[0010] In one embodiment, the exit pupil grating structure is divided into 5-15 sub-exit pupil regions in the vertical direction, and the diffraction efficiency of each sub-exit pupil region gradually increases in the direction away from the entrance pupil grating unit, and the diffraction efficiency of the sub-exit pupil region is 5%-95%.

[0011] In one embodiment, the pupil expansion grating structure is quadrilateral, and the four corners of the pupil expansion grating structure and the four corners of the exit pupil grating structure are both arc-shaped, with a curvature radius of 0-20 mm.

[0012] In one embodiment, the horizontal distance between the center of the left exit pupil grating unit and the center of the right exit pupil grating unit is the interpupillary distance of the human eye, which is 60-70 mm; and the vertical distance between the center of the entrance pupil grating unit and the center of the left exit pupil grating unit is 8-25 mm.

[0013] In one embodiment, with the left-to-right direction as the reference, the grating vector direction of the entrance pupil grating unit is -1-1 degree, the grating vector direction of the left pupil expansion grating unit is 30-60 degrees, the grating vector direction of the right pupil expansion grating unit is 120-150 degrees, the grating vector direction of the left exit pupil grating unit is 88-92 degrees, and the grating vector direction of the right exit pupil grating unit is 88-92 degrees.

[0014] In one embodiment, in the wave vector space, the wave vector regions of the left output light, the right output light and the input light coincide, the wave vector regions of the first left conducting light and the first right conducting light, the second left conducting light and the second right conducting light are between the total internal reflection minimum wave vector and the total internal reflection maximum wave vector of the waveguide plate, and the wave vector regions of the second left conducting light and the second right conducting light coincide.

[0015] In one embodiment, the grating vector of the entrance pupil grating unit is in the left direction, and the sum of the grating vectors of the entrance pupil grating unit, the left pupil expansion grating unit and the left exit pupil grating unit is zero; the grating vector of the entrance pupil grating unit is in the right direction, and the sum of the grating vectors of the entrance pupil grating unit, the right pupil expansion grating unit and the right exit pupil grating unit is zero.

[0016] To solve the above technical problems, the application further provides a display device, comprising a light engine and the above optical device; the light engine is used to generate the input light.

[0017] Differing from the prior art, the optical device of the application has an entrance pupil grating unit formed on the waveguide plate, which diffracts the input light into left and right conducting light by using positive and negative diffraction orders; the same waveguide plate also has left and right symmetrical pupil expansion grating units and left and right symmetrical exit pupil grating units, which can realize binocular display. Since the waveguide plate is an integral whole, it has basic flatness, and the left and right eyes can realize binocular fusion without other additional adjustment. Due to the overall left and right symmetrical relationship, the images of the left and right eyes realize color complementation, thereby realizing better color uniformity and larger FOV. Through the partition of the left and right pupil expansion units and the left and right exit pupil units, better color uniformity is further realized. At the same time, the positive and negative diffraction orders of the entrance pupil unit are all utilized, which greatly improves the utilization of system light energy, so the power consumption of the binocular system is far lower than that of the conventional binocular display scheme. BRIEF DESCRIPTION OF DRAWINGS

[0018] The above and other objects, features and advantages of the exemplary embodiments of the present disclosure will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which several embodiments of the present disclosure are shown by way of example, and wherein like or corresponding elements refer to like or corresponding parts throughout. In the drawings:

[0019] Figure 1 is a structural schematic diagram of an embodiment of the optical device of the application;

[0020] Figure 2 is Figure 1 is a partitioning schematic diagram of the grating units in an embodiment of the optical device shown;

[0021] Figure 3 is Figure 1Vector directions of grating units in an embodiment of the optical device shown;

[0022] Figure 4 is Figure 1 A side view of an embodiment of the optical device shown;

[0023] Figure 5 is Figure 1 A wave vector diagram of light in an embodiment of the optical device shown;

[0024] Figure 6 is a structural schematic diagram of another embodiment of the optical device of the present application. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present disclosure.

[0026] The specific embodiments of the present disclosure will be described in detail below with reference to the drawings.

[0027] As Figure 1 shown, the optical device EPE1 can include a waveguide plate SUB01, which is a plane with good flatness, but the shape of the waveguide plate SUB01 can be a flat plate or a curved plate that fits the face, both of which have good flatness.

[0028] The waveguide plate SUB01 is formed with an entrance pupil grating unit DOE1, a left pupil expansion grating unit DOE2a, a right pupil expansion grating unit DOE2b, a left exit pupil grating unit DOE3a, and a right exit pupil grating unit DOE3b.

