A metasurface phase coefficient optimization method, device and electronic equipment

Abstract

The present invention provides a metasurface phase coefficient optimization method, device and electronic device, wherein the method includes: determining initial structural parameters, the structural parameters at least include: phase coefficients of each order; using the initial structural parameters as the initial values ​​of the current structural parameters, optimizing the current structural parameters in a manner of optimizing the equivalent refractive index difference corresponding to the current structural parameters, and determining the optimized target structural parameters. The metasurface phase coefficient optimization method, device and electronic device provided by the embodiments of the present invention can obtain the target structural parameters that meet the process requirements after optimization by optimizing the equivalent refractive index difference of the current structural parameters, and the target structural parameters can make the nanostructure on its corresponding metasurface meet the periodic arrangement; the embodiments of the present invention innovatively optimize the phase coefficients of each order of the metasurface in the optical system, reducing the difficulty of the manufacturing process of the optical system at the beginning of the design, so as to realize mass production.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and in particular to a metasurface phase coefficient optimization method, device, electronic device and computer-readable storage medium. Background Art

[0002] In theory, the phase coefficient of the metasurface can take any value; but in reality, the phase distribution of the metasurface obtained based on the phase coefficient of the unconstrained metasurface shows that the phase corresponding to the nanostructure changes frequently within a very short radius, that is, the arrangement of the nanostructure within a very short radius must be adjusted multiple times accordingly, and does not satisfy the periodic arrangement. In practical applications, it is reflected in the need to place nanostructures of different phases one by one, which will greatly increase the difficulty of the metasurface manufacturing process and cannot be achieved in mass production.

[0003] Currently, there is no literature or patent that constrains the range of metasurface phase coefficients in a metalens optical system, or an optical system that combines a metalens with a traditional refractive lens (also known as a refractive-metahybrid system). Summary of the invention

[0004] In order to solve the existing technical problems, the embodiments of the present invention provide a metasurface phase coefficient optimization method, device, electronic device and computer-readable storage medium.

[0005] In the first aspect, an embodiment of the present invention provides a method for optimizing the phase coefficient of a metasurface, comprising: determining initial structural parameters, wherein the structural parameters are used to limit the structural characteristics of the metasurface, and the structural parameters include at least: phase coefficients of each order; using the initial structural parameters as the initial values ​​of the current structural parameters, optimizing the current structural parameters in a manner of optimizing the equivalent refractive index difference corresponding to the current structural parameters, and determining the optimized target structural parameters; the equivalent refractive index difference is the difference between the maximum and minimum values ​​of the equivalent refractive index in the metasurface corresponding to the corresponding structural parameters, and the equivalent refractive index difference corresponding to the target structural parameters is less than a reasonable constant that meets the process requirements.

[0006] Optionally, the current structural parameters are optimized in a manner of optimizing the equivalent refractive index difference corresponding to the current structural parameters, including: cyclically performing parameter optimization operations on the current structural parameters until the equivalent refractive index difference corresponding to the optimized current structural parameters is less than the reasonable constant; the parameter optimization operation includes: determining the equivalent refractive index difference corresponding to the current structural parameters; judging whether the equivalent refractive index difference corresponding to the current structural parameters is less than the reasonable constant; if the current structural parameters meet the requirements, using the current structural parameters as the target structural parameters; if the current structural parameters do not meet the requirements, updating the current structural parameters; wherein, the current structural parameters meeting the requirements includes that the equivalent refractive index difference corresponding to the current structural parameters is less than the reasonable constant.

[0007] Optionally, the parameter optimization operation also includes: determining the current performance parameters of the metasurface corresponding to the current structural parameters, and determining a current image quality evaluation factor; the current image quality evaluation factor includes the difference between the current performance parameters and the expected performance parameters and the difference between the equivalent refractive index difference corresponding to the current structural parameters and the reasonable constant; judging whether the current image quality evaluation factor is greater than a first limit value; wherein, the current structural parameters meeting the requirements also includes: the current image quality evaluation factor is less than or equal to the first limit value; the current structural parameters not meeting the requirements include: the equivalent refractive index difference corresponding to the current structural parameters is not less than the reasonable constant, and / or the current image quality evaluation factor is greater than the first limit value.

[0008] Optionally, determining a current image quality assessment factor comprises: determining the current image quality assessment factor based on a current image quality assessment function, wherein the current image quality assessment function comprises weighted processing of a first item and a second item, wherein the first item is used to represent the difference between the current performance parameter and the expected performance parameter, and the second item is used to represent the difference between the equivalent refractive index difference corresponding to the current structural parameter and the reasonable constant.

[0009] Optionally, the current image quality evaluation function satisfies:

[0010]

[0011] Wherein, M represents the current image quality evaluation factor; V i represents the current performance parameter of the ith type; T i represents the i-th desired performance parameter; w i represents the weight corresponding to the difference between the i-th current performance parameter and the expected performance parameter; F xrepresents the equivalent refractive index difference corresponding to the current structural parameters; C represents the reasonable constant; p represents the weight corresponding to the difference between the equivalent refractive index difference corresponding to the current structural parameters and the reasonable constant.

[0012] Optionally, the current image quality evaluation function also includes a third item, which is used to represent a return value that can be adjusted; the parameter optimization operation also includes: after determining the current image quality evaluation factor, updating the current image quality evaluation function by updating the return value; wherein, updating the return value includes: when the equivalent refractive index difference is greater than the reasonable constant, updating the return value to a first value; when the equivalent refractive index difference is equal to the reasonable constant, updating the return value to a second value; the first value is greater than the second value.

[0013] Optionally, updating the current image quality evaluation function in a manner of updating the return value includes: when the current image quality evaluation factor is less than or equal to a first limit value, updating the current image quality evaluation function in a manner of updating the return value.

[0014] Optionally, the weight corresponding to the difference between the equivalent refractive index difference corresponding to the current structural parameter and the reasonable constant is smaller than the weight corresponding to the return value.

[0015] Optionally, the current image quality evaluation function satisfies:

[0016]

[0017] Wherein, M represents the current image quality evaluation factor; V i represents the current performance parameter of the ith type; T i represents the i-th desired performance parameter; w i represents the weight corresponding to the difference between the i-th current performance parameter and the expected performance parameter; F x represents the equivalent refractive index difference corresponding to the current structural parameters; C represents the reasonable constant; p represents the weight corresponding to the difference between the equivalent refractive index difference corresponding to the current structural parameters and the reasonable constant; K represents the return value; q represents the weight corresponding to the return value.

[0018] Optionally, the performance parameters include at least one of effective focal length, F number, image height, diffuse spot size, field of view angle, relative aperture and total system length.

[0019] Optionally, determining the equivalent refractive index difference corresponding to the current structural parameters includes: determining the phase of the metasurface corresponding to the current structural parameters at multiple positions, and determining the equivalent refractive index at the corresponding position based on the phase, and there is a positive correlation between the equivalent refractive index and the phase; determining the maximum and minimum values ​​of the multiple equivalent refractive indices, and taking the difference between the maximum and minimum values ​​as the equivalent refractive index difference corresponding to the current structural parameters.

[0020] Optionally, determining the equivalent refractive index difference corresponding to the current structural parameters also includes: determining the maximum radius of the supersurface corresponding to the current structural parameters, taking a as the step size and selecting multiple radius values ​​from zero to the maximum radius, different radius values ​​representing different positions.

[0021] Optionally, the relationship between the equivalent refractive index and the phase satisfies:

[0022]

[0023] Wherein, F represents the equivalent refractive index; represents the phase at position r; k represents the wave number, and λ represents the wavelength; Hd represents the height of the nanostructure at position r.

[0024] Optionally, determining the initial structural parameters includes: determining original structural parameters; determining original performance parameters of the metasurface corresponding to the original structural parameters, and determining original image quality evaluation factors; the original image quality evaluation factors include the difference between the original performance parameters and the expected performance parameters; when the original image quality evaluation factors are less than or equal to a second limit value, using the original structural parameters as the initial structural parameters.

[0025] Optionally, the original image quality evaluation factor satisfies:

[0026]

[0027] Wherein, N represents the original image quality evaluation factor; V m represents the mth original performance parameter; T m represents the mth desired performance parameter; w m Represents the weight corresponding to the difference between the mth original performance parameter and the expected performance parameter.

[0028] Optionally, the phase of the metasurface corresponding to the current structural parameters at multiple positions satisfies one of the following formulas:

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035] Wherein, r represents the distance from the position to the center; (x, y) represents the coordinates of the position; f represents the focal length; a i , b i 、a ij and b ij They all represent the phase coefficients of the various orders.

[0036] Optionally, the structural parameters further include: the maximum radius and the height of the nanostructure.

[0037] In a second aspect, an embodiment of the present invention further provides a metasurface phase coefficient optimization device, comprising: a determination module and an optimization module.

