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CN116699753A - Diffraction beam expander and display device - Google Patents

Diffraction beam expander and display device Download PDF

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Publication number
CN116699753A
CN116699753A CN202310681285.9A CN202310681285A CN116699753A CN 116699753 A CN116699753 A CN 116699753A CN 202310681285 A CN202310681285 A CN 202310681285A CN 116699753 A CN116699753 A CN 116699753A
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CN
China
Prior art keywords
diffractive
light
output
coupling structure
diffraction
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.)
Pending
Application number
CN202310681285.9A
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Chinese (zh)
Inventor
朱良富
朱以胜
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.)
Shenzhen Guangtu Display Technology Co ltd
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Shenzhen Guangtu Display Technology Co ltd
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Application filed by Shenzhen Guangtu Display Technology Co ltd filed Critical Shenzhen Guangtu Display Technology Co ltd
Priority to CN202310681285.9A priority Critical patent/CN116699753A/en
Publication of CN116699753A publication Critical patent/CN116699753A/en
Pending legal-status Critical Current

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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
    • 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
    • G02B6/0023—Means for improving the coupling-in of light from the light source into the light guide provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
    • G02B6/0026—Wavelength selective element, sheet or layer, e.g. filter or grating
    • 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
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0055—Reflecting element, sheet or layer

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)

Abstract

The application provides a diffraction beam expanding device and display equipment, and relates to the technical field of virtual display, comprising a waveguide plate, wherein the waveguide plate comprises a first main surface and a second main surface which are parallel to each other; a diffraction input coupling structure for coupling input light into the waveguide plate to form guided light, and a diffraction output coupling structure for diffracting the extended guided light to form output light emission are formed on the waveguide plate; the reflection element is positioned on the waveguide plate and corresponds to the position of the diffraction output coupling structure and is used for reflecting part of output light emitted by diffraction of the diffraction output coupling structure; a portion of the output light reflected by the reflective element and another portion of the output light output by the diffractive outcoupling structure are both single-sided output from the first or second major surface of the waveguide plate. By reflecting the image light transmitted to one principal plane of the waveguide plate to another principal plane, unidirectional output of the image light is realized, and display brightness and privacy are improved.

Description

Diffraction beam expander and display device
Technical Field
The application relates to the technical field of virtual display, in particular to a diffraction beam expanding device and display equipment.
Background
A known display device (fig. 10) comprises an optical engine ENG1 and a diffractive beam expander EPE0. The display device may display a virtual image by diffractively expanding the light beam provided by the optical engine ENG1. The diffractive beam expander device EPE0 provides an enlarged BOX1 for viewing the virtual image displayed. The diffraction beam expander EPE0 diffracts and expands the beam of the input light IN1 to form the output light OUT1. When the output light beam of the output light OUT1 is irradiated to the EYE1 of the viewer, the viewer can see the virtual image displayed.
The known output coupling element DOEX can couple the light beam B3 through the first main surface SRF1 of the waveguide plate SUB0 P1,T-1 Diffraction to the intended viewer EYE1. However, some known output coupling elements DOEX may also diffract the output beam B3 through the second main surface SRF2 of the waveguide plate SUB0 P1,R-1 . Diffraction of guided wave light by the second main surface SRF2 may reduce the brightness of the virtual image displayed to the BOX 1. In addition, light diffracted by the second major surface SRF2 is directed away from the BOX1 and cannot be observed by the intended first observer, but may impinge on the EYE2 of the second observer. Diffraction of guided wave light by the second major surface SRF2 may also allow viewing of the displayed virtual image from the second BOX 2. The light diffracted into the second BOX2 may interfere with the second viewer and/or may reveal confidential information to the second viewer.
Disclosure of Invention
The embodiment of the application aims to provide a diffraction beam expanding device and display equipment, which can realize unidirectional output of image light, improve image brightness and realize privacy protection.
In one aspect of an embodiment of the present application, there is provided a diffraction beam expanding device, including a waveguide plate including a first main surface and a second main surface parallel to each other; a diffraction input coupling structure for coupling input light into the waveguide plate to form guided light and a diffraction output coupling structure for diffractively expanding the guided light to form output light;
the reflecting element is positioned on the waveguide plate and corresponds to the position of the diffraction output coupling structure and is used for reflecting part of the output light which is diffracted and emitted by the diffraction output coupling structure; a portion of the output light reflected by the reflective element and another portion of the output light output by the diffractive outcoupling structure are both single-sided output from the first or second major surface of the waveguide plate.
Optionally, the diffractive in-coupling structure and the diffractive out-coupling structure are located inside the waveguide plate or on the first major surface or on the second major surface.
Optionally, the reflective element is located on the first major surface or the second major surface.
Optionally, the projection of the reflective element covers the projection of the diffractive outcoupling structure in a direction from the first main surface to the second main surface.
Optionally, the projection of the reflective element covers the projection of the diffractive in-coupling structure and the diffractive out-coupling structure in a direction from the first main surface to the second main surface.
