Lidar

Abstract

The application provides a laser radar, which comprises a laser transceiver module, a correction mirror and a window, the laser transceiver module is used for emitting laser and receiving reflected laser, the laser is emitted to a measured object after sequentially passing through the correction mirror and the window, and the reflected laser formed by the measured object is incident to the laser transceiver module after sequentially passing through the window and the correction mirror; wherein the correction mirror and the window constitute a 4f system, and the 4f system is used for reducing the divergence angle and spot size of the laser and reducing the signal amplitude attenuation of the reflected laser. The laser radar provided by the application reduces the divergence angle and spot size of the laser and reduces the signal amplitude attenuation of the reflected laser by constituting a 4f system with the correction mirror and the window, so as to improve the accuracy of the detection result of the laser radar.

Description

Technical Field

[0001] This application relates to the technical field of lidar, specifically to a lidar system. Background Technology

[0002] LiDAR is a commonly used ranging sensor with features such as long detection range, high resolution, and low susceptibility to environmental interference. It is widely used in fields such as intelligent robots, drones, and autonomous driving.

[0003] In related technologies, the viewing window of lidar is usually a cylindrical window. When the emitted laser passes through the cylindrical window, the divergence angle and spot size of the emitted laser will increase, resulting in inaccurate detection results of lidar. Summary of the Invention

[0004] This application provides a lidar to solve the technical problem that when the laser emitted by existing lidar passes through a cylindrical window, the divergence angle and spot size of the emitted laser increase, resulting in inaccurate detection results.

[0005] To address the aforementioned technical issues, this application provides a laser radar, comprising a laser transceiver module, a calibration mirror, and a viewing window. The laser transceiver module is used to emit laser light and receive reflected laser light. The laser light is emitted to the object under test after passing through the calibration mirror and the viewing window in sequence. The reflected laser light formed by the object under test passes through the viewing window and the calibration mirror in sequence before entering the laser transceiver module. The calibration mirror and the viewing window constitute a 4f system, which is used to reduce the divergence angle and spot size of the laser light and reduce the signal amplitude attenuation of the reflected laser light.

[0006] In one embodiment, the window has a first surface and a second surface facing away from each other, the first surface facing the object to be measured, and the first surface is cylindrical or spherical, and the second surface is spherical.

[0007] In one embodiment, the distance between the first surface and the second surface is greater than or equal to 1 mm and less than or equal to 3 mm.

[0008] In one embodiment, the focal length of the window is greater than or equal to 1000mm and less than or equal to 1200mm.

[0009] In one embodiment, the focal length of the correction lens is greater than or equal to 1100 mm and less than or equal to 1300 mm.

[0010] In one embodiment, the lidar further includes an antireflective film, a hydrophobic film, and an antifog film, wherein the antireflective film is stacked on the first surface, the hydrophobic film is stacked on the antireflective film, and the antifog film is stacked on the second surface.

[0011] In one embodiment, the lidar further includes a wedge mirror disposed in the optical path between the correction mirror and the viewing window.

[0012] In one embodiment, the lidar further includes a reflector for reflecting laser light passing through the wedge mirror to the viewing window, and the reflector is also used to reflect reflected laser light passing through the viewing window to the wedge mirror.

[0013] In one embodiment, the laser transceiver module includes a laser emitting plate, a collimating module, a transmitting reflector, and a laser receiving plate. The laser emitting plate is used to emit laser light, which is then directed to the calibration mirror after passing through the collimating module and the transmitting reflector. The laser receiving plate is used to receive reflected laser light, which is then directed to the laser receiving plate after passing through the calibration mirror and the transmitting reflector.

[0014] In one embodiment, the collimation module includes a first aperture, a fast-axis collimating lens, a slow-axis collimating lens, and a second aperture. The laser beam passes through the first aperture, the fast-axis collimating lens, the slow-axis collimating lens, and the second aperture in sequence before being directed toward the emitting reflector.

[0015] The beneficial effects of this application are: the lidar provided by this application forms a 4f system with a correction mirror and a viewing window, thereby reducing the divergence angle and spot size of the laser and reducing the signal amplitude attenuation of the reflected laser, so as to improve the accuracy of the lidar detection results. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a diagram showing the beam pattern of a lidar with a viewing window.

