Superlens, design method thereof and optical projection system

Abstract

The invention discloses a super lens, a design method thereof and an optical projection system. The super lens is provided with a super surface and microstructures, the microstructures are arranged on the super surface, the super surface is provided with a plurality of sub-partitions and a plurality of groups of microstructures, and each sub-partition correspondingly comprises one group of microstructures; each sub-partition has the same target phase distribution, so that light emitted by each sub-partition can independently form a sub-target image on a target imaging surface; a plurality of sub-target images formed by the plurality of sub-partitions are coherently stacked on the target imaging surface to form a target image, and the sub-target images and the target image have the same spatial characteristics; the first uniformity of the sub-target image is smaller than the second uniformity of the target image, and the imaging quality of the target image is improved.

Description

Technical Field

[0001] This invention relates to the field of superlenses, and more particularly to a superlens and its design method, and an optical projection system. Background Technology

[0002] Metasurfaces are novel micro-devices that precisely manipulate multiple physical parameters of light, such as amplitude, phase, and polarization, by designing and fabricating nanoscale microstructures in their shape, size, and arrangement. Metasurfaces can replace various traditional optical elements, enabling diverse optical functions and improving the functional density and integration of optical devices. Employing phase modulation, metasurfaces can achieve projection imaging with various morphologies, such as lattice projection and flat-top light shaping.

[0003] Lattice projection requires a high degree of uniformity in the energy distribution of the lattice to achieve high-quality imaging. When designing the phase for metasurface imaging, the incident light field must be clearly defined before targeted phase design. In practice, vertical-cavity surface-emitting lasers (VCSELs) are often chosen as the source for the lattice. Since light from different locations illuminates different positions on the metasurface, it is difficult for a metasurface designed for a specific intensity distribution to simultaneously achieve the same perfect modulation of the incident light field at different positions to ensure uniformity of the projected lattice.

[0004] When designing the imaging phase, the incident light field is usually designed for collimated light. For divergent light sources, a collimated phase is often superimposed to compensate for the divergent phase of the designed incident light. However, there is an error between the actual output light phase and the theoretical imaging phase. When the designed imaging phase is sensitive, such as for precise patterns like dot lattices, it can easily lead to a decrease in uniformity.

[0005] The actual light source module is affected by factors such as temperature, and the light emission morphology will also change. When theoretically designing the imaging phase, the incident parameters and the outgoing parameters are deterministic, and the phase distribution in different regions precisely controls the different light rays. For example, the edge phase often controls the edge incident light rays, and the center phase often controls the center light rays. When the light source morphology changes, it is equivalent to a large deviation between the actual incident parameters and the theoretical incident parameters, resulting in errors in the actual imaging results. Summary of the Invention

[0006] One of the objectives of this invention is to provide a superlens to at least solve the technical problem in the prior art where the actual imaging quality of a metasurface is reduced due to the deviation between the actual incident parameters and the theoretical incident parameters.

[0007] To achieve one of the above-mentioned objectives, one embodiment of the present invention provides a superlens having a metasurface and microstructures, wherein the microstructures are disposed on the metasurface, and the metasurface has multiple sub-partitions and multiple sets of microstructures, each of the sub-partitions corresponding to a set of the microstructures; Each of the sub-regions has the same target phase distribution, such that the light rays emitted from each of the sub-regions can independently form a sub-target image on the target imaging surface; Multiple sub-target images formed by multiple sub-regions are coherently superimposed on the target imaging plane to form a target image, and the sub-target images and the target image have the same spatial features.

[0008] As a further improvement of one embodiment of the present invention, the target phase distribution of the sub-region is configured such that each sub-region can independently generate the sub-target image on the target imaging surface based on the light incident on its own region.

[0009] As a further improvement of one embodiment of the present invention, each of the sub-partitions has an actual phase distribution, and the actual phase distributions of multiple sub-partitions are not the same; the actual phase distribution is realized by the actual manufacturing parameters of the microstructure, and there is a random phase deviation between the actual phase distribution and the target phase distribution.

[0010] As a further improvement of one embodiment of the present invention, the plurality of sub-partitions are arranged in a periodic or non-periodic manner, and the plurality of sub-partitions are spliced ​​together to form the metasurface.

[0011] As a further improvement of one embodiment of the present invention, the plurality of sub-partitions have the same shape or different shapes.

[0012] As a further improvement of one embodiment of the present invention, the superlens is configured to collimate the incident light rays.