Optionally, the reflective element comprises a multilayer dielectric reflective film plated on the first major surface or the second major surface of the waveguide plate.
Optionally, the reflective element has a reflectivity of at least 50% for the visible light band.
Optionally, an intermediate diffractive coupling structure is further included, the intermediate diffractive coupling structure being located on the waveguide plate between the diffractive in-coupling structure and the diffractive out-coupling structure;
the intermediate diffraction coupling structure is used for diffracting and expanding guided wave light formed by diffraction of the diffraction input coupling structure to form second guided wave light, and the second guided wave light passes through the diffraction output coupling structure to form output light.
Optionally, the intermediate diffractive coupling structure is located inside the waveguide plate or on the first major surface or on the second major surface.
In another aspect of the embodiment of the present application, there is provided a display apparatus including: the device comprises an optical engine for emitting input light and the diffraction beam expander arranged on the light emitting side of the optical engine.
According to the diffraction beam expanding device and the display device provided by the embodiment of the application, the diffraction input coupling structure couples input light into the waveguide plate to form guided light, the waveguide plate distributes the guided light to the diffraction output coupling structure in a guiding way, and the diffraction output coupling structure diffracts the guided light out of the waveguide plate to form output light. When an output beam of output light impinges on the user's eye, the user may observe a virtual image that is displayed; coupling in and coupling out of the initial image light are realized in a grating diffraction mode, so that an expanded image light beam is formed; the reflecting element reflects the image light transmitted to one main plane of the waveguide plate to the other main plane, so that the unidirectional output of the image light is realized, the display brightness and the privacy are improved, and in addition, the power consumption of the optical engine can be reduced by coupling output of a single side.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and should not be considered as limiting the scope, and other related 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 diffraction beam expander according to the present embodiment;
FIG. 2 is a schematic diagram of a diffraction beam expander according to the second embodiment;
FIG. 3 is a third schematic diagram of the diffraction beam expander according to the present embodiment;
FIGS. 4 a-4 e are schematic diagrams illustrating different states of an input image of the diffraction beam expander according to the present embodiment;
fig. 5 is a schematic diagram of an optical path of the diffraction beam expander according to the present embodiment;
FIG. 6 is a schematic diagram of a waveguide structure of the diffraction beam expander according to the present embodiment;
FIG. 7 is a second schematic diagram of a waveguide structure of the diffraction beam expander according to the present embodiment;
FIG. 8 is a third schematic view of a waveguide structure of the diffraction beam expander according to the present embodiment;
FIG. 9 is a diagram showing a waveguide structure of a diffraction beam expander according to the fourth embodiment;
fig. 10 is a schematic diagram of a prior art structure.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application.
In the description of the present application, it should be noted that, the azimuth or positional relationship indicated by the terms "inner", "outer", etc. are based on the azimuth or positional relationship shown in the drawings, or the azimuth or positional relationship that is commonly put in use of the product of this application, are merely for convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element to be referred to must have a specific azimuth, be configured and operated in a specific azimuth, and therefore should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like, are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.
It should also be noted that the terms "disposed," "coupled," and "connected" are to be construed broadly, and may be, for example, fixedly coupled, detachably coupled, or integrally coupled, unless otherwise specifically defined and limited; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present application will be understood in specific cases by those of ordinary skill in the art.
The embodiment of the application provides a diffraction beam expander EPE1, which mainly solves the problems of low brightness and privacy leakage of a single main plane image caused by the fact that a conventional output coupling element DOEX of the diffraction beam expander EPE0 diffracts output images to two main planes of a waveguide plate SUB0 at the same time in the background art.
Specifically, referring to fig. 1, a diffraction beam expander EPE1 provided in an embodiment of the present application includes a waveguide plate SUB1, where the waveguide plate SUB1 includes a first main surface SRF1 and a second main surface SRF2 parallel to each other; a diffraction input coupling structure DOE1 for coupling the input light IN1 into the waveguide plate SUB1 to form the guided light (B1, B2), and a diffraction output coupling structure DOE3 for diffracting the extended guided light (B1, B2) to form the output light OUT1 are formed on the waveguide plate SUB 1;
a reflection element REFF, which is located on the waveguide plate SUB1 and corresponds to the position of the diffractive output coupling structure DOE3, and is used for reflecting part of the output light OUT1 emitted by the diffractive output coupling structure DOE3; the part of the output light OUT1 reflected by the reflective element REFF and the other part of the output light OUT1 output by the diffractive outcoupling structure DOE3 are both output on one side from the first main surface SRF1 or the second main surface SRF2 of the waveguide plate SUB1.
The diffraction beam expander EPE1 is configured to expand the input light IN1 by diffraction to form output light OUT1, and an optical engine ENG1 is disposed at one side of the diffraction beam expander EPE1, and the optical engine ENG1 can provide the input light IN1; wherein the input light IN1 comprises a plurality of input light beams (B0 P1 ，B0 P2 ) The output light OUT1 comprises a plurality of corresponding output light beams (B3 P1 ，B3 P2 )。
The waveguide plate SUB1 comprises a first main surface SRF1 and a second main surface SRF2, and a diffractive input coupling structure DOE1 and a diffractive output coupling structure DOE3 are also formed on the waveguide plate SUB1, the diffractive input coupling structure DOE1 being used for coupling input light IN1 into the waveguide plate SUB 1; the diffractive outcoupling structure DOE3 forms the output light OUT1 by diffracting the guided light (B1, B2) from the waveguide plate SUB1.
