CN114296053A - Laser radar and scanning monitoring system - Google Patents

Abstract

The application provides a laser radar and a scanning monitoring system, which relate to the technical field of radar and comprise a base body, a laser, a first reflecting element, a second reflecting element, a first motor, a second motor and a receiving assembly, wherein the laser, the first reflecting element, the second reflecting element, the first motor and the second motor are arranged on the base body; the detection beam of laser outgoing carries out two-dimensional scanning to the target object after first reflection component and second reflection component reflection in proper order, the echo beam of being reflected by the target object returns second reflection component and first reflection component back incidence receiving assembly in proper order, laser instrument and receiving assembly all are located the income light side of first reflection component, so that the outgoing optical axis of laser instrument is parallel with receiving assembly's incident optical axis, so, alright form coaxially in the direction of two optical axes of perpendicular with the transmission and receipt, thereby the line row receiving mode that current off-axis scheme need adopt has been avoided, and then laser radar's volume and cost have been reduced.

Description

Laser radar and scanning monitoring system

Technical Field

The application relates to the technical field of radars, in particular to a laser radar and a scanning monitoring system.

Background

With the development of laser technology, laser scanning technology is more and more widely applied to the fields of measurement, traffic, driving assistance, mobile robots and the like. The laser radar is a radar system for detecting the position, speed and other characteristic quantities of a target by laser, and the working principle of the radar system is that a detection beam is firstly emitted to the target, then a signal reflected from the target is compared with an emitted signal, and after appropriate processing, the information of the target, such as distance, direction, height, speed, attitude, even shape and the like, can be obtained.

In the existing scheme of realizing two-dimensional scanning by arranging a prism and a swing mirror, an emission light source and a receiving sensor are arranged in an off-axis mode, and the receiving sensor adopts a linear receiving mode, so that the size of the laser radar is increased, and the cost is increased.

Disclosure of Invention

An object of this application lies in, to the not enough among the above-mentioned prior art, provides a laser radar and scanning monitoring system to solve current transmitting light source and receiving sensor off-axis setting, lead to the great problem of laser radar volume.

In order to achieve the above purpose, the technical solutions adopted in the embodiments of the present application are as follows:

in one aspect of the embodiments of the present application, a laser radar is provided, which includes a base, and a laser, a first reflection element, a second reflection element, a first motor, a second motor, and a receiving assembly, which are disposed on the base; the first motor is in driving connection with the first reflecting element so that the laser radar can perform first-dimensional scanning, the second motor is in driving connection with the second reflecting element so that the laser radar can perform second-dimensional scanning, the detection light beams emitted by the laser device are reflected by the first reflecting element and the second reflecting element in sequence and then perform two-dimensional scanning on a target object, the echo light beams reflected by the target object return to the second reflecting element and the first reflecting element in sequence and then enter the receiving assembly, and the laser device and the receiving assembly are both located on the light inlet side of the first reflecting element so that the emitting optical axis of the laser device is parallel to the incident optical axis of the receiving assembly.

Optionally, the second reflecting element includes a rotating shaft and a polygon mirror, one end of the rotating shaft is fixedly connected to an output shaft of the second motor, and the other end of the rotating shaft penetrates through the polygon mirror and is fixedly connected to the polygon mirror, so that the second motor can drive the polygon mirror to rotate around the first direction relative to the base.

Optionally, the first reflecting element is a reflector, and the first motor is fixedly connected to the reflector, so that the first motor can drive the polygon mirror to rotate around the second direction relative to the base, and the first direction is perpendicular to the second direction.

Optionally, the laser radar further includes a detection device, and the detection device is disposed at the other end of the rotating shaft and is used for detecting a rotation angle of the polygon mirror.

Optionally, the diameter of the receiving aperture of the receiving assembly is positively correlated with the area of any one of the reflecting surfaces in the polygon mirror.

Optionally, the first motor is a slow-axis motor, and the second motor is a fast-axis motor, so that the probe beam is reflected by the first reflecting element and the second reflecting element in sequence and then forms a plurality of scanning lines in parallel in the vertical direction in the target area.