[0029] The entrance pupil grating unit DOE1 can receive an input light beam IN1, and the left and right exit pupil grating units DOE3a and DOE3b can provide expanded output light beams OUT1 and OUT2, respectively. Under the action of the left and right pupil expansion grating units DOE2a and DOE2b and the left and right exit pupil grating units DOE3a and DOE3b, the length and width of the output light beams OUT1 and OUT2 are greater than the length and width of the input light beam IN1, achieving the function of pupil expansion.

[0030] The optical device EPE1 can expand the light beam IN1 in two dimensions (e.g., along the horizontal direction SX and along the vertical direction SY). The expansion process can also be referred to as exit pupil expansion, light ray expansion, etc. The optical device EPE1 can be referred to as a beam expander or an exit pupil expander, etc.

[0031] The entrance pupil grating unit DOE1 can be used as an in-coupling unit. The entrance pupil grating unit DOE1 can diffract the input light beam IN1 to form the first left conducting light B1a and the first right conducting light B1b. The input light beam IN1 can be incident from the front surface of the optical device EPE1 or from the back surface of the EPE1. The first left conducting light B1a and the first right conducting light B1b can propagate inside the planar waveguide plate SUB01, and the main directions of propagation are left-right symmetric. The first left conducting light B1a and the first right conducting light B1b can be confined in the planar waveguide plate SUB01 for total internal reflection (TIR).

[0032] The term "conducting" can mean that the light propagates inside the planar waveguide plate SUB01, and the light is confined inside the plate by total internal reflection (TIR). The term "waveguide" can be the same as the term "optical waveguide".

[0033] The left pupil expanding grating unit DOE2a is configured to receive the first left conducting light B1a and diffract the first left conducting light B1a to form the second left conducting light B2a. The left pupil expanding grating unit DOE2a can distribute the second left conducting light B2a to the left exit pupil grating unit DOE3a in a nearly uniform manner, and the light beam width of the second left conducting light B2a is much larger than that of the first left conducting light B1a. The second left conducting light B2a can propagate in the waveguide plate SUB01 by total internal reflection.

[0034] The right pupil expanding grating unit DOE2b is configured to receive the first right conducting light B1b and diffract the first right conducting light B1b to form the second right conducting light B2b. The right pupil expanding grating unit DOE2b can distribute the second right conducting light B2b to the right exit pupil grating unit DOE3b in a nearly uniform manner, and the light beam width of the second right conducting light B2b is much larger than that of the first right conducting light B1b. The second right conducting light B2b can propagate in the waveguide plate SUB01 by total internal reflection.

[0035] The first left conducting light B1a and the first right conducting light B1b are left-right symmetric, and the second left conducting light B2a and the second right conducting light B2b have the same main direction.

[0036] The left exit pupil grating unit DOE3a can diffract the expanded conducting light B2a to form the left output light OB1, which is further expanded in the Y direction and maintains good uniformity, and the left output light OB1 and the left output light beam OUT1 form the left output light beam OUT1 as a whole. The directions of the left output light OB1 and the left output light beam OUT1 are DIR0'.

[0037] The right pupil expanding grating unit DOE3b can diffract the expanded conducting light B2b to form the right output light OB2, which is further expanded in the Y direction and maintains good uniformity, and the whole forms the right output light beam OUT2. The directions of the right output light OB2 and the right output light beam OUT2 are also DIR0'.

[0038] The direction DIR0 of the incident light beam IN1 is consistent with the direction DIR0' of the left and right output light beams OUT1 and OUT2, and this relationship always holds true regardless of the direction of the incident light beam IN1. Since the directions DIR0' of the left and right output light beams OUT1 and OUT2 are the same, the virtual image VIMG1 received by the left eye EYE1 and the virtual image VIMG2 received by the right eye EYE2 can naturally merge together without angular deviation, and the content of the virtual image VIMG1 and the virtual image VIMG2 is exactly the same.

[0039] SX, SY and SZ are orthogonal directions. The waveguide plate SUB1 can be parallel to the plane defined by SX and SY.

[0040] As Figure 2 The partitioning and size of different grating regions of the optical device EPE1 are given. The diameter of the entrance pupil grating unit DOE1 is D1, and the area range of D1 is 2.5mm-7mm. The entrance pupil grating unit DOE1 can be a surface grating or a holographic volume grating, which has a high diffraction efficiency and can propagate the first left conducting light B1a and the first right conducting light B1a to the left and right sides.

