WO2021218362A1

WO2021218362A1 - Coaxial laser radar system based on one-dimensional galvanometer and polyhedral rotating mirror

Info

Publication number: WO2021218362A1
Application number: PCT/CN2021/078772
Authority: WO
Inventors: 毛胜平; 向少卿
Original assignee: 上海禾赛科技股份有限公司
Priority date: 2020-04-26
Filing date: 2021-03-02
Publication date: 2021-11-04
Also published as: CN113640812A

Abstract

A transmitting unit and a receiving unit of a laser radar based on a one-dimensional galvanometer and a polyhedral rotating mirror, as well as a coaxial laser radar, capable of effectively preventing field distortion by selecting the swinging frequency of the one-dimensional galvanometer and the rotating frequency of the polyhedral rotating mirror. The transmitting unit (10) applicable to the laser radar comprises: a laser (11) array independently driven to emit a light beam; a one-dimensional galvanometer (12) provided downstream of a light path of the laser (11), having a first reflecting surface (121) and a first rotating shaft (122) along a first direction, rotating about the first rotating shaft (122), and reflecting the laser beam incident thereon; and a polyhedral rotating mirror (13) provided downstream of a light path of the one-dimensional galvanometer (12), and having a plurality of second reflecting surfaces (131) and a second rotating shaft (132) along a second direction. The first direction is perpendicular to the second direction. The polyhedral rotating mirror can rotate about the second rotating shaft (132). The second reflecting surfaces (131) can reflect light beams incident thereon outside of the laser radar for detecting a target object.

Description

Coaxial lidar system based on one-dimensional galvanometer and polygon mirror

Technical field

The present invention generally relates to the field of laser detection technology, and more particularly to a laser radar transmitting unit, receiving unit and laser radar including a one-dimensional galvanometer and a polygon mirror.

Background technique

The lidar system includes a laser emission system and a detection and reception system. The emitted laser is reflected after encountering the target and is received by the detection system. The distance between the target and the radar can be measured by measuring the round-trip time of the laser (time-of-flight method). After area scanning and detection, three-dimensional imaging can finally be realized. As a commonly used ranging sensor, Lidar has the advantages of long detection distance, high resolution, strong anti-active interference ability, small size, and light weight. It is widely used in intelligent robots, unmanned aerial vehicles, unmanned driving, etc. field.

The scanning methods of lidar systems generally include oscillating (pendulum) scanning, rotating polygon mirror scanning, nutation scanning and fiber scanning. The scanning method of the lidar largely determines the field of view and resolution of the lidar. A reasonable scanning structure promotes the stability of the entire lidar system, and can obtain a larger field of view and higher angular resolution.

The content of the background technology is only the technology known to the public, and does not of course represent the existing technology in the field.

Summary of the invention

In view of at least one defect of the prior art, the present invention provides a laser radar transmitting unit, a receiving unit and a laser radar including a one-dimensional galvanometer and a polygon mirror.

The present invention provides a transmitting unit that can be used for lidar, including:

Laser array, each laser can be individually driven to emit a laser beam;

A one-dimensional galvanometer, the one-dimensional galvanometer is arranged downstream of the optical path of the laser, has a first reflecting surface and a first rotation axis along a first direction, the one-dimensional galvanometer can rotate around the first rotation axis , And reflect the laser beam incident on it;

A polygon mirror, the polygon mirror is arranged downstream of the optical path of the one-dimensional galvanometer, and has a plurality of second reflection surfaces and a second rotation axis along a second direction, wherein the first direction is perpendicular to the second Direction, the polygon mirror can rotate around the second rotation axis, and the second reflection surface can reflect the laser beam incident on it to the outside of the lidar for detecting a target.

According to one aspect of the present invention, the transmitting unit further includes a fast axis compression lens and a converging lens, which are sequentially arranged between the laser and the one-dimensional galvanometer, wherein the fast axis compression lens is configured to receive and compress The divergence angle of the laser beam emitted by the laser along the fast axis direction, the converging lens is configured to converge the compressed laser beam, and the one-dimensional galvanometer is arranged at the focal position of the converging lens .

According to an aspect of the present invention, the emitting unit further includes a fast axis compression lens between the laser and the one-dimensional galvanometer and a converging lens between the one-dimensional galvanometer and the polygon mirror , Wherein the fast axis compression lens is configured to receive and compress the divergence angle of the laser beam emitted by the laser along the fast axis direction, and the converging lens is configured to converge the laser beam reflected by the one-dimensional galvanometer To the multi-sided rotating mirror.

According to an aspect of the present invention, the one-dimensional galvanometer includes a galvanometer mechanical resonator mirror or a MEMS galvanometer mirror.

According to an aspect of the present invention, the one-dimensional galvanometer works at its resonance frequency, and the ratio of the resonance frequency to the rotation frequency of the polygon mirror is an integer greater than 1.

