WO2019228280A1 - 全息光学元件及其制作方法、像重建方法、增强现实眼镜 - Google Patents

全息光学元件及其制作方法、像重建方法、增强现实眼镜 Download PDF

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WO2019228280A1
WO2019228280A1 PCT/CN2019/088404 CN2019088404W WO2019228280A1 WO 2019228280 A1 WO2019228280 A1 WO 2019228280A1 CN 2019088404 W CN2019088404 W CN 2019088404W WO 2019228280 A1 WO2019228280 A1 WO 2019228280A1
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Prior art keywords
light
optical element
holographic optical
interference fringe
lens
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PCT/CN2019/088404
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English (en)
French (fr)
Inventor
张洪术
赵合彬
邱云
王丹
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京东方科技集团股份有限公司
北京京东方显示技术有限公司
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Application filed by 京东方科技集团股份有限公司, 北京京东方显示技术有限公司 filed Critical 京东方科技集团股份有限公司
Priority to US16/615,215 priority Critical patent/US11320785B2/en
Priority to EP19810947.2A priority patent/EP3805867A4/en
Publication of WO2019228280A1 publication Critical patent/WO2019228280A1/zh

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/26—Processes or apparatus specially adapted to produce multiple sub- holograms or to obtain images from them, e.g. multicolour technique
    • G03H1/2645—Multiplexing processes, e.g. aperture, shift, or wavefront multiplexing
    • G03H1/265—Angle multiplexing; Multichannel holograms
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/04—Processes or apparatus for producing holograms
    • G03H1/0402—Recording geometries or arrangements
    • 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
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    • G02—OPTICS
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    • G02B5/00—Optical elements other than lenses
    • G02B5/32—Holograms used as optical elements
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/04—Processes or apparatus for producing holograms
    • G03H1/0465—Particular recording light; Beam shape or geometry
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/04—Processes or apparatus for producing holograms
    • G03H1/10—Processes or apparatus for producing holograms using modulated reference beam
    • G03H1/12—Spatial modulation, e.g. ghost imaging
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/22—Processes or apparatus for obtaining an optical image from holograms
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/22—Processes or apparatus for obtaining an optical image from holograms
    • G03H1/2202—Reconstruction geometries or arrangements
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    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
    • G11B7/0065—Recording, reproducing or erasing by using optical interference patterns, e.g. holograms
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
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    • G02B27/01—Head-up displays
    • G02B27/0101—Head-up displays characterised by optical features
    • G02B2027/0127—Head-up displays characterised by optical features comprising devices increasing the depth of field
    • 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
    • G02B2027/0174—Head mounted characterised by optical features holographic
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
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    • G02B27/017—Head mounted
    • G02B2027/0178—Eyeglass type
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1347—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/22—Processes or apparatus for obtaining an optical image from holograms
    • G03H1/2294—Addressing the hologram to an active spatial light modulator
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/02—Details of features involved during the holographic process; Replication of holograms without interference recording
    • G03H2001/0208—Individual components other than the hologram
    • G03H2001/0224—Active addressable light modulator, i.e. Spatial Light Modulator [SLM]
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/04—Processes or apparatus for producing holograms
    • G03H1/0402—Recording geometries or arrangements
    • G03H2001/0439—Recording geometries or arrangements for recording Holographic Optical Element [HOE]
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/04—Processes or apparatus for producing holograms
    • G03H1/0465—Particular recording light; Beam shape or geometry
    • G03H2001/0473—Particular illumination angle between object or reference beams and hologram
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/22—Processes or apparatus for obtaining an optical image from holograms
    • G03H1/2249—Holobject properties
    • G03H2001/2281—Particular depth of field
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H2223/00—Optical components
    • G03H2223/17—Element having optical power
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H2223/00—Optical components
    • G03H2223/19—Microoptic array, e.g. lens array
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
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    • G03H2225/00—Active addressable light modulator
    • G03H2225/60—Multiple SLMs
    • G—PHYSICS
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    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H2270/00—Substrate bearing the hologram
    • G03H2270/55—Substrate bearing the hologram being an optical element, e.g. spectacles

Definitions

  • Embodiments of the present disclosure relate to a holographic optical element and a manufacturing method thereof, an image reconstruction method, and augmented reality glasses.
  • Holographic optical elements are optical elements made according to the principle of holography, and are usually made on photosensitive film materials.
  • Holographic optical element is a kind of diffractive optical element based on the principle of diffraction.
  • the so-called holography refers to the technique of recording the amplitude and phase distribution of light waves on a photographic film or a dry plate and reproducing a three-dimensional image of an object.
  • Ordinary photography can only record the amplitude (intensity) of the reflected or transmitted light of an object, so a two-dimensional image of the object is recorded.
  • Holography records not only the amplitude but also the phase of light.
  • the reflected light wave of the illuminating object carries the information transmission of the object shape.
  • the wave front carrying the information is recorded with a recording medium, and the wave front can be reproduced at another time and place by appropriate methods, so that the object's Three-dimensional image.
  • Depth of field refers to the range of distances between the front and back of the subject as measured by imaging at the leading edge of a camera lens or other imager.
  • At least one embodiment of the present disclosure provides a holographic optical element, including a substrate, and a recording material layer disposed on the substrate.
  • the recording material layer records at least two sets of interference fringes, each set of The interference fringe includes a first interference fringe and a second interference fringe; the first interference fringe is formed by first signal light and a first reference light incident from both sides of the recording material layer, respectively; and the second interference fringe is formed by A second signal light and a second reference light incident from both sides of the recording material layer are formed, and the second signal light passes through a lens before being incident; an incident angle of the first signal light and the second reference light The incidence angles of the first signal light corresponding to the interference fringes of each group are different, and the focal lengths of the lenses through which the second signal light corresponding to the interference fringes of each group pass before being incident are different.
  • At least one embodiment of the present disclosure also provides a method for manufacturing a holographic optical element, including: forming a recording material layer on a substrate, and fabricating at least two sets of interference fringes in the recording material layer, wherein each set of The interference fringe includes a first interference fringe and a second interference fringe.
  • Making each group of the interference fringes includes: irradiating the recording material layer from both sides of the substrate with a first signal light and a first reference light, and recording the first interference fringes in the recording material layer; A lens is placed on one side of the substrate, and a second signal light and a second reference light are used to irradiate the recording material layer from both sides of the substrate, respectively, and the second signal light and the lens are on the substrate.
  • a second interference fringe is recorded in the recording material layer.
  • the angle of incidence of the first signal light is equal to the angle of incidence of the second reference light; when making the interference fringes of different groups, the first signal light with a different incident direction is used. And use lenses with different focal lengths.
  • At least one embodiment of the present disclosure also provides an image reconstruction method of a holographic optical element, which is applied to the holographic optical element as described above.
  • the image reconstruction method includes: irradiating at least two of the holographic optical element with detection light, respectively.
  • Each group of interference fringes is grouped to establish an image of at least two depths of field, wherein the interference fringes of each group include a first interference fringe and a second interference fringe.
  • Illuminating each group of interference fringes with the detection light includes: setting a spatial light modulator on one side of the holographic optical element, the spatial light modulator being at a first signal forming a first interference fringe of the holographic optical element An extension line of the optical light path; using the detection light to irradiate the first interference fringe along the incident direction of the first reference light, the detection light and the spatial light modulator are on the same side of the holographic optical element, so that the The detection light is diffracted to the spatial light modulator by the first interference fringe; the spatial light modulator is used to modulate the diffracted light of the detection light, and the modulated modulated light forms the holographic optical element along The incident direction of the second reference light of the second interference fringe is returned to the holographic optical element, so that the modulated light is diffracted by the second interference fringe to the extension of the optical path of the second signal light forming the second interference fringe. on-line.
  • the detection light is coherent light of the first signal light
  • the modulated light is coherent light of
  • At least one embodiment of the present disclosure also provides an augmented reality glasses including a mirror lens, and the lens is provided with the holographic optical element of the above embodiment.
  • FIG. 1A is a schematic diagram of a method for manufacturing a first interference fringe in a group of interference fringes provided by at least one embodiment of a method for manufacturing a holographic optical element.
  • FIG. 1B is a schematic structural diagram of a holographic optical element provided by at least one embodiment of the present disclosure.
  • FIG. 2 is a schematic diagram of a method for manufacturing a second interference fringe in a group of interference fringe shown in FIG. 1.
  • FIG. 3 is a schematic diagram of a method for manufacturing a first interference fringe in another group of interference fringe of a method for manufacturing a holographic optical element provided by at least one embodiment of the present disclosure.
  • FIG. 4 is a schematic diagram of a method for manufacturing a second interference fringe in another group of interference fringe shown in FIG. 3.
