WO2023122897A1 - 近眼显示装置和超表面透镜的构建方法 - Google Patents

近眼显示装置和超表面透镜的构建方法 Download PDF

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Publication number
WO2023122897A1
WO2023122897A1 PCT/CN2021/141731 CN2021141731W WO2023122897A1 WO 2023122897 A1 WO2023122897 A1 WO 2023122897A1 CN 2021141731 W CN2021141731 W CN 2021141731W WO 2023122897 A1 WO2023122897 A1 WO 2023122897A1
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Prior art keywords
lens
metasurface
metasurface lens
pixel
phase
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PCT/CN2021/141731
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English (en)
French (fr)
Inventor
彭玮婷
凌秋雨
王维
孟宪芹
梁蓬霞
吴谦
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京东方科技集团股份有限公司
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Application filed by 京东方科技集团股份有限公司 filed Critical 京东方科技集团股份有限公司
Priority to PCT/CN2021/141731 priority Critical patent/WO2023122897A1/zh
Priority to US18/274,473 priority patent/US20240094538A1/en
Priority to CN202180004223.3A priority patent/CN116670563A/zh
Publication of WO2023122897A1 publication Critical patent/WO2023122897A1/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
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/002—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of materials engineered to provide properties not available in nature, e.g. metamaterials
    • 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

Definitions

  • the present disclosure relates to but not limited to the field of display technology, and in particular relates to a near-eye display device and a construction method of a metasurface lens.
  • VR Virtual reality
  • AR Augmented Reality
  • VR Virtual reality
  • AR Augmented Reality
  • Near-eye display is a display technology that enables viewers to see clearly the content that is very close to the eyes.
  • the optical system is used to image the displayed content within the focus range of the eyes, so that the eyes can see the displayed content clearly.
  • an exemplary embodiment of the present disclosure provides a near-eye display device, including a substrate, a metasurface lens array disposed on a side of the substrate close to the eye, and a pixel island array located on the side of the substrate away from the eye, the The pixel island array includes a plurality of pixel islands, the metasurface lens array includes a plurality of metasurface lenses corresponding to the plurality of pixel islands one by one, the orthographic projection of the lens center of the metasurface lens on the substrate and The orthographic projections of the pixel center of the pixel island on the substrate overlap, the lens center is the geometric center of the metasurface lens, and the pixel center is the geometric center of the pixel island.
  • At least one metasurface lens has an imaging function and a light deflecting function, and the metasurface lens satisfies the following lens phase formula:
  • (x, y) are the coordinates of different position points on the described metasurface lens, and the geometric center of the described metasurface lens is the coordinate origin, Be the phase at the position point (x, y) on the metasurface lens, ⁇ is the wavelength of the incident light, f is the focal length of the metasurface lens, and ⁇ is the coordinate orientation of the pixel island corresponding to the metasurface lens angle, ⁇ is the light deflection angle required by the pixel island corresponding to the metasurface lens.
  • the plurality of pixel islands are configured to respectively display a part of images in a complete picture
  • the plurality of metasurface lenses are configured to modulate an optical path so that images of all the pixel islands are spliced into a complete picture.
  • the plurality of metasurface lenses have the same lens aperture and focal length.
  • the metasurface lens includes a plurality of metasurface units regularly arranged in a unit period, at least one metasurface unit includes a base and a column arranged on the base, and the refractive index of the base is The index is different from the refractive index of the cylinder.
  • a difference between a refractive index of the substrate and a refractive index of the pillar is greater than or equal to 0.5.
  • the material of the base includes silicon oxide
  • the material of the pillars includes silicon nitride
  • the height of the pillars is 500nm to 800nm.
  • the pillar is a cylinder, and the radius of the cylinder is 55 nm to 125 nm.
  • the unit period is 200nm to 300nm.
  • the exemplary embodiment of the present disclosure also provides a method for constructing a metasurface lens, including:
  • the lens structure database comprising a plurality of base phases and a plurality of metasurface units corresponding to the base phases;
  • the metasurface lens is constructed by using metasurface units in different regions on the metasurface lens.
  • the construction of the lens structure database includes:
  • the basic structure database includes a plurality of metasurface units whose phase information covers the range of 0 to 2 ⁇ ;
  • a plurality of metasurface units corresponding to the plurality of basic phases are selected from the basic structure database to form a lens structure database.
  • the phase acquisition of different positions on the metasurface lens includes:
  • (x, y) are the coordinates of different position points on the described metasurface lens, and the geometric center of the described metasurface lens is the coordinate origin, Be the phase at the position point (x, y) on the metasurface lens, ⁇ is the wavelength of the incident light, f is the focal length of the metasurface lens, and ⁇ is the coordinate orientation of the pixel island corresponding to the metasurface lens angle, ⁇ is the light deflection angle required by the pixel island corresponding to the metasurface lens.
  • said obtaining a plurality of basic phases according to a preset phase selection strategy includes:
  • the metasurface units at the positions of different regions on the metasurface lens are determined.
  • the construction of the metasurface lens using metasurface units at different regions on the metasurface lens includes: using the obtained metasurface units at different region locations on the metasurface lens Structural filling is performed at different regions to construct the metasurface lens.
  • 1 is a schematic structural view of a near-eye display device
  • Figure 2 is a schematic diagram of near-eye display
  • FIG. 3 is a schematic structural diagram of a near-eye display device according to an exemplary embodiment of the present disclosure
  • Figure 4a is a schematic diagram of the modulation effect when a metasurface lens expresses the lens phase
  • Figure 4b is a schematic diagram of the modulation effect when a metasurface lens expresses the phase of a deflection grating
  • Figure 4c is a schematic diagram of the modulation effect when a metasurface lens expresses the phase of the lens and the deflection grating;
  • FIG. 5 is a schematic structural diagram of a metasurface unit according to an exemplary embodiment of the present disclosure.
  • FIG. 6 is a schematic diagram of a lens structure database according to an exemplary embodiment of the present disclosure.
  • Fig. 7 is the phase diagram of different positions on the metasurface lens
  • Figure 8 is a schematic diagram of the discretized phase on the metasurface lens
  • FIG. 9 is a schematic diagram of a metasurface lens constructed by a metasurface unit
  • FIG. 10 is a schematic diagram of a metasurface lens array according to an exemplary embodiment of the present disclosure.
  • Fig. 11a to Fig. 11c are the schematic diagrams of phase and structure of a kind of 0° angle deflection metasurface lens
  • 12a to 12c are schematic diagrams of phase and structure of a 5.725° angle deflection metasurface lens
  • Figure 13a is an MTF curve of a geometric lens imaging in a 5.725° field of view
  • Figure 13b is the MTF curve of the metasurface lens imaging in the 5.725° field of view
  • Figure 14a is the MTF curve of a geometric lens imaging at 5.725°+5.725° field of view
  • Figure 14b is the MTF curve of the metasurface lens imaging in the field of view of 5.725°+5.725°;
  • Fig. 15a is a schematic diagram of the mosaic display effect of the metasurface lens array shown in Fig. 10;
  • Fig. 15b is a display luminance distribution curve diagram of the metasurface lens array shown in Fig. 10;
  • 16 is a schematic diagram of another metasurface lens array according to an exemplary embodiment of the present disclosure.
  • Fig. 17a is a schematic diagram of the mosaic display effect of the metasurface lens array shown in Fig. 16;
  • Fig. 17b is a display luminance distribution curve diagram of the metasurface lens array shown in Fig. 16;
  • FIG. 18 is a schematic diagram of yet another metasurface lens array according to an exemplary embodiment of the present disclosure.
  • 10 substrate
  • 20 microlens array
  • 30 pixel island array
  • the proportions of the drawings in the present disclosure can be used as a reference in the actual process, but are not limited thereto.
  • the width-to-length ratio of the channel, the thickness and spacing of each film layer, and the width and spacing of each signal line can be adjusted according to actual needs.
  • the number of pixels in the display substrate and the number of sub-pixels in each pixel are not limited to the numbers shown in the figure.
  • the figures described in the present disclosure are only structural schematic diagrams, and one mode of the present disclosure is not limited to the accompanying drawings. The shape or value shown in the figure, etc.
  • connection should be interpreted in a broad sense.
  • it may be a fixed connection, or a detachable connection, or an integral connection; it may be a mechanical connection, or an electrical connection; it may be a direct connection, or an indirect connection through an intermediate piece, or an internal communication between two components.
  • a transistor refers to an element including at least three terminals of a gate electrode, a drain electrode, and a source electrode.
  • a transistor has a channel region between a drain electrode (drain electrode terminal, drain region, or drain electrode) and a source electrode (source electrode terminal, source region, or source electrode), and current can flow through the drain electrode, the channel region, and the source electrode .
  • a channel region refers to a region through which current mainly flows.
  • the first electrode may be a drain electrode and the second electrode may be a source electrode, or the first electrode may be a source electrode and the second electrode may be a drain electrode.
  • the functions of the "source electrode” and “drain electrode” may be interchanged. Therefore, in this specification, “source electrode” and “drain electrode” can be interchanged with each other.
  • electrically connected includes the case where constituent elements are connected together through an element having some kind of electrical function.
  • the "element having some kind of electrical action” is not particularly limited as long as it can transmit and receive electrical signals between connected components.
  • Examples of “elements having some kind of electrical function” include not only electrodes and wiring but also switching elements such as transistors, resistors, inductors, capacitors, and other elements having various functions.
  • parallel refers to a state where the angle formed by two straight lines is -10° to 10°, and therefore includes a state where the angle is -5° to 5°.
  • perpendicular means a state in which the angle formed by two straight lines is 80° to 100°, and therefore also includes an angle of 85° to 95°.
  • film and “layer” are interchangeable.
  • conductive layer may sometimes be replaced with “conductive film”.
  • insulating film may sometimes be replaced with “insulating layer”.
  • the "same-layer arrangement" used refers to a structure formed by patterning two (or more than two) structures through the same patterning process, and their materials may be the same or different.
  • the materials of precursors forming multiple structures arranged in the same layer are the same, and the materials finally formed may be the same or different.
  • triangle, rectangle, trapezoid, pentagon, or hexagon in this specification are not strictly defined, and may be approximate triangles, rectangles, trapezoids, pentagons, or hexagons, etc., and there may be some small deformations caused by tolerances. There can be chamfers, arc edges, deformations, etc.
  • Fig. 1 is a schematic structural diagram of a near-eye display device, illustrating a mosaic imaging scheme using a combination of a microlens array and a pixel island array
  • Fig. 2 is a schematic diagram of a near-eye display.
  • the near-eye display device may include a microlens array 20 and a pixel island array 30 , and the microlens array 20 is disposed between the eye 100 and the pixel island array 30 .
  • the microlens array 20 may include a plurality of microlenses (microlenses 201 to 205), and the microlenses may be one or more of a geometric lens, a binary diffractive lens, and a holographic plane lens, The microlenses may have a diameter of 0.1 mm to 3 mm.
  • the pixel island array 30 may include a plurality of pixel islands (pixel island 301 to pixel island 305 ), and the pixel island 301 to pixel island 305 are arranged corresponding to the microlenses 201 to 205 . Each pixel island is equivalent to a tiny display screen, and may include multiple sub-pixels.
  • the light emitted by the multiple sub-pixels enters the eye 100 through the corresponding microlens, and forms an enlarged virtual image 200 at a certain depth of field in front of the eye 100 .
  • Multiple pixel islands can be arranged according to the viewing requirements of the eyes 100. For a complete picture to be viewed by the viewer, each pixel island only displays a part of the image in the complete picture. By designing the position arrangement of the pixel island and the microlens, it can The virtual images of all the pixel islands are formed at the same depth of field, and the virtual image 200 formed by the images of all the pixel islands can be spliced into a complete virtual image at the same depth of field to realize field of view splicing.
