WO2022120904A1 - 一种激光雷达及其扫描方法 - Google Patents

一种激光雷达及其扫描方法 Download PDF

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Publication number
WO2022120904A1
WO2022120904A1 PCT/CN2020/136627 CN2020136627W WO2022120904A1 WO 2022120904 A1 WO2022120904 A1 WO 2022120904A1 CN 2020136627 W CN2020136627 W CN 2020136627W WO 2022120904 A1 WO2022120904 A1 WO 2022120904A1
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WO
WIPO (PCT)
Prior art keywords
wedge
module
mirror
optical fiber
shaped mirror
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PCT/CN2020/136627
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English (en)
French (fr)
Inventor
疏达
杨野
吴江
李�远
Original Assignee
北醒（北京）光子科技有限公司
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Publication of WO2022120904A1 publication Critical patent/WO2022120904A1/zh

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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
    • 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
    • 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
    • G01S7/497—Means for monitoring or calibrating

Definitions

  • the present application relates to the technical field of measurement, and in particular, to a laser radar and a scanning method thereof.
  • Frequency Modulation Continuous Wave Lidar is essentially heterodyne interferometry.
  • the principle is to linearly modulate the laser frequency and divide the laser into two parts, one for the local oscillator light, one for the signal light, and the other for the signal light. It is collimated and reflected by the target into the receiving system. It interferes with the local oscillator light to generate a beat frequency signal.
  • the signal carries the frequency tuning amount generated by the time of flight and the Doppler frequency shift generated by the relative motion.
  • the beat frequency is measured to settle the settlement. Distance and speed information.
  • the scanning system of FMCW is mainly based on reflection methods such as galvanometers and prisms for scanning.
  • this scanning method is used for medium and long-distance measurement, it is easy to cause the problem that the coupling between the echo signal and the receiving device caused by the time-of-flight is reduced, thereby affecting the imaging quality.
  • the embodiments of the present application provide a laser radar and a scanning method thereof, so as to improve the problem of reduced coupling between an echo signal and a receiving device caused by time of flight.
  • an embodiment of the present application provides a laser radar, including: a transmitting and receiving module, a collimating module and a scanning module, wherein the transmitting and receiving module is arranged in the collimating module
  • the scanning module is arranged at the front end of the collimating module; wherein, the transmitting and receiving module includes an optical waveguide with at least one channel; the scanning module includes a first wedge-shaped mirror mold group and the second wedge-shaped mirror module, the first wedge-shaped mirror module and the second wedge-shaped mirror module are arranged at intervals along the optical axis direction of the collimating module, the first wedge-shaped mirror module and the The wedge mirrors in the second wedge mirror module can rotate around the optical axis of the collimation module respectively.
  • the light emitted by a channel in the optical waveguide is collimated by the collimation module, and passes through the first wedge-shaped mirror module and the second wedge-shaped mirror module After group scanning, the echo reflected by the target passes through the first wedge-shaped mirror module and the second wedge-shaped mirror module, and is coupled into the channel by the collimation module.
  • the optical waveguide is an optical fiber or an optical fiber bundle, and the light-emitting end faces of the optical fiber bundle are arranged in an array.
  • the first wedge-shaped mirror module includes: a first rotation mechanism and a first wedge-shaped mirror mounted on the first rotation mechanism;
  • the second wedge-shaped mirror module includes: A second rotation mechanism and a second wedge mirror mounted on the second rotation mechanism.
  • the first rotation mechanism includes a first drive motor, a first gear transmission mechanism, and a first wedge mirror mounting barrel; the input end of the first gear transmission mechanism is connected to the first The output shaft of the driving motor is connected, and the output end is connected with the first wedge-shaped mirror mounting barrel; the first wedge-shaped mirror is mounted in the first wedge-shaped mirror mounting barrel; the second rotating mechanism includes a second driving motor, a second gear transmission mechanism and a second wedge-shaped mirror mounting barrel; the input end of the second gear transmission mechanism is connected with the output shaft of the second drive motor, and the output end is connected with the second wedge-shaped mirror mounting barrel; the The second wedge-shaped mirror is mounted in the second wedge-shaped mirror mounting barrel; or,
  • the first rotation mechanism includes a first drive motor, a first drive gear, and a first ring gear, the first drive gear is connected to the output shaft of the first drive motor, and the first ring gear is connected to the first ring gear.
  • a driving gear meshes with each other, the first wedge mirror is installed in the first ring gear;
  • the second group of rotating mechanisms includes a second driving motor, a second driving gear and a second ring gear, the second driving The gear is connected with the output shaft of the second driving motor, the second ring gear is engaged with the second driving gear, and the second wedge mirror is installed in the second ring gear.
  • the first gear transmission mechanism includes a first drive gear and a first ring gear; the first ring gear is sleeved on the outer circumference of the first wedge-shaped mirror mounting barrel and is connected with the The first wedge-shaped mirror mounting barrel is fixedly connected, the first drive gear is fixedly connected with the output shaft of the first drive motor, and meshes with the teeth on the outer circumference of the first gear ring; the second gear transmission mechanism includes A second driving gear and a second ring gear; the second ring gear is sleeved on the outer periphery of the second wedge-shaped mirror mounting barrel and is fixedly connected with the second wedge-shaped mirror mounting barrel, and the second driving gear is connected to the second wedge-shaped mirror mounting barrel.
  • the output shaft of the second driving motor is fixedly connected and meshes with the teeth on the outer circumference of the second ring gear.
  • the scanning module further includes a scanning lens barrel, a first bearing and a second bearing; the first bearing and the second bearing are arranged in the scanning lens barrel, so The outer ring of the first bearing and the outer ring of the second bearing are relatively fixed with the scanning lens barrel; the first wedge-shaped mirror mounting barrel is sleeved in the inner ring of the first bearing and is connected to the scanning lens barrel. The inner ring of a bearing is fixed; the second wedge-shaped mirror mounting barrel is sleeved in the inner ring of the second bearing and fixed with the inner ring of the second bearing.
  • the first end of the optical fiber or the optical fiber bundle is provided in the optical fiber box, and the end face of the first end of the optical fiber or the optical fiber bundle is located at the end of the optical fiber box.
  • the laser radar further includes a focus adjustment module; wherein, the focus adjustment module includes: a focus adjustment nut, and the front end of the focus adjustment nut is sleeved on the The rear end of the collimating module is screwed with the rear end of the collimating module, and the rear end of the focusing nut is arranged adjacent to the transmitting and receiving module.
  • the focus adjustment module includes: a focus adjustment nut, and the front end of the focus adjustment nut is sleeved on the The rear end of the collimating module is screwed with the rear end of the collimating module, and the rear end of the focusing nut is arranged adjacent to the transmitting and receiving module.
  • the focusing nut is a cylindrical structure with a threaded connection at one end, and a channel corresponding to the channel of the optical waveguide is provided at the center of the bottom of the cylindrical structure. an optical port; the focusing nut is threadedly connected to the rear end of the collimating module through the threaded connection port;
  • An elastic compensating member is arranged inside the cylindrical structure, and the elastic compensating member is pressed between the rear end of the collimating module and the bottom of the cylindrical structure.
  • the optical waveguide is an optical fiber or an optical fiber bundle
  • the first end of the optical fiber or the optical fiber bundle is set in the optical fiber box, and the end face of the first end of the optical fiber or the optical fiber bundle is located in the The end of the optical fiber box
  • the optical fiber box is provided with an optical fiber box fixing member
  • the front end of the optical fiber box fixing member is provided with a connecting plate, and on the connecting plate, are respectively provided on the first circumference and the second circumference.
  • first circumference and the second circumference are respectively provided with more than two threaded holes; at least one threaded hole on the first circumference corresponds to a track groove on the first circumference on the connecting plate, and on the second circumference At least one threaded hole corresponds to a track groove on the second circumference of the connecting plate.
  • the laser radar further includes an optical axis adjustment module, and the optical axis adjustment module is connected with the transmitting and receiving module; wherein, the optical axis adjustment module
  • the group includes an up-down position adjustment module and a horizontal position adjustment module, so as to adjust the position of the optical waveguide with two degrees of freedom in the up-down direction and in the horizontal direction.
  • the collimating module includes a collimating lens barrel, a lens is provided at the front end of the collimating lens barrel, and a diaphragm opening is provided at the rear end of the collimating lens barrel; wherein, the The light-transmitting surface of the lens on the side close to the transmitting and receiving module is a plane, and the light-transmitting surface on the side away from the transmitting and receiving module is a convex surface.
  • an embodiment of the present application provides a laser radar scanning method, including: emitting laser light from at least one channel of an optical waveguide; collimating the laser light emitted from at least one channel of the optical waveguide; and the collimated laser light, After being scanned by two or more wedge mirrors with different rotational speeds in sequence, it is emitted.
  • the emitting the laser light from the optical waveguide includes: emitting the laser light from the optical waveguide in an array manner.
  • the shooting of the laser light from the optical waveguide in an array manner includes: shooting the laser light in an array manner from an array of fiber end faces of a fiber bundle composed of multiple fibers.
  • the two or more wedge-shaped mirrors with different rotational speeds are scanned, including a first wedge-shaped mirror and a second wedge-shaped mirror; wherein, the collimated laser passes through two or more wedge-shaped mirrors in sequence.
  • Wedge-shaped mirrors with different rotational speeds are scanned and emitted, including: the collimated laser is scanned by the first wedge-shaped mirror, and then scanned by the second wedge-shaped mirror and emitted; the first wedge-shaped mirror and the second wedge-shaped mirror have different Rotating speed.
  • the rotational speed of the first wedge mirror is 0.5 times to 3 times the rotational speed of the second wedge mirror.
  • the laser radar scanning method further includes: after collimating the laser light emitted from a channel of the optical waveguide, scanning through the two or more wedge mirrors with different rotational speeds in sequence After being emitted, the reflected light reflected by the target passes through the two or more wedge mirrors in sequence, and then converges to the channel and is received by the channel.
  • the first wedge-shaped mirror module and the second wedge-shaped mirror module cooperate to scan the outgoing light of the optical waveguide, so as to obtain a scanning trajectory symmetrical around the center of the optical axis.
  • the scanning speed is the smallest at the edge of the field of view, and the maximum scanning speed is only in the central field of view, so the average speed of the entire scanning process is relatively small, and the image shift is relatively small during most of the scanning time, thereby improving the overall time of flight.
  • the resulting problem is that the coupling between the echo signal and the optical waveguide is reduced.
  • 1a and 1b are schematic diagrams of receiving echo signals in a non-scanning state and a scanning state, respectively, based on reflection methods such as a galvanometer and a prism.
  • Figure 2a is a schematic diagram of the light path transmission of a single wedge mirror.
  • Figure 2b is a schematic diagram of the scanning trajectory of a single wedge mirror.
  • Figure 2c Schematic diagram of the scanning principle of the double wedge mirror.
  • Fig. 2d Schematic diagram of the scanning trajectory of the double wedge mirror.
  • FIG. 3 is a front view of a lidar structure according to an embodiment of the present application.
  • FIG. 4 is a top view of the embodiment shown in FIG. 3 .