  • FIG. 5 is a schematic diagram of an image reconstruction method for a group of interference fringes shown in FIGS. 1 and 2.
  • FIG. 6 is a schematic diagram of an image reconstruction method for another group of interference fringes shown in FIG. 3 and FIG. 4.
  • FIG. 7 is a schematic diagram of depth of field after image reconstruction in FIG. 5 and FIG. 6.
  • Figure 8 is a schematic diagram of the principle of a compressed light field.
  • FIG. 9A is a schematic diagram of augmented reality glasses provided by at least one embodiment of the present disclosure.
  • FIG. 9B is a block diagram of augmented reality glasses provided by at least one embodiment of the present disclosure.
  • Some embodiments of the present disclosure provide a holographic optical element including a substrate and a recording material layer disposed on the substrate. At least two sets of interference fringes are recorded in the recording material layer, and each set of interference fringes includes a first interference fringe and The second interference fringe.
  • the first interference fringe is formed by first signal light and first reference light incident from both sides of the recording material layer; the second interference fringe is formed by second signal light and second reference light incident from both sides of the recording material layer
  • the reference light is formed and the second signal light passes through the lens before being incident; the incident angle of the first signal light is equal to the incident angle of the second reference light; the incident direction of the first signal light corresponding to each group of interference fringes is different And the focal lengths of the lenses through which the second signal light corresponding to each group of interference fringes passes before being incident are different.
  • Each group of interference fringes recorded on the above holographic optical element can form an image of one depth of field, and a holographic optical element having multiple groups of interference fringes can form an image of multiple depths of field.
  • the process of forming the first interference fringe is equivalent to the process of making a mirror with a specific angle.
  • the probe light can be directionally diffracted to a specific direction through the first interference fringe. Therefore, the holographic optical element has a directional reflection function.
  • the nature of the lens is used to make the imaging position in a fixed position.
  • the human eye can only observe the image at a specific position related to the focal length, so that the holographic optical element has a lens function. .
  • the interference fringes of signal light of different incident angles are recorded in the above holographic optical element, and images corresponding to multiple angle signal light can be presented to realize multi-angle multiplexing of the holographic optical element; and interference fringes of signal light of different incident angles are stored in the same
  • the capacity of the holographic optical element to store wavefront information can be effectively increased, and the storage density can be improved.
  • the above-mentioned holographic optical element also has the advantages of transparency, small size, and thin thickness, and can be applied to augmented reality glasses.
  • ambient light can enter the human eye through holographic optical elements and fuse with images of different depths of field To form a rich visual experience.
  • the holographic optical element 1 is in a sheet shape.
  • the holographic optical element 1 includes a substrate 101 and a recording material layer 102 disposed on the substrate 101.
  • the substrate 101 is a transparent substrate or a transparent base film, and is made of, for example, glass or a plastic material.
  • At least two sets of interference fringes are recorded in the recording material layer 102, and each set of interference fringes includes a first interference fringe and a second interference fringe.
  • the first interference fringe is formed by the first signal light 3 and the first reference light 5 incident from both sides of the recording material layer; see FIG. 2, the second interference fringe is formed by the second signal light incident from both sides of the recording material layer 4 and the second reference light 6 are formed, and the second signal light 4 passes through the lens 2 before being incident.
  • the incident angle ⁇ 1 of the first signal light 3 is equal to the incident angle ⁇ 1 ′′ of the second reference light 6.
  • the incident angle refers to the included angle between the incident light and the normal of the incident surface (as shown by the dashed line perpendicular to the surface of the holographic optical element 1 in FIG. 1). Therefore, the incident angles of two rays with different incident directions may be the same. For example, the two incident rays are incident symmetrically from both sides of the normal of the incident surface, and the incident angles are equal.
  • first signal light 3, the first reference light 5, the second signal light 4, and the second reference light 6 are plane waves.
  • the first reference light 5 is a coherent light of the first signal light 3, for example, the first reference light 5 and the first signal light 3 are both lasers, for example, both are from the same first light source (not shown) laser beam and separated by light Mirror decomposed.
  • the second reference light 6 is a coherent light of the second signal light 4, and the second reference light 6 and the second signal light 4 are lasers, for example, both come from the same second light source (not shown) and are split by a beam splitter. get.
  • the first light source is the same as or different from the second light source.
  • the first signal light 3 is incident from the left side of the recording material layer of the holographic optical element 1 at an angle of ⁇ 1
  • the first reference light 5 is at ⁇ 1 ′.
  • the angle is incident from the right side of the recording material layer of the holographic optical element 1, and the first signal light 3 and the first reference light 5 interfere in the plane where the recording material layer is located (for example, according to the design in the center plane of the recording material layer).
  • the first interference fringe is recorded in the recording material layer of the holographic optical element 1.
  • the second signal light 4 is incident from the left side of the holographic optical element 1 and passes through the lens 2 with a focal length F1 before the incident.
  • the second reference light 6 is from the right side of the holographic optical element 1 at an angle of ⁇ 1 ”.
  • the second signal light 4 and the second reference light 6 interfere in the plane in which the recording material layer is located (for example, in the center plane of the recording material layer according to the design), so that the first recording material layer in the recording material layer of the holographic optical element 1 is recorded. Two interference fringes.
  • a holographic optical element 1 having a set of interference fringes can be formed thereby.
  • changing the incident angles of the first signal light 3, the first reference light 5 and the second reference light 6, and changing the focal length of the lens for example, using a lens with a focal length different from F1
  • changing the focal length of the lens for example, using a lens with a focal length different from F1
  • multiple groups of interference fringes can be formed on the same holographic optical element 1 by changing the angle of the light beam and the focal length of the lens.
  • a holographic imaging technology realizes multi-depth-of-field imaging by programming a computer algorithm or by using a zoom distance, for example, adjusting a voltage in a liquid crystal prism to achieve zooming and then forming a multi-depth-of-field image.
  • each group of interference fringes recorded on the holographic optical element 1 can be an image of one depth of field, and the holographic optical element 1 having multiple groups of interference fringes can be an image of multiple depths of field.
  • the imaging method is simple and easy to operate. And lower cost.
  • the process of forming the first interference fringe is equivalent to the process of making a specific angle mirror.
  • the detection light can be directionally diffracted to a specific direction by the first interference fringe, so that the holographic optical element 1 has a directional reflection function.
  • the nature of the focus of the lens 2 is used, so that the imaging position is at a fixed position.
  • the human eye can only observe the image at a specific position related to the focal length, so that the holographic optical element 1 has the lens 2 Features. Therefore, the above-mentioned embodiments of the present disclosure integrate the functions of various optical elements in one holographic optical element 1, which is more practical.
  • the interference fringes of the signal light of different incident angles are recorded in the holographic optical element 1 of each embodiment of the present disclosure, and images corresponding to multiple angle signal lights can be presented to realize multi-angle multiplexing of the holographic optical element 1; and different incident angles
  • the interference fringes of the signal light are stored in the same holographic optical element 1, which can effectively increase the capacity of the holographic optical element 1 to store the wavefront information and increase the storage density.
  • the holographic optical element 1 of some embodiments of the present disclosure also has the advantages of transparency, small volume, and thin thickness.
  • Some embodiments of the present disclosure integrate the functions of multiple optical elements in a thin film of a holographic optical element 1, and the other holographic optical technology described above implements the integration of multiple optical element functions through an element (such as a liquid crystal prism) having a certain thickness.
  • the holographic optical element 1 of some embodiments of the present disclosure has a thin thickness and high transparency, and can be applied to augmented reality glasses. When used for augmented reality glasses, ambient light can pass through the holographic optical element 1 Enter the human eye and fuse with different depth of field images to form a rich visual experience.
  • the material forming the recording material layer includes at least one of a photosensitive resin, silver halide, and dichromate gelatin.
  • Some embodiments of the present disclosure also provide a method for manufacturing a holographic optical element, for manufacturing the holographic optical element 1 in the above embodiment.
  • the manufacturing method of the holographic optical element 1 includes a step of forming a recording material layer on a substrate, and further includes a step of making at least two sets of interference fringes in the recording material layer.
  • the step of making at least two sets of interference fringes in the recording material layer includes: irradiating the recording material layer from both sides of the substrate with the first signal light 3 and the first reference light 5 so that the first signal light 3 Interference with the first reference light 5 occurs in the recording material layer, and the first interference fringe is recorded in the recording material layer; the lens 2 is placed on the substrate side, and the second signal light 4 and the second reference light 6 are used respectively from the substrate Both sides of the recording material layer are irradiated, and the second signal light 4 and the lens 2 are on the same side of the substrate, so that the second signal light 4 and the second reference light 6 interfere in the recording material layer and record in the recording material layer.
