WO2021083016A1 - 激光雷达和利用其进行探测的方法 - Google Patents

激光雷达和利用其进行探测的方法 Download PDF

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Publication number
WO2021083016A1
WO2021083016A1 PCT/CN2020/122660 CN2020122660W WO2021083016A1 WO 2021083016 A1 WO2021083016 A1 WO 2021083016A1 CN 2020122660 W CN2020122660 W CN 2020122660W WO 2021083016 A1 WO2021083016 A1 WO 2021083016A1
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WIPO (PCT)
Prior art keywords
lens
lidar
mirror
detector
receiving
Prior art date
Application number
PCT/CN2020/122660
Other languages
English (en)
French (fr)
Inventor
杨金涛
向少卿
Original Assignee
上海禾赛科技股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from CN201911137252.8A external-priority patent/CN111090082A/zh
Application filed by 上海禾赛科技股份有限公司 filed Critical 上海禾赛科技股份有限公司
Priority to EP20880519.2A priority Critical patent/EP4053587A4/en
Publication of WO2021083016A1 publication Critical patent/WO2021083016A1/zh
Priority to US17/733,954 priority patent/US20220260677A1/en

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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
    • G01S17/88—Lidar systems specially adapted for specific applications
    • G01S17/93—Lidar systems specially adapted for specific applications for anti-collision purposes
    • G01S17/931—Lidar systems specially adapted for specific applications for anti-collision purposes of land vehicles
    • 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
    • G01S17/003—Bistatic lidar systems; Multistatic lidar systems
    • 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
    • G01S17/06—Systems determining position data of a target
    • G01S17/42—Simultaneous measurement of distance and other co-ordinates
    • 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
    • G01S7/4817—Constructional features, e.g. arrangements of optical elements relating to scanning

Definitions

  • the present invention relates to the field of optoelectronic technology, in particular to a laser radar and a detection method using the laser radar.
  • Lidar 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 of the corresponding target point can be measured (such as the time-of-flight method).
  • three-dimensional imaging can finally be realized.
  • Lidar has an important application in unmanned driving systems. In this application, Lidar is required to have the characteristics of high imaging frame rate, high resolution, long-range ranging capability, small size, high reliability, and low cost.
  • lidar transmitting systems and receiving systems are separated (different from the situation where the transmitting system and the receiving system share a set of lenses).
  • the field of view of the laser transmitting beam and the detector is at a long distance (such as 200m) aligned, as shown in Figure 1, within a certain distance range closer to the lidar, the laser emission beam and the detector's field of view are completely non-overlapping, so in this distance range, the lidar The detector can not receive the signal light reflected on the target, or the received signal light is extremely weak, this is the close blind zone.
  • the reason for the weak short-distance blind zone or short-distance signal of the lidar is the non-common optical path structure of the transceiver separately, that is, the common optical path structure of the laser transmitting optical path and the signal receiving optical path are not completely coincident, refer to Figure 1, between the transmitting lens and the receiving lens There is a horizontal translation.
  • the short-distance blind zone is an area where the emitted laser beam does not overlap the receiving field of view at a short distance. This means that the lidar detector "cannot see” the emitted laser beam in this area, that is, the detector cannot receive the signal light reflected from the target in this area.
  • the present invention provides a laser radar, including:
  • Laser configured to emit a laser beam
  • An emitting lens arranged downstream of the optical path of the laser, configured to shape the laser beam to emit a probe beam, and the emitting lens has an aperture stop area;
  • a receiving lens configured to receive the light beam of the probe beam after being reflected outside the lidar
  • the compensation mirror is arranged in the aperture stop area of the transmitting lens and configured to receive at least a part of the laser beam and/or the probe beam and deflect it toward the receiving lens.
  • the aperture stop region is located on the side of the emitting lens close to the laser, or on the side far from the laser, or in the middle of the emitting lens.
  • the compensation mirror includes one or more of optical wedges, microprisms, and diffractive optical elements, or a combination of them with spherical lenses or cylindrical lenses, which are covered by an adhesive or a holder. Fixed in the aperture stop area.
  • the compensation mirror is located at a position close to the receiving lens in the aperture stop region.
  • the transmitting lens and the receiving lens are juxtaposed in a horizontal direction, and the position of the compensation mirror satisfies the following relationship:
  • ⁇ 1 is the beam deflection angle, the angle between the beam deflected by the compensation mirror and the beam received by the receiving lens,
  • d is the distance from the installation position of the compensation lens to the center of the receiving lens
  • D is the diameter of the receiving lens
  • the range between L and L' is the area where the short-distance signal is enhanced.
  • the angle between the beam deflected by the compensation mirror and the main field of view of the lidar is smaller than the angle between the ghost line field of view and the main field of view
  • the lidar further includes a receiving end mirror structure and a detector which are sequentially located downstream of the optical path of the receiving lens, and a ghost line elimination device located between the receiving end mirror structure and the detector to block the The light beam that causes ghost lines in the point cloud of the lidar is incident on the detector.
  • the ghost line elimination device includes a diaphragm, and the diaphragm and the detector satisfy the following relationship:
  • D is the diameter of the receiving lens
  • f is the focal length of the receiving lens
  • h is the distance from the diaphragm to the detector
  • d1 is the width of the diaphragm.
  • the diaphragm is in the shape of a strip hole or a round hole, and the diaphragm is made of any one of the following materials: metal, glass that can absorb or reflect light, or ceramic .
  • the ghost line elimination device includes a light barrier.
  • the ghost line elimination device is configured to block a light beam that is not reflected by the mirror structure at a time.
  • the receiving end mirror structure includes a first mirror and a second mirror disposed opposite to each other, the detector includes a photodiode, and the ghost line elimination device is configured to block those The first reflecting mirror and the second reflecting mirror respectively reflect light beams other than the light beams once.
  • the present invention also provides a detection method using the above-mentioned lidar, which includes:
  • Emitting a laser beam through the laser Emitting a laser beam through the laser
  • the light beam reflected by the obstruction outside the lidar is received by the receiving lens.
  • the short-distance blind area range of the transceiver split lidar can be reduced, and/or the signal strength of short-distance detection can be enhanced.
  • Figures 1 and 2 show schematic diagrams of possible causes of the near blind zone
  • Fig. 3 shows a schematic diagram of a lidar according to an embodiment of the present invention
  • Fig. 4 shows a schematic diagram of multiple laser beams passing through an aperture stop on the focal plane of the emitting lens
  • Fig. 5 shows a schematic diagram of ghost lines in a lidar point cloud according to an embodiment of the present disclosure
  • Fig. 6 shows a schematic diagram of a ghost line caused by a transmitting end according to an embodiment of the present disclosure
  • FIG. 7 shows a schematic diagram of a ghost line caused by a receiving end according to an embodiment of the present disclosure
  • Fig. 8A shows a schematic diagram of a receiving system for suppressing ghost lines with an aperture according to an embodiment of the present disclosure
  • Fig. 8B shows a schematic diagram of the parameters of the diaphragm and the detector
  • Fig. 9 shows a schematic diagram of a strip hole diaphragm according to an embodiment of the present disclosure.
  • Fig. 10 shows a schematic diagram of a circular aperture diaphragm according to an embodiment of the present disclosure
  • Fig. 11 shows a schematic diagram of a receiving system for suppressing ghost lines by a light barrier according to an embodiment of the present disclosure
  • Fig. 12 shows a schematic diagram of a light barrier according to an embodiment of the present disclosure
  • FIG. 13 shows a method for suppressing ghost lines in the point cloud of lidar according to an embodiment of the present disclosure
  • Figure 14 shows a schematic diagram of a lidar according to a preferred embodiment of the present invention.
  • Figure 15 shows a schematic diagram of a lidar according to a preferred embodiment of the present invention.
  • Figure 16 shows a schematic diagram of a lidar according to a preferred embodiment of the present invention.
  • Figure 17 shows a schematic diagram of a lidar according to a preferred embodiment of the present invention.
  • FIG. 18 shows a method of detecting using lidar according to an 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 relationship.
  • an intermediate medium which can be the internal communication of two components or the interaction of two components relationship.
  • the first feature "on” or “under” 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 obliquely 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 obliquely above the second feature, or it simply means that the level of the first feature is smaller than the second feature.
  • Fig. 3 shows a schematic diagram of a lidar 100 according to an embodiment of the present invention. This will be described in detail below in conjunction with FIG. 3.
  • the laser radar 100 includes a laser 101, a transmitting lens 102, a receiving lens 103 and a detector 105.
  • the laser 101 is, for example, an edge emitting laser (EEL) or a vertical cavity surface emitting laser (VCSEL), which is configured to emit a laser beam, and the laser beam is incident on the emitting lens 102 downstream of the optical path.
  • the emitting lens 102 is configured to shape the laser beam to emit a probe beam, and the emitting lens 102 has an aperture stop area.
  • the detection beam is incident on an object OB outside the lidar 100, causing diffuse reflection, and a part of the reflected beam returns to the receiving lens 103, and is condensed on the detector 105 through the receiving lens 103.
  • the detector 105 is, for example, a photodiode, such as an avalanche photodiode (APD), or a single photon detector (such as SiPM, Spad).
  • APD avalanche photodiode
  • SiPM SiPM, Spad
  • a compensation mirror 104 is provided in the aperture stop area of the transmitting lens 102.
  • the aperture stop area is an inherent parameter of the emitting lens (or lens group).
  • the compensation mirror 104 is configured to receive at least a part of the laser beam emitted by the laser 101 and/or the probe beam emitted from the emitting lens 102 and deflect it toward the receiving lens 103. As shown in FIG. 3, where the receiving lens 103 is juxtaposed with the transmitting lens 102 in the horizontal direction, the compensation mirror 104 deflects the detection beam toward the receiving lens 103 in a certain direction.