[0013] To achieve one of the above-mentioned objectives, one embodiment of the present invention provides a method for designing a superlens, comprising the following steps: Based on the incident light field model and the target light field distribution, the target phase distribution is calculated; The metasurface of the superlens is divided into multiple independent sub-regions; The target phase distribution is copied, and the multiple target phase distributions are assigned to the multiple sub-partitions in a one-to-one correspondence. The target phase distributions of all the sub-regions are combined to form the overall phase distribution of the superlens; The overall phase distribution is mapped to the physical parameters of the microstructure array on the metasurface.

[0014] As a further improvement of one embodiment of the present invention, the incident light field model is a point light source, a lattice light source, a collimated plane wave, or a collimated Gaussian light intensity distribution.

[0015] To achieve one of the above-mentioned objectives, one embodiment of the present invention provides an optical projection system including the superlens described in any of the above technical solutions.

[0016] As a further improvement of one embodiment of the present invention, the optical projection system includes a light source and an imaging system. The sub-light field formed by the light emitted from the same point of the light source after passing through the sub-partition has coherence. The target imaging surface is disposed in the imaging system. The light source, the superlens, and the target imaging surface are arranged along the direction of light propagation.

[0017] As a further improvement of one embodiment of the present invention, the light source can be selectively configured as: a point light source, a dot matrix light source, a plane wave, or a Gaussian light intensity distribution; the light source can be selectively switched between the point light source, the dot matrix light source, the plane wave, or the Gaussian light.

[0018] As a further improvement of one embodiment of the present invention, the light source is configured to be positionally offset relative to the superlens, wherein the incident light spot center of the light source moves a distance on the supersurface not greater than 50% of the size of a single sub-section.

[0019] Compared with the prior art, the present invention provides a superlens with a metasurface having multiple sub-regions, each sub-region having the same target phase distribution, such that the light rays emitted from each sub-region can independently form a sub-target image on the target imaging surface, and multiple sub-target images are coherently superimposed on the target imaging surface to form a target image; the sub-target images and the target image have the same spatial characteristics, and the first uniformity of the sub-target images is less than the second uniformity of the target image, thereby improving the imaging quality of the target image. Attached Figure Description

[0020] Figure 1 This is a side view of a superlens according to one embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of a partitioned superlens according to one embodiment of the present invention.

[0022] Figure 3-8 This is a schematic diagram of different arrangements and combinations of multiple sub-partitions of the superlens in various embodiments of the present invention.

[0023] Figure 9 This is a formula for calculating the collimated phase in one embodiment of the present invention.

[0024] Figure 10 This is a functional schematic diagram of the optical projection system in the first embodiment of the present invention.

[0025] Figure 11 This is a normalized light intensity distribution diagram of the optical projection system in the first embodiment of the present invention.

[0026] Figure 12 a is the target dot matrix image generated by the dot matrix projection system in the prior art.

[0027] Figure 12 b is the target dot matrix generated by the optical projection system in the second embodiment of the present invention.

[0028] Figure 13a This is a functional schematic diagram of a collimated plane wave projection system in the prior art.

[0029] Figure 13b Is Figure 13a A functional diagram showing the replacement of the collimated plane wave with a Gaussian intensity distribution.

[0030] Figure 13c Is Figure 13a A functional diagram showing the replacement of a traditional superlens with a partitioned superlens.

[0031] Figure 14 This is a functional schematic diagram of the optical projection system in the fourth embodiment of the present invention.

[0032] Figure 15 This is a functional schematic diagram of the optical projection system in the fifth embodiment of the present invention.

[0033] Figure 16 This is a functional schematic diagram of the optical projection system in the sixth embodiment of the present invention.

[0034] Figure 17 This is a functional schematic diagram of the optical projection system in the seventh embodiment of the present invention. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the scope of protection of the present invention.

[0036] It should be noted that the term "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Furthermore, the terms "first," "second," "third," "fourth," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] The terms “connection,” “connected to,” or any other variations are intended to encompass various relative positions where a connection exists, including both direct and indirect connections. A direct connection can be formed through a pneumatic conduit, while an indirect connection can be formed through devices such as valves or sensors, through pneumatic components such as brake control units, or through any other medium such as air.

[0038] Please see Figure 1 This is a schematic diagram of a superlens 100 provided in an embodiment of the present invention. The superlens 100 has a metasurface 2, and the metasurface 2 is provided with a plurality of microstructures 201.

[0039] Metasurface 2 is a functional surface with artificial microstructures 201. The microstructures 201 have nanoscale dimensions and are arranged in a two-dimensional array. The microstructures 201 are the basic units that make up the metasurface. By designing the geometry of each microstructure 201, such as cylinder, square prism, elliptical cylinder, etc., its size, and rotation direction, the phase, amplitude, and polarization of light can be precisely controlled.

