Superlens for projecting X-shaped light spots, design method thereof and emission module

Abstract

The invention provides a super lens for projecting an X-shaped light spot, a design method of the super lens and an emission module. The invention provides a super lens for projecting X-shaped light spots. The super lens comprises a substrate and a micro-nano structure arranged on the substrate, the super lens is used for receiving incident light and modulating and outputting the incident light so as to project to obtain an X-shaped light spot; the sub-areas in the coverage area of the X-shaped light spots are in one-to-one mapping with the sub-areas in the effective area of the super lens. The X-shaped light spot projected by the super lens provided by the invention can be a cross-shaped light spot, and the light intensity distribution of the X-shaped light spot projected by the super lens can accurately meet the target requirement.

Description

Technical Field

[0001] This application relates to the field of optics, and particularly to a metalens for projecting an X-shaped light spot, its design method, and an emission module. Background Art

[0002] An X-shaped light spot refers to a light spot whose shape is similar to the letter "X", and it can be regarded as obtained by the intersection of two line light spots; when the two line light spots forming the X-shaped light spot intersect perpendicularly, the shape of the X-shaped light spot is similar to the Chinese character "十" (cross), so in this case, the X-shaped light spot can also be called a cross-shaped light spot.

[0003] Cross-shaped light spots are widely used in scenarios such as alignment and positioning, optical measurement, microscope observation, virtual reality, and augmented reality. In related technologies, a lens group composed of two mutually perpendicular cylindrical lenses with one long and one short, or a lens group formed by splicing multiple refractive mirrors, is usually used to generate cross-shaped light spots. Since these lens groups require at least two traditional lenses, their volumes are relatively large, which is not conducive to the miniaturization of optical devices. To facilitate the miniaturization of optical devices, related technologies also propose using a single metalens to generate cross-shaped light spots. However, for the metalens provided by related technologies for generating cross-shaped light spots, the light intensity distribution of the projected cross-shaped light spot is difficult to accurately meet the target requirements. Summary of the Invention

[0004] An object of this application is to provide a metalens for projecting an X-shaped light spot, its design method, and an emission module. The X-shaped light spot projected by the metalens provided by this application can be a cross-shaped light spot, and moreover, the light intensity distribution of the projected X-shaped light spot can accurately meet the target requirements.

[0005] According to one aspect of the embodiments of this application, a metalens for projecting an X-shaped light spot is disclosed. The metalens includes a substrate and a micro-nano structure disposed on the substrate; the metalens is configured to receive incident light, modulate the incident light, and output it to project an X-shaped light spot;

[0006] Each sub-region within the coverage area of the X-shaped light spot is mapped one-to-one with each sub-region within the effective area of the metalens.

[0007] In an exemplary embodiment of this application, the X-shaped light spot includes an intersecting first line light spot and a second line light spot; the first line light spot intersects the second line light spot perpendicularly.

[0008] According to one aspect of an embodiment of the present application, a design method for a metalens for projecting an X-shaped light spot is disclosed, the method being used to design a metalens as provided in any one of the above embodiments, wherein the X-shaped light spot comprises an intersecting first line light spot and a second line light spot, wherein the first line light spot and the second line light spot share an overlapping area; the method comprising:

[0009] Based on a first target light intensity distribution of the first line light spot, a first phase for the first line light spot to be projected by the metalens is obtained, and based on a second target light intensity distribution of the second line light spot, a second phase for the second line light spot to be projected by the metalens is obtained;

[0010] Based on the first phase and the second phase, simulating the process of the superlens projecting the X-shaped light spot to obtain a simulated light intensity distribution of the X-shaped light spot;

[0011] If the simulated light intensity distribution does not meet the target requirement, the first target light intensity distribution and the second target light intensity distribution are collaboratively optimized at least in the overlapping area, and based on the optimized target light intensity distribution, the first phase, the second phase and the simulated light intensity distribution are updated until the simulated light intensity distribution meets the target requirement, thereby obtaining the first phase and the second phase that meet the target requirement;

[0012] Based on the first phase and the second phase that meet target requirements, the superlens for projecting the X-shaped light spot is constructed.

[0013] In an exemplary embodiment of the present application, the method further includes:

[0014] If the simulated light intensity distribution does not meet the target requirement, the first target light intensity distribution and the second target light intensity are subjected to distributed optimization outside the overlapping area.

[0015] In an exemplary embodiment of the present application, in the overlapping area, the first target light intensity distribution and the second target light intensity distribution are collaboratively optimized, including:

[0016] In the overlapping area, the first target light intensity distribution and the second target light intensity distribution are first weakened, and then the weakened first target light intensity distribution and the second target light intensity distribution are collaboratively optimized.

[0017] In an exemplary embodiment of the present application, in the overlapping area, the first target light intensity distribution and the second target light intensity distribution are weakened, including:

[0018] Based on the coherence of the incident light, determining a multiplication factor of the light intensity after superposition in the overlapping area compared to the light intensity without superposition;

[0019] Based on the multiplication factor, the first target light intensity distribution and the second target light intensity distribution are weakened in the overlapping area.

[0020] In an exemplary embodiment of the present application, in the overlapping area, the first target light intensity distribution and the second target light intensity distribution are weakened, including:

[0021] In the overlapping region, determining a first minimum light intensity that the first target light intensity distribution should reach after the light intensity is weakened, and a second minimum light intensity that the second target light intensity distribution should reach;

[0022] In the overlapping area, a first Gaussian function with coordinate shift is used to describe the first target light intensity distribution after the light intensity is weakened; the light intensity described by the first Gaussian function with coordinate shift at the center position of the overlapping area matches the first minimum light intensity; the light intensity described by the first Gaussian function with unshifted coordinate at the center position of the overlapping area matches the maximum light intensity of the first target light intensity distribution;

[0023] In the overlapping area, a second Gaussian function with coordinate shift is used to describe the second target light intensity distribution after the light intensity is weakened; the light intensity described by the second Gaussian function with coordinate shift at the center position of the overlapping area matches the second minimum light intensity; the light intensity described by the second Gaussian function with unshifted coordinates at the center position of the overlapping area matches the maximum light intensity of the second target light intensity distribution.

[0024] In an exemplary embodiment of the present application, the first target light intensity distribution and the second target light intensity distribution are both described and optimized using a high-order modulus Gaussian function.

[0025] In an exemplary embodiment of the present application, the high-order modulus Gaussian function includes: a super Gaussian function, a flat-top Gaussian function, and a super Lorentzian function.

[0026] According to one aspect of an embodiment of the present application, an emission module for projecting an X-shaped light spot is disclosed, the emission module comprising: a light source; a super lens as provided in any of the above embodiments;

[0027] The super lens is arranged on the light-emitting side of the light source; the super lens is used to receive the light beam emitted by the light source, and modulate and project the light beam emitted by the light source into an X-shaped light spot.

[0028] According to one aspect of an embodiment of the present application, a design device for a metalens for projecting an X-shaped light spot is disclosed, the device comprising:

[0029] A phase acquisition module is configured to acquire a first phase for the first line light spot to be projected by the metalens based on a first target light intensity distribution of the first line light spot, and to acquire a second phase for the second line light spot to be projected by the metalens based on a second target light intensity distribution of the second line light spot;

[0030] A simulation module is configured to simulate a process of projecting an X-shaped light spot by the metalens based on the first phase and the second phase to obtain a simulated light intensity distribution of the X-shaped light spot;

[0031] The optimization module is configured to collaboratively optimize the first target light intensity distribution and the second target light intensity distribution at least in the overlapping area if the simulated light intensity distribution does not meet the target requirement, and update the first phase, the second phase and the simulated light intensity distribution based on the optimized target light intensity distribution until the simulated light intensity distribution meets the target requirement, thereby obtaining the first phase and the second phase that meet the target requirement;

[0032] The building module is configured to build a metalens for projecting an X-shaped light spot based on a first phase and a second phase that meet target requirements.

[0033] According to one aspect of an embodiment of the present application, an electronic device is disclosed, comprising: one or more processors; and a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the electronic device implements any one of the above method embodiments.

[0034] According to one aspect of an embodiment of the present application, a computer-readable storage medium is disclosed, on which computer-readable instructions are stored. When the computer-readable instructions are executed by a processor of a computer, the computer is caused to execute any one of the above method embodiments.