[0018] Figure 2 This is an image showing the beam pattern of a lidar output without a viewport.

[0019] Figure 3 The dispersion angle spectrum of the beam emitted by the LiDAR with a viewing window;

[0020] Figure 4 The dispersion angle spectrum of the beam emitted by a lidar without a viewing window;

[0021] Figure 5A diagram showing the energy distribution of reflected laser light received by a lidar with a viewport.

[0022] Figure 6 This is a diagram showing the energy distribution of reflected laser light received by a lidar without a viewport.

[0023] Figure 7 This is a schematic diagram of the optical path of a lidar in one embodiment of this application;

[0024] Figure 8 This is a dispersion angle spectrum of the laser radar beam emitted in one embodiment of this application;

[0025] Figure 9 This is an energy distribution diagram of the reflected laser received by the lidar in one embodiment of this application. Detailed Implementation

[0026] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are for illustrative purposes only and do not limit the scope of the application. Similarly, the following embodiments are only some, not all, embodiments of the present application, and all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0027] The terms "first," "second," and "third" in this application are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationships and movements between components in a specific orientation (as shown in the figures). If the specific orientation changes, the directional indications also change accordingly. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. A process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0028] In this document, the term "implementation" means that a specific feature, structure, or characteristic described in connection with an implementation may be included in at least one implementation of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same implementation, nor is it a separate or alternative implementation mutually exclusive with other implementations. It will be explicitly and implicitly understood by those skilled in the art that the implementations described herein can be combined with other implementations.

[0029] In related technologies, a lidar system includes a housing, a window, and a laser transceiver module. The window is mounted on the housing and encloses a space within it. The laser transceiver module is located within this space and is used to emit and receive reflected laser light. The laser emitted by the transceiver module passes through the window and is emitted to the object under test. The reflected laser light, formed by the object under test, passes through the window and is incident on the laser transceiver module. The lidar calculates information between the lidar and the object under test, such as the distance, azimuth, height, velocity, attitude, and even shape of the object, based on the time difference between the emitted and received laser light. The lidar window is typically cylindrical, and the cylindrical shape significantly affects the dispersion angle and spot size of the emitted laser light, as well as the signal amplitude of the reflected laser light. Figures 1 to 6 As shown, Figure 1 This is a diagram showing the beam pattern of a lidar with a viewing window. Figure 2 This is an image showing the beam pattern of a lidar output without a viewport. Figure 3 The dispersion angle spectrum of the beam emitted by the lidar with a viewing window; Figure 4 The dispersion angle spectrum of the beam emitted by a lidar without a viewing window; Figure 5 A diagram showing the energy distribution of reflected laser light received by a lidar with a viewport.

[0030] Figure 6 This is a diagram showing the energy distribution of reflected laser light received by a lidar system without a viewport. Figures 1 to 6 It is known that the presence of a cylindrical window increases the divergence angle and spot size of the emitted laser, as well as the attenuation of the reflected laser signal amplitude, thus leading to inaccurate detection results from the lidar.

[0031] To address the impact of cylindrical windows on lidar, this application provides a lidar 10, such as... Figures 7 to 9As shown, the lidar 10 includes a laser transceiver module 100, a calibration mirror 200, and a viewing window 300. The laser transceiver module 100 is used to emit laser light and receive reflected laser light. The laser light emitted by the laser transceiver module 100 passes through the calibration mirror 200 and the viewing window 300 before being emitted to the object under test. The reflected laser light formed by the object under test passes through the viewing window 300 and the calibration mirror 200 before being incident on the laser transceiver module 100. The calibration mirror 200 and the viewing window 300 constitute a 4f system, which is used to reduce the divergence angle and spot size of the laser light and enhance the signal amplitude of the reflected laser light. Compared with related technologies, the lidar 10 provided in this application reduces the divergence angle and spot size of the laser light and reduces the signal amplitude attenuation of the reflected laser light by forming a 4f system with the calibration mirror 200 and the viewing window 300, thereby improving the accuracy of the lidar 10's detection results.

