Nano-printing angle multiplexing method and system based on phase holography

Abstract

The present invention discloses a nano-printing angle multiplexing method based on phase-type holography, comprising the following steps: S1, acquiring different target grayscale images and compensating the image intensities accordingly; S2, combining the object light amplitude distribution of the compensated grayscale images with a preset periodic phase distribution to form different object lights, and then interfering and superimposing each with a preset reference light to obtain a corresponding phase-type holographic phase distribution; S3, secondary encoding each phase-type holographic phase distribution into a selected multiplexing angle to obtain a final printing angle multiplexing phase distribution, where each multiplexing angle corresponds to an observation angle; S4, determining the angular arrangement of nanobricks based on the final printing angle multiplexing phase distribution. The present invention enables different observation angles to correspond to different images, enabling switching of displayed images by transforming information channels (i.e., transforming the observation angle).

Description

Technical Field

[0001] The present invention belongs to the field of information optics technology, and in particular relates to a nano-printing angle multiplexing method and system based on phase-type holography. Background Art

[0002] As a novel image display technology, supersurface nanoprinting has attracted more and more attention due to its unique and superior technical characteristics, and has become one of the important research contents of modern image display technology.

[0003] Traditional metasurface nanoprinting mostly uses polarization modulation for grayscale image display. According to Malus's theorem, linear polarization in different polarization directions produces different intensities, thus achieving the purpose of grayscale nanoprinting. However, existing metasurface grayscale nanoprinting schemes are mostly based on polarization modulation of light. For polarization modulation nanoprinting schemes, although precise grayscale control can be achieved, this polarization modulation-based nanoprinting cannot be observed in an output direction that is not perpendicular to the metasurface, and it cannot achieve angle multiplexing. There are technical limitations that will hinder the practical application of ultra-high-resolution metasurface nanoprinting. This technical limitation needs to be addressed urgently.

[0004] In addition, this grayscale nanoprinting technology based on polarization modulation requires external polarization modulation optical devices - polarizers, analyzers and wave plates. These additional polarization modulation devices will greatly reduce the structural compactness of the metasurface printing solution and affect its integration. This is contrary to the demand for image display in daily life and will hinder the application of metasurface nanoprinting solutions in real life.

[0005] Phase, as one of the important optical parameters, has not yet been used in the angle-reuse nanoprinting scheme based on metasurfaces, which is a blank in this field. The angle-reuse nanoprinting scheme based on phase-type holography can achieve grayscale control without additional optical devices. Combining it with metasurface geometric phase modulation can realize a new nanoprinting angle-reuse scheme. This feature makes the nanoprinting angle-reuse scheme based on phase-type holography have high application prospects and practical value. Summary of the Invention

[0006] The main purpose of the present invention is to provide a multi-angle grayscale image multiplexing method and system based on phase-type holographic nano-printing, which can realize the switching of displayed images by changing the observation angle.

[0007] The technical solution adopted in the present invention is:

[0008] A nano-printing angle multiplexing method based on phase holography is provided, characterized in that it includes the following steps:

[0009] S1, obtaining different target grayscale images and performing corresponding compensation on the image intensity;

[0010] S2, combining the object light amplitude distribution of the compensated grayscale image and the preset periodic phase distribution into different object lights, and then interfering and superimposing them with the preset reference light to obtain corresponding phase-type holographic phase distribution;

[0011] S3, re-encoding each phase-type holographic phase distribution into a selected multiplexing angle to obtain a final printed angle multiplexing phase distribution, where each multiplexing angle corresponds to an observation angle;

[0012] S4. Determine the angular arrangement of the nanobricks based on the final printing angle multiplexing phase distribution.

[0013] Following the above technical solution, the number of grayscale images and nano-printing observation angles is the same.

[0014] Following the above technical solution, step S1 specifically includes:

[0015] S11, reading grayscale information of different target images and normalizing it to obtain grayscale information of different target images;

[0016] S12. Select reference light and perform corresponding compensation on the intensities of different target images to obtain compensated object light amplitude distribution.

