Superlens for beam splitting, transmitting module and laser radar detection system

Abstract

The utility model provides a super lens for beam splitting, a transmitting module and a laser radar detection system. The super lens comprises a substrate and cells arranged on the substrate, the cells are arranged on the substrate in an equal period, and each cell comprises at least one micro-nano structure; the super lens is used for modulating a light beam emitted by the light source and outputting a plurality of sub light beams; and the plurality of sub-light beams jointly form a light spot dot matrix on a target plane. The superlens provided by the utility model can modulate the received light beam and output a plurality of sub-light beams with high signal-to-noise ratios, so that the effective detection distance of the laser radar detection system comprising the superlens is longer, and the detection precision of the laser radar detection system is also improved.

Description

Technical Field

[0001] The present application relates to the field of optics, and particularly to a metalens for beam splitting, a transmitting module, and a lidar detection system. Background Art

[0002] Lidar detection systems are usually used to obtain the depth information of an object to be detected relative to the lidar detection system, and by processing the collected depth information, the distribution of the object to be detected in the environment can be obtained. Therefore, lidar detection systems are also widely used in automotive autonomous driving, military detection, and various types of autonomous robots.

[0003] However, in the prior art, lidar detection systems have the disadvantages of large size and low signal-to-noise ratio of the emitted light beam, which can lead to problems such as short effective detection distance and poor detection accuracy of the lidar detection system. Summary of the Utility Model

[0004] An object of the present application is to provide a metalens for beam splitting, a transmitting module, and a lidar detection system. The metalens provided by the present application can modulate the received light beam and ensure that multiple sub-beams after diffraction beam splitting have high signal-to-noise ratio and high collimation, thereby improving the effective detection distance of the lidar and also improving the detection accuracy.

[0005] According to an aspect of an embodiment of the present application, a metalens for beam splitting is disclosed. The metalens includes: a substrate and cells disposed on the substrate; the cells are arranged in an equal period on the substrate, and each cell includes at least one micro-nano structure; the metalens is used to modulate the light beam emitted by a light source and output multiple sub-beams; the multiple sub-beams jointly form a light spot array on a target plane.

[0006] In an exemplary embodiment of the present application, the metalens satisfies:

[0007] dsinα m =mλ;

[0008]

[0009] where d is the grating constant, m is the diffraction order, α m is the diffraction angle corresponding to the m-th diffraction order, λ is the central wavelength of the light beam emitted by the light source, p is the period of the micro-nano structure of the metalens, and n is an adjustable positive integer.

[0010] In an exemplary embodiment of the present application, the metalens further satisfies:

[0011]

[0012] Among them, L m is the size of the effective area of the superlens, and θ is the half-angle of divergence of the sub-beams obtained by splitting the beam emitted by the light source.

[0013] In an exemplary embodiment of the present application, the full angle of divergence of each sub-beam output by the superlens is less than 0.5°.

[0014] In an exemplary embodiment of the present application, the full angle of divergence of each sub-beam output by the superlens is less than 0.2°.

[0015] In an exemplary embodiment of the present application, a light emitting module is disclosed. The light emitting module includes: a light source; a superlens provided as in any of the above embodiments;

[0016] The superlens is disposed on the light-emitting side of the light source; the superlens is configured to receive the beam emitted by the light source and modulate it to output multiple sub-beams, and the multiple sub-beams form a light spot array on the target plane.

[0017] In an exemplary embodiment of the present application, the light source is a single-mode fiber laser.

[0018] In an exemplary embodiment of the present application, a lidar detection system is disclosed. The lidar detection system includes: a light emitting module provided as in any of the above embodiments; a receiving module;

[0019] The receiving module is configured to receive the reflected beam reflected by the target plane and sense the reflected beam.

[0020] In an exemplary embodiment of the present application, the receiving module includes: a focusing lens; a sensor;

[0021] The focusing lens is configured to converge the reflected beam reflected by the target plane and emit the converged reflected beam to the sensor;

[0022] The sensor is configured to sense the reflected beam converged by the focusing lens.

