CN209979838U

CN209979838U - Multi-line laser radar

Info

Publication number: CN209979838U
Application number: CN201920236494.1U
Authority: CN
Inventors: 尹向辉; 马丁昽
Original assignee: Suteng Innovation Technology Co Ltd
Current assignee: Suteng Innovation Technology Co Ltd
Priority date: 2019-02-25
Filing date: 2019-02-25
Publication date: 2020-01-21
Anticipated expiration: 2029-02-25

Abstract

The utility model relates to a multi-line laser radar. A multiline lidar comprising: a laser emitting device; the laser receiving device is used for receiving the reflected laser; the reflected laser is the laser after the emergent laser is reflected by the detected object; the main rotating mirror rotates around a rotating shaft of the main rotating mirror, and the main rotating mirror is used for reflecting emergent laser emitted by the laser emitting device and reflecting the reflected laser to the laser receiving device; the secondary rotating mirror rotates around a rotating shaft of the secondary rotating mirror, is used for reflecting the emergent laser reflected by the main rotating mirror to a scanning area, and is also used for reflecting the reflected laser to the main rotating mirror; and the rotation driving system is used for driving the main rotating mirror and the secondary rotating mirror to rotate. In the multi-line laser radar, only the main rotating mirror and the secondary rotating mirror rotate, and the laser emitting device and the laser receiving device are fixed; the control and structural system design inside the multi-line laser radar are simplified, and the reliability of the multi-line laser radar is improved.

Description

Multi-line laser radar

Technical Field

The utility model relates to a laser detection technology field especially relates to a multi-line laser radar.

Background

The laser radar is a system for detecting characteristic quantities such as the position, the speed and the like of a detection object by emitting a laser beam, and is widely applied to the field of laser detection.

At present, a plurality of transmitting-receiving pairs are arranged in the vertical direction for detection by the laser radar, the number of lines is the number of the transmitting-receiving pairs in the vertical direction, and the vertical resolution of the laser radar is determined by the number of lines. A plurality of transmitting-receiving pairs can detect a plurality of directions, and meanwhile, the whole laser radar rotates in the working process, so that the detection of the surrounding environment of the laser radar is realized.

However, the transmitting plate and the receiving plate arranged in the vertical direction occupy a certain space, which limits the increase of the number of laser radar lines and the improvement of the vertical resolution; multiple transmit-receive pairs, requiring multiple components to increase cost, while increasing power consumption and internal heat generation; the working state of the laser radar is rotating, power supply and communication are needed for transmitting-receiving pairs on the rotating module, and the system design is complex.

SUMMERY OF THE UTILITY MODEL

In view of the above, there is a need to provide a multiline lidar in view of the problems of high cost and complicated optical and structural system design of the conventional lidar.

A multiline lidar comprising:

the laser emitting device is used for emitting emergent laser;

the laser receiving device is arranged on the same side as the laser emitting device and is used for receiving reflected laser; the reflected laser is the laser reflected by the detected object of the emergent laser;

the main rotating mirror rotates around a rotating shaft of the main rotating mirror, and the main rotating mirror is used for reflecting emergent laser emitted by the laser emitting device and reflecting the reflected laser to the laser receiving device;

the secondary rotating mirror rotates around a rotating shaft of the secondary rotating mirror, and is used for reflecting the emergent laser reflected by the main rotating mirror to a scanning area and reflecting the reflected laser to the main rotating mirror;

the rotation driving system is used for driving the main rotating mirror and the secondary rotating mirror to rotate; and

the laser emitting device, the laser receiving device, the main rotating mirror, the secondary rotating mirror and the rotary driving system are all arranged in the shell.

In one embodiment, the rotating shaft of the main rotating mirror is 45 degrees to the horizontal plane; the included angle between the normal line of the main rotating mirror and the rotating shaft of the main rotating mirror is a first angle, and the first angle is not zero.

In one embodiment, the rotation axis of the secondary turning mirror is located in the vertical direction; the included angle between the normal of the secondary rotating mirror and the rotating shaft of the secondary rotating mirror is a second angle; the second angle and the first angle cooperate to determine a scanning angle range of the emergent laser light in the longitudinal direction.

In one embodiment, the rotation speed of the primary rotating mirror is greater than that of the secondary rotating mirror.