[0017] Following the above technical solution, step S3 specifically includes:

[0018] S31, selecting a multiplexing angle according to different observation angles, and determining the corresponding multiplexing angle phase distribution;

[0019] S32, performing secondary encoding on the phase-type holographic phase distribution and the multiplexed angle phase distribution to obtain a final printed angle multiplexed phase distribution.

[0020] Following the above technical solution, the method also includes the following steps: when simulating using an electromagnetic simulation tool, left-handed circularly polarized light is vertically incident on the combination of the reflective dielectric metasurface nanobrick and the substrate, and the conversion efficiency of the reflected right-handed circularly polarized light is optimized to find a set of geometric parameters with the highest cross-polarization conversion efficiency and the lowest co-polarization conversion efficiency.

[0021] Following the above technical solution, step S4 is specifically as follows: adjust the rotation angle of the nanobrick unit to be equal to half of the size of the corresponding unit printing angle multiplexing phase distribution, and the amplitude distribution is uniform, and the nanobrick unit after geometric parameter optimization is arranged on the silica substrate according to the final printing angle multiplexing phase distribution, and the silica substrate is placed on the silicon substrate.

[0022] Following the above technical solution, if there are two different observation angles, the nano-printing angle multiplexing method includes the following steps:

[0023] Read the grayscale information of the two target images and normalize them to obtain the grayscale information of different target images I1(x,y) and I2(x,y);

[0024] Select the reference light and compensate for the intensity of different target images respectively. According to the Fourier series expansion formula of the phase grating and the different target image intensities, the inverse function of the first-order Bessel function is used for compensation to obtain the corresponding object light amplitude distribution A1(x,y) and A2(x,y) after compensation:

[0025]

[0026]

[0027] Where R is the amplitude distribution of the reference light, J0 is the first kind zero-order Bessel function;

[0028] The compensated object light amplitude distribution and periodic phase distribution The two different object beams are combined into two different beams, which are interfered and superimposed with the reference beam in succession to obtain the phase-type holographic phase distribution. and It can be expressed as:

[0029]

[0030]

[0031] Among them, I f1 (x,y) and I f2 (x,y) is the intensity distribution after interference superposition, is the periodic phase distribution of the object light;

[0032] According to the selected multiplexing coding angles θ1 and θ2, the corresponding phase distributions α1(x,y) and α2(x,y) are determined; then compared with the phase distribution of the phase type hologram and Perform secondary encoding to obtain the final phase distribution

[0033]

[0034] According to the final phase distribution Determine the angular arrangement of nanobricks in a reflective dielectric metasurface nanobrick array.

[0035] The present invention also provides a nano-printing angle multiplexing system based on phase holography, comprising:

[0036] Grayscale image compensation module, used to obtain different target grayscale images and compensate the image intensity accordingly;

[0037] The phase modulation encoding module is used to combine the object light amplitude distribution of the compensated grayscale image with the preset periodic phase distribution into different object lights, and then perform interference superposition with the preset reference light to obtain the corresponding phase-type holographic phase distribution;

[0038] Angle multiplexing encoding module, used to encode each phase-type holographic phase distribution into the selected multiplexing angle to obtain the final printed angle multiplexing phase distribution, where each multiplexing angle corresponds to an observation angle;

[0039] The nanobrick arrangement module is used to determine the angular arrangement of the nanobricks according to the final printing angle multiplexing phase distribution.

[0040] Following the above technical solution, the system also includes a nanobrick optimization module, which is used to optimize the geometric parameters of the nanobricks in the reflective dielectric nanobrick array according to the performance requirements of an equivalent micro half-wave plate, where the operating wavelength of the micro half-wave plate is in the visible light band; the geometric parameters make the cross-polarization conversion efficiency of the nanobrick array the highest and the co-polarization conversion efficiency the lowest.

