Method for realizing full-space color holography based on double-layer metasurface

Abstract

The invention provides a method for realizing full-space color holography based on a double-layer metasurface, and the method comprises the steps: determining incident light, and setting the polarization state of the incident light; the set polarization state is incident to the double-layer metasurface; phase modulation is carried out on the incident light in the set polarization state through the double-layer metasurface, so that color holographic images are formed in the reflection space and the transmission space; wherein the double-layer metasurface comprises a wavelength selection type metasurface and a transmission type metasurface. According to the method for realizing full-space color holography based on the double-layer metasurface, multi-dimensional regulation and control on a complex optical function are realized by means of the double-layer metasurface, so that color holographic images are respectively obtained in a reflection space and a transmission space, and the quality and the information capacity of the holographic images are improved.

Description

Technical Field

[0001] This invention relates to the field of micro-nano optics and holography, and in particular to a method for realizing full-space color holography based on a double-layer metasurface. Background Technology

[0002] Color holographic display is a three-dimensional display technology that can vividly record and reproduce color holographic images. With the development of science and technology and people's increasing demands for visual experience, full-space color holographic technology has broad application prospects in many fields such as display, encryption, and storage, including virtual reality, augmented reality, 3D display, and information security. Therefore, the demand for technology that can realize full-space color holographic display is becoming increasingly urgent.

[0003] Currently, full-space color holography has certain limitations in display effects, making it difficult to achieve all-round, high-quality color holographic display. Furthermore, it has limited capabilities in terms of information storage density, display size, and viewing angle. Therefore, there is an urgent need for a new method of full-space color holography to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide a method for realizing full-space color holography based on a double-layer metasurface. The double-layer metasurface provides more design freedom and stronger wavefront modulation capabilities, enabling multi-dimensional modulation of complex optical functions, thereby achieving higher information storage density and better imaging quality.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for realizing full-space color holography based on a double-layer metasurface, comprising:

[0006] Determine the incident light and set its polarization state;

[0007] The pre-set polarization state is incident onto the bilayer metasurface;

[0008] Phase modulation of incident light with a pre-defined polarization state is achieved by using a double-layer metasurface to form color holographic images in both the reflection and transmission spaces.

[0009] Among them, the double-layer metasurface includes: wavelength-selective metasurface and transmissive metasurface.

[0010] Preferably, the double-layer metasurface is composed of an array of a plurality of structural units, the structural units comprising: a substrate and a support layer, the support layer being arranged on the substrate, the support layer connecting the wavelength-selective metasurface and the transmissive metasurface; a first nano-brick and a second nano-brick are arranged on the top surface of the support layer, the first nano-brick being located on the left side of the upper surface of the support layer, and the second nano-brick being located on the right side of the upper surface of the support layer; the inside of the support layer is provided with a third nano-brick and a fourth nano-brick, the projection center of the third nano-brick on the substrate coincides with the projection center of the first nano-brick on the substrate, and the projection center of the fourth nano-brick on the substrate coincides with the projection center of the second nano-brick on the substrate.

[0011] Preferably, the substrate is made of an aluminum oxide material.

[0012] Preferably, the upper end of the support layer is provided with a hollow cavity of a cover plate, and the support layer is made of fused quartz glass material.

[0013] Preferably, the position distance between the first nano-brick and the third nano-brick is determined according to the wavelength of the incident light, and the position distance between the second nano-brick and the fourth nano-brick is determined according to the wavelength of the incident light.

[0014] Preferably, the first nano-brick, the second nano-brick, the third nano-brick and the fourth nano-brick are made of polysilicon material.

[0015] Preferably, before the incident light is phase-modulated by the double-layer metasurface, the nano-bricks of the double-layer metasurface are optimized by electromagnetic simulation.

[0016] Preferably, when the incident light with a set polarization state is phase-modulated by the double-layer metasurface, the phase modulation is performed based on the first nano-brick, the second nano-brick, the third nano-brick and the fourth nano-brick in the optimized state, comprising:

[0017] The first nano-brick in the parameter optimization state and the second nano-brick in the parameter optimization state are used to select and phase-modulate the incident light by the wavelength-selective metasurface;

[0018] In the transmissive metasurface, the third nano-brick in the parameter optimization state and the fourth nano-brick in the parameter optimization state are combined to phase-modulate the incident light.

[0019] Preferably, the polarization state of the incident light is set, comprising:

[0020] Determining a target polarized light;

[0021] Adjusting the state of the incident light according to the target polarized light, setting the incident light to a target state to obtain a target incident light;

[0022] Stability of the target incident light is monitored, and target incident light correction is performed when the target incident light fluctuates according to the stability monitoring result.

[0023] Preferably, when the prepared polarization state is incident to the double-layer metasurface, the incident angle is corrected according to the position of the viewer, including:

[0024] The position of the viewer is determined, and the viewing field range is obtained based on the position of the viewer, while the image presentation angle of the reflection space and the transmission space is determined;

[0025] The viewing field range is combined with the image presentation angle to analyze the presentation effect deviation, and the viewing visual effect deviation information is obtained;

[0026] The incident light is corrected according to the viewing visual effect deviation information, and the incident light with the prepared polarization state is incident to the double-layer metasurface according to the corrected incident angle.

