Laser radar and laser radar detection method

Abstract

The present invention discloses a laser radar (LIDAR) comprising: a rotating mirror unit including a multi-faceted rotating mirror portion, the multi-faceted rotating mirror portion being rotatable about a rotation axis and having multiple reflective surfaces for changing the angle of a light beam incident thereon; a transmitting unit configured to transmit a detection light beam; and a receiving unit configured to receive an echo after the detection light beam is reflected by a target object. The detection light beam is reflected by the reflective surface of the multi-faceted rotating mirror portion and then emitted; the echo is reflected by the reflective surface and then reaches the receiving unit. Furthermore, each reflective surface of the multi-faceted rotating mirror portion has the same scanning field of view. The embodiments of the present invention significantly suppress the motion blur effect present during laser radar measurement, thereby improving the measurement accuracy of the laser radar.

Description

Technical Field

[0001] The present disclosure relates to the field of radar, and in particular to a laser radar and a detection method of a laser radar. Background Art

[0002] LiDAR (LiDAR) is a radar system that uses laser beams to detect target position, velocity, and other characteristics. It is an advanced detection method that combines laser technology with photoelectric detection technology. Due to its high resolution, good concealment, strong resistance to active interference, excellent low-altitude detection performance, small size, and light weight, LiDAR is widely used in unmanned driving, drones, intelligent robots, transportation and communications, energy security monitoring, resource exploration, and other fields. With the rapid development of autonomous driving technology in recent years, LiDAR has become indispensable as a core sensor for distance perception in this field.

[0003] In the field of autonomous driving, automotive LiDAR, known as the "eyes" of autonomous vehicles, is one of the most important sensors and plays a crucial role in ensuring driving safety. LiDAR uses multiple laser pulses that rotate around an axis at a specific angle to measure distance to the surrounding environment. Combined with software, it creates a point cloud map, providing the autonomous vehicle with sufficient environmental information.

[0004] Rotating-mirror automotive LiDARs, such as multi-mirror LiDARs, are typically installed at the front or side of a vehicle. However, the point cloud stitching of these multi-mirror systems can be distorted by motion blur. Current solutions using multi-mirror systems often require stitching together point clouds scanned by multiple mirrors to obtain complete scan information for the field of view. However, this approach suffers from significant motion blur, which distorts the shape of moving objects.

[0005] For example, if there is an angle difference between the two sides of the two mirrors, the points scanned by the two sides are combined into one frame to improve the vertical resolution, such as Figure 1 The following figure shows a schematic diagram of a mosaic scan. At a 10Hz frame rate, the acquisition time span for a point on an object within the field of view reaches 50ms. A three-mirror mosaic would span 66.6ms, a four-mirror mosaic would span 75ms, and so on.

[0006] For example, in some scanning methods without splicing frames, Figure 2Taking the single-beam two-dimensional scanning shown in the figure as an example, in single-beam two-dimensional scanning, a fixed light source is usually used in combination with a scanning device. For example, two or more prisms are used to adjust the light beam output position by the relative rotation of the prisms to achieve scanning. In the single-beam two-dimensional scanning method, when the frame rate is 10Hz, the time span of the acquisition of a point on an object in the field of view may be close to 100ms. Therefore, it takes a long time to cover an area as a whole, which may cause a certain amount of motion blur in the entire scanned object.

[0007] The contents of the background technology section are merely the technologies known to the inventors and do not necessarily represent the existing technologies in this field. Summary of the Invention

[0008] The laser radar of the present invention significantly suppresses the motion blur effect produced by the laser radar during measurement by adopting one-dimensional rotating mirror scanning without framing, and solves the problems of point cloud distortion caused by obtaining scanning information through framing in the prior art, and field of view irregularities and large resolution differences among different points in the field of view caused by obtaining scanning information without framing.

[0009] To solve the above technical problems, an embodiment of the present invention provides a laser radar, comprising:

[0010] a rotating mirror unit comprising a multi-faceted rotating mirror portion, the multi-faceted rotating mirror portion being rotatable about a rotation axis and having a plurality of reflecting surfaces for changing an angle of a light beam incident thereon;

[0011] a transmitting unit configured to transmit a detection beam;

[0012] a receiving unit configured to receive an echo after the detection beam is reflected by a target object;

[0013] The detection beam is reflected by the reflective surface of the multifaceted mirror and then emitted; the echo is reflected by the reflective surface and then reaches the receiving unit; and the scanning field of view corresponding to each reflective surface of the multifaceted mirror is the same.

[0014] According to one aspect of the present invention, the laser radar also includes a processing unit, which is coupled to the receiving unit and configured to generate a frame of point cloud by acquiring an electrical signal generated by the receiving unit based on an echo reflected by any reflecting surface, and the multiple reflecting surfaces of the multi-faceted rotating mirror part are rotationally symmetric relative to the rotation axis.