  • microlenses and pixel island sets For a subset of microlenses and pixel island sets (a subset includes multiple pixel islands), if they can all generate a beam of light at a certain angle (such as 0°), and these light rays can all enter the pupil of the eye, These light rays produce the same virtual image point for the eyes (such as the virtual image point at infinity corresponding to the 0° field of view).
  • the placement height since there is a certain distance between the microlens array 20 and the pixel island array 30 (called the placement height), it is necessary to set corresponding dislocations between the microlens and the corresponding pixel islands to achieve different angles of light emitted by different pixel islands. Deflection, stitched into a complete picture through off-axis imaging.
  • the maximum off-axis imaging angle of microlenses has a certain limit. For example, when the placement height is 10mm, the maximum off-axis imaging angle is about ⁇ 10°. Therefore, limited by the maximum off-axis imaging angle of a single microlens, the near-eye display device with the existing structure cannot achieve a larger viewing angle.
  • one technical solution is to use a curved substrate and use the curved angle of the curved substrate to increase the viewing angle.
  • the use of a curved substrate will not only increase the thickness of the near-eye display device, which is inconsistent with the development trend of light and thin.
  • the processing technology is complicated, the difficulty is great, and the production cost is high.
  • another technical solution is to add a holographic grating structure on the microlens to diffract and deflect the light after passing through the microlens.
  • a near-eye display device includes a substrate, a metasurface lens array disposed on the side of the substrate close to the eye, and a pixel island array disposed on the side of the substrate away from the eye, and the pixel island array includes a plurality of The pixel island, the metasurface lens array includes a plurality of metasurface lenses corresponding to the plurality of pixel islands, the orthographic projection of the lens center of the metasurface lens on the substrate is the same as the pixel of the pixel island Orthographic projections centered on the substrate overlap.
  • a lens center of the metasurface lens may be a geometric center of the metasurface lens
  • a pixel center of the pixel island may be a geometric center of the pixel island.
  • FIG. 3 is a schematic structural diagram of a near-eye display device according to an exemplary embodiment of the present disclosure.
  • the near-eye display device may include: a substrate 10 , a metasurface lens array 40 disposed on the side of the substrate 10 close to the eye 100 , and a pixel island array 30 disposed on the side of the substrate 10 away from the eye 100 .
  • the substrate 10 may be a carrier constructed of a transparent material, configured to carry the metasurface lens array 40 , and serve as a placement height H to achieve light transmission.
  • the pixel island array 30 can include a plurality of pixel islands (the first pixel island 31 to the seventh pixel island 37) arranged at intervals, and each pixel island can be equivalent to a tiny display screen, displaying a part of the image in the complete picture, more The picture displayed by each pixel island can be spliced into a complete picture by the human eye after the optical path is designed.
  • the metasurface lens array 40 may include a plurality of metasurface lenses (the first metasurface lens 41 to the seventh metasurface lens 47) arranged at intervals, each metasurface lens is configured to have imaging function and light deflection function simultaneously, the metasurface
  • the phase expressed by the lens is the phase of the imaging lens and the deflection phase required by the position of the corresponding pixel island, and the imaging of light rays with different deflection requirements without off-axis phase difference is performed.
  • the substrate 10 may be made of materials such as glass, ceramics, and quartz, or may be made of a silicon compound, such as silicon nitride Si 3 N 4 , or the like.
  • the substrate may be made of a light transparent material, such as polymethyl methacrylate (PMMA), also known as acrylic or plexiglass.
  • PMMA polymethyl methacrylate
  • Each pixel island may include multiple pixels of the same color (one pixel includes at least one sub-pixel), forming a pixel cluster, which is equivalent to a tiny display screen composed of pixel clusters.
  • the space between the pixel islands serves as a transparent area for the near-eye display for the entry of external light.
  • the pixel island may be a self-luminous display, or may be a non-self-luminous display including a backlight module.
  • the pixel island may include any one or more of the following: liquid crystal display (Liquid Crystal Display, LCD for short), organic light emitting diode display (Organic Light Emitting Diode, OLED for short), light emitting diode display (Light Emitting Diode, LED for short), Inorganic electroluminescence display (Electro Luminescent display, referred to as EL), field emission display (Field Emission Display, referred to as FED), surface conduction electron emission display (Surface-conduction Electron-emitter Display, referred to as SED), plasma display (Plasma Display Panel, referred to as PDP), electrophoretic display (Electro Phoretic Display, referred to as EPD).
  • liquid crystal display Liquid Crystal Display, LCD for short
  • organic light emitting diode display Organic Light Emitting Diode, OLED for short
  • the metasurface lens may have a lens center, which may be a geometric center of the metasurface lens.
  • the pixel island may have a pixel center, which may be the geometric center of the pixel island.
  • the plurality of pixel islands may include a first pixel island 31, a second pixel island 32, a third pixel island 33, a fourth pixel island 34, a fifth pixel island 35, a sixth pixel island 36, and a sixth pixel island.
  • a plurality of metasurface lenses may include a first metasurface lens 41 corresponding to the first pixel island 31, a second metasurface lens 42 corresponding to the second pixel island 32, and a metasurface lens 42 corresponding to the third pixel island 33.
  • the orthographic projection of the lens center of the metasurface lens on the substrate 10 substantially overlaps the orthographic projection of the pixel center of the pixel island on the substrate 10 may include any one or more of the following: a first metasurface
  • the orthographic projection of the lens center of the lens 41 on the substrate 10 substantially overlaps the orthographic projection of the pixel center of the first pixel island 31 on the substrate 10
  • the orthographic projection of the lens center of the second metasurface lens 42 on the substrate 10 overlaps with the first pixel center on the substrate 10.
  • the orthographic projection of the pixel center of the second pixel island 32 on the substrate 10 substantially overlaps, the orthographic projection of the lens center of the third metasurface lens 43 on the substrate 10 and the orthographic projection of the pixel center of the third pixel island 33 on the substrate 10 Basically overlapping, the orthographic projection of the lens center of the fourth metasurface lens 44 on the substrate 10 substantially overlaps the orthographic projection of the pixel center of the fourth pixel island 34 on the substrate 10, the lens center of the fifth metasurface lens 45 is at The orthographic projection on the substrate 10 substantially overlaps the orthographic projection of the pixel center of the fifth pixel island 35 on the substrate 10, and the orthographic projection of the lens center of the sixth metasurface lens 46 on the substrate 10 overlaps with the pixel center of the sixth pixel island 36.
  • the orthographic projection of the center on the substrate 10 substantially overlaps, and the orthographic projection of the lens center of the seventh metasurface lens 47 on the substrate 10 substantially overlaps the orthographic projection of the pixel center of the seventh pixel island 37 on the substrate 10 .
  • the center of the eye 100, the lens center of the fourth metasurface lens 44, and the pixel center of the fourth pixel island 34 are collinear, and the center of the eye 100, the lens center of the fourth metasurface lens 44, and The line connecting the three points of the pixel centers of the fourth pixel island 34 is called the central line of sight O.
  • the orthographic projection of the lens center of the metasurface lens on the substrate and the orthographic projection of the pixel center of the pixel island on the substrate basically overlap. It can be understood that the lens center of each metasurface lens corresponds to the pixel center of the pixel island it regulates And the positions are aligned, the line connecting the lens center and the pixel center is parallel to the central line of sight O.
  • each pixel island may be disposed at a focal point of a corresponding metasurface lens.
  • the metasurface lens can be composed of metasurface units whose scale is smaller than the wavelength of the incident light, arranged according to a certain arrangement rule, and the metasurface unit can realize accurate modulation of the phase of the incident light with its micro-nano structure optical modulation characteristics , so as to realize the imaging function and light deflection function of the metasurface lens.
  • metasurface can realize the phase modulation of light through subwavelength unit structure.
  • the overall device can perform the phase expression of the required light control device through a large number of unit structures, so as to achieve the overall device performance output.
  • the metasurface lens realizes light field regulation by expressing the required light field regulation phase plane through the metasurface unit, so that the light can have the required regulation effect after passing through the metasurface lens.
  • Fig. 4a is a schematic diagram of the modulation effect when a metasurface lens expresses the phase of the lens. As shown in Figure 4a, when the metasurface lens expresses the lens phase, the metasurface lens can realize the modulation effect of beam convergence or divergence.
  • Fig. 4b is a schematic diagram of the modulation effect when a metasurface lens expresses the phase of a deflection grating. As shown in Figure 4b, when the metasurface lens expresses the phase with a deflection grating, the metasurface lens can realize the deflection modulation effect of the beam.
  • Fig. 4c is a schematic diagram of a metasurface lens expressing the modulation effect of the phase of the lens and the phase of the deflection grating.
  • the metasurface lens By combining the metasurface lens to express the lens phase and the deflection grating phase, and superimposing the metasurface lens lens phase information and the deflection grating phase information, the metasurface lens can be realized to have the expressive characteristics of expressing the lens phase and the deflection grating phase .
  • the metasurface lens when the metasurface lens expresses the phase of the lens and the phase of the deflection grating, the metasurface lens can not only achieve the modulation effect of beam convergence or divergence, but also the deflection modulation effect of the beam, and finally realize the modulation effect of the metasurface lens.
  • the modulation effect required by the light has a high degree of freedom in the design of the modulation effect.
  • phase expression when the metasurface lens expresses the lens phase and the deflection grating phase, its phase expression is:
  • (x, y) are the coordinates of different positions on the metasurface lens, and the center of the metasurface lens is the coordinate origin, is the phase at the point (x, y) on the metasurface lens, ⁇ is the wavelength of the incident light, f is the focal length of the metasurface lens, which is highly related to the placement of the lens, and ⁇ is the coordinate orientation of the pixel island corresponding to the metasurface lens angle, ⁇ is the light deflection angle required by the pixel island corresponding to the metasurface lens.
  • Lens phase information can be expressed.
  • the absolute value of the lens phase is proportional to the radius of the point on the metasurface lens.
  • 2 ⁇ (xcos ⁇ +ysin ⁇ )sin ⁇ / ⁇ can be expressed as deflection grating phase information.
  • the absolute value of the deflection grating phase is proportional to the light deflection angle ⁇ required by the pixel island.
  • the deflection grating phase of the first metasurface lens 41 corresponding to the first pixel island 31 is larger than that of the second pixel island 31.
  • the phase of the deflection grating of the second metasurface lens 42 corresponding to the island 32 can be expressed as deflection grating phase information.
  • the metasurface unit may be a metal microstructure or a dielectric microstructure with a size smaller than a wavelength built on a substrate.
  • silicon oxide SiOx
  • silicon nitride SiNx
  • the refractive index difference between silicon oxide and silicon nitride may be greater than or equal to 0.5.
  • the metasurface unit phase modulation can include the transmission phase metasurface modulation based on the change of the unit structure scale (including height, width, diameter, etc.) to introduce the equivalent refractive index change to form a phase delay, and the introduction of polarization based on the same unit structure and different rotation angles.
  • the phase modulation of the metasurface unit based on the transmission phase design can be understood as the phase difference caused by the transmission of light in structures with different aspect ratios.
  • the phase change caused by the transmission of light in the metasurface unit is proportional to the equivalent refractive index of the metasurface unit and the propagation distance.
  • the equivalent refractive index of the metasurface unit changes immediately. Therefore, by adjusting the radius of the nanopillar, the phase retardation value of light passing through the metasurface unit can be adjusted.
  • Fig. 5 is a schematic structural diagram of a metasurface unit according to an exemplary embodiment of the present disclosure.
