WO2023029360A1 - 光学扩瞳装置、显示装置、光束扩展方法及图像显示方法 - Google Patents

光学扩瞳装置、显示装置、光束扩展方法及图像显示方法 Download PDF

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WO2023029360A1
WO2023029360A1 PCT/CN2022/072565 CN2022072565W WO2023029360A1 WO 2023029360 A1 WO2023029360 A1 WO 2023029360A1 CN 2022072565 W CN2022072565 W CN 2022072565W WO 2023029360 A1 WO2023029360 A1 WO 2023029360A1
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Prior art keywords
pupil
light
unit
grating
optical
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PCT/CN2022/072565
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English (en)
French (fr)
Inventor
利沃拉·塔帕尼·卡列沃
蒋厚强
朱以胜
朱奕帆
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深圳市光舟半导体技术有限公司
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Publication of WO2023029360A1 publication Critical patent/WO2023029360A1/zh

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/017—Head mounted
    • G02B27/0172—Head mounted characterised by optical features
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/0018—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 with means for preventing ghost images
    • 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
    • G02B27/0081—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 with means for altering, e.g. enlarging, the entrance or exit pupil
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/0101—Head-up displays characterised by optical features
    • G02B27/0103—Head-up displays characterised by optical features comprising holographic elements
    • 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
    • G02B27/10—Beam splitting or combining systems
    • G02B27/1086—Beam splitting or combining systems operating by diffraction only
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/203—Filters having holographic or diffractive elements
    • 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
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/34—Optical coupling means utilising prism or grating
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/0101—Head-up displays characterised by optical features
    • G02B2027/0112—Head-up displays characterised by optical features comprising device for genereting colour display
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/0101—Head-up displays characterised by optical features
    • G02B2027/0123—Head-up displays characterised by optical features comprising devices increasing the field of view
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/0101—Head-up displays characterised by optical features
    • G02B2027/0123—Head-up displays characterised by optical features comprising devices increasing the field of view
    • G02B2027/0125—Field-of-view increase by wavefront division
    • 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
    • G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
    • G02B27/4272—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having plural diffractive elements positioned sequentially along the optical path

Definitions

  • the invention relates to the field of display technology, in particular to an optical pupil expansion device, a display device, a light beam expansion method and an image display method.
  • an optical pupil expansion device EPE0 includes a waveguide plate SUB01, and the waveguide plate further includes a diffraction entrance pupil unit DOE01, a diffraction pupil expansion unit DOE02 and a diffraction exit pupil unit DOE03.
  • the optical pupil expanding device expands the input light beam IN1 through multiple diffractions, and finally forms the output light OUT1.
  • the input light IN1 can be emitted by the light engine ENG1.
  • the light engine ENG1 may consist of a microdisplay DISP1 and a collimating optic LNS1.
  • the coupling-entry pupil unit DOE01 diffracts the input light IN1 into the first guided light B1 through diffraction.
  • the pupil expansion unit DOE02 expands and diffracts the first guided light B1 through diffraction to form guided light B2.
  • the diffractive exit pupil unit DOE03 diffracts and expands the guided light B2 into the output light OUT1 through extended diffraction.
  • the optical pupil expander EPE0 can expand the light beam both in the direction SX and in the direction SY.
  • the width wOUT1 of the output light OUT1 may be much larger than the width wIN1 of the input light IN1.
  • the optical pupil expansion device EPE0 can be used to expand the pupil of the virtual display device, so that the eye EYE1 has a larger comfortable viewing position relative to the viewing position of the virtual display device.
  • the observer's eye EYE1 can see the completed virtual image within the observation position of the output light beam.
  • the output light may comprise one or more output beams, wherein each output beam may correspond to a different image position of the displayed virtual image VIMG1.
  • the optical pupil expansion device can also be called, for example, a pupil expansion unit, an optical pupil expansion device, an optical pupil expansion device, and the like.
  • the virtual image VIMG1 shown may have an angular spread LIM1.
  • a way to realize full-color virtual image VIMG1 display using the optical pupil expansion device EPE0 as shown in Figure 1 may cause the red or blue light emitted from the image point at the edge or corner of the virtual image to fail to meet the waveguide during transmission. Total reflection conditions for SUB01. As a result, one or more corner regions of the virtual image VIMG1 may lack red or blue light.
  • Embodiments of the present invention provide an optical pupil dilation device, a display device, a beam expansion method, and an image display method, aiming at displaying full-color pictures so as to provide full-color display with a larger viewing angle.
  • an embodiment of the present invention provides an optical pupil dilation device, including a waveguide plate, and the waveguide plate is provided with:
  • an entrance pupil unit configured to diffract the input light to form a first guided light and a second guided light
  • a first pupil expanding unit configured to diffract the first guided light to form a third guided light
  • a second pupil expanding unit configured to diffract the second guided light to form a fourth guided light
  • an exit pupil unit for diffracting the third guided light to form a first output light, and for diffracting the fourth guided light to form a second output light, and combining the first output light and the second output light to form Combined output light;
  • the entrance pupil unit and the exit pupil unit are arranged along the diagonal of the waveguide plate, and the exit pupil unit is arranged below the entrance pupil unit, and the first pupil expansion unit and the second pupil expansion unit are arranged on The two sides of the entrance pupil unit and the exit pupil unit.
  • an embodiment of the present invention provides a display device, including the optical pupil expansion device as described in the first aspect, and an optical engine for forming a main image.
  • an embodiment of the present invention provides a method for expanding a beam, using the optical pupil expanding device as described in the first aspect to expand the beam.
  • an embodiment of the present invention provides an image display method, which uses the optical pupil dilation device as described in the first aspect for image display.
  • An embodiment of the present invention provides an optical pupil expansion device, a display device, a beam expansion method, and an image display method.
  • the optical pupil expansion device includes a waveguide plate, and the waveguide plate is provided with: an entrance pupil unit for Input light to form first guided light and second guided light; a first pupil expanding unit for diffracting the first guided light to form a third guided light; a second pupil expanding unit for diffracting the second guided light Wave the light to form a fourth guided light; an exit pupil unit is used to diffract the third guided light to form a first output light, and to diffract the fourth guided light to form a second output light, and to convert the first output
  • the light and the second output light are combined to form a combined output light;
  • the entrance pupil unit and the exit pupil unit are arranged along the diagonal of the waveguide plate, and the exit pupil unit is arranged below the entrance pupil unit, and the first A pupil expansion unit and a second pupil expansion unit are arranged on both sides of the entrance pupil unit and the exit pupil unit.
  • the embodiment of the present invention can provide two different light transmission paths to overcome the limitation caused by the light guiding ability of the waveguide plate, and realize the transmission of different colors of light in a wide image in the waveguide, so as to display full-color pictures and provide a larger Full color display of angle of view.
  • Fig. 1 is the structural representation of a kind of optical pupil expanding device in the prior art
  • Figure 2a is a schematic structural diagram of an optical pupil dilation device provided by an embodiment of the present invention.
  • Fig. 2b is a schematic diagram of spectral filtering of guided wave light propagating along the first path in an optical pupil expansion device provided by an embodiment of the present invention
  • Fig. 2c is a schematic diagram of spectral filtering of guided light propagating along the second path in an optical pupil expansion device provided by an embodiment of the present invention
  • Fig. 3a is a three-dimensional schematic diagram of a display device provided by an embodiment of the present invention.
  • Fig. 3b is a schematic diagram of the overall output light formed by the superposition of the first output light and the second output light in an optical pupil dilation device provided by an embodiment of the present invention
  • Fig. 4a is a schematic diagram of an interfering ghost light beam formed when the second pupil expansion unit diffracts and receives blue light from the first pupil expansion unit in an optical pupil expansion device provided by an embodiment of the present invention
  • Fig. 4b is a schematic diagram of an interfering ghost light beam formed when the first pupil expansion unit diffracts and receives red light from the second pupil expansion unit in an optical pupil expansion device provided by an embodiment of the present invention
  • Fig. 5a is a cross-sectional schematic diagram of a pupil expanding device in which the first color filter region and the first Bragg grating region are on the same surface of the waveguide plate in an optical pupil expanding device provided by an embodiment of the present invention
  • Fig. 5b is a schematic cross-sectional view of the first spectral filter region and the first Bragg grating region on different surfaces of the waveguide plate in an optical pupil expansion device provided by an embodiment of the present invention
  • Fig. 5c is a schematic diagram of multiple consecutive reflections of guided light in the Bragg grating region in an optical pupil expansion device provided by an embodiment of the present invention
  • Fig. 5d is a schematic diagram of an overlapping area of the first spectral filter area and the first Bragg grating area in an optical pupil expansion device provided by an embodiment of the present invention
  • Fig. 6a is a schematic diagram of the width of the cross-section of the first Bragg grating area and the height of the cross-section of the second Bragg grating area in an optical pupil expansion device provided by an embodiment of the present invention
  • Fig. 6b is a schematic cross-sectional view of a display device provided by an embodiment of the present invention.
  • Fig. 6c is a cross-sectional schematic diagram of the reflection of blue light in the second Bragg grating region in an optical pupil expansion device provided by an embodiment of the present invention.
  • Fig. 7a is a schematic diagram of an exit pupil area of a pupil exit unit in an optical pupil expansion device provided by an embodiment of the present invention.
  • Fig. 7b is a schematic diagram of the size of an optical pupil dilation device provided by an embodiment of the present invention.
  • Fig. 7c is a schematic diagram of another size of an optical pupil dilation device provided by an embodiment of the present invention.
  • Fig. 8a is a cross-sectional schematic diagram of forming a first guided light by coupling an input beam into a waveguide in an optical pupil expanding device provided by an embodiment of the present invention, wherein the inclination angle of the first guided light is close to the critical angle of total internal reflection;
  • Fig. 8b is a schematic cross-sectional view of an optical pupil expanding device provided by an embodiment of the present invention by coupling an input beam into a waveguide to form a first guided light, wherein the inclination angle of the first guided light is close to 90 degrees;
  • Fig. 8c is a schematic diagram of the relationship between the wave vector angle of the first guided light and the wave vector angle of the input light in an optical pupil expansion device provided by an embodiment of the present invention
  • Fig. 9a is a vector diagram of blue light wave vector propagating along the first path in an optical pupil dilation device provided by an embodiment of the present invention.
  • Figures 9b and 9c are vector diagrams of red light wave vectors propagating along the first path in an optical pupil dilation device provided by an embodiment of the present invention.
  • Figures 9d and 9e are vector diagrams of blue light wave vectors propagating along the first path in the corner points of the displayed image in an optical pupil dilation device provided by an embodiment of the present invention.
  • Fig. 10a is a vector diagram of the wave vector of red light propagating along the second path in an optical pupil dilation device provided by an embodiment of the present invention
  • Fig. 10b is a vector diagram of blue light wave vector in an optical pupil dilation device provided by an embodiment of the present invention.
  • Figures 10c and 10d are vector diagrams of blue light wave vectors at the corner points of the image displayed in an optical pupil dilation device provided by an embodiment of the present invention.
  • Fig. 10e is a vector diagram of blue light wave vector propagating along the second path in an optical pupil dilation device provided by an embodiment of the present invention.
  • Fig. 10f and 10g are the vector diagrams of the red light wave vector of the corner points of the displayed image propagating along the second path in a kind of optical pupil dilation device provided by the embodiment of the present invention.
  • Figure 11a is an example diagram of the propagation of blue light at the corner point P1 in the waveguide plate SUB1 in an optical pupil dilation device provided by an embodiment of the present invention
  • Fig. 11b is an example diagram of the propagation of red light at the corner point P1 in the waveguide plate SUB1 in an optical pupil dilation device provided by an embodiment of the present invention
  • Figure 12a is an example diagram of the propagation of blue light at the corner point P2 in the waveguide plate SUB1 in an optical pupil dilation device provided by an embodiment of the present invention
  • Fig. 12b is an example diagram of the propagation of red light at the corner point P2 in the waveguide plate SUB1 in an optical pupil dilation device provided by an embodiment of the present invention
  • Fig. 13a is an example diagram of the propagation of blue light at the center point P0 in the waveguide plate SUB1 in an optical pupil dilation device provided by an embodiment of the present invention
  • Fig. 13b is an example diagram of the propagation of red light at the center point P0 in the waveguide plate SUB1 in an optical pupil dilation device provided by an embodiment of the present invention
  • Fig. 14a is an example diagram of propagation of blue light at the corner point P3 in the waveguide plate SUB1 in an optical pupil dilation device provided by an embodiment of the present invention
  • Fig. 14b is an example diagram of the propagation of red light at the corner point P3 in the waveguide plate SUB1 in an optical pupil dilation device provided by an embodiment of the present invention
  • Fig. 15a is an example diagram of propagation of blue light at the corner point P4 in the waveguide plate SUB1 in an optical pupil dilation device provided by an embodiment of the present invention
  • Fig. 15b is an example diagram of the propagation of red light at the corner point P4 in the waveguide plate SUB1 in an optical pupil dilation device provided by an embodiment of the present invention
  • 16a-16e are schematic diagrams of how the light engine in a display device according to an embodiment of the present invention forms incident light
  • Fig. 16f is a schematic diagram of displaying a virtual image in a display device according to an embodiment of the present invention.
  • Fig. 16g is a schematic diagram of the horizontal angle amplitude of a virtual image in a display device provided by an embodiment of the present invention.
  • Fig. 16h is a schematic diagram of pitch angle amplitude of a virtual image in a display device according to an embodiment of the present invention.
  • an optical pupil expansion device EPE1 provided by an embodiment of the present invention includes a waveguide plate SUB1, and the waveguide plate SUB1 is provided with:
  • the entrance pupil unit DOE1 is configured to diffract the input light to form the first guided light and the second guided light;
  • the first pupil expansion unit DOE2a is configured to diffract the first guided light to form a third guided light
  • the second pupil expansion unit DOE2b is configured to diffract the second guided light to form a fourth guided light
  • an exit pupil unit DOE3 for diffracting the third guided light to form a first output light, and for diffracting the fourth guided light to form a second output light, and combining the first output light and the second output light form a combined output light;
  • the entrance pupil unit DOE1 and the exit pupil unit DOE3 are arranged along the diagonal of the waveguide plate SUB1, and the exit pupil unit DOE3 is arranged below the entrance pupil unit DOE1, and the first pupil expansion unit DOE2a and the second pupil expansion unit DOE2a Two pupil expansion units DOE2b are arranged on both sides of the entrance pupil unit DOE1 and the exit pupil unit DOE3.
  • This embodiment can display a color picture, and the color image can be an RGB image, including red (R) light, green (G) light and blue (B) light.
  • RGB image including red (R) light, green (G) light and blue (B) light.
  • Increasing the exit pupil size of the displayed image may result in leakage of blue and/or red light from pixels at the edges or corners of the displayed image.
  • the red light or blue light received by the entrance pupil unit DOE1 of the optical pupil expanding device EPE1 may not be completely confined in the waveguide plate through total internal reflection.
  • the optical pupil expansion device EPE1 proposed by the present invention can provide two different light transmission paths to overcome the limitation caused by the light guiding ability of the waveguide plate, and realize the transmission of different color lights of wide images in the waveguide.
  • the optical pupil expanding device EPE1 can split the input light, and propagate to the exit pupil unit DOE3 through the first path and the second path respectively.
  • the first path can realize light transmission from the entrance pupil unit DOE1 to the exit pupil unit DOE3 through the first pupil expansion unit DOE2a.
  • the second path can realize light transmission from the entrance pupil unit DOE1 to the exit pupil unit DOE3 through the second pupil expansion unit.
  • the blue light can travel to the exit pupil unit through the first path, and the red light can travel to the exit pupil unit DOE3 through the second path.
  • different color components can compensate each other at the output of the optical pupil expansion device EPE1 through different paths, and are combined in the pupil exit unit DOE3 to display a full-color wide image.
  • the first path may be optimized for diffraction of blue light and the second path may be optimized for diffraction of red light.
  • the grating period of the first path may be different from the grating period of the second path, therefore, the unplanned propagation of blue light along the second path may cause ghost images and affect the display of pictures. Similarly, the unintended propagation of red light along the first path may also cause ghosting, affecting the display of the picture.
  • the optical pupil expansion device EPE1 may comprise a substantially planar waveguide SUB1 which in turn comprises a diffractive entrance pupil unit DOE1, a first pupil expander DOE2a, a second pupil expander DOE2b and a diffractive exit pupil DOE3.
  • the grating unit used can be on the first surface or the second surface of the waveguide plate SUB1.
  • the entrance pupil unit DOE1 can receive input light IN1 and the exit pupil unit DOE3 can provide output light OUT1 .
  • the input light IN1 may contain multiple beams traveling in different directions.
  • the output light OUT1 may comprise a plurality of expanded beams formed by the beam B0 in the input light IN1.
  • the width wOUT1 of the output light OUT1 may be greater than the width wIN1 of the input light IN1.
  • the optical pupil expander EPE1 can expand the input light IN1 two-dimensionally (for example, in the horizontal direction SX and in the vertical direction SY). The dilation process may also be called pupil dilation.
  • the optical pupil expander EPE1 may be called a beam pupil expander or an exit pupil expander.
  • the entrance pupil unit DOE1 may form the first guided light B1a and the second guided light B1b by diffracting the input light IN1.
  • the first guided light B1a and the second guided light B1b may propagate in the planar waveguide plate SUB1.
  • the first wave-guided light B1a and the second wave-guided light B1b may be confined within the board SUB1 by total internal reflection.
  • conducting may mean that light propagates within the planar waveguide plate SUB1, thereby confining the light beam within the waveguide plate by total internal reflection (TIR).
  • TIR total internal reflection
  • conducting may mean the same as the term "waveguide”.
  • the entrance pupil unit DOE1 can couple the input light IN1 to propagate to the exit pupil unit DOE3 via two different paths, namely via the first pupil dilation unit DOE2a and the second pupil dilation unit DOE2b. Through optical coupling, it enters the entrance pupil unit DOE1, passes through the first pupil expansion unit DOE2a, and finally reaches the exit pupil unit DOE3. It can also be optically coupled into the entrance pupil unit DOE1, then through the second pupil expansion unit DOE2b, and finally to the exit pupil unit DOE3.
  • the optical pupil expansion device EPE1 may provide a first path from unit DOE1 to unit DOE3 via unit DOE2a.
  • the optical pupil expansion device EPE1 may provide a second path from unit DOE1 to unit DOE3 via unit DOE2b.
  • the first path may represent an optical path from the entrance pupil unit DOE1 to the exit pupil unit DOE3 and passes through the first pupil expansion unit DOE2a.
  • the second path may refer to an optical path from the entrance pupil unit DOE1 to the exit pupil unit DOE3 and passing through the second pupil expansion unit DOE2b.
  • the first guided light B1a may mainly propagate along the first direction DIR1a from the entrance pupil unit DOE1 to the first pupil expansion unit DOE2a.
  • the first pupil expansion unit DOE2a may form the third guided light B2a by diffracting the first guided light B1a.
  • the lateral dimension of the third guided light B2a may be larger than the corresponding lateral dimension of the input light IN1.
  • the third guided light B2a may also be referred to as extended guided light B2a.
  • the expanded guided light B2a may propagate from the first pupil expansion unit DOE2a to the exit pupil unit DOE3.
  • the expanded guided light B2a can be confined within the plate SUB1 by total internal reflection.
  • the exit pupil unit DOE3 can expand the guided light B2a by diffracting to form the first output light OB3a.
  • the second guided light B1b may mainly propagate along the second direction DIR1b from the entrance pupil unit DOE1 to the second pupil expansion unit DOE2b.
  • the second pupil expansion unit DOE2b may form fourth guided light B2b by diffracting the second guided light B1b.
  • the lateral dimension of the fourth guided light B2a may be larger than the corresponding lateral dimension of the input light IN1.
  • the fourth guided light B2b may also be referred to as extended guided light B2b.
  • the expanded guided light B2b may propagate from the second pupil expansion unit DOE2b to the exit pupil unit DOE3.
  • the expanded guided light B2b can be confined within the plate SUB1 by total internal reflection.
  • the exit pupil unit DOE3 may form the second output light OB3b by diffracting the extended waveguide light B2b.
  • the exit pupil unit DOE3 can diffract the guided light B2a received by the first pupil expansion unit DOE2a, and at the same time, the exit pupil unit DOE3 can diffract the guided light B2b received by the second pupil expansion unit DOE2b.
  • the direction DIR1a may represent an average propagation direction of the first guided light B1a.
  • the direction DIR1a may also indicate the central axis of propagation of the first guided light B1a.
  • the direction DIR1b may represent an average propagation direction of the second guided light B1b.
  • the direction DIR1b may also indicate the central axis of propagation of the second guided light B1b.
  • An angle ⁇ 1ab between the first direction DIR1a and the second direction DIR1b may be in the range of 60° to 120°.
  • the expanded guided light B2a may propagate in a third direction DIR2a, which may be substantially parallel to the second direction DIR1b.
  • the expanded guided light B2b may propagate in a fourth direction DIR2b, which may be substantially parallel to the first direction DIR1a.
  • the optical pupil expansion device EPE1 further includes a spectral filter area
  • the spectral filter area includes a first spectral filter area C2a and a first spectral filter area C2a arranged inside the first pupil expansion unit DOE2a
  • the second spectral filter area C2b arranged inside the second pupil expansion unit, the first spectral filter area C2a is used to prevent the first color light from passing through the first pupil expansion unit DOE2a from the entrance
  • the pupil unit is transmitted to the exit pupil unit
  • the second spectral filter area C2b is used to prevent the second color light from being transmitted from the entrance pupil unit DOE1 to the exit pupil unit through the second pupil expansion unit DOE2b DOE3.
  • the optical pupil expansion device EPE1 includes a first spectral filter area C2a, the first spectral filter area prevents coupling from entering through the entrance pupil unit DOE1, and is transmitted to The red light of the exit pupil unit DOE3.