Optionally, the first motor is a fast-axis motor, and the second motor is a slow-axis motor, so that the probe beam is reflected by the first reflecting element and the second reflecting element in sequence and then forms a plurality of scanning lines parallel to each other in the transverse direction in the target area.

Optionally, the driving period of the first motor and the driving period of the second motor are alternately set.

Optionally, the receiving assembly includes a receiving lens and a receiving circuit board disposed on the light emitting side of the receiving lens.

In another aspect of the embodiments of the present application, a scanning monitoring system is provided, which includes any one of the above-mentioned lidar.

The beneficial effect of this application includes:

the application provides a laser radar and scanning monitoring system, which comprises a base body, a laser, a first reflecting element, a second reflecting element, a first motor, a second motor and a receiving assembly, wherein the laser, the first reflecting element, the second reflecting element, the first motor, the second motor and the receiving assembly are arranged on the base body; the first motor is in driving connection with the first reflecting element so that the laser radar can perform first-dimensional scanning, the second motor is in driving connection with the second reflecting element so that the laser radar can perform second-dimensional scanning, the detection light beam emitted by the laser device is reflected by the first reflecting element and the second reflecting element in sequence and then two-dimensionally scans a target object, the echo light beam reflected by the target object returns to the second reflecting element and the first reflecting element in sequence and then enters the receiving assembly, the laser device and the receiving assembly are both positioned on the light incident side of the first reflecting element so that the emergent optical axis of the laser device is parallel to the incident optical axis of the receiving assembly, and therefore the emitting direction and the receiving direction of the laser device are coaxial, the linear array receiving mode required by the existing off-axis scheme is avoided, and the size and the cost of the laser radar are reduced.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

Fig. 1 is a top view of a lidar according to an embodiment of the present disclosure;

fig. 2 is a second top view of a laser radar according to an embodiment of the present disclosure;

fig. 3 is a top view of a lidar according to another embodiment of the present disclosure;

fig. 4 is a schematic view of a scanning line of a lidar according to an embodiment of the present disclosure;

fig. 5 is a second schematic view of a scanning line of a lidar according to an embodiment of the present disclosure.

Icon: 100-a seat body; 110-a laser; 111-scan lines; 120-a polygon mirror; 130-a receiving component; 140-mirror.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. It should be noted that, in case of conflict, various features of the embodiments of the present application may be combined with each other, and the combined embodiments are still within the scope of the present application.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or orientations or positional relationships that the products of the application usually place when in use, and are used only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the devices or elements being referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present application. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.

Furthermore, the terms "horizontal", "vertical" and the like do not imply that the components are required to be absolutely horizontal or pendant, but rather may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the present application, it is further noted that, unless expressly stated or limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

In an aspect of the embodiment of the present application, a lidar is provided, as shown in fig. 1, and includes a base 100, a laser 110, a first reflective element, a second reflective element, a first motor, a second motor, and a receiving assembly 130, where the laser 110, the first reflective element, the second reflective element, the first motor, the second motor, and the receiving assembly 130 are all disposed on the base 100, so as to form an integral structure with the base 100.

As shown in fig. 1, the laser 110 and the receiving assembly 130 are both located on the light incident side of the first reflective element, in other words, the first reflective element is located not only on the emergent optical axis of the laser 110, but also on the incident optical axis of the receiving assembly 130, so that on one hand, after the probe beam emitted from the laser 110 reaches the first reflective element, the probe beam is reflected by the reflective surface of the first reflective element toward the second reflective element, and on the other hand, the echo beam reflected by the target object is reflected by the first reflective element and can be correspondingly received by the receiving assembly 130.