[0035] In the embodiment of the present application, each sub-area within the coverage area of ​​the X-shaped light spot is mapped one-to-one with each sub-area within the effective area of ​​the metalens 2, that is, any point in the X-shaped light spot is not formed by the superposition of physically independent light spots from different sources. Therefore, the light intensity of any point in the X-shaped light spot will not produce uncontrollable mutations. Therefore, the light intensity distribution of the X-shaped light spot projected by the metalens 2 provided in the present application can accurately meet the target requirements.

[0036] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by the practice of the present application.

[0037] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The above and other objects, features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

[0039] Figure 1 A schematic diagram of an X-shaped light spot in an embodiment of the present application is shown.

[0040] Figure 2 A schematic diagram of an X-shaped light spot in an embodiment of the present application is shown.

[0041] Figure 3 A schematic diagram of an X-shaped light spot in an embodiment of the present application is shown.

[0042] Figure 4 A schematic diagram of an X-shaped light spot in an embodiment of the present application is shown.

[0043] Figure 5 A schematic diagram of an X-shaped light spot in an embodiment of the present application is shown.

[0044] Figure 6 A schematic diagram of the structure of the metalens provided in this application is shown.

[0045] Figure 7 A schematic diagram of mapping between sub-regions within the coverage area of ​​the X-shaped light spot and sub-regions within the effective area of ​​the metalens in one embodiment of the present application is shown.

[0046] Figure 8 A flow chart of a method for designing a metalens for projecting an X-shaped light spot provided in the present application is shown.

[0047] Fig. 9 A schematic diagram showing, in an embodiment of the present application, a first Gaussian function whose coordinates are not offset is used to describe the first target light intensity distribution before the light intensity is weakened in the overlapping area.

[0048] Fig.10 A schematic diagram showing a first target light intensity distribution after light intensity attenuation in an overlapping region using a first Gaussian function with coordinate shifting in one embodiment of the present application is shown.

[0049] Fig.11 A schematic diagram showing, in one embodiment of the present application, a second Gaussian function with unshifted coordinates is used to describe the second target light intensity distribution before the light intensity is weakened in the overlapping area.

[0050] Fig.12A schematic diagram showing a second target light intensity distribution after light intensity attenuation in an overlapping region using a second Gaussian function with coordinate shifting in one embodiment of the present application is shown.

[0051] Fig.13 A schematic diagram of the architecture of the transmission module provided in an embodiment of the present application is shown.

[0052] Fig.14 (a) shows the target light intensity distribution of a cross-shaped light spot in one embodiment of the present application.

[0053] Fig.14 (b) shows Fig.14 (a) shows the target light intensity distribution of the horizontal line spot in the horizontal direction.

[0054] Fig.14 (c) shows Fig.14 Target light intensity distribution of the vertical line light spot in the vertical direction in (a).

[0055] Fig.15 (a) shows a comparative example, according to Fig.14 The target light intensity distribution of the cross-shaped light spot shown in (a) is obtained by adopting the design method provided by the relevant technology to design the light intensity distribution of the cross-shaped light spot projected by the super lens.

[0056] Fig.15 (b) shows Fig.15 (a) shows the light intensity distribution of the horizontal line spot in the horizontal direction.

[0057] Fig.15 (c) shows Fig.15 Light intensity distribution of the vertical line light spot in the vertical direction in (a).

[0058] Fig.16 (a) shows an embodiment of the present application, according to Fig.14 The target light intensity distribution of the cross-shaped light spot shown in (a) is obtained by weakening the target light intensity distribution of the horizontal line light spot in the horizontal direction and the target light intensity distribution of the vertical line light spot in the vertical direction in the overlapping area, thereby obtaining the light intensity distribution of the cross-shaped light spot used as the iterative optimization target.

[0059] Fig.16 (b) shows Fig.16 (a) shows the light intensity distribution of the horizontal line spot in the horizontal direction.

[0060] Fig.16 (c) shows Fig.16 Light intensity distribution of the vertical line light spot in the vertical direction in (a).

[0061] Fig.17 (a) shows an embodiment of the present application, according to Fig.14 The target light intensity distribution of the cross-shaped light spot shown in (a) adopts the design method provided by this application and is based on Fig.16 After iterative optimization of the weakened light intensity distribution shown in (a), the intensity distribution of the cross-shaped light spot projected by the finally designed superlens is obtained.

[0062] Fig.17 (b) shows Fig.17 (a) shows the light intensity distribution of the horizontal line spot in the horizontal direction.

[0063] Fig.17 (c) shows Fig.17 Light intensity distribution of the vertical line light spot in the vertical direction in (a).

[0064] Fig.18 A block diagram of a design device for a metalens for projecting an X-shaped light spot provided in the present application is shown.

[0065] Description of reference numerals:

[0066] 10-sub-region within the coverage area of ​​the X-shaped light spot; 11-first line light spot; 12-second line light spot; 13-overlapping region; 2-superlens; 20-sub-region within the effective area of ​​the superlens; 21-substrate; 22-micro-nano structure; 4-light source. DETAILED DESCRIPTION

[0067] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these example embodiments are provided so that the description of the present application will be more comprehensive and complete and the concepts of the example embodiments will be fully conveyed to those skilled in the art. The accompanying drawings are only schematic illustrations of the present application and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0068] In addition, the described features, structures or characteristics may be combined in one or more example embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the example embodiments of the present application. However, those skilled in the art will appreciate that the technical solution of the present application may be practiced while omitting one or more of the specific details, or other methods, components, steps, etc. may be adopted. In other cases, known structures, methods, implementations or operations are not shown or described in detail to avoid obscuring the present application and making the various aspects of the present application obscure.

[0069] Some of the blocks shown in the accompanying drawings are functional entities that do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0070] Specifically, the related art proposes the following two monolithic metalenses for generating a cross-shaped light spot:

[0071] 1. Partition the effective area of ​​the metalens. For each effective sub-area obtained by partitioning, configure the phase in each effective sub-area to be flip-symmetric about a specific axis. In this way, when the light beam passes through the metalens, it will be given mutually perpendicular optical focal lengths by these effective sub-areas, so the light beams output by each of these effective sub-areas are perpendicular to each other. The light beams output by each of these effective sub-areas are used to project a line light spot, and the line light spots projected by different effective sub-areas are physically independent of each other. Since the light beams output by each of these effective sub-areas are perpendicular to each other, these physically independent line light spots intersect vertically to form a cross-shaped light spot.

[0072] Second, configure two different types of light sources for the metalens so that the two different types of light sources provide the metalens with two types of incident light with different physical properties (for example: two types of incident light with different working bands; two types of incident light with different polarization states). For the micro-nanostructures in the effective area of ​​the metalens, by configuring the structural parameters of the micro-nanostructures, the metalens can reuse the physical properties of the incident light, so that the metalens can simultaneously apply different modulation effects to the two types of incident light - the metalens projects the incident light of the first type of physical properties as a first line light spot, and projects the incident light of the second type of physical properties as a second line light spot, the first line light spot and the second line light spot are perpendicular to each other and physically independent of each other; therefore, when the metalens receives the two types of incident light at the same time, the physically independent first line light spot and the second line light spot intersect perpendicularly, thereby forming a cross-shaped light spot.

[0073] The two types of metalenses proposed in the related art project cross-shaped light spots that are obtained by perpendicularly intersecting multiple physically independent line light spots. When multiple physically independent line light spots intersect, the light intensity in the overlapping area will change suddenly; moreover, if the light beam has a certain coherence, the sudden change in light intensity in the overlapping area is difficult to accurately quantify in advance, which makes it difficult to control the sudden change in light intensity in the overlapping area, and ultimately makes it difficult for the light intensity distribution of the projected cross-shaped light spot to accurately meet the target requirements.

[0074] In order to overcome the above-mentioned defects of the related art, the present application provides a metalens for projecting an X-shaped light spot. The X-shaped light spot projected by the metalens provided in the present application can be a cross-shaped light spot, and the light intensity distribution of the projected X-shaped light spot can accurately meet the target requirements.

[0075] Figure 1 A schematic diagram of an X-shaped light spot in an embodiment of the present application is shown. Figure 2 A schematic diagram of an X-shaped light spot in an embodiment of the present application is shown. Figure 3 A schematic diagram of an X-shaped light spot in an embodiment of the present application is shown. Figure 4 A schematic diagram of an X-shaped light spot in an embodiment of the present application is shown. Figure 5 A schematic diagram of an X-shaped light spot in an embodiment of the present application is shown.