Illustratively, the waveguide plate SUB1 includes a planar waveguide core; in one embodiment, the waveguide plate SUB1 may optionally include, for example, one or more cladding layers, one or more protective layers, and/or one or more mechanical support layers. Height h S The thickness of the planar waveguide core of the waveguide plate SUB1 may be expressed.
The waveguide plate SUB1 may comprise or consist essentially of a transparent solid material. The waveguide plate SUB1 may include, for example, glass, polycarbonate, or polymethyl methacrylate (PMMA). The diffractive optical structure may be formed, for example, by molding, embossing, and/or etching.
The reflection element REFF is configured to reflect the output light OUT1 (image light) diffracted by the diffractive outcoupling structure DOE3 toward the first main surface SRF1 or the second main surface SRF2, so that all the image light is output from the second main surface SRF2 or the first main surface SRF1 on one side, improving the image brightness and realizing privacy protection.
The position of the reflective element REFF needs to correspond to the position of the out-coupling structure in order to receive and reflect the image light diffracted by the diffractive out-coupling structure DOE3 towards the first main surface SRF1 or the second main surface SRF2.
In one realisation of the application, the reflective element REFF may be arranged in a different plane than the diffractive out-coupling structure DOE3. For example, when the diffractive outcoupling structure DOE3 is located inside the waveguide plate SUB1, the reflective element REFF may be located on the first main surface SRF1 or the second main surface SRF2, in other words, the reflective element REFF is in gapless contact with the first main surface SRF1 or the second main surface SRF2 of the waveguide plate SUB 1; when the diffractive outcoupling structure DOE3 is located on the first main surface SRF1 of the waveguide plate SUB1, the reflective element REFF is located on the second main surface SRF2 of the waveguide plate SUB1 at a position corresponding to the diffractive outcoupling structure DOE3; when the diffractive outcoupling structure DOE3 is located on the second main surface SRF2 of the waveguide plate SUB1, the reflective element REFF is located on the first main surface SRF1 of the waveguide plate SUB1 at a position corresponding to the diffractive outcoupling structure DOE3.
In another realisable form of the application, the reflective element REFF may also be arranged in the same plane as the diffractive out-coupling structure DOE3. For example, when the diffractive outcoupling structure DOE3 is located on the first main surface SRF1 of the waveguide plate SUB1, the reflective element REFF is located on the first main surface SRF1 of the waveguide plate SUB1 in the same area as the diffractive outcoupling structure DOE3 and covers the diffractive outcoupling structure DOE3; when the diffractive outcoupling structure DOE3 is located on the second main surface SRF2 of the waveguide plate SUB1, the reflective element REFF is located on the second main surface SRF2 of the waveguide plate SUB1 in the same area as the diffractive outcoupling structure DOE3 and covers the diffractive outcoupling structure DOE3.
A view box, which is a spatial region in which the user's eye can see the displayed virtual image, is also provided in the outgoing direction of the output light OUT1. When the eye is outside the view box, the user cannot see the displayed image or cannot see the complete image.
The principle of the diffraction beam expander EPE1 of the present application is shown IN fig. 1, IN which the optical engine ENG1 forms the input light IN1, and the diffraction beam expander EPE1 forms the output light OUT1 by diffracting and expanding the input light IN 1.
Optical engine ENG1 may provide input light IN1 including a plurality of input light beams B0 P1 、B0 P2 Which represent image points P1, P2 of the input image IMG0. The input light IN1 comprises a plurality of input light beams B0 transmitted IN different directions P1 、B0 P2 Which corresponds to image points P1, P2 of the input image IMG0 (fig. 2).
The diffraction beam expander EPE1 includes a waveguide plate SUB1, and a diffraction input coupling structure DOE1 and a diffraction output coupling structure DOE3 are formed on the waveguide plate SUB1. The diffraction beam expander EPE1 can receive the input light IN1 from the optical engine ENG 1; the diffractive input coupling structure DOE1 may receive the input light IN1, the diffractive input coupling structure DOE1 forms guided light (B1, B2) by diffracting the input light IN1, the input coupled light may propagate IN the waveguide plate SUB1 IN the form of guided light (B1, B2), the guided light (B1, B2) may be confined within the waveguide plate SUB1 by Total Internal Reflection (TIR), the diffractive output coupling structure DOE3 forms output light OUT1 by diffracting the guided light (B1, B2) from the waveguide plate SUB 1; the output light OUT1 comprises a plurality of output light beams B3 corresponding to the image points P1, P2 of the input image IMG0.