[0040] The superlens 100 has a base 1 and a metasurface 2 formed on at least one side of the base 1. The base 1 provides mechanical support and optical transmission for the entire device.

[0041] The metasurface 2 has multiple sub-regions 20 and multiple sets of microstructures 201, with each sub-region 20 containing a set of microstructures 201. Each sub-region 20 has the same target phase distribution, so that the light emitted from each sub-region 20 can independently form a sub-target image on the target imaging surface. The multiple sub-target images formed by the multiple sub-regions are coherently superimposed on the target imaging surface to form the target image, and the sub-target images and the target image have the same spatial characteristics. The first uniformity of the sub-target images is less than the second uniformity of the target image, which improves the uniformity of the target image and thus improves the imaging quality of the target image.

[0042] The target phase distribution refers to the phase modulation function calculated for sub-region 20 during the optical design phase, which is expected to be realized under a preset optical environment. The target phase distribution is obtained by solving an algorithm based on a unified and standardized incident light field model and a preset target light field distribution. Each sub-region 20 has a target phase distribution to ensure that each sub-region 20 is functionally self-consistent and independently forms a sub-target image.

[0043] Each sub-partition 20 has the same target phase distribution to ensure that the sub-target image and the target image formed by each sub-partition 20 have the same spatial features.

[0044] Having the same spatial features as the target image means that the sub-target image and the target image have the same target pattern distribution, such as having the same shape, outline, dot matrix pattern, flat-top light spot, etc. The sub-target image and the target image have the same pattern, but the sharpness of the same pattern differs, that is, the uniformity differs as described in this application.

[0045] In this application, the uniformity of the target image refers to the uniformity of the light intensity distribution. For most projection imaging applications, especially in the field of dot matrix projection, the more uniform the light intensity distribution, the higher the image quality. In other words, the higher the uniformity, the higher the image quality.

[0046] Understandably, light intensity itself is not a vector and cannot be coherently superimposed. However, the sub-light field formed by sub-region 20, which is the complex amplitude distribution, can be vectorively superimposed, and the light intensity is the square of the complex amplitude modulus. The coherent superposition of the complex amplitude distributions determines the actual light intensity distribution. Coherent superposition of the complex amplitude distributions can suppress biased sub-light fields and improve the uniformity of light intensity.

[0047] In existing technologies, metasurface 2 has a globally precise-designed target phase distribution, with each microstructure 201 precisely controlling the phase of a specific incident light to achieve good uniformity in the final image. However, in actual reproduction, there are manufacturing deviations and instabilities in the actual incident light source, both of which are random and accidental. The globally designed metasurface 2, when used for actual imaging, is affected by these manufacturing deviations and instabilities in the actual incident light source, generating random deviation light fields that affect the light intensity distribution and lead to a decrease in image quality.

[0048] This application designs the metasurface 2 in partitions, with multiple sub-partitions 20 designed based on the same target phase distribution. The multiple target phase distributions of the multiple sub-partitions 20 form the overall phase distribution of the metasurface 2. Therefore, the overall phase distribution of the metasurface 2 is no longer a globally continuous target phase distribution, but rather is composed of multiple replicated target phase distributions.

[0049] When each sub-region 20 has a target phase distribution, each sub-region 20 is an independently functional phase modulation region, capable of forming a sub-target image on the target imaging surface. The sub-target image has a first uniformity, although the first uniformity is low. However, multiple sub-target images can coherently superimpose on the target imaging surface to obtain a target image, which has a second uniformity, and the second uniformity is high. Because of the coherent superposition of multiple sub-target images, the unwanted random deviation sub-light fields corresponding to the multiple sub-target images can interfere, thereby suppressing the average light intensity of the unwanted deviation sub-light fields and improving the light intensity distribution of the overall light field.

[0050] Specifically, each sub-region 20 forms a corresponding sub-light field on the target imaging surface, and the light field formed on the target imaging surface by the metasurface 2 is a coherent superposition of all sub-light fields. Each sub-light field includes a main signal light field and a deviation light field. The main signal light field corresponds to the desired light field that generates the sub-target image, while the deviation light field is the unwanted stray light field, which leads to inhomogeneity in the sub-target image. Each sub-region 20 has the same function but is independent. The main signal light fields it generates are identical and can be superimposed and enhanced, while the generated deviation light fields are random and can compensate for each other to reduce light intensity fluctuations. Therefore, when the final coherent superposition is reflected on the target image, it can make the target image have better uniformity.