  • the metasurface unit can include a substrate 51 and a pillar 52 arranged on the substrate 51, the substrate 51 can be made of silicon dioxide ( SiO2 ), the pillar 52 can be made of silicon nitride (SiNx), and the pillar 52 can be made of silicon nitride (SiNx).
  • the height h of 52 may be about 500nm to 800nm, and the radius r of the pillars may be about 55nm to 125nm.
  • the post may be a cylinder.
  • the cylinder may be an elliptical cylinder, a triangular cylinder, a rectangular cylinder or a polygonal cylinder, which is not limited in the present disclosure.
  • the phase change of the light field is a continuous change between 2 ⁇ (360° phase change), and by traversing the parameters of the metasurface unit, multiple metasurfaces containing 2 ⁇ phase changes at different wavelengths can be obtained
  • the basic structure database contains column structures with different heights and different radii, and the phase information corresponding to these column structures, and the phase information covers the range from 0 to 2 ⁇ .
  • the basic structure database can be used for different Phase modulation requires the construction of corresponding metasurface lenses.
  • a lens structure database in order to simplify the computational complexity of constructing a metasurface lens and improve construction efficiency, can be constructed on the basis of the basic structure database.
  • the lens structure database contains columnar structures with the same height and n radii , and the basic phase information corresponding to n columnar structures respectively, using the lens structure database to construct the corresponding metasurface lens, n can be a positive integer greater than or equal to 2.
  • the phase division can be performed according to the phase step size of ⁇ /4 to obtain 8 basic phases, which are: 0, ⁇ /4, ⁇ /2, 3 ⁇ /4, ⁇ , 5 ⁇ /4, 3 ⁇ /2, and 7 ⁇ /4.
  • 8 column structures corresponding to 8 basic phases are selected to construct the lens structure database. Therefore, the lens structure database includes 8 basic phases and column structures corresponding to the 8 basic phases.
  • phase step size the more refined the obtained lens structure database, but the more complicated the calculation and processing.
  • Choosing a phase step of ⁇ /4 can not only ensure that the metasurface lens can cover the required phase information, but also facilitate calculation and subsequent fabrication.
  • the phase steps may be the same, or may be different, which is not limited by the present disclosure.
  • FIG. 6 is a schematic diagram of a lens structure database according to an exemplary embodiment of the present disclosure, illustrating a plurality of metasurface units for a wavelength of 620 nm.
  • the lens structure database can include 8 basic phases and columnar metasurface units corresponding to the 8 basic phases.
  • the 8 metasurface units include SiO 2 substrates with a height of 800nm and radii of 55nm and 75nm respectively. , 85nm, 90nm, 100nm, 105nm, 110nm, 125nm SiNx nanopillars, the basic phases of the 8 metasurface units are 0°, 32°, 90°, 178°, 235°, 266°, 316°, 329° .
  • the unit period may be the distance between the centers of adjacent metasurface units, which may be about 200nm to 300nm.
  • the cell period may be approximately 250nm.
  • the construction process of the metasurface lens may include:
  • the lens structure database includes a plurality of basic phases and a plurality of metasurface units corresponding to the multiple basic phases;
  • phase and lens structure database of different positions on the metasurface lens determine the metasurface units at different regions on the metasurface lens
  • the metasurface lens is constructed by using the metasurface units at different positions on the metasurface lens.
  • building the lens structure database may include:
  • Multiple metasurface units corresponding to multiple basic phases are selected from the basic structure database to form a lens structure database.
  • the metasurface unit may be a cylindrical structure
  • the constructed basic structure database may contain multiple cylindrical structures with different heights and different radii, and phase information corresponding to these cylindrical structures, and the phase information covers range from 0 to 2 ⁇ .
  • the metasurface units in the basic structure database can be processed according to the actual machinable cylinder height and the theoretical optimal principle pick. For example, metasurface elements of the same height can be selected.
  • the preset phase selection strategy may be a preset phase step size, or may be a preset phase value.
  • the preset phase selection strategy may be to select the basic phase with a phase step size of ⁇ /4 within the range of phase 0 to 2 ⁇ .
  • the preset phase selection strategy can be within the range of phase 0 to 2 ⁇ , select phase values of 0°, 32°, 90°, 178°, 235°, 266°, 316°, and 329° as the basis phase.
  • metasurface units corresponding to the multiple basic phases may be selected from the basic structure database to form the lens structure database.
  • the radii of the eight corresponding metasurface units are 55nm, 75nm, 85nm, 90nm, 100nm, 105nm, 110nm, 125nm
  • the height of the 8 metasurface units is 800nm.
  • obtaining phases at different positions of the metasurface lens may include: obtaining phases at different positions on the metasurface lens according to lens phase formula (1).
  • obtaining the phases of different positions of the metasurface lens may include: first, establishing a two-dimensional coordinate system on the first metasurface lens 41, and the first metasurface lens 41 The geometric center of is the coordinate origin. Then, the design wavelength is selected, and the design wavelength may be the wavelength of red light, the wavelength of green light or the wavelength of blue light. For example, 620nm may be selected as the design wavelength. Subsequently, the phases at different positions on the first metasurface lens 41 at a design wavelength of 620 nm are calculated using the lens phase formula (1), as shown in FIG. 7 , which is a schematic diagram of phases at different positions on the metasurface lens.
  • determining the metasurface units of different regions on the metasurface lens may include: discretizing the phases of different positions on the metasurface lens, obtaining The phases of different regions on the metasurface lens, according to the phases of different regions on the metasurface lens and the lens structure database, determine the metasurface units of different regions on the metasurface lens.
  • the metasurface unit for determining the positions of different regions on the metasurface lens may include: first, dividing different regions on the first metasurface lens 41, taking the center of the region The point coordinates are used as the position of the region, and the phases of each position in each region are discretized to obtain the phases of different regions on the metasurface lens, as shown in Figure 8, which is a schematic diagram of the discretized phase on the metasurface lens.
  • the unit period of the metasurface unit can be used as the minimum division scale, and the discretization can be performed according to the size of the unit period of the metasurface unit.
  • the discretized phase can be the phase of the coordinates of the center point of the area, or it can be the area The average value of the phases of each position in the range, which is not limited in the present disclosure.
  • the obtained phase of a certain region of the first metasurface lens 41 is compared with the basic phase in the lens structure database to obtain a basic phase closest to the phase.
  • a basic phase that is closest to the phase can be obtained by matching using the nearest principle.
  • the metasurface unit corresponding to the basic phase is selected from the structure database, so as to obtain the metasurface unit at the position of the region on the metasurface lens. By repeating this process, the metasurface units of all regions on the metasurface lens can be obtained.
  • constructing the metasurface lens according to the metasurface units at different regional positions in the metasurface lens may include: using the acquired metasurface units at different regional positions, performing structure filling at different regional positions of the metasurface lens, thereby The metasurface lens is constructed, and the phase information corresponding to different regions of the metasurface lens can realize that the metasurface lens has both the imaging function and the light deflection function, as shown in Figure 9, which is a metasurface constructed by the metasurface unit.
  • Figure 9 is a metasurface constructed by the metasurface unit.
  • a plurality of metasurface lenses may have the same imaging lens characteristics, that is, have the same lens aperture and focal length. According to the required deflection angle, the corresponding metasurface lens has corresponding deflection angle characteristics, so that the deflection of the pixel island imaging can be realized in the non-off-axis situation, and finally the seamless splicing can be realized on the human retina.
  • the first metasurface lens 41 to the seventh metasurface lens 47 have the same display field of view range
  • the deflection angle of the fourth metasurface lens 44 on the central line of sight O is 0, and the deflection angle of the fourth metasurface lens 44 located on the fourth metasurface lens
  • the deflection angle of the third metasurface lens 43 and the fifth metasurface lens 45 on the outside of 44 (the side away from the central line of sight O) is ⁇
  • the deflection angle of the sixth metasurface lens 46 outside the surface lens 45 is 2 ⁇
  • the deflection angle of the first metasurface lens 41 outside the second metasurface lens 42 and the seventh metasurface lens 47 outside the sixth metasurface lens 46 The angle is 3 ⁇ .
  • parameters such as the placement height H and the focal length f of the metasurface lens can be known, and according to the positions of the first metasurface lens 41 to the seventh metasurface lens 47, the metasurface lens can be known.
  • the coordinate azimuth angle ⁇ of the pixel island corresponding to the surface lens, the light deflection angle ⁇ required by the corresponding pixel island, the wavelength ⁇ of the incident light and other parameters, and then the phase expression of each lens can be calculated by formula (1), according to The phase expression of each lens is used to construct the metasurface lens, and the metasurface unit with the corresponding phase in the lens structure database is used for structure filling, and finally a metasurface lens equivalent to the corresponding optical modulation effect can be obtained.
  • the metasurface lens array provided by the exemplary embodiment of the present disclosure because the thickness of the metasurface lens is less than or equal to about 800 nm, compared with the traditional microlens array with a thickness of about 2 ⁇ m, the lens thickness is effectively reduced, which is beneficial to near-eye display Thinning of the device.
  • the metasurface lens proposed in this disclosure has both imaging function and light deflection function. Compared with the traditional dislocation imaging deflection structure, it effectively avoids the large aberration caused by off-axis imaging, and can ensure the imaging quality of different deflection angles. . Since the metasurface lens is an expression of the transmission formula of the ideal lens, compared with the traditional geometric lens, it effectively avoids the aberration problem caused by the uneven processing of the lens.
  • FIG. 10 is a schematic diagram of a metasurface lens array according to an exemplary embodiment of the present disclosure.
  • the metasurface lens array can include 3 ⁇ 3 metasurface lenses arranged in a matrix, the diameter (aperture) D of the metasurface lens can be about 0.7mm, and the spacing (unit period) L between adjacent metasurface lenses can be about is 2.807mm, the focal length of the metasurface lens can be about 5mm, and the central field angle of the metasurface lens is 5.725°.
  • the deflection angle angle information of each metasurface lens can be known.
  • the deflection angle of the first lens T1 may be 0°.
  • the horizontal deflection angle of the second lens T2 and the third lens T3 may be 5.725°, and the vertical deflection angle may be 0°.
  • the horizontal deflection angle of the fourth lens T4 and the fifth lens T5 may be 0°, and the vertical deflection angle may be 5.725°.
  • the horizontal deflection angle of the sixth lens T6, the seventh lens T7, the eighth lens T8 and the ninth lens T9 may be 5.725°, and the vertical deflection angle may be 5.725°.
  • the structural design of the metasurface lens for monochromatic deflection imaging with deflection angles of 0° and 5.725° can be performed, and Fig. 11a to Fig. 11c are a kind of Schematic diagram of the design of a metasurface lens with an additional deflection angle of 0°.
  • Figure 11a is a schematic diagram of the phase distribution of the lens at a field of view of 0°, through the formula calculated.
  • Figure 11b is 0 Schematic diagram of the phase distribution of the °FOV metasurface lens in the range of 0 to 2 ⁇ . Perform phase discretization according to the period of the metasurface unit, and place the corresponding phase modulation value metasurface unit at the corresponding coordinates to obtain the final metalens structure.
  • Figure 11c shows the structure of the metasurface lens with a 0° field of view, which is a part of the metasurface lens Top view, rendered as a circle of corresponding radius in top view.
  • Figure 12a to Figure 12c are schematic diagrams of the design of a metasurface lens with an additional deflection angle of 5.725°
  • Figure 12a is a schematic diagram of the phase distribution of the lens at a 5.725° field of view
  • Figure 12b is a metasurface lens with a 5.725° field of view at 0 to 2 ⁇
  • Figure 12c is the structure of the metasurface lens with a field of view of 5.725°.