[0038] The determination module is used to determine initial structural parameters, and the structural parameters are used to define the structural characteristics of the metasurface, and the structural parameters at least include: phase coefficients of each order.

[0039] The optimization module is used to use the initial structural parameters as the initial values ​​of the current structural parameters, optimize the current structural parameters in a manner of optimizing the equivalent refractive index difference corresponding to the current structural parameters, and determine the optimized target structural parameters; the equivalent refractive index difference is the difference between the maximum and minimum values ​​of the equivalent refractive index in the metasurface corresponding to the corresponding structural parameters, and the equivalent refractive index difference corresponding to the target structural parameters is less than a reasonable constant that meets the process requirements.

[0040] In the third aspect, an embodiment of the present invention provides 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 in any one of the above-described methods for optimizing the metasurface phase coefficient.

[0041] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps in any one of the above-mentioned methods for optimizing the metasurface phase coefficient are implemented.

[0042] The metasurface phase coefficient optimization method, device, electronic device and computer-readable storage medium provided in the embodiments of the present invention can obtain the target structural parameters that meet the process requirements (less than a reasonable constant) after optimization by optimizing the equivalent refractive index difference of the current structural parameters. The target structural parameters can make the nanostructure on its corresponding metasurface meet the periodic arrangement. The embodiments of the present invention innovatively optimize the structural parameters of the metasurface in the optical system (such as the phase coefficients of each order), thereby reducing the difficulty of the manufacturing process of the optical system at the beginning of the design to achieve mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the background technology, the drawings required for use in the embodiments of the present invention or the background technology will be described below.

[0044] Figure 1 A flow chart of a metasurface phase coefficient optimization method provided by an embodiment of the present invention is shown;

[0045] Figure 2 A schematic diagram of the phase distribution of a metasurface corresponding to an unconstrained phase coefficient in a metasurface phase coefficient optimization method provided in an embodiment of the present invention is shown;

[0046] Figure 3 A schematic diagram of the phase distribution of a metasurface corresponding to target structural parameters in the metasurface phase coefficient optimization method provided in an embodiment of the present invention is shown;

[0047] Figure 4 A flowchart of a specific metasurface phase coefficient optimization method provided by an embodiment of the present invention is shown;

[0048] Figure 5 A schematic diagram of simulation results obtained based on the method for optimizing the phase coefficient of a metasurface provided by an embodiment of the present invention is shown;

[0049] Figure 6 The optical modulation transfer function diagram generated by the metasurface corresponding to the unconstrained phase coefficient in a specific metasurface phase coefficient optimization method provided by an embodiment of the present invention is shown;

[0050] Figure 7 The figure shows an optical modulation transfer function diagram generated by a metasurface corresponding to a constrained phase coefficient in a specific metasurface phase coefficient optimization method provided by an embodiment of the present invention;

[0051] Figure 8 A schematic structural diagram of a metasurface phase coefficient optimization device provided by an embodiment of the present invention is shown;

[0052] Fig. 9A schematic structural diagram of an electronic device for executing a metasurface phase coefficient optimization method provided by an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0053] The embodiments of the present invention are described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0054] Figure 1 FIG. 4 is a flow chart showing a method for optimizing a metasurface phase coefficient provided by an embodiment of the present invention. Figure 1 As shown, the method includes the following steps 101-102.

[0055] Step 101: Determine initial structural parameters, where the structural parameters are used to define the structural features of the metasurface, and the structural parameters at least include: phase coefficients of each order.

[0056] A metasurface is a sub-wavelength artificial nanostructure film that can control the phase, amplitude, polarization and other characteristics of the incident light according to the nanostructure on it. Among them, the structural parameters of the metasurface can characterize the structural characteristics of the metasurface (such as the nanostructure on the metasurface). For example, the structural parameters can be phase coefficients of various orders used to represent the phase distribution of the metasurface. The phase coefficients of various orders can determine the phase distribution of the nanostructure on the metasurface (such as the phase corresponding to the nanostructure at different positions); further, the structural characteristics of the nanostructure, such as the height and period of the nanostructure, can be determined based on the phase of the nanostructure.

[0057] like Figure 2 As shown, Figure 2 The schematic diagram of the phase distribution of the metasurface corresponding to the unconstrained phase coefficient is shown, wherein the abscissa represents the radial distance of the nanostructure (the distance from the nanostructure to the center of the metasurface), and the ordinate represents the phase (unit: rad); Figure 2 It can be seen that the phase corresponding to the nanostructure of the metasurface obtained based on the unconstrained phase coefficient needs to change multiple times within an extremely short distance, that is, it is necessary to set up a variety of nanostructures with different phases within an extremely short distance of the metasurface (for example, it can be understood that the nanostructures are not arranged periodically, but need to be placed one by one; or, the phase change of the metasurface (such as a mutation from 0 to π) will cause some positions to have irregular lack of nanostructures, and it is still necessary to design the nanostructures in each period separately). From the current process level, this is obviously not achievable. Therefore, the embodiment of the present invention can impose a series of constraints on structural parameters such as phase coefficients of each order to achieve a phase distribution of nanostructures on the metasurface that better meets the process requirements.

[0058] The embodiment of the present invention can first determine a set of initial structural parameters. For example, the structural parameters to be optimized for the first time can be determined by optical design software (such as Zemax). The structural parameters include phase coefficients of various orders, and the structural parameters correspond to the structural characteristics of a certain metasurface.

[0059] Step 102: Using the initial structural parameters as the initial values ​​of the current structural parameters, optimizing the current structural parameters in a manner of optimizing the equivalent refractive index difference corresponding to the current structural parameters, and determining the optimized target structural parameters; the equivalent refractive index difference is the difference between the maximum and minimum values ​​of the equivalent refractive index in the metasurface corresponding to the corresponding structural parameters, and the equivalent refractive index difference corresponding to the target structural parameters is less than a reasonable constant that meets the process requirements.

[0060] In an embodiment of the present invention, the initial structural parameters determined in the above step 101 are used as the initial values ​​of the current structural parameters, that is, the current structural parameters optimized for the first time, and the current structural parameters optimized for the first time are optimized. The optimization method adopted in the embodiment of the present invention may be: determining the equivalent refractive index difference corresponding to the current structural parameters, for example, the equivalent refractive index difference may be expressed as the difference between the maximum value and the minimum value of the equivalent refractive index of the metasurface corresponding to the current structural parameters, optimizing the equivalent refractive index difference so that the equivalent refractive index difference is less than a reasonable constant; when the equivalent refractive index difference is less than a reasonable constant, determining the current structural parameters as the optimized target structural parameters; wherein the reasonable constant is a constant that meets the process requirements, for example, it may be any constant between 0.2 and 2.

[0061] For example, the maximum value F of the equivalent refractive index of the metasurface corresponding to the current structural parameters can be calculated according to the current structural parameters. max and the minimum value F min , and obtain the equivalent refractive index difference F x , if the equivalent refractive index difference F x If the current structural parameter is less than the reasonable constant C, it can be determined that the current structural parameter is the target structural parameter, that is, the metasurface corresponding to the target structural parameter can meet the process requirements. The phase distribution diagram of the metasurface corresponding to the target structural parameter can be seen in Figure 3 As shown by Figure 3 It can be seen that the nanostructure on the metasurface changes periodically. Within an extremely short radius distance, the phase change corresponding to the nanostructure is no longer frequent, which meets the process requirements.

[0062] The embodiment of the present invention can obtain the target structural parameters that meet the process requirements (less than a reasonable constant) after optimization by optimizing the equivalent refractive index difference of the current structural parameters. The target structural parameters can make the nanostructure on its corresponding metasurface meet the periodic arrangement. The embodiment of the present invention innovatively optimizes the structural parameters of the metasurface in the optical system (such as the phase coefficients of each order), thereby reducing the difficulty of the manufacturing process of the optical system at the beginning of the design to achieve mass production.

[0063] Optionally, optimizing the current structural parameters in a manner of optimizing the equivalent refractive index difference corresponding to the current structural parameters may include the following step A.

[0064] Step A: cyclically perform parameter optimization operations on the current structural parameters until the equivalent refractive index difference corresponding to the optimized current structural parameters is less than a reasonable constant.

[0065] In an embodiment of the present invention, the current structural parameters can be optimized by cyclically executing parameter optimization operations. For example, after performing parameter optimization operations on the current structural parameters, if the equivalent refractive index difference corresponding to the current structural parameters is not less than a reasonable constant, the parameter optimization operation can be cyclically executed until a current structural parameter having an equivalent refractive index difference less than a reasonable constant is obtained, and the current structural parameter is used as the target structural parameter.

[0066] The parameter optimization operation includes the following steps A1-A3.

[0067] Step A1: Determine the equivalent refractive index difference corresponding to the current structural parameters.