  • the second interference fringe When making each group of interference fringes, the angle of incidence of the first signal light 3 is equal to the angle of incidence of the second reference light 6; when making different groups of interference fringes, the first signal light 3 with a different incident direction is used, and Lens 2.
  • the first signal light 3, the first reference light 5, the second signal light 4, and the second reference light 6 are plane waves, and the first reference light 5 is a coherent light of the first signal light 3.
  • the second reference light 6 is a coherent light of the second signal light 4.
  • the role of adding the lens 2 when making the second interference fringe is to use the function of the lens 2 as a focal point so that the position where the light is imaged after passing through the holographic optical element 1 is at a specific position, and the observer can only observe the specific position image.
  • the imaging position of the holographic optical element 1 is different, thereby realizing the multi-field depth imaging function.
  • the lenses 2 used in the production of multiple sets of interference fringes are of the same type, and other specifications such as different focal lengths and sizes may be the same or different.
  • the beneficial effects produced by using the above method to make the holographic optical element 1 are the same as the beneficial effects of the holographic optical element 1 described in some embodiments of the present disclosure, and are not repeated here.
  • an incident angle of the second signal light 4 is determined according to a position and a viewing angle of an eye relative to the holographic optical element 1 when an observer observes an image. For example, when an observer observes an image, his eyes are facing the center of the holographic optical element 1 and the angle of view is zero. At this time, the incident direction of the second signal light 4 is set to be perpendicular to the plane of the substrate, so that the imaging position is located in the direction observed by the observer.
  • the observer's eyes are located above the right side of the substrate plane of the holographic optical element 1, and the second signal light 4 is set to be incident from the left side and below the substrate plane of the holographic optical element 1, so that the observer can observe the imaging smoothly.
  • the method of making the holographic optical element 1 will be described in detail by taking the eye facing the center of the holographic optical element 1 as an example when an observer observes an image.
  • the operation when making the first set of interference fringes includes the steps of making the first interference fringes.
  • the first signal light 3 is incident from the left side of the recording material layer of the holographic optical element 1 at an angle of ⁇ 1
  • the first reference light 5 is incident from the recording material layer of the holographic optical element 1 at an angle of ⁇ 1 ′
  • the first interference fringe is recorded in the recording material layer of the holographic optical element 1.
  • the operation of making the first group of interference fringes also includes the steps of making the second interference fringes.
  • a lens 2 with a focal length of F1 is placed on the left side of the substrate of the holographic optical element 1, and the second signal light 4 is used.
  • the recording material layer is irradiated from the left side of the lens 2. Since the observer faces the center of the holographic optical element 1 when viewing the image, the second signal light 4 is incident in the horizontal direction (normal direction of the holographic optical element 1) in FIG. 2. ;
  • the second reference light 6 is used to irradiate the recording material layer from the right side of the substrate at an angle of ⁇ 1 ′′ to record the second interference fringe in the recording material layer.
  • the incident angle ⁇ 1 of the first signal light 3 The angle is equal to the incident angle ⁇ 1 ′′ of the second reference light 6.
  • the operation when making the second set of interference fringes also includes making the first interference fringes.
  • the first signal light 3 is incident from the left side of the recording material layer of the holographic optical element 1 at an angle of ⁇ 2
  • the first reference light 5 is incident from the recording material layer of the holographic optical element 1 at an angle of ⁇ 2 ′
  • the first interference fringes of the second group of interference fringes are recorded in the recording material layer of the holographic optical element 1 incident on the right side.
  • a lens 2 ′ having a focal length F2 (for example, different from the focal length F1) is placed on the left side of the substrate of the holographic optical element 1.
  • the left side of 2 ' is irradiated with the recording material layer in the horizontal direction, and the second reference light 6 is used to irradiate the recording material layer from the right side of the substrate at an angle of ⁇ 2 ", and a second group of interference fringes can be recorded in the recording material layer.
  • the second interference fringe is equal.
  • the incident direction of the first signal light 3 is changed, and the incident angles of the corresponding first reference light 5 and second reference light 6 are also changed.
  • lenses with different focal lengths that is, different from the previous lens 2 and lens 2 '
  • can make multiple sets of interference fringes such as 3 sets, 4 sets of interference fringes, etc., or more sets of interference fringes to form an image with multiple depths of field.
  • the incident angle difference of the second reference light 6 of the different groups of interference fringes is greater than or equal to 0.5 °. Because the interference fringes of different groups are angularly dependent, holographic diffraction at different angles does not affect each other, but the angles should not be too close. If the angle is too close, tiny diffraction occurs between the interference fringes, which can easily form "ghost shadows" and affect the imaging quality. In practice, when multiple reference light emitters are required, the installation space between the emitters is limited. If the angle is too close, the transmitter cannot be installed and the imaging effect is affected.
  • the types of the above-mentioned lens 2 and the above-mentioned lens 2 ′ include at least one of a convex lens, a concave lens, and a Fresnel lens, or any combination of at least two, etc., that is, the lens 2 and the lens 2 'Can be a combination lens (lens group).
  • the types of the lens 2 and the lens 2 'used in the process of making the holographic optical element 1 are different, the types of imaging after image reconstruction are different. In application, the types of the lens 2 and the lens 2' can be selected according to the actual imaging needs.
  • a convex lens is used to form a real image with multiple depths of field.
  • the imaging observation position and the convex lens are on the opposite side of the holographic optical element 1.
  • Multiple sets of convex lenses with different focal lengths form an image with multiple depths of field.
  • a concave lens is used to form a virtual image with multiple depths of field.
  • the imaging observation position and the concave lens are located on the same side of the holographic optical element 1.
  • An enlarged virtual image is presented, and there is a difference between the magnification of each group of images.
  • the Fresnel lens is equivalent to a multifocal convex lens 2.
  • a Fresnel lens is used to form a main image and a plurality of sub-images, and a reduced real image with multiple depths of field.
  • the area of the selected lens 2 and lens 2 ' is equal to or larger than the area of the substrate, so that it is convenient to record interference fringes on the entire substrate and increase the area of the visible field of the holographic optical element 1.
  • the lens 2 and the lens 2 ' are disposed close to the substrate, and the distance between the lens 2 and the lens 2' and the substrate is 0 to 5 cm. If the distance between the lens 2 and the lens 2 'and the substrate is too far, the imaging of the first interference fringe and the imaging of the second interference fringe will not be on the same plane, and a phase difference will easily occur. Ideally, if the lens 2 and the lens 2 'are integrated with the element substrate, this enables the substrate to realize the functions of the lens 2 and the lens 2'. In actual operation, the lens 2 and the lens 2 'can be as close as possible to the substrate, which is not easy. Generate a phase difference.
  • Some embodiments of the present disclosure also provide an image reconstruction method of a holographic optical element, which is applied to the holographic optical element 1 made by the method described above.
  • the image reconstruction method includes the steps of separately irradiating at least two sets of interference fringes of the holographic optical element 1 with detection light to establish an image of at least two depths of field.
  • Each set of interference fringes includes a first interference fringes and a second interference fringes.
  • the steps of each group of interference fringes include the following operations.
  • a spatial light modulator is provided on one side of the holographic optical element 1, and the spatial light modulator is located on the extension line of the first signal light 3 optical path forming the first interference fringe of the holographic optical element 1;
  • the detection light is used to irradiate the first interference fringe along the incident direction of the first reference light 5.
  • the detection light and the spatial light modulator are on the same side of the holographic optical element 1, so that the detection light is diffracted to the spatial light modulator by the first interference fringe;
  • the spatial light modulator modulates the diffracted light of the detection light, and returns the modulated light to the holographic optical element 1 along the incident direction of the second reference light 6 forming the second interference fringe of the holographic optical element 1 to make the modulated light
  • the second interference fringe is diffracted to the extension line of the optical path of the second signal light 4 forming the second interference fringe.
  • the detection light is coherent light of the first signal light 3 and the modulated light is coherent light of the second signal light 4.
  • the beneficial effects that can be obtained by performing the image reconstruction on the holographic optical element 1 by using the foregoing method are the same as the beneficial effects of the holographic optical element 1 described in some embodiments of the present disclosure, and are not repeated here.
  • the image reconstruction method of the holographic optical element 1 made according to the above embodiment will be described in detail with the eyes facing the center of the holographic optical element 1 when the observer observes the image and imaging into two depths of field images as an example.
  • the first group of interference fringes is used for imaging.
  • a first spatial light modulator SLM1 is disposed on the right side of the holographic optical element 1, and the first spatial light modulator SLM1 is located on the extension line of the first signal light 3 optical path forming the first interference fringe of the first group of interference fringe.
  • the first spatial light modulator SLM1 is used to modulate the diffracted light of the first detection light 7, for example, to modulate the amplitude and phase of the light. It is also possible to modulate how much light is reflected by each pixel, that is, adjust the gray level of each pixel , So that the emitted light appears different images.