According to one aspect of the present invention, the transmitting unit further includes a laser driving circuit configured to obtain the current real-time vertical angle and horizontal angle through the position feedback of the galvanometer and the polygon mirror respectively, so as to determine whether to trigger the laser Glow.

The present invention also provides a receiving unit that can be used for lidar, which includes a detector array, a one-dimensional galvanometer and a polygon mirror,

The detector array includes a plurality of detectors, and each detector can receive the echo of the lidar and convert it into an electric signal;

A polygon mirror, the polygon mirror is provided with a plurality of second reflection surfaces and a second rotation axis along a second direction, the polygon rotation mirror can rotate around the second rotation axis, and the second reflection surface can rotate The echo incident thereon is reflected on the one-dimensional galvanometer;

The one-dimensional galvanometer is arranged on the optical path between the detector array and the polygon mirror, and has a first reflecting surface and a first rotation axis along a first direction. The one-dimensional galvanometer can surround the The first rotating shaft rotates and reflects the echo incident thereon to the detector array, wherein the first direction is perpendicular to the second direction.

According to an aspect of the present invention, the receiving unit further includes a condensing lens disposed between the detector array and the one-dimensional galvanometer or between the one-dimensional galvanometer and the polygon mirror .

The present invention also provides a laser radar, including:

The transmitting unit as described above is configured to emit a detection laser beam for detecting a target object;

The receiving unit as described above, configured to receive echoes and convert them into electrical signals; and

The point cloud generating unit is coupled to the transmitting unit and the receiving unit, and is configured to calculate the distance of the target object according to the flight time of the detection laser beam, and generate a point cloud.

The present invention also provides a laser radar, including:

Laser array, each laser can be individually driven to emit a laser beam;

The detector array includes multiple detectors, each of which can receive the echo of the lidar and convert it into an electrical signal;

A beam splitter is arranged between the laser and the one-dimensional galvanometer to allow a part of the laser beam emitted by the laser to pass and be incident on the one-dimensional galvanometer;

A polygon mirror, the polygon mirror is arranged downstream of the optical path of the one-dimensional galvanometer, and has a plurality of second reflection surfaces and a second rotation axis along a second direction, wherein the first direction is perpendicular to the second Direction, the polygon mirror can rotate around the second rotation axis, the second reflective surface can reflect the laser beam incident on it to the outside of the lidar for detecting the target; the second reflective surface and The echo can be reflected on the one-dimensional galvanometer, and after being reflected by the one-dimensional galvanometer, it passes through the beam splitter and is incident on the detector array.

According to an aspect of the present invention, the lidar further includes a fast axis compression lens and a converging lens, wherein the fast axis compression lens is disposed between the laser and the beam splitter, and is configured to receive and compress the laser The divergence angle of the emitted laser beam along the fast axis direction. The condensing lens is arranged between the one-dimensional galvanometer and the polygon mirror, and is configured to converge the compressed laser beam. The echoes reflected by the polygon mirror converge on the one-dimensional galvanometer, wherein the one-dimensional galvanometer is arranged at the focal position of the converging lens.

According to an aspect of the present invention, the lidar further includes a fast axis compression lens between the laser and the beam splitter, and a converging lens between the beam splitter and the one-dimensional galvanometer, wherein The fast axis compression lens is configured to receive and compress the divergence angle of the laser beam emitted by the laser along the fast axis direction.

The present invention also provides a detection method using the lidar as described above.

The preferred embodiment of the present invention provides a laser radar transmitting unit, a receiving unit, and a coaxial laser radar transceiver system based on a one-dimensional galvanometer mirror and a polygon mirror. The choice of, improves the angular resolution of the lidar system, expands the vertical and horizontal field of view angles, and effectively prevents field of view distortion.

Description of the drawings

The drawings constituting a part of the present disclosure are used to provide a further understanding of the present disclosure. The exemplary embodiments and descriptions of the present disclosure are used to explain the present disclosure, and do not constitute an improper limitation of the present disclosure. In the attached picture:

Fig. 1 schematically shows a transmitting unit of a lidar according to a preferred embodiment of the present invention;

Fig. 2 schematically shows a transmitting unit of a lidar according to another preferred embodiment of the present invention;

Fig. 3 schematically shows a transmitting unit of a lidar according to another preferred embodiment of the present invention;

Fig. 4 schematically shows a transmitting unit of a lidar according to another preferred embodiment of the present invention;

Figure 5 shows a laser control method that can be used for the transmitting unit

Fig. 6 schematically shows a receiving unit of a lidar according to a preferred embodiment of the present invention;

Fig. 7 schematically shows a receiving unit of a lidar according to another preferred embodiment of the present invention;

Fig. 8 schematically shows a laser radar according to a preferred embodiment of the present invention;

Fig. 9 schematically shows a laser radar according to another preferred embodiment of the present invention;

Fig. 10A schematically shows a schematic diagram of a point cloud result according to a preferred embodiment of the present invention;

FIG. 10B schematically shows a schematic diagram of a point cloud result according to another preferred embodiment of the present invention;

FIG. 10C schematically shows a schematic diagram of a point cloud result according to another preferred embodiment of the present invention;

FIG. 11A schematically shows a schematic diagram of a point cloud result according to another preferred embodiment of the present invention;

FIG. 11B schematically shows a schematic diagram of a point cloud result according to another preferred embodiment of the present invention.