[0023] In an exemplary embodiment of the present application, a filter film is disposed on the focusing lens; the filter film is configured to filter out the beams outside the working wavelength band of the beam emitted by the light source.

[0024] The metalens for beam splitting provided by the present application includes: a substrate and cells disposed on the substrate; the cells are arranged on the substrate with equal periods, and each cell includes at least one micro-nano structure; the metalens is used to modulate the light beam emitted by a light source and output multiple sub-beams; the multiple sub-beams jointly form a light spot array on a target plane. The metalens provided by the present application can modulate the received light beam and output multiple sub-beams with high signal-to-noise ratio, so that the effective detection distance of the lidar detection system including it is longer, and the detection accuracy of the lidar detection system is also improved.

[0025] Other features and advantages of the present application will become apparent from the following detailed description, or be learned in part from the practice of the present application.

[0026] It should be understood that the above general description and the following detailed description are exemplary and do not limit the present application. Description of the Drawings

[0027] By referring to the accompanying drawings and describing its exemplary embodiments in detail, the above and other objects, features, and advantages of the present application will become more apparent.

[0028] Figure 1 The schematic structural diagram of the metalens provided by an embodiment of the present application is shown.

[0029] Figure 2 The schematic structural diagram of the emission module provided by an embodiment of the present application is shown.

[0030] Figure 3 The schematic structural diagram of the lidar detection system provided by an embodiment of the present application is shown.

[0031] Figure 4 The schematic structural diagram of the lidar detection system provided by an embodiment of the present application is shown.

[0032] Figure 5 The schematic structural diagram of the lidar detection system provided by an embodiment of the present application is shown.

[0033] Figure 6 The schematic structural diagram of the lidar detection system provided by an embodiment of the present application is shown.

[0034] Figure 7 The noise map of the light spot array projected by the lidar detection system provided in Embodiment 1 of the present application is shown.

[0035] Figure 8 The noise map of the light spot array projected by the lidar detection system provided in Embodiment 2 of the present application is shown.

[0036] Reference numerals:

[0037] 1 - metalens; 11 - substrate; 12 - micro - nano structure; 2 - light source; 3 - light source fixing structure; 4 - focusing lens; 5 - sensor; 6 - housing; 7 - filter film; 8 - baffle structure; 9 - first cavity; 10 - second cavity. Detailed implementation manners

[0038] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these example embodiments are provided so that this application will be more thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. The drawings are only schematic illustrations of this application and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus their repeated description will be omitted.

[0039] In addition, the described features, structures, or characteristics can be combined in any suitable manner in one or more example embodiments. In the following description, numerous specific details are provided to give a thorough understanding of the example embodiments of this application. However, those skilled in the art will realize that one or more of the specific details can be omitted in practicing the technical solutions of this application, or other methods, components, steps, etc. can be adopted. In other cases, well - known structures, methods, implementations, or operations are not shown or described in detail to avoid obscuring the various aspects of this application.

[0040] In the prior art, in many application scenarios, a lidar detection system is usually used to detect a target object. The lidar detection system measures the distance from the target object to the lidar detection system by calculating the time difference between the emitted light beam and the received light beam. However, the lidar detection system in the prior art has problems of large size and low signal - to - noise ratio of the emitted light beam, which results in a short effective detection distance of the lidar detection system and poor detection accuracy of the lidar detection system.

[0041] In consideration of overcoming the above - mentioned defects existing in the related art, this application provides a metalens for beam splitting, a transmitting module, and a lidar detection system. The metalens provided by this application can modulate the received light beam and output multiple sub - beams with high signal - to - noise ratio, so that the lidar detection system including it has a longer effective detection distance and also improves the detection accuracy of the lidar detection system.