[0041] The left pupil expanding grating unit DOE2a is a quadrilateral with a maximum width W2 and a maximum height H2 and the highest left side. The width W2 can be 5-10 times the diameter D1, and the height H2 can be 2-5 times the diameter D1. The angles between the upper and lower edges of the quadrilateral and the horizontal direction are a21 and a22, respectively. The left pupil expanding grating unit DOE2a needs to be further divided into 5-15 sub-pupil expanding regions. Taking 6 regions as an example, the left pupil expanding grating unit DOE2a includes sub-regions L11, L12, L13, L14, L15 and L16, and the angle between the dividing lines of different sub-regions is a23. This angle can be set in the range of 20° to 160°, and the angles between the dividing lines of different adjacent sub-regions can be different to achieve better uniformity. In addition, the grating period in different sub-regions can be fixed, and the shape characteristics, depth, duty cycle or exposure conditions of the grating can be controlled to gradually increase the diffraction efficiency of different sub-regions, i.e. when i is greater than j, the grating diffraction efficiency of the sub-region L1i is greater than that of the sub-region L1j. The efficiency of the corresponding sub-region diffraction grating can be set in the range of 5%-95%.

[0042] The right pupil-expanding grating unit DOE2b is a quadrilateral with a maximum width W4 and a maximum height H4, and the rightmost highest. The width W4 can be 5-10 times the diameter D1, and the height H4 can be 2-5 times the diameter D1. The angles between the upper and lower edges of the quadrilateral and the horizontal direction are b21 and b22, respectively. The right pupil-expanding grating unit DOE2b needs to be further divided into 5-15 sub-pupil-expanding regions. Taking 6 regions as an example, the right pupil-expanding grating unit DOE2b includes sub-regions R11, R12, R13, R14, R15, and R16. The angles of the boundary lines between different sub-regions are b23, which can be set to a range of 20° to 160°, and the angles of the boundary lines between different adjacent sub-regions can be different to achieve better uniformity. In addition, the grating period in different sub-regions can be fixed, the shape characteristics, depth, duty cycle, or exposure conditions of the grating can be controlled, so that the diffraction efficiency of different sub-regions gradually increases, that is, when i is greater than j, the grating diffraction efficiency of the sub-region R1i is greater than that of the sub-region R1j. The efficiency of the diffraction grating of all corresponding sub-regions can be set to a range of 5% to 95%.

[0043] The left pupil-expanding grating unit DOE2a and the right pupil-expanding grating unit DOE2b have the same pupil-expanding grating structure, and the structure size, grating parameters, and partition characteristics must be strictly left-right mirror symmetric, and the diffraction efficiency of each sub-region must also be the same, that is, L1i = R1i.

[0044] The left pupil-expanding grating unit DOE2a and the right pupil-expanding grating unit DOE2b have the same pupil-expanding grating structure, and the structure size, grating parameters, and partition characteristics must be strictly left-right mirror symmetric, and the diffraction efficiency of each sub-region must also be the same, that is, L1i = R1i.

[0045] The right exit pupil grating unit DOE3b is a rectangle with length W5 and height H5. The width W5 can be 80%-95% of the width W4, and the height H5 can be 3-6 times the diameter D1. The right exit pupil grating unit DOE3b needs to be further divided into 5-15 sub-regions. For example, the right exit pupil grating unit DOE3b contains sub-regions R21, R22, R23, R24, R25, R26, and R27 to achieve better uniformity. In addition, the grating period in different sub-regions can be fixed, and the shape characteristics, depth, duty cycle, or exposure conditions of the grating can be controlled, so that the diffraction efficiency of different sub-regions gradually increases, that is, when i is greater than j, the grating diffraction efficiency of the sub-region R2i is greater than that of the sub-region R2j. The efficiency of all corresponding sub-region diffraction gratings can be set to 5%-95%.

[0046] The left exit pupil grating unit DOE3a and the right exit pupil grating unit DOE3b have the same exit pupil grating structure, and the structure size, grating parameters, and partition characteristics must be strictly left-right mirror symmetric, and the diffraction efficiency of each sub-region must also be the same, that is, L2i = R2i.

[0047] The distance between the center positions of the left exit pupil grating unit DOE3a and the right exit pupil grating unit DOE3b is the interpupillary distance IPD, which is set to be in the range of IPD = 60mm-70mm, where the left half distance X1 is equal to the right half distance X2, and X1+X2 = IPD. The vertical distance between the center of the entrance pupil grating unit DOE1 and the center of the left exit pupil grating unit DOE3a is Y1, which is set to be in the range of 8mm-25mm.