  • the optical pupil expansion device EPE1 includes a second spectral filter area C2b, the second spectral filter area prevents coupling from entering through the entrance pupil unit DOE1, and transmits to the exit pupil unit via the first pupil expansion unit DOE2b Blue rays of DOE3.
  • the optical pupil expansion device EPE1 further includes a Bragg grating area, and the Bragg grating area includes first spectral filter area C2a and second spectral filter area C2b.
  • the optical pupil expansion device EPE1 includes a first Bragg grating region BRGa.
  • the first Bragg grating region BRGa at least partially overlaps with the first spectral filter region C2a, thereby strengthening the first spectral filter region. Absorption of red light in the light sheet region C2a;
  • the optical pupil expansion device EPE1 includes a second Bragg grating region BRGb, and the second Bragg grating region BRGb at least partially overlaps with the second spectral filter region C2b, thereby strengthening the second spectral filter region C2b Absorption of blue light.
  • the Bragg grating area ensures that the spectral filter area can effectively prevent the generation of undesired ghost images.
  • the Bragg grating regions enhance the light absorption of the spectral filter, thereby suppressing unwanted ghost beams.
  • Interaction of the guided light with the Bragg grating regions may result in multiple successive reflections of the guided light.
  • the guided light can be diffracted back and forth several times through the Bragg grating to increase the absorption path of the guided light in the spectral filter area.
  • the red light in the corner of the image may leak out of the waveguide due to failure to satisfy the total internal reflection (TIR) condition of the waveguide.
  • TIR total internal reflection
  • the blue light at the corner point will not be coupled to the second pupil expansion unit through the entrance pupil unit, possibly because the solution of the diffraction equation is not satisfied.
  • Incomplete coupling and/or failure to confine light within the waveguide plate can result in non-uniform brightness distribution of the displayed image.
  • Non-uniform brightness distribution may mean that the maximum brightness of a first region of a displayed image will be significantly different from the maximum brightness of a second region of a displayed image.
  • the first spectral filter and the second spectral filter can make brightness distribution more uniform or/and reduce color distortion. Therefore, the optical pupil dilating device can expand the input uniform color picture light through diffraction to display a uniform full-color picture.
  • the red light propagating through the first path carries incomplete red local image information, and the red light at some corner points of the image is lost.
  • the first spectral filter region can filter red light, and the filtered red light can form an incomplete red light partial image.
  • the first spectral filter can basically eliminate all red light passing through the first path, so as to prevent incomplete partial red images from interfering with the displayed multi-color picture.
  • the blue light propagating through the second path carries incomplete blue local image information, and the blue light at some corner points of the image is lost.
  • the second spectral filter area can filter blue light, and the filtered blue light can form an incomplete blue light partial image.
  • the second spectral filter can basically eliminate all blue light passing through the second path, so as to prevent incomplete local blue images from interfering with the displayed multi-color picture.
  • the waveguide plate SUB1 may contain a first spectral filter region C2a, preventing coupling of red light propagating from the entrance pupil unit DOE1 to the exit pupil unit DOE3 via the first optical pupil expansion device DOE2a.
  • the waveguide plate SUB1 may contain one or more first spectral filter regions (C1a, C2a) preventing coupling of red light propagating from the entrance pupil unit DOE1 to the exit pupil unit DOE3 via the first optical pupil expansion device DOE2a.
  • the first spectral filter or the first spectral filter area (C1a, C2a) can couple the blue light propagating from the entrance pupil unit DOE1 to the exit pupil unit DOE3 via the first pupil expansion unit DOE2a.
  • the first spectral filter or first spectral filter region, can improve the uniformity of the displayed picture by eliminating incomplete red images.
  • the waveguide plate SUB1 may include a second spectral filter region C2b to prevent coupling of blue light propagating from the entrance pupil unit DOE1 to the exit pupil unit DOE3 via the second optical pupil expansion device DOE2b.
  • the waveguide plate SUB1 may contain one or more second spectral filter regions (C1b, C2b) preventing coupling of blue light propagating from the entrance pupil unit DOE1 to the exit pupil unit DOE3 via the second optical pupil expansion device DOE2b.
  • the second spectral filter or the second spectral filter region can couple the red light propagating from the entrance pupil unit DOE1 to the exit pupil unit DOE3 through the second pupil expansion unit DOE2b.
  • the second spectral filter or second spectral filter region, can improve the uniformity of the displayed picture by eliminating incomplete blue images.
  • the waveguide plate SUB1 may contain one or more optical isolation units ISO1 to prevent direct optical coupling between the first pupil expansion unit DOE2a and the second pupil expansion unit DOE2b.
  • Isolation unit ISO1 stops all color propagation.
  • the isolation unit ISO1 can block the transmission of red light (R), green light (G), and blue light (B).
  • the isolation unit ISO1 can be obtained by depositing (black) absorbing material on the surface of the plate, or/and by adding (black) absorbing material to the corresponding area material of the plate, or/and by forming one or more openings in the plate to fulfill.
  • the first spectral filter area (C1a, C2a) and the second spectral filter area (C1b, C2b) can also be used as an optical isolation structure ISO1 to prevent the first pupil expansion unit DOE2a and The second pupil expansion unit DOE2b performs direct optical coupling.
  • SX, SY and SZ are orthogonal directions.
  • the waveguide plate SUB1 may be parallel to the plane defined by SX and SY.
  • the guided light (B1a, B2a) passing through the first path may initially contain red light (R), green light (G) and blue light (B).
  • guided light B2a may have an initial spectral intensity distribution I2A( ⁇ ).
  • the first spectral filter or one or more first spectral filter regions (C1a, C2a) may substantially prevent red light from propagating to the exit pupil unit DOE3.
  • One or more first spectral filter regions (C1a, C2a) on the first path may have a spectral transmittance equation TFA( ⁇ ).
  • the spectral transmittance equation TFA( ⁇ ) may have a critical wavelength ⁇ CUT,A.
  • the one or more first spectral filter regions (C1a, C2a) may substantially prevent propagation of spectral elements having wavelengths greater than the critical wavelength ⁇ CUT,A.
  • the one or more first spectral filter regions (C1a, C2a) may allow those spectral elements whose wavelength is smaller than the critical wavelength ⁇ CUT,A to propagate to the exit pupil unit DOE3.
  • the filtered guided light (B1a, B2a) may have a spectral intensity distribution I'2A( ⁇ ).
  • the first spectral filter or one or more first spectral filter regions (C1a, C2a) may substantially prevent red light from propagating to the exit pupil unit DOE3.
  • the one or more first spectral filter regions (C1a, C2a) may allow blue and green light to propagate from the first pupil dilation unit DOE2a to the exit pupil unit DOE3.
  • ⁇ R may represent the wavelength of red light (R).
  • ⁇ R may represent, for example, the wavelength of maximum spectral intensity of red light (R).
  • ⁇ G may represent the wavelength (G) of green light.
  • ⁇ G may represent, for example, the wavelength of the maximum spectral intensity of green light (G).
  • ⁇ B may represent the wavelength (B) of blue light.
  • ⁇ B may represent, for example, the wavelength of the maximum spectral intensity of blue light (B).
  • IMAX can represent the maximum value of spectral intensity.
  • the guided light (B1b, B2b) passing through the second path may initially contain red light (R), green light (G) and blue light (B).
  • guided light B2b may have an initial spectral intensity distribution I2B( ⁇ ).
  • the second spectral filter or one or more second spectral filter regions (C1b, C2b) may substantially prevent blue and green light from propagating to the exit pupil unit DOE3.
  • One or more second spectral filter regions (C1b, C2b) on the second path may have a spectral transmittance equation TFB( ⁇ ).
  • the spectral transmittance equation TFB( ⁇ ) may have a critical wavelength ⁇ CUT,B.
  • the one or more second spectral filter regions (C1b, C2b) may substantially prevent propagation of spectral elements having wavelengths smaller than the critical wavelength ⁇ CUT,B.
  • One or more second spectral filter regions (C1b, C2b) may allow those spectral elements whose wavelength is greater than the critical wavelength ⁇ CUT,B to propagate to the exit pupil unit DOE3.
  • the filtered guided light (B1b, B2b) may have a spectral intensity distribution I'2B( ⁇ ).
  • the second spectral filter or one or more second spectral filter regions (C1b, C2b) may substantially prevent blue and green light from propagating to the exit pupil unit DOE3.
  • the one or more second spectral filter regions (C1b, C2b) may allow red light to propagate from the second pupil dilation unit DOE2b to the exit pupil unit DOE3.
  • the first spectral filter or one or more first spectral filter regions (C1a, C2a) may substantially prevent red and green light from propagating to the exit pupil unit DOE3.
  • the first spectral filter or one or more first spectral filter regions (C1a, C2a) may allow red and green light to pass through the second pupil expansion unit DOE2b to the exit pupil unit DOE3.
  • the second spectral filter or one or more second spectral filter regions (C1b, C2b) may substantially prevent blue light from propagating to the exit pupil unit DOE3.
  • the first spectral filter or one or more first spectral filter regions (C1b, C2b) may allow red and green light to pass through the second pupil expansion unit DOE2b to the exit pupil unit DOE3.
  • the green light (G) may travel to the exit pupil unit DOE3 via the second path.
  • the blue light (B) may travel to the exit pupil unit DOE3 via a first path
  • the red light (R) and green light (G) may travel to the exit pupil unit DOE3 via a second path.
  • the spectral filter region C2a may be arranged to prevent green and red light from being coupled from the entrance pupil unit DOE1 to the exit pupil unit DOE3 through the first pupil expansion unit DOE2a.
  • the means EPE1 may be arranged to couple green light from the entrance pupil unit DOE1 to the exit pupil unit DOE3 through the second pupil expansion unit DOE2b.
  • the first spectral filter area C2a and the second spectral filter area C2b can jointly prevent red light (R) green light (G) blue light (B) from entering the first pupil expansion unit (DOE2a) and the second pupil expansion unit ( Coupling of DOE2b).
  • the combined spectral transmittance TFA( ⁇ ) ⁇ TFB( ⁇ ) of the first spectral filter region C2a and the second spectral filter region C2b is substantially zero for all (visible) spectral elements of the input light B0.
  • the grating period (d2b) of the second pupil expansion unit DOE2b does not match the wavelength of the guided light B2a received from the first pupil expansion unit DOE2a. Therefore, the second pupil expansion unit DOE2b will form one or more unnecessary additional beams B2g by diffracting the guided light B2a.
  • the additional beam B2g may be called, for example, a ghost beam.
  • the exit pupil unit DOE3 couples out the waveguide plate SUB1
  • the light of the ghost light beam B2g will form a disturbing ghost image. Unwanted ghost images may interfere with the actual virtual image VIMG1.
  • the grating period (d2a) of the first pupil expansion unit DOE2a does not match the wavelength of the guided light B2b received from the second pupil expansion unit DOE2b. Therefore, the first pupil expansion unit DOE2a will form one or more unwanted additional beams B2e by diffracting the guided light B2b.
  • the additional beam B2e may be called, for example, a ghost beam.
  • the exit pupil unit DOE3 couples out the waveguide plate SUB1
  • the light of the ghost light beam B2e will form a disturbing ghost image.
  • the optical pupil expansion device EPE1 may include a first Bragg grating area BRGa to enhance light absorption in the first spectral filter area C2a, thereby preventing coupling of the guided light B2b with the first pupil expansion unit DOE2a.
  • the first Bragg grating region BRGa may enhance light absorption in the first spectral filter region C2a, thereby preventing one or more ghost beams B2e from being formed.
  • the optical pupil expansion device EPE1 may include a second Bragg grating area BRGb to enhance light absorption in the second spectral filter area C2b, thereby preventing coupling of the guided light B2a with the second pupil expansion unit DOE2b.
  • the second Bragg grating region BRGb may enhance light absorption in the second spectral filter region C2b, thereby preventing the formation of one or more ghost beams B2g.
  • the waveguide plate comprises at least one cladding layer, at least one protective layer, and at least one mechanical support layer, and the spectral filter region and the Bragg grating region are located on the same side of the waveguide plate or different side.
  • the waveguide plate may have a thickness tSUB1.
  • the waveguide plate contains a planar waveguide core.
  • the waveguide plate SUB1 may optionally include one or more cladding layers, one or more protective layers and/or one or more mechanical support layers.
  • the thickness tSUB1 may refer to the thickness of the planar waveguide core portion of the waveguide plate SUB1.
  • the Bragg grating region BRGb and the spectral filter region C2b may be located on the same side of the waveguide plate SUB1.
  • the Bragg grating region BRGb and the spectral filter region C2b may be located on the first main surface SRF1.
  • the Bragg grating region BRGb and the spectral filter region C2b may be located on the second main surface SRF2.
  • the spectral filter region C2b and the Bragg grating region BRGb together can form the transmitted light B2aT and the reflected light B2aR from the guided light B2a.
  • the Bragg grating can reflect the guided wave light B2a back through the Bragg diffraction phenomenon. Bragg gratings can enhance light absorption in the region of the spectral filter.
  • the spectral filter region C2b and the Bragg grating region BRGb may be set to suppress the intensity of the transmitted light B2aT.
  • the spectral filtering region C2b and the Bragg grating region BRGb may be arranged together such that the intensity of the transmitted light B2aT is low or zero.
  • the symbol dBRGb indicates the grating period of the Bragg grating of the Bragg grating region BRGb.
  • a single ray of guided light B2a may undergo total internal reflection (TIR) at a first reflection point of surface SRF1 and an adjacent second reflection point of surface SRF1.
  • LTIR represents the distance between the reflection points.
  • the distance LTIR may be in the range of 1.5 to 4.0 times the thickness tSUB1 of the plate SUB1, depending on the position and color of the image point corresponding to the guided light in question.
  • the average value of the distance LTIR is substantially equal to 2.6.
  • the Bragg grating region BRGb and the spectral filter region C2b may be located on different sides of the waveguide plate SUB1.
  • the Bragg grating region BRGb may be on the first main surface SRF1 and the spectral filter region C2b may be on the second main surface SRF2.
  • the Bragg grating region BRGb may be on the second main surface SRF2 and the spectral filtering region C2b may be on the first main surface SRF1.
  • the area of the first overlapping region between the first Bragg grating region and the first spectral filter region is 50%-100% of the area of the first Bragg grating region
  • the first The area of the second overlapping area between the two Bragg grating areas and the second spectral filter area is 50%-100% of the area of the second Bragg grating area.
  • the Bragg grating BRGa can cause multiple consecutive reflections of the guided light B2a, B2aR.
  • the guided light B2a, B2aT can be reflected back and forth from the Bragg grating multiple times, so as to increase the absorption path of the guided light B2a, B2aR in the spectral filter region C2b.
  • the guided light can propagate along the folded optical path, where the guided light can encounter the absorbing filter region multiple times. Parts of the guided beam B2a may be reflected back to the first expanding element DOE2a.
  • the Bragg grating regions BRGb can respectively cause multiple consecutive reflections of the guided light B2b, B2bR.
  • the first Bragg grating region BRGa when viewed from a direction (SZ) perpendicular to the waveguide plate SUB1, the first Bragg grating region BRGa may partially or completely overlap the first spectral filter region C2a.
  • the area of the first spectral filter region C2a may be greater than, equal to, or smaller than the area of the first Bragg grating region BRGa.
  • the area of the first spectral filter region C2a may range from 50% to 200% of the area of the first Bragg grating region BRGa.
  • the position of the first Bragg grating region BRGa may coincide with the position of the first spectral filter region C2a.
  • the first Bragg grating area BRGa may be shifted relative to the first spectral filter area C2a.
  • COMa may denote a common overlapping area of the first Bragg grating area BRGa and the first spectral filter area C2a.
  • the area of the common overlapping area COMa may range from 50% to 100% of the area of the first Bragg grating area BRGa.
  • COMb denotes a common overlapping area of the second Bragg grating area BRGb and the second spectral filter area C2b.
  • the second Bragg grating region BRGb may partially or completely overlap the second spectral filter region C2b.
  • the area of the common overlapping area COMb may range from 50% to 100% of the area of the second Bragg grating area BRGb.
  • the exit pupil unit DOE3 may have a first grating vector VDOE3a for coupling the guided light B2a out of the plate SUB1.
  • the exit pupil unit DOE3 may have a second grating vector VDOE3b for coupling the guided light B2b out of the plate SUB1.
  • the cross-sectional width of the first Bragg grating region in the horizontal direction is 3 to 5 times the thickness of the waveguide layer of the waveguide plate
  • the cross-sectional width of the second Bragg grating region in the vertical direction is The thickness of the waveguide layer of the waveguide plate is 3 to 5 times.
  • the first Bragg grating area BRGa may define a vertical line segment LIN12 from a perpendicular line perpendicular to the grating vector V3a of the exit pupil unit DOE3.
  • the length of the line segment LIN12 may be referred to as a horizontal cross-sectional width h12 of the first Bragg grating region BRGa.
  • the horizontal cross-sectional width h12 may be greater than 3-5 times, for example 4 times, the thickness tSUB1 of the waveguide SUB1 to ensure effective absorption of the light B2b by the first spectral filter region C2a.
  • the horizontal line segment LIN12 may be perpendicular to the first grating vector V3a of the exit pupil unit DOE3.
  • the second Bragg grating region BRGb may define a vertical line segment LIN34 from a perpendicular line perpendicular to the grating vector V3b of the exit pupil unit DOE3.
  • the length of the line segment LIN34 may be referred to as a vertical cross-sectional height h34 of the second Bragg grating region BRGb.
  • the vertical cross-sectional height h34 may be greater than 3-5 times, eg 4 times, the thickness tSUB1 of the waveguide plate SUB1 to ensure efficient absorption of light B2a in the second spectral filter region C2a.
  • the vertical line segment LIN34 may be perpendicular to the second grating vector V3b of the exit pupil unit DOE3.
  • the second spectral filter area C2a and the Bragg grating area BRGa may have a common overlapping area COMa (Fig. 5d).
  • the common overlap area COMa may define a horizontal line segment (LIN12) with a line parallel to the diffractive feature (F3a) of the exit pupil unit DOE3.
  • the length (w12) of the horizontal line segment (LIN12) may be greater than 4 times the thickness of the waveguide layer (tSUB1) of the waveguide plate SUB1.
  • the spectral filter area C2b and the Bragg grating area BRGb may have a common overlapping area COMb (Fig. 5d).
  • the common overlap region COMb may define a vertical line segment (LIN34) from a line parallel to the diffractive feature (F3b) of the exit pupil unit DOE3.
  • the length (h34) of the vertical line segment (LIN34) may be greater than 4 times the thickness of the waveguide layer (tSUB1) of the waveguide plate SUB1.
  • POS1 denotes the first lateral position where the guided light B2a impinges on the second Bragg grating region BRGb.
  • POS2 denotes the second lateral position where the guided light B2a strikes the exit pupil unit DOE3.
  • the propagation of the guided light B2a at the first lateral position POS1 is illustrated with reference to Fig. 6b.
  • the first pupil expansion unit DOE2a forms guided light B2a.
  • a part of the guided light B2a may propagate toward the second pupil expansion unit DOE2b.
  • the combination of the second spectral filter area C2b and the second Bragg grating area BRGb can prevent the guided light B2a from propagating to the second pupil expansion unit DOE2b, thereby preventing the formation of an unnecessary ghost beam B2g.
  • the guided light B2a may have blue color, and the second spectral filter region C2b may absorb the blue light.
  • the propagation of the guided light B2a at the second lateral position POS2 is illustrated with reference to Fig. 6c.
  • the first pupil expansion unit DOE2a forms guided light B2a, which can propagate to the exit pupil unit DOE3 through the combination of the first spectral filter region C2a and the first Bragg grating region BRGa.
  • the first spectral filter area C2a may prevent the transmission of red light, and the first spectral filter area C2a may allow the transmission of blue light B2a.
  • the first spectral filter region C2a may allow the guided light B2a to be coupled from the first pupil expansion unit DOE2a to the exit pupil unit DOE3, thereby forming the blue color of the virtual image VIMG1.
  • the device EPE1 may comprise a spectral filter region C2a positioned between the first pupil dilation unit DOE2a and the exit pupil unit DOE3 to prevent red light from being coupled from the entrance pupil unit DOE1 through the first pupil dilation unit DOE2a To exit pupil unit DOE3.
  • the device EPE1 may include a spectral filter area C2b, located between the second pupil expansion unit DOE2b and the exit pupil unit DOE3, to prevent blue light from coupling from the entrance pupil unit DOE1 to the exit pupil unit DOE3 through the second pupil expansion unit DOE2b.
  • the first spectral filter area C2a and the second spectral filter area C2b can prevent red light (R), green light (G) and blue light (B) between the first pupil expansion unit DOE2a and the second pupil expansion unit DOE2b together. ) coupling.
  • the device EPE1 may also comprise one or more optical isolation elements ISO1 to prevent direct optical coupling between the first pupil expansion unit DOE2a and the second pupil expansion unit DOE2b.
  • the first pupil expansion unit DOE2a may be arranged to distribute the guided light B2a to the first exit pupil region REG3a of the exit pupil unit DOE3.
  • the first exit pupil region REG3a can diffract the guided light B2a out of the plate SUB1.
  • the second pupil expansion unit DOE2b may be arranged to distribute the guided light B2b to the second exit pupil region REG3b of the exit pupil unit DOE3.
  • the second exit pupil region REG3b can diffract the guided light B2b out of the plate SUB1.
  • the first exit pupil region REG3a may overlap with the second exit pupil region REG3b.
  • the common overlapping region COM1 of the first exit pupil region REG3a and the second exit pupil region REG3b can diffract the guided light B2a and the guided light B2b out of the plate SUB1.
  • the area of the common overlapping area COM1 may be greater than 50%, preferably greater than 70%, of the area of one side of the exit pupil unit DOE3.
  • the entrance pupil unit DOE1 may be arranged to diffract the input light IN1 such that the first guided light B1a contains the light of the center point P0 of the input image IMG0 and such that the second guided light B1b includes the light of the center point P0.