[0027] The present application realizes full-space color holographic images in reflection space and transmission space through double-layer metasurfaces, which not only doubles the information capacity or function on the same physical area, improves the information storage density, but also enables the observer to see clear holographic images at any angle, expands the visual range of the holographic image, and guarantees the full-space imaging effect, providing a wider space for the application scenarios of holographic display technology. Moreover, the double-space imaging mode can ensure that each part of the image can be accurately presented, avoiding information loss or incomplete conditions caused by single-space imaging, and enhancing the integrity of the image. In addition, in the double-layer metasurface, the wavelength selective metasurface is combined with the transmission metasurface to selectively modulate light of different wavelengths (i.e. light of different colors), accurately control the phase and other parameters of light of different colors as needed, thereby realizing more accurate color reproduction, rich color levels, and thus improving the imaging quality. In addition, the color holographic images on the reflection space and the transmission space can be independently designed and are not related to each other, having higher design freedom.

[0028] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be realized and obtained by the structure particularly pointed out in the application file.

[0029] The technical solutions of the present application will be further described in detail below with the help of the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0030] The accompanying drawings are used to provide a further understanding of the present application, and constitute a part of the specification, together with the embodiments of the present application, to explain the present application, and do not constitute a limitation on the present application. In the drawings:

[0031] Figure 1 Schematic diagram of the method according to the present application;

[0032] Figure 2 Schematic diagram of the minimum structural unit of the metasurface in the method according to the present application;

[0033] Figure 3 Schematic diagram of a portion of the structure of the double-layer metasurface in the method according to the present application;

[0034] Figure 4 Schematic diagram of another portion of the structure of the double-layer metasurface in the method according to the present application;

[0035] Figure 5 Transmittance-reflectance scan of the first nanobrick in the method according to the present application;

[0036] Figure 6 Transmittance-reflectance scan of the third nanobrick in the method according to the present application;

[0037] Figure 7 Transmittance-reflectance scan of the second nanobrick in the method according to the present application;

[0038] Figure 8 Transmittance-reflectance scan of the fourth nanobrick in the method according to the present application;

[0039] Figure 9 Schematic diagram of the phase modulation step in the method according to the present application;

[0040] Figure 10 Phase map of the metasurface array in the reflection space for the first wavelength in the method according to the present application;

[0041] Figure 11 Phase map of the metasurface array in the reflection space for the second wavelength in the method according to the present application;

[0042] Figure 12 Phase map of the metasurface array in the transmission space for the first wavelength in the method according to the present application;

[0043] Figure 13 Phase map of the metasurface array in the transmission space for the second wavelength in the method according to the present application;

[0044] Figure 14 Full-space color holographic image effect diagram in the method according to the present application.

[0045] In the figure, substrate 1, support layer 2, first nanobrick 3, second nanobrick 4, third nanobrick 5, fourth nanobrick 6. DETAILED DESCRIPTION

[0046] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, in which it is understood that the preferred embodiments described below are merely intended to illustrate and explain the present application, and are not intended to limit the present application.

[0047] As shown in the drawings, Figure 1 The embodiment of the present application provides a method for realizing full-space color holography based on a double-layer metasurface, which comprises the following steps:

[0048] Determining incident light and setting the polarization state of the incident light.

[0049] In the step of setting the polarization state of the incident light, the light source system sets the polarization state of the incident light after determining the incident light, and here, the incident light is set as circularly polarized light, and the circularly polarized light comprises light of different wavelengths.

[0050] The set polarization state is incident to the double-layer metasurface.

[0051] Here, the circularly polarized light is incident to the double-layer metasurface, so that the double-layer metasurface adjusts the phase according to the wavelength for the circularly polarized light.

[0052] The incident light with the set polarization state is phase-modulated by the double-layer metasurface to form color holographic images on the reflection space and the transmission space.

[0053] In the method, the double-layer metasurface comprises a wavelength-selective metasurface and a transmission metasurface.

[0054] The above-mentioned double-layer metasurface realizes full-space color holographic images on the reflection space and the transmission space, which not only doubles the information capacity or function on the same physical area, improves the information storage density, but also enables the observer to see clear holographic images at any angle, expands the visual range of the holographic images, guarantees the full-space imaging effect, and provides a wider space for the application scenarios of the holographic display technology. Moreover, the double-space imaging mode can ensure that each part of the image can be accurately presented, avoid information loss or incomplete conditions caused by single-space imaging, and enhance the integrity of the image. In addition, in the double-layer metasurface, the wavelength-selective metasurface is combined with the transmission metasurface to selectively modulate light of different wavelengths (i.e. light of different colors), accurately control the phase and other parameters of light of different colors as needed, thereby realizing more accurate color reproduction, rich color levels, and thus improving the imaging quality. In addition, the color holographic images on the reflection space and the transmission space can be independently designed and irrelevant to each other, and have higher design freedom.

[0055] In some embodiments, as Figure 2As shown, the double-layer metasurface is composed of a plurality of structural unit arrays, the structural unit includes: a substrate 1 and a support layer 2, the support layer 2 is arranged on the substrate 1, the top surface of the support layer 2 is provided with a first nano brick 3 and a second nano brick 4, and the inside of the support layer 2 is provided with a third nano brick 5 and a fourth nano brick 6. The structural unit is divided into a first part and a second part, as shown Figure 3 As shown, in the first part, the first nano brick 3 is located on the left side of the upper surface of the support layer, and the center of the projection of the third nano brick 5 on the substrate coincides with the center of the projection of the first nano brick 3 on the substrate. As shown Figure 4 As shown, the second nano brick 4 is located on the right side of the upper surface of the support layer, and the center of the projection of the fourth nano brick 6 on the substrate coincides with the center of the projection of the second nano brick 4 on the substrate.

