CN116893470B - Diffraction optical waveguide and augmented reality display device - Google Patents

Diffraction optical waveguide and augmented reality display device Download PDF

Info

Publication number
CN116893470B
CN116893470B CN202311165701.6A CN202311165701A CN116893470B CN 116893470 B CN116893470 B CN 116893470B CN 202311165701 A CN202311165701 A CN 202311165701A CN 116893470 B CN116893470 B CN 116893470B
Authority
CN
China
Prior art keywords
angle
waveguide substrate
view
refractive index
image light
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202311165701.6A
Other languages
Chinese (zh)
Other versions
CN116893470A (en
Inventor
黄鹏
张雅琴
楼歆晔
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shanghai Kunyou Technology Co ltd
Original Assignee
Shanghai Kunyou Technology Co ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shanghai Kunyou Technology Co ltd filed Critical Shanghai Kunyou Technology Co ltd
Priority to CN202311165701.6A priority Critical patent/CN116893470B/en
Publication of CN116893470A publication Critical patent/CN116893470A/en
Application granted granted Critical
Publication of CN116893470B publication Critical patent/CN116893470B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0015—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0016—Grooves, prisms, gratings, scattering particles or rough surfaces
    • 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
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Couplings Of Light Guides (AREA)

Abstract

The application provides a diffraction optical waveguide and augmented reality display equipment, which comprises a waveguide substrate, a coupling-in grating and a coupling-out grating, wherein image light is coupled into the waveguide substrate through the coupling-in grating and is coupled out into human eyes through the coupling-out grating after being transmitted to the coupling-out grating through total reflection; the refractive index of the waveguide substrate is anisotropic and rotationally symmetric, so that the expected angle range of the image light entering the waveguide substrate is smaller than the reference angle range, wherein the reference angle range is the angle range of the image light entering the waveguide substrate when the refractive index of the waveguide substrate is isotropic, and min (n 1 )≤n 2 ＜max(n 1 )，n 1 A refractive index value n which is the refractive index anisotropy of the waveguide substrate 2 Is the refractive index value of the waveguide substrate that is isotropic in refractive index. Therefore, the light density difference between the light rays with different angles of view can be reduced, and the FOV uniformity of the diffraction optical waveguide is improved.

