A design method and system of polarization multiplexing metasurface optics for 3D imaging

Abstract

The application provides a design method and system of polarization multiplexing metasurface optics for 3D imaging, a plurality of projection planes or projection light fields are formed at intervals di outside the metasurface optics, di is the distance from the metasurface optics to different angle polarization projection planes; the phase distribution of each projection plane or projection light field is optimized, each is recorded as phase distribution i, and the phase interval is 0 to 2*pi; the phase distribution i of each different angle linear polarization incident light is scanned, and the metasurface structure corresponding to each phase is formed; each group of phase distribution i and each group of metasurface structure are combined into a metasurface structure distribution, so that the metasurface structure distribution corresponds to each group of phase distribution of the different angle linear polarization incident light. The design method and system realize different light field projection at different distances through one diffractive optical device, while eliminating the crosstalk between each other, and greatly improve the performance of 3D imaging.

Description

Technical Field

[0001] This invention relates to the field of 3D imaging technology, and in particular to a design method and system for polarization multiplexing metasurface optical devices for 3D imaging. Background Technology

[0002] With social development and technological progress, people's demand for more realistic and accurate 3D information acquisition and presentation continues to grow, driving the development of 3D imaging technology. The earliest 3D imaging technologies were hand-drawn and photographic techniques based on the principle of stereoscopic vision, such as stereoscopic photography and stereoscopic paintings. In the 1960s, people began to experiment with computer-generated 3D models. In the 1970s and 1980s, automatic 3D imaging technology based on stereo parallax emerged. In the late 1990s, emerging technologies such as structured light and time-of-flight methods gradually matured, providing breakthroughs for the rapid and accurate acquisition of 3D information.

[0003] In optical engineering, 3D imaging and 3D sensing have flourished in recent years, finding wide application in fields such as facial recognition and industrial inspection, including mobile phone recognition, smart door locks, and vehicle recognition. The principle of 3D imaging is to project a light field distribution onto a target surface using a diffractive optical element (DOE). This light field can be a dense lattice, modulated field illumination, or a modulated special light field distribution. After the light field illuminates the object, it is recorded by a detector and matched with a corresponding 3D algorithm to reconstruct the 3D shape of the target object. A crucial issue is the direct correlation between the projected light field and the working distance. Therefore, 3D imaging in reality is limited by its working distance. Expanding the working distance or enriching the projected light field distribution using a single DOE is significant, as it can greatly expand the application areas of 3D imaging and improve its performance.

[0004] One existing technical solution is to use a single diffractive optical element (DOE) to project different light fields at different working distances via Fresnel propagation, achieving the function described above. Projecting different light fields at different working distances requires different phase distributions from different DOEs. Directly integrating these different phase distributions into a single DOE leads to crosstalk between the light field distributions at different distances during operation, affecting the quality of 3D imaging and significantly impacting the device's performance. Summary of the Invention

[0005] Based on this, the present invention provides a design method and system for a polarization multiplexing metasurface optical device for 3D imaging, which can realize different light field projections at different distances through a diffractive optical device, while eliminating crosstalk between them, thus greatly improving the performance of 3D imaging.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a design method for a polarization-multiplexed metasurface optical device for 3D imaging, comprising:

[0007] S100. Multiple projection surfaces or projection light fields are formed at intervals at point di outside the metasurface optical device, where di is the distance from the metasurface optical device to projection surfaces with different polarization angles;

[0008] S200. Optimize the phase distribution for each projection surface or projection light field, denoted as phase distribution i;

[0009] S300. The phase distribution i of linearly polarized incident light 2*pi at different angles is scanned to form a metasurface structure corresponding to each phase;

[0010] S400. Combine each set of phase distributions i and each set of metasurface structures into a metasurface structure distribution, such that the metasurface structure distribution corresponds to each set of phase distributions for linearly polarized incident light at different angles, and linearly polarized incident light at different angles forms different projection surfaces at different distances in the metasurface optics.

[0011] Furthermore, a scalar optimization algorithm is used to optimize the phase distribution of each projection surface or projection light field; or, a vector optimization algorithm is used to optimize the phase distribution of each projection surface or projection light field.

