Design Method of Non-Polarized Light Responsive Spatial Metasurface Lens and Stereo Imaging System

Abstract

The present invention discloses a design method for a non-polarized light-responsive spatial division metasurface lens and a three-dimensional imaging system, comprising the following steps: S1. Set the variation range and variation interval of the degrees of freedom of the nano-units, and according to the preset working wavelength of the incident light, scan to obtain the nano-unit shapes composed of nano-units with different degrees of freedom, and obtain the transmittance database and phase database of the combinations; S2. Calculate the theoretical phase distribution of the spatial division metasurface lens, and use the phase database to match the theoretical phase distribution to obtain the size combination with the highest transmittance within the preset threshold; S3. Map each size in the size combination to a sampling coordinate, and set nano-units on the sampling coordinate to obtain a non-polarized light-responsive spatial division metasurface lens. Compared with the traditional technology, the present application can achieve high-resolution imaging under non-polarized light response, and has the advantages of small volume and simple system structure.

Description

Technical Field

[0001] The present invention relates to the technical field of lens imaging, and more specifically, to a design method of a non-polarized light-responsive spatial division metasurface lens and a stereoscopic imaging system. Background Art

[0002] The metasurface lens is composed of special micro-nano scattering units, which can regulate parameters such as the amplitude, phase, and polarization of the local electromagnetic field to achieve the function of focusing imaging. After years of development, the metasurface lens not only has good optical focusing performance, but also is easy to be integrated into a miniaturized system, showing its advantages in imaging applications. In the field of microscopic imaging, the metasurface lens has a wide range of applications. By designing a metasurface lens with an inclined symmetric double optical axis, an optical imaging system can be built with this as the core to achieve stereoscopic microscopic imaging.

[0003] The traditional stereomicroscope is based on the principle of binocular stereoscopic vision and can achieve stereoscopic microscopic imaging. However, due to its two independent lens groups, the internal space is crowded, resulting in limited lens size. At the same time, in order to maintain a fixed stereo angle, the magnification and numerical aperture of the objective lens are relatively low, and the magnification and resolution are insufficient during imaging.

[0004] The prior art discloses a design method of a spatial division metasurface lens and its stereoscopic imaging system, which can realize a spatial division metasurface lens with two imaging optical paths having appropriate binocular parallax. And due to the existence of the overlapping region of the left and right metasurface lenses, the design of the numerical aperture is not restricted. Therefore, high-resolution imaging can be achieved, significantly improving the imaging performance. The defect of this scheme is that it cannot work under non-polarized light conditions.

[0005] Therefore, in combination with the above requirements and the defects of the prior art, the present application proposes a design method of a non-polarized light-responsive spatial division metasurface lens and a stereoscopic imaging system. Summary of the Invention

[0006] The present invention provides a design method of a non-polarized light-responsive spatial division metasurface lens and a stereoscopic imaging system, which can work under non-polarized light and achieve high-resolution imaging under non-polarized light response.

[0007] The primary object of the present invention is to solve the above technical problems, and the technical solution of the present invention is as follows:

[0008] The first aspect of the present invention provides a design method of a non-polarized light-responsive spatial division metasurface lens, and this method includes the following steps:

[0009] S1. Set the change range and change interval of the degrees of freedom of the nano-units. According to the preset working wavelength of the incident light, scan to obtain the nano-unit shapes composed of nano-units with different degrees of freedom, and obtain the transmittance database and phase database of the combinations.

[0010] S2. Calculate the theoretical phase distribution of the spatial light superlens, match the theoretical phase distribution using the phase database, and obtain the size combination with the highest transmittance within a preset threshold.

[0011] S3. Map each size in the size combination to a sampling coordinate, and set nano-units at the sampling coordinate to obtain a non-polarized light-responsive spatial light superlens.

[0012] Further, the non-polarized light-responsive spatial light superlens includes a left superlens and a right superlens. The left superlens and the right superlens are spaced apart in spatial position. The phase centers of the left superlens and the right superlens are symmetric with respect to the tilted optical axis, and the spatial light superlens is used to generate two images that are symmetric in position and have parallax.

[0013] Further, the nano-units are set on a substrate. The periphery of the nano-units is coated with a medium. The shape of the nano-units is set according to requirements. The spacing, refractive index, material, handedness, and size between the nano-units are set according to requirements. The type of the medium is set according to requirements.

