Superlens for laser emission, laser emission device and laser radar

Abstract

The invention discloses a super lens for laser emission, a laser emission device and a laser radar. The super lens comprises a substrate and a micro-nano structure arranged on the substrate, in an effective area of the super lens, at least a local area in a first direction is used for receiving a light beam obliquely incident relative to the first direction, and the first direction is parallel to the effective area; the super lens is at least used for collimating and deflecting the received light beam along the first direction. According to the superlens and the laser emitting device provided by the invention, large-angle scanning of the laser radar can be realized under the condition that the process precision is relatively low, the production difficulty of the laser radar capable of performing large-angle scanning is reduced, and the production cost is also reduced.

Description

Technical Field

[0001] The present application relates to the field of laser radar, and in particular to a super lens for laser emission, a laser emission device and a laser radar. Background Art

[0002] In the fields of terrain mapping, road surveying, indoor 3D measurement and now intelligent driving, technicians usually use LiDAR to scan the shape of specific objects or environmental objects to determine spatial information. At present, because the angle range covered by the light beam emitted by LiDAR is not large enough, additional methods are needed to make the light beam emitted by LiDAR cover a larger angle range. The method usually used is to rotate the optical element with mechanical parts to deflect the light beam, thereby achieving large-angle scanning.

[0003] However, the volume of the laser radar that uses mechanical parts to rotate optical elements is not easy to compress, and the mechanical parts are not sensitive to response, the scanning speed is slow, and long-term use is prone to mechanical wear, which leads to a decrease in the scanning ability of the laser radar. Therefore, it is currently more inclined to use solid-state array light sources to scan by partition lighting. However, the divergence angle of the light beam emitted by the array light source is small, and a diffraction optical element with a large diffraction angle is required to expand the light beam in order to scan a larger angle range. However, the diffraction optical element with a large diffraction angle requires higher processing accuracy, low structural fault tolerance, and high processing cost. Summary of the invention

[0004] In response to the above technical problems, the present application provides a metalens for laser emission, a laser emission device, and a laser radar. The metalens and laser emission device provided in the present application can achieve large-angle coverage of the laser radar even when the process precision is low, thereby reducing the production difficulty of the laser radar capable of large-angle coverage and also reducing the production cost.

[0005] According to one aspect of an embodiment of the present application, a superlens for laser emission is disclosed, the superlens comprising: a substrate and a micro-nano structure disposed on the substrate;

[0006] In the effective region of the metalens, at least a partial region in a first direction is used to receive a light beam obliquely incident relative to the first direction, and the first direction is parallel to the effective region;

[0007] The superlens is at least used to collimate and deflect the received light beam along the first direction.

[0008] In an exemplary embodiment of the present application, in the effective area of ​​the superlens, the entire area in the first direction is used to receive light beams having the same inclination angle relative to the first direction.

[0009] In an exemplary embodiment of the present application, the effective area of ​​the metalens includes at least two partitions in the first direction, the same partition is used to receive light beams with the same inclination angle relative to the first direction, and different partitions are used to receive light beams with different inclination angles relative to the first direction.

[0010] In an exemplary embodiment of the present application, all subareas of the metalens in the first direction are symmetrically distributed about a center position of the effective area in the first direction.

[0011] According to one aspect of an embodiment of the present application, a laser emitting device is disclosed, and the laser emitting device includes: a superlens as described in any one of the above embodiments; and an array light source.

[0012] In an exemplary embodiment of the present application, the effective area of ​​the metalens includes at least two partitions in the first direction, and the arrayed light source includes at least two light source partitions in the first direction;

[0013] The number of partitions of the metalens is equal to the number of light source partitions of the array light source, and the partitions are matched one-to-one with the light source partitions; each of the partitions is used to receive and modulate the light beam emitted by the corresponding light source partition.

[0014] In an exemplary embodiment of the present application, the arrayed light source includes a first inclined portion and a second inclined portion;

[0015] All light source subareas on the first inclined portion are distributed on a first straight line inclined relative to the first direction, and all light source subareas on the second inclined portion are distributed on a second straight line inclined relative to the first direction, wherein the first straight line is inclined to the second straight line.

[0016] In an exemplary embodiment of the present application, all light source partitions on the array light source are distributed in a curve relative to the first direction.

[0017] In an exemplary embodiment of the present application, the arrayed light source is symmetrical in the first direction about a center position of the effective area in the first direction.

[0018] In an exemplary embodiment of the present application, the effective area of ​​the metalens includes at least two partitions in the first direction; each partition is used to independently deflect an obliquely incident light beam.

[0019] In an exemplary embodiment of the present application, the superlens is also used to perform beam splitting processing on the light beam emitted by each of the light source partitions in a second direction of the plane where the superlens is located;

[0020] The second direction is perpendicular to the first direction.