  • the emitting lens 102 may include a single lens, or may be a lens group composed of multiple lenses, all of which belong to the emitting lens referred to in the present invention.
  • its aperture stop area can be located on either side of the emitting lens 102 according to the optical design, such as the left or right side of the emitting lens 102 in FIG. 3, that is, the one near the laser 101.
  • the compensation mirror 104 When the compensation mirror 104 is located on the side close to the laser 101, the compensation mirror receives and deflects the laser beam emitted by the laser 101, and then shapes the probe beam through the emission lens; the compensation mirror 104 is located at a distance away from the laser 101. In the case of the side, the compensation mirror receives the probe beam and deflects it; in the case that the compensation mirror 104 is located in the middle of the transmitting lens, the compensation mirror receives and deflects the partially shaped laser beam, all of which are within the protection scope of the present invention .
  • the compensation mirror 104 includes one or more of optical wedges, microprisms, and diffractive optical elements, or a combination of them with a spherical lens or a cylindrical lens, as long as it can make the laser 101 emit At least a part of the laser beam and/or the probe beam emitted from the transmitting lens 102 may be deflected toward the receiving lens 103.
  • the compensation mirror 104 may be fixed in the aperture stop area by adhesive, a bracket, or the like.
  • a part of the emitted beam (for example, the beam emitted by a laser or the probe beam emitted by the emitting lens) is deflected to the receiving field of view of the detector at a specific angle. Therefore, the beam emitted by the compensation mirror 104 begins to overlap with the receiving field of view of the detector at a position very close to the lidar (point A in FIG. 3), thereby reducing the range of the short-distance blind zone, such as As shown in Figure 3, the range of the new blind zone is significantly smaller than the original blind zone.
  • the compensation mirror 104 is provided in the aperture stop region of the emission system.
  • the aperture stop area is an inherent parameter of the emitting lens (or lens group), and can be located on one side of the emitting lens (group) or in the middle of the emitting lens group according to the optical design of the system.
  • FIG. 4 shows a situation where multiple lasers (at different heights) are arranged on the focal plane of the emitting lens (group) 102 to emit laser light, wherein three lasers 101-1, 101-2, and 101- are schematically shown. 3.
  • the spots of multiple lasers are coincident, so only one compensation mirror 104 can be used to achieve equal proportional compensation for multiple laser beams.
  • FIG. 4 is a schematic diagram of the aperture stop area (shown by the dotted circle in Fig. 4) located on the side of the emitting lens group (the downstream side of the optical path). It can be seen from the figure that the spots of the exit beams of multiple lasers overlap in the aperture stop area.
  • the function of the compensation mirror 104 is to separate a part of the detection beam from the detection beam and let it change its direction (which can also include the change of the divergence angle), starting from a position very close to the lidar and the detector's field of view. overlap. In this way, the detector can receive the signal light reflected by the short-range target, and achieve the purpose of reducing the blind area of the lidar.
  • the compensation mirror 104 is located at a position close to the receiving lens in the area of the aperture stop.
  • 3 is a top view of the lidar 100, for example, the transmitting lens 102 and the receiving lens 103 are arranged side by side in the horizontal direction, and have substantially the same vertical height.
  • a smaller structure size can be obtained.
  • the architecture of a multi-line mechanical lidar in an embodiment of the present invention When the lidar with a folding mirror structure scans a high-reflection board (high-reflectivity obstacles, such as road signs) at a close distance, as shown in Figure 5, ghost lines will appear in the obtained lidar point cloud. That is to say, some point clouds that do not actually exist will appear on the left and right sides of the high reflector.
  • the lidar scans a high-reflectivity street sign, the ghost line generated in the lidar point cloud will be recognized as an obstacle, leading to automatic parking.
  • FIG. 6 shows a schematic diagram of the ghost line phenomenon caused by the transmitter.
  • the laser radar transmitting end since the transmittance of the coating of the transmitting lens 22 is not 100%, the laser light emitted by the laser 23 forms multiple reflections at each glass-air interface of the transmitting lens 22 and the mask 21, and then exits, and finally illuminates a short distance.
  • the target is a very large light spot. Although the energy of the light spot except the center is very low, when the reflectivity of the target is high, there is still the possibility of being detected.
  • Figure 7 shows a schematic diagram of the ghost line caused by the receiver.
  • the field of view of the lidar includes: the main field of view FOV B and the ghost line field of view FOV A, FOV C.
  • the main field of view FOV B is the field of view in which the light beam is reflected once on the first mirror 311 and the second mirror 312, and the ghost line field of view FOV A is that the light beam is not reflected on the first mirror 311 and the second mirror 312.
  • the field of view reflected on the mirror 312, and the ghost line field of view FOV C is a field of view in which the total number of reflections of the light beam on the first mirror 311 and the second mirror 312 exceeds two times.
  • the lidar scans counterclockwise, when the main field of view FOV B is still outside the high reflector, the ghost line field of view FOV A can already see the high reflector, because the distance of the high reflector Closer, the high reflection board is illuminated by a large spot at the transmitting end, so the detector 32 receives the light beam through the optical path of the ghost line field of view FOV A, which generates a ghost line on the right side of the high reflection board; The lidar continues to scan.
  • the detector 32 can still pass through the ghost The optical path of the line-of-view FOV C receives the reflected light beam of the high-reflective plate, and thus a ghost line on the left side of the high-reflective plate is generated.
  • the ghost line field of view FOV C sees the high reflector plate before the main field of view FOV B.
  • the detector 32 is, for example, Photodiodes, such as avalanche photodiodes (APD), or single photon detectors (such as SiPM, Spad).
  • APD avalanche photodiodes
  • SiPM single photon detectors
  • the present disclosure provides a receiving system that can be used for lidar, including: a receiving lens, a mirror structure, a detector, and a ghost line elimination device.
  • the reflecting mirror structure is arranged downstream of the optical path of the receiving lens
  • the detector is arranged downstream of the optical path of the reflecting mirror structure
  • the ghost line elimination device is arranged between the reflecting mirror structure and the detector .
  • the external light beam enters the reflector structure through the receiving lens, changes its propagation direction through multiple reflectors in the reflector structure, and then passes through the ghost line elimination device. Part or all of it will be in the point cloud of the lidar.
  • the light beam causing the ghost line is blocked by the ghost line elimination device, and finally the remaining light beam reaches the detector.
  • the Lidar field of view of the embodiment of the present disclosure includes: a main field of view and a ghost line field of view, the main field of view is the field of view where the light beam is reflected once on each mirror, and the ghost line field of view is that the light beam is not reflected on the mirror. And/or the field of view where the total number of reflections on the mirror exceeds the number of mirrors. Because there is a gap between the ghost line field of view and the main field of view at a specific position on the optical path, a diaphragm and/or a light barrier device can be used as the ghost line elimination device to block the ghost line
  • the optical path of the field of view realizes the suppression of ghost lines in the lidar point cloud caused by the high-reflection plate at close range.
  • FIG. 8A shows a schematic diagram of a receiving system 40 that can be used for lidar according to an embodiment of the present disclosure.
  • a receiving system 40 that can be used for lidar includes: a receiving lens 41, a mirror structure, an aperture 44, and a detector 43.
  • the mirror structure includes a first mirror 421 and a second mirror 422.
  • the receiving lens 41 can receive an external light beam, for example, a light beam reflected back by an outgoing laser beam of a lidar by an external obstacle.
  • the first reflecting mirror 421 and the second reflecting mirror 422 are arranged downstream of the optical path of the receiving lens 41, and they are arranged opposite to each other.
  • the light beam received by the receiving lens is incident on the reflecting mirror structure and passes through the first reflecting mirror 421 and The reflection of the second mirror 422 changes the propagation direction of the light beam.
  • the detector 43 is arranged downstream of the optical path of the mirror structure, and is used to receive the light beam from the mirror structure and generate an electrical signal, which undergoes further signal processing, such as filtering, amplification, AD conversion, digital signal processing, etc. , Forming the point cloud data of the lidar.
  • the diaphragm 44 is arranged between the mirror structure and the detector 43, and can allow the light of the main field of view to pass through and be incident on the detector 43, while restricting the passage of part of the light beam, for example, it can partially or completely block those Light beams that will cause ghost lines in the point cloud of the lidar are prevented from being incident on the detector.
  • the light beam corresponding to the main field of view FOV B undergoes a certain deflection after passing through the receiving lens 41, and then enters the first mirror 421 and is reflected by the first mirror 421, and then passes through the second reflection.
  • the light beam reflected by the mirror 422 and finally reflected by the second mirror 422 can pass through the diaphragm 44 and irradiate the detector 43 to generate an electric signal.
  • the light beam corresponding to the ghost line field of view FOV A after passing through the receiving lens 41, is not incident on the first reflector 421 or the second reflector 422, but directly irradiates the diaphragm 44, and is blocked by the diaphragm 44. It is blocked or absorbed to prevent it from irradiating the detector 43 and causing ghost lines to be generated in the point cloud of the lidar.
  • the light beam corresponding to the ghost line field of view FOV C passes through the receiving lens 41, is incident on the first reflector 421, is reflected by the first reflector 421 to the second reflector 422, and then is reflected by the second reflector 422 to the 421 is then reflected once by the first mirror 421 and the second mirror 422, and finally incident on the diaphragm 44, blocked or absorbed by the diaphragm 44, to prevent it from irradiating the detector 43 above and produce ghost lines in the lidar point cloud.
