Diffractive optical elements and their design methods and systems, light projection devices, equipment, and storage media

Abstract

This application provides a diffractive optical element and its design method and system, light projection device, equipment, and storage medium. The design method includes: acquiring a target light field on an output surface of the emitted light from the diffractive optical element, wherein the output surface and the diffractive optical element are spaced apart by a predetermined distance; designing and acquiring a first target phase distribution of the diffractive optical element based on the target light field using scalar diffraction theory; and optimizing the first target phase distribution based on vector diffraction theory to obtain a second target phase distribution, wherein the second target phase distribution is used to characterize the distribution of multiple first microstructures on the diffractive optical element. The design method of this application can achieve uniformity in the output light field of the DOE (Optical Distributor).

Description

Technical Field

[0001] This application relates generally to the field of diffractive optics technology, and more specifically to a diffractive optical element and its design method and system, light projection device, equipment, and storage medium. Background Technology

[0002] A diffractive optical element (DOE) is an optical element designed based on the principles of diffraction optics. Typically, for incident laser light of a specific wavelength, a surface micro / nano structure is designed to modulate the energy and phase of the laser to achieve the desired output diffraction pattern. A beam-splitting lattice is a type of DOE whose function is to split an incident laser beam into multiple uniform output laser beams through diffraction based on a target diffraction pattern (regular or irregular lattice). Beam-splitting lattices play important roles in many fields, such as autonomous driving, security monitoring, and facial recognition. These fields have high requirements for the uniformity of DOE beam splitting. Uniformity reflects the consistency of energy (or intensity) between laser points after beam splitting by the DOE; the lower its absolute value, the better.

[0003] Currently, the commonly used design method for split-beam DOEs is usually based on scalar diffraction theory. Scalar diffraction theory is an approximate analysis method, that is, it only considers one transverse complex amplitude of the electromagnetic field component and assumes that any other related components can be treated in the same way. DOE analysis and design based on scalar diffraction theory must meet the following conditions: (1) the characteristic size of the diffraction element is much larger than the wavelength; (2) the observation point of the diffraction field is sufficiently far from the diffraction element. When the above conditions cannot be met, vector diffraction theory is required. Its characteristic is that it considers the polarization characteristics of light and the influence of the interaction between different polarized lights on the diffraction results. It requires rigorous solution of Maxwell's equations, thus the computational load is large. Because scalar diffraction theory is an approximate theory, its results differ greatly from actual results. The performance of the DOE finally obtained by designing solely based on scalar diffraction theory is often unsatisfactory. Summary of the Invention

[0004] This application is made to address at least one of the aforementioned problems. Specifically, a first aspect of this application provides a method for designing a diffractive optical element, the method comprising:

[0005] The target light field of the emitted light after exiting from the diffractive optical element is obtained on the output surface, wherein the output surface and the diffractive optical element are spaced apart by a predetermined distance;

[0006] Based on the target light field, the first target phase distribution of the diffractive optical element is designed and obtained using scalar diffraction theory.

[0007] The first target phase distribution is optimized based on vector diffraction theory to obtain a second target phase distribution, wherein the second target phase distribution is used to characterize the distribution of multiple first microstructures on the diffractive optical element.

[0008] Optionally, the step of designing and obtaining the first phase distribution of the diffractive optical element based on the target light field using scalar diffraction theory includes:

[0009] Step S11: Obtain the first input wave function of the input surface of the diffractive optical element, wherein the first input wave function in the first iteration is determined based on the first estimated phase distribution and the preset input light amplitude distribution, and the first estimated phase distribution is a random phase distribution;

[0010] Step S12: Perform forward diffraction operation on the first input wave function to obtain the first output wave function of the output surface, wherein the first output wave function includes the output light amplitude distribution and the output surface phase distribution;

[0011] Step S13: Modulate the output light amplitude distribution and update the first output wave function based on the modulated output light amplitude distribution to obtain the updated first output wave function;

[0012] Step S14: Perform inverse diffraction operation on the updated first output wavefunction to obtain the second estimated phase distribution and the second input light amplitude distribution on the input surface;

[0013] Step S15: Modulate the second input light amplitude distribution, and obtain the first input wave function for the next iteration based on the modulated second input light amplitude distribution and the second estimated phase distribution;

[0014] Step S16: Repeat steps S11 to S15 until the first iteration loop termination condition is met, and output the second estimated phase distribution obtained in the last iteration as the first target phase distribution.

[0015] Optionally, the termination condition of the first iteration loop includes at least one of the following conditions:

[0016] The preset number of iterations has been reached;

[0017] The uniformity of the output light amplitude distribution is less than or equal to the first preset uniformity.

[0018] Optionally, optimizing the phase distribution of the first target based on vector diffraction theory to obtain the phase distribution of the second target includes:

[0019] Step S21: Obtain a first phase distribution and adjust the first phase distribution to obtain an adjusted phase distribution, wherein the first phase distribution at the first iteration is the first target phase distribution;

[0020] Step S22: Using the vector diffraction theory, the output light field at the output surface of the input light after passing through the diffraction optical element with the adjusted phase distribution is simulated to obtain the first simulated light field;

[0021] Step S23: Determine whether the first simulated light field meets the first light field evaluation condition. If it meets the first light field evaluation condition, it indicates that the adjusted phase distribution is better than the first phase distribution. If it does not meet the first light field evaluation condition, it indicates that the adjusted phase distribution is worse than the first phase distribution. Then return to step S21.

[0022] Step S24: Repeat steps S21 to S23 until the second iteration loop termination condition is met, and output the adjusted phase distribution corresponding to the first simulated light field that last meets the first light field evaluation condition as the second target phase distribution.

[0023] Optionally, if the adjusted phase distribution obtained in the previous iteration is better than the first phase distribution before the iteration ends, the adjusted phase distribution obtained in the previous iteration shall be used as the first phase distribution for the next iteration.

[0024] Optionally, the first light field evaluation condition includes: the uniformity of the first simulated light field is less than or equal to the second preset uniformity.

[0025] Optionally, the design method further includes:

[0026] At least one second microstructure is added to the second target phase distribution to obtain a third target phase distribution, wherein the second microstructure is used to modulate the high-frequency components of the light wave.

