Laser radar
By combining a polarization beam splitter and a beam adjustment device, the detection beam and the echo beam can share the same optical path, which solves the problem of large size of lidar and achieves the effects of cost reduction and size reduction.
Patent Information
- Application Number
- CN202511256158.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2020-12-11
- Publication Date
- 2025-11-21
AI Technical Summary
Existing lidar systems, while meeting the requirements for detection accuracy and range, are relatively large in size and require rational design to reduce their size.
By employing a polarization beam splitter and a beam adjustment device, the probe beam and the echo beam share the same optical path, reducing the number of optical components and achieving a polarization coaxial optical path.
While ensuring detection accuracy and range, we aim to reduce costs and decrease the size of the lidar, thereby improving detection accuracy.
Smart Images
Figure CN120993375A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of environmental perception technology, and particularly relates to a laser radar. BACKGROUND
[0002] The laser radar is an important sensor for perceiving the information around the vehicle, and is a guarantee for the safety and intelligence of the vehicle with the automatic driving function.
[0003] Since the laser radar needs to be installed on the vehicle, and the information detected by the laser radar will directly affect the safety of the vehicle driving process, the laser radar needs to meet the performance of small volume, high reliability, high imaging frame frequency, high resolution, long range, etc.
[0004] In the prior art, in order to ensure the performance of the laser radar, a large number of optical devices are arranged or a large number of laser radars are directly arranged, so that the volume of the laser radar is large, and therefore, the laser radar needs to be reasonably designed to be more miniaturized on the basis of meeting the light path transmission requirement and the detection accuracy.
[0005] Therefore, how to reduce the volume of the laser radar on the basis of the detection accuracy and the detection distance requirement of the laser radar has become a technical problem to be solved. SUMMARY
[0006] The present application provides a laser radar, which reduces the cost and the volume of the laser radar on the basis of ensuring the detection accuracy and the detection distance requirement of the laser radar.
[0007] To solve the above problems, the present application provides a laser radar, which comprises a light emitting device, a polarization light splitting device, a light beam adjusting device, a scanning device and a light receiving device, wherein:
[0008] The light emitting device is adapted to emit a detection light beam for detecting a target;
[0009] The polarization light splitting device is adapted to reflect the detection light beam and transmit a return light beam which is subjected to polarization state adjustment and focusing processing by the light beam adjusting device;
[0010] The light beam adjusting device is adapted to perform focusing processing and polarization state adjustment on the detection light beam reflected by the polarization light splitting device and the return light beam reflected by the scanning device;
[0011] The scanning device is adapted to reflect the detection light beam subjected to focusing processing and polarization state adjustment by the light beam adjusting device to scan the target, and reflect the return light beam reflected by the target;
[0012] The light receiving device is adapted to receive the return light beam transmitted by the polarization light splitting device.
[0013] Optionally, the light beam adjustment device comprises a lens and a wave plate, wherein:
[0014] the lens is adapted to focus the probe light beam reflected by the polarization light splitting device and the echo light beam whose polarization state is adjusted by the wave plate;
[0015] the wave plate is adapted to adjust the polarization state of the probe light beam focused by the lens and the echo light beam reflected by the scanning device.
[0016] Optionally, the included angle between the plane where the lens is located and the plane where the wave plate is located ranges from 3° to 15°.
[0017] Optionally, the scanning device is arranged at the front focal point of the lens.
[0018] Optionally, the light emitting device comprises a plurality of laser emitters, and the included angle between the plane where the probe light beam is located and the vertical plane ranges from 0° to 15°.
[0019] Optionally, further comprising:
[0020] a first mirror adapted to reflect the probe light beam focused and adjusted in polarization state by the light beam adjustment device to the scanning device, and to reflect the echo light beam reflected by the scanning device to the light beam adjustment device.
[0021] Optionally, the number of the light emitting device, the polarization light splitting device, the light beam adjustment device, the first mirror and the light receiving device is two, and they are symmetrically arranged about the scanning device.
[0022] Optionally, the included angle between the plane where the probe light beams reflected by the two first mirrors to the scanning device are located and the normal line of the scanning device when it is in the initial position ranges from 15° to 25°.
[0023] Optionally, the probe light beam reflected by the scanning device when it is in the initial position is parallel to the light beam propagation plane, wherein the light beam propagation plane is the plane where the probe light beam is reflected by the polarization light splitting device, focused and adjusted in polarization state by the light beam adjustment device.