Detailed ways

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

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " "Back", "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inner", "Outer", "Clockwise", "Counterclockwise" and other directions or The positional relationship is based on the position or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the pointed device or element must have a specific orientation, be constructed and operated in a specific orientation, Therefore, it cannot be understood as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more than two, unless otherwise specifically defined.

In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected or integrally connected: It can be mechanically connected, or electrically connected or can communicate with each other; it can be directly connected or indirectly connected through an intermediate medium, which can be the internal communication of two components or the interaction of two components relation. For those of ordinary skill in the art, the specific meanings of the above-mentioned terms in the present invention can be understood according to specific situations.

In the present invention, unless otherwise clearly defined and defined, the "on" or "under" of the first feature of the second feature may include the first and second features in direct contact, or may include the first and second features Not in direct contact but through other features between them. Moreover, the "above", "above", and "above" of the first feature on the second feature include the first feature directly above and diagonally above the second feature, or it simply means that the first feature is higher in level than the second feature. The “below”, “below” and “below” of the first feature of the second feature include the first feature directly above and diagonally above the second feature, or it simply means that the level of the first feature is smaller than the second feature.

The following disclosure provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention may repeat reference numerals and/or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, and does not indicate the relationship between the various embodiments and/or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and/or the use of other materials.

The preferred embodiments of the present invention will be described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

As shown in FIG. 1, according to a preferred embodiment of the present invention, the present invention provides a transmitting unit 10 that can be used for lidar, which includes an array of lasers 11, a one-dimensional galvanometer 12 and a polygon mirror 13. Each of the lasers 11 can be individually driven to emit a laser beam. The one-dimensional galvanometer 12 may be, for example, a galvanometer mechanical resonator mirror or a MEMS galvanometer, which is arranged downstream of the optical path of the laser 11 and has a first reflecting surface 121 and a first rotation axis 122. The one-dimensional galvanometer 12 can rotate around the first rotation axis 122 , And reflect the laser beam incident on it. In FIG. 1, the first rotating shaft 122 is in a direction perpendicular to the surface of the paper. When the one-dimensional galvanometer 12 rotates to different positions around the first rotating shaft 122, it can reflect the laser beam incident on it to different exit directions. Therefore, for the same laser 11, through the rotation scanning of the one-dimensional galvanometer 12, the laser beams emitted in multiple directions are realized, that is, the encryption of the laser beams is realized. The polygon mirror 13 is arranged downstream of the optical path of the one-dimensional galvanometer 12, and has a plurality of second reflecting surfaces 131 and a second rotation axis 132, wherein the direction of the first rotation axis 122 is perpendicular to the direction of the second rotation axis 132, and the polygon mirror 13 It can rotate around the second rotating shaft 132, and the second reflecting surface 131 can reflect the laser beam incident on it to the outside of the lidar for detecting the target. As shown in Fig. 1 schematically, the polygon mirror 13 is a four-sided mirror whose four sides can be used as the second reflecting surface 131. The second rotation axis 132 is along the vertical direction in the figure. When the polygon mirror 13 surrounds When the second rotating shaft 132 rotates, the plurality of second reflecting surfaces 131 are sequentially rotated to a position facing the one-dimensional galvanometer 12, so that the laser beam from the one-dimensional galvanometer 12 can be reflected twice and reflected to the lidar External, used to detect targets. In addition, those skilled in the art can easily understand that in addition to four-sided rotating mirrors, three-sided rotating mirrors, five-sided rotating mirrors, and more polygonal rotating mirrors can also be used. In addition, preferably, the rotating mirror is a regular polygon rotating mirror.

As shown in FIG. 1, the transmitting unit 10 may further include a fast axis compression lens 14 and a converging lens 15, which are sequentially arranged between the laser 11 and the one-dimensional galvanometer 12. The fast axis compression lens 14 is configured to receive and compress the laser 11 emission. The divergence angle of the laser beam along the fast axis direction. When the laser 11 adopts a vertical cavity surface emitting laser VCSEL, the divergence angle of the laser beam along the fast axis is relatively large. Therefore, the divergence angle of the laser beam along the fast axis direction can be compressed by the fast axis compression lens 14 to make it Closer to a parallel beam. The condensing lens 15 is configured to converge the compressed laser beam. The one-dimensional galvanometer 12 is arranged at the focal position of the condensing lens 15, so the laser beam condensed by the condensing lens 15 is focused on the one. Dimension galvanometer 12 is on.