  • Figure 13a is a curve of the MTF of a geometric lens imaging in a field of view of 5.725° with resolution
  • Figure 13b is a curve of the MTF of a metasurface lens in a field of view of 5.725° with resolution
  • Figure 14a is a curve of a geometric lens
  • Figure 14b is the curve of the MTF of the metasurface lens imaging at the field of view of 5.725°+5.725° changing with the resolution
  • the line pair on the constant left can reflect the resolution Rate.
  • the 5.725° field of view may be the field of view of the second lens T2 or the third lens T3 (with a horizontal deflection angle of 5.725°), or it may be the fourth lens T4 or the fifth lens T5 (with a vertical deflection angle of 5.725°)
  • the field of view of 5.725°+5.725° can be the field of view of the sixth lens T6, the seventh lens T7, the eighth lens T8 or the ninth lens T9 (horizontal deflection angle is 5.725°, vertical deflection angle is 5.725°) field. Since geometric lenses are stitched into a complete picture through off-axis imaging, there is a risk of off-axis aberrations.
  • the MTF curves of the disclosed metasurface lens in the 5.725° field of view imaging and 5.725°+5.725° field of view imaging that the MTF curves of the sagittal plane and the meridian plane under different field of view conditions They are all coincident, indicating that the metasurface lens has the same imaging ability in different field angles and different directions corresponding to the metasurface lens, thus realizing aberration-free imaging.
  • the light imaging of the metasurface lens in different fields of view The quality can be kept consistent with the central field of view, which ensures the imaging quality of the field of view controlled by different lenses.
  • the metasurface lens of the present disclosure is applied in a splicing display system, which avoids the limitation of the overall viewing angle of the system caused by the large viewing angle aberration of the existing structure, and the disclosed scheme makes it feasible to expand the viewing angle.
  • Figure 15a is a schematic diagram of the splicing display effect of the metasurface lens array shown in Figure 10
  • Figure 15b is a display luminance distribution curve diagram of the metasurface lens array shown in Figure 10
  • X is the coordinate in the horizontal direction taking the center of the splicing picture as the origin
  • Y is the coordinate in the vertical direction with the center of the spliced screen as the origin.
  • Fig. 16 is a schematic diagram of another metasurface lens array according to an exemplary embodiment of the present disclosure.
  • Fig. 17a is a schematic diagram of the mosaic display effect of the metasurface lens array shown in Fig. 16, and Fig. 17b is a display brightness of the metasurface lens array shown in Fig. 16 Distribution graph. Since the metasurface lens is not affected by off-axis aberrations, the field of view constructed by it is only limited by the size of the backplane. As long as the size of the backplane is large enough, the metasurface lens array can expand the field of view of the spliced display as much as possible. field angle.
  • the metasurface lens array can include matrix-arranged 5 ⁇ 5 metasurface lenses, the diameter (diameter) D of the metasurface lens can be about 0.7mm, the unit period L of the metasurface lens can be about 2.807mm, the focal length of the metasurface lens can be about 5mm, the The central field of view is 5.725°.
  • the simulation results show that the metasurface lens array can increase the deflection angle by 11.45° and achieve a stitching field angle close to 28°, as shown in Figure 17a, and the brightness fluctuation is less than 0.5%, as shown in Figure 17b.
  • FIG. 18 is a schematic diagram of yet another metasurface lens array according to an exemplary embodiment of the present disclosure, illustrating the distribution of the metasurface lens array during color mosaic display. Due to the wavelength-selective properties of the metasurface lens, it is necessary to design correspondingly for the red (R) pixel island, green (G) pixel island, and blue (B) pixel island to realize the display of color pixel island splicing.
  • the metasurface lens array can include 27 metasurface lenses arranged regularly, the diameter (diameter) D of the metasurface lens can be about 0.7mm, and the unit period L of the metasurface lens can be about 2.807mm, The focal length of the metasurface lens can be about 5mm, and the central field angle of the metasurface lens is 5.725°.
  • 3 B pixel islands and 3 R pixel islands may be arranged alternately in the horizontal direction, and 3 B pixel islands and 3 G pixel islands may be arranged alternately in the vertical direction,
  • the color of the sub-pixels in each pixel island is the same, and the size of the pixel island corresponding to each color is the same as the optical parameters of the metasurface lens.
  • the principle of converging into the same point on the retina of the eye realizes the superposition of three colors, realizes overlapping at the imaging surface (human eye), and achieves color display, and cooperates with the design of the deflection angle of the super-lens of adjacent pixel islands to realize color splicing display.
  • the present disclosure proposes the use of a metasurface lens array based on the requirements of pixel-island splicing display devices for expanding the field of view angle and utilizing the high degree of freedom of metasurface light field regulation.
  • the pixel island splicing display scheme that realizes large-angle off-axis light imaging realizes the improvement of the viewing angle of the splicing display device on the basis of thinning and thinning.