[0056] Further, the wavelength selective metasurface is the first nano brick 3 and the second nano brick 4 arranged on the top surface of the support layer 2, and the transmission metasurface is the third nano brick 5 and the fourth nano brick 6 arranged in the inside of the support layer 2, and the wavelength selective metasurface and the transmission metasurface are connected through the support layer 2.

[0057] Further, the substrate 1 is made of aluminum oxide material. The substrate has high refractive index and good optical performance by using aluminum hydride material, which improves the propagation efficiency of incident light in the substrate during light propagation, reduces light loss, and further ensures the optical effect in the reflection space and the transmission space, improves the quality of the color holographic image, and has good mechanical stability and chemical stability, can withstand high temperature and pressure, and ensure that the double metasurface can realize full-space color hologram under various environmental conditions.

[0058] Further, the upper end of the support layer 2 is provided with a hollow cavity of the cover plate, which enhances the integrity of the entire double metasurface structure, reduces the damage of the structure caused by external force or environmental change, improves the mechanical stability and reliability of the metasurface, and also protects the hollow cavity from the influence of the external environment, ensures that the light propagation path and phase modulation in the double metasurface are not disturbed by the external environment, improves the stability and consistency of the optical performance, and ensures the reliability and service life of the double metasurface. Moreover, the hollow cavity can reduce the propagation loss of light in the support layer and improve the light transmittance.

[0059] Further, the support layer 2 is made of fused quartz glass material. The support layer has very high transparency in a wide wavelength range by using fused quartz glass material, effectively reducing light absorption and scattering, improving light transmittance and transmission efficiency, and further improving light utilization efficiency, reducing chromatic aberration, and improving color fidelity of color holographic image.

[0060] Further, the position distance between the first nano-brick 3 and the third nano-brick 5 is determined according to the wavelength of the incident light, and the position distance between the second nano-brick 4 and the fourth nano-brick 6 is determined according to the wavelength of the incident light. Here, the distance between the upper surface of the first nano-brick 3 and the second nano-brick 4 and the lower surface of the corresponding third nano-brick 5 and the fourth nano-brick 6 is half of the wavelength of the incident light, that is, the distance between the upper surface of the first nano-brick 3 and the lower surface of the third nano-brick 5 is half of the wavelength of the incident light, and the distance between the upper surface of the second nano-brick 4 and the lower surface of the fourth nano-brick 6 is half of the wavelength of the incident light. By setting the distance, space is left for phase change when the light passes through, ensuring adjustment of the phase, and setting the distance to half of the wavelength of the incident light enables the metasurface to work in a wide wavelength range, expanding the application range, improving the versatility and flexibility of the dual metasurface, while also reducing the loss of light during propagation, enabling more light to reach the observer's eyes, thereby improving the brightness and contrast of the holographic image.

[0061] Further, the first nano-brick 3, the second nano-brick 4, the third nano-brick 5, and the fourth nano-brick 6 are made of polycrystalline silicon material. By using polycrystalline silicon material, the first nano-brick 3, the second nano-brick 4, the third nano-brick 5, and the fourth nano-brick 6 can adjust light of multiple wavelengths, achieving more accurate phase control, thereby improving the quality and clarity of the holographic image, while also reducing absorption and scattering of light during propagation, improving the utilization efficiency of light, thereby enhancing the brightness and contrast of the holographic image.

[0062] The above-mentioned arrangement of structural units can improve the density of structural units, make the structure of the double-layer metasurface more compact, realize finer wavefront control, and thus produce a holographic image or optical focus with higher resolution and larger viewing angle, improve the quality of the color holographic image, make the visual effect of the color holographic image more realistic, and meanwhile, can fully cover the double-layer metasurface, ensure that the holographic image is uniformly formed in all directions, avoid discontinuity and missing parts of the image, and guarantee the full-space imaging capability. Moreover, the first and second nanobricks 3 and 4 arranged on the top surface of the support layer 2 and the third and fourth nanobricks 5 and 6 arranged inside can realize high-precision phase modulation of the incident light, so that the incident light passing through the double metasurface can improve the quality and definition of the holographic image through phase modulation, guarantee the quality of the color holographic image on the reflection space and transmission space, and meanwhile, the projection center of the third nanobrick 5 on the substrate coincides with the projection center of the first nanobrick 3 on the substrate, and the projection center of the fourth nanobrick 6 on the substrate coincides with the projection center of the second nanobrick 4 on the substrate, which guarantees the cooperation between the first and second nanobricks 3 and 4 and the third and fourth nanobricks 5 and 6 when modulating the phase of light, helps to reduce phase errors, and ensures the quality of the color holographic image. Moreover, by dividing the structural units into the first and second parts, the color holographic image is determined on the reflection space and transmission space respectively, two independent design imaging processes are formed, and the flexibility of realizing full-space color holography based on the double-layer metasurface is improved.

[0063] In some embodiments, before the incident light with a set polarization state is phase-modulated by the double-layer metasurface, electromagnetic simulation is also used to optimize the nanobricks of the double-layer metasurface.