For example, the input light IN1 may comprise an input beam B0 corresponding to the image points P1, P2 P1 、B0 P2 . The diffractive input coupling structure DOE1 can pass the diffractive input beam B0 P1 To form the guided wave light B1 P1 . The diffractive input coupling structure DOE1 can pass the diffractive input beam B0 P2 To form the guided wave light B1 P2 。
The waveguide plate SUB1 has a first main surface SRF1 and a second main surface SRF2. The diffractive input coupling structure DOE1 couples input light IN1 into the waveguide plate SUB1 via the first main surface SRF1 and the second main surface SRF2. The diffractive outcoupling structure DOE3 diffracts the guided light (B1, B2) out of the waveguide plate SUB1 through the first main surface SRF1 and the second main surface SRF2.
Further, the diffractive in-coupling structures DOE1 and DOE3 are located inside the waveguide plate SUB1 or on the first main surface SRF1 or on the second main surface SRF2. And the reflective element REFF is located on the first main surface SRF1 or on the second main surface SRF2.
As shown in fig. 1, the diffractive outcoupling structure DOE3 in fig. 1 is located on the first main surface SRF1 and the reflective element REFF is located on the second main surface SRF2. The diffractive outcoupling structure DOE3 can diffract guided light B1 corresponding to the P1 image point P1 Forming a first output beam B3 output from the first main surface SRF1 P1，T-1 And a relay beam B3 propagating to the second main surface SRF2 P1，R-1 A relay beam B3 propagating to the second main surface SRF2 P1，R-1 Reflected by a reflecting element REFF located at the second main surface SRF2, forms a second output beam B3 'corresponding to the P1 image point output from the first main surface SRF 1' P1，R-1 . First output beam B3 P1，T-1 And a second output beam B3' P1，R-1 The propagation directions are the same; first output beam B3 P1，T-1 And a second output beam B3' P1，R-1 Together, the output light OUT1 is composed.
When the output light OUT1 is irradiated to the EYE1 of the viewer, the viewer can see the displayed virtual image point P1. When the first output beam B3 P1，T-1 And a second output beam B3' P1，R-1 Upon illumination within the BOX1 of the display device 500, the viewer can see the displayed image point P1. As output beam B3 P2、T-1 And B3' P2、R-1 Upon illumination within the BOX1 of the display device 500, the viewer can see the displayed image point P2. When the output light OUT1 corresponding to all the image points on the image is irradiated into the BOX1 of the display device 500, the viewer can see the displayed full image virtual image VIMG1. When the EYE1 of the viewer is within the BOX1 of the display device 500, the viewer can see the virtual image VIMG1 displayed.
In the above embodiment, the diffractive beam expander EPE1 is implemented only by the diffractive input coupling structure DOE1 and the diffractive output coupling structure DOE3. The diffractive beam expanding device EPE1 may comprise a diffractive in-coupling structure DOE1 to form the first guided light B1, wherein the diffractive OUT-coupling structure DOE3 may be arranged to form the output light OUT1 by diffracting the first guided light B1 OUT of the waveguide plate SUB1.
On the basis, the diffraction beam expanding device EPE1 further comprises at least one intermediate diffraction coupling structure DOE2, the intermediate diffraction coupling structure DOE2 is positioned on the waveguide plate SUB1 and between the diffraction input coupling structure DOE1 and the diffraction output coupling structure DOE3, the intermediate diffraction coupling structure DOE2 is used for diffracting and expanding the first guided light B1 formed by the diffraction input coupling structure DOE1 to form second guided light B2, and the second guided light B2 forms output light OUT1 through the diffraction output coupling structure DOE3.
Referring to fig. 2, the diffractive beam expanding device EPE1 may optionally comprise one or more intermediate diffractive coupling structures DOE2 located in the optical path between the diffractive in-coupling structures DOE1 and the diffractive out-coupling structures DOE3. The intermediate diffractive coupling structure DOE2 serves as a diffractive expansion structure for diffracting the expanded guided wave light.
The diffractive input coupling structure DOE1 may form the first guided light B1 by diffracting the input light IN1, the intermediate diffractive coupling structure DOE2 may form the second guided light B2 by diffracting the first guided light B1, and the diffractive output coupling structure DOE3 may form the output light OUT1 by diffracting the second guided light B2. When the output light OUT1 is irradiated onto the EYE1, the EYE1 of the viewer can see the virtual image VIMG1 displayed.
Further, a plurality of diffractive input coupling structures DOE1, intermediate diffractive coupling structures DOE2, and a plurality of diffractive output coupling structures DOE3 are formed on the waveguide plate SUB1 for controlling the propagation direction of light in the optical path.
The diffractive beam expander device EPE1 may further comprise a set of diffractive input coupling structures DOE1, intermediate diffractive coupling structures DOE2 and diffractive output coupling structures DOE3 for controlling the propagation direction of the output light beam in the output light OUT1.
Illustratively, four diffractive structures, one diffractive input coupling structure DOE1, two intermediate diffractive coupling structures DOE2, and one diffractive output coupling structure DOE3, are formed on the waveguide plate SUB1 for controlling the direction of the output light beam. The four diffractive structures may be positioned to define an optical path from the diffractive in-coupling structure DOE1 to the diffractive out-coupling structure DOE3.