[0032] Specifically, the 4F system can Figure 1 , Figure 3 and Figure 5 The output laser and reflected laser shown are optimized to be close. Figure 2 , Figure 4 and Figure 6 The emitted and reflected lasers shown are, as... Figure 8 and Figure 9 The emitted laser and reflected laser of the lidar 10 provided in this application are shown.

[0033] For example, such as Figure 7 As shown, the laser transceiver module 100 includes a laser emitting plate 110, a collimation module 120, a transmitting reflector 130, and a laser receiving plate 140. The laser emitting plate 110 emits laser light. The laser light emitted by the laser emitting plate 110 is collimated by the collimation module 120, reflected by the transmitting reflector 130, refracted by the correction mirror 200, and refracted by the viewing window 300 before being emitted to the object under test. The laser receiving plate 140 receives the reflected laser light. The reflected laser light formed by the object under test is refracted by the viewing window 300, refracted by the correction mirror 200, and transmitted by the transmitting reflector 130 before being incident on the laser receiving plate 140.

[0034] The lidar 10 calculates information between the lidar and the object under test by the time difference between the laser emitted by the laser emitter 110 and the laser receiver 140 receiving the reflected laser. This information includes parameters such as the distance, orientation, height, speed, attitude, and even shape of the object under test.

[0035] The 4f system consisting of the correction mirror 200 and the viewing window 300 can reduce the divergence angle and spot size of the laser and reduce the signal amplitude attenuation of the reflected laser, thereby improving the accuracy of the detection results of the lidar 10.

[0036] Optional, such as Figure 7 As shown, the collimation module 120 includes a first aperture 121, a fast-axis collimating lens 122, a prism 123, a slow-axis collimating lens 124, and a second aperture 125. The optical axis of the first aperture 121 coincides with the optical axis of the fast-axis collimating lens 122, and the optical axis of the slow-axis collimating lens 124 coincides with the optical axis of the second aperture 125. The laser emitted by the laser emitting plate 110 passes through the first aperture 121 for limitation, the fast-axis collimating lens 122 for collimation, the prism 123 for reflection, the slow-axis collimating lens 124 for collimation, and the second aperture 125 for limitation in sequence, and then obtains a laser beam with a beam shape and intensity distribution that meets specific requirements before being directed toward the emitting reflector 130.

[0037] Specifically, the laser emitted by the laser emitting plate 110 first passes through a first aperture stop 121 to filter out suitable lasers. The first aperture stop 121 can be an aperture stop or a field stop. When the laser filtered by the first aperture stop 121 reaches the fast-axis collimating lens 122, the fast-axis collimating lens 122 can focus the laser in the fast-axis direction to suppress the direction of the most severe laser divergence, thereby reducing the area of ​​the lens used subsequently and reducing the spot size. When the laser collimated by the fast-axis collimating lens 122 reaches the prism 123, the prism 123 reflects the laser twice to the slow-axis collimating lens 124. The function of the prism 123 is to fold the optical path so that the lidar 10 can meet the miniaturization requirements. When the laser reflected by the prism 123 reaches the slow-axis collimating lens 124, the slow-axis collimating lens 124 can focus the laser in the slow-axis direction, thereby giving the laser better linearity and reducing the spot size. The laser collimated by the slow-axis collimating lens 124 is directed to the second aperture 125, which further restricts and filters the laser to obtain a high-quality laser with a small divergence angle and a small spot size.

[0038] It should be noted that in other embodiments, the prism 123 may not be provided. The same technical effect can be achieved simply by aligning the optical axes of the first aperture 121, the fast-axis collimating lens 122, the slow-axis collimating lens 124, and the second aperture 125.

[0039] Optionally, the transmitting reflector 130 is a semi-transparent and semi-reflective mirror, used to reflect the laser that has been limited and filtered by the second aperture 125, and to transmit the reflected laser that has been transmitted by the correction mirror 200. Therefore, the transmitting optical path and the receiving optical path of the lidar 10 partially overlap, while the other part does not overlap, so that the lidar 10 can utilize laser energy more effectively and improve detection distance and accuracy.