[0064] When the electromagnetic simulation is used to optimize the nanobricks of the double-layer metasurface, the parameters of the first, second, third and fourth nanobricks 3, 4, 5 and 6 are optimized through electromagnetic simulation in combination with the wavelength of the incident light, a simulation model is established for the double-layer metasurface, the first, second, third and fourth nanobricks 3, 4, 5 and 6 are simulated based on the simulation model through the incident light, the geometric parameters of the first, second, third and fourth nanobricks 3, 4, 5 and 6 are optimized, and the first nanobrick 3 in the parameter-optimized state and the second, third and fourth nanobricks 4, 5 and 6 in the parameter-optimized state are obtained.

[0065] When the simulation model is used to simulate the first nano brick 3, the second nano brick 4, the third nano brick 5 and the fourth nano brick 6 respectively by the incident light, the first nano brick 3, the second nano brick 4, the third nano brick 5 and the fourth nano brick 6 are taken as the research objects respectively, and the optimization targets of the first nano brick 3, the second nano brick 4, the third nano brick 5 and the fourth nano brick 6 are determined respectively, and then the optimal values of the geometric parameters of the first nano brick 3, the second nano brick 4, the third nano brick 5 and the fourth nano brick 6 are determined based on the optimization targets, so as to obtain the first nano brick 3 in the parameter optimization state, the second nano brick 4 in the parameter optimization state, the third nano brick 5 in the parameter optimization state and the fourth nano brick 6 in the parameter optimization state. Here, the geometric parameters include the length of the long side of the upper surface, the length of the short side of the upper surface and the height. Specifically as follows:

[0066] When the first nano brick 3 is analyzed, the transmission polarization efficiency and the reflection cross-polarization efficiency are taken as the optimization targets, the reflection and transmission of the first nano brick 3 to the incident light are scanned and analyzed, and the geometric parameters of the first nano brick 3 are determined under the optimal conditions of the transmission polarization efficiency and the reflection cross-polarization efficiency, so as to obtain the optimal values of the length L1 of the long side of the upper surface, the length W1 of the short side of the upper surface and the height H1 of the first nano brick 3, that is, the first nano brick 3 in the parameter optimization state is obtained when the length L1 of the long side of the upper surface, the length W1 of the short side of the upper surface and the height H1 of the first nano brick 3 take the optimal values respectively.

[0067] When the third nano brick 5 is analyzed, the transmission cross-polarization efficiency is taken as the optimization target, the reflection and transmission of the third nano brick 5 to the first wavelength light in the incident light are scanned and analyzed, and the geometric parameters of the third nano brick 5 are determined under the optimal conditions of the transmission cross-polarization efficiency, so as to obtain the optimal values of the length L3 of the long side of the upper surface, the length W3 of the short side of the upper surface and the height H3 of the third nano brick 3, that is, the third nano brick 3 in the parameter optimization state is obtained when the length L3 of the long side of the upper surface, the length W3 of the short side of the upper surface and the height H3 of the third nano brick 3 take the optimal values respectively.

[0068] When the second nano brick 4 is analyzed, the transmission polarization efficiency and the reflection cross-polarization efficiency are taken as the optimization targets, the reflection and transmission of the second nano brick 4 to the incident light are scanned and analyzed, and the geometric parameters of the second nano brick 4 are determined under the optimal conditions of the transmission polarization efficiency and the reflection cross-polarization efficiency, so as to obtain the optimal values of the length L2 of the long side of the upper surface, the length W2 of the short side of the upper surface and the height H2 of the second nano brick 4 in the parameter optimization state, that is, the second nano brick 4 in the parameter optimization state is obtained when the length L2 of the long side of the upper surface, the length W2 of the short side of the upper surface and the height H2 of the second nano brick 4 take the optimal values respectively.

[0069] When analyzing the fourth nanobrick 6, the transmission cross-polarization efficiency is taken as the optimization target, the reflection and transmission of the fourth nanobrick 6 to the second wavelength light in the incident light are scanned and analyzed, the geometric parameters of the fourth nanobrick 6 are determined in the case that the transmission cross-polarization efficiency is optimal, and the optimal values of the long side length L4 of the upper surface, the optimal values of the short side length W4 of the upper surface, and the optimal values of the height H4 of the fourth nanobrick 6 are obtained, that is, the fourth nanobrick 6 in the parameter optimization state is obtained when the long side length L4 of the upper surface, the short side length W4 of the upper surface, and the height H4 of the fourth nanobrick 6 take the optimal values respectively.

[0070] The above-mentioned electromagnetic simulation can accurately simulate the interaction between the double metasurface and the incident light, thereby optimizing the geometric parameters of the nanobrick in the double metasurface, reducing the waste of material resources, and at the same time ensuring that the double metasurface can effectively adjust the phase of the incident light, so that the incident light can be more accurately and effectively phase-adjusted when realizing full-space color holography based on the double-layer metasurface, improving the optical performance of the double-layer metasurface, reducing the trial-and-error cost, and ensuring the quality of the full-space color holography.

[0071] In some embodiments, as shown in FIG. 6, when the double-layer metasurface phase-modulates the incident light with a set polarization state, the first nanobrick 3, the second nanobrick 4, the third nanobrick 5, and the fourth nanobrick 6 in the optimization state are used for phase modulation, including: Figure 9

[0072] S1, using the wavelength-selective metasurface to wavelength-select and phase-modulate the incident light by the first nanobrick 3 in the parameter optimization state and the second nanobrick 4 in the parameter optimization state;

[0073] The incident light is the incident light with a set polarization state. When the wavelength-selective metasurface wavelength-selects the incident light, the target wavelength is determined according to the imaging requirement, and when the incident light with a set polarization state is incident on the double-layer surface, the wavelength-selective metasurface selects the target wavelength by the first nanobrick 3 and the second nanobrick 4 in the parameter optimization state, thereby reflecting and refracting the incident light to obtain the first wavelength reflected light, the first wavelength transmitted light, the second wavelength reflected light, and the second wavelength transmitted light. The first nanobrick 3 reflects the first wavelength incident light and transmits the second wavelength incident light. The second nanobrick 4 reflects the second wavelength incident light and transmits the first wavelength incident light.