[0051] Each sub-region 20 has an actual phase distribution, and the actual phase distributions of multiple sub-regions 20 are not the same. The actual phase distribution is realized through the actual fabrication parameters of the microstructure 201. There is a random phase deviation between the actual phase distribution and the target phase distribution. Multiple random phase deviations have a compensating effect on each other, so as not to affect the actual imaging.

[0052] Theoretically, sub-regions 20 are designed with phase distribution based on the same target, and the actual phase distribution of each sub-region 20 depends on the actual fabrication parameters of the microstructure 201, such as the shape, size, and rotation angle of the microstructure 201. It can be understood that when the actual artificial microstructure 201 reproduces the target phase distribution, each sub-region 20 will have an actual phase distribution after the actual fabrication is completed.

[0053] Although the actual phase distribution is infinitely close to the target phase distribution, the randomness and unpredictability of actual manufacturing process errors result in a random phase distribution. In other words, when actually reproducing the target phase distribution, there is a random phase deviation between the actual phase distribution and the target phase distribution. This random phase deviation will cause the sub-light field to form a randomly biased light field.

[0054] The randomness of the actual incident light source is reflected in the changes in light source intensity caused by the influence of electricity and the influence of actual ambient temperature. These changes will cause deviations between the actual incident parameters and the theoretical incident parameters, resulting in the generation of a random deviation light field in the sub-division 20 when forming the sub-light field.

[0055] The partitioned superlens 100 of this application can adaptively compensate for various random deviation light fields, thereby improving the uniformity of light intensity. Specifically, the sub-partition 20 includes a first sub-partition 210 and a second sub-partition 220. The first sub-partition 210 forms a first sub-light field, which includes a main signal light field and a first deviation light field, the first deviation light field being a randomly generated, unwanted light field. The second sub-partition 220 forms a second sub-light field, which includes both the main signal light field and the second deviation light field, the second deviation light field being a randomly generated, unwanted light field. The first and second deviation light fields interfere with each other, and the light intensities of the two deviation light fields are superimposed and averaged, thereby suppressing the light intensity mean error, changing the light intensity distribution, and improving the uniformity of the target image.

[0056] The target phase distribution of sub-region 20 is configured such that each sub-region 20 can independently generate a sub-target image on the target imaging surface based on the light incident on its own region; each sub-region 20 generates a sub-target image based on the local light incident on itself, rather than based on the global light, thereby improving the robustness of the metasurface 2 to changes in incident parameters and the generalization of incident light field switching.

[0057] In existing technologies, metasurfaces are the target phase distribution of globally coupled optimization design. They are overall continuous and globally coordinated phase distributions, which are sensitive to changes in the position, shape, and intensity distribution of the light source. In actual imaging, changes in incident light parameters, such as shifts in the incident light position, changes in the incident light morphology, or changes in the incident light intensity distribution, have a significant impact on the uniformity of the actual imaging.

[0058] In this application, when the global incident parameters have complex variables, these global complex variables are decoupled and distributed to each sub-partition 20. For each sub-partition 20, it perceives only the variables of the decoupled partial incident parameters. This is equivalent to the complex variables of the global incident parameters being weakened locally, thereby reducing the sensitivity of each sub-partition 20 to changes in the global incident parameters.

[0059] Sub-partition 20 can achieve functional self-consistency. Changes in global incident parameters do not affect the ability of each sub-partition 20 to still generate sub-target images. Furthermore, the uniformity of multiple sub-target images is optimized after coherent superposition to obtain the target image.

[0060] It is understandable that when the global incident parameters change, for example, the intensity distribution of the actual light intensity changes, the variables of the incident light parameters sensed by each sub-partition 20 are random, and the sub-light field of each sub-partition 20 generates a random deviation light field. Multiple random deviation light fields can interfere with each other, weakening the influence of the random deviation light field.

[0061] In existing technologies, metasurfaces are radially partitioned, dividing the metasurface into a central circle and multiple concentric rings, with the multiple concentric rings sharing the same center as the central circle. The radially partitioned metasurface represents a continuous, global target phase distribution function. Radial partitioning is used to more easily achieve this continuous, global target phase distribution function, or to design different phases for different regions. However, existing radially partitioned metasurfaces do not allow for independent imaging of each partition, nor can they achieve coherent superposition of images from multiple partitions.

[0062] In this application, multiple sub-partitions 20 are arranged in a periodic or non-periodic manner, and the multiple sub-partitions 20 are spliced ​​together to form a metasurface 2. There are multiple possibilities for the arrangement of multiple sub-partitions 20. As long as each sub-partition 20 has the same target phase distribution, the multiple sub-partitions 20 can be spliced ​​together to form a metasurface 2.