[0027] Optionally, adding at least one second microstructure to the second target phase distribution to obtain the third target phase distribution includes:

[0028] Step S31: Add at least one second microstructure to the second phase distribution to obtain a third phase distribution, wherein the second phase distribution during the first iteration is the second target phase distribution;

[0029] Step S32: Use the vector diffraction theory to simulate the output light field at the output surface after passing through the diffractive optical element with the third phase distribution, so as to obtain the second simulated light field;

[0030] Step S33: Determine whether the second simulated light field meets the second light field evaluation condition. If it meets the second light field evaluation condition, it indicates that the third phase distribution is better than the second phase distribution. If it does not meet the second light field evaluation condition, it indicates that the third phase distribution is worse than the second phase distribution. Return to step S31.

[0031] Step S34: Repeat steps S31 to S33 until the third iteration loop termination condition is met, and output the third phase distribution corresponding to the second simulated light field that last met the second light field evaluation condition as the third target phase distribution.

[0032] Optionally, if the third phase distribution obtained in the previous iteration is better than the second phase distribution before the iteration ends, then the third phase distribution obtained in the previous iteration is used as the second phase distribution in the next iteration.

[0033] Optionally, the second light field evaluation condition includes: the uniformity of the second simulated light field is less than or equal to a third preset uniformity.

[0034] Optionally, the length of the second microstructure on the surface of the diffractive optical element is less than or equal to 1 / 2 of the wavelength of the input light.

[0035] Optionally, at least one of the second microstructures is located outside the first microstructure and is not connected to any of the first microstructures; and / or

[0036] At least one of the second microstructures is located within the first microstructure; and / or

[0037] At least one of the second microstructures is located at the edge of the first microstructure and is connected to the first microstructure.

[0038] Optionally, when at least one of the second microstructures is located within the first microstructure, the second microstructure is presented as a groove.

[0039] Optionally, the number of the second microstructure is not less than 10 in each cycle of the first microstructure.

[0040] A second aspect of this application also provides a diffractive optical element, comprising:

[0041] The substrate and a plurality of microstructure units formed on the substrate, wherein the plurality of microstructure units include a plurality of first microstructures, the microstructure units being configured to split the emitted light emitted by the light source into multiple outgoing light beams, wherein the distribution of the plurality of first microstructures is designed and obtained by using scalar diffraction theory to design and obtain a first target phase distribution of the diffractive optical element, and by optimizing the first target phase distribution based on vector diffraction theory.

[0042] Optionally, the plurality of microstructure units further include at least one second microstructure, wherein the second microstructure is used to modulate the high-frequency component of the light wave.

[0043] Optionally, the length of the second microstructure on the substrate surface is less than or equal to 1 / 2 of the wavelength of the emitted light.

[0044] Optionally, at least one of the second microstructures is located outside the first microstructure and is not connected to any of the first microstructures; and / or

[0045] At least one of the second microstructures is located within the first microstructure; and / or

[0046] At least one of the second microstructures is located at the edge of the first microstructure and is connected to the first microstructure.

[0047] Optionally, when at least one of the second microstructures is located within the first microstructure, the second microstructure is presented as a groove.

[0048] Optionally, the number of the second microstructure is not less than 10 in each cycle of the first microstructure.

[0049] Optionally, the first microstructure includes a protrusion structure located on the surface of the substrate.

[0050] A third aspect of this application provides a light projection device, comprising:

[0051] A light source, used to emit light;

[0052] The aforementioned diffractive optical element is disposed in the optical path of the emitted light from the light source, and is used to receive the emitted light emitted by the light source, split the emitted light emitted by the light source into multiple outgoing light beams, and to modulate the high-frequency component of the light wave so as to project a light field onto the target surface.

[0053] A fourth aspect of this application provides an apparatus characterized by including the aforementioned light projection device.

[0054] A fifth aspect of this application provides a design system for a diffractive optical element, the design system comprising:

[0055] Memory is used to store executable program instructions;

[0056] One or more processors are configured to execute the program instructions stored in the memory, such that the processors perform the design method described above.

[0057] The sixth aspect of this application provides a computer storage medium having a computer program stored thereon, which, when executed by a processor, implements the aforementioned design method.

[0058] The design method of this application first obtains the first target phase distribution of the diffractive optical element through scalar design, and then optimizes the first target phase distribution using vector diffraction theory to obtain the second target phase distribution, thereby improving the uniformity of the output light field of the DOE. Attached Figure Description

[0059] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0060] Figure 1 A flowchart illustrating a design method for a diffractive optical element is shown.

[0061] Figure 2 A flowchart is shown showing a method for designing and obtaining the first phase distribution of a diffractive optical element based on the target light field using scalar diffraction theory.

[0062] Figure 3 A flowchart is shown showing a method for optimizing the phase distribution of the first target based on vector diffraction theory to obtain the phase distribution of the second target;

[0063] Figure 4 A schematic diagram of a second target phase distribution is shown;

[0064] Figure 5 A flowchart is shown for a method of adding at least one second microstructure to a second target phase distribution;

[0065] Figure 6 A schematic diagram showing the shape of the second microstructure is provided;

[0066] Figure 7 A schematic diagram of a third target phase distribution is shown;

[0067] Figure 8A A schematic diagram of a target light field with 61 beam splitting points is shown.

[0068] Figure 8B Showing the target Figure 8A A schematic diagram of the first target phase distribution after scalar optimization of the target light field;

[0069] Figure 8C It shows Figure 8B A schematic diagram of the DOE output optical field corresponding to the phase distribution of the first target in the diagram;

[0070] Figure 8D It shows Figure 8C A schematic diagram showing the energy percentage at each point in the output light field;

[0071] Figure 8E Showing the target Figure 8B A schematic diagram of the optimized phase distribution vector of the second target after the first target phase distribution vector is used.

[0072] Figure 8F It shows Figure 8E A schematic diagram of the DOE output optical field corresponding to the phase distribution of the second target in the diagram;

[0073] Figure 8G It shows Figure 8H A schematic diagram showing the energy percentage at each point in the output light field;

[0074] Figure 8H Showing the target Figure 8E A schematic diagram of the phase distribution of the third target after adding the second microstructure to the phase distribution of the second target;

[0075] Figure 8I It shows Figure 8H A schematic diagram of the DOE output optical field corresponding to the phase distribution of the third target in the diagram;

[0076] Figure 8J It shows Figure 8I A schematic diagram showing the energy percentage at each point in the output light field;

[0077] Figure 9A A schematic diagram of a target light field with 89 beam splitting points is shown.