Fig. 2 shows a transmitting unit 20 that can be used for lidar according to a preferred embodiment of the present invention. The following focuses on the differences between the transmitting unit 20 of the embodiment of FIG. 2 and the transmitting unit 10 of the embodiment of FIG. 1. As shown in FIG. 2, the fast axis compression lens 14 is arranged between the laser 11 and the one-dimensional galvanometer 12, and the convergent lens 15 is arranged between the one-dimensional galvanometer 12 and the polygon mirror 13. The laser 11 is driven to emit a laser beam. The fast axis compression lens 14 compresses the divergence angle of the laser beam emitted by the laser 11 along the fast axis direction. The one-dimensional galvanometer 12 is arranged downstream of the optical path of the fast axis compression lens 14 and has a first reflection With the surface 121 and the first rotating shaft 122, the one-dimensional galvanometer 12 can rotate around the first rotating shaft 122 and reflect the laser beam incident on it. The laser beam reflected by the one-dimensional galvanometer 12 is received by the converging lens 15, and Converging them on the polygon mirror 13, the polygon mirror has a plurality of second reflecting surfaces 131 and a second rotation axis 132, wherein the direction of the first rotation axis 122 is perpendicular to the direction of the second rotation axis 132, and the polygon mirror 13 can surround the first rotation axis 132. The two rotating shafts 132 rotate, and the second reflecting surface 131 can reflect the laser beam incident thereon to the outside of the lidar for detecting the target. In the embodiment of FIG. 1 and FIG. 2, the one-dimensional galvanometer 12 may be a galvanometer mechanical resonator mirror or a MEMS galvanometer mirror.

When used in a lidar, the one-dimensional galvanometer 12 can provide a scanning field of view in the vertical direction of the lidar, and the polygon mirror 13 can provide a scanning field of view in the horizontal direction of the lidar.

It can be seen from the above two preferred embodiments that when the one-dimensional galvanometer 12 is between the laser 11 and the converging lens 15 (the transmitting unit 20 shown in FIG. 2), the swing amplitude of the one-dimensional galvanometer 12 needs to be greater than that of the lidar The vertical field of view of the system can provide a wider field of view, which is condensed by the condensing lens 15 to form an outgoing beam. When the one-dimensional galvanometer 12 is behind the condensing lens 15 (the transmitting unit 10 shown in FIG. 1), the swing amplitude of the one-dimensional galvanometer 12 is equivalent to the vertical field of view of the lidar system, but in this case, the incident The light beam to the one-dimensional galvanometer 12 has diverged, and the one-dimensional galvanometer 12 is required to have a larger aperture. When the one-dimensional galvanometer has a large aperture, it can work reliably at a lower speed and a smaller swing. At this time, the system's vertical field of view and the number of lines can be compensated by the arrangement of multiple transceiver pairs.

3 and 4 show the situation when the emitting unit uses a laser array (an array composed of a plurality of lasers 11) to emit a laser beam. According to a preferred embodiment of the present invention, the transmitting unit 30 of the laser radar is shown in FIG. 3. Each laser of the multiple lasers 11 can be driven separately to emit a laser beam. The light path of the beam travels in the same direction, which will not be repeated here. In particular, it needs to be pointed out that the one-dimensional galvanometer 12 can be set at the focal position of the converging lens 15, so that a galvanometer with a relatively small aperture can scan all the light beams.

If a large number of lasers 11 are used and a certain angular resolution and field of view range in the vertical direction have been ensured, the requirements for the swing amplitude and scanning frequency of the one-dimensional galvanometer 12 will be reduced. A plurality of vibrating mirrors 12 are arranged between the laser 11 and the converging lens 15, as shown in FIG. 4.

It can be seen from the above two preferred embodiments that the vertical field of view angle of the multi-line lidar system is mainly determined by the array of multiple lasers 11 and various parameters of the converging lens 15, and the one-dimensional galvanometer 12 surrounds The laser beam within the vertical field of view angle range is micro-scanned to encrypt the angular resolution in the vertical direction.

According to the vertical field of view and angular resolution required by the actual detection requirements of the lidar system, as well as the number of lines of the lidar, the distance between the fast axis (one-dimensional galvanometer scan) and the slow axis (multi-sided rotating mirror scan) can be calculated The frequency ratio of N, where N is a positive integer. In order to avoid fluctuations in the point cloud caused by changes in the frequency of the one-dimensional galvanometer due to changes in temperature or environment, it is necessary to lock the rotation frequency of the polygon mirror and the swing frequency of the one-dimensional galvanometer in real time at the moment of light emission (ie, maintain a constant ratio). In the fast axis direction, the phase-locked loop is used to ensure that the one-dimensional galvanometer works at the resonant frequency. The real-time frequency of the one-dimensional galvanometer swing is the main frequency, which is recorded as fr. The rotating frequency followed by the polygon mirror is the slave frequency, which is based on the main frequency. Change the real-time adjustment of the slave frequency to fr/N, so as to keep the angular resolution of the lidar system as constant as possible. When the real-time frequency of the one-dimensional galvanometer swing changes too much, the overall field of view can be zoomed by changing the frequency ratio N, of course, the angular resolution of the system should be maintained as much as possible.