[0068] The maximum and minimum values ​​of the equivalent refractive index of the metasurface corresponding to the current structural parameters are calculated. The interval from the minimum value to the maximum value of the equivalent refractive index is the equivalent refractive index range, and the difference Fx between the maximum value and the minimum value can be used to concretely represent the equivalent refractive index difference.

[0069] Step A2: Determine whether the equivalent refractive index difference corresponding to the current structural parameters is less than a reasonable constant.

[0070] The equivalent refractive index difference corresponding to the current structural parameter is compared with a reasonable constant that meets the process requirements to determine whether the equivalent refractive index difference (such as the difference Fx) is smaller than the reasonable constant.

[0071] Step A3: When the current structural parameters meet the requirements, the current structural parameters are used as target structural parameters; when the current structural parameters do not meet the requirements, the current structural parameters are updated; wherein the current structural parameters meet the requirements including that the equivalent refractive index difference corresponding to the current structural parameters is less than a reasonable constant.

[0072] In the embodiments of the present invention, the necessary condition for the current structural parameters to meet the requirements is that the equivalent refractive index difference corresponding to the current structural parameters is less than a reasonable constant. That is, only when the equivalent refractive index difference corresponding to the current structural parameters is less than a reasonable constant, can it be further determined that the current structural parameters meet the requirements. Among them, if the current structural parameters meet the requirements, it can be determined that the equivalent refractive index difference corresponding to the current structural parameters must be less than a reasonable constant, and the current structural parameters are the target structural parameters that meet the process requirements; if the current structural parameters do not meet the requirements, the current structural parameters that do not meet the requirements are updated, and the update method can adopt the gradient descent method, etc., which is not limited in this embodiment. Among them, there are various ways to determine that the current structural parameters do not meet the requirements. For example, when the equivalent refractive index difference corresponding to the current structural parameters is not less than a reasonable constant, that is, the equivalent refractive index difference F x is greater than or equal to the reasonable constant C, it is determined that the current structural parameters are the structural parameters that do not meet the process requirements, and the current structural parameters do not meet the requirements; alternatively, it can also be determined that the current structural parameters do not meet the requirements through other judgment methods, and the embodiments of the present invention do not limit the judgment methods for the current structural parameters not meeting the requirements.

[0073] For example, when calculating the equivalent refractive index difference F x corresponding to the current structural parameters, it is judged whether the equivalent refractive index difference F x is less than the reasonable constant C. If F x <C, it can be considered that the current structural parameters meet the requirements, and it can be determined that the current structural parameters meet the process requirements, and it is the target structural parameter; if F x ≥C, it can be determined that the current structural parameters do not meet the process requirements, the current structural parameters do not meet the requirements, and the current structural parameters that do not meet the requirements are updated.

[0074] The embodiments of the present invention adopt a method of circularly executing parameter optimization operations to iteratively optimize the equivalent refractive index of the current structural parameters. When the current structural parameters do not meet the requirements, the current structural parameters can be updated, and circular iteration is performed until the current structural parameters that meet the requirements are obtained, and the target structural parameters that meet the process requirements are determined.

[0075] Optionally, in addition to the above steps A1 - A3 included in the parameter optimization operation, the following steps A4 - A5 may also be included.

[0076] Step A4: Determine the current performance parameters of the metasurface corresponding to the current structural parameters, and determine the current image quality evaluation factor; the current image quality evaluation factor includes the difference between the current performance parameters and the expected performance parameters and the difference between the equivalent refractive index difference corresponding to the current structural parameters and the reasonable constant.

[0077] In an embodiment of the present invention, the current structural parameters correspond to the corresponding metasurface, and the metasurface or the optical system having the metasurface usually has a variety of performance parameters, which are used to characterize some imaging effects that the metasurface or the optical system can bring (such as the imaging requirements corresponding to the optical system). Optionally, the performance parameters include: effective focal length, F number, image height, diffuse spot size, field angle, relative aperture and at least one of the total length of the system. In an embodiment of the present invention, one or more of the above performance parameters can be selected according to actual needs to determine the expected performance parameters that meet the system requirements in the metasurface or optical system to be constructed, that is, the target value expected to be achieved by the selected performance parameters; and determine the actual value of the above performance parameters corresponding to the metasurface corresponding to the current structural parameters, that is, the current performance parameters. Based on the current performance parameters and the expected performance parameters, as well as the equivalent refractive index and reasonable constant corresponding to the current structural parameters, the image quality evaluation factor corresponding to the metasurface can be determined, that is, the current image quality evaluation factor, and the current image quality evaluation factor is used as another condition for judging whether the current structural parameters meet the requirements (another condition other than whether the equivalent refractive index difference is less than a reasonable constant).

[0078] Specifically, the current image quality evaluation factor represents the difference between the current performance parameter and the expected performance parameter, and the difference between the equivalent refractive index difference of the current structural parameter and a reasonable constant; for example, the absolute value of the difference between the current performance parameter and the expected performance parameter can be used as the difference between the two, and the absolute value of the difference between the equivalent refractive index difference of the current structural parameter and a reasonable constant can be used as the difference between the two.

[0079] Step A5: Determine whether the current image quality evaluation factor is greater than the first limit value; wherein, the current structural parameters meet the requirements and also include: the current image quality evaluation factor is less than or equal to the first limit value; the current structural parameters do not meet the requirements and include: the equivalent refractive index difference corresponding to the current structural parameters is not less than a reasonable constant, and / or the current image quality evaluation factor is greater than the first limit value.

[0080] Among them, the first limit value represents the image quality evaluation factor corresponding to the optical system with the metasurface under the minimum imaging requirement. The embodiment of the present invention can further determine whether the current structural parameters meet the requirements by judging whether the current image quality evaluation factor is greater than the first limit value. In the case that the current image quality evaluation factor is less than or equal to the first limit value and the equivalent refractive index difference of the current structural parameter is less than a reasonable constant, it is determined that the current structural parameter meets the requirements; in the case that the current image quality evaluation factor is greater than the first limit value and / or the equivalent refractive index difference corresponding to the current structural parameter is not less than a reasonable constant, it is determined that the current structural parameter does not meet the requirements; for example, if the current image quality evaluation factor is greater than the first limit value, regardless of whether the equivalent refractive index difference corresponding to the current structural parameter is less than a reasonable constant, it can be determined that the current structural parameter does not meet the requirements. The embodiment of the present invention limits additional conditions on whether the current structural parameters meet the requirements by introducing the current image quality evaluation factor, so that the current structural parameters corresponding to the metasurface whose equivalent refractive index difference is less than a reasonable constant and whose current image quality evaluation factor is less than or equal to the first limit value are taken as the structural parameters that meet the requirements, so that the metasurface designed in the embodiment of the present invention not only meets the process requirements, but also meets the required imaging effects (such as imaging requirements).

[0081] Optionally, determining the current image quality assessment factor may include the following steps A41.

[0082] Step A41: Determine the current image quality evaluation factor based on the current image quality evaluation function, the current image quality evaluation function includes weighted processing of the first item and the second item, the first item is used to represent the difference between the current performance parameter and the expected performance parameter, and the second item is used to represent the difference between the equivalent refractive index difference corresponding to the current structural parameter and a reasonable constant.

[0083] Among them, the current image quality evaluation function is a mathematical relationship for determining the current image quality evaluation factor, and the current image quality evaluation function includes: weighting the difference between the current performance parameter and the expected performance parameter, and the difference between the equivalent refractive index difference corresponding to the current structural parameter and a reasonable constant. Among them, the difference between the current performance parameter and the expected performance parameter can be used as the first item of the current image quality evaluation function, and the difference between the equivalent refractive index difference corresponding to the current structural parameter and a reasonable constant can be used as the second item of the current image quality evaluation function. The embodiment of the present invention utilizes the current image quality evaluation function to conveniently calculate the current image quality evaluation factor.

[0084] Optionally, the current image quality evaluation function satisfies:

[0085]

[0086] Where M represents the current image quality assessment factor; V irepresents the i-th current performance parameter; T i represents the i-th expected performance parameter; w i represents the weight corresponding to the difference between the i-th current performance parameter and the expected performance parameter; F x represents the equivalent refractive index difference corresponding to the current structural parameters; C represents a reasonable constant; p represents the weight corresponding to the difference between the equivalent refractive index difference corresponding to the current structural parameters and the reasonable constant.