  • FIG. 5 is a cross-sectional view of the embodiment shown in FIG. 3 .
  • FIG. 6 is a schematic diagram of transmitting and receiving optical paths of an optical fiber end face array according to an embodiment of the present application.
  • FIG. 7a to 7d are schematic structural diagrams of an optical fiber box according to an embodiment of the present application.
  • FIG. 8 is a schematic structural diagram of the collimation module in FIG. 1 .
  • FIG. 9 is a schematic structural diagram of the scanning module in FIG. 1 .
  • FIG. 10a is a schematic structural diagram of the fixing member of the optical fiber box in FIG. 5 .
  • FIG. 10b is a schematic end view of the rear end of the focusing nut in FIG. 5 .
  • Figure 10c is a schematic diagram of the structure of the fitting structure between the fixing member of the optical fiber box and the rear end face of the focusing nut.
  • FIG. 11 is a flowchart of a laser radar scanning method according to an embodiment of the present application.
  • 12a to 12d are scanning patterns when the slow wedge mirror rotates 1, 2, 5 and 13 revolutions when scanning through two wedge mirrors according to an embodiment of the present application.
  • FIG. 13a is a schematic diagram of a fiber end face array with a 4*4 distribution in an embodiment of the present application.
  • Fig. 13b is a schematic diagram of scanning through two wedge mirrors after collimated laser light emitted by the fiber end face array shown in Fig. 13a.
  • FIG. 14a is a schematic diagram of a frame of scanned point cloud trajectories obtained by scanning with two wedge mirrors in an embodiment of the present application.
  • FIG. 14b is a schematic diagram of scanning point cloud trajectories after ten frames are superimposed in an embodiment of the present application.
  • FMCW is a scanning system based on optical waveguides, which can scan based on reflection methods such as galvanometers and prisms.
  • this kind of scanning based on reflection methods such as galvanometers and prisms may not be suitable for medium and long distance measurements.
  • the scanning range is usually large in medium and long distance measurement, in order to ensure the refresh rate of the point cloud, the fast axis needs to scan at an extremely fast scanning speed, and the light used for measurement has a long flight time, which is easy to
  • the echo signal deviates from the receiving surface of the optical waveguide, causing the offset of the imaging point, so that the receiving surface of the optical waveguide cannot receive the echo signal, or causes the echo signal to decay rapidly, which affects the measurement accuracy.
  • FIG. 1a and 1b are schematic diagrams of receiving echo signals in a non-scanning state and a scanning state, respectively, based on reflection methods such as a galvanometer and a prism.
  • Fig. 1a when not scanning, the emitted light and the received light are coaxial (ie, the receiving and transmitting light is coaxial), the signal light returns to the original path, and the imaging point is on the receiving optical axis at this time.
  • Figure 1b during scanning, the receiving optical axis (shown by the solid line) rotates during the flight time. At this time, the measured object moves relative to the receiving optical axis, which is equivalent to the imaging point on the receiving surface. move the imaging point away from the optical axis. When the off-axis height of the imaging point away from the optical axis is greater than the size boundary of the receiving surface, the receiving surface cannot receive echo information.
  • the embodiments of the present application provide a laser radar with a wedge mirror scanning structure and a scanning method thereof.
  • FIG. 2a is a schematic diagram of a circular scanning trajectory formed when a wedge mirror rotates.
  • FIG. 3 is a front view of a lidar structure according to an embodiment of the present application
  • FIG. 4 is a top view of the embodiment shown in FIG. 3
  • FIG. 5 is a cross-sectional view of the embodiment shown in FIG. 3 . 3 to 5
  • the lidar 10 in this embodiment includes: a transmitting and receiving module 20, a collimating module 30 and a scanning module 40, and the transmitting and receiving module 20 is arranged at the rear end of the collimating module 30,
  • the scanning module 40 is arranged at the front end of the collimating module 30; wherein, the transmitting and receiving module 20 includes an optical waveguide with at least one channel; the scanning module 40 includes a first wedge-shaped mirror module 401 and a second wedge-shaped mirror module 402, the first wedge-shaped mirror module 401 and the second wedge-shaped mirror module 402 are arranged at intervals along the optical axis direction of the collimating module 30, and the wedge-shaped mirrors in the first wedge-shaped mirror module 401 and the second wedge-shaped mirror module 40
  • the first wedge-shaped mirror module 401 and the second wedge-shaped mirror module 402 can respectively drive the respective wedge-shaped mirrors to rotate, so as to scan the outgoing light emitted by the optical waveguide.
  • One of the first wedge-shaped mirror module 401 and the second wedge-shaped mirror module 402 may be the fast-axis scanning module 40 (wherein the wedge-shaped mirror may be referred to as a fast wedge-shaped mirror), and the other may be the slow-axis scanning module 40 (wherein the wedge-shaped mirror may be referred to as a fast wedge-shaped mirror).
  • Wedge mirrors may be referred to as fast wedge mirrors).
  • the first wedge-shaped mirror module 401 and the second wedge-shaped mirror module 402 cooperate to scan the outgoing light of the optical waveguide, so as to obtain a scanning trajectory symmetrical around the center of the optical axis.
  • the scanning speed is the smallest at the edge of the field of view, and the maximum scanning speed is only in the central field of view, so the average speed of the entire scanning process is relatively small, and the image shift is relatively small during most of the scanning time, thereby improving the overall time of flight.
  • the resulting problem is that the coupling between the echo signal and the optical waveguide is reduced.
  • wedge mirror scanning eliminates the need to allocate the number of scanning lines in the horizontal and vertical directions in the scanning space, and the scanning trajectory is rotated without periodic dislocation, and under multiple frames (that is, the scanned images obtained with the passage of scanning time) High point density and complete coverage of the entire scanning area can be achieved.
  • the transmitting and receiving module 20 , the collimating module 30 and the scanning module 40 can be jointly disposed on a substrate 50 .
  • the transmitting and receiving module 20 which may also be called a transmitting and receiving device, is used to transmit laser light and receive echoes (also called echo signals or return light) reflected by the target.
  • the laser emitted by the transmitting and receiving module 20 may be a continuous laser or a pulsed laser.
  • An optical waveguide is a medium device that guides light waves to propagate in it, also known as a medium optical waveguide.
  • the number of channels (also referred to as optical channels) of the optical waveguide may be one.
  • the light emitted by one channel is collimated by the collimation module 30, and after being scanned by the first wedge mirror module 401 and the second wedge mirror module 402, the echo reflected by the target passes through the first wedge mirror module.
  • the collimation module 30 is coupled into the channel, that is, received by the channel, which can realize coaxial light emission and reception, which is beneficial to improve the measurement accuracy of echo reception.
  • the optical waveguide may have multiple channels.
  • the light emitted by each channel is collimated by the collimation module 30, and after being scanned by the first wedge mirror module 401 and the second wedge mirror module 402, the echo reflected by the target passes through the first wedge mirror module.
  • the group 401 and the second wedge-shaped mirror module 402 are coupled into the corresponding channel by the collimation module 30, that is, received by the corresponding channel.
  • the light emitted by a channel, after the echo reflected by the target is received by the same channel that emits the light, so that the light emission and reception can be coaxial, which is beneficial to improve the measurement accuracy of echo reception.
  • the first channel can not only transmit light, but also receive the echo of the light emitted by it, and the first channel can realize the coaxial transmission and reception of light.
  • the second channel and other channels can realize the coaxial transmission and reception of light, that is, the optical transmission and reception paths are reversible.
  • the light-emitting end faces of the multiple channels of the optical waveguide may be arranged in an array arrangement.
  • the array arrangement can be a matrix array, a circular array, or a line array.
  • the spacing between the centers of adjacent channels can be 150um to 300um.
  • Optical waveguides can take a variety of structural forms.
  • the optical waveguide takes the form of an optical fiber.
  • a fiber bundle structure can be used, that is, a structure in which multiple fibers are combined side by side.
  • the optical waveguide is mainly illustrated by taking the optical fiber bundle 201 as an example.
  • the light-emitting end faces of the optical fibers are arranged in an array. Therefore, the light-emitting end faces of the optical fiber bundle 201 may also be referred to as an array of optical fiber end faces.
  • the number of fibers in fiber bundle 201 may be 2-18.
  • the optical fiber bundle 201 is composed of 12 optical fibers, and the light-emitting end faces of the 12 optical fibers are arranged in a matrix array.
  • the optical fiber bundle 201 is composed of 18 optical fibers, and the light-emitting end faces of the 18 optical fibers are arranged in a circular array.
  • Each of the fibers can be a single-mode fiber, the full angle of divergence can be 9° to 12°, and the divergence angle can be obtained by numerical aperture.
  • FIG. 6 is a schematic diagram of transmitting and receiving optical paths of an optical fiber end face array according to an embodiment of the present application.
  • the light emitted by an optical fiber end face in the optical fiber end face array is collimated by the collimation module 30, and after scanning by the first wedge mirror module 401 and the second wedge mirror module 402, it passes through the target reflected back.
  • the wave after passing through the first wedge mirror module 401 and the second wedge mirror module 402, is coupled into the fiber end face by the collimation module 30, that is, received by the fiber end face. That is to say, the light emitted by the same fiber end face, through the echo reflected by the target, is received by the same fiber end face, so that the light emission and reception can be coaxial.
  • FIG. 7a to 7d are schematic structural diagrams of an optical fiber box according to an embodiment of the present application.
  • 7a is a front view of an optical fiber box in an embodiment of the application
  • FIG. 7b is a partially enlarged schematic view of the position A (fiber end face array) in FIG. 7a
  • FIG. 7c is a bottom view of the optical fiber box shown in FIG. 7a
  • FIG. 7d It is a perspective view of the optical fiber box shown in FIG. 7a. 1 and 7a to 7d, in order to facilitate the arrangement of the optical fiber bundle 201, one end of the optical fiber bundle 201 can be arranged in the optical fiber box 202, and the optical fiber end face array 203 is located at the front end of the optical fiber box 202, which is convenient for light output and echo reception.
  • the other end of the optical fiber bundle 201 is drawn out from the rear end of the optical fiber box 202 and can be fixed on the substrate 50 by the optical fiber fixing member.
  • the collimating module 30 is used for collimating the laser beams emitted by the transmitting and receiving modules 20 to form parallel beams.
  • FIG. 8 is a schematic structural diagram of the collimation module in FIG. 1 .
  • the collimation module 30 may include a collimating lens barrel 301 , and a lens 302 is provided at the front end of the collimating lens barrel 301 .
  • the front end of the collimating lens barrel 301 refers to the end of the two ends of the collimating lens barrel 301 that is far away from the transmitting and receiving module 20 .
  • the light-transmitting surface of the lens 302 on the side close to the transmitting and receiving module 20 is a plane, and the light-transmitting surface on the side far from the transmitting and receiving module 20 is a convex surface.
  • the diameter of the lens 302 may be 3-100 mm, and the focal length may be 3-500 mm.
  • the lidar 10 of this embodiment can be used to measure distance and/or speed at medium and long distances (0.1km-5km).
  • the lens 302 has a diameter of 60 mm and a focal length of 220 mm, which can be used for distance and/or velocity measurements over 5 km long distances.