[0042] This application provides a metalens for beam splitting, as Figure 1 shown Figure 1The schematic structural diagram of the metalens provided by an embodiment of the present application is shown. The metalens 1 includes: a substrate 11 and cells disposed on the substrate 11; the cells are arranged equidistantly on the substrate 11, and each cell includes at least one micro-nano structure 12, and the micro-nano structure 12 is a sub-wavelength structure. Among them, the equidistant arrangement of the cells means that the cell sizes are equal and are continuously arranged on the substrate 11, preferably arranged in a close-packed pattern, such as a square or a regular hexagon; the metalens 1 mainly provides corresponding phases at various locations thereon by configuring parameters such as the material, cross-sectional size, height, and arrangement period of the micro-nano structures 12 at various locations thereon, applies different phase mutations to the received light beam, and further enables each position on the metalens 1 to have a certain phase gradient, so that the metalens 1 modulates the light beams received at different positions thereon.

[0043] As Figure 1 shown, Figure 1 each part within each dashed box in is represented as a cell. It should be noted that the number of micro-nano structures 12 included in each cell is the same, Figure 1 which is only for illustrative purposes and does not represent the actual number of micro-nano structures 12 included in each cell in the metalens 1.

[0044] In the embodiment of the present application, the metalens 1 is used to split the received light beam, so as to output multiple sub-light beams. After the multiple sub-light beams propagate a certain distance, they jointly form a light spot array on the target plane where the object to be measured is located.

[0045] Based on the superposition property of the metalens phase, the phase of the metalens 1 includes a splitting phase; the splitting phase is used to diffractively split the light beam received by the metalens 1; that is to say, the phase distribution within the coverage area of the metalens 1 in the present application includes a splitting phase for diffractively splitting the received light beam. Thereby, the present application can achieve diffractive splitting of the light beam through a single metalens. Compared with the traditional method of using a combination of a beam splitting device and a lens to achieve diffractive splitting of the light beam, this can reduce the volume of the system and also reduce the production cost. Moreover, the cells on the metalens 1 provided in the present application are periodically arranged in a grating manner, which can more accurately modulate the received light beam, and the metalens 1 can also suppress unwanted reflected light beams or refracted light beams, so that each sub-light beam output by the metalens 1 has a high signal-to-noise ratio.

[0046] In one embodiment, the beam splitting phase of the metalens 1 is optimized by the GS (Gerchberg-Saxton Algorithm); the GS algorithm is a phase retrieval algorithm, and its principle is to retrieve the corresponding phase distribution through the known light intensity distribution of the object plane and the intensity distribution of the observation plane. In order to enable the metalens 1 to split the received light beam into sub-beams with high signal-to-noise ratio, in this application, during the design process of the beam splitting phase of the metalens 1, the grating method is used to assist the GS algorithm in the design, that is, during the process of using the GS algorithm to design the beam splitting phase of the metalens 1, the coefficient limitation of the grating method is added. Specifically, the metalens 1 needs to satisfy the following formula:

[0047] dsinα m =mλ;(1)

[0048]

[0049] Wherein, d is the grating constant, m is the diffraction order, α m is the diffraction angle corresponding to the m-th diffraction order, λ is the central wavelength of the light beam emitted by the light source, p is the period of the micro-nano structure 12 of the metalens 1, and n is an adjustable positive integer.

[0050] It should be noted that when introducing the grating method in the design of the beam splitting phase of the metalens, the metalens 1 is actually regarded as a transmission grating for design. When the light beam passes through the metalens 1, the light beam is dispersed into multiple sub-beams in different directions, and each sub-beam has a corresponding diffraction order and a corresponding diffraction angle. Therefore, according to formula (1), the grating constant d can be calculated through the diffraction angle α m corresponding to the m-th diffraction order required in practice, where m is a non-zero integer. It can be understood that the grating constant d also represents the size of each unit cell on the metalens; then, according to formula (2), the period of the micro-nano structure 12 on the metalens 1 is calculated through the grating constant d. In fact, n represents the number of micro-nano structures 12 included within the length range corresponding to the grating constant d. If the value of n is larger, it means that the number of micro-nano structures 12 within the length range corresponding to the grating constant d is more, that is, the number of micro-nano structures 12 included within the size of each unit cell on the metalens is more, which also means that the diffraction efficiency of the metalens 1 is higher, so that the metalens 1 can achieve more precise control of the light beam. Note that in the embodiments of this application, the value range of n is [180, 1800]. The lower limit of the value range of n ensures the modulation ability of the metalens for the light beam while reducing the processing difficulty and production cost; the upper limit enables the metalens 1 to have better modulation ability for the light beam and achieve more precise control of the light beam. Preferably, the value range of n is [300, 450].