[0078] Figure 9B Showing the target Figure 9A A schematic diagram of the first target phase distribution after scalar optimization of the target light field;

[0079] Figure 9C It shows Figure 9B A schematic diagram of the DOE output optical field corresponding to the phase distribution of the first target in the diagram;

[0080] Figure 9D It shows Figure 9C A schematic diagram showing the energy percentage at each point in the output light field;

[0081] Figure 9E Showing the target Figure 9B A schematic diagram of the optimized phase distribution vector of the second target after the first target phase distribution vector is used.

[0082] Figure 9F It shows Figure 9E A schematic diagram of the DOE output optical field corresponding to the phase distribution of the second target in the diagram;

[0083] Figure 9G It shows Figure 9H A schematic diagram showing the energy percentage at each point in the output light field;

[0084] Figure 9H Showing the target Figure 9E A schematic diagram of the phase distribution of the third target after adding the second microstructure to the phase distribution of the second target;

[0085] Figure 9I It shows Figure 9H A schematic diagram of the DOE output optical field corresponding to the phase distribution of the third target in the diagram;

[0086] Figure 9J It shows Figure 9I A schematic diagram showing the energy percentage at each point in the output light field;

[0087] Figure 10 A cross-sectional schematic diagram of a DOE structure is shown;

[0088] Figure 11 A schematic block diagram of a light projection device is shown;

[0089] Figure 12 A schematic block diagram of a design system for a diffractive optical element is shown. Detailed Implementation

[0090] To make the objectives, technical solutions, and advantages of this application more apparent, exemplary embodiments according to this application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments of this application. It should be understood that this application is not limited to the exemplary embodiments described herein. Based on the embodiments of this application described herein, all other embodiments obtained by those skilled in the art without inventive effort should fall within the protection scope of this application.

[0091] The following description provides numerous specific details to offer a more thorough understanding of this application. However, it will be apparent to those skilled in the art that this application can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described to avoid confusion with this application.

[0092] It should be understood that this application can be implemented in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of this application to those skilled in the art.

[0093] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0094] To fully understand this application, a detailed structure will be presented in the following description to illustrate the technical solution proposed in this application. Optional embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other implementation methods.

[0095] Below, please refer to the appendix. Figure 1 To be continued Figure 9J The design method of the diffractive optical element of this application is described and explained. It is worth mentioning that, without conflict, the features of the various embodiments of this application can be combined with each other.

[0096] As an example, such as Figure 1 As shown, the design method 100 of this application includes the following steps S110 to S130:

[0097] In step S110, the target light field of the emitted light from the diffractive optical element on the output surface is obtained, wherein the output surface and the diffractive optical element are spaced apart by a predetermined distance; in step S120, based on the target light field, a first target phase distribution of the diffractive optical element is designed and obtained using scalar diffraction theory; in step S130, the first target phase distribution is optimized based on vector diffraction theory to obtain a second target phase distribution, wherein the second target phase distribution is used to characterize the distribution of multiple first microstructures on the diffractive optical element.

[0098] The design method of this application first obtains the first target phase distribution of the diffractive optical element through scalar design, and then optimizes the first target phase distribution using vector diffraction theory to obtain the second target phase distribution, thereby enabling the output light field of the DOE to have good uniformity.

[0099] The target light field can be the desired target light field of a designed diffractive optical element (DOE). The DOE projects the target light field onto an output surface at a predetermined distance (i.e., the designed distance) from the DOE. The target light field can include the light field of a beam-splitting lattice. A beam-splitting lattice is a type of diffractive optical element (DOE) whose function is to split an incident laser beam into multiple uniform outgoing laser beams through diffraction based on a target diffraction pattern (a regular or irregular lattice). Depending on different application requirements, the predetermined distance between the output surface and the diffractive optical element can be different, and the target light field can have different shapes, sizes, target diffraction patterns, etc.

[0100] The design of a DOE (Distributed Optical Element) is based on the target light field, ensuring that the actual light field formed by the designed DOE during actual use is substantially consistent with the target light field. The first phase distribution of the diffractive optical element can be designed and obtained using scalar diffraction theory based on the target light field. Any suitable method well-known to those skilled in the art can be used to design and obtain the first phase distribution of the diffractive optical element using scalar diffraction theory. For example, the GS algorithm and its improved versions, the Yang-Gu (YG) algorithm and its improved versions, simulated annealing (SA) algorithm, genetic algorithm (GA), and various hybrid algorithms can be used to obtain the first target phase distribution of the diffractive optical element.

[0101] The first target phase distribution of the DOE can be designed through multiple iterations. In a specific example, such as... Figure 2 As shown, in step S120, the step of designing and obtaining the first phase distribution of the diffractive optical element based on the target light field using scalar diffraction theory includes the following steps S11 to S16:

[0102] Step S11: Obtain the first input wavefunction of the input surface of the diffractive optical element. The first input wavefunction is determined based on a first estimated phase distribution and a preset input light amplitude distribution. The first estimated phase distribution is a random phase distribution, and the method for determining this random phase distribution can be any suitable method, which can be determined based on the target light field. It is worth noting that the first input wavefunction in the first iteration is determined based on the first estimated phase distribution and the preset input light amplitude distribution. Optionally, the preset input light amplitude distribution can be determined based on information such as the intensity of the emitted light emitted by the light source to be modulated by the diffractive optical element.

[0103] Step S12: Perform a forward diffraction operation on the first input wavefunction to obtain a first output wavefunction of the output surface, wherein the first output wavefunction includes the output light amplitude distribution and the output surface phase distribution; optionally, the forward diffraction operation can be performed on the first input wavefunction based on, for example, the Fresnel diffraction formula or the Fraunhofer diffraction formula.

[0104] Step S13: Modulate the output light amplitude distribution and update the first output wave function based on the modulated output light amplitude distribution to obtain the updated first output wave function; Optionally, the method for modulating the output light amplitude distribution can be any suitable modulation method, such as modulating the output light amplitude distribution through the target output light amplitude distribution, wherein the target output light amplitude distribution can be determined based on the designed target light field.