[0087] Specifically, the current image quality evaluation function can be expressed as the above mathematical relationship, where the first term It is used to indicate the influence ratio of the sum of the differences between multiple current performance parameters and the expected performance parameters on the current image quality evaluation factor. For example, the first item has the greatest influence on the current image quality evaluation factor, which can make the performance of the metasurface corresponding to the current structural parameters more in line with the expected ideal situation. For example, the four performance parameters of effective focal length, F number, image height and diffuse spot size can be selected. At this time, i = 1, 2, 3, 4. The effective focal length, F number, image height and diffuse spot size of the optical system to be designed correspond to T in the first item above. i , that is, the expected performance parameters; and the above performance parameters of the optical system composed of the metasurface corresponding to the current structural parameters correspond to V in the first item above i , that is, the current performance parameter; based on the weight w of the first item i , we can determine the influence of the first item on the current image quality evaluation factor. It is used to indicate the influence of the difference between the equivalent refractive index difference corresponding to the current structural parameter and the reasonable constant on the current image quality evaluation factor. For example, the influence of the second term on the current image quality evaluation factor is less than the influence of the first term on the current image quality evaluation factor. The second term can make the equivalent refractive index difference F corresponding to the current structural parameter x It can be closer to a reasonable constant C; based on the weight p of the second item, the influence proportion of the second item on the current image quality evaluation factor can be determined; after obtaining the first item and the second item, the current image quality evaluation factor M can be determined.

[0088] The embodiment of the present invention calculates the current image quality evaluation factor based on the current image quality evaluation function, and by assigning different weights to the first item and the second item, the subsequent update of the current structural parameters can gradually approach a more optimal direction.

[0089] Optionally, the current image quality evaluation function further includes a third term, which is used to represent the return value that can be adjusted; wherein, the third term is an item that can be increased when updating the current structural parameters, and is the same as the first and second terms of the current image quality evaluation function, both of which are mathematical expressions obtained through a certain weighting process. That is to say, the current image quality evaluation function includes weighting the first term, the second term, and the third term.

[0090] In the embodiments of the present invention, the parameter optimization operation may further include the following step A6.

[0091] Step A6: After determining the current image quality evaluation factor, update the current image quality evaluation function in the way of updating the return value.

[0092] Wherein, updating the return value includes step A61:

[0093] Step A61: When the equivalent refractive index difference is greater than the reasonable constant, update the return value to the first value; when the equivalent refractive index difference is equal to the reasonable constant, update the return value to the second value; the first value is greater than the second value.

[0094] In the embodiments of the present invention, the third term is used to further constrain the second term in the current image quality evaluation function. For example, it is made such that the equivalent refractive index difference corresponding to the current structural parameters not only approaches the reasonable constant, but is closer to being less than the reasonable constant. When it is necessary to update the current structural parameters, the return value can be adjusted once to change the third term and update the current image quality evaluation function. Specifically, in the embodiments of the present invention, the return values corresponding to different situations are different. According to the corresponding return value, the third term of the current image quality evaluation function can be updated. For example, when the equivalent refractive index difference F x corresponding to the current structural parameters is greater than the reasonable constant C, the return value in the third term is updated to the first value, and the first value is a value greater than 0; when the equivalent refractive index difference F x corresponding to the current structural parameters is equal to the reasonable constant C, the return value in the third term is updated to the second value, and the second value is a value greater than 0 and less than the first value. That is to say, when F x >C, the updated return value is a relatively large value greater than 0 (the first value), making the current image quality evaluation factor relatively large, indicating that the current structural parameters do not meet the requirements very well and need to update the current structural parameters in the next round to make it closer to the situation where F x <C; while when F x =C, the updated return value is a relatively small value greater than 0 (the second value), making the current image quality evaluation factor smaller compared to when F x>C is smaller, indicating that although the current structural parameter also does not fully meet the requirements, compared with the structural parameter that makes F x >C, it is closer to F x <In the case of <C, when updating the current structural parameter in the next round, it is possible to further optimize and update on the basis of the current structural parameter that makes F x =C, so that it is further closer to F x <In the case of <C.

[0095] Optionally, update the current image quality evaluation function in the way of updating the return value, including: when the current image quality evaluation factor is less than or equal to the first limit value, update the current image quality evaluation function in the way of updating the return value.

[0096] In the embodiment of the present invention, after determining the current image quality evaluation factor, it is possible to perform step A6 "update the current image quality evaluation function in the way of updating the return value" in the above steps only when the current image quality evaluation factor is less than or equal to the first limit value; that is, if the current image quality evaluation factor is greater than the first limit value, at this time, the return value may not be updated, that is, the current image quality evaluation function is not updated, and the "parameter optimization operation" of the next round is directly executed. For example, if the current image quality evaluation factor is less than or equal to the first limit value, then judge the size relationship between the equivalent refractive index difference F x and the reasonable constant C, and update the return value based on the above step A61; on the contrary, if the current image quality evaluation factor is greater than the first limit value, the size relationship between the equivalent refractive index difference F x and the reasonable constant C may not be judged, and the parameter optimization operation of the next round is directly performed.

[0097] Optionally, the weight corresponding to the difference between the equivalent refractive index difference corresponding to the current structural parameter and the reasonable constant is less than the weight corresponding to the return value.

[0098] In the embodiment of the present invention, the weight of the third item (the item with a return value) corresponding to the current image quality evaluation function is greater than the weight of the second item (the item corresponding to the difference between the equivalent refractive index difference corresponding to the current structural parameter and the reasonable constant) corresponding to the current image quality evaluation function. The purpose of doing this is to reduce the proportion of the second item (the equivalent refractive index difference F x is closer to the reasonable constant C) in the current image quality evaluation function, so that the equivalent refractive index difference F x is closer to being less than the reasonable constant C.

[0099] Optionally, the current image quality evaluation function satisfies:

[0100]

[0101] Where M represents the current image quality assessment factor; V i Indicates i Current performance parameters; T i represents the i-th expected performance parameter; w i represents the weight corresponding to the difference between the i-th current performance parameter and the expected performance parameter; F x Represents the equivalent refractive index difference corresponding to the current structural parameters; C represents a reasonable constant; p represents the weight corresponding to the difference between the equivalent refractive index difference corresponding to the current structural parameters and the reasonable constant; K represents the return value; q represents the weight corresponding to the return value.

[0102] Specifically, the current image quality evaluation function can be expressed as the above mathematical relationship with three terms, where the first term is and the second The meaning is consistent with that when the current image quality evaluation function includes two items, and will not be repeated here. It is used to indicate the influence ratio of the return value on the current image quality evaluation factor when the equivalent refractive index difference corresponding to the current structural parameter is not less than a reasonable constant. The influence of the third item on the current image quality evaluation factor is greater than the influence of the second item on the current image quality evaluation factor. The third item can make the equivalent refractive index difference F corresponding to the current structural parameter x It can be closer to being smaller than a reasonable constant C; based on the size of the return value K of the third item and the weight q, the influence proportion of the third item on the current image quality evaluation factor can be determined; and after determining the first item, the second item and the third item, the current image quality evaluation factor M is obtained.

[0103] The embodiment of the present invention calculates the current image quality evaluation factor based on the current image quality evaluation function including three items. By assigning different weights to the first item, the second item and the third item, the current structural parameters can gradually approach a better direction during the updating process (i.e., the above-mentioned parameter optimization operation).

[0104] Optionally, determining the equivalent refractive index difference corresponding to the current structural parameters includes the following steps A11-A12.

[0105] Step A11: Determine the phase of the metasurface corresponding to the current structural parameters at multiple positions, and determine the equivalent refractive index at the corresponding position according to the phase, and there is a positive correlation between the equivalent refractive index and the phase.

[0106] In the embodiment of the present invention, there is a positive correlation between the equivalent refractive index and the phase, that is, the larger the equivalent refractive index is, the larger the corresponding phase is, so the equivalent refractive index can be determined by calculating the phase. Specifically, multiple positions can be selected from the metasurface corresponding to the current structural parameters, the phase corresponding to each selected position can be calculated, and the equivalent refractive index at each position can be calculated based on the positive correlation between the phase and the equivalent refractive index.

[0107] Step A12: Determine the maximum value and the minimum value among the multiple equivalent refractive indices, and use the difference between the maximum value and the minimum value as the equivalent refractive index difference corresponding to the current structural parameters.

[0108] According to the multiple equivalent refractive indices respectively calculated from the multiple positions selected on the metasurface corresponding to the current structural parameters, the maximum and minimum values ​​can be selected from the multiple equivalent refractive indices, and the difference between the two is used as the equivalent refractive index difference corresponding to the current structural parameters.

[0109] Optionally, determining the equivalent refractive index difference corresponding to the current structural parameters also includes: determining the maximum radius of the supersurface corresponding to the current structural parameters, taking a as the step size and selecting multiple radius values ​​from zero to the maximum radius, different radius values ​​representing different positions.

[0110] In the embodiment of the present invention, before determining the phases of the hypersurface corresponding to the current structural parameters at multiple positions, the maximum radius of the hypersurface corresponding to the current structural parameters is first divided into multiple radius values ​​from zero with a step size a to obtain multiple positions corresponding to the multiple radius values. For example, the maximum radius of the hypersurface corresponding to the current structural parameters is r max , from 0 to r max Starting from the maximum radius r, with a step size a max Divided into multiple radius values, each radius value corresponds to a position.

[0111] Optionally, the relationship between the equivalent refractive index and the phase satisfies:

[0112]

[0113] Wherein, F represents the equivalent refractive index; represents the phase at position r; k represents the wave number, and λ represents the wavelength; Hd represents the height of the nanostructure at position r.