The diffractive input coupling structure DOE1 may form the first guided light B1 by diffracting the input light IN1, the intermediate diffractive coupling structure DOE2 may form the extended second guided light B2 by diffracting the first guided light B1, the additional intermediate diffractive coupling structure DOE2 may form the additional extended third guided light by diffracting the extended second guided light B2, and the diffractive output coupling structure DOE3 may form the output light OUT1 by diffracting the additional extended third guided light OUT of the waveguide plate SUB1.
SX, SY, and SZ represent orthogonal directions, and the first major surface SRF1 may be in a plane defined by the directions SX and SY; the second major surface SRF2 may be parallel to the first major surface SRF 1.
As shown in fig. 3, the diffractive outcoupling structure DOE3 may have a length L, e.g. in SX DOE3 And the diffractive outcoupling structure DOE3 may have a width W in e.g. the SY direction DOE3 . Length L of output beam OUT1 Can be less than or equal to the length L of the diffractive out-coupling structure DOE3 DOE3 . Width W of output beam OUT1 Can be smaller than or equal to the width W of the diffraction out-coupling structure DOE3 DOE3 。
Fig. 3 shows by way of example the dimensions of the diffraction beam expander EPE 1; the diffractive beam expander device EPE1 may comprise a set of diffractive structures for controlling the direction of the output light beam; the diffraction beam expanding device EPE1 may include a diffraction structure constructed on the waveguide plate SUB 1; the diffraction beam expanding device EPE1 can comprise a diffraction input coupling structure DOE1, an intermediate diffraction coupling structure DOE2 and a diffraction output coupling structure DOE3; the set of constituent structures may include a diffractive out-coupling structure DOE3.
The diffractive input coupling structure DOE1 may have a grating period d 1 . The diffractive input coupling structure DOE1 can be implemented as a diffraction grating G1 having a grating period Λ 1 . The grating G1 includes a diffraction feature F1, the grating G1 having a grating vector V1. The direction of the grating vector V1 may be specified, for example, by an angle φ 1 . The direction of the grating vector V1 may be specified, for example with respect to the direction SY, or with respect to the direction-SY, which is opposite to the direction SY. Diffraction in-coupling structure DOE1 may have a width W DOE1 (e.g., in the SY direction).
The intermediate diffractive coupling structure DOE2 may have a grating period d2. The intermediate diffractive coupling structure DOE2 may be implemented as a diffraction grating G2 having a grating period Λ 2 . The grating G2 includes a diffraction feature F2, the grating G2 having a grating vector V2. The direction of the grating vector V2 may be defined by an angle phi 2 And (5) designating. The intermediate diffractive coupling structure DOE2 may have a width W DOE2 (e.g., in the SY direction).
The grating period of the diffractive output coupling structure DOE3 may be Λ 3 The diffractive outcoupling structure DOE3 may be implemented as a diffraction grating G3 having a grating period Λ 3 . The grating G3 has a grating vector V3. The direction of the grating vector V3 may be defined by an angle phi 3 And (5) designating. The output element DOE3 may have a width W DOE3 (e.g., in the SY direction). The diffractive outcoupling structure DOE3 may have a length L DOE3 (e.g., in the SX direction).
The magnitude of the grating vector depends on the grating period of the diffraction grating of the diffraction structure, and the direction of the grating vector depends on the orientation of the diffraction grating. For example, the magnitude of the grating vector V1 depends on the grating period Λ of the diffractive input coupling structure DOE1 1 . The magnitude of the grating vector V2 depends on the grating period Λ of the intermediate diffractive coupling structure DOE2 2 . The magnitude of the grating vector V3 depends on the grating period Λ of the diffractive output coupling structure DOE3 3 。
The diffractive beam expander EPE1 can be designed such that the vector sum of the grating vectors of the diffractive structures in the optical path is zero (v1+v2+v3=0) so as to ensure that each beam B3 coupled out by the diffractive output coupling structure DOE3 P1 、B3 P2 And a corresponding input beam B0 obtained from optical engine ENG1 P1 、B0 P2 Parallel.
The diffractive in-coupling structure DOE1 may be implemented on the first main surface SRF1, on the second main surface SRF2 or inside the waveguide plate SUB 1; the intermediate diffractive coupling structure DOE2 may be implemented on the first main surface SRF1, on the second main surface SRF2 or inside the waveguide plate SUB 1; the diffractive outcoupling structures DOE3 may be implemented on the first main surface SRF1, on the second main surface SRF2 or inside the waveguide plate SUB1, which may be chosen according to practical needs.
The diffractive structure may be processed by, for example, photolithographic techniques. For example, one or more imprint template tools may be fabricated by electron beam lithography, and the diffraction grating may be formed using the one or more imprint template tools.
In one embodiment of the application, the diffractive in-coupling structure DOE1, the intermediate diffractive out-coupling structure DOE2 and the diffractive out-coupling structure DOE3 are all located at the first main surface SRF1 or the second main surface SRF2 of the waveguide plate SUB1.