  • the diaphragm 44 between the mirror structure and the detector 43, as a ghost line elimination device, it is possible to at least partially block the light that will cause ghost lines in the lidar point cloud from entering the detector 43. .
  • the number of reflectors in the embodiment of FIG. 8A is two, which is only illustrative, and a larger number of reflectors may also be included.
  • the number of reflectors may also be three or Four, the present disclosure does not impose any limitation on the number of mirrors.
  • the light beams of the ghost line field of view FOV A and FOV C can be better realized.
  • the distance between the diaphragm 44 and the detector 43 (for example, a single APD, or APD linear array or area array) is h, and the distance of the diaphragm 44 is h.
  • the horizontal width of the hole is d1 (as shown in FIG. 8B), then when the horizontal width d1 of the aperture of the aperture 44 and the distance h from the aperture 44 to the detector 43 satisfy the following relationship, It is better to block the light beams of the ghost line FOV A and FOV C:
  • the lidar when the lidar scans counterclockwise or clockwise, the light beams of the ghost line field of view FOVA and FOV C are blocked by the diaphragm 44 and cannot reach the detector 43, but the main The beam of FOV B in the field of view can reach the detector 43 through the aperture of the diaphragm 44, thereby suppressing or even eliminating the ghost lines generated by the close-range high-reflection plate in the lidar point cloud, and avoiding the misidentification of the lidar , Improve detection accuracy.
  • the mirror structure may include a plurality of mirrors, and the ghost line elimination device, such as the diaphragm 44, is configured to block light beams that are not once reflected by the mirror structure.
  • the light beam reflected once by the mirror structure refers to the light beam reflected once by each mirror in the mirror structure (such as the field of view FOV B in FIG. 8A);
  • the light beam reflected once by the mirror structure means that the light beam is not reflected by at least one of the mirrors (such as the light beam corresponding to FOV A in FIG. 8A), or is reflected by at least one of the mirrors more than twice (such as FIG. 8A).
  • the light beam corresponding to the FOV C in the middle ghost line field of view ).
  • the material of the diaphragm may be metal, glass that can absorb or reflect light, or ceramic.
  • the diaphragm includes: a strip-shaped hole or a round-shaped hole.
  • FIG. 9 shows a schematic diagram of an embodiment of the strip-shaped hole diaphragm of the present disclosure
  • FIG. 10 shows a circle of the present disclosure.
  • the shape of the aperture of the diaphragm may also be square or elliptical, and the present disclosure does not impose any limitation on the shape of the aperture of the diaphragm.
  • Fig. 9 shows a schematic diagram of a strip-shaped aperture diaphragm according to an embodiment of the present disclosure.
  • the aperture of the diaphragm 52 is a strip-shaped aperture 51
  • the horizontal width of the aperture is d1
  • the diaphragm 52 is set
  • the diaphragm 52 can be attached to the support 53, which is arranged in front of the circuit board 55, and the detectors 54 can be arranged in a linear array on the circuit board 55.
  • the distance between the diaphragm 52 and the detector 54 is h. d1 and h satisfy the above-mentioned restriction relationship.
  • 6 rows of detectors 54 are provided on the circuit board 55, and correspondingly, 6 strip-shaped holes 51 are provided on the diaphragm 52 (the width of the strip-shaped holes 51 is d1, adjacent).
  • the center spacing of the shape hole 51 is set with reference to the center spacing of the adjacent detector 54 line array on the circuit board 55, and the length of the strip shape hole is also set with reference to the length of the detector 54 line array on the circuit board 55), which can block all APD array of light beams from the ghost line field of view.
  • the number of strip-shaped holes can also be adjusted as needed to block part of the APD array from the ghost line of light beams.
  • the detector 54 rotates and scans around the rotation axis of the lidar, the light beams of the ghost line field of view FOV A and FOV C are blocked by the left and right sides of the strip-shaped hole 51 of the diaphragm 52, which limits the ghost line field of view FOV A and FOV
  • the light beam of C passes, but the light beam of the main field of view FOV B can pass through the strip-shaped hole 51 of the diaphragm 52 and reach the detector 54.
  • Fig. 10 shows a schematic diagram of a circular aperture diaphragm according to an embodiment of the present disclosure.
  • the aperture of the diaphragm 62 is a circular aperture 61, and the horizontal width of the aperture is d1 (that is, the diameter of the aperture is d1)
  • the diaphragm 62 is arranged on a bracket 63, for example, the diaphragm 62 can be attached to the bracket 63, and the bracket 63 is arranged in front of the circuit board 65 and a detector located on the circuit board 65
  • the detector 64 may be, but is not limited to, a photodiode, such as APD.
  • the distance between the diaphragm 62 and the detector 64 is h.
  • each detector 64 corresponds to a circular hole 61 of the diaphragm 62.
  • the number of linear arrays (number of columns) of the detector 64 corresponds to the number of columns of the circular hole 61 of the diaphragm 62. As shown in FIG.
  • three rows of detectors 64 are provided on the circuit board 65, and Correspondingly, three rows of circular holes 61 are provided on the diaphragm 62, which can block all the light beams from the ghost line field of view of the APD array.
  • the number of circular holes can also be adjusted as needed to block part of the APD array from the ghost line of light beams.
  • the detector 64 rotates and scans around the rotation axis of the lidar, the beams of the ghost line field of view FOV A and FOV C are blocked by the circumference of the circular hole 61 of the diaphragm 62, which limits the ghost line field of view FOV A and FOV C.
  • the light beam passes, but the light beam of the main field of view FOV B can pass through the circular hole 61 of the diaphragm 62 to reach the detector 64.
  • FIG. 11 shows a schematic diagram of a receiving system 70 that can be used for lidar according to an embodiment of the present disclosure.
  • a receiving system 70 that can be used for lidar includes: a receiving lens 71, a reflecting mirror structure, a light barrier 74, and a detector 73.
  • the reflecting mirror structure includes a first reflecting mirror 721 and a second reflecting mirror 722. .
  • the receiving lens 71 can receive an external light beam, and the first reflecting mirror 721 and the second reflecting mirror 722 oppositely arranged downstream of the optical path of the receiving lens 71 can receive the light beam and change the propagation direction of the light beam through reflection,
  • the light barrier 74 arranged downstream of the optical path of the first reflector 721 and the second reflector 722 can block some or all of the light beams that may cause ghost lines in the point cloud of the lidar, and is finally set on the barrier.
  • the detector 73 downstream of the optical path of the light sheet 74 receives the light beam that is not blocked by the light barrier 74.
  • the detector 73 can rotate around the rotation axis of the lidar.
  • the number of reflectors can also be three or four, and the present disclosure does not impose any limitation on the number of reflectors.
  • the light barrier 74 can be arranged on the left and right sides of the detector 73, and can be directly arranged on the circuit board.
  • the detector 73 rotates and scans around the rotation axis of the lidar, the beams of the ghost line field of view FOV A and FOV C are blocked by the light barriers 74 on the left and right sides of the detector 73, which limits the ghost line field of view FOV A and FOV C
  • the beam of light reaches the detector 73, but the light beam of the main field of view FOV B is not blocked by the light barrier 74 and can reach the detector 73.
  • the detectors 73 can be arranged on the circuit board in a linear array or area array.
  • part of the light barriers can be multiplexed as needed to reduce the number of light barriers used, and At the same time, the effect of suppressing the ghost lines generated by the close-range high-reflection plate in the lidar point cloud can be achieved.
  • the number of light barriers in the present disclosure may be multiple, such as two, three, or four, and the present disclosure does not impose any limitation on the number of light barriers.
  • Fig. 12 shows a schematic diagram of a light barrier according to an embodiment of the present disclosure.
  • a is the front view and b is the right view.
  • the detector arrays 81, 82 and 83 are arranged on the circuit board 87, and the light shielding sheets 84, 85 and 86 are also arranged on the circuit board 87, preferably The light-shielding sheets 84, 85, and 86 are vertically arranged on the circuit board 87.
  • the detector arrays 81 and 82 share the light barrier 85, and the detector arrays 82 and 83 share the light barrier 86. While reducing the number of light barriers used, it can also achieve the effect of suppressing the occurrence of ghost lines in the lidar point cloud by the close-range high-reflection plate.
  • the focal length of the receiving lens of the receiving system is set to 69mm, the angle between the first reflector and the horizontal direction is 45 degrees, and the angle between the second reflector and the horizontal direction is 51 degrees, such as As shown in a in Figure 12, from left to right, the horizontal distances from the center of each column of APD to the light barrier are 2.45mm, 1.95mm, and 1.25mm, and from left to right, the height of the light barrier is 4mm and 4mm, respectively. , 3.2mm, can achieve a good effect of constraining the ghost line field of view.
  • the lidar system respectively includes an aperture or a light barrier as a ghost line elimination device.
  • the ghost line elimination device can also use the diaphragm and the light barrier at the same time to achieve the purpose of suppressing the ghost lines generated by the close-range high-reflection plate in the lidar point cloud.
  • the present disclosure also provides a laser radar, including: a transmitting system and the receiving system as described above.
  • the transmitting system may emit a laser beam for detecting a target, and the receiving system may receive echoes of the laser beam reflected on the target.
  • the receiving system can suppress the high-reflectivity obstacle from generating ghost lines in the lidar point cloud, avoiding the misrecognition of the lidar, and improving the detection accuracy.
  • the ghost line elimination device does not block the main field of view beam, the influence on the distance measurement capability of the lidar is minimized.