[0024] Optionally, further comprising:
[0025] a second mirror adapted to reflect the probe light beam reflected by the polarization light splitting device to the light beam adjustment device, and to reflect the echo light beam focused and adjusted in polarization state by the light beam adjustment device to the polarization light splitting device.
[0026] Optionally, further comprising:
[0027] A linear polarizer is adapted to polarize the probe light beam emitted by the light emitting device and then irradiate the polarized light splitting device.
[0028] Optionally, further comprising:
[0029] An optical fiber is adapted to adjust the probe light beam emitted by the light emitting device and then irradiate the polarized light splitting device.
[0030] Optionally, further comprising:
[0031] A filter is adapted to filter the echo light beam transmitted by the polarized light splitting device and then irradiate the light receiving device.
[0032] Optionally, further comprising:
[0033] A beam expander is adapted to expand the detection range of the probe light beam reflected by the scanning device and the receiving range of the echo light beam reflected by the target.
[0034] Compared with the prior art, the technical scheme of the embodiment of the present application has the following advantages:
[0035] The laser radar provided by the embodiment of the present application comprises a light emitting device, a polarized light splitting device, a beam adjusting device, a scanning device and a light receiving device. The light emitting device emits a probe light beam for detecting a target. The polarized light splitting device reflects the probe light beam to the beam adjusting device for focus processing and polarization state adjustment, and then irradiates the scanning device. The scanning device reflects the probe light beam which has been processed by the beam adjusting device, scans the target, and reflects the echo light beam generated by the reflection of the probe light beam on the target to the beam adjusting device. The beam adjusting device further processes the echo light beam, and then irradiates the polarized light splitting device. The echo light beam transmitted by the polarized light splitting device is irradiated to the light receiving device and received by the light receiving device. It can be seen that, by using the polarized light splitting device and the beam adjusting device, the optical device used for the propagation of the probe light beam can be the same as the optical device used for the propagation of the echo light beam, so that the propagation of the probe light beam and the echo light beam can be realized simultaneously by using the same optical device, a polarized coaxial light path is realized, the used optical device is reduced, the cost is reduced on the basis of ensuring the detection accuracy and the detection distance of the laser radar, and the volume of the laser radar is reduced.
[0036] In an optional solution, the light beam adjusting device comprises a lens and a wave plate, the lens is adapted to focus the probe light beam reflected by the polarization light splitting device and the echo light beam whose polarization state is adjusted by the wave plate; and the wave plate is adapted to adjust the polarization state of the probe light beam focused by the lens and the echo light beam reflected by the scanning device. In this way, during the propagation of the probe light beam, the probe light beam reflected by the polarization light splitting device firstly undergoes the focusing treatment by the lens and then the polarization state adjustment by the wave plate, so that the stray light beam reflected by the lens surface is still a light beam without polarization state adjustment, and when the stray light beam irradiates to the polarization light splitting device, it will not be transmitted from the polarization light splitting device, so as not to affect the detection precision due to the fact that the light receiving device receives the light beam containing the stray light beam reflected by the lens surface, improve the accuracy of the laser radar detection, and the lens is arranged behind the polarization light splitting device in the propagation path of the probe light beam, so that the used devices can be reduced, and the volume of the laser radar is further reduced. BRIEF DESCRIPTION OF DRAWINGS
[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.