[0076] See also Figures 1 to 5 In the embodiment of the present application, from the perspective of geometric features, the X-shaped light spot can be regarded as including an intersecting first line light spot 11 and a second line light spot 12, and the first line light spot 11 and the second line light spot 12 share an overlapping area 13 due to the intersection.

[0077] like Figures 1 to 4 As shown, in the embodiment of the present application, the first line light spot 11 and the second line light spot 12 can intersect at an angle; at the same time, as Figure 5 As shown, in the embodiment of the present application, the first line light spot 11 and the second line light spot 12 may intersect vertically. When the first line light spot 11 and the second line light spot 12 intersect vertically, the X-shaped light spot is a cross-shaped light spot.

[0078] like Figure 1 , Figure 3 , Figure 4 as well as Figure 5 As shown, in the embodiment of the present application, the line width of the first line spot 11 and the line width of the second line spot 12 can be equal; at the same time, Figure 2 As shown, in the embodiment of the present application, the line width of the first line light spot 11 and the line width of the second line light spot 12 may be different.

[0079] like Figure 1 , Figure 2 , Figure 4 as well as Figure 5 As shown, in the embodiment of the present application, the line length of the first line spot 11 and the line length of the second line spot 12 can be equal; at the same time, Figure 3 As shown, in the embodiment of the present application, the line length of the first line light spot 11 and the line length of the second line light spot 12 may be different.

[0080] like Figure 1 , Figure 2 as well as Figure 5As shown, in the embodiment of the present application, the center positions of the first line light spot 11 and the second line light spot 12 can be both located in the overlapping area 13; at the same time, Figure 3 As shown, in the embodiment of the present application, the center position of only one of the first line light spot 11 and the second line light spot 12 may be located in the overlapping area 13; at the same time, Figure 4 As shown, in the embodiment of the present application, the center positions of the first line light spot 11 and the second line light spot 12 may not be located in the overlapping area 13 .

[0081] However, it should be noted that Figures 1 to 5 The X-shaped light spot is shown as the intersecting first line light spot 11 and the second line light spot 12 only to intuitively demonstrate the geometric features of the X-shaped light spot in the embodiment of the present application; however, this does not mean that the X-shaped light spot in the embodiment of the present application is actually formed by the intersection of the physically independent first line light spot 11 and the second line light spot 12.

[0082] Figure 6 Schematic diagram of the structure of the metalens provided in this application is shown. Figure 6 The metalens 2 provided in the present application includes a substrate 21 and a micro-nano structure 22 disposed on the substrate 21. The micro-nano structure 22 is a subwavelength structure. By controlling the material, cross-sectional shape, cross-sectional size, height, arrangement period and other parameters of the micro-nano structure 22 at various positions on the metalens 2, the micro-nano structure 22 at various positions on the metalens 2 can provide a certain phase for the received light beam, so that the light beam received at various positions on the metalens 2 has a certain phase delay, and then each position on the metalens 2 has a certain phase gradient, thereby exerting a specific modulation effect on the light beam received at each position.

[0083] In the embodiment of the present application, the metalens 2 modulates and outputs the received incident light, and then projects an X-shaped light spot. As described above, from the perspective of geometric features, the X-shaped light spot in the embodiment of the present application includes the intersecting first line light spot 11 and the second line light spot 12; however, this does not mean that the X-shaped light spot in the embodiment of the present application is actually formed by the intersection of the physically independent first line light spot 11 and the second line light spot 12.

[0084] In fact, in the embodiment of the present application, any part of the X-shaped light spot is not formed by the superposition of physically independent light spots from different sources; this is specifically manifested as follows: in the embodiment of the present application, each sub-area within the coverage area of ​​the X-shaped light spot is mapped one-to-one with each sub-area within the effective area of ​​the metalens 2. The effective area of ​​the metalens 2 refers to the area in the metalens 2 where the micro-nano structure 22 is provided to effectively modulate the light beam.

[0085] Figure 7 FIG. 1 shows a schematic diagram of mapping between each sub-region within the coverage area of ​​the X-shaped light spot and each sub-region within the effective area of ​​the metalens 2 in one embodiment of the present application. Figure 7 In the embodiment of the present application, the coverage area of ​​the X-shaped light spot can be divided into a plurality of sub-areas 10, and the effective area of ​​the metalens 2 can be divided into a plurality of sub-areas 20. If a pair of sub-areas 10 and sub-areas 20 have a mapping relationship, and the light spot in the sub-area 10 is just and only projected by the sub-area 20, then the sub-area 10 is only uniquely mapped to the sub-area 20.

[0086] It should be noted that the one-to-one mapping relationship between the sub-regions 10 and the sub-regions 20 depends on the modulation effect provided by the metalens 2 in its effective area for the incident light. Therefore, not all arbitrarily divided sub-regions 10 and arbitrarily divided sub-regions 20 can be arbitrarily mapped one-to-one. To verify the feature that "each sub-region 10 in the coverage area of ​​the X-shaped light spot is mapped one-to-one with each sub-region 20 in the effective area of ​​the metalens 2", the following method can be used:

[0087] By shielding a certain sub-region 20 on the metalens 2, the sub-region 20 cannot receive the light beam, so that the light intensity of a certain sub-region 10 in the X-shaped light spot is significantly reduced compared to before the shielding. Therefore, the shielded sub-region 20 and the sub-region 10 whose light intensity is significantly reduced in response to the shielding have a mutual mapping relationship.

[0088] The effective area of ​​the metalens 2 is divided into N mutually independent and non-overlapping sub-areas 20, and then only one sub-area 20 is shielded each time, so as to determine the N sub-areas 10 to which the N sub-areas 20 are respectively mapped; N is an integer greater than 1. Regardless of the division method used, if the N sub-areas 10 to which the N sub-areas 20 are respectively mapped are also independent and non-overlapping, and these N sub-areas 10 just constitute the coverage area of ​​the X-shaped light spot, it means that each sub-area 10 in the coverage area of ​​the X-shaped light spot is mapped one by one with each sub-area 20 in the effective area of ​​the metalens 2.

[0089] On the contrary, if there is at least one division method such that N mutually independent and non-overlapping sub-regions 20 are mapped to N sub-regions 10, but there is at least one pair of overlapping sub-regions 10 among the N sub-regions 10, it means that the sub-regions 10 in the coverage area of ​​the X-shaped light spot are not mapped one-to-one with the sub-regions 10 in the effective area of ​​the metalens 2.

[0090] It should be noted that if a certain sub-region 10 and a certain sub-region 20 are uniquely mapped to each other, then ideally, after the sub-region 20 is shielded, the light intensity in the sub-region 10 will be reduced to 0. However, in practice, when the sub-region 20 is shielded, it is inevitable to use a shielding element with a certain size, and the use of the shielding element will lead to the generation of edge diffraction effect, which will make it difficult for the light intensity in the sub-region 10 to be completely reduced to 0. Therefore, when the sub-region 20 is shielded and the sub-region 10 whose light intensity is significantly reduced due to the shielding is judged, the existence of the edge diffraction effect needs to be considered.

[0091] In the embodiment of the present application, each sub-region 10 in the coverage area of ​​the X-shaped light spot is mapped one-to-one with each sub-region 20 in the effective area of ​​the metalens 2, that is, any point in the X-shaped light spot is not formed by the superposition of physically independent light spots from different sources. Therefore, the light intensity of any point in the X-shaped light spot will not produce uncontrollable mutations. Therefore, the light intensity distribution of the X-shaped light spot projected by the metalens 2 provided in the present application can accurately meet the target requirements.

[0092] The present application also provides a design method for a superlens 2 for projecting an X-shaped light spot. Figure 8 FIG. 1 is a flow chart showing a design method of a metalens 2 for projecting an X-shaped light spot provided by the present application. Figure 8 , the method provided in this application includes:

[0093] Step S310, based on the first target light intensity distribution of the first line light spot 11, obtaining a first phase for the metalens 2 to project the first line light spot 11, and based on the second target light intensity distribution of the second line light spot 12, obtaining a second phase for the metalens 2 to project the second line light spot 12;

[0094] Step S320, based on the first phase and the second phase, simulating the process of the metalens 2 projecting the X-shaped light spot to obtain a simulated light intensity distribution of the X-shaped light spot;

[0095] Step S330: If the simulated light intensity distribution does not meet the target requirement, then collaboratively optimize the first target light intensity distribution and the second target light intensity distribution at least in the overlapping area, and update the first phase, the second phase and the simulated light intensity distribution based on the optimized target light intensity distribution until the simulated light intensity distribution meets the target requirement, thereby obtaining the first phase and the second phase that meet the target requirement;

[0096] Step S340: constructing a metalens 2 for projecting an X-shaped light spot based on the first phase and the second phase that meet the target requirements.