[0021] In an exemplary embodiment of the present application, the array light source is a VCSEL array light source.

[0022] In an exemplary embodiment of the present application, a laser radar is disclosed, and the laser radar includes: a laser emitting device as described in any one of the above items; and a receiving device.

[0023] The metalens for laser emission provided in the embodiment of the present application includes: a substrate and a micro-nano structure arranged on the substrate; in the effective area of ​​the metalens, at least a local area in a first direction is used to receive a light beam obliquely incident relative to the first direction, and the first direction is parallel to the effective area; the metalens is at least used to collimate and deflect the received light beam along the first direction. The present application realizes large-angle laser scanning through a single-chip metalens, and can realize large-angle scanning of laser radar under low process precision, reducing the production difficulty of laser radar capable of large-angle scanning and also reducing production costs.

[0024] 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.

[0025] 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

[0026] 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.

[0027] Figure 1 A schematic structural diagram of a prior art laser radar is shown.

[0028] Figure 2 A schematic structural diagram of a superlens 1 provided in one embodiment of the present application is shown.

[0029] Figure 3 A schematic structural diagram of an array light source 2 provided in an embodiment of the present application is shown.

[0030] Figure 4 A schematic diagram of a laser emitting device provided in an embodiment of the present application is shown.

[0031] Figure 5 A schematic diagram of a laser emitting device provided in an embodiment of the present application is shown.

[0032] Figure 6A schematic diagram of the phase design of a laser emitting device in a first direction provided by an embodiment of the present application is shown.

[0033] Figure 7 A schematic diagram of a laser emitting device provided by an embodiment of the present application in a second direction is shown.

[0034] Figure 8 A schematic diagram of a laser emitting device provided in an embodiment of the present application is shown.

[0035] Fig. 9 A schematic diagram of a laser emitting device provided in an embodiment of the present application is shown.

[0036] Fig.10 A schematic diagram of the laser radar provided in this application is shown.

[0037] Fig.11 The local phase distribution diagram of the superlens 1 of the laser emitting device provided in Example 1 of the present application is shown.

[0038] Fig.12 The light intensity distribution diagram of the outermost light beam projected by the laser emitting device provided in Example 1 of the present application is shown.

[0039] Fig.13 The light intensity distribution diagram of the outermost light beam projected by the laser emitting device provided in Example 1 of the present application is shown.

[0040] Fig.14 The local phase distribution diagram of the superlens 1 of the laser emitting device provided in Example 2 of the present application is shown.

[0041] Fig.15 The light intensity distribution diagram of the outermost light beam projected by the laser emitting device provided in Example 2 of the present application is shown.

[0042] Fig.16 The local phase distribution diagram of the superlens of the laser emitting device provided in Example 3 of the present application is shown.

[0043] Fig.17 The light intensity distribution diagram of the outermost light beam projected by the laser emitting device provided in Example 3 of the present application is shown.

[0044] Reference numerals:

[0045] 1-superlens; 11-substrate; 12-micro-nano structure; 110-partition; 2-array light source; 21-light source partition; 22-control circuit; 23-first inclined portion; 24-second inclined portion; 3-spherical mirror. DETAILED DESCRIPTION

[0046] 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.

[0047] 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 modules, components, 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 unclear.

[0048] In the prior art, since the angle range covered by the light beam emitted by the laser emitting device carried by the laser radar is not large enough, the laser radar usually uses mechanical parts to rotate the optical element to deflect the light beam, thereby realizing scanning within a certain spatial area, such as Figure 1 As shown, Figure 1 The structure diagram of the prior art laser radar is shown. Figure 1 In the process, the beam is deflected by rotating the galvanometer to scan the detection area within a certain angle range. However, the scanning is achieved by rotating the optical element through mechanical parts, which makes the laser radar bulky, difficult to miniaturize, and has high production costs. In addition, the mechanical parts are not sensitive to reaction, the scanning speed is slow, and mechanical wear is prone to occur after long-term use, thereby reducing the scanning performance of the laser radar. Therefore, it is currently more inclined to use a solid-state array light source to scan by partition lighting. However, the divergence angle of the light beam emitted by the array light source is small, and a diffraction optical element with a large diffraction angle is required to expand the light beam to scan a larger angle range. However, the diffraction optical element with a large diffraction angle requires high processing accuracy, low structural fault tolerance, and high processing cost. In addition, the diffraction optical element designed in this way can only make the light beam in the center part have a high diffraction efficiency, and the diffraction efficiency of the light beam on both sides of the edge is low, resulting in insufficient utilization of light energy.