[0038] Figure 1 is a structural block diagram of the optical device of the laser radar provided by the embodiment of the present application;
[0039] Figure 2 is a structural schematic diagram of the optical device of the laser radar provided by the embodiment of the present application and a light path propagation schematic diagram of the probe light beam;
[0040] Figure 3 is Figure 2 is a structural schematic diagram of the optical device of the laser radar and a light path propagation schematic diagram of the echo light beam;
[0041] Figure 4 is a structural schematic diagram of the laser radar provided by the embodiment of the present application;
[0042] Figure 5 is Figure 4 is an exploded view of the laser radar;
[0043] Figure 6 is an enlarged schematic diagram of the optical fiber of the laser radar provided by the embodiment of the present application;
[0044] Figure 7 is another structural schematic diagram of the laser radar provided by the embodiment of the present application;
[0045] Figure 8 is Figure 4 a partial cross-sectional schematic view of a laser radar. DETAILED DESCRIPTION
[0046] In order to reduce the volume of the laser radar, the embodiment of the present application provides a laser radar, comprising a light emitting device, a polarization light splitting device, a light beam adjusting device, a scanning device and a light receiving device, wherein:
[0047] The light emitting device is adapted to emit a detection light beam for detecting a target;
[0048] The polarization light splitting device is adapted to reflect the detection light beam and transmit a return light beam which is subjected to polarization state adjustment and focusing processing by the light beam adjusting device;
[0049] The light beam adjusting device is adapted to perform focusing processing and polarization state adjustment on the detection light beam reflected by the polarization light splitting device and the return light beam reflected by the scanning device;
[0050] The scanning device is adapted to reflect the detection light beam subjected to focusing processing and polarization state adjustment by the light beam adjusting device to scan the target, and reflect the return light beam reflected by the target;
[0051] The light receiving device is adapted to receive the return light beam transmitted by the polarization light splitting device
[0052] Thus, when detecting the target, the light emitting device emits the detection light beam for detecting the target, the polarization light splitting device reflects the detection light beam to the light beam adjusting device for focusing processing and polarization state adjustment, and then irradiates to the scanning device, the scanning device reflects the detection light beam subjected to focusing processing and polarization state adjustment by the light beam adjusting device to scan the target, when the detection light beam irradiates to the target, the return light beam reflected by the target is irradiated to the scanning device, the scanning device reflects the return light beam to the light beam adjusting device, the light beam adjusting device further performs focusing processing and polarization state adjustment on the return light beam, and then irradiates to the polarization light splitting device, and the return light beam is transmitted by the polarization light splitting device and irradiated to the light receiving device and received by the light receiving device.
[0053] It can be seen that the laser radar provided by the embodiment of the present application uses the polarization light splitting device, so that the optical device used for the propagation of the detection light beam is the same as the optical device used for the propagation of the return light beam, so that the same optical device can be used to realize the propagation of the detection light beam and the return light beam at the same time, a polarization coaxial light path is realized, the used optical devices are reduced, the cost can be reduced on the basis of ensuring the detection precision and detection distance of the laser radar, and the volume of the laser radar can be reduced.
[0054] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.
[0055] It should be noted that the indicated orientation or position relationship involved in the present specification is based on the orientation or position relationship shown in the drawings, which is only for the convenience of description and simplification of description, and does not indicate or imply that the device must have a specific orientation or be constructed in a specific orientation, so it cannot be understood as a limitation on the present application.
[0056] Please refer to Figures 1-3 , Figure 1 is a structural diagram of an optical device of a laser radar provided by the embodiment of the present application; Figure 2 is a structural diagram of an optical device of a laser radar provided by the embodiment of the present application and a schematic diagram of light path propagation of a probe light beam; Figure 3 is Figure 2 a structural diagram of an optical device of a laser radar and a schematic diagram of light path propagation of a return light beam.
[0057] As shown in Figures 1-3 , the laser radar provided by the embodiment of the present application comprises a light emitting device 1, a polarization light splitting device 2, a light beam adjusting device 3, a scanning device 4 and a light receiving device 5, wherein: the light emitting device 1 is adapted to emit a probe light beam for detecting a target; the polarization light splitting device 2 is adapted to reflect the probe light beam and transmit a return light beam which is subjected to polarization state adjustment and focusing processing by the light beam adjusting device 3; the light beam adjusting device 3 is adapted to perform focusing processing and polarization state adjustment on the probe light beam reflected by the polarization light splitting device 2 and the return light beam reflected by the scanning device 4; the scanning device 4 is adapted to reflect the probe light beam subjected to focusing processing and polarization state adjustment by the light beam adjusting device 3 to scan the target, and reflect the return light beam reflected by the target; and the light receiving device 5 is adapted to receive the return light beam transmitted by the polarization light splitting device 2.
[0058] It should be noted that the positions of the light emitting device 1, the polarization light splitting device 2, the light beam adjusting device 3, the scanning device 4 and the light receiving device 5 are only required to satisfy the transmission requirements of the light beams, and the specific positions are not limited. Of course, in a specific embodiment, the light emitting device 1, the polarization light splitting device 2, the light beam adjusting device 3, the scanning device 4 and the light receiving device 5 can be arranged as close as possible to reduce the volume of the laser radar from the structural point of view.
[0059] In addition, the light beam adjustment device 3 can adjust the polarization state of the light beam and focus the light beam, and the number of photoelectric devices contained therein is not limited.