[0114] In the embodiment of the present invention, r represents a radius value, for example, any radius value divided according to the maximum radius of the metasurface corresponding to the current structural parameters, and the position corresponding to the radius value r can be directly represented by r. Among them, the equivalent refractive index F at the position r and the phase at the position r are The positive correlation between Indicates that the wave number k is a known quantity; and the height Hd of the nanostructure is also a physical quantity that can be determined. Therefore, based on the phase at position r and the known wave number k and the height Hd of the nanostructure, the equivalent refractive index at the radius r position in the metasurface corresponding to the current structural parameters can be calculated. Optionally, the structural parameters that need to be optimized may also include: the maximum radius and the height of the nanostructure; that is, in addition to the phase coefficients of each order, the structural parameters may also include the maximum radius and the height of the nanostructure. When determining the current structural parameters, the corresponding maximum radius of the metasurface and the height of the nanostructure may also be determined at the same time.

[0115] Optionally, determining initial structural parameters includes the following steps B1-B3.

[0116] Step B1: Determine the original structural parameters.

[0117] A set of structural parameters may be randomly generated as original structural parameters, for example, a set of structural parameters may be randomly generated as original structural parameters by using optical design software (such as Zemax).

[0118] Step B2: Determine the original performance parameters of the metasurface corresponding to the original structural parameters, and determine the original image quality evaluation factor; the original image quality evaluation factor includes the difference between the original performance parameters and the expected performance parameters.

[0119] Among them, the performance parameters of the metasurface corresponding to the original structural parameters are determined, and the performance parameters may include multiple types, such as F number, effective focal length, and diffuse spot size; the determined performance parameters are set as the original performance parameters, and the original image quality evaluation factor can be obtained by determining the difference between the original performance parameters and the expected performance parameters (the target value or expected value corresponding to the performance parameters). For example, the difference between each original performance parameter and the corresponding expected performance parameter can be determined respectively, and the sum of the differences between all the original performance parameters and the corresponding expected performance parameters is used as the original image quality evaluation factor.

[0120] Step B3: When the original image quality evaluation factor is less than or equal to the second limit value, the original structural parameters are used as initial structural parameters.

[0121] The second limit value may represent the image quality evaluation factor corresponding to the optical system having the metasurface corresponding to the original structural parameter under the minimum imaging requirement. For example, the second limit value may be the same as the first limit value mentioned above. If the original image quality evaluation factor is less than or equal to the second limit value, the original structural parameter corresponding to the metasurface corresponding to the original image quality evaluation factor may be used as the initial structural parameter.

[0122] Before determining the initial structural parameters, the embodiment of the present invention can determine the original performance parameters of the metasurface corresponding to the original structural parameters, and determine the original image quality evaluation factor based on the original performance parameters; by judging whether the original image quality evaluation factor is less than or equal to the image quality evaluation factor corresponding to the minimum imaging requirement (such as the second limit value), the original structural parameters that meet the minimum imaging requirement can be obtained, and the original structural parameters that meet the minimum imaging requirement are used as the initial structural parameters. This method can ensure that the determined initial structural parameters will not be higher than the second limit value, that is, the determined initial structural parameters meet the minimum imaging requirement.

[0123] Optionally, the original image quality evaluation factor satisfies:

[0124]

[0125] Where N represents the original image quality assessment factor; V m represents the mth original performance parameter; T m represents the mth expected performance parameter; w m Represents the weight corresponding to the difference between the mth original performance parameter and the expected performance parameter.

[0126] In the embodiment of the present invention, the original image quality evaluation factor can be specifically expressed as the above mathematical relationship with one term, wherein the term It is used to represent the sum of the differences between multiple original performance parameters and the expected performance parameters; for example, the four performance parameters of effective focal length, F number, image height and diffuse spot size can be selected; the effective focal length, F number, image height and diffuse spot size of the optical system to be designed correspond to T in the above items m , that is, the expected performance parameters; and the above performance parameters of the optical system composed of the metasurface corresponding to the original structural parameters correspond to V in the above terms m , that is, the original performance parameters.

[0127] Optionally, the phase of the metasurface corresponding to the current structural parameters at multiple positions satisfies one of the following formulas:

[0128]

[0129]

[0130]

[0131]

[0132]

[0133]

[0134] Among them, r represents the distance from the position to the center; (x, y) represents the coordinates of the position; f represents the focal length; a i , b i 、a ij and b ij They all represent the phase coefficients of each order.

[0135] In the embodiment of the present invention, any one of the above six formulas can be selected to calculate the phase of the metasurface at multiple positions corresponding to the current structural parameters. The above six formulas can be used to calculate the phase of the metasurface at multiple positions (at the radius value r) corresponding to the current structural parameters. Usually, if optical design software (such as Zemax) is used for simulation, the system will select formula The phase of the hypersurface corresponding to the current structural parameters at multiple positions (at the radius value r) is calculated, and the embodiment of the present invention does not impose any limitation on which calculation formula is selected.

[0136] The following is a detailed introduction to the process of the metasurface phase coefficient optimization method through an embodiment. Among them, the working band of the optical system with the metasurface is the near-infrared band, the central wavelength is 940nm, the maximum half field of view angle is 39°, the effective focal length is 2.46mm, the Fno (the inverse of the relative aperture) is 1.3, and the TTL (total length of the system) is 3.8mm. Taking the second surface as the metasurface to be optimized as an example, its phase distribution satisfies the formula:

[0137] Where r represents the distance from the nanostructure to the center of the metasurface; Indicates the constant phase of light with a working wavelength of λ; a i Represents the phase coefficient of each order, i = 1, 2, 3...n.

[0138] Specifically, the method includes the following steps 401-412. The flowchart of the method can be found in Figure 4 shown.

[0139] Step 401: Randomly generate original structural parameters.

[0140] Step 402: Determine the original performance parameters of the metasurface corresponding to the original structural parameters.

[0141] Step 403: Determine the original image quality assessment factor.

[0142] The original image quality evaluation factor may be determined based on the above step B2, which will not be described in detail here.

[0143] Step 404: determine whether the original image quality evaluation factor is less than or equal to the second limit value, if so, execute step 405; if not, execute step 406;

[0144] The second limit value is the same as the first limit value.

[0145] Step 405: Use the original structural parameters as the initial structural parameters, use the initial structural parameters as the initial values ​​of the current structural parameters, and continue to execute step 407.

[0146] Step 406: Update the original structural parameters based on the gradient descent method and repeat step 402.

[0147] Step 407: Determine the equivalent refractive index difference corresponding to the current structural parameters.

[0148] Step 408: Determine whether the equivalent refractive index difference corresponding to the current structural parameters is less than a reasonable constant. If so, execute step 409; if not, execute step 410.

[0149] Step 409: Determine the current structural parameter as the target structural parameter.

[0150] Among them, the target structural parameters meet the process requirements and conform to the imaging needs.

[0151] Step 410: Determine whether the equivalent refractive index difference corresponding to the current structural parameters is greater than a reasonable constant. If so, execute step 411; if not, execute step 412.

[0152] Step 411: Update the return value K=k1, update the current image quality evaluation function, update the current structural parameters based on the gradient descent method, and execute step 413.

[0153] Step 412: Update the return value K=k0, update the current image quality evaluation function, update the current structural parameters based on the gradient descent method, and execute step 413.

[0154] Among them, k1 is greater than k0.

[0155] Step 413: Based on the current image quality evaluation function, determine the current image quality evaluation factor, and judge whether the current image quality evaluation factor is less than or equal to the first limit value. If so, execute the above step 407; if not, execute step 414.

[0156] Step 414: Update the current structural parameters based on the gradient descent method and execute the above step 413.

[0157] Among them, see Figure 2 , Figure 3 , Figure 5 , Figure 6 and Figure 7 As shown, Figure 5 A schematic diagram of simulation results obtained based on this method is shown; Figure 2 and Figure 6 A schematic diagram of the phase distribution of the metasurface corresponding to the unconstrained phase coefficient and a diagram of the optical modulation transfer function generated by the metasurface corresponding to the unconstrained phase coefficient are shown respectively; Figure 3 and Figure 7 Schematic diagrams of the phase distribution of the metasurface corresponding to the constrained phase coefficient and the generated optical modulation transfer function diagram of the metasurface corresponding to the constrained phase coefficient are respectively shown; Based on the above figures, it can be seen that the metasurface phase coefficient optimization method provided by the embodiment of the present invention can be used to Figure 4 The simulation results of the optical system shown are optimized so that the optimized target structure parameters meet the process requirements and achieve the imaging needs.

[0158] The above describes in detail the metasurface phase coefficient optimization method provided by an embodiment of the present invention. The method can also be implemented by a corresponding device. The following describes in detail the metasurface phase coefficient optimization device provided by an embodiment of the present invention.