[0012] Furthermore, design methods for polarization-multiplexed metasurface optics for 3D imaging include:

[0013] S600. Four projection surfaces or projection light fields are formed at distances d1, d2, d3, and d4 from the metasurface optics, respectively; where d1 is the distance from the metasurface optics to the 0° polarization projection surface; d2 is the distance from the metasurface optics to the 45° polarization projection surface; d3 is the distance from the metasurface optics to the 90° polarization projection surface; and d4 is the distance from the metasurface optics to the 135° polarization projection surface.

[0014] S700. For the projection surface of d1, optimize a phase distribution, denoted as phase distribution 1; for the projection surface of d2, optimize a phase distribution 2; for the projection surface of d3, optimize a phase distribution 3; for the projection surface of d4, optimize a phase distribution 4.

[0015] S800 scans the phase distribution of linearly polarized incident light at 0°, 45°, 90° and 135° for 2*pi, respectively, and the corresponding four metasurface structures.

[0016] S900. Combine the four sets of phase distributions and the four sets of metasurface structures into a single metasurface structure distribution, such that the metasurface structure distribution corresponds to the four sets of phase distributions for linearly polarized incident light at 0°, 45°, 90°, and 135°.

[0017] To achieve the above objectives, in a second aspect, the present invention provides a polarization-multiplexed metasurface optical device system for 3D imaging, comprising a metasurface optical device and a projection surface or projection light field; the projection surface or projection light field comprises multiple projection surfaces or projection light fields, each projection surface or projection light field being at a distance di from the metasurface optical device, wherein di is the distance from the metasurface optical device to a projection surface polarized at different angles; the phase distribution of each projection surface or projection light field is optimized and denoted as phase distribution i, and the phase distribution i of linearly polarized incident light at different angles (2*pi) is scanned to form a metasurface structure corresponding to each phase; each set of phase distribution i and each set of metasurface structures are combined into a metasurface structure distribution, such that the metasurface structure distribution corresponds to each set of phase distributions for linearly polarized incident light at different angles.

[0018] Furthermore, combined into a pixelated metasurface structure distribution, the structure distribution in the i-th row and j-th column satisfies the following condition:

[0019]

[0020]

[0021]

[0022]

[0023] Wherein, Φ0 is the phase value of incident under 0° linear polarization, Φ45 is the phase value of incident under 45° linear polarization, Φ90 is the phase value of incident under 90° linear polarization, and Φ135 is the phase value of incident under 135° linear polarization. It is phase distribution 1 in step 1. It is phase distribution 2 in step 1. It is phase distribution 3 in step 1. It is phase distribution 4 in step 1.

[0024] Furthermore, different dot matrices with varying numbers of dots are formed on different polarized light projection surfaces. Preferably, 0° polarized light is projected as a 4x4 dot matrix at 0.1m, 45° polarized light as a 6x6 dot matrix at 0.5m, 90° polarized light as an 8x8 dot matrix at 1m, and 135° polarized light as a 10x10 dot matrix at 2m, to achieve different dot matrix densities at different working distances.

[0025] Furthermore, 0° polarized light is projected as a 4x4 dot matrix at 0.1m, 45° polarized light is projected as a 6x6 dot matrix at 0.5m, 90° polarized light is projected as an 8x8 dot matrix at 1m, and 135° polarized light is projected as a 10x10 dot matrix at 2m, in order to achieve different dot matrix densities at different working distances.

[0026] Furthermore, the metasurface optical device includes a diffractive optical device (DOE).

[0027] The technical advantages of the proposed design method and system for polarization-multiplexed metasurface optical devices for 3D imaging are at least reflected in the following aspects:

[0028] By using metasurface optics to achieve polarization multiplexing of different projection content at different working distances, and by using a diffractive optics to achieve different light field projections at different distances, while eliminating crosstalk between them, the working distance of 3D imaging can be increased, the projection light field content of 3D imaging can be enriched, the performance of 3D imaging can be greatly improved, and the application fields of 3D imaging can be expanded. Attached Figure Description

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The accompanying drawings, which are provided to further illustrate the invention and constitute a part of this application, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the provided drawings:

[0030] Figure 1 This is a flowchart illustrating the design method for polarization-multiplexed metasurface optics used in 3D imaging.

