CN215641806U

CN215641806U - Laser radar

Info

Publication number: CN215641806U
Application number: CN202120917490.7U
Authority: CN
Inventors: 曾昭明; 向少卿
Original assignee: Hesai Technology Co Ltd
Current assignee: Hesai Technology Co Ltd
Priority date: 2021-04-30
Filing date: 2021-04-30
Publication date: 2022-01-25
Anticipated expiration: 2031-04-30

Abstract

The utility model discloses a laser radar, comprising: a mirror unit including a polygon mirror portion rotatable about a rotation axis and having a plurality of reflection surfaces for changing an angle of a light beam incident thereon; a transmitting unit configured to transmit a probe beam; the receiving unit is configured to receive the echo of the probe beam after being reflected by the target object; the detection light beam is reflected by a reflecting surface of the multi-surface rotating mirror part and then is emitted; the echo reaches the receiving unit after being reflected by the reflecting surface; and the scanning field ranges corresponding to the reflecting surfaces of the multi-surface rotating mirror part are the same. By the embodiment of the utility model, the motion blur effect of the laser radar during measurement is obviously inhibited, and the measurement precision of the laser radar is improved.

Description

Laser radar

Technical Field

The present disclosure relates to the field of radar, and more particularly, to a laser radar.

Background

The laser radar is a radar system for detecting characteristic quantities such as target position, speed and the like by emitting laser beams, and is an advanced detection mode combining a laser technology and a photoelectric detection technology. The laser radar has the characteristics of high resolution, good concealment, strong active interference resistance, good low-altitude detection performance, small volume, light weight and the like, and is widely applied to the fields of unmanned driving, unmanned aerial vehicles, intelligent robots, traffic communication, energy safety detection, resource exploration and the like. With the rapid development of automatic driving technology in recent years, lidar has become indispensable as a core sensor for distance sensing in the field of automatic driving.

In the field of automatic driving, a vehicle-mounted laser radar is one of the most important sensors as the 'eyes' of an automatic driving automobile, and has important significance for ensuring the driving safety of the automatic driving automobile. The laser radar can adopt a plurality of laser pulses to rotate around a shaft by a certain angle so as to detect the distance of the surrounding environment, and draw a point cloud picture by combining software, thereby providing enough environment information for the automatic driving automobile.

The vehicle-mounted laser radar with a rotating mirror is usually arranged at the front end or the side of the vehicle, such as a polygon mirror laser radar. However, polygon mirror point cloud stitching can produce point cloud distortion due to motion blur effects. In the current scheme of adopting a polygon mirror, point clouds obtained by scanning a plurality of mirror surfaces are often needed to be spliced to obtain complete scanning information of a field area. However, this method has a serious motion blur effect, i.e., the shape of the object is distorted when a moving object is measured.

For example, two surfaces of two mirrors have an angle difference, and the scanned points from the two surfaces are combined into a frame to improve the vertical resolution, as shown in the frame splicing diagram of fig. 1. At a frame rate of 10Hz, at a point on an object in the field of view, the time span for acquisition may reach 50 ms. The time span of three-surface mirror framing can reach 66.6ms, the time span of four-surface mirror framing can reach 75ms, and the like.

For another example, in some scanning methods without framing, a single-beam two-dimensional scanning as shown in fig. 2 is taken as an example, but in the beam two-dimensional scanning, a fixed light source is usually combined with a scanning device to realize the scanning. For example, two or more prisms are used to adjust the beam exit position by relative rotation of the prisms to achieve scanning. In a single beam two-dimensional scanning mode, the time span for acquisition of a point on an object within the field of view may be close to 100ms when the frame rate is 10 Hz. Therefore, it takes a long time to cover an area as a whole, which may cause some motion blur of the whole object scanned.

The statements in the background section are merely prior art as they are known to the inventors and do not, of course, represent prior art in the field.

SUMMERY OF THE UTILITY MODEL

According to the laser radar, the one-dimensional rotating mirror scanning without splicing frames is adopted, so that the motion blur effect generated by the laser radar during measurement is obviously inhibited, and the problems of point cloud distortion caused by obtaining scanning information through splicing frames, special view field caused by obtaining the scanning information without splicing frames, large resolution difference at each position in the view field and the like in the prior art are solved.