As shown in fig. 1, the first reflection element and the second reflection element are rotatably disposed on the base 100, respective rotation directions of the first reflection element and the second reflection element are perpendicular to each other, the first motor is in driving connection with the first reflection element to enable the lidar to perform a first dimension scanning under the driving of the first motor, and the second motor is in driving connection with the second reflection element to enable the lidar to perform a second dimension scanning under the driving of the second motor, for example, the first dimension scanning is a vertical scanning, the second dimension scanning is a horizontal scanning, and for convenience of description, the following description will be performed by using a spatial rectangular coordinate system: with the top view direction shown in fig. 1 as the Z axis (vertical direction), the first motor is in driving connection with the first reflective element, so that the first reflective element can rotate around the Y axis (e.g. rotate along the direction of the rotation arrow at the first reflective element in fig. 1) relative to the base 100 under the driving of the first motor, in other words, the output shaft of the first motor is collinear with the Y axis; the second motor is connected to the second reflection element in a driving manner, so that the second reflection element can rotate around the Z axis relative to the base 100 (e.g. rotate along the direction of the rotation arrow at the second reflection element in fig. 1) under the driving of the second motor, in other words, the output shaft of the second motor is collinear with the Z axis, based on that after the laser 110 emits the probe beam, the probe beam is reflected by the first reflection element and then enters the second reflection element, and then is reflected by the second reflection element to the outside, therefore, when the first reflection element rotates around the Y axis, the emission direction of the probe beam is changed along the Z axis correspondingly, so as to realize vertical scanning (first-dimensional scanning) of the probe beam, and when the second reflection element rotates around the Z axis, the emission direction of the probe beam is changed along the X axis correspondingly, so as to realize transverse scanning (second-dimensional scanning) of the probe beam, and thus, the first reflection element and the second reflection element are respectively driven by superimposing the first motor and the second motor, two-dimensional scanning (i.e., vertical and lateral scanning) of the lidar may be achieved.

During actual detection, as shown in fig. 1, a laser 110 emits a probe beam, and the probe beam is reflected by a first reflective element and a second reflective element in sequence and then emitted outward (a solid line with an arrow in fig. 1, the arrow indicates a transmission direction), so that a detection field is formed and two-dimensional scanning is performed; as shown in fig. 2, when the target is located in the detection field, a part of the detection beam (the dotted line with an arrow in fig. 2, the arrow indicates the transmission direction) is reflected by the target to form an echo beam, and then returns to the second reflective element, and is reflected by the second reflective element, returns to the first reflective element, and is reflected by the first reflective element to enter the receiving assembly 130, so that the software analysis can obtain the relevant information about the target.

In conclusion, this application adopts first reflection component and second reflection component to form two-dimensional scanning, simultaneously, laser instrument 110 and receiving component 130 in this application all are located the income light side of first reflection component, can make laser instrument 110's outgoing optical axis parallel with receiving component 130's receiving optical axis, so, alright form coaxially in the direction of two optical axes of perpendicular with receiving in order to make transmission, thereby avoided the linear array receiving mode that current off-axis scheme need adopt, and then reduced lidar's volume and cost.

Optionally, as shown in fig. 1 and fig. 3, the second reflection element includes a rotation shaft and a polygon mirror 120, the second motor is fixedly disposed on the base 100, one end of the rotation shaft is fixedly connected to an output shaft of the second motor, and the other end of the rotation shaft is inserted into the polygon mirror 120 from a bottom surface of the polygon mirror 120 and is fixedly connected to the polygon mirror 120, so that the second motor can drive the polygon mirror 120 to rotate around the base 100 in the first direction (which may be the Z-axis direction) through the rotation shaft, and meanwhile, the side surface of the polygon mirror 120 can be fully utilized as a reflection surface by utilizing a manner that the rotation shaft is inserted into the polygon mirror 120, thereby avoiding affecting reflection of the side surface of the polygon mirror 120. It should be understood that the polygon mirror 120 is formed by a top surface, a bottom surface and a plurality of side surfaces, wherein the plurality of side surfaces of the polygon mirror 120 can be used as reflecting surfaces to reflect the probe beam and the echo beam. Since the polygon mirror 120 is used as the scanning mirror, the detection beam emitted from the laser 110 to the polygon mirror 120 is reflected by the multiple side surfaces of the polygon mirror 120 in sequence every time the polygon mirror 120 rotates one circle, so that multiple scanning frames can be generated.