  • the exit pupil unit DOE3 may be arranged to diffract the third guided light B2a received from the first pupil expansion unit DOE2a such that the first output light OB3a includes the light of the central point P0.
  • the exit pupil unit DOE3 may be arranged to diffract the fourth guided light B2b received from the second pupil expansion unit DOE2b such that the second output light OB3b contains the light of the central point P0.
  • the light of the central point P0 in the first output light OB3a may propagate in the axial direction (k3P0,R), and the light of the central point P0 in the second output light OB3b may propagate in the same axial direction (k3P0,R).
  • the axial direction (k3P0,R) may be parallel to the optical axis (AX0) of the optical engine ENG1.
  • the light of the center point P0 in the first waveguide light B1a can propagate in the first direction (k1aP0), wherein the light of the center point P0 in the second waveguide light B1b can propagate in the second direction (k1bP0), wherein the first An angle ( ⁇ AB) between the direction (k1aP0) and the second direction (k1bP0) may be in the range of 60° to 120°.
  • the first region REG3a of the pupil exit unit DOE3 may be arranged to outcouple the light of the center point (P0) received from the first pupil dilation unit DOE2a, and the second region REG3b of the pupil exit unit DOE3 may be arranged to outcouple light from the second The pupil dilation unit DOE2b receives the light of the central point (P0).
  • the first region REG3a may overlap with the second region REG3a, so that the common overlapping region COM1 of the first region REG3a and the second region REG3b has an area larger than 50% of the area of one side of the exit pupil unit DOE3.
  • the optical pupil expanding device EPE1 can form output light OUT1 by diffracting and directing input light IN1 obtained from optical engine ENG1.
  • the display device 500 may include an optical engine ENG1 and an optical pupil expansion device EPE1.
  • the input light IN1 may contain multiple beams traveling in different directions. Each beam of input light IN1 may correspond to a different point of the input image IMG0.
  • the output light OUT1 may comprise a plurality of beams propagating in different directions. Each beam of output light OUT1 may correspond to a different point of the displayed virtual image VIMG1.
  • the pupil expansion unit EPE1 may form the output light OUT1 from the input light IN1 such that the direction and intensity of the beam of the output light OUT1 correspond to points of the input image IMG0 .
  • a beam of input light IN1 may correspond to a single image point (P0) of a display image.
  • the optical pupil expander EPE1 can form an output beam from a beam of input light IN1 such that the direction (k3, P0, R) of the output beam is parallel to the direction (k3, P0, R) of the beam of corresponding input light IN1.
  • the entrance pupil unit is provided with a first diffraction feature for diffracting the first guided light to the first pupil expansion unit, and a first diffraction feature for diffracting the second guided light to the second pupil expansion unit.
  • the second diffractive feature, the first diffractive feature and the second diffractive feature are both protrusions or grooves.
  • the entrance pupil unit may include a first diffractive feature to diffract light to the first pupil dilation unit.
  • the entrance pupil unit may contain second diffractive features to diffract light to the second pupil dilation unit.
  • the first diffractive feature may have a first grating period and the second diffractive feature may have a second, different grating period.
  • the first grating period can be chosen to ensure that the blue guided light at the corner points is confined within the waveguide plate.
  • the second grating period can be chosen to ensure that the red guided light at the corner points is confined within the waveguide plate.
  • the first diffractive feature may have a first orientation and the second diffractive feature may have a second, different orientation.
  • the two paths can at least partially compensate for color deviations in corner points of the displayed image.
  • Two paths can reduce or avoid color errors at corner points of wide color display images.
  • Two paths can improve the color uniformity of wide color display images.
  • the spectral filter area can improve the color uniformity of the full-color image.
  • the exit pupil unit may form the first output light by diffracting the third waveguide light propagating along the first path.
  • the diffracted third guided light comes from the first pupil expanding unit.
  • the exit pupil unit may form the second output light by diffracting the fourth guided light propagating along the second path.
  • the diffracted fourth guided light comes from the second pupil expanding unit.
  • the first light output may spatially overlap the second light output.
  • the exit pupil unit combines the first output light and the second output light to form a combined output light.
  • the pupil exit unit may include a first diffractive feature to diffract the guided light received from the first pupil dilation unit.
  • the exit pupil unit may contain a second diffractive feature to diffract guided light received from the second pupil dilation unit.
  • the first diffractive feature may have a first grating period and the second diffractive feature may have a second, different grating period.
  • the first grating period can be chosen to ensure that the blue guided light at the corner points is confined within the waveguide plate.
  • the second grating period can be chosen to ensure that the red guided light at the corner points is confined within the waveguide plate.
  • the first diffractive feature may have a first direction and the second diffractive feature may have a second, different direction.
  • the exit pupil efficiency of the first diffractive feature for coupling light received from the second pupil dilation unit may be very low or negligible.
  • the exit pupil efficiency of the second diffractive feature for coupling light received from the first pupil dilation unit may be very low or negligible.
  • the Bragg grating region can enhance light absorption by the spectral filter region.
  • the Bragg grating regions may be formed at the same time as one or more other grating regions of the optical pupil expanding device are formed. The use of the Bragg grating area has little or negligible impact on the manufacturing cost of the optical pupil expansion device.
  • the optical pupil expander EPE1 can expand the light beam in two directions, in the direction SX and in the direction SY.
  • the width of the output light OUT1 (along the SX direction) may be greater than the width of the input light IN1, and the height of the output light OUT1 (along the SY direction) may be greater than the height of the input light IN1.
  • the optical pupil expansion device EPE1 may be configured to expand the pupil of the virtual display device 500 so as to facilitate the positioning of the eye EYE1 relative to the virtual display device 500 .
  • the output light OUT1 may comprise one or more output beams, wherein each output beam may correspond to a different image point (P0', P1') of the displayed virtual image VIMG1.
  • the light engine ENG1 may contain a microdisplay DISP1 for displaying the main image IMG0.
  • the light engine ENG1 and the optical pupil expander EPE1 can be arranged to convert the main image IMG0 into a plurality of input beams (for example, B0P0, R, B0P1, R, B0P2, R, B0P3, R, B0P4, R, ..., B0P0 ,B, B0P1, B, B0P2, B, B0P3, B, B0P4, B, ...), and form the output light OUT1 by expanding the input beam.
  • the notation B0P2,R may represent an input beam, which corresponds to image point P2 and has red color (R).
  • the notation B0P2,B may represent an input beam, which corresponds to image point P2 and has a blue color (B).
  • the input light beams may together constitute input light IN1.
  • the input light IN1 can contain multiple input beams (for example, B0P0,R,B0P1,R,B0P2,R,B0P3,R,B0P4,R,...B0P0,B,B0P1,B,B0P2,B,B0P3,B ,B0P4,B,).
  • the output light OUT1 may include multiple output beams, and each output beam may form a different image point (P0', P1') of the virtual image VIMG1.
  • the main image IMG0 can be represented eg as graphics and/or text.
  • the main image IMG0 may be represented, for example, as a video.
  • the light engine ENG1 and the optical pupil expansion device EPE1 may be arranged to display the virtual image VIMG1 such that each image point (P0', P1') of the virtual image VIMG1 corresponds to a different image point on the main image IMG0.
  • the waveguide plate SUB1 may have a first main surface SRF1 and a second main surface SRF2.
  • Surfaces SRF1 , SRF2 may be substantially parallel to a plane defined by directions SX and SY.
  • the spectral filters or spectral filtering regions can be realized by depositing spectrally absorbing materials on the waveguide plate SUB1.
  • the spectral filter or the spectral filter area (C1a, C2a, C1b, C2a) can be realized by converting the material of the local waveguide SUB1 into a spectrally absorbing material.
  • spectral filters or spectral filtering regions (C1a, C2a, C1b, C2b) may be formed by locally doping the waveguide plate SUB1 with one or more dopants.
  • each unit DOE1, DOE2a, DOE2b, DOE3 may contain one or more diffraction gratings to diffract light as described above.
  • unit DOE1 may contain one or more gratings G1a, G1b.
  • unit DOE2a may contain grating G2a.
  • unit DOE2b may contain grating G2b.
  • unit DOE3 may contain one or more gratings G3a, G3b.
  • the grating period (d) of the diffraction grating and the orientation ( ⁇ ) of the diffractive features of the diffraction grating can be determined from the grating vector V of said diffraction grating.
  • a diffraction grating contains a plurality of diffractive features (F) that can act as diffraction lines. Diffractive features may be, for example, tiny ridges or grooves. Diffractive features can also be, for example, microscopic protrusions (or depressions), wherein adjacent protrusions (or depressions) can act as diffraction lines.
  • a grating vector V can be defined as a vector having a direction perpendicular to the diffraction lines of a diffraction grating and a magnitude given by 2 ⁇ /d, where d is the grating period.
  • the grating period is equal to the grating period length.
  • the grating period may be the length between successive diffractive features of the grating.
  • the grating period may be equal to a unit length divided by the number of diffractive features lying within said unit length.
  • the grating periods d1a, d1b of the entrance pupil unit DOE1 may be in the range of 330nm to 450nm.
  • the optimal value of the grating period d may depend on the refractive index of the plate SUB1 and the wavelength ⁇ of the light diffracted by d.
  • the first grating of the entrance pupil unit DOE1 may be optimized for blue wavelengths
  • the second grating of the entrance pupil unit DOE1 may be optimized for red wavelengths.
  • the first grating period d1a of the entrance pupil unit DOE1 may be different from the second grating period d1b of the entrance pupil unit DOE1.
  • the entrance pupil unit DOE1 may have raster vectors V1a, V1b.
  • the first pupil expansion unit DOE2a may have a raster vector V2a.
  • the second pupil expansion unit DOE2b may have a raster vector V2b.
  • the exit pupil unit DOE3 may have raster vectors V3a, V3b.
  • the raster vector V1a has a direction ⁇ 1a and a magnitude 2 ⁇ /d1a.
  • the grating vector V1b has a direction ⁇ 1b and a magnitude 2 ⁇ /d1b.
  • the grating vector V2a has a direction ⁇ 2a and a magnitude 2 ⁇ /d2a.
  • the grating vector V2b has a direction ⁇ 2b and a magnitude 2 ⁇ /d2b.
  • the raster vector V3a has a direction ⁇ 3a and a magnitude 2 ⁇ /d3b.
  • the grating vector V3b has a direction ⁇ 3b and a magnitude 2 ⁇ /d3b.
  • the direction ( ⁇ ) of the grating vector may be defined as the angle between the grating vector and a reference direction (eg, direction SX).
  • the grating period (d) and the direction ( ⁇ ) of the diffraction grating of the optical units DOE1, DOE2a, DOE3 can be selected so that the propagation direction (k3P0, R) of the light at the central point P0 in the first output light OB3a is parallel to the input light
  • the grating period (d) and the direction ( ⁇ ) of the diffraction grating of the optical units DOE1, DOE2b, DOE3 can be selected so that the propagation direction (k3P0, R) of the light at the center point P0 of the second output light OB3b is the same as that of the input light IN1
  • the propagation direction (k0P0,R) of the light at the center point P0 is parallel.
  • the diffraction period (d) and the direction ( ⁇ ) of the diffraction grating of the optical units DOE1, DOE2a, DOE2b, DOE3 can be selected so that the propagation direction (k3P0, R) of the light at the central point P0 of the combined output light OUT1 is the same as that of the input light IN1
  • the direction of light propagation (k0P0, R) in the center point P0 is parallel.
  • the included angle between the directions of the grating vectors V1a, V1b of the entrance pupil unit DOE1 may be in the range of 60° to 120°.
  • the first grating period d1a of unit DOE1 may be different from the second grating period d1b of unit DOE1 to optimize the first path for a first color and the second path for a second different color.
  • the first grating period length d1a of the first grating of the entrance pupil unit DOE1 can be different from the second grating period length d1b of the second grating of the entrance pupil unit DOE1, so that the first grating of the entrance pupil unit DOE1 can be aimed at the wavelength of blue light ( ⁇ B ) is optimized, and the second grating of the entrance pupil unit DOE1 can be optimized for the wavelength of red light ( ⁇ R).
  • the first grating period d3a of unit DOE3 may be different from the second grating period d3b of unit DOE3 to optimize the first path for a first color and the second path for a second different color.
  • the first grating period d1a of the unit DOE1 may be different from the second grating period d1b of the unit DOE1, eg, a first path optimized for blue, and a second path for red.
  • the first grating period d3a of the unit DOE3 may be different from the second grating period d3b of the unit DOE3, for example, to optimize a first path for blue, and a second path for red.
  • the grating period (d) and direction ( ⁇ ) of the grating vector can satisfy the condition that the vector sum (m1aV1a+m2aV2a+m3aV3a) is zero for predetermined integers m1a, m2a, m3a.
  • V1a represents the raster vector of unit DOE1.
  • V2a represents the raster vector of unit DOE2a.
  • V3a represents the raster vector of unit DOE3.
  • the values of these predetermined integers are usually +1 or -1.
  • the value of the integer m1a can be +1 or -1.
  • the value of the integer m2a can be +1 or -1.
  • the value of the integer m3a can be +1 or -1.
  • the grating period (d) and direction ( ⁇ ) of the grating vector can satisfy the condition that the vector sum (m1bV1b+m2bV2b+m3bV3b) is zero for predetermined integers m1b, m2b, m3b.
  • V1b represents the raster vector of unit DOE1.
  • V2b represents the raster vector of element DOE2b.
  • V3b represents the raster vector of unit DOE3.
  • the values of these predetermined integers are usually +1 or -1.
  • the value of the integer m1b can be +1 or -1.
  • the value of the integer m2b can be +1 or -1.
  • the value of integer m3b can be +1 or -1.
  • the first unit DOE1 may have a first grating vector V1a to form a first guided light B1a along a direction DIR1a, and a second grating vector V1b to form a second guided light B1b along a direction DIR1b.
  • the first element DOE1 may have first diffractive features F1a to provide a first grating having a grating period d1a and a direction ⁇ 1a (relative to the reference direction SX).
  • the first element DOE1 may have second diffractive features F1b to provide a second grating having a grating period d1b and a direction ⁇ 1b (relative to the reference direction SX).
  • the first unit DOE1 can be realized by, for example, a crossed grating or two linear gratings.
  • the first unit DOE1 may be such that, for example, a first area of the first unit DOE1 contains a first feature F1a, while a second area of the first unit DOE1 contains a second feature F1b.
  • a first linear grating having diffractive features F1a may be disposed on the first main surface of the waveguide plate SUB1 (for example, on the input side surface SRF1), and a second linear grating having diffractive features F1b may be disposed on the first major surface of the waveguide plate SUB1.
  • Two main surfaces for example on the output side surface SRF2).
  • the diffractive features may be, for example, micro-ridges or micro-protrusions.
  • the pupil expansion unit DOE2a may have a grating vector V2a to form the third guided light B2a by diffracting the first guided light B1a.
  • the pupil expansion unit DOE2a may have diffractive features F2a to provide a grating G2a having a grating period d2a and a direction ⁇ 2a (relative to the reference direction SX).
  • the pupil expansion unit DOE2b may have a grating vector V2b and form fourth guided light B2b by diffracting the second guided light B1b.
  • the pupil expansion unit DOE2b may have diffractive features F2b to provide a grating G2b having a grating period d2b and a direction ⁇ 2b (relative to the reference direction SX).
  • the first pupil expansion unit DOE2a may have a grating period d2a for forming the guided light B2a
  • the second pupil expansion unit DOE2b may have a grating period d2b for forming the guided light B2b, wherein the grating period d2a may be different from the grating period d2b.
  • the exit pupil unit DOE3 may have a first grating vector V3a to couple the expanded light B2a out of the waveguide plate SUB1.
  • the exit pupil unit DOE3 may have a second grating vector V3b to couple the expanded light B2b out of the waveguide plate SUB1.
  • the exit pupil unit DOE3 may have diffractive features F3a to provide a grating G3a with a grating period d3a and a direction ⁇ 3a (relative to the reference direction SX).
  • the exit pupil unit DOE3 may have diffractive features F3b to provide a grating G3b with a grating period d3b and a direction ⁇ 3b (relative to the reference direction SX).
  • the exit pupil unit DOE3 can be realized by a cross grating or two linear gratings.
  • a first linear grating G3a with diffractive features F3a can be implemented on the first major surface of the waveguide plate SUB1 (e.g., SRF1), and a second linear grating G3b with diffractive features F3b can be implemented on the second major surface of the waveguide plate SUB1 ( For example, implemented on SRF2).
  • the entrance pupil unit DOE1 may have a width w1 and a height h1.
  • the first pupil dilation unit DOE2a may have a width w2a and a height h2a.
  • the second pupil dilation unit DOE2b may have a width w2b and a height h2b.
  • the exit pupil unit DOE3 may have a width w3 and a height h3.
  • the width may represent a dimension in the direction SX, and the height may represent a dimension in the direction SY.
  • the exit pupil unit DOE3 may be, for example, substantially rectangular. The edges of the exit pupil unit DOE3 may be along directions SX and SY.
  • the width w2a of the pupil dilation unit DOE2a may be much larger than the width w1 of the pupil entrance unit DOE1.
  • the width of the expanded guided beam B2a can be much larger than the width w1 of the entrance pupil unit DOE1.
  • the waveguide plate SUB1 may comprise or consist essentially of a transparent solid material.
  • the waveguide plate SUB1 may comprise, for example, glass, polycarbonate or polymethylmethacrylate (PMMA).
  • the diffractive optical elements DOE1, DOE2a, DOE2b, DOE3 may be formed by eg molding, embossing and/or etching.
  • the units DOE1, DOE2a, DOE2b, DOE3 can be realized eg by one or more surface diffraction gratings or by one or more volume diffraction gratings.
  • the spatial distribution of the diffraction efficiency can be tuned arbitrarily, e.g. by selecting the local height of the microscopic diffraction features F. Therefore, the height of the microscopic diffraction features F of the exit pupil unit DOE3 can be selected to further make the intensity distribution of the output light OUT1 uniform.
  • the entrance pupil unit includes a first entrance pupil grating and a second entrance pupil grating for forming the first guided light and the second guided light respectively, the first entrance pupil grating and the second
  • the entrance pupil grating has a first entrance pupil grating period and a second entrance pupil grating period, and the first entrance pupil grating period and the second entrance pupil grating period are different;
  • the exit pupil unit includes a first exit pupil grating and a second exit pupil grating respectively for forming the first output light and the second output light, and the first exit pupil grating and the second exit pupil grating respectively have the first exit pupil grating and the second exit pupil grating respectively.
  • An exit pupil grating period and a second exit pupil grating period, and the first exit pupil grating period is different from the second exit pupil grating period.
  • the grating periods of the first Bragg grating area and the second Bragg grating area are half of the first exit pupil grating period and the second exit pupil grating period respectively.
  • the first Bragg grating region BRGa has a grating vector VBRGa.
  • the grating vector VBRGa of the first Bragg grating area BRGa may be parallel to the grating vector VDOE3a of the exit pupil unit DOE3.
  • the direction of the grating vector VBRGa is set by the angle ⁇ BRGa.
  • the first Bragg grating region BRGa has a grating period dBRGa.
  • the grating period dBRGa of the first Bragg grating region BRGa may be equal to half of the grating period dDOE3a of the exit pupil unit DOE3.
  • the second Bragg grating region BRGb has a grating vector VBRGb.
  • the grating vector VBRGb of the second Bragg grating region BRGb may be parallel to the grating vector VDOE3b of the exit pupil unit DOE3.
  • the direction of the grating vector VBRGb is set by the angle ⁇ BRGa.
  • the second Bragg grating region BRGb has a grating period dBRGb.
  • the grating period dBRGb of the second Bragg grating region BRGb may be equal to half of the grating period dDOE3b of the exit pupil unit DOE3.
  • the first Bragg grating region BRGa may have diffractive features FBRGa.
  • the second Bragg grating region BRGa may have diffraction characteristics FBRGb.
  • the cross-sectional shape of the diffractive features FBRGa, FBRGb may be binary, trapezoidal, sinusoidal or oblique.
  • the diffraction characteristics of FBRGa and FBRGb may also be those of a volume grating.
  • the Bragg grating regions BRGa, BRGb can be formed by embossing or embossing.
  • the layer of optically absorbing material of the spectral filter regions C2a, C2b may be added before or after forming the diffractive features FBRGa, FBRGb.
  • the filter region C2a can be formed by applying a thin layer of absorbing material on the plate SUB1, wherein the Bragg grating region BRGa can then be formed by embossing the layer of absorbing material and the surface of the waveguide plate SUB1.
  • the diffractive features FBRGa may be formed on the surface of the waveguide plate SUB1, and the diffractive features FBRGa may then be covered by the layer of optically absorbing material of the filter region C2a.
  • Figures 8a to 8c demonstrate the input angles for coupling light into the waveguide plate.
  • the wave vector of the guided light should reside in the zone ZONE1 between the first boundary BND1 and the second boundary BND2.
  • the zone ZONE1 and the first boundary BND1 and the second boundary BND2 are shown in Figs. 9a to 10g.
  • Figure 8a illustrates, through a cross-sectional side view, the formation of a first guided light by coupling an input beam into a waveguide where the tilt angle of the first guided light is near the critical angle for total internal reflection
  • the situation of Fig. 8a may correspond to operation near the first boundary BND1 of the zone ZONE1.
  • Figure 8b illustrates, through a cross-sectional side view, the formation of a first guided light by coupling an input beam into a waveguide where the angle of inclination of the first guided light Close to 90 degrees.
  • the situation of Fig. 8b may correspond to operation near the second boundary BND2 of the zone ZONE1.
  • the curve CRV1 in FIG. 8c shows the functional relationship between the tilt angle ⁇ k1 of the wave vector k1 of the first guided light B1a and the input angle ⁇ k0 of the wave vector k0 of the input light B0.
  • the tilt angle ⁇ k1 may represent the angle between the wave vector sum direction SZ and the reference plane REF1 defined by SY.