[0031] Figure 2 A flowchart illustrating a specific embodiment of a design method for polarization-multiplexed metasurface optics used in 3D imaging, illustrating the design of four projection surfaces.

[0032] Figure 3 This is a schematic diagram illustrating the arrangement of four projection surfaces or four projection light fields.

[0033] Figure 4 The first arrangement of four projection surfaces or four projection light fields is shown in the diagram.

[0034] Figure 5 A schematic diagram of the phase distribution of a 4x4 dot matrix obtained through optimization.

[0035] Figure 6 This is a schematic diagram of the phase distribution under 0° linear polarization during scanning.

[0036] Figure 7 This is a schematic diagram of the phase distribution under 90° linear polarization during scanning.

[0037] Figure 8 This is a schematic diagram of the cylindrical structure used.

[0038] Figure 9 This is a schematic diagram of the metasurface structure distribution of a cylindrical structure.

[0039] Figure 10 This is a schematic diagram illustrating the principle of 3D imaging achieved through a dense dot matrix.

[0040] Explanation of reference numerals in the attached diagram:

[0041] 1—0° polarization projection surface, 2—45° polarization projection surface, 3—90° polarization projection surface, 4—135° polarization projection surface, 5—metasurface optical devices. Detailed Implementation

[0042] In optical engineering, the principle of 3D imaging is to project a light field distribution onto a target surface using a diffractive optical element (DOE). This light field can be a dense lattice, modulated field illumination, or a modulated special light field distribution. After the light field illuminates the object, it is recorded by a detector and matched with a corresponding 3D algorithm to reconstruct the 3D shape of the target object. A crucial issue is the direct correlation between the projected light field and the working distance. One existing technical solution is to use the same DOE to project different light fields at different working distances via Fresnel propagation to achieve the aforementioned function. Projecting different light fields at different working distances requires different phase distributions from different DOEs. Directly integrating different phase distributions into a single DOE results in crosstalk between the light field distributions at different distances, affecting the quality of the 3D image and significantly impacting the device's performance.

[0043] To address the aforementioned problems, this invention provides a design method and system for a polarization-multiplexed metasurface optical device for 3D imaging. Multiple projection surfaces or projection light fields are formed at intervals di outside the metasurface optical device, where di is the distance from the metasurface optical device to different angle-polarized projection surfaces. The phase distribution of each projection surface or projection light field is optimized, denoted as phase distribution i. The phase distribution i of 2*pi of linearly polarized incident light at different angles is scanned to form metasurface structures corresponding to each phase. The phase distribution i and the metasurface structures are combined into a single metasurface structure distribution, such that the metasurface structure distribution corresponds to each phase distribution for linearly polarized incident light at different angles. This design method and system achieves projection of different light fields at different distances using a single diffractive optical device, while simultaneously eliminating crosstalk, significantly improving the performance of 3D imaging.

[0044] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use.

[0045] like Figure 1 As shown, a design method for a polarization-multiplexed metasurface optical device for 3D imaging is provided, including the following steps:

[0046] S100. Multiple projection surfaces or projection light fields are formed at intervals at point di outside the metasurface optical device, where di is the distance from the metasurface optical device to projection surfaces with different polarization angles;

[0047] S200. Optimize the phase distribution for each projection surface or projection light field, denoted as phase distribution i;

[0048] S300. The phase distribution i of linearly polarized incident light 2*pi at different angles is scanned to form a metasurface structure corresponding to each phase;

[0049] S400. Combine each group of phase distributions i and each group of metasurface structures into a metasurface structure distribution, such that the metasurface structure distribution corresponds to each group of phase distributions for linearly polarized incident light at different angles.