To solve the above technical problem, an embodiment of the present invention provides a laser radar, including:

a mirror unit including a polygon mirror portion rotatable about a rotation axis and having a plurality of reflection surfaces for changing an angle of a light beam incident thereon;

a transmitting unit configured to transmit a probe beam;

the receiving unit is configured to receive the echo of the probe beam after being reflected by the target object;

the detection light beam is reflected by a reflecting surface of the multi-surface rotating mirror part and then is emitted; the echo reaches the receiving unit after being reflected by the reflecting surface; and the scanning field ranges corresponding to the reflecting surfaces of the multi-surface rotating mirror part are the same.

According to an aspect of the present invention, the lidar further includes a processing unit coupled to the receiving unit and configured to generate a frame of point cloud by acquiring an electric signal generated by the receiving unit based on an echo reflected by any one of the reflection surfaces, the plurality of reflection surfaces of the polygonal mirror portion being rotationally symmetric with respect to the rotation axis.

According to one aspect of the utility model, the emission optical axis and the receiving optical axis are coaxial.

According to an aspect of the present invention, the laser radar further includes a beam splitting component, the probe beam is reflected to the mirror unit through the beam splitting component, and a corresponding echo is transmitted through the beam splitting component and received by the receiving unit; or the detection beam is transmitted to the rotating mirror unit through the light splitting component, and the corresponding echo is reflected by the light splitting component and received by the receiving unit.

According to an aspect of the present invention, a transmission optical axis from which the probe beam transmitted by the transmission unit is reflected by a reflection surface of the polygon mirror portion and a reception optical axis from which the echo is reflected by the reflection surface and reaches the reception unit are independent of each other.

According to an aspect of the utility model, the turning mirror unit further comprises a motor and a turning mirror frame for accommodating the plurality of reflecting surfaces, the motor is contained in a polygonal space surrounded by the reflecting surfaces to drive the multi-surface turning mirror part to rotate around a rotating axis thereof, wherein an angle of at least one reflecting surface of the plurality of reflecting surfaces is adjustable to realize rotational symmetry of the plurality of reflecting surfaces of the turning mirror unit with respect to the central axis.

According to one aspect of the present invention, the emission unit includes an emission module and an emission lens group; the emitting module is configured to emit a probe beam, and the probe beam is emitted to the reflecting surface of the rotating mirror unit through the emitting lens group and the light splitting component.

According to an aspect of the utility model, the emission unit further comprises at least one first turning mirror, and the emission lens group comprises a plurality of emission lenses disposed between the emission module and the first turning mirror, and between the first turning mirror and the light splitting component.

According to an aspect of the present invention, the receiving unit includes a receiving lens group and a receiving module; and the echo is reflected by any reflecting surface of the rotating mirror unit and then enters the receiving module through the light splitting assembly and the receiving lens group.

According to an aspect of the present invention, the receiving unit further includes at least one second turning mirror, and the receiving lens group includes a plurality of receiving lenses disposed between the light splitting assembly and the second turning mirror, and between the second turning mirror and the receiving module.

According to an aspect of the utility model, the polygon mirror portion includes two, three or four reflecting surfaces.

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

According to an aspect of the utility model, the plurality of lasers includes at least one laser provided with a microlens.

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

According to an aspect of the present invention, a plurality of the microlens structures are disposed corresponding to an arrangement pattern of the plurality of light emitting points.

According to an aspect of the present invention, the field angle span in the horizontal direction of the entire emission unit is not more than 10 degrees.

According to an aspect of the present invention, a mirror surface angle of the plurality of reflection surfaces of the polygon mirror portion in the vertical direction is configured to be adjustable.

The utility model also provides a detection method of the laser radar, which uses the laser radar to detect.

According to one aspect of the utility model, the transmitting module comprises a plurality of lasers arranged in a linear array or an area array, the plurality of lasers are divided into a plurality of groups, each group of lasers is excited once or repeatedly at each detection angle, a point cloud combination arranged in a linear array or an area array is obtained, and a frame of point cloud is generated according to the point cloud combination.

According to one aspect of the utility model, one or more sets of lasers are activated multiple times at different energies at portions of the detection angle to obtain near and far distance point cloud information, and a frame of point cloud is generated from the point cloud information.