[0041] The present invention also provides a storage medium storing a computer program for executing the nano-printing angle multiplexing method based on phase-type holography described in the above technical solution.

[0042] The beneficial effects of the present invention are as follows: the present invention encodes the image grayscale information based on the metasurface phase modulation principle to obtain a phase-type holographic phase distribution, and then encodes it twice into the corresponding observation angle to obtain the final printed angle multiplexing phase distribution. Finally, the angular arrangement of the nanobricks is determined according to the phase distribution, so that different observation angles correspond to different images, and the display image is switched by changing the information channel (i.e., changing the observation angle). BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0044] Figure 1 It is a structural diagram of an embodiment of the present invention;

[0045] Figure 2 is the intensity information of two different target images in a specific embodiment;

[0046] Figure 3 1 is the amplitude distribution (a) and phase distribution (b) of the object light after compensation in a specific embodiment;

[0047] Figure 4 is the phase distribution calculated respectively under the interferometric recording in a specific implementation mode;

[0048] Figure 5 is the final phase distribution obtained by angle multiplexing encoding in a specific implementation manner;

[0049] Figure 6 is a schematic diagram of the dielectric nanobrick unit structure in a specific embodiment;

[0050] Figure 7 is a schematic diagram of the polarization conversion efficiency of a dielectric nanobrick unit in a specific embodiment;

[0051] In the figure, 1-silicon nanobrick unit, 2-silicon dioxide substrate, 3-silicon substrate. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0053] The present invention uses a nano-printing angle multiplexing method based on phase-type holography to encode required multiplexed image information according to information channels (different observation angles).

[0054] like Figure 1 As shown, the nano-printing angle multiplexing method based on phase holography in an embodiment of the present invention includes the following steps:

[0055] S1. Record different grayscale image information through interference based on the principle of phase holography;

[0056] S2, encoding the image grayscale information after interference recording based on the metasurface phase modulation principle to obtain a phase-type holographic phase distribution;

[0057] S3, re-encoding the phase-type holographic phase distribution into the corresponding observation angle to obtain the final printed angle-multiplexed phase distribution, where different observation angles correspond to different grayscale images;

[0058] S4. Determine the angular arrangement of the nanobricks based on the final printing angle multiplexing phase distribution.

[0059] Taking the nano-printing angle multiplexing of two different images as an example, step S1 mainly includes the following steps:

[0060] S11, read the grayscale information I1 and I2 of different target images, such as Figure 2As shown; specifically, the grayscale information contained in the target image can be read by a computer, and then normalized to obtain normalized grayscale information I1(x, y) and I2(x, y) of different target images.

[0061] S12, selecting reference light and performing corresponding compensation for the intensities of different target images;

[0062] Step S12 is specifically as follows:

[0063] According to the Fourier series expansion formula of the phase grating and different target image intensities, the inverse function of the first-order Bessel function is used for compensation to obtain the corresponding amplitude distribution A1(x, y) and A2(x, y), as shown in Figure 2. Figure 3 As shown:

[0064]

[0065]

[0066] Wherein, A1 and A2 are the amplitude distributions of the object light after compensation, R is the amplitude distribution of the reference light, and J0 is the first kind zero-order Bessel function.

[0067] Step S13 is specifically as follows:

[0068] The compensated object beam amplitude distribution (A1(x,y) and A2(x,y)) and periodic phase distribution They are combined into two different object beams, which are interfered and superimposed with the reference beam to obtain the intensity distribution of the interference fringes I f1 (x,y) and I f2 (x, y); According to the phase hologram recording principle, the intensity distribution of the interference fringe is converted into the corresponding phase distribution, and the obtained phase type holographic phase distribution is and like Figure 4 As shown, it can be expressed as:

[0069]

[0070] Among them, I f1 (x,y) and I f2 (x,y) is the intensity distribution after interference superposition, is the periodic phase distribution of the object light.