  • the metasurface lens array has the properties of aberration-free lens and deflection grating at the same time, the off-axis phase difference problem of the lens corresponding to the pixel island with a large viewing angle is avoided, and the dislocation between the lens and the pixel island is no longer required to ensure Splicing imaging, the imaging field of view of the splicing display device is no longer limited by the off-axis aberration of the lens and the size of the back plate, which can realize the expansion of the field of view, and has the advantages of thinning and lightening and device integration, which can be applied to thinning and lightening of AR The expansion of the field of view in transparent display and VR thin and light display.
  • Exemplary embodiments of the present disclosure also provide a method for constructing a metasurface lens.
  • a method of constructing a metasurface lens may include:
  • the lens structure database includes a plurality of basic phases and a plurality of metasurface units corresponding to the multiple basic phases;
  • building the lens structure database in step S1 may include:
  • the basic structure database includes a plurality of metasurface units whose phase information covers a range from 0 to 2 ⁇ ;
  • obtaining phases at different positions on the metasurface lens in step S2 may include: obtaining phases at different positions on the metasurface lens according to a lens phase formula, and the lens phase formula is:
  • (x, y) are the coordinates of different position points on the described metasurface lens, and the geometric center of the described metasurface lens is the coordinate origin, Be the phase at the position point (x, y) on the metasurface lens, ⁇ is the wavelength of the incident light, f is the focal length of the metasurface lens, and ⁇ is the coordinate orientation of the pixel island corresponding to the metasurface lens angle, ⁇ is the light deflection angle required by the pixel island corresponding to the metasurface lens.
  • step S3 may include:
  • step S4 may include: using the obtained metasurface units in different regions, to perform structural filling in different regions of the metasurface lens, to construct the metasurface lens.
  • the method for constructing a metasurface lens calculates and discretizes the phase distribution of a metasurface lens, selects metasurface units with corresponding phase modulation values from the lens structure database, and utilizes these metasurface units Filling and arranging to construct a metasurface lens with a corresponding light field regulation effect can effectively avoid structural errors in the process of processing and designing traditional geometric optical devices, and can realize the design of optical devices in a small scale.
  • Exemplary embodiments of the present disclosure also provide a virtual/augmented reality device, including the aforementioned near-eye display device.
  • Virtual/augmented reality devices can be virtual/augmented reality head-mounted displays, or other devices or devices with near-eye display functions, which can realize large-angle light aberration-free deflection imaging, and achieve VR/ AR reality device.

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Abstract

本公开提供了一种近眼显示装置和超表面透镜的构建方法。近眼显示装置包括基板(10)、设置在基板(10)靠近眼睛(100)一侧的超表面透镜阵列(40)和位于基板(10)远离眼睛(100)一侧的像素岛阵列(30)，像素岛阵列(30)包括多个像素岛，超表面透镜阵列(40)包括多个超表面透镜，超表面透镜的透镜中心在基板(10)上的正投影与像素岛的像素中心在基板上的正投影重叠，透镜中心为超表面透镜的几何中心，像素中心为像素岛的几何中心。

Description

近眼显示装置和超表面透镜的构建方法 技术领域
本公开涉及但不限于显示技术领域，具体涉及一种近眼显示装置和超表面透镜的构建方法。
背景技术
虚拟现实(Virtual Reality，简称VR)和增强现实(Augmented Reality，简称AR)设备已逐步应用到显示、游戏、医疗等领域，用于实现VR/AR的近眼显示技术受到越来越多的关注和研究。近眼显示是一种使得观看者能够看清距离眼睛很近的内容的显示技术，利用光学系统将显示内容成像在眼睛的聚焦范围内，使眼睛能够看清显示内容。
发明内容
以下是对本文详细描述的主题的概述。本概述并非是为了限制权利要求的保护范围。
一方面，本公开示例性实施例提供了一种近眼显示装置，包括基板、设置在所述基板靠近眼睛一侧的超表面透镜阵列和位于所述基板远离眼睛一侧的像素岛阵列，所述像素岛阵列包括多个像素岛，所述超表面透镜阵列包括与所述多个像素岛一一对应的多个超表面透镜，所述超表面透镜的透镜中心在所述基板上的正投影与所述像素岛的像素中心在所述基板上的正投影重叠，所述透镜中心为所述超表面透镜的几何中心，所述像素中心为所述像素岛的几何中心。
在示例性实施方式中，至少一个超表面透镜具有成像功能和光线偏转功能，所述超表面透镜满足如下透镜相位公式：
Figure PCTCN2021141731-appb-000001
其中，(x,y)为所述超表面透镜上不同位置点的坐标，所述超表面透镜 的几何中心为坐标原点，
Figure PCTCN2021141731-appb-000002
为所述超表面透镜上位置点(x,y)处的相位，λ为入射光的波长，f为所述超表面透镜的焦距，Φ为所述超表面透镜所对应的像素岛的坐标方位角，θ为所述超表面透镜所对应的像素岛所需的光线偏转角度。
在示例性实施方式中，所述多个像素岛被配置为分别显示完整画面中的一部分图像，所述多个超表面透镜被配置为调制光路，使所有像素岛的图像拼接成的完整画面。
在示例性实施方式中，多个超表面透镜具有相同的透镜口径和焦距。
在示例性实施方式中，所述超表面透镜包括以单元周期进行规则排布的多个超表面单元，至少一个超表面单元包括基底和设置在所述基底上的柱体，所述基底的折射率与所述柱体的折射率不同。
在示例性实施方式中，所述基底的折射率与所述柱体的折射率的差值大于或等于0.5。
在示例性实施方式中，所述基底的材料包括硅氧化物，所述柱体的的材料包括硅氮化物。
在示例性实施方式中，所述柱体的高度为500nm至800nm。
在示例性实施方式中，所述柱体为圆柱体，所述圆柱体的半径为55nm至125nm。
在示例性实施方式中，所述单元周期为200nm至300nm。
另一方面，本公开示例性实施例还提供了一种超表面透镜的构建方法，包括：
构建透镜结构数据库，所述透镜结构数据库包括多个基础相位和与所述多个基础相位相对应的多个超表面单元；
获取超表面透镜上不同位置的相位，所述超表面透镜被配置为同时具有成像功能和光线偏转功能；
根据所述超表面透镜上不同位置的相位和所述透镜结构数据库，确定所述超表面透镜上不同区域位置的超表面单元；
采用所述超表面透镜上不同区域位置的超表面单元构建所述超表面透镜。
在示例性实施方式中，所述构建透镜结构数据库，包括：
构建基础结构数据库，所述基础结构数据库包括相位信息涵盖0到2π范围的多个超表面单元；
根据预设的相位选择策略得到多个基础相位；
在所述基础结构数据库中挑选出与所述多个基础相位相对应的多个超表面单元，组成透镜结构数据库。
在示例性实施方式中，所述获取超表面透镜上不同位置的相位，包括：
根据透镜相位公式得到所述超表面透镜上不同位置的相位，所述透镜相位公式为：
Figure PCTCN2021141731-appb-000003
其中，(x,y)为所述超表面透镜上不同位置点的坐标，所述超表面透镜的几何中心为坐标原点，
Figure PCTCN2021141731-appb-000004
为所述超表面透镜上位置点(x,y)处的相位，λ为入射光的波长，f为所述超表面透镜的焦距，Φ为所述超表面透镜所对应的像素岛的坐标方位角，θ为所述超表面透镜所对应的像素岛所需的光线偏转角度。
在示例性实施方式中，所述根据预设的相位选择策略得到多个基础相位，包括：
对所述超表面透镜上不同位置的相位进行离散化，获取所述超表面透镜上不同区域的相位；
根据所述超表面透镜上不同区域的相位和所述透镜结构数据库，确定所述超表面透镜上不同区域位置的超表面单元。
在示例性实施方式中，所述采用所述超表面透镜上不同区域位置的超表面单元构建所述超表面透镜，包括：利用获取的不同区域位置的超表面单元，在所述超表面透镜的不同区域位置进行结构填充，构建出所述超表面透镜。
在阅读并理解了附图和详细描述后，可以明白其他方面。
附图说明
附图用来提供对本公开技术方案的进一步理解，并且构成说明书的一部分，与本公开的实施例一起用于解释本公开的技术方案，并不构成对本公开技术方案的限制。附图中各部件的形状和大小不反映真实比例，目的只是示意说明本公开内容。
图1为一种近眼显示装置的结构示意图；
图2为近眼显示的原理图；
图3为本公开示例性实施例一种近眼显示装置结构示意图；
图4a为一种超表面透镜表达透镜相位时调制效果的示意图；
图4b为一种超表面透镜表达偏折光栅相位时调制效果的示意图；
图4c为一种超表面透镜表达透镜和偏折光栅相位时调制效果示意图；
图5为本公开示例性实施例一种超表面单元的结构示意图；
图6为本公开示例性实施例一种透镜结构数据库的示意图；
图7为超表面透镜上不同位置的相位示意图；
图8为超表面透镜上离散化后的相位示意图；
图9为由超表面单元构建出的超表面透镜的示意图；
图10为本公开示例性实施例一种超表面透镜阵列的示意图；
图11a至图11c为一种0°角度偏转超表面透镜相位和结构的示意图；
图12a至图12c为一种5.725°角度偏转超表面透镜相位和结构的示意图；
图13a为一种几何透镜在5.725°视场成像的MTF曲线；