[0105] Step S14: Perform inverse diffraction on the updated first output wavefunction to obtain the second estimated phase distribution and the second input light amplitude distribution on the input surface; optionally, the inverse diffraction operation is the inverse operation of the forward diffraction operation. For example, when the forward diffraction operation is based on the Fresnel diffraction formula, the inverse diffraction operation can be the inverse Fresnel diffraction formula. As another example, when the forward diffraction operation is based on the Fraunhofer diffraction formula, the inverse diffraction operation can be the inverse Fraunhofer diffraction formula.

[0106] Step S15: Modulate the second input light amplitude distribution, and obtain the first input wave function for the next iteration based on the modulated second input light amplitude distribution and the second estimated phase distribution; Optionally, the method for modulating the second input light amplitude distribution can be any suitable method known to those skilled in the art, for example, the second input light amplitude distribution can be modulated by the preset input light amplitude distribution in step S11.

[0107] Step S16: Repeat steps S11 to S15 until the first iteration cycle termination condition is met, and output the second estimated phase distribution obtained in the last iteration as the first target phase distribution. Optionally, the first iteration cycle termination condition includes at least one of the following conditions: the number of iterations reaches a preset number; the uniformity of the output light amplitude distribution is less than or equal to a first preset uniformity, wherein the preset number and the first preset uniformity can be any suitable value reasonably set as needed, and are not specifically limited here. It is worth mentioning that after step S15 in each iteration process, it is determined whether the current iteration meets the first iteration cycle termination condition. If it does, the iteration stops, and the second estimated phase distribution obtained in the current iteration is output as the first target phase distribution. If it does not meet the condition, the process returns to step S11 for the next iteration until the first iteration cycle termination condition is met.

[0108] Furthermore, in step S130, the phase distribution of the first target is optimized based on vector diffraction theory to obtain the phase distribution of the second target, such as... Figure 3 As shown, the process includes the following steps S21 to S24:

[0109] Step S21: Obtain a first phase distribution and adjust the first phase distribution to obtain an adjusted phase distribution, wherein the first phase distribution at the time of the first iteration is the first target phase distribution. The method for adjusting the first phase distribution can be any suitable method well known to those skilled in the art, and is not specifically limited here.

[0110] Step S22: Using the vector diffraction theory, the output light field at the output surface of the input light after passing through the diffractive optical element with the adjusted phase distribution is simulated to obtain the first simulated light field; Optionally, the first simulated light field corresponding to the adjusted phase distribution can be obtained through the vector diffraction theory, so as to evaluate whether the adjusted phase distribution meets the requirements based on the first simulated light field.

[0111] Step S23: Determine whether the first simulated light field meets the first light field evaluation condition. If it meets the first light field evaluation condition, it indicates that the adjusted phase distribution is better than the first phase distribution. If it does not meet the first light field evaluation condition, it indicates that the adjusted phase distribution is worse than the first phase distribution. Then return to step S21. Optionally, the first light field evaluation condition includes: the uniformity of the first simulated light field is less than or equal to a second preset uniformity. Each iteration can correspond to a different second preset uniformity. For example, the second preset uniformity of the current iteration can be less than the uniformity of the simulated light field corresponding to the first phase distribution. Thus, the first light field evaluation condition is used to determine whether the adjusted phase is better than the first phase distribution. Alternatively, in other examples, the first light field evaluation condition may also include: the uniformity of the first simulated light field is less than the uniformity of the simulated light field corresponding to the first phase distribution. The simulated light field corresponding to the first phase distribution refers to the output light field obtained by simulating the output light field at the output surface after the input light passes through the diffractive optical element with the first phase distribution.

[0112] Step S24: Repeat steps S21 to S23 until the second iteration loop termination condition is met, and output the adjusted phase distribution corresponding to the first simulated light field that last met the first light field evaluation condition as the second target phase distribution. Optionally, the second iteration loop termination condition includes at least one of the following conditions: the number of iteration loops reaches a preset number, or the uniformity of the first simulated light field is lower than a preset uniformity. Since the method of this application first performs scalar diffraction theory calculations and then optimizes using vector diffraction theory, the uniformity of the output light field of the DOE obtained based on this design method is further improved.

[0113] It is worth mentioning that, before the end of the iteration, if the adjusted phase distribution obtained in the previous iteration is better than the first phase distribution, then the adjusted phase distribution obtained in the previous iteration will be used as the first phase distribution for the next iteration.

[0114] In this application, the uniformity of the light field can be defined as U = (Imax - Imin) / (Imax + Imin), where I represents light intensity, Imax represents the maximum light intensity, Imin represents the minimum light intensity, and U represents uniformity. Generally, the smaller the value of the uniformity U, the more uniform the light intensity distribution of the light field.

[0115] Through the above step S130, the first target phase distribution can be optimized based on vector diffraction theory to obtain a second target phase distribution. The second target phase distribution is used to characterize the distribution of multiple first microstructures on the diffractive optical element, such as... Figure 4 As shown, the white area represents the first microstructure, and the black area corresponds to the substrate layer of the DOE. Optionally, the multiple first microstructures can be a single periodically distributed microstructure or multiple periodically distributed microstructures. Optionally, in actual DOE devices, the first microstructure corresponding to the white area can typically be a protrusion structure on the DOE substrate.

[0116] In one example, after step S130, the design method of this application further includes step S140: adding at least one second microstructure to the second target phase distribution to obtain a third target phase distribution, wherein the second microstructure is used to modulate the high-frequency components of the light wave. Adding the second microstructure to the second phase distribution obtained through vector diffraction theory optimization can enhance the modulation capability of the DOE to the high-frequency components of the light wave, thereby further improving the uniformity of the output light field of the DOE obtained based on this design method.

[0117] Optionally, the length of the second microstructure on the surface of the diffractive optical element is less than or equal to 1 / 2 of the wavelength of the input light. This length can refer to the maximum diagonal dimension of the projection of the second microstructure onto the DOE substrate surface, and for a regular circular second microstructure, this length is also the diameter of the circle.