Description

Diffraction optical waveguide and augmented reality display device
Technical Field
The application relates to the technical field of optics, in particular to a diffraction optical waveguide and an augmented reality display device.
Background
Augmented reality is a technology that merges real world and virtual information, and an augmented reality display system typically includes a micro projector and an optical display screen, where the micro projector provides virtual display content for the augmented reality display system to be projected into the human eye through the optical display screen, which is typically a transparent optical component, so that a user can see the real world through the optical display screen at the same time.
The diffraction optical waveguide is an implementation manner of an optical display screen, and the diffraction angles of light rays with different angles of view (FOV) after the light rays are acted by the diffraction grating are different, so that the light ray densities of the light rays with different angles of view in the waveguide substrate are different, so that the energy distribution difference is large, and the uniformity of the FOV is poor.
Disclosure of Invention
The embodiment of the application provides a diffraction optical waveguide and an augmented reality display device, which can reduce the light density difference between light rays with different angles of view, thereby improving the uniformity of the FOV of the diffraction optical waveguide.
A diffraction optical waveguide comprises a waveguide substrate, an in-coupling grating and an out-coupling grating, wherein image light is coupled into the waveguide substrate through the in-coupling grating and is transmitted to the waveguide substrate in a total reflection wayThe coupling-out grating is coupled out into human eyes through the coupling-out grating; the refractive index of the waveguide substrate is anisotropic and rotationally symmetric, so that the expected angle range of the image light entering the waveguide substrate is smaller than the reference angle range, wherein the reference angle range is the angle range of the image light entering the waveguide substrate when the refractive index of the waveguide substrate is isotropic, and min (n 1 )≤n 2 ＜max(n 1 )，n 1 A refractive index value n which is the refractive index anisotropy of the waveguide substrate 2 Is the refractive index value of the waveguide substrate that is isotropic in refractive index.
In one embodiment, the expected angles of the image light beams of each field angle after entering the waveguide substrate are smaller than the reference angles corresponding to each field angle, and the difference between the expected angles corresponding to each field angle and the reference angles is positively correlated with the reference angles corresponding to each field angle.
In one embodiment, the desired angle of the image light beam at the first partial angle of view after entering the waveguide substrate is greater than the corresponding reference angle, and the desired angle of the image light beam at the second partial angle of view after entering the waveguide substrate is less than the corresponding reference angle, wherein the reference angle corresponding to the first partial angle of view is less than the reference angle corresponding to the second partial angle of view.
In practice, the refractive index of the waveguide substrate is anisotropic and an anomalous dispersion condition is satisfied such that the refractive index value of the waveguide substrate is positively correlated with the wavelength of the image light.
In one embodiment, the effective diffraction order of the image light beam entering the waveguide substrate after being diffracted by the coupling-in grating is split into a first beam and a second beam, the transmission angle of the first beam is the desired angle, and the transmission angle of the second beam is different from the desired angle, where the optical axis is perpendicular to or parallel to the plane of the waveguide substrate.
In one embodiment, the transmission angle of the second beam of light after the image light of the third part of the field angle enters the waveguide substrate is larger than the desired angle, and the transmission angle of the second beam of light after the image light of the fourth part of the field angle enters the waveguide substrate is smaller than the desired angle, wherein the desired angle corresponding to the third part of the field angle is smaller than the desired angle corresponding to the fourth part of the field angle.
In one embodiment, the diffractive optical waveguide further comprises a dielectric layer interposed between a grating structure and the waveguide substrate, the grating structure comprising the in-coupling grating and the out-coupling grating.
In one embodiment, the refractive index of the dielectric layer is different from the refractive index of the waveguide substrate, and the refractive index of the dielectric layer is the same as or different from the refractive index of the grating structure.
In practice, the thickness and/or refractive index of the dielectric layer is adjusted to optimize the coupling-in efficiency and/or the coupling-out efficiency of the diffractive optical waveguide.
An augmented reality display device, the augmented reality display device comprising: projection optics and a diffractive optical waveguide according to any of the preceding claims.
According to the diffraction optical waveguide provided by the application, one refractive index value of the waveguide substrate which is isotropic and the refractive index of the diffraction optical waveguide substrate is anisotropic is taken as a reference, the angle range of the diffraction optical waveguide substrate after the image light enters the isotropic waveguide substrate is taken as a reference angle range, the refractive index anisotropy and the rotation symmetry distribution of the diffraction optical waveguide substrate are set, so that the expected angle range of the diffraction optical waveguide substrate after the image light enters the anisotropic waveguide substrate is smaller than the reference angle range, the angle difference of the light rays with different view angles when the light rays with different view angles are transmitted in the waveguide substrate can be reduced, and the light ray density difference among the light rays with different view angles is further reduced, so that the FOV uniformity of the diffraction optical waveguide is improved.
The augmented reality display device provided by the application comprises the diffractive optical waveguide, and has the advantages of the diffractive optical waveguide.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the description of the embodiments will be briefly described below, it will be apparent that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art;
FIG. 1 is a schematic diagram of a diffractive optical waveguide provided in an embodiment of the present application;