[0014] Further, the theoretical phase distribution of the spatial light superlens is calculated through prior knowledge and the following formula:

[0015]

[0016]

[0017] where and respectively represent the phase curves of the left superlens and the right superlens. (x, y) represents the coordinate position of the sampling point on the two-dimensional plane. λ0 represents the wavelength in air, λ sub represents the wavelength in the substrate, s represents the object distance, v represents the image distance, θ represents the tilt angle of the object-side optical axis, ξ represents the tilt angle of the image-side optical axis, l represents the horizontal distance of the image point from the middle Z-axis, and Im represents taking the imaginary part.

[0018] Further, the specific step S1 is as follows: preset the degree-of-freedom set of the target nano-units; preset the change value of the target degree of freedom and the working wavelength of the incident light. According to the nano-unit combination set after presetting the change value of the target degree of freedom and the working wavelength of the incident light, and combining numerical simulation processing, determine the phase database and the transmittance database of the target nano-unit combination set; the target nano-units include non-polarized light-responsive variable nano-units.

[0019] Further, the degree-of-freedom set of the target nano-units includes the interval value of the repetition period, the shape of the repetition period, the shape of the nano-units in the repetition period, the length of the nano-units, and the width of the nano-units.

[0020] Further, the process of obtaining the combined transmittance database and phase database is as follows: through numerical simulation processing, obtain the outgoing phase and transmittance of each nanounit combination in the nanounit combination set when horizontally polarized light is incident and when vertically polarized light is incident; according to the outgoing phase and the transmittance, determine the phase database of the target nanounit combination set.

[0021] The second aspect of the present invention provides a stereoscopic imaging system, which adopts the non-polarized light-responsive space-division metasurface lens designed by the design method of a non-polarized light-responsive space-division metasurface lens described above. It is characterized by including: a light source, a non-polarized light-responsive space-division metasurface lens, a charge-coupled device, and a processing unit. The light source is arranged on the central axis of the non-polarized light-responsive space-division metasurface lens and maintains a set distance from it. The sample to be measured is arranged between the light source and the non-polarized light-responsive space-division metasurface lens. The sample to be measured forms an image through the space-division metasurface lens, and the charge-coupled device collects the image and inputs it to the processing unit.

[0022] Further, the light source is a transmissive illumination light source, and a beam adjustment and focusing system is also arranged between the light source and the sample to be measured, which is used to focus the divergent light beam emitted by the light source onto the sample to be measured.

[0023] Further, the image is two images that are symmetric in position and have parallax.

[0024] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0025] The present invention provides a design method of a non-polarized light-responsive space-division metasurface lens and a stereoscopic imaging system, designs a non-polarized light-responsive space-division metasurface lens with binocular parallax, and realizes a non-polarized light-responsive space-division metasurface lens stereoscopic imaging system with two imaging light paths with appropriate binocular parallax through the spatial arrangement of the space-division metasurface lens, which can achieve high-resolution imaging under non-polarized light response and has the advantages of small volume and simple system structure. Description of the Drawings

[0026] Figure 1 It is a flowchart of a design method of a non-polarized light-responsive space-division metasurface lens of the present invention.

[0027] Figure 2 It is a schematic structural diagram of the nanounits of a non-polarized light-responsive space-division metasurface lens in an embodiment of the present invention.

[0028] Figure 3 It is a schematic diagram of the spatial distribution of the phases of the left metasurface lens and the right metasurface lens of a non-polarized light-responsive space-division metasurface lens in an embodiment of the present invention.

[0029] Figure 4 Schematic diagram of local nano-units of a non-polarized light-responsive spatial division metasurface lens in an embodiment of the present invention.

[0030] Figure 5 Schematic diagram of a three-dimensional imaging system of the present invention.

[0031] Figure 6 Functional schematic diagram of a non-polarized light-responsive spatial division metasurface lens in an embodiment of the present invention. Detailed implementation manners

[0032] In order to more clearly understand the above objects, features and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0033] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0034] Embodiment 1

[0035] As Figure 1 shown, the present invention provides a design method for a non-polarized light-responsive spatial division metasurface lens. The method includes the following steps:

[0036] S1. Set the change range and change interval of the degrees of freedom of the nano-units. According to the preset working wavelength of the incident light, scan to obtain the nano-unit shapes composed of nano-units with different degrees of freedom, and obtain the transmittance database and phase database of the combinations.

[0037] S2. Calculate the theoretical phase distribution of the spatial division metasurface lens, and use the phase database to match the theoretical phase distribution to obtain the size combination with the highest transmittance within the preset threshold.