[0049] In order to overcome the above-mentioned defects of the related art, the present application provides a metalens, a laser emitting device and a laser radar for laser emission. The metalens and laser emitting device provided in the present application can realize large-angle scanning of the laser radar under low process precision conditions, reduce the production difficulty of the laser radar capable of large-angle scanning, reduce the production cost, and also improve the scanning speed and stability, with strong controllability, and do not require large mechanical parts, which greatly compresses the overall volume of the laser emitting device, thereby reducing the volume of the laser radar, and ensures that all light beams within the maximum diffraction angle have high diffraction efficiency, thereby reducing the loss of light energy.

[0050] The present application provides a superlens 1 for laser emission, specifically, Figure 2 As shown, Figure 2 The schematic diagram of the structure of a superlens 1 provided in an embodiment of the present application is shown. The superlens 1 includes a substrate 11 and a micro-nano structure 12 disposed on the substrate 11, and the micro-nano structure 12 is a subwavelength structure. The superlens 1 mainly configures the material, cross-sectional size, height, arrangement period and other parameters of the micro-nano structure 12 at various locations thereon, thereby providing corresponding phases at various locations thereon, applying a phase mutation to the received light beam, and thus making each location on the superlens 1 have a certain phase gradient, so that the superlens 1 modulates the light beams received at different locations thereon.

[0051] In an embodiment of the present application, in the effective area of ​​the metalens 1, at least a partial area in the first direction is used to receive a light beam obliquely incident relative to the first direction, wherein the first direction is parallel to the effective area of ​​the metalens 1; the metalens 1 is at least used to collimate and deflect the received light beam along the first direction. It should be noted that the effective area of ​​the metalens 1 refers to an area that can be used for light beam modulation, and the light beam received by the metalens 1 includes a normally incident light beam and a light beam obliquely incident relative to the first direction. After receiving the light beam, the effective area of ​​the metalens 1 modulates the light beam along the first direction.

[0052] For the metalens 1, the maximum diffraction angle of the external light beam at normal incidence satisfies the following formula:

[0053]

[0054] Among them, θ maxis the maximum diffraction angle, λ is the working center wavelength of the light source, and P is the period of the micro-nano structure 12 on the metalens 1. After the light beam is modulated by the metalens 1, the diffraction angle of the light beam with high diffraction efficiency is less than 60% of the maximum diffraction angle, that is, only the light beam in the central area has a high diffraction efficiency, and the diffraction efficiency of the light beam at both ends of the edge is low. It can be found from formula (1) that since the working center wavelength λ is determined during the design and cannot be adjusted, the maximum diffraction angle of the metalens can only be increased by reducing the period P of the micro-nano structure 12 as much as possible. However, this will result in a very small size of the micro-nano structure 12 that meets the phase coverage. The smaller the size of the micro-nano structure 12, the higher the required process precision, and the greater the corresponding manufacturing difficulty.

[0055] However, according to the grating equation:

[0056]

[0057] Among them, θ i is the incident angle of the light beam, θ t is the exit angle of the light beam, m is the diffraction order of the grating, D is the grating constant,

[0058] Or, from the generalized Snell's law:

[0059]

[0060] Among them, n t is the refractive index of the material on the exit side of the light beam, n i is the material refractive index on the incident side of the light beam, is the phase distribution of superlens 1 Phase gradient with respect to coordinate x.

[0061] It can be found from formula (2) and formula (3) that, while keeping the other optical parameters unchanged, increasing the incident angle of the light beam emitted by the light source when irradiating the metalens 1 can increase the output angle of the light beam after being modulated and output by the metalens 1. Therefore, the light beam input to the metalens 1 can be set to an oblique incident light beam, so that the metalens 1 can achieve a large-angle deflection of the light beam. At the same time, since the relative deflection angle of the oblique incident light beam before and after modulation is small, it can also ensure that all light beams within the maximum diffraction angle have a high diffraction efficiency, thereby reducing the loss of light energy.

[0062] In one embodiment, the entire area of ​​the active area of ​​the metalens 1 in the first direction is used to receive light beams having the same inclination angle relative to the first direction. That is, in this case, the entire area of ​​the active area of ​​the metalens 1 receives light beams having the same incident angle, and collimates and deflects the received light beams in the first direction.

[0063] In one embodiment, the metalens 1 is partitioned in the first direction, that is, the effective area of ​​the metalens 1 is divided into at least two partitions 110 in the first direction, such as Figure 2 As shown, Figure 2 Each dotted box in the figure represents a different partition 110 ( Figure 2 For example only, the same partition 110 is used to receive light beams with the same inclination angle relative to the first direction, and different partitions 110 are used to receive light beams with different inclination angles relative to the first direction, that is, each partition 110 receives a light beam with a corresponding incident angle, and after receiving the light beam, each partition 110 also modulates the received light beam accordingly.