[0118] Optionally, such as Figure 6 As shown, the shape of the second microstructure can be a relatively regular circle, ellipse or rectangle, or it can be an irregular shape, and there is no specific limitation on it here.

[0119] At least one second microstructure can be added to the second target phase distribution using any suitable method known to those skilled in the art to obtain a third target phase distribution. For example, in one example, such as Figure 5 As shown, adding at least one second microstructure to the second target phase distribution to obtain a third target phase distribution includes the following steps S31 to S34:

[0120] Step S31: Add at least one second microstructure to the second phase distribution to obtain a third phase distribution, wherein the second phase distribution in the first iteration is the second target phase distribution; In summary, the method of adding at least one second microstructure to the second phase distribution can be any suitable method known to those skilled in the art, and is not specifically limited here. For example, in the first iteration, any suitable number and shape of second microstructures can be added randomly at any position in the second phase distribution.

[0121] Step S32: The output light field at the output surface after passing through the diffractive optical element with the third phase distribution is simulated using the vector diffraction theory to obtain the second simulated light field; Optionally, the second simulated light field corresponding to the third phase distribution can be obtained through the vector diffraction theory, so as to evaluate whether the third phase distribution meets the requirements based on the second simulated light field.

[0122] Step S33: Determine whether the second simulated light field meets the second light field evaluation condition. If it meets the second light field evaluation condition, it indicates that the third phase distribution is better than the second phase distribution. If it does not meet the second light field evaluation condition, it indicates that the third phase distribution is worse than the second phase distribution, and return to step S31. Optionally, the second light field evaluation condition includes: the uniformity of the second simulated light field is less than or equal to a third preset uniformity. Each iteration can correspond to a different third preset uniformity. For example, the third preset uniformity of the current iteration can be less than the uniformity of the simulated light field corresponding to the second phase distribution, thereby determining whether the third phase distribution is better than the second phase distribution through the second light field evaluation condition. Alternatively, in other examples, the second light field evaluation condition may also include: the uniformity of the second simulated light field is less than the uniformity of the simulated light field corresponding to the second phase distribution. The simulated light field corresponding to the second phase distribution refers to the output light field obtained by simulating the output light field at the output surface after the input light passes through the diffractive optical element with the second phase distribution.

[0123] Step S34: Repeat steps S31 to S33 until the third iteration cycle termination condition is met, and output the third phase distribution corresponding to the second simulated light field that last met the second light field evaluation condition as the third target phase distribution. Optionally, the third iteration cycle termination condition includes at least one of the following conditions: the number of iteration cycles reaches a preset number, or the uniformity of the second simulated light field is lower than a preset uniformity.

[0124] It is worth mentioning that, before the end of the iteration, if the third phase distribution obtained in the previous iteration is better than the second phase distribution, then the third phase distribution obtained in the previous iteration will be used as the second phase distribution in the next iteration.

[0125] By using step S140 of this application, a second microstructure can be added to the second phase distribution to obtain a third target phase distribution, which can be used for subsequent DOE fabrication.

[0126] In DOE microstructure design diagrams (such as the design diagram corresponding to the phase distribution of the third target), the larger continuous structural morphology can be referred to as a continent, which corresponds to the first microstructure. The size of the first microstructure is larger than that of the second microstructure.

[0127] Optionally, such as Figure 7 As shown, at least one second microstructure is located outside the first microstructure and is not connected to any of the first microstructures, i.e., it is scattered among the first microstructures (also referred to as continental blocks) to form an island; and / or at least one second microstructure is located within the first microstructure. For example, when at least one second microstructure is located within the first microstructure, the second microstructure appears as a groove, which can also be described as being scattered inside the continental block to form a hole; and / or at least one second microstructure is located at the edge of the first microstructure and is connected to the first microstructure, i.e., it is scattered at the edge of the continental block to form a tentacle. The second microstructures located within the first microstructure can also be scattered among the continental blocks to form islands.

[0128] In the third target phase distribution, the first microstructure is arranged periodically. For example, the same first microstructure can be arranged periodically at a predetermined interval. The number of second microstructures added to the third target phase distribution can be any suitable number. Optionally, the number of second microstructures is not less than 10 in each period of the first microstructure.

[0129] In one specific embodiment of this application, a collimated light DOE with 61 beam-splitting points can be designed based on the design method of this application, and its target light field is as follows: Figure 8A As shown, the first target phase distribution obtained through scalar optimization in step S120 can be as follows: Figure 8B As shown, the output light field corresponding to the phase distribution of the first target is as follows: Figure 8C As shown, the energy percentage at each point of the output light field is as follows: Figure 8D As shown, the uniformity of the output optical field of the scalar-optimized DOE microstructure is 57%. The second target phase distribution obtained after vector optimization in step S130 can be as follows: Figure 8E As shown, the output light field corresponding to the phase distribution of the second target is as follows: Figure 8F As shown, the energy percentage at each point of the output light field is as follows: Figure 8GAs shown, the uniformity of the output light field is reduced to 20%. This demonstrates that the uniformity of the output light field is significantly improved after vector optimization compared to scalar optimization. After step S140, which involves adding a second microstructure (also known as a high-frequency fine structure) to the second target phase distribution, the third target phase distribution can be obtained as follows: Figure 8H As shown, the output light field corresponding to the phase distribution of the third target is as follows: Figure 8I As shown, the energy percentage at each point of the output light field is as follows: Figure 8J As shown, the uniformity of the output light field is reduced to 13%, indicating that the energy ratio of each point in the output light field is more consistent and uniform compared to the result of vector optimization.

[0130] In another embodiment of this application, a collimated light DOE with an 89-point beam splitter array is designed, and its target light field is as follows: Figure 9A As shown, the first target phase distribution obtained through scalar optimization in step S120 can be as follows: Figure 9B As shown, the output light field corresponding to the phase distribution of the first target is as follows: Figure 9C As shown, the energy percentage at each point of the output light field is as follows: Figure 9D As shown, the uniformity of the output optical field of the scalar-optimized DOE microstructure is 46%. The second target phase distribution obtained after vector optimization in step S130 can be as follows: Figure 9E As shown, the output light field corresponding to the phase distribution of the second target is as follows: Figure 9F As shown, the energy percentage at each point of the output light field is as follows: Figure 9G As shown, the uniformity of the output light field decreased to 28%, indicating that the uniformity of the output light field after vector optimization was significantly improved compared to the scalar optimization result. After step S140, by adding a second microstructure (also known as a high-frequency fine structure) to the second target phase distribution, the third target phase distribution can be obtained as follows: Figure 9H As shown, the output light field corresponding to the phase distribution of the third target is as follows: Figure 9I As shown, the energy percentage at each point of the output light field is as follows: Figure 9J As shown, the uniformity of the output light field is reduced to 19%, indicating that the energy ratio of each point in the output light field is more consistent and uniform compared to the result of vector optimization.