[0074] ​For example, the target wavelength range is 625nm-750nm, when the incident light is incident on the double-layer surface, the target incident light and the non-target incident light are determined according to the target wavelength range 625nm-750nm, and the first wavelength incident light and the second wavelength incident light are obtained, then the first nanobrick 3 reflects the first wavelength incident light and transmits the second wavelength incident light, and the second nanobrick 4 reflects the second wavelength incident light and transmits the first wavelength incident light, thereby obtaining the first wavelength reflected light, the first wavelength transmitted light, the second wavelength reflected light and the second wavelength transmitted light.

[0075] When the wavelength selective metasurface selects the target wavelength by the first nanobrick 3 and the second nanobrick 4 in the parameter optimization state, the first nanobrick 3 in the parameter optimization state and the second nanobrick 4 in the parameter optimization state adjust the phase of the first wavelength reflected light and the second wavelength reflected light, respectively, including:

[0076] A spatial rectangular coordinate system is established for the double-layer metasurface, and the spatial coordinates of the first nanobrick 3 in the parameter state and the second nanobrick 4 in the parameter optimization state are converted based on the spatial rectangular coordinate system to obtain the spatial coordinate information of the first nanobrick 3 and the spatial coordinate information of the second nanobrick 4.

[0077] The long side vector of the upper surface of the first nanobrick 3 is determined according to the spatial coordinate information of the first nanobrick 3, and the rotation angle of the first nanobrick 3 is obtained according to the long side vector of the upper surface.

[0078] The long side vector of the upper surface of the second nanobrick 4 is determined according to the spatial coordinate information of the second nanobrick 4, and the rotation angle of the second nanobrick 4 is obtained according to the long side vector of the upper surface.

[0079] The phase modulation amount of the first nanobrick 3 is determined according to the phase modulation relationship of the rotation angle of the first nanobrick 3 to obtain the phase modulation amount of the first wavelength reflected light. Here, when the first wavelength light in the incident light is incident on the first nanobrick 3, the cross-polarized light is obtained, the first wavelength reflected light is obtained, and the polarization state analysis is performed according to the incident light, the first wavelength reflected light and the attribute characteristics of the first nanobrick 3 to determine that there is a relationship as shown in the following formula: e is a natural constant, i is an imaginary unit, is the Jones matrix of the first wavelength light, is the Jones matrix of the first nanobrick 3, is the Jones matrix of the first wavelength reflected light, and the phase modulation relationship of the first nanobrick 3 is obtained as follows: wherein, The phase modulation amount of the first wavelength reflected light is θ1, which is the rotation angle of the first nano-brick 3. According to the rotation angle of the second nano-brick 4, the phase modulation amount is determined according to the phase modulation relationship, and the phase modulation amount of the second wavelength reflected light is obtained. Here, when the second wavelength light in the incident light is incident to the second nano-brick 4, the cross-polarized light is obtained, and the second wavelength reflected light is obtained. According to the incident light, the second wavelength reflected light, and the attribute characteristics of the second nano-brick 4, the polarization state analysis is performed to determine that there is a relationship as shown in where e is a natural constant, and i is an imaginary unit, is the Jones matrix of the second wavelength light, is the Jones matrix of the second nano-brick 4, is the Jones matrix of the second wavelength reflected light, and further the phase modulation relationship of the second nano-brick 4 is: wherein is the phase modulation amount of the second wavelength reflected light, and θ2 is the rotation angle of the second nano-brick 4.

[0080] The phase of the first wavelength reflected light is adjusted according to the phase modulation amount of the first wavelength reflected light, and the holographic image 1 is formed in the reflection space after diffraction. Here, as shown in Figure 10 the phase distribution interval is 0 to 2π, and the phase arrangement diagram obtained in the reflection space is an example of the holographic image 1.

[0081] The phase of the second wavelength reflected light is adjusted according to the phase modulation amount of the second wavelength reflected light, and the holographic image 2 is formed in the reflection space after diffraction. Here, as shown in Figure 11 the phase distribution interval is 0 to 2π, and the phase arrangement diagram obtained in the reflection space is an example of the holographic image 2.

[0082] S2, in the transmission type super surface, the third nano-brick 5 in the parameter optimization state and the fourth nano-brick 6 in the parameter optimization state are combined to perform phase modulation on the incident light.

[0083] wherein when the transmission type super surface combines the third nano-brick 5 in the parameter optimization state and the fourth nano-brick 6 to perform phase modulation on the incident light, the first nano-brick 3 in the parameter optimization state is combined with the third nano-brick 5 in the optimization state to realize the phase modulation of the second wavelength transmission light in the incident light, and the second nano-brick 4 in the parameter optimization state is combined with the fourth nano-brick 6 in the parameter optimization state to realize the phase modulation of the first wavelength transmission light in the incident light.