In one embodiment, the rotating speed of the primary rotating mirror is N times of the rotating speed of the secondary rotating mirror; n is a non-integer and the range of N is 10-100.

In one embodiment, the device further comprises a collimating lens group; the collimating lens group is used for collimating emergent laser emitted by the laser emitting device.

In one embodiment, the device further comprises a focusing lens group; the focusing lens group is used for focusing the reflected laser to the laser receiving device.

In one embodiment, the number of the laser emitting devices and the number of the laser receiving devices are both 1.

In one embodiment, the rotary drive system comprises a rotary drive, a first linkage assembly, a second linkage assembly, and an encoder; the rotation driving device drives the main rotating mirror to rotate through the first connecting assembly; the rotation driving device drives the secondary rotating mirror to rotate through the second connecting assembly; the encoder is used for measuring the rotating speed and the position of the main rotating mirror and the secondary rotating mirror.

In one embodiment, the system further comprises a control panel; the control panel is also arranged in the shell; the control panel is electrically connected with the laser emitting device, the laser receiving device and the rotary driving system.

The multi-line laser radar comprises a laser transmitting device, a laser receiving device, a main rotating mirror, an auxiliary rotating mirror and a rotary driving system; emergent laser emitted by the laser emitting device is reflected by the main rotating mirror and the secondary rotating mirror in sequence and then is emitted to the scanning area, and the reflected laser is reflected by the secondary rotating mirror and the main rotating mirror in sequence and then is emitted to the laser receiving device. In the multi-line laser radar, only the main rotating mirror and the secondary rotating mirror rotate and are passive optical devices, and power supply and communication are not needed for the main rotating mirror and the secondary rotating mirror; the laser emitting device and the laser receiving device are both fixed; the control and structural system design inside the multi-line laser radar are simplified, and the reliability of the multi-line laser radar is improved. The main rotating mirror is inclined and rotated, emergent laser is reflected by the main rotating mirror and then does not vertically upwards shoot to the secondary rotating mirror, and the reflected emergent laser and the vertical direction rotate at a fixed included angle; the emergent laser is reflected by the secondary rotating mirror and then emitted to the scanning area, and the rotation of the secondary rotating mirror enables the emergent laser to be emitted to the range of 360 degrees around the multi-line laser radar; the scanning effect and the function requirement of the multi-line laser radar can be realized only by adopting one laser transmitting device and one laser receiving device, the number of occupied components is small, the cost is low, the occupied space is small, the power consumption is low, and the system design is simple.

Drawings

Fig. 1 is a schematic diagram of an internal structure of a multiline lidar in an embodiment.

Fig. 2 is a schematic diagram of scanning tracks of the lissajous pattern formed by the optical axis when the main rotating mirror and the secondary rotating mirror rotate.

FIG. 3 is a schematic view of the scanning track of the optical axis when the primary rotating mirror rotates and the secondary rotating mirror does not move.

FIG. 4 is a diagram of the scanning trajectory of the optical axis at an angular resolution of 0.25 degrees.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

In the description of the present application, it is to be understood that the terms "center", "lateral", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner" and "outer" etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a particular orientation, be constructed in a particular orientation, and be operated, and thus should not be construed as limiting the present application. Further, when an element is referred to as being "formed on" another element, it can be directly connected to the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present.

Fig. 1 is a schematic diagram of an internal structure of a multiline lidar in an embodiment. Referring to fig. 1, the lidar includes a laser transmitter 110, a laser receiver 120, a primary turning mirror 132, a secondary turning mirror 134, and a rotational drive system 180.

The laser emitting device 110 is used to emit outgoing laser light. The frequency of the emitted laser light emitted by the laser emitting device 110 can be set as desired. The emitted laser beam may be a visible light beam or a non-visible light beam. The present application is not particularly limited. In the present embodiment, the laser emitting device 110 includes only one. In other embodiments, the laser emitting device 110 and the laser receiving device 120 may be multiple so as to enhance the scanning density of the emitted laser.

The laser receiver 120 is configured to receive the reflected laser light and convert the received reflected laser light into an electrical signal that can be recognized by a processor or a processing chip. The reflected laser is laser light reflected by the outgoing laser-detected object. In the present embodiment, the laser receiver 120 is disposed on the same side as the laser transmitter 110. Generally, the laser emitting device 110 emits the outgoing laser with a certain divergence angle, so that the diameter of the cross section of the outgoing laser is larger and larger in the process of propagation, and the spot irradiated on the detected object is larger than the caliber of the laser emitting device 110. The reflected laser light reflected from the object to be detected must have a part of light irradiated onto the laser receiving device 120 provided on the same side as the laser emitting device 110, so that the reflected laser light is received by the laser receiving device 120.