[0038] S3. Map each size in the size combination to a sampling coordinate, and set nano-units on the sampling coordinate to obtain a non-polarized light-responsive spatial division metasurface lens.

[0039] It should be noted that for a non-polarized light-responsive spatial division metasurface lens provided by the present invention, its three-dimensional imaging system has higher resolution and magnification, and operates under non-polarized light, reducing the requirements for the irradiation light source and enabling non-polarized light imaging of samples.

[0040] As Figure 3As shown, the non-polarized light-responsive spatial division metasurface lens includes a left metasurface lens and a right metasurface lens. The phases of the left metasurface lens at positions 3, 5, 7 and the phases of the right metasurface lens at positions 4, 6, 8 on the metasurface lens plane are spaced apart in spatial positions. The phase centers of the left metasurface lens and the right metasurface lens are symmetric with respect to the tilted optical axis. The spatial division metasurface lens is used to generate two symmetrically positioned images with parallax.

[0041] In a specific embodiment, as Figure 2 shown, the nano-units 2 of the present invention are disposed on the substrate. The nano-units 2 are coated by the medium 1. The nano-units 2 can be in the shape of a cylinder, a truncated cylinder, a rectangular column, etc. The spacing, refractive index, material, handedness, dimensions in each orientation, and the type of the medium 1 coating the nano-units 2 can all be adjusted according to the design.

[0042] The theoretical phase distribution of the spatial division metasurface lens is calculated through prior knowledge, spherical wave propagation theory, and focusing phase theory:

[0043]

[0044]

[0045] Wherein, and respectively represent the phase curves of the left metasurface lens and the right metasurface lens. (x, y) represents the coordinate position of the sampling point on the two-dimensional plane. λ0 represents the wavelength in air, and λ sub represents the wavelength in the substrate. s represents the object distance, v represents the image distance, θ represents the tilt angle of the object-side optical axis, ξ represents the tilt angle of the image-side optical axis, l represents the horizontal distance of the image point from the middle Z-axis, and Im represents taking the imaginary part.

[0046] The step S1 is specifically as follows: preset the degree-of-freedom set of the target nano-units; preset the change value of the target degree of freedom and the working wavelength of the incident light. According to the nano-unit combination set after presetting the change value of the target degree of freedom and the working wavelength of the incident light, and combining numerical simulation processing, determine the phase database and the transmittance database of the target nano-unit combination set. The target nano-units include non-polarized light-responsive variable nano-units.

[0047] The degree-of-freedom set of the target nano-units includes the interval value of the repetition period, the shape of the repetition period, the shape of the nano-units in the repetition period, the length of the nano-units, and the width of the nano-units.

[0048] The process of obtaining the combined transmittance database and phase database is as follows: numerical simulation processing is adopted to obtain the outgoing phases and transmittances of each nano-unit combination in the nano-unit combination set when horizontally polarized light is incident and when vertically polarized light is incident; based on the outgoing phases and the transmittances, the phase database of the target nano-unit combination set is determined.

[0049] According to the above technical features, the present invention modifies the formula to adapt to the working scenario of unpolarized light, realizing the design of an unpolarized light-responsive spatial division metasurface lens with binocular parallax. At the same time, the present invention utilizes the high degree of freedom in the design of the metasurface lens to design a spatial division metasurface lens operating under unpolarized light, which includes two metasurface lens functional regions and two tilted optical axes, and can generate two symmetric focal points, that is, two images can be generated for one object at the same time, and due to the optical axes being tilted, the images have built-in parallax.

[0050] Embodiment 2

[0051] Based on the above Embodiment 1, combined with Figure 6 , this embodiment elaborates in detail the principle of the unpolarized light-responsive spatial division metasurface lens in the present invention.

[0052] As Figure 6 shown, the unpolarized light-responsive spatial division metasurface lens of the present invention includes an object plane 9, a spatial division metasurface lens 10, a left metasurface lens tilted optical axis and beam focusing 11, a right metasurface lens tilted optical axis and beam focusing 12, and an image plane 13. Among them, both the left metasurface lens and the right metasurface lens operate under unpolarized light; the tilting angles of the object-side optical axis and the image-side optical axis can be set according to requirements.

[0053] In one embodiment, the materials of the nano-units and the substrate in the present invention are prepared from any one or more optical dielectric materials such as optical crystals, optical glasses, optical thin films, optical plastics, optical metals such as gold, silver, and aluminum, and optical non-metallic materials such as group III-V compound semiconductors, and the optical crystals include but are not limited to optical single crystals, optical polycrystals, and optical amorphous materials.