[0084] When the first nano-brick 3 in the parameter optimization state and the third nano-brick 5 in the parameter optimization state are combined to realize phase modulation of the second wavelength of the transmitted light in the incident light, and the second nano-brick 4 in the parameter optimization state and the fourth nano-brick 6 in the parameter optimization state are combined to realize phase modulation of the first wavelength of the transmitted light in the incident light, a spatial rectangular coordinate system is established for the double-layer metasurface, and spatial coordinate conversion is performed on the geometric parameters of the first nano-brick 3 in the parameter state, the second nano-brick 4 in the parameter optimization state, the third nano-brick 5 in the parameter optimization state, and the fourth nano-brick 6 in the parameter optimization state based on the spatial rectangular coordinate system, to obtain spatial coordinate information of the first nano-brick 3, spatial coordinate information of the second nano-brick 4, spatial coordinate information of the third nano-brick 5, and spatial coordinate information of the fourth nano-brick 6; the long-side vector of the upper surface is determined according to the spatial coordinate information of the first nano-brick 3, the spatial coordinate information of the second nano-brick 4, the spatial coordinate information of the third nano-brick 5, and the spatial coordinate information of the fourth nano-brick 6, and the angle is determined according to the long-side vector of the upper surface to obtain the angle of the first nano-brick 3, the angle of the second nano-brick 4, the angle of the third nano-brick 5, and the angle of the fourth nano-brick 6.

[0085] The third nano-brick 5 is a transmission type, which acts as a half-wave plate on the transmitted light. When the first wavelength of the incident light is incident on the second nano-brick 4, the transmitted light of the first wavelength continues to pass through the fourth nano-brick 6. At this time, according to the attribute characteristics of the incident light combined with the first nano-brick 3 and the third nano-brick 5, the polarization state is analyzed to determine that there is a relationship as shown in wherein e is a natural constant and i is an imaginary unit. is the Jones matrix of the first nano-brick 3, is the Jones matrix of the third nano-brick 5, is the Jones matrix of the incident light, e is a natural constant, and i is an imaginary unit, so that the phase modulation relationship is wherein θ3 is the angle of the third nano-brick 5, θ1 is the angle of the first nano-brick 3, is the phase modulation amount of the transmitted light of the first wavelength, so that diffraction occurs after phase modulation, and a holographic image 3 is formed in the transmission space. For example, as shown in Figure 12 when the angle distribution interval is 0 to 2π, a phase arrangement diagram is obtained in the transmission space.

[0086] The fourth nano-brick 6 is a transmission type, which acts as a half-wave plate on the transmitted light. When the second wavelength of the incident light is incident on the first nano-brick 3, the transmitted light of the second wavelength continues to pass through the third nano-brick 5. At this time, according to the attribute characteristics of the incident light combined with the second nano-brick 4 and the fourth nano-brick 6, the polarization state is analyzed to determine that there is a relationship as shown in wherein e is a natural constant and i is an imaginary unit. is a Jones matrix of the second nano-brick 4, is a Jones matrix of the fourth nano-brick 6, is a Jones matrix of the incident light, and the phase modulation relationship is wherein, θ2 is the rotation angle of the second nano-brick 4, and θ4 is the rotation angle of the fourth nano-brick 6, is the phase modulation amount of the transmitted light of the second wavelength, so that diffraction occurs after phase modulation, and a holographic image 4 is formed in the transmission space. For example, as shown in Figure 13 the angle distribution interval is 0 to 2π, a phase arrangement diagram is obtained in the transmission space.

[0087] Further, the effect reconstruction is performed according to the holographic image 1, the holographic image 2, the holographic image 3 and the holographic image 4, and a full-space color holographic image as shown in Figure 14 is obtained.

[0088] The wavelength selection of the incident light by the first nano-brick 3 and the second nano-brick 4 enables the wavelength selection type super surface to efficiently process specific light, improves the target specificity of the double-layer super surface, and enables the realization of full-space color holography according to the requirements. By establishing a spatial rectangular coordinate system, the parameters of the first nano-brick 3 and the second nano-brick 4 and the third nano-brick 5 and the fourth nano-brick 6 are quantified in a more intuitive coordinate form, which provides convenience for the analysis and calculation of the rotation angle, and ensures the accuracy of the rotation angle of the first nano-brick 3, the rotation angle of the second nano-brick 4, the rotation angle of the third nano-brick 5 and the rotation angle of the fourth nano-brick 6, thereby ensuring the accuracy of the phase modulation amount, realizing the accurate phase modulation of the first wavelength reflected light, the second wavelength reflected light, the first wavelength transmitted light and the second wavelength transmitted light, and ensuring the quality of the color holography. The color and information amount of the holographic image are enriched, the clarity and contrast of the holographic image are improved, and the holographic image is more realistic and lively.

[0089] In some embodiments, the polarization state of the incident light is set, including:

[0090] The target polarized light is determined.

[0091] In the determination of the target polarized light, the target polarization state is determined, for example, circularly polarized light, elliptically polarized light, linearly polarized light, etc. Here, it is generally circularly polarized light.

[0092] The target polarization state is set to the incident light according to the target polarized light, and the target incident light is obtained.

[0093] Wherein, when adjusting and setting the incident light according to the target polarized light, the light source system is automatically set and adjusted, the polarizer is matched for the target polarized light, the target polarizer is determined, the target polarizer is adjusted in the moving process combined with the light source, the target position is determined, then the target polarizer is fixed at the target position, the incident light source is turned on, the incident light is modulated into circularly polarized light by the target polarizer at the target position, and the target incident light is obtained.

[0094] The stability of the target incident light is monitored, and the target incident light is corrected according to the stability monitoring result when the target incident light fluctuates.