FIG. 5 shows a laser control method 100 that can be used in the above-mentioned emitting

unit

10 or 20, including:

In step S101, a phase locked loop is used in the fast axis direction to ensure that the one-dimensional galvanometer 12 works at the resonant frequency, and its real-time frequency is fr.

In step S102, in the slow axis direction, the rotation speed of the polygon mirror 13 is adjusted to set it to fr/N.

In step S103, the positions or states of the one-dimensional galvanometer 12 and the polygon mirror 13 (that is, corresponding to the vertical angle and the horizontal angle respectively) are obtained through position feedback.

In step S104, the laser is triggered to emit light.

In order to reduce the distortion during scanning with a large field of view, each laser pulse should be perpendicularly incident on the galvanometer and polygon mirror at the initial moment of emission. According to a preferred embodiment of the present invention, as shown in Figure 1, Figure 2, and Figure 3 The transmitting

units

10, 20, 30, and 40 of the lidar shown in FIG. 4 also include a laser driving circuit configured to obtain the current real-time vertical angle through the position feedback of the one-dimensional galvanometer and the polygon mirror. And the horizontal angle to determine whether to trigger the laser to emit light. It corresponds to the vertical angle and the horizontal angle when it will emit light, which can be set as required. For example, if you only pay attention to obstacle information in a certain horizontal angle range [α1,α2], you can start the laser to emit light when the angle is rotated to α1, and stop emitting light when the angle is rotated to α2.

According to a preferred embodiment of the present invention, the vertical field of view of the lidar system can reach tens of degrees (depending on the length of the laser array at the transmitter, the focal length of the converging lens and the swing of the one-dimensional galvanometer), and the horizontal field of view can be from several Degree to more than 100 degrees (depending on the number of faces of the polygon mirror).

As shown in FIG. 6, according to a preferred embodiment of the present invention, the present invention also provides a receiving unit 50 that can be used for lidar, including a detector array 51, a one-dimensional galvanometer 12 and a polygon mirror 13. The detector array 51 includes a plurality of detectors, and each detector can receive the echo of the lidar and convert it into an electric signal. The polygon mirror 13 has a plurality of second reflecting surfaces 131 and a second rotating shaft 132. The polygon mirror 13 It can rotate around the second rotation axis 132, and the second reflecting surface 131 can reflect the echo incident thereon to the one-dimensional galvanometer 12, which is arranged between the detector array 51 and the polygon mirror 13 The optical path has a first reflecting surface 121 and a first rotating shaft 122. The one-dimensional galvanometer 12 can rotate around the first rotating shaft 122 and reflect the echo incident on it to the detector array 51. The direction is perpendicular to the direction of the second rotating shaft 132.

The receiving unit 50 also includes a condensing lens 15, which is arranged between the one-dimensional galvanometer 12 and the polygon mirror 13, or is arranged between the detector array 51 and the one-dimensional galvanometer 12 (as shown in FIG. 7 for the laser Radar receiving unit 60).

The preferred embodiment of FIG. 6 shows a beam splitter 16 which is suitable for a coaxial transmission and reception system of a laser radar. The beam splitter 16 uses a semi-reflective and semi-transmissive optical surface to separate the emitted light beam from the radar echo. According to a preferred embodiment of the present invention, the one-dimensional galvanometer 12 includes a galvanometer mechanical resonator mirror and a MEMS galvanometer. The one-dimensional galvanometer 12 works at its resonance frequency. The ratio of the resonance frequency to the rotation frequency of the polygon mirror 13 Is an integer greater than 1.

The laser control method 100 shown in FIG. 5 can also be applied to the receiving units of FIGS. 6 and 7. For example, a phase-locked loop can also be used to ensure that the one-dimensional galvanometer 12 works at the resonant frequency, and its real-time frequency is fr, which is in the slow axis direction. Above, adjust the implementation speed of the polygon mirror 13, set it to fr/N, and obtain the position or state of the one-dimensional galvanometer 12 and the polygon mirror 13 (that is, corresponding to the vertical angle and the horizontal angle, respectively) through position feedback. ), and read the output of the detector array 51 at an appropriate time.

According to a preferred embodiment of the present invention, the present invention also provides a laser radar, comprising: one or more of the above-mentioned laser

radar transmitting units

10, 20, 30, and 40, configured to emit detection laser The beam is used to detect the target; one or more of the receiving

units

50 and 60 of the lidar as described above are configured to receive echoes and convert them into electrical signals; the point cloud generation unit, and the transmitting unit and the receiving unit It is coupled and configured to calculate the distance of the target object according to the flight time of the detection laser beam, and generate a point cloud.