[0054] As Figure 4 shown, the metasurface lens unit of the present invention is provided with micro-nano structures arranged in a patterned manner, and the array can be obtained by methods including but not limited to electron beam lithography, ultraviolet lithography, and laser direct writing, and the etching method can be dry etching or wet etching.

[0055] Embodiment 3

[0056] As Figure 5As shown in the figure, the present invention also provides a three-dimensional imaging system. This system uses the non-polarization light-responsive spatial superlens obtained by the present invention, and includes: a light source 14, a non-polarization light-responsive spatial superlens 16, a charge-coupled device 18, and a processing unit 19. The light source 14 is arranged on the central axis of the non-polarization light-responsive spatial superlens 16 and maintains a set distance from it. The sample to be measured 15 is arranged between the light source 14 and the non-polarization light-responsive spatial superlens 16. The sample to be measured 15 forms an image 17 through the spatial superlens, and the charge-coupled device 18 collects the image 17 and inputs it to the processing unit 19.

[0057] The light source 14 is a transmissive illumination light source. A beam adjustment and focusing system is also arranged between the light source 14 and the sample to be measured 15, which is used to focus the divergent light beam emitted by the light source 14 onto the sample to be measured 15. The image 17 is two images that are symmetric in position and have parallax.

[0058] In a specific embodiment, in this embodiment, the processing unit 19 is a computer, which is used to output the image collected by the charge-coupled device (CCD). This system also includes a carrier plate, which is used to fix the superlens 16 and the sample to be measured 15.

[0059] It should be noted that in the above imaging system, the specific working principle is as follows: The divergent light beam emitted by the transmissive illumination light source 14 first passes through a series of beam adjustment and focusing systems, and finally converges on the test sample 15 placed on the carrier plate. The spatial superlens 16 is also placed on a carrier plate at a higher level. The illuminated area of the test sample will serve as a new light source, and two symmetrically positioned images 17 with parallax will be formed in its subsequent space through the superlens directly above. These images are collected by the CCD 18 and output through the computer 19 to achieve three-dimensional microscopic imaging.

[0060] According to the above technical features, under non-polarization light conditions, non-polarization light imaging of the sample can be realized, which reduces the requirements for the illumination light source and expands the application range; the superlens and optical elements designed according to the present invention can be used to build a non-polarization light-responsive three-dimensional imaging system to achieve three-dimensional microscopic imaging, and the imaging quality is not inferior to that of a traditional stereomicroscope with a glass lens as the core. The present invention has the following advantages compared with the prior art:

[0061] (1) High resolution. The left superlens and right superlens distributed in space intervals can achieve spatial multiplexing of the superlens surface, and the design of the numerical aperture is not restricted. Therefore, high-resolution imaging can be realized;

[0062] (2) Symmetric imaging. Since the space-division metasurface lens contains two independent functional regions with two symmetric tilted optical axes, a single object on the object plane will form a pair of images with positions symmetric about the Z-axis through the metasurface lens, and the images have parallax.

[0063] (3) The symmetric images have no crosstalk. The tilt angle of the image-side optical axis of the space-division metasurface lens can be designed independently, so that the images after stereoscopic metasurface lens imaging are spatially separated, realizing crosstalk-free imaging of the left metasurface lens and the right metasurface lens under non-polarized light.

[0064] (4) Small volume. The designed space-division metasurface lens has a very small volume, with a thickness on the order of millimeters, which is easy to integrate into a miniaturized system.

[0065] (5) Mature technology. It can be fabricated using existing semiconductor micro-nano processing technologies without the need to develop new process technologies additionally.

[0066] (6) Non-polarized light imaging. The designed lens operates under non-polarized light and can achieve polarized imaging of birefringent samples and circular dichroism samples.

[0067] In the embodiments provided in this application, it should be understood that the disclosed systems and methods can be implemented in other ways. Those of ordinary skill in the art can understand that all or part of the steps of implementing the above method embodiments can be completed by hardware related to program instructions. The foregoing program can be stored in a computer-readable storage medium. When the program is executed, it executes the steps including the above method embodiments; and the foregoing storage medium includes: removable storage devices, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks and other various media that can store program codes.

[0068] Alternatively, if the above embodiments of the present invention are implemented in the form of software function modules and sold or used as independent products, they can also be stored in a computer-readable storage medium. Based on such an understanding, the technical solutions of the embodiments of the present invention, in essence, or the part that contributes to the prior art can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device to execute all or part of the methods described in the various embodiments of the present invention. And the foregoing storage medium includes: removable storage devices, ROM, RAM, magnetic disks, or optical disks and other various media that can store program codes.