[0095] Wherein, when the stability of the target incident light is monitored, the target incident light is locked, the stability detection data information is obtained for the target incident light, and the stability monitoring analysis data is obtained by using a comprehensive analysis algorithm according to the stability detection data information combined with the influence coefficient, then the stability monitoring analysis data is binarized, and the light monitoring result is determined based on the binarization result. The stability detection data information includes various monitoring analysis data, for example: the degree of polarization monitoring data is obtained by a polarimeter or a Stokes parameter measuring instrument, and the degree of polarization change data is obtained according to the degree of polarization monitoring data; the shape of the target incident light is monitored, and the circularity change data and the polarization angle change data are obtained based on the shape analysis; the light intensity of the target incident light is monitored, and the light intensity change data is determined. The influence coefficient is determined by analyzing the data deviation rate according to the deviation analysis of the monitoring analysis data, and the influence coefficient is obtained according to the conversion relationship. The conversion relationship is determined by fitting the data deviation rate and the influence coefficient in advance, for example: when the data deviation rate is 0.1%, the corresponding influence coefficient is 0.999 according to the conversion relationship. In the comprehensive analysis algorithm, the monitoring analysis data is matched and corresponding to the influence coefficient, the monitoring analysis data is adjusted based on the matching and corresponding result using the influence coefficient, then the adjusted data is summarized to obtain the stability monitoring analysis data. When the stability monitoring analysis data is binarized, the binarization conversion is performed combined with the error tolerance factor, the stability monitoring analysis data is converted into a value of 0 or 1, when the binarization data is 0, the light monitoring result is stable, when the binarization data is 1, the light monitoring result is unstable. When the light monitoring result is stable, no correction is needed, when the light monitoring result is unstable, the target incident light is corrected, the distribution of the target incident light is obtained, the polarization state of the target incident light is corrected based on the distribution of the target incident light, the influence of optical noise on the stability of circularly polarized light is reduced, and the target incident light remains stable.

[0096] The above-mentioned setting of the polarization state of the incident light, adjusting and setting the incident light according to the target polarized light so that the target incident light is the required target polarized light, and adjusting the target polarizer during movement in combination with the light source so that the position of the target polarizer is determined in advance, so that the target incident light can be more accurately obtained when generating the target incident light, ensuring the correctness of the target incident light, and thus obtaining a color holographic image with better visual effect in the reflection space and the transmission space. Moreover, by monitoring the stability of the target incident light, the instability of the target incident light can be found in time and accurately, avoiding the instability of the target incident light leading to uneven image presentation of the color holographic image and affecting the visual experience of the viewer, ensuring the visual presentation effect of the color holographic image. And by correcting the target incident light according to the light monitoring result, the target incident light remains stable during the presentation of the color holographic image in the reflection space and the transmission space, ensuring the visual presentation stability of the color holographic image and avoiding bad visual experience for the viewer.

[0097] In some embodiments, when the set polarization state is incident to the double-layer metasurface, the incident angle is also corrected in combination with the position of the viewer, including:

[0098] The position of the viewer is determined, and the viewing field range is obtained based on the position of the viewer, and the image presentation viewing angle of the reflection space and the transmission space is determined.

[0099] Wherein, when determining the position of the viewer, if there is a specific viewer, the number of viewers is determined, when the number of viewers is one, the position of the viewer is obtained, the viewing field range is analyzed based on the position of the viewer, and the viewing field range is determined, when the number of viewers is multiple, the position of the viewer is obtained, the distribution of the viewers is analyzed according to the position of the viewer using a clustering analysis algorithm, multiple viewer distribution clusters are obtained, and the main area is determined according to the viewer distribution cluster, the main area is quantized to obtain a target analysis point, the viewing field range is analyzed based on the target analysis point, and the viewing field range is determined.

[0100] When determining the image presentation viewing angle of the reflection space and the transmission space, the presentation angle of the color holographic image in the reflection space and the transmission space is analyzed, the presentation viewing angle of the color holographic image in the reflection space and the transmission space is determined, and the image presentation viewing angle of the reflection space and the transmission space is obtained.

[0101] The viewing visual effect deviation information is obtained by analyzing the presentation effect deviation of the viewing field range in combination with the image presentation viewing angle.

[0102] The viewing field range is combined with the image presentation visual angle to perform presentation effect deviation analysis, the optimal viewing area is determined according to the image presentation visual angle, a relationship diagnosis model is used to perform position relationship diagnosis analysis according to the optimal viewing area and the viewing field range, the relationship between the optimal viewing area and the viewing field range is determined, and the relationship includes containing and being contained, partial overlap, and no intersection. The relationship diagnosis model is a neural network model obtained by feature training based on the relationship in advance. After the relationship between the optimal viewing area and the viewing field range is determined, the critical information of the optimal viewing area and the viewing field range is obtained when the relationship between the optimal viewing area and the viewing field range is no intersection according to the relationship between the optimal viewing area and the viewing field range, deviation analysis is performed according to the critical information, viewing visual deviation information is obtained, visual impact effects caused by the viewing visual deviation information are determined, and viewing visual effect deviation information is obtained.

[0103] The incident angle of the incident light is corrected according to the viewing visual effect deviation information, and the incident light with the set polarization state is incident to the double-layer metasurface according to the corrected incident angle.