  • the first angle limit ⁇ BND1 may correspond to the tilt angle ⁇ k1 of the first guided wave equal to the critical angle of total internal reflection Case.
  • the second angle limit ⁇ BND2 may correspond to the case where the inclination angle ⁇ k1 of the first guided light is equal to 90 degrees.
  • Fig. 9a gives by way of example a wave vector diagram of blue light propagating along a first path inside the waveguide plate SUB1.
  • the first path may be a clockwise path.
  • the wave vector of the input light IN1 may exist in one region BOX0 of the wave vector space defined by the initial wave vectors kx and ky. Each corner of the region BOX0 can represent a wave vector of light at a corner point of the input image IMG0 (Fig. 9d).
  • the wave vector of the first guided light B1a may be within the area BOX1a.
  • the wave vector of the third guided light B2a may be within the area BOX2a.
  • the wave vector of the first output light OB3a may be within the area BOX3.
  • the entrance pupil unit DOE1 can form the first guided light B1a by diffracting the input light IN1. Diffraction can be represented by adding the grating vector m1aV1a of the entrance pupil unit DOE1 to the wavevector of the input light IN1.
  • the wavevector of the first guided light B1a can be determined by adding the grating vector m1aV1a to the wavevector of the input light IN1.
  • the wave vector of the third guided light B2a can be determined by adding the grating vector m2aV2a to the wave vector of the first guided light B1a.
  • the wavevector of the outgoing light OB3a can be determined by adding the grating vector m3aV3a to the wavevector of the second guided light B2a.
  • BND1 represents the first boundary for satisfying the total internal reflection (TIR) criterion in the waveguide plate SUB1.
  • BND2 represents the second boundary of the maximum wave vector in the waveguide plate SUB1.
  • the maximum wave vector can be determined by the refractive index of the waveguide plate.
  • Light can be waveguided in the slab SUB1 only when the wave vector of said light is in the zone ZONE1 between the first boundary BND1 and the second boundary BND2. If the wavevector of the light is outside zone ZONE1, the light may leak out of the waveguide plate or not propagate at all.
  • the grating period d1a of the entrance pupil unit DOE1 may be chosen such that, for example, all wave vectors of the first blue guided wave light B1a are within the zone ZONE1 delimited by the boundaries BND1, BND2.
  • kx represents the direction in the wave vector space, where the direction kx is parallel to the direction SX in the actual space.
  • ky represents the direction in the wave vector space, where the ky direction is parallel to the SY direction in the actual space.
  • the symbol kz (not shown in the figure) indicates the direction in the wave vector space, where the direction kz is parallel to the direction SZ in the real space.
  • the wave vector k can have components in the directions kx, ky and/or kz.
  • Figures 9b and 9c illustrate, by way of example, the vector diagrams of the wave vector of red light propagating along the first path in the waveguide plate SUB1.
  • the wave vectors of some corner points of the red light may be outside the zone ZONE1.
  • the waveguide plate SUB1 cannot confine or guide the red light of some corner points of the input image IMG0.
  • the wave vector falling in the sub-region FAIL1 of the region BOX1a corresponds to the situation that the input unit DOE1 cannot form guided light by diffracting the input light.
  • the diffraction equation has no correct practical solution for the wave vectors existing in the sub-region FAIL1 of the region BOX1a. Therefore, in case the wave vector of the guided light is outside the zone ZONE1, it is not possible to couple red light into the waveguide plate for some image points.
  • the leakage of red light may limit the angular width of the displayed virtual image VIMG1.
  • the boundaries BND1, BND2 of the zone ZONE1 can limit the angular width of the displayed virtual image VIMG1 Formation of wave vectors outside zone ZONE1 may mean light leakage from the waveguide plate or failure of optical coupling.
  • the first path of the optical pupil expansion device EPE1 may contain one or more spectral filter areas C1a, C2a to prevent incomplete red pictures from interfering with the final displayed picture (VIMG1).
  • the optical pupil expansion device EPE1 may comprise a spectral filter zone C2a to provide a suppression zone ZONE2 for the guided light B2a.
  • the spectral filter region C2a may be arranged to eliminate the red component of the guided light B2a.
  • Figures 9d and 9e show, by way of example, the wave vectors of blue light for image points (P0, P1, P2, P3, P4) in the wave vector space.
  • Fig. 10a gives by way of example a wave vector diagram of red light propagating along the second path in the waveguide plate SUB1.
  • the second path may be, for example, a counterclockwise path.
  • the grating period d1b of the coupling unit DOE1 can be chosen such that, for example, all wave vectors of the second red guided wave light B1b are within the zone ZONE1 delimited by the boundaries BND1, BND2.
  • Figures 10b to 10d show the wave vector diagrams of blue light propagating in the waveguide plate SUB1 along the second path by way of comparative examples, in which case the propagation of blue light on the second path cannot be avoided.
  • Figures 10b to 10d demonstrate the formation of an incomplete blue image.
  • the wave vectors of the blue light at some corner points may be outside the zone ZONE1.
  • the waveguide SUB1 cannot limit the blue light of some corner points of the input image IMG0. Leakage of blue light may limit the angular width of the displayed virtual image VIMG1.
  • the wave vector falling in the sub-region LEAK1 of the region BOX2b represents the light not confined in the waveguide plate by total internal reflection.
  • Figure 10e illustrates by way of pictorial example the suppression zone ZONE3 used to eliminate incomplete blue images from the second path.
  • the first path of the optical pupil expansion device EPE1 may contain one or more spectral filter areas C1a, C2a to prevent incomplete blue pictures from interfering with the final displayed picture (VIMG1).
  • Figures 10f and 10g give by way of example wave vector diagrams for red light propagating along the second path within the waveguide plate SUB1.
  • the second path may be, for example, a counterclockwise path.
  • the wave vector of the input light IN1 may exist in one region BOX0 of the wave vector space.
  • Each corner of the area BOX0 can respectively represent a wave vector showing the corner points of the image IMG0.
  • the wave vector of the second guided light B1b may be within the region BOX1b.
  • the wave vector of the fourth guided light B2b may be within the area BOX2b.
  • the wave vector of the first output light OB3b may be within the area BOX3.
  • the optical pupil expansion device EPE1 may be arranged to provide a first path and a second path.
  • the first path can provide the full width of the blue display image VIMG1
  • the second path can provide the full width of the display image VIMG1 in red Therefore, the optical pupil expansion device EPE1 can be configured to display a Color virtual image VIMG1.
  • the optical pupil expansion device EPE1 can be set to display all corner points (P1, P2, P3, P4) of the color virtual image VIMG1 having a full width in red and blue
  • the angular width of the color virtual image VIMG1 displayed by using two paths Can be substantially larger than the maximum angular width (LIM1) of a color virtual image displayed by other devices (EPE0) that do not use the second path.
  • the optical pupil expansion device EPE1 with two paths can be arranged to display a color virtual image VIMG1 with an extended angular width
  • the first path may be configured to transmit the blue component of the input image while allowing leakage of red light at one or more corner points of the input image.
  • the second path can be set to transmit the red component of the input image while allowing blue light to leak from one or more corner points of the input image.
  • the entrance pupil unit (DOE1) can be set as:
  • raster vectors (m1aV1a, m2aV2a, m3aV3a, m1bV1b, m2bV2b, m3bV3b) of cells (DOE1, DOE2a, DOE2b, DOE3) are selected such that:
  • the red light from the first corner point (P1) is directed from the entrance pupil unit (DOE1) to the exit pupil unit (DOE3) through the second pupil dilation unit (DOE2b),
  • the first guided light (B1a) does not contain the red light of the first corner point (P1)
  • the blue light of the second corner point (P2) is directed from the entrance pupil unit (DOE1) to the exit pupil unit (DOE3) through the first pupil dilation unit (DOE2a), and
  • the blue light of the second corner point (P2) fails to meet the criterion of total internal reflection (TIR) between the entrance pupil unit (DOE1) and the second pupil expansion unit (DOE2b).
  • the entrance pupil unit (DOE1) can be set as:
  • raster vectors (m1aV1a, m2aV2a, m3aV3a, m1bV1b, m2bV2b, m3bV3b) of cells (DOE1, DOE2a, DOE2b, DOE3) are selected such that:
  • the red light from the first corner point (P1) is directed from the entrance pupil unit (DOE1) to the exit pupil unit (DOE3) through the second pupil dilation unit (DOE2b),
  • the first guided light (B1a) does not contain the red light of the first corner point (P1)
  • the blue light of the first corner point (P1) is directed from the entrance pupil unit (DOE1) to the exit pupil unit (DOE3) through the first pupil dilation unit (DOE2a),
  • the blue light of the first corner point (P1) fails to pass through the second pupil dilation unit (DOE2b) from the entrance pupil unit (DOE1) to the exit pupil unit (DOE3),
  • the red light of the second corner point (P2) fails to pass through the first pupil dilating unit (DOE2a) from the entrance pupil unit (DOE1) to the exit pupil unit (DOE3),
  • the red light from the second corner point (P2) is directed from the entrance pupil unit (DOE1) to the exit pupil unit (DOE3) through the second pupil dilation unit (DOE2b),
  • the blue light of the second corner point (P2) is directed from the entrance pupil unit (DOE1) to the exit pupil unit (DOE3) through the first pupil dilation unit (DOE2a), and
  • the blue light of the second corner point (P2) cannot satisfy the condition of total internal reflection (TIR) between the entrance pupil unit (DOE1) and the second pupil expansion unit (DOE2b).
  • the optical pupil expanding device EPE1 may be arranged to operate such that, in the case of blue guided wave light propagating via the first path of the device EPE1, the wave vector of the blue guided wave light falls within the zone ZONE1, and the device EPE1 may be arranged to, at In case the red guided light propagates through the second path of the device EPE1, the wave vector of the red guided light falls within the zone ZONE1.
  • An embodiment of the present invention also provides a display device, including the above-mentioned optical pupil dilation device, and an optical engine for forming a main image.
  • the optical engine ENG1 may consist of a display DISP1 and a collimating optic LNS1.
  • the display DISP1 may be set to display the input image IMG0.
  • the display DISP1 may also be called a microdisplay.
  • the display DISP1 may also be referred to as a spatial light intensity modulator.
  • the input image IMG0 may also be referred to as an image source.
  • the input image IMG0 may contain a center point P0 and four corner points P1, P2, P3, P4.
  • P1 may represent the upper left corner point.
  • P2 may represent the upper right corner point.
  • P3 may represent the lower left corner point.
  • P4 may represent the lower right corner point.
  • the input image IMG0 may contain graphic characters such as "F", "G” and "H”.
  • the input image IMG0 can be a color image.
  • the input image IMG0 may be, for example, an RGB image, which may contain a red partial image, a green partial image and a blue partial image.
  • Each image point can provide eg red, green and/or blue light.
  • Red light can be expressed as red, for example, with a wavelength of 650nm
  • green light can be expressed as green, for example, with a wavelength of 510nm.
  • Blue light can appear blue, for example, with a wavelength of 470nm.
  • the light at the corner point of the color image IMG0 may contain red light and blue light.
  • Optical engine ENG1 may provide input light IN1, which may comprise a plurality of substantially collimated beams (B0). Each red beam may travel in a different direction and may correspond to a different point of the input image IMG0.
  • a red light beam B0P1,R may correspond to image point P1 and propagate in the direction of wave vector k0P1,R.
  • the blue light beam (B0P1,B) may correspond to the same image point P1, and propagate in the direction of the wave vector (k0P1,B).
  • the propagation direction (k0P1,B) of the blue beam (B0P1,B) corresponding to the first corner point P1 of the input image IMG0 can be parallel to the red beam (B0P1,R) corresponding to the first corner point P1
  • the direction of propagation (k0P1,R) can be parallel to the red beam (B0P1,R) corresponding to the first corner point P1 The direction of propagation (k0P1,R).
  • the propagation direction (k0P2,B) of the blue light beam (B0P2,B) corresponding to the second corner point P2 of the input image IMG0 can be parallel to the red light beam (B0P2,R) corresponding to the second corner point P2
  • the red light beam B0P2,R may correspond to the image point P2 and propagate in the direction of the wave vector k0P2,R.
  • the red light beam B0P3,R may correspond to the image point P3 and propagate in the direction of the wave vector k0P3,R.
  • a red light beam B0P4,R may correspond to image point P4 and propagate in the direction of wave vector k0P4,R.
  • the red light beam B0P0,R may correspond to the central image point P1 and propagate in the direction of the wave vector k0P0,R.
  • the wavevector (k) of light can be defined as the vector having the direction of propagation of said light, given magnitude by 2 ⁇ / ⁇ , where ⁇ is the wavelength of said light.
  • the output light OUT1 may include a plurality of output light beams, which may correspond to the displayed virtual image VIMG1. Each output beam corresponds to an image point at a different position on the image.
  • a red light beam propagating in the direction of wave vector k3P0,R may correspond to point P0' of image VIMG1.
  • a red light beam propagating in the direction of wave vector k3P1,R may correspond to point P1' of image VIMG1.
  • a red light beam propagating in the direction of wave vector k3P2,R may correspond to point P2' of image VIMG1.
  • a red light beam propagating in the direction of wave vector k3P3,R may correspond to point P3'.
  • a red beam propagating in the direction of wave vector k3P4,R may correspond to point P4'.
  • the optical pupil expanding device EPE1 can form the output light OUT1 by expanding the exit pupil of the light engine ENG1.
  • the output light OUT1 may include a plurality of output beams corresponding to the displayed virtual image VIMG1.
  • the output light beam OUT1 can be irradiated on the observer's eye EYE1, so that the observer can see the displayed virtual image VIMG1.
  • the displayed virtual image VIMG1 may have a center point P0' and four corner points P1', P2', P3', P4'.
  • the input light IN1 may comprise a plurality of light beams corresponding to points P0, P1, P2, P3, P4 of the input image IMG0.
  • the optical pupil expansion device EPE1 can diffract and transmit the light from the point P0 of the input image IMG0 to form the point P0' of the displayed virtual image VIMG1.
  • the optical pupil expansion device EPE1 can form points P1', P2', P3', P4' by diffracting and transmitting light from points P1, P2, P3, P4, respectively.
  • the optical pupil expansion device EPE1 may form an output light OUT1 comprising a plurality of beams propagating in different directions specified by wave vectors k3P0,R, k3P1,R, k3P2,R, k3P3,R, k3P4,R, etc.
  • the red light beam corresponding to point P0' of the displayed virtual image VIMG1 has a wave vector k3P0,R.
  • the red beam corresponding to point P1' has wave vector k3P1,R.
  • the red beam corresponding to point P2' has wave vector k3P2,R.
  • the red beam corresponding to point P3' has wave vector k3P3,R.
  • the red beam corresponding to point P4' has wave vector k3P4,R.
  • the optical pupil expansion device EPE1 can be designed such that the wave vector k3P1,R is parallel to the wave vector k0P1,R of the red light corresponding to the point P1 in the input light IN1.
  • the wave vector k3P0,R may be parallel to the wave vector k0P0,R corresponding to the point P0.
  • the wave vector k3P2,R may be parallel to the wave vector k0P2,R corresponding to the point P2.
  • the wave vector k3P3,R may be parallel to the wave vector k0P3,R corresponding to the point P3.
  • the wave vector k3P4,R may be parallel to the wave vector k0P4,R corresponding to the point P4.
  • the displayed virtual image VIMG1 may have, for example, a first corner point P1 ′, on the left side of the image VIMG1 ; and a second corner point P2 ′, eg, on the right side of the image VIMG1 .
  • the angular width of the virtual image VIMG1 may be equal to the horizontal angle between the wave vectors k3P1,R, k3P2,R of the corner points P1', P2'.
  • the displayed virtual image VIMG1 may have an upper corner point P1' and a lower corner point P3'.
  • the angular height ⁇ of the virtual image VIMG1 may be equal to the vertical angle between the wave vectors k3P1,R, k3P3,R of the corner points P1', P3'.
  • the two paths of the optical pupil expansion device EPE1 may allow displaying a wide color virtual image VIMG1.
  • the two paths of the optical pupil expander EPE1 allow display with extended angular width Color virtual image VIMG1.
  • angle can represent the angle between the wave vector and the reference plane REF1.
  • a reference plane REF1 may be defined as the plane of the directions SZ and SY.
  • the angle ⁇ may represent the angle between the wave vector and the reference plane REF2.
  • a reference plane REF2 may be defined as the plane of the directions SZ and SX.
  • the display device 500 may be a virtual reality device 500 .
  • the display device 500 may be an augmented reality device 500 .
  • the display apparatus 500 may be a near-eye device.
  • the display device 500 may be a wearable device, such as a helmet.
  • the display device 500 may include, for example, a headband, and the display device 500 may be worn on the user's head through the headband.
  • the pupil exit unit DOE3 may be positioned, for example, in front of the user's left eye EYE1 or right eye EYE1.
  • the display apparatus 500 may project the output light OUT1 into the user's eye EYE1.
  • the display device 500 may include two engines ENG1 and/or two optical pupil expansion devices EPE1 to display stereoscopic images.
  • the light engine ENG1 may be arranged to generate still images and/or video.
  • the light engine ENG1 can generate the real main image IMG0 from the digital image.
  • the light engine ENG1 can receive one or more digital images from the Internet or a smartphone.
  • the display device 500 may be a smartphone.
  • the displayed image can be viewed by a human, but also by an animal or a machine (possibly including, for example, a camera).
  • the display apparatus 500 may include an optical engine ENG1 to form a main image IMG0 and convert the main image IMG0 into a plurality of light beams of the input light IN1.
  • Light from the light engine ENG1 can be coupled in from the entrance pupil unit DOE1 of the optical pupil expander EPE1.
  • the input light IN1 can be coupled in from the entrance pupil unit DOE1 of the optical pupil expansion device EPE1.
  • the display device 500 may be a display device for displaying virtual images.
  • the display device 500 may also be a near-eye optical device.
  • the optical pupil expansion device EPE1 can propagate the virtual image content from the light engine ENG1 in front of the user's eye EYE1.
  • the optical pupil expansion device EPE1 can expand the pupil, thereby enlarging the eyebox.
  • the light engine ENG1 may contain a microdisplay DISP1 to generate the main image IMG0.
  • the microdisplay DISP1 may comprise a two-dimensional array of light-emitting pixels.
  • the display DISP1 can generate, for example, the main image IMG0 with a resolution of 1280 ⁇ 720 (HD).
  • the display DISP1 can generate for example the main image IMG0 with a resolution of 1920 ⁇ 1080 (Full HD)).
  • the display DISP1 can generate, for example, the main image IMG0 with a resolution of 3840 ⁇ 2160 (4K UHD).
  • the main image IMG0 may contain multiple image points P0, P1, P2, . . .
  • the light engine ENG1 may contain collimating optics LNS1 to form a different light beam for each image pixel.
  • Light engine ENG1 may comprise collimating optics LNS1 to form a substantially collimated beam of light from image point P0.
  • the center of the display DISP1 and the center of the optics LNS1 may define an optical axis AX0 of a light engine ENG1.
  • the point P0 and the center point of the optic LNS1 may define an optical axis AX0.
  • the light beam corresponding to the image point P0 may propagate in the direction specified by the wave vector k0P0,R.
  • Light beams corresponding to different image points P1 may propagate in a direction k0P1,R different from the direction k0P0,R.
  • the light engine ENG1 may provide a plurality of light beams corresponding to the generated main image IMG0. One or more light beams provided by the light engine ENG1 can be coupled into the optical pupil expansion device EPE1 as input light IN1.
  • the light engine ENG1 may comprise, for example, one or more light emitting diodes (LEDs).
  • the display DISP1 may include one or more microdisplay imagers, such as liquid crystal on silicon (LCOS), liquid crystal display (LCD), and digital micromirror device (DMD).
  • LCOS liquid crystal on silicon
  • LCD liquid crystal display
  • DMD digital micromirror device
  • the embodiment of the present invention also provides a beam expansion method, which uses the above-mentioned optical pupil expanding device to expand the beam.
  • An embodiment of the present invention also provides an image display method, which uses the above-mentioned optical pupil dilation device for image display.