[0131] This concludes the description of the main steps of the design method of this application. Without conflict, the order of the steps in this application can be alternated or changed.

[0132] In summary, the design method of this application first obtains the first target phase distribution of the diffractive optical element through scalar design, and then optimizes the first target phase distribution using vector diffraction theory to obtain a second target phase distribution, thereby improving the uniformity of the output light field of the DOE. Furthermore, the method of this application can further improve the uniformity of the output light field of the DOE by adding a second microstructure to the second target phase distribution to obtain a third target phase distribution. The second microstructure can modulate the high-frequency components of the light wave, thereby further improving the uniformity of the output light field of the DOE.

[0133] Furthermore, this application also provides a diffractive optical element designed based on the aforementioned design method, which will be referred to below. Figure 10 The diffractive optical element is described.

[0134] As an example, such as Figure 10 As shown, the diffractive optical element 600 of this application includes: a substrate 610 and a plurality of microstructure units formed on the substrate 610, wherein the plurality of microstructure units include a plurality of first microstructures 620 and at least one second microstructure (not shown), the microstructure units are configured to split the emitted light emitted by the light source into multiple outgoing light beams, and the at least one second microstructure is used to modulate the high-frequency component of the light wave.

[0135] The substrate 610 can be any suitable material, such as glass. The first microstructure 620 and the second microstructure can be protrusions located on the surface of the substrate 610.

[0136] Microstructures corresponding to the second or third target phase distribution described above can be formed on the substrate 610 using any suitable method. For example, microstructures can be formed in the polymer by coating the substrate 610 with a polymer material and then imprinting it, or microstructures can be formed by etching the substrate 610.

[0137] Optionally, the distribution of the plurality of first microstructures 620 is designed by using scalar diffraction theory to obtain the first target phase distribution of the diffractive optical element, and by optimizing the first target phase distribution based on vector diffraction theory.

[0138] In one example, the length of the second microstructure on the surface of the substrate 610 is less than or equal to half the wavelength of the emitted light.

[0139] In one example, at least one second microstructure is located outside the first microstructure 620 and is not connected to any of the first microstructures 620; and / or at least one second microstructure is located inside the first microstructure 620, for example, when at least one second microstructure is located inside the first microstructure 620, the second microstructure is presented as a groove; and / or at least one second microstructure is located at the edge of the first microstructure 620 and is connected to the first microstructure 620.

[0140] The first microstructure 620 is arranged periodically. For example, identical first microstructures 620 can be arranged periodically at predetermined intervals. The number of second microstructures can be any suitable number. Optionally, the number of second microstructures is not less than 10 in each period of the first microstructure 620. Some details of this embodiment can also be found in the preceding embodiments.

[0141] Since the DOE in this embodiment is designed based on the aforementioned design method, it has the same advantages as the aforementioned design method. The energy ratio of each beam splitting point after the emitted light from the light source is projected by the DOE is consistent and more uniform.

[0142] Furthermore, this application also provides a light projection device, which may include the aforementioned diffractive optical element. Reference will now be made to... Figure 11 The light projection device of this application will be described.

[0143] As an example, such as Figure 11 As shown, the light projection device 1100 may include a light source 1110 for emitting light. Optionally, the light source 1110 may be a laser emitter for emitting laser light.

[0144] A diffractive optical element 1120 is disposed in the optical path of the emitted light from the light source 1110. It receives the emitted light from the light source, splits the emitted light into multiple outgoing beams, and modulates the high-frequency components of the light wave to project a light field onto the target surface. This output light field exhibits excellent uniformity. The diffractive optical element 1120 can be implemented based on the aforementioned diffractive optical element 600.

[0145] The number of beams can be reasonably set during the design process according to actual needs. For example, the output light field can be implemented as described in the aforementioned embodiment. Figure 8A and Figure 9A The style shown.

[0146] In addition to a light source and a DOE, the light projection device may also include other optical systems, such as a collimating lens group. The collimating lens group can be placed between the light source and the DOE to collimate the emitted light from the light source.

[0147] The light projection device of this application may also include other components, which are not specifically limited here. Since the light projection device of this application has the DOE in the foregoing embodiments, it has the same advantages as the foregoing DOE.

[0148] Furthermore, this application embodiment also includes a device, which can be any device having the aforementioned light projection device, such as security equipment, terminal equipment, mobile platform equipment, etc. Terminal equipment may include, but is not limited to, mobile phones, tablets, laptops, desktop computers, etc., and mobile platform equipment may include, but is not limited to, vehicles, aircraft, ships, robots, etc., wherein the vehicle may also be an unmanned vehicle, etc.

[0149] Since the device of this application has the aforementioned light projection device, the energy distribution uniformity of the beam-splitting array projected by the light projection device is good, thus improving the device's ability to detect and sense the environment.

[0150] This application also provides a design system for diffractive optical elements. This design system can be used as the execution subject of the aforementioned design method for diffractive optical elements. This design system can be implemented based on any computing device with data processing and computing capabilities, such as a desktop computer or a laptop.

[0151] As an example, such as Figure 12 As shown, the design system 1200 includes one or more processors 1210, a display, a memory 1220, and a communication interface, etc. These components are interconnected via a bus system and / or other forms of connection mechanisms (not shown). It should be noted that... Figure 12 The components and structures of the design system 1200 shown are merely exemplary and not limiting; the design system 1200 may also have other components and structures as needed.

[0152] Memory 1220 is used to store various data and executable programs generated during the design process of diffractive optical elements, such as system programs, various application programs, or algorithms that implement various specific functions of the design system 1200. It may include one or more computer program products, which can include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. Volatile memory may include, for example, random access memory (RAM) and / or cache memory. Non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. In the design system, any data that needs to be stored locally can be stored in memory 1220.