[0050] Through this design method, a polarization-multiplexed metasurface optical device system for 3D imaging is formed, including metasurface optical devices and projection surfaces or projection light fields. Multiple projection surfaces or projection light fields are included, and the distance from each projection surface or projection light field to the metasurface optical device is denoted as di, where di is the distance from the metasurface optical device to projection surfaces with different polarization angles. The phase distribution of each projection surface or projection light field is optimized and denoted as phase distribution i. The phase distribution i of linearly polarized incident light at different angles (2*pi) is scanned to form a metasurface structure corresponding to each phase. Each set of phase distribution i and each set of metasurface structures are combined into a single metasurface structure distribution, such that the metasurface structure distribution corresponds to each set of phase distributions for linearly polarized incident light at different angles.

[0051] The present invention provides a design method and system for a polarization multiplexing metasurface optical device for 3D imaging. It realizes projection of different light fields at different distances through a diffractive optical device, while eliminating crosstalk between them. This increases the working distance of 3D imaging, enriches the projection light field content of 3D imaging, greatly improves the performance of 3D imaging, and expands the application fields of 3D imaging.

[0052] The following is combined Figures 2 to 10 Specific embodiments will be described below.

[0053] like Figure 2 As shown, in one specific embodiment, the design method of a polarization-multiplexed metasurface optical device for 3D imaging includes:

[0054] S600. At distances d1, d2, d3 and d4 from the metasurface optical device, four projection surfaces are formed respectively: 0° polarization projection surface 1, 45° polarization projection surface 2, 90° polarization projection surface 3 and 135° polarization projection surface 4. d1 is the distance from the metasurface optical device to the 0° polarization projection surface, d2 is the distance from the metasurface optical device to the 45° polarization projection surface, d3 is the distance from the metasurface optical device to the 90° polarization projection surface, and d4 is the distance from the metasurface optical device to the 135° polarization projection surface.

[0055] S700. For the 0° polarization projection surface 1, optimize a phase distribution, denoted as phase distribution 1; for the 45° polarization projection surface 2, optimize a phase distribution 2; for the 90° polarization projection surface 3, optimize a phase distribution 3; for the 135° polarization projection surface 4, optimize a phase distribution 4.

[0056] S800 scans the phase distribution of linearly polarized incident light at 0°, 45°, 90° and 135° for 2*pi, respectively, and the corresponding four metasurface structures.

[0057] S900. Combine the four sets of phase distributions and the four sets of metasurface structures into a single metasurface structure distribution, such that the metasurface structure distribution corresponds to the four sets of phase distributions for linearly polarized incident light at 0°, 45°, 90°, and 135°.

[0058] like Figure 3 As shown, four projection surfaces or four projection light fields are formed on the 0° polarization projection surface 1, the 45° polarization projection surface 2, the 90° polarization projection surface 3, and the 135° polarization projection surface 4. The design method is as follows:

[0059] Specifically, for the 0° polarization projection surface 1, a phase distribution is optimized based on a scalar or vector algorithm, denoted as phase distribution 1. For the 45° polarization projection surface 2, a phase distribution 2 is optimized. For the 90° polarization projection surface 3, a phase distribution 3 is optimized. For the 135° polarization projection surface 4, a phase distribution 4 is optimized. Corresponding to the phase distributions of 2*pi of linearly polarized incident light at 0°, 45°, 90°, and 135°, the four sets of metasurface structures are scanned respectively. The four sets of phase distributions and the four sets of metasurface structures are combined into a single metasurface structure distribution. This allows the metasurface structure distribution to be used for the four phase distributions in step 1 corresponding to linearly polarized incident light at 0°, 45°, 90°, and 135°. Incident light with different polarizations can form different projection surfaces at different distances in the metasurface optics, thereby eliminating crosstalk between projection surfaces at different distances. This enables the reuse of polarization using metasurface optics.

[0060] Based on this, combined into a pixelated metasurface structure distribution, the structure distribution in the i-th row and j-th column must satisfy the following conditions, where Φ0 is the phase value of incident under 0° linear polarization, Φ45 is the phase value of incident under 45° linear polarization, Φ90 is the phase value of incident under 90° linear polarization, and Φ135 is the phase value of incident under 135° linear polarization. It is phase distribution 1 in step 1. It is phase distribution 2 in step 1. It is phase distribution 3 in step 1. It is phase distribution 4 in step 1.