[0097] Specifically, in order to construct a metalens 2 for projecting an X-shaped light spot, it is necessary to first design a target phase of the metalens 2. Under the effect of the designed target phase, the metalens 2 can modulate the received incident light into an output light beam with specific optical properties; as the output light beam propagates, the output light beam can be projected on a target plane (e.g., the ground, a wall, etc.) to obtain an X-shaped light spot that meets the target requirements.

[0098] It should be noted that the target demand for the X-shaped light spot is mainly used to describe the target light intensity distribution of the X-shaped light spot. The target light intensity distribution of the X-shaped light spot can be further described by the following two dimensions: 1. The geometric characteristics of the target light intensity distribution of the X-shaped light spot, such as: the angle between the first line light spot 11 and the second line light spot 12, the position of the overlapping area 13 on the first line light spot 11 and the second line light spot 12, the line length and line width of the first line light spot 11, the line length and line width of the second line light spot 12, etc.; 2. The uniformity characteristics of the target light intensity distribution of the X-shaped light spot, such as: the uniformity of the light intensity distribution of the first line light spot 11 along its line length direction, the uniformity of the light intensity distribution of the second line light spot 12 along its line length direction, etc.

[0099] Since in most application scenarios, the X-shaped light spot is usually required to have a uniform light intensity distribution as much as possible, for the purpose of ease of description, when introducing the implementation details of the embodiments of the present application, "the target light intensity distribution of the X-shaped light spot is uniform" is used as an example; however, this does not mean that the target light intensity distribution of the X-shaped light spot in the embodiments of the present application must be uniform, nor does it mean that the metalens 2 designed in the present application can only be used to generate an X-shaped light spot with a uniform light intensity distribution.

[0100] Next, a detailed description is given of how to design and obtain the target phase of the metalens 2 in the embodiment of the present application, and how to construct the metalens 2 accordingly.

[0101] In the embodiment of the present application, the first phase and the second phase are decomposed from the target phase of the metalens 2; wherein the first phase is used to project the first line spot 11, and the second phase is used to project the second line spot 12. Moreover, both the first phase and the second phase are effective in the entire effective area of ​​the metalens 2. That is, if the second phase is removed from the target phase of the metalens 2, the entire effective area of ​​the metalens 2 modulates the received light beam together, and then projects the first line spot 11; if the first phase is removed from the target phase of the metalens 2, the entire effective area of ​​the metalens 2 modulates the received light beam together, and then projects the second line spot 12.

[0102] Since the first phase is used to project the first line light spot 11, after determining the first target light intensity distribution of the first line light spot 11, the first target light intensity distribution can be used as the modulation output target of the metalens 2 to design the first phase. Similarly, after determining the second target light intensity distribution of the second line light spot 12, the second target light intensity distribution can be used as the modulation output target of the metalens 2 to design the second phase.

[0103] The first target light intensity distribution of the first line light spot 11 and the second target light intensity distribution of the second line light spot 12 can be obtained by random initialization, or the target light intensity distribution of the X-shaped light spot can be determined according to the target requirements for the X-shaped light spot, and then the first target light intensity distribution and the second target light intensity distribution can be initialized according to the target light intensity distribution of the X-shaped light spot. Initialization according to the target light intensity distribution of the X-shaped light spot can make the first target light intensity distribution and the second target light intensity distribution have a good initial state.

[0104] After obtaining the first phase and the second phase, the first phase is superimposed on the second phase, and then the process of the metalens 2 projecting an X-shaped light spot based on the superimposed phase is simulated to determine the intensity distribution of the X-shaped light spot projected by the light beam output by the metalens 2 when the metalens 2 modulates the received light beam based on the superimposed phase, that is, the simulated light intensity distribution of the X-shaped light spot.

[0105] Since the superposition of the first phase and the second phase can be regarded as the superposition of the first line light spot 11 and the second line light spot 12, and the light intensity in the overlapping area 13 will produce changes that are difficult to accurately quantitatively measure in advance, the simulated light intensity distribution obtained initially is usually difficult to meet the target requirements.

[0106] It is understandable that if the simulated light intensity distribution does not meet the target requirement, it means that the corresponding first phase and second phase do not meet the target requirement. Therefore, if the simulated light intensity distribution does not meet the target requirement, the first phase and the second phase need to be optimized to obtain the first phase and the second phase that meet the target requirement.

[0107] Considering that if the first phase and the second phase are optimized directly, it will be similar to searching and trial-and-error in a black box manner, and the optimization efficiency is low, therefore, in an embodiment of the present application, the first target light intensity distribution and the second target light intensity distribution are optimized, and then the first phase and the second phase are indirectly optimized, thereby improving the optimization efficiency of the phase under the guidance of the first target light intensity distribution and the second target light intensity distribution.

[0108] Furthermore, since the first target light intensity distribution and the second target light intensity distribution in the overlapping region 13 affect each other, the optimization of the first target light intensity distribution and the optimization of the second target light intensity distribution in the overlapping region 13 will restrict each other. Therefore, in the embodiment of the present application, at least in the overlapping region 13, the first target light intensity distribution and the second target light intensity distribution are collaboratively optimized, thereby improving the optimization efficiency of the target light intensity distribution, and further improving the optimization efficiency of the phase. Specifically, a particle swarm optimization algorithm, an ant colony optimization algorithm, etc. can be used for collaborative optimization.

[0109] After the optimization of the first target light intensity distribution and the second target light intensity distribution is completed, the optimized first target light intensity distribution and the optimized second target light intensity distribution are obtained. Similarly, the first phase is obtained according to the first target light intensity distribution, and the first phase can be updated according to the optimized first target light intensity distribution; similarly, the second phase is obtained according to the second target light intensity distribution, and the second phase can be updated according to the optimized second target light intensity distribution. Then, the updated first phase is superimposed with the updated second phase, and the process of the metalens 2 projecting the X-shaped light spot based on the superimposed phase is simulated again, so as to update the simulated light intensity distribution of the X-shaped light spot.

[0110] This process is repeated over and over again until the simulated light intensity distribution meets the target requirement; at this time, it means that the corresponding first phase and second phase also meet the target requirement, and thus the first phase and second phase that meet the target requirement are obtained.

[0111] The first phase and the second phase that meet the target requirement are superimposed to obtain a superimposed phase that meets the target requirement, and then based on the superimposed phase that meets the target requirement, a target phase of the metalens 2 that meets the target requirement is obtained.

[0112] Specifically, if the incident light received by the metalens 2 is not collimated light, and when designing the first phase and the second phase, the incident angle of the light beam at each position on the metalens 2 is assumed to be 0°, then during simulation, it is necessary to continue to superimpose the collimated phase for collimating the incident light on the basis of the phase corresponding to the superposition of the first phase and the second phase, so as to obtain the target phase of the metalens 2 used for simulation; in this case, on the basis of the phase corresponding to the superposition of the first phase and the second phase that meets the target requirements, the collimated phase is continued to be superimposed to obtain the target phase of the metalens 2 that meets the target requirements.

[0113] If the incident light received by the metalens 2 is collimated light, or the first phase and the second phase have been designed with consideration of the actual light beam incident angles at various positions on the metalens 2, then during simulation, the phase obtained by superimposing the first phase and the second phase can be directly used as the target phase of the metalens 2 for simulation; in this case, the phase obtained by superimposing the first phase and the second phase that meet the target requirements can be directly used as the target phase of the metalens 2 that meets the target requirements.

[0114] After obtaining the target phase of the metalens 2 that meets the target requirements, the phase that the micro-nano structures at various positions on the metalens 2 should provide can be determined. Therefore, the micro-nano structure database is traversed to select micro-nano structures that can provide corresponding phases for various positions on the metalens 2, thereby determining the micro-nano structures that should be arranged at various positions on the metalens 2. Then, the determined micro-nano structures are arranged at various positions on the metalens 2, that is, a metalens 2 for projecting an X-shaped light spot is constructed, and the light intensity distribution of the X-shaped light spot projected by the metalens 2 meets the target requirements. Among them, the micro-nano structure database at least describes the phase provided by the micro-nano structure with specific structural parameters for the light beam in a specific working band.