  • FIG. 13 shows a method 100 for suppressing ghost lines in a point cloud of a lidar according to an embodiment of the present disclosure. As shown in Figure 13, it specifically includes the following steps:
  • Step S101 receiving a light beam from the outside of the lidar through a receiving lens
  • Step S102 receiving the light beam from the receiving lens through the reflector structure and changing the propagation direction of the light beam through reflection
  • Step S103 blocking the light beam from the mirror structure that will cause ghost lines in the point cloud of the lidar
  • Step S104 receiving the unblocked light beam from the mirror structure through the detector.
  • the step of blocking the light beam from the mirror structure that may cause ghost lines in the point cloud of the lidar includes: blocking the light beam from the lidar by an aperture and/or a light barrier. Light beams that cause ghost lines in the point cloud.
  • the lidar receiving system of the present disclosure uses ghost line elimination devices, such as specific apertures and/or light barriers, to solve the problem of ghost lines generated by short-distance high-reflectivity obstacles in the lidar point cloud.
  • ghost line elimination devices such as specific apertures and/or light barriers.
  • Fig. 14 shows a schematic diagram of a lidar 100 according to a preferred embodiment of the present invention.
  • the laser radar 100 in addition to the laser 101, the transmitting lens 102, the receiving lens 103, the compensation mirror 104, and the detector 105, the laser radar 100 also includes a receiving end mirror structure.
  • the receiving end reflector structure includes two or more reflectors.
  • the receiving end reflector structure is arranged downstream of the optical path of the receiving lens 103, located between the receiving lens 103 and the detector 105, for receiving the echo beam condensed by the receiving lens 103, and reflected by the reflector to make it incident To the detector 105.
  • the lidar 100 further includes the ghost line elimination device between the receiving end reflector structure and the detector as described in the second aspect of the present invention to block light beams that may cause ghost lines in the point cloud of the lidar Incident on the detector.
  • the ghost line elimination device shown in FIG. 14 is the diaphragm 108.
  • the diaphragm 108 can block the light beams L1 and L3 of the ghost line field of view FOV A and FOV C from being incident on the detector 105, but does not or basically does not prevent the light beam L2 of the main field of view FOV B from being incident on the detector 105 .
  • the diaphragm and the detector satisfy the following relationship:
  • D is the diameter of the receiving lens
  • f is the focal length of the receiving lens
  • h is the distance from the diaphragm to the detector
  • d1 is the width of the diaphragm, as described with reference to FIG. 8B , I won’t repeat it here.
  • the diaphragm 108 is, for example, in the shape of a strip hole or a circular hole, and the diaphragm is made of any one of the following materials: metal, light-absorbing or light-reflecting Glass, or ceramic.
  • the ghost line eliminating device includes a light barrier. I won't repeat them here.
  • the ghost line elimination device is configured to block the light beam that is not once reflected by the receiving end reflector structure.
  • the ghost line elimination device is configured to block those that are blocked by the first mirror 107-1 and 107-2.
  • the reflecting mirror and the second reflecting mirror respectively reflect light beams other than the light beam once.
  • the angle ⁇ 1 between the beam deflected by the compensation mirror 104 and the main field of view of the lidar is smaller than the angles ⁇ 2 and ⁇ between the ghost line field of view and the main field of view. 3 .
  • the compensation mirror provided by the present invention deflects a small part of the beam.
  • the angle ⁇ 1 between the deflected beam and the main field of view of the detector is smaller than the ghost line field of view and main field of view of the mechanical radar with the double mirror folded optical path.
  • the angle between ⁇ 2 and ⁇ 3 is shown in Figure 14 (line L2 represents the beam of the detector's main field of view FOV B, and lines L1 and L3 represent the beam of ghost line field of view FOV A and FOV C), so in It is applied to lidar that eliminates the ghost line field of view through the aperture scheme, and no new ghost lines are introduced.
  • the angle ⁇ 1 between the beam deflected by the compensation mirror 104 and the main field of view of the lidar is greater than the angle ⁇ 2 or ⁇ 3 between the original ghost line field of view and the main field of view, then it will be on both sides of the deflected beam Bring new ghost lines. Setting up a compensation mirror in the lidar receiving system usually introduces new ghost lines.