  • the first modulated light is obtained by modulating the diffracted light of the first detection light 7, and the first modulated light is along the incident direction of the second reference light 6 (which is the same as the first detection light 7) that forms the second interference fringe of the first interference fringes.
  • the direction of the diffracted light is opposite to return to the holographic optical element 1, that is, the incident angle of the first modulated light is ⁇ 1 ”, so that the first modulated light is diffracted by the second interference fringe to the second signal light 4 forming the second interference fringe
  • the extension line of the optical path (the first modulated light diffracted is emitted in the horizontal direction).
  • the observer's eyes are in a direction facing the center of the holographic optical element 1, and an image of a depth of field, that is, the first image 9 can be observed.
  • a second group of interference fringes is used for imaging.
  • a second spatial light modulator SLM2 is provided on the right side of the holographic optical element 1, and the second spatial light modulator SLM2 is located on the extension line of the first signal light 3 optical path forming the first interference fringe of the second group of interference fringe.
  • the second detection light 8 is used to irradiate the first interference fringe along the incident direction of the first reference light 5 with an angle of incidence ⁇ 2 ', so that the second detection light 8 is diffracted by the first interference fringe to The second spatial light modulator SLM2.
  • the second spatial light modulator SLM2 is used to modulate the diffracted light of the second detection light 8 and make the modulated second modulated light along the incident direction of the second reference light 6 forming the second interference fringe of the second group of interference fringe (In the opposite direction of the diffracted light path of the second detection light 8) to return to the holographic optical element 1, that is, the incident angle of the second modulated light is ⁇ 2 ", so that the second modulated light is diffracted by the second interference fringe to form a second interference
  • the extended line of the second signal light 4 of the stripe (the second modulated light that is diffracted is emitted in the horizontal direction).
  • the observer's eyes are in the direction facing the center of the holographic optical element 1, and an image of another depth of field can be observed. Ie second image 10.
  • the imaging distance between the first image 9 and the second image 10 is related to the focal length of the lens 2 and the lens 2 'used in making the holographic optical element 1. For example, if the focal length F1> F2 of the lens 2 and the lens 2 ′ used in making the holographic optical element 1, as shown in FIG. 7, the distance between the imaging position of the first image 9 and the holographic optical element 1 is greater than the second image 10 The distance between the imaging position and the holographic optical element 1.
  • the spatial light modulator includes an amplitude-type spatial light modulator or a phase-type spatial light modulator.
  • the spatial light modulator is an amplitude modulator, such as a digital micromirror (DMD), it can form an image with a fixed depth of field, such as the first image 9 and the second image 10 in FIG. 7.
  • DMD digital micromirror
  • the spatial light modulator uses a phase-type spatial light modulator (a spatial light modulator that can change the phase), such as an LCOS (Liquid Crystal, Silicon, Liquid Crystal with Silicon) modulator, the phase change will affect the image, and it will appear like Complex, variable depth of field, image-changing images.
  • LCOS Liquid Crystal, Silicon, Liquid Crystal with Silicon
  • the image reconstruction method of the holographic optical element further includes: using a plurality of spatial light modulators, and repeating the above image reconstruction steps to form multiple beams of modulated light.
  • Different beams of modulated light modulate images of different depths of field, and the light intensities of multiple beams of modulated light satisfy the light-emphasis relationship of the compressed light field to form a light field augmented reality.
  • the so-called light field refers to the amount of light that passes through each point in each direction.
  • Ordinary Augmented Reality (AR) can only present plane images or images with a single depth of field through the lens.
  • Light field augmented reality technology can present images with at least two depths of field.
  • the depth of field of the image shown in FIG. 7 is a fixed depth of field; if a light field augmented reality is formed, when the modulated light field is observed by the human eye, The perceived depth of field is greater than the depth of field shown in Figure 7.
  • the depth of the compressed light scene is a continuous range, not two fixed points, and the depth of field is wider. Therefore, a light field augmented reality is formed, and an observer can observe an image with continuous depth of field, and the visual perception of the depth of field is wider, improving the user experience.
  • the light field system is usually provided with a backlight layer 12, a polarizing layer 11, and a plurality of liquid crystal screens.
  • the liquid crystal screen is used as a spatial light modulation unit for multi-layer light field display.
  • the gray value at the sub-pixel position modulates the light intensity of the incident light (from the backlight layer 12).
  • the gray value of the corresponding pixel of each layer of the LCD screen determines the light intensity transmission rate.
  • ⁇ 1 , ⁇ 2 , and ⁇ 1 are the pixel positions of the LCD screen layer A 13 and the LCD screen layer B14, respectively. Assume that two beams of light pass through the LCD screen layer A 13 and the LCD screen layer B 14.
  • the output intensity of the beam of light can be expressed as
  • I out ( ⁇ 1 , ⁇ 1 ) I in ⁇ T A ( ⁇ 1 ) ⁇ T B ( ⁇ 1 )
  • I out ( ⁇ 2 , ⁇ 1 ) I in ⁇ T A ( ⁇ 2 ) ⁇ T B ( ⁇ 1 )
  • T A ( ⁇ 1) and T A ( ⁇ 2) denote the LCD layer A 13 in the [alpha] 1 and the light intensity of the transmission rate 2 position ⁇
  • T B ( ⁇ 1) represents the position beta] of Light intensity transmission rate, so two rays have different light intensity.
  • the light field can be controlled by controlling the display pixels of different LCD screens.
  • the first image 9 and the second image 10 in FIG. 7 can be assumed to be two liquid crystal screens.
  • the first image 9 and the second image 10 play a role in the principle of compressing the liquid crystal.
  • the function of the screen is equivalent to setting two liquid crystal screens at two fixed positions, and the light passing through the two liquid crystal screens can modulate each other.
  • the first LCD screen (first image 9) displays an image
  • the second LCD screen (second image 10) functions as a pixel switch.
  • the switch and gray level of each pixel are set by the algorithm of the spatial light modulator. Determine, and then obtain the light path direction of each light, so as to form a specific light field.
  • the human eye directly observes and sees an image of two depths of field, which is a tomographic light field; if an algorithm is set between the two spatial light modulators, the spatial light modulation is performed.
  • the controller controls the brightness, darkness and gray level of each pixel to form a continuous compressed light field.
  • the depth of the compressed light scene is a range, not two fixed points, and the depth of field is wider.
  • the direction of the light is not unique.
  • a point on the front screen may correspond to two or more points on the back screen, which is equivalent to multi-purpose pixels.
  • the direction of light is not unique.
  • the depth of field depth of the light field is not deep enough.
  • the three-point and one-line determination of the direction of the light is more accurate. After the light is uniquely determined through the points on each screen, an infinite depth of field can be modulated. Since the number of pixels is limited in practical applications, a three-layer screen cannot uniquely determine all light directions, so the more screens (imaging numbers), the better the modulation effect.
  • Each layer screen corresponds to a spatial light modulator, and a multilayer screen (multiple images) needs to be provided with multiple spatial light modulators.
  • each spatial light modulator cooperates with each other, and the reflected modulated light continuously changes to form a dynamically changing image.
  • the augmented reality glasses 200 include a frame 201 and a lens 202, and the lens 202 is provided with the holographic optical element 1 of any of the embodiments described above.
  • the holographic optical element 1 is light, thin, and transparent, and can be directly applied to the lens 202.
  • the operation is simple and convenient, and the holographic optical element 1 can realize simultaneous modulation of multi-depth-of-field images. Therefore, the holographic optical element 1 presents its modulated multi-depth-of-field image.
  • the external ambient light can also enter the human eye through the holographic optical element 1, thereby merging with the multi-depth-of-field image and presenting richer image information.
  • the augmented reality glasses 200 further include a detection light transmitter 203 and a spatial light modulator 204, both of which are arranged on the frame 201, and can be connected by snap-fit, paste connection or fixed connection. Way to connect.
  • the positions and angles set by the detection light emitter 203 and the spatial light modulator 204 are set according to the actual directions and angles required by the light rays they emit.