[0063] Multiple sub-partitions 20 may have the same or different shapes. The shape of a sub-partition 20 includes its size and shape. Similarly, there are multiple possibilities for the specific shape of a sub-partition 20, as long as each sub-partition 20 has the same target phase distribution.

[0064] Combination Figure 2 As shown in the specific embodiment, the superlens 100 has a first direction and a second direction that are perpendicular to each other, corresponding to the length and width directions of the superlens 100. Each sub-partition 20 is a small rectangular structure, and multiple sub-partitions 20 have the same shape and are spliced ​​together to form a large rectangular structure. A single sub-partition 20 has a sub-length x in the first direction and a sub-width y in the second direction. The entire phase distribution has a length X in the first direction and a width Y in the second direction. X = M * x, Y = N * y, where M and N are the number of sub-partitions in the first and second directions. This highly regularized combination of sub-partitions greatly simplifies the actual manufacturing process and assembly design, and can efficiently drive the optimization and verification of theoretical algorithms.

[0065] Combination Figure 3 As shown, each sub-partition 20 is a small parallelogram structure, and multiple sub-partitions 20 with the same shape are joined together to form a large parallelogram structure. Combined with... Figure 4-5 As shown, each sub-partition 20 is a small rectangular structure, and multiple sub-partitions 20 have the same shape but are arranged in a staggered manner. Combined with... Figure 6 As shown, each sub-partition 20 has a hexagonal structure, and multiple sub-partitions 20 have the same shape and are arranged in a honeycomb pattern. The fact that multiple sub-partitions 20 have the same shape means that they have the same structure and are of equal size. Thus, after designing the target phase distribution of a single sub-partition 20, the target phase distribution of all sub-partitions can be obtained by replication, and then arranged to form the complete phase distribution of the metasurface 2.

[0066] Combination Figure 7 As shown, a single sub-partition 20 is a rectangular structure, multiple sub-partitions 20 have different sizes, and multiple sub-partitions 20 are joined together to form a larger rectangular structure. Combined with... Figure 8 As shown, a single sub-partition 20 is a parallelogram structure, and multiple sub-partitions 20 have different sizes. These multiple sub-partitions 20 are then joined together to form a larger parallelogram structure. Since the multiple sub-partitions 20 have different shapes, for each uniquely shaped or sized sub-partition 20, the phase distribution is independently optimized using an iterative algorithm to obtain its corresponding target phase distribution.

[0067] The overall phase distribution of metasurface 2 obtained from the theory needs to be physically reproduced through microstructure 201. Essentially, it involves discretizing the continuous target phase distribution function and mapping it to an array of microstructures 201 with specific geometric shapes and fabrication parameters, which will be elaborated in detail in the design method below.

[0068] In one embodiment, the superlens 100 is configured to collimate incident light rays. Specifically, by incorporating a collimating phase design into the overall phase distribution of the metasurface 2, collimation and imaging can be integrated into the metasurface 2. The collimating phase can be... Figure 9 The formula shown is the result of calculation. This formula is prior art and will not be described in detail in this application.

[0069] This application includes an optical projection system, including the superlens 100 in any of the above technical solutions. The optical projection system realizes projection imaging. By using the superlens 100 in the technical solution of this application, the uniformity of the imaging of the optical projection system can be significantly improved.

[0070] The optical projection system includes a light source 300 and an imaging system. The light emitted from the same point of the light source 300 forms a sub-light field after passing through the sub-partition 20, which is coherent. The target imaging surface is located in the imaging system. The light source, the superlens, and the target imaging surface are arranged along the direction of light propagation. The optical projection system uses the phase modulation capability of the superlens 100 to shape the light emitted from the light source 300 into a specific spatial distribution image.

[0071] The coherence of the light source 300 is the physical basis for realizing the output of sub-light fields from multiple sub-regions 20 and the coherent superposition of the sub-light fields.

[0072] The imaging system is located in the subsequent optical path of the superlens 100. The target imaging surface is a specific plane in the imaging system on which the target image formed by the superlens, such as a dot pattern or a flat-top light spot, is clearly presented.

[0073] In one embodiment, the light source 300 can be selectively configured as a point light source, a lattice light source, a plane wave, or Gaussian light; the light source 300 can be selectively switched between point light source, lattice light source, plane wave, or Gaussian light. The aforementioned sub-regions 20 have low sensitivity to changes in global incident parameters, and the sub-light fields of each sub-region 20 have the function of coherent superposition to suppress the average intensity error of the biased light field. This makes the metasurface 2 have good generalization ability for different incident light fields. After selectively switching between some different light sources 300, the imaging system can maintain a certain uniformity, thereby ensuring imaging quality.