The laser radar only comprises one laser emitting device 110 and one laser receiving device 120, the scanning effect same as that of a multi-channel emitting-receiving pair is achieved, the scanning high resolution is met, a small number of components are occupied, the system design is simple, the cost is low, the power consumption is low, and the space is small.

The main rotating mirror 132 is used for reflecting the outgoing laser light emitted by the laser emitting device 110 to the sub rotating mirror 134. The main rotating mirror 132 is also used to reflect the reflected laser light to the laser receiving device 120. The secondary rotating mirror 134 is used for reflecting the emergent laser light reflected by the primary rotating mirror 132 to the scanning area. The secondary turning mirror 134 also serves to reflect the reflected laser light to the primary turning mirror 132. That is, the laser emitting device 132 emits the outgoing laser beam, and the outgoing laser beam is reflected by the main rotating mirror 132 and the sub rotating mirror 134 in sequence and then projected to the scanning area. The emitted laser is reflected by the object in the scanning area, and then is reflected by the secondary rotating mirror 134 and the primary rotating mirror 132, and then is projected to the laser receiving device 120, and is received by the laser receiving device 120. In this way, the outgoing and incoming optical paths share the primary and secondary mirrors 132, 134 of the multiline lidar, reducing the complexity and cost of the multiline lidar structure.

It will be appreciated that high resolution scanning is achieved by the reflective action of the primary and secondary turning mirrors 132, 134, which have an angular relationship. The inclination angles of the main rotating mirror 132 and the sub rotating mirror 134 may be adjusted and determined according to the vertical scanning range of the emitted laser light to be projected, and are not limited to a specific state. In one embodiment, primary turning mirror 132 and secondary turning mirror 134 are elliptical to ensure that the vertical cross-section of the reflected beam trajectory is circular to form a desired cone beam shape. The rotation driving system 180 is configured to drive the main rotating mirror 132 to rotate around its rotation axis, so that the emitted laser is reflected by the main rotating mirror 132 and does not vertically emit upward to the secondary rotating mirror 134, and the emitted laser precesses around the central longitudinal axis at a fixed angle. The outgoing laser light finally reflected from the sub-rotating mirror 134 to the scanning area is made to scan in a circle on the vertical plane, and can be projected to different heights in the vertical direction, as shown in fig. 3. The rotation driving system 180 is also used to drive the secondary rotating mirror 134 to rotate around its rotation axis, so that the emitted laser reflected by the primary rotating mirror 132 is projected to the scanning area. Thus, each outgoing laser beam finally reflected from the sub-rotating mirror 134 to the scanning area can be scanned in the horizontal direction, and 360-degree scanning of the surrounding space is achieved. After being reflected by the main rotating mirror 132 and the sub rotating mirror 134, the trajectory of the optical axis of the emitted laser is a lissajous curve, as shown in fig. 2. The shape of the curve is determined by the tilt angle and the rotation speed of the primary rotating mirror 132 and the secondary rotating mirror 134, and the rotation speed of the primary rotating mirror 132 is generally required to be greater than that of the secondary rotating mirror 134.

The multiline laser radar comprises a laser emitting device 110, a laser receiving device 120, a main rotating mirror 132, a secondary rotating mirror 134 and a rotary driving system 180. The laser beam emitted from the laser emitting device 110 is reflected by the main rotating mirror 132 and the sub rotating mirror 134 in sequence and then emitted to the scanning area. The reflected laser beam is reflected by the secondary mirror 134 and the primary mirror 132 in sequence and then emitted to the laser receiver 120. In the multi-line laser radar, only the main rotating mirror 132 and the secondary rotating mirror 134 rotate, and the main rotating mirror 132 and the secondary rotating mirror 134 are passive optical devices, so that power supply and communication for the main rotating mirror 132 and the secondary rotating mirror 134 are not needed; the laser emitting device 110 and the laser receiving device 120 are both fixed; the control and structural system design inside the multi-line laser radar are simplified, and the reliability of the multi-line laser radar is improved. The main rotating mirror 132 is inclined and rotated, the emergent laser is reflected by the main rotating mirror 132 and then does not vertically upwards shoot to the secondary rotating mirror 134, and the reflected emergent laser and the vertical direction rotate at a fixed included angle; the emitted laser is reflected by the sub-rotating mirror 134 and then emitted to the scanning area, and the rotation of the sub-rotating mirror 134 enables the emitted laser to be emitted to the surrounding scanning area within 360 degrees. This multi-line laser radar only needs a laser emission device 110 and a laser receiving device 120 just can realize multi-line laser radar's function and effect, has still reduced optics and mechanical structure's the design degree of difficulty when having reduced the cost, does not need laser emission device 110 and laser receiving device 120 to rotate at the in-process of scanning moreover, has simplified the inside control of multi-line laser radar and structural system design, has improved multi-line laser radar's reliability.