[0060] As shown in Figure 4 and Figure 5 , the laser radar provided by the embodiment of the present application comprises a light emitting device 1, a polarization light splitting device 2, a light beam adjustment device 3, a scanning device 4 and a light receiving device 5. Figure 4 is a structural schematic diagram of the laser radar provided by the embodiment of the present application; Figure 5 is an exploded view of the laser radar as shown in Figure 4 In addition to the light emitting device 1, the polarization light splitting device 2, the light beam adjustment device 3, the scanning device 4 and the light receiving device 5, the laser radar provided by the embodiment of the present application further comprises a mechanical structure 12 for mounting the devices (including the light emitting device 1, the polarization light splitting device 2, the light beam adjustment device 3, the scanning device 4 and the light receiving device 5), and a control device 11 for controlling and signal processing of the light emitting device 1, the light receiving device 5 and the scanning device 4, and specifically, the control device 11 can be a circuit board.
[0061] The polarization light splitting device 2 can reflect or transmit the laser beams with different polarization states, and cooperates with the polarization state adjustment of the light beam adjustment device 3 on the detection light beam and the echo light beam to ensure the realization of the polarization coaxial light path. However, the light beam will continuously diverge during the propagation, and the divergent light beam will affect the far measuring capability of the laser radar, so the light beam adjustment device 3 also needs to have the function of focusing.
[0062] Specifically, the polarization light splitting device 2 can be a polarizing beam splitter (PBS), and can also be a polarization light splitting sheet; the light emitting device 5 can be a semiconductor laser, including a vertical cavity surface emitting laser (VCSEL) or an edge emitting laser (EEL), so as to reduce the cost on the premise of ensuring the detection resolution.
[0063] Specifically, the scanning device 24 can be a galvanometer, which is driven to rotate by a driving device, so as to scan the target in the three-dimensional space by the detection light beam, and receive the echo light beam reflected by the target in the three-dimensional space.
[0064] In a specific embodiment, the light emitting device 5 can comprise a plurality of laser emitters, such as 4 or more, and the included angle between the plurality of laser emitters and the plane where the detection light beam is located and the vertical plane is 0°-15°, so as to improve the detection coverage and the detection resolution.
[0065] It is easy to understand that the plurality of laser emitters and the plane where the detection light beam is located are the planes where the laser emitters are located, and the vertical plane is a plane in the vertical plane when the laser radar is placed according to the detection position, which is parallel to the irradiation direction of the detection light beam emitted by the laser emitters.
[0066] Therefore, when conducting environmental surveys, please refer to... Figures 1-3 The light propagation path shown is such that the light emitting device 1 emits a detection beam for detecting the target, which then illuminates the polarization beam splitter 2. The polarization beam splitter 2 transmits and reflects beams with different polarization states within the detection beam, with the reflected detection beam following... Figure 1 and Figure 2 The beam, illuminating the direction of arrow A, is directed towards beam adjustment device 3 (the transmitted portion passes through polarization beam splitter 2, stopping object detection). Beam adjustment device 3 focuses and adjusts the polarization of the detection beam before directing it towards scanning device 4. Scanning device 4 reflects the beam, and the reflected beam illuminates the environment to scan the target. The target reflects the detection beam, generating an echo beam that illuminates scanning device 4. Please refer to [reference needed]. Figure 1 and 3 As shown in the optical path propagation diagram, the echo beam illuminates the beam adjustment device 3 along arrow B. The beam adjustment device 3 focuses and adjusts the polarization state of the echo beam. Thus, after the beam reflected by the polarization beam splitter 2 undergoes two polarization state adjustments, its polarization state changes. After illuminating the polarization beam splitter 2 again, it can be transmitted and illuminate the light receiving device 5.
[0067] When the beam is split using the polarization beam splitter 2, not only is part of the beam reflected to generate the detection beam, but also part of the beam is transmitted through the polarization beam splitter 1 along the beam propagation direction. In order to reduce the influence of the transmitted beam on the detection results of the lidar, in one specific embodiment, a light-absorbing device or light-absorbing material can be set in the propagation path of the transmitted beam.
[0068] Thus, the lidar provided in this embodiment of the invention, through the use of a polarization beam splitter and a beam adjustment device, allows the optical device used for the propagation of the detection beam to be the same as the optical device used for the propagation of the echo beam. This enables the simultaneous propagation of both the detection beam and the echo beam using the same optical device, achieving a polarization coaxial optical path, reducing the number of optical components used, and lowering the cost and size of the lidar while ensuring the environmental detection accuracy and detection distance requirements of the lidar.