[0051] Furthermore, the metalens 1 is also configured with a collimation phase for collimating the light beam received by the metalens 1. Although the metalens 1 is already configured with a collimation phase so that the metalens 1 can collimate the light beam it receives and project a light beam with a smaller divergence angle, in order to ensure that each sub-beam obtained by splitting the light beam by the metalens 1 has a higher collimation degree, in this embodiment, the far-field divergence angle of each sub-beam is restricted during the design of the splitting phase of the metalens 1. Specifically, the metalens 1 also needs to satisfy the following formula:

[0052]

[0053] where L m is the size of the effective area of the metalens 1, λ is the central wavelength of the light beam emitted by the light source, and θ is the half divergence angle of each sub-beam obtained by splitting the light beam. Note that the effective area of the metalens 1 refers to the area on the metalens where micro-nano structures are provided. The shape of this effective area includes, but is not limited to: circular, elliptical, rectangular, square; when the shape of the effective area is circular, L m represents the diameter of the effective area; when the shape of the effective area is elliptical, L m represents the major axis or minor axis of the effective area. Note that in this case, the half divergence angle λ is also divided into the half divergence angle in the major axis direction and the half divergence angle in the minor axis direction; when the effective area is square, L m represents the side length of the effective area; when the effective area is rectangular, L m represents the length or width of the effective area. Similar to the elliptical effective area, the half divergence angle λ is also divided into two half divergence angles in two directions, corresponding to the long side direction and the wide side direction respectively.

[0054] It should be noted that the divergence angles of each sub-beam obtained by splitting the light beam by the metalens 1 are approximately the same. Therefore, θ is uniformly used to represent the half divergence angle of all sub-beams, and θ is expressed in radians. Radian is a dimensionless unit; as Figure 2 shown, Figure 2The shaded part in [Figure] is the sub - beam output by the metalens 1. The dotted line in the shaded part is the central ray of the sub - beam. θ represents the half - angle of the divergence angle of the sub - beam, and β represents the angle between adjacent sub - beams. According to Equation (3), the radius of the metalens 1 is related to the central wavelength of the beam and the divergence angle of each sub - beam, specifically showing a negative correlation. That is to say, if the divergence angle of each sub - beam obtained after the beam splitting by the metalens 1 is smaller, the radius of the metalens 1 is larger. In fact, it is to adjust the radius of the metalens 1 according to the divergence angle of the sub - beam to be achieved, so as to be able to cooperate with the collimation phase of the metalens 1 to make each sub - beam obtained by the beam splitting of the metalens 1 have higher collimation. When the collimation of each sub - beam is higher, it means that the signal intensity of the light spot projected on the target plane is more concentrated, that is, the signal intensity is stronger. The sub - beam with high collimation can also reduce unnecessary scattering and reduce the background noise caused by scattering. Therefore, the sub - beam with high collimation improves the signal intensity while reducing the noise, thereby improving the signal - to - noise ratio of the sub - beam.

[0055] In one embodiment, the full - angle of the divergence angle of each sub - beam output by the metalens 1 is less than 0.5°. Preferably, the full - angle of the divergence angle of each sub - beam output by the metalens 1 is less than 0.2°. In this case, multiple sub - beams with high collimation can be output by a single metalens, improving the light energy utilization rate of the light spot array.

[0056] In one embodiment, the collimation phase of the metalens 1 provided in the present application is obtained by optimizing and fitting through an optical product design and simulation software (such as Zemax simulation software). After the metalens 1 obtains the collimation phase through this method of optimization and fitting, it can better collimate the beam emitted by the actual light source type, having a better collimation effect. The collimation phase of the metalens 1 before optimization satisfies:

[0057]

[0058] wherein, is the collimation phase of the metalens 1 before optimization, λ is the central wavelength of the beam emitted by the light source, f is the focal length of the metalens 1, and x and y are the coordinates of the metalens 1 in its two - dimensional plane, respectively.