[0064] In one embodiment, all subareas of the metalens 1 in the first direction are symmetrically distributed about the center position of the effective area of ​​the metalens 1 in the first direction. Figure 2 As shown, Figure 2 The four partitions in the metalens 1 are symmetrically distributed about the center position of the effective area of ​​the metalens 1 in the first direction.

[0065] The present application provides a laser emitting device, which includes: a superlens 1 as described in the above embodiment; and an array light source 2.

[0066] Specifically, the array light source 2 is used to emit multiple light beams, and the superlens 1 is used to receive each light beam and modulate each light beam separately to achieve large-angle scanning.

[0067] In one embodiment, the metalens 1 includes at least two subareas 110 in the first direction, and the arrayed light source 2 includes at least two light source subareas 21 in the first direction. Figure 3 As shown, Figure 3 The schematic diagram of the structure of the array light source 2 provided in one embodiment of the present application is shown. The array light source 2 includes at least two sub-light sources, at least one of which constitutes a light source partition 21. The light source partition 21 is a partition consisting of a column or a row of independent sub-light sources. Figure 3 In the embodiment shown, the light source partition 21 is composed of a series of sub-light sources, and the dotted frame portion is a light source partition 21. In actual operation, the array light source 2 lights up each light source partition 21 in a time-sharing manner through the control circuit 22 to perform subsequent scanning operations. The x-axis is parallel to the horizontal direction of the paper surface, the y-axis is parallel to the vertical direction of the paper surface, and the z-axis is perpendicular to the paper surface.

[0068] In the embodiment of the present application, the superlens 1 is used to collimate the light beam emitted by each light source partition 21, and deflect the light beam emitted by at least one light source partition 21 in the first direction of the plane where the superlens 1 is located, so as to achieve large-angle scanning. It should be noted that the array light source 2 includes at least two light source partitions 21 in the first direction, and the direction of the x-axis is the same as the aforementioned first direction.

[0069] Furthermore, the number of the partitions 110 of the metalens 1 is equal to the number of the light source partitions 21 of the array light source 2, and the partitions 110 are matched one by one with the light source partitions 21, that is, each partition 110 has a light source partition 21 matched therewith, and each partition 110 is used to receive and modulate the light beam emitted by the corresponding light source partition 21. In fact, each partition 110 is used to receive the light beam emitted by the corresponding light source partition 21, collimate the received light beam, and at least one partition 110 deflects the light beam emitted by the corresponding light source partition 21 in the first direction.

[0070] In one embodiment, the array light source 2 adopts an obliquely distributed oblique incident light source, that is, the array light source 2 includes a first inclined portion 23 and a second inclined portion 24 in the first direction, and the first inclined portion 23 and the second inclined portion 24 each include a certain number of light source partitions 21.

[0071] Specifically, the array light source 2 uses a symmetrically tilted oblique incident light source to take into account the projection angles on both sides, such as Figure 4 As shown, Figure 4 A schematic diagram of a laser emitting device provided by an embodiment of the present application is shown, wherein the array light source 2 includes a first inclined portion 23 and a second inclined portion 24 in a first direction (x-axis direction), wherein all light source partitions 21 on the first inclined portion 23 are distributed along a first straight line inclined relative to the first direction, and all light source partitions 21 on the second inclined portion 24 are distributed along a second straight line inclined relative to the first direction, wherein the first straight line is inclined to the second straight line, the first straight line is parallel to the first inclined portion 23, and the second straight line is parallel to the second inclined portion.

[0072] Further, the first inclined portion 23 and the second inclined portion 24 are symmetrical about the center position of the effective area of ​​the metalens 1 in the first direction. It can also be understood that the first inclined portion 23 and the second inclined portion 24 are symmetrical about the normal line passing through the center position of the effective area of ​​the metalens 1. Figure 4The dashed straight line in is the normal line passing through the center position of the effective area of ​​the metalens 1, that is, the first inclined portion 23 and the second inclined portion 24 include the same number of light source subareas 21, and the first inclined portion 23 and the second inclined portion 24 have the same offset angle relative to the first direction. It should be noted that, in this case, the boundary line between adjacent light source subareas 21 in the array light source 2 is parallel to the y-axis direction.

[0073] Furthermore, based on the divergence angle of the sub-light source in the array light source 2, a reasonable relative position of the superlens 1 and the array light source 2 is set so that the irradiation areas of the light beams emitted by each light source partition 21 in the array light source 2 do not overlap, thereby avoiding crosstalk between the light beams emitted by adjacent light source partitions 21, and facilitating the separate regulation of each light beam by the superlens 1.