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Abstract

一种全息光学元件及其制作方法、像重建方法、增强现实眼镜。该全息光学元件（1）包括基材（101）及记录材料层（102），记录材料层（102）中记录有至少两组干涉条纹，每组干涉条纹包括第一干涉条纹和第二干涉条纹；第一干涉条纹由分别从记录材料层（102）两侧入射的第一信号光（3）和第一参考光（5）形成；第二干涉条纹由分别从记录材料层（102）两侧入射的第二信号光（4）和第二参考光（6）形成，且第二信号光（4）在入射前经过透镜（2，2'）；第一信号光（3）的入射角与第二参考光(6)的入射角相等；各组干涉条纹对应的第一信号光（3）的入射方向各不相同，且各组干涉条纹对应的第二信号光（4）在入射前所经过的透镜（2，2'）的焦距各不相等。利用上述方法制作和进行像重建的全息光学元件可以成多个景深的像。

Description

全息光学元件及其制作方法、像重建方法、增强现实眼镜
本申请要求于2018年5月31日递交的中国专利申请第201810549783.7号的优先权，在此全文引用上述中国专利申请公开的内容以作为本申请的一部分。
技术领域
本公开的实施例涉及全息光学元件及其制作方法、像重建方法、增强现实眼镜。
背景技术
全息光学元件(Holographic Optical Elements，HOE)是根据全息术原理制成的光学元件，通常制作在感光薄膜材料上。全息光学元件基于衍射原理，是一种衍射光学元件。所谓全息术是指在照相胶片或干板上通过记录光波的振幅和位相分布并再现物体三维图像的技术。普通照相只能记录物体反射或透射光的振幅(强度)，所以记录的是物体的二维图像。全息术不仅可记录光的振幅，还可记录其位相。照明物体的反射光波承载着物体形态的信息传播，用记录介质把携带信息的光波波前记录下来，将可在另一时间和场所，采用适当方法把波前再现出来，从而可观察到物体的三维图像。
景深是指在摄影机镜头或其他成像器前沿能够取得清晰图像的成像所测定的被摄物体前后的距离范围。随着全息光学元件的发展以及用户端对图像景深需求的增加，显示领域对于具有多景深的全息光学元件的研究越来越受到关注。
发明内容
本公开的至少一个实施例提供了一种全息光学元件，包括基材，及设置于所述基材上的记录材料层，所述记录材料层中记录有至少两组干涉条纹，每组所述干涉条纹包括第一干涉条纹和第二干涉条纹；所述第一干涉条纹由分别从所述记录材料层两侧入射的第一信号光和第一参考光形成；所述第二 干涉条纹由分别从所述记录材料层两侧入射的第二信号光和第二参考光形成，且所述第二信号光在入射前经过透镜；所述第一信号光的入射角与所述第二参考光的入射角相等；各组所述干涉条纹对应的第一信号光的入射方向各不相同，且各组所述干涉条纹对应的第二信号光在入射前所经过的透镜的焦距各不相等。
本公开的至少一个实施例还提供了一种全息光学元件的制作方法，包括：在基材上形成记录材料层，以及在所述记录材料层中制作至少两组干涉条纹其中，每组所述干涉条纹包括第一干涉条纹和第二干涉条纹。制作每组所述干涉条纹，包括：采用第一信号光与第一参考光分别从所述基材的两侧照射所述记录材料层,在所述记录材料层中记录第一干涉条纹；在所述基材一侧放置透镜，采用第二信号光和第二参考光分别从所述基材的两侧照射所述记录材料层，且所述第二信号光与所述透镜处于所述基材的同一侧，在所述记录材料层中记录第二干涉条纹。制作每组所述干涉条纹时，所述第一信号光的入射角与所述第二参考光的入射角角度相等；制作不同组所述干涉条纹时，采用入射方向不同的第一信号光，且采用焦距不同的透镜。
本公开的至少一个实施例还提供了一种全息光学元件的像重建方法，应用于如上所述的全息光学元件，所述像重建方法包括：采用探测光分别照射所述全息光学元件的至少两组干涉条纹每一组，以建立至少两种景深的像，其中，每组所述干涉条纹包括第一干涉条纹和第二干涉条纹。采用所述探测光照射每组所述干涉条纹包括：在所述全息光学元件的一侧设置空间光调制器，该空间光调制器处于形成所述全息光学元件的第一干涉条纹的第一信号光光路的延长线上；采用探测光沿第一参考光的入射方向照射所述第一干涉条纹，所述探测光与所述空间光调制器处于所述全息光学元件的同侧，使所述探测光经所述第一干涉条纹衍射至所述空间光调制器；利用所述空间光调制器对所述探测光的衍射光进行调制，并使调制得到的调制光沿形成所述全息光学元件的第二干涉条纹的第二参考光的入射方向返回至所述全息光学元件，使所述调制光经所述第二干涉条纹衍射至形成所述第二干涉条纹的第二信号光光路的延长线上。所述探测光为所述第一信号光的相干光，所述调制光为所述第二信号光的相干光。
本公开的至少一个实施例还提供了一种增强现实眼镜，包括镜镜片，所 述镜片上设置有上述实施例的全息光学元件。
附图说明
为了更清楚地说明本发明实施例的技术方案，下面将对实施例的附图作简单地介绍，显而易见地，下面描述中的附图仅仅涉及本发明的一些实施例，而非对本发明的限制。
图1A为本公开至少一个实施例所提供的全息光学元件制作方法的一组干涉条纹中第一干涉条纹的制作方法示意图。
图1B为本公开至少一个实施例所提供的全息光学元件的结构示意图。
图2为图1所示的一组干涉条纹中第二干涉条纹的制作方法示意图。
图3为本公开至少一个实施例所提供的全息光学元件制作方法的另一组干涉条纹中第一干涉条纹的制作方法示意图。
图4为图3所示的另一组干涉条纹中第二干涉条纹的制作方法示意图。
图5为图1和图2所示的一组干涉条纹的像重建方法示意图。
图6为图3和图4所示的另一组干涉条纹的像重建方法示意图。
图7为图5和图6中像重建后的景深示意图。
图8为压缩光场原理示意图。
图9A为本公开至少一实施例提供的增强现实眼镜的示意图。
图9B为本公开至少一实施例提供的增强现实眼镜的框图。
具体实施方式
为使本发明实施例的目的、技术方案和优点更加清楚，下面将结合本发明实施例的附图，对本发明实施例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的一部分实施例，而不是全部的实施例。基于所描述的本发明的实施例，本领域普通技术人员在无需创造性劳动的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。
除非另作定义，此处使用的技术术语或者科学术语应当为本发明所属领域内具有一般技能的人士所理解的通常意义。本公开中使用的“第一”、“第二”以及类似的词语并不表示任何顺序、数量或者重要性，而只是用来区分不同的组成部分。同样，“包括”或者“包含”等类似的词语意指出现该词 前面的元件或者物件涵盖出现在该词后面列举的元件或者物件及其等同，而不排除其他元件或者物件。“连接”或者“相连”等类似的词语并非限定于物理的或者机械的连接，而是可以包括电性的连接，不管是直接的还是间接的。“上”、“下”、“左”、“右”等仅用于表示相对位置关系，当被描述对象的绝对位置改变后，则该相对位置关系也可能相应地改变。
本公开的一些实施例提供了一种全息光学元件，包括基材及设置于基材上的记录材料层，记录材料层中记录有至少两组干涉条纹，每组干涉条纹包括第一干涉条纹和第二干涉条纹。第一干涉条纹由分别从所述记录材料层两侧入射的第一信号光和第一参考光形成；第二干涉条纹由分别从所述记录材料层两侧入射的第二信号光和第二参考光形成，且第二信号光在入射前经过透镜；第一信号光的入射角与所述第二参考光的入射角相等；各组干涉条纹对应的第一信号光的入射方向各不相同，且各组干涉条纹对应的第二信号光在入射前所经过的透镜的焦距各不相等。
上述全息光学元件上记录的每一组干涉条纹都可以成一种景深的像，具备多组干涉条纹的全息光学元件可以成多景深的像。
并且，形成第一干涉条纹的过程相当于制作特定角度反射镜的过程，通过设计第一信号光和第一参考光的入射角度，可以使探测光经第一干涉条纹定向衍射至特定的方向，从而使全息光学元件具备定向反射功能。
另外，形成第二干涉条纹的过程中利用了透镜具有焦点的性质，使成像的位置处于固定位置，人眼只有在与焦距有关的特定位置才可以观察到像，使全息光学元件具备了透镜功能。