FIG. 2 is a schematic diagram of a diffractive optical waveguide provided by another embodiment of the present application;
FIG. 3 is a schematic view showing the refractive index distribution of a waveguide substrate according to an embodiment of the present application;
FIG. 4 is a schematic view showing refractive index distribution of a waveguide substrate according to another embodiment of the present application;
FIG. 5 is a schematic diagram of a diffractive optical waveguide provided by another embodiment of the present application;
FIG. 6 is a schematic diagram of a diffractive optical waveguide provided by another embodiment of the present application;
FIG. 7 is a schematic diagram of a diffractive optical waveguide provided by another embodiment of the present application;
FIG. 8 is a schematic diagram of a diffractive optical waveguide provided by another embodiment of the present application;
the attached drawings are identified:
110, a grating structure;
101, coupling into a grating;
102, coupling out a grating;
120, a waveguide substrate;
130, a dielectric layer;
141, first light splitting;
142, second spectroscopy.
Detailed Description
In order that those skilled in the art will better understand the present application, a technical solution in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, shall fall within the scope of the present application.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present application and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the application described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
According to an aspect of the present application, referring to fig. 1 and 2, an embodiment of the present application provides a diffractive optical waveguide, including a waveguide substrate 120, an in-coupling grating 101 and an out-coupling grating 102, where an image light is coupled into the waveguide substrate 120 through the in-coupling grating 101, and is totally reflected and transmitted to the out-coupling grating 102, and then coupled out into a human eye through the out-coupling grating 102; the refractive index of the waveguide substrate 120 is anisotropic and rotationally symmetric such that the desired angular range of the image light after entering the waveguide substrate 120 is smaller than the reference angular range, which is the angular range of the image light after entering the waveguide substrate 120 when the refractive index of the waveguide substrate 120 is isotropic, and min (n 1 )≤n 2 ＜max(n 1 )，n 1 N, the refractive index value of the refractive index anisotropy of the waveguide substrate 120 2 Is an isotropic refractive index value of the refractive index of the waveguide substrate 120.
Specifically, the image light rays 1, 2 are edge angles of view of the light machine exitThe image light rays of (2) are diffracted by the coupling grating 101 and then enter the waveguide substrate for transmission, wherein the transmission angle is the diffraction angle +.>I.e. the angle between the image light and the normal to the surface of the waveguide substrate. Image light 1,Diffraction angle +.2 for image light of other angles of view between 2>Wherein->For the edge angle of view +.>Diffraction angle of image ray, +.>For the edge angle of view +.>Diffraction angles of the image rays of (2), it can be understood that in +.>And->The greater the difference in (2), the poorer the FOV uniformity of the diffractive optical waveguide, at +.>And->The smaller the difference in the FOV uniformity of the diffractive optical waveguide. Based on this, the waveguide substrate 120 of the present application is provided with refractive index anisotropy and rotationally symmetric distribution by compression +.>And->The difference between them improves the FOV uniformity of the diffractive optical waveguide.
In the embodiment of the application, the waveguide substrate is taken as the isotropy of the refractive index (the refractive index is) For reference scenes, image lightThe transmission angle of the line after entering the isotropic waveguide substrate is the reference angle +.>The method comprises the steps of carrying out a first treatment on the surface of the Setting the refractive index anisotropy of the waveguide substrate (refractive index +.>) And coverage of the range->The transmission angle of the image light entering the anisotropic waveguide substrate is a desired angleSo that the desired angular range of the image light after entering the anisotropic waveguide substrate +.>Less than the reference angle range after the image light enters the isotropic waveguide substrate>. I.e.And->Wherein->Is +.>Minimum value->Is +.>Maximum value of>Is a reference angle->Minimum value->Is a reference angle->Maximum value of>Is the maximum value of refractive index when the refractive index is anisotropic, < >>Is the refractive index minimum value at the time of refractive index anisotropy.
Therefore, the difference of transmission angles of the light rays with different angles of view in the waveguide substrate can be compressed, the light ray density difference between the light rays with different angles of view is further reduced, and the FOV uniformity of the diffraction optical waveguide is improved.
In one embodiment of the present application, referring to fig. 1, the expected angles of the image light rays of each field angle after entering the waveguide substrate are smaller than the reference angles corresponding to each field angle, and the difference between the expected angles corresponding to each field of view and the reference angles are positively correlated with the reference angles corresponding to each field angle.
Specifically, the image light is diffracted after being incident on the coupling-in grating, and the diffracted light is transmitted in the waveguide substrate. Setting the refractive index of the waveguide substrate to beThe value in the case of anisotropy is +.>The value in isotropy is +.>，/>For the diffraction angle of the image light, i.e. the transmission of the image light in the waveguide substrateAngle. Referring to FIG. 3, due to->In combination with the grating equation: />Therefore->Wherein->For coupling into the grating period of the grating +.>Refractive index of air, +.>Refractive index of waveguide substrate, +.>Is the angle of incidence of the image light, i.e. the angle of view of the image light. That is, for image light of any angle of view, satisfy +.>And with continued reference to fig. 3 it can be seen that as +.>Become larger and get on>Also becomes larger gradually, so that the difference between the desired angle corresponding to each field of view and the reference angle is positively correlated with the reference angle corresponding to each field of view, there is +.>Therefore, the difference of transmission angles of the light rays with different angles of view in the waveguide substrate can be compressed, the light ray density difference between the light rays with different angles of view is further reduced, and the FOV uniformity of the diffraction optical waveguide is improved.