[0069] However, in order to facilitate the setting of the scanning device 4, realize a reasonable layout of each device, improve the structural compactness of the lidar, and further reduce the size of the lidar, in another specific embodiment, the lidar provided by the present invention may also include a first reflector 6, which is suitable for reflecting the detection beam that has been focused and polarized by the beam adjustment device 3 to the scanning device 4, and reflecting the echo beam reflected by the scanning device 4 to the beam adjustment device 3.
[0070] As shown in Figures 2-5 When the first reflector 6 is arranged, the scanning device 4 can be arranged in the space above the other optical devices (the light emitting device 1, the polarization light splitting device 2, the light beam adjusting device 3 and the light receiving device 5) by properly arranging the tilt state and the tilt angle of the first reflector 6, so that the space of the laser radar can be more fully utilized, and the increase of the size of the laser radar due to the arrangement of the devices in the same plane can be avoided.
[0071] Thus, when the target is detected, the detection light beam emitted by the light emitting device 1 is irradiated to the first reflector 6 through the polarization light splitting device 2 and the light beam adjusting device 3, is reflected to the scanning device 4 through the first reflector 6, is further reflected by the scanning device 4, and the reflected scanning light beam is irradiated to the environment to scan the target. The target reflects the detection light beam to generate a return light beam, and the return light beam is irradiated to the scanning device 4, then is irradiated to the first reflector 6 through the scanning device 4, is reflected to the light beam adjusting device 3 by the first reflector 6, and is transmitted to the light receiving device 5 through the polarization light splitting device 2.
[0072] Of course, in order to further reduce the volume of the laser radar, in another embodiment, a second reflector 7 can also be arranged, which is adapted to reflect the detection light beam reflected by the polarization light splitting device 2 to the light beam adjusting device 3, and reflect the return light beam focused and processed by the light beam adjusting device 3 and adjusted in polarization state to the polarization light splitting device 2.
[0073] The arrangement of the second reflector 7 can change the transmission direction of the detection light beam and the return light beam, so that the relative position between the light beam adjusting device 3 and the polarization light splitting device 2 can be adjusted, the rationality of the arrangement of the devices in the laser radar is improved, and the compactness of the laser radar is improved, and the volume of the laser radar is further reduced.
[0074] In order to improve the quality of the light beam for detection, in another embodiment, the laser radar provided by the embodiment of the present application can further comprise a linear polarizer 8, which is adapted to polarize the detection light beam emitted by the light emitting device 1 and irradiate the polarized detection light beam to the polarization light splitting device 2.
[0075] It is easy to understand that the linear polarizer 8 first polarizes the detection light beam emitted by the light emitting device 1, and the polarized detection light beam is irradiated to the polarization light splitting device 2, so the linear polarizer 8 is arranged between the light emitting device 1 and the polarization light splitting device 2.
[0076] The arrangement of the linear polarizer 8 can polarize the light beam emitted by the light emitting device 1, and obtain a light beam perpendicular to the polarization angle of the linear polarizer 8, so as to improve the quality of the detection light beam for scanning and the detection effect.
[0077] In order to reduce the divergence angle of the probe light beam, in another embodiment, as shown in Figure 2 and Figure 6 , Figure 6 is an enlarged schematic view of the optical fiber of the laser radar provided by the embodiments of the present application. The laser radar provided by the embodiments of the present application can further include: an optical fiber 9, which is adapted to irradiate the probe light beam emitted by the light emitting device 1 to the polarization light splitting device 2 after beam adjustment.
[0078] It is easy to understand that the optical fiber 9 can also be arranged between the light emitting device 1 and the polarization light splitting device 2.
[0079] The optical fiber 9 can perform beam adjustment processing on the light beam emitted by the light emitting device 1, so as to reduce the divergence angle of the probe light beam, improve the quality of the probe light beam used for scanning, and improve the detection effect.
[0080] Of course, in another embodiment, the optical fiber 9 and the linear polarizer 8 can also be arranged at the same time, so as to achieve more comprehensive processing of the probe light beam.
[0081] In order to improve the performance of the laser radar and improve the quality of the echo light beam received by the light receiving device 5, in an embodiment, the laser radar provided by the embodiments of the present application can further include: an optical filter (not shown in the figure), which is adapted to irradiate the echo light beam transmitted by the polarization light splitting device 2 to the light receiving device 5 after filtering.
[0082] The arrangement of the optical filter can filter the light beam transmitted by the polarization light splitting device 2, so as to reduce the influence of unnecessary light beams (stray light beams) on the detection effect.