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Abstract

光学扩瞳装置（EPE1）、显示装置、光束扩展方法及图像显示方法，该光学扩瞳装置（EPE1）包括波导板（SUB1），所述波导板（SUB1）上设置有：入瞳单元（DOE1），用于通过衍射输入光以形成第一导波光和第二导波光；第一扩瞳单元（DOE2a），用于衍射第一导波光以形成第三导波光；第二扩瞳单元（DOE2b），用于衍射第二导波光以形成第四导波光；出瞳单元（DOE3），用于衍射第三导波光以形成第一输出光，和用于衍射第四导波光以形成第二输出光，以及将第一输出光和第二输出光组合形成组合输出光；入瞳单元（DOE1）和出瞳单元（DOE3）沿波导板（SUB1）对角线设置，且出瞳单元（DOE3）设置于入瞳单元（DOE1）的下方，第一扩瞳单元（DOE2a）和第二扩瞳单元（DOE2b）设置于入瞳单元（DOE1）和出瞳单元（DOE3）的两侧。通过该光学扩瞳装置（EPE1）可以提供更大的视场角度的全彩色显示。

Description

光学扩瞳装置、显示装置、光束扩展方法及图像显示方法 技术领域
本发明涉及显示技术领域，特别涉及光学扩瞳装置、显示装置、光束扩展方法及图像显示方法。
背景技术
结合图1，一种光学扩瞳装置EPE0包含波导板SUB01，所述波导板又包含衍射入瞳单元DOE01，衍射扩瞳单元DOE02和衍射出瞳单元DOE03。所述光学扩瞳装置通过对输入光束IN1的多次衍射扩束，最后形成输出光OUT1。
所述输入光IN1可由光引擎ENG1发出。所述光引擎ENG1可以由微型显示器DISP1和准直光学器件LNS1组成。
所述耦合入瞳单元DOE01通过衍射，将所述输入光IN1衍射成第一传导光B1。所述扩瞳单元DOE02通过衍射，将所述第一导波光B1扩展衍射而形成导波光B2。所述衍射出瞳单元DOE03通过扩展衍射，将所述导波光B2衍射扩展为输出光OUT1。
所述光学扩瞳装置EPE0可以在方向SX和在方向SY这两个方向上扩展光束。所述输出光OUT1的宽度wOUT1可以远大于输入光IN1的宽度wIN1。所述光学扩瞳装置EPE0可以用于扩展虚拟显示装置的视瞳，以便于眼睛EYE1相对于虚拟显示装置的观察位置有更大的舒适观察位置。观察者的眼睛EYE1可以在输出光束的观察位置内看到完成的虚拟图像。所述输出光可以包含一个或多个输出光束，其中每个输出光束可以对应于显示的虚拟图像VIMG1的不同图像位置。所述光学扩瞳装置也可以称为例如扩瞳单元，光学扩瞳装置件，光学扩瞳装置等。
所示虚拟图像VIMG1可具有角度展宽LIM1。一种如图1所示的利用光学扩瞳装置EPE0实现全彩虚拟图像VIMG1显示的方式可能会造成位于虚拟图像边缘或角落像点发出的红色或蓝色光线在传输过程中无法满足所述波导SUB01的全反射条件。从而造成虚拟图像VIMG1的一个或多个角落区域会出现缺少红 色或者蓝色光线的现象。
发明内容
本发明实施例提供了一种光学扩瞳装置、显示装置、光束扩展方法及图像显示方法，旨在显示全彩图片，以提供更大的视场角度的全彩色显示。
第一方面，本发明实施例提供了一种光学扩瞳装置，包括波导板，所述波导板上设置有：
入瞳单元，用于通过衍射输入光以形成第一导波光和第二导波光；
第一扩瞳单元，用于衍射所述第一导波光以形成第三导波光；
第二扩瞳单元，用于衍射所述第二导波光以形成第四导波光；
出瞳单元，用于衍射所述第三导波光以形成第一输出光，和用于衍射第四导波光以形成第二输出光，以及将所述第一输出光和第二输出光组合形成组合输出光；
所述入瞳单元和出瞳单元沿所述波导板对角线设置，且所述出瞳单元设置于所述入瞳单元的下方，所述第一扩瞳单元和第二扩瞳单元设置于所述入瞳单元和出瞳单元的两侧。
第二方面，本发明实施例提供了一种显示装置，包括如第一方面所述的光学扩瞳装置，以及用于形成主图像的光学引擎。
第三方面，本发明实施例提供了一种光束扩展方法，采用如第一方面所述的光学扩瞳装置进行光束扩展。
第四方面，本发明实施例提供了一种图像显示方法，采用如第一方面所述的光学扩瞳装置进行图像显示。
本发明实施例提供了一种光学扩瞳装置、显示装置、光束扩展方法及图像显示方法，该光学扩瞳装置，包括波导板，所述波导板上设置有：入瞳单元，用于通过衍射输入光以形成第一导波光和第二导波光；第一扩瞳单元，用于衍射所述第一导波光以形成第三导波光；第二扩瞳单元，用于衍射所述第二导波光以形成第四导波光；出瞳单元，用于衍射所述第三导波光以形成第一输出光，和用于衍射第四导波光以形成第二输出光，以及将所述第一输出光和第二输出光组合形成组合输出光；所述入瞳单元和出瞳单元沿所述波导板对角线设置，且所述出瞳单元设置于所述入瞳单元的下方，所述第一扩瞳单元和第二扩瞳单 元设置于所述入瞳单元和出瞳单元的两侧。本发明实施例可以提供两条不同的光传输路径，以克服由波导板导光能力造成的限制，实现宽图像的不同颜色光在波导内的传输，从而显示全彩图片，以提供更大的视场角度的全彩色显示。
附图说明
为了更清楚地说明本发明实施例技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为现有技术中的一种光学扩瞳装置的结构示意图；
图2a为本发明实施例提供的一种光学扩瞳装置的结构示意图；
图2b为本发明实施例提供的一种光学扩瞳装置中沿第一路径传播的导波光的光谱滤波示意图；
图2c为本发明实施例提供的一种光学扩瞳装置中沿第二路径传播的导波光的光谱滤波示意图；
图3a为本发明实施例提供的一种显示装置的三维示意图；
图3b为本发明实施例提供的一种光学扩瞳装置中通过第一输出光和第二输出光的叠加形成整体输出光的示意图；
图4a为本发明实施例提供的一种光学扩瞳装置中第二扩瞳单元衍射从第一扩瞳单元接收到蓝光时，形成干扰的鬼影光束的示意图；
图4b为本发明实施例提供的一种光学扩瞳装置中第一扩瞳单元衍射从第二扩瞳单元接收到红光时，形成干扰的鬼影光束的示意图；
图5a为本发明实施例提供的一种光学扩瞳装置中第一滤色区域和第一布拉格光栅区域在波导板的同一面的扩瞳装置的截面示意图；
图5b为本发明实施例提供的一种光学扩瞳装置中第一光谱滤光片区域和第一布拉格光栅区域在波导板的不同面的截面示意图；
图5c为本发明实施例提供的一种光学扩瞳装置中导波光在布拉格光栅区域的多次连续反射的示意图；
图5d为本发明实施例提供的一种光学扩瞳装置中第一光谱滤光片区域和第一布拉格光栅区域的一个重叠区域的示意图；
图6a为本发明实施例提供的一种光学扩瞳装置中第一布拉格光栅区域截面的宽度和第二布拉格光栅区域截面的高度的示意图；
图6b为本发明实施例提供的一种显示装置的截面示意图；
图6c为本发明实施例提供的一种光学扩瞳装置中第二布拉格光栅区域的蓝光的反射的截面示意图；
图7a为本发明实施例提供的一种光学扩瞳装置中出瞳单元的出瞳区域的示意图；
图7b为本发明实施例提供的一种光学扩瞳装置的尺寸示意图；
图7c为本发明实施例提供的一种光学扩瞳装置的另一尺寸示意图；
图8a为本发明实施例提供的一种光学扩瞳装置中通过将输入光束耦合到波导中形成第一导波光，其中第一导波光的倾斜角接近全内反射的临界角的截面示意图；
图8b为本发明实施例提供的一种光学扩瞳装置中通过将输入光束耦合到波导中形成第一导波光，其中第一导波光的倾斜角度接近90度的截面示意图；
图8c为本发明实施例提供的一种光学扩瞳装置中第一导波光的波矢角度与输入光的波矢角度之间的关系示意图；
图9a为本发明实施例提供的一种光学扩瞳装置中沿第一路径传播的蓝光波矢的矢量图；
图9b和9c为本发明实施例提供的一种光学扩瞳装置中沿第一路径传播的红光波矢的矢量图；
图9d和9e为本发明实施例提供的一种光学扩瞳装置中沿第一路径传播的显示图像角落点的蓝光波矢的矢量图；
图10a为本发明实施例提供的一种光学扩瞳装置中沿第二路径传播的红光波矢的矢量图；
图10b为本发明实施例提供的一种光学扩瞳装置中蓝光波矢的矢量图；
图10c和10d为本发明实施例提供的一种光学扩瞳装置中显示图像角落点的蓝光波矢的矢量图；
图10e为本发明实施例提供的一种光学扩瞳装置中沿第二路径传播的蓝光波矢的矢量图；
图10f和10g为本发明实施例提供的一种光学扩瞳装置中沿第二路径传播的 显示图像角落点的红光波矢的矢量图；
图11a为本发明实施例提供的一种光学扩瞳装置中角落点P1的蓝光在波导板SUB1中的传播示例图；
图11b为本发明实施例提供的一种光学扩瞳装置中角落点P1的红光在波导板SUB1中的传播示例图；
图12a为本发明实施例提供的一种光学扩瞳装置中角落点P2的蓝光在波导板SUB1中的传播示例图；
图12b为本发明实施例提供的一种光学扩瞳装置中角落点P2的红光在波导板SUB1中的传播示例图；
图13a为本发明实施例提供的一种光学扩瞳装置中中心点P0的蓝光在波导板SUB1中的传播示例图；
图13b为本发明实施例提供的一种光学扩瞳装置中中心点P0的红光在波导板SUB1中的传播示例图；
图14a为本发明实施例提供的一种光学扩瞳装置中角落点P3的蓝光在波导板SUB1中的传播示例图；
图14b为本发明实施例提供的一种光学扩瞳装置中角落点P3的红光在波导板SUB1中的传播示例图；
图15a为本发明实施例提供的一种光学扩瞳装置中角落点P4的蓝光在波导板SUB1中的传播示例图；
图15b为本发明实施例提供的一种光学扩瞳装置中角落点P4的红光在波导板SUB1中的传播示例图；
图16a-图16e为本发明实施例提供的一种显示装置中光引擎如何形成入射光线的示意图；
图16f为本发明实施例提供的一种显示装置中虚拟图像的显示示意图；
图16g为本发明实施例提供的一种显示装置中虚拟图像的水平角幅度示意图；
图16h为本发明实施例提供的一种显示装置中虚拟图像的俯仰角幅度示意图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
应当理解，当在本说明书和所附权利要求书中使用时，术语“包括”和“包含”指示所描述特征、整体、步骤、操作、元素和/或组件的存在，但并不排除一个或多个其它特征、整体、步骤、操作、元素、组件和/或其集合的存在或添加。
还应当理解，在此本发明说明书中所使用的术语仅仅是出于描述特定实施例的目的而并不意在限制本发明。如在本发明说明书和所附权利要求书中所使用的那样，除非上下文清楚地指明其它情况，否则单数形式的“一”、“一个”及“该”意在包括复数形式。
还应当进一步理解，在本发明说明书和所附权利要求书中使用的术语“和/或”是指相关联列出的项中的一个或多个的任何组合以及所有可能组合，并且包括这些组合。
下面请参见图2a，本发明实施例提供的一种光学扩瞳装置EPE1，包括波导板SUB1，所述波导板SUB1上设置有：
入瞳单元DOE1，用于通过衍射输入光以形成第一导波光和第二导波光；
第一扩瞳单元DOE2a，用于衍射所述第一导波光以形成第三导波光；
第二扩瞳单元DOE2b，用于衍射所述第二导波光以形成第四导波光；
出瞳单元DOE3，用于衍射所述第三导波光以形成第一输出光，和用于衍射第四导波光以形成第二输出光，以及将所述第一输出光和第二输出光组合形成组合输出光；
所述入瞳单元DOE1和出瞳单元DOE3沿所述波导板SUB1对角线设置，且所述出瞳单元DOE3设置于所述入瞳单元DOE1的下方，所述第一扩瞳单元DOE2a和第二扩瞳单元DOE2b设置于所述入瞳单元DOE1和出瞳单元DOE3的两侧。
本实施例可以显示彩色图片，彩色图像可以是RGB图像，包含红(R)光，绿(G)光和蓝(B)光。增加显示图像的出瞳尺寸可能会导致显示图像边缘或角落像点的蓝光和/或红光泄漏。光学扩瞳装置EPE1的入瞳单元DOE1接受的 红光或蓝光，可能无法全部通过全内反射被限制在波导板内。本发明提出的光学扩瞳装置EPE1可以提供两条不同的光传输路径，以克服由波导板导光能力造成的限制，实现宽图像的不同颜色光在波导内的传输。
所述光学扩瞳装置EPE1可以将输入光分开，分别经由第一路径和经由第二路径传播到出瞳单元DOE3。第一路径可以通过第一扩瞳单元DOE2a实现从入瞳单元DOE1到出瞳单元DOE3的光传输。第二路径可以通过第二扩瞳单元实现从入瞳单元DOE1到出瞳单元DOE3的光传输。通过优化第一路径，用于传播图像边缘或角落点的蓝光，同时通过优化第二路径，用于传播图像或边缘角落点的红光。因此，所述光学扩瞳装置EPE1可以使得所有角落点发出的红色和蓝色光都传输正常。蓝光可以通过第一路径传播到出瞳单元，红光可以通过第二路径传播到出瞳单元DOE3。这样，不同的颜色分量通过不同的路径可以在光学扩瞳装置EPE1的输出处相互补偿，在出瞳单元DOE3进行组合以显示一个全彩的宽图像。
所述第一路径可针对蓝光的衍射进行优化，所述第二路径可针对红光的衍射进行优化。第一路径的光栅周期可以与第二路径的光栅周期不同，因此，蓝光沿第二条路径非计划的传播可能会导致鬼影，影响图片的显示。同样的，红光沿第一条路径非计划的传播可能也会导致鬼影，影响图片的显示。
参照图2a，光学扩瞳装置EPE1可以包含基本平面的波导板SUB1，其又包含衍射入瞳单元DOE1，第一扩瞳单元DOE2a，第二扩瞳单元DOE2b和衍射出瞳单元DOE3。所用到光栅单元可以在波导板SUB1的第一表面上或第二表面上。
入瞳单元DOE1可以接收输入光IN1，而出瞳单元DOE3可以提供输出光OUT1。输入光IN1可以包含在不同方向上传播的多个光束。输出光OUT1可以包含由输入光IN1中的光束B0形成的多个扩展光束。
输出光OUT1的宽度wOUT1可以大于输入光IN1的宽度wIN1。光学扩瞳装置EPE1可以在二维上(例如，沿水平方向SX和沿垂直方向SY)扩展输入光IN1。扩展过程也可以称为扩瞳。光学扩瞳装置EPE1可以称为光束扩瞳装置或出射光瞳扩瞳装置。
入瞳单元DOE1可以通过衍射输入光IN1来形成第一导波光B1a和第二导波光B1b。第一导波光B1a和第二导波光B1b可以在平面波导板SUB1内传播。第一导波光B1a和第二导波光B1b可以通过全内反射被限制在板SUB1内。
术语“传导”可以表示光在平面波导板SUB1内传播，从而通过全内反射(TIR)将光束限制在波导板内。术语“传导”可以表示与术语“波导”相同的含义。
入瞳单元DOE1可以经由两个不同的路径，即经由第一扩瞳单元DOE2a和第二扩瞳单元DOE2b，耦合输入光IN1以传播至出瞳单元DOE3。通过光学耦合进入入瞳单元DOE1再经由第一扩瞳单元DOE2a，最后到出瞳单元DOE3。同样可以通过光学耦合进入入瞳单元DOE1再经由第二扩瞳单元DOE2b，最后到出瞳单元DOE3。光学扩瞳装置EPE1可以提供从单元DOE1经由单元DOE2a到单元DOE3的第一路径。光学扩瞳装置EPE1可以提供从单元DOE1经由单元DOE2b到单元DOE3的第二路径。第一路径可以表示从入瞳单元DOE1到出瞳单元DOE3，并且经过第一扩瞳单元DOE2a的光路。第二路径可以指的是从入瞳单元DOE1到出瞳单元DOE3，并且经过第二扩瞳单元DOE2b的光路。
结合图3a和图3b，第一导波光B1a可以主要沿着第一方向DIR1a，从入瞳单元DOE1传播到第一扩瞳单元DOE2a。第一扩瞳单元DOE2a可以通过使第一导波光B1a发生衍射而形成第三导波光B2a。第三导波光B2a的横向尺寸可以大于输入光IN1的相应横向尺寸。第三导波光B2a也可以被称为扩展的导波光B2a。
扩展的导波光B2a可以从第一扩瞳单元DOE2a传播到出瞳单元DOE3。可以通过全内反射将扩展的导波光B2a限制在板SUB1内。
出瞳单元DOE3可以通过衍射扩展导波光B2a从而形成第一输出光OB3a。
第二导波光B1b可以主要沿着第二方向DIR1b，从入瞳单元DOE1传播到第二扩瞳单元DOE2b。第二扩瞳单元DOE2b可以通过使第二导波光B1b发生衍射而形成第四导波光B2b。第四导波光B2a的横向尺寸可以大于输入光IN1的相应横向尺寸。第四导波光B2b也可以被称为扩展的导波光B2b。
扩展的导波光B2b可以从第二扩瞳单元DOE2b传播到出瞳单元DOE3。可以通过全内反射将扩展的导波光B2b限制在板SUB1内。出瞳单元DOE3可以通过衍射扩展导波光B2b来形成第二输出光OB3b。
出瞳单元DOE3可以对第一扩瞳单元DOE2a接收的导波光B2a进行衍射，同时，出瞳单元DOE3可以对第二扩瞳单元DOE2b接收的导波光B2b进行衍射。
方向DIR1a可以表示第一导波光B1a的平均传播方向。方向DIR1a也可以 表示第一导波光B1a传播的中心轴。
方向DIR1b可以表示第二导波光B1b的平均传播方向。方向DIR1b也可以表示第二导波光B1b传播的中心轴。
第一方向DIR1a和第二方向DIR1b之间的角度γ1ab可以是60°至120°范围内。
扩展的导波光B2a可以在第三方向DIR2a上传播，该第三方向可以是大致平行于第二方向DIR1b。扩展的导波光B2b可以在第四方向DIR2b上传播，该方向可以是大致平行于第一方向DIR1a。
在一实施例中，所述光学扩瞳装置EPE1还包括光谱滤光片区域，所述光谱滤光片区域包括设置于所述第一扩瞳单元DOE2a内侧的第一光谱滤光片区域C2a和设置于所述第二扩瞳单元内侧的第二光谱滤光片区域C2b，所述第一光谱滤光片区域C2a用于防止第一颜色光通过所述第一扩瞳单元DOE2a从所述入瞳单元传输至所述出瞳单元，所述第二光谱滤光片区域C2b用于防止第二颜色光通过所述第二扩瞳单元DOE2b从所述入瞳单元DOE1传输至所述出瞳单元DOE3。
本实施例中，所述光学扩瞳装置EPE1包含第一光谱滤光区域C2a，所述第一光谱滤光区域阻止通过所述入瞳单元DOE1耦合进入，并经由第一扩瞳单元DOE2a传输到所述出瞳单元DOE3的红色光线。
其中，光学扩瞳装置EPE1包含第二光谱滤光区域C2b，所述第二光谱滤光区域阻止通过所述入瞳单元DOE1耦合进入，并经由第一扩瞳单元DOE2b传输到所述出瞳单元DOE3的蓝色光线。
在一实施例中，所述光学扩瞳装置EPE1还包括布拉格光栅区域，所述布拉格光栅区域包括分别设置于第一光谱滤光片区域C2a内侧和第二光谱滤光片区域C2b内侧的第一布拉格光栅区域BRGa和第二布拉格光栅区域BRGb，且所述第一布拉格光栅区域BRGa和第二布拉格光栅区域BRGb分别与第一光谱滤光片区域C2a和第二光谱滤光片区域C2b重叠设置。
本实施例中，所述光学扩瞳装置EPE1包含第一布拉格光栅区域BRGa所述第一布拉格光栅区域BRGa至少部分与所述第一光谱滤光片区域C2a重合，从而加强所述第一光谱滤光片区域C2a对红光的吸收；
其中，光学扩瞳装置EPE1包含第二布拉格光栅区域BRGb，所述第二布拉 格光栅区域BRGb至少部分与所述第二光谱滤光片区域C2b重合，从而加强所述第二光谱滤光片区域C2b对蓝光的吸收。
所述布拉格光栅区域，以保证光谱滤光片区域可以有效的防止不希望得到的鬼影的产生。布拉格光栅区域可以增强光谱滤光片的光吸收，从而抑制有害的鬼影光束。
导波光与所述布拉格光栅区域的相互作用可能导致导波光的多次连续反射。导波光通过布拉格光栅可以来回数次衍射，以增加光谱滤光片区域的导波光的吸收光程。
当需要显示宽图像时，由于未能满足波导板内全反射(TIR)条件，图像角落的红光可能会泄漏出波导板。当需要显示宽图像时，可能由于不满足衍射方程的解，角落点的蓝光不会通过所述入瞳单元耦合到所述第二扩瞳单元。不完全的耦合或/和未能把光限制在波导板内，会导致显示图像的亮度分布不均匀。不均匀的亮度分布所指的可以是显示图像的第一区域的最大亮度将会与显示图像的第二区域的最大亮度相差极大。所述第一光谱滤光片和所述第二光谱滤光片，可以使得亮度分布更加均匀或/和减少色彩畸变。因此，所述光学扩瞳装置可以通过衍射扩大被输入的均匀彩色图片光显示一张均匀的全彩图片。
经过第一路径传播的红光携带不完整的红色局部图像信息，其中图像一些角落点的红光丢失。所述的第一光谱滤光区域可以滤除红色光线，所滤除的红色光线可形成不完整的红光局部图像。所述第一光谱滤光片可以基本上消除所有通过第一路径的红光，以阻止不完全的局部红色图像对于显示的多色图片的干扰。
经过第二路径传播的蓝光携带不完整的蓝色局部图像信息，其中图像一些角落点的蓝光丢失。所述第二光谱滤光区域可以滤除蓝色光线，所滤除的蓝光可形成不完整的蓝光局部图像。所述第二光谱滤光片可以基本上消除所有通过第二路径的蓝光，以阻止不完全的局部蓝色图像对于显示的多色图片的干扰。