[0015] According to one aspect of the present invention, the transmitting optical axis and the receiving optical axis are partially coaxial.

[0016] According to one aspect of the present invention, the laser radar also includes a spectroscopic component, the detection beam is reflected by the spectroscopic component to the rotating mirror unit, and the corresponding echo is transmitted by the spectroscopic component and received by the receiving unit; or the detection beam is transmitted by the spectroscopic component to the rotating mirror unit, and the corresponding echo is reflected by the spectroscopic component and received by the receiving unit.

[0017] According to one aspect of the present invention, the emission optical axis of the detection light beam emitted by the emitting unit and then reflected by the reflective surface of the polygonal mirror and the receiving optical axis of the echo wave reflected by the reflective surface and then reaching the receiving unit are independent of each other.

[0018] According to one aspect of the present invention, the rotating mirror unit also includes a motor and a rotating mirror frame for accommodating the multiple reflecting surfaces, and the motor is contained in the polygonal space surrounded by the reflecting surfaces to drive the multi-faceted rotating mirror part to rotate around its rotation axis, wherein the angle of at least one of the multiple reflecting surfaces is adjustable to achieve rotational symmetry of the multiple reflecting surfaces of the rotating mirror unit relative to the central axis.

[0019] According to one aspect of the present invention, the transmitting unit includes a transmitting module and a transmitting lens group; the transmitting module is configured to transmit a detection beam, and the detection beam passes through the transmitting lens group and the spectroscopic component and is emitted to the reflecting surface of the rotating mirror unit.

[0020] According to one aspect of the present invention, the transmitting unit further includes at least one first folding reflector, and the transmitting lens group includes a plurality of transmitting lenses arranged between the transmitting module and the first folding reflector, and between the first folding reflector and the spectroscopic component.

[0021] According to one aspect of the present invention, the receiving unit includes a receiving lens group and a receiving module; after the echo is reflected by any reflecting surface of the rotating mirror unit, it passes through the spectroscopic component and the receiving lens group and is incident on the receiving module.

[0022] According to one aspect of the present invention, the receiving unit further includes at least one second folding reflector, and the receiving lens group includes a plurality of receiving lenses arranged between the light splitting component and the second folding reflector, and between the second folding reflector and the receiving module.

[0023] According to one aspect of the present invention, the multi-faceted mirror portion includes two, three or four reflecting surfaces.

[0024] According to one aspect of the present invention, the transmitting module includes a plurality of lasers arranged in a linear array or a planar array, and the receiving unit includes a plurality of photodetectors having the same number as the lasers and a corresponding arrangement, wherein each photodetector corresponds to one of the lasers and is configured to receive an echo reflected on a target object by a detection beam emitted by the corresponding laser.

[0025] According to one aspect of the present invention, the plurality of lasers includes at least one laser provided with a microlens.

[0026] According to one aspect of the present invention, a laser provided with a microlens includes a plurality of light-emitting points, and each light-emitting point has a corresponding microlens structure.

[0027] According to one aspect of the present invention, the plurality of microlens structures are arranged corresponding to an arrangement pattern of the plurality of light-emitting points.

[0028] According to one aspect of the present invention, the angular span of the field of view of the entire transmitting unit in the horizontal direction is no greater than 10 degrees.

[0029] According to one aspect of the present invention, the mirror angles of the multiple reflective surfaces of the polygonal mirror portion in the vertical direction are configured to be adjustable.

[0030] The present invention also provides a laser radar detection method, which uses the laser radar as described above for detection.

[0031] According to one aspect of the present invention, the transmitting module includes a plurality of lasers arranged in a linear array or a planar array, and the plurality of lasers are divided into multiple groups. Each group of lasers is excited once or multiple times at each detection angle to obtain a point cloud combination arranged in a linear array or a planar array, and a frame of point cloud is generated based on the point cloud combination.

[0032] According to one aspect of the present invention, one or more groups of lasers are excited multiple times with different energies at partial detection angles to obtain point cloud information at short distances and long distances, and a frame of point cloud is generated based on the point cloud information.