  • the lidar 100 also includes a reflector structure at the transmitting end.
  • the reflector structure at the transmitting end includes at least one reflector, as shown in FIG. 14, which schematically shows two reflectors 106-1 and 106-2.
  • the reflector structure at the transmitting end may also be Including more or fewer mirrors.
  • the reflector structure at the transmitting end is arranged between the laser 101 and the transmitting lens 102, and is used to receive the laser beam emitted by the laser 101 and reflect it so that it is incident on the transmitting lens 102, is shaped and then emitted.
  • FIG. 15 shows an embodiment of the present invention.
  • the components of the lidar system in this embodiment mainly include: a laser, a transmitting lens, a compensation mirror, a receiving lens, a folding receiving end mirror structure, and a detector (such as APD) , And the compensation mirror is located at the center of the emission lens (in the area of the aperture stop), for example.
  • FIG. 16 shows another embodiment of the present invention.
  • the difference between this embodiment and FIG. 15 is that a diaphragm that blocks the ghost line field of view is added in the lidar structure.
  • the compensation mirror can be an optical wedge, a microprism, a diffractive element, or a combination of them with a spherical lens or a cylindrical lens, which can deflect a small part of the emitted light beam by a certain angle.
  • the compensation mirror can be fixed on the emitting lens by bonding, or fixed by a bracket.
  • the transmitting lens and the receiving lens are juxtaposed along the horizontal direction, and the relationship between the deflection angle of the compensation mirror and the reduction of the short-distance blind area is shown in FIG. 17.
  • the beam deflection angle in Figure 17 is ⁇ 1 ( ⁇ 1 is the angle between the beam deflected by the compensation mirror and the receiving beam (ie the main field of view beam L2)), the distance between the installation position of the compensation mirror and the center of the receiving lens is d, the receiving lens
  • the diameter of is D
  • the area where the signal is enhanced at close range the farthest from the apex of the receiving lens is L
  • the nearest is L′
  • parameters such as the installation position and deflection angle of the compensation mirror can be determined according to the closest distance L'that needs to be enhanced through the above-mentioned relational expression.
  • a light barrier can also be used to block the ghost line field of view.
  • the specific content has been clearly described in the patent before the ghost line field of view, and will not be repeated here.
  • the present invention also relates to a detection method 200 using the above-mentioned lidar 100, as shown in FIG. 18, including:
  • Step S201 emit a laser beam through the laser
  • Step S202 shaping the laser beam through the emitting lens, and emitting a probe beam
  • Step S203 deflect at least a part of the laser beam and/or the probe beam toward the receiving lens through the compensation mirror;
  • Step S204 Receive the beam of the probe beam reflected by the obstacle outside the lidar through the receiving lens.

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Abstract

一种激光雷达（100），包括：激光器（101），配置成可发出激光束；发射透镜（102），设置在激光器（101）的光路下游，配置成可将激光束整形后，出射探测光束，发射透镜（102）具有孔径光阑区域；接收透镜（103），接收透镜（103）配置成可接收探测光束在激光雷达外部被反射后的光束；和补偿镜（104），设置在发射透镜（102）的孔径光阑区域中，配置成可接收激光束和/或探测光束的至少一部分，并将其朝着接收透镜（103）偏折。

Description

激光雷达和利用其进行探测的方法 技术领域
本发明涉及光电技术领域，尤其涉及一种激光雷达以及利用该激光雷达进行探测的方法。
背景技术
激光雷达包括激光发射系统和探测接收系统，发射激光遇到目标后反射并被探测系统所接收，通过测量激光往返的时间可测量相应目标点的距离(如时间飞行法)，当对整个目标区域扫描探测后，则最终可实现三维成像。激光雷达在无人驾驶系统中有着重要应用，在该应用中需要激光雷达具有高成像帧频、高分辨率、远测距能力、小体积、高可靠性、低成本等特点。
目前，多数激光雷达发射系统和接收系统分置(区别于发射系统和接收系统共用一组镜头的情况)，为了测试远距离的目标，激光发射光束与探测器的视场是在远距离(比如200m)对准的，如图1所示，在距离激光雷达较近的某段距离范围内，激光发射光束与探测器的视场是完全没有交叠的，因此在这段距离范围，激光雷达的探测器不能接收到目标上反射的信号光，或者接收到的信号光极弱，这就是近距离盲区。
近距离盲区或激光雷达近距离信号弱的原因是收发分置的非共光路结构，即，激光发射光路和信号接收光路不是完全重合的共光路结构，参考图1，发射透镜和接收透镜之间是有水平方向的平移。申请人发现存在两种可能的原因。
第一种原因：参考图1，近距离盲区是发射的激光光束在近距离处与接收视场完全不交叠的区域。这意味着激光雷达的探测器在这个区域“看不到”发射的激光光束，也就是，探测器接收不到从这个区域的目标上反射回来的信号光。
第二种原因：参考图2，近距离盲区内有一目标，从近距离目标反射回来的信号光通过接收透镜所成的像点不在接收透镜的焦平面上，而是在焦平面之后。另外，因为近距离目标在接收透镜光轴的上方，所以它通过接收透镜所成的像点一定在接收透镜光轴的下方。综合这两方面的考虑，近距离目标反射光聚焦点与探测器的相对位置，如图2所示意。在激光雷达的近距离盲区范围内，激光雷达探测器完全接收不到目标的反射信号。
背景技术部分的内容仅仅是发明人所知晓的技术，并不当然代表本领域的现有技术。
发明内容
有鉴于现有技术的至少一个缺陷，本发明提供一种激光雷达，包括：
激光器，配置成可发出激光束；
发射透镜，设置在所述激光器的光路下游，配置成可将所述激光束整形后，出射探测光束，所述发射透镜具有孔径光阑区域；
接收透镜，所述接收透镜配置成可接收所述探测光束在激光雷达外部被反射后的光束；和
补偿镜，设置在所述发射透镜的孔径光阑区域中，配置成可接收所述激光束和/或所述探测光束的至少一部分，并将其朝着所述接收透镜偏折。
根据本发明的一个方面，所述孔径光阑区域位于所述发射透镜的靠近所述激光器的一侧、或远离所述激光器的一侧、或者所述发射透镜的中间。
根据本发明的一个方面，其中所述补偿镜包括光楔、微棱镜、衍射光学元件中的一种或多种，或者它们分别与球面透镜或柱透镜的组合，其通过粘结剂或支架被固定在所述孔径光阑区域中。
根据本发明的一个方面，其中所述补偿镜位于所述孔径光阑区域中靠近所述接收透镜的位置处。
根据本发明的一个方面，其中所述发射透镜与接收透镜沿着水平方向并置，所述补偿镜的位置满足以下关系：
Figure PCTCN2020122660-appb-000001
L′＝L-D/tanθ 1
其中θ 1为光束偏转角，经补偿镜偏折的光束与所述接收透镜接收的光束的夹角，
d为补偿镜安装位置到接收透镜中心距离，