Alternatively, as shown in fig. 1, the area of the reflection surface of the polygon mirror 120 may be determined according to the receiving area of the receiving assembly 130, for example: receiving element 130's receiving aperture is circular, and the diameter of circular receiving aperture is positively correlated with the area of any one plane of reflection of polygon mirror 120 to this, compare in the current mode that adopts galvanometer scanning, this application adopts polygon mirror 120 can realize the heavy-calibre and receives, thereby improves laser radar's measurement accuracy.

In some embodiments, the number of the lasers 110 in the present application may be one or multiple, and the present application does not limit the number of the lasers 110, for example, as shown in fig. 2, when two lasers 110 include two lasers, the two lasers 110 may share a receiving lens of a receiving assembly 130, that is, echo beams formed by reflection of probe beams emitted by the two lasers 110 by an object may both enter the same receiving lens, and then are correspondingly received by different receiving chips.

It should be understood that the laser 110 and the receiving assembly 130 may be distributed in sequence along the horizontal direction, or may be distributed in sequence along the vertical direction (Z-axis direction). Similarly, when the laser 110 includes a plurality of lasers 110, the plurality of lasers 110 may be sequentially distributed along the transverse direction (X-axis direction), so that, in view of the fact that each laser 110 can form one two-dimensional detection field, the field width of the laser radar along the transverse direction can be increased by the superposition of the plurality of two-dimensional detection fields; the two-dimensional detection fields can be distributed along the vertical direction (Z-axis direction), so that the field width of the laser radar along the vertical direction can be increased through superposition of the two-dimensional detection fields.

Optionally, as shown in fig. 1, the first reflective element is a reflector 140, the first motor is fixedly disposed on the base 100, and an output shaft of the first motor is fixedly connected to the reflector 140, so that the first motor can drive the reflector 140 to rotate around the second direction (which may be a Y-axis direction) relative to the base 100.

In some embodiments, as shown in fig. 1 to 2, the polygon mirror 120 may be a quadrangular prism, and the rotation shaft passes through the quadrangular prism from the bottom surface thereof, and in the actual detection: as shown in fig. 1, the laser 110 emits the probe beam to the four-prism, and the reflecting mirror 140 and the four-prism are driven by the first motor and the second motor, respectively, so that the position where the probe beam enters the four-prism can be changed along the Z-axis when the reflecting mirror 140 rotates about the Y-axis, and the direction in which the probe beam exits can be changed along the X-axis when the four-prism rotates about the Z-axis, thereby forming two-dimensional scanning. When the four-prism rotates for one circle, the detection beam emitted by the laser 110 sequentially passes through four side surfaces of the four-prism, and 4 scanning frames are correspondingly generated, so that the scanning frame rate is higher. Since each frame generates 4 scanning frames per rotation of the quadrangular prism, each frame is rotated by 90 degrees with respect to the quadrangular prism, and the outgoing angle of the probe beam reflected by the quadrangular prism is rotated by 2 degrees per 1 degree based on the quadrangular prism, the optical scanning angle of each frame is 180 degrees, and when the actual scanning angle of the laser radar is set, the actual scanning angle can be smaller than that of each frame, in other words, a part of the angle can be intercepted or utilized as the actual scanning angle in the optical scanning angle of each frame, for example, if the actual scanning angle of the laser radar is 120 degrees, only 120 degrees out of 180 degrees need to be intercepted/utilized as the actual scanning angle in each frame.

In some embodiments, as shown in fig. 3, the polygon mirror 120 may also be a pentaprism, and the rotation axis still passes through the bottom surface of the pentaprism and is set in the pentaprism, in the actual detection: the laser 110 emits a probe beam to the pentaprism, and when the pentaprism rotates for one circle, the probe beam emitted by the laser 110 sequentially passes through five side surfaces of the pentaprism, and correspondingly generates 5 scanning frames, so that the scanning frame rate is higher. Since 5 scanning frames can be generated by rotating the pentaprism every one rotation, each frame corresponds to 72 degrees of the pentaprism rotation, and the emergent angle of the probe beam reflected by the pentaprism rotates 2 degrees based on 1 degree of the pentaprism rotation, so the optical scanning angle of each frame is 144 degrees, when the actual scanning angle (horizontal scanning angle) of the laser radar is set, the actual scanning angle can be smaller than that of each frame, in other words, a part of the angle can be intercepted or utilized as the actual scanning angle in the optical scanning angle of each frame, for example, if the actual scanning angle of the laser radar is 120 degrees, only 120 degrees out of 144 degrees need to be intercepted/utilized as the actual scanning angle in each frame.