For example, refer toFig. 1 shows an image light ray 1 (edge angle of view) After being diffracted into the waveguide substrate 120 by the coupling grating 101, the refractive index isotropy of the waveguide substrate 120 takes on a value +.>The diffracted light is shown in solid lines (diffraction angle is reference angle +.>) The refractive index anisotropy value in the waveguide substrate 120 is +.>The diffracted light is shown by a long dashed line (diffraction angle is desired angle +.>) At this time, the->The method comprises the steps of carrying out a first treatment on the surface of the Image ray 2 shown in short dashed line (edge angle of view +.>) After being diffracted into the waveguide substrate 120 by the coupling grating 101, the refractive index isotropy of the waveguide substrate 120 takes on a value +.>The diffracted light is shown in short dashed lines (diffraction angle is reference angle +.>) The refractive index anisotropy value in the waveguide substrate 120 is +.>The diffracted light is shown in dotted lines (diffraction angle is desired angle +.>) At this time, the first and second electrodes are connected,/>. For image light of any other view angle, due to its view angle +.>At->To->Between, then its corresponding reference angle +.>Also at->To->Between, corresponding to the desired angle +>Also atTo->In the case where the difference between the desired angle corresponding to each field of view and the reference angle is positively correlated with the reference angle corresponding to each field of view, i.e. +.>) There is->This also enables compression of the differences in the transmission angles of light rays of different angles of view in the waveguide substrate.
In one embodiment of the present application, referring to fig. 2, the desired angle of the first partial angle of view of the image light entering the waveguide substrate is greater than the corresponding reference angle, and the desired angle of the second partial angle of view of the image light entering the waveguide substrate is less than the corresponding reference angle, wherein the corresponding reference angle of the first partial angle of view is less than the corresponding reference angle of the second partial angle of view.
Specifically, the image light is diffracted after being incident on the coupling-in grating, and the diffracted light is transmitted in the waveguide substrate. Setting the refractive index of the waveguide substrate to beThe value in the case of anisotropy is +.>The value in isotropy is +.>，/>The full view field at least comprises a first part of view angle and a second part of view angle, wherein the reference angle corresponding to the first part of view angle is smaller than the reference angle corresponding to the second part of view angle. Referring to FIG. 4, for the image light of the first partial angle of view, due to +.>In combination with the grating equation:therefore->For image light at the second partial angle of view, due toIn combination with the grating equation: />Therefore->Just there isTherefore, the difference of transmission angles of the light rays with different angles of view in the waveguide substrate can be compressed, the light ray density difference between the light rays with different angles of view is further reduced, and the FOV uniformity of the diffraction optical waveguide is improved. Wherein (1)>For coupling into the grating period of the grating +.>Refractive index of waveguide substrate, +.>Is the angle of incidence of the image light, i.e. the angle of view of the image light.
For example, referring to fig. 2, image ray 1 (edge angle of view) After being diffracted into the waveguide substrate 120 by the coupling grating 101, the refractive index isotropy of the waveguide substrate 120 takes on a value +.>The diffracted light is shown in solid lines (diffraction angle is reference angle +.>) The refractive index anisotropy value in the waveguide substrate 120 is +.>The diffracted light is shown by a long dashed line (diffraction angle is desired angle +.>) At this time, the->The method comprises the steps of carrying out a first treatment on the surface of the Image ray 2 shown in short dashed line (edge angle of view +.>) After being diffracted into the waveguide substrate 120 by the coupling grating 101, the refractive index isotropy of the waveguide substrate 120 takes on a value +.>The diffracted light is shown in short dashed lines (diffraction angle is reference angle +.>) The refractive index anisotropy value in the waveguide substrate 120 is +.>The diffracted light is shown in dotted lines (diffraction angle is desired angle +.>) At this time, the->. For image light of any other view angle, due to its view angle +.>At->To->Between, then its corresponding reference angle +.>Also at->To->Between, corresponding to the desired angle +>Also atTo->There is->This also enables compression of the differences in the transmission angles of light rays of different angles of view in the waveguide substrate.
It should be noted that, the refractive index anisotropy of the waveguide substrate refers to a function of a direction angle of the refractive index in space, that is, a function of a transmission angle of the image light in the waveguide substrate. The spatial distribution of the refractive index of the waveguide substrate may be, for example, an ellipsoid, a cube, a hexahedron, or the like, in a rotationally symmetrical manner. The material of the waveguide substrate may be, but is not limited to, lithium niobate, lithium tantalate, sapphire, calcite, and the like.
Further, according to an aspect of the present application, referring to fig. 5 and 6, the waveguide substrate of the diffractive optical waveguide provided in the embodiment of the present application further has a spectroscopic characteristic. In one embodiment, the effective diffraction order of the image light entering the waveguide substrate after being diffracted by the coupling grating is split into a first beam splitter 141 and a second beam splitter 142, the transmission angle of the first beam splitter 141 is a desired angle, and the transmission angle of the second beam splitter 142 is different from the desired angle, wherein the optical axis is perpendicular or parallel to the plane of the waveguide substrate.
Thus, by splitting the light into two parts, one part being at the same angle as the conventional transmission and the other part being at a different angle from the conventional transmission, the light density can be adjusted. For example, the transmission angle of the light in the conventional waveguide substrate without the light splitting characteristic is a conventional transmission angle, after the waveguide substrate is changed to have the light splitting characteristic, one part of the light is the same as the conventional transmission angle, the other part of the light is different from the conventional transmission angle, and if the transmission angle is smaller than the conventional transmission angle, the equivalent transmission angle of two light parts is reduced, so that the average density of the light is increased; otherwise, the average density of light is reduced.