[0074] Specifically, when applied to plane wave shaping, the light source 300 switches between plane wave and Gaussian intensity distributions to ensure good imaging results. Specifically, when applied to array light sources, the partitioned superlens ensures a highly uniform dot pattern when switching between array light source applications designed according to various practical needs.

[0075] In one embodiment, the light source 300 is configured to be positionally offset relative to the superlens 100, with the incident light spot center of the light source 100 moving no more than 50% of the size of a single sub-region 20 on the metasurface 2. Each sub-region 20 exhibits poor sensitivity to changes in global incident parameters, and the sub-fields of each sub-region 20 have the effect of coherently superimposing and suppressing the average intensity error of the biased light field, thus making the metasurface 2 highly robust to changes in incident light parameters. Even without superimposing collimating phases, the light source 300 can be positionally offset relative to the metasurface 2, and the uniformity and imaging quality of the imaging system can still be guaranteed after the offset.

[0076] In the first embodiment of this application, the light source 300 is a point light source. After passing through different sub-regions of the optical projection system and traveling through similar optical paths, it can meet the requirements of coherent superposition. After the point light source passes through the metasurface 2, multiple sub-regions 20 generate multiple sub-dot matrix images on the target imaging surface. The spatial characteristics of the multiple sub-dot matrix images are the same, that is, the dot matrix pattern is the same. After coherent superposition, a highly uniform target dot matrix image is formed. Combined with... Figure 10 As shown, the light intensity distribution map in the frequency domain coordinates is displayed. It can be seen that after sub-partition 20 generates sub-dot matrix images and superimposes them to form the target dot matrix image, the imaging quality of the target dot matrix image is better.

[0077] When the light source becomes a dot matrix light source, continue to refer to... Figure 11 As can be clearly seen from the normalized light intensity distribution map, the light intensity of the sub-dot matrix image is not uniform, but the target dot matrix image obtained by coherent superposition has a highly uniform light intensity distribution.

[0078] In the second embodiment of this application, the light source 300 is a dot matrix light source, specifically a vertical cavity surface emitting laser (VCSEL).

[0079] Combination Figure 12 a and Figure 12 As shown in b. Figure 12 a is a dot matrix distribution using VCSEL array 1' combined with a traditional superlens 2', while Figure 12 Using the dot matrix distribution diagram of the VCSEL array combined with the partitioned superlens, it can be seen that under the same optical environment, the imaging quality is significantly improved after using the partitioned superlens 100.

[0080] Existing metasurfaces exhibit poor generalization to different incident light fields. This is because traditional metalenses are highly sensitive to the incident light field, making it impossible for them to achieve precise modulation after switching between different incident light fields, leading to a sharp drop in image quality. Combined with... Figure 13a As shown, the existing flat-top light shaping system includes a plane wave light source 300', a collimating device 400', and a traditional superlens 100'. After designing a monolithic metasurface for collimating plane waves, a flat-top light spot with high uniformity can be obtained.

[0081] Combination Figure 13b As shown, keeping other optical environments unchanged, the collimated plane wave source 300' is replaced with Gaussian light 310'. As can be seen from the light intensity distribution diagram, the light intensity after imaging exhibits a highly concentrated and uneven phenomenon, and the imaging quality cannot meet the actual requirements.

[0082] Combination Figure 13c As shown, in the third embodiment of this application, in Figure 13a In terms of optical conditions, a partitioned superlens 100 is designed, and then the collimated plane wave is replaced with Gaussian light, combined with... Figure 13c As can be seen from the imaging results, the light intensity can still maintain a certain uniformity, thus ensuring the imaging quality. In other words, the optical projection system of the partitioned superlens 100 in this application still has high uniformity in the target image when the plane wave is switched to Gaussian light, verifying the generalization of the partitioned superlens 100.

[0083] Combination Figure 14-16 As shown, in several specific embodiments of this application, the light source 300 is a VCSEL array. However, depending on different practical needs, the incident light field and the target light field differ in various specific embodiments. Nevertheless, when the partitioned superlens is applied to the aforementioned specific optical projection systems, it can ensure a high uniformity of the target image.

[0084] Combination Figure 14As shown, in the fourth embodiment of this application, the optical projection system includes a collimating device 400, which and the superlens 100 are separately arranged, and the metasurface 2 does not need to superimpose collimating phases. Specifically, the metasurface 2 is configured in a nine-square grid shape, with each sub-division measuring 0.3mm * 0.3mm. The light source 300 operates at a wavelength of 940nm, has an effective focal length of 1mm, a field of view of the target image of 50° * 70°, and a target image uniformity of 90%.