[0033] In the above embodiment, by adopting a one-dimensional scanning rotating mirror laser radar without frame splicing, the point cloud information obtained on each mirror surface of the rotating mirror laser radar is generated into a complete frame of point cloud to complete the scanning of the entire field of view area, which significantly suppresses the motion blur effect existing in the laser radar during measurement and improves the measurement accuracy of the laser radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings, which constitute part of this disclosure, are used to provide a further understanding of the disclosure. The exemplary embodiments of the disclosure and their descriptions are used to explain the disclosure and do not constitute an improper limitation of the disclosure. In the accompanying drawings:

[0035] Figure 1 A schematic diagram of a frame stitching method for scanning by stitching frames in the prior art is shown;

[0036] Figure 2 A schematic diagram of a two-dimensional scan without framing is shown;

[0037] Figure 3 A schematic diagram of a laser radar according to an embodiment of the present invention is shown;

[0038] Figure 4 A block diagram of a laser radar according to an embodiment of the present invention is shown;

[0039] Figure 5 shows a schematic diagram of a rotating mirror unit according to one embodiment of the present invention;

[0040] Figure 6 shows an exploded view of a rotating mirror unit according to one embodiment of the present invention;

[0041] Figure 7 shows a schematic diagram of a rotating mirror unit according to another embodiment of the present invention;

[0042] Figure 8A A schematic diagram showing a detection beam of a double-sided rotating mirror portion at a start scanning position according to an embodiment of the present invention is shown;

[0043] Figure 8B Shown Figure 8A Schematic diagram of the echo of the double-sided rotating mirror part at the start scanning position;

[0044] Figure 9A A schematic diagram showing a detection beam of a double-sided rotating mirror portion at an end scanning position according to an embodiment of the present invention is shown;

[0045] Figure 9B Shown Figure 9A Schematic diagram of the echo of the double-sided rotating mirror portion at the end scanning position;

[0046] Figure 10A and Figure 10B FIG2 shows a schematic diagram of providing a microlens on a laser according to an embodiment of the present invention;

[0047] Figure 11A FIG. 1 is a schematic diagram showing a microlens structure provided on a laser light emitting point according to an embodiment of the present invention. Figure 11B Shown Figure 11A Preferred dimensional relationships of the embodiments;

[0048] Figure 12 A schematic diagram showing a microlens structure provided on a laser light emitting point according to another embodiment of the present invention is shown;

[0049] Figure 13 A schematic diagram showing motion distortion generated when single-beam two-dimensional scanning is used; and

[0050] Figure 14 A schematic diagram showing the motion distortion generated when using multi-beam one-dimensional scanning. DETAILED DESCRIPTION

[0051] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.

[0052] In the description of the present invention, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," "clockwise," "counterclockwise," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for the purpose of facilitating the description of the present invention and simplifying the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more of the aforementioned features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0053] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, removable, or integral connections; mechanical, electrical, or intercommunication connections; direct or indirect connections through an intermediary; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0054] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may also include the first and second features not being in direct contact but being in contact via another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or diagonally above the second feature, or may simply mean that the first feature is at a higher level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly above or diagonally above the second feature, or may simply mean that the first feature is at a lower level than the second feature.

[0055] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0056] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0057] Figure 3 FIG. 1 shows a schematic diagram of a laser radar 100 according to an embodiment of the present invention. Figure 3 As shown, the laser radar 100 includes a rotating mirror unit 200, a transmitting unit 300 and a receiving unit 400. The rotating mirror unit 200 includes a multi-faceted rotating mirror portion 210, and the multi-faceted rotating mirror portion 210 has a rotation axis OO' (see Figure 3 ), which can rotate around the rotation axis OO' and has a plurality of reflecting surfaces 211 (see Figure 3 ). Figure 3 In the figure, the multi-faceted mirror portion 210 is exemplarily shown as having two reflecting surfaces 211, but the present invention is not limited thereto, and the multi-faceted mirror portion 210 may also have other numbers of reflecting surfaces, such as 3, 4, 5 or more.

[0058] The multiple reflective surfaces 211 are used to change the angle of the light beam incident thereon, wherein the multiple reflective surfaces 211 of the polygonal mirror portion 210 are preferably rotationally symmetrical with respect to the rotation axis. In the present invention, "the multiple reflective surfaces 211 of the polygonal mirror portion 210 are rotationally symmetrical with respect to the rotation axis" means that after the polygonal mirror portion 210 is rotated by a certain angle about its rotation axis OO', the multiple reflective surfaces 211 of the polygonal mirror portion 210 can still overlap with the multiple reflective surfaces 211 before the rotation by the certain angle. Taking the example of the polygonal mirror portion 21 including two reflecting surfaces 211 (for example, 180 degrees opposite each other), the two reflecting surfaces 211 will overlap once every time the polygonal mirror portion 210 rotates 180 degrees; taking the example of the polygonal mirror portion 21 being a square and including four reflecting surfaces 211, the four reflecting surfaces 211 will overlap once every time the polygonal mirror portion 210 rotates 90 degrees; taking the example of the polygonal mirror portion 21 being a rectangle and including four reflecting surfaces 211, the four reflecting surfaces 211 will overlap once every time the polygonal mirror portion 210 rotates 180 degrees.