[0074] Furthermore, in order to reasonably utilize the effective working area of ​​the metalens 1, when configuring the light source partitions 21 in the first direction, the spatial positions of each light source partition 21 can be reasonably distributed so that the irradiation areas of the light beams emitted by each light source partition 21 are just closely arranged.

[0075] In one embodiment, all light source subareas 21 on the array light source 2 are distributed in a curve relative to the first direction.

[0076] Specifically, the array light source 2 arranges the light source partitions 21 in the first direction in the form of a curve distribution, that is, the light source partitions 21 are arranged as follows: Figure 5 As shown, Figure 5 A schematic diagram of a laser emitting device provided in an embodiment of the present application is shown.

[0077] Furthermore, the arrayed light source 2 is distributed in a symmetrical curve in the first direction, and the arrayed light source 2 is symmetrical about the center position of the effective area of ​​the metalens 1 in the first direction. It can also be understood that the arrayed light source 2 is symmetrical about the normal line passing through the center position of the effective area of ​​the metalens 1. Figure 5 The dotted straight line in is the normal line passing through the center position of the effective area of ​​the super lens 1.

[0078] It should be noted that, based on the divergence angle of the sub-light source in the array light source 2, the reasonable relative position of the metalens 1 and the array light source 2 is set so that the irradiation areas of the light beams emitted by each light source partition 21 in the array light source 2 do not overlap, avoiding the crosstalk of the light beams emitted by adjacent light source partitions 21, and facilitating the separate regulation of each light beam by the metalens 1. Moreover, in this case, the dividing line between adjacent light source partitions 21 in the array light source 2 is parallel to the y-axis direction.

[0079] Furthermore, in order to reasonably utilize the effective working area of ​​the metalens 1, when configuring the light source partitions 21 in the first direction, the spatial positions of the light source partitions 21 can be reasonably distributed, so that the irradiation areas of the light beams emitted by the light source partitions 21 are just closely arranged. The present application realizes laser projection by introducing a light source with an oblique incident angle and the cooperation of a metalens, so that a larger projection angle can be obtained even when the difficulty of the metalens processing technology is relatively low, and a light beam projection with a larger limit angle can be realized, thereby realizing laser projection within a larger angle range, reducing the processing difficulty of the metalens and reducing the production cost.

[0080] In one embodiment, the light beam projected by the laser emitting device needs to have a uniform angular distribution. However, since the light beam emitted by the array light source 2 has a certain divergence angle, if it is projected into the far field, the light beam will inevitably diverge, resulting in the problem that the angular distribution of the light beam does not meet the requirements and the energy is not concentrated. Therefore, it is necessary to collimate the light beam emitted by the array light source 2, that is, it is necessary to design a collimation phase for the metalens 1. like Figure 6 As shown, Figure 6 A schematic diagram of the phase design of a laser emitting device in a first direction provided by an embodiment of the present application is shown.

[0081] Since all the light beams received by the metalens 1 need to be collimated, all the partitions 110 in the metalens 1 can be designed as a whole to collimate the phase. Collimation Phase Satisfies any of the following formulas:

[0082]

[0083] Among them, x and y are the spatial coordinates of the two-dimensional plane where the superlens 1 is located, f is the effective focal length of the superlens 1, and a k is the phase coefficient, n is the phase order, and x0 and y0 are the off-axis coordinates of the focus corresponding to the collimated phase of each partition 110 in the metalens 1 relative to the geometric center of the partition 110. As an example, Figure 6 As shown, when the geometric center of the overall irradiation area of ​​each light source partition 21 on the array light source 2 is aligned with the geometric center of the corresponding partition 110: y0=0, x0=ftanγ, where γ is the angle between the main light beam and the plane where the super lens 1 is located.

[0084] Furthermore, the effective area of ​​the metalens 1 includes at least two partitions 110 in the first direction. After the light beam emitted by the light source partition 21 of the array light source 2 is collimated by the corresponding partition 110, it needs to be deflected to a specific angle, that is, directional deflection. Therefore, it is necessary to design a corresponding deflection phase for each partition 110 on the metalens 1. In other words, each partition 110 on the metalens 1 provides an independent deflection phase, and each deflection phase is used to independently deflect the received light beam in the first direction, thereby deflecting the light beam emitted by the light source partition 21 corresponding to each partition 110 into light beams with different exit angles. The exit angle refers to the angle between the main light ray of the exiting light beam and the normal of the metalens 1, such as Figure 6 α in .

[0085] It should be noted that, considering the maximization of the scanning angle of the laser emitting device, preferably, the light beam emitted by each light source partition 21 on the array light source 2 is obliquely incident on the metalens 1 in the first direction, that is, each partition 110 on the metalens 1 is used to deflect the received light beam. For the sake of convenience, it is assumed below that each partition 110 on the metalens 1 is used to deflect the received light beam.