图13b为超表面透镜在5.725°视场成像的MTF曲线；
图14a为一种几何透镜在5.725°+5.725°视场成像的MTF曲线；
图14b为超表面透镜在5.725°+5.725°视场成像的MTF曲线；
图15a为图10所示超表面透镜阵列的拼接显示效果示意图；
图15b为图10所示超表面透镜阵列的显示亮度分布曲线图；
图16为本公开示例性实施例另一种超表面透镜阵列的示意图；
图17a为图16所示超表面透镜阵列的拼接显示效果示意图；
图17b为图16所示超表面透镜阵列的显示亮度分布曲线图；
图18为本公开示例性实施例又一种超表面透镜阵列的示意图。
附图标记说明:
10—基板；             20—微透镜阵列；       30—像素岛阵列；
40—超表面透镜阵列；   51—基底；             52—柱体；
100—眼睛；            200—虚像。
具体实施方式
为使本公开的目的、技术方案和优点更加清楚明白，下文中将结合附图对本公开的实施例进行详细说明。注意，实施方式可以以多个不同形式来实施。所属技术领域的普通技术人员可以很容易地理解一个事实，就是方式和内容可以在不脱离本公开的宗旨及其范围的条件下被变换为各种各样的形式。因此，本公开不应该被解释为仅限定在下面的实施方式所记载的内容中。在不冲突的情况下，本公开中的实施例及实施例中的特征可以相互任意组合。为了保持本公开实施例的以下说明清楚且简明，本公开省略了部分已知功能和已知部件的详细说明。本公开实施例附图只涉及到与本公开实施例涉及到的结构，其他结构可参考通常设计
本公开中的附图比例可以作为实际工艺中的参考，但不限于此。例如：沟道的宽长比、各个膜层的厚度和间距、各个信号线的宽度和间距，可以根据实际需要进行调整。显示基板中像素的个数和每个像素中子像素的个数也不是限定为图中所示的数量，本公开中所描述的附图仅是结构示意图，本公开的一个方式不局限于附图所示的形状或数值等。
本说明书中的“第一”、“第二”、“第三”等序数词是为了避免构成要素的混同而设置，而不是为了在数量方面上进行限定的。
在本说明书中，为了方便起见，使用“中部”、“上”、“下”、“前”、“后”、“竖直”、“水平”、“顶”、“底”、“内”、“外”等指示方位或位置关系的词句以参照附图说明构成要素的位置关系，仅是为了便于描述本说明书和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本公开的限制。构成要素的位置关系根据描述各构成要素的方向适当地改变。因此，不局限于在说明书中说明的词句，根据情况可以适当地更换。
在本说明书中，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”应做广义理解。例如，可以是固定连接，或可拆卸连接，或一体地连接；可以是机械连接，或电连接；可以是直接相连，或通过中间件间接相连，或两个元件内部的连通。对于本领域的普通技术人员而言，可以具体情况理解上述术语在本公开中的具体含义。
在本说明书中，晶体管是指至少包括栅电极、漏电极以及源电极这三个端子的元件。晶体管在漏电极(漏电极端子、漏区域或漏电极)与源电极(源电极端子、源区域或源电极)之间具有沟道区域，并且电流能够流过漏电极、沟道区域以及源电极。注意，在本说明书中，沟道区域是指电流主要流过的区域。
在本说明书中，第一极可以为漏电极、第二极可以为源电极，或者第一极可以为源电极、第二极可以为漏电极。在使用极性相反的晶体管的情况或电路工作中的电流方向变化的情况等下，“源电极”及“漏电极”的功能有时互相调换。因此，在本说明书中，“源电极”和“漏电极”可以互相调换。
在本说明书中，“电连接”包括构成要素通过具有某种电作用的元件连接在一起的情况。“具有某种电作用的元件”只要可以进行连接的构成要素间的电信号的授受，就对其没有特别的限制。“具有某种电作用的元件”的例子不仅包括电极和布线，而且还包括晶体管等开关元件、电阻器、电感器、电容器、其它具有各种功能的元件等。
在本说明书中，“平行”是指两条直线形成的角度为-10°以上且10°以下的状态，因此，也包括该角度为-5°以上且5°以下的状态。另外，“垂直”是指两条直线形成的角度为80°以上且100°以下的状态，因此，也包括85°以上且95°以下的角度的状态。
在本说明书中，“膜”和“层”可以相互调换。例如，有时可以将“导电层”换成为“导电膜”。与此同样，有时可以将“绝缘膜”换成为“绝缘层”。
在本说明书中，所采用的“同层设置”是指两种(或两种以上)结构通过同一次图案化工艺得以图案化而形成的结构，它们的材料可以相同或不同。例如，形成同层设置的多种结构的前驱体的材料是相同的，最终形成的材料可以相同或不同。
本说明书中三角形、矩形、梯形、五边形或六边形等并非严格意义上的，可以是近似三角形、矩形、梯形、五边形或六边形等，可以存在公差导致的一些小变形，可以存在导角、弧边以及变形等。
本公开中的“约”，是指不严格限定界限，允许工艺和测量误差范围内的数值。
图1为一种近眼显示装置的结构示意图，示意了一种采用微透镜阵列和像素岛阵列组合的拼接成像型方案，图2为近眼显示的原理图。如图1所示，近眼显示装置可以包括微透镜阵列20和像素岛阵列30，微透镜阵列20设置在眼睛100与像素岛阵列30之间。在示例性实施方式中，微透镜阵列20可以包括多个微透镜(微透镜201至微透镜205)，微透镜可以是几何透镜、二元衍射透镜和全息平面透镜中的一种或多种，微透镜的直径可以为0.1mm至3mm。像素岛阵列30可以包括多个像素岛(像素岛301至像素岛305)，像素岛301至像素岛305与微透镜201至微透镜205对应地设置。每个像素岛相当于一块微小的显示屏，可以包括多个子像素，多个子像素发出的光线通过对应的微透镜进入眼睛100，并在眼睛100前某一景深处形成放大的虚像200。多个像素岛可以按照眼睛100的观看需求排布，对于观看者要观看的完整画面，每个像素岛只显示该完整画面中的一部分图像，通过设计像素岛和微透镜的位置排布，可以使所有像素岛的虚像形成在同一景深处，所有像素岛的图像形成的虚像200可以在同一景深处拼接成完整的虚 像，实现视场拼接。
实现视场拼接时，需要相邻像素岛边缘发出的光线进入眼睛的角度相同。如图2所示，对于相邻的像素岛302和像素岛303，像素岛303上边缘发出的光线经过微透镜203放大后产生进入眼睛的平行光的角度，等于像素岛302下边缘发出的光线经过微透镜202放大后产生的进入眼睛的平行光的角度。对于微透镜和像素岛集合中的一个子集合(一个子集合包括多个像素岛)，如果它们均能产生一束某一角度的光线(如0°)，且这些光线均可以进入眼睛瞳孔，则这些光线对于眼睛而言，产生的是同一虚像点(如0°视场对应的无限远处的虚像点)。
研究表明，由于微透镜阵列20与像素岛阵列30之间相距一定距离(称为放置高度)，因而需要微透镜与对应像素岛之间设置相应的位错来实现不同像素岛发出光线的不同角度偏转，通过离轴成像拼接成完整的画面。目前，微透镜的最大离轴成像角度具有一定的极限。例如，当放置高度为10mm时，最大离轴成像角度约为±10°。因此，受限于单个微透镜的最大离轴成像角度，现有结构的近眼显示装置无法实现较大的视场角。
为了增大近眼显示装置的视场角，相关技术提供了多种技术方案。例如，一个技术方案是采用曲面基板，利用曲面基板弯曲的角度来实现视场角的增大，但采用曲面基板不仅会增加近眼显示装置的厚度，与轻薄化的发展趋势不符，而且曲面基板的加工工艺复杂，难度大，生产成本高。又如，另一个技术方案是在微透镜上增加全息体光栅结构，将经微透镜后的光线进行衍射偏转，由于需要在每个像素岛位置上设计对应周期或光栅矢量方向的子光栅，因而该方案不仅设计复杂，加工难度大，而且对光源准直度要求高。再如，又一个技术方案是在透镜上增加偏转棱镜，由于微透镜阵列的加工要求高，因而该方案加工难度大，且会影响系统整体尺寸。
本公开示例性实施例提供了一种近眼显示装置。在示例性实施方式中，近眼显示装置包括基板、设置在所述基板靠近眼睛一侧的超表面透镜阵列以及设置在所述基板远离眼睛一侧的像素岛阵列，所述像素岛阵列包括多个像素岛，所述超表面透镜阵列包括与所述多个像素岛一一对应的多个超表面透镜，所述超表面透镜的透镜中心在所述基板上的正投影与所述像素岛的像素 中心在所述基板上的正投影重叠。
在示例性实施方式中，所述超表面透镜的透镜中心可以是超表面透镜的几何中心，所述像素岛的像素中心可以是像素岛的几何中心。
图3为本公开示例性实施例一种近眼显示装置结构示意图。如图3所示，近眼显示装置可以包括：基板10，设置在基板10靠近眼睛100一侧的超表面透镜阵列40，以及设置在基板10远离眼睛100一侧的像素岛阵列30。在示例性实施方式中，基板10可以是由透明材料构建的载体，被配置为搭载超表面透镜阵列40，并作为放置高度H实现光线的透射。像素岛阵列30可以包括多个间隔设置的像素岛(第一像素岛31至第七像素岛37)，每个像素岛可等效于一块微小的显示屏，显示完整画面中的一部分图像，多个像素岛所显示的画面经光路设计后，可在人眼处拼接成为完整画面。超表面透镜阵列40可以包括多个间隔设置的超表面透镜(第一超表面透镜41至第七超表面透镜47)，每个超表面透镜被配置为同时具有成像功能和光线偏转功能，超表面透镜所表达的相位为成像透镜相位和对应像素岛位置所需的偏转相位，对不同偏转需求的光线进行无离轴相差成像。
在示例性实施方式中，基板10可以采用玻璃、陶瓷、石英等材料，或者可以采用硅化合物，如氮化硅Si 3N 4等。为了减小整个近眼显示装置的重量，基板可以采用较轻的透明材料，如聚甲基丙烯酸甲酯(polymethyl methacrylate，PMMA)，又称为亚克力或有机玻璃。每个像素岛可以包括多个相同颜色的像素点(一个像素点包括至少一个子像素)，形成一个像素点簇，相当于由像素点簇组成的一块微小的显示屏。像素岛与像素岛之间的间隔作为近眼显示的透明区，用于外部光线的进入。本实施结构中，像素岛可以是自发光显示，或者可以是包括背光模组的非自发光显示。像素岛可以包括如下的任意一种或多种：液晶显示(Liquid Crystal Display，简称LCD)，有机发光二极管显示(Organic Light Emitting Diode，简称OLED)，发光二极管显示(Light Emitting Diode，简称LED)，无机电致发光显示(Electro Luminescent display，简称EL)，场致发射显示(Field Emission Display，简称FED)，表面传导电子发射显示(Surface-conduction Electron-emitter Display，简称SED)，等离子显示(Plasma Display Panel，简称PDP)，电 泳显示(Electro Phoretic Display，简称EPD)。
在示例性实施方式中，在平行于基板的平面上，超表面透镜可以具有透镜中心，透镜中心可以是超表面透镜的几何中心。在平行于基板的平面上，像素岛可以具有像素中心，像素中心可以是像素岛的几何中心。
在示例性实施方式中，多个像素岛可以包括第一像素岛31、第二像素岛32、第三像素岛33、第四像素岛34、第五像素岛35、第六像素岛36和第七像素岛37，多个超表面透镜可以包括与第一像素岛31对应的第一超表面透镜41、与第二像素岛32对应的第二超表面透镜42、与第三像素岛33对应的第三超表面透镜43、与第四像素岛34对应的第四超表面透镜44、与第五像素岛35对应的第五超表面透镜45、与第六像素岛36对应的第六超表面透镜46、以及与第七像素岛37对应的第七超表面透镜47。
在示例性实施方式中，超表面透镜的透镜中心在基板10上的正投影与像素岛的像素中心在基板10上的正投影基本上重叠可以包括如下任意一项或多项：第一超表面透镜41的透镜中心在基板10上的正投影与第一像素岛31的像素中心在基板10上的正投影基本上重叠，第二超表面透镜42的透镜中心在基板10上的正投影与第二像素岛32的像素中心在基板10上的正投影基本上重叠，第三超表面透镜43的透镜中心在基板10上的正投影与第三像素岛33的像素中心在基板10上的正投影基本上重叠，第四超表面透镜44的透镜中心在基板10上的正投影与第四像素岛34的像素中心在基板10上的正投影基本上重叠，第五超表面透镜45的透镜中心在基板10上的正投影与第五像素岛35的像素中心在基板10上的正投影基本上重叠，第六超表面透镜46的透镜中心在基板10上的正投影与第六像素岛36的像素中心在基板10上的正投影基本上重叠，第七超表面透镜47的透镜中心在基板10上的正投影与第七像素岛37的像素中心在基板10上的正投影基本上重叠。
在示例性实施方式中，眼睛100的中心、第四超表面透镜44的透镜中心和第四像素岛34的像素中心三点共线，眼睛100的中心、第四超表面透镜44的透镜中心和第四像素岛34的像素中心三点的连线称之为中心视线O。超表面透镜的透镜中心在基板上的正投影与像素岛的像素中心在基板上的正投影基本上重叠可以理解为，每个超表面透镜的透镜中心与其调控的像素岛 的像素中心一一对应且位置对齐，透镜中心和像素中心两点的连线与中心视线O平行。
在示例性实施方式中，每个像素岛可以设置在所对应的超表面透镜的焦点处。
在示例性实施方式中，超表面透镜可以由尺度小于入射光波长的超表面单元按照一定排列规律进行排列构成，超表面单元能够以其微纳结构光学调制特性，实现对入射光相位的准确调制，从而实现超表面透镜的成像功能和光线偏转功能。超表面作为一种新型的光学调控元件，可通过亚波长量级的单元结构实现光的相位调制。整体器件可通过大量的单元结构，进行所需的光线调控器件的相位表达，从而进行整体的器件性能输出。由于超表面单元的高设计自由度和本身在尺度上的优势(百纳米量级的结构厚度)，使其能够突破传统光学元器件的加工难度，不受传统几何光学理论的限制，实现任意光场调控需求，可在更小尺度上，利用简单工艺制造出超薄、平坦、无像差的光学器件，具有设计性强、结构尺寸小、集成度高、可精确控光设计等特点。