此外，上述全息光学元件中记录不同入射角度信号光的干涉条纹，可以呈现多个角度信号光对应的像，实现全息光学元件的多角度复用；且不同入射角度信号光的干涉条纹储存于同一全息光学元件中，可以有效地增大全息光学元件存储波前信息的容量，提高存储密度。
另一方面，上述全息光学元件还具有透明、体积小、厚度薄的优点，可以贴敷于增强现实眼镜，用于增强现实眼镜时环境光可以透过全息光学元件进入人眼与不同景深图像融合，形成丰富的视觉体验。
在至少一个实施例中，请参阅图1A和图1B，该全息光学元件1成片状，该全息光学元件1包括基材101及设置于基材101上的记录材料层102。该 基材101为透明基板或透明基膜，例如由玻璃或塑料材料制备。记录材料层102中记录有至少两组干涉条纹，每组干涉条纹包括第一干涉条纹和第二干涉条纹。
第一干涉条纹由分别从记录材料层两侧入射的第一信号光3和第一参考光5形成；请参阅图2，第二干涉条纹由分别从记录材料层两侧入射的第二信号光4和第二参考光6形成，且第二信号光4在入射前经过透镜2。第一信号光3的入射角θ 1与第二参考光6的入射角θ 1”相等。
注意，各组干涉条纹对应的第一信号光3的入射方向各不相同，且各组干涉条纹对应的第二信号光4在入射前所经过的透镜2的焦距各不相等。
需要说明的是，本公开中，入射角指入射光线与入射表面法线(如图1中垂直于全息光学元件1表面的虚线所示)的夹角。因此，入射方向不同的两束光线其入射角可能相同，例如两束入射光线从入射表面法线的两侧对称入射，其入射角相等。
还需要说明的是，第一信号光3、第一参考光5、第二信号光4和第二参考光6为平面波。第一参考光5为第一信号光3的相干光，例如，第一参考光5和第一信号光3均为激光，例如二者来自同一第一光源(未示出)激光光束并由分光镜分解得到。第二参考光6为第二信号光4的相干光，第二参考光6和第二信号光4均为激光，例如二者来自同一第二光源(未示出)激光光束并由分光镜分解得到。该第一光源与第二光源相同或不同。
示例性的，请参阅图1A，对于第一组干涉条纹，第一信号光3以θ 1的角度从全息光学元件1的记录材料层的左侧入射，第一参考光5以θ 1’的角度从全息光学元件1的记录材料层的右侧入射，第一信号光3和第一参考光5发生在记录材料层所在的平面内(例如根据设计在记录材料层的中心平面)干涉，由此全息光学元件1的记录材料层中记录下第一干涉条纹。
请参阅图2，第二信号光4从全息光学元件1的左侧入射，且入射前经过焦距为F1的透镜2，第二参考光6以θ 1”的角度从全息光学元件1的右侧入射，第二信号光4和第二参考光6发生在记录材料层所在的平面内(例如根据设计在记录材料层的中心平面)干涉，由此全息光学元件1的记录材料层中记录下第二干涉条纹。
经过上述两个操作，由此可以形成具有一组干涉条纹的全息光学元件1。 在其他一些实施例中，对于第二组干涉条纹，改变第一信号光3、第一参考光5和第二参考光6的入射角度，改变透镜的焦距，例如采用焦距不同于F1的透镜，继续重复上述步骤形成第二组干涉条纹的第一干涉条纹和第二干涉条纹。以此类推，通过改变光束的角度和透镜的焦距，可以在同一全息光学元件1上形成多组干涉条纹。
一种全息成像技术通过编程计算机算法或者通过变焦距实现多景深成像，例如调整液晶棱镜中的电压实现变焦进而成多景深的像。本公开的各个实施例中，全息光学元件1上记录的每一组干涉条纹都可以成一种景深的像，具备多组干涉条纹的全息光学元件1可以成多景深的像，成像方法简单易操作，成本较低。
并且，在本公开的一些实施例中，形成第一干涉条纹的过程相当于制作特定角度反射镜的过程。通过设计第一信号光3和第一参考光5的入射角度，可以使探测光经第一干涉条纹定向衍射至特定的方向，从而使全息光学元件1具备定向反射功能。形成第二干涉条纹的过程中利用了透镜2具有焦点的性质，使成像的位置处于固定位置，人眼只有在与焦距有关的特定位置才可以观察到像，使全息光学元件1具备了透镜2功能。因此，本公开的上述实施例在一个全息光学元件1中集成了多种光学元件的功能，更具有实用性。
另外，本公开的各个实施例的全息光学元件1中记录不同入射角度信号光的干涉条纹，可以呈现多个角度信号光对应的像，实现全息光学元件1的多角度复用；且不同入射角度信号光的干涉条纹储存于同一全息光学元件1中，可以有效地增大全息光学元件1存储波前信息的容量，提高存储密度。
此外，本公开一些实施例的全息光学元件1还具有透明、体积小、厚度薄的优点。本公开一些实施例在一个全息光学元件1薄膜里集成多种光学元件的功能，而上述另一种全息光学技术是通过具有一定厚度的元件(如液晶棱镜)实现多种光学元件功能的集成。与该另一种全息光学技术相比，本公开一些实施例的全息光学元件1厚度薄、透明度高，可以贴敷于增强现实眼镜，用于增强现实眼镜时环境光可以透过全息光学元件1进入人眼与不同景深图像融合，形成丰富的视觉体验。
在本公开一些实施例中，记录材料层的形成材料包括感光树脂、卤化银和重铬酸明胶中的至少一种。
本公开的一些实施例还提供了一种全息光学元件的制作方法，用于制作上述实施例中的全息光学元件1。该全息光学元件1的制作方法，包括在基材上形成记录材料层的步骤，并且还包括在记录材料层中制作至少两组干涉条纹的步骤。
该在记录材料层中制作至少两组干涉条纹中每一组的步骤包括：采用第一信号光3与第一参考光5分别从基材的两侧照射记录材料层，使得第一信号光3与第一参考光5在记录材料层中发生干涉，在记录材料层中记录第一干涉条纹；在基材一侧放置透镜2，采用第二信号光4和第二参考光6分别从基材的两侧照射记录材料层，且第二信号光4与透镜2处于基材的同一侧，使得第二信号光4和第二参考光6在记录材料层中发生干涉，在记录材料层中记录第二干涉条纹。制作每组干涉条纹时，第一信号光3的入射角与第二参考光6的入射角角度相等；制作不同组干涉条纹时，采用入射方向不同的第一信号光3，且采用焦距不同的透镜2。
需要说明的是，上述制作过程中，第一信号光3、第一参考光5、第二信号光4和第二参考光6为平面波，第一参考光5为第一信号光3的相干光，第二参考光6为第二信号光4的相干光。
另外，在制作第二干涉条纹时加入透镜2的作用是，利用透镜2具有焦点的功能，使光线通过全息光学元件1后成像的位置处于特定位置，观察者只有在该特定位置才可以观察到像。采用透镜2参数不同，全息光学元件1成像的位置就不同，从而实现多景深成像功能。多组干涉条纹制作过程中采用的透镜2种类相同，焦距不同，大小等其他规格可以相同或不同。
采用上述方法制作全息光学元件1所能产生的有益效果与本公开的一些实施例中所述的全息光学元件1的有益效果相同，此处不再赘述。
在本公开的一些实施例中，第二信号光4的入射角度根据观察者观察图像时眼睛相对于全息光学元件1的位置及视角确定。例如，观察者观察图像时，眼睛正对全息光学元件1的中心，视角为零，此时设置第二信号光4的入射方向与基材平面相垂直，可使成像位置位于观察者观察的方向；又例如，观察者眼睛位于全息光学元件1基材平面的右侧上方，设置第二信号光4从全息光学元件1基材平面的左侧下方入射，可以使观察者顺利观察到成像。
下面以观察者观察图像时眼睛正对全息光学元件1的中心为例，详细说 明全息光学元件1的制作方法。
制作第一组干涉条纹时的操作包括对第一干涉条纹进行制作的步骤。请参阅图1A，第一信号光3以θ 1的角度从全息光学元件1的记录材料层的左侧入射，同时第一参考光5以θ 1’的角度从全息光学元件1的记录材料层的右侧入射，全息光学元件1的记录材料层中记录下第一干涉条纹。
制作第一组干涉条纹时的操作还包括对第二干涉条纹进行制作的步骤，请参阅图2，在全息光学元件1的基材左侧放置焦距为F1的透镜2，采用第二信号光4从透镜2的左侧照射记录材料层，由于观察者观察图像时眼睛正对全息光学元件1的中心，第二信号光4延图2中的水平方向(全息光学元件1的法线方向)入射；同时采用第二参考光6以θ 1”的角度从基材的右侧照射记录材料层，即可在记录材料层中记录第二干涉条纹。这里，第一信号光3的入射角θ 1与第二参考光6的入射角θ 1”角度相等。