[0048] Figure 3 The periods and directions of different grating regions of the optical device EPE1 are given. Each unit DOE1, DOE2a, DOE2b, DOE3a, and DOE3b can contain one or more diffraction grating regions. For example, the unit DOE1 can contain one grating region. For example, the unit DOE2a can contain multiple sub-regions, and the periods and directions of the grating of each sub-region are consistent. For example, the unit DOE2b can contain multiple sub-regions, and the periods of the grating of the sub-regions are consistent. For example, the unit DOE3a can contain multiple sub-regions, and the periods and directions of the grating of each sub-region are consistent. For example, the unit DOE3b can contain multiple sub-regions, and the periods and directions of the grating of each sub-region are consistent.

[0049] The grating period (d) of a diffraction grating and the orientation (β) of the diffraction features of the diffraction grating can be determined by the grating vector V of the diffraction grating. A diffraction grating comprises a plurality of diffraction features (F) which can serve as diffraction lines. A diffraction feature can be, for example, a tiny ridge or groove. A diffraction feature can also be, for example, a microscopic protrusion (or indentation), where adjacent protrusions (or indentations) can serve as diffraction lines. The grating vector V can be defined as a vector having a direction perpendicular to the diffraction lines of the diffraction grating and an amplitude given by 2π / d, where d is the grating period. The grating period means the same as the length of the grating period. The grating period can be the length between consecutive diffraction features of the grating. The grating period can be equal to the unit length divided by the number of diffraction features located within the unit length. The grating period d1a of the entrance pupil grating unit DOE1 can be in the range of, for example, 330 nm to 450 nm, with the optimum value depending on the refractive index of SUB1 and the wavelength λ of the diffracted light.

[0050] The entrance pupil grating unit DOE1 can have a grating vector V1. The left pupil expansion grating unit DOE2a can have a grating vector V2a. The right pupil expansion grating unit DOE2b can have a grating vector V2b. The left exit pupil grating unit DOE3a can have a grating vector V3a. The right exit pupil grating unit DOE3b can have a grating vector V3b.

[0051] The grating vector V1 has a direction β1 and a magnitude 2π / d1. The grating vector V2a has a direction β2a and a magnitude 2π / d2a. The grating vector V2b has a direction β2b and a magnitude 2π / d2b. The grating vector V3a has a direction β3a and a magnitude 2π / d3a. The grating vector V3b has a direction β3b and a magnitude 2π / d3b. The direction (β) of a grating vector can be defined as the angle between the grating vector and a reference direction, for example the direction SX.

[0052] The grating period (d) of the optical units DOE1, DOE2a, DOE3a and the orientation (β) of the diffraction grating can be selected such that the propagation direction DIR0’ of the light of the central point in the output light beam OUT1 is parallel to the propagation direction DIR0 of the light of the central point in the input light IN1.

[0053] The grating period (d) of the optical units DOE1, DOE2b, DOE3b and the orientation (β) of the diffraction grating can be selected such that the propagation direction DIR0’ of the light of the central point in the output light beam OUT2 is also parallel to the propagation direction DIR0 of the light of the central point in the input light IN1.

[0054] The direction β1 of the grating vector V1 in the entrance pupil grating unit DOE1 can be around 0°, for example, -1° to 1°. The direction β2a of the grating vector V2a in the left expanding pupil grating unit DOE2a can be from 30° to 60°. The direction β2b of the grating vector V2b in the right expanding pupil grating unit DOE2b can be from 120° to 150°, and the grating vectors V2a and V2b are mirror-symmetric. The direction β3a of the grating vector V3a in the left exit pupil grating unit DOE3a can be around 90°, for example, 88° to 92°; the direction β3b of the grating vector V3b in the right exit pupil grating unit DOE3b can be around 90°, for example, 88° to 92°; and the grating vectors V3a and V3b are mirror-symmetric.

[0055] For predetermined integers m1, m2a, m2b, m3a, and m3b, the grating period (d) and direction (β) of the grating vector can satisfy the following: the vector sum (m1V1 + m2aV2a + m3aV3a) is zero, and the vector sum (-m1V1 + m2bV2b + m3bV3b) is zero. The values ​​of these predetermined integers are typically +1 or -1. For example, the values ​​of integers m1, m2a, m2b, m3a, and m3b can be +1 or -1. Specifically, if V1 is directed to the left, the sum of V1, V2a, and V3a is zero; if V1 is directed to the right, the sum of V1, V2b, and V3b is zero.

[0056] like Figure 4 As shown, the optical device EPE1 can form the output light OUT1 by diffracting and transmitting the input light IN1 obtained from the optical engine ENG1. The display device 500 may include the optical engine ENG1 and the optical device EPE1.