在示例性实施方式中，超表面透镜是通过超表面单元对所需光场调控相位面的表达来实现光场调控，使得光线经过超表面透镜后，具有所需的调控效果。
图4a为一种超表面透镜表达透镜相位时调制效果的示意图。如图4a所示，当超表面透镜表达透镜相位时，超表面透镜可以实现光束会聚或发散的调制效果。图4b为一种超表面透镜表达偏折光栅相位时调制效果的示意图。如图4b所示，当超表面透镜表达具有偏折光栅的相位时，超表面透镜可以实现光束的偏折调制效果。图4c为一种超表面透镜表达透镜相位和偏折光栅相位时调制效果的示意图。通过将超表面透镜表达透镜相位和表达偏折光栅相位组合起来，将超表面透镜透镜相位信息与偏折光栅相位信息进行叠加，可以实现超表面透镜具有表达透镜相位和偏折光栅相位的表达特性。如图4c所示，在超表面透镜表达透镜相位和偏折光栅相位时，超表面透镜不仅可以实现光束会聚或发散的调制效果，而且可以实现光束的偏折调制效果，最终实现超表面透镜对光线所需的调控效果，具有调制效果设计的高自 由度。
在示例性实施方式中，在超表面透镜表达透镜相位和偏折光栅相位时，其相位表达式为：
Figure PCTCN2021141731-appb-000005
其中，(x,y)为超表面透镜上不同位置点的坐标，超表面透镜的中心为坐标原点，
Figure PCTCN2021141731-appb-000006
为超表面透镜上位置点(x,y)处的相位，λ为入射光的波长，f为超表面透镜的焦距，与透镜放置高度相关，Φ为超表面透镜所对应的像素岛的坐标方位角，θ为超表面透镜所对应的像素岛所需的光线偏转角度。
在示例性实施方式中，
Figure PCTCN2021141731-appb-000007
可以表达透镜相位信息。在入射光的波长λ和超表面透镜的焦距f不变的情况下，透镜相位的绝对值与超表面透镜上位置点的半径成正比。
在示例性实施方式中，2π(xcosφ+ysinφ)sinθ/λ可以表达为偏转光栅相位信息。在超表面透镜所对应的像素岛的坐标方位角Φ一定的情况下，偏转光栅相位的绝对值与像素岛所需的光线偏转角度θ成正比。例如，由于第一像素岛31所需的光线偏转角度大于第二像素岛32所需的光线偏转角度，因而第一像素岛31所对应的第一超表面透镜41的偏转光栅相位大于第二像素岛32所对应的第二超表面透镜42的偏转光栅相位。
在示例性实施方式中，超表面单元可以为构建在基底上的尺寸小于波长的金属微结构或者介质微结构。例如，基底的材料可以采用硅氧化物(SiOx)，介质微结构的材料可以采用硅氮化物(SiNx)，基底和介质微结构之间具有较大的折射率差。例如，硅氧化物与硅氮化物的折射率差可以大于或等于0.5。
超表面单元相位调制可以包含基于单元结构尺度变化(包括高度、宽度、直径等)不同而引入等效折射率变化构成相位延迟的传输相位型超表面调制、基于相同单元结构、不同旋转角度引入偏振分量电磁场相位差的几何 型超表面调制以及二者结合实现的混合相位调制原理。其中，基于传输型相位设计的超表面单元相位调制可理解为光线在不同深宽比结构内传输所引起的相位不同。
在示例性实施方式中，光线在超表面单元内传输所引起的相位变化与超表面单元的等效折射率和传播距离成正比。对于采用纳米柱结构的超表面单元，当纳米柱的半径发生变化时，超表面单元的等效折射率随即发生变化，因而通过调整纳米柱半径，可以调整光线经过超表面单元的相位延迟值。
图5为本公开示例性实施例一种超表面单元的结构示意图。如图5所示，超表面单元可以包括基底51和设置在基底51上的柱体52，基底51可以采用二氧化硅(SiO 2)，柱体52可以采用氮化硅(SiNx)，柱体52的高度h可以约为500nm至800nm，柱体的半径r可以约为55nm至125nm。
在示例性实施方式中，柱体可以圆柱体。在一些可能的示例性实施方式中，柱体可以椭圆柱体、三角柱体、矩形柱体或者多边形柱体，本公开在此不做限定。
在示例性实施方式中，光场的相位变化为2π(360°相位变化)之间的连续变化，通过对超表面单元的参数进行遍历，可以获得不同波长下包含2π相位变化的多个超表面单元，构成基础结构数据库，基础结构数据库中包含了不同高度、不同半径的柱结构，以及这些柱结构分别对应的相位信息，且相位信息涵盖了0到2π的范围，利用基础结构数据库可以针对不同相位调制需求构建相应的超表面透镜。
在示例性实施方式中，为了简化构建超表面透镜的计算复杂度以及提高构建效率，可以在基础结构数据库的基础上构建透镜结构数据库，透镜结构数据库中包含了相同高度、n个半径的柱结构，以及n个柱结构分别对应的基础相位信息，利用透镜结构数据库构建相应的超表面透镜，n可以大于或等于2的正整数。
在示例性实施方式中，在相位为0到2π的范围内，可以按照π/4的相位步长进行相位划分，得到8个基础相位，分别为：0、π/4、π/2、3π/4、π、5π/4、3π/2和7π/4。在基础结构数据库中挑选出与8个基础相位对应的8个柱结构，构建出透镜结构数据库，因而透镜结构数据库中，包含8个基础相 位以及8个基础相位对应的柱结构。
在示例性实施方式中，相位步长越小，得到的透镜结构数据库越精细，但计算与加工也越复杂。选择π/4的相位步长不仅可以保证超表面透镜可以涵盖所需的相位信息，并且可以方便计算与后续工艺制作。在示例性实施方式中，相位步长可以是相同的，或者可以是不同的，本公开在此不做限定。
图6为本公开示例性实施例一种透镜结构数据库的示意图，示意了针对620nm波长的多个超表面单元。如图6所示，透镜结构数据库可以包括8个基础相位以及8个基础相位对应的柱结构状的超表面单元，8个超表面单元包括SiO 2基板上高为800nm、半径分别为55nm、75nm、85nm、90nm、100nm、105nm、110nm、125nm的SiNx纳米柱，8个超表面单元的基础相位分别为0°、32°、90°、178°、235°、266°、316°、329°。
在示例性实施方式中，由于不同的超表面单元具有不同的相位延迟值，通过将多个超表面单元以设定的单元周期进行排列，即可针对不同相位调制需求构建出相应的超表面透镜。在示例性实施方式中，单元周期可以是相邻的超表面单元中心之间的距离，可以约为200nm至300nm。例如，单元周期可以约为250nm。
在示例性实施方式中，超表面透镜的构建过程可以包括：
构建透镜结构数据库，透镜结构数据库包括多个基础相位和与多个基础相位相对应的多个超表面单元；
获取超表面透镜上不同位置的相位，超表面透镜被配置为同时具有成像功能和光线偏转功能；
根据超表面透镜上不同位置的相位和透镜结构数据库，确定超表面透镜上不同区域位置的超表面单元；
采用超表面透镜上不同区域位置的超表面单元构建超表面透镜。
在示例性实施方式中，构建透镜结构数据库可以包括：
构建基础结构数据库，基础结构数据库包括相位信息涵盖0到2π范围的多个超表面单元；
根据预设的相位选择策略得到多个基础相位；
在基础结构数据库中挑选出与多个基础相位相对应的多个超表面单元，组成透镜结构数据库。
在示例性实施方式中，超表面单元可以是圆柱结构，所构建的基础结构数据库中可以包含不同高度、不同半径的多个圆柱结构，以及这些圆柱结构分别对应的相位信息，且相位信息涵盖了0到2π的范围。
在示例性实施方式中，为了方便后续加工以及提高超表面透镜的构建效率，在构建透镜结构数据库时，可以根据实际可加工的圆柱高度和理论最优原则对基础结构数据库中的超表面单元进行挑选。例如，可以选择高度相同的超表面单元。
在示例性实施方式中，预设的相位选择策略可以是预设的相位步长，或者可以是预设的相位值。例如，预设的相位选择策略可以是在相位0到2π的范围内以π/4的相位步长选择基础相位。又如，预设的相位选择策略可以是在相位0到2π的范围内，选择相位值分别为0°、32°、90°、178°、235°、266°、316°、329°作为基础相位。
在示例性实施方式中，得到多个基础相位后，可以在基础结构数据库中挑选出与多个基础相位对应的超表面单元，组成透镜结构数据库。例如，对于基础相位分别为0°、32°、90°、178°、235°、266°、316°、329°，8个对应的超表面单元的半径分别为55nm、75nm、85nm、90nm、100nm、105nm、110nm、125nm，8个超表面单元的高度均为800nm。
在示例性实施方式中，获取超表面透镜不同位置的相位可以包括：根据透镜相位公式(1)得到超表面透镜上不同位置的相位。
在示例性实施方式中，以第一超表面透镜41为例，获取超表面透镜不同位置的相位可以包括：首先，在第一超表面透镜41上建立二维坐标系，第一超表面透镜41的几何中心为坐标原点。随后，选择设计波长，设计波长可以为红色光线的波长、绿色光线的波长或者蓝色光线的波长。例如，可以选择620nm作为设计波长。随后，利用透镜相位公式(1)计算得到在设计波长620nm下第一超表面透镜41上不同位置的相位，如图7所示，图7为超表面透镜上不同位置的相位示意图。
在示例性实施方式中，根据超表面透镜上不同位置的相位和透镜结构数 据库，确定超表面透镜上不同区域位置的超表面单元可以包括：对超表面透镜上不同位置的相位进行离散化，获取超表面透镜上不同区域位置的相位，根据超表面透镜上不同区域位置的相位和透镜结构数据库，确定超表面透镜上不同区域位置的超表面单元。
在示例性实施方式中，以第一超表面透镜41为例，确定超表面透镜上不同区域位置的超表面单元可以包括：首先，在第一超表面透镜41上划分不同的区域，以区域中心点坐标作为该区域位置，将各个区域内各个位置的相位进行离散化，获取超表面透镜上不同区域位置的相位，如图8所示，图8为超表面透镜上离散化后的相位示意图。在示例性实施方式中，可以按照超表面单元的单元周期为最小划分尺度，根据超表面单元单元周期的尺寸进行离散，离散化后的相位可以是区域中心点坐标的相位，或者，可以是区域内各个位置相位的平均值，本公开在此不做限定。随后，将获取的第一超表面透镜41某一区域位置的相位与透镜结构数据库中的基础相位进行对比，得到与该相位最接近的一个基础相位。在示例性实施方式中，为了能够选取较合适的超表面单元，可以采用就近原则匹配得到与相位最接近的一个基础相位。随后，从结构数据库中选择出该基础相位对应的超表面单元，从而得到超表面透镜上该区域位置的超表面单元。重复该过程，可以得到超表面透镜上所有区域位置的超表面单元。
在示例性实施方式中，根据超表面透镜内不同区域位置的超表面单元构建超表面透镜可以包括：利用获取的不同区域位置的超表面单元，在超表面透镜的不同区域位置进行结构填充，从而构建出超表面透镜，超表面透镜的不同区域位置上对应的相位信息，可以实现超表面透镜同时具有成像功能和光线偏转功能，如图9所示，图9为由超表面单元构建出的超表面透镜的示意图。
在示例性实施方式中，对应于不同的像素岛，多个超表面透镜可以具有相同的成像透镜特性，即具有相同的透镜口径和焦距。根据所需偏转角度，相应的超表面透镜具有相应的偏转角度特性，从而在非离轴情况下实现像素岛成像的偏转，最终在人眼视网膜上实现无缝拼接。如图3所示，第一超表面透镜41至第七超表面透镜47具有相同显示视场范围，位于中心视线O上 的第四超表面透镜44的偏转角度为0，位于第四超表面透镜44外侧(远离中心视线O一侧)的第三超表面透镜43和第五超表面透镜45的偏转角度为θ，位于第三超表面透镜43外侧的第二超表面透镜42和位于第五超表面透镜45外侧的第六超表面透镜46的偏转角度为2θ，位于第二超表面透镜42外侧的第一超表面透镜41和位于第六超表面透镜46外侧的第七超表面透镜47的偏转角度为3θ。
在示例性实施方式中，根据近眼显示装置的结构设计，可以获知超表面透镜的放置高度H和焦距f等参数，根据第一超表面透镜41至第七超表面透镜47的位置，可以获知超表面透镜所对应的像素岛的坐标方位角Φ、对应的像素岛所需的光线偏转角度θ、入射光的波长λ等参数，然后通过公式(1)可以计算获得各个透镜的相位表达式，根据各个透镜的相位表达式进行超表面透镜的构建，利用透镜结构数据库内相应相位的超表面单元进行结构填充，最终可以获得等效于相应光学调制效果的超表面透镜。
本公开示例性实施例所提供的超表面透镜阵列，由于超表面透镜的厚度小于或等于800nm左右，相比于厚度约2μm左右的传统微透镜阵列，有效减小了透镜厚度，有利于近眼显示装置的轻薄化。本公开所提出的超表面透镜同时具有成像功能和光线偏转功能，相比于传统的位错成像偏转结构，有效避免了离轴成像带来的较大像差，可以保证不同偏转角度的成像质量。由于超表面透镜是对理想透镜的传输公式表达，因而相比于传统的几何透镜，有效避免了因透镜加工不均一引起的像差问题。
图10为本公开示例性实施例一种超表面透镜阵列的示意图。在示例性实施方式中，以基于8mm×8mm的OLED背板构建的单色像素岛拼接方案为例，根据像素岛尺寸(如3.308mm)、像素尺寸(如3.96μm)以及人眼分辨率需求，超表面透镜阵列可以包括矩阵方式排列的3×3个超表面透镜，超表面透镜的直径(口径)D可以约为0.7mm，相邻超表面透镜之间的间距(单元周期)L可以约为2.807mm，超表面透镜的焦距可以约为5mm，超表面透镜的中心视场角为5.725°。
如图10所示，根据各个超表面透镜的位置情况，可以得知各个超表面透镜透镜的偏转角度角度信息。例如，第一透镜T1的偏转角度可以为0°。 第二透镜T2和第三透镜T3的水平偏转角度可以为5.725°，竖直偏转角度可以为0°。第四透镜T4和第五透镜T5的水平偏转角度可以为0°，竖直偏转角度可以为5.725°。第六透镜T6、第七透镜T7、第八透镜T8和第九透镜T9的水平偏转角度可以为5.725°，竖直偏转角度可以为5.725°。
在示例性实施方式中，根据近眼显示装置和超表面透镜的参数信息，可以进行偏转角度为0°和5.725°的单色偏转成像的超表面透镜的结构设计，图11a至图11c为一种附加偏转角为0°的超表面透镜的设计示意图。图11a为0°视场时透镜的相位分布示意图，通过公式