[0059] The transmitting unit 300 is configured to transmit a detection beam L1; the receiving unit 400 is configured to receive an echo L1' after the detection beam L1 is reflected by the target object OB and convert it into an electrical signal. The subsequent processing unit can calculate information such as the distance and / or reflectivity of the target object based on the electrical signal. The detection light beam L1 is reflected by the reflecting surface 211 of the multifaceted mirror portion 210 and then emitted, and the echo L1' is reflected by the reflecting surface 211 and then reaches the receiving unit 400; and the scanning field of view corresponding to each reflecting surface 211 of the multifaceted mirror portion 210 is the same, that is, during the rotation of the multifaceted mirror portion 210, for each reflecting surface 211, its working angle range is the same. Within this range, the detection light beam L1 is reflected by the reflecting surface to the outside of the laser radar, and the echo L1' is reflected by the reflecting surface and then incident on the receiving unit 400; outside this range, the transmitting unit 300 does not emit the detection light beam L1, and the receiving unit 400 also stops receiving the echo; or alternatively, outside this range, the processing unit will not calculate information such as the distance and / or reflectivity of the target object based on the electrical signal.

[0060] Figure 4 FIG. 1 shows a block diagram of a laser radar according to an embodiment of the present invention. Figure 4As shown, the laser radar 100 also includes a processing unit 500, which is coupled to the receiving unit 400 and configured to obtain the electrical signal generated by the receiving unit 400 based on the echo reflected by any reflective surface 211 of the rotating mirror unit 200, and generate a frame of point cloud. Therefore, according to a preferred embodiment of the present invention, by separately forming a frame of point cloud with the echo obtained from each reflective surface of the rotating mirror, there is no need to splice the echoes from multiple reflective surfaces. Specifically, when the laser radar 100 is in operation, the transmitting unit 300 transmits a detection beam L1 to the surrounding environment after being reflected by the rotating mirror unit 200. The emitted detection beam L1 is projected onto the target object OB, causing scattering. A portion of the detection beam is reflected back and converges to form an echo L1'. The receiving unit 400 receives the echo L1' reflected by the rotating mirror unit 200 and converts it into an electrical signal. The processing unit 500 analyzes and calculates the electrical signal to obtain the distance between the target object OB and the laser radar 100.

[0061] In addition, when the laser radar of the present invention is working, not every reflecting surface is used to generate a frame of point cloud. For example, only a part of the reflecting surfaces can be used to generate point clouds.

[0062] According to one embodiment of the present invention, Figure 3 As shown, the transmitting optical axis and the receiving optical axis of the laser radar 100 are partially coaxial. Optionally, the optical axis portions of the transmitting optical axis and the receiving optical axis that are emitted or incident through the rotating mirror unit 200 share the same optical axis, that is, the optical path of the detection light beam L1 after being reflected by one of the reflective surfaces 211 and the optical path of the echo L1' returning to the reflective surface 211 are the same or parallel. Alternatively, according to an alternative embodiment of the present invention, the transmitting optical axis and the receiving optical axis are not coaxial, that is, the transmitting optical axis of the detection light beam L1 emitted by the transmitting unit 300 and emitted after being reflected by the reflective surface 211 of the multi-faceted rotating mirror unit 210 and the receiving optical axis of the echo L1' after being reflected by the reflective surface and reaching the receiving unit 400 are independent of each other. For example, different areas on the reflective surface 211 can be used to transmit the detection light beam L1 and receive the echo L1', respectively. Preferably, a transmitting lens barrel and a receiving lens barrel are provided, both of which extend to the rotating mirror unit 200 and are used for transmitting the detection beam L1 and receiving the echo L1 ′ respectively. The axes of the transmitting lens barrel and the receiving lens barrel are independent of each other.

[0063] According to one embodiment of the present invention, Figure 3As shown, the laser radar 100 also includes a spectroscopic component 600, the detection beam L1 is reflected by the spectroscopic component 600 to the rotating mirror unit 200, and the corresponding echo L1' is transmitted by the spectroscopic component 600 and received by the receiving unit 400; or the detection beam L1 is transmitted by the spectroscopic component 600 to the rotating mirror unit 200, and the corresponding echo L1' is reflected by the spectroscopic component 600 and received by the receiving unit 400.

[0064] According to one embodiment of the present invention, the beam splitting component 600 is a semi-transparent, semi-reflective mirror, such as a reflector with an opening in the middle. Light beams incident on portions outside the opening are reflected, while light beams incident on the opening are transmitted. Alternatively, the beam splitting component 600 includes a polarization splitting structure, which causes the phase difference between the incoming and outgoing light beams to be half a wavelength, and transmits / reflects light beams of different wavelengths separately.