制作第二组干涉条纹时的操作同样包括对第一干涉条纹的制作。请参阅图3，第一信号光3以θ 2的角度从全息光学元件1的记录材料层的左侧入射，同时第一参考光5以θ 2’的角度从全息光学元件1的记录材料层的右侧入射，全息光学元件1的记录材料层中记录下第二组干涉条纹的第一干涉条纹。对第二干涉条纹进行制作的步骤，请参阅图4，在全息光学元件1的基材左侧放置焦距为F2(例如，不同于焦距F1)的透镜2’，采用第二信号光4从透镜2’的左侧延水平方向照射记录材料层，同时采用第二参考光6以θ 2”的角度从基材的右侧照射记录材料层，即可在记录材料层中记录第二组干涉条纹的第二干涉条纹。这里，第一信号光3的入射角θ 2与第二参考光6的入射角θ 2”角度相等。
在本公开的一些实施例中，在制作第一、二组干涉条纹的过程中，两个第一信号光3的入射角可以采用不对称的设计，即θ 1＝θ 1”，θ 2＝θ 2”，且θ 1≠θ 2；也可以采用对称设计，即θ 1＝θ 1”＝θ 2＝θ 2”，两个第一信号光3以同样的入射角大小入射，但是方向不同。
采用上述方法，改变第一信号光3的入射方向，相应的第一参考光5、第二参考光6入射角也随之改变，同时采用不同焦距的透镜(即不同于之前的透镜2和透镜2’)，可以制作多组干涉条纹(例如3组、4组干涉条纹等，或更多组干涉条纹)，形成多景深的像。
在本公开的一些实施例中，不同组干涉条纹的第二参考光6的入射角度差大于或等于0.5°。由于不同组干涉条纹之间具有角度依存性，不同角度全息衍射互不影响，但角度不宜过于相近。如果角度过近，干涉条纹之间发生微小的衍射，容易形成“鬼影”，影响成像质量，并且实际应用时在参考光发射器需要多个的情况下，发射器之间的安装空间受到限制，角度过于接近会导致发射器无法安装，影响成像效果。
在本公开的一些实施例中，上述透镜2和上述透镜2’的种类包括凸透镜、凹透镜和菲涅尔透镜中的至少一种，或至少两种的任意组合等，也即透镜2和透镜2’可以为组合透镜(透镜组)。制作全息光学元件1过程中使用的透镜2和透镜2’的种类不同，则像重建后成像种类不同，应用时可根据实际成像需要选择透镜2和透镜2’的种类。
例如，采用凸透镜，成多景深实像，成像观察位置与凸透镜处于全息光学元件1的异侧，多组不同焦距的凸透镜成多景深的像，且凸透镜焦距越大，成像位置距离全息光学元件1越远。例如，采用凹透镜，成多景深虚像，成像观察位置与凹透镜处于全息光学元件1的同侧，呈现的是放大的虚像，各组像存在放大倍率之间的差异。菲涅尔透镜相当于多焦点的凸透镜2，例如，采用菲涅尔透镜成一个主像和多个副像，且成缩小的多景深实像。
在本公开的一些实施例中，选用的透镜2和透镜2’的面积等于或大于基材的面积，这样便于在整个基材上记录干涉条纹，增大全息光学元件1可视场的面积。
在本公开的一些实施例中，透镜2和透镜2’贴近基材设置，透镜2和透镜2’与基材之间的间距为0～5cm。透镜2和透镜2’与基材的距离如果太远，第一干涉条纹的成像与第二干涉条纹的成像就会不在一个平面，容易产生相差。理想状况下，透镜2和透镜2’如果与元件基材合为一体，这使基材实现透镜2和透镜2’的功能，实际操作时，透镜2和透镜2’可以尽量贴近基材，不易产生相差。
本公开的一些实施例还提供了一种全息光学元件的像重建方法，应用于如上所述方法制作的全息光学元件1。该像重建方法包括采用探测光分别照射全息光学元件1的至少两组干涉条纹以建立至少两种景深的像的步骤，每组干涉条纹包括第一干涉条纹和第二干涉条纹，采用探测光照射每组干涉条 纹的步骤包括如下操作。
在全息光学元件1的一侧设置空间光调制器(Spatial Light Modulator，简称SLM)，该空间光调制器处于形成全息光学元件1的第一干涉条纹的第一信号光3光路的延长线上；采用探测光沿第一参考光5的入射方向照射第一干涉条纹，探测光与空间光调制器处于全息光学元件1的同侧，使探测光经第一干涉条纹衍射至空间光调制器；利用空间光调制器对探测光的衍射光进行调制，并使调制得到的调制光沿形成全息光学元件1的第二干涉条纹的第二参考光6的入射方向返回至全息光学元件1，使调制光经第二干涉条纹衍射至形成第二干涉条纹的第二信号光4光路的延长线上。这里，探测光为第一信号光3的相干光，调制光为第二信号光4的相干光。
采用上述方法对全息光学元件1进行像重建所能产生的有益效果与本公开的一些实施例中所述的全息光学元件1的有益效果相同，此处不再赘述。
下面以观察者观察图像时眼睛正对全息光学元件1的中心，且成像为两种景深的像为例，详细说明按照上述实施例制作的全息光学元件1的像重建方法。
请参阅图5，第一种景深的像成像时，利用第一组干涉条纹进行成像。在全息光学元件1的右侧设置第一空间光调制器SLM1，该第一空间光调制器SLM1处于形成第一组干涉条纹的第一干涉条纹的第一信号光3光路的延长线上。在全息光学元件1的右侧，采用第一探测光7沿第一参考光5的入射方向照射第一干涉条纹，入射角为θ 1’，使第一探测光7经第一干涉条纹衍射至第一空间光调制器SLM1。利用第一空间光调制器SLM1对第一探测光7的衍射光进行调制，例如对光进行振幅、相位的调制，也可以对每个像素反射多少光进行调制，即调整每个像素的灰阶，从而使出射光呈现不同的像。对第一探测光7的衍射光进行调制后得到第一调制光，第一调制光沿形成第一组干涉条纹的第二干涉条纹的第二参考光6的入射方向(与第一探测光7的衍射光光路方向相反)返回至全息光学元件1，即第一调制光的入射角为θ 1”，使第一调制光经第二干涉条纹衍射至形成第二干涉条纹的第二信号光4光路的延长线上(衍射后的第一调制光延水平方向出射)。观察者眼睛处于正对全息光学元件1的中心的方向，可以观察到一种景深的图像，即第一像9。
请参阅图6，第二种景深的像成像时，利用第二组干涉条纹进行成像。在全息光学元件1的右侧设置第二空间光调制器SLM2，该第二空间光调制器SLM2处于形成第二组干涉条纹的第一干涉条纹的第一信号光3光路的延长线上。在全息光学元件1的右侧，采用第二探测光8沿第一参考光5的入射方向照射第一干涉条纹，入射角为θ 2’，使第二探测光8经第一干涉条纹衍射至第二空间光调制器SLM2。利用第二空间光调制器SLM2对第二探测光8的衍射光进行调制，并使调制得到的第二调制光沿形成第二组干涉条纹的第二干涉条纹的第二参考光6的入射方向(与第二探测光8的衍射光光路方向相反)返回至全息光学元件1，即第二调制光的入射角为θ 2”，使第二调制光经第二干涉条纹衍射至形成第二干涉条纹的第二信号光4光路的延长线上(衍射后的第二调制光延水平方向出射)。观察者眼睛处于正对全息光学元件1的中心的方向，可以观察到另一种景深的图像，即第二像10。
第一像9与第二像10的成像远近关系，与制作全息光学元件1时使用的透镜2和透镜2’的焦距有关。例如，制作全息光学元件1时使用的透镜2和透镜2’的焦距F1＞F2，则如图7所示，第一像9的成像位置与全息光学元件1之间的距离大于第二像10的成像位置与全息光学元件1之间的距离。
在本公开一些实施例中，空间光调制器包括振幅型空间光调制器或相位型空间光调制器。如果空间光调制器选用振幅型调制器，例如数字微镜(DMD)，可以成固定景深的像，如图7中的第一像9和第二像10。如果空间光调制器选用相位型空间光调制器(可改变相位的空间光调制器)，如LCOS(Liquid Crystal on Silicon，液晶附硅)调制器，相位变化会对图像产生影响，呈现的像是复杂的、变景深、图像改变的像。当需要呈现可动态调整的图像时，可选用相位型空间光调制器。
在本公开的一些实施例中，全息光学元件的像重建方法还包括：采用多个空间光调制器，重复上述像重建的步骤，形成多束调制光。不同束调制光对不同景深的像进行调制，且使多束调制光的光强满足压缩光场光强调制关系，以形成光场增强现实。
所谓光场，就是指光在每一个方向通过每一个点的光量。使用光场技术，可以起到基于距离对物体进行聚焦的效果。普通的增强现实(AR)透过镜片只能呈现平面图像或单一景深的图像，光场增强现实技术可以呈现至少两个 景深的图像。
按照如上所述的步骤进行全息光学元件的制作和像重建之后，呈现出的如图7所示的图像景深是固定的景深；如果形成光场增强现实，通过人眼观察调制的光场时，所感觉到的景深比图7中所示的景深要大，与图7中的景深相比，压缩光场景深是一个连续的范围，不是两个固定的点，景深更广。因此，形成光场增强现实，观察者可观察到连续景深的像，视觉感觉景深更广，提升用户体验。