[0059] The present application provides a transmitting module, as Figure 2 shown. The transmitting module includes: a light source 2; the metalens 1 as described in any of the above embodiments. The metalens 1 is disposed on the light - emitting side of the light source 2 and is used to receive the beam emitted by the light source 2, and then modulate the beam to output multiple sub - beams with high signal - to - noise ratio. After all the sub - beams propagate a certain distance, they jointly form a light spot array at the target plane or the detection object.

[0060] Since the metalens 1 in the transmitting module has the ability to project multiple sub-beams with high signal-to-noise ratio, the lidar detection system including it can split the beam emitted by the light source through a single metalens, simplifying the structure of the lidar detection system, reducing the volume of the lidar detection system, and also reducing the production cost of the lidar detection system; moreover, the beam projected by the lidar detection system also has a high signal-to-noise ratio, thereby increasing the effective detection range of the lidar detection system and also improving the detection accuracy of the lidar detection system.

[0061] In one embodiment, the light source 2 in the receiving module is a single-mode fiber laser. The single-mode fiber laser can emit high-power laser beams, enabling the lidar detection system to have a greater effective detection range, so as to be applicable to more application scenarios.

[0062] In one embodiment, the transmitting module further includes: a light source fixing structure 3 for fixing the light source 2 (as Figure 3 shown). The light source fixing structure 3 can fix the light source 2 at the actual required position, preventing the light source 2 from shifting due to the change in the spatial position of the lidar detection system, which may cause the lidar detection system to be unable to perform the detection task.

[0063] This application provides a lidar detection system, as Figure 3 shown, Figure 3 which shows a schematic structural diagram of the lidar detection system provided by an embodiment of this application. The lidar system includes: a transmitting module and a receiving module as described in the above embodiment; the receiving module is configured to receive the reflected beam reflected by the target plane and sense the reflected beam. It should be noted that Figure 3 the dashed line in Figure 3 is only for the purpose of facilitating explanation. The left side of the dashed line represents the receiving module of the lidar detection system, and the right side of the dashed line represents the transmitting module in the lidar detection system. The positions of the receiving module and the transmitting module can be swapped. In the lidar detection system, through the cooperation of the transmitting module and the receiving module, the light spot array projected by the transmitting module can be used to measure the distance of the target plane or the detection object, and can also be used to sense the shape of the target plane or the detection object, and can also be used to sense the attitude of the target plane or the detection object.

[0064] In one embodiment, the receiving module includes: a focusing lens 4; a sensor 5.

[0065] Specifically, the focusing lens 4 is used to converge the reflected light beam reflected by the target plane, and converge the received light beam so that the converged light beam can be emitted by the focusing lens 4 onto the sensor 5. The sensor 5 is used to sense the reflected light beam converged by the focusing lens 4. In fact, the sensor 5 senses the light spot array projected by the emitting device on the target plane or the detection object.

[0066] After multiple sub-beams with high signal-to-noise ratio emitted by the metalens 1 of the emitting module jointly form a light spot array on the target plane or the detection object, the reflected light beam reflected by this light spot array can be received by the focusing lens 4, and the focusing lens 4 converges and outputs the reflected light beam, so that the sensor 5 can sense this light spot array. Thereby, the lidar detection system can determine the distance, shape or posture of the target plane or the detection object based on the light spot array sensed by the sensor 5.

[0067] In one embodiment, the focusing lens 4 is a refractive lens with focusing ability.

[0068] In one embodiment, the focusing lens 4 is a first metalens; it should be noted that the "first" in the first metalens here is only used to distinguish it from the metalens 1 of the emitting module. The phase of the first metalens is different from the phase of the metalens 1. The first metalens can only have a focusing phase for converging the light beam; on the basis of having a focusing phase, the first metalens can also have a collimating phase for collimating the light beam.