The diffractive input, intermediate and diffractive output coupling structures DOE1, DOE2, DOE3 are realized on the same main surface of the waveguide plate SUB1 in order to manufacture the diffractive input, intermediate and diffractive output coupling structures DOE1, DOE2, DOE3 by embossing.
Whereas for the reflective element REFF, as shown in fig. 6, in one embodiment of the application, the projection of the reflective element REFF covers the projection of the diffractive out-coupling structure DOE3 in the direction of the first main surface SRF1 to the second main surface SRF2.
In other words, the area of the reflective element REFF is preferably larger than or equal to the area of the diffractive outcoupling structure DOE3, so as to reflect all image light diffracted by the diffractive outcoupling structure DOE3 towards the first main surface SRF1 or the second main surface SRF2. By the arrangement, the single-sided output of all image lights can be realized, and the waveguide plate SUB1 is simple in structure and convenient to implement.
In another embodiment, the projection of the reflective element REFF covers the projections of the diffractive in-coupling structure DOE1 and the diffractive out-coupling structure DOE3 in the direction of the first main surface SRF1 to the second main surface SRF2.
As shown in fig. 7, when the projection of the reflective element REFF covers both the diffractive input-coupling structure DOE1 and the diffractive output-coupling structure DOE3, the optical coupling efficiency of the input-coupling element can be improved, and the image brightness can be further improved.
In fig. 8, the diffractive outcoupling structure DOE3 is located inside the waveguide plate SUB1, and the projection of the reflective element REFF also covers the projection of the diffractive outcoupling structure DOE3 in the direction along the first main surface SRF1 to the second main surface SRF2.
It is also possible that in fig. 9 the reflective element REFF and the diffractive outcoupling structure DOE3 are located on the same main surface, and that the reflective element REFF covers the diffractive outcoupling structure DOE3. When the reflection element REFF is directly covered on the diffraction output coupling structure DOE3, only a single diffraction output exists in the diffraction output coupling structure DOE3, and the effect of single-sided image output is realized.
Further, the reflective element REFF includes a multilayer dielectric reflective film plated on the first main surface SRF1 or the second main surface SRF2 of the waveguide plate SUB1.
The reflection element REFF may be a multilayer dielectric reflection film which is vapor-deposited or adhered on one of the main surfaces of the waveguide plate SUB1, the multilayer dielectric reflection film including film layers having different refractive indices alternately stacked. In addition, the reflective element REFF may be a metal reflective film. It may have a length L on, for example, SX REFF And the reflective element REFF may have a width W in e.g. the SY direction REFF . Length L of reflective element REFF REFF May preferably be greater than or equal to the width W of the diffractive outcoupling structure DOE3 DOE3 . Width W of reflective element REFF REFF May preferably be greater than or equal to the width W of the diffractive outcoupling structure DOE3 DOE3 。
Furthermore, the reflective element REFF has a reflectivity of at least 50% for the visible light band.
The reflective element REFF may have a high reflectivity for the visible light band, which may be light having a wavelength in the range of 400nm to 700 nm. The reflective element REFF may have, for example, a reflectivity of more than 99% or a reflectivity of more than 90% or a reflectivity of more than 80% or a reflectivity of more than 50% for light in the wavelength range of 400nm to 700 nm. Due to the high reflectivity of the reflective element REFF in the visible light band, the area of the waveguide plate SUB1 in contact with the reflective element REFF is opaque or has a low transmittance.
While for the optical engine ENG1 as the image generation unit, the optical engine ENG1 may include, for example, oneOr a plurality of Light Emitting Diodes (LEDs); as shown in fig. 2, optical engine ENG1 may also include a display element DISP1 to form an input image IMG0; optical engine ENG1 may also include optics LNS1 to form input beam B0 from light at image points P1, P2 of input image IMG0 P1 、B0 P2 . Input beam B0 P1 、B0 P2 Can have a width W IN1 . The output beam may have a width W OUT1 Width W OUT1 Can be greater than the width W IN1 The diffraction beam expander EPE1 can form the output light OUT1 by diffracting the expanded input light IN 1.
Further, the display DISP1 may comprise a two-dimensional array of light emitting display pixels; the display DISP1 may include, for example, one or more micro-display imagers, such as Liquid Crystal On Silicon (LCOS), liquid Crystal Displays (LCDs), digital Micromirror Devices (DMDs). The display DISP1 may generate an input image IMG0, for example, with a resolution of 1280×720 (HD). Display DISP1 may generate input image IMG0, for example, at a resolution of 1920 x 1080 (full high definition). The display DISP1 may generate an input image IMG0, for example with a resolution of 3840 x 2160 (4K UHD). The input image IMG0 may comprise a plurality of image points P0, P1, P2.
In addition, optical engine ENG1 may include collimating optics LNS1 to form a beam from each image pixel, and optical engine ENG1 may include collimating optics LNS1 to form a substantially collimated beam from the light of the image point.