[0086] In this case, the deflection phase of each partition 110 on the metalens 1 satisfies the following formula:

[0087]

[0088] Wherein, α is the angle between the main ray of the light beam projected in the partition 110 and the normal line of the metalens, which can also be called the deflection angle. That is to say, in this case, the phase distribution of each partition 110 on the metalens 1 is

[0089] It should be noted that in the design with a high uniformity of angle distribution, the angles of the light beams projected by each partition 110 in the observation area are required to be equal, that is, the lateral field of view angle U is evenly divided:

[0090] U = nβ; (7)

[0091] Where n is the total number of beams projected by the laser emitting device, and β is the lateral occupancy angle of each beam. At this time, when n is an odd number, the deflection angle α of the pth beam is p It is expressed as:

[0092] α p =pβ; (8)

[0093] Wherein, p is the serial number of the light beam projected by the laser emitting device, the serial number of the light beam with a deflection angle of 0° is set to 0, and the light beam emission direction is the vertical upward direction parallel to the paper surface, and the clockwise order is the increasing positive integer, and the counterclockwise order is the decreasing negative integer, such as Figure 5 As shown, the serial number of the positively emitted light beam is set to 0.

[0094] When n is an even number, the deflection angle α of the pth beam p It is expressed as:

[0095]

[0096] Wherein, p is the serial number of the light beam projected by the laser emitting device, with the normal of the super lens 1 where the symmetry axis of the array light source 2 is located, and the light beam emission direction is the vertical upward direction parallel to the paper surface, the serial number of the first clockwise light beam is set to +1, and then it is a positive integer that increases in sequence; the serial number of the first counterclockwise light beam is set to -1, and then it is a negative integer that decreases in sequence, such as Figure 4 shown.

[0097] In one embodiment, although the light beam modulated by the superlens 1 can achieve large-angle scanning in the x-axis direction, it cannot meet the large-angle scanning requirement in the y-direction. Therefore, in this embodiment, the superlens 1 is also used to split the light beam emitted by each light source partition 21 in the second direction of the plane where the superlens 1 is located, wherein the second direction is perpendicular to the first direction, that is, the second direction is actually the y-axis direction.

[0098] Specifically, the beam splitting process in the second direction is implemented by diffraction beam splitting, that is, the dot matrix replication method. The existing dot matrix replication usually adopts the M×N form of simultaneous replication in the second direction and the first direction. However, for the large-angle scanning method targeted by this application, the replication in the first direction does not meet the requirements of partition projection. Therefore, this application only adopts the M×1 second direction replication, such as Figure 7 As shown, Figure 7 A schematic diagram of a laser emitting device provided by an embodiment of the present application in a second direction is shown, Figure 7 It is actually a second direction replication of the 3×1 formula.

[0099] The diffraction phase of each partition on the metalens 1 is modulated by the above-mentioned lattice replication. The calculation can be performed using the GS algorithm (Gerchberg-Saxton algorithm) or the iterative Fourier transform algorithm. Figure 7In the figure, a light beam emitted by a sub-light source is split into three beams along the second direction. There are three replication areas distributed along the second direction, and the dot matrix distribution pattern corresponding to the sub-light source is repeated in each replication area. It is worth mentioning that when the metalens 1 is partitioned in the first direction, the collimation phase of each partition for the light beam has been designed. When calculating the diffraction phase, the input light intensity can be a plane wave or a collimated light beam, and then the diffraction phase of the metalens 1 used for lattice replication in the second direction can be calculated by the GS algorithm or the iterative Fourier algorithm. Therefore, in this case, the phase distribution of each partition 110 on the metalens 1 is

[0100] It should be noted that, since the array light source 2 in this embodiment is divided into a plurality of light source partitions 21 in the first direction, and the dividing line between adjacent light source partitions 21 is parallel to the second direction, it can be understood that each light source partition 21 is composed of a row of sub-light sources parallel to the second direction. For dot matrix replication in the second direction, it is not necessary to avoid the overlapping problem of the illumination areas of the sub-light sources in each light source partition. In the array light source 2, the illumination areas of each light source partition 21 in the first direction cannot overlap, and the illumination areas of the sub-light sources in the light source partition 21 in the array light source 2 in the second direction may overlap or may not overlap. In other words, the arrangement periods of the sub-light sources in the array light source 2 in the first direction and the second direction may be different. In this case, it is only necessary to pay attention to the arrangement period of the sub-light sources in the first direction, which reduces the difficulty of light source arrangement, simplifies the design process, and improves design efficiency.

[0101] In one embodiment, the array light source 2 is distributed in a plane, that is, all sub-light sources on the array light source 2 are arranged on the same plane, and the array light source 2 is arranged parallel to the super lens 1.