[0061]

[0062]

[0063]

[0064]

[0065] Different polarized incident light can form different projection surfaces at different distances in metasurface optics, which can greatly enrich the functions of 3D imaging.

[0066] like Figure 5 As shown, 0° polarized light is projected as a 4x4 dot matrix at 0.1m, 45° polarized light as a 6x6 dot matrix at 0.5m, 90° polarized light as an 8x8 dot matrix at 1m, and 135° polarized light as a 10x10 dot matrix at 2m, thus achieving different dot matrix densities at different working distances. The phase distribution diagram under 0° linear polarization obtained using the above method is shown below. Figure 6 As shown, the phase distribution under 90° linear polarization during scanning is illustrated in the diagram. Figure 7 As shown.

[0067] In a preferred embodiment, the provided polarization-multiplexed metasurface optics system for 3D imaging is used for 3D imaging of cylindrical structures. Figure 8 This is a schematic diagram of the cylindrical structure used. Figure 9 A schematic diagram of the metasurface structure distribution of the formed cylindrical structure.

[0068] In another preferred embodiment, face imaging is performed using the provided polarization-multiplexed metasurface optics system for 3D imaging. Figure 10 This is a schematic diagram illustrating the principle of 3D imaging achieved through a dense dot matrix.

[0069] One existing 3D imaging technology uses a single diffractive optical element (DOE) to project different light fields at different working distances via Fresnel propagation, achieving the function described above. Projecting different light fields at different working distances requires different phase distributions from the DOEs. Directly integrating these different phase distributions into a single DOE leads to crosstalk between the light field distributions at different distances during operation, affecting the quality of the 3D image and significantly impacting the device's performance.

[0070] The design method and system for polarization multiplexing metasurface optical devices for 3D imaging provided by this invention solves the above-mentioned technical problems. By using metasurface optical devices to achieve polarization multiplexing of different projection content at different working distances, and by using a diffractive optical device to achieve different light field projections at different distances, the performance of 3D imaging is greatly improved. At the same time, crosstalk between components is eliminated, which greatly enhances the performance of 3D imaging. The structure is simple, reduces the complexity of component assembly and adjustment, helps to improve the product qualification rate, reduces the processing difficulty and cost, and helps to expand the application fields of 3D imaging.

[0071] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. The above drawings and specific embodiments are for illustrative purposes only, and this invention is not limited thereto. Minor modifications to this invention within the inventive spirit and scope defined by the claims of this invention all fall within the protection scope of this invention.

Claims

1. A design method for a polarization-multiplexed metasurface optical device for 3D imaging, characterized in that, include: S100. Multiple projection surfaces or projection light fields are formed at intervals at point di outside the metasurface optical device, where di is the distance from the metasurface optical device to projection surfaces with different polarization angles; S200. Optimize the phase distribution for each projection surface or projection light field, denoted as phase distribution i, with a phase range of 0 to 2*pi; S300. The phase distribution i of linearly polarized incident light at different angles is scanned to form a metasurface structure corresponding to each phase; S400. Combine each group of phase distributions i and each group of metasurface structures into a metasurface structure distribution, such that the metasurface structure distribution corresponds to each group of phase distributions in the linearly polarized incident light at different angles; S500. Four projection surfaces or projection light fields are formed at distances d1, d2, d3, and d4 from the metasurface optics, respectively; where d1 is the distance from the metasurface optics to the 0° polarization projection surface; d2 is the distance from the metasurface optics to the 45° polarization projection surface; d3 is the distance from the metasurface optics to the 90° polarization projection surface; and d4 is the distance from the metasurface optics to the 135° polarization projection surface. S600. For the projection surface of d1, optimize a phase distribution, denoted as phase distribution 1; for The projection surface of d2 is optimized with a phase distribution 2; For the projection surface of d3, optimize a phase distribution 3; for the projection surface of d4, optimize a phase distribution 4. S700 scans the phase distribution of linearly polarized incident light at 0°, 45°, 90° and 135°, with a phase range of 0 to 2*pi, and scans the corresponding four metasurface structures. S800. Combine the four sets of phase distributions and the four sets of metasurface structures into a single metasurface structure distribution, such that the metasurface structure distribution corresponds to the four sets of phase distributions for linearly polarized incident light at 0°, 45°, 90°, and 135°.