  • the lens 302 can be fixed on the collimating lens barrel 301 by a glue and/or a pressure ring, so as to enhance the reliability of the connection with the collimating lens barrel 301 .
  • the lens 302 can not only collimate the laser light emitted by each fiber end face in the fiber end face array 203 to form a parallel beam, but also can converge the echoes, couple them into the corresponding fiber end face, and be received by the corresponding fiber end face.
  • the collimating barrel 301 may be a hollow elongated structure.
  • the inner wall of the collimating lens barrel 301 can be treated with threads or extinction, and the rear end of the collimating lens barrel 301 can be provided with a diaphragm opening to eliminate the stray light reflected back before the diaphragm, including the reflected light on the surface of the lens 302, There may be reflected light from the surface of the wedge mirror as the scanning element, as well as reflected light on other structural surfaces.
  • the scanning module 40 is used for scanning the light collimated by the lens 302 of the collimating module 30 to obtain a larger spatial measurement range.
  • the first wedge-shaped mirror module 401 and the second wedge-shaped mirror module 402 in the scanning module 40 are respectively installed with wedge-shaped mirrors.
  • the shape of the wedge-shaped mirror can be circular, and the cross-sectional shape is wedge-shaped.
  • the apex angle (also referred to as the wedge angle) of the wedge mirror can be 0.2°-30°, which can affect the diameter of the maximum scanning range.
  • the maximum theoretical full scan angle can be twice the sum of the deflection angles of the two wedges.
  • the vertex angles of the wedge mirrors installed on the first wedge mirror module 401 and the second wedge mirror module 402 may be the same or different.
  • the wedge mirrors in the first wedge mirror module 401 and the second wedge mirror module 402 can rotate at different rotational speeds.
  • the rotation directions of the wedge mirrors in the first wedge mirror module 401 and the second wedge mirror module 402 may be the same or different.
  • the apex angle of the wedge-shaped mirror is 0.5°
  • the rotation directions of the two wedge-shaped mirrors are opposite
  • the rotation ratio is 1:3.3.
  • the rotation speed ratio can effectively reduce the image shift of the optical fiber, that is, the end face of a single optical fiber can accurately receive the echo of the light emitted by it, so as to avoid the situation of not receiving the echo.
  • the scanning module 40 may also include a third wedge-shaped mirror module, a fourth wedge-shaped mirror module, and other multiple Wedge mirror module.
  • FIG. 9 is a schematic structural diagram of the scanning module in FIG. 1 .
  • the first wedge mirror module 401 and the second wedge mirror module 402 can be two sets of relatively independent mirror modules.
  • the first wedge-shaped mirror module 401 may include: a first rotating mechanism 4011 and a first wedge-shaped mirror 4012 mounted on the first rotating mechanism 4011;
  • the second wedge-shaped mirror module 402 may include: a second rotating mechanism 4021 and a first wedge-shaped mirror 4012 The second wedge-shaped mirror 4022 on the second rotating mechanism 4021.
  • the first wedge-shaped mirror 4012 is driven to rotate by the first rotating mechanism 4011
  • the second wedge-shaped mirror 4022 is driven to rotate by the second rotating mechanism 4021 .
  • the first rotation mechanism 4011 and the second rotation mechanism 4021 may include a timing belt transmission mechanism or a gear transmission mechanism. 4 and 9 , in one embodiment, the first rotation mechanism 4011 and the second rotation mechanism 4021 include a gear transmission mechanism.
  • the first rotation mechanism 4011 may include a first drive motor 40111 and a first gear transmission mechanism. 40112 and the first wedge-shaped mirror mounting barrel 40113; the input end of the first gear transmission mechanism 40112 is connected with the output shaft of the first drive motor 40111, and the output end is connected with the first wedge-shaped mirror mounting barrel 40113; the first wedge-shaped mirror 4012 is installed on the A wedge-shaped mirror is installed in the barrel 40113.
  • the second rotation mechanism 4021 may include a second drive motor 40211, a second gear transmission mechanism 40212 and a second wedge mirror mounting barrel 40213; the input end of the second gear transmission mechanism 40212 is connected to the output shaft of the second drive motor 40211, and the output end It is connected with the second wedge-shaped mirror installation barrel 40213; the second wedge-shaped mirror 4022 is installed in the second wedge-shaped mirror installation barrel 40213.
  • the first wedge-shaped mirror 4012 and the second wedge-shaped mirror 4022 can be respectively fixed in the corresponding wedge-shaped mirror installation barrel by wedge-shaped mirror press rings and glue dispensing.
  • One of the first driving motor 40111 and the second driving motor 40211 can be a fast-axis motor (relatively fast rotation speed), and the other can be a slow-axis motor (relatively slow rotation speed).
  • the scanning track and speed of the double wedge mirror (the first wedge mirror 4012 and the second wedge mirror 4022) can be controlled by controlling the rotational speed of the first drive motor 40111 and the second drive motor 40211, and the real-time bit is fed back by the motor encoder. posture, so as to achieve efficient and accurate aperiodic high-speed scanning of the double wedge mirror.
  • a semi-open-loop mode can also be used, which does not require high-frequency real-time control of the rotational speeds of the first drive motor 40111 and the second drive motor 40211, but scans the trajectory according to the real-time pose feedback from the encoder. Perform the calculation to obtain the actual scanning trajectory coordinates.
  • the first gear transmission mechanism 40112 may include a first drive gear 401121 and a first ring gear 401122; the first ring gear 401122 is sleeved on the outer periphery of the first wedge-shaped mirror mounting barrel 40113 and is connected with the first wedge-shaped mirror
  • the installation cylinder 40113 is fixedly connected, and the first driving gear 401121 is fixedly connected with the output shaft of the first driving motor 40111, and meshes with the teeth on the outer circumference of the first ring gear 401122.
  • the second gear transmission mechanism 40212 may include a second driving gear 402121 and a second ring gear 402122; the second ring gear 402122 is sleeved on the outer periphery of the second wedge-shaped mirror mounting barrel 40213 and is fixedly connected with the second wedge-shaped mirror mounting barrel 40213.
  • the two driving gears 402121 are fixedly connected with the output shaft of the second driving motor 40211, and mesh with the teeth on the outer circumference of the second ring gear 402122.
  • the outer peripheries of the first wedge-shaped mirror mounting barrel 40113 and the second wedge-shaped mirror mounting barrel 40213 may be respectively provided with clamping grooves for fixedly connecting with the corresponding ring gears.
  • the reduction ratios of the gear sets of the first gear transmission mechanism 40112 and the second gear transmission mechanism 40212 may be the same or different.
  • the gear reduction ratios of the first gear transmission mechanism 40112 and the second gear transmission mechanism 40212 are different, a wider range of control of the scanning trajectory and scanning speed of the wedge mirror can be achieved.
  • the fast shaft gear set may be 1-3 times the output speed of the slow shaft gear set.
  • Fast-axis wedge mirrors can be 1-10 times faster than slow-axis wedge mirrors.
  • first wedge mirror 4012 and the second wedge mirror 4022 are respectively installed in the corresponding wedge mirror installation barrels, and the wedge mirror installation barrel is driven to rotate by the ring gear connected with the wedge mirror installation barrel and the drive gear connected with the ring gear. , thereby driving the wedge mirror to rotate to realize the scanning function.
  • the wedge mirror can also be directly installed in the ring gear.
  • the first rotation mechanism 4011 includes a first driving motor 40111, a first driving gear 401121 and a first ring gear 401122 , the first drive gear 401121 is connected to the output shaft of the first drive motor 40111, the first ring gear 401122 meshes with the first drive gear 401121, the first wedge mirror 4012 is installed in the first ring gear 401122;
  • the second set of rotating mechanisms It includes a second drive motor 40211, a second drive gear 402121 and a second ring gear 402122.
  • the second drive gear 402121 is connected to the output shaft of the second drive motor 40211.
  • the second ring gear 402122 meshes with the second drive gear 402121.
  • Two wedge mirrors 4022 are installed in the second ring gear 402122.
  • first wedge-shaped mirror 4012 and the second wedge-shaped mirror 4022 are respectively installed in the corresponding wedge-shaped mirror mounting barrels, in order to provide stable support for the rotation of the wedge-shaped mirror mounting barrels, and to maintain the two wedge-shaped mirror mounting barrels Coaxially arranged, referring to FIG.
  • the scanning module 40 may further include a scanning lens barrel 403 , a first bearing 404 and a second bearing 405 ; the first bearing 404 and the second bearing 405 are provided on the scanning lens barrel In 403, the outer ring of the first bearing 404 and the outer ring of the second bearing 405 are relatively fixed with the scanning lens barrel 403; The inner ring of the second bearing 405 is sleeved and fixed with the inner ring of the second bearing 405 .
  • One side of the outer ring of the first bearing 404 and the second bearing 405 can respectively abut on the annular step in the scanning lens barrel 403, and the other side can be locked by a pressure ring.
  • the lidar 10 may further include a focus adjustment module 60 .
  • the focus adjustment module 60 may include: a focus adjustment nut 601 , and the front end of the focus adjustment nut 601 is sleeved on the rear end of the collimation module 30 and is threadedly connected with the rear end of the collimation module 30 , the rear end of the focusing nut 601 is disposed adjacent to the transmitting and receiving module 20 .
  • an elastic compensator 602 can be arranged between the focusing nut 601 and the collimation module 30 , and the thread gap can be eliminated by the elastic compensator 602 and the adjustment accuracy can be increased. .
  • the focusing nut 601 is a cylindrical structure with a threaded connection port at one end, and a light-passing port corresponding to the fiber end face array 203 is provided at the center of the bottom of the cylindrical structure, so that the The laser beam emitted from 203 enters the collimating lens barrel 301 after passing through the focusing nut 601; the focusing nut 601 is threadedly connected with the rear end of the collimating module 30 through a threaded connection port; an elastic compensation is provided inside the cylindrical structure
  • the elastic compensation member 602 is pressed between the rear end of the collimation module 30 and the bottom of the cylindrical structure.
  • the elastic compensating member 602 may be a spring, a metal dome or a rubber elastic member, or the like.
  • the focusing nut 601 and the transmitting and receiving module 20 may not be directly connected. together to achieve mutual positioning.
  • one end of the optical fiber bundle 201 is provided in the optical fiber box 202 , and the fiber end face array 203 is located at the end of the optical fiber box 202 .
  • Fig. 10a is a schematic structural diagram of the fiber box fixing member in Fig. 5
  • Fig. 10b is a schematic view of the end face of the rear end of the focusing nut in Fig. 5
  • Fig. 10c is a schematic diagram of the matching structure between the fiber box fixing member and the rear end face of the focusing nut.
  • the optical fiber box 202 is provided with a fiber box fixing member 204 , the front end of the fiber box fixing member 204 is provided with a connecting plate 2041 , and a differential track groove is opened on the connecting plate 2041 .
  • a plurality of threaded holes are provided on the end surface of the rear end of the focusing nut 601 .
  • the connecting plate 2041 there are two or more track grooves S1 and S2 arranged at intervals on the first circumference and the second circumference, respectively, wherein the two or more track grooves S2 on the second circumference are the same as the first circumference.