[0057] The input light IN1 can contain multiple beams propagating in different directions. Each beam of input light IN1 can correspond to a different point in the input image IMG0. The output lights OUT1 and OUT2 can contain multiple beams propagating in different directions, entering the left eye EYE1 and right eye EYE2 respectively. Each beam of output lights OUT1 and OUT2 can correspond to a different point in the displayed virtual image VIMG1. The pupil dilator EPE1 can form the left output light OUT1 and the right output light OUT2 from the input light IN1, such that the direction and intensity of the output lights OUT1 and OUT2 correspond to a point in the input image IMG0.

[0058] The input light IN1 can correspond to a single image point of the displayed image. The optical device EPE1 can form a left-out beam OB1 and a right-out output beam OB2 with the same direction from the beam of the input light IN1, such that the direction of the output beam DIR0' is parallel to the direction DIR0 of the corresponding input light IN1 beam.

[0059] Display device 500 can include an optical engine ENG1 to form a primary image IMG0 and to convert the primary image IMG0 into a plurality of light beams of input light IN1. Light from optical engine ENG1 can be coupled into an entrance pupil grating unit DOE1 of optical apparatus EPE1. Input light IN1 can be coupled into an entrance pupil grating unit DOE1 of optical apparatus EPE1. Apparatus 500 can be a display device for displaying a virtual image. Apparatus 500 can also be a myopia optical device.

[0060] Optical apparatus EPE1 can propagate virtual image content from optical engine ENG1 in front of a left eye EYE1 and a right eye EYE2 of a user. Optical apparatus EPE1 can expand a viewing pupil, thereby expanding an eyebox.

[0061] Optical engine ENG1 can include a microdisplay DISP1 to generate a primary image IMG0. Microdisplay DISP1 can include a two-dimensional array of light-emitting pixels. Display DISP1 can produce, for example, a primary image IMG0 with a resolution of 1280 x 720 (HD). Display DISP1 can produce, for example, a primary image IMG0 with a resolution of 1920 x 1080 (Full HD). Display DISP1 can produce, for example, a primary image IMG0 with a resolution of 3840 x 2160 (4K UHD). Optical engine ENG1 can include collimating optics LNS1 to form a different light beam for each image pixel. Optical engine ENG1 can include collimating optics LNS1 to cause light emitted from a certain pixel to form a substantially collimated light beam. Different pixels can correspond to different collimating directions.

[0062] Optical engine ENG1 can provide a plurality of light beams corresponding to a generated primary image IMG0. One or more light beams provided by optical engine ENG1 can be coupled into optical apparatus EPE1 and serve as input light IN1.

[0063] Optical engine ENG1 can include, for example, one or more light-emitting diodes (LEDs). Display DISP1 can include one or more microdisplay imagers, such as liquid crystal on silicon (LCOS), liquid crystal display (LCD), digital micromirror device (DMD).

[0064] Waveguide plate SUB1 can have a first major surface SRF1 and a second major surface SRF2. Surfaces SRF1, SRF2 can be substantially parallel to a plane defined by directions SX and SY. Waveguide plate SUB1 can have a thickness t1. Waveguide plate can include a planar waveguide core portion. In embodiments, waveguide plate SUB1 can optionally include, for example, one or more cladding layers, one or more protective layers, and / or one or more mechanical support layers. Thickness t1 can refer to the thickness of the planar waveguide core portion of waveguide plate SUB1.

[0065] The grating structure of the entrance pupil expander DOE1 can be disposed on the first major surface SRF1 or the second major surface SRF2 of the waveguide plate SUB1, and diffracts the input light beam IN1 to form the first left conducting light B1a and the first right conducting light B1b. The input light beam IN1 can be incident from the front surface of the optical device EPE1 or from the back surface of the EPE1. The first left conducting light B1a and the first right conducting light B1b can propagate inside the planar waveguide plate SUB01, and the main direction of propagation is left-right symmetric. The first left conducting light B1a and the first right conducting light B1b can be confined in the planar waveguide plate SUB1 and undergo total internal reflection (TIR).

[0066] The grating structure of the right exit pupil expander DOE2b and the right exit pupil expander DOE2b can be disposed on the first major surface SRF1 or the second major surface SRF2 of the waveguide plate SUB1. The left exit pupil expander DOE2a receives the first left conducting light B1a and diffracts to form the second left conducting light B2a. The left exit pupil expander DOE2a can distribute the second left conducting light B2a approximately uniformly to the left exit pupil expander DOE3a, and the second left conducting light B2a can propagate in the waveguide plate SUB1 by total internal reflection. The right exit pupil expander DOE2b receives the first right conducting light B1a and diffracts to form the second right conducting light B2b. The right exit pupil expander DOE2b can distribute the second right conducting light B2b approximately uniformly to the right exit pupil expander DOE3b. The second left conducting light B2a can propagate in the waveguide plate SUB1 by total internal reflection.