Figure PCTCN2021141731-appb-000008
计算得到。由于透镜的相位分布为2π的倍数，为了将其运用在覆盖2π相位范围的超表面单元进行表达，需将透镜相位分布对2π取余，使其折叠在0至2π范围内，图11b为0°视场超表面透镜在0至2π范围的相位分布示意图。根据超表面单元的周期进行相位离散，并在相应坐标处放置相应相位调制值得超表面单元，得到最终的超透镜结构，图11c为0°视场超表面透镜的结构，为超表面透镜的局部俯视图，俯视图中呈现为相应半径的圆。图12a至图12c为一种附加偏转角为5.725°的超表面透镜的设计示意图，图12a为5.725°视场时透镜的相位分布示意图，图12b为5.725°视场超表面透镜在0至2π范围的相位分布示意图，图12c为5.725°视场超表面透镜的结构，为超表面透镜的局部俯视图，设计流程与图11a至图11c类似，区别在于相位分布通过公式(1)计算得到。
图13a为一种几何透镜在5.725°视场成像的MTF随分辨率变化的曲线，图13b为超表面透镜在5.725°视场成像的MTF随分辨率变化的曲线，图14a为一种几何透镜在5.725°+5.725°视场成像的MTF随分辨率变化的曲线，图14b为超表面透镜在5.725°+5.725°视场成像的MTF随分辨率变化的曲线，恒左边的线对可以反映分辨率。其中，5.725°视场可以是第二透镜T2或第三透镜T3(水平偏转角度为5.725°)的视场，或者可以是第四透镜T4或第五透镜T5(竖直偏转角度为5.725°)的视场，5.725°+5.725°视场可以是第六透镜T6、第七透镜T7、第八透镜T8或第九透镜T9(水平偏转角度为5.725°，竖直偏转角度为5.725°)的视场。由于几何透镜通过离轴成像拼接成完整的画面，因而具有离轴像差的风险。如图13a和图14a所示，从几 何透镜在5.725°视场成像和5.725°+5.725°视场成像的调制传递函数(Modulation Transfer Function，简称MTF)曲线可以看出，几何透镜中最边缘(5.725°)、次边缘(2.8625°)及中心视场(0°)的弧矢面与子午面的MTF随分辨率变化的曲线存在较大差距，边缘光线的成像质量相比于中心光线有大幅下降。由于本公开通过采用超表面透镜的在非离轴情况下实现像素岛成像的偏转，因而消除了离轴像差。如图13b和图14b所示，从本公开超表面透镜在5.725°视场成像和5.725°+5.725°视场成像的MTF曲线可以看出，不同视场条件的弧矢面与子午面的MTF曲线都是重合的，说明在超表面透镜对应的不同视场角及不同方向上，超表面透镜都有相同的成像能力，从而实现了无像差成像，超表面透镜在不同视场上的光线成像质量能保持与中心视场的一致性，确保了不同透镜管控视场范围的成像质量。本公开超表面透镜应用于在拼接显示系统中，避免了现有结构的大视角像差造成的系统整体视场角限制，本公开方案使得视场角扩展有了可行性。
图15a为图10所示超表面透镜阵列的拼接显示效果示意图，图15b为图10所示超表面透镜阵列的显示亮度分布曲线图，X为以拼接画面中心为原点的水平方向的坐标，Y为以拼接画面中心为原点的竖直方向的坐标。通过对图10所示超表面透镜阵列进行仿真，仿真结果表明，本公开所构建的超表面透镜阵列，可在人眼(光线接收面)处得约17°较优成像质量的视场拼接效果，如图15a所示，拼接画面中X向和Y向的亮度波动小于0.5％，在人眼可接受范围内，如图15b所示。
图16为本公开示例性实施例另一种超表面透镜阵列的示意图，图17a为图16所示超表面透镜阵列的拼接显示效果示意图，图17b为图16所示超表面透镜阵列的显示亮度分布曲线图。由于超表面透镜不受离轴像差的影响，其所构建的视场角仅受限于背板尺寸，只要背板尺寸足够大，超表面透镜阵列便可以尽可能大的扩大拼接显示的视场角。如图16所示，以基于12mm×12mm的OLED背板构建的单色像素岛拼接方案为例，根据像素岛尺寸、像素尺寸以及人眼分辨率需求，超表面透镜阵列可以包括矩阵方式排列的5×5个超表面透镜，超表面透镜的直径(口径)D可以约为0.7mm，超表面透镜的单元周期L可以约为2.807mm，超表面透镜的焦距可以约为5mm， 超表面透镜的中心视场角为5.725°。仿真结果表明，该超表面透镜阵列可以增加11.45°的偏转角度，实现接近28°的拼接视场角，如图17a所示，亮度波动小于0.5％，如图17b所示。
图18为本公开示例性实施例又一种超表面透镜阵列的示意图，示意了颜色拼接显示时超表面透镜的阵列分布情况。由于超表面透镜具有波长选择特性，因而需要针对红色(R)像素岛、绿色(G)像素岛和蓝色(B)像素岛分别进行相应设计，以实现颜色像素岛拼接的显示。如图18所示，超表面透镜阵列可以包括规则排布的27个超表面透镜，超表面透镜的直径(口径)D可以约为0.7mm，超表面透镜的单元周期L可以约为2.807mm，超表面透镜的焦距可以约为5mm，超表面透镜的中心视场角为5.725°。
在示例性实施方式中，27个像素岛中，3个B像素岛和3个R像素岛可以在水平方向交替设置，3个B像素岛和3个G像素岛可以在竖直方向交替设置，每个像素岛内子像素的颜色相同，每个颜色所对应的像素岛的大小和超表面透镜的光学参数相同，通过相应响应波长超表面透镜的偏转角度设计利用相同角度入射的光线经眼睛后在眼睛视网膜上汇聚为同一点的原理实现三色叠加，实现在成像面(人眼)处重合，达成彩色显示，配合相邻像素岛超透镜偏转角度的设计，实现颜色拼接显示。
通过本公开示例性实施例近眼显示装置的结构可以看出，本公开基于像素岛拼接显示器件在视场角扩大上的需求，利用超表面光场调控的高自由度，提出了采用超表面透镜阵列实现大角度离轴光线成像的像素岛拼接显示方案，在轻薄化的基础上实现了拼接显示器件视场角的提升。由于超表面透镜阵列同时具有无像差透镜和偏折光栅的属性，避免了大视角像素岛所对应透镜存在的离轴相差问题，也不再需要通过透镜与像素岛之间的位错来确保拼接成像，拼接显示器件成像视场角不再受限于透镜离轴像差及背板尺寸，可实现视场角的扩大，且具有轻薄化及器件集成化的优势，可应用于AR轻薄化透明显示以及VR轻薄化显示中对视场角的扩大。
本公开示例性实施例还提供了一种超表面透镜的构建方法。在示例性实施方式中，超表面透镜的构建方法可以包括：
S1、构建透镜结构数据库，所述透镜结构数据库包括多个基础相位和 与所述多个基础相位相对应的多个超表面单元；
S2、获取超表面透镜上不同位置的相位，所述超表面透镜被配置为同时具有成像功能和光线偏转功能；
S3、根据所述超表面透镜上不同位置的相位和所述透镜结构数据库，确定所述超表面透镜上不同区域位置的超表面单元；
S4、采用所述超表面透镜上不同区域位置的超表面单元构建所述超表面透镜。
在示例性实施方式中，步骤S1中构建透镜结构数据库可以包括：
S11、构建基础结构数据库，所述基础结构数据库包括相位信息涵盖0到2π范围的多个超表面单元；
S12、根据预设的相位选择策略得到多个基础相位；
S13、在所述基础结构数据库中挑选出与所述多个基础相位相对应的多个超表面单元，组成透镜结构数据库。
在示例性实施方式中，步骤S2中获取超表面透镜上不同位置的相位可以包括：根据透镜相位公式得到所述超表面透镜上不同位置的相位，所述透镜相位公式为：
Figure PCTCN2021141731-appb-000009
其中，(x,y)为所述超表面透镜上不同位置点的坐标，所述超表面透镜的几何中心为坐标原点，
Figure PCTCN2021141731-appb-000010
为所述超表面透镜上位置点(x,y)处的相位，λ为入射光的波长，f为所述超表面透镜的焦距，Φ为所述超表面透镜所对应的像素岛的坐标方位角，θ为所述超表面透镜所对应的像素岛所需的光线偏转角度。
在示例性实施方式中，步骤S3可以包括：
S31、对所述超表面透镜上不同位置的相位进行离散化，获取所述超表面透镜上不同区域的相位；
S31、根据所述超表面透镜上不同区域的相位和所述透镜结构数据库，确定所述超表面透镜上不同区域位置的超表面单元。
在示例性实施方式中，步骤S4可以包括：利用获取的不同区域位置的超表面单元，在所述超表面透镜的不同区域位置进行结构填充，构建出所述超表面透镜。
本公开示例性实施例提供的超表面透镜的构建方法，通过对超表面透镜的相位分布进行计算和离散化，在透镜结构数据库挑选出具有相应相位调制值的超表面单元，利用这些超表面单元进行填充排布，构建出具有相应光场调控效果的超表面透镜，可以有效避免传统几何光学器件加工、设计过程中的结构误差，可以实现在小尺度范围内进行光学器件的设计。
本公开示例性实施例还提供了一种虚拟/增强现实设备，包括前述的近眼显示装置。虚拟/增强现实设备可以是虚拟/增强现实头戴显示器，也可以是其它具有近眼显示功能的装置或设备，可以实现大角度光无像差偏折成像，达成具有大视场角特性的VR/AR现实设备。
虽然本公开所揭露的实施方式如上，但所述的内容仅为便于理解本公开而采用的实施方式，并非用以限定本公开。任何本公开所属领域内的技术人员，在不脱离本公开所揭露的精神和范围的前提下，可以在实施的形式及细节上进行任何的修改与变化，但本申请的专利保护范围，仍须以所附的权利要求书所界定的范围为准。

Claims (15)

  1. 一种近眼显示装置，包括基板、设置在所述基板靠近眼睛一侧的超表面透镜阵列和位于所述基板远离眼睛一侧的像素岛阵列，所述像素岛阵列包括多个像素岛，所述超表面透镜阵列包括与所述多个像素岛一一对应的多个超表面透镜，所述超表面透镜的透镜中心在所述基板上的正投影与所述像素岛的像素中心在所述基板上的正投影重叠，所述透镜中心为所述超表面透镜的几何中心，所述像素中心为所述像素岛的几何中心。
  2. 根据权利要求1所述的近眼显示装置，其中，至少一个超表面透镜具有成像功能和光线偏转功能，所述超表面透镜满足如下透镜相位公式：
    Figure PCTCN2021141731-appb-100001
    其中，(x,y)为所述超表面透镜上不同位置点的坐标，所述超表面透镜的几何中心为坐标原点，
    Figure PCTCN2021141731-appb-100002
    为所述超表面透镜上位置点(x,y)处的相位，λ为入射光的波长，f为所述超表面透镜的焦距，Φ为所述超表面透镜所对应的像素岛的坐标方位角，θ为所述超表面透镜所对应的像素岛所需的光线偏转角度。
  3. 根据权利要求1所述的近眼显示装置，其中，所述多个像素岛被配置为分别显示完整画面中的一部分图像，所述多个超表面透镜被配置为调制光路，使所有像素岛的图像拼接成的完整画面。
  4. 根据权利要求1所述的近眼显示装置，其中，多个超表面透镜具有相同的透镜口径和焦距。
  5. 根据权利要求1至4任一项所述的近眼显示装置，其中，所述超表面透镜包括以单元周期进行规则排布的多个超表面单元，至少一个超表面单元包括基底和设置在所述基底上的柱体，所述基底的折射率与所述柱体的折射率不同。
  6. 根据权利要求5所述的近眼显示装置，其中，所述基底的折射率与所述柱体的折射率的差值大于或等于0.5。
  7. 根据权利要求5所述的近眼显示装置，其中，所述基底的材料包括硅氧化物，所述柱体的的材料包括硅氮化物。
  8. 根据权利要求5所述的近眼显示装置，其中，所述柱体的高度为500nm至800nm。
  9. 根据权利要求5所述的近眼显示装置，其中，所述柱体为圆柱体，所述圆柱体的半径为55nm至125nm。
  10. 根据权利要求5所述的近眼显示装置，其中，所述单元周期为200nm至300nm。
  11. 一种超表面透镜的构建方法，包括：
    构建透镜结构数据库，所述透镜结构数据库包括多个基础相位和与所述多个基础相位相对应的多个超表面单元；
    获取超表面透镜上不同位置的相位，所述超表面透镜被配置为同时具有成像功能和光线偏转功能；
    根据所述超表面透镜上不同位置的相位和所述透镜结构数据库，确定所述超表面透镜上不同区域位置的超表面单元；
    采用所述超表面透镜上不同区域位置的超表面单元构建所述超表面透镜。
  12. 根据权利要求11所述的构建方法，其中，所述构建透镜结构数据库，包括：
    构建基础结构数据库，所述基础结构数据库包括相位信息涵盖0到2π范围的多个超表面单元；
    根据预设的相位选择策略得到多个基础相位；
    在所述基础结构数据库中挑选出与所述多个基础相位相对应的多个超表面单元，组成透镜结构数据库。
  13. 根据权利要求11所述的构建方法，其中，所述获取超表面透镜上不同位置的相位，包括：
    根据透镜相位公式得到所述超表面透镜上不同位置的相位，所述透镜相位公式为：
    Figure PCTCN2021141731-appb-100003
    其中，(x,y)为所述超表面透镜上不同位置点的坐标，所述超表面透镜的几何中心为坐标原点，
    Figure PCTCN2021141731-appb-100004
    为所述超表面透镜上位置点(x,y)处的相位，λ为入射光的波长，f为所述超表面透镜的焦距，Φ为所述超表面透镜所对应的像素岛的坐标方位角，θ为所述超表面透镜所对应的像素岛所需的光线偏转角度。
  14. 根据权利要求11所述的构建方法，其中，所述根据预设的相位选择策略得到多个基础相位，包括：
    对所述超表面透镜上不同位置的相位进行离散化，获取所述超表面透镜上不同区域的相位；
    根据所述超表面透镜上不同区域的相位和所述透镜结构数据库，确定所述超表面透镜上不同区域位置的超表面单元。
  15. 根据权利要求11所述的构建方法，其中，所述采用所述超表面透镜上不同区域位置的超表面单元构建所述超表面透镜，包括：利用获取的不同区域位置的超表面单元，在所述超表面透镜的不同区域位置进行结构填充，构建出所述超表面透镜。
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