[0085] Combination Figure 15 As shown in the fifth embodiment of this application, the optical projection system does not include a separately configured collimating device; the metasurface 2 needs to be superimposed with a collimating phase. Specifically, the metasurface 2 is configured in a nine-square grid shape, with each sub-division measuring 0.9mm*0.9mm. The light source 300 operates at a wavelength of 850nm, has an effective focal length of 3mm, and the target image has a field of view of 120°*90°. The target image uniformity reaches over 90%. By superimposing the collimating phase using the metasurface 2, the optical system can be simplified while achieving high uniformity.

[0086] Combination Figure 16 As shown in the sixth embodiment of this application, the optical projection system does not include a separately configured collimating device; the metasurface 2 requires superimposed collimating phase. The superlens 100 is specifically configured with an irregular shape; for example, the metasurface 2 is formed by staggered splicing of 9-12 rectangular sub-sections 20 of different sizes. In this case, while maintaining the operating wavelength of the light source 300 at 850nm, the effective focal length at 3mm, and the field of view of the target image at 120°*90°, the uniformity of the target image can be maintained at over 90%.

[0087] Combination Figure 17 As shown, in the seventh embodiment of this application, the optical projection system does not include a separately configured collimating device; the metasurface 2 needs to be superimposed with collimating phase. The light source 300 is a collimated plane wave, and the metasurface 2 is specifically configured as a nine-square grid shape, with each sub-division measuring 0.2mm * 0.2mm. The light source 300 operates at a wavelength of 940nm, has an effective focal length of 0.6mm, a field of view of the target image of 50° * 70°, and a target image uniformity of 80%.

[0088] This application includes a method for designing a superlens, used to fabricate the superlens 100 described above. The method for designing the superlens 100 includes the following steps: S1: Based on the incident light field model and the target light field distribution, the target phase distribution is calculated. The incident light field model includes at least the incident parameters such as wavelength, wavefront type, amplitude distribution, and coherence. The target light field distribution includes at least the indicators such as image type, spatial size, light intensity uniformity, and working focal length. Computational holography, such as GS and deep learning algorithms, is used to design the target phase distribution of a single sub-region 20. The target phase distribution ensures that, under the ideal design model, a single sub-region 20 can independently modulate the incident light into a sub-target image.

[0089] The incident light field model is a point source, a lattice source, a collimated plane wave, or a collimated Gaussian intensity distribution, all of which are incident orthogonally onto the superlens 100. A unified and simplified incident light field model is used for each sub-region to improve the generalization and robustness of the superlens 100 under actual complex incident conditions.

[0090] S2: Divide the metasurface 2 of the superlens into multiple independent sub-regions 20; each sub-region 20 has independent spatial characteristics. In order to simplify the actual manufacturing process and combination design, and to facilitate theoretical algorithm optimization and verification, it is preferable that the multiple sub-regions 20 have a periodic and regular two-dimensional rectangular arrangement, such as a nine-square grid or a sixteen-square grid arrangement.

[0091] S3: Copy the target phase distribution and assign multiple target phase distributions to multiple sub-partitions 20 in a one-to-one correspondence; multiple sub-partitions 20 obtain the same target phase distribution to ensure that multiple sub-target images are coherently superimposed on the target imaging plane to form a sub-target image.

[0092] The fact that multiple sub-regions 20 have the same target phase distribution means that, theoretically, each sub-region 20 corresponds to an identical incident light field model. In theoretical design, the target phase distribution of each sub-region is independently designed based on a simplified incident light field model, such as a normally incident plane wave. This allows each sub-region 20 to function as a self-consistent functional unit, generating a complete sub-target image using only the light incident on its own region, and the sub-target images generated by multiple sub-regions 20 are coherently superimposed. This decouples the globally complex incident light field perturbation to each sub-region 20, reducing sensitivity to changes in the global incident light field.

[0093] S4: Combine the target phase distributions of all sub-regions to form the overall phase distribution of the superlens; the overall phase distribution of the superlens is a superposition and combination of multiple parallel, redundant, and fault-tolerant target phase distributions.

[0094] S5: Map the overall phase distribution to the physical parameters of the microstructure 201 array on the metasurface; in other words, reproduce the overall phase distribution using the microstructure 201 on the metasurface. Specifically, taking a cylindrical metasurface as an example, parameters are first scanned using electromagnetic simulation software for the specific operating wavelength, substrate, and material system of the metasurface. By changing the radius of the nanopillars and calculating the phase delay of their transmitted light field, a database of the correspondence between the geometric parameters of the nanopillars, such as the radius of the nanopillars, and the phase modulation amount can be established.