In other embodiments, the polygon mirror 120 in the present application may be a triangular prism, a hexagonal prism, a seven-prism, or the like, and when the number of side surfaces of the polygon mirror 120 is increased, the corresponding scan frame rate is also higher. It should be understood that as the scanning frame rate is increased, the optical scanning angle of each frame is smaller, and the range where the actual scanning angle of the lidar can be intercepted/utilized is smaller, so that in the actual selection and setting, the actual scanning angle should be reasonably selected according to actual requirements, and the application does not specifically limit the optical scanning angle.

Optionally, the laser radar further includes a detection device, and the detection device is disposed at the other end of the rotating shaft, for example: the second motor and the detecting device are respectively located on the bottom surface and the top surface of the polygon mirror 120, so that when the polygon mirror 120 is driven by the second motor, the rotating angle of the polygon mirror 120 can be detected through the detecting device, which is convenient for monitoring the rotating state of the polygon mirror 120.

Optionally, as shown in fig. 4, the first motor is a slow-axis motor, the second motor is a fast-axis motor, and at this time, the rotation speed of the second motor is greater than that of the first motor, so that when the first motor and the second motor are used to implement two-dimensional scanning, the probe beam finally reflected by the polygon mirror 120 to the target object region may form a plurality of vertically parallel scanning lines 111. It should be understood herein that the scan line 111 may be a horizontal line, which may be formed directly after scanning, without software algorithm modification, such as: when the driving period of the first motor and the driving period of the second motor are alternately arranged along the time line, in the driving period of the second motor, the first motor stops driving, the detection beam completes the scanning line 111 of one straight line segment, then enters the driving period of the first motor, the second motor stops driving, the first motor drives the reflector 140 to rotate, so that the detection beam moves along the vertical direction, then enters the driving period of the second motor, the first motor stops driving, the detection beam after moving along the vertical direction completes the scanning line 111 of the other straight line segment, and the above steps are repeated, so that a plurality of scanning lines 111 which are parallel along the vertical direction and are shown in fig. 4 can be formed; the scan line 111 may be a horizontal line, or the horizontal line may be formed by scanning and then modifying through a software algorithm, for example: when the two-dimensional scanning is realized, the first motor and the second motor are driven simultaneously, at the moment, the detection light beam completes a straight line segment and a scanning line 111 with a certain slope, and the horizontal scanning line 111 can be obtained through later-stage algorithm correction.

Optionally, as shown in fig. 5, the first motor is a fast axis motor, the second motor is a slow axis motor, and at this time, the rotation speed of the first motor is greater than that of the second motor, so that when the first motor and the second motor are used to implement two-dimensional scanning, the probe beam finally reflected by the polygon mirror 120 to the target object region may form a plurality of scanning lines 111 parallel in the transverse direction. It should be understood herein that the scan line 111 may be a vertical line, which may be formed directly after scanning, without software algorithm modification, such as: when the driving period of the first motor and the driving period of the second motor are alternately arranged along the time line, in the driving period of the second motor, the first motor stops driving, the probe beam completes the scanning line 111 of one straight line segment, then enters the driving period of the first motor, the second motor stops driving, the first motor drives the reflector 140 to rotate, so that the probe beam moves along the transverse direction, then enters the driving period of the second motor, the first motor stops driving, the probe beam after moving along the transverse direction completes the scanning line 111 of the other straight line segment, and the above cycles are repeated, so that a plurality of scanning lines 111 parallel along the transverse direction as shown in fig. 5 can be formed; the scan line 111 may be a vertical line, or a vertical line formed by scanning and then correcting by a software algorithm, for example: when the two-dimensional scanning is realized, the first motor and the second motor are driven simultaneously, at the moment, the detection light beam completes a straight line segment and has a scanning line 111 with a certain slope, and the vertical scanning line 111 can be obtained through later-stage algorithm correction.