[0159] Figure 8 FIG. 2 shows a schematic diagram of the structure of a metasurface phase coefficient optimization device provided by an embodiment of the present invention. Figure 8 As shown, the metasurface phase coefficient optimization device includes: a determination module 81 and an optimization module 82.

[0160] The determination module 81 is used to determine initial structural parameters, where the structural parameters are used to define the structural features of the metasurface, and the structural parameters at least include: phase coefficients of each order.

[0161] The optimization module 82 is used to use the initial structural parameters as the initial values ​​of the current structural parameters, optimize the current structural parameters in a manner of optimizing the equivalent refractive index difference corresponding to the current structural parameters, and determine the optimized target structural parameters; the equivalent refractive index difference is the difference between the maximum and minimum values ​​of the equivalent refractive index in the metasurface corresponding to the corresponding structural parameters, and the equivalent refractive index difference corresponding to the target structural parameters is less than a reasonable constant that meets the process requirements.

[0162] Optionally, the optimization module 82 includes: a circulation unit.

[0163] The circulation unit is used to cyclically perform parameter optimization operations on the current structural parameters until the equivalent refractive index difference corresponding to the optimized current structural parameters is less than the reasonable constant;

[0164] The circulation unit includes: an equivalent refractive index difference determination unit and an equivalent refractive index difference judgment unit.

[0165] The equivalent refractive index difference determination unit is used to determine the equivalent refractive index difference corresponding to the current structural parameters.

[0166] The equivalent refractive index difference judgment unit is used to judge whether the equivalent refractive index difference corresponding to the current structural parameters is less than the reasonable constant; if the current structural parameters meet the requirements, the current structural parameters are used as the target structural parameters; if the current structural parameters do not meet the requirements, the current structural parameters are updated; wherein, the current structural parameters meet the requirements including that the equivalent refractive index difference corresponding to the current structural parameters is less than the reasonable constant.

[0167] Optionally, the circulation unit further includes: a current image quality assessment factor determination unit and a current image quality assessment factor judgment unit.

[0168] The current image quality assessment factor determination unit is used to determine the current performance parameters of the metasurface corresponding to the current structural parameters, and to determine the current image quality assessment factor; the current image quality assessment factor includes the difference between the current performance parameters and the expected performance parameters and the difference between the equivalent refractive index difference corresponding to the current structural parameters and the reasonable constant.

[0169] The current image quality assessment factor judgment unit is used to judge whether the current image quality assessment factor is greater than a first limit value; wherein, the current structural parameters satisfying the requirements also include: the current image quality assessment factor is less than or equal to the first limit value; the current structural parameters not satisfying the requirements include: the equivalent refractive index difference corresponding to the current structural parameters is not less than the reasonable constant, and / or the current image quality assessment factor is greater than the first limit value.

[0170] Optionally, the current image quality assessment factor determination unit includes: a weighted processing unit.

[0171] The weighted processing unit is used to determine the current image quality evaluation factor based on the current image quality evaluation function, and the current image quality evaluation function includes weighted processing of a first item and a second item, the first item is used to represent the difference between the current performance parameter and the expected performance parameter, and the second item is used to represent the difference between the equivalent refractive index difference corresponding to the current structural parameter and the reasonable constant.

[0172] Optionally, in the weighted processing unit, the current image quality evaluation function satisfies:

[0173]

[0174] Wherein, M represents the current image quality evaluation factor; V i represents the current performance parameter of the ith type; T i represents the i-th desired performance parameter; w irepresents the weight corresponding to the difference between the i-th current performance parameter and the expected performance parameter; F x represents the equivalent refractive index difference corresponding to the current structural parameters; C represents the reasonable constant; p represents the weight corresponding to the difference between the equivalent refractive index difference corresponding to the current structural parameters and the reasonable constant.

[0175] Optionally, in the weighted processing unit, the current image quality evaluation function further includes a third item, and the third item is used to represent a return value that can be adjusted.

[0176] The cycle unit also includes: an update unit.

[0177] The updating unit is used to update the current image quality evaluation function by updating the return value after the current image quality evaluation factor is determined.

[0178] Wherein, the updating unit includes: a return value determination subunit.

[0179] The return value determination subunit is used to update the return value to a first value when the equivalent refractive index difference is greater than the reasonable constant; and to update the return value to a second value when the equivalent refractive index difference is equal to the reasonable constant; the first value is greater than the second value.

[0180] Optionally, the update unit includes: an update subunit.

[0181] The updating subunit is used for updating the current image quality evaluation function by updating the return value when the current image quality evaluation factor is less than or equal to the first limit value.

[0182] Optionally, the weight corresponding to the difference between the equivalent refractive index difference corresponding to the current structural parameter and the reasonable constant is smaller than the weight corresponding to the return value.

[0183] Optionally, the current image quality evaluation function satisfies:

[0184]

[0185] Wherein, M represents the current image quality evaluation factor; V i represents the current performance parameter of the ith type; T i represents the i-th desired performance parameter; w i represents the weight corresponding to the difference between the i-th current performance parameter and the expected performance parameter; F xrepresents the equivalent refractive index difference corresponding to the current structural parameters; C represents the reasonable constant; p represents the weight corresponding to the difference between the equivalent refractive index difference corresponding to the current structural parameters and the reasonable constant; K represents the return value; q represents the weight corresponding to the return value.

[0186] Optionally, the performance parameters include: at least one of effective focal length, F number, image height, diffuse spot size, field of view angle, relative aperture and total system length.

[0187] Optionally, the equivalent refractive index difference determining unit includes: a phase determining subunit and an equivalent refractive index difference determining subunit.

[0188] The phase determination subunit is used to determine the phase of the metasurface corresponding to the current structural parameters at multiple positions, and determine the equivalent refractive index at the corresponding position according to the phase, and there is a positive correlation between the equivalent refractive index and the phase.

[0189] The equivalent refractive index difference determination subunit is used to determine the maximum value and the minimum value among the multiple equivalent refractive indices, and take the difference between the maximum value and the minimum value as the equivalent refractive index difference corresponding to the current structural parameter.

[0190] Optionally, the equivalent refractive index difference determination unit further includes: a radius value determination subunit.

[0191] The radius value determination subunit is used to determine the maximum radius of the hypersurface corresponding to the current structural parameters, with a as the step size and multiple radius values ​​selected from zero to the maximum radius, and different radius values ​​represent different positions.

[0192] Optionally, the relationship between the equivalent refractive index and the phase satisfies:

[0193]

[0194] Wherein, F represents the equivalent refractive index; represents the phase at position r; k represents the wave number, and λ represents the wavelength; Hd represents the height of the nanostructure at position r.

[0195] Optionally, the determination module 81 includes: an original structural parameter determination unit, an original image quality assessment factor determination unit and an original image quality assessment factor judgment unit.

[0196] The original structure parameter determination unit is used to determine the original structure parameters.

[0197] The original image quality evaluation factor determination unit is used to determine the original performance parameters of the metasurface corresponding to the original structural parameters, and determine the original image quality evaluation factor; the original image quality evaluation factor includes the difference between the original performance parameters and the expected performance parameters.

[0198] The original image quality evaluation factor judgment unit is used to use the original structure parameter as the initial structure parameter when the original image quality evaluation factor is less than or equal to the second limit value.

[0199] Optionally, the original image quality evaluation factor satisfies:

[0200]

[0201] Wherein, N represents the original image quality evaluation factor; V m represents the mth original performance parameter; T m represents the mth desired performance parameter; w m Represents the weight corresponding to the difference between the mth original performance parameter and the expected performance parameter.

[0202] Optionally, the phase of the metasurface corresponding to the current structural parameters at multiple positions satisfies one of the following formulas:

[0203]

[0204]

[0205]

[0206]

[0207]

[0208]

[0209] Wherein, r represents the distance from the position to the center; (x, y) represents the coordinates of the position; f represents the focal length; a i , b i 、a ij and b ij They all represent the phase coefficients of the various orders.

[0210] Optionally, the structural parameters further include: the maximum radius and the height of the nanostructure.

[0211] The device provided by the embodiment of the present invention can obtain the target structural parameters that meet the process requirements (less than a reasonable constant) after optimization by optimizing the equivalent refractive index difference of the current structural parameters. The target structural parameters can make the nanostructure on its corresponding metasurface satisfy the periodic arrangement. The embodiment of the present invention innovatively optimizes the structural parameters of the metasurface in the optical system (such as the phase coefficients of each order), thereby reducing the difficulty of the manufacturing process of the optical system at the beginning of the design to achieve mass production.

[0212] In addition, an embodiment of the present invention further 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 respectively connected via a bus. When the computer program is executed by the processor, each process of the above-mentioned metasurface phase coefficient optimization method embodiment is implemented, and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

[0213] For details, see Fig. 9 As shown, an embodiment of the present invention further 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 .