In the embodiment, the one-dimensional scanning mirror-rotating laser radar without frame splicing is adopted, and the point cloud information obtained on each mirror surface of the mirror-rotating laser radar is generated into a complete frame of point cloud to complete the scanning of the whole field area, so that the motion blur effect of the laser radar during measurement is obviously inhibited, and the measurement precision of the laser radar is improved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure. In the drawings:

FIG. 1 is a diagram illustrating a prior art framing scheme for scanning by framing;

FIG. 2 shows a schematic diagram of a two-dimensional scan without framing;

FIG. 3 shows a schematic diagram of a lidar in accordance with one embodiment of the utility model;

FIG. 4 shows a block diagram of a lidar in accordance with one embodiment of the utility model;

FIG. 5 shows a schematic view of a turning mirror unit according to an embodiment of the utility model;

FIG. 6 shows an exploded view of a rotating mirror unit according to one embodiment of the present invention;

FIG. 7 shows a schematic view of a turning mirror unit according to another embodiment of the utility model;

FIG. 8A shows a schematic diagram of a probe beam at a start scan position of a double-sided mirror segment in accordance with one embodiment of the present invention;

FIG. 8B shows a schematic diagram of the echo of the double-sided mirror portion of FIG. 8A at the start of a scan position;

FIG. 9A shows a schematic view of a probe beam at the end of a scan position of a double-sided mirror segment in accordance with one embodiment of the present invention;

FIG. 9B shows a schematic diagram of the echo of the double-sided mirror portion of FIG. 9A at the end of the scanning position;

FIGS. 10A and 10B illustrate a schematic view of a laser with a microlens disposed thereon, in accordance with one embodiment of the present invention;

FIG. 11A is a schematic diagram showing a micro-lens structure disposed on a light emitting point of a laser according to an embodiment of the present invention, and FIG. 11B is a diagram showing a preferred dimensional relationship of the embodiment of FIG. 11A;

FIG. 12 is a schematic diagram showing a microlens structure disposed on a light emitting point of a laser according to another embodiment of the present invention;

FIG. 13 is a schematic diagram showing the motion distortion caused by two-dimensional scanning with a single beam; and

figure 14 shows a schematic representation of the motion distortion that occurs when one-dimensional scanning with a multi-beam is used.

Detailed Description

In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the description of the present invention, it should be noted that unless otherwise explicitly stated or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection, either mechanically, electrically, or in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly above and obliquely above the second feature, or simply meaning that the first feature is at a lesser level than the second feature.

The following disclosure provides many different embodiments or examples for implementing different features of the utility model. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or uses of other materials.

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.

Fig. 3 shows a schematic diagram of a lidar 100 according to an embodiment of the utility model. As shown in fig. 3, the laser radar 100 includes a turning mirror unit 200, a transmitting unit 300, and a receiving unit 400. Wherein the mirror unit 200 includes a polygon mirror portion 210, the polygon mirror portion 210 having a rotation axis OO '(see fig. 3), being rotatable about the rotation axis OO', and having a plurality of reflecting surfaces 211 (see fig. 3). In fig. 3, the polygon mirror portion 210 is exemplarily shown to have two reflecting surfaces 211, but the present invention is not limited thereto, and may have other numbers of reflecting surfaces, for example, 3, 4, 5 or more.

The plurality of reflection surfaces 211 serve to change the angle of the light beam incident thereon, wherein the plurality of reflection surfaces 211 of the polygon mirror portion 210 are preferably rotationally symmetric with respect to the rotation axis. In the present invention, the phrase "the plurality of reflection surfaces 211 of the polygon mirror portion 210 are rotationally symmetrical with respect to the rotation axis" means that the plurality of reflection surfaces 211 of the polygon mirror portion 210 can still coincide with the plurality of reflection surfaces 211 before the rotation of the polygon mirror portion 210 by a certain angle after the polygon mirror portion 210 rotates by a certain angle around the rotation axis OO'. Taking the case where the polygon mirror portion 21 includes two reflecting surfaces 211 (for example, 180 degrees opposite to each other), every time the polygon mirror portion 210 rotates 180 degrees, the two reflecting surfaces 211 will coincide; taking the polygon mirror part 21 as a square and including four reflecting surfaces 211 as an example, every time the polygon mirror part 210 rotates 90 degrees, the four reflecting surfaces 211 will coincide once; taking the polygon mirror 21 as a rectangle and including four reflection surfaces 211 as an example, the four reflection surfaces 211 are overlapped once every 180 degrees of rotation of the polygon mirror 210.