波导板SUB1可以包含第一光谱滤光片区域C2a，阻止经由第一光学扩瞳装置DOE2a，从入瞳单元DOE1传播到出瞳单元DOE3的红光的耦合。波导板SUB1可以包含一个或更多第一光谱滤光片区域(C1a,C2a)，阻止经由第一光学扩瞳装置DOE2a，从入瞳单元DOE1传播到出瞳单元DOE3的红光的耦合。
第一光谱滤光器或第一光谱滤光片区域(C1a,C2a)，可以使经由第一扩瞳单 元DOE2a，从入瞳单元DOE1传播到出瞳单元DOE3的蓝光的耦合。
红光耦合到第一路径会形成不完整的红色图片，例如其中两个角落点的红光丢失。第一光谱滤光器或第一光谱滤光片区域，可以通过消除不完整的红色图像来改进显示图片的均匀性。
波导板SUB1可以包含第二光谱滤光片区域C2b，阻止经由第二光学扩瞳装置DOE2b，从入瞳单元DOE1传播到出瞳单元DOE3的蓝光的耦合。波导板SUB1可以包含一个或更多第二光谱滤光片区域(C1b,C2b)，阻止经由第二光学扩瞳装置DOE2b，从入瞳单元DOE1传播到出瞳单元DOE3的蓝光的耦合。
第二光谱滤光器或第二光谱滤光片区域，可以使通过第二扩瞳单元DOE2b，从入瞳单元DOE1传播到出瞳单元DOE3的红光的耦合。
蓝光耦合到第二路径会形成不完整的蓝色图片，例如其中两个角落点的蓝光丢失。第二光谱滤光器或第二光谱滤光片区域，可以通过消除不完整的蓝色图像来改进显示图片的均匀性。
波导板SUB1可以包含一个或多个光学隔离单元ISO1，以防止第一扩瞳单元DOE2a和第二扩瞳单元DOE2b之间的直接光学耦合。隔离单元ISO1可以阻止所有颜色的传播。隔离单元ISO1可以阻止红光(R),绿光(G),蓝光(B)的传播。隔离单元ISO1，可以通过在板的表面上沉积(黑色)吸收材料，或/和通过将(黑色)吸收材料添加到板的对应区域材料中，或/和通过在板中形成一个或多个开口来实现。
在一具体实施例中，第一光谱滤光片区域(C1a,C2a)和第二光谱滤光片区域(C1b,C2b)也可以共同作为光学隔离结构ISO1，以防止第一扩瞳单元DOE2a和第二扩瞳单元DOE2b进行直接的光学耦合。
SX，SY和SZ是正交的方向。波导板SUB1可以与SX和SY限定的平面平行。
参照图2b，通过第一路径的导波光(B1a,B2a)初始可以包含红光(R)绿光(G)和蓝光(B)。例如，导波光B2a可以具有一个初始的光谱强度分布I2A(λ)。
第一光谱滤光器或一个或多个第一光谱滤光片区域(C1a,C2a)可以基本上防止红光到传播到出瞳单元DOE3。第一路径上的一个或更多第一光谱滤光片区域(C1a,C2a)可以具有一个光谱透射率方程TFA(λ)。光谱透射率方程TFA(λ)可以具有一个临界波长λCUT,A。一个或多个第一光谱滤光片区域(C1a,C2a)可以基 本上防止波长大于临界波长λCUT,A的光谱元素的传播。一个或多个第一光谱滤光片区域(C1a,C2a)可以允许那些波长小于临界波长λCUT,A的光谱元素传播到出瞳单元DOE3。
在通过一个或多个第一光谱滤光片区域(C1a,C2a)之后，被过滤的导波光(B1a,B2a)可以具有一个光谱强度分布I'2A(λ)。第一光谱滤光器或一个或多个第一光谱滤光片区域(C1a,C2a)可以基本上防止红光到传播到出瞳单元DOE3。一个或多个第一光谱滤光片区域(C1a,C2a)可以允许蓝光和绿光从第一扩瞳单元DOE2a传播到出瞳单元DOE3。
λR可以表示红光(R)的波长。λR可表示例如红光(R)的最大光谱强度的波长。λG可以表示绿光的波长(G)。λG可表示例如绿光(G)的最大光谱强度的波长。λB可以表示蓝光的波长(B)。λB可表示例如蓝光(B)的最大光谱强度的波长。IMAX可以表示光谱强度的最大值。
参照图2c，通过第二路径的导波光(B1b,B2b)初始可以包含红光(R)绿光(G)和蓝光(B)。例如，导波光B2b可以具有一个初始的光谱强度分布I2B(λ)。
第二光谱滤光器或一个或多个第二光谱滤光片区域(C1b,C2b)可以基本上防止蓝光和绿光到传播到出瞳单元DOE3。第二路径上的一个或更多第二光谱滤光片区域(C1b,C2b)可以具有一个光谱透射率方程TFB(λ)。光谱透射率方程TFB(λ)可以具有一个临界波长λCUT,B。一个或多个第二光谱滤光片区域(C1b,C2b)可以基本上防止波长小于临界波长λCUT,B的光谱元素的传播。一个或多个第二光谱滤光片区域(C1b,C2b)可以允许那些波长大于临界波长λCUT,B的光谱元素传播到出瞳单元DOE3。
在通过一个或多个第二光谱滤光片区域(C1b,C2b)之后，被过滤的导波光(B1b,B2b)可以具有一个光谱强度分布I'2B(λ)。第二光谱滤光器或一个或多个第二光谱滤光片区域(C1b,C2b)可以基本上防止蓝光和绿光到传播到出瞳单元DOE3。一个或多个第二光谱滤光片区域(C1b,C2b)可以允许红光从第二扩瞳单元DOE2b传播到出瞳单元DOE3。
第一光谱滤光器或一个或多个第一光谱滤光片区域(C1a,C2a)可以基本上防止红光和绿光到传播到出瞳单元DOE3。第一光谱滤光器或一个或多个第一光谱滤光片区域(C1a,C2a)可以允许红光和绿光通过第二扩瞳单元DOE2b传导到出瞳单元DOE3。
第二光谱滤光器或一个或多个第二光谱滤光片区域(C1b,C2b)可以基本上防止蓝光到传播到出瞳单元DOE3。第一光谱滤光器或一个或多个第一光谱滤光片区域(C1b,C2b)可以允许红光和绿光通过第二扩瞳单元DOE2b传导到出瞳单元DOE3。
在另一个实施例中，绿光(G)可以经由第二路径传播到出瞳单元DOE3。蓝光(B)可以经由第一路径传播到出瞳单元DOE3，红光(R)和绿光(G)可以经由第二路径传播到出瞳单元DOE3。光谱滤光片区域C2a可被布置以防止绿光和红光通过第一扩瞳单元DOE2a从入瞳单元DOE1耦合到出瞳单元DOE3。装置EPE1可被布置以通过第二扩瞳单元DOE2b将绿光从入瞳单元DOE1耦合到出瞳单元DOE3。
第一光谱滤光片区域C2a和第二光谱滤光片区域C2b可以共同防止红光(R)绿光(G)蓝光(B)在第一扩瞳单元(DOE2a)和第二扩瞳单元(DOE2b)的耦合。对于输入光B0的所有(可见)光谱元素，第一光谱滤光片区域C2a和第二光谱滤光片区域C2b的组合光谱透射率TFA(λ)·TFB(λ)基本上为零。
参照图4a，第二扩瞳单元DOE2b的光栅周期(d2b)与从第一扩瞳单元DOE2a接收的导波光B2a的波长不匹配。因此，第二扩瞳单元DOE2b会通过衍射导波光B2a来形成一个或多个不需要的附加光束B2g。附加光束B2g可被称为例如鬼影光束。当由出瞳单元DOE3耦合出波导板SUB1时，鬼影光束B2g的光会形成干扰的鬼影图像。不需要的鬼影图像可能会干扰实际虚拟图像VIMG1。
参照图4b，第一扩瞳单元DOE2a的光栅周期(d2a)与从第二扩瞳单元DOE2b接收的导波光B2b的波长不匹配。因此，第一扩瞳单元DOE2a会通过衍射导波光B2b来形成一个或多个不需要的附加光束B2e。附加光束B2e可被称为例如鬼影光束。当由出瞳单元DOE3耦合出波导板SUB1时，鬼影光束B2e的光会形成干扰的鬼影图像。
参照回图2a，光学扩瞳装置EPE1可包括第一布拉格光栅区域BRGa，以增强第一光谱滤光片区域C2a中的光吸收，从而防止导波光B2b与第一扩瞳单元DOE2a的耦合。第一布拉格光栅区域BRGa可以增强第一光谱滤光片区域C2a中的光吸收，从而防止形成一个或多个鬼影光束B2e。
光学扩瞳装置EPE1可包括第二布拉格光栅区域BRGb，以增强第二光谱滤 光片区域C2b中的光吸收，从而防止导波光B2a与第二扩瞳单元DOE2b的耦合。第二布拉格光栅区域BRGb可以增强第二光谱滤光片区域C2b中的光吸收，从而防止形成一个或多个鬼影光束B2g。
在一实施例中，所述波导板至少包含一个覆层、至少一个保护层以及至少一个机械支撑层，所述光谱滤光片区域与所述布拉格光栅区域位于所述波导板的同一侧或者不同侧。
本实施例中，波导板可以具有厚度tSUB1。波导板包含平面波导核心部分。在一个实施例中，波导板SUB1可以选择性的包含一个或多个覆层，一个或多个保护层和/或一个或多个机械支撑层。厚度tSUB1可以指波导板SUB1的平面波导核心部分的厚度。
参照图5a，布拉格光栅区域BRGb和光谱滤光片区域C2b可以位于波导板SUB1的同一侧。例如，布拉格光栅区域BRGb和光谱滤光片区域C2b可以位于第一主表面SRF1。例如，布拉格光栅区域BRGb和光谱滤光片区域C2b可以位于第二主表面SRF2。
光谱滤光片区域C2b和布拉格光栅区域BRGb一起可以形成来自导波光B2a的透射光B2aT和反射光B2aR。布拉格光栅可以通过布拉格衍射现象将导波光B2a反射回去。布拉格光栅可以增强光谱滤光片区域的光吸收。光谱滤波区域C2b和布拉格光栅区域BRGb可被设置以抑制透射光B2aT的强度。光谱滤波区域C2b和布拉格光栅区域BRGb可一起被布置以使得透射光B2aT的强度很低或为零。
标志dBRGb表示布拉格光栅区域BRGb的布拉格光栅的光栅周期。导波光B2a的单个光线可在表面SRF1的第一反射点和表面SRF1的相邻的第二反射点处经历全内反射(TIR)。LTIR表示所述反射点之间的距离。距离LTIR可以在板SUB1的厚度tSUB1的1.5到4.0倍的范围内，这取决于对应于所讨论的导波光的图像点的位置和颜色。距离LTIR的平均值基本上等于2.6。
参照图5b，布拉格光栅区域BRGb和光谱滤光片区域C2b可以位于波导板SUB1的不同侧。例如，布拉格光栅区域BRGb可以在第一主表面SRF1上，并且光谱滤光片区域C2b可以在第二主表面SRF2上。例如，布拉格光栅区域BRGb可以在第二主表面SRF2上，并且光谱滤波区域C2b可以在第一主表面SRF1上。
在一实施例中，所述第一布拉格光栅区域与所述第一光谱滤光片区域之间 的第一重叠区域面积为所述第一布拉格光栅区域面积的50％～100％，所述第二布拉格光栅区域与所述第二光谱滤光片区域之间的第二重叠区域面积为所述第二布拉格光栅区域面积的50％～100％。
本实施例中，参考图5c，布拉格光栅BRGa可以导致导波光B2a,B2aR多次连续的反射。导波光B2a,B2aT可以从布拉格光栅多次来回反射，以增加导波光B2a,B2aR在光谱滤光片区域C2b的吸收光程。
导波光可以沿着折叠光路传播，其中导波光可以多次遇到吸收滤光片区域。导波光束B2a的一些部分可以被反射回第一扩展元件DOE2a。
布拉格光栅区域BRGb可分别引起导波光B2b、B2bR的多次连续反射。
参考图5d，当从垂直于波导板SUB1的方向(SZ)上观看时，第一布拉格光栅区域BRGa可部分或完全与第一光谱滤光片区域C2a重叠。第一光谱滤光片区域C2a的面积可以大于、等于或小于第一布拉格光栅区域BRGa的面积。第一光谱滤光片区域C2a的面积可以在第一布拉格光栅区域BRGa的面积的50％到200％的范围内。第一布拉格光栅区域BRGa的位置可以与第一光谱滤光片区域C2a的位置重合。或者，第一布拉格光栅区域BRGa可以相对于第一光谱滤光片区域C2a被移位。COMa可以表示第一布拉格光栅区域BRGa和第一光谱滤光片区域C2a的公共重叠区域。公共重叠区COMa的面积可以在第一布拉格光栅区BRGa的面积的50％到100％的范围内。
COMb表示第二布拉格光栅区域BRGb和第二光谱滤光片区域C2b的公共重叠区域。当从垂直于板SUB1的方向(SZ)上观看时，第二布拉格光栅区域BRGb可部分或完全与第二光谱滤光片区域C2b重叠。公共重叠区域COMb的面积可以在第二布拉格光栅区域BRGb的面积的50％到100％的范围内。
出瞳单元DOE3可以具有第一光栅矢量VDOE3a，用于将导波光B2a耦合出板SUB1。出瞳单元DOE3可以具有第二光栅矢量VDOE3b，用于将导波光B2b耦合出板SUB1。
在一实施例中，所述第一布拉格光栅区域在水平方向的横截面宽度为所述波导板的导波层厚度3～5倍，所述第二布拉格光栅区域在垂直方向的横截面宽度为所述波导板的导波层厚度3～5倍。
参考图6a，第一布拉格光栅区域BRGa可以从垂线定义垂直线段LIN12，该垂线垂直于出瞳单元DOE3的光栅矢量V3a。线段LIN12的长度可被称为第 一布拉格光栅区域BRGa的水平横截面宽度h12。水平横截面宽度h12可以大于波导板SUB1的厚度tSUB1的3～5倍，例如4倍，以确保第一光谱滤光片区域C2a对光B2b的有效吸收。水平线段LIN12可以垂直于出瞳单元DOE3的第一光栅矢量V3a。
第二布拉格光栅区域BRGb可以从垂线定义垂直线段LIN34，该垂线垂直于出瞳单元DOE3的光栅矢量V3b。线段LIN34的长度可被称为第二布拉格光栅区域BRGb的垂直横截面高度h34。垂直横截面高度h34可以大于波导板SUB1的厚度tSUB1的3～5倍，例如4倍，以确保在第二光谱滤光片区域C2a中对光B2a的有效吸收。垂直线段LIN34可以垂直于出瞳单元DOE3的第二光栅矢量V3b。
第二光谱滤光片区域C2a和布拉格光栅区域BRGa可以具有公共重叠区域COMa(图5d)。公共重叠区COMa可以以与出瞳单元DOE3的衍射特征(F3a)平行的线定义水平线段(LIN12)。水平线段(LIN12)的长度(w12)可以大于波导板SUB1的波导层厚度(tSUB1)的4倍。
光谱滤光片区域C2b和布拉格光栅区域BRGb可以具有共同的重叠区域COMb(图5d)。公共重叠区域COMb可从与出瞳单元DOE3的衍射特征(F3b)平行的线定义垂直线段(LIN34)。垂直线段(LIN34)的长度(h34)可以大于波导板SUB1的导波层厚度(tSUB1)的4倍。
POS1表示第一横向位置，其中导波光B2a撞击第二布拉格光栅区域BRGb。
POS2表示第二横向位置，其中导波光B2a撞击出瞳单元DOE3。
参考图6b举例说明了导波光B2a在第一横向位置POS1处的传播。第一扩瞳单元DOE2a形成导波光B2a。导波光B2a的一部分可以向第二扩瞳单元DOE2b传播。第二光谱滤光片区域C2b和第二布拉格光栅区域BRGb的组合可以防止导波光B2a传播到第二扩瞳单元DOE2b，从而防止形成不需要的鬼影光束B2g。导波光B2a可以具有蓝色，并且第二光谱滤光片区域C2b可以吸收蓝光。
参考图6c举例说明了在第二横向位置POS2处导波光B2a的传播。第一扩瞳单元DOE2a形成导波光B2a，该导波光B2a可通过第一光谱滤光片区域C2a和第一布拉格光栅区域BRGa的组合传播到出瞳单元DOE3。第一光谱滤光片区域C2a可以防止红光的传播，并且第一光谱滤光片区域C2a可以允许蓝光B2a 的传播。第一光谱滤光片区域C2a可允许导波光B2a从第一扩瞳单元DOE2a耦合到出瞳单元DOE3，从而形成虚拟图像VIMG1的蓝色。装置EPE1可以包括光谱滤光片区域C2a，该光谱滤光片区域C2a位于第一扩瞳单元DOE2a和出瞳单元DOE3之间，以防止红光从入瞳单元DOE1通过第一扩瞳单元DOE2a耦合到出瞳单元DOE3。
装置EPE1可包括光谱滤光片区域C2b，位于第二扩瞳单元DOE2b和出瞳单元DOE3之间，以防止蓝光从入瞳单元DOE1通过第二扩瞳单元DOE2b耦合到出瞳单元DOE3。
第一光谱滤光片区域C2a和第二光谱滤光片区域C2b可一起防止第一扩瞳单元DOE2a和第二扩瞳单元DOE2b之间红光(R)、绿光(G)和蓝光(B)的耦合。
设备EPE1还可以包含一个或多个光学隔离元件ISO1，以防止第一扩瞳单元DOE2a和第二扩瞳单元DOE2b之间的直接光学耦合。
参考图7a，第一扩瞳单元DOE2a可以被布置成将导波光B2a分布到出瞳单元DOE3的第一出瞳区域REG3a。第一出瞳区域REG3a可将导波光B2a衍射出板SUB1。第二扩瞳单元DOE2b可被布置成将导波光B2b分布到出瞳单元DOE3的第二出瞳区域REG3b。第二出瞳区域REG3b可将导波光B2b衍射出板SUB1。
第一出瞳区域REG3a可以与第二出瞳区域REG3b重叠。第一出瞳区域REG3a和第二出瞳区域REG3b的公共重叠区域COM1可以将导波光B2a和导波光B2b衍射出板SUB1。公共重叠区域COM1的面积可以大于出瞳单元DOE3的单侧面积的50％，最好大于70％。
入瞳单元DOE1可被布置以衍射输入光IN1，使得第一导波光B1a包含输入图像IMG0的中心点P0的光，并且使得第二导波光B1b包括中心点P0的光。出瞳单元DOE3可被布置成以衍射从第一扩瞳单元DOE2a接收的第三导波光B2a，使得第一输出光OB3a包括中心点P0的光。出瞳单元DOE3可被布置以衍射从第二扩瞳单元DOE2b接收的第四导波光B2b，使得第二输出光OB3b包含中心点P0的光。第一输出光OB3a中的中心点P0的光可以轴向(k3P0,R)传播，第二输出光OB3b中的中心点P0的光可以相同轴向(k3P0,R)传播。轴向(k3P0,R)可以与光学引擎ENG1的光轴(AX0)平行。
第一导波光B1a中的中心点P0的光可以在第一方向(k1aP0)上传播，其 中第二导波光B1b中的中心点P0的光可以在第二方向(k1bP0)上传播，其中第一方向(k1aP0)和第二方向(k1bP0)之间的角度(γAB)可以在60°至120°的范围内。
出瞳单元DOE3的第一区域REG3a可被布置以出耦合从第一扩瞳单元DOE2a接收的中心点(P0)的光，出瞳单元DOE3的第二区域REG3b可被布置以出耦合从第二扩瞳单元DOE2b接收的中心点(P0)的光。第一区域REG3a可以和第二区域REG3a重叠，使得第一区域REG3a和第二区域REG3b的公共重叠区域COM1的面积大于出瞳单元DOE3的单侧面积的50％。
参考回图3a和6c，光学扩瞳装置EPE1可以通过衍射和引导从光学引擎ENG1获得的输入光IN1来形成输出光OUT1。显示装置500可以包括光引擎ENG1和光学扩瞳装置EPE1。
输入光IN1可以包含在不同方向上传播的多个光束。输入光IN1的每个光束可以对应于输入图像IMG0的不同点。输出光OUT1可以包含在不同方向上传播的多个光束。输出光OUT1的每个光束可以对应于所显示的虚像VIMG1的不同点。扩瞳单元EPE1可以由输入光IN1形成输出光OUT1，使得输出光OUT1的光束的方向和强度对应于输入图像IMG0的点。
输入光IN1的光束可以对应于显示图像的单个图像点(P0)。光学扩瞳装置EPE1可以从输入光IN1的光束形成输出光束，使得输出光束的方向(k3,P0,R)平行于相应输入光IN1的光束的方向(k3,P0,R)。
在一实施例中，所述入瞳单元设置有用于将第一导波光衍射到所述第一扩瞳单元的第一衍射特征，以及用于将第二导波光衍射到第二扩瞳单元的第二衍射特征，所述第一衍射特征和第二衍射特征均为凸起或者凹槽。
本实施例中，所述入瞳单元可以包含第一衍射特征，以将光衍射到所述第一扩瞳单元。所述入瞳单元可以包含第二衍射特征，以将光衍射到所述第二扩瞳单元。所述第一衍射特征可以具有第一光栅周期，并且所述第二衍射特征可以具有不同的第二光栅周期。可以选择第一光栅周期以确保角落点的蓝色导波光被限制在波导板内。可以选择第二光栅周期以确保角落点的红色导波光被限制在波导板内。所述第一衍射特征可以具有第一方向，所述第二衍射特征可以具有不同的第二方向。
两条路径可以一起至少部分地补偿所显示图像的角落点的颜色偏差。两条 路径可以减少或避免宽的彩色显示图像的角落点的颜色错误。两条路径可以改善宽的彩色显示图像的颜色均匀性。所述光谱滤光区域可以提高全彩图像的色彩均匀性。
所述出瞳单元可以通过衍射沿着第一路径传播的第三导波光，来形成第一输出光。被衍射的第三导波光来自第一扩瞳单元。所述出瞳单元可以通过衍射沿着第二路径传播的第四导波光来形成第二输出光。被衍射的第四导波光来自第二扩瞳单元。第一输出光可以在空间上与第二输出光重叠。所述出瞳单元通过将第一输出光与第二输出光组合，以形成组合的输出光。
进一步的，所述出瞳单元可以包含第一衍射特征，以衍射从第一扩瞳单元接收的导波光。所述出瞳单元可以包含第二衍射特征，以衍射从第二扩瞳单元接收的导波光。所述第一衍射特征可以具有第一光栅周期，并且所述第二衍射特征可以具有不同的第二光栅周期。可以选择第一光栅周期以确保角落点的蓝色导波光被限制在波导板内。可以选择第二光栅周期以确保角落点的红色导波光被限制在波导板内。所述第一衍射特征可以具有第一方向，并且所述第二衍射特征可以具有不同的第二方向。第一衍射特征对于从第二扩瞳单元接收的光的耦合出瞳效率，可能非常低或可忽略。第二衍射特征对于从第一扩瞳单元接收的光的耦合出瞳效率，可能非常低或可忽略。