[0115] In the embodiment of the present application, although the first phase for projecting the first line light spot 11 and the second phase for projecting the second line light spot 12 are designed separately when designing the phase, the first phase and the second phase are finally superimposed together and take effect on the metalens 2, so the first line light spot 11 and the second line light spot 12 are actually modulated as a whole, rather than physically independent of each other. Therefore, the metalens 2 designed by the design method provided in the present application can accurately meet the target requirements by projecting the light intensity distribution of the X-shaped light spot.

[0116] In addition, in the embodiment of the present application, by optimizing the first target light intensity distribution and the second target light intensity distribution, the first phase and the second phase are indirectly optimized, thereby improving the optimization efficiency of the phase; and by collaboratively optimizing the first target light intensity distribution and the second target light intensity distribution at least in the overlapping area 13, the optimization efficiency of the target light intensity distribution is improved, thereby further improving the optimization efficiency of the phase. By improving the optimization efficiency of the phase, the embodiment of the present application improves the design efficiency of the metalens 2.

[0117] It should be noted that a phase recovery algorithm can be used to obtain the phase of the metalens 2, wherein the phase recovery algorithm includes the GS (Gerchberg-Saxton) algorithm, the Yang-Gu algorithm, etc. However, if a phase recovery algorithm is used to obtain the phase of the metalens 2, when the incident light has a strong coherence, the metalens 2 obtained by actual processing modulates the incident light according to the designed phase, and the light spot obtained by actual projection includes not only the X-shaped light spot, but also very likely to have redundant 0th order diffraction light spots. If the 0th order diffraction light spot is to be eliminated, very high requirements will be placed on the processing technology of the metalens 2. Therefore, in the embodiment of the present application, a phase recovery algorithm is not used to obtain the phase of the metalens 2. Specifically, in the embodiment of the present application, the phase of the metalens 2 is obtained by energy mapping.

[0118] According to the law of conservation of energy, if the energy loss generated during the propagation of the light beam is ignored, the total energy of the light intensity distribution of the incident light is equal to the total energy of the light intensity distribution of the light spot projected by the superlens 2.

[0119] Therefore, according to the light intensity distribution of the incident light, the light energy received by each position on the metalens 2 is determined, and according to the first target light intensity distribution, the light energy of each position on the first line spot 11 is determined. Then, each position on the metalens 2 is mapped one by one with each position on the first line spot 11; a pair of positions with a mapping relationship have equal light energies. Therefore, according to the mapping result, the light beam exit angle at each position on the metalens 2 for projecting the first line spot 11 can be determined. Then, the light beam exit angle at each position on the metalens 2 is combined with the light beam incident angle, and the generalized Snell's law is applied to calculate the phase at each position on the metalens 2 for projecting the first line spot 11, that is, the first phase is obtained.

[0120] Similarly, the implementation details of obtaining the second phase by means of energy mapping are not repeated.

[0121] It should also be noted that if, during the energy mapping process, the overall light intensity distribution of the X-shaped light spot is directly used as the target light intensity distribution as the output target, and then the phase of the metalens 2 is directly designed as a whole, when the incident light has strong coherence, after the metalens 2 modulates the incident light according to the designed phase, dark spots are likely to appear in the projected X-shaped light spot.

[0122] For example, the X-shaped light spot is taken as a whole, and energy mapping is performed along the first line light spot 11, and energy mapping is performed along the second line light spot 12. It can be understood that when the X-shaped light spot is taken as a whole, the first line light spot 11 will separate the second line light spot 12 into two broken parts, or the second line light spot 12 will separate the first line light spot 11 into two broken parts. Therefore, the energy mapping process of one of the first line light spot 11 and the second line light spot 12 is discontinuous; and this situation will cause the X-shaped light spot obtained by projection to be prone to dark spots after the metalens 2 modulates the incident light according to the designed phase when the incident light has strong coherence.

[0123] Therefore, in the embodiment of the present application, when the phase of the metalens 2 is obtained by adopting the energy mapping method, the first target light intensity distribution of the first line light spot 11 and the second target light intensity distribution of the second line light spot 12 are respectively used as output targets, so as to respectively design the first phase and the second phase, so that when the incident light has strong coherence, after the metalens 2 modulates the incident light according to the designed phase, the X-shaped light spot obtained by projection is not prone to dark spots.

[0124] In one embodiment, if the simulated light intensity distribution does not meet the target requirement, the first target light intensity distribution and the second target light intensity distribution are collaboratively optimized within the overlapping area 13, and at the same time, the first target light intensity distribution and the second target light intensity distribution outside the overlapping area 13 are collaboratively optimized.

[0125] In one embodiment, the method provided by the present application further includes:

[0126] If the simulated light intensity distribution does not meet the target requirement, the first target light intensity distribution and the second target light intensity distribution are subjected to distributed optimization outside the overlapping area 13 .

[0127] In this embodiment, if the simulated light intensity distribution does not meet the target requirement, the first target light intensity distribution and the second target light intensity distribution are collaboratively optimized within the overlapping area 13, and the first target light intensity distribution and the second target light intensity distribution are distributedly optimized outside the overlapping area 13.

[0128] Since the first target light intensity distribution and the second target light intensity distribution can be regarded as independent of each other outside the overlapping area 13, there is no need to perform collaborative optimization on the two outside the overlapping area 13; and the more optimization objects involved in the collaborative optimization, the higher the complexity of the optimization process. Therefore, in this embodiment, distributed optimization is performed on the two outside the overlapping area 13 to reduce the complexity of the optimization process.

[0129] In one embodiment, in the overlapping area 13, the first target light intensity distribution and the second target light intensity distribution are collaboratively optimized, including:

[0130] In the overlapping region 13 , the first target light intensity distribution and the second target light intensity distribution are first weakened, and then the weakened first target light intensity distribution and the second target light intensity distribution are collaboratively optimized.

[0131] In this embodiment, the light intensity is actively weakened in the overlapping area 13 , and then the two light intensity weakened light intensity are coordinated optimized in the overlapping area 13 .

[0132] Specifically, when the first target light intensity distribution and the second target light intensity distribution are initialized, the light intensities of the two in the overlapping area 13 are usually not specially processed; therefore, after the first phase and the second phase obtained for the first time are superimposed and simulated accordingly, the light intensity of the simulated light intensity distribution of the X-shaped light spot in the overlapping area 13 will be significantly stronger than the light intensity specified by the target requirement in the overlapping area 13.

[0133] Therefore, in this embodiment, after the simulated light intensity distribution is obtained through the initial simulation and it is confirmed that the simulated light intensity distribution does not meet the target requirements, and before the first target light intensity distribution and the second target light intensity distribution are optimized in the overlapping area 13, the light intensity of the two is actively weakened in the overlapping area 13, and then the two after the weakened light intensity are collaboratively optimized in the overlapping area 13.

[0134] If the light intensity is not actively weakened in the overlapping area 13 during each iterative optimization, and only collaborative optimization is performed, then after multiple iterative optimizations, an optimization result that meets the target requirements can be obtained. However, in this case, the light intensity can only be passively weakened by relying on the collaborative optimization algorithm, which will increase the data processing volume of the iterative optimization, resulting in low efficiency of the iterative optimization. Therefore, in this embodiment, the light intensity is actively weakened in the overlapping area 13 first, and then the two after the light intensity is weakened are collaboratively optimized in the overlapping area 13, which is conducive to improving the efficiency of iterative optimization.

[0135] It should be noted that, in the process of multiple iterations of optimization, the light intensity may be actively weakened in the overlapping area 13 only in a certain iteration of optimization. Preferably, the light intensity is actively weakened in the overlapping area 13 only in the process of the first iteration of optimization.

[0136] In one embodiment, in the overlapping area 13, the first target light intensity distribution and the second target light intensity distribution are weakened, including:

[0137] Based on the coherence of the incident light, a multiplication factor of the light intensity after superposition in the overlapping region 13 is determined compared to the light intensity without superposition;

[0138] Based on the multiplication factor, the light intensity of the first target light intensity distribution and the second target light intensity distribution are weakened in the overlapping area 13 .