  • Two or more track grooves S1 on the circumference are staggered;
  • At least one threaded hole h1 on the first circumference and the first circumference on the connecting plate Corresponding to a track groove S1 on the circumference, at least one threaded hole h2 on the second circumference corresponds to a track groove S2 on the second circumference on the connecting plate.
  • the focus adjustment (also referred to as focal length adjustment) between the lenses 302 has continuity, and after the adjustment is completed, it is convenient to thread the screw in the threaded hole to connect the focus nut 601 and the fiber box fixing member 204 back and forth. Positioning relative to position.
  • the threaded holes on the end face of the rear end of the focusing nut 601 may include six threaded holes provided on the first circumference and six threaded holes set on the second circumference, and six threaded holes on the second circumference. , corresponding to the six threaded holes on the first circumference.
  • the fiber box fixing member 204 may be provided with a fiber box accommodating cavity 2042 , and the fiber box 202 may be arranged in the fiber box accommodating cavity 2042 .
  • the lidar 10 may further include an optical axis adjustment module 70, and the optical axis adjustment module 70 is connected with the transmitting and receiving module 20;
  • the optical axis adjustment module 70 includes an upper and lower position adjustment module and a horizontal position adjustment module, so as to perform the position of the optical fiber end face array 203 with two degrees of freedom in the vertical direction and the horizontal direction (also referred to as the X direction and the Y direction). adjust.
  • This embodiment is not limited to this, and in other embodiments, the optical axis adjustment module 70 can also adjust the orientation of the fiber end face array 203 such as upper left, lower left, upper right and upper right.
  • the upper and lower position adjustment modules and the horizontal position adjustment modules cooperate to realize the displacement adjustment in the two degrees of freedom directions with an implementation structure, which can be realized by using the existing related technologies, and will not be described in detail here.
  • the optical axis adjustment module 70 can be connected with the optical fiber box fixing member 204, by adjusting the displacement of the optical fiber box fixing member 204 in the up-down direction and the horizontal direction, so that the optical fiber box fixing member 204 is installed on the The central optical axis of the optical fiber end face array 203 on the optical fiber box 202 is aligned with the optical axis of the lens 302 in the collimating lens barrel 301 .
  • the optical fiber box fixing member 204 can be fixedly connected to the optical axis adjustment module 70 through a back plate 2042 .
  • the rear end of the optical fiber box fixing member 204 can also be provided with a connecting plate, and the connection plate and the back plate 2042 can also adopt the threaded hole and the differential rail between the connecting plate at the front end of the optical fiber box fixing member 204 and the focusing nut 601.
  • the connection structure matched with the groove.
  • the optical axis adjustment module 70 can be used in combination with the focus adjustment module 60 . After the focus adjustment is completed by the focus adjustment module 60, the focus adjustment nut 601 and the optical fiber box fixing member 204 are positioned relative to each other by threading a screw in the threaded hole, and then the optical axis adjustment module 70 is operated, The vertical and/or horizontal positions of the fiber end face array 203 are adjusted to achieve alignment of the central optical axis of the fiber end face array 203 with the optical axis of the lens 302 in the collimating lens barrel 301 .
  • the diameter of the screw through the threaded hole is smaller than the width of the track groove, so that even after the screw locates the front and rear relative positions between the focusing nut 601 and the optical fiber box fixing member 204, the optical fiber can be adjusted by the optical axis adjustment module 70.
  • the screw can still float in the vertical and horizontal directions in the track groove.
  • the screws can be tightened to lock the screws and the track grooves with each other, and further sealing and fixing can be performed.
  • FIG. 11 is a flowchart of a laser radar scanning method according to an embodiment of the present application.
  • the scanning method in this embodiment can be applied to laser measurement based on heterodyne interference.
  • the scanning method in this embodiment may include steps ( S100 - S104 ) :
  • S100 Emit the laser light from at least one channel of the optical waveguide.
  • An optical waveguide is a medium device that guides light waves to propagate in it, also known as a medium optical waveguide.
  • the number of channels (also referred to as optical channels) of the optical waveguide may be one or more.
  • the laser light emitted by the light source can be a continuous laser or a pulsed laser.
  • the laser After the laser is emitted from at least one channel of the optical waveguide, it can be collimated by a collimating lens, that is, the laser beam emitted from the at least one channel of the optical waveguide is collimated to form a parallel beam.
  • the optical waveguide may have multiple channels.
  • the light emitted by each channel can be collimated by the collimating lens.
  • the collimated laser is sequentially scanned by two or more wedge mirrors with different rotational speeds and then emitted.
  • the shape of the wedge-shaped mirror can be circular, and the cross-sectional shape is wedge-shaped.
  • the apex angle (also referred to as the wedge angle) of the wedge mirror can be 0.2°-30°, which can affect the diameter of the maximum scanning range.
  • the maximum theoretical full scan angle can be twice the sum of the deflection angles of the two wedges.
  • the vertex angles of the first wedge-shaped mirror and the second wedge-shaped mirror may be the same or different.
  • Two or more wedge mirrors can be rotated according to different rotational speeds to scan the collimated laser.
  • the two or more wedge mirrors may include a first wedge mirror and a second wedge mirror.
  • One of the first wedge mirror and the second wedge mirror can be a fast wedge mirror, and the other is a fast wedge mirror.
  • the rotational speed of the first wedge mirror is 0.5 times to 3 times the rotational speed of the second wedge mirror.
  • the rotation directions of the first wedge mirror and the second wedge mirror may be the same or different.
  • 12a to 12d are scanning patterns when the slow wedge mirror rotates 1, 2, 5 and 13 revolutions when scanning through two wedge mirrors according to an embodiment of the present application.
  • a scanning trajectory that is symmetrical around the center of the optical axis can be obtained.
  • the scanning speed is the smallest at the edge of the field of view, and the maximum scanning speed is only in the central field of view, so the average speed of the entire scanning process is relatively small, and the image shift is relatively small during most of the scanning time, thereby improving the overall time of flight.
  • the resulting problem is that the coupling between the echo signal and the optical waveguide is reduced.
  • wedge mirror scanning eliminates the need to allocate the number of scanning lines in the horizontal and vertical directions in the scanning space, and the scanning trajectory is rotated without periodic dislocation, and under multiple frames (that is, the scanned images obtained with the passage of scanning time) High point density and complete coverage of the entire scanning area can be achieved.
  • the laser light may be emitted in an array from the optical waveguide.
  • the array can be a matrix array, a circular array or a line array, etc.
  • the light-emitting end faces of the multiple channels of the optical waveguide may be arranged in an array arrangement.
  • the spacing between the centers of adjacent channels can be 150um to 300um.
  • the optical waveguide may be in the form of an optical fiber.
  • a fiber bundle structure can be used, that is, a structure in which multiple fibers are combined side by side.
  • the light-emitting end faces of the optical fibers are arranged in an array. Therefore, the light-emitting end faces of the optical fiber bundle can also be called an array of optical fiber end faces.
  • the sending out the laser light from the optical waveguide in an array manner may include: ejecting the laser light in an array manner from an array of fiber end faces of an optical fiber bundle composed of a plurality of optical fibers.
  • FIG. 13a is a schematic diagram of a 4*4 fiber end face array in an embodiment of the present application
  • FIG. 13b is a schematic diagram of the laser beam emitted by the fiber end face array shown in FIG. 13a being collimated and scanned by two wedge mirrors.
  • FIG. 14a is a schematic diagram of a scanned point cloud trajectory of one frame obtained by scanning two wedge mirrors in an embodiment of the application
  • FIG. 14b is a schematic diagram of a scanned point cloud trajectory of ten frames superimposed in an embodiment of the application. It can be seen from Fig. 14a and Fig. 14b that the two wedge-shaped mirrors perform rotational scanning according to their respective rotational speeds, so that circular area scanning with high dot density can be achieved.
  • the laser radar scanning method may further include the step of: after collimating the laser light emitted from a channel of the optical waveguide, scanning the laser light through the two or more wedge mirrors with different rotational speeds in sequence, and then outputting the laser light. , the reflected light reflected by the target passes through the two or more wedge-shaped mirrors in sequence, then converges to the channel and is received by the channel.
  • the laser light emitted from a channel of the optical waveguide after being reflected by the target, passes through the two or more wedge mirrors in sequence, and then can be converged to the channel through the collimating lens, and the light-receiving end face of the channel can be collected by the collimating lens. (also the light-emitting end face) receiving, so as to realize the coaxial light emission and reception, which is beneficial to improve the measurement accuracy of echo reception.
  • the scanning method embodiments of the present application can be applied to the above-mentioned lidar embodiments, so as to improve the problem of reduced coupling between the echo signal and the optical waveguide caused by the time-of-flight, so as to achieve complete coverage of the high point density in the entire scanning area, and A larger clear aperture can be obtained.