[0067] The grating structure of the left exit pupil expander DOE3a and the right exit pupil expander DOE3b can be disposed on the first major surface SRF1 or the second major surface SRF2 of the waveguide plate SUB1. The left exit pupil expander DOE3a diffracts the expanded conducting light B2a to form the left output light OB1, and the left output light OB1 forms the left output light beam OUT1 as a whole. The direction of the left output light OB1 and the left output light beam OUT1 is DIR0’. The right exit pupil expander DOE3b diffracts the expanded conducting light B2b to form the right output light OB2, and the right output light OB2 forms the right output light beam OUT2 as a whole. The direction of the right output light OB2 and the right output light beam OUT2 is also DIR0’.

[0068] The left output light beam OUT1 and the right output light beam OUT2 enter the left eye EYE1 and the right eye EYE2, respectively, and the left and right eyes can achieve binocular fusion without additional adjustment because the directions of the light beams are the same. Due to the overall left-right symmetry, the images of the left and right eyes achieve color complementation, thereby achieving better color uniformity and a larger FOV.

[0069] The waveguide plate SUB1 can comprise or consist essentially of a transparent solid material. The waveguide plate SUB1 can comprise, for example, glass, polycarbonate or polymethyl methacrylate (PMMA). The diffractive optical units DOE1, DOE2a, DOE2b, DOE3a, DOE3b can be formed by, for example, molding, embossing and / or etching. The units DOE1, DOE2a, DOE2b, DOE3a, DOE3b can be implemented by, for example, one or more surface diffraction gratings or by one or more volume diffraction gratings.

[0070] Figure 5 A wave vector diagram for light of a wavelength is shown by way of example, which light can propagate within the waveguide plate SUB along a left path and a right path. The wave vectors of the input light IN1 can exist in a region BOX0 of a wave vector space defined by initial wave vectors kxand ky. Each corner of the region BOX0 can represent a wave vector of light of a corner point of an input image IMG0.

[0071] The wave vectors of the first left transmitted light B1 a can be within a region BOX1 a, the wave vectors of the first right transmitted light B1 b can be within a region BOX1 a, the wave vectors of the second left transmitted light B2a can be within a region BOX2a, the wave vectors of the second right transmitted light B2b can be within a region BOX2b, the wave vectors of the left output light beam OUT1 can be within a region BOX3a. The wave vectors of the right output light beam OUT2 can be within a region BOX3b.

[0072] BND1 represents a minimum boundary for satisfying total internal reflection (TIR) criteria in the waveguide plate SUB1, BND2 represents a maximum boundary for satisfying total internal reflection (TIR) criteria in the waveguide plate SUB1, which can be determined by the refractive index of the waveguide plate. Light can be waveguided in the plate SUB1 only if the wave vectors of the light are in a region ZONE1 between the first boundary BND1 and the second boundary BND2. If the wave vectors of the light are outside the region ZONE1, the light can leak out of the waveguide plate or not propagate at all.

[0073] The grating period (d) and the orientation (β) of the diffraction gratings of the optical units DOE1, DOE2a, DOE3a, DOE2b, DOE3b can be chosen such that the regions BOX0, BOX3a, BOX3b in the wave vector space almost coincide. At the same time for the wavelengths of the three colors RGB, the wave vectors of the regions BOX1 a and BOX1 b, BOX2a, BOX2b are within the region ZONE1 defined by the boundaries BND1, BND2. At the same time the regions BOX2a, BOX2b in the wave vector space almost coincide.

[0074] The left path is counter-clockwise, for example, the entrance pupil grating unit DOE1 can diffract the input light IN1 to form the first left conducted light B1a, i.e. the wave vector of the first left conducted light B1a is represented by adding the grating vector -m1V1 of the entrance pupil grating unit DOE1 to the wave vector of the input light IN1. The wave vector of the second left conducted light B2a can be determined by adding the grating vector m2aV2a to the wave vector of the first conducted light B1a. Finally the wave vector of the exit light OUT1 can be determined by adding the grating vector m3aV3a to the wave vector of the second left conducted light B2a.

[0075] The right path is counter-clockwise, for example, the entrance pupil grating unit DOE1 can diffract the input light IN1 to form the first right conducted light B1b, i.e. the wave vector of the first right conducted light B1b is represented by adding the grating vector m1V1 of the entrance pupil grating unit DOE1 to the wave vector of the input light IN1. The wave vector of the second right conducted light B2b can be determined by adding the grating vector m2bV2b to the wave vector of the first conducted light B1b. Finally the wave vector of the exit light OUT2 can be determined by adding the grating vector m3bV3b to the wave vector of the second right conducted light B2b.