[0071] Step S3 performs a secondary encoding operation based on the calculated phase-type holographic phase distribution and the multiplexed coding angle distribution (θ1 and θ2) to obtain the final phase distribution.

[0072] Specifically: according to the selected multiplexing angles θ1 and θ2, the corresponding phase distributions α1(x, y) and α2(x, y) are determined; then according to the calculated phase type holographic phase distribution and Secondary encoding obtains the final phase distribution like Figure 5 shown.

[0073]

[0074] In another embodiment of the present invention, before determining the angular arrangement of the nanobricks, the step is further included: optimizing the geometric parameters of the dielectric nanobricks in the reflective nanobrick array according to the performance requirements of the half-wave plate, wherein the operating wavelength is the visible light band.

[0075] By optimizing the geometric parameters of the silicon nanobricks, the phase delay along their major and minor axes is equal to π, while the amplitude is maximized. This means that the combination of the silicon nanobricks, silica substrate, and silicon substrate is equivalent to a miniature half-wave plate. A half-wave plate has a strong phase control capability. When left-handed circularly polarized light passes through a miniature half-wave plate with a rotation angle of α, it is phase-modulated by the nanobricks and converted into right-handed circularly polarized light with the opposite rotation direction, with an additional phase delay of ±2α. This is the principle of geometric phase modulation of the metasurface in this invention.

[0076] This step is specifically as follows:

[0077] Using electromagnetic simulation tools, left-handed circularly polarized light is incident perpendicularly on a reflective dielectric nanobrick and substrate combination. The optimization objective is to find a set of geometric parameters that maximize cross-polarization conversion efficiency and minimize co-polarization conversion efficiency, focusing on the nanobrick's length (L), width (W), height (H), and period (C). This step is accomplished using existing electromagnetic simulation software platforms. Cross-polarization refers to the conversion of left-handed circularly polarized light into right-handed circularly polarized light, or vice versa. Co-polarization refers to the unchanged handedness of left-handed or right-handed circularly polarized light.

[0078] In this embodiment, the optimized geometric parameters 1 are: L = 200nm, W = 100nm, H = 220nm, C = 300nm, where L, W, H, and C refer to the length, width, height, and period of the dielectric nanobricks in the reflective nanobrick array, respectively. Under these geometric parameters, the broadband response and polarization conversion efficiency curves of the dielectric nanobricks in the reflective nanobrick array are shown in Fig. Figure 7 .

[0079] This invention uses a metasurface material as the information carrier for image display. The metasurface consists of a substrate and a periodically arranged array of nanobrick units. Its operating mode is either reflection or transmission (depending on the specific performance requirements), its operating distance is the surface of the metasurface material, and its operating wavelength covers the entire visible light band.

[0080] The dielectric nanobrick array consists of subwavelength dielectric nanobricks arranged in an array on a substrate. The azimuth angle is the angle between the long axis of the dielectric nanobrick and the X-axis, where the X-axis is the length of the substrate. The number of nanobricks in a nanobrick array unit is equal to the number of pixels in the target image. The rotation angle of each nanobrick is determined by the calculated phase distribution of the phase hologram, and the structural size of each nanobrick is determined by the color information of the target image.

[0081] Figure 6 The structure of the dielectric working unit is shown, which consists of a silicon dioxide substrate and a silicon substrate with a period size of C, and a silicon nanobrick with a length of L, a width of W, and a height of H. The projections of the centers of the silicon nanobrick unit 1, the silicon dioxide substrate 2, and the silicon substrate 3 on the XOY plane coincide. The coordinate system adopted by the present invention is based on the X-axis and Y-axis directions of the length and width of the substrate, respectively, and the Z-axis direction of the height of the substrate. The XOY plane is the plane where the upper surface of the substrate is located. By optimizing the geometric parameters of the silicon nanobrick, the polarization conversion efficiency of the silicon nanobrick is very high. For an anisotropic nanostructure, it has a phase control function. When left-handed circularly polarized light passes through an anisotropic nanostructure with a rotation angle of α, it will be phase modulated by the nanobrick and converted into right-handed circularly polarized light with the opposite rotation direction, and a phase delay of ±2α is added. This is the geometric phase modulation principle of the metasurface in the present invention.