As shown in FIG. 8, according to a preferred embodiment of the present invention, the present invention also provides a laser radar 70, including: an array of lasers 11, each of which can be individually driven to emit a laser beam, and a detector array 51 including: A plurality of detectors, each detector can receive the echo of the lidar and convert it into an electrical signal. The one-dimensional galvanometer 12 is arranged downstream of the optical path of the laser 11 and has a first reflecting surface 121 and a first rotating shaft 122. The mirror 12 can rotate around the first rotation axis 122 and reflect the laser beam incident on it. The beam splitter 16 is arranged between the laser 11 and the one-dimensional galvanometer 12 to allow the laser beam emitted by the laser 11 to pass through and be incident on it. The one-dimensional galvanometer 12, the polygon mirror 13 is arranged downstream of the optical path of the one-dimensional galvanometer 12, and has a plurality of second reflecting surfaces 131 and a second rotating shaft 132, wherein the direction of the first rotating shaft 122 is perpendicular to the direction of the second rotating shaft 132 , The polygon mirror 13 can rotate around the second rotation axis 132, the second reflective surface 131 can reflect the laser beam incident on it to the outside of the lidar for detecting the target, and the second reflective surface 131 can also echo It is reflected on the one-dimensional galvanometer 12, passes through the beam splitter 16 after being reflected by the one-dimensional galvanometer 12, and is incident on the detector array 51.

In order to ensure the stability of the generated point cloud image, the scanning frequency of the reciprocating swing of the one-dimensional galvanometer 12 should match the radar frame frequency. For example, the radar frame frequency is 10 Hz. (Sweep horizontal direction of light emission misalignment), the swing frequency of the one-dimensional galvanometer should be set to 10 Hz, if one frame is being scanned, and the retrace is the next frame, the swing frequency should be set to 5 Hz.

In a lidar system in which a one-dimensional galvanometer and a polygon mirror are coupled, only the reflection result of one reflective surface of the polygon mirror can be used as a radar independent frame, then the rotation frequency of the polygon mirror is equal to the radar frame frequency; The reflection results of multiple reflective surfaces of the polygon mirror can be combined into one frame, then the rotation frequency of the polygon mirror = the radar frame frequency * the number of reflective surfaces.

The lidar 70 also includes a fast axis compression lens 14 and a converging lens 15. The fast axis compression lens 14 is arranged between the laser 11 and the beam splitter 16, and is configured to receive and compress the divergence of the laser beam emitted by the laser 11 along the fast axis direction. Angle, the converging lens 15 is arranged between the one-dimensional galvanometer 12 and the polygon mirror 13, and is configured to converge the compressed laser beam and converge the echoes reflected by the polygon mirror 13 to the one-dimensional galvanometer 12 Above, the one-dimensional galvanometer 12 is set at the focal position of the converging lens 15.

According to a preferred embodiment of the present invention, the present invention also provides a laser radar 80, as shown in FIG. 9: the fast axis compression lens 14 is arranged between the laser 11 and the beam splitter 16, and the converging lens 15 is arranged between the beam splitter 16 and the beam splitter 16 Between 12 one-dimensional galvanometers.

According to a preferred embodiment of the present invention, the present invention also provides a double-sided transceiving coaxial lidar system. Except for the polygon mirror 13, other components need to use two sets and are arranged on both sides of the polygon mirror 13.

Different point cloud images can be obtained by using different relative speeds or frequencies of a one-dimensional galvanometer (mainly responsible for scanning in the vertical direction) and a multi-sided rotating mirror (mainly responsible for scanning in the horizontal direction).

For example, as shown in FIG. 10A, it is a schematic diagram of the point cloud result of a single laser scanning according to the present invention. A row in the point cloud diagram corresponds to a reflective surface of a multi-face rotating mirror, where surface 1, surface 2, surface 3, and surface 4 are respectively Corresponding to the first, second, third and fourth sides of the polygon mirror. It can be seen from the point cloud results that the swing frequency of the one-dimensional galvanometer in the vertical direction of the preferred embodiment is higher, and the rotation frequency of the polygon mirror in the horizontal direction is lower, which increases the light emission interval in the vertical direction, which is beneficial in It can still maintain a high vertical resolution when the flight time is insufficient.

For another example, as shown in FIG. 10B, it is another schematic diagram of the point cloud results of a single laser scanning according to the present invention. 4 respectively correspond to the first, second, third and fourth surfaces of the polygon mirror. It can be seen from the point cloud results that the rotation frequency of the polygon mirror in the horizontal direction of the preferred embodiment is higher, and the swing frequency of the one-dimensional galvanometer mirror in the vertical direction is lower.