[0102] Specifically, Figure 8 As shown, Figure 8 A schematic diagram of a laser emitting device provided by an embodiment of the present application is shown. In this case, the metalens 1 does not need to be partitioned in the first direction. At this time, the phase of the metalens 1 is continuous, and the light beams projected by the array light source 2 set within a certain distance range can be collimated. The projection form of the light beams is that each light beam is deflected to the focus and collimated, and then projected to the observation area at a certain angle. Moreover, in this case, it is not necessary to distinguish whether the irradiation areas of each partitioned light source overlap, and the metalens 1 also provides a collimated phase as a whole.

[0103] Furthermore, in order to reduce the difficulty of regulating the superlens 1, a spherical mirror 3 can be arranged downstream of the superlens 1 along the propagation direction of the light path, such as Fig. 9 As shown, Fig. 9 A schematic diagram of a laser emitting device provided in an embodiment of the present application is shown, in which the spherical mirror 3 is used to receive the light beam modulated by the superlens 1, and to deflect the light beam modulated by the superlens 1 again in the first direction to achieve a larger deflection angle, so that the laser emitting device can have a larger field of view angle, and the detection range of the laser emitting device is larger.

[0104] It should be noted that, in the case of the above-mentioned planar distributed array light source 2, the lighting order of each light source partition 21 in the array light source 2 is opposite to the actual scanning order. And, in this case, the metalens 1 as a whole provides a collimated phase Satisfies any one of the above formulas (4) or (5); the superlens 1 may also include a diffraction phase in the second direction Therefore, the overall phase distribution of the metalens 1 in this case is:

[0105]

[0106] In an embodiment of the present application, if the minimum period of the micro-nano structure of the superlens in the manufacturing process is allowed to be very small. For example, the minimum period of the micro-nano structure is allowed to be less than 300nm. At this time, the superlens 1 has a larger maximum diffraction angle for most array light sources 2. Taking the array light source 2 as a common VCSEL light source with a working center wavelength of 940nm as an example, when the array light source 2 is not modified (that is, the array light source 2 is distributed in a plane), when the light beam emitted by the array light source 2 is incident, the maximum field of view angle of the light beam modulated by the superlens 1 can reach 140° (full angle), which meets most laser scanning requirements. At this time, the scanning requirements can be met by designing the superlens as a collimating lens as a whole, that is, as Figure 8 However, micro-nano structure periods less than 300nm require higher processing precision and low structural tolerance, which is not suitable for mass production. If a micro-nano structure period of 500nm with relatively wide requirements is adopted, it is only necessary to place the array light source as Figure 4 In the configuration, the first inclined portion and the second inclined portion are both offset by 10° relative to the metalens, so that the original maximum field of view angle of 69° can be expanded to nearly 95°, and the light beam within the maximum field of view angle has a higher diffraction efficiency.

[0107] In one embodiment, each sub-light source in the array light source 2 is a VCSEL light source (Vertical-Cavity Surface-Emitting Laser), that is, the array light source 2 is a VCSEL array light source.

[0108] The present application also provides a laser radar, which includes: a laser emitting device as described in the above embodiment; and a receiving device. Fig.10 As shown, Fig.10 A schematic diagram of the laser radar provided in this application is shown.

[0109] Example 1

[0110] The structure of the laser emitting device provided in Example 1 is as follows Figure 4 As shown, a VCSEL array light source with a working center wavelength of 940nm is used as the array light source 2, with a size of 4mm×8mm, and the first inclined portion and the second inclined portion of the array light source 2 are offset at an angle of 12° relative to the superlens 1; the distance between the superlens 1 and the array light source 2 is 2.75mm, the period of the micro-nano structure 12 of the superlens 1 is 500nm, the collimation focal length of the partition 110 on the superlens 1 is the distance between the light source exit point and the superlens 1, and 5 times replication is used in the second direction. Figure 11 to Figure 13 As shown, Fig.11 The local phase distribution diagram of the superlens 1 of the laser emitting device provided in Example 1 of the present application is shown. Fig.11 The phase distribution of the left and right subareas 110 in the local area is shown in FIG. Fig.12 shows the light intensity distribution diagram of the edge light beam projected by the laser emitting device provided in Example 1 of the present application, Fig.12 The scanning angle range of the laser emitting device in the first direction is 100°, Fig.12 The dotted box in the figure is the designed scanning area; if the bias angle of the array light source 2 is increased, the scanning angle range can be expanded. Fig.13 shows the light intensity distribution diagram of the edge light beam projected by the laser emitting device provided in Example 1 of the present application, Fig.13 The scanning angle range of the laser emitting device in the first direction is 120°, Fig.13 The dotted box in the figure is the designed scanning area.