[0095] After obtaining the relationship between the structural geometric parameters and the phase modulation amount, each phase value in the designed, discretized target phase distribution map is mapped one by one to the specific geometric parameters of the corresponding nanopillars on the metasurface. For example, if a microstructure 201 requires a first phase, the radius of the nanopillar that provides the closest first phase is selected and placed on the microstructure 201. By completing this mapping operation for all microstructures 201 on the metasurface, the final phase distribution containing the complete nanostructure array is obtained, which can then be further processed to obtain an actual optical device.

[0096] The unit design of the artificial microstructure 201 is not limited to cylinders; square cylinders, elliptical cylinders, nanopores, or more complex composite structures can be used depending on actual process or performance requirements. Correspondingly, the phase modulation mechanism is not limited to size; it can also be a rotation angle, etc.

[0097] The beneficial effects of this invention are as follows: each sub-region 20 has the same target phase distribution, so that the light emitted from each sub-region 20 can independently form a sub-target image on the target imaging surface; multiple sub-target images formed by multiple sub-regions are coherently superimposed on the target imaging surface to form a target image, and the sub-target image and the target image have the same spatial characteristics; the first uniformity of the sub-target image is less than the second uniformity of the target image, which improves the uniformity of the target image and thus improves the imaging quality of the target image; each sub-region 20 independently generates a sub-target image based on the local light incident on itself, rather than based on the global light, thereby improving the robustness of the metasurface 2 to changes in incident parameters and its generalization to different incident light fields.

[0098] This can be formed by referring to any of the technical solutions provided above, and will not be elaborated here.

[0099] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0100] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A superlens having a metasurface and a microstructure, wherein the microstructure is disposed on the metasurface, characterized in that: The metasurface has multiple sub-partitions and multiple sets of microstructures, and each sub-partition contains a set of microstructures. Each of the sub-regions has the same target phase distribution, such that the light rays emitted from each of the sub-regions can independently form a sub-target image on the target imaging surface; Multiple sub-target images formed by multiple sub-regions are coherently superimposed on the target imaging plane to form a target image, and the sub-target images and the target image have the same spatial features.

2. The superlens according to claim 1, characterized in that, The target phase distribution of the sub-region is configured such that each sub-region can independently generate the sub-target image on the target imaging surface based on the light incident on its own region.

3. The superlens according to claim 1, characterized in that, Each of the sub-partitions has an actual phase distribution, and the actual phase distributions of multiple sub-partitions are not the same; the actual phase distribution is achieved through the actual manufacturing parameters of the microstructure, and there is a random phase deviation between the actual phase distribution and the target phase distribution.

4. The superlens according to claim 1, characterized in that, The multiple sub-partitions are arranged in a periodic or non-periodic manner, and the multiple sub-partitions are spliced ​​together to form the metasurface.

5. The superlens according to claim 1, characterized in that, Multiple sub-partitions may have the same or different shapes.

6. The superlens according to claim 1, characterized in that, The superlens is configured to collimate incident light rays.

7. A method for designing a superlens, characterized in that, Includes the following steps: Based on the incident light field model and the target light field distribution, the target phase distribution is calculated; The metasurface of the superlens is divided into multiple independent sub-regions; The target phase distribution is copied, and the multiple target phase distributions are assigned to the multiple sub-partitions in a one-to-one correspondence. The target phase distributions of all the sub-regions are combined to form the overall phase distribution of the superlens; The overall phase distribution is mapped to the physical parameters of the microstructure array on the metasurface.

8. The method for designing a superlens according to claim 7, characterized in that, The incident light field model is a point source, a lattice source, a collimated plane wave, or a collimated Gaussian light.

9. An optical projection system, characterized in that, Includes the superlens according to any one of claims 1-6.

10. The optical projection system according to claim 9, characterized in that, The optical projection system includes a light source and an imaging system. The sub-light field formed by light emitted from the same point of the light source after passing through the sub-partition has coherence. The target imaging surface is located in the imaging system. The light source, the superlens, and the target imaging surface are arranged along the direction of light propagation.

11. The optical projection system according to claim 10, characterized in that, The light source can be selectively configured as: a point light source, a dot matrix light source, a plane wave, or Gaussian light; the light source can be selectively switched between the point light source, the dot matrix light source, the plane wave, or the Gaussian light.

12. The optical projection system according to claim 10, characterized in that, The light source is configured to be positionally offset relative to the superlens, and the incident light spot center of the light source moves a distance on the supersurface that is no greater than 50% of the size of a single sub-section.

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