[0083] In order to further improve the detection range of the laser radar, in an embodiment, please refer to Figure 7 , Figure 7 is another structural schematic view of the laser radar provided by the embodiments of the present application. As shown in the figure, the laser radar provided by the embodiments of the present application includes a beam expander 10, which is adapted to expand the detection range of the probe light beam reflected by the scanning device 4 and the receiving range of the echo light beam reflected by the target.
[0084] Through the processing of the beam expander 10 on the probe light beam, the detection range that can be irradiated by the probe light beam is larger, and the echo light beam reflected by the target in a larger range can also be received, so as to realize the expansion of the detection range and the receiving range.
[0085] In order to improve the field of view range of the laser radar, specifically, please continue to refer to Figure 1The number of the light emitting device 1, the polarization light splitting device 2, the light beam adjusting device 3, the first mirror 6 and the light receiving device 5 of the laser radar provided by the embodiment of the present application can be two, and the two are symmetrically arranged with respect to the scanning device 4.
[0086] It should be noted that the symmetric arrangement of the scanning device 4 described herein refers to the symmetric arrangement with respect to the plane formed by the horizontal direction and the vertical direction of the center of the scanning device 4 in the direction of the outgoing detection light beam of the laser radar, i.e., the structure as shown in Figure 1 and Figure 2 .
[0087] In this way, the field of view ranges of the two sets of devices can be obtained, and a larger field of view range can be obtained through field of view splicing, thereby improving the detection range of the laser radar.
[0088] Of course, when the laser radar is also provided with the linear polarizer 8, the light ray 9 or the optical filter, the linear polarizer 8, the light ray 9 or the optical filter can also be provided with two respectively, and the two are symmetrically arranged with respect to the scanning device.
[0089] In order to ensure the effect of splicing the images corresponding to the fields of view detected by the two sets of devices, in one specific embodiment, the angle range between the plane where the detection light beams reflected by the two first mirrors 6 of the laser radar provided by the embodiment of the present application to the scanning device 4 are located and the normal line of the scanning device 4 when the scanning device 4 is in the initial position is 15°-25°.
[0090] It is easy to understand that the plane where the detection light beams reflected by the two first mirrors 6 to the scanning device 4 are located refers to the plane formed by the two detection light beams; and the initial position of the scanning device 4 refers to the position of the scanning device 4 when the scanning device 4 is not driven to rotate.
[0091] If the angle between the plane where the detection light beams reflected by the two first mirrors 6 to the scanning device 4 are located and the normal line of the scanning device 4 when the scanning device 4 is in the initial position is too large, it is easy to cause the range covered by the detection light beams to be discontinuous, and the spliced pattern to be irregular; and if the angle is too small, it is easy to cause the range covered by the detection light beams to have a high degree of overlap, and the interference between different detection light beams to affect the detection effect.
[0092] In order to enable the light beam adjusting device 3 to realize the functions of the gathering processing and the polarization state adjustment of the detection light beam and the return light beam, in one specific embodiment, please refer to Figure 8 , Figure 8 is Figure 4A partial cross-sectional schematic diagram of the laser radar is shown. The beam adjusting device 3 of the laser radar provided by the embodiment of the present application can include a lens 31 and a wave plate 32, wherein the lens 31 is adapted to focus the probe beam reflected by the polarization light splitting device 2 and the echo beam whose polarization state is adjusted by the wave plate 32; and the wave plate 32 is adapted to adjust the polarization state of the probe beam focused by the lens 31 and the echo beam reflected by the scanning device 4.
[0093] In the propagation path of the probe beam, the lens 31 is located in front of the wave plate 32, and in the propagation path of the echo beam, the lens 31 is located behind the wave plate 32.
[0094] In a specific embodiment, the wave plate 32 can be a 1 / 4 wave plate, so that the polarization direction of the beam reflected by the polarization light splitting device 2 is changed after passing through the wave plate 7, and the beam is transmitted to the light receiving device 5 after being transmitted to the polarization light splitting device 2.
[0095] In a specific embodiment, the lens 31 and the wave plate 32 can be arranged in a common mounting seat, and the fixation of the two can be achieved by arranging a spacer therebetween, and the adaptability of the lens 31 and the wave plate 32 to the environment can be improved, the risk of fragmentation can be reduced, and the reliability can be improved.