[0111] Example 2

[0112] The structure of the laser emitting device provided in Example 2 is as follows Figure 8 As shown, a VCSEL array light source with a working center wavelength of 940nm is used as the array light source 2, with a size of 2mm×5mm. The distance between the superlens 1 and the array light source 2 is 14mm. The superlens 1 is designed to collimate the phase as a whole in the first direction, and 7 times the dot matrix is ​​replicated in the second direction. The local phase distribution of the superlens 1 is as shown in FIG. Fig.14 As shown, Fig.14The local phase distribution diagram of the metalens 1 of the laser emitting device provided in Example 2 of the present application is shown. Finally, the laser emitting device provided in Example 2 can perform scanning with a scanning angle range of 100°×40° (first direction×second direction), wherein the light intensity distribution of the edge light beam projected by the laser emitting device is as follows: Fig.15 As shown, Fig.15 The light intensity distribution diagram of the outermost light beam projected by the laser emitting device provided in Example 2 of the present application is shown.

[0113] Example 3

[0114] The structure of the laser emitting device provided in Example 3 is as follows Fig. 9 As shown, a metalens 1 and a spherical mirror 3 are used to collimate and deflect the light beam. In this embodiment, a VCSEL array light source with a working center wavelength of 905nm is used as the array light source 2, and the size is 4mm×5mm; the size of the metalens 1 is 8mm×11mm, and the distance between the metalens 1 and the array light source 2 is 2.75mm. The local phase distribution of the metalens 1 is as shown in Fig.16 As shown, Fig.16 The local phase distribution diagram of the metalens of the laser emitting device provided in Example 3 of the present application is shown; the surface curvature radius of the spherical mirror 3 is 4.6 mm, and the distance between the spherical mirror 3 and the metalens 1 is 3.96 mm; the light intensity distribution of the edge light beam projected by the laser emitting device is shown in FIG. Fig.17 As shown, Fig.17 The light intensity distribution diagram of the edge light beam projected by the laser emitting device provided in Example 3 of the present application is shown. Fig.17 It can be seen from the figure that when the collimation phase of the metalens 1 is designed as a whole in the first direction, the edge light beam projected by the laser emitting device has a large distortion.

[0115] 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 laser emission, characterized in that: The superlens comprises: a substrate and a micro-nano structure arranged on the substrate; In the effective region of the metalens, at least a partial region in a first direction is used to receive a light beam obliquely incident relative to the first direction, and the first direction is parallel to the effective region; The superlens is at least used to collimate and deflect the received light beam along the first direction.

2. The metalens according to claim 1, characterized in that In the effective area of ​​the super lens, the entire area in the first direction is used to receive light beams having the same inclination angle relative to the first direction.

3. The metalens according to claim 1, characterized in that The effective area of ​​the metalens includes at least two partitions in the first direction, the same partition is used to receive light beams with the same inclination angle relative to the first direction, and different partitions are used to receive light beams with different inclination angles relative to the first direction.

4. The metalens according to claim 3, characterized in that All partitions of the metalens in the first direction are symmetrically distributed about a center position of the effective area in the first direction.

5. A laser emitting device, characterized in that: The laser emitting device comprises: a superlens as described in any one of claims 1 to 4; and an array light source.

6. The laser emitting device according to claim 5, characterized in that: The effective area of ​​the metalens includes at least two partitions in the first direction, and the arrayed light source includes at least two light source partitions in the first direction; The number of partitions of the metalens is equal to the number of light source partitions of the array light source, and the partitions are matched one-to-one with the light source partitions; each of the partitions is used to receive and modulate the light beam emitted by the corresponding light source partition.

7. The laser emitting device according to claim 6, characterized in that: The array light source comprises a first inclined portion and a second inclined portion; All light source subareas on the first inclined portion are distributed on a first straight line inclined relative to the first direction, and all light source subareas on the second inclined portion are distributed on a second straight line inclined relative to the first direction, wherein the first straight line is inclined to the second straight line.

8. The laser emitting device according to claim 6, characterized in that: All light source partitions on the array light source are distributed in a curve relative to the first direction.

9. The laser emitting device according to claim 7 or 8, characterized in that: The arrayed light source is symmetrical in the first direction about a center position of the effective area in the first direction.

10. The laser emitting device according to claim 5, characterized in that: The effective area of ​​the metalens includes at least two partitions in the first direction; each partition is used to independently deflect an obliquely incident light beam.

11. The laser emitting device according to claim 5, characterized in that: The super lens is also used to perform beam splitting processing on the light beam emitted by each of the light source partitions in the second direction of the plane where the super lens is located; The second direction is perpendicular to the first direction.

12. A laser radar, characterized in that: The laser radar includes: a laser emitting device as described in claims 5-11; and a receiving device.

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