[0139] In this embodiment, the multiplication factor is used to describe the multiple of the light intensity after superposition in the overlapping area 13 relative to the light intensity without superposition, and the multiplication factor is closely related to the coherence of the incident light. Specifically, if the incident light is incoherent light, the light intensity after superposition in the overlapping area 13 is twice the light intensity without superposition, so the multiplication factor of the light intensity after superposition in the overlapping area 13 is 2 compared to the light intensity without superposition. If the incident light is coherent light, the light intensity after superposition in the overlapping area 13 is 4 times the light intensity without superposition, so the multiplication factor of the light intensity after superposition in the overlapping area 13 is 4 compared to the light intensity without superposition. If the incident light is partially coherent light, the multiplication factor of the light intensity after superposition in the overlapping area 13 is between 2 and 4 compared to the light intensity without superposition, and the specific multiplication factor can be determined by optical analysis simulation.

[0140] After the multiplication factor is determined, the first target light intensity distribution and the second target light intensity distribution can be weakened based on the multiplication factor in the overlapping area 13. Specifically, if the multiplication factor is 2, the first target light intensity distribution and the second target light intensity distribution are weakened based on 1 / 2 of their respective light intensities in the overlapping area 13. Similarly, if the multiplication factor is 4, the first target light intensity distribution and the second target light intensity distribution are weakened based on 1 / 4 of their respective light intensities in the overlapping area 13.

[0141] In this embodiment, by first determining the multiplication factor based on the coherence of the incident light and then weakening the light intensity based on the multiplication factor, the rationality of the light intensity weakening can be ensured and the degree of light intensity weakening that is too small or too large can be avoided.

[0142] In one embodiment, the light intensity of the first target light intensity distribution and the second target light intensity distribution is weakened, including:

[0143] In the overlapping region 13, a first minimum light intensity that the first target light intensity distribution should reach and a second minimum light intensity that the second target light intensity distribution should reach are determined after the light intensity is weakened;

[0144] In the overlapping area 13, the first Gaussian function with coordinate shift is used to describe the first target light intensity distribution after the light intensity is weakened; the light intensity described by the first Gaussian function with coordinate shift at the center position of the overlapping area matches the first minimum light intensity; the light intensity described by the first Gaussian function with unshifted coordinate at the center position of the overlapping area matches the maximum light intensity of the first target light intensity distribution;

[0145] In the overlapping area 13, a second Gaussian function with coordinate shifting is used to describe the second target light intensity distribution after the light intensity is weakened; the light intensity described by the second Gaussian function with coordinate shifting at the center position of the overlapping area matches the second minimum light intensity; the light intensity described by the second Gaussian function with unshifted coordinates at the center position of the overlapping area matches the maximum light intensity of the second target light intensity distribution.

[0146] In this embodiment, in the overlapping area 13, a Gaussian function is used to describe the first target light intensity distribution and the second target light intensity distribution, and the first target light intensity distribution and the second target light intensity distribution are weakened in the overlapping area 13 by means of coordinate shifting of the Gaussian function. This embodiment is mainly used to generate an X-shaped light spot with uniform target light intensity distribution.

[0147] Specifically, Fig. 9 A schematic diagram showing, in one embodiment of the present application, a first target light intensity distribution before light intensity attenuation is described using a first Gaussian function whose coordinates are not shifted in the overlapping area 13 . Fig.10 A schematic diagram showing, in one embodiment of the present application, a first Gaussian function with coordinate shift is used in the overlapping area 13 to describe the first target light intensity distribution after the light intensity is weakened.

[0148] See also Fig. 9 and Fig.10 , wherein the horizontal axis is the x-axis, representing the line length direction of the first line light spot 11, the origin of the horizontal axis represents the center position of the overlapping area 13 in the line length direction of the first line light spot 11, and [x1, x2] represents the coverage range of the overlapping area 13 in the line length direction of the first line light spot 11; the vertical axis represents the normalized light intensity. Fig. 9 as well as Fig.10 The curves shown are all first Gaussian functions. The solid line part of the curve represents the effective area of ​​the first Gaussian function, and the dotted line part of the curve represents the ineffective area of ​​the first Gaussian function. Since the coverage range of the overlapping area 13 in the line length direction of the first line spot 11 is [x1, x2], the first Gaussian function is actually only effective within the range of [x1, x2].

[0149] See also Fig. 9 , the value of the first Gaussian function whose coordinates are not offset at the center position of the overlapping area 13 is the maximum value of the first Gaussian function; therefore, the light intensity described by the first Gaussian function whose coordinates are not offset at the center position of the overlapping area 13 is the maximum light intensity of the first target light intensity distribution.

[0150] In the overlapping region 13, determining a first minimum light intensity that the first target light intensity distribution should reach after the light intensity is weakened; Fig. 9 In the figure, the light intensity described by the two px points symmetrical about the vertical axis is the first minimum light intensity.

[0151] Then Fig. 9 The first Gaussian function in is translated along the positive direction of the horizontal axis until the px point originally located on the negative semi-axis side of the horizontal axis is located on the vertical axis; symmetrically, Fig. 9 The first Gaussian function in is translated along the negative direction of the horizontal axis until the px point originally located on the positive semi-axis side of the horizontal axis is located on the vertical axis. In this way, by symmetrically translating the first Gaussian function, we get Fig.10 The first Gaussian function of the coordinate shift shown. Fig.10 As shown, the light intensity described by the first Gaussian function of coordinate offset at the center position of the overlapping area 13 is the first minimum light intensity, and the light intensity described by the first Gaussian function of coordinate offset gradually increases from the center position of the overlapping area 13 to the edge position of the overlapping area 13 (the position corresponding to x1, or the position corresponding to x2).

[0152] Fig.11 A schematic diagram showing, in one embodiment of the present application, a second target light intensity distribution before light intensity attenuation is described in the overlapping region 13 using a second Gaussian function whose coordinates are not shifted. Fig.12 A schematic diagram showing, in one embodiment of the present application, a second Gaussian function with coordinate shift is used in the overlapping area 13 to describe the second target light intensity distribution after the light intensity is weakened.

[0153] See also Fig.11 and Fig.12 , wherein the horizontal axis is the y-axis (the x-axis and the y-axis may be perpendicular to each other or inclined to each other), representing the line length direction of the second line light spot 11, the origin of the horizontal axis represents the center position of the overlapping area 13 in the line length direction of the second line light spot 11, and [y1, y2] represents the coverage range of the overlapping area 13 in the line length direction of the second line light spot 11; the vertical axis represents the normalized light intensity. Fig.11 as well as Fig.12 The curves shown are all second Gaussian functions. The solid line part of the curve represents the effective area of ​​the second Gaussian function, and the dotted line part of the curve represents the ineffective area of ​​the second Gaussian function. Since the coverage range of the overlapping area 13 in the line length direction of the second line spot 11 is [y1, y2], the second Gaussian function is actually only effective within the range of [y1, y2].

[0154] See also Fig.11 , the value of the second Gaussian function whose coordinates are not offset at the center position of the overlapping area 13 is the maximum value of the second Gaussian function; therefore, the light intensity described by the second Gaussian function whose coordinates are not offset at the center position of the overlapping area 13 is the maximum light intensity of the second target light intensity distribution.

[0155] In the overlapping region 13, determining a second minimum light intensity that the second target light intensity distribution should reach after the light intensity is weakened; Fig.11 In the figure, the light intensity described by the two points py that are symmetrical about the longitudinal axis is the second minimum light intensity.

[0156] Then Fig.11 The second Gaussian function in is translated along the positive direction of the horizontal axis until the point py, which was originally located on the negative semi-axis side of the horizontal axis, is located on the vertical axis; symmetrically, Fig.11 The second Gaussian function in is translated along the negative direction of the horizontal axis until the point py, which was originally located on the positive semi-axis side of the horizontal axis, is located on the vertical axis. In this way, by symmetrically translating the second Gaussian function, we get Fig.12 The second Gaussian function of the coordinate shift shown. Fig.12 As shown, the light intensity described by the second Gaussian function of coordinate offset at the center position of the overlapping area 13 is the second minimum light intensity, and the light intensity described by the second Gaussian function of coordinate offset gradually increases from the center position of the overlapping area 13 to the edge position of the overlapping area 13 (the position corresponding to y1, or the position corresponding to y2).

[0157] The characteristics of the Gaussian function are conducive to optimizing and obtaining a uniform target light intensity distribution. Therefore, when the target light intensity distribution of the X-shaped light spot has a high requirement for uniformity, in the overlapping area 13, the Gaussian function is used to describe the first target light intensity distribution and the second target light intensity distribution, which is conducive to quickly optimizing and obtaining an X-shaped light spot with a uniform target light intensity distribution. At the same time, the first target light intensity distribution and the second target light intensity distribution need to be actively weakened in the overlapping area 13. If the weakening process destroys the characteristics of the Gaussian function of the first target light intensity distribution and the second target light intensity distribution, it will be difficult to maintain the contribution of the Gaussian function to the optimization. However, coordinate shifting of the Gaussian function does not destroy the characteristics of the Gaussian function. Therefore, in this embodiment, the method of coordinate shifting of the Gaussian function is adopted to weaken the light intensity of the first target light intensity distribution and the second target light intensity distribution in the overlapping area 13, so as to continue to maintain the contribution of the Gaussian function to the optimization.