[0076] The grating periods (d) and the orientations (β) of the diffraction gratings of the optical units DOE1, DOE2a, DOE3a, DOE2b, DOE3b can be selected such that the angle between the grating vectors -V1 and V2a can be 30° to 60°, the angle between the grating vectors V1 and V2b can be 120° to 150°, the angle between the grating vectors V2a and V3a can be 30° to 60°, the angle between the grating vectors V2b and V3b can be 30° to 60°, and the left and right paths of the light propagation are mirror-symmetric.

[0077] kx denotes a direction in the wave vector space, wherein the direction kx is parallel to the direction SX in the real space. ky denotes a direction in the wave vector space, wherein the direction ky is parallel to the direction SY in the real space. The symbol kz (not shown in the figures) denotes a direction in the wave vector space, wherein the direction kz is parallel to the direction SZ in the real space. The wave vector k can have components in the directions kx, ky and / or kz.

[0078] Figure 6 The corner of the grating area can be made arc-shaped to better adapt to the shape of the eyeglasses, as illustrated by the front view of the optical device EPE1.

[0079] The upper left arc of the second left pupil-expanding region DOE2a is r1, the lower left arc is r2, the right arc is r5, the upper right arc of the second right pupil-expanding region DOE2b is r3, the lower right arc is r4, and the left arc is r6. The four-corner arc of the third left pupil-expanding region DOE3a can be r7, and the four-corner arc of the third right pupil-expanding region DOE3b can be r8. The radius of curvature of all the arcs ranges from 2 mm to 20 mm.

[0080] The optical device of the embodiment can surround the entrance pupil light of the left and right eyes, only one light engine is needed, and the overall efficiency of the diffraction waveguide is improved. The grating setting of the waveguide plate is used to control binocular coupling by using the precision of the glass wafer, to reduce the difficulty of binocular coupling generation and improve the coupling degree. The optical symmetry of the left and right eyes can be mutually compensated, and the uniformity of color perception is better. The integrated waveguide design can be matched with the arc modeling, and is more suitable for human use.

[0081] In the above description of the present specification, unless otherwise explicitly specified and limited, the terms "fixed", "mounted", "connected" or "linked" and the like should be understood in a broad sense. For example, as to the term "connected", it can be fixed connection, detachable connection, or integral; it can be mechanical connection, electrical connection; it can be direct connection, or indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements. Therefore, unless otherwise explicitly limited in the present specification, those skilled in the art can understand the specific meaning of the above terms in the present application according to the specific circumstances.

[0082] According to the above description of the present specification, those skilled in the art can also understand that the terms used, such as "upper", "lower", "front", "rear", "left", "right", "length", "width", "thickness", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", "center", "longitudinal", "transverse", "clockwise" or "counterclockwise", and the like indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings of the present specification, which are only for the purpose of facilitating the description of the scheme of the present application and simplifying the description, and are not explicitly or implicitly indicating or suggesting that the devices or elements involved must have the specific orientation, be constructed and operated in a specific orientation, therefore the above orientation or positional relationship terms cannot be understood or interpreted as a limitation on the scheme of the present application.

[0083] In addition, the terms "first" or "second" and the like used in the description of the specification are used for terms indicating numbers or ordinal numbers only for the purpose of description and cannot be understood as explicitly or implicitly indicating relative importance or implying the number of indicated technical features. Thus, the features defined with "first" or "second" can explicitly or implicitly include at least one of the features. In the description of the specification, the meaning of "plurality" is at least two, for example, two, three or more, etc., unless otherwise explicitly and specifically limited.

[0084] While the present specification has shown and described a number of embodiments of the present application, it is to be understood that such embodiments are merely exemplary of the application and that various modifications, changes, and substitutions can be made by those skilled in the art without departing from the idea and scope of the present application. It is therefore intended that the following claims be interpreted only as limiting and in the broadest sense.