In one embodiment, as shown in FIG. 1, the axis of rotation of the primary turning mirror 132 is at 45 degrees to the horizontal. The normal of the main turning mirror 132 forms a first angle θ with the rotation axis of the main turning mirror 132. It will be appreciated that to achieve the effect of the primary turning mirror 132, the first angle θ is not zero, so that the exiting laser is reflected by the rotating primary turning mirror 132 and does not project vertically upward to the secondary turning mirror 134. Thus, after the outgoing laser is reflected by the rotating main rotating mirror 132, the outgoing laser forms an angle of 2 θ with the vertical direction, and the optical axis of the outgoing laser precesses around the longitudinal axis, and the precession angle is θ. If the first angle θ is zero and the direction of the outgoing laser beam emitted from the laser emitting device 110 is horizontal, the direction of the outgoing laser beam reflected from the main rotating mirror 132 to the sub rotating mirror is always vertical during the rotation of the main rotating mirror 132, and the outgoing laser beam is not emitted in multiple directions. The first angle θ may be positive or negative. Preferably, the first angle θ is in a range of-45 ° to 45 ° and is not zero. As shown in fig. 3, the emergent laser is reflected by the rotating main rotating mirror 132 and then emitted to the scanning area through the stationary secondary rotating mirror 134, forming a circular scanning track on the vertical plane. By adjusting the first angle θ, the distribution size of the circular scanning locus can be adjusted.

In one embodiment, as shown in FIG. 1, the axis of rotation of the secondary mirror 134 is in a vertical direction. The normal of the secondary turning mirror 134 forms a second angle γ with the rotation axis of the secondary turning mirror 134. The plane that makes an angle of 45 with the horizontal plane is the reference plane 136. The secondary turning mirror 134 forms an angle with the reference plane 136, and the second angle γ is in a range of 0 ° to 90 °, where the angle is equal to (45 ° - γ). When the emitted laser is reflected to the scanning area from the secondary rotating mirror 134, the scanning track is in the longitudinal direction, the included angle between the uppermost edge and the horizontal plane is (phi + theta), and the included angle between the lowermost edge and the horizontal plane is (phi-theta). The second angle γ is adjusted to adjust the angle φ between the secondary turning mirror 134 and the reference plane 136. By adjusting the included angle phi and the first angle theta, the longitudinal angle distribution of the emergent laser projected to the scanning area from the secondary rotating mirror 134 can be adjusted, namely, the pitch angle of the laser radar scanning is adjusted, so that the longitudinal scanning range of the laser radar is aligned to the appropriate scanning area, and the laser radar scanning device is suitable for various laser radar detection scenes. Meanwhile, the sub-rotating mirror 134 rotates around its rotation axis, so that the emitted laser can scan in the horizontal direction, and the emitted laser can scan a range of 360 ° around the laser radar.

In one embodiment, the rotation speed of the primary rotating mirror 132 is greater than that of the secondary rotating mirror 134, so that the emitted laser beam completes one scanning cycle in the horizontal direction and completes a plurality of scanning cycles in the vertical direction to form a scanning track of a lissajous curve. The greater the rotational speed of primary turning mirror 132 relative to the rotational speed of secondary turning mirror 134, the greater the angular resolution that can be achieved, i.e., the denser the angular scan.