[0096] It is easy to understand that, in addition to the functions of focusing or adjusting the polarization state of the beam, each optical device such as the lens 31 and the wave plate 32 inevitably reflects the beam on the surface. In the propagation path of the probe beam, the surface of the lens 31 reflects the beam to generate a first stray beam, and the reflected beam is irradiated to the polarization light splitting device 2. Since the lens 31 is located in front of the wave plate 32, the first stray beam does not pass through the wave plate 32 for polarization state adjustment, and the reflected beam irradiated to the polarization light splitting device 2 will not be transmitted from the polarization light splitting device 2, and will not affect the beam received by the light receiving device 5.
[0097] In this way, in the propagation process of the probe beam, the probe beam reflected by the polarization light splitting device 2 first passes through the lens 31 for focusing, and then passes through the wave plate 32 for polarization state adjustment, so that the stray beam reflected by the surface of the lens 32 is still a beam without polarization state adjustment. When the stray beam is irradiated to the polarization light splitting device 2, it will not be transmitted from the polarization light splitting device 2, so as not to affect the detection accuracy due to the stray beam reflected by the surface of the lens 31 included in the beam received by the light receiving device 5, and to improve the accuracy of the laser radar detection.
[0098] However, it is easy to understand that, in order to further reduce the generation of stray light beams in the laser radar, avoid the detection light beam after the polarization state change being reflected by the surface of the wave plate 32 and being received by the light receiving device 5 through the polarization beam splitting device 2, affecting the detection accuracy of the laser radar, in a specific embodiment, the laser radar provided by the embodiment of the present application has a certain included angle between the plane where the lens 31 is located and the plane where the wave plate 32 is located, so that the stray light beam generated by the reflection of the detection light beam after the polarization state change on the surface of the wave plate 32 is deflected by a certain angle, and the deflected stray light beam will not return along the original transmission path of the detection light beam, so as not to be received by the light receiving device 5.
[0099] The included angle between the plane where the lens 31 of the laser radar is located and the plane where the wave plate 32 is located can be set, and for this purpose, the included angle range can be set to 3°-15°. For the above-mentioned included angle range, when the included angle is too large, the optical path volume will increase, and when the included angle is too small, the effect of reducing stray light will not be achieved.
[0100] It should be noted that the included angle between the plane where the lens 31 is located and the plane where the wave plate 32 is located described herein refers to the included angle between the plane where the lens 31 is located and the plane where the wave plate 32 is located, both of which are perpendicular to the base of the laser radar.
[0101] In order to further improve the detection accuracy of the laser radar, the distance between the polarization beam splitting device 2 and the light emitting device 1 and the distance between the polarization beam splitting device 2 and the light receiving device 5 can be shortened. In a specific embodiment, no lens is required to be arranged between the light emitting device 1 and the polarization beam splitting device 2 in the propagation path of the detection light beam, and no lens is required to be arranged between the light receiving device 5 and the polarization beam splitting device 2 in the propagation path of the return light beam, that is, the number of lenses along the propagation path of the detection light beam or the return light beam is one.
[0102] In this way, on the one hand, since no lens is required to be arranged between the light emitting device 1 and the polarization beam splitting device 2, the distance between the light emitting device 1 and the polarization beam splitting device 2 is short, so as to improve the alignment reliability of the polarization beam splitting device 2 and the light emitting device 1, and at the same time, no lens is required to be arranged between the light receiving device 5 and the polarization beam splitting device 2, so as to shorten the distance between the light receiving device 5 and the polarization beam splitting device 2, improve the alignment reliability of the polarization beam splitting device 2 and the light receiving device 5, and thus improve the detection accuracy; on the other hand, the number of lenses along the propagation path of the detection light beam or the return light beam is one, so as to reduce the number of optical devices used on the basis of ensuring the propagation of the light beam to the requirements of the light beam, realize the shortening of the optical path, and further improve the detection accuracy.
[0103] In addition, it should be noted that other optical devices can be set between the polarization beam splitter 2 and the light emitting device 1, as well as between the light receiving device 5 and the polarization beam splitter 2, such as the aforementioned linear polarizer 8, optical fiber 9, and filter. Even with a reduction in the number of lenses, the alignment reliability and the detection accuracy of the lidar can still be improved.
[0104] However, when the light emitting device 1 includes multiple laser emitters, the detection beams emitted by each laser emitter do not overlap due to the position of each laser emitter. This means that after the detection beams emitted by each laser emitter pass through the beam adjustment device 3, they cannot all illuminate the center of the scanning device 4, resulting in a decrease in detection accuracy. Therefore, in one specific embodiment, the scanning device 4 is positioned at the front focal point of the lens 31.