Claims

1. An optical device, characterized by, The optical device comprises a waveguide plate, and a: An entrance pupil grating unit, through which the input light diffracts to form first left and right conducting lights, wherein the entrance pupil grating unit has only one grating vector (V1); A left pupil expanding grating unit located on the left side of the entrance pupil grating unit, through which the first left conducting light diffracts to form second left conducting light, wherein the left pupil expanding grating unit has only one grating vector (V2a); A right pupil expanding grating unit located on the right side of the entrance pupil grating unit, through which the first right conducting light diffracts to form second right conducting light, wherein the right pupil expanding grating unit has only one grating vector (V2b); A left exit pupil grating unit located on the lower side of the left pupil expanding grating unit, through which the second left conducting light diffracts to form left output light, wherein the left exit pupil grating unit has only one grating vector (V3a); A right exit pupil grating unit located on the lower side of the right pupil expanding grating unit, through which the second right conducting light diffracts to form right output light, wherein the right exit pupil grating unit has only one grating vector (V3b); The left and right pupil expanding grating units are mirror-symmetrical to each other with the entrance pupil grating unit as the center, and the left and right exit pupil grating units are mirror-symmetrical to each other with the entrance pupil grating unit as the center; The left and right pupil expanding grating units comprise a plurality of sub-pupil expanding regions, and the diffraction efficiency of each sub-pupil expanding region gradually increases in the direction away from the entrance pupil grating unit, and the angle between the boundary line between adjacent sub-pupil expanding regions and the horizontal direction is different; The directions of the input light, the left output light and the right output light are consistent, so that the virtual images received by the left eye and the virtual images received by the right eye have the same content.

2. The optical device of claim 1, wherein, The entrance pupil grating unit is a surface grating or a holographic volume grating, the entrance pupil grating unit is circular, the diameter is 2.5mm-7mm, and the grating period of the entrance pupil grating unit is 330nm-450nm.

3. The optical device of claim 2, wherein, The left and right pupil expanding grating units are pupil expanding grating structures, and the height of the pupil expanding grating structure in the vertical direction gradually increases in the horizontal direction away from the entrance pupil grating unit; the maximum height of the pupil expanding grating structure in the vertical direction is 2-5 times the diameter of the entrance pupil grating unit, and the width of the pupil expanding grating structure in the horizontal direction is 5-10 times the diameter of the entrance pupil grating unit.

4. The optical device of claim 3, wherein, The pupil expanding grating structure is divided into 5-15 sub-pupil expanding regions, and the angle between the boundary line between adjacent sub-pupil expanding regions and the horizontal direction is 20-160 degrees; the diffraction efficiency of the sub-pupil expanding region is 5%-95%.

5. The optical device of claim 3, wherein, The left and right exit pupil grating units are exit pupil grating structures, and the exit pupil grating structure is rectangular, the height in the vertical direction is 3-6 times the diameter of the entrance pupil grating unit, and the width in the horizontal direction is 80%-95% of the width of the pupil expanding grating structure.

6. The optical device of claim 5, wherein, The exit pupil grating structure is divided into 5-15 sub-exit pupil regions in the vertical direction, and the diffraction efficiency of each sub-exit pupil region gradually increases in the direction away from the entrance pupil grating unit in the vertical direction, and the diffraction efficiency of the sub-exit pupil region is 5%-95%.

7. The optical device of claim 5, wherein, The pupil expanding grating structure is a quadrilateral, and the four corners of the pupil expanding grating structure and the four corners of the exit pupil grating structure are arc-shaped, and the curvature radius of the arc is 0mm-20mm.

8. The optical device of claim 1, wherein, The horizontal distance from the center of the left exit pupil grating unit to the center of the right exit pupil grating unit is the interpupillary distance of the human eye, and the interpupillary distance of the human eye is 60mm-70mm; the vertical distance from the center of the entrance pupil grating unit to the center of the left exit pupil grating unit is 8mm-25mm.

9. The optical device of claim 1, wherein, Taking the left-to-right direction as the reference, the grating vector direction of the entrance pupil grating unit is-1 degree-1 degree, the grating vector direction of the left pupil expanding grating unit is 30 degrees-60 degrees, the grating vector direction of the right pupil expanding grating unit is 120 degrees-150 degrees, the grating vector direction of the left exit pupil grating unit is 88 degrees-92 degrees, and the grating vector direction of the right exit pupil grating unit is 88 degrees-92 degrees.

10. The optical device of claim 9, wherein, In the wave vector space, the wave vector regions of the left output light, the right output light and the input light coincide, the wave vector regions of the first left conducting light and the first right conducting light, the second left conducting light and the second right conducting light are between the total internal reflection minimum wave vector and the total internal reflection maximum wave vector of the waveguide plate, and the wave vector regions of the second left conducting light and the second right conducting light coincide.

11. The optical device of claim 9, wherein, The grating vector of the entrance pupil grating unit is to the left, and the sum of the grating vectors of the entrance pupil grating unit, the left pupil expanding grating unit and the left exit pupil grating unit is zero; the grating vector of the entrance pupil grating unit is to the right, and the sum of the grating vectors of the entrance pupil grating unit, the right pupil expanding grating unit and the right exit pupil grating unit is zero.

12. A display device, characterized by comprising: The display device comprises a light engine and an optical device according to any one of claims 1-11; the light engine is used to generate the input light.

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