As shown in FIG. 10C, a schematic diagram of the point cloud results of multi-laser scanning according to the present invention. In this embodiment, multiple lasers are scanned in parallel in the horizontal direction, and the laser array includes four lasers as an example, each of which is laser 1. , Laser 2, laser 3 and laser 4, face 1, face 2, face 3, face 4 respectively correspond to the first face, second face, third face and fourth face of the polygon mirror. In FIG. 10C, one row corresponds to one rotating mirror reflecting surface, which increases the light-emitting interval in the vertical direction, which helps to maintain a high vertical resolution even when the flight time is insufficient. The other dimension (horizontal direction) is realized and scanned by several lasers next to each other, thereby improving the horizontal resolution and also helping to reduce the resonant frequency required by the galvanometer. The preferred embodiment reduces the requirement on the rotation frequency of the polygon mirror, thereby also reducing the resonant frequency required by the one-dimensional galvanometer.

For example, as shown in FIG. 11A, it is a schematic diagram of the point cloud results according to a preferred embodiment of the present invention, in which for one surface of the polygon mirror, multiple lasers emit light at the same time (especially, the light may be emitted at intervals) . This embodiment adopts a multi-line lidar. At the same time, multiple lasers emit light in the vertical direction at the same time. Among them, surface 1, surface 2, surface 3, and surface 4 correspond to the first surface, second surface, and third surface of the polygon mirror, respectively. On the fourth side, the laser array includes four lasers, namely laser 1, laser 2, laser 3, and laser 4. The laser array should emit light at equal angles in the vertical direction every time the one-dimensional galvanometer swings to the same position. The position of the one-dimensional galvanometer can be fed back by the angle sensor. In this preferred embodiment, the number of light-emitting times of the one-dimensional galvanometer is conjugate to the number of mirror surfaces of the polygon mirror, which is an integer multiple of the number of mirror surfaces of the polygon mirror.

For example, as shown in FIG. 11B, according to a schematic diagram of the point cloud results of a preferred embodiment of the present invention, the laser array in the vertical direction emits light periodically in order. This preferred embodiment reduces the optical crosstalk that may exist when multiple lasers emit light at the same time. problem.

In the above-mentioned preferred embodiment of the present invention, the laser array includes a discrete edge-emitting laser combination array, a monolithic edge-emitting laser array, a VCSEL array, a solid laser array, and a single fiber laser. If you use high repetition frequency devices such as fiber lasers, you can use a single laser to scan; if you use semiconductor lasers, when the system requires too high a frequency, a single laser repetition cannot meet the requirements of use, and you can use a scanning method with multiple lasers arranged in parallel. At the same time, the requirements for the swing frequency of the one-dimensional galvanometer can be reduced.

In the above-mentioned preferred embodiment of the present invention, the detector array includes a plurality of APD combination arrays, a whole-chip APD array, SiPM array, and SPAD array. The beam splitter includes a typical small hole reflector and PBS polarizing beam splitter. The light spot drift in the vertical direction caused by the high-speed scanning of the galvanometer can be adjusted by the dynamic compensation of the receiving end.

The present invention also provides a detection method using the above-mentioned lidar.

The preferred embodiment of the present invention provides a laser radar transmitting unit, a receiving unit, and a coaxial laser radar transceiver system based on a one-dimensional galvanometer mirror and a polygon mirror. The choice of, improves the angular resolution of the lidar system, expands the vertical and horizontal field of view angles, and effectively prevents field of view distortion. In addition, the horizontally scanned polygon mirror only needs a rotation speed of a few Hz to tens of Hz, which is very suitable as the slow axis of scanning and realizes a large field of view, while the vertical scanning resonant mirror can be realized when the aperture or swing is small. Very high scanning frequency, suitable as the fast axis of scanning.

Finally, it should be noted that the above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, it is still for those skilled in the art. The technical solutions described in the foregoing embodiments may be modified, or some of the technical features may be equivalently replaced. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

A transmitting unit that can be used for lidar, including:

Laser array, each laser can be individually driven to emit a laser beam;

A one-dimensional galvanometer, the one-dimensional galvanometer is arranged downstream of the optical path of the laser, has a first reflecting surface and a first rotation axis along a first direction, the one-dimensional galvanometer can rotate around the first rotation axis , And reflect the laser beam incident on it;