[0069] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. The icons describing the structural positional relationships in the drawings are only for illustrative purposes and cannot be construed as limitations on the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A design method for a non-polarized light-responsive spatial superlens, characterized in that, Including the following steps: S1. Set the change range and change interval of the degrees of freedom of the nano-units. According to the preset working wavelength of the incident light, scan to obtain the nano-unit shapes composed of nano-units with different degrees of freedom, and obtain the transmission rate database and phase database of the combinations. S2. Calculate the theoretical phase distribution of the space-division metasurface lens. Use the phase database to match the theoretical phase distribution to obtain the size combination with the highest transmission rate within the preset threshold. The theoretical phase distribution of the space-division metasurface lens is calculated through prior knowledge and the following formula: Among them, and respectively represent the phase curves of the left and right metasurface lenses, (x, y) represents the coordinate position of the sampling points on the two-dimensional plane, λ0 represents the wavelength in air, λ sub represents the wavelength in the substrate, s represents the object distance, v represents the image distance, θ represents the tilt angle of the object-side optical axis, ξ represents the tilt angle of the image-side optical axis, and l represents the horizontal distance of the image point from the middle Z-axis; S3. Map each size in the size combination to a sampling coordinate, and set nano-units on the sampling coordinate to obtain a non-polarized light-responsive space-division metasurface lens. The non-polarized light-responsive space-division metasurface lens includes a left metasurface lens and a right metasurface lens. The left metasurface lens and the right metasurface lens are spaced apart in spatial position. The phase centers of the left metasurface lens and the right metasurface lens are symmetric with respect to the tilted optical axis. The space-division metasurface lens is used to generate two images that are symmetric in position and have parallax.

2. The design method of a non-polarized light-responsive spatial superlens according to claim 1, wherein The nano-units are arranged on a substrate. The periphery of the nano-units is coated with a medium. The shape of the nano-units is set according to requirements. The intervals, refractive indices, materials, rotation directions, and sizes between the nano-units are set according to requirements. The type of the medium is set according to requirements.

3. The design method of a non-polarized light-responsive spatial superlens according to claim 1, characterized in that The specific content of step S1 is: preset the degree-of-freedom set of the target nano-units; preset the change value of the target degree of freedom and the working wavelength of the incident light. According to the nano-unit combination set after presetting the change value of the target degree of freedom and the working wavelength of the incident light, and combining numerical simulation processing, determine the phase database and transmission rate database of the target nano-unit combination set. The target nano-units include non-polarized light-responsive variable nano-units.

4. The design method of a non-polarized light-responsive spatial superlens according to claim 3, characterized in that, The degree-of-freedom set of the target nano-units includes the interval value of the repetition period, the shape of the repetition period, the shape of the nano-units in the repetition period, the length of the nano-units, and the width of the nano-units.

5. The design method of a non-polarized light-responsive spatial superlens according to claim 4, wherein The process of obtaining the transmission rate database and phase database of the combinations is: use numerical simulation processing to obtain the outgoing phases and transmittances of each nano-unit combination in the nano-unit combination set when horizontally polarized light is incident and when vertically polarized light is incident; according to the outgoing phases and the transmittances, determine the phase database of the target nano-unit combination set.

6. A stereoscopic imaging system, which uses a non-polarized light-responsive spatial division metasurface lens obtained by the design method of a non-polarized light-responsive spatial division metasurface lens described in any one of claims 1-5, characterized in that, Including: a light source (14), a non-polarized light-responsive space-division metasurface lens (16), a charge-coupled device (18), and a processing unit (19). The light source (14) is arranged on the central axis of the non-polarized light-responsive space-division metasurface lens (16) and maintains a set distance from it. A sample to be measured (15) is arranged between the light source (14) and the non-polarized light-responsive space-division metasurface lens (16). The sample to be measured (15) forms an image (17) through the space-division metasurface lens. The charge-coupled device (18) collects the image (17) and inputs it to the processing unit (19).

7. A three-dimensional imaging system according to claim 6, wherein The light source (14) is a transmissive illumination light source. A beam adjustment and focusing system is also arranged between the light source (14) and the sample to be measured (15) for focusing the divergent light beam emitted by the light source (14) onto the sample to be measured (15).

8. A stereoscopic imaging system according to claim 6, characterized in that, The images (17) are two images that are symmetric in position and have parallax.

Images