D为接收透镜的直径，
L和L′之间的范围为近距离信号增强的区域，经补偿镜偏折的光束与接收光束的交点和接收透镜顶点的距离，最远为L，最近为L′。
根据本发明的一个方面，其中所述经补偿镜偏折的光束与激光雷达主视场之间的角度小于鬼线视场与主视场之间的角度,
其中所述激光雷达还包括依次位于所述接收透镜的光路下游的接收端反射镜结构和探测器，还包括位于所述接收端反射镜结构和探测器之间的鬼线消除装置，以阻挡会在激光雷达的点云中造成鬼线的光束入射到所述探测器。
根据本发明的一个方面，其中所述鬼线消除装置包括光阑，所述光阑和所述探测器满足以下关系：
Figure PCTCN2020122660-appb-000002
其中，D为所述接收透镜的直径，f为所述接收透镜的焦距，h为所述光阑到所述探测器的距离，d1为所述光阑的宽度。
根据本发明的一个方面，其中所述光阑为条形孔状或圆孔状，所述光阑由以下材料中的任一种制成：金属，可吸收光或反射光的玻璃，或陶瓷。
根据本发明的一个方面，其中所述鬼线消除装置包括隔光片。
根据本发明的一个方面，其中所述鬼线消除装置配置成可遮挡未经所述反射镜结构一次反射的光束。
根据本发明的一个方面，其中所述接收端反射镜结构包括相向设置的第一反射镜和第二反射镜，所述探测器包括光电二极管，所述鬼线消除装置配置成可遮挡那些被所述第一反射镜和第二反射镜分别反射一次的光束以外的其他光束。
本发明还提供一种使用如上所述的激光雷达进行探测的方法，包括：
通过所述激光器发射激光束；
通过所述发射透镜，对所述激光束进行整形，出射探测光束；
通过所述补偿镜，将所述激光束和/或所述探测光束中的至少一部分朝着所述接收透镜偏折；
通过所述接收透镜接收所述探测光束被激光雷达外部障碍物反射的光束。
通过本发明实施例的方案，能够减小收发分置激光雷达的近距离盲区范围，和/或增强近距离探测的信号强度。
附图说明
构成本发明的一部分的附图用来提供对本发明的进一步理解，本发明的示意性实施例 及其说明用于解释本发明，并不构成对本发明的不当限定。在附图中：
图1和图2示出了近距离盲区产生的可能原因的示意图；
图3示出了根据本发明一个实施例的激光雷达的示意图；
图4示出了发射透镜焦平面上多个激光器出射光束通过孔径光阑的示意图；
图5示出了根据本公开一个实施例的激光雷达点云中鬼线的示意图；
图6示出了根据本公开一个实施例的发射端导致鬼线的示意图；
图7示出了根据本公开一个实施例的接收端导致鬼线的示意图；
图8A示出了根据本公开一个实施例的光阑抑制鬼线的接收系统示意图；
图8B示出了光阑与探测器的参数示意图；
图9示出了根据本公开一个实施例的条形孔状光阑示意图；
图10示出了根据本公开一个实施例的圆孔状光阑示意图；
图11示出了根据本公开一个实施例的隔光片抑制鬼线的接收系统示意图；
图12示出了根据本公开一个实施例的隔光片示意图；
图13示出了根据本公开一个实施例的一种抑制激光雷达的点云中产生鬼线的方法；
图14示出了根据本发明一个优选实施例的激光雷达的示意图；
图15示出了根据本发明一个优选实施例的激光雷达的示意图；
图16示出了根据本发明一个优选实施例的激光雷达的示意图；
图17示出了根据本发明一个优选实施例的激光雷达的示意图；和
图18示出了根据本发明一个实施例的使用激光雷达进行探测的方法。
具体实施方式
在下文中，仅简单地描述了某些示例性实施例。正如本领域技术人员可认识到的那样，在不脱离本发明的精神或范围的情况下，可通过各种不同方式修改所描述的实施例。因此，附图和描述被认为本质上是示例性的而非限制性的。
在本发明的描述中，需要理解的是，术语"中心"、"纵向"、"横向"、"长度"、"宽度"、"厚度"、"上"、"下"、"前"、"后"、"左"、"右"、"坚直"、"水平"、"顶"、"底"、"内"、"外"、"顺时针"、"逆时针"等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本发明和简化描述，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发明的限制。此外，术语"第一"、"第二"仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有"第一"、"第二"的特征可以明示或者隐含地包括一个或者更多个所述特征。在本发明的描述中，"多个"的含义是两个或两个以上，除非另有明确具体的限定。
在本发明的描述中，需要说明的是，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:可以是机械连接，也可以是电连接或可以相互通讯；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通或两个元件的相互作用关系。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本发明中的具体含义。
在本发明中，除非另有明确的规定和限定，第一特征在第二特征之"上"或之"下"可以包括第一和第二特征直接接触，也可以包括第一和第二特征不是直接接触而是通过它们之间的另外的特征接触。而且，第一特征在第二特征"之上"、"上方"和"上面"包括第一特征在第二特征正上方和斜上方，或仅仅表示第一特征水平高度高于第二特征。第一特征在第二特征"之下"、"下方"和"下面"包括第一特征在第二特征正上方和斜上方，或仅仅表示第一特征水平高度小于第二特征。
下文的公开提供了许多不同的实施方式或例子用来实现本发明的不同结构。为了简化本发明的公开，下文中对特定例子的部件和设置进行描述。当然，它们仅仅为示例，并且目的不在于限制本发明。此外，本发明可以在不同例子中重复参考数字和/或参考字母，这种重复是为了简化和清楚的目的，其本身不指示所讨论各种实施方式和/或设置之间的关系。此外，本发明提供了的各种特定的工艺和材料的例子，但是本领域普通技术人员可以意识到其他工艺的应用和/或其他材料的使用。
以下结合附图对本发明的优选实施例进行说明，应当理解，此处所描述的优选实施例仅用于说明和解释本发明，并不用于限定本发明。
第一方面
图3示出了根据本发明一个实施例的激光雷达100的示意图。下面结合图3详细描述。如图3所示，激光雷达100包括激光器101、发射透镜102、接收透镜103、探测器105。 其中，激光器101例如为边发射激光器(EEL)或垂直腔面发射激光器(VCSEL)，配置成可发出激光束，激光束入射到光路下游的发射透镜102上。发射透镜102配置成可将所述激光束进行整形后，出射探测光束，所述发射透镜102具有孔径光阑区域。探测光束入射到激光雷达100外部的物体OB上，产生漫反射，部分反射光束返回到接收透镜103上，通过接收透镜103被会聚到探测器105上。探测器105例如为光电二极管，诸如雪崩光电二极管(APD)，或者单光子探测器(如SiPM、Spad)。探测器105在接收到反射光束后，会产生与光束的强度或者光子数目成一定关系的电信号，通过后续的电路对该电信号进行放大、滤波，从而可以获得障碍物的距离、角度、反射率等参数中的一个或多个的数据信号，从而形成激光雷达的点云数据，供后续处理使用，此处不再赘述。
另外，根据本发明的实施例，在图3中，为了减小所述激光雷达100的盲区，在所述发射透镜102的孔径光阑区域中设置有补偿镜104。孔径光阑区域为发射透镜(或透镜组)固有的参数。补偿镜104配置成可接收由激光器101发出的激光束和/或从发射透镜102出射的探测光束的至少一部分，并将其朝着所述接收透镜103偏折。如图3中所示，其中接收透镜103例如与发射透镜102在水平方向上并置，补偿镜104将探测光束朝着接收透镜103的一侧进行一定方向的偏折。
本领域技术人员容易理解，所述发射透镜102可以包括单个透镜，或者可以是由多个透镜构成的透镜组，都属于本发明中所称的发射透镜。在发射透镜102为单个透镜的情况下，其孔径光阑区域根据光学设计可位于发射透镜102的任一侧，如图3中的发射透镜102的左侧或右侧，即靠近激光器101的一侧或远离激光器101的一侧；在发射透镜102是由多个透镜构成的透镜组的情况下，其孔径光阑区域根据光学设计可以位于透镜组的任一侧，也可以位于发射透镜的中间，即位于其中两个透镜之间。在补偿镜104位于靠近激光器101一侧的情况下，补偿镜接收所述激光器101发射出的激光束并进行偏折，随后经发射透镜整形出射探测光束；在补偿镜104位于远离激光器101的一侧的情况下，补偿镜接收探测光束并进行偏折；在补偿镜104位于发射透镜中间的情况下，补偿镜接收经部分整形的激光束并进行偏折，这些都在本发明的保护范围内。
根据本发明的一个优选实施例，所述补偿镜104包括光楔、微棱镜、衍射光学元件中的一种或多种，或者它们分别与球面透镜或柱透镜的组合，只要能够使得激光器101发出的激光束和/或从发射透镜102出射的探测光束的至少一部分朝着所述接收透镜103偏折即 可。补偿镜104可以通过粘结剂、支架等被固定在所述孔径光阑区域中。
在图3的实施例中，通过在发射系统中设置补偿镜104，将发射光束的一部分(例如激光器发出的光束，或者由发射透镜出射的探测光束)以特定角度向探测器的接收视场偏斜，因此通过补偿镜104发射的光束，在距离激光雷达很近的位置处(图3中的点A)就开始与探测器的接收视场产生交叠，从而减小近距离盲区范围，如图3中所示，新盲区的范围显著小于原盲区。
上述技术方案中，在发射系统的孔径光阑区域中设置补偿镜104。孔径光阑区域为发射透镜(或透镜组)固有的参数，根据系统光学设计可以位于发射透镜(组)的某一侧，或发射透镜组的中间。图4示出了在发射透镜(组)102的焦平面上设置有多个激光器(处于不同高度)发射激光的情况，其中示意性示出了三个激光器101-1、101-2以及101-3。其中，在发射透镜的孔径光阑区域，多个激光器的光斑是重合的，因此只使用一个补偿镜104就可以实现对多个激光束的等比例补偿。图4是孔径光阑区域(如图4中虚线圆圈所示)位于发射透镜组一侧(光路下游侧)的示意图，从图中可见多个激光器的出射光束的光斑在孔径光阑区域重合。补偿镜104的作用是将探测光束的一部分，从探测光束分出来，让其改变方向(也可以包括发散角的改变)，从距离激光雷达很近的位置就开始与探测器的视场开始产生交叠。这样探测器就能接收到近距离目标反射的信号光，达到减小激光雷达近距离盲区的目的。
根据本发明的一个优选实施例，所述补偿镜104位于所述孔径光阑区域中靠近所述接收透镜的位置处。图3例如是激光雷达100的俯视图，发射透镜102与接收透镜103在水平方向上并排布置，具有大致相同的竖直高度。
第二方面
本申请要求PCT国际申请PCT/CN2019/103724的优先权，PCT国际申请PCT/CN2019/103724的内容通过引用的方式在此全部结合引入。
对于折叠反射镜结构的激光雷达(在激光雷达接收透镜和探测器之有两片以上反射镜构成反射镜结构来折叠光路)，在相同透镜焦距的情况下，能够获得更小的结构尺寸，是本发明一实施例中的多线机械激光雷达的架构。折叠反射镜结构的激光雷达，在扫描到近距 离处的高反板(高反射率障碍物，如路牌等)时，如图5所示，在得到的激光雷达点云中会出现鬼线，即在高反板的左右两侧会出现一些实际不存在的点云。在无人驾驶过程中，激光雷达扫描到高反射率的路牌时，会将其在激光雷达点云中产生的鬼线识别成障碍物，导致自动停车。
经过大量的研究以及实验，申请人发现，折叠反射镜结构的激光雷达，多种原因均可能导致鬼线的产生。图6示出了发射端的原因造成鬼线现象的示意图。在激光雷达发射端，由于发射透镜22镀膜的透过率不是100％，激光器23发射的激光在发射透镜22以及光罩21的每个玻璃—空气界面形成多次反射后出射，最终照明近距离目标的是一个非常大的光斑，虽然光斑除正中心之外的能量很低，但是当目标物的反射率很高时，仍然存在被探测到的可能性。