[0065] According to a preferred embodiment, the relative angles of the mirror surfaces 211 of the polygonal mirror 210 are adjusted to achieve a rotationally symmetric structure of the polygonal mirror 210 relative to the central axis. Figure 5 FIG. 4 shows a schematic diagram of a rotating mirror unit according to an embodiment of the present invention, Figure 6 FIG. 1 shows an exploded view of a rotating mirror unit according to an embodiment of the present invention. Figure 5 and Figure 6 As shown, the rotating mirror unit 200 further includes a motor 220 and a rotating mirror frame 230 for accommodating the multiple reflective surfaces 211. The motor 220 is contained within the polygonal space enclosed by the reflective surfaces 211 and is configured to drive the multi-faceted rotating mirror portion 210 to rotate about its rotation axis O1. The rotating mirror frame 230 is connected to and driven by the rotor of the motor 220. Optionally, the motor 220 is an integrated motor, and the multi-faceted rotating mirror portion 210 of the rotating mirror unit 200 is connected to the motor 220 via an elastic component 231, wherein the elastic component 231 is, for example, a disc spring, and the mirror angles of the multiple reflective surfaces 211 in the vertical direction are set to be adjustable by the disc spring.

[0066] Figure 7 FIG. 1 shows a schematic diagram of a rotating mirror unit according to another embodiment of the present invention. Figure 7 As shown, the rotating mirror unit 200 includes a motor 220, a multi-faceted rotating mirror portion 210, and a rotating mirror frame 230. The motor 220 is a split motor, and the rotating mirror frame 230 is connected to the motor 220 by a fixing bolt 232. The eccentric bolt 233 is used to adjust the mirror angle of the reflecting surface 211 on the left side of the figure in the vertical direction. Figure 7In the embodiment, the polygonal mirror portion 210 includes two reflecting surfaces 211 that are 180 degrees opposite to each other, thereby achieving rotational symmetry.

[0067] According to one embodiment of the present invention, Figure 3 As shown, the transmitting unit 300 includes a transmitting module 310 and a transmitting lens group 320, wherein the transmitting module 310 is configured to transmit a detection beam L1, and the detection beam L1 passes through the transmitting lens group 320 and the spectroscopic component 600 and is emitted to the reflecting surface 211 of the rotating mirror unit 200.

[0068] According to one embodiment of the present invention, Figure 3 As shown, the transmitting unit 300 further includes at least one first folding reflector 330. The at least one first folding reflector 330 is used to change the direction of the detection light beam L1 emitted by the transmitting module 310 so that the detection light beam L1 can be incident on the reflecting surface 211 after at least one reflection and then emitted to the surrounding environment.

[0069] According to one embodiment of the present invention, the emitting lens group 320 includes one or more lenses arranged between the emitting module 310 and the first folding reflector 330. Additionally or optionally, it may also include one or more emitting lenses arranged between the first folding reflector 330 and the spectrometer component 600.

[0070] According to one embodiment of the present invention, Figure 3 As shown, the receiving unit 400 includes a receiving lens group 420 and a receiving module 410 ; the echo L1 ′ is reflected by any reflective surface 211 of the rotating mirror unit 200 , and then passes through the light splitting component 600 and the receiving lens group 420 to enter the receiving module 410 .

[0071] According to one embodiment of the present invention, Figure 3 As shown, the receiving unit 400 also includes at least one second folding reflector 430. The at least one second folding reflector 430 is used to change the transmission direction of the echo L1' after being reflected by the reflective surface 211, so that the echo L1' can be received by the receiving module 410 after at least one reflection. The provision of the first folding reflector 330 and the second folding reflector 430 helps to make the structure of the transmitting unit and the receiving unit more compact, saving space.

[0072] According to one embodiment of the present invention, the receiving lens group 420 includes one or more receiving lenses arranged between the splitting component 600 and the second folding reflector 430. Additionally or alternatively, it may also include one or more receiving lenses between the second folding reflector 430 and the receiving module 410.

[0073] Figure 8A and 8B as well as Figure 9A and 9B Schematic diagrams of the optical paths of the double-sided rotating mirror portion at the start scanning and end scanning positions according to an embodiment of the present invention are shown respectively. Figure 8A and Figure 8B Schematic diagrams of the detection beam and echo when the polygon mirror is in the start scanning position are shown respectively. Figure 9A and Figure 9B Schematic diagrams of the detection beam and the echo when the polygonal mirror is in the end scanning position are respectively shown.