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Abstract

一种激光雷达（10）及其扫描方法，激光雷达（10）包括：发射及接收模组（20）、准直模组（30）和扫描模组（40），发射及接收模组（10）设在准直模组（20）的后端，扫描模组（40）设在准直模组（20）的前端；其中，发射及接收模组（20）包括具有至少一个通道的光波导；扫描模组（40）包括第一楔形镜模组（401）和第二楔形镜模组（402），第一楔形镜模组（401）和第二楔形镜模组（402）沿准直模组（20）的光轴方向前后间隔设置，其适用于中长距离的测量。

Description

一种激光雷达及其扫描方法
本申请要求于2020年12月10日提交中国专利局、申请号为202011458450.7，发明名称为“一种激光雷达及其扫描方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及测量技术领域，尤其涉及一种激光雷达及其扫描方法。
背景技术
频连续波激光雷达(Frequency Modulation Continuous Wave Lidar,FMCW Lidar)本质是外差干涉测量，原理是将激光器线性调频，并将激光一分为二，一路为本振光，一路为信号光，信号光准直出射并经目标反射进入接收系统，与本振光进行干涉产生拍频信号，信号中携带了飞行时间产生的频率调谐量以及相对运动产生的多普勒频移，测量拍频频率从而结算距离和速度信息。
目前FMCW的扫描系统，主要是基于振镜、棱镜等反射方式进行扫描。这种扫描方式进行中长距测量时，容易造成飞行时间带来的回波信号与接收器件之间耦合性降低的问题，从而影响成像质量。
发明内容
有鉴于此，本申请实施例提供一种激光雷达及其扫描方法，便于改善飞行时间带来的回波信号与接收器件之间耦合性降低的问题。
为达到上述目的，第一方面，本申请实施例提供一种激光雷达，包括：发射及接收模组、准直模组和扫描模组，所述发射及接收模组设在所述准直模组的后端，所述扫描模组设在所述准直模组的前端；其中，所述发射及接收模组包括具有至少一个通道的光波导；所述扫描模组包括第一楔形镜模组和第二楔形镜模组，所述第一楔形镜模组和第二楔形镜模组沿所述准直模组的光轴方向前后间隔设置，所述第一楔形镜模组和所述第二楔形镜模组中的楔形镜能够分别绕所述准直模组的光轴旋转。
根据本申请实施例一具体实现方式，所述光波导中的一通道发出的光，由所述准直模组准直，并通过所述第一楔形镜模组和所述第二楔形镜模组扫描后，通过目标反射后的回波，通过所述第一楔形镜模组和所述第二楔形镜模组后，由所述准直模组耦合进入该通道。
根据本申请实施例一具体实现方式，所述光波导为光纤或光纤束，所述光纤束的出光端面呈阵列排布。
根据本申请实施例一具体实现方式，所述第一楔形镜模组包括：第一旋转机构和安装在所述第一旋转机构上的第一楔形镜；所述第二楔形镜模组包括：第二旋转机构和安装在所述第二旋转机构上的第二楔形镜。
根据本申请实施例一具体实现方式，所述第一旋转机构包括第一驱动电机、第一齿轮传动机构和第一楔形镜安装筒；所述第一齿轮传动机构的输入端与所述第一驱动电机的输出轴相连，输出端与所述第一楔形镜安装筒相连；所述第一楔形镜安装在所述第一楔形镜安装筒内；所述第二旋转机构包括第二驱动电机、第二齿轮传动机构和第二楔形镜安装筒；所述第二齿轮传动机构的输入端与所述第二驱动电机的输出轴相连，输出端与所述第二楔形镜安装筒相连；所述第二楔形镜安装在所述第二楔形镜安装筒内；或者，
所述第一旋转机构包括第一驱动电机、第一驱动齿轮和第一齿圈，所述第一驱动齿轮与所述第一驱动电机的输出轴相连，所述第一齿圈与所述第一驱动齿轮相啮合，所述第一楔形镜安装在所述第一齿圈中；所述第二组旋转机构包括第二驱动电机、第二驱动齿轮和第二齿圈，所述第二驱动齿轮与所述第二驱动电机的输出轴相连，所述第二齿圈与所述第二驱动齿轮相啮合，所述第二楔形镜安装在所述第二齿圈中。
根据本申请实施例一具体实现方式，所述第一齿轮传动机构包括第一驱动齿轮和第一齿圈；所述第一齿圈套设在所述第一楔形镜安装筒的外周并与所述第一楔形镜安装筒固定连接，所述第一驱动齿轮与所述第一驱动电机的输出轴固定连接，并与所述第一齿圈外周的齿相啮合；所述第二齿轮传动机构包括第二驱动齿轮和第二齿圈；所述第二齿圈套设在所述第二楔形镜安装筒的外周并与所述第二楔形镜安装筒固定连接，所述第二驱动齿轮与所述第二驱动电机的输出轴固定连接，并与所述第二齿圈外周的齿相啮合。
根据本申请实施例一具体实现方式，所述扫描模组还包括扫描镜筒、第一轴承和第二轴承；所述第一轴承和所述第二轴承设在所述扫描镜筒内，所述第一轴承的外圈和所述第二轴承的外圈与所述扫描镜筒相对固定；所述第一楔形镜安装筒套设在所述第一轴承的内圈中并与所述第一轴承的内圈相固定；所述第二楔形镜安装筒套设在所述第二轴承的内圈中并与所述第二轴承的内圈相固定。
根据本申请实施例一具体实现方式，所述光纤或光纤束的第一端设在光纤盒中，所述光纤或光 纤束的第一端的端面位于所述光纤盒的端部。
根据本申请实施例一具体实现方式，所述的激光雷达，还包括对焦调节模组；其中，所述对焦调节模组包括：调焦螺帽，所述调焦螺帽的前端套设在所述准直模组的后端并与所述准直模组的后端螺纹连接，所述调焦螺帽的后端与所述发射及接收模组相邻设置。
根据本申请实施例一具体实现方式，所述调焦螺帽为一端具有螺纹连接口的筒状结构，所述筒状结构的底部中央位置处设有与所述光波导的通道相对应的通光口；所述调焦螺帽通过所述螺纹连接口与所述准直模组的后端螺纹连接；
在所述筒状结构内部设有弹性补偿件，所述弹性补偿件抵压在所述准直模组的后端和所述筒状结构的底部之间。
根据本申请实施例一具体实现方式，所述光波导为光纤或光纤束，所述光纤或光纤束的第一端设在光纤盒中，所述光纤或光纤束的第一端的端面位于所述光纤盒的端部；所述光纤盒上设有光纤盒固定件，所述光纤盒固定件的前端设有连接板，在所述连接板上，于第一圆周和第二圆周上分别设有两个以上间隔设置的轨道槽，其中第二圆周上的两个以上的轨道槽，与第一圆周上的两个以上的轨道槽交错设置；所述调焦螺帽后端的端面上，于第一圆周上和第二圆周上分别设有两个以上的螺纹孔；第一圆周上至少有一个螺纹孔与所述连接板上的第一圆周上的一轨道槽相对应，第二圆周上至少有一个螺纹孔与所述连接板上的第二圆周上的一轨道槽相对应。
根据本申请实施例一具体实现方式，所述的激光雷达，还包括光轴调节模组，所述光轴调节模组与所述发射及接收模组相连接；其中，所述光轴调节模组包括上下位置调节模组和水平位置调节模组，以对所述光波导进行上下方向和水平方向两个自由度的位置调节。
根据本申请实施例一具体实现方式，所述准直模组包括准直镜筒，在准直镜筒的前端设有透镜，准直镜筒的后端设置光阑开孔；其中，所述透镜靠近所述发射及接收模组一侧的透光面为平面，远离所述发射及接收模组一侧的透光面为凸面。
第二方面，本申请实施例提供一种激光雷达扫描方法，包括：将激光从光波导的至少一个通道中射出；对光波导的至少一个通道射出的激光进行准直；准直后的激光，依次经过两个以上具有不同转速的楔形镜扫描后射出。
根据本申请实施例一具体实现方式，所述将激光从光波导中射出，包括：将激光从光波导中以 阵列的方式射出。
根据本申请实施例一具体实现方式，所述将激光从光波导中以阵列的方式射出，包括：将激光从由多根光纤组成的光纤束的光纤端面阵列，以阵列的方式射出。
根据本申请实施例一具体实现方式，所述两个以上具有不同转速的楔形镜扫描，包括第一楔形镜和第二楔形镜；其中，所述准直后的激光，依次经过两个以上具有不同转速的楔形镜扫描后射出，包括：准直后的激光，经过第一楔形镜扫描后，再经过第二楔形镜扫描射出；所述第一楔形镜和所述第二楔形镜具有不同的转速。
根据本申请实施例一具体实现方式，所述第一楔形镜的转速是所述第二楔形镜的转速的0.5倍-3倍。
根据本申请实施例一具体实现方式，所述的激光雷达扫描方法，还包括：对所述光波导的一通道射出的激光准直后，依次经过所述两个以上具有不同转速的楔形镜扫描后射出，经目标反射后的反射光，依次经过所述两个以上楔形镜后，汇聚至该通道，由该通道接收。
本申请实施例激光雷达及及其扫描方法，第一楔形镜模组和第二楔形镜模组相配合对光波导的出射光进行扫描，可获得围绕光轴中心对称的扫描轨迹。在边缘视场扫描速度最小，仅在中心视场时扫描速度达到最大，因而其整个扫描过程中的平均速度相对更小，大部分扫描时间内的像移相对较小，从而整体上改善飞行时间带来的回波信号与光波导之间耦合性降低的问题。
附图说明
为了更清楚地说明本申请实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其它的附图。
图1a和图1b是基于振镜、棱镜等反射方式，分别在不扫描状态下和扫描状态下回波信号接收示意图。
图2a为单个楔形镜光路传导示意图。
图2b为单个楔形镜扫描轨迹示意图。
图2c双楔形镜扫描原理示意图。
图2d双楔形镜扫描轨迹示意图。
图3为本申请一实施例激光雷达结构的主视图。
图4为图3所示实施例的俯视图。
图5为图3所示实施例的剖视图。
图6为本申请一实施例中光纤端面阵列发射及接收光路示意图。
图7a至图7d为本申请一实施例中光纤盒的结构示意图。
图8为图1中准直模组的结构示意图。
图9为图1中扫描模组的结构示意图。
图10a为图5中光纤盒固定件的结构示意图。
图10b为图5中调焦螺帽后端的端面示意图。
图10c为光纤盒固定件与调焦螺帽后端端面配合结构示意图。
图11为本申请一实施例激光雷达扫描方法流程图。
图12a-图12d为本申请一实施例中通过两个楔形镜扫描时，慢速楔形镜旋转1、2、5和13圈时的扫描图案。
图13a为本申请一实施例中4*4分布的光纤端面阵列示意图。
图13b为通过图13a所示的光纤端面阵列出射的激光准直后通过两个楔形镜扫描的示意图。
图14a为本申请一实施例中通过两个楔形镜扫描获得的一帧扫描点云轨迹示意图。
图14b为本申请一实施例中十帧叠加后的扫描点云轨迹示意图。
具体实施方式
下面结合附图对本申请实施例进行详细描述。
应当明确，本文所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其它实施例，都属于本申请保护的范围。
FMCW基于光波导的扫描系统，可以基于振镜、棱镜等反射方式进行扫描。但这种基于振镜、棱镜等反射方式进行扫描，在中长距测量下可能并不太适用。因为在中长距测量下，扫描的范围通常较大，为确保点云的刷新速率，快轴需要以极快的扫描速度进行扫描，用来测量的光又具有较长的飞行时间，这样容易使回波信号偏离出光波导的接收面，造成成像点的偏移，从而使光波导的接收面无法收到回波信号，或导致回波信号快速衰减，影响测量精度。