It will be appreciated that the transmission angles of image light rays of different angles of view in the waveguide substrate are different, the greater the transmission angle, the lower the density of light rays, and the lower the transmission angle, the higher the density of light rays. Then in order to improve the FOV uniformity of the diffractive optical waveguide, it is desirable to reduce the density difference between image light rays at different angles of view, such as increasing the density of image light rays at large transmission angles and/or decreasing the density of image light rays at small transmission angles.
Illustratively, referring to fig. 5, the transmission angle of the second split beam 142 after the image light of the third partial angle of view enters the waveguide substrate is greater than the desired angle, and referring to fig. 6, the transmission angle of the second split beam 142 after the image light of the fourth partial angle of view enters the waveguide substrate is less than the desired angle, wherein the desired angle corresponding to the third partial angle of view is less than the desired angle corresponding to the fourth partial angle of view.
Specifically, the full field of view includes at least a third part of view angle and a fourth part of view angle, and since the expected angle corresponding to the third part of view angle is smaller than the expected angle corresponding to the fourth part of view angle, that is to say, the density of the image light corresponding to the third part of view angle is greater than the density of the image light corresponding to the fourth part of view angle, in this embodiment, the transmission angle of the second beam of light after the image light of the third part of view angle enters the waveguide substrate is set to be greater than the expected angle, so as to reduce the light density of the image light corresponding to the third part of view angle, and the transmission angle of the second beam of light after the image light of the fourth part of view angle enters the waveguide substrate is set to be less than the expected angle, so as to increase the density difference between the image light of different view angles, and improve the uniformity of the FOV of the diffracted optical waveguide.
The division of the first and second partial angles of view is independent of the division of the third and fourth partial angles of view, and the division is based on different rules.
Further, referring to fig. 7 and 8, according to an aspect of the present application, the diffractive optical waveguide provided in an embodiment of the present application further includes a dielectric layer 130, the dielectric layer 130 being interposed between the grating structure 110 and the waveguide substrate 120, the grating structure 110 including the in-coupling grating 101 and the out-coupling grating 102.
Specifically, the image light rays 1 and 2 are the image light rays of the edge view angle emitted by the optical machineAfter being diffracted by the coupling grating 101, the light enters the medium layer 130 for transmission, wherein the transmission angle is the diffraction angle +.>That is, the included angle between the image light and the normal line of the surface of the waveguide substrate, the image light is continuously refracted by the interface between the dielectric layer 130 and the waveguide substrate 120 and then enters the waveguide substrate 120 for transmission, and the transmission angle is refraction angle +.>. Refraction angle of image light of other angle of field between image light 1, 2 +.>Wherein->For the edge angle of view +.>Refraction angle of image ray, +.>For the edge angle of view +.>Is, then, understood to be at +.>And->The greater the difference in (2), the poorer the FOV uniformity of the diffractive optical waveguide, at +.>And->The smaller the difference in the FOV uniformity of the diffractive optical waveguide. Based on this, the waveguide substrate 120 of the present application is provided with refractive index anisotropy and rotationally symmetric distribution by compression +.>And->The difference between them improves the FOV uniformity of the diffractive optical waveguide.
In one embodiment of the present application, referring to fig. 7, the expected angles of the image light rays of each field angle after entering the waveguide substrate are smaller than the reference angles corresponding to each field angle, and the difference between the expected angles corresponding to each field of view and the reference angles are positively correlated with the reference angles corresponding to each field angle.
Specifically, the refractive index of the dielectric layer is set toThe refractive index of the waveguide substrate is +.>The value in the case of anisotropy is +.>The value in isotropy is +.>，/>Is the angle of refraction of the image light, i.e., the angle of transmission of the image light in the waveguide substrate. At->When combined with the snell formula: />Therefore, it is desirable toAngle->Less than the reference angle->. That is, for image light of any angle of view, satisfy +.>And with->Become larger and get on>Also becomes larger gradually, so that the difference between the desired angle corresponding to each field of view and the reference angle is positively correlated with the reference angle corresponding to each field of view, there is +.>，/>Is +.>Minimum value->Is +.>Maximum value of>Is a reference angle->Minimum value->Is a reference angle->Therefore, the difference of transmission angles of the light rays with different angles of view in the waveguide substrate can be compressed, the light ray density difference between the light rays with different angles of view is further reduced, and the FOV uniformity of the diffraction optical waveguide is improved.
For example, referring to fig. 7, image ray 1 (edge angle of view) After being diffracted by the coupling grating 101 into the dielectric layer 130, the diffracted light is shown by a solid line, and after being refracted into the waveguide substrate 120, the isotropic value of the refractive index of the waveguide substrate 120 is +.>The refracted ray is shown in solid line (refractive angle is reference angle +.>) The refractive index anisotropy value in the waveguide substrate 120 is +.>The refracted ray is shown in long dashed lines (refractive angle is desired angle +>) At this time, the->The method comprises the steps of carrying out a first treatment on the surface of the Image ray 2 shown in short dashed line (edge angle of view +.>) After being diffracted by the coupling grating 101 into the dielectric layer 130, the diffracted light is shown by a short dashed line, and after being refracted into the waveguide substrate 120, the isotropic value of the refractive index of the waveguide substrate 120 is +.>The refracted ray is shown in short dashed lines (refractive angle is the reference angle) The refractive index anisotropy value in the waveguide substrate 120 is +.>The refracted ray is shown in dotted lines (refractive angle is desired angle + ->) At this time, the->. For image light of any other view angle, due to its view angle +.>At->To->Between, then its corresponding reference angle +.>Also at->To->Between, corresponding to the desired angle +>Also at->To->In the case where the difference between the desired angle corresponding to each field of view and the reference angle is positively correlated with the reference angle corresponding to each field of view, i.e. +.>) At the time, there isThis also enables compression of the differences in the transmission angles of light rays of different angles of view in the waveguide substrate.