[0074] like Figure 8A 、 8B and Figure 9A 、 9B As shown, the multi-faceted mirror portion 210 includes two reflecting surfaces 211 (i.e., the long sides of the rectangular multi-faceted reflective portion 210 in the figure), and the multi-faceted mirror portion 210 can rotate around the rotation axis OO' along the direction indicated by the arrow R. Figure 8A and 8B The starting scanning position shown is rotated clockwise around the rotation axis OO' to Figure 9A and 9B The scanning end position is shown. The scanning angle of the light beam is twice the rotation angle of the polygon mirror 210, that is, Figure 8A and 8B The start scanning position shown is Figure 9A and 9B At the end scanning position shown, the polygon mirror portion 210 is horizontally rotated by 60°, and correspondingly, the emitted detection light beam L1 rotates through a horizontal field of view of 120°.

[0075] According to one embodiment of the present invention, the multi-faceted rotating mirror unit 210 includes three or four reflecting surfaces 211. Those skilled in the art will appreciate that the number of the reflecting surfaces 211 can be set to be greater as needed. Moreover, under the same frame rate, the more reflecting surfaces 211 are set, the slower the rotating mirror unit 200 needs to rotate, and thus it can have more flight time advantages. For example, when the laser radar 100 outputs 10 frames of point cloud in 1 second, the multi-faceted rotating mirror unit 210 with two reflecting surfaces 211 needs to rotate 5 times; the multi-faceted rotating mirror unit 210 with four reflecting surfaces 211 only needs to rotate 2.5 times. Obviously, under the same conditions, the rotation speed of the multi-faceted rotating mirror unit 210 with four reflecting surfaces 211 can be selected to be slower, thereby allocating more measurement time to each reflecting surface 211, thus having more flight time advantages and thus being able to have better distance measurement performance.

[0076] According to one embodiment of the present invention, the transmitting module 310 includes multiple lasers 311 arranged in a linear or planar array, and the receiving unit 400 includes multiple photodetectors, the same number as the lasers 311 and arranged in a corresponding manner. Each photodetector corresponds to one of the lasers 311 and is configured to receive the echo L1' reflected from the target object OB by the probe beam emitted by the corresponding laser 311. Optionally, the multiple lasers 311 can be arranged in a variety of ways, such as a single row, a double row, a staggered zigzag arrangement, etc., and the photodetectors are arranged accordingly to the arrangement of the lasers 311. The number of beams can vary depending on the actual required scanning accuracy. For example, a multi-beam transmission and reception mode with 32 beams, 64 beams, or 128 beams can be used to achieve higher measurement accuracy.

[0077] Figure 10A and Figure 10B FIG. 1 shows a schematic diagram of a laser according to an embodiment of the present invention provided with a microlens. Figure 10A and 10B As shown, the multiple lasers 311 include at least one laser 311 provided with a microlens 312. By providing the microlens 312 on the at least one laser 311, the collimation effect of the detection beam L1 can be improved, the horizontal angle can be constrained, and the light output energy utilization rate can be improved.

[0078] According to one embodiment of the present invention, a laser 311 provided with a microlens includes a plurality of light-emitting points 313, and each light-emitting point 313 has a corresponding microlens structure 314. Optionally, the laser 311 is a vertical cavity surface emitting laser (VCSEL). Compared with the edge-emitting laser (EEL) currently widely used in laser radars, the vertical cavity surface emitting laser (VCSEL) has the advantage of a spatially symmetrical distribution of divergence angles. VCSEL is used in laser radars, and the requirement of laser radars for high peak power has led to an increasing number of VCSELs adopting three-layer and five-layer quantum well structures to increase the emission power. However, due to the large divergence angle of VCSEL, the emission power density still cannot be significantly improved. Most existing VCSEL collimation schemes use a single large-aperture lens to collimate the entire VCSEL, which will result in an increase in the equivalent light-emitting surface and a decrease in power density. In an embodiment of the present invention, a separate or directly printed micro-lens array (MLA) is added to the light-emitting surface of the VCSEL. Unlike solutions that use a single lens to collimate the entire VCSEL, each lens unit in the micro-lens structure 314 of this embodiment collimates the laser beam emitted by each light-emitting point 313 separately, and the shape of the micro-lens is designed according to the arrangement of the light-emitting points 313. Figure 11AFIG. 1 is a schematic diagram showing a microlens structure provided on a laser light emitting point according to an embodiment of the present invention. Figure 11B Shown Figure 11A The preferred size relationship of the embodiment. Figure 11A As shown, the laser 311 includes a plurality of light-emitting points 313 distributed in a hexagonal pattern. Correspondingly, each of the microlens structures 314 is also arranged in a hexagonal pattern. Compared with the commonly used circular lenses, it is difficult to achieve dense arrangement of circular lens units. A portion of the detection beam will pass through the gaps, and this portion of light cannot be collimated, resulting in a loss of power density. Figure 11A and 11B As shown, the hexagonal microlens structure 314 matches the arrangement of the light-emitting points 313. The length of the inscribed circle diameter d2 of the hexagonal microlens structure 314 is equal to the center-to-center spacing d1 of adjacent light-emitting points 313 (i.e., the center-to-center spacing of the VCSEL's light-emitting units), i.e., d1 = d2. This achieves a dense arrangement and improves the VCSEL's light energy utilization. Optionally, the lens surface can be designed to be plano-convex, with the convex side being spherical or aspherical, depending on the collimation requirements. Furthermore, an anti-reflection coating at the VCSEL wavelength can be applied to either or both the flat and convex surfaces of the MLA to improve transmittance.