[0105] It is easy to understand that the front focal point of lens 31 mentioned in this article refers to the point where the probe beam converges after it shines on lens 31. Of course, as... Figure 1 As shown, when the scanning device 4 is positioned above the lens 31, the front focal point of the lens 31 can be located above the lens 31. That is, as the detection beam propagates after passing through the lens 31, it changes its transmission direction after passing through the first reflector 6. The point of convergence in the transmission optical path after passing through the first reflector 6 is located above the lens 31, that is, the front focal point is located above the lens 31. When setting up the scanning device 4, the scanning device 4 is positioned in the corresponding position.
[0106] By placing the scanning device 4 at the front focal point of the lens 31, a telecentric optical path is formed between the scanning device 4 and the lens 31. The detection beams emitted by each laser emitter can illuminate the center of the scanning device 4 after passing through the lens 31, thereby improving the detection accuracy of the lidar.
[0107] In another specific embodiment, in order to facilitate the design and control of the detection range, the lidar proposed in this embodiment of the invention can make the detection beam reflected by the scanning device 4 in the initial position parallel to the beam propagation plane, wherein the beam propagation plane is the plane on which the beam propagation path of the detection beam is located after being reflected by the polarization beam splitter 2, focused by the beam adjustment device 3 and adjusted by the polarization state.
[0108] This improves the accuracy of controlling the scanning angle of the scanning device and enhances the detection precision of the lidar.
[0109] While the embodiments of the present invention have been disclosed above, the present invention is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.
Claims
1. A lidar, characterized in that, It includes a light emitting device, a light receiving device, a scanning device, a first reflecting mirror, a base for the first reflecting mirror, and a base for the scanning device, wherein: The optical emitting device is adapted to emit a detection beam for detecting a target, and the optical emitting device includes a vertical cavity surface-emitting laser or a side-emitting laser; The optical receiving device is adapted to receive the echo beam reflected by the target from the detection beam; The scanning device is adapted to reflect the probe beam to scan three-dimensional space, and to receive the echo beam and guide the echo beam to the light receiving device; wherein the scanning device is mounted on the scanning device base, and the surface of the scanning device mounted on the scanning device base is inclined relative to a vertical plane; The first reflector is adapted to reflect the detection beam to the scanning device and the echo beam to the light receiving device; wherein, the lidar includes two first reflectors, the two first reflectors are mounted obliquely on the first reflector base relative to the vertical plane, the two first reflectors have an included angle, and the two first reflectors are symmetrically arranged about the scanning device; in, The scanning device is located between the light emitting device and the first reflector, and the scanning device is also located between the light receiving device and the first reflector.
2. The lidar as described in claim 1, characterized in that, The lidar also includes: The second reflector is adapted to reflect the echo beam to the light receiving device; wherein the lidar includes two second reflectors, the two second reflectors are separately arranged and symmetrically arranged with respect to the scanning device; along the propagation direction of the echo beam, the second reflector is located between the scanning device and the light receiving device.
3. The lidar as described in claim 2, characterized in that, The lidar also includes a second reflector base, on which the second reflector is mounted; the second reflector base includes a light-transmitting aperture, which is adapted to allow the detection beam and the echo beam to pass through. The echo beam reflected by the first reflector passes through the light aperture and then enters the second reflector.
4. The lidar as described in claim 1, characterized in that, The lidar also includes two light emitting devices, which are symmetrically arranged relative to the scanning device.
5. The lidar as described in claim 4, characterized in that, The lidar also includes two light receiving devices, which are symmetrically arranged relative to the scanning device.
6. The lidar as described in claim 5, characterized in that, The two optical receiving devices are arranged horizontally, and their fields of view are stitched together to expand the field of view of the lidar.
7. The lidar as described in any one of claims 1-6, characterized in that, The lidar also includes: A filter is provided to filter the echo beam before it is applied to the light receiving device.
8. The lidar as described in any one of claims 1-6, characterized in that, The scanning device includes a galvanometer and a driving device, wherein the galvanometer rotates under the drive of the driving device.
9. The lidar as described in claim 8, characterized in that, The galvanometer is located in the space above the light emitting device and the first reflector.
10. The lidar as described in any one of claims 1-6, characterized in that, The lidar also includes: A lens suitable for focusing the echo beam.