The emitting unit 300 is configured to emit a probe light beam L1; the receiving unit 400 is configured to receive the echo L1' of the probe beam L1 reflected by the object OB and convert the echo into an electrical signal, and a subsequent processing unit may calculate information such as the distance and/or reflectivity of the object according to the electrical signal. The probe light beam L1 is reflected by the reflection surface 211 of the polygon mirror part 210 and then exits, and the echo L1' is reflected by the reflection surface 211 and then reaches the receiving unit 400; moreover, the scanning field ranges corresponding to the respective reflection surfaces 211 of the polygon mirror portion 210 are the same, that is, during the rotation of the polygon mirror portion 210, the working angle range of each reflection surface 211 is the same, within which the probe light beam L1 is reflected by the reflection surface to the outside of the laser radar, and the echo L1' is reflected by the reflection surface and then enters the receiving unit 400; while outside this range, the transmitting unit 300 does not transmit the probe light beam L1, and the receiving unit 400 also stops receiving the echo; or alternatively, outside this range, the processing unit does not calculate information such as distance and/or reflectivity of the target object from the electrical signal.

FIG. 4 shows a block diagram of a lidar in accordance with one embodiment of the utility model. As shown in fig. 4, the lidar 100 further includes a processing unit 500, and the processing unit 500 is coupled to the receiving unit 400 and configured to acquire an electrical signal generated by the receiving unit 400 based on an echo reflected by any one of the reflecting surfaces 211 of the turning mirror unit 200, and generate a frame of point cloud. Therefore, according to the preferred embodiment of the present invention, the echo obtained by each reflecting surface of the rotating mirror is individually formed into a frame point cloud, and the frame splicing by the echoes of a plurality of reflecting surfaces is not required. Specifically, when the laser radar 100 is in operation, the transmitting unit 300 emits the probe beam L1 to the surrounding environment through reflection of the turning mirror unit 200, the emitted probe beam L1 is projected on the object OB to cause scattering, and a part of the probe beam is reflected back and converged to form the echo L1'. The receiving unit 400 receives the echo L1' reflected by the turning 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 object OB and the laser radar 100.

In addition, when the laser radar of the present invention is in operation, not every reflecting surface is used to generate a frame of point cloud, for example, only a portion of the reflecting surfaces may be used to generate the point cloud.

According to an embodiment of the present invention, as shown in fig. 3, the transmitting optical axis and the receiving optical axis of the lidar 100 are coaxial. Alternatively, the optical axis portions of the transmitting optical axis and the receiving optical axis, which are emitted or incident via the turning mirror unit 200, share the same optical axis, that is, the optical path of the probe light beam L1 reflected by one of the reflecting surfaces 211 is the same as or parallel to the optical path of the echo L1' returning to the reflecting surface 211. Or 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 probe light beam L1 emitted by the transmitting unit 300 after reaching the reflecting surface 211 of the polygon mirror portion 210 and being reflected and then emitted and the receiving optical axis of the echo L1' after being reflected by the reflecting surface and reaching the receiving unit 400 are independent of each other. For example, different regions on the reflecting surface 211 may be utilized for emitting the probe light beam L1 and receiving the echo L1', respectively. Preferably, a transmitting lens barrel and a receiving lens barrel, both extending to the rotating mirror unit 200, are provided for transmitting the probe beam L1 and receiving the echo L1', respectively, with their axes independent from each other.

According to an embodiment of the present invention, as shown in fig. 3, the laser radar 100 further includes a beam splitting assembly 600, the probe beam L1 is reflected to the mirror unit 200 through the beam splitting assembly 600, and the corresponding echo L1' is transmitted through the beam splitting assembly 600 and received by the receiving unit 400; or the probe light beam L1 is transmitted to the turning mirror unit 200 through the light splitting assembly 600, and the corresponding echo L1' is reflected by the light splitting assembly 600 and received by the receiving unit 400.

According to an embodiment of the present invention, the light splitting assembly 600 is a half mirror, such as a mirror with an opening in the middle, and the light beam incident on the portion outside the opening will be reflected and the light beam incident on the opening will be transmitted. Or alternatively, the light splitting assembly 600 includes a polarization light splitting structure, so that the difference between the outgoing and incident light beams is half wavelength, and the light beams with different wavelengths are transmitted/reflected respectively.