[0079] According to an embodiment of the present invention, the microlens structure 314 is arranged corresponding to the arrangement pattern of each light-emitting point 313 . Figure 12 FIG. 1 shows a schematic diagram of a microlens structure provided on a laser light emitting point according to another embodiment of the present invention. Figure 12 As shown, the laser 311 includes a plurality of light-emitting points 313 distributed in a quadrilateral pattern. Correspondingly, each microlens structure 314 is also configured as a quadrilateral structure. Similarly, for the light-emitting points distributed in a pentagonal pattern, a corresponding pentagonal microlens structure is configured. The same applies, and will not be further described here.

[0080] According to one embodiment of the present invention, the horizontal field of view of the transmitting unit 300 as a whole is less than or equal to 10 degrees. Optionally, the horizontal field of view of the transmitting and receiving channels can be controlled by designing the transmitting and receiving lines to be as narrow as possible in the horizontal direction and having as long a focal length as possible, so as to avoid excessive horizontal angles that affect the rotation angle of the code disk, thereby affecting the next scan.

[0081] The present invention also relates to a laser radar detection method, which uses the laser radar 100 for detection. According to one embodiment of the present invention, the transmitting module 310 includes multiple lasers 311 arranged in a linear array or a planar array. The multiple lasers 311 are divided into multiple groups. Each group of lasers is excited once or multiple times at each detection angle. Through multiple detections within a horizontal angle range, a point cloud combination arranged in a linear array or a planar array is obtained, and a frame of point cloud within the field of view is generated based on the point cloud combination.

[0082] According to one embodiment of the present invention, during detection, lasers arranged in multiple linear arrays are used to sequentially excite each group of detectors at each detection angle to obtain a linear array point cloud, and a frame of point cloud is generated based on the combination of the linear array point clouds at each detection angle.

[0083] According to one embodiment of the present invention, during detection, one or more groups of lasers are excited multiple times with different energies at some detection angles to obtain point cloud information at close range and long range, and a frame of point cloud is generated based on the point cloud information.

[0084] The advantages of the embodiments of the present invention are described below by way of example, taking an obstacle with a size of 2m*2m*2m at a distance of 50m from the laser radar 100 as an example, and the obstacle moving at a speed of 100km / h relative to the laser radar 100.

[0085] Figure 13 The figure shows the motion distortion caused by single beam two-dimensional scanning. Figure 14 As shown in the figure, when using single-beam 2D ​​scanning, taking a 10Hz frame rate and 100ms accumulation to obtain a single image frame, the time difference between the earliest and latest points hitting the obstacle in a single frame can be as much as 100ms. Considering the obstacle's movement distance of 100km / h, the obstacle moves 2.8 meters in 100ms. In other words, under this scanning method, the obstacle is distorted by up to 2.8 meters.

[0086] Figure 14 The figure shows the motion distortion caused by multi-beam one-dimensional scanning. Figure 14 As shown in the figure, under the same circumstances, using the multi-beam one-dimensional scanning method, the 2m width of the obstacle occupies a horizontal field of view of about 2.3° at a distance of 50m. When the horizontal scanning field of view range is 120° and the frame rate is 10HZ, the time to scan this angle is 33ms*(2.3 / 120)=0.63ms. At this time, the moving distance of the obstacle is 0.0175m.

[0087] Through the above comparison, it is obvious that the use of multi-beam one-dimensional scanning can better reduce the motion distortion existing in the laser radar measurement.

[0088] To sum up, the present invention uses a one-dimensional scanning rotating mirror laser radar without frame splicing to generate a complete frame of point cloud from the point cloud information obtained on each mirror surface of the rotating mirror laser radar, thereby completing the scanning of the entire field of view area, significantly suppressing the motion blur effect that exists in the laser radar during measurement, significantly reducing the object shape distortion caused by moving objects during measurement, and improving the measurement accuracy of the laser radar.