2. The design method for polarization-multiplexed metasurface optical devices for 3D imaging according to claim 1, characterized in that: The phase distribution of each projection surface or projection light field is optimized using a scalar optimization algorithm.

3. The design method for polarization-multiplexed metasurface optical devices for 3D imaging according to claim 1, characterized in that: The phase distribution of each projection surface or projection light field is optimized using a vector optimization algorithm.

4. A polarization-multiplexed metasurface optical device system for 3D imaging, characterized in that: This includes metasurface optics and projection surfaces or projection light fields; The projection surface or projection light field includes multiple projection surfaces or projection light fields, and the distance from each projection surface or projection light field to the metasurface optical device is di, where di is the distance from the metasurface optical device to projection surfaces with different angles of polarization. The phase distribution of each projection surface or projection light field is optimized and denoted as phase distribution i, with a phase range of 0 to 2*pi. The phase distribution i of 2*pi of linearly polarized incident light at different angles is scanned to form a metasurface structure corresponding to each phase. Each set of phase distribution i and each set of metasurface structures are combined into a metasurface structure distribution, so that the metasurface structure distribution corresponds to each set of phase distributions of linearly polarized incident light at different angles. The projection surface or projection light field includes four points at distances d1, d2, d3, and d4 from the metasurface optics. d1 is the distance from the metasurface optics to the 0° polarization projection surface; d2 is the distance from the metasurface optics to the 45° polarization projection surface; d3 is the distance from the metasurface optics to the 90° polarization projection surface; and d4 is the distance from the metasurface optics to the 135° polarization projection surface. For the projection surface of d1, optimize a phase distribution, denoted as phase distribution 1; for The projection surface of d2 is optimized with a phase distribution 2; For the projection surface d3, optimize a phase distribution 3; for the projection surface d4, optimize a phase distribution 4; for the phase distributions of linearly polarized incident light 2*pi at 0°, 45°, 90° and 135°, scan the corresponding four sets of metasurface structures respectively; combine the four sets of phase distributions and the four sets of metasurface structures into a metasurface structure distribution, so that the metasurface structure is distributed in the four sets of phase distributions corresponding to linearly polarized incident light at 0°, 45°, 90° and 135°.

5. The polarization-multiplexed metasurface optical device system for 3D imaging according to claim 4, characterized in that: Combined into a pixelated metasurface structure distribution, the structure distribution in the i-th row and j-th column satisfies the following condition: in, It is the phase value of the incident light under 0° linear polarization. It is the phase value of the incident light under 45° linear polarization. It is the phase value of the incident light under 90° linear polarization. It is the phase value of the incident light under 135° linear polarization; It is phase distribution 1 in step 1. It is phase distribution 2 in step 1. It is phase distribution 3 in step 1. It is phase distribution 4 in step 1.

6. The polarization-multiplexed metasurface optical device system for 3D imaging according to claim 5, characterized in that: Different numbers of dots are formed on different polarized light projection surfaces.

7. The polarization-multiplexed metasurface optical device system for 3D imaging according to claim 6, characterized in that: 0° polarized light is projected as a 4×4 dot matrix at 0.1m, 45° polarized light is projected as a 6×6 dot matrix at 0.5m, 90° polarized light is projected as an 8×8 dot matrix at 1m, and 135° polarized light is projected as a 10×10 dot matrix at 2m, so as to achieve different dot matrix densities at different working distances.

8. The polarization-multiplexed metasurface optical device system for 3D imaging according to claim 4, characterized in that: The metasurface optical devices include diffractive optical devices (DOEs).

Images