图7示出了接收端原因造成鬼线的示意图。在激光雷达接收端，在折叠反射镜的光路中，除了存在光束在反射镜上各反射一次的主视场之外，还存光束不在反射镜上反射的视场和在反射镜上反射总次数超过反射镜数量的视场。当激光雷达扫描时，接收端的探测器会接收到不在反射镜上反射和/或在反射镜上反射总次数超过反射镜数量的光束，因而产生了鬼线。如图7所示，激光雷达的视场包括：主视场FOV B和鬼线视场FOV A、FOV C。所述主视场FOV B为光束在第一反射镜311和第二反射镜312上各反射一次的视场，所述鬼线视场FOV A为光束未在第一反射镜311和第二反射镜312上反射的视场，所述鬼线视场FOV C为光束在第一反射镜311和第二反射镜312上反射总次数超过两次的视场。
假设激光雷达逆时针扫描，当所述主视场FOV B还在高反板外侧时，所述鬼线视场FOV A就已经能看到所述高反板了，因所述高反板距离较近，所述高反板被发射端很大的光斑照明，所以探测器32通过所述鬼线视场FOV A的光路接收到光束，产生了所述高反板右侧的鬼线；所述激光雷达继续扫描，当所述主视场FOV B离开所述高反板，所述鬼线视场FOV C仍在所述高反板上时，所述探测器32仍然可通过所述鬼线视场FOV C的光路接收到所述高反板的反射光束，因而产生了所述高反板左侧的鬼线。可替换的，所述激光雷达顺时针扫描时，所述鬼线视场FOV C先于主视场FOV B看到高反板，当所述主视场FOV B离开所述高反板，所述鬼线视场FOV A仍在所述高反板上，鬼线视场FOV A、FOV C分别导致所述高反板的右侧和左侧的鬼线，其中所述探测器32例如为光电二极管，诸如雪崩光电二极管(APD)，或者单光子探测器(如SiPM、Spad)。
为了减小或者抑制上述鬼线的问题，本公开提供一种可用于激光雷达的接收系统，包括：接收透镜、反射镜结构、探测器、鬼线消除装置。所述反射镜结构设置在所述接收透镜的光路下游，所述探测器设置在所述反射镜结构的光路下游，所述鬼线消除装置设置在所述反射镜结构和所述探测器之间。外部光束通过所述接收透镜进入所述反射镜结构，在所述反射镜结构内经过多个反射镜反射改变传播方向，再经过所述鬼线消除装置，部分或者全部会在激光雷达的点云中造成鬼线的光束被所述鬼线消除装置阻挡，最后剩余光束到达所述探测器。
本公开的实施例的激光雷达视场包括：主视场和鬼线视场，主视场为光束在每一反射镜上反射一次的视场，鬼线视场为光束未在反射镜上反射和/或在反射镜上反射总次数超过反射镜数量的视场。因为所述鬼线视场与主视场在光路上的特定位置是有间隙的，所以可通过使用光阑和/或隔光片装置作为所述鬼线消除装置，用于阻挡所述鬼线视场的光路，实现抑制近距离高反板在激光雷达点云中产生鬼线。
下面结合图8A-图10详细介绍本公开的一个实施例。
图8A示出了根据本公开一个实施例的可用于激光雷达的接收系统40的示意图。如图8A所示，可用于激光雷达的接收系统40包括：接收透镜41、反射镜结构、光阑44、探测器43，所述反射镜结构包括第一反射镜421和第二反射镜422。所述接收透镜41可接收外部光束，例如激光雷达的出射激光束经外部障碍物反射回的光束。第一反射镜421和第二反射镜422设置在所述接收透镜41的光路下游，二者相向设置，由所述接收透镜接收的所述光束入射至反射镜结构，通过第一反射镜421和第二反射镜422的反射改变所述光束的传播方向。探测器43设置在反射镜结构的光路下游，其用于接收来自反射镜结构的光束，并产生电信号，所述电信号经过进一步的信号处理，例如滤波、放大、AD转换、数字信号处理等，形成激光雷达的点云数据。光阑44设置在所述反射镜结构与探测器43之间，可允许主视场的光线穿过并入射到所述探测器43上，同时可限制部分光束通过，例如可部分或者全部阻挡那些会在激光雷达的点云中造成鬼线的光束，防止这些会造成鬼线的光束入射到所述探测器上。如图8A所示，主视场FOV B对应的光束，经过所述接收透镜41后产生一定的偏折，然后入射至第一反射镜421并被第一反射镜421反射，随后经过第二反射 镜422反射，最终经过第二反射镜422反射后的光束可穿过光阑44，照射到所述探测器43上，产生电信号。鬼线视场FOV A对应的光束，经过所述接收透镜41后，未入射到所述第一反射镜421或第二反射镜422上，而是直接照射到光阑44上，被光阑44所阻挡或吸收，避免其照射到所述探测器43上而导致在激光雷达的点云中产生鬼线。鬼线视场FOV C对应的光束经过接收透镜41后，入射到第一反射镜421上，被第一反射镜421上反射到第二反射镜422上，然后被第二反射镜422上反射至421上，随后又被所述第一反射镜421和第二反射镜422各反射一次，最终入射到所述光阑44上，被光阑44所阻挡或吸收，避免其照射到所述探测器43上而在激光雷达点云中产生鬼线。
因此，通过在所述反射镜结构与探测器43之间设置光阑44，作为鬼线消除装置，可以至少部分地阻挡那些会在激光雷达的点云中造成鬼线的光线入射到探测器43。
另外，本领域技术人员容易理解，图8A实施例中反射镜的数量为两个，这仅是示意性的，也可以包括更多数目的反射镜，例如反射镜的数量还可以为三个或者四个，本公开对于反射镜的数量不做任何限制。
根据本公开一个优选实施例，所述光阑44与所述探测器43的距离满足一定关系时，可更好地实现遮挡所述鬼线视场FOV A和FOV C的光束。
具体地，假设接收透镜41的直径为D，其焦距为f，所述光阑44到探测器43(例如单个APD，或APD线阵或面阵)的距离为h，所述光阑44的孔的水平宽度为d1(如图8B所示)，那么当所述光阑44的孔的水平宽度d1和所述光阑44到所述探测器43的距离h满足下面的关系式时，可以更好地实现遮挡所述鬼线视场FOV A和FOV C的光束：
Figure PCTCN2020122660-appb-000003
如图8A所示，当激光雷达逆时针或者顺时针扫描时，所述鬼线视场FOVA和FOV C的光束被所述光阑44阻挡，而无法到达所述探测器43，但是所述主视场FOV B的光束可通过所述光阑44的孔到达所述探测器43，进而实现了抑制甚至消除近距离高反板在激光雷达点云中产生鬼线，避免了激光雷达的误识别，提高探测准确度。
如上所述，反射镜结构可包括多个反射镜，所述鬼线消除装置例如光阑44配置成可遮挡未经所述反射镜结构一次反射的光束。本发明中，经所述反射镜结构一次反射的光束，是指经所述反射镜结构中的每一个反射镜反射一次的光束(诸如图8A中的视场FOV B)；未 经所述反射镜结构一次反射的光束，是指该光束未经其中至少一个反射镜反射(诸如图8A中鬼线视场FOV A对应的光束)，或者被其中至少一个反射镜反射两次以上(诸如图8A中鬼线视场FOV C对应的光束)。
根据本公开一个实施例的接收系统，制作所述光阑的材料可为金属、可吸收光或反射光的玻璃、或者陶瓷。
根据本公开一个实施例的接收系统，所述光阑包括：条形状孔或者圆形状孔，图9示出了本公开条形孔状光阑的实施例示意图，图10示出了本公开圆孔状光阑的实施例示意图。或者可替换的，所述光阑的孔的形状还可以是方形或者椭圆形，本公开对于光阑的孔的形状不做任何限制。
图9示出了根据本公开一个实施例的条形孔状光阑示意图,如图9所示，光阑52的孔为条形状孔51，孔的水平宽度为d1，所述光阑52设置在支架53上，例如，所述光阑52可贴置于所述支架53上，所述支架53设置在电路板55前方，所述探测器54可在所述电路板55上排列成线阵或者面阵，所述光阑52到所述探测器54的距离为h。d1和h满足如上所述限制关系，例如当我们确定了光阑的孔的水平宽度为d1后，将上述限制关系式取等号，即可确定所述光阑52到所述探测器54的距离h。所述探测器54的线阵数(列数)与所述光阑52的条形状孔的数量相对应。如图9所示，在电路板55上设置有6列探测器54，与之相对应的，在光阑52上设置有6个条形状孔51(条形状孔51的宽度为d1，相邻形状孔51的中心间距参照电路板55上相邻探测器54线阵的中心间距设定，条形状孔的长度亦参照电路板55上探测器54线阵的长度设定)，即可以遮挡所有APD列阵的来自鬼线视场的光束。当然，也可以根据需要调整条形状孔的数量，遮挡部分APD列阵的来自鬼线视场的光束。
当探测器54围绕激光雷达转轴旋转扫描时，鬼线视场FOV A和FOV C的光束被所述光阑52的条形状孔51的左右两侧阻挡，限制了鬼线视场FOV A和FOV C的光束通过，但是主视场FOV B的光束可通过所述光阑52的条形状孔51，到达所述探测器54。
图10示出了根据本公开一个实施例的圆孔状光阑示意图，如图10所示，所述光阑62的孔为圆形状孔61，孔的水平宽度为d1(即孔的直径为d1)，所述光阑62设置在支架63上，例如，所述光阑62可贴置于所述支架63上，所述支架63设置在电路板65前方，位于电路板65上的探测器64的前方，其中所述探测器64可以是但不限于是光电二极管，例 如APD。所述光阑62到所述探测器64的距离为h。d1和h满足如上所述限制关系，例如当我们确定了光阑的孔的水平宽度为d1(即孔的直径)后，将上述限制关系式取等号，即可确定所述光阑52到所述探测器54的距离h。每一探测器64对应一个所述光阑62的圆形状孔61。所述探测器64的线阵数(列数)与所述光阑62的圆形状孔61的列数相对应，如图10所示，在电路板65上设置有3列探测器64，与之相对应的，在光阑62上设置有3列圆形状孔61，可以遮挡所有APD列阵的来自鬼线视场的光束。当然，也可以根据需要调整圆形状孔的数量，遮挡部分APD列阵的来自鬼线视场的光束。
当探测器64围绕激光雷达转轴旋转扫描时，鬼线视场FOV A和FOV C的光束被所述光阑62的圆形状孔61的四周阻挡，限制了鬼线视场FOV A和FOV C的光束的通过，但是主视场FOV B的光束可通过所述光阑62的圆形状孔61，到达所述探测器64。
下面结合图11、图12详细介绍本公开的另一个实施例。
图11示出了根据本公开一个实施例的可用于激光雷达的接收系统70示意图。如图11所示，可用于激光雷达的接收系统70包括：接收透镜71、反射镜结构、隔光片74、探测器73，所述反射镜结构包括第一反射镜721和第二反射镜722。所述接收透镜71可接收外部光束，相向设置在所述接收透镜71的光路下游的第一反射镜721和第二反射镜722可接收所述光束，并通过反射改变所述光束的传播方向，设置在所述第一反射镜721和所述第二反射镜722的光路下游的隔光片74可阻挡部分或者全部会在激光雷达的点云中造成鬼线的光束，最后设置在所述隔光片74的光路下游的探测器73接收未被所述隔光片74阻挡的光束。所述探测器73可围绕激光雷达转轴进行旋转。可替换的，反射镜的数量还可以为三个或者四个，本公开对于反射镜的数量不做任何限制。
所述隔光片74可设置在所述探测器73的左右两侧，可直接设置于电路板上。当探测器73围绕激光雷达转轴旋转扫描时，鬼线视场FOV A和FOV C的光束被所述探测器73左右两侧的隔光片74阻挡，限制了鬼线视场FOV A和FOV C的光束到达所述探测器73，但是主视场FOV B的光束未被所述隔光片74阻挡，可到达所述探测器73。
所述探测器73可在所述电路板上排列成线阵或者面阵，对于多个探测器阵列的情况，可以根据需要复用部分隔光片，以减小隔光片的使用数量，且可同时达到抑制近距离高反板在激光雷达点云中产生鬼线的效果。本公开的隔光片数量可为多个，例如两个、三个、 或者四个，本公开对隔光片的数量不做任何限制。