According to a preferred embodiment, the rotational symmetry of the entire polygon mirror 210 with respect to the central axis is achieved by adjusting the relative angles of the respective mirror surfaces 211 of the polygon mirror 210. Fig. 5 shows a schematic view of a mirror turning unit according to an embodiment of the present invention, and fig. 6 shows an exploded view of a mirror turning unit according to an embodiment of the present invention. As shown in fig. 5 and 6, the mirror rotating unit 200 further includes a motor 220 and a mirror rotating frame 230 for accommodating the plurality of reflecting surfaces 211, the motor 220 is contained in a polygonal space surrounded by the reflecting surfaces 211 and configured to drive the multi-faceted mirror portion 210 to rotate around the rotation axis O1, and the mirror rotating frame 230 is connected to a rotor of the motor 220 and is driven by the rotor of the motor 220. Alternatively, the motor 220 is an integrated motor, and the multi-surface mirror portion 210 of the mirror unit 200 is connected to the motor 220 through an elastic member 231, wherein the elastic member 231 is, for example, a disc spring, and the mirror surface angle of the plurality of reflective surfaces 211 in the vertical direction is set to be adjustable through the disc spring.

Fig. 7 shows a schematic view of a turning mirror unit according to another embodiment of the utility model. As shown in fig. 7, the mirror rotating unit 200 includes a motor 220, a polygon mirror portion 210, and a mirror rotating frame 230. The motor 220 is a split motor, the rotating frame 230 is connected with the motor 220 through a fixing bolt 232, and the mirror surface angle of the reflecting surface 211 on the left side in the figure in the vertical direction is adjusted through an eccentric bolt 233. In the embodiment of fig. 7, the polygonal mirror portion 210 includes two reflecting surfaces 211 opposed at 180 degrees, achieving rotational symmetry.

According to an embodiment of the present invention, as shown in fig. 3, the emitting unit 300 includes an emitting module 310 and an emitting lens group 320, wherein the emitting module 310 is configured to emit a probe light beam L1, and the probe light beam L1 exits to the reflecting surface 211 of the rotating mirror unit 200 through the emitting lens group 320 and the light splitting component 600.

According to one embodiment of the present invention, as shown in fig. 3, the emission unit 300 further includes at least one first turning mirror 330. The at least one first turning mirror 330 is configured to change a direction of the probe light beam L1 emitted from the emitting module 310, so that the probe light beam L1 can be incident on the reflecting surface 211 after being reflected at least once and be emitted to the surrounding environment.

According to an embodiment of the present invention, the emission lens group 320 includes one or more lenses disposed between the emission module 310 and the first folding mirror 330, and additionally or alternatively, may also include one or more emission lenses disposed between the first folding mirror 330 and the light splitting assembly 600.

According to an embodiment of the present invention, as shown in fig. 3, the receiving unit 400 includes a receiving lens group 420 and a receiving module 410; the echo L1' is reflected by any one of the reflecting surfaces 211 of the turning mirror unit 200, and then enters the receiving module 410 through the beam splitter assembly 600 and the receiving lens group 420.

According to an embodiment of the present invention, as shown in fig. 3, the receiving unit 400 further includes at least one second turning mirror 430. The at least one second turning mirror 430 is configured to change a transmission direction of the echo L1 'after being reflected by the reflection surface 211, so that the echo L1' can be received by the receiving module 410 after being reflected at least once. By providing the first turning mirror 330 and the second turning mirror 430, the structural design of the transmitting unit and the receiving unit can be more compact, and the space can be saved.

According to an embodiment of the present invention, the receiving lens group 420 includes one or more receiving lenses disposed between the light splitting assembly 600 and the second turning mirror 430, and additionally or alternatively, may also include one or more receiving lenses between the second turning mirror 430 and the receiving module 410.

Fig. 8A and 8B and fig. 9A and 9B show schematic diagrams of optical paths of the double-sided mirror portion at a start scanning position and an end scanning position, respectively, according to an embodiment of the present invention, wherein fig. 8A and 8B show schematic diagrams of the probe beam and the echo when the multi-sided mirror portion is at the start scanning position, respectively, and fig. 9A and 9B show schematic diagrams of the probe beam and the echo when the multi-sided mirror portion is at the end scanning position, respectively.