[0069] In one embodiment, as Figure 4 and Figure 5 shown, Figure 4 shows a schematic structural diagram of a lidar detection system provided by an embodiment of the present application. Figure 5 shows a schematic structural diagram of a lidar detection system provided by an embodiment of the present application. A filter film 7 can be provided on the focusing lens 5; the filter film 7 is used to filter the light beam outside the working wavelength band of the light beam emitted by the light source 2.

[0070] It should be noted that the filter film 7 in this embodiment can be provided on the light-emitting surface of the focusing lens 4, as Figure 4 shown; or it can be provided on the light-incident surface of the focusing lens 4, as Figure 5 shown. In this case, the filter film 7 can block the light beam outside the working wavelength band of the light beam emitted by the light source from reaching the sensor 5 from outside the receiving module, so as to ensure that the sensor 5 can accurately sense the light spot array projected by the emitting device, and further improve the detection accuracy of the lidar detection system.

[0071] In addition, in another embodiment, an independent filter can also be provided in the receiving device to filter out the light beams outside the working wavelength band of the light beams emitted by the light source 2 through the independent filter.

[0072] In one embodiment, the transmitting module and the receiving module in the lidar system are two independent components, which are respectively arranged at different positions in the lidar. In this case, as long as the receiving module can effectively receive the reflected light spot array projected by the transmitting module.

[0073] In another embodiment, as Figures 3 to 5 shown, the transmitting module and the receiving module in the lidar detection system are arranged in the same housing. The lidar detection system provided by the present application further includes: a housing 6; both the transmitting module and the receiving module are arranged inside the space enclosed by the housing 6.

[0074] Specifically, the housing 6 is actually used to fix the transmitting module and the receiving module. The light source 2 can be directly fixed at the bottom inside the housing 6, or can be fixed at the bottom inside the housing 6 through the light source fixing structure 3; the sensor 5 can also be fixed at the bottom inside the housing 6; in this case, a power supply element can also be provided at the bottom inside the housing 6 to provide a driving current for the light source 2 and the sensor 5. It should be noted that in this case, the light source 2 and the sensor 5 can be respectively fixed at different positions in the housing 6, not limited to being fixed at the bottom inside the housing 6, Figures 3 to 5 only for example.

[0075] The metalens 1 and the focusing lens 4 can be arranged at the top inside the housing 6, and can be fixed by means of dispensing or other means, which is not limited herein. It should be noted that the metalens 1 and the focusing lens 4 can also be fixed inside the space enclosed by the housing 6 through an additionally provided fixing structure, as long as the metalens 1 can project a light spot array at the target plane or the detection object, and the focusing lens 4 can receive the light beam reflected by the target plane and converge it to the sensor 5. The specific setting position is not limited in the present application.

[0076] In Figures 3 to 5 the lidar detection system provided by the corresponding embodiment, the transmitting module and the receiving module are jointly arranged inside the space enclosed by the housing 6. In this case, the light beam emitted by the light source 2 may be reflected by the metalens 1 and directly propagate inside the lidar detection system to the sensor 5, thereby interfering with the sensor 5 and reducing the detection accuracy of the lidar detection system.

[0077] Therefore, in one embodiment, as Figure 6 shown, Figure 6The schematic structural diagram of the lidar detection system provided by an embodiment of the present application is shown. The lidar detection system further includes a baffle structure 8 disposed inside the space enclosed by the housing 6. The baffle structure 8 divides the space enclosed by the housing 7 into a first cavity 9 and a second cavity 10. The transmitting module is located in the first cavity 9, and the receiving module is located in the second cavity 10. It should be noted that the transmitting module can also be located in the second cavity 10, and the receiving module can also be located in the first cavity 9. Moreover, the material of the baffle structure 8 is a material that is opaque in the working wavelength band of the light beam emitted by the light source 2.

[0078] In this way, the baffle structure 8 separates the transmitting module and the receiving module in two independent spaces, avoiding the light beam emitted by the light source 2 in the transmitting module from directly reflecting inside the lidar detection system onto the sensor 5 in the receiving module. As a result, the light beams received by the sensor 5 are all reflected light beams from outside the receiving module, reflected by the target plane or the detection object, further ensuring the detection accuracy of the lidar detection system.