In some embodiments, the rotation speed of the first motor may be controlled to be constant, so as to uniformly distribute the plurality of scanning lines 111, or the rotation speed of the first motor may be controlled to be variable, so as to densely distribute the plurality of scanning lines 111.

Optionally, the receiving assembly 130 includes a receiving lens and a receiving chip disposed on the light emitting side of the receiving lens, so that after the echo light beam enters the receiving lens, the receiving chip can obtain the receiving information.

In another aspect of the embodiments of the present application, a scanning monitoring system is provided, which includes any one of the above-mentioned lidar. Through adopting first reflection element and second reflection element to form two-dimensional scanning, simultaneously, laser instrument 110 and receiving component 130 in this application all are located first reflection element's income light side, can be so that laser instrument 110's outgoing optical axis is parallel with receiving component 130's receiving optical axis, so, alright form coaxially in the direction of two perpendicular optical axes with making transmission and receipt to the line row receiving mode that current off-axis scheme need adopt has been avoided, and then laser radar's volume and cost have been reduced.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims (10)

1. A laser radar is characterized by comprising a base body, a laser, a first reflecting element, a second reflecting element, a first motor, a second motor and a receiving assembly, wherein the laser, the first reflecting element, the second reflecting element, the first motor, the second motor and the receiving assembly are arranged on the base body; the laser radar device comprises a first motor, a second motor, a first reflecting element, a second reflecting element, a receiving assembly and a laser, wherein the first motor is in driving connection with the first reflecting element so that the laser radar performs first-dimension scanning, the second motor is in driving connection with the second reflecting element so that the laser radar performs second-dimension scanning, a detection beam emitted by the laser sequentially passes through the first reflecting element and is reflected by the second reflecting element so that a target object is subjected to two-dimension scanning, an echo beam reflected by the target object sequentially returns to the second reflecting element and is incident behind the first reflecting element to the receiving assembly, and the laser and the receiving assembly are both positioned on the incident side of the first reflecting element so that the emergent optical axis of the laser is parallel to the incident optical axis of the receiving assembly.

2. The lidar of claim 1, wherein the second reflective element comprises a rotating shaft and a polygon mirror, one end of the rotating shaft is fixedly connected to the output shaft of the second motor, and the other end of the rotating shaft is disposed through the polygon mirror and fixedly connected to the polygon mirror, so that the second motor can drive the polygon mirror to rotate around a first direction relative to the base.

3. The lidar of claim 2, wherein the first reflective element is a mirror, and the first motor is fixedly connected to the mirror such that the first motor can drive the polygon mirror to rotate relative to the base in a second direction, the first direction being perpendicular to the second direction.

4. The lidar of claim 2, further comprising a detecting means disposed at the other end of the shaft for detecting a rotation angle of the polygon mirror.

5. The lidar of claim 2, wherein a diameter of a receiving aperture of the receiving assembly is positively correlated to an area of any one of the reflecting surfaces of the polygon mirror.

6. The lidar of any of claims 1 to 5, wherein the first motor is a slow axis motor and the second motor is a fast axis motor, such that the probe beam is reflected by the first reflective element and the second reflective element in sequence to form a plurality of vertically parallel scan lines in the target area.

7. The lidar of any of claims 1 to 5, wherein the first motor is a fast axis motor and the second motor is a slow axis motor, such that the probe beam is reflected by the first reflective element and the second reflective element in sequence to form a plurality of laterally parallel scan lines in the target area.

8. The lidar of any of claims 1 to 5, wherein drive periods of the first motor alternate with drive periods of the second motor.

9. The lidar of any of claims 1 to 5, wherein the receiving assembly comprises a receiving lens and a receiving circuit board disposed on a light exit side of the receiving lens.

10. A scanning monitoring system comprising a lidar according to any of claims 1 to 9.

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