As shown in fig. 8A and 8B and fig. 9A and 9B, the polygon mirror portion 210 includes two reflecting surfaces 211 (i.e., long sides of the polygon mirror portion 210 having a rectangular shape in the drawing), and the polygon mirror portion 210 is rotatable around a rotation axis OO' in a direction indicated by an arrow R. The polygon mirror portion 210 rotates about the rotation axis OO' in a clockwise direction from the start scanning position shown in fig. 8A and 8B to the end scanning position shown in fig. 9A and 9B. In which the beam scannable angle is twice the rotation angle of the polygon mirror portion 210, that is, the polygon mirror portion 210 is horizontally rotated by 60 ° from the start scanning position shown in fig. 8A and 8B to the end scanning position shown in fig. 9A and 9B, and accordingly, the outgoing probe beam L1 is rotated through the horizontal field of view of 120 °.

According to an embodiment of the present invention, the polygon mirror portion 210 includes three or four reflecting surfaces 211. Those skilled in the art will appreciate that the number of the reflecting surfaces 211 may be more as required. And under the same frame rate, the greater the number of the reflecting surfaces 211, the slower the rotation speed of the mirror rotating unit 200 is required to rotate, so that the advantage of more flight time can be obtained. For example, in the case that the laser radar 100 generates 10 frames of point cloud in 1s, the polygon mirror portion 210 having the two reflection surfaces 211 needs to rotate 5 turns; the polygon mirror portion 210 having the four reflecting surfaces 211 need only rotate 2.5 turns. Obviously, under the same conditions, the rotation speed of the polygon mirror portion 210 having four reflecting surfaces 211 can be selected to be slower, so as to distribute more measuring time on each reflecting surface 211, and therefore have more flight time advantages, so as to have better distance measuring performance.

According to an embodiment of the present invention, wherein the transmitting module 310 includes a plurality of lasers 311 arranged in a linear array or an area array, the receiving unit 400 includes a plurality of photodetectors corresponding to the same number of lasers 311 and arranged in a corresponding manner, wherein each photodetector corresponds to one of the lasers 311 and is configured to receive an echo L1' reflected by the probe beam emitted by the corresponding laser 311 on the object OB. Alternatively, the plurality of lasers 311 may be arranged in various manners, such as single column, double column, zigzag staggered arrangement, and the like, and the photodetectors are arranged in accordance with the arrangement manner of the lasers 311. The number of the beam can be different according to the actually required scanning precision. For example, a multi-beam transceiving mode of 32 lines, 64 lines and 128 lines is adopted, so that higher measurement accuracy is achieved.

Fig. 10A and 10B show schematic diagrams of disposing a microlens on a laser according to an embodiment of the present invention. As shown in fig. 10A and 10B, wherein the plurality of lasers 311 includes at least one laser 311 provided with a microlens 312. By arranging the micro lens 312 on the at least one laser 311, the collimation effect of the probe light beam L1 can be improved, the restriction on the horizontal angle is realized, and the utilization rate of the light-emitting energy can be improved.

According to an embodiment of the present invention, the laser 311 provided with the micro lens includes a plurality of light emitting points 313, and each light emitting point 313 has a corresponding micro lens structure 314. Optionally, the laser 311 is a Vertical Cavity Surface Emitting Laser (VCSEL). Compared with an Edge Emitting Laser (EEL) widely used in the laser radar at present, a Vertical Cavity Surface Emitting Laser (VCSEL) has the advantage of spatially symmetrical distribution of divergence angles. The VCSEL is applied in the lidar, and the requirement of the lidar for high peak power causes more and more VCSELs to adopt a three-layer junction and five-layer junction quantum well structure to increase the emission power. However, the emission power density cannot be greatly increased due to the large VCSEL divergence angle. Most of the existing VCSEL collimation schemes adopt a single large-aperture lens to collimate the whole VCSEL, so that an equivalent light emitting surface is enlarged, and the power density is reduced. In the embodiment of the present invention, unlike the scheme of collimating the whole VCSEL by using one lens, a separate or directly-imprinted micro-lens array (MLA) is additionally disposed on the light emitting surface of the VCSEL, and each lens unit in the micro-lens structure 314 in the embodiment collimates the laser beam emitted from each light emitting point 313, and designs the shape of the micro-lens according to the arrangement of the light emitting points 313. Fig. 11A shows a schematic diagram of a micro-lens structure arranged on a light emitting point of a laser according to an embodiment of the utility model, and fig. 11B shows a preferable size relationship of the embodiment of fig. 11A. As shown in fig. 11A, the laser 311 includes a plurality of light emitting points 313 distributed in a hexagonal shape, and correspondingly, each of the microlens structures 314 is also arranged in a hexagonal structure. Compared with a commonly used circular lens, the circular lens unit is difficult to realize close packing, a part of the detection light beam can pass through a gap, the part of the light cannot realize collimation, and a part of power density can be lost. As shown in fig. 11A and 11B, the hexagonal microlens structures 314 are arranged to match the light emitting points 313, and the length of the inscribed circle diameter d2 of the hexagonal microlens structures 314 is d1 (i.e. the center-to-center distance of the light emitting units of the VCSEL) of the adjacent light emitting points 313, i.e. d1 is equal to d2, so that the dense distribution is realized and the optical energy utilization rate of the VCSEL is improved. Alternatively, the lens profile may be plano-convex with the convex side being spherical or aspherical, depending on the collimation requirements. In addition, the plane and the convex surface or any surface of the MLA can be coated with an antireflection film with the wavelength of VCSEL to improve the transmittance.