[0158] It should be noted that when a high uniformity requirement is imposed on the target light intensity distribution of the X-shaped light spot, in order to improve the utilization rate of light energy and avoid physical damage to the metalens 2 caused by excessive local light intensity on the metalens 2, the target light intensity distribution of the X-shaped light spot under ideal conditions should not be described by the fundamental mode Gaussian function.

[0159] Therefore, in one embodiment, the first target light intensity distribution and the second target light intensity distribution are both described and optimized using a high-order modulus Gaussian function, so that the X-shaped light spot projected by the metalens 2 has a highly uniform light intensity distribution and maintains a high light energy utilization rate, while avoiding physical damage to the metalens 2 due to excessive local light intensity.

[0160] In one embodiment, the high-order mode Gaussian function used to describe and optimize the first target light intensity distribution and the second target light intensity distribution includes: a super Gaussian function, a flat-top Gaussian function, and a super Lorentzian function.

[0161] Exemplarily, the first target light intensity distribution or the second target light intensity distribution described by the super Gaussian function can be expressed as:

[0162]

[0163] Among them, I SG (R) is the target light intensity distribution described, R is the radial distance of each position relative to the center position in the target light intensity distribution described, and I SG,0 is the normalized light intensity coefficient, R SG is the beam waist radius corresponding to the target light intensity distribution described, p When the first target light intensity distribution is described by a super-Gaussian function, optimizing the first target light intensity distribution is to optimize the order. p Similarly, when the second target light intensity distribution is described by a super-Gaussian function, optimizing the second target light intensity distribution is to optimize the order p .

[0164] The present application also provides an emission module for projecting an X-shaped light spot. Fig.13 Schematic diagram of the architecture of the transmitting module provided in the embodiment of the present application is shown. Fig.13 The emission module provided in the present application includes: a light source 4; and a super lens 2 as provided in any of the above embodiments.

[0165] In the embodiment of the present application, the light source 4 can be a single point light source or an array light source. The superlens 2 is arranged on the light output side of the light source 4, so the superlens 2 receives the light beam emitted by the light source 4, modulates the light beam emitted by the light source 4, and then outputs it, and finally projects it as an X-shaped light spot.

[0166] The light beam emitted by the light source 4 is generally a divergent light with a certain divergence angle. Therefore, when no other optical element with a modulation function is provided between the light source 4 and the metalens 2, the light beam emitted by the light source 4 received by the metalens 2 is a divergent light with a certain divergence angle; when a collimating element for collimating the light beam is provided between the light source 4 and the metalens 2, the light beam emitted by the light source 4 received by the metalens 2 is a collimated light that is approximately parallel light.

[0167] With reference to the description of the structure of the metalens 2 and the design method thereof in the above embodiment, the implementation details of the structure or design method of the metalens 2 will not be repeated here.

[0168] Fig.14(a) shows the target light intensity distribution of a cross-shaped light spot in one embodiment of the present application. Fig.14 (b) shows Fig.14 (a) shows the target light intensity distribution of the horizontal line spot in the horizontal direction. Fig.14 (c) shows Fig.14 Target light intensity distribution of the vertical line light spot in the vertical direction in (a).

[0169] Fig.15 (a) shows a comparative example, according to Fig.14 The target light intensity distribution of the cross-shaped light spot shown in (a) is obtained by adopting the design method provided by the relevant technology to design the light intensity distribution of the cross-shaped light spot projected by the super lens 2. Fig.15 (b) shows Fig.15 (a) shows the light intensity distribution of the horizontal line spot in the horizontal direction. Fig.15 (c) shows Fig.15 Light intensity distribution of the vertical line light spot in the vertical direction in (a).

[0170] Fig.16 (a) shows an embodiment of the present application, according to Fig.14 The target light intensity distribution of the cross-shaped light spot shown in (a) is obtained by weakening the target light intensity distribution of the horizontal line light spot in the horizontal direction and the target light intensity distribution of the vertical line light spot in the vertical direction in the overlapping area, thereby obtaining the light intensity distribution of the cross-shaped light spot used as the iterative optimization target. Fig.16 (b) shows Fig.16 (a) shows the light intensity distribution of the horizontal line spot in the horizontal direction. Fig.16 (c) shows Fig.16 Light intensity distribution of the vertical line light spot in the vertical direction in (a).

[0171] Fig.17 (a) shows an embodiment of the present application, according to Fig.14 The target light intensity distribution of the cross-shaped light spot shown in (a) adopts the design method provided by this application and is based on Fig.16 After iterative optimization of the weakened light intensity distribution shown in (a), the light intensity distribution of the cross-shaped light spot projected by the finally designed superlens 2 is obtained. Fig.17 (b) shows Fig.17 (a) shows the light intensity distribution of the horizontal line spot in the horizontal direction. Fig.17 (c) shows Fig.17 Light intensity distribution of the vertical line light spot in the vertical direction in (a).

[0172] See also Fig.14In one embodiment, the light beam received by the metalens 2 is a collimated coherent Gaussian light with a central wavelength of 650nm and a beam waist radius of 0.6mm. The light intensity distribution of the cross-shaped light spot projected by the metalens 2 is highly uniform (the light intensity distribution of the horizontal light spot in the horizontal direction is highly uniform, and the light intensity distribution of the vertical light spot in the vertical direction is also highly uniform), and the illumination coverage angle corresponding to the horizontal light spot should reach 80°, and the illumination coverage angle corresponding to the vertical light spot should also reach 80°.

[0173] See also Fig.15 In the comparative example, the design method provided by the relevant technology is adopted, based solely on Fig.14 The target light intensity distribution shown in (b) is iterated to obtain the phase for projecting the horizontal line spot alone, and based on Fig.14 The target light intensity distribution shown in (c) is iterated to obtain the phase for projecting the vertical line spot. Then the two phases are superimposed to design the corresponding metalens. The metalens designed in this way projects Fig.15 The cross-shaped spot shown in (a).

[0174] Depend on Fig.15 (a) Fig.15 (b) and Fig.15 (c) It can be seen that, in the cross-shaped light spot projected by the metalens designed by the design method provided by the relevant technology, the light intensity distribution of the horizontal line light spot in the horizontal direction is significantly prominent in the overlapping area, which does not meet the requirement of high uniformity; similarly, the light intensity distribution of the vertical line light spot in the vertical direction is also significantly prominent in the overlapping area, which also does not meet the requirement of high uniformity.

[0175] In order to improve the uniformity of the light intensity distribution of the cross-shaped light spot, see Fig.16 In one embodiment, in the overlapping area, the target light intensity distribution of the horizontal line light spot in the horizontal direction and the target light intensity distribution of the vertical line light spot in the vertical direction are both weakened to obtain Fig.16 The cross-shaped spot shown in (a) is then based on Fig.16 The target light intensity distribution shown in (b) is obtained by iterative design to obtain the first phase for projecting the horizontal line spot that meets the target requirements, and based on Fig.16The target light intensity distribution shown in (c) is iteratively designed to obtain the second phase for projecting the vertical line light spot that meets the target requirements; when iteratively designing the first phase and the second phase, the target light intensity distribution of the horizontal line light spot and the target light intensity distribution of the vertical line light spot are collaboratively optimized in the overlapping area, and the two are distributedly optimized outside the overlapping area. Then the first phase and the second phase that meet the target requirements are superimposed to design the corresponding metalens 2. The metalens 2 designed by the design method provided in this application projects Fig.17 The cross-shaped spot shown in (a).

[0176] Depend on Fig.17 (a) Fig.17 (b) and Fig.17 It can be seen from (c) that, in the cross-shaped light spot projected by the metalens 2 designed by the design method provided in the present application, the light intensity distribution uniformity of the horizontal light spot in the horizontal direction is relatively high. Similarly, the light intensity distribution uniformity of the vertical light spot in the vertical direction is also relatively high.

[0177] The present application also provides a design device for a superlens for projecting an X-shaped light spot. Fig.18 A block diagram of a design device for a metalens for projecting an X-shaped light spot provided in the present application is shown.