所述布拉格光栅区域可以增强光所述谱滤光片区域对光的吸收。在一个实施例中，可以在形成光学扩瞳装置的一个或多个其他光栅区域的同时形成布拉格光栅区域。布拉格光栅区域的运用对光学扩瞳装置的制造成本的影响很小或可以忽略。
光学扩瞳装置EPE1可以在两个方向上扩展光束，在方向SX和在方向SY上。输出光OUT1的宽度(沿SX方向)可以大于输入光IN1的宽度，并且输出光OUT1的高度(沿SY方向)可以大于输入光IN1的高度。
光学扩瞳装置EPE1可以被设置为扩展虚拟显示装置500的视瞳，从而便于眼睛EYE1相对于虚拟显示装置500的定位。在输出光OUT1入射在观看者的眼睛EYE1上的情况下，观看者可以看到显示的虚拟图像VIMG1。输出光OUT1可以包含一个或多个输出光束，其中每个输出光束可以对应于所显示的虚像VIMG1的不同图像点(P0'，P1')。光引擎ENG1可以包含用于显示主图像IMG0的微型显示器DISP1。光引擎ENG1和光学扩瞳装置EPE1可以设置为把主图像 IMG0转换成多个输入光束(例如，B0P0,R，B0P1,R，B0P2,R，B0P3,R，B0P4,R，...，B0P0,B，B0P1,B，B0P2,B，B0P3,B，B0P4,B，...)，并通过扩大输入光束形成输出光OUT1。例如，符号B0P2,R可以表示输入光束，其对应于图像点P2并且具有红色(R)。例如，符号B0P2,B可以表示输入光束，其对应于图像点P2并且具有蓝色(B)。输入光束可以一起构成输入光IN1。输入光IN1可以包含多个输入光束(例如，B0P0,R,B0P1,R,B0P2,R,B0P3,R,B0P4,R,...B0P0,B,B0P1,B,B0P2,B,B0P3,B,B0P4,B,...)。
输出光OUT1可以包含多个输出光束，每个输出光束可以形成虚像VIMG1的不同像点(P0'，P1')。主图像IMG0可以表示为，例如图形和/或文字。主图像IMG0可以表示为，例如视频。光引擎ENG1和光学扩瞳装置EPE1可以被设置为显示虚拟图像VIMG1，使得虚拟图像VIMG1的每个图像点(P0'，P1')对应于主图像IMG0上的不同图像点。
波导板SUB1可以具有第一主表面SRF1和第二主表面SRF2。表面SRF1，SRF2可以与方向SX和SY限定的平面基本平行。
光谱滤光器或光谱滤光区域(C1a,C2a,C1b,C2a)可以通过将光谱吸收的材料沉积在波导板SUB1上实现。光谱滤光器或光谱滤光区域(C1a,C2a,C1b,C2a)可以通过把局部的波导板SUB1的材料转化为光谱吸收的材料实现。例如，光谱滤光器或光谱滤光区域(C1a,C2a,C1b,C2b)可以通过用一种或多种掺杂剂局部掺杂波导板SUB1而形成。
参照图7b，每个单元DOE1，DOE2a，DOE2b，DOE3可以包含一个或多个衍射光栅，以如上所述地衍射光。例如，单元DOE1可以包含一个或多个光栅G1a，G1b。例如，单元DOE2a可以包含光栅G2a。例如，单元DOE2b可以包含光栅G2b。例如，单元DOE3可以包含一个或多个光栅G3a，G3b。
衍射光栅的光栅周期(d)和衍射光栅的衍射特征的取向(β)可以由所述衍射光栅的光栅矢量V确定。衍射光栅包含可以用作衍射线的多个衍射特征(F)。衍射特征可以是，例如微小的脊或凹槽。衍射特征也可以是，例如微观的凸起(或凹陷)，其中相邻的凸起(或凹陷)可以作为衍射线。光栅矢量V可以定义为具有垂直于衍射光栅的衍射线的方向和由2π/d给出的幅度的矢量，其中d是光栅周期。光栅周期等同于光栅周期长度。光栅周期可以是光栅的连续衍射特征之间的长度。光栅周期可以等于单位长度除以位于所述单位长度内的衍射 特征的数量。入瞳单元DOE1的光栅周期d1a,d1b可以在330nm到450nm的范围内。光栅周期d的最优值可以取决于板SUB1的折射率和被d衍射光的波长λ。例如，入瞳单元DOE1的第一光栅可针对蓝光波长进行优化，入瞳单元DOE1的第二光栅可针对红光波长进行优化。入瞳单元DOE1的第一光栅周期d1a可以不同于入瞳单元DOE1的第二光栅周期d1b。
入瞳单元DOE1可以具有光栅矢量V1a，V1b。第一扩瞳单元DOE2a可以具有光栅矢量V2a。第二扩瞳单元DOE2b可以具有光栅矢量V2b。出瞳单元DOE3可以具有光栅矢量V3a，V3b。
光栅矢量V1a具有方向β1a和大小2π/d1a。光栅矢量V1b具有方向β1b和大小2π/d1b。光栅矢量V2a具有方向β2a和幅度2π/d2a。光栅矢量V2b具有方向β2b和大小2π/d2b。光栅矢量V3a具有方向β3a和幅值2π/d3b。光栅矢量V3b具有方向β3b和幅度2π/d3b。光栅矢量的方向(β)可以被定义为光栅矢量和参考方向(例如，方向SX)之间的夹角。
可以选择光学单元DOE1，DOE2a，DOE3的光栅周期(d)和衍射光栅的方向(β)，使得在第一输出光OB3a中的中心点P0的光的传播方向(k3P0,R)平行于输入光IN1中的中心点P0的光的传播方向(k0P0,R)。
可以选择光学单元DOE1，DOE2b，DOE3的光栅周期(d)和衍射光栅的方向(β)，使得第二输出光OB3b的中心点P0的光的传播方向(k3P0,R)与输入光IN1中的中心点P0的光的传播方向(k0P0,R)平行。
可以选择光学单元DOE1，DOE2a，DOE2b，DOE3的衍射周期(d)和衍射光栅的方向(β)，使得在组合输出光OUT1的中心点P0的光的传播方向(k3P0,R)与输入光IN1中的中心点P0的光的传播方向(k0P0,R)平行。
入瞳单元DOE1的光栅矢量V1a，V1b的方向之间的夹角可以在60°至120°的范围内。
单元DOE1的第一光栅周期d1a可以不同于单元DOE1的第二光栅周期d1b，以针对第一颜色优化第一路径，并且针对第二不同颜色优化第二路径。
入瞳单元DOE1的第一光栅的第一光栅周期长度d1a可以不同于入瞳单元DOE1的第二光栅的第二光栅周期长度d1b，使得入瞳单元DOE1的第一光栅可以针对蓝光的波长(λB)进行优化，并且入瞳单元DOE1的第二光栅可针对红光的波长(λR)进行优化。
单元DOE3的第一光栅周期d3a可以不同于单元DOE3的第二光栅周期d3b，以针对第一颜色优化第一路径，并且针对第二不同颜色优化第二路径。
单元DOE1的第一光栅周期d1a可以不同于单元DOE1的第二光栅周期d1b，例如，用于优化蓝色的第一条路径，以及用于红色的第二条路径。
单元DOE3的第一光栅周期d3a可以不同于单元DOE3的第二光栅周期d3b，例如，用于优化蓝色的第一条路径，以及用于红色的第二条路径。
光栅矢量的光栅周期(d)和方向(β)可以满足，对于预定整数m1a，m2a，m3a时，矢量和(m1aV1a+m2aV2a+m3aV3a)为零的条件。V1a表示单元DOE1的光栅矢量。V2a表示单元DOE2a的光栅矢量。V3a表示单元DOE3的光栅矢量。这些预定整数的值通常为+1或-1。整数m1a的值可以是+1或-1。整数m2a的值可以是+1或-1。整数m3a的值可以是+1或-1。
光栅矢量的光栅周期(d)和方向(β)可以满足，对于预定整数m1b，m2b，m3b时，矢量和(m1bV1b+m2bV2b+m3bV3b)为零的条件。V1b表示单元DOE1的光栅矢量。V2b表示单元DOE2b的光栅矢量。V3b表示单元DOE3的光栅矢量。这些预定整数的值通常为+1或-1。整数m1b的值可以是+1或-1。整数m2b的值可以是+1或-1。整数m3b的值可以是+1或-1。
第一单元DOE1可以具有第一光栅矢量V1a以形成沿方向DIR1a的第一导波光B1a，以及第二光栅矢量V1b以形成沿方向DIR1b的第二导波光B1b。第一单元DOE1可以具有第一衍射特征F1a以提供第一光栅，该第一光栅具有光栅周期d1a和方向β1a(相对于参考方向SX)。第一单元DOE1可以具有第二衍射特征F1b，以提供第二光栅，该第二光栅具有光栅周期d1b和方向β1b(相对于参考方向SX)。第一单元DOE1可以通过例如交叉光栅或两个线性光栅来实现。第一单元DOE1可以是，例如第一单元DOE1的第一区域包含第一特征F1a，同时第一单元DOE1的第二区域包含第二特征F1b。
具有衍射特征F1a的第一线性光栅可以被设置在波导板SUB1的第一主表面(例如在输入侧表面SRF1上)，并且具有衍射特征F1b的第二线性光栅可以被设置在波导板SUB1的第二主表面(例如在输出侧表面SRF2上)。所述衍射特征可以是，例如微小的脊或微小的凸起。
扩瞳单元DOE2a可以具有光栅矢量V2a，通过使第一导波光B1a衍射来形成第三导波光B2a。扩瞳单元DOE2a可以具有衍射特征F2a，以提供光栅G2a， 该光栅G2a具有光栅周期d2a和方向β2a(相对于参考方向SX)。
扩瞳单元DOE2b可以具有光栅矢量V2b，通过使第二导波光B1b衍射来形成第四导波光B2b。扩瞳单元DOE2b可以具有衍射特征F2b，以提供光栅G2b，该光栅G2b具有光栅周期d2b和方向β2b(相对于参考方向SX)。
第一扩瞳单元DOE2a可以具有用于形成导波光B2a的光栅周期d2a，第二扩瞳单元DOE2b可以具有用于形成导波光B2b的光栅周期d2b，其中光栅周期d2a可以不同于光栅周期d2b。
出瞳单元DOE3可以具有第一光栅矢量V3a，以将扩展的光B2a耦合出波导板SUB1。出瞳单元DOE3可以具有第二光栅矢量V3b，以将扩展的光B2b耦合出波导板SUB1。出瞳单元DOE3可以具有衍射特征F3a，以提供具有光栅周期d3a和方向β3a(相对于参考方向SX)的光栅G3a。出瞳单元DOE3可以具有衍射特征F3b，以提供具有光栅周期d3b和方向β3b(相对于参考方向SX)的光栅G3b。出瞳单元DOE3可以通过交叉光栅或两个线性光栅来实现。具有衍射特征F3a的第一线性光栅G3a可以在波导板SUB1的第一主表面(例如，SRF1)上实现，并且具有衍射特征F3b的第二线性光栅G3b可以在波导板SUB1的第二主表面(例如，SRF2)上实现。
入瞳单元DOE1可以具有宽度w1和高度h1。第一扩瞳单元DOE2a可以具有宽度w2a和高度h2a。第二扩瞳单元DOE2b可以具有宽度w2b和高度h2b。出瞳单元DOE3可以具有宽度w3和高度h3。
宽度可以表示方向SX上的尺寸，高度可以表示方向SY上的尺寸。出瞳单元DOE3可以是，例如大体上为矩形。出瞳单元DOE3的边沿可以沿着方向SX和SY。
扩瞳单元DOE2a的宽度w2a可以大幅大于入瞳单元DOE1的宽度w1。扩展的导波光束B2a的宽度可以大幅大于入瞳单元DOE1的宽度w1。
波导板SUB1可以包含或基本上由透明固体材料组成。波导板SUB1可包含例如玻璃，聚碳酸酯或聚甲基丙烯酸甲酯(PMMA)。衍射光学单元DOE1，DOE2a，DOE2b，DOE3可以通过例如模制，压印和/或蚀刻形成。单元DOE1，DOE2a，DOE2b，DOE3可以通过例如一个或多个表面衍射光栅或通过一个或多个体积衍射光栅实现。
衍射效率的空间分布可任意的被调整，例如通过选择微观衍射特征F的局 部高度。因此，可以选择出瞳单元DOE3的微观衍射特征F的高度，以进一步使输出光OUT1的强度分布变得均匀。
在一实施例中，所述入瞳单元包括分别用于形成所述第一导波光和第二导波光的第一入瞳光栅和第二入瞳光栅，所述第一入瞳光栅和第二入瞳光栅分别具有第一入瞳光栅周期和第二入瞳光栅周期，且所述第一入瞳光栅周期和第二入瞳光栅周期不同；
所述出瞳单元包括分别用于形成所述第一输出光和第二输出光的第一出瞳光栅和第二出瞳光栅，所述第一出瞳光栅和第二出瞳光栅分别具有第一出瞳光栅周期和第二出瞳光栅周期，且所述第一出瞳光栅周期和第二出瞳光栅周期不同。
进一步的，所述第一布拉格光栅区域和第二布拉格光栅区域的光栅周期分别为所述第一出瞳光栅周期和第二出瞳光栅周期的一半。
参照图7c，第一布拉格光栅区域BRGa具有光栅矢量VBRGa。第一布拉格光栅区域BRGa的光栅矢量VBRGa可以与出瞳单元DOE3的光栅矢量VDOE3a平行。光栅矢量VBRGa的方向由角度βBRGa设定。第一布拉格光栅区域BRGa具有光栅周期dBRGa。第一布拉格光栅区域BRGa的光栅周期dBRGa可以等于出瞳单元DOE3的光栅周期dDOE3a的一半。
第二布拉格光栅区域BRGb具有光栅矢量VBRGb。第二布拉格光栅区域BRGb的光栅矢量VBRGb可以与出瞳单元DOE3的光栅矢量VDOE3b平行。光栅矢量VBRGb的方向由的方向由角度βBRGa设定。第二布拉格光栅区域BRGb具有光栅周期dBRGb。第二布拉格光栅区域BRGb的光栅周期dBRGb可以等于出瞳单元DOE3的光栅周期dDOE3b的一半。
第一布拉格光栅区域BRGa可以具有衍射特征FBRGa。第二布拉格光栅区域BRGa可以具有衍射特性FBRGb。衍射特征FBRGa、FBRGb的横截面形状可以是二元的、梯形的、正弦的或倾斜的。FBRGa、FBRGb的衍射特性也可以是体光栅的特性。
布拉格光栅区域BRGa、BRGb可以通过压印或模压形成。光谱滤光片区域C2a、C2b的光学吸收材料层可在形成衍射特征FBRGa、FBRGb之前或之后添加。例如，可以通过在板SUB1上施加一薄层吸收材料来形成滤波区域C2a，其中布拉格光栅区域BRGa可以随后通过压印吸收材料层和波导板SUB1的表面 来形成。例如，衍射特征FBRGa可以形成在波导板SUB1的表面上，并且衍射特征FBRGa可以随后被滤光片区域C2a的光学吸收材料层覆盖。
图8a到8c演示了把光耦入波导板的输入角度。为使其成功耦合，导波光的波矢应该驻留在第一边界BND1和第二边界BND2之间的区域ZONE1中。区域ZONE1和第一边界BND1和第二边界BND2如图例9a到10g所示。
图8a通过截面图侧视图说明，通过将输入光束耦合到波导中形成第一导波光，其中第一导波光的倾斜角
Figure PCTCN2022072565-appb-000001
接近全内反射的临界角
Figure PCTCN2022072565-appb-000002
图8a的情况可以对应于区域ZONE1的第一边界BND1附近的操作。
图8b通过截面图侧视图说明，通过将输入光束耦合到波导中形成第一导波光，其中第一导波光的倾斜角度
Figure PCTCN2022072565-appb-000003
接近90度。图8b的情况可以对应于区域ZONE1的第二边界BND2附近的操作。
图8c中的曲线CRV1给出了第一导波光B1a的波矢k1的倾斜角φk1与输入光B0的波矢k0的输入角度φk0之间的函数关系。倾斜角φk1可以表示波矢和方向SZ与SY限定的参考平面REF1之间的夹角。通过使用衍射方程式，可以通过输入角
Figure PCTCN2022072565-appb-000004
输入单元DOE1的光栅周期以及波导板SUB1的折射率计算出倾斜角
Figure PCTCN2022072565-appb-000005
第一角度限制φBND1可以对应于第一导波光的倾斜角度φk1等于全内反射的临界角度
Figure PCTCN2022072565-appb-000006
的情况。第二角度限制φBND2可以对应于第一导波光的倾斜角度φk1等于90度的情况。
图9a通过示例给出了蓝光的波矢图，该蓝光沿着第一路径在波导板SUB1内传播。第一路径可以是顺时针路径。输入光IN1的波矢可以存在于以初始波矢kx和ky定义的波矢空间的一个区域BOX0中。区域BOX0的每个角落都可以代表一个输入图像IMG0的角落点的光的波矢(图9d)。
第一导波光B1a的波矢可以在区域BOX1a内。
第三导波光B2a的波矢可以在区域BOX2a内。
第一输出光OB3a的波矢可以在区域BOX3内。
入瞳单元DOE1可以通过衍射输入光IN1，来形成第一导波光B1a。可以通过将入瞳单元DOE1的光栅矢量m1aV1a与输入光IN1的波矢相加来表示衍射。可以通过将光栅矢量m1aV1a与输入光IN1的波矢相加来确定第一导波光B1a的波矢。第三导波光B2a的波矢可以通过将光栅矢量m2aV2a与第一导波光B1a的波矢相加来确定。可以通过将光栅向量m3aV3a加到第二导波光B2a的波矢 上来确定出射光OB3a的波矢。
BND1表示用于满足波导板SUB1中的全内反射(TIR)标准的第一边界。BND2表示波导板SUB1中的最大波矢的第二边界。最大波矢可以由波导板的折射率确定。仅当所述光的波矢在第一边界BND1与第二边界BND2之间的区域ZONE1中时，光才可以在板SUB1中被波导。如果光的波矢在区域ZONE1之外，则光可能会泄漏出波导板或根本不传播。
可以选择入瞳单元DOE1的光栅周期d1a，使得例如，第一蓝色导波光B1a的所有波矢都在由边界BND1，BND2限定的区域ZONE1内。
kx表示波矢空间中的方向，其中方向kx与实际空间的方向SX平行。ky表示波矢空间中的方向，其中ky方向与实际空间的SY方向平行。符号kz(图中未示出)表示波矢空间中的方向，其中方向kz与实际空间的方向SZ平行。波矢k可以具有在方向kx，ky和/或kz上的分量。
图9b和9c用例子说明了，在波导板SUB1内沿第一条路径传播的红光波矢的矢量图。
如果已选择入瞳单元DOE1的光栅周期d1a，以使第一蓝色导波光B1a的所有波矢都在区域ZONE1内，那么某些角落点的红光的波矢可能会位于区域ZONE1外。换句话说，波导板SUB1不能限制或传导输入图像IMG0的某些角落点的红光。
落在区域BOX1a的子区域FAIL1内的波矢，对应的是输入单元DOE1不能通过衍射输入光来形成导波光的情况。换句话说，对于存在于区域BOX1a的子区域FAIL1内的波矢，衍射方程式没有正确的实际解。因此，导波光的波矢在区域ZONE1之外的情况下，对于某些图像点，不可能将红光耦合到波导板中。
导波光的波矢在区域ZONE1之外的情况，对于某些(其他)图像点，红光的泄漏可能会限制所显示虚像VIMG1的角度宽度。
因此，区域ZONE1的边界BND1，BND2可以限制所显示的虚像VIMG1的角宽度
Figure PCTCN2022072565-appb-000007
在区域ZONE1之外形成波矢可能意味着光从波导板泄漏或光耦合失败。
红光从波导板泄漏或光耦合失败可能导致生成不完整的红色图片。光学扩瞳装置EPE1的第一路径可以包含一个或更多光谱滤光片区域C1a,C2a，以防止不完整的红色图片对最终显示图片(VIMG1)的干扰。
光学扩瞳装置EPE1可以包括光谱滤光片区域C2a，以为导波光B2a提供抑制区域ZONE2。光谱滤光片区域C2a可以被布置以消除导波光B2a的红色分量。
图9d和9e通过示例示给出了在波矢空间中的图像点(P0，P1，P2，P3，P4)的蓝光的波矢。
图10a通过示例给出了红光的波矢图，该红光沿着第二路径在波导板SUB1内传播。第二路径可以是例如，逆时针路径。
可以选择耦合单元DOE1的光栅周期d1b，使得例如，第二红色导波光B1b的所有波矢都在由边界BND1，BND2限定的区域ZONE1内。
图10b到10d通过对比示例给出了蓝光的波矢图，该蓝光沿着第二路径在波导板SUB1内传播，在此情况下无法避免蓝光在第二路径上的传播。图10b到10d演示了不完整的蓝色图像的形成。
现在，如果已经选择了入瞳单元DOE1的光栅周期d1b，使得第二红色导波光B1b的所有波矢都在区域ZONE1内，那么某些角落点的蓝光的波矢可能会位于区域ZONE1外。换句话说，波导板SUB1不能限制输入图像IMG0的某些角落点的蓝光。蓝光的泄漏可能会限制显示的虚拟图像VIMG1的角度宽度。落在区域BOX2b的子区域LEAK1中的波矢，代表不被全内反射限制在波导板内的光。
图10e通过图片例子说明抑制区域ZONE3用于从第二路径消除不完整的蓝色图像。
蓝光从波导板泄漏或光耦合失败可能导致生成不完整的蓝色图片。光学扩瞳装置EPE1的第一路径可以包含一个或更多光谱滤光片区域C1a,C2a，以防止不完整的蓝色图片对最终显示图片(VIMG1)的干扰。
图10f和10g通过示例给出了红光的波矢图，该红光沿着第二路径在波导板SUB1内传播。第二路径可以是例如，逆时针路径。输入光IN1的波矢可以存在于波矢空间的一个区域中BOX0。区域BOX0的各个角落都可以分别代表一个显示图片IMG0角落点的波矢。