According to an embodiment of the present invention, the micro lens structures 314 are disposed corresponding to the arrangement pattern of each light emitting point 313. Fig. 12 is a schematic diagram showing a microlens structure disposed on a light emitting point of a laser according to another embodiment of the present invention. As shown in fig. 12, the laser 311 includes a plurality of light-emitting points 313 distributed in a quadrilateral shape, and correspondingly, each of the microlens structures 314 is also configured as a quadrilateral structure. Similarly, the light emitting points distributed in the pentagon shape are provided with the corresponding pentagon-shaped micro-lens structure, and so on, which is not described herein again.

According to an embodiment of the present invention, wherein the field angle span in the horizontal direction of the entire emission unit 300 is less than or equal to 10 degrees. Optionally, the transceiving line array is designed to be as narrow as possible in the horizontal direction, and the focal length is designed to be as long as possible, so that the field angle span of the transceiving channel in the horizontal direction is controlled, and the influence of the overlarge horizontal angle on the rotation angle of the code spanning disc is avoided, and the influence on the next scanning is avoided.

The utility model also relates to a detection method of the laser radar, which uses the laser radar 100 for detection. According to an embodiment of the present invention, the transmitting module 310 includes a plurality of lasers 311 arranged in a linear array or an area array, the plurality of lasers 311 are divided into a plurality of groups, each group of lasers is excited once or many times at each detection angle, a point cloud combination arranged in a linear array or an area array is obtained through multiple detections in a horizontal angle range, and a frame of point clouds in a field of view is generated according to the point cloud combination.

According to one embodiment of the utility model, lasers distributed in groups of linear arrays are adopted during detection, each group of detectors is sequentially excited at each detection angle, so that linear array point clouds are obtained, and one frame of point clouds is generated according to linear array point cloud combination of each detection angle.

According to one embodiment of the utility model, one or more groups of lasers are excited for multiple times by adopting different energy at part of detection angles during detection, so that near-distance and far-distance point cloud information is obtained, and a frame of point cloud is generated according to the point cloud information.

The advantages of embodiments of the present invention are specifically illustrated below by way of example. Taking an obstacle with a size of 2m × 2m at a distance of 50m from the laser radar 100 as an example, the moving speed per hour of the obstacle relative to the laser radar 100 is 100 km/h.

Fig. 13 is a schematic diagram showing a motion distortion situation generated when two-dimensional scanning is performed by using a single beam. As shown in fig. 14, when the single beam two-dimensional scanning is adopted, taking a frame rate of 10Hz and an image obtained by accumulating 100ms as an example, the time difference between the point which is the earliest on the obstacle and the point which is the latest on the obstacle in a single frame may be different by 100ms at the maximum. In combination with the moving distance of the obstacle of 100km/h, the moving distance of the obstacle within 100ms is 2.8 meters, that is, in the scanning mode, the obstacle distortion reaches 2.8 meters.

Figure 14 shows a schematic representation of the motion distortion that occurs when one-dimensional scanning with a multi-beam is used. In the same case, as shown in fig. 14, in 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, the horizontal field of view is 120 °, and when the horizontal field of view is 10HZ, the time for scanning the angle is 33ms (2.3/120) to 0.63ms, and the moving distance of the obstacle is 0.0175m at this time.