Referring again to fig. 4 a-4 e, optical engine ENG1 may form input light IN1, which represents input image IMG0. The optical engine ENG1 may form an input image IMG0 and may convert the input image IMG0 into a plurality of light beams B0 of the input light IN1 P1 、B0 P2 . The input light IN1 may include a plurality of input light beams (B0) representing an input image IMG0 P1 、B0 P2 ). Optical engine ENG1 may include a display DISP1 to generate an input image IMG0, and input image IMG0 may include a plurality of image points P1, P2 arranged in a two-dimensional array. The optical engine ENG1 may include collimating optics LNS1 to form a plurality of input light beams (B0) from image points P1, P2 of the input image IMG0 P1 、B0 P2 )。
The input image IMG0 may include a center point P0 and four corner points P1, P2, P3, P4. P1 may represent an upper left corner, P2 may represent an upper right corner, P3 may represent a lower left corner, P4 may represent a lower right corner, and the input image IMG0 may include graphic characters "F", "G", and "H", for example. The input image IMG0 may represent displayed information.
The input image IMG0 may be a single-color image or a multi-color image. The input image IMG0 may be, for example, an RGB image, and may include a red (R) partial image, a green (G) partial image, and a blue (B) partial image. The input image IMG0 may form light obtained from one or more light emitting diodes, for example, by modulating a laser or by modulating.
Optical engine ENG1 may provide input light IN1, which may include a plurality of substantially collimated light beams B0 P0 、B0 P1 、B0 P2 、B0 P3 、B0 P4 . Light B0 at center point P0 P0 May propagate in the direction of the optical axis AX0 of the optical engine ENG1.
Referring to fig. 5, the virtual image VIMG1 is shown to have a center point P0' and four corner points P1', P2', P3', P4'. The input light IN1 may include a plurality of partial light beams corresponding to points P0, P1, P2, P3, P4 of the input image IMG0. The diffraction beam expander EPE1 may form the point P0' of the displayed virtual image VIMG1, by diffracting and guiding the light of the point P0 of the input image IMG0. The diffractive beam expanding device EPE1 can form points P1', P2', P3', P4' by diffracting and directing light of the points P1, P2, P3, P4, respectively.
The output light OUT1 may comprise a plurality of output light beams B3 P0 、B3 P1 、B3 P2 、B3 P3 、B3 P4 . The diffractive outcoupling structure DOE3 of the diffractive beam expander EPE1 can form the output beam B3 by diffracting the guided light (B1, B2) from the waveguide plate SUB1 P0 、B3 P1 、B3 P2 、B3 P3 、B3 P4 . The diffractive outcoupling structure DOE3 is arranged to couple light by transmitting the diffraction order (T -1 ) Or-1 st reflection diffraction order (R -1 ) Diffraction of the guided light (B1, B2) to form an output beam B3 P0 、B3 P1 、B3 P2 、B3 P3 、B3 P4 。
Output beam B3 P0 May be formed by the light of the input beam B0P0, which corresponds to the image point P0 of the input image IMG0. Output beam B3 P0 It may appear to originate from point P0' of virtual image VIMG1.
Output beam B3 P0 May correspond to the image point P0 of the input image IMG0, and the image point P0' of the virtual image VIMG1. Output beam B3 P1 May correspond to the image point P1 of the input image IMG0, and the image point P1' of the virtual image VIMG1. Output beam B3 P2 May correspond to the image point P2 of the input image IMG0 and the image point P2' of the virtual image VIMG1. Output beam B3 P3 May correspond to the image point P3 of the input image IMG0 and the image point P3' of the virtual image VIMG1. Output beam B3 P4 May correspond to the image point P4 of the input image IMG0 and the image point P4' of the virtual image VIMG1.
The input image IMG0 may represent displayed information; the input image IMG0 may represent, for example, graphics and/or text; the input image IMG0 may represent, for example, video. Engine ENG1 may be arranged to generate still images and/or video; engine ENG1 may generate a real primary image IMG0 from the digital image; engine ENG1 may receive one or more digital images, for example from an internet server or a smart phone.
On the other hand, the embodiment of the application also discloses a display device 500, which comprises an optical engine ENG1 for emitting input light IN1, and a diffraction beam expanding device EPE1 arranged on the light emitting side of the optical engine ENG1.
The optical engine ENG1, i.e. the projector, may provide an input light IN1 comprising a plurality of input light beams corresponding to the input image points; the input light beam propagates in different directions corresponding to image points of the input image. The intensity of the input light beam corresponds to the brightness of the image point of the input image.
The display device 500 further comprises a diffractive beam expanding means EPE1 for expanding the input light IN 1. The diffractive beam expanding device EPE1 comprises a waveguide plate SUB1, a diffractive input coupling structure DOE1, one or more optional intermediate diffractive coupling structures DOE2, a diffractive output coupling structure DOE3, and a reflective element REFF located on a certain principal plane of the waveguide plate SUB1 corresponding to the diffractive output coupling structure DOE3.