图12示出了根据本公开一个实施例的隔光片示意图。a为主视图，b为右视图，如图12中a所示，探测器阵列81、82和83设置在电路板87上，隔光片84、85和86也设置在电路板87上，优选地所述隔光片84、85和86垂直设置在电路板87上。所述探测器阵列81和82共用所述隔光片85，所述探测器阵列82和83共用所述隔光片86。在减少了隔光片的使用数量的同时，可达到了抑制近距离高反板在激光雷达点云中产生鬼线的效果。
根据本公开一个优选实施例，设置所述接收系统的接收透镜的焦距为69mm，第一反射镜与水平方向的夹角为45度，第二反射镜与水平方向的夹角为51度，如图12中a所示，从左到右，每列APD的中心到隔光片的水平距离分别为2.45mm、1.95mm、1.25mm，从左到右，隔光片的高度分别为4mm、4mm、3.2mm时，可取得很好的约束鬼线视场的效果。
上述实施例中，激光雷达的系统分别包括光阑或者隔光片，作为鬼线消除装置。根据本公开一个实施例的接收系统，其中所述鬼线消除装置还可以同时使用光阑和隔光片，来达到抑制近距离高反板在激光雷达点云中产生鬼线的目的。
本公开还提供一种激光雷达，包括：发射系统和如上所述的接收系统。所述发射系统可发射出探测目标的激光束，所述接收系统可接收所述激光束在目标上反射后的回波。当探测的目标为近距离高反射率障碍物时，所述接收系统可抑制所述高反射率障碍物在激光雷达点云中产生鬼线，避免了激光雷达的误识别，提高探测准确度，同时由于所述鬼线消除装置不遮挡主视场光束，因此对所述激光雷达的测远能力的影响达到最小化。
图13示出了根据本公开一个实施例的一种抑制激光雷达的点云中产生鬼线的方法100。如图13所示，具体包括如下步骤：
步骤S101,通过接收透镜从激光雷达的外部接收光束；
步骤S102，通过反射镜结构，接收来自所述接收透镜的光束并通过反射改变所述光束的传播方向；
步骤S103，阻挡来自所述反射镜结构的、会在激光雷达的点云中造成鬼线的光束；
步骤S104，通过探测器接收来自所述反射镜结构的、未被阻挡得光束。
根据本公开的一个实施例，所述阻挡来自所述反射镜结构的、会在激光雷达的点云中 造成鬼线的光束的步骤包括：通过光阑和/或隔光片阻挡会在激光雷达的点云中造成鬼线的光束。
本公开的激光雷达接收系统通过使用鬼线消除装置，例如特定的光阑和/或隔光片，解决了近距离高反射率障碍物在激光雷达点云中产生鬼线，带来的激光雷达误识别的问题。在无人驾驶应用中，本公开的激光雷达扫描近距离的高反射率的路牌时，能够避免路牌在激光雷达的点云中产生鬼线，提高了探测准确度。
第三方面
本发明第一方面的增设补偿镜的技术方案可以与本发明第二方面的消除鬼线的方案相结合。
图14示出了根据本发明一个优选实施例的激光雷达100的示意图。如图14所示的，除了激光器101、发射透镜102、接收透镜103、补偿镜104、探测器105以外，激光雷达100还包括接收端反射镜结构。接收端反射镜结构包括两个或多个反射镜，图中示意性示出了两个反射镜107-1和107-2，本领域技术人员容易理解，接收端反射镜结构也可以包括数目更多的反射镜。接收端反射镜结构设置接收透镜103的光路下游，位于所述接收透镜103与所述探测器105之间，用于接收由接收透镜103会聚的回波光束，并经过反射镜反射，使其入射到探测器105上。另外，激光雷达100还包括如本发明第二方面所述的位于所述接收端反射镜结构和探测器之间的鬼线消除装置，以阻挡会在激光雷达的点云中造成鬼线的光束入射到所述探测器。图14中示出的鬼线消除装置为光阑108。光阑108能够阻挡鬼线视场FOV A和FOV C的光束L1和L3入射到所述探测器105上，但不会或基本不会阻止主视场FOV B的光束L2入射到探测器105上。
根据本发明的一个优选实施例，所述光阑和所述探测器满足以下关系：
Figure PCTCN2020122660-appb-000004
其中，D为所述接收透镜的直径，f为所述接收透镜的焦距，h为所述光阑到所述探测器的距离，d1为所述光阑的宽度，如参考图8B所描述的，此处不再赘述。
如本发明第二方面所述的，所述光阑108例如为条形孔状或圆孔状，所述光阑由以下 材料中的任一种制成：金属，可吸收光或反射光的玻璃，或陶瓷。
或者如本发明第二方面所述的，所述鬼线消除装置包括隔光片。此处不再赘述。优选的，所述鬼线消除装置配置成可遮挡未经所述接收端反射镜结构一次反射的光束。例如对于图14中所示的接收端反射镜结构包括相向设置的第一反射镜107-1和第二反射镜107-2的情况下，鬼线消除装置配置成可遮挡那些被所述第一反射镜和第二反射镜分别反射一次的光束以外的其他光束。
另外优选的，如图14所示的，所述经补偿镜104偏折的光束与激光雷达主视场之间的角度θ 1小于鬼线视场与主视场之间的角度θ 2和θ 3。
本发明设置的补偿镜，让一小部分光束产生偏折，偏折光束与探测器主视场之间的角度θ 1，小于双反射镜折叠光路的机械雷达的鬼线视场与主视场之间的角度θ 2和θ 3，如图14所示(线L2表示探测器的主视场FOV B的光束，线L1和L3表示鬼线视场FOV A和FOV C的光束)，因此在通过光阑方案消除了鬼线视场的激光雷达上面应用，不会引入新的鬼线。如若经补偿镜104偏折的光束与激光雷达主视场之间的角度θ 1大于原鬼线视场与主视场之间的角度θ 2或θ 3，那么会在偏折光束的两侧带来新的鬼线。在激光雷达接收系统设置补偿镜通常会引入新的鬼线。
另外，激光雷达100还包括发射端反射镜结构。发射端反射镜结构包括至少一个反射镜，如图14所示，图中示意性示出了两个反射镜106-1和106-2，本领域技术人员容易理解，发射端反射镜结构也可以包括数目更多或者更少的反射镜。发射端反射镜结构设置在所述激光器101与所述发射透镜102之间，用于接收激光器101出射的激光束并经过反射，使其入射到发射透镜102上，经过整形然后出射。
图15示出了本发明的一个实施例，该实施例中激光雷达系统的组件主要包括：激光器、发射透镜、补偿镜、接收透镜、折叠式的接收端反射镜结构、探测器(如APD),并且补偿镜例如位于(孔径光阑区域内)发射透镜中心的位置。
图16示出了本发明的另一个实施例，该实施例和图15的区别是激光雷达结构中增加了遮挡鬼线视场的光阑。补偿镜可以是光楔，微棱镜，衍射元件，或者它们分别与球面透镜或柱透镜的组合，能将发射光束的一小部分偏折某个特定的角度。另外，补偿镜可以通过粘结的方式固定在发射透镜上，或者通过支架的方式进行固定。
根据本发明的一个优选实施例，发射透镜与接收透镜沿着水平方向并置，补偿镜偏转角度与近距离盲区范围减小的关系如图17所示。
图17中光束偏转角为θ 1(θ 1为经补偿镜偏折的光束与接收光束〔即主视场光束L2〕的夹角)，补偿镜安装位置到接收透镜中心距离为d，接收透镜的直径为D，近距离信号增强的区域，距离接收透镜顶点最远为L，最近为L′，如图所示，那么它们之间满足下面的关系：
Figure PCTCN2020122660-appb-000005
L'＝L-D/tanθ 1
因此可以通过上述关系式，根据需要增强的最近距离L′，确定补偿镜的安装位置、偏转角等参数。
在本发明中遮挡鬼线视场同样可以采用隔光片，具体内容在鬼线视场前专利已有明确说明，此处不再赘述。
本发明还涉及一种使用如上所述的激光雷达100进行探测的方法200，如图18所示，包括：
步骤S201：通过所述激光器发射激光束；
步骤S202：通过所述发射透镜，对所述激光束进行整形，出射探测光束；
步骤S203：通过所述补偿镜，将所述激光束和/或所述探测光束中的至少一部分朝着所述接收透镜偏折；
步骤S204：通过所述接收透镜接收所述探测光束被激光雷达外部障碍物反射的光束。
以上所述仅为本发明的较佳实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。最后应说明的是：以上所述仅为本发明的优选实施例而已，并不用于限制本发明，尽管参照前述实施例对本发明进行了详细的说明，对于本领域的技术人员来说，其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (12)

  1. 一种激光雷达，包括：
    激光器，配置成可发出激光束；
    发射透镜，设置在所述激光器的光路下游，配置成可将所述激光束整形后，出射探测光束，所述发射透镜具有孔径光阑区域；
    接收透镜，所述接收透镜配置成可接收所述探测光束在激光雷达外部被反射后的光束；和
    补偿镜，设置在所述发射透镜的孔径光阑区域中，配置成可接收所述激光束和/或所述探测光束的至少一部分，并将其朝着所述接收透镜偏折。
  2. 根据权利要求1所述的激光雷达，所述孔径光阑区域位于所述发射透镜的靠近所述激光器的一侧、或远离所述激光器的一侧、或者所述发射透镜的中间。
  3. 根据权利要求1或2所述的激光雷达，其中所述补偿镜包括光楔、微棱镜、衍射光学元件中的一种或多种，或者它们分别与球面透镜或柱透镜的组合，其通过粘结剂或支架被固定在所述孔径光阑区域中。
  4. 根据权利要求1-2中任一项所述的激光雷达，其中所述补偿镜位于所述孔径光阑区域中靠近所述接收透镜的位置处。
  5. 根据权利要求4所述的激光雷达，其中所述发射透镜与接收透镜沿着水平方向并置，所述补偿镜的位置满足以下关系：
    Figure PCTCN2020122660-appb-100001
    L′＝L-D/tanθ 1
    其中θ 1为光束偏转角，经补偿镜偏折的光束与所述接收透镜接收的光束 的夹角，
    d为补偿镜安装位置到接收透镜中心距离，
    D为接收透镜的直径，
    L和L′之间的范围为近距离信号增强的区域，经补偿镜偏折的光束与接收光束的交点和接收透镜顶点的距离，最远为L，最近为L′。
  6. 根据权利要求1-2中任一项所述的激光雷达，其中所述经补偿镜偏折的光束与激光雷达主视场之间的角度小于鬼线视场与主视场之间的角度,
    其中所述激光雷达还包括依次位于所述接收透镜的光路下游的接收端反射镜结构和探测器，还包括位于所述接收端反射镜结构和探测器之间的鬼线消除装置，以阻挡会在激光雷达的点云中造成鬼线的光束入射到所述探测器。
  7. 根据权利要求6所述的激光雷达，其中所述鬼线消除装置包括光阑，所述光阑和所述探测器满足以下关系：
    Figure PCTCN2020122660-appb-100002
    其中，D为所述接收透镜的直径，f为所述接收透镜的焦距，h为所述光阑到所述探测器的距离，d1为所述光阑的宽度。
  8. 根据权利要求7所述的激光雷达，其中所述光阑为条形孔状或圆孔状，所述光阑由以下材料中的任一种制成：金属，可吸收光或反射光的玻璃，或陶瓷。
  9. 根据权利要求6所述的激光雷达，其中所述鬼线消除装置包括隔光片。
  10. 根据权利要求7或9所述的激光雷达，其中所述鬼线消除装置配置成可遮挡未经所述反射镜结构一次反射的光束。
  11. 根据权利要求7或9所述的激光雷达，其中所述接收端反射镜结构包括相向设置的第一反射镜和第二反射镜，所述探测器包括光电二极管，所述鬼线消除装置配置成可遮挡那些被所述第一反射镜和第二反射镜分别反射一次的光束以外的其他光束。
  12. 一种使用如权利要求1-11中任一项所述的激光雷达进行探测的方法，包括：
    通过所述激光器发射激光束；
    通过所述发射透镜，对所述激光束进行整形，出射探测光束；
    通过所述补偿镜，将所述激光束和/或所述探测光束中的至少一部分朝着所述接收透镜偏折；
    通过所述接收透镜接收所述探测光束被激光雷达外部障碍物反射的光束。
PCT/CN2020/122660 2019-11-01 2020-10-22 激光雷达和利用其进行探测的方法 WO2021083016A1 (zh)

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