[0153] Processor 1210 may be a central processing unit (CPU), graphics processing unit (GPU), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), or other form of processing unit with data processing and / or instruction execution capabilities, and may control other components in the design system 1200 to perform desired functions. For example, processor 1210 may include one or more embedded processors, processor cores, microprocessors, logic circuits, hardware finite state machines (FSMs), digital signal processors (DSPs), graphics processing units (GPUs), or combinations thereof.

[0154] In one example, design system 1200 also includes a communication interface (not shown) for communication between components within design system 1200 and between components of design system 1200 and other devices outside the system. The communication interface can be an interface using any known communication protocol, such as a wired or wireless interface. The communication interface may include one or more serial ports, USB interfaces, Ethernet ports, WiFi, wired networks, DVI interfaces, device interconnect modules, or other suitable ports, interfaces, or connections.

[0155] In one example, the design system also includes an input device (not shown), which can be a device used by a user to input instructions, and can include one or more of a keyboard, trackball, mouse, microphone and touch screen, or other input devices consisting of control buttons.

[0156] The design system of this invention also includes an output device that can output various information (e.g., images or sounds) to the outside (e.g., a user), and may include one or more of a display, a speaker, etc.

[0157] In this embodiment, the display of the design system can be a touch screen, an LCD screen, or a standalone display such as an LCD screen or television, independent of the design system. It can also be a display screen on an electronic device such as a mobile phone or tablet. The display can be used to show information input by the user or information provided to the user, as well as various graphical user interfaces of the design system. These graphical user interfaces can be composed of graphics, text, icons, video, and any combination thereof.

[0158] The processor 1210 can be used to execute program instructions stored in memory, causing the processor to execute the design method 100 of the diffractive optical element described herein. The specific design method of the diffractive optical element can be referred to the previous description and will not be repeated here.

[0159] In addition, embodiments of this application also provide a computer storage medium on which a computer program is stored. One or more computer program instructions may be stored on the computer-readable storage medium, and a processor may execute the program instructions stored in the storage device to implement the functions (implemented by the processor) in the embodiments of this application and / or other desired functions, such as performing the corresponding steps of the design method 100 for diffractive optical elements according to embodiments of this application. Various application programs and various data may also be stored in the computer-readable storage medium, such as various data used and / or generated by the application programs.

[0160] For example, the computer storage medium may include a memory card for a smartphone, a storage component for a tablet computer, a hard disk for a personal computer, a read-only memory (ROM), an erasable programmable read-only memory (EPROM), a portable compact disc read-only memory (CD-ROM), a USB memory, or any combination of the above storage media. The computer-readable storage medium may be any combination of one or more computer-readable storage media.

[0161] Although exemplary embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above exemplary embodiments are merely illustrative and are not intended to limit the scope of this application. Various changes and modifications can be made therein by those skilled in the art without departing from the scope and spirit of this application. All such changes and modifications are intended to be included within the scope of this application as claimed in the appended claims.

[0162] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0163] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed.

[0164] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of this application may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0165] Similarly, it should be understood that, in order to streamline this application and aid in understanding one or more of the various inventive aspects, features of this application may sometimes be grouped together in a single embodiment, figure, or description thereof in the description of exemplary embodiments of this application. However, this approach should not be construed as reflecting an intention that the claimed application requires more features than are expressly recited in each claim. Rather, as reflected in the corresponding claims, its inventive point lies in solving the corresponding technical problem with features fewer than all features of a single disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of this application.

[0166] Those skilled in the art will understand that, apart from the mutual exclusion of features, all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or elements of any method or apparatus so disclosed can be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature serving the same, equivalent, or similar purpose.

[0167] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features but not others included in other embodiments, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

[0168] The various component embodiments of this application can be implemented in hardware, or as software modules running on one or more processors, or a combination thereof. Those skilled in the art will understand that microprocessors or digital signal processors (DSPs) can be used in practice to implement some or all of the functions of some modules according to the embodiments of this application. This application can also be implemented as an apparatus program (e.g., a computer program and computer program product) for performing part or all of the methods described herein. Such an implementation of this application can be stored on a computer-readable medium, or can be in the form of one or more signals. Such signals can be downloaded from an Internet website, provided on a carrier signal, or provided in any other form.

[0169] It should be noted that the above embodiments are illustrative of this application and not limiting of it, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. This application can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

Claims

1. A method for designing a diffractive optical element, characterized in that, The design method includes: The target light field of the emitted light after exiting from the diffractive optical element is obtained on the output surface, wherein the output surface and the diffractive optical element are spaced apart by a predetermined distance; Based on the target light field, the first target phase distribution of the diffractive optical element is designed and obtained using scalar diffraction theory. Optimizing the first target phase distribution based on vector diffraction theory to obtain a second target phase distribution, wherein the second target phase distribution is used to characterize the distribution of multiple first microstructures on the diffractive optical element, and optimizing the first target phase distribution based on vector diffraction theory to obtain the second target phase distribution specifically includes the following steps: Step S21: Obtain a first phase distribution and adjust the first phase distribution to obtain an adjusted phase distribution, wherein the first phase distribution at the first iteration is the first target phase distribution; Step S22: Using the vector diffraction theory, the output light field at the output surface of the input light after passing through the diffraction optical element with the adjusted phase distribution is simulated to obtain the first simulated light field; Step S23: Determine whether the first simulated light field meets the first light field evaluation condition. If it meets the first light field evaluation condition, it indicates that the adjusted phase distribution is better than the first phase distribution. If it does not meet the first light field evaluation condition, it indicates that the adjusted phase distribution is worse than the first phase distribution. Then return to step S21. Step S24: Repeat steps S21 to S23 until the second iteration loop termination condition is met, and output the adjusted phase distribution corresponding to the first simulated light field that last meets the first light field evaluation condition as the second target phase distribution.