The diffraction input coupling structure DOE1 couples the input light IN1 into the waveguide plate SUB1 to form the guided light, and the waveguide plate SUB1 guides and distributes the guided light (B1 and B2) to the diffraction output coupling structure DOE3; the diffractive output coupling structure DOE3 forms the output light OUT1 by diffracting the guided wave light OUT of the waveguide plate SUB1. When the output light beam of the output light OUT1 is irradiated onto the eyes of the user, the user can observe the displayed virtual image. The diffraction beam expander EPE1 forms an output beam by diffraction expanding an input beam.
The display device 500 may be used for displaying virtual images, the display device 500 may be used for displaying as an augmented reality, the user may observe the displayed virtual images and real objects simultaneously, looking through the diffractive out-coupling structure DOE3 of the display device 500. In addition, the display device 500 may also be used as a head-up display for a vehicle.
The reflection element REFF may reflect the image light diffracted by the diffractive outcoupling structure DOE3 to the principal plane in which the reflection element REFF is located to another principal plane opposite thereto, and output together with the image light diffracted by the diffractive outcoupling structure DOE3 to the other principal plane. The single-sided coupling-out may reduce the power consumption of the optical engine ENG1, since most of the guided light may be coupled out of the waveguide plate SUB1 towards the intended observer.
The display apparatus 500 based on the diffractive beam expander EPE1 (diffractive optical waveguide) includes an optical engine ENG1 as an image generating unit for generating initial image light (input light IN 1) to be displayed; the beam expanding device realizes coupling in, beam expanding and coupling OUT of the initial image light in a grating diffraction mode to form an expanded image light beam (output light OUT 1); the reflection element REFF reflects the image light transmitted to one main plane of the diffraction beam expander EPE1 to the other main plane, thereby realizing unidirectional output of the image light and improving display brightness and privacy.
The display device 500 may include a diffraction beam expander EPE1 and an optical engine ENG1 when delivered to a user. However, optical engine ENG1 may be a replaceable component of display device 500. The display device 500 may also be delivered to the user without the optical engine ENG1. The beam expanding device EPE1 and the light engine ENG1 may be delivered to a user, respectively, and the user may mount the light engine ENG1 on the display apparatus 500.
In an application scenario of the present application, the display device 500 may be configured for use with, for example, a virtual reality display (VR), an augmented reality display (AR), and/or a heads-up display (HUD) on a vehicle. For example, when the display device 500 is applied to a vehicle, the vehicle may include the display device 500 for displaying the virtual image VIMG1 to a user of the vehicle.
The display apparatus 500 includes the same structure and advantageous effects as those of the diffraction beam expander EPE1 in the foregoing embodiment. The structure and the beneficial effects of the diffraction beam expander EPE1 are described in detail in the foregoing embodiments, and are not described in detail herein.
The above description is only an example of the present application and is not intended to limit the scope of the present application, and various modifications and variations will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims (10)

1. A diffraction beam expander device, comprising:
a waveguide plate including a first main surface and a second main surface parallel to each other; a diffraction input coupling structure for coupling input light into the waveguide plate to form guided light and a diffraction output coupling structure for diffractively expanding the guided light to form output light;
the reflecting element is positioned on the waveguide plate and corresponds to the position of the diffraction output coupling structure and is used for reflecting part of the output light which is diffracted and emitted by the diffraction output coupling structure; a portion of the output light reflected by the reflective element and another portion of the output light output by the diffractive outcoupling structure are both single-sided output from the first or second major surface of the waveguide plate.
2. The diffractive beam expanding device according to claim 1, wherein the diffractive in-coupling structure and the diffractive out-coupling structure are located inside the waveguide plate or on the first or second main surface.
3. The diffractive beam expander device according to claim 2, wherein the reflective element is located on the first main surface or the second main surface.
4. A diffractive beam expander according to claim 3, wherein the projection of the reflective element covers the projection of the diffractive outcoupling structure in the direction of the first main surface to the second main surface.
5. A diffractive beam expander according to claim 3, wherein the projection of the reflective element covers the projections of the diffractive in-coupling structure and the diffractive out-coupling structure in the direction from the first main surface to the second main surface.
6. The diffractive beam expander device according to claim 1, wherein the reflective element comprises a multilayer dielectric reflective film plated on the first or second main surface of the waveguide plate.
7. The diffractive beam expander device according to claim 1, wherein the reflective element has a reflectivity of at least 50% for the visible light band.
8. The diffractive beam expander device according to any one of claims 1 to 7, further comprising an intermediate diffractive coupling structure located on the waveguide plate between the diffractive input coupling structure and the diffractive output coupling structure;
the intermediate diffraction coupling structure is used for diffracting and expanding guided wave light formed by diffraction of the diffraction input coupling structure to form second guided wave light, and the second guided wave light passes through the diffraction output coupling structure to form output light.
9. The diffractive beam expander device according to claim 8, wherein the intermediate diffractive coupling structure is located inside the waveguide plate or on the first or second main surface.
10. A display device comprising an optical engine for emitting input light, and the diffraction beam expanding device according to any one of claims 1 to 9 provided on an light emitting side of the optical engine.
CN202310681285.9A 2023-06-08 2023-06-08 Diffraction beam expander and display device Pending CN116699753A (en)

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Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
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