压缩光场的原理请参阅图8。如图8所示，光场系统通常设置背光层12、偏振层11和多个液晶屏幕，使用液晶屏幕作为多层光场显示的空间光调制单元，它可以通过层与层之间对应像素甚至亚像素位置的灰度值来调制入射光线(来自于背光层12)的光强，每层液晶屏幕对应像素的灰度值决定了光强传输率。请参阅图8，α 1，α 2，β 1分别为液晶屏幕层A 13和液晶屏幕层B14的像素位置，假设有两束光线穿过液晶屏幕层A 13和液晶屏幕层B 14，这两束光线的输出光强可以表示成
I out(α 1,β 1)＝I in×T A(α 1)×T B(β 1)
I out(α 2,β 1)＝I in×T A(α 2)×T B(β 1)
其中，T A(α 1)和T A(α 2)分别表示液晶屏幕层A 13在α 1和α 2位置的光强传输率，同样的，T B(β 1)表示在β 1位置的光强传输率，因此两束光线具有不同的光强。基于这一模型，虽然不同的光线会经过某一液晶屏的相同像素，但是它们必将经过相隔一定距离的另一层屏幕的不同像素，并因此实现了不同光场强度信息。根据这一原理，可以利用控制不同液晶屏的显示像素来实现光场的调控。
对应到本公开的一些实施例中，图7中的第一像9和第二像10，可以假设为两个液晶屏，第一像9和第二像10起到了压缩光场的原理中液晶屏的作用，相当于在两个固定的位置设置两个液晶屏，穿过两个液晶屏的光可以互相调制。第一个液晶屏(第一像9)显示了一个图像，第二个液晶屏(第二像10)起到像素开关的作用，每个像素的开关和灰度通过空间光调制器的算法设定，进而获得每条光线的光路方向，从而形成一个特定的光场。如果后期不对空间光调制器设置任何算法，人眼直接观察，看到的是两个景深的像，是一个断层的光场；如果两个空间光调制器之间设置了算法，通过空间光调 制器控制每个像素的亮暗和灰度，就可以形成一个连续的压缩光场，压缩光场景深是一个范围，不是两个固定的点，景深更广。
穿过两个液晶屏(两个像)的光在调制的时候，光线方向不是唯一确定的，前面屏上的一个点，可能对应后面屏上的两个点或多个点，相当于像素多用，光线的方向不是唯一的。在光线方向不唯一确定的情况下，光场的景深深度就不够深。三层屏(三个像)时，三点一线对光线方向的确定情况更加准确，光线通过每一层屏上的点唯一确定之后，就可以调制出无穷大的景深。实际应用中由于像素数量是有限的，三层屏也不能唯一确定所有的光线方向，所以屏数(成像数)越多，调制的效果越好。每一层屏(每个像)对应设置一个空间光调制器，多层屏(多个像)就需要设置多个空间光调制器。形成压缩光场的过程中每个空间光调制器互相配合，反射的调制光不断变化，就可以形成一个动态变化的图像。
本公开的一些实施例还提供了一种增强现实眼镜，参见图9A，该增强现实眼镜200包括镜框201和镜片202，镜片202上设置如上所述任一实施例的全息光学元件1。上述全息光学元件1轻薄、透明，可以直接贴敷于镜片202上，操作简单方便，并且上述全息光学元件1可实现多景深图像同时调制，因此全息光学元件1在呈现其调制的多景深图像的同时，外界环境光也可以透过全息光学元件1进入人眼，从而与多景深图像融合，呈现出更丰富的图像信息。
在一些实施例中，参见图9B，增强现实眼镜200还包括探测光发射器203和空间光调制器204，二者设置在镜框上201，可以通过卡扣连接、粘贴连接或固定连接等可行的方式连接。探测光发射器203和空间光调制器204设置的位置和角度根据其出射光线所需的实际方向和角度设置。
以上所述仅是本公开的示范性实施方式，而非用于限制本发明的保护范围，本公开的保护范围由所附的权利要求确定。

Claims (14)

  1. 一种全息光学元件，包括：基材及设置于所述基材上的记录材料层，其中，所述记录材料层中记录有至少两组干涉条纹，每组所述干涉条纹包括第一干涉条纹和第二干涉条纹；
    所述第一干涉条纹由分别从所述记录材料层两侧入射的第一信号光和第一参考光形成；
    所述第二干涉条纹由分别从所述记录材料层两侧入射的第二信号光和第二参考光形成，且所述第二信号光在入射前经过透镜；
    所述第一信号光的入射角与所述第二参考光的入射角相等；
    各组所述干涉条纹对应的第一信号光的入射方向各不相同，且各组所述干涉条纹对应的第二信号光在入射前所经过的透镜的焦距各不相等。
  2. 根据权利要求1所述的全息光学元件，其中，所述记录材料层的形成材料包括选自感光树脂、卤化银和重铬酸明胶构成的组中的至少一种。
  3. 一种全息光学元件的制作方法，包括：
    在基材上形成记录材料层，以及
    在所述记录材料层中制作至少两组干涉条纹，其中，每组所述干涉条纹包括第一干涉条纹和第二干涉条纹，制作每组所述干涉条纹包括：
    采用第一信号光与第一参考光分别从所述基材的两侧照射所述记录材料层,在所述记录材料层中记录所述第一干涉条纹；
    在所述基材一侧放置透镜，采用第二信号光和第二参考光分别从所述基材的两侧照射所述记录材料层，且所述第二信号光与所述透镜处于所述基材的同一侧，在所述记录材料层中记录所述第二干涉条纹；
    其中，制作每组所述干涉条纹时，所述第一信号光的入射角与所述第二参考光的入射角角度相等；
    制作不同组所述干涉条纹时，采用入射方向不同的第一信号光，且采用焦距不同的透镜。
  4. 根据权利要求3所述的全息光学元件的制作方法，其中，所述第二信号光的入射角度根据观察者观察图像时眼睛相对于全息光学元件的位置及视角确定。
  5. 根据权利要求4所述的全息光学元件的制作方法，其中，观察者眼睛正对全息光学元件中心，所述第二信号光的入射方向与基材平面相垂直。
  6. 根据权利要求3所述的全息光学元件的制作方法，其中，不同组第二参考光的入射角度差大于或等于0.5°。
  7. 根据权利要求3所述的全息光学元件的制作方法，其中，所述透镜包括选自由凸透镜、凹透镜和菲涅尔透镜构成的组中的至少一种。
  8. 根据权利要求3所述的全息光学元件的制作方法，其中，所述透镜的面积等于或大于所述基材的面积。
  9. 根据权利要求3所述的全息光学元件的制作方法，其中，所述透镜贴近所述基材设置，所述透镜与所述基材之间的间距为0～5cm。
  10. 一种全息光学元件的像重建方法，应用于如权利要求1所述的全息光学元件，所述像重建方法包括：
    采用探测光分别照射所述全息光学元件的至少两组干涉条纹每一组，以建立至少两种景深的像，其中，每组所述干涉条纹包括第一干涉条纹和第二干涉条纹，采用所述探测光照射每组所述干涉条纹包括：
    在所述全息光学元件的一侧设置空间光调制器，所述空间光调制器处于形成所述全息光学元件的所述第一干涉条纹的第一信号光光路的延长线上；
    采用所述探测光沿第一参考光的入射方向照射所述第一干涉条纹，所述探测光与所述空间光调制器处于所述全息光学元件的同侧，使所述探测光经所述第一干涉条纹衍射至所述空间光调制器；
    利用所述空间光调制器对所述探测光的衍射光进行调制，并使调制得到的调制光沿形成所述全息光学元件的所述第二干涉条纹的第二参考光的入射方向返回至所述全息光学元件，使所述调制光经所述第二干涉条纹衍射至形成所述第二干涉条纹的第二信号光光路的延长线上；
    其中，所述探测光为所述第一信号光的相干光，所述调制光为所述第二信号光的相干光。
  11. 根据权利要求10所述的全息光学元件的像重建方法，其中，所述空间光调制器包括振幅型空间光调制器或相位型空间光调制器。
  12. 根据权利要求10所述的全息光学元件的像重建方法，还包括：
    采用多个所述空间光调制器，重复如权利要求9所述的步骤，形成多束 调制光，不同束所述调制光对不同景深的像进行调制，且使多束所述调制光的光强满足压缩光场光强调制关系，以形成光场增强现实。
  13. 一种增强现实眼镜，包括镜片，其中，所述镜片上设置有如权利要求1所述的全息光学元件。
  14. 根据权利要求13所述的增强现实眼镜，还包括镜框、探测光发射器和空间光调制器，
    其中，所述探测光发射器和所述空间光调制器设置在所述镜框上。
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