[0082] Step S4 mainly determines the angular arrangement of nanobricks in the dielectric metasurface nanobrick array based on the calculated phase distribution. Specifically:

[0083] According to the final printing angle multiplexing phase distribution, the rotation angle β(x,y) of the nanobrick unit is equal to the corresponding unit phase Half the size, that is:

[0084]

[0085] The amplitude distribution is uniform, and the optimized nanobrick units are arranged on the silicon dioxide substrate according to the phase distribution and the corresponding relationship, and the silicon dioxide substrate is placed on the silicon substrate.

[0086] In this embodiment, the number of nanobricks in the dielectric nanobrick array is consistent with the number of pixels of the target image, that is, one nanobrick unit corresponds to one pixel of the target image. In this embodiment, the target image size is selected to be 500*500 pixels.

[0087] In the above embodiment, for encoding image information within the information channel, the image information is encoded into the zeroth order of the phase hologram. The design of the phase hologram simulates the interference recording method of traditional phase holography. The interference superposition of two light waves is simulated and recorded in a computer, and the target image is converted into a corresponding phase distribution. The phase holograms corresponding to different target images are then re-multiplexed and encoded according to the set observation angle to obtain the final phase distribution. The nanobrick array is arranged according to this final phase distribution. When natural light shines on the dielectric metasurface nanobricks carrying the phase distribution, the outgoing light is composed of the zeroth order diffraction orders of different phase holograms. The different zeroth order diffraction lights serve as the information channels for image display. All non-zeroth order diffraction lights of the phase hologram will become evanescent waves and cannot propagate to the far field. The reproduced light has a uniform intensity distribution, equal amplitude distribution, and equal phase distribution.

[0088] To achieve nano-printing angle multiplexing of three different images, that is, to achieve three-channel multiplexing, it is roughly the same as the two-channel multiplexing scheme in the above embodiment. The first step is to compensate according to the selected grayscale image to obtain A1(x,y), A2(x,y) and A3(x,y); the second step is to encode the compensated grayscale image into the corresponding phase distribution to obtain and The third step is to select the angles θ1, θ2 and θ3 of the information channel to be encoded and encode them to obtain the final phase distribution:

[0089]

[0090] The remaining steps are basically the same as the above two channels.

[0091] The same applies to more channels, which will not be elaborated here.

[0092] The present invention further provides a nano-printing angle multiplexing system based on phase holography, for implementing the above method embodiment, the system comprising:

[0093] Grayscale image compensation module, used to obtain different target grayscale images and compensate the image intensity accordingly;

[0094] The phase modulation encoding module is used to combine the object light amplitude distribution of the compensated grayscale image with the preset periodic phase distribution into different object lights, and then perform interference superposition with the preset reference light to obtain the corresponding phase-type holographic phase distribution;

[0095] Angle multiplexing encoding module, used to encode each phase-type holographic phase distribution into the selected multiplexing angle to obtain the final printed angle multiplexing phase distribution, where each multiplexing angle corresponds to an observation angle;

[0096] The nanobrick arrangement module is used to determine the angular arrangement of the nanobricks according to the final printing angle multiplexing phase distribution.

[0097] Furthermore, the system also includes a nanobrick optimization module, which is used to optimize the geometric parameters of the nanobricks in the reflective dielectric nanobrick array according to the performance requirements of an equivalent micro half-wave plate, where the operating wavelength of the micro half-wave plate is the visible light band; the geometric parameters make the cross-polarization conversion efficiency of the nanobrick array the highest and the co-polarization conversion efficiency the lowest.