图1a和图1b是基于振镜、棱镜等反射方式，分别在不扫描状态下和扫描状态下回波信号接收示意图。图1a中是在不扫描时，发射光和接收光同轴(即收发同轴)，信号光原路返回，此时成像点在接收光轴上。图1b中是在扫描时，接收光轴(实线所示)在飞行时间内发生旋转，此时被测物相对于接收光轴发生了移动，等效于成像点在接收面上发生了像移，成像点远离光轴。当成像点远离光轴的离轴高度大于接收面尺寸边界时，接收面无法接收到回波信息。
为有效降低飞行时间带来的回波信号与接收器件(光波导)之间耦合性降低的问题，本申请实施例提供一种具有楔形镜扫描结构的激光雷达及其扫描方法。
楔形镜扫描原理：
光学经过楔形镜，光线会发生偏折。偏折角度与折射率和楔形夹角有关。如图2a所示，折射角sinβ＝n sinα，出射光线相对于竖直的入射光的偏转角度为φ＝β-α；当楔形镜绕竖直轴进行角度为γ的旋转时，会使出射光沿竖直轴旋转夹角γ，且与竖直轴始终保持夹角φ，这就形成了一个圆形的扫描轨迹。图2b为一楔形镜旋转时形成的一个圆形扫描轨迹示意图。
当两个楔形镜重叠并按各自周期旋转，其偏转角φ和旋转夹角γ也进行了各自的叠加，则形成了一个复杂的扫描轨迹。在双楔形镜各自特定的扫描周期下，可实现圆形区域的全覆盖非周期扫描，参看图2c及图2d。
图3为本申请一实施例激光雷达结构的主视图，图4为图3所示实施例的俯视图，图5为图3所示实施例的剖视图。参看图3至图5，本实施例激光雷达10包括：发射及接收模组20、准直模组30和扫描模组40，发射及接收模组20设在准直模组30的后端，扫描模组40设在准直模组30的前端；其中，发射及接收模组20包括具有至少一个通道的光波导；扫描模组40包括第一楔形镜模组401和第二楔形镜模组402，第一楔形镜模组401和第二楔形镜模组402沿准直模组30的光轴方向前后间隔设置，第一楔形镜模组401和第二楔形镜模组402中的楔形镜能够分别绕所述准直模组30的光轴旋转。
第一楔形镜模组401和第二楔形镜模组402可分别带动各自的楔形镜进行旋转，以实现对光波导所发出的出射光进行扫描。第一楔形镜模组401和第二楔形镜模组402其中一个可为快轴扫描模组40(其中的楔形镜可称为快速楔形镜)，另一个为慢轴扫描模组40(其中的楔形镜可称为快速楔形镜)。
本实施例中，第一楔形镜模组401和第二楔形镜模组402相配合对光波导的出射光进行扫描，可获得围绕光轴中心对称的扫描轨迹。在边缘视场扫描速度最小，仅在中心视场时扫描速度达到最大，因而其整个扫描过程中的平均速度相对更小，大部分扫描时间内的像移相对较小，从而整体上改善飞行时间带来的回波信号与光波导之间耦合性降低的问题。
此外，采用楔形镜扫描，无需在扫描空间中进行横向和纵向的扫描线数分配，其扫描轨迹是无周期错位旋转的，多帧数下(即随着扫描时间的推移所获得的扫描图像)能实现整个扫描区域的高点密度完全覆盖。
再者，采用楔形镜扫描时，因其扫描时是绕光轴进行旋转的，可获得较大的通光口径。
发射及接收模组20、准直模组30和扫描模组40可共同设在一基板50上。
发射及接收模组20，也可称为发射及接收器件，用来发射激光和接收经目标反射后的回波(也可称为回波信号或返回光)。发射及接收模组20发射的激光，可以是连续激光，也可以是脉冲激光。
光波导(optical waveguide)是引导光波在其中传播的介质装置，又称介质光波导。
光波导的通道(也可称为光通道)数量可为一个。一个通道发出的光，由准直模组30准直，并通过第一楔形镜模组401和第二楔形镜模组402扫描后，通过目标反射后的回波，通过第一楔形镜模组401和第二楔形镜模组402后，由准直模组30耦合进入该通道，即由该通道接收，可实现光的发射与接收同轴，有利于提高回波接收的测量的精确度。
为提高所获得的测量图像的点云密度，光波导可具有多个通道。每一通道发出的光，由准直模组30准直，并通过第一楔形镜模组401和第二楔形镜模组402扫描后，通过目标反射后的回波，通过第一楔形镜模组401和第二楔形镜模组402后，由准直模组30耦合进入对应的通道，即由该对应的通道接收。简言之，由一通道发出的光，通过目标反射后的回波，由该发出光的同一通道接收，可实现光的发射与接收同轴，有利于提高回波接收的测量的精确度。
比如光波导上有12个通道，第1个通道既可发射光，也可接收其发射的光的回波，第1个通道可实现光的收发同轴。同理，第2个通道等其它各通道，均可实现光的收发同轴，即收发光路可逆。
光波导的多个通道的出光端面可呈阵列排布方式布置。阵列排布方式可以是矩阵阵列、圆形阵列或线阵列等。相邻通道中心的间距可为150um至300um。
光波导可采用多种结构形式。在一实施例中，光波导采用光纤的结构形式。当需要采用多个通道时，可采用光纤束的结构形式，即采用由多根光纤并排组合在一起的结构形式。下面的实施例中光波导主要以光纤束201为例进行举例说明。
在光纤束201中，光纤的出光端面呈阵列布置，因此，光纤束201的出光端面也可称为光纤端面阵列。
光纤束201中光纤的数量可以是2-18根。在一个例子中，由12根光纤组成光纤束201，12根光纤的出光端面呈矩阵阵列布置。在另一个例子中，由18根光纤组成光纤束201，18根光纤的出光端面呈圆形阵列布置。
其中的每根光纤可为单模光纤，其发散全角可为9°至12°，发散角可由数值孔径获得。
图6为本申请一实施例中光纤端面阵列发射及接收光路示意图。参看图6，光纤端面阵列中一光纤端面发出的光，由准直模组30准直，并通过第一楔形镜模组401和第二楔形镜模组402扫描后，通过目标反射后的回波，通过第一楔形镜模组401和第二楔形镜模组402后，由准直模组30耦合进入该光纤端面，即由该光纤端面接收。也就是说，由同一光纤端面发出的光，通过目标反射后的回波，由同一光纤端面接收，可实现光的发射与接收同轴。
图7a至图7d为本申请一实施例中光纤盒的结构示意图。其中，图7a为本申请一实施例中光纤盒的主视图，图7b为图7a中A处(光纤端面阵列)的局部放大示意图，图7c为图7a所示光纤盒的仰视图，图7d为图7a所示光纤盒的立体图。参看图1及图7a至图7d，为便于光纤束201的排布，光纤束201的一端可设在光纤盒202中，光纤端面阵列203位于光纤盒202的前端，便于出光及接收回波。光纤束201的另一端自光纤盒202的后端引出并可通过光纤固定件固定在基板50上。
准直模组30，用来将发射及接收模组20出射的激光束进行准直，形成平行光束。图8为图1中准直模组的结构示意图，参看图8，在一实施例中，准直模组30可包括准直镜筒301，在准直镜筒301的前端设有透镜302。准直镜筒301的前端是指准直镜筒301的两端中远离发射及接收模组20的一端。
透镜302靠近发射及接收模组20一侧的透光面为平面，远离发射及接收模组20一侧的透光面为凸面。透镜302的直径可为3-100mm，焦距可为3-500mm。
本实施例的激光雷达10，可用来进行中长距离(0.1km-5km)的距离和/或速度测量。在一个例子中，透镜302的直径为60mm，焦距为220mm，可用来5km长距离的距离和/或速度测量。
透镜302可通过胶体和/或压圈固定在准直镜筒301上，以增强与准直镜筒301之间连接的可靠性。
透镜302除了可以将光纤端面阵列203中各光纤端面发出的激光进行准直形成平行光束外，还可以将回波进行汇聚，耦合进入对应的光纤端面，被对应的光纤端面所接收。
准直镜筒301可为中空的长型结构。在准直镜筒301的内壁可做螺纹或消光等处理，准直镜筒301的后端可设置光阑开孔，以消除光阑前反射回来的杂散光，包括透镜302表面的反射光，可能存在的作为扫描部件的楔形镜表面的反射光，以及其它结构面上的反射光。
扫描模组40，用来将经过准直模组30的透镜302准直后的光进行扫描，以获得较大的空间测量范围。扫描模组40中的第一楔形镜模组401和第二楔形镜模组402分别安装有楔形镜。楔形镜的外形可为圆形，截面形状为楔形。楔形镜的顶角(也可称为楔角)可以是0.2°-30°，其可影响最大扫描范围的直径。最大的理论扫描全角可为两个光楔偏转角和的两倍。第一楔形镜模组401和第二楔形镜模组402安装的楔形镜的顶角可以相同，也可以不同。
第一楔形镜模组401和第二楔形镜模组402中的楔形镜可按不同的转速进行转动。第一楔形镜模组401和第二楔形镜模组402中的楔形镜的转动方向可以相同，也可以不同。
在一个例子中，楔形镜的顶角为0.5°，两楔形镜旋转方向相反，转速比为1:3.3。该转速比可有效减少光纤的像移，即可使单根光纤的端面对其发出的光的回波进行准确接收，避免接收不到回波的情况。
应当理解的是，扫描模组40中除了包括第一楔形镜模组401和第二楔形镜模组402之外，还可包括第三楔形镜模组、第四楔形镜模组等其它多个楔形镜模组。
图9为图1中扫描模组的结构示意图，参看图9，第一楔形镜模组401和第二楔形镜模组402可为两套相对独立的形镜模组。第一楔形镜模组401可包括：第一旋转机构4011和安装在第一旋转机构4011上的第一楔形镜4012；第二楔形镜模组402可包括：第二旋转机构4021和安装在第二旋转机构4021上的第二楔形镜4022。第一楔形镜4012由第一旋转机构4011带动旋转，第二楔形镜4022由第二旋转机构4021带动旋转。
第一旋转机构4011和第二旋转机构4021可包括同步带传动机构或齿轮传动机构。参看图4及图9，在一实施例中，第一旋转机构4011和第二旋转机构4021包括齿轮传动机构，具体地，第一旋转机构4011可包括第一驱动电机40111、第一齿轮传动机构40112和第一楔形镜安装筒40113；第一齿轮传动机构40112的输入端与第一驱动电机40111的输出轴相连，输出端与第一楔形镜安装筒40113相连；第一楔形镜4012安装在第一楔形镜安装筒40113内。
第二旋转机构4021可包括第二驱动电机40211、第二齿轮传动机构40212和第二楔形镜安装筒40213；第二齿轮传动机构40212的输入端与第二驱动电机40211的输出轴相连，输出端与第二楔形镜安装筒40213相连；第二楔形镜4022安装在第二楔形镜安装筒40213内。
第一楔形镜4012和第二楔形镜4022可分别通过楔形镜压圈和点胶固定在对应的楔形镜安装筒内。
第一驱动电机40111和第二驱动电机40211，其中一个可为快轴电机(转速相对较快)，另一个可为慢轴电机(转速相对较慢)。可通过对第一驱动电机40111和第二驱动电机40211转速的控制来控制双楔镜(第一楔形镜4012和第二楔形镜4022)的扫描轨迹和速度，并由电机编码器反馈实时的位姿情况，从而实现高效且准确的双楔镜非周期高速扫描。为降低系统复杂性，也可采用半开环的模式，不需对第一驱动电机40111和第二驱动电机40211的转速进行高频率实时控制，而是根据编码器反馈的实时位姿对扫描轨迹进行解算，获得实际扫描轨迹坐标。