[0214] In an embodiment of the present invention, the electronic device also includes: a computer program stored in the memory 1150 and executable on the processor 1120, and when the computer program is executed by the processor 1120, each process of the above-mentioned metasurface phase coefficient optimization method embodiment is implemented.

[0215] The transceiver 1130 is configured to receive and send data under the control of the processor 1120 .

[0216] In an embodiment of the present invention, the bus architecture (represented by bus 1110), 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 a memory represented by memory 1150.

[0217] Bus 1110 represents one or more of any of several types of bus structures, including a memory bus and memory controller, a peripheral bus, an Accelerate Graphical Port (AGP), a processor, or a local bus using any of a variety of bus architectures. By way of example and not limitation, such architectures include: Industry Standard Architecture (ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, Video Electronics Standards Association (VESA), Peripheral Component Interconnect (PCI) bus.

[0218] The processor 1120 may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method embodiment may be completed by an integrated logic circuit of hardware in the processor or an instruction in the form of software. The above processors include: a general-purpose processor, a central processing unit (CPU), a network processor (NP), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), a complex programmable logic device (CPLD), a programmable logic array (PLA), a microcontroller unit (MCU) or other programmable logic devices, discrete gates, transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present invention may be implemented or executed. For example, the processor may be a single-core processor or a multi-core processor, and the processor may be integrated into a single chip or located in multiple different chips.

[0219] Processor 1120 can be a microprocessor or any conventional processor. The method steps disclosed in conjunction with the embodiments of the present invention can be directly executed by a hardware decoding processor, or by a combination of hardware and software modules in the decoding processor. The software module can be located in a readable storage medium known in the art, such as a random access memory (RAM), a flash memory (FlashMemory), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), a register, etc. The readable storage medium is located in a memory, and the processor reads the information in the memory and completes the steps of the above method in conjunction with its hardware.

[0220] The bus 1110 may also connect various other circuits such as peripheral devices, voltage regulators or power management circuits, and the bus interface 1140 provides an interface between the bus 1110 and the transceiver 1130, which are well known in the art. Therefore, the embodiments of the present invention will not be further described.

[0221] The transceiver 1130 may be one element or multiple elements, such as multiple receivers and transmitters, and provides a unit for communicating with various other devices on a transmission medium. For example, the transceiver 1130 receives external data from other devices, and the transceiver 1130 is used to send data processed by the processor 1120 to other devices. Depending on the nature of the computer system, a user interface 1160 may also be provided, such as a touch screen, a physical keyboard, a display, a mouse, a speaker, a microphone, a trackball, a joystick, and a stylus.

[0222] It should be understood that in an embodiment of the present invention, the memory 1150 may further include a memory remotely arranged relative to the processor 1120, and these remotely arranged memories may be connected to the server through a network. One or more parts of the above-mentioned network may be an ad hoc network, an intranet, an extranet, a virtual private network (VPN), a local area network (LAN), a wireless local area network (WLAN), a wide area network (WAN), a wireless wide area network (WWAN), a metropolitan area network (MAN), the Internet, a public switched telephone network (PSTN), a plain old telephone service network (POTS), a cellular telephone network, a wireless network, a wireless fidelity (Wi-Fi) network, and a combination of two or more of the above-mentioned networks. For example, the cellular telephone network and the wireless network can be a Global System for Mobile Communications (GSM) system, a Code Division Multiple Access (CDMA) system, a Worldwide Interoperability for Microwave Access (WiMAX) system, a General Packet Radio Service (GPRS) system, a Wideband Code Division Multiple Access (WCDMA) system, a Long Term Evolution (LTE) system, a LTE Frequency Division Duplex (FDD) system, a LTE Time Division Duplex (TDD) system, an Advanced Long Term Evolution (LTE-A) system, a Universal Mobile Telecommunications (UMTS) system, an Enhanced Mobile Broadband (Enhance Mobile Broadband, eMBB) system, a massive Machine Type of Communication (mMTC) system, an Ultra-Reliable Low Latency Communications (UltraReliable Low Latency Communications, uRLLC) system, etc.

[0223] It should be understood that the memory 1150 in the embodiment of the present invention may be a volatile memory or a non-volatile memory, or may include both a volatile memory and a non-volatile memory. Among them, the non-volatile memory includes: a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory.

[0224] Volatile memory includes: Random Access Memory (RAM), which is used as an external cache. By way of example but not limitation, many forms of RAM are available, such as: Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate Synchronous Dynamic Random Access Memory (DDRSDRAM), Enhanced Synchronous Dynamic Random Access Memory (ESDRAM), Synchronous Link Dynamic Random Access Memory (SLDRAM) and Direct Rambus RAM (DRRAM). The memory 1150 of the electronic device described in the embodiment of the present invention includes but is not limited to the above and any other suitable types of memory.

[0225] In the embodiment of the present invention, the memory 1150 stores the following elements of the operating system 1151 and the application program 1152: executable modules, data structures, or subsets thereof, or extended sets thereof.

[0226] Specifically, the operating system 1151 includes various system programs, such as a framework layer, a core library layer, a driver layer, etc., which are used to implement various basic services and process hardware-based tasks. The application 1152 includes various applications, such as a media player (Media Player) and a browser (Browser), which are used to implement various application services. The program for implementing the method of the embodiment of the present invention may be included in the application 1152. The application 1152 includes applets, objects, components, logic, data structures, and other computer system executable instructions that perform specific tasks or implement specific abstract data types.

[0227] In addition, an embodiment of the present invention further provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the various processes of the above-mentioned metasurface phase coefficient optimization method embodiment are implemented and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

[0228] Computer readable storage media include: permanent and non-permanent, removable and non-removable media, which are tangible devices that can retain and store instructions for use by instruction execution devices. Computer readable storage media include: electronic storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, and any suitable combination of the above. 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 technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassette storage, magnetic tape disk storage or other magnetic storage devices, memory sticks, mechanical encoding devices (such as punched cards or raised structures in grooves with instructions recorded thereon) or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined in the embodiments of the present invention, 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 (such as light pulses passing through fiber optic cables), or electrical signals transmitted through wires.

[0229] In the several embodiments provided in the present application, it should be understood that the disclosed devices, electronic devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, or it can be an electrical, mechanical or other form of connection.

[0230] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, and may be located in one location or distributed on multiple network units. Some or all of the units may be selected according to actual needs to solve the problem to be solved by the embodiments of the present invention.

[0231] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0232] If the integrated unit is implemented in the form of 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 solution of the embodiment of the present invention is essentially or part of the contribution to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (including: a personal computer, a server, a data center or other network device) to perform all or part of the steps of the method described in each embodiment of the present invention. The above-mentioned storage medium includes various media that can store program codes as listed above.

[0233] In the description of the embodiments of the present invention, those skilled in the art should know that the embodiments of the present invention can be implemented as methods, devices, electronic devices and computer-readable storage media. Therefore, the embodiments of the present invention can be specifically implemented in the following forms: complete hardware, complete software (including firmware, resident software, microcode, etc.), a combination of hardware and software. In addition, in some embodiments, the embodiments of the present invention can also be implemented in the form of a computer program product in one or more computer-readable storage media, and the computer-readable storage medium contains computer program code.

[0234] The above-mentioned computer-readable storage medium may adopt any combination of one or more computer-readable storage media. Computer-readable storage media include: electrical, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or devices, or any combination of the above. More specific examples of computer-readable storage media include: portable computer disks, hard disks, random access memories (RAM), read-only memories (ROM), erasable programmable read-only memories (EPROM), flash memories, optical fibers, compact disk read-only memories (CD-ROM), optical storage devices, magnetic storage devices or any combination of the above. In an embodiment of the present invention, a computer-readable storage medium may be any tangible medium containing or storing a program, which may be used by or in combination with an instruction execution system, device, or device.

[0235] The computer program code contained in the above-mentioned computer-readable storage medium can be transmitted using any appropriate medium, including: wireless, wire, optical cable, radio frequency (RF) or any suitable combination thereof.

[0236] The computer program code for performing the operation of the embodiments of the present invention can be written in assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data, integrated circuit configuration data, or in one or more programming languages ​​or a combination thereof, wherein the programming language includes an object-oriented programming language, such as Java, Smalltalk, C++, and also includes a conventional procedural programming language, such as C language or a similar programming language. The computer program code can be executed completely on the user's computer, partially on the user's computer, as an independent software package, partially on the user's computer, partially on a remote computer, and completely on a remote computer or server. In the case of a remote computer, the remote computer can be connected to the user's computer or to an external computer through any type of network, including a local area network (LAN) or a wide area network (WAN).

[0237] The embodiments of the present invention describe the provided methods, devices, and electronic devices through flowcharts and / or block diagrams.

[0238] It should be understood that each box in the flowchart and / or block diagram and the combination of boxes in the 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 device to produce a machine, and these computer-readable program instructions are executed by a computer or other programmable data processing device to produce a device that implements the functions / operations specified by the boxes in the flowchart and / or block diagram.

