WO2021218362A1 - Système radar à laser coaxial basé sur un galvanomètre unidimensionnel et un miroir rotatif polyédrique - Google Patents

Système radar à laser coaxial basé sur un galvanomètre unidimensionnel et un miroir rotatif polyédrique Download PDF

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Publication number
WO2021218362A1
WO2021218362A1 PCT/CN2021/078772 CN2021078772W WO2021218362A1 WO 2021218362 A1 WO2021218362 A1 WO 2021218362A1 CN 2021078772 W CN2021078772 W CN 2021078772W WO 2021218362 A1 WO2021218362 A1 WO 2021218362A1
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WIPO (PCT)
Prior art keywords
laser
dimensional galvanometer
polygon mirror
galvanometer
lidar
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PCT/CN2021/078772
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English (en)
Chinese (zh)
Inventor
毛胜平
向少卿
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上海禾赛科技股份有限公司
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Publication of WO2021218362A1 publication Critical patent/WO2021218362A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G01S7/4811—Constructional features, e.g. arrangements of optical elements common to transmitter and receiver
    • G01S7/4812—Constructional features, e.g. arrangements of optical elements common to transmitter and receiver transmitted and received beams following a coaxial path
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G01S7/4817—Constructional features, e.g. arrangements of optical elements relating to scanning

Definitions

  • 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.
  • 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.
  • Lidar 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 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:
  • 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 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 .
  • 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 ,
  • 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 laser beam reflected by the one-dimensional galvanometer To the multi-sided rotating mirror.
  • the one-dimensional galvanometer includes a galvanometer mechanical resonator mirror or a MEMS galvanometer mirror.
  • 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.
  • 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.
  • 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 one-dimensional galvanometer includes a galvanometer mechanical resonator mirror or a MEMS galvanometer mirror.
  • 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.
  • 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;
  • 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:
  • 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 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • an intermediate medium which can be the internal communication of two components or the interaction of two components relation.
  • 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.
  • 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 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.
  • the first rotating shaft 122 is in a direction perpendicular to the surface of the paper.
  • 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.
  • 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.
  • the rotating mirror is a regular polygon rotating mirror.
  • 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 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.
  • the one-dimensional galvanometer 12 may be a galvanometer mechanical resonator mirror or a MEMS galvanometer mirror.
  • the one-dimensional galvanometer 12 can provide a scanning field of view in the vertical direction of the lidar
  • the polygon mirror 13 can provide a scanning field of view in the horizontal direction of the lidar.
  • 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.
  • the one-dimensional galvanometer 12 is behind the condensing lens 15 (the transmitting unit 10 shown in FIG.
  • 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.
  • 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.
  • FIG. 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.
  • 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.
  • 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.
  • a plurality of vibrating mirrors 12 are arranged between the laser 11 and the converging lens 15, as shown in FIG. 4.
  • 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.
  • 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.
  • 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.
  • 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:
  • 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.
  • step S102 in the slow axis direction, the rotation speed of the polygon mirror 13 is adjusted to set it to fr/N.
  • 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.
  • step S104 the laser is triggered to emit light.
  • each laser pulse should be perpendicularly incident on the galvanometer and polygon mirror at the initial moment of emission.
  • 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 [ ⁇ 1, ⁇ 2], you can start the laser to emit light when the angle is rotated to ⁇ 1, and stop emitting light when the angle is rotated to ⁇ 2.
  • 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).
  • 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).
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • the scanning frequency of the reciprocating swing of the one-dimensional galvanometer 12 should match the radar frame frequency.
  • the radar frame frequency is 10 Hz.
  • 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.
  • 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.
  • 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
  • the one-dimensional galvanometer 12 is set at the focal position of the converging lens 15.
  • 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.
  • 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).
  • a one-dimensional galvanometer mainly responsible for scanning in the vertical direction
  • a multi-sided rotating mirror mainly responsible for scanning in the horizontal direction
  • 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.
  • 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.
  • 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.
  • FIG. 10C a schematic diagram of the point cloud results of multi-laser scanning according to the present invention.
  • 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.
  • 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.
  • 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.
  • multiple lasers emit light in the vertical direction at the same time.
  • surface 1, surface 2, surface 3, and surface 4 correspond to the first surface, second surface, and third surface of the polygon mirror, respectively.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Electromagnetism (AREA)
  • Optical Radar Systems And Details Thereof (AREA)

Abstract

L'invention concerne une unité d'émission et une unité de réception d'un radar laser basées sur un galvanomètre unidimensionnel et un miroir rotatif polyédrique, ainsi qu'un radar laser coaxial, pouvant empêcher efficacement la distorsion de champ en sélectionnant la fréquence d'oscillation du galvanomètre unidimensionnel et la fréquence de rotation du miroir rotatif polyédrique. L'unité de transmission (10) applicable au radar laser comprend : un réseau de lasers (11) commandés indépendamment pour émettre un faisceau lumineux ; un galvanomètre unidimensionnel (12) situé en aval d'un trajet lumineux du laser (11), doté d'une première surface réfléchissante (121) et d'un premier arbre rotatif (122) le long d'une première direction, tournant autour du premier arbre rotatif (122), et réfléchissant le faisceau laser incident sur celui-ci ; et un miroir rotatif polyédrique (13) situé en aval d'un trajet lumineux du galvanomètre unidimensionnel (12), et doté d'une pluralité de secondes surfaces réfléchissantes (131) et d'un second arbre rotatif (132) le long d'une seconde direction. La première direction est perpendiculaire à la seconde direction. Le miroir rotatif polyédrique peut tourner autour du second arbre rotatif (132). Les secondes surfaces réfléchissantes (131) peuvent réfléchir des faisceaux lumineux incidents à l'extérieur du radar laser pour détecter un objet cible.
PCT/CN2021/078772 2020-04-26 2021-03-02 Système radar à laser coaxial basé sur un galvanomètre unidimensionnel et un miroir rotatif polyédrique WO2021218362A1 (fr)

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CN117890930A (zh) * 2024-03-14 2024-04-16 深圳阜时科技有限公司 一种转镜激光雷达、转动角度检测方法及电子设备

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CN115166693A (zh) * 2022-08-02 2022-10-11 天津帆探科技有限公司 一种混合固态式激光雷达及激光雷达扫描方法
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CN114858097A (zh) * 2022-05-27 2022-08-05 森思泰克河北科技有限公司 激光雷达转镜夹角测量方法及测量装置
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CN115685147A (zh) * 2022-12-14 2023-02-03 深圳市速腾聚创科技有限公司 调频连续波激光雷达及自动驾驶设备
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CN117890930A (zh) * 2024-03-14 2024-04-16 深圳阜时科技有限公司 一种转镜激光雷达、转动角度检测方法及电子设备

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