[0079] Embodiment 1

[0080] See Figure 7 , Figure 7 which shows the noise map of the light spot array projected by the lidar detection system provided in Embodiment 1 of the present application. In this embodiment, the light source 2 is a single-mode fiber laser with a working center wavelength of 1550 nm. After the light beam emitted by the light source 2 is split by the superlens 1, 8 sub-beams are output. The angle between each two sub-beams is 1°, and the divergence angle of each sub-beam is less than 0.1°. According to Figure 7 it can be seen that the high-order noise is suppressed to below -30 dB, and the noise within the 8 sub-beams is suppressed to below -50 dB. The distance between the target plane and the superlens 1 is 1 m.

[0081] Embodiment 2

[0082] See Figure 8 , Figure 8 which shows the noise map of the light spot array projected by the lidar detection system provided in Embodiment 2 of the present application. In this embodiment, the light source 2 is a single-mode fiber laser with a working center wavelength of 1310 nm. After the light beam emitted by the light source 2 is split by the superlens 1, 16 sub-beams are output. The angle between each two sub-beams is 1°, and the divergence angle of each sub-beam is less than 0.08°. According to Figure 8 it can be seen that the high-order noise is suppressed to below -25 dB, and the noise within the 16 sub-beams is suppressed to below -50 dB. The distance between the target plane and the superlens 1 is 1 m.

[0083] Other embodiments of the present application will be readily contemplated by those skilled in the art upon consideration of the specification and practice of the utility model disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application, which follow the general principles of the present application and include known common general knowledge or conventional technical means in the technical field not disclosed in the present application. The specification and examples are only to be considered as exemplary, and the true scope and spirit of the present application are pointed out by the appended claims.

Claims

1. A metalens for beam splitting, characterized in that, The metalens includes: a substrate and cells disposed on the substrate; the cells are arranged equidistantly on the substrate, and each cell includes at least one micro-nano structure; The metalens is configured to modulate a light beam emitted by a light source and output multiple sub-beams; the multiple sub-beams jointly form a light spot array on a target plane.

2. The superlens according to claim 1, wherein The metalens satisfies: dsinα m = mλ; where d is the grating constant, m is the diffraction order, α m is the diffraction angle corresponding to the m-th diffraction order, λ is the central wavelength of the light beam emitted by the light source, p is the period of the micro-nano structure, and n is an adjustable positive integer.

3. The metalens according to claim 2, wherein The metalens further satisfies: Among them, L m is the size of the effective area of the superlens, and θ is the half-angle of divergence of the sub-beams obtained by splitting the beam emitted by the light source.

4. The metalens according to claim 1, wherein The full divergence angle of each sub-beam output by the metalens is less than 0.5°.

5. The metalens according to claim 1, wherein The full divergence angle of each sub-beam output by the metalens is less than 0.2°.

6. A transmitting module, characterized in that, The emission module includes: a light source; the metalens according to any one of claims 1-5; The metalens is disposed on the light-emitting side of the light source; the metalens is configured to receive the light beam emitted by the light source and perform modulation to output multiple sub-beams, and the multiple sub-beams form a light spot array on the target plane.

7. The emission module according to claim 6, characterized in that, The light source is a single-mode fiber laser.

8. A lidar detection system, characterized in that, The lidar detection system includes: the emission module according to any one of claims 6-7; a reception module; The reception module is configured to receive a reflected light beam reflected by the target plane and sense the reflected light beam.

9. The lidar detection system according to claim 8, characterized in that, The reception module includes: a focusing lens; a sensor; The focusing lens is configured to converge the reflected light beam reflected by the target plane and emit the converged reflected light beam to the sensor; The sensor is configured to sense the reflected light beam converged by the focusing lens.

10. The lidar detection system according to claim 9, wherein, A filter film is disposed on the focusing lens; the filter film is configured to filter light beams outside the working wavelength band of the light beam emitted by the light source.

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