In the present embodiment, the rotation speed of the primary rotating mirror 132 is N times the rotation speed of the secondary rotating mirror 134. N is a non-integer and is in the range of 10 to 100. At this time, as shown in fig. 4, the scanning track of the lissajous curve drifts a fixed distance every frame, and this way can cover the non-scanned area of the previous lissajous curve, so that the scanning covers the whole scanning area, and the scanning blind area is avoided. The relationship between the angular resolution of the multiline lidar and the rotation periods of the primary rotating mirror 132 and the secondary rotating mirror 134 is as follows:

wherein n is a positive integer, and n is the complete ring number contained in the Lissajous curve scanning track in one rotation period of the secondary rotating mirror. The angular resolution of the laser radar is ω, the rotation period of the main rotating mirror 132 is T, and the rotation period of the sub rotating mirror 134 is T. The period T of the main rotating mirror 132 and the period T of the secondary rotating mirror 134 can be adjusted by controlling the rotation speed of the main rotating mirror 132 and the secondary rotating mirror 134, and the proper angular resolution ω of the laser radar scanning can be obtained. Illustratively, when the angular resolution is 0.25, then,

as shown in fig. 4, the sub-mirror 134 rotates for one cycle to complete one scanning cycle, forming a scanning trajectory of the lissajous curve of the first frame. The secondary mirror 134 rotates to complete the next scanning cycle, forming the scanning trajectory of the lissajous curve for the second frame. The Lissajous curve of the second frame is staggered by 0.25 degrees compared with the Lissajous curve of the first frame, and the gap between rings in the Lissajous curve scanning track of the first frame is covered, so that the Lissajous curve scanning track of the next frame can cover the non-scanning area of the Lissajous curve scanning track of the previous frame, and the scanning resolution is improved.

In one embodiment, as shown in FIG. 1, the multiline lidar further includes a collimating lens group 114. The collimating lens group 114 is used for collimating the outgoing laser light emitted by the laser emitting device 110. In the present embodiment, collimating lens group 114 is disposed between laser emitting device 110 and primary turning mirror 132. The emitted laser light is generally divergent, and after the emitted laser light emitted by the laser emitting device 110 passes through the collimating lens group 114, the emitted laser light is emitted to the primary rotating mirror 132 as a substantially parallel beam. In other embodiments, laser emitting device 110 includes a laser and a modulator, such as a frequency modulator, that modulates the emitted outgoing laser light, emitting the outgoing laser light at a fixed frequency.

In one embodiment, as shown in FIG. 1, the multiline lidar further includes a focusing lens group 124. The focusing lens group 124 is used for focusing the reflected laser light to the laser receiving device 120. In the present embodiment, the focusing lens group 124 is disposed between the laser receiving device 120 and the main rotating mirror 132. The focusing lens group 124 can converge the reflected laser light and receive the laser light by the laser receiving device 120. In one embodiment, the focusing lens group 124 is a Fresnel lens. The Fresnel lens only keeps a curved surface which is refracted, a large amount of materials are saved, the same light condensation effect is achieved, and cost reduction is facilitated.

In one embodiment, the number of the laser emitting devices 110 and the number of the laser receiving devices 120 are both 1. Only one laser emitting device 110 is needed to emit a beam of emergent laser, and the scanning effect of the multi-line laser radar with high resolution can be realized through the action of the main rotating mirror 132 and the secondary rotating mirror 134. Meanwhile, only one laser receiving device 120 is needed to receive the reflected laser light reflected by the detected object. Compared with the traditional multi-line laser radar, the laser radar has the advantages of simple structure and cost saving.

In one embodiment, the rotational drive system 180 includes a rotational drive device, a first linkage assembly, a second linkage assembly, and an encoder. The first connection assembly is connected to the rotation driving device and the main turning mirror 132, respectively. The rotation driving device drives the main rotating mirror 132 to rotate through the first connecting assembly. The second connecting assembly is connected to the rotary drive and the secondary mirror 134, respectively. The rotation driving device drives the secondary rotating mirror 134 to rotate through the second connecting assembly. The encoders are used to measure the rotational speed and position of the primary and secondary turning mirrors 132, 134. Optionally, the rotary drive is a motor. Optionally, the first connecting assembly is a first gear set, and the rotation driving device drives the main rotating mirror to rotate through the first gear set. Optionally, the second connecting assembly is a second gear set, and the rotation driving device drives the secondary rotating mirror to rotate through the second gear set. Optionally, the rotation driving device 140 includes a first motor 142 and a second motor 144, the first motor 142 drives the primary rotating mirror 132 to rotate through a first connecting assembly 182, and the second motor 144 drives the secondary rotating mirror 134 to rotate through a second connecting assembly 184, as shown in fig. 1; the encoder 150 includes a first encoder 152 and a second encoder 154; a first encoder 152 is provided on the rotation shaft of the main turning mirror 132 for measuring the rotation speed and position of the main turning mirror 132; the second encoder 154 is provided on the rotation shaft of the sub-mirror 134, and measures the rotation speed and position of the sub-mirror 134.