[0178] See also Fig.18 , the device provided in this application includes:

[0179] The phase acquisition module 510 is configured to acquire a first phase for the first line light spot to be projected by the metalens based on a first target light intensity distribution of the first line light spot, and acquire a second phase for the second line light spot to be projected by the metalens based on a second target light intensity distribution of the second line light spot;

[0180] The simulation module 520 is configured to simulate the process of the metalens projecting the X-shaped light spot based on the first phase and the second phase to obtain a simulated light intensity distribution of the X-shaped light spot;

[0181] The optimization module 530 is configured to collaboratively optimize the first target light intensity distribution and the second target light intensity distribution at least in the overlapping area if the simulated light intensity distribution does not meet the target requirement, and update the first phase, the second phase and the simulated light intensity distribution based on the optimized target light intensity distribution until the simulated light intensity distribution meets the target requirement, thereby obtaining the first phase and the second phase that meet the target requirement;

[0182] The construction module 540 is configured to construct a metalens for projecting an X-shaped light spot based on the first phase and the second phase that meet the target requirements.

[0183] In an exemplary embodiment of the present application, the device provided by the present application is configured as follows:

[0184] If the simulated light intensity distribution does not meet the target requirement, the first target light intensity distribution and the second target light intensity are distributedly optimized outside the overlapping area.

[0185] In an exemplary embodiment of the present application, the optimization module 530 is configured as follows:

[0186] In the overlapping area, the first target light intensity distribution and the second target light intensity distribution are first weakened, and then the weakened first target light intensity distribution and the second target light intensity distribution are collaboratively optimized.

[0187] In an exemplary embodiment of the present application, the optimization module 530 is configured as follows:

[0188] Based on the coherence of the incident light, a multiplication factor of the light intensity after superposition in the overlapping area compared to the light intensity without superposition is determined;

[0189] Based on the multiplication factor, the light intensity of the first target light intensity distribution and the second target light intensity distribution are weakened in the overlapping area.

[0190] In an exemplary embodiment of the present application, the optimization module 530 is configured as follows:

[0191] In the overlapping region, determining a first minimum light intensity that the first target light intensity distribution should reach after the light intensity is weakened, and a second minimum light intensity that the second target light intensity distribution should reach;

[0192] In the overlapping area, the first Gaussian function with coordinate shift is used to describe the first target light intensity distribution after the light intensity is weakened; the light intensity described by the first Gaussian function with coordinate shift at the center position of the overlapping area matches the first minimum light intensity; the light intensity described by the first Gaussian function with unshifted coordinate at the center position of the overlapping area matches the maximum light intensity of the first target light intensity distribution;

[0193] In the overlapping area, a second Gaussian function with coordinate shifting is used to describe the second target light intensity distribution after the light intensity is weakened; the light intensity described by the second Gaussian function with coordinate shifting at the center position of the overlapping area matches the second minimum light intensity; the light intensity described by the second Gaussian function with unshifted coordinates at the center position of the overlapping area matches the maximum light intensity of the second target light intensity distribution.

[0194] The present application also provides an electronic device. The electronic device is in the form of a general-purpose computing device. The components of the electronic device may include, but are not limited to: at least one processor, at least one memory, and a bus connecting different system components (including the memory and the processor). The processor may include: Fig.18 The various modules in the device shown.

[0195] The memory stores program codes, which can be executed by the processor so that the processor executes the steps of the exemplary embodiments described in the various exemplary embodiments above. For example, the processor can execute Figure 8 The steps shown in .

[0196] The memory may include readable media in the form of volatile memory, such as random access memory (RAM) and / or cache memory, and may further include read only memory (ROM).

[0197] The memory may also include a program / utility having a set (at least one) of program modules, such program modules including but not limited to: an operating system, one or more application programs, other program modules and program data, each of which or some combination may include an implementation of a network environment.

[0198] The bus may represent one or more of several types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, a processor, or a local bus using any of a variety of bus architectures.

[0199] The present application also provides a computer-readable storage medium having computer-readable instructions stored thereon. When the computer-readable instructions are executed by a processor of a computer, the computer is enabled to execute a method provided by any of the above method embodiments.

[0200] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the appended claims.

Claims

1. A superlens for projecting an X-shaped light spot, characterized in that: The superlens includes a substrate and a micro-nano structure disposed on the substrate; the superlens is used to receive incident light, and modulate and output the incident light to project an X-shaped light spot; Each sub-region within the coverage area of ​​the X-shaped light spot is mapped one-to-one with each sub-region within the effective area of ​​the super lens.

2. The metalens according to claim 1, characterized in that The X-shaped light spot includes a first line light spot and a second line light spot intersecting each other; the first line light spot intersects the second line light spot perpendicularly.

3. A method for designing a metalens for projecting an X-shaped light spot, characterized in that: The method is used to design a superlens as claimed in any one of claims 1 to 2, wherein the X-shaped light spot includes an intersecting first line light spot and a second line light spot, and the first line light spot and the second line light spot share an overlapping area; the method comprises: Based on a first target light intensity distribution of the first line light spot, a first phase for the first line light spot to be projected by the metalens is obtained, and based on a second target light intensity distribution of the second line light spot, a second phase for the second line light spot to be projected by the metalens is obtained; Based on the first phase and the second phase, simulating the process of the superlens projecting the X-shaped light spot to obtain a simulated light intensity distribution of the X-shaped light spot; If the simulated light intensity distribution does not meet the target requirement, the first target light intensity distribution and the second target light intensity distribution are collaboratively optimized at least in the overlapping area, and based on the optimized target light intensity distribution, the first phase, the second phase and the simulated light intensity distribution are updated until the simulated light intensity distribution meets the target requirement, thereby obtaining the first phase and the second phase that meet the target requirement; Based on the first phase and the second phase that meet target requirements, the superlens for projecting the X-shaped light spot is constructed.

4. The method according to claim 3, characterized in that The method further comprises: If the simulated light intensity distribution does not meet the target requirement, the first target light intensity distribution and the second target light intensity are subjected to distributed optimization outside the overlapping area.

5. The method according to claim 3, characterized in that: In the overlapping area, collaboratively optimizing the first target light intensity distribution and the second target light intensity distribution includes: In the overlapping area, the first target light intensity distribution and the second target light intensity distribution are first weakened, and then the weakened first target light intensity distribution and the second target light intensity distribution are collaboratively optimized.

6. The method according to claim 5, characterized in that In the overlapping area, the first target light intensity distribution and the second target light intensity distribution are weakened, including: Based on the coherence of the incident light, determining a multiplication factor of the light intensity after superposition in the overlapping area compared to the light intensity without superposition; Based on the multiplication factor, the first target light intensity distribution and the second target light intensity distribution are weakened in the overlapping area.

7. The method according to claim 5, characterized in that In the overlapping area, the first target light intensity distribution and the second target light intensity distribution are weakened, including: In the overlapping region, determining a first minimum light intensity that the first target light intensity distribution should reach after the light intensity is weakened, and a second minimum light intensity that the second target light intensity distribution should reach; In the overlapping area, a first Gaussian function with coordinate shift is used to describe the first target light intensity distribution after the light intensity is weakened; the light intensity described by the first Gaussian function with coordinate shift at the center position of the overlapping area matches the first minimum light intensity; the light intensity described by the first Gaussian function with unshifted coordinate at the center position of the overlapping area matches the maximum light intensity of the first target light intensity distribution; In the overlapping area, a second Gaussian function with coordinate shift is used to describe the second target light intensity distribution after the light intensity is weakened; the light intensity described by the second Gaussian function with coordinate shift at the center position of the overlapping area matches the second minimum light intensity; the light intensity described by the second Gaussian function with unshifted coordinates at the center position of the overlapping area matches the maximum light intensity of the second target light intensity distribution.

8. The method according to claim 1, characterized in that The first target light intensity distribution and the second target light intensity distribution are both described and optimized using high-order modulus Gaussian functions.

9. The method according to claim 8, characterized in that The high-order modulus Gaussian function includes: a super Gaussian function, a flat-top Gaussian function, and a super Lorentzian function.

10. An emission module for projecting an X-shaped light spot, characterized in that: The emission module comprises: a light source; a super lens as described in any one of claims 1 to 2; The super lens is arranged on the light-emitting side of the light source; the super lens is used to receive the light beam emitted by the light source, and modulate and project the light beam emitted by the light source into an X-shaped light spot.

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