A polygon mirror, the polygon mirror is arranged downstream of the optical path of the one-dimensional galvanometer, and has a plurality of second reflection surfaces and a second rotation axis along a second direction, wherein the first direction is perpendicular to the second Direction, the polygon mirror can rotate around the second rotation axis, and the second reflection surface can reflect the laser beam incident on it to the outside of the lidar for detecting a target.
The laser radar transmitting unit according to claim 1, further comprising a fast axis compression lens and a converging lens, which are sequentially arranged between the laser and the one-dimensional galvanometer, wherein the fast axis compression lens is configured to receive And compress the divergence angle of the laser beam emitted by the laser along the fast axis direction, the converging lens is configured to converge the compressed laser beam, and the one-dimensional galvanometer is set at the focus of the converging lens Location.
The laser radar transmitting unit according to claim 1, further comprising a fast axis compression lens located between the laser and the one-dimensional galvanometer and between the one-dimensional galvanometer and the polygon mirror The converging lens, wherein the fast axis compression lens is configured to receive and compress the divergence angle of the laser beam emitted by the laser along the fast axis direction, and the converging lens is configured to reflect the one-dimensional galvanometer The laser beam is converged on the polygon mirror.
The laser radar transmitting unit according to any one of claims 1 to 3, wherein the one-dimensional galvanometer mirror comprises a galvanometer mechanical resonator mirror or a MEMS galvanometer mirror.
The laser radar transmitting unit according to claim 1 or 2, wherein the one-dimensional galvanometer works at its resonant frequency, and the ratio of the resonant frequency to the rotation frequency of the polygon mirror is an integer greater than 1.
The laser radar transmitting unit according to claim 1 or 2, further comprising a laser driving circuit configured to obtain the current real-time vertical angle through position feedback of the one-dimensional galvanometer and the polygon mirror respectively And the horizontal angle to determine whether to trigger the laser to emit light.
A receiving unit that can be used for lidar, including a detector array, a one-dimensional galvanometer and a polygon mirror,

The detector array includes a plurality of detectors, and each detector can receive the echo of the lidar and convert it into an electric signal;

A polygon mirror, the polygon mirror is provided with a plurality of second reflection surfaces and a second rotation axis along a second direction, the polygon rotation mirror can rotate around the second rotation axis, and the second reflection surface can rotate The echo incident thereon is reflected on the one-dimensional galvanometer;

The one-dimensional galvanometer is arranged on the optical path between the detector array and the polygon mirror, and has a first reflecting surface and a first rotation axis along a first direction. The one-dimensional galvanometer can surround the The first rotating shaft rotates and reflects the echo incident thereon to the detector array, wherein the first direction is perpendicular to the second direction.
The receiving unit of the lidar according to claim 7, further comprising a converging lens, the converging lens is arranged between the detector array and the one-dimensional galvanometer or the one-dimensional galvanometer and the polygon mirror between.
The laser radar receiving unit according to claim 7 or 8, wherein the one-dimensional galvanometer includes a galvanometer mechanical resonator mirror or a MEMS galvanometer.
The laser radar receiving unit according to claim 7 or 8, wherein the one-dimensional galvanometer works at its resonance frequency, and the ratio of the resonance frequency to the rotation frequency of the polygon mirror is an integer greater than 1.
A type of lidar, including:

The launching unit according to any one of claims 1-6, configured to emit a detection laser beam for detecting a target;

The receiving unit according to any one of claims 7-10, configured to receive echoes and convert them into electrical signals; and

The point cloud generating unit is coupled to the transmitting unit and the receiving unit, and is configured to calculate the distance of the target object according to the flight time of the detection laser beam, and generate a point cloud.
A type of lidar, including:

Laser array, each laser can be individually driven to emit a laser beam;

The detector array includes multiple detectors, each of which can receive the echo of the lidar and convert it into an electrical signal;

A one-dimensional galvanometer, the one-dimensional galvanometer is arranged downstream of the optical path of the laser, has a first reflecting surface and a first rotation axis along a first direction, the one-dimensional galvanometer can rotate around the first rotation axis , And reflect the laser beam incident on it;

A beam splitter is arranged between the laser and the one-dimensional galvanometer to allow a part of the laser beam emitted by the laser to pass and be incident on the one-dimensional galvanometer;

A polygon mirror, the polygon mirror is arranged downstream of the optical path of the one-dimensional galvanometer, and has a plurality of second reflection surfaces and a second rotation axis along a second direction, wherein the first direction is perpendicular to the second Direction, the polygon mirror can rotate around the second rotation axis, the second reflective surface can reflect the laser beam incident on it to the outside of the lidar for detecting the target; the second reflective surface and The echo can be reflected on the one-dimensional galvanometer, and after being reflected by the one-dimensional galvanometer, it passes through the beam splitter and is incident on the detector array.
The lidar according to claim 12, further comprising a fast axis compression lens and a converging lens, wherein the fast axis compression lens is disposed between the laser and the beam splitter, and is configured to receive and compress the laser The divergence angle of the emitted laser beam along the fast axis direction. The condensing lens is arranged between the one-dimensional galvanometer and the polygon mirror, and is configured to converge the compressed laser beam. The echoes reflected by the polygon mirror converge on the one-dimensional galvanometer, wherein the one-dimensional galvanometer is arranged at the focal position of the converging lens.
The lidar according to claim 12, further comprising a fast axis compression lens between the laser and the beam splitter and a converging lens between the beam splitter and the one-dimensional galvanometer, wherein the The fast axis compression lens is configured to receive and compress the divergence angle of the laser beam emitted by the laser along the fast axis direction.
A method for detecting using the lidar of any one of claims 12-14.