In one embodiment, the laser emitting device 110 further includes an isolator. The isolator is disposed between the laser and the main turning mirror 132. The isolator is used for isolating the reflected laser light. In other embodiments, the projection of the isolator onto the laser surface does not intersect the projection of the focusing lens group 124 onto the laser surface, so that the reflected laser light does not strike the laser and does not block the reflected laser light converged by the focusing lens group 124. The isolator is arranged in the laser emitting device 110, so that the problem that a part of light is projected to the laser to reduce the service life of the laser in the process that the emergent laser is received by the laser receiving device 120 can be avoided.

In one embodiment, the above described multiline lidar further includes a housing 160 and a control board 170, as shown in fig. 1. The rotary drive system 180, the laser emitting device 110, the laser receiving device 120, and the control board 170 are all fixedly disposed within the housing 160. The control board 170 is electrically connected to the laser emitting device 110, the laser receiving device 120, and the rotation driving system 180. Optionally, the control board 170 is disposed below the laser emitting device 110 and the laser receiving device 120, so as to facilitate power supply and communication.

In one embodiment, the housing 160 includes a transmissive region 162 located around the secondary mirror 134. The transmission region 162 is a filter region through which the emitted laser can pass and project to the scanning region, and the reflected laser reflected by the detection object in the scanning region can pass through the filter region to the inside of the multi-line lidar. Alternatively, the transmissive region 162 is disposed obliquely toward the secondary mirror 134, i.e., the transmissive region 162 forms a tapered structure that gradually expands from top to bottom. In other embodiments, the transmissive region 162 may not be defined.

In one embodiment, the laser emitting device 110 emits the outgoing laser light as a pulse-type outgoing laser light. The pulse laser has larger output power, and can enable the measuring result to be more accurate.

In one embodiment, the multiline lidar may be formed as a multi-segmented structure based on the volume occupied by internal components. The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. A multiline lidar comprising:

the laser emitting device is used for emitting emergent laser;

2. Multiline lidar according to claim 1, wherein the axis of rotation of said primary turning mirror is at 45 degrees to the horizontal; the included angle between the normal line of the main rotating mirror and the rotating shaft of the main rotating mirror is a first angle, and the first angle is not zero.

3. Multiline lidar according to claim 2, wherein the axis of rotation of said secondary mirror is in a vertical direction; the included angle between the normal of the secondary rotating mirror and the rotating shaft of the secondary rotating mirror is a second angle; the second angle and the first angle cooperate to determine a scanning angle range of the emergent laser light in the longitudinal direction.

4. Multiline lidar according to claim 1 wherein the rotational speed of said primary mirror is greater than the rotational speed of said secondary mirror.

5. Multiline lidar according to claim 4, wherein the rotational speed of the primary turning mirror is N times the rotational speed of the secondary turning mirror; n is a non-integer and the range of N is 10-100.

6. The multiline lidar of claim 1 further comprising a collimating lens group; the collimating lens group is used for collimating emergent laser emitted by the laser emitting device.

7. The multiline lidar of claim 1 further comprising a focusing lens group; the focusing lens group is used for focusing the reflected laser to the laser receiving device.

8. Multiline lidar according to claim 1, wherein the number of said laser transmitter and said laser receiver is 1.

9. Multiline lidar according to claim 1 wherein said rotary drive system includes a rotary drive, a first linkage assembly, a second linkage assembly and an encoder; the rotation driving device drives the main rotating mirror to rotate through the first connecting assembly; the rotation driving device drives the secondary rotating mirror to rotate through the second connecting assembly; the encoder is used for measuring the rotating speed and the position of the main rotating mirror and the secondary rotating mirror.

10. The multiline lidar of claim 1 further comprising a control board; the control panel is also arranged in the shell; the control panel is electrically connected with the laser emitting device, the laser receiving device and the rotary driving system.