In one embodiment of the present application, referring to fig. 8, the desired angle of the first partial angle of view of the image light entering the waveguide substrate is greater than the corresponding reference angle, and the desired angle of the second partial angle of view of the image light entering the waveguide substrate is less than the corresponding reference angle, wherein the corresponding reference angle of the first partial angle of view is less than the corresponding reference angle of the second partial angle of view.
Specifically, the refractive index of the dielectric layer is set toSetting the refractive index of the waveguide substrate to +.>The value in the case of anisotropy is +.>The value in isotropy is +.>，/>The full view field at least comprises a first part of view angle and a second part of view angle, wherein the reference angle corresponding to the first part of view angle is smaller than the reference angle corresponding to the second part of view angle. For the image light of the first partial angle of view, due to +.>In combination with the snell formula: />So the desired angle +.>Greater than reference angle->For image light at the second partial angle of view, due to +.>In combination with the snell formula: />So the desired angle +.>Less than the reference angle->There is->Therefore, the difference of transmission angles of the light rays with different angles of view in the waveguide substrate can be compressed, the light ray density difference between the light rays with different angles of view is further reduced, and the FOV uniformity of the diffraction optical waveguide is improved.
For example, referring to fig. 8, image ray 1 (edge angle of view) After being diffracted by the coupling grating 101 into the dielectric layer 130, the diffracted light is shown by a solid line, and after being refracted into the waveguide substrate 120, the isotropic value of the refractive index of the waveguide substrate 120 is +.>The refracted ray is shown in solid line (refractive angle is reference angle +.>) The refractive index anisotropy value in the waveguide substrate 120 is +.>When refractingThe light rays are shown in long dashed lines (refractive angle is desired angle +.>) At this time, the->The method comprises the steps of carrying out a first treatment on the surface of the Image ray 2 shown in short dashed line (edge angle of view +.>) After being diffracted by the coupling grating 101 into the dielectric layer 130, the diffracted light is shown by a short dashed line, and after being refracted into the waveguide substrate 120, the isotropic value of the refractive index of the waveguide substrate 120 is +.>The refracted ray is shown in short dashed lines (refractive angle is the reference angle) The refractive index anisotropy value in the waveguide substrate 120 is +.>The refracted ray is shown in dotted lines (refractive angle is desired angle + ->) At this time, the->. For image light of any other view angle, due to its view angle +.>At->To->Between, then its corresponding reference angle +.>Also at->To->Between, corresponding to the desired angle +>Also at->To->There is->This also enables compression of the differences in the transmission angles of light rays of different angles of view in the waveguide substrate.
In practice, the refractive index of the dielectric layer is different from the refractive index of the waveguide substrate, and the refractive index of the dielectric layer is the same as or different from the refractive index of the grating structure.
In practice, the thickness and/or refractive index of the dielectric layer is adjusted to optimize the coupling-in efficiency and/or the coupling-out efficiency of the diffractive optical waveguide. Specifically, the thickness and/or refractive index of the dielectric layer is adjusted to increase the coupling-in-coupling-out efficiency by interference.
In particular implementations, the grating structure 110 has a grating height of 20-500nm and the dielectric layer 130 has a thickness of 50-300nm, for example. The waveguide substrate 120 has a thickness of 0.3-2 mm.
Still further in accordance with an aspect of the present application, embodiments of the present application provide a diffractive optical waveguide in which the refractive index anisotropy of the waveguide substrate satisfies anomalous dispersion conditions such that the refractive index value of the waveguide substrate is positively correlated with the wavelength of the image light.
Specifically, the long wavelength band corresponds to a larger refractive index, and the short wavelength band corresponds to a smaller refractive index. In this way, under the condition that the refractive indexes are the same, the diffraction angle corresponding to the longer wavelength is larger, and the diffraction angle corresponding to the shorter wavelength is smaller, namely, when the refractive indexes are positively correlated with the wavelengths of the image light, the diffraction angle of the long wave can be reduced, and the diffraction angle of the short wave is increased, so that the density difference of the image light rays with different wavelengths propagating in the waveguide is compensated, and the diffraction uniformity of the diffraction optical waveguide is improved.
According to an aspect of the present application, there is also provided an augmented reality display device including: projection light engine and diffractive optical waveguide as in any of the preceding claims. The projection light machine is used for emitting image light. The augmented reality display device may be embodied as an augmented reality eye or an augmented reality helmet, etc. The augmented reality display device provided by the application comprises the diffractive optical waveguide, and has the advantages of the diffractive optical waveguide.
The above embodiments do not limit the scope of the present application. It will be apparent to those skilled in the art that various modifications, combinations, sub-combinations and alternatives are possible, depending on design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the scope of the present application.