[0040] Furthermore, the laser transceiver module 100 also includes a receiving lens 150 and a receiving reflector 160. The reflected laser light transmitted through the transmitting reflector 130 is transmitted through the receiving lens 150 and reflected by the receiving reflector 160 and then incident on the laser receiving plate 140. The function of the receiving reflector 160 is to fold the optical path so that the lidar 10 can meet the miniaturization requirements.

[0041] Optionally, the calibration mirror 200 is made of PC material, meaning it is constructed from PC and has a focal length greater than or equal to 1100mm and less than or equal to 1300mm. For example, the focal length can be 1100mm, 1120mm, 1140mm, 1160mm, 1180mm, 1200mm, 1220mm, 1240mm, 1260mm, 1280mm, or 1300mm. By adjusting the focal length of the calibration mirror 200, the 4F system can better adjust the emitted and reflected lasers, and it can also adjust the lasers emitted by different laser emitting plates 110, thereby improving the applicability of the 4F system. It should be noted that in other embodiments, the calibration mirror 200 can also be made of glass.

[0042] Optionally, the window 300 is made of PC material, meaning it is constructed from PC and has a focal length greater than or equal to 1000mm and less than or equal to 1200mm. For example, the focal length of the window 300 can be 1000mm, 1020mm, 1040mm, 1060mm, 1080mm, 1100mm, 1120mm, 1140mm, 1160mm, 1180mm, or 1200mm. By adjusting the focal length of the window 300, the 4F system can better adjust the emitted and reflected lasers, and it can also adjust the lasers emitted by different laser emitting plates 110, thereby improving the applicability of the 4F system. It should be noted that in other embodiments, the window 300 can also be made of glass.

[0043] Furthermore, the focal length of the corrector mirror 200 is greater than or equal to the focal length of the viewing window 300. For example, if the focal length of the viewing window 300 is 1150mm, then the focal length of the corrector mirror 200 needs to be greater than or equal to 1150mm and less than or equal to 1300mm. By adjusting the relationship between the focal lengths of the corrector mirror 200 and the viewing window 300, the 4F system can better adjust the emitted and reflected lasers. It is understandable that the focal lengths of the corrector mirror 200 and the viewing window 300 can be determined based on the distance between them.

[0044] Optionally, the viewing window 300 has a first surface 310 and a second surface 320 facing away from each other. The first surface 310 faces the object to be measured, and the first surface 310 is cylindrical, while the second surface 320 is spherical. That is, the viewing window 300 is a cylinder forming a receiving space, with its outer surface being cylindrical and its inner surface (the sidewall of the receiving space) being spherical. It should be noted that in other embodiments, the first surface 310 may also be spherical.

[0045] Furthermore, the lidar 10 also includes an anti-reflection film (not shown), a hydrophobic film (not shown), and an anti-fog film (not shown). The anti-reflection film is attached to the first surface 310, the hydrophobic film is attached to the anti-reflection film, and the anti-fog film is attached to the second surface 320.

[0046] Optionally, the antireflective coating may include an antireflective coating with a transmittance of greater than 99.5% for the wavelength band used by the laser, in order to improve the light output efficiency of the lidar 10.

[0047] Optionally, the hydrophobic film includes a water droplet angle greater than 100°, thereby reducing the accumulation of dust, rainwater, etc. on the viewing window 300. Without the need for windshield wipers, dust and debris will slide down the viewing window 300 on their own without accumulation, thereby reducing interference from external signals and improving the signal collection capability of the wind-measuring lidar.

[0048] Furthermore, the size of the hydrophobic membrane is larger than that of the antireflective membrane, so that the hydrophobic membrane is attached to the antireflective membrane and then covers the antireflective membrane and is attached to the first surface 310, thereby sealing the antireflective membrane to prevent water vapor from entering between the antireflective membrane and the first surface 310, and further improving the performance stability of the lidar 10.

[0049] Optionally, the anti-fog film can be a heating film. In cold weather, the anti-fog film of the lidar 10 can heat the viewing window 300 to prevent the viewing window 300 from fogging, thereby enabling the lidar 10 to have a certain active anti-interference capability to ensure the performance stability of the lidar 10 in harsh weather environments.