参看图4及图9，第一齿轮传动机构40112可包括第一驱动齿轮401121和第一齿圈401122；第一齿圈401122套设在第一楔形镜安装筒40113的外周并与第一楔形镜安装筒40113固定连接，第一驱动齿轮401121与第一驱动电机40111的输出轴固定连接，并与第一齿圈401122外周的齿相啮合。
第二齿轮传动机构40212可包括第二驱动齿轮402121和第二齿圈402122；第二齿圈402122套设在第二楔形镜安装筒40213的外周并与第二楔形镜安装筒40213固定连接，第二驱动齿轮402121与第二驱动电机40211的输出轴固定连接，并与第二齿圈402122外周的齿相啮合。
第一楔形镜安装筒40113和第二楔形镜安装筒40213的外周，可分别设有用来与对应的齿圈固定连接的卡槽。
第一齿轮传动机构40112和第二齿轮传动机构40212的齿轮组(驱动齿轮和齿圈构成的齿轮组) 的减速比可以相同，也可以不同。当第一齿轮传动机构40112和第二齿轮传动机构40212的齿轮组减速比不同时，能实现楔形镜扫描轨迹和扫描速度的更宽范围的控制。在一实施例，快轴齿轮组可以是慢轴齿轮组的输出转速的1-3倍。快轴楔形镜是可以是慢轴楔形镜转速的1-10倍。
上述实施例中，第一楔形镜4012和第二楔形镜4022分别安装在对应的楔形镜安装筒中，通过与楔形镜安装筒相连的齿圈及与齿圈相连的驱动齿轮带动楔形镜安装筒转动，从而带动楔形镜转动，以实现扫描功能。
为使结构更加简单，在其它一些实施例中，楔形镜也可直接安装在齿圈中，具体地，第一旋转机构4011包括第一驱动电机40111、第一驱动齿轮401121和第一齿圈401122，第一驱动齿轮401121与第一驱动电机40111的输出轴相连，第一齿圈401122与第一驱动齿轮401121相啮合，第一楔形镜4012安装在第一齿圈401122中；第二组旋转机构包括第二驱动电机40211、第二驱动齿轮402121和第二齿圈402122，第二驱动齿轮402121与第二驱动电机40211的输出轴相连，第二齿圈402122与第二驱动齿轮402121相啮合，第二楔形镜4022安装在第二齿圈402122中。
在第一楔形镜4012和第二楔形镜4022分别安装在对应的楔形镜安装筒中的实施例中，为了便于对楔形镜安装筒的转动提供稳定的支撑，以及便于使两个楔形镜安装筒保持同轴设置，参看图9，在一些实施例中，扫描模组40还可包括扫描镜筒403、第一轴承404和第二轴承405；第一轴承404和第二轴承405设在扫描镜筒403内，第一轴承404的外圈和第二轴承405的外圈与扫描镜筒403相对固定；第一楔形镜安装筒40113套设在第一轴承404的内圈中并与第一轴承404的内圈相固定；第二楔形镜安装筒40213套设在第二轴承405的内圈中并与第二轴承405的内圈相固定。
第一轴承404和第二轴承405的外圈的一侧可分别抵靠在扫描镜筒403内的环形台阶上，另一侧可通过压圈锁定。
为便于准直镜筒301中的透镜302将回波准确地耦合进入对应的光纤端面，需要使光纤端面阵列203的中心调节至所述透镜302的焦点位置。为此，参看图3及图5，在一实施例中，所述激光雷达10，还可包括对焦调节模组60。
参看图8，其中，对焦调节模组60可包括：调焦螺帽601，调焦螺帽601的前端套设在准直模组30的后端并与准直模组30的后端螺纹连接，调焦螺帽601的后端与发射及接收模组20相邻设置。
沿着一个方向(如逆时针方向)旋转调焦螺帽601，调焦螺帽601向准直模组30的后端方向移动，以便可推动发射及接收模组20向后移动，从而增大光纤端面阵列203与准直模组30中的透镜302之间的焦距。
沿着相反方向(如顺时针方向)旋转调焦螺帽601，调焦螺帽601向准直模组30的前端方向移动，以便带动(或手动推动)发射及接收模组20向前移动，从而减小光纤端面阵列203与准直模组30中的透镜302之间的焦距。
参看图8，为避免螺纹间隙对调焦精确度的影响，可在调焦螺帽601与准直模组30之间设置弹性补偿件602，通过弹性补偿件602可消除螺纹间隙，增加调节精度。在一实施例中，调焦螺帽601为一端具有螺纹连接口的筒状结构，筒状结构的底部中央位置处设有与光纤端面阵列203相对应的通光口，以使自光纤端面阵列203出射的激光束通过调焦螺帽601后进入准直镜筒301中；调焦螺帽601通过螺纹连接口与准直模组30的后端螺纹连接；在筒状结构内部设有弹性补偿件602，弹性补偿件602抵压在准直模组30的后端和筒状结构的底部之间。弹性补偿件602可以是弹簧，为金属弹片或橡胶弹性件等。
在调焦过程中，为使光纤端面阵列203仅做前后移动而不做转动，调焦螺帽601和发射及接收模组20之间可不直接相连，在调焦完成后再将二者连接在一起以实现相互定位。
参看图7a至图7d，在一实施例中，光纤束201的一端设在光纤盒202中，光纤端面阵列203位于光纤盒202的端部。
图10a为图5中光纤盒固定件的结构示意图,图10b为图5中调焦螺帽后端的端面示意图,图10c为光纤盒固定件与调焦螺帽后端端面配合结构示意图。
参看图5及图10a，光纤盒202上设有光纤盒固定件204，光纤盒固定件204的前端设有连接板2041，在连接板2041上开设有差分式轨道槽。
参看图10b及图10c，调焦螺帽601后端的端面上设有多个螺纹孔。调焦螺帽601旋转360度的过程中，可始终有螺纹孔与差分式轨道槽相对应。
具体地，在连接板2041上，于第一圆周和第二圆周上分别设有两个以上间隔设置的轨道槽S1和S2，其中第二圆周上的两个以上的轨道槽S2，与第一圆周上的两个以上的轨道槽S1交错设置；
调焦螺帽601后端的端面上，于第一圆周上和第二圆周上分别设有两个以上的螺纹孔h1和h2； 第一圆周上至少有一个螺纹孔h1与连接板上的第一圆周上的一轨道槽S1相对应，第二圆周上至少有一个螺纹孔h2与连接板上的第二圆周上的一轨道槽S2相对应。
这样，调焦螺帽601旋转360度的过程中，始终有螺纹孔与差分式轨道槽相对应，可实现调焦螺帽601的无级调节，使光纤端面阵列203和准直镜筒301中的透镜302之间的对焦调节(也可称为焦距调节)具有连续性，并在调节完成后，便于通过在螺纹孔中穿设螺钉以将调焦螺帽601与光纤盒固定件204进行前后相对位置的定位。
参看图10a，在一个例子中，第一圆周上设置有三个轨道槽，该三个轨道槽等间距设置；第二圆周上也设置有三个轨道槽，该三个轨道槽亦等间距设置。第二圆周的半径小于第一圆周的半径，第二圆周上的三个轨道槽与第一圆周上的三个轨道槽交错设置。参看图10b，调焦螺帽601后端的端面上的螺纹孔可包括第一圆周上设置的六个螺纹孔和在第二圆周上设置的六个螺纹孔，第二圆周上的六个螺纹孔，与第一圆周上的六个螺纹孔对应设置。
光纤盒固定件204上可设有光纤盒容纳腔2042，光纤盒202可设在光纤盒容纳腔2042中。
为了使光纤端面阵列203的中心光轴与准直镜筒301中的透镜302的光轴相一致，使得回波能够准确地耦合到对应的光纤中，参看图3及图5，在一实施例中，所述激光雷达10，还可包括光轴调节模组70，光轴调节模组70与发射及接收模组20相连接；
其中，光轴调节模组70包括上下位置调节模组和水平位置调节模组，以对光纤端面阵列203进行上下方向和水平方向两个自由度(也可称为X方向和Y方向)的位置调节。本实施例不限于此，在其它实施例中，光轴调节模组70也可对光纤端面阵列203实现左上、左下、右上及右上等方位的调节。
其中的上下位置调节模组和水平位置调节模组相配合以实现两个自由度方向的位移调节的具有实现结构，可采用现有的相关技术来实现，在此不做详细阐述。
参看图5，在一实施例中，光轴调节模组70可与光纤盒固定件204相连，通过调节光纤盒固定件204在上下方向和水平方向的位移，以使光纤盒固定件204上安装的光纤盒202上的光纤端面阵列203的中心光轴与准直镜筒301中的透镜302的光轴对齐。在一个例子中，光纤盒固定件204可通过一背板2042固定连接在光轴调节模组70上。
光纤盒固定件204的后端也可设有连接板，该连接板与背板2042之间也可采用光纤盒固定件 204前端的连接板与调焦螺帽601之间的螺纹孔与差分轨道槽相配合的连接结构。
光轴调节模组70可以和对焦调节模组60结合使用。通过对焦调节模组60调焦完成后，通过在所述螺纹孔中穿设螺钉以将调焦螺帽601与光纤盒固定件204进行前后相对位置的定位，然后操作光轴调节模组70，调节光纤端面阵列203的上下方向和/或水平方向的位置，以实现光纤端面阵列203的中心光轴与准直镜筒301中的透镜302的光轴对齐。
其中，螺纹孔中穿设的螺钉直径小于轨道槽的宽度，以便即使螺钉将调焦螺帽601与光纤盒固定件204之间的前后相对位置定位后，在通过光轴调节模组70实现光纤端面阵列203的中心光轴与准直镜筒301中的透镜302的光轴对齐的过程(也简称为对轴过程)中，螺钉在轨道槽中仍可在上下方向和水平方向浮动。当对轴过程完成后，可将拧紧螺钉，以将螺钉与轨道槽相互锁紧，也可进一步进行封胶固定。
图11为本申请一实施例激光雷达扫描方法流程图，本实施例的扫描方法可应用于基于外差干涉的激光测量，参看图11，本实施例的扫描方法可包括步骤(S100-S104)：
S100、将激光从光波导的至少一个通道中射出。
光波导是引导光波在其中传播的介质装置，又称介质光波导。光波导的通道(也可称为光通道)数量可为一个，也可为多个。激光从光源发出后，通过光波导的至少一个通道中射出。光源发出的激光可以是连续激光，也可以是脉冲激光。
S102、对光波导的至少一个通道射出的激光进行准直。
激光从光波导的至少一个通道射出后，可通过准直透镜进行准直，即将从光波导的至少一个通道出射的激光束进行准直，形成平行光束。
为提高所获得的测量图像的点云密度，光波导可具有多个通道。每一通道发出的光，均可通过准直透镜进行准直。
S104、准直后的激光，依次经过两个以上具有不同转速的楔形镜扫描后射出。
楔形镜的外形可为圆形，截面形状为楔形。楔形镜的顶角(也可称为楔角)可以是0.2°-30°，其可影响最大扫描范围的直径。最大的理论扫描全角可为两个光楔偏转角和的两倍。第一楔形镜和第二楔形镜的顶角可以相同，也可以不同。
两个以上楔形镜可根据不同的转速进行转动，以对准直后的激光进行扫描。
两个以上的楔形镜可包括第一楔形镜和第二楔形镜。第一楔形镜和第二楔形镜其中一个可为快速楔形镜，另一个为快速楔形镜。在一实施例中，第一楔形镜的转速是第二楔形镜的转速的0.5倍-3倍。第一楔形镜和第二楔形镜的转动方向可以相同，也可以不同。
本实施例中，通过两个以上具有不同转速的楔形镜相配合，对光波导的出射光进行扫描，可获得围绕光轴中心对称的扫描轨迹。图12a-图12d为本申请一实施例中通过两个楔形镜扫描时，慢速楔形镜旋转1、2、5和13圈时的扫描图案。
本申请实施例可获得围绕光轴中心对称的扫描轨迹。在边缘视场扫描速度最小，仅在中心视场时扫描速度达到最大，因而其整个扫描过程中的平均速度相对更小，大部分扫描时间内的像移相对较小，从而整体上改善飞行时间带来的回波信号与光波导之间耦合性降低的问题。