[0098] The functions of each module correspond to those in the above method embodiment and will not be described in detail here.

[0099] The present invention also provides a computer-readable storage medium, such as a flash memory, a hard disk, a multimedia card, a card-type memory (e.g., SD or DX memory), a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a programmable read-only memory (PROM), a magnetic memory, a disk, an optical disk, a server, an App store, etc., storing a computer program that, when executed by a processor, implements corresponding functions. The computer-readable storage medium of this embodiment, when executed by a processor, is used to implement the phase-type holographic nanoprinting angle multiplexing method of the method embodiment.

[0100] In summary, the present invention combines the design method of phase-type holography with the geometric phase modulation of metasurfaces to realize a new nano-printing angle multiplexing scheme based on phase-type holography, which realizes multi-angle grayscale image multiplexing display while ensuring the compactness of the structure - that is, without adding any additional optical devices. Moreover, as an emerging optical material, metasurfaces have attracted more and more attention for their superior optical properties. The subwavelength structural size can produce diffracted light with a higher spatial frequency, which is more convenient for realizing grayscale modulation through the zero-order diffracted light of the phase-type holography, and can eliminate the influence of non-zero-order diffracted light on the image display channel. Moreover, the metasurface processing technology is mature, the structure is simple, and it is easy to replicate, making it an excellent choice for nano-printing angle multiplexing schemes based on phase-type holography.

[0101] Compared with existing grayscale display technology and near-field image angle multiplexing solutions, the nano-printing angle multiplexing solution based on phase holography has the following advantages and positive effects:

[0102] (1) The resolution of the displayed image is extremely high;

[0103] (2) The image can be directly observed by the naked eye without the assistance of additional optical devices, ensuring the ultra-high integration of metasurface devices;

[0104] (3) The nano-printing angle multiplexing scheme based on phase-type holography fills the gap in the field of phase modulation of nano-printing angle multiplexing technology, making it applicable to more application scenarios;

[0105] (4) The phase algorithm in the present invention is simple to calculate, does not require a multi-step iterative algorithm, and has very low computational requirements;

[0106] (5) The phase-type holographic nanoprinting angle multiplexing scheme of the present invention provides a multiplexing mode that cannot be achieved by traditional nanoprinting, namely angle multiplexing, which realizes the switching of display images by changing the observation angle;

[0107] (6) Angle multiplexing technology has more information channels, a simpler multiplexing method, and can store more information.

[0108] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all such improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A nano-printing angle multiplexing method based on phase holography, characterized in that: The following steps are involved: S1, obtaining different target grayscale images and performing corresponding compensation on the image intensity; S2, combining the object light amplitude distribution of the compensated grayscale image and the preset periodic phase distribution into different object lights, and then interfering and superimposing them with the preset reference light to obtain corresponding phase-type holographic phase distribution; S3. Selecting a multiplexing angle according to different observation angles, determining the corresponding multiplexing angle phase distribution, and re-encoding each phase-type holographic phase distribution into the selected multiplexing angle to obtain the final printing angle multiplexing phase distribution, where each multiplexing angle corresponds to one observation angle; S4, determining the angular arrangement of the nanobricks according to the final printing angle multiplexing phase distribution; If there are two different observation angles, the nano-printing angle multiplexing method includes the following steps: Read the grayscale information of the two target images and normalize them to obtain the grayscale information of different target images; A reference light is selected and the intensity of different target images is compensated accordingly. Based on the Fourier series expansion formula of the phase grating and different target image intensities, the inverse function of the first-order Bessel function is used for compensation to obtain the corresponding object light amplitude distribution after compensation. The compensated object beam amplitude distribution and periodic phase distribution are combined into two different object beams, which are interfered and superimposed with the reference beam to obtain the phase-type holographic phase distribution. The corresponding phase distribution is determined according to the selected multiplexing coding angle, and then secondary encoded with the phase-type holographic phase distribution to obtain the final phase distribution; According to the final phase distribution, the angular arrangement of nanobricks in the reflective dielectric metasurface nanobrick array is determined.