[0104] When the incident angle of the incident light is corrected according to the viewing visual effect deviation information, it is determined according to the viewing visual effect deviation information whether the incident angle needs to be corrected. If the visual impact effect exceeds the analysis and judgment standard, the incident angle needs to be corrected. At this time, the original incident angle of the incident light is taken as a reference, the incident angle correction information is determined according to the viewing visual deviation information according to the incident angle correction rule, and then the target correction result is determined by combining the reference and the incident angle correction information, so that the incident light with the set polarization state is adjusted according to the target correction result and then incident to the double-layer metasurface. Here, the analysis and judgment standard is a threshold value related to the visual impact effect. For example, the analysis and judgment standard is 20%, if the visual impact effect is greater than 20%, the incident angle needs to be corrected, otherwise, the incident angle does not need to be corrected.

[0105] The above-mentioned incident angle revision by combining the position of the viewer enables the viewer to better experience the visual effect when viewing the color holographic image in the reflection space and the transmission space, guarantees the presentation effect of the color holographic image, avoids the viewer seeing a distorted or defective color holographic image, and brings better visual effect to the viewer. By analyzing the viewer visual deviation information according to the viewing field range combined with the image presentation visual angle of the reflection space and the transmission space, the relative relationship between the viewing field range and the image presentation visual angle of the reflection space and the transmission space is determined, the reflection space and the transmission space repeatedly consider the situation of the viewer when presenting the color holographic image, the flexibility of the color holographic image presentation is improved, the presentation effect of the color holographic image is ensured, and the visual experience of the viewer is improved.

[0106] It will be understood by those skilled in the art that the first, second, third and fourth are merely referring to different stages of application.

[0107] Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the concepts disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the disclosure being indicated by the following claims.

[0108] It is to be understood that the disclosure is not limited to the precise structures herein described and illustrated in the drawings, and that various modifications and changes can be made without departing from its scope. The scope of the disclosure is limited only by the claims that follow.

Claims

1. A method for realizing full-space color holography based on a double-layer metasurface, characterized in that, include: Determine the incident light and set its polarization state; The pre-set polarization state is incident onto the bilayer metasurface; Phase modulation of incident light with a pre-defined polarization state is achieved by using a double-layer metasurface to form color holographic images in both the reflection and transmission spaces. Among them, the double-layer metasurface includes: wavelength-selective metasurface and transmissive metasurface.

2. The method according to claim 1, characterized in that, The double-layer metasurface is composed of an array of multiple structural units, each of which includes a substrate (1) and a support layer (2). The support layer (2) is disposed on the substrate (1) and connects the wavelength-selective metasurface and the transmissive metasurface. A first nanobrick (3) and a second nanobrick (4) are disposed on the top surface of the support layer (2). The first nanobrick (3) is located on the left side of the upper surface of the support layer, and the second nanobrick (4) is located on the right side of the upper surface of the support layer. A third nanobrick (5) and a fourth nanobrick (6) are disposed inside the support layer (2). The projection center of the third nanobrick (5) on the substrate coincides with the projection center of the first nanobrick (3) on the substrate, and the projection center of the fourth nanobrick (6) on the substrate coincides with the projection center of the second nanobrick (4) on the substrate.

3. The method according to claim 2, characterized in that, The substrate (1) is made of alumina material.

4. The method according to claim 2, characterized in that, The upper end of the support layer (2) is provided with a hollow cavity with a cover plate, and the support layer (2) is made of fused silica glass.

5. The method according to claim 2, characterized in that, The positional distance between the first nanobrick (3) and the third nanobrick (5) is determined according to the wavelength of the incident light, and the positional distance between the second nanobrick (4) and the fourth nanobrick (6) is determined according to the wavelength of the incident light.

6. The method according to claim 2, characterized in that, The first nanobrick (3), the second nanobrick (4), the third nanobrick (5) and the fourth nanobrick (6) are made of polycrystalline silicon material.

7. The method according to claim 1, characterized in that, Before using a bilayer metasurface to modulate the phase of incident light, electromagnetic simulation was used to optimize the bilayer metasurface using nanobricks.

8. The method according to claim 2, characterized in that, When phase modulation of incident light with a pre-defined polarization state is performed using a double-layer metasurface, phase modulation is performed based on the first nanobrick (3), second nanobrick (4), third nanobrick (5), and fourth nanobrick (6) in an optimized state, including: Wavelength-selective metasurfaces are used to perform wavelength selection and phase modulation on incident light using the first nanobrick (3) under parameter optimization and the second nanobrick (4) under parameter optimization. In a transmissive metasurface, the incident light is phase-modulated by combining the third nanobrick (5) under parameter optimization and the fourth nanobrick (6) under parameter optimization.

9. The method according to claim 1, characterized in that, Setting the polarization state of the incident light includes: Determine the target polarized light; Adjust the state of the incident light according to the target polarization light, set the incident light to the target state, and obtain the target incident light; Monitor the stability of the incident light from the target, and correct the incident light when fluctuations occur based on the stability monitoring results.

10. The method according to claim 1, characterized in that, When the pre-set polarization state is incident on the bilayer metasurface, the incident angle is also corrected based on the viewer's position, including: Determine the position of the viewer and obtain the viewing field of view based on the viewer's position, while determining the image presentation angle in the reflection space and the transmission space; By combining the viewing field of view with the image presentation angle, a presentation effect deviation analysis is performed to obtain viewing visual effect deviation information; The incident light is corrected for the incident angle based on the visual effect deviation information, and the incident light with the set polarization state is incident onto the double-layer metasurface according to the corrected incident angle.

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