Claims (10)

1. The diffraction optical waveguide is characterized by comprising a waveguide substrate, a coupling-in grating and a coupling-out grating, wherein image light rays with a full field of view are coupled into the waveguide substrate through the coupling-in grating, are transmitted to the coupling-out grating in a total reflection mode, and are coupled out into human eyes through the coupling-out grating; the refractive index of the waveguide substrate is anisotropic and is rotationally symmetrically distributed, so that the expected angle range of the full-view image light entering the waveguide substrate is smaller than the reference angle range, and the angle range of the transmission angle of the full-view image light entering the waveguide substrate is further compressed; wherein the reference angle range is an angle range of a transmission angle after the image light of the full field enters the waveguide substrate when the refractive index of the waveguide substrate is isotropic, the expected angle range is an angle range of a transmission angle after the image light of the full field enters the waveguide substrate when the refractive index of the waveguide substrate is anisotropic and rotationally symmetric, and，/>refractive index value being the refractive index anisotropy of the waveguide substrate, < >>Is the refractive index value of the waveguide substrate that is isotropic in refractive index.
2. The diffractive optical waveguide according to claim 1, wherein the expected angles of the image light rays at each field angle after entering the waveguide substrate are smaller than the reference angles corresponding to each field angle, and the difference between the expected angles corresponding to each field and the reference angles is positively correlated with the reference angle corresponding to each field angle.
3. The diffractive optical waveguide according to claim 1, characterized in that the full field of view comprises a first partial angle of view and a second partial angle of view, for the image rays of the first partial angle of view:for image rays at a first partial angle of view: />The method comprises the steps of carrying out a first treatment on the surface of the The expected angle of the image light ray with the first part of the view angle after entering the waveguide substrate is larger than the corresponding reference angle, and the expected angle of the image light ray with the second part of the view angle after entering the waveguide substrate is smaller than the corresponding reference angle, wherein the reference angle corresponding to the first part of the view angle is smaller than the reference angle corresponding to the second part of the view angle.
4. The diffractive optical waveguide according to claim 1, characterized in that the refractive index anisotropy of the waveguide substrate and anomalous dispersion conditions are fulfilled such that the refractive index value of the waveguide substrate is positively correlated with the wavelength of the image light.
5. The diffractive optical waveguide according to claim 1, wherein the effective diffraction order of the image light rays entering the waveguide substrate after being diffracted by the coupling-in grating is split into a first beam and a second beam, the transmission angle of the first beam being the desired angle, the transmission angle of the second beam being different from the desired angle, wherein the optical axis is perpendicular or parallel to the plane of the waveguide substrate.
6. The diffractive optical waveguide according to claim 5, wherein the full field of view comprises a third partial angle of view and a fourth partial angle of view, the transmission angle of the second split of the image light entering the waveguide substrate at the third partial angle of view being greater than the desired angle, the transmission angle of the second split of the image light entering the waveguide substrate at the fourth partial angle of view being less than the desired angle, wherein the desired angle corresponding to the third partial angle of view is less than the desired angle corresponding to the fourth partial angle of view.
7. The diffractive optical waveguide according to claim 1, further comprising a dielectric layer between a grating structure and the waveguide substrate, the grating structure comprising the in-coupling grating and the out-coupling grating.
8. The diffractive optical waveguide according to claim 7, wherein the refractive index of the dielectric layer is different from the refractive index of the waveguide substrate, the refractive index of the dielectric layer being the same as or different from the refractive index of the grating structure.
9. The diffractive optical waveguide according to claim 7, characterized in that the thickness and/or refractive index of the dielectric layer is adjusted to optimize the coupling-in and/or coupling-out efficiency of the diffractive optical waveguide.
10. An augmented reality display device, the augmented reality display device comprising: projection optics and a diffractive optical waveguide according to any one of claims 1-9.
CN202311165701.6A 2023-09-11 2023-09-11 Diffraction optical waveguide and augmented reality display device Active CN116893470B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202311165701.6A CN116893470B (en) 2023-09-11 2023-09-11 Diffraction optical waveguide and augmented reality display device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202311165701.6A CN116893470B (en) 2023-09-11 2023-09-11 Diffraction optical waveguide and augmented reality display device