[0050] Optionally, the lidar 10 also includes a wedge mirror 400. The wedge mirror 400 is positioned in the optical path between the correction mirror 200 and the viewing window 300. The wedge mirror 400 is a non-power element and does not affect the 4f system formed by the correction mirror 200 and the viewing window 300. The wedge mirror 400 deflects the emitted and reflected laser beams towards the thicker side of the wedge mirror 400. By adjusting the angle and position of the wedge mirror 400, the propagation direction of the emitted and reflected laser beams can be precisely controlled to adjust and optimize the propagation path of the optical path, reduce aberrations and distortions, and further improve the accuracy of the lidar 10's detection results. Furthermore, the wedge mirror 400 can also be used to shape the laser beam transmitted through the correction mirror 200, thereby achieving precise control of the laser profile, such as shaping an elliptical laser beam into a circular laser beam to meet the needs of a specific optical system.

[0051] Furthermore, the lidar 10 also includes a reflector 500, which is disposed in the optical path between the viewing window 300 and the wedge mirror 400. The reflector 500 is used to reflect the laser light passing through the wedge mirror 400 back to the viewing window 300, and also to reflect the reflected laser light passing through the viewing window 300 back to the wedge mirror 400. The receiving reflector 160 can fold the receiving optical path so that the lidar 10 can meet the miniaturization requirements.

[0052] The above description is only a partial embodiment of this application and does not limit the scope of protection of this application. Any equivalent device or equivalent process transformation made based on the content of this application specification and drawings, or directly or indirectly applied to other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A lidar, characterized in that, The device includes a laser transceiver module, a calibration mirror, and a viewing window. The laser transceiver module is used to emit laser light and receive reflected laser light. The laser light is emitted to the object under test after passing through the calibration mirror and the viewing window in sequence. The reflected laser light formed by the object under test passes through the viewing window and the calibration mirror in sequence before entering the laser transceiver module. The correction mirror and the viewing window constitute a 4f system, which is used to reduce the divergence angle and spot size of the laser and reduce the signal amplitude attenuation of the reflected laser. The viewing window has a first surface and a second surface facing away from each other. The first surface faces the object to be measured, and the first surface is a cylindrical or spherical surface, while the second surface is a spherical surface.

2. The lidar as described in claim 1, characterized in that, The distance between the first surface and the second surface is greater than or equal to 1 mm and less than or equal to 3 mm.

3. The lidar as described in claim 2, characterized in that, The focal length of the window is greater than or equal to 1000mm and less than or equal to 1200mm.

4. The lidar as described in claim 3, characterized in that, The focal length of the correction mirror is greater than or equal to 1100mm and less than or equal to 1300mm.

5. The lidar as described in claim 1, characterized in that, The lidar also includes an anti-reflective coating, a hydrophobic coating, and an anti-fog coating. The anti-reflective coating is stacked on the first surface, the hydrophobic coating is stacked on the anti-reflective coating, and the anti-fog coating is stacked on the second surface.

6. The lidar as described in claim 1, characterized in that, The lidar also includes a wedge mirror, which is disposed in the optical path between the correction mirror and the viewing window.

7. The lidar as described in claim 6, characterized in that, The lidar also includes a reflector for reflecting laser light passing through the wedge mirror to the viewing window, and the reflector is also used to reflect reflected laser light passing through the viewing window to the wedge mirror.

8. The lidar as described in claim 1, characterized in that, The laser transceiver module includes a laser emitting plate, a collimating module, a emitting reflector, and a laser receiving plate. The laser emitting plate is used to emit laser light, which is then directed to the calibration mirror after passing through the collimating module and the emitting reflector. The laser receiving plate is used to receive reflected laser light, which is then directed to the laser receiving plate after passing through the calibration mirror and the emitting reflector.

9. The lidar as described in claim 8, characterized in that, The collimation module includes a first aperture, a fast-axis collimating lens, a slow-axis collimating lens, and a second aperture. The laser beam passes through the first aperture, the fast-axis collimating lens, the slow-axis collimating lens, and the second aperture in sequence before being directed toward the emitting reflector.

Images