2. The design method as described in claim 1, characterized in that, Based on the target light field, the first phase distribution of the diffractive optical element is designed and obtained using scalar diffraction theory, including: Step S11: Obtain the first input wave function of the input surface of the diffractive optical element, wherein the first input wave function in the first iteration is determined based on the first estimated phase distribution and the preset input light amplitude distribution, and the first estimated phase distribution is a random phase distribution; Step S12: Perform forward diffraction operation on the first input wave function to obtain the first output wave function of the output surface, wherein the first output wave function includes the output light amplitude distribution and the output surface phase distribution; Step S13: Modulate the output light amplitude distribution and update the first output wave function based on the modulated output light amplitude distribution to obtain the updated first output wave function; Step S14: Perform inverse diffraction operation on the updated first output wavefunction to obtain the second estimated phase distribution and the second input light amplitude distribution on the input surface; Step S15: Modulate the second input light amplitude distribution, and obtain the first input wave function for the next iteration based on the modulated second input light amplitude distribution and the second estimated phase distribution; Step S16: Repeat steps S11 to S15 until the first iteration loop termination condition is met, and output the second estimated phase distribution obtained in the last iteration as the first target phase distribution.

3. The design method as described in claim 2, characterized in that, The termination condition for the first iteration loop includes at least one of the following conditions: The preset number of iterations has been reached; The uniformity of the output light amplitude distribution is less than or equal to the first preset uniformity.

4. The design method as described in claim 1, characterized in that, If, before the end of the iteration, the adjusted phase distribution obtained in the previous iteration is better than the first phase distribution, then the adjusted phase distribution obtained in the previous iteration shall be used as the first phase distribution for the next iteration.

5. The design method as described in claim 1 or 4, characterized in that, The first light field evaluation condition includes: the uniformity of the first simulated light field is less than or equal to the second preset uniformity.

6. The design method as described in claim 1, characterized in that, The design method further includes: At least one second microstructure is added to the second target phase distribution to obtain a third target phase distribution, wherein the second microstructure is used to modulate the high-frequency components of the light wave.

7. The design method as described in claim 6, characterized in that, Adding at least one second microstructure to the second target phase distribution to obtain the third target phase distribution includes: Step S31: Add at least one second microstructure to the second phase distribution to obtain a third phase distribution, wherein the second phase distribution during the first iteration is the second target phase distribution; Step S32: Use the vector diffraction theory to simulate the output light field at the output surface after passing through the diffractive optical element with the third phase distribution, so as to obtain the second simulated light field; Step S33: Determine whether the second simulated light field meets the second light field evaluation condition. If it meets the second light field evaluation condition, it indicates that the third phase distribution is better than the second phase distribution. If it does not meet the second light field evaluation condition, it indicates that the third phase distribution is worse than the second phase distribution. Return to step S31. Step S34: Repeat steps S31 to S33 until the third iteration loop termination condition is met, and output the third phase distribution corresponding to the second simulated light field that last met the second light field evaluation condition as the third target phase distribution.

8. The design method as described in claim 7, characterized in that, If, before the end of the iteration, the third phase distribution obtained in the previous iteration is better than the second phase distribution, then the third phase distribution obtained in the previous iteration is used as the second phase distribution for the next iteration.

9. The design method as described in claim 7, characterized in that, The second light field evaluation condition includes: the uniformity of the second simulated light field is less than or equal to the third preset uniformity.

10. The design method according to any one of claims 6 to 9, characterized in that, The length of the second microstructure on the surface of the diffractive optical element is less than or equal to 1 / 2 of the wavelength of the input light.

11. The design method as described in claim 6, characterized in that, At least one of the second microstructures is located outside the first microstructure and is not connected to any of the first microstructures; and / or At least one of the second microstructures is located within the first microstructure; and / or At least one of the second microstructures is located at the edge of the first microstructure and is connected to the first microstructure.

12. The design method as described in claim 11, characterized in that, When at least one of the second microstructures is located within the first microstructure, the second microstructure presents as a groove.

13. The design method as described in claim 6, characterized in that, The number of the second microstructure is not less than 10 in each cycle of the first microstructure.

14. A diffractive optical element designed based on the design method of a diffractive optical element as described in any one of claims 1 to 13, characterized in that, include: The substrate and a plurality of microstructure units formed on the substrate, wherein the plurality of microstructure units include a plurality of first microstructures, the microstructure units being configured to split the emitted light emitted by the light source into multiple outgoing light beams, wherein the distribution of the plurality of first microstructures is designed and obtained by using scalar diffraction theory to design and obtain a first target phase distribution of the diffractive optical element, and by optimizing the first target phase distribution based on vector diffraction theory.

15. The diffractive optical element as claimed in claim 14, characterized in that, The plurality of microstructure units further include at least one second microstructure, wherein the second microstructure is used to modulate the high-frequency component of the light wave.

16. The diffractive optical element as claimed in claim 15, characterized in that, The length of the second microstructure on the substrate surface is less than or equal to 1 / 2 of the wavelength of the emitted light.

17. The diffractive optical element as claimed in claim 15, characterized in that, At least one of the second microstructures is located outside the first microstructure and is not connected to any of the first microstructures; and / or At least one of the second microstructures is located within the first microstructure; and / or At least one of the second microstructures is located at the edge of the first microstructure and is connected to the first microstructure.

18. The diffractive optical element as claimed in claim 17, characterized in that, When at least one of the second microstructures is located within the first microstructure, the second microstructure presents as a groove.

19. The diffractive optical element as claimed in claim 15, characterized in that, The number of the second microstructure is not less than 10 in each cycle of the first microstructure.

20. The diffractive optical element as claimed in any one of claims 14 to 19, characterized in that, The first microstructure includes a protrusion structure located on the surface of the substrate.

21. A light projection device, characterized in that, include: A light source, used to emit light; The diffractive optical element as described in any one of claims 14 to 20 is disposed in the optical path of the emitted light of the light source, for receiving the emitted light emitted by the light source, splitting the emitted light emitted by the light source into multiple outgoing light beams, and for modulating the high-frequency component of the light wave to project a light field onto the target surface.

22. A device for environmental detection and sensing, characterized in that, Includes the light projection device as described in claim 21.

23. A design system for a diffractive optical element, characterized in that, The design system includes: Memory is used to store executable program instructions; One or more processors are configured to execute the program instructions stored in the memory, such that the processors perform the design method as described in any one of claims 1 to 13.

24. A computer storage medium having a computer program stored thereon, the computer program being executed by a processor to implement the design method as described in any one of claims 1 to 13.

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