Publications (2)

Publication Number Publication Date
CN116893470A CN116893470A (en) 2023-10-17
CN116893470B true CN116893470B (en) 2023-11-28

Family

ID=88309760

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202311165701.6A Active CN116893470B (en) 2023-09-11 2023-09-11 Diffraction optical waveguide and augmented reality display device

Country Status (1)

Country Link
CN (1) CN116893470B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117631128B (en) * 2024-01-25 2024-04-05 上海鲲游科技有限公司 Diffraction optical waveguide and augmented reality display device

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1705908A (en) * 2003-03-19 2005-12-07 日本电信电话株式会社 Optical switch, optical modulator and variable wavelength filter
CN102681066A (en) * 2012-05-23 2012-09-19 天津大学 High-efficient wide-angle coupling grating
CN108107506A (en) * 2018-02-12 2018-06-01 福州大学 A kind of optical communicating waveband polymer waveguide grating coupler and preparation method thereof
CN114236819A (en) * 2021-12-29 2022-03-25 东南大学 Waveguide display two-dimensional pupil expanding method based on polarizer holographic grating
TW202244565A (en) * 2021-01-04 2022-11-16 美商元平台技術有限公司 Layered pupil-replicating waveguide
CN115356803A (en) * 2022-10-19 2022-11-18 北京驭光科技发展有限公司 Diffractive optical waveguide, design method thereof and near-to-eye display device

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9791696B2 (en) * 2015-11-10 2017-10-17 Microsoft Technology Licensing, Llc Waveguide gratings to improve intensity distributions

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1705908A (en) * 2003-03-19 2005-12-07 日本电信电话株式会社 Optical switch, optical modulator and variable wavelength filter
CN102681066A (en) * 2012-05-23 2012-09-19 天津大学 High-efficient wide-angle coupling grating
CN108107506A (en) * 2018-02-12 2018-06-01 福州大学 A kind of optical communicating waveband polymer waveguide grating coupler and preparation method thereof
TW202244565A (en) * 2021-01-04 2022-11-16 美商元平台技術有限公司 Layered pupil-replicating waveguide
CN114236819A (en) * 2021-12-29 2022-03-25 东南大学 Waveguide display two-dimensional pupil expanding method based on polarizer holographic grating
CN115356803A (en) * 2022-10-19 2022-11-18 北京驭光科技发展有限公司 Diffractive optical waveguide, design method thereof and near-to-eye display device

Also Published As

Publication number Publication date
CN116893470A (en) 2023-10-17

Similar Documents

Publication Publication Date Title
EP2979126B1 (en) Improvements in and relating to displays
US8934171B2 (en) Planar optical system for wide field-of-view polychromatic imaging
CN116893470B (en) Diffraction optical waveguide and augmented reality display device
CN111158153B (en) Near-to-eye display device and augmented reality equipment
US8760762B1 (en) Image waveguide utilizing two mirrored or polarized surfaces
EP3715935A1 (en) Substrate-guided optical device
KR20190015507A (en) Waveguide structure
GB2514658A (en) Improvements in and relating to displays
CN111788501B (en) Diffraction grating structure comprising a plurality of grating lines
TW201831959A (en) Method and system for high resolution digitized display
US11086128B2 (en) Methods and apparatuses for reducing stray light emission from an eyepiece of an optical imaging system
WO2019144596A1 (en) Optical waveguide structure and display device
TWI724732B (en) Waveguide device and optical engine
CN113433613A (en) Waveguide assembly, optical device and intelligent glasses
EP2784569A1 (en) Improvements in and relating to displays
CN217443725U (en) Optical-mechanical system
CN113433614A (en) Waveguide assembly, optical device and intelligent glasses
TWM615839U (en) Ultra short distance eyepiece system
CN215264107U (en) Waveguide assembly, optical device and intelligent glasses
TWI816370B (en) Optical system and aiming equipment
US20220276489A1 (en) Optical system and mixed reality device
JP2003050325A (en) Wavelength demultiplexer
CN113330349A (en) Optical waveguide lens and near-to-eye display device
EP4089466A1 (en) Waveguide
CN215264106U (en) Waveguide assembly, optical device and intelligent glasses

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant