Design methods, devices, and electronic equipment for superlenses-based optical systems

Abstract

This application provides a design method, apparatus, and electronic device for a superlens-based optical system, belonging to the technical field of optical systems. The method obtains a discrete configuration of the superlens' nanostructure based on an initial phase distribution at the dominant wavelength, and then optimizes the discrete configuration and discrete phase distribution of the superlens' nanostructure. This results in a superlens with higher imaging quality over a wider spectrum than superlenses obtained using traditional optimization methods. The design method, apparatus, and electronic device for this superlens-based optical system optimize the discrete phase distribution of the superlens, effectively suppressing differences in imaging performance of the optical system containing the superlens at different wavelengths.

Description

Technical Field

[0001] This application relates to the technical field of optical elements, and more specifically, to a design method, apparatus, and electronic device for an optical system based on a superlens. Background Technology

[0002] A metalens is a type of metasurface, which is a subwavelength artificial nanostructure film. The amplitude, phase, and polarization of incident light can be modulated through nanostructure units placed on it. In contrast, existing refractive lenses adjust the optical path difference by varying the thickness and curvature.

[0003] When superlenses are applied to broadband imaging optical systems, their imaging performance varies at different wavelengths. This is because superlenses differ from traditional refractive lenses in their imaging principles, and existing optical system design methods do not incorporate optimization steps for superlenses.

[0004] Therefore, there is an urgent need for a design method, device, and electronic equipment for optical systems based on superlenses. Summary of the Invention

[0005] To address the existing technical problems, embodiments of this application provide a design method, apparatus, electronic device, and computer-readable storage medium for an optical system based on a superlens.

[0006] In a first aspect, embodiments of this application provide a design method for an optical system based on a superlens, characterized in that the method includes:

[0007] Determine the target wavelength band of the optical system, and select the dominant wavelength and reference wavelength within the target wavelength band;

[0008] Determine the system variables and evaluation function of the optical system;

[0009] Based on the dominant wavelength, system optimization is performed to obtain the initial phase distribution of the superlens in the optical system;

[0010] Based on the initial phase distribution, the structural parameters of the nanostructure of the superlens are determined and the discretized arrangement of the nanostructure is configured to obtain a discrete phase distribution;

[0011] The phase of the nanostructure at the dominant wavelength and the reference wavelength is applied to the superlens in the optical system, and the evaluation function of the optical system at the dominant wavelength and the reference wavelength is calculated; it is then determined whether the evaluation function of the optical system at the dominant wavelength and the reference wavelength satisfies the target condition.

[0012] If so, output the structural parameters of the nanostructure, the discretized arrangement, and the discrete phase distribution;

[0013] If not, optimize the discrete phase distribution until the evaluation function is satisfied.

[0014] Optionally, the number of dominant wavelengths is 1, and the number of reference wavelengths is greater than or equal to 1; the dominant wavelength is the center wavelength of the target band.

[0015] Optionally, optimizing the discrete phase distribution includes reconfiguring the structural parameters of the nanostructure and / or discretizing the arrangement and re-obtaining the modulated phase of the reference wavelength until the evaluation function of the optical system at the dominant wavelength and the reference wavelength satisfies the target condition.

[0016] Optionally, optimizing the discrete phase distribution includes fitting the discrete phase distribution at different wavelengths into a phase curve of a continuous function according to the spatial location, and optimizing the fitted continuous phase.

[0017] Optionally, optimizing the discrete phase distribution further includes optimizing the phase coefficients of the discrete phase distribution of the superlens at different wavelengths.

[0018] Optionally, the system variables include any one or more combinations of the lens spacing, lens curvature, lens thickness, and phase coefficients of each order of the superlens in the optical system.

[0019] Optionally, the evaluation function shall at least satisfy:

[0020] ;

[0021] Where MF is the evaluation function, Vi represents the actual value of each system variable, Ti represents the target value of each system variable, and Wi represents the weighting factor of each system variable.

[0022] Optionally, the target value of the evaluation function includes any one or more combinations of modulation transfer function, relative illumination, root mean square speckle, phase deviation of nanostructure, aberration, and dispersion.

[0023] Optionally, when the optical system includes both a refractive lens and a superlens, the curvature and thickness of the refractive lens are variables, while the curvature and thickness of the superlens are constants.

[0024] Optionally, calculating the evaluation function includes setting weights based on the light intensity of the dominant wavelength and the reference wavelength.

[0025] Optionally, the point spread function of the optical system satisfies:

[0026] ;

[0027] Among them, PSFi Either the reference wavelength or the dominant wavelength The point spread function is given by m, where m is the sum of the number of the dominant wavelength and the reference wavelength.

[0028] Optionally, the point spread function also satisfies:

[0029] ;

[0030] Among them, PSF i For any one of the reference wavelength and the dominant wavelength Point spread function over long distances; For any wavelength The ratio of light intensity to total light intensity.

[0031] Secondly, embodiments of this application also provide a design apparatus for an optical system based on a superlens, characterized in that it is applied to the design method provided in any of the above embodiments, the design apparatus comprising:

[0032] The input module is configured to input the target band, system variables, and evaluation function of the optical system.

[0033] The optimization module is configured to calculate and / or optimize the phase of the superlens in the optical system;

[0034] The evaluation module is configured to calculate the evaluation function of the optical system;

[0035] The judgment module is configured to determine whether the evaluation function satisfies the target condition;

[0036] The output module is configured to output the structural parameters, discretized arrangement, and discrete phase distribution of the nanostructure of the superlens.

[0037] Optionally, the calculation and / or optimization of the phase of the optical system includes:

[0038] System optimization is performed based on the dominant wavelength of the target band to obtain the initial phase distribution; and / or,

[0039] The discrete phase distribution of the nanostructure is obtained based on the initial phase distribution; and / or,

[0040] Calculate the modulation phase of the reference wavelength.

[0041] Optionally, the design device further includes:

[0042] The matching module is configured to select structural parameters of a nanostructure that match the initial phase distribution.

[0043] Optionally, the design device further includes:

[0044] The balancing module is configured to set the weights corresponding to each wavelength in the evaluation function based on the light intensity of different wavelengths within the target band.

[0045] Thirdly, an electronic device includes a bus, a transceiver, a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the transceiver, the memory, and the processor are connected via the bus, and the computer program, when executed by the processor, implements the steps in the design method provided in any of the above embodiments.

[0046] Fourthly, a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any of the methods provided in any of the above embodiments.

[0047] The design method, apparatus, electronic device, and computer-readable storage medium for a superlens-based optical system provided in this application obtain an initial phase distribution based on the dominant wavelength. Then, based on the initial phase distribution, the structural parameters and discretized distribution of the nanostructure are configured to obtain a discrete phase distribution. The evaluation function of the superlens corresponding to the discrete phase distribution at multiple wavelengths is calculated and analyzed to determine whether the structure and phase of the current superlens need further optimization. Therefore, this design method obtains the discretized configuration of the superlens nanostructure based on the initial phase distribution at the dominant wavelength, and then optimizes the discretized configuration of the superlens nanostructure and the discrete phase distribution. This effectively suppresses the difference in imaging performance of the optical system containing the superlens at different wavelengths, resulting in a superlens with higher imaging quality over a wider spectrum than that obtained by traditional optimization methods. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of this application or the background art, the accompanying drawings used in the embodiments of this application or the background art will be described below.

[0049] Figure 1 A flowchart illustrating a design method for a superlens-based optical system provided in an embodiment of this application is shown.

[0050] Figure 2 This paper shows a schematic diagram of an optional structure of the optical system provided in an embodiment of the present application;

[0051] Figure 3 It shows Figure 2 An optional phase distribution of the superlens in the optical system shown;

[0052] Figure 4 It shows Figure 2An optimized alternative phase distribution for the superlens of the optical system shown;

[0053] Figure 5 It shows Figure 2 An optional fitting result for the discrete phase distribution of the superlens of the optical system shown;

[0054] Figure 6 It shows Figure 2 Another possible fitting result for the discrete phase distribution of the superlens of the optical system shown;

[0055] Figure 7 It shows Figure 2 The modulation transfer function curves of the superlens of the optical system shown are at different wavelengths;

[0056] Figure 8 The following diagram illustrates the modulation transfer function curves of an optical system provided in this application under different fields of view and different wavelengths.

[0057] Figure 9 This illustration shows an optional structural schematic diagram of a design apparatus for a superlens-based optical system provided in an embodiment of this application;

[0058] Figure 10 This illustration shows another optional structural schematic diagram of a design device for a superlens-based optical system provided in an embodiment of this application;

[0059] Figure 11 A schematic diagram of an optional structure of the electronic device provided in an embodiment of this application is shown.

[0060] The reference numerals in the figure represent:

[0061] 10 - Filter; 20 - Aperture; 30 - Superlens;

[0062] 1110 - Bus; 1120 - Processor; 1130 - Transceiver; 1140 - Bus interface; 1150 - Memory; 1160 - User interface. Detailed Implementation

[0063] In the description of the embodiments of this application, those skilled in the art should understand that the embodiments of this application can be implemented as methods, apparatuses, electronic devices, and computer-readable storage media. Therefore, the embodiments of this application can be specifically implemented in the following forms: entirely hardware, entirely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software. Furthermore, in some embodiments, the embodiments of this application can also be implemented as a computer program product contained in one or more computer-readable storage media, which includes computer program code.

[0064] The aforementioned computer-readable storage medium may be any combination of one or more computer-readable storage media. Computer-readable storage media include: electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any combination thereof. More specific examples of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), flash memory, optical fiber, optical disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any combination thereof. In embodiments of this application, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0065] The computer program code contained in the aforementioned computer-readable storage medium may be transmitted using any suitable medium, including wireless, wire, optical fiber, radio frequency (RF), or any suitable combination thereof.

[0066] Computer program code for performing the operations of the embodiments of this application can be written in assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, integrated circuit configuration data, or in one or more programming languages ​​or combinations thereof. The programming languages ​​include object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The computer program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer or an external computer via any type of network, including a local area network (LAN) or a wide area network (WAN).

[0067] The embodiments of this application describe the provided methods, apparatus, and electronic devices through flowcharts and / or block diagrams.

[0068] It should be understood that each block of a flowchart and / or block diagram, as well as combinations of blocks in a flowchart and / or block diagram, can be implemented by computer-readable program instructions. These computer-readable program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine that, when executed by a computer or other programmable data processing apparatus, creates means for implementing the functions / operations specified in the blocks of the flowchart and / or block diagram.

[0069] These computer-readable program instructions may also be stored in a computer-readable storage medium that enables a computer or other programmable data processing device to function in a particular manner. In this way, the instructions stored in the computer-readable storage medium produce an instruction apparatus product that includes the functions / operations specified in the blocks of a flowchart and / or block diagram.

[0070] Computer-readable program instructions may also be loaded onto a computer, other programmable data processing apparatus or other device to cause a series of operational steps to be performed on the computer, other programmable data processing apparatus or other device to produce a computer-implemented process, such that the instructions that execute on the computer or other programmable data processing apparatus provide a process for implementing the functions / operations specified in the blocks of the flowchart and / or block diagram.

[0071] When existing superlenses are used for broadband imaging, the imaging effect varies at different wavelengths. The inventors of this application have discovered that optimization based on existing optical design software and methods cannot effectively suppress this difference.

[0072] The inventors of this application unexpectedly discovered that the reason for this phenomenon lies in the fact that existing optical design methods and software are designed to better optimize optical systems composed of traditional refractive lenses. Therefore, most existing optical design methods and software are based on spatially continuous phase distributions (the phase is continuous in space), and the dispersion relation is based solely on the material's refractive index. However, superlenses manipulate incident electromagnetic waves through nanostructures. Different nanostructures in a superlens have different optical responses to different wavelengths, the modulated phase of the structural units changes non-linearly with wavelength, and the nanostructures are spatially discrete. Therefore, traditional optical design methods and software are not suitable for optimizing superlenses.

[0073] In view of the above problems, this application provides a design method for an optical system based on a superlens. The method optimizes the phase of the superlens' nanostructure, which is spatially discrete and nonlinearly varies with wavelength, to improve the imaging quality of the optical system over a wide spectrum. The embodiments of this application are described below with reference to the accompanying drawings.

[0074] Figure 1 A flowchart illustrating a design method for a superlens-based optical system provided in an embodiment of this application is shown. Figure 1 As shown, the specific implementation of this method is described below.

[0075] Step one: Determine the target wavelength band of the optical system, and select the dominant wavelength and reference wavelength within the target wavelength band. According to the embodiments of this application, the target wavelength band is the operating wavelength band of the optical system, which is typically a wideband.

[0076] In some optional embodiments, m wavelengths are selected in the target band. From these m wavelengths, one wavelength is selected as the dominant wavelength, and n wavelengths are selected as reference wavelengths, where m = n + 1, m and n are both integers, and m ≥ 2. Optionally, the aforementioned m wavelengths consist of a dominant wavelength and reference wavelengths. The number of dominant wavelengths is 1, and the number of reference wavelengths is greater than or equal to 1. For example, the dominant wavelength of the target band is the center wavelength of the target band, the number of dominant wavelengths is 1, and the number of reference wavelengths is greater than or equal to 1. Optionally, the number of reference wavelengths is greater than or equal to 2.

[0077] According to embodiments of this application, the optical system can be composed entirely of superlenses, or it can be a hybrid refractive-superlens optical system composed of superlenses and conventional refractive lenses. Optionally, the field of view and / or entrance pupil diameter of the optical system are further determined.

[0078] Step two involves determining the system variables and evaluation functions of the optical system. Specifically, the system variables are determined based on the basic architecture (i.e., optical parameters) of the optical system. System variables directly affect the optical system's ability to control the light field. System variables include any combination of one or more of the following: lens spacing, lens curvature, lens thickness, and phase coefficients of various orders of the superlens. For example, when the optical system includes both traditional refractive lenses and superlenses, the curvature and thickness of the refractive lenses are set as variables, while the thickness and curvature of the superlenses are set as constants.

[0079] Step 3: Optimize the system based on the dominant wavelength of the target band to obtain the initial phase distribution of the superlens in the optical system.

[0080] According to the embodiments of this application, when obtaining the initial phase distribution, an initial value is selected for the already determined system variables to begin optimization. The initial value of the system variables can be obtained through calculation or determined empirically. In this step, optimization is not performed directly on multiple wavelengths in the working band or on the discrete phase of the superlens. Instead, a dominant wavelength is determined within the working band, and the system variables are optimized for the dominant wavelength. The initial phase distribution of the superlens is thus obtained and used as the initial value for global optimization of the optical system. It should be noted that in the optical system provided by this application, the initial phase of the superlens is spatially continuous and can be obtained quickly using conventional continuous phase optimization methods (such as genetic algorithms).

[0081] Step four: Based on the initial phase distribution, determine the structural parameters of the nanostructure of the superlens and configure the discretized arrangement of the nanostructure to obtain a discrete phase distribution. The initial optimization obtained in the above optimization steps is based on the dominant wavelength, while the distribution of the nanostructure in the superlens is discrete. Furthermore, the phase of the superlens changes non-linearly with wavelength. Therefore, according to the embodiment of this application, an initial phase based on the dominant wavelength is first obtained, then the structural parameters of the nanostructure are selected based on the initial phase, and then the selected nanostructure is discretized. In this way, a discrete phase distribution of the superlens matching the dominant wavelength and its nearby continuous wavelengths can be obtained. According to the embodiment of this application, the structural parameters of the nanostructure include characteristic dimensions and structure type, etc.

[0082] Optionally, the aforementioned nanostructures can be selected from a nanostructure database. This database includes various structure types and other structural parameters. For example, nanostructure types include cylinders, rings, prisms, and cross-shaped prisms. It should be understood that the same phase can correspond to multiple structure types. For instance, a superlens corresponding to the same phase distribution can include the same type of nanostructure or nanostructures of different types. Furthermore, the same phase distribution can be achieved using cylindrical nanostructures or cross-shaped prism nanostructures. It is easy to understand that when selecting a nanostructure, the preferred structure type, feature size, and distribution pattern are those closest to the initial phase distribution. It should be understood that the computational difficulty during optimization and the complexity of the fabrication process must also be considered when selecting a nanostructure.

[0083] It should be noted that since phase optimization can be optionally performed after configuring the structure type, feature size and discretization distribution of the nanostructure, cylindrical nanostructures can be selected to improve the optimization rate and reduce the optimization and fabrication difficulty.

[0084] In fact, the response of the superlens to the target wavelength is the response of the discretized nanostructures to the target wavelength. Once the discretized configuration of the nanostructures (structure type, feature size, and arrangement, etc.) is determined, the modulation phase of each light-receiving position on the superlens for the incident electromagnetic wave is also determined accordingly. Since the discrete phase distribution for the dominant wavelength and its nearby continuous wavelengths is already determined, the optical response of the discretized nanostructures to the entire target wavelength is unknown. Therefore, it is necessary to select a reference wavelength other than the dominant wavelength in the target wavelength for phase analysis. According to the embodiments of this application, by sequentially reading the modulation phase of each configured nanostructure in the database at the reference wavelength, the discrete phase distribution of the superlens under the current discretized configuration of the nanostructures can be obtained.

[0085] Step 5: Apply the phase of the nanostructure at the dominant wavelength and the reference wavelength to the superlens in the optical system, and calculate the evaluation function of the optical system at the dominant wavelength and the reference wavelength.

[0086] According to embodiments of this application, the evaluation function of the optical system is determined based on the design objectives of the optical system. Optionally, the design objectives of the evaluation function include modulation transfer function (MTF), relative illumination (RI), root mean square (RMS) speckle, phase deviation of the nanostructure, and various aberrations and dispersions. It should be understood that phase deviation of the nanostructure is unavoidable during nanostructure matching and optimization processes, specifically when replacing nanostructures. That is, there is a certain deviation between the theoretically calculated phase and the actual phase of the matched nanostructure; as long as the phase deviation of the nanostructure is controlled within an allowable range, it is acceptable.

[0087] For example, the evaluation function of the optical system must at least satisfy the following formula (1):

[0088] (1)

[0089] Where MF is the evaluation function, Vi represents the actual value of each system variable, Ti represents the target value of each system variable, and Wi represents the weighting factor of each system variable. For example, when solving a high-resolution optical system, the MTF or RMS of the optical system can be used as the target value for optimization until the MF is obtained. 2 By finding the minimum value of , a high-resolution optical system that meets (or approximates) the design goals can be obtained.

[0090] In some example implementations, the design goal of this optical system is MTF (Modulation Transfer Function). MTF is a commonly used metric for evaluating the performance of an optical system. It describes the system's ability to transfer contrast from an object to an image at a specific resolution. MTF = 1 when the object and image distributions are perfectly aligned. However, every component in an optical system inevitably contributes to the image, making perfect alignment between object and image distributions virtually impossible. During the design of an optical system, the contribution of each component to the overall MTF should be reasonably considered to improve image quality. The MTF is calculated as follows:

[0091] (2)

[0092] (3)

[0093] in, Fourier transform; OTF is the optical transfer function, used to characterize the relative changes in modulation and lateral phase shift during imaging; PSF is the point spread function, used to describe the response of an imaging system to a point source or point object; () represents the horizontal and vertical coordinates of the PSF; The horizontal and vertical spatial resolutions of MTF or OTF.

[0094] MTF of optical systems is usually measured using sinusoidal gratings. At locations off-center from the image field, the MTF values ​​measured by sinusoidal gratings along the tangential direction and those along the radial direction are different. The MTF curve generated by lines parallel to the diameter is called the sagittal curve, denoted as S (Sagittal), while the MTF curve generated by lines perpendicular to the tangent is called the meridional curve, denoted as M (Meridional) or T (Tangential). In the calculation methods of formulas (2) and (3), the sagittal curve is the transverse intercept of MTF at the center, and the meridional curve is the longitudinal intercept of MTF at the center, as shown in formulas (4) and (5):

[0095] (4)

[0096] ;(5)

[0097] It should be understood that the light intensity of different wavelengths in a broadband target band may be inconsistent. Therefore, optionally, when designing the evaluation function in the embodiments of this application, weights can be set according to the light intensity of each wavelength (for example, W in formula (1)).i value).

[0098] In principle, the point spread function (PSF) is the intensity distribution of light from a point source after passing through an optical system. Since the intensities of incident light of different wavelengths can be directly added, the point spread function over a wide optical band is...

[0099] (6)

[0100] In formula (6), PSF i Either the reference wavelength or the dominant wavelength The point spread function is given by equation (6), where m is the sum of the number of the dominant wavelength and the reference wavelength. After obtaining the PSF of the target band (wideband) based on equation (6), the MTF of the target band (wideband) can be calculated according to equations (2) and (3).

[0101] More advantageously, the point spread function also satisfies:

[0102] (7)

[0103] Among them, PSF i Either the reference wavelength or the dominant wavelength The point spread function below; For any wavelength The ratio of light intensity to total light intensity.

[0104] Based on formulas (2) to (7), this application provides a method for calculating the target band MTF of an optical system, and uses the target band MTF as a design target to evaluate the imaging quality of the optical system under the target band. This parameter can also be used to write evaluation functions. However, existing optical design software (such as Zemax or CodeV) can only analyze the MTF of a single wavelength and cannot evaluate the MTF of the optical system under a wide band.

[0105] Step Six: Determine if the evaluation function meets the target conditions. If the evaluation function meets the target conditions, it means that configuring the nanostructure of the superlens in the current way can enable the optical system to achieve its design goals. At this point, the structural parameters, discretized arrangement, and discrete phase distribution of the nanostructure can be output. If not, optimize the discrete phase distribution until the evaluation function is met.

[0106] For example, optimizing the discrete phase distribution includes a reconfiguration step, i.e., reconfiguring the structural parameters and / or discretization arrangement of the nanostructure to update the modulation phase of the optical system at a reference wavelength other than the dominant wavelength until the reconfigured nanostructure causes the evaluation function of the optical system at both the dominant wavelength and the reference wavelength to satisfy the target condition. For example, the design target of the optical system is any threshold; if the current system's evaluation function is less than this threshold, then the optical system satisfies the target condition.

[0107] According to the embodiments of this application, after steps three and four, the discrete phase distribution of the superlens under multiple wavelengths has been determined, and the discrete phase distribution has a better controllable response for the main wavelength. Optionally, the discrete phase distribution determined in steps three and four is directly subjected to phase optimization, so that the discrete phase distribution also has a good optical response at a reference wavelength outside the main wavelength in the target band.

[0108] Therefore, the optimization of the discrete phase distribution in this embodiment may optionally include a fitting step, that is, fitting the discrete phase distribution at different wavelengths into a phase curve of a continuous function according to the spatial position r. By optimizing the continuous phase obtained by fitting, the optimization efficiency can be improved, and corresponding phase coefficients can be generated for each wavelength. The reason why this embodiment can achieve rapid optimization by fitting the phase is that the size of the nanostructure of the superlens is on the subwavelength scale, and the phase change caused by fitting has a small impact.

[0109] The optimization of the discrete phase distribution may include a fitting step and / or a reconfiguration step. When both fitting and reconfiguration steps are included, the fitting step is performed first, followed by the reconfiguration step. For example, actual structural units are selected for matching to the continuous phase distribution obtained by the fitting step. In this case, to better match the phase of multiple wavelengths, the nanostructure database may include various structural types, such as cylinders and rings. Subsequently, the arrangement of the structural units will be readjusted, and the discrete phase distribution of the superlens for multiple wavelengths will be updated. Then, steps five and six are executed to determine whether to proceed to the next iteration.

[0110] The embodiments of this application exemplarily provide a phase distribution of a superlens as shown in the following formulas (8) and (9):

[0111] (8)

[0112] (9)

[0113] in, λ is the wavelength of the incident light, r is the distance from the center of any nanostructure on the superlens surface to the center point of the superlens surface, (x, y) are the coordinates of the superlens surface, n is the order of the polynomial phase curve, and coefficients a and b are the phase coefficients of each order. Since this scheme needs to consider broadband light, different wavelengths... The phase coefficients a and b will both change.

[0114] Furthermore, optimization in the fitting step method can also be applied to the phase coefficients at different wavelengths. In this case, there are fewer variables (only a few sets of phase coefficients compared to all spatially discrete phase values), and the phase function is spatially continuous, making it suitable for traditional optical simulation software and resulting in high optimization efficiency.

[0115] Example 1

[0116] Example 1 provides an exemplary design method for a superlens-based optical system, which optimizes for dispersion. The architecture of the optical system in Example 1 is as follows: Figure 2 As shown. Figure 2 In this optical system, a filter 10, an aperture stop 20, and a superlens 30 are arranged sequentially along the incident light path, with the nanostructure of the superlens 30 facing the object side. The remaining optical parameters of the optical system in Example 1 are shown in Table 1. The filter 10 is used to filter out incident light outside the 820nm to 870nm range. The optimization objective of this optical system is to achieve a weighted average MTF of greater than 0.7 for the meridional MTF and sagittal MTF within a spatial frequency range of 10 lp / mm in the 820nm to 870nm band.

[0117] Table 1

[0118]

[0119] In Example 1, 850nm was selected as the main wavelength, and 820nm, 830nm, 840nm, 860nm and 870nm were selected as reference wavelengths. Figure 3 The phase distribution of a cylindrical nanostructure within a radius of 0-0.1 mm for a superlens is shown, with the continuous curve representing continuous phase pairs 2. The continuous curve after taking the remainder, and the stepped broken line represent the phase distribution of the matched nanostructure units at the corresponding positions, which are discrete in spatial position. Figure 3 The target phase in the design is the phase distribution of the superlens that theoretically satisfies the design target (i.e., the initial phase distribution at the dominant wavelength). Figure 3 The phase of the nanopillars in the diagram represents the phase distribution of the actual discretized nanostructure. Figure 3 It is known that, according to the design method provided in this application, the nanostructure is discretized based on the initial phase distribution, and the resulting discrete phase distribution has a high degree of agreement with the theoretical target phase distribution.

[0120] Figure 4 It shows Figure 2 The discrete phase distribution of the medium-cylindrical nanostructure, after optimization according to step six in the embodiments of this application, is the discrete phase distribution at the dominant wavelength and the reference wavelength. For example... Figure 4 As shown, the electromagnetic responses of each nanostructure unit differ at different wavelengths, resulting in different modulation phases and broken-line phase distributions at each wavelength. The method provided in this application, through optimization, achieves high consistency in the response of the nanostructure in the superlens to different wavelengths within the target band. In other words, the design of the superlens-based optical system provided in this application suppresses the differences in imaging at different wavelengths and reduces the dispersion of the optical system.

[0121] Table 2 shows the phase coefficients of the superlens at various wavelengths obtained after fitting the discrete phase distribution and phase gradient into a continuous phase curve. The phase coefficients in Table 2 can be approximately applied to traditional optical design software based on continuous phase distribution. Figure 5 The fitting results of the discrete phase distribution of the superlens in the range of 0 to 0.1 mm are shown. Figure 6 The fitting results of the discrete phase distribution of the superlens in the range of 0.85 mm to 0.853 mm are shown. The phase distribution separated at different wavelengths determines the separation of the fitted phase curves. (Comparison) Figure 5 and Figure 6 It can be seen that in the region far from the center of the superlens, the spacing between the phase curves of different wavelengths is more obvious. That is to say, along the direction away from the center of the superlens, the difference in the phase modulation of different wavelengths by the superlens increases, and the dispersion becomes more obvious. Figure 7 This illustrates the imaging performance of the optical system at different wavelengths after optimization of the discrete phase distribution. Figure 7 As can be seen, after optimization, the MTF curves of the optical system at different wavelengths are close to the diffraction limit, and the sagittal MTF curve and the meridional MTF curve show high consistency. In summary, the optical system designed by the improved design method of the superlens-based optical system in this application exhibits excellent imaging performance and minimal differences in response to different wavelengths.

[0122] Table 2

[0123]

[0124] Example 2

[0125] Example 2 provides another example of a design method for a superlens-based optical system, which optimizes the MTF of the optical system. In the optical system provided in Example 2, the superlens has a diameter of 2.4 mm, operates in the wavelength range of 560 nm to 870 nm, and the design target is a broadband MTF greater than 0.6 at the incident angle field of view. The other optical parameters are the same as in Example 1. Figure 8 MTF curves for different wavelengths are shown at incident angles of 0°, 10.95°, 18.25°, 25.55°, 29.20°, 32.85°, and 36.50°. (Source: [Original Text]) Figure 8 It can be seen that the MTF curves of the optical system designed by the design method provided in this application are all greater than 0.6 for each field of view at different wavelengths, and the sagittal MTF curve and the meridional MTF curve have high consistency. In summary, the optical system designed by the improved design method of the superlens-based optical system in this application has high resolution and excellent imaging performance.

[0126] The above text combined Figures 1 to 8 This application describes in detail the design method of an optical system based on a superlens provided in the embodiments. This method can also be implemented by corresponding devices. The following will be combined with Figure 9 and Figure 10 This application provides a detailed description of the design apparatus for a superlens-based optical system provided in the embodiments of this application.

[0127] Figure 9 A schematic diagram of the design device for a superlens-based optical system provided in an embodiment of this application is shown. Figure 9 As shown, the design device for the superlens-based optical system includes: an input module configured to input the target wavelength band, system variables, and evaluation function of the optical system;

[0128] The optimization module is configured to calculate and / or optimize the phase of the superlens in the optical system;

[0129] The evaluation module is configured to calculate the evaluation function for the optical system;

[0130] The judgment module is configured to determine whether the evaluation function meets the target conditions.

[0131] The output module is configured to output the structural parameters, discretized arrangement, and discrete phase distribution of the nanostructure of the superlens.

[0132] According to embodiments of this application, calculating and / or optimizing the phase of the optical system includes:

[0133] System optimization based on the dominant wavelength yields the initial phase distribution of the superlens in the optical system; and / or,

[0134] The discrete phase distribution of the nanostructure in the superlens is obtained based on the initial phase distribution; and / or,

[0135] Calculate the modulation phase of the reference wavelength.

[0136] According to the embodiments of this application, such as Figure 10 As shown, the design apparatus for this superlens-based optical system also includes:

[0137] The matching module is configured to select structural parameters of a nanostructure that match the initial phase distribution; and / or,

[0138] The balancing module is configured to set the weights corresponding to each wavelength in the evaluation function based on the light intensity of different wavelengths within the target band.

[0139] In addition, this application also provides an electronic device, including a bus, a transceiver, a memory, a processor, and a computer program stored in the memory and executable on the processor. The transceiver, the memory, and the processor are connected via a bus. When the computer program is executed by the processor, it implements the various processes of the above-described design method embodiment of the optical system based on a superlens and achieves the same technical effect. To avoid repetition, it will not be described again here.

[0140] For details, see Figure 11 As shown in the figure, this application embodiment also provides an electronic device, which includes a bus 1110, a processor 1120, a transceiver 1130, a bus interface 1140, a memory 1150 and a user interface 1160.

[0141] In this embodiment of the application, the electronic device further includes: a computer program stored in the memory 1150 and executable on the processor 1120, wherein the computer program, when executed by the processor 1120, performs the following steps:

[0142] Determine the target wavelength band of the optical system, and select the dominant wavelength and reference wavelength within the target wavelength band;

[0143] Determine the system variables and evaluation functions of the optical system;

[0144] The initial phase distribution of the superlens in the optical system is obtained by optimizing the system based on the dominant wavelength.

[0145] Based on the initial phase distribution, the structural parameters of the nanostructure of the superlens are determined and the discretized arrangement of the nanostructure is configured to obtain the discrete phase distribution;

[0146] The phase of the nanostructure at the dominant wavelength and the reference wavelength is applied to the superlens in the optical system, and the evaluation function of the optical system at the dominant wavelength and the reference wavelength is calculated.

[0147] Determine whether the evaluation function satisfies the objective condition;

[0148] If so, output the structural parameters, discretized arrangement, and discrete phase distribution of the nanostructure;

[0149] If not, optimize the discrete phase distribution until the evaluation function is satisfied.

[0150] Optionally, when the computer program is executed by the processor 1120, it may also perform the following steps:

[0151] Directly perform discrete phase optimization; or...

[0152] The discrete phase distributions at different wavelengths are fitted into phase curves of continuous functions according to their spatial locations, and the resulting continuous phases are then optimized.

[0153] Optionally, when the computer program is executed by the processor 1120 in the step of "applying the phase of the nanostructure at multiple wavelengths to the superlens in the optical system and calculating the evaluation function of the optical system at multiple wavelengths", the processor specifically implements the following steps:

[0154] Superimpose point spread functions at different wavelengths in the target band;

[0155] The modulation transfer function of the optical system in the target band is calculated based on the point spread function at different wavelengths in the target band.

[0156] According to an embodiment of this application, transceiver 1130 is used to receive and transmit data under the control of processor 1120.

[0157] In this embodiment of the application, the bus architecture (represented by bus 1110) may include any number of interconnected buses and bridges, and bus 1110 connects various circuits including one or more processors represented by processor 1120 and memory represented by memory 1150.

[0158] Bus 1110 represents one or more of several types of bus architectures, including memory buses and memory controllers, peripheral buses, Accelerated Graphics Port (AGP), processors, or local buses using any bus architecture from various bus architectures. As an example and not a limitation, such architectures include: Industry Standard Architecture (ISA) buses, Micro Channel Architecture (MCA) buses, Enhanced ISA (EISA) buses, Video Electronics Standards Association (VESA) buses, and Peripheral Component Interconnect (PCI) buses.

[0159] The processor 1120 can be an integrated circuit chip with signal processing capabilities. In implementation, the steps of the above method embodiments can be completed by integrated logic circuits in the processor hardware or by instructions in software form. The processors mentioned above include: general-purpose processors, central processing units (CPUs), network processors (NPs), digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), complex programmable logic devices (CPLDs), programmable logic arrays (PLAs), microcontroller units (MCUs) or other programmable logic devices, discrete gates, transistor logic devices, and discrete hardware components. They can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. For example, the processor can be a single-core processor or a multi-core processor, and the processor can be integrated on a single chip or located on multiple different chips.

[0160] Processor 1120 can be a microprocessor or any conventional processor. The method steps disclosed in the embodiments of this application can be directly executed by a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can reside in readable storage media known in the art, such as Random Access Memory (RAM), Flash Memory, Read-Only Memory (ROM), Programmable Read-Only Memory (PROM), Erasable Programmable Read-Only Memory (EPROM), registers, etc. The readable storage medium is located in the memory, and the processor reads the information in the memory and, in conjunction with its hardware, completes the steps of the above method.

[0161] Bus 1110 can also connect various other circuits, such as peripheral devices, voltage regulators, or power management circuits. Bus interface 1140 provides an interface between bus 1110 and transceiver 1130, all of which are well known in the art. Therefore, the embodiments of this application will not be described further.

[0162] Transceiver 1130 can be a single element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices over a transmission medium. For example, transceiver 1130 receives external data from other devices, and transceiver 1130 is used to send data processed by processor 1120 to other devices. Depending on the nature of the computer system, a user interface 1160 may also be provided, such as a touchscreen, physical keyboard, monitor, mouse, speaker, microphone, trackball, joystick, or stylus.

[0163] It should be understood that, in this embodiment of the application, memory 1150 may further include memory remotely configured relative to processor 1120, and such remotely configured memory can be connected to a server via a network. One or more portions of the aforementioned network may be an ad hoc network, intranet, extranet, virtual private network (VPN), local area network (LAN), wireless local area network (WLAN), wide area network (WAN), wireless wide area network (WWAN), metropolitan area network (MAN), Internet, public switched telephone network (PSTN), ordinary old-style telephone service (POTS), cellular telephone network, wireless network, Wi-Fi network, and combinations of two or more of the aforementioned networks. For example, cellular telephone networks and wireless networks can be Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA), WiMAX, General Packet Radio Service (GPRS), Wideband Code Division Multiple Access (WCDMA), Long Term Evolution (LTE), LTE Frequency Division Duplex (FDD), LTE Time Division Duplex (TDD), Advanced Long Term Evolution (LTE-A), Universal Mobile Telecommunications System (UMTS), Enhanced Mobile Broadband (eMBB), Massive Machine Type Communication (mMTC), Ultra Reliable Low Latency Communications (uRLLC), etc.

[0164] It should be understood that the memory 1150 in the embodiments of this application may be volatile memory or non-volatile memory, or may include both volatile memory and non-volatile memory. Non-volatile memory includes: read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory.

[0165] Volatile memory includes random access memory (RAM), which serves as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (Synchlink DRAM, SLDRAM), and direct memory bus RAM (DRRAM). The memory 1150 of the electronic device described in this application embodiment includes, but is not limited to, the above and any other suitable types of memory.

[0166] In this embodiment, memory 1150 stores the following elements of operating system 1151 and application 1152: executable modules, data structures, or subsets thereof, or extended sets thereof.

[0167] Specifically, the operating system 1151 includes various system programs, such as a framework layer, a core library layer, and a driver layer, used to implement various basic business functions and handle hardware-based tasks. The application program 1152 includes various applications, such as a media player and a browser, used to implement various application functions. Programs implementing the methods of the embodiments of this application may be included in the application program 1152. The application program 1152 includes applets, objects, components, logic, data structures, and other computer system executable instructions that perform specific tasks or implement specific abstract data types.

[0168] Furthermore, this application also provides a computer-readable storage medium storing a computer program thereon. When the computer program is executed by a processor, it implements the various processes of the above-described design method embodiment of the superlens-based optical system and achieves the same technical effect. To avoid repetition, it will not be described again here.

[0169] Specifically, when a computer program is executed by a processor, it can perform the following steps:

[0170] Determine the optical parameters of the optical system;

[0171] Determine the system variables and evaluation functions of the optical system;

[0172] The system is optimized based on the dominant wavelength of the target band to obtain the initial phase distribution;

[0173] Based on the initial phase distribution, the structural parameters of the nanostructure are determined and the discretized arrangement of the nanostructure is configured to obtain the discrete phase distribution.

[0174] Calculate the phase modulation of a number of reference wavelengths other than the dominant wavelength by the discretized arrangement of nanostructures;

[0175] The phase of the nanostructure at multiple wavelengths is applied to the superlens in the optical system, and the evaluation function of the optical system at multiple wavelengths is calculated; the multiple wavelengths include the dominant wavelength and a number of reference wavelengths.

[0176] Determine whether the evaluation function of the multi-wavelength optical system satisfies the target condition;

[0177] If so, output the structural parameters, discretized arrangement, and discrete phase distribution of the nanostructure;

[0178] If not, optimize the discrete phase distribution until the evaluation function is satisfied; or,

[0179] Reconfigure the structural parameters of the nanostructure and / or discretize its arrangement, and re-obtain the modulated phase of a number of reference wavelengths other than the dominant wavelength until the evaluation function of the optical system in multiple wavelengths meets the target conditions.

[0180] Alternatively, when a computer program is executed by a processor, it may also perform the following steps:

[0181] Directly perform discrete phase optimization; or...

[0182] The discrete phase distributions at different wavelengths are fitted into phase curves of continuous functions according to their spatial locations, and the resulting continuous phases are then optimized.

[0183] Optionally, when the computer program is executed by the processor in the step of "applying the phase of the nanostructure at multiple wavelengths to the superlens in the optical system and calculating the evaluation function of the optical system at multiple wavelengths", the processor specifically implements the following steps:

[0184] Superimpose point spread functions at different wavelengths in the target band;

[0185] The modulation transfer function of the optical system in the target band is calculated based on the point spread function at different wavelengths in the target band.

[0186] Computer-readable storage media include: permanent and non-permanent, removable and non-removable media, which are tangible devices capable of retaining and storing instructions for use by an instruction execution device. Computer-readable storage media include: electronic storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, and any suitable combination thereof. Computer-readable storage media include: phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), non-volatile random access memory (NVRAM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, optical disc read-only memory (CD-ROM), digital versatile optical disc (DVD) or other optical storage, magnetic tape storage, magnetic disk storage or other magnetic storage devices, memory sticks, mechanical encoding devices (such as punched cards or raised structures in grooves on which instructions are recorded), or any other non-transfer medium that can be used to store information accessible by a computing device. As defined in the embodiments of this application, computer-readable storage media do not include temporary signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses passing through fiber optic cables), or electrical signals transmitted through wires.