Through the comparison, obviously, the motion distortion condition of the laser radar during measurement can be better reduced by adopting a multi-line-beam one-dimensional scanning mode.

In summary, the utility model adopts the one-dimensional scanning mirror-rotating 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 mirror-rotating laser radar, thereby completing the scanning of the whole field area, obviously inhibiting the motion blur effect of the laser radar during the measurement, obviously reducing the shape distortion of the object generated by the moving object during the measurement, and improving the measurement precision of the laser radar.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the utility model. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A lidar comprising:

a transmitting unit configured to transmit a probe beam;

2. The lidar of claim 1, further comprising a processing unit coupled to the receiving unit and configured to generate a frame of point cloud by acquiring electrical signals produced by the receiving unit based on echoes reflected by any one of the reflective surfaces, the plurality of reflective surfaces of the polygonal mirror portion being rotationally symmetric with respect to the axis of rotation.

3. Lidar according to claim 1 or 2, wherein its transmitting optical axis and receiving optical axis portions are coaxial.

4. The lidar of claim 3, further comprising a beam splitting assembly, the probe beam being reflected by the beam splitting assembly to the mirror unit, and a corresponding echo being transmitted by the beam splitting assembly and received by the receiving unit; or the detection beam is transmitted to the rotating mirror unit through the light splitting component, and the corresponding echo is reflected by the light splitting component and received by the receiving unit.

5. The lidar according to claim 1 or 2, wherein a transmission optical axis from which the probe beam transmitted by the transmission unit is reflected by a reflection surface of the polygon mirror section and emitted, and a reception optical axis from which the echo is reflected by the reflection surface and reaches the reception unit are independent of each other.

6. The lidar according to claim 1 or 2, wherein the mirror unit further comprises a motor and a mirror holder for accommodating the plurality of reflecting surfaces, the motor being comprised in a polygonal space enclosed by the reflecting surfaces for driving the multi-faceted mirror portion to rotate around its rotation axis, wherein an angle of at least one of the plurality of reflecting surfaces is adjustable for achieving rotational symmetry of the plurality of reflecting surfaces of the mirror unit with respect to the central axis.

7. The lidar according to claim 1 or 2, wherein a mirror surface angle of the plurality of reflection surfaces of the polygon mirror part in a vertical direction is configured to be adjustable.

8. The lidar of claim 4, wherein the transmitting unit comprises a transmitting module and a transmitting lens group; the emitting module is configured to emit a probe beam, and the probe beam is emitted to the reflecting surface of the rotating mirror unit through the emitting lens group and the light splitting component.

9. The lidar of claim 8, wherein the transmitting unit further comprises at least a first fold mirror, the transmitting lens group comprising a plurality of transmitting lenses disposed between the transmitting module and the first fold mirror, between the first fold mirror and the beam splitting assembly.

10. The lidar according to claim 8, wherein the receiving unit comprises a receiving lens group and a receiving module; and the echo is reflected by any reflecting surface of the rotating mirror unit and then enters the receiving module through the light splitting assembly and the receiving lens group.

11. The lidar of claim 10, wherein the receiving unit further comprises at least one second turning mirror, the receiving lens group comprising a plurality of receiving lenses disposed between the beam splitting assembly and the second turning mirror, between the second turning mirror and the receiving module.

12. The lidar according to claim 1 or 2, wherein the polygon mirror part comprises two, three or four reflecting faces.

13. The lidar according to claim 10, wherein the transmitting module comprises a plurality of lasers arranged in a linear array or an area array, and the receiving unit comprises a plurality of photodetectors arranged in a corresponding manner with the same number of lasers, wherein each photodetector corresponds to one of the lasers and is configured to receive an echo reflected by a detection beam emitted by the corresponding laser on a target object.

14. The lidar of claim 13, wherein the plurality of lasers comprises at least one laser provided with a micro-lens.

15. The lidar according to claim 13, wherein the laser provided with the microlens comprises a plurality of light emitting points, and each light emitting point has a corresponding microlens structure.

16. The lidar according to claim 15, wherein a plurality of the microlens structures are provided corresponding to an arrangement pattern of the plurality of light emitting points.

17. The lidar according to claim 1 or 2, wherein a field angle span in a horizontal direction of the entire transmitting unit is not more than 10 degrees.