[0239] 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 work in a specific manner. In this way, the instructions stored in the computer-readable storage medium produce an instruction device product including functions / operations specified in the blocks in the flowchart and / or block diagram.

[0240] Computer-readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device, so that a series of operational steps are performed on the computer, other programmable data processing apparatus, or other device to produce a computer-implemented process, thereby enabling the instructions executed on the computer or other programmable data processing apparatus to provide a process for implementing the functions / operations specified in the blocks in the flowchart and / or block diagram.

[0241] The above is only a specific implementation of the embodiment of the present invention, but the protection scope of the embodiment of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the embodiment of the present invention, which should be included in the protection scope of the embodiment of the present invention. Therefore, the protection scope of the embodiment of the present invention should be based on the protection scope of the claims.

Claims

1. A metasurface phase coefficient optimization method, characterized in that: include: Determining initial structural parameters, where the structural parameters are used to define structural features of the metasurface, and the structural parameters at least include: phase coefficients of each order; Taking the initial structural parameters as the initial values ​​of the current structural parameters, optimizing the current structural parameters in a manner of optimizing the equivalent refractive index difference corresponding to the current structural parameters, and determining the optimized target structural parameters; the equivalent refractive index difference is the difference between the maximum value and the minimum value of the equivalent refractive index in the metasurface corresponding to the corresponding structural parameters, and the equivalent refractive index difference corresponding to the target structural parameters is less than a reasonable constant that meets the process requirements; The optimizing the current structural parameters in a manner of optimizing the equivalent refractive index difference corresponding to the current structural parameters comprises: The parameter optimization operation is cyclically performed on the current structural parameters until the equivalent refractive index difference corresponding to the optimized current structural parameters is less than the reasonable constant.

2. The method according to claim 1, characterized in that The parameter optimization operation includes: Determine the equivalent refractive index difference corresponding to the current structural parameters; Determine whether the equivalent refractive index difference corresponding to the current structural parameter is less than the reasonable constant; When the current structural parameters meet the requirements, the current structural parameters are used as the target structural parameters; when the current structural parameters do not meet the requirements, the current structural parameters are updated; wherein, the current structural parameters meet the requirements including that the equivalent refractive index difference corresponding to the current structural parameters is less than the reasonable constant.

3. The method according to claim 2, characterized in that The parameter optimization operation further includes: Determine the current performance parameters of the metasurface corresponding to the current structural parameters, and determine the current image quality evaluation factor; the current image quality evaluation factor includes the difference between the current performance parameters and the expected performance parameters and the difference between the equivalent refractive index difference corresponding to the current structural parameters and the reasonable constant; Determining whether the current image quality assessment factor is greater than a first limit value; Among them, the current structural parameters satisfying the requirements also include: the current image quality evaluation factor is less than or equal to the first limit value; the current structural parameters not satisfying the requirements include: the equivalent refractive index difference corresponding to the current structural parameters is not less than the reasonable constant, and / or the current image quality evaluation factor is greater than the first limit value.

4. The method according to claim 3, characterized in that: The determining of the current image quality assessment factor comprises: The current image quality evaluation factor is determined based on a current image quality evaluation function, wherein the current image quality evaluation function includes weighted processing of a first item and a second item, wherein the first item is used to represent the difference between the current performance parameter and the expected performance parameter, and the second item is used to represent the difference between the equivalent refractive index difference corresponding to the current structural parameter and the reasonable constant.

5. The method according to claim 4, characterized in that The current image quality evaluation function satisfies: Wherein, M represents the current image quality evaluation factor; V i represents the current performance parameter of the ith type; T i represents the i-th desired performance parameter; w i represents the weight corresponding to the difference between the i-th current performance parameter and the expected performance parameter; F x represents the equivalent refractive index difference corresponding to the current structural parameters; C represents the reasonable constant; q represents the weight corresponding to the difference between the equivalent refractive index difference corresponding to the current structural parameters and the reasonable constant.

6. The method according to claim 4, characterized in that The current image quality evaluation function further includes a third item, and the third item is used to represent a return value that can be adjusted; The parameter optimization operation further includes: After the current image quality assessment factor is determined, updating the current image quality assessment function in a manner of updating the return value; Wherein, updating the return value includes: When the equivalent refractive index difference is greater than the reasonable constant, the return value is updated to a first value; when the equivalent refractive index difference is equal to the reasonable constant, the return value is updated to a second value; the first value is greater than the second value.

7. The method according to claim 6, characterized in that The updating of the current image quality evaluation function by updating the return value includes: When the current image quality evaluation factor is less than or equal to the first limit value, the current image quality evaluation function is updated in a manner of updating the return value.

8. The method according to claim 6, characterized in that The weight corresponding to the difference between the equivalent refractive index difference corresponding to the current structural parameter and the reasonable constant is smaller than the weight corresponding to the returned value.

9. The method according to claim 8, characterized in that The current image quality evaluation function satisfies: Wherein, M represents the current image quality evaluation factor; V i represents the current performance parameter of the ith type; T i represents the i-th desired performance parameter; w i represents the weight corresponding to the difference between the i-th current performance parameter and the expected performance parameter; F x represents the equivalent refractive index difference corresponding to the current structural parameters; C represents the reasonable constant; q represents the weight corresponding to the difference between the equivalent refractive index difference corresponding to the current structural parameters and the reasonable constant; K represents the return value; q represents the weight corresponding to the return value.

10. The method according to claim 3, characterized in that: The performance parameters include at least one of effective focal length, F number, image height, diffuse spot size, field of view angle, relative aperture and total system length.

11. The method according to claim 2, characterized in that The determining the equivalent refractive index difference corresponding to the current structural parameter includes: Determine the phase of the metasurface corresponding to the current structural parameters at multiple positions, and determine the equivalent refractive index at the corresponding position according to the phase, wherein the equivalent refractive index is positively correlated with the phase; The maximum value and the minimum value among the multiple equivalent refractive indices are determined, and the difference between the maximum value and the minimum value is used as the equivalent refractive index difference corresponding to the current structural parameter.

12. The method according to claim 11, characterized in that The determining of the equivalent refractive index difference corresponding to the current structural parameter also includes: The maximum radius of the hypersurface corresponding to the current structural parameters is determined, and a plurality of radius values ​​are selected from zero to the maximum radius with a as the step size, and different radius values ​​represent different positions.

13. The method according to claim 11, characterized in that The relationship between the equivalent refractive index and the phase satisfies: Wherein, F represents the equivalent refractive index; represents the phase at position r; k represents the wave number, and λ represents the wavelength; Hd represents the height of the nanostructure at position r.

14. The method according to claim 1, characterized in that The step of determining the initial structural parameters comprises: Determine the original structural parameters; Determining original performance parameters of the metasurface corresponding to the original structural parameters, and determining an original image quality evaluation factor; the original image quality evaluation factor includes the difference between the original performance parameters and the expected performance parameters; When the original image quality evaluation factor is less than or equal to the second limit value, the original structural parameter is used as the initial structural parameter.

15. The method according to claim 14, characterized in that The original image quality evaluation factor satisfies: Wherein, N represents the original image quality evaluation factor; V m represents the mth original performance parameter; T m represents the mth desired performance parameter; w m Represents the weight corresponding to the difference between the mth original performance parameter and the expected performance parameter.

16. The method according to claim 13, characterized in that The phase of the metasurface corresponding to the current structural parameters at multiple positions satisfies one of the following formulas: Wherein, r represents the distance from the position to the center; (x, y) represents the coordinates of the position; f represents the focal length; a i 、b i 、a ij and b ij All represent the phase coefficients of the respective orders; N represents the maximum order of the phase coefficient; Represents the phase of the metasurface at the position indicated by the (x,y) coordinate.

17. The method according to claim 13, characterized in that The structural parameters also include: the maximum radius and the height of the nanostructure.

18. A metasurface phase coefficient optimization device, characterized in that: include: Determine modules and optimize modules; The determination module is used to determine initial structural parameters, and the structural parameters are used to define the structural characteristics of the metasurface, and the structural parameters at least include: phase coefficients of each order; The optimization module is used to use the initial structural parameters as the initial values ​​of the current structural parameters, optimize the current structural parameters in a manner of optimizing the equivalent refractive index difference corresponding to the current structural parameters, and determine the optimized target structural parameters; the equivalent refractive index difference is the difference between the maximum and minimum values ​​of the equivalent refractive index in the metasurface corresponding to the corresponding structural parameters, and the equivalent refractive index difference corresponding to the target structural parameters is less than a reasonable constant that meets the process requirements.

19. 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, wherein: When the computer program is executed by the processor, the steps in the metasurface phase coefficient optimization method according to any one of claims 1 to 17 are implemented.

20. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps in the metasurface phase coefficient optimization method according to any one of claims 1 to 17 are implemented.

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