[0187] In the several embodiments provided in this application, it should be understood that the disclosed apparatus, electronic devices, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, or it may be an electrical, mechanical, or other form of connection.

[0188] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of these units can be selected to solve the problems addressed by the embodiments of this application, depending on actual needs.

[0189] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0190] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the embodiments of this application, in essence, or the parts that contribute to the prior art, or all or part of the technical solutions, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (including: a personal computer, a server, a data center, or other network device) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media listed above that can store program code.

[0191] The above description is merely a specific implementation of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the embodiments of this application should be included within the protection scope of the embodiments of this application. Therefore, the protection scope of the embodiments of this application should be determined by the protection scope of the claims.

Claims

1. A design method for an optical system based on a superlens, characterized in that, The method includes: Determine the target wavelength band of the optical system, and select the dominant wavelength and reference wavelength within the target wavelength band; Determine the system variables and evaluation function of the optical system; Based on the dominant wavelength, system optimization is performed to obtain the initial phase distribution of the superlens in the optical system; Based on the initial phase distribution, the structural parameters of the nanostructure of the superlens are determined and the discretized arrangement of the nanostructure is configured. A reference wavelength other than the dominant wavelength is selected in the target band for phase analysis to obtain a discrete phase distribution of the superlens that matches the dominant wavelength and its nearby continuous wavelengths. The phase of the nanostructure at the dominant wavelength and the reference wavelength is applied to the superlens in the optical system, and the evaluation function of the optical system at the dominant wavelength and the reference wavelength is calculated; it is then determined whether the evaluation function satisfies the target condition. If so, output the structural parameters of the nanostructure, the discretized arrangement, and the discrete phase distribution; If not, optimize the discrete phase distribution until the evaluation function is satisfied.

2. The design method according to claim 1, characterized in that, The number of the main wavelength is 1, and the number of the reference wavelength is greater than or equal to 1. The dominant wavelength is the center wavelength of the target band.

3. The design method according to claim 1, characterized in that, The optimization of the discrete phase distribution includes: fitting the discrete phase distribution at different wavelengths into a phase curve of a continuous function according to the spatial position, and optimizing the continuous phase obtained by fitting.

4. The design method according to claim 1, characterized in that, The optimization of the discrete phase distribution includes: reconfiguring the structural parameters and / or discretizing the arrangement of the nanostructure and re-obtaining the modulated phase of the reference wavelength until the evaluation function of the optical system at the dominant wavelength and the reference wavelength meets the target condition.

5. The design method according to claim 1, characterized in that, The optimization of the discrete phase distribution also includes: The phase coefficients of the discrete phase distribution of the superlens at different wavelengths are optimized.

6. The design method according to claim 1, characterized in that, The system variables include any combination of one or more of the following: lens spacing, lens curvature, lens thickness, and phase coefficients of each order of the superlens in the optical system.

7. The design method according to claim 1, characterized in that, The evaluation function must at least satisfy: ； Where MF is the evaluation function, V i T represents the actual value of each system variable. i W represents the target value of each system variable. i This represents the weighting factor for each system variable.

8. The design method according to claim 1 or 7, characterized in that, The target value of the evaluation function includes any one or more combinations of modulation transfer function, relative illumination, root mean square speckle, phase deviation of nanostructure, aberration, and dispersion.

9. The design method according to claim 6, characterized in that, When the optical system includes both a refractive lens and a superlens, the curvature and thickness of the refractive lens are variables, while the curvature and thickness of the superlens are constants.

10. The design method according to claim 1 or 7, characterized in that, Calculating the evaluation function includes setting weights based on the light intensity of the dominant wavelength and the reference wavelength.

11. The design method according to claim 1, characterized in that, The point spread function of the optical system satisfies: ； Among them, PSF i Either the reference wavelength or the dominant wavelength The point spread function is given by m, where m is the sum of the number of the dominant wavelength and the reference wavelength.

12. The design method according to claim 11, characterized in that, The point spread function also satisfies: ； Among them, PSF i Either the reference wavelength or the dominant wavelength The point spread function below; For any wavelength The ratio of light intensity to total light intensity.

13. A design device for an optical system based on a superlens, characterized in that, Applied to the design method as described in any one of claims 1-12, the design apparatus comprises: The input module is configured to input the target band, system variables, and evaluation function of the optical system. An optimization module is configured to calculate and / or optimize the phase of the superlens in the optical system; The evaluation module is configured to calculate the evaluation function of the optical system; The judgment module is configured to determine whether the evaluation function satisfies the target condition; The output module is configured to output the structural parameters, discretized arrangement, and discrete phase distribution of the nanostructure of the superlens.

14. The design apparatus according to claim 13, characterized in that, The calculation and / or optimization of the phase of the optical system includes: System optimization is performed based on the dominant wavelength of the target band to obtain the initial phase distribution of the superlens in the optical system; and / or, The discrete phase distribution of the nanostructure of the superlens is obtained based on the initial phase distribution; and / or, Calculate the modulation phase of the reference wavelength.

15. The design apparatus according to claim 13, characterized in that, The design device further includes: The matching module is configured to select structural parameters of a nanostructure that match the initial phase distribution; and / or The balancing module is configured to set the weights corresponding to each wavelength in the evaluation function based on the light intensity of different wavelengths within the target band.

16. An electronic device comprising a bus, a transceiver, a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the transceiver, the memory, and the processor are connected via the bus, and the computer program, when executed by the processor, implements the steps of the method according to any one of claims 1-12.

17. A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method according to any one of claims 1-12.

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