2. The nano-printing angle multiplexing method based on phase holography according to claim 1, characterized in that: The number of grayscale images and nanoprinting observation angles is the same.

3. The nano-printing angle multiplexing method based on phase holography according to claim 1, characterized in that: Step S1 specifically includes: S11, reading grayscale information of different target images and normalizing it to obtain grayscale information of different target images; S12. Select reference light and perform corresponding compensation on the intensities of different target images to obtain compensated object light amplitude distribution.

4. The nano-printing angle multiplexing method based on phase holography according to claim 1, characterized in that: The method also includes the following steps: when simulating using an electromagnetic simulation tool, vertically incident left-handed circularly polarized light on a combination of a reflective dielectric metasurface nanobrick and a substrate, optimizing the conversion efficiency of reflected right-handed circularly polarized light, and finding a set of geometric parameters with the highest cross-polarization conversion efficiency and the lowest co-polarization conversion efficiency.

5. The nano-printing angle multiplexing method based on phase holography according to claim 4, characterized in that: Step S4 is specifically as follows: adjusting the rotation angle of the nanobrick unit to be equal to half of the size of the corresponding unit printing angle multiplexing phase distribution, and the amplitude distribution is uniform, and the nanobrick unit after geometric parameter optimization is arranged on the silica substrate according to the final printing angle multiplexing phase distribution, and the silica substrate is placed on the silicon substrate.

6. A nano-printing angle multiplexing system based on phase holography, characterized in that: include: Grayscale image compensation module, used to obtain different target grayscale images and compensate the image intensity accordingly; The phase modulation encoding module is used to combine the object light amplitude distribution of the compensated grayscale image with the preset periodic phase distribution into different object lights, and then perform interference superposition with the preset reference light to obtain the corresponding phase-type holographic phase distribution; Angle multiplexing encoding module, used to select multiplexing angles according to different observation angles, determine the corresponding multiplexing angle phase distribution, and re-encode each phase-type holographic phase distribution into the selected multiplexing angle to obtain the final printed angle multiplexing phase distribution. Each multiplexing angle corresponds to one observation angle. A nanobrick arrangement module is used to determine the angular arrangement of nanobricks based on the final printing angle multiplexing phase distribution; If there are two different observation angles, the nano-printing angle multiplexing system performs the following steps: Read the grayscale information of the two target images and normalize them to obtain the grayscale information of different target images; A reference light is selected and the intensity of different target images is compensated accordingly. Based on the Fourier series expansion formula of the phase grating and different target image intensities, the inverse function of the first-order Bessel function is used for compensation to obtain the corresponding object light amplitude distribution after compensation. The compensated object beam amplitude distribution and periodic phase distribution are combined into two different object beams, which are interfered and superimposed with the reference beam to obtain the phase-type holographic phase distribution. The corresponding phase distribution is determined according to the selected multiplexing coding angle, and then secondary encoded with the phase-type holographic phase distribution to obtain the final phase distribution; According to the final phase distribution, the angular arrangement of nanobricks in the reflective dielectric metasurface nanobrick array is determined.

7. The nano-printing angle multiplexing system based on phase holography according to claim 6, characterized in that: The system also includes a nanobrick optimization module for optimizing the geometric parameters of the nanobricks in the reflective dielectric nanobrick array based on the performance requirements of an equivalent micro half-wave plate, where the operating wavelength of the micro half-wave plate is in the visible light band; the geometric parameters make the cross-polarization conversion efficiency of the nanobrick array the highest and the co-polarization conversion efficiency the lowest.

8. A storage medium, characterized in that: A computer program is stored therein, which executes the nano-printing angle multiplexing method based on phase-type holography according to any one of claims 1 to 5.

Images