第二导波光B1b的波矢可以在区域BOX1b内。
第四导波光B2b的波矢可以在区域BOX2b内。
第一输出光OB3b的波矢可以在区域BOX3内。
光学扩瞳装置EPE1可以被设置为提供第一路径和第二路径。第一路径可以提供蓝色的显示图像VIMG1的全宽度
Figure PCTCN2022072565-appb-000008
第二路径可以提供红色的显示图像VIMG1的全宽度
Figure PCTCN2022072565-appb-000009
因此，光学扩瞳装置EPE1可以被设置为显示具有全宽度
Figure PCTCN2022072565-appb-000010
的彩色虚拟图像VIMG1。
因此，光学扩瞳装置EPE1可以被设置为以红色和蓝色来显示彩色虚拟图像VIMG1的所有角落点(P1，P2，P3，P4)，其中所述彩色虚拟图像VIMG1具有全宽度
Figure PCTCN2022072565-appb-000011
因此，通过使用两条路径显示的彩色虚拟图像VIMG1的角宽度
Figure PCTCN2022072565-appb-000012
可以大幅大于其他不使用第二条路径的设备(EPE0)显示的彩色虚拟图像的最大角宽度(LIM1)。
具有两条路径的光学扩瞳装置EPE1可以被设置为显示彩色虚拟图像VIMG1，其具有扩展的角宽度
Figure PCTCN2022072565-appb-000013
第一路径可以被设置为传输输入图像的蓝色分量，同时允许泄漏输入图像的一个或多个角落点的红光。第二路径可以被设置为传输输入图像的红色分量，同时允许泄漏输入图像的一个或多个角落点的蓝光。
例如，在输入光(IN1)对应于输入图像(IMG0)且输入图像(IMG0)的宽度
Figure PCTCN2022072565-appb-000014
大于预定限制(LIM1)的情况下，入瞳单元(DOE1)可以设置为：
-与输入图像(IMG0)的第一个角落点(P1)对应的红光(B1aP1,R)，
-与输入图像(IMG0)的第二个角落点(P2)对应的蓝光(B1bP1,B)，
其中选择单元(DOE1，DOE2a，DOE2b，DOE3)的光栅矢量(m1aV1a，m2aV2a，m3aV3a，m1bV1b，m2bV2b，m3bV3b)，以便：
-第一角落点(P1)的红光通过第二扩瞳单元(DOE2b)从入瞳单元(DOE1)导向出瞳单元(DOE3)，
-第一导波光(B1a)不包含第一角落点(P1)的红光，
-第二角落点(P2)的蓝光通过第一扩瞳单元(DOE2a)从入瞳单元(DOE1)导向出瞳单元(DOE3)，并且
-第二角落点(P2)的蓝光无法满足在入瞳单元(DOE1)和第二扩瞳单元(DOE2b)之间全内反射(TIR)的标准。
例如，在输入光(IN1)对应于输入图像(IMG0)且输入图像(IMG0)的 宽度
Figure PCTCN2022072565-appb-000015
大于预定限制(LIM1)的情况下，入瞳单元(DOE1)可以设置为：
-与输入图像(IMG0)的第一角落点(P1)对应的红光(B1aP1,R)，
-与输入图像(IMG0)的第一角落点(P1)对应的蓝光(B1aP1,B)，
-与输入图像(IMG0)的第二角落点(P2)对应的红光(B1bP2,R)，
-与输入图像(IMG0)的第二角落点(P2)对应的蓝光(B1bP2,B)，
其中选择单元(DOE1，DOE2a，DOE2b，DOE3)的光栅矢量(m1aV1a，m2aV2a，m3aV3a，m1bV1b，m2bV2b，m3bV3b)，以便：
-第一角落点(P1)的红光通过第二扩瞳单元(DOE2b)从入瞳单元(DOE1)导向出瞳单元(DOE3)，
-第一导波光(B1a)不包含第一角落点(P1)的红光，
-第一角落点(P1)的蓝光通过第一扩瞳单元(DOE2a)从入瞳单元(DOE1)导向出瞳单元(DOE3)，
-第一角落点(P1)的蓝光未能通过第二扩瞳单元(DOE2b)从入瞳单元(DOE1)导向出瞳单元(DOE3)，
-第二角落点(P2)的红光未能通过第一扩瞳单元(DOE2a)从入瞳单元(DOE1)导向出瞳单元(DOE3)，
-第二角落点(P2)的红光通过第二扩瞳单元(DOE2b)从入瞳单元(DOE1)导向出瞳单元(DOE3)，
-第二角落点(P2)的蓝光通过第一扩瞳单元(DOE2a)从入瞳单元(DOE1)导向出瞳单元(DOE3)，并且
-第二角落点(P2)的蓝光无法满足在入瞳单元(DOE1)和第二扩瞳单元(DOE2b)之间全内反射(TIR)的条件。
光学扩瞳装置EPE1可以被设置为如下操作，使得在蓝色导波光经由装置EPE1的第一路径传播的情况下，蓝色导波光的波矢落在区域ZONE1内，并且装置EPE1可以设置为，在红色导波光通过装置EPE1的第二路径传播的情况下，红色导波光的波矢落在区域ZONE1内。
结合图11a和11b，分别可知角落点P1的蓝光和红光在波导板SUB1中的传播情况；结合图12a和12b，分别可知角落点P2的蓝光和红光在波导板SUB1中的传播情况；结合图13a和13b，分别可知中心点P0的蓝光和红光在波导板SUB1中的传播情况；结合图14a和14b，分别可知角落点P3的蓝光和红光在 波导板SUB1中的传播情况；结合图15a和15b，分别可知角落点P4的蓝光和红光在波导板SUB1中的传播情况。
本发明实施例还提供了一种显示装置，包括如上所述的光学扩瞳装置，以及用于形成主图像的光学引擎。
如图16a至16e所示，光学引擎ENG1可以由显示器DISP1和准直光学器件LNS1组成。显示器DISP1可以被设置为显示输入图像IMG0。显示器DISP1也可以被称为微型显示器。显示器DISP1也可以被称为空间光强度调制器。输入图像IMG0也可以被称为图像源。
输入图像IMG0可以包含中心点P0和四个角落点P1，P2，P3，P4。P1可以表示左上角落点。P2可以表示右上角落点。P3可以表示左下角落点。P4可以表示右下角落点。输入图像IMG0可以包含图形字符例如，“F”，“G”和“H”。
输入图像IMG0可以是彩色图像。输入图像IMG0可以是例如，RGB图像，其可以包含红色局部图像，绿色局部图像和蓝色局部图像。每个图像点可以提供例如红光，绿光和/或蓝光。红光可以表现为红色，例如，波长650nm，绿光可以表现为绿色，例如，波长510nm。蓝光可以表现为蓝色，例如，波长470nm。特别的，彩色图像IMG0的角落点的光可以包含红光和蓝光。
光学引擎ENG1可以提供输入光IN1，其可以包含多个基本准直的光束(B0)。每个红色光束可以沿不同方向传播，并且可以对应于输入图像IMG0的不同点。例如，红色光束B0P1,R可以对应于图像点P1，并且在波矢k0P1,R的方向上传播。
类似的，蓝色光束(B0P1,B)可以对应于相同的图像点P1，并且在波矢(k0P1,B)的方向上传播。
输入光IN1中，输入图像IMG0第一角落点P1相对应的蓝色光束(B0P1,B)的传播方向(k0P1,B)可以平行于第一角落点P1相对应的红色光束(B0P1,R)的传播方向(k0P1,R)。
输入光IN1中，输入图像IMG0第二角落点P2相对应的蓝色光束(B0P2,B)的传播方向(k0P2,B)可以平行于第二角落点P2相对应的红色光束(B0P2,R)的传播方向(k0P2,R)。
红色光束B0P2,R可以对应于图像点P2，并且在波矢k0P2,R的方向上传播。 红色光束B0P3,R可以对应于图像点P3，并且在波矢k0P3,R的方向上传播。红色光束B0P4,R可以对应于图像点P4，并且在波矢k0P4,R的方向上传播。红色光束B0P0,R可以对应于中心像点P1，并且在波矢k0P0,R的方向上传播。
光的波矢(k)可以被定义为具有所述光的传播方向的矢量，由2π/λ给出大小，其中λ是所述光的波长。
参照图16f，输出光OUT1可以包含多个输出光束，其可以对应于所显示的虚像VIMG1。每个输出光束对应于图像上不同位置的像点。例如，在波矢k3P0,R的方向上传播的红色光束可以对应于图像VIMG1的点P0'。在波矢k3P1,R的方向上传播的红色光束可以对应于图像VIMG1的点P1'。沿波矢k3P2,R的方向传播的红色光束可以对应于图像VIMG1的点P2'。在波矢k3P3,R的方向上传播的红色光束可以对应于点P3'。在波矢k3P4,R的方向上传播的红色光束可以对应于点P4'。
光学扩瞳装置EPE1可以通过扩展光引擎ENG1的出射光瞳来形成输出光OUT1。输出光OUT1可以包含多个输出光束，其对应于所显示的虚像VIMG1。输出光束OUT1可以照射在观察者的眼睛EYE1上，使得观察者可以看到显示的虚像VIMG1。
显示的虚拟图像VIMG1可以具有中心点P0'和四个角落点P1'，P2'，P3'，P4'。输入光IN1可以包含与输入图像IMG0的点P0，P1，P2，P3，P4相对应的多个光束。光学扩瞳装置EPE1可以通过衍射和传导来自输入图像IMG0的点P0的光以形成所显示的虚拟图像VIMG1的点P0'。光学扩瞳装置EPE1可以分别通过衍射和传导来自点P1，P2，P3，P4的光以形成点P1′，P2′，P3′，P4′。
光学扩瞳装置EPE1可以形成输出光OUT1，其包含在由波矢k3P0,R，k3P1,R，k3P2,R，k3P3,R，k3P4,R等指定的不同方向上传播的多个光束。
对应于所显示虚像VIMG1的点P0'的红色光束具有波矢k3P0,R。对应于点P1'的红色光束具有波矢k3P1,R。对应于点P2'的红色光束具有波矢k3P2,R。对应于点P3'的红色光束具有波矢k3P3,R。对应于点P4'的红色光束具有波矢k3P4,R。
光学扩瞳装置EPE1可以被设计成，使得波矢k3P1,R与输入光IN1中的点P1对应的红光的波矢k0P1,R平行。波矢k3P0,R可以与点P0对应的波矢k0P0,R 平行。波矢k3P2,R可以与点P2对应的波矢k0P2,R平行。波矢k3P3,R可以与点P3对应的波矢k0P3,R平行。波矢k3P4,R可以与点P4对应的波矢k0P4,R平行。
在图16g和16h中，所显示的虚像VIMG1具有角宽度
Figure PCTCN2022072565-appb-000016
和角高度Δθ。
所显示的虚拟图像VIMG1可以具有例如第一角落点P1'，在图像VIMG1的左侧；第二角落点P2'，例如在图像VIMG1的右侧。虚拟图像VIMG1的角宽度可以等于角落点P1'，P2'的波矢k3P1,R，k3P2,R之间的水平夹角。
显示的虚像VIMG1可以具有上角落点P1'和下角落点P3'。虚拟图像VIMG1的角高度Δθ可以等于角落点P1'，P3'的波矢k3P1,R，k3P3,R之间的垂直夹角。
光学扩瞳装置EPE1的两条路径可以允许显示宽的彩色虚拟图像VIMG1。光学扩瞳装置EPE1的两条路径可以允许显示具有扩展的角宽度
Figure PCTCN2022072565-appb-000017
的彩色虚拟图像VIMG1。
可通过方位角
Figure PCTCN2022072565-appb-000018
和θ以指定波矢的方向。角度
Figure PCTCN2022072565-appb-000019
可以表示波矢与参考平面REF1之间的角度。参考平面REF1可以被定义为方向SZ和SY的平面。角度θ可以表示波矢与参考平面REF2之间的角度。参考平面REF2可以被定义为方向SZ和SX的平面。
显示装置500可以是虚拟现实设备500。显示装置500可以是增强现实设备500。显示装置500可以是近眼设备。显示装置500可以是可穿戴设备，例如，头盔。显示装置500可以包含例如头带，显示装置500可以通过头带佩戴在用户的头上。在显示装置500的操作期间，可以将出瞳单元DOE3定位在，例如用户的左眼EYE1或右眼EYE1前面。显示装置500可以将输出光OUT1投射到用户的眼睛EYE1中。在一个实施例中，显示装置500可以包含两个引擎ENG1和/或两个光学扩瞳装置EPE1以显示立体图像。在增强现实显示装置500中，除了显示的虚拟图像之外，观看者还可以通过光学扩瞳装置EPE1看到真实的物体和/或环境。光引擎ENG1可以被设置为生成静止图像和/或视频。光引擎ENG1可以从数字图像生成真实的主图像IMG0。光引擎ENG1可以从互联网或智能手机接收一个或多个数字图像。显示装置500可以是智能手机。所显示的图像可以被人观看，还可以被动物或机器(可能包含例如照相机)观看。
显示装置500可以包含光学引擎ENG1，以形成主图像IMG0并将主图像IMG0转换成输入光IN1的多个光束。光引擎ENG1的光可以从光学扩瞳装置 EPE1的入瞳单元DOE1耦入。输入光IN1可以从光学扩瞳装置EPE1的入瞳单元DOE1耦入。显示装置500可以是用于显示虚拟图像的显示装置。显示装置500也可以是近眼光学设备。
光学扩瞳装置EPE1可以将虚拟图像内容从光引擎ENG1传播到用户的眼睛EYE1前面。光学扩瞳装置EPE1可以扩展视瞳，从而扩大了eyebox。
光引擎ENG1可以包含微显示器DISP1以生成主图像IMG0。微型显示器DISP1可以包含发光像素的二维阵列。显示器DISP1可以产生例如主图像IMG0，分辨率为1280×720(HD)。显示器DISP1可以产生例如主图像IMG0，分辨率为1920×1080(Full HD))。显示器DISP1可以产生例如主图像IMG0，分辨率为3840×2160(4KUHD)。主图像IMG0可以包含多个图像点P0，P1，P2，...。光引擎ENG1可以包含准直光学器件LNS1，以形成与每个图像像素不同的光束。光引擎ENG1可以包含准直光学器件LNS1，以从图像点P0的光形成基本准直的光束。显示器DISP1中心和光学器件LNS1的中心可以定义一个光引擎ENG1的光轴AX0。点P0和光学器件LNS1的中心点可以定义光轴AX0。
与图像点P0相对应的光束可以在波矢k0P0,R指定的方向上传播。对应于不同的图像点P1的光束可以沿与方向k0P0,R不同的方向k0P1,R传播。
光引擎ENG1可以提供与所生成的主图像IMG0相对应的多个光束。由光引擎ENG1提供的一个或多个光束可以耦合到光学扩瞳装置EPE1中，并作为输入光IN1。
光引擎ENG1可以包含例如一个或多个发光二极管(LED)。显示器DISP1可以包含一台或多台微显示器成像仪，例如硅基液晶(LCOS)，液晶显示器(LCD)，数字微镜器件(DMD)。
本发明实施例还提供了一种光束扩展方法，采用如上所述的光学扩瞳装置进行光束扩展。
本发明实施例还提供了一种图像显示方法，采用如上所述的光学扩瞳装置进行图像显示。
说明书中各个实施例采用递进的方式描述，每个实施例重点说明的都是与其他实施例的不同之处，各个实施例之间相同相似部分互相参见即可。对于实施例公开的系统而言，由于其与实施例公开的方法相对应，所以描述的比较简单，相关之处参见方法部分说明即可。应当指出，对于本技术领域的普通技术 人员来说，在不脱离本申请原理的前提下，还可以对本申请进行若干改进和修饰，这些改进和修饰也落入本申请权利要求的保护范围内。
还需要说明的是，在本说明书中，诸如第一和第二等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来，而不一定要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的过程、方法、物品或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法、物品或者设备所固有的要素。在没有更多限制的状况下，由语句“包括一个……”限定的要素，并不排除在包括所述要素的过程、方法、物品或者设备中还存在另外的相同要素。

Claims (14)

  1. 一种光学扩瞳装置，其特征在于，包括波导板，所述波导板上设置有：
    入瞳单元，用于通过衍射输入光以形成第一导波光和第二导波光；
    第一扩瞳单元，用于衍射所述第一导波光以形成第三导波光；
    第二扩瞳单元，用于衍射所述第二导波光以形成第四导波光；
    出瞳单元，用于衍射所述第三导波光以形成第一输出光，和用于衍射第四导波光以形成第二输出光，以及将所述第一输出光和第二输出光组合形成组合输出光；
    所述入瞳单元和出瞳单元沿所述波导板对角线设置，且所述出瞳单元设置于所述入瞳单元的下方，所述第一扩瞳单元和第二扩瞳单元设置于所述入瞳单元和出瞳单元的两侧。
  2. 根据权利要求1所述的光学扩瞳装置，其特征在于，还包括光谱滤光片区域，所述光谱滤光片区域包括设置于所述第一扩瞳单元内侧的第一光谱滤光片区域和设置于所述第二扩瞳单元内侧的第二光谱滤光片区域，所述第一光谱滤光片区域用于防止第一颜色光通过所述第一扩瞳单元从所述入瞳单元传输至所述出瞳单元，所述第二光谱滤光片区域用于防止第二颜色光通过所述第二扩瞳单元从所述入瞳单元传输至所述出瞳单元。
  3. 根据权利要求2所述的光学扩瞳装置，其特征在于，还包括布拉格光栅区域，所述布拉格光栅区域包括分别设置于第一光谱滤光片区域内侧和第二光谱滤光片区域内侧的第一布拉格光栅区域和第二布拉格光栅区域，且所述第一布拉格光栅区域和第二布拉格光栅区域分别与第一光谱滤光片区域和第二光谱滤光片区域重叠设置。
  4. 根据权利要求3所述的光学扩瞳装置，其特征在于，所述波导板至少包含一个覆层、至少一个保护层以及至少一个机械支撑层，所述光谱滤光片区域与所述布拉格光栅区域位于所述波导板的同一侧或者不同侧。
  5. 根据权利要求3所述的光学扩瞳装置，其特征在于，所述第一布拉格光栅区域与所述第一光谱滤光片区域之间的第一重叠区域面积为所述第一布拉格光栅区域面积的50％～100％，所述第二布拉格光栅区域与所述第二光谱滤光片区域之间的第二重叠区域面积为所述第二布拉格光栅区域面积的50％～100％。
  6. 根据权利要求3所述的光学扩瞳装置，其特征在于，所述第一布拉格光栅区域在水平方向的横截面宽度为所述波导板的导波层厚度3～5倍，所述第二布拉格光栅区域在垂直方向的横截面宽度为所述波导板的导波层厚度3～5倍。
  7. 根据权利要求1所述的光学扩瞳装置，其特征在于，所述入瞳单元设置有用于将第一导波光衍射到所述第一扩瞳单元的第一衍射特征，以及用于将第二导波光衍射到第二扩瞳单元的第二衍射特征，所述第一衍射特征和第二衍射特征均为凸起或者凹槽。
  8. 根据权利要求3所述的光学扩瞳装置，其特征在于，所述入瞳单元包括分别用于形成所述第一导波光和第二导波光的第一入瞳光栅和第二入瞳光栅，所述第一入瞳光栅和第二入瞳光栅分别具有第一入瞳光栅周期和第二入瞳光栅周期，且所述第一入瞳光栅周期和第二入瞳光栅周期不同；
    所述出瞳单元包括分别用于形成所述第一输出光和第二输出光的第一出瞳光栅和第二出瞳光栅，所述第一出瞳光栅和第二出瞳光栅分别具有第一出瞳光栅周期和第二出瞳光栅周期，且所述第一出瞳光栅周期和第二出瞳光栅周期不同。
  9. 根据权利要求8所述的光学扩瞳装置，其特征在于，所述第一布拉格光栅区域和第二布拉格光栅区域的光栅周期分别为所述第一出瞳光栅周期和第二出瞳光栅周期的一半。
  10. 根据权利要求1-9任一项所述的光学扩瞳装置，其特征在于，所述入瞳单元用于衍射输入光，使得第一导波光包括输入图像的中心点的光，并且使得第二导波光包括图像中心点的光；
    所述出瞳单元用于衍射从第一扩瞳单元接收的所述第三导波光，使得所述第一输出光包括中心点的光，其中所述出瞳单元被用于衍射从第二扩瞳单元接收的所述第四导波光，使得所述第二输出光包括中心点的光，所述第一输出光中的中心点的光沿光轴传播，所述第二输出光中的中心点的光沿相同的光轴传播。
  11. 根据权利要求10所述的光学扩瞳装置，其特征在于，所述第一导波光中的中心点的光在第一方向传播，所述第二导波光中的中心点的光在第二方向传播，其中所述第一方向与所述第二方向的夹角范围为60°～120°。
  12. 一种显示装置，其特征在于，包括如权利要求1～11任一项所述的光学 扩瞳装置，以及用于形成主图像的光学引擎。
  13. 一种光束扩展方法，其特征在于，采用如权利要求1～11任一项所述的光学扩瞳装置进行光束扩展。
  14. 一种图像显示方法，其特征在于，采用如权利要求1～11任一项所述的光学扩瞳装置进行图像显示。
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