[0089] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A laser radar comprising: A rotating mirror unit, comprising a multi-faceted rotating mirror portion, the multi-faceted rotating mirror portion being rotatable about a rotation axis and having a plurality of reflecting surfaces for changing the angle of a light beam incident thereon, wherein the angle of at least one of the plurality of reflecting surfaces is adjustable to achieve rotational symmetry of the plurality of reflecting surfaces of the rotating mirror unit relative to the rotation axis, wherein the angle of the reflecting surface is a mirror angle of the reflecting surface in a vertical direction; a transmitting unit configured to transmit a detection beam; a receiving unit configured to receive an echo after the detection beam is reflected by a target object; a processing unit coupled to the receiving unit and configured to generate a frame of point cloud by acquiring an electrical signal generated by the receiving unit based on an echo reflected by any one of the reflecting surfaces, wherein the plurality of reflecting surfaces of the multi-faceted rotating mirror portion are rotationally symmetric with respect to the rotation axis; The detection beam is reflected by the reflective surface of the multifaceted mirror and then emitted; the echo is reflected by the reflective surface and then reaches the receiving unit; and the scanning field of view corresponding to each reflective surface of the multifaceted mirror is the same.

2. The laser radar according to claim 1, wherein: Its transmitting optical axis and receiving optical axis are partially coaxial.

3. The laser radar according to claim 2 further includes a spectroscopic component, wherein the detection beam is reflected to the rotating mirror unit through the spectroscopic component, and the corresponding echo is transmitted through the spectroscopic component and received by the receiving unit; or the detection beam is transmitted to the rotating mirror unit through the spectroscopic component, and the corresponding echo is reflected by the spectroscopic component and received by the receiving unit.

4. The laser radar according to claim 1, wherein: The emission optical axis of the detection light beam emitted by the emission unit and then reflected by the reflection surface of the polygonal mirror portion and the receiving optical axis of the echo wave reflected by the reflection surface and then reaching the receiving unit are independent of each other.

5. The laser radar according to any one of claims 2 to 4, wherein: The rotating mirror unit further includes a motor and a rotating mirror frame for accommodating the multiple reflecting surfaces. The motor is contained in a polygonal space surrounded by the reflecting surfaces to drive the multi-faceted rotating mirror portion to rotate around its rotation axis. 6 . The laser radar according to claim 1 , wherein the mirror angles of the multiple reflecting surfaces of the multi-faceted rotating mirror portion in the vertical direction are configured to be adjustable.

7. The laser radar according to claim 3, wherein the transmitting unit includes a transmitting module and a transmitting lens group; the transmitting module is configured to transmit a detection beam, and the detection beam passes through the transmitting lens group and the spectroscopic component and is emitted to the reflecting surface of the rotating mirror unit.

8. The laser radar according to claim 7, wherein: The transmitting unit further includes at least one first folding reflector, and the transmitting lens group includes a plurality of transmitting lenses arranged between the transmitting module and the first folding reflector, and between the first folding reflector and the light splitting component.

9. The laser radar according to claim 7, wherein: The receiving unit includes a receiving lens group and a receiving module; after the echo is reflected by any reflecting surface of the rotating mirror unit, it passes through the light splitting component and the receiving lens group and is incident on the receiving module.

10. The laser radar according to claim 9, wherein: The receiving unit further includes at least one second folding reflector, and the receiving lens group includes a plurality of receiving lenses arranged between the light splitting component and the second folding reflector and between the second folding reflector and the receiving module.

11. The laser radar according to claim 1, wherein: The multi-faceted rotating mirror portion includes two, three or four reflecting surfaces.

12. The laser radar according to claim 9, wherein: The transmitting module includes multiple lasers arranged in a linear array or a planar array, and the receiving unit includes multiple photodetectors with the same number as the lasers and a corresponding arrangement, wherein each photodetector corresponds to one of the lasers and is configured to receive the echo reflected by the target object from the detection beam emitted by the corresponding laser.

13. The laser radar according to claim 12, wherein: The plurality of lasers include at least one laser provided with a microlens.

14. The laser radar according to claim 12, wherein: The laser with microlens includes multiple light-emitting points, and each light-emitting point has a corresponding microlens structure.

15. The laser radar according to claim 14, wherein: The plurality of microlens structures are arranged corresponding to the arrangement pattern of the plurality of light-emitting points.

16. The laser radar according to claim 1, wherein the field of view angle span of the transmitting unit as a whole in the horizontal direction is no more than 10 degrees.

17. A laser radar detection method, wherein the laser radar according to any one of claims 1 to 16 is used for detection.

18. The detection method according to claim 17, wherein the transmitting unit includes a transmitting module, the transmitting module includes a plurality of lasers arranged in a linear array or a planar array, the plurality of lasers are divided into a plurality of groups, each group of lasers is excited once or multiple times at each detection angle to obtain a point cloud combination arranged in a linear array or a planar array, and a frame of point cloud is generated based on the point cloud combination.

19. The detection method according to claim 18, wherein one or more groups of lasers are excited multiple times with different energies at some detection angles to obtain point cloud information at close range and long range, and a frame of point cloud is generated based on the point cloud information.

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