此外，采用楔形镜扫描，无需在扫描空间中进行横向和纵向的扫描线数分配，其扫描轨迹是无周期错位旋转的，多帧数下(即随着扫描时间的推移所获得的扫描图像)能实现整个扫描区域的高点密度完全覆盖。
再者，采用楔形镜扫描时，因其扫描时是绕光轴进行旋转的，可获得较大的通光口径。
在一实施例中，可将激光从光波导中以阵列的方式射出。其中的阵列可以是矩阵阵列、圆形阵列或线阵列等。相应地，光波导的多个通道的出光端面可呈阵列排布方式布置。相邻通道中心的间距可为150um至300um。
光波导可采用多种结构形式。本实施例中，光波导可采用光纤的结构形式。当需要采用多个通道时，可采用光纤束的结构形式，即采用由多根光纤并排组合在一起的结构形式。在光纤束中，光纤的出光端面呈阵列布置，因此，光纤束的出光端面也可称为光纤端面阵列。在一实施例中，所述将激光从光波导中以阵列的方式射出，可包括：将激光从由多根光纤组成的光纤束的光纤端面阵列，以阵列的方式射出。
图13a为本申请一实施例中4*4分布的光纤端面阵列示意图，图13b为通过图13a所示的光纤端面阵列出射的激光准直后通过两个楔形镜扫描的示意图。
图14a为本申请一实施例中通过两个楔形镜扫描获得的一帧扫描点云轨迹示意图，图14b为本申请一实施例中十帧叠加后的扫描点云轨迹示意图。根据图14a及图14b可以看出，两个楔形镜按照各自的转速进行旋转扫描，可实现高点密度的圆形区域扫描。
在一实施例中，所述的激光雷达扫描方法，还可包括步骤：对所述光波导的一通道射出的激光准直后，依次经过所述两个以上具有不同转速的楔形镜扫描后射出，经目标反射后的反射光，依次经过所述两个以上楔形镜后，汇聚至该通道，由该通道接收。
本实施例中，光波导的一通道射出的激光，经目标反射后的反射光，依次经过所述两个以上楔形镜后，可通过准直透镜汇聚至该通道，由该通道的光接收端面(亦为光发射端面)接收，以实现光的发射与接收同轴，有利于提高回波接收的测量的精确度。
本申请扫描方法实施例，可应用于上述激光雷达实施例中，以改善飞行时间带来的回波信号与光波导之间耦合性降低的问题，实现整个扫描区域的高点密度完全覆盖，并可获得较大的通光口径。
需要说明的是，在本文中，术语“上”、“下”等指示的方位或位置关系的用语，仅是为了便于描述本申请和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。除非另有明确的规定和限定，术语“安装”、“相连”、“连接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接；可以是直接相连，也可以通过中间媒介间接相连。诸如，第一和第二等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来，而不一定要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的过程、方法、物品或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法、物品或者设备所固有的要素。在没有更多限制的情况下，由语句“包括一个……”限定的要素，并不排除在包括要素的过程、方法、物品或者设备中还存在另外的相同要素。对于本领域的普通技术人员而言，可以通过具体情况理解。
以上，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到的变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以权利要求的保护范围为准。

Claims (19)

  1. 一种激光雷达，其特征在于，包括：发射及接收模组、准直模组和扫描模组，所述发射及接收模组设在所述准直模组的后端，所述扫描模组设在所述准直模组的前端；
    其中，所述发射及接收模组包括具有至少一个通道的光波导；
    所述扫描模组包括第一楔形镜模组和第二楔形镜模组，所述第一楔形镜模组和第二楔形镜模组沿所述准直模组的光轴方向前后间隔设置，所述第一楔形镜模组和所述第二楔形镜模组中的楔形镜能够分别绕所述准直模组的光轴旋转。
  2. 根据权利要求1所述的激光雷达，其特征在于，所述光波导中的一通道发出的光，由所述准直模组准直，并通过所述第一楔形镜模组和所述第二楔形镜模组扫描后，通过目标反射后的回波，通过所述第一楔形镜模组和所述第二楔形镜模组后，由所述准直模组耦合进入该通道。
  3. 根据权利要求1所述的激光雷达，其特征在于，所述光波导为光纤或光纤束，所述光纤束的出光端面呈阵列排布。
  4. 根据权利要求1所述的激光雷达，其特征在于，所述第一楔形镜模组包括：第一旋转机构和安装在所述第一旋转机构上的第一楔形镜；
    所述第二楔形镜模组包括：第二旋转机构和安装在所述第二旋转机构上的第二楔形镜。
  5. 根据权利要求4所述的激光雷达，其特征在于，所述第一旋转机构包括第一驱动电机、第一齿轮传动机构和第一楔形镜安装筒；所述第一齿轮传动机构的输入端与所述第一驱动电机的输出轴相连，输出端与所述第一楔形镜安装筒相连；所述第一楔形镜安装在所述第一楔形镜安装筒内；
    所述第二旋转机构包括第二驱动电机、第二齿轮传动机构和第二楔形镜安装筒；所述第二齿轮传动机构的输入端与所述第二驱动电机的输出轴相连，输出端与所述第二楔形镜安装筒相连；所述第二楔形镜安装在所述第二楔形镜安装筒内；
    或者，
    所述第一旋转机构包括第一驱动电机、第一驱动齿轮和第一齿圈，所述第一驱动齿轮与所述第一驱动电机的输出轴相连，所述第一齿圈与所述第一驱动齿轮相啮合，所述第一楔形镜安装在所述第一齿圈中；
    所述第二组旋转机构包括第二驱动电机、第二驱动齿轮和第二齿圈，所述第二驱动齿轮与所述第二驱动电机的输出轴相连，所述第二齿圈与所述第二驱动齿轮相啮合，所述第二楔形镜安装在所述第二齿圈中。
  6. 根据权利要求5所述的激光雷达，其特征在于，
    所述第一齿轮传动机构包括第一驱动齿轮和第一齿圈；所述第一齿圈套设在所述第一楔形镜安装筒的外周并与所述第一楔形镜安装筒固定连接，所述第一驱动齿轮与所述第一驱动电机的输出轴固定连接，并与所述第一齿圈外周的齿相啮合；
    所述第二齿轮传动机构包括第二驱动齿轮和第二齿圈；所述第二齿圈套设在所述第二楔形镜安装筒的外周并与所述第二楔形镜安装筒固定连接，所述第二驱动齿轮与所述第二驱动电机的输出轴固定连接，并与所述第二齿圈外周的齿相啮合。
  7. 根据权利要求6所述的激光雷达，其特征在于，所述扫描模组还包括扫描镜筒、第一轴承和第二轴承；
    所述第一轴承和所述第二轴承设在所述扫描镜筒内，所述第一轴承的外圈和所述第二轴承的外圈与所述扫描镜筒相对固定；
    所述第一楔形镜安装筒套设在所述第一轴承的内圈中并与所述第一轴承的内圈相固定；
    所述第二楔形镜安装筒套设在所述第二轴承的内圈中并与所述第二轴承的内圈相固定。
  8. 根据权利要求3所述的激光雷达，其特征在于，所述光纤或光纤束的第一端设在光纤盒中，所述光纤或光纤束的第一端的端面位于所述光纤盒的端部。
  9. 根据权利要求1所述的激光雷达，其特征在于，还包括对焦调节模组；
    其中，所述对焦调节模组包括：调焦螺帽，所述调焦螺帽的前端套设在所述准直模组的后端并与所述准直模组的后端螺纹连接，所述调焦螺帽的后端与所述发射及接收模组相邻设置。
  10. 根据权利要求9所述的激光雷达，其特征在于，所述调焦螺帽为一端具有螺纹连接口的筒状结构，所述筒状结构的底部中央位置处设有与所述光波导的通道相对应的通光口；
    所述调焦螺帽通过所述螺纹连接口与所述准直模组的后端螺纹连接；
    在所述筒状结构内部设有弹性补偿件，所述弹性补偿件抵压在所述准直模组的后端和所述筒状 结构的底部之间。
  11. 根据权利要求10所述的激光雷达，其特征在于，所述光波导为光纤或光纤束，所述光纤或光纤束的第一端设在光纤盒中，所述光纤或光纤束的第一端的端面位于所述光纤盒的端部；
    所述光纤盒上设有光纤盒固定件，所述光纤盒固定件的前端设有连接板，在所述连接板上，于第一圆周和第二圆周上分别设有两个以上间隔设置的轨道槽，其中第二圆周上的两个以上的轨道槽，与第一圆周上的两个以上的轨道槽交错设置；
    所述调焦螺帽后端的端面上，于第一圆周上和第二圆周上分别设有两个以上的螺纹孔；第一圆周上至少有一个螺纹孔与所述连接板上的第一圆周上的一轨道槽相对应，第二圆周上至少有一个螺纹孔与所述连接板上的第二圆周上的一轨道槽相对应。
  12. 根据权利要求1所述的激光雷达，其特征在于，还包括光轴调节模组，所述光轴调节模组与所述发射及接收模组相连接；
    其中，所述光轴调节模组包括上下位置调节模组和水平位置调节模组，以对所述光波导进行上下方向和水平方向两个自由度的位置调节。
  13. 根据权利要求1所述的激光雷达，其特征在于，所述准直模组包括准直镜筒，在准直镜筒的前端设有透镜，准直镜筒的后端设置光阑开孔；其中，所述透镜靠近所述发射及接收模组一侧的透光面为平面，远离所述发射及接收模组一侧的透光面为凸面。
  14. 一种激光雷达扫描方法，其特征在于，包括：
    将激光从光波导的至少一个通道中射出；
    对光波导的至少一个通道射出的激光进行准直；
    准直后的激光，依次经过两个以上具有不同转速的楔形镜扫描后射出。
  15. 根据权利要求14所述的激光雷达扫描方法，其特征在于，所述将激光从光波导中射出，包括：
    将激光从光波导中以阵列的方式射出。
  16. 根据权利要求15所述的激光雷达扫描方法，其特征在于，所述将激光从光波导中以阵列的方式射出，包括：
    将激光从由多根光纤组成的光纤束的光纤端面阵列，以阵列的方式射出。
  17. 根据权利要求14所述的激光雷达扫描方法，其特征在于，所述两个以上具有不同转速的楔形镜扫描，包括第一楔形镜和第二楔形镜；
    其中，所述准直后的激光，依次经过两个以上具有不同转速的楔形镜扫描后射出，包括：
    准直后的激光，经过第一楔形镜扫描后，再经过第二楔形镜扫描射出；所述第一楔形镜和所述第二楔形镜具有不同的转速。
  18. 根据权利要求18所述的激光雷达扫描方法，其特征在于，所述第一楔形镜的转速是所述第二楔形镜的转速的0.5倍-3倍。
  19. 根据权利要求14所述的激光雷达扫描方法，其特征在于，还包括：
    对所述光波导的一通道射出的激光准直后，依次经过所述两个以上具有不同转速的楔形镜扫描后射出，经目标反射后的反射光，依次经过所述两个以上楔形镜后，汇聚至该通道，由该通道接收。
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