Laser radar

Abstract

The invention provides a laser radar which comprises a laser receiving and transmitting module, a correction mirror and a window, the laser receiving and transmitting module is used for transmitting laser and receiving reflected laser, and the laser is transmitted to a to-be-measured object after being sequentially acted by the correction mirror and the window. Reflected laser formed by reflection of the object to be measured is incident to the laser transceiving module after being sequentially acted by the window and the correction mirror; wherein the correction mirror and the window form a 4f system, and the 4f system is used for reducing the divergence angle and the spot size of the laser and reducing the signal amplitude attenuation of the reflected laser. According to the laser radar provided by the invention, the correction mirror and the window form a 4f system, so that the divergence angle and the spot size of the laser are reduced, the signal amplitude attenuation of the reflected laser is reduced, and the accuracy of the detection result of the laser radar is improved.

Description

Technical Field

[0001] The present application relates to the technical field of laser radar, and specifically to a laser radar. Background Art

[0002] LiDAR is a commonly used ranging sensor with the characteristics of long detection distance, high resolution and little environmental interference. It is widely used in intelligent robots, drones, unmanned driving and other fields.

[0003] In related technologies, the window of a laser radar 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 become larger, resulting in inaccurate detection results of the laser radar. Summary of the Invention

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

[0005] In order to solve the above technical problems, the application provides a laser radar, including a laser transceiver module, a correction mirror and a window, wherein the laser transceiver module is used to emit laser and receive reflected laser, and the laser is emitted to the object to be measured after passing through the correction mirror and the window in turn, and the reflected laser formed by the object to be measured is incident on the laser transceiver module after passing through the window and the correction mirror in turn; wherein the correction mirror and the window constitute a 4f system, and the 4f system is used to reduce the divergence angle and spot size of the laser and reduce the signal amplitude attenuation of the reflected laser.

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

[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 viewing window is greater than or equal to 1000 mm and less than or equal to 1200 mm.

[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 laser radar further includes an anti-reflection film, a hydrophobic film and an anti-fog film, wherein the anti-reflection film is stacked on the first surface, the hydrophobic film is stacked on the anti-reflection film, and the anti-fog film is stacked on the second surface.

[0011] In one embodiment, the laser radar further includes a wedge mirror, which is arranged on the optical path between the correction mirror and the window.

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

[0013] In one embodiment, the laser transceiver module includes a laser emitting plate, a collimation module, a transmitting reflector and a laser receiving plate. The laser emitting plate is used to emit laser, and the laser passes through the collimation module and the transmitting reflector in turn and is emitted to the correction mirror; the laser receiving plate is used to receive reflected laser, and the reflected laser passes through the correction mirror and is emitted into the laser receiving plate after passing through the transmitting reflector.

[0014] In one embodiment, the collimation module includes a first aperture, a fast axis collimator, a slow axis collimator and a second aperture. The laser passes through the first aperture, the fast axis collimator, the slow axis collimator and the second aperture in sequence and then is emitted to the emitting reflector.

[0015] The beneficial effect of the present application is that the laser radar provided by the present application forms a 4f system with the correction mirror and the 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 detection results of the laser radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained from these drawings without any creative work.

[0017] Figure 1 This is the effect diagram of the light beam spot emitted by the laser radar with a window;

[0018] Figure 2 This is the effect diagram of the light beam spot emitted by the laser radar without a window;

[0019] Figure 3 This is the dispersion angle spectrum of the light beam emitted by the laser radar with a window;

[0020] Figure 4 This is the angular dispersion spectrum of the light beam emitted by the laser radar without a window;

[0021] Figure 5This is the energy distribution diagram of the reflected laser received by the laser radar with a window;

[0022] Figure 6 This is the energy distribution diagram of the reflected laser received by the laser radar without a window;

[0023] Figure 7 This is a schematic diagram of the optical path of a laser radar in one embodiment of the present application;

[0024] Figure 8 A dispersion angle spectrum diagram of a light beam emitted by a laser radar in one embodiment of the present application;

[0025] Figure 9 This is an energy distribution diagram of the reflected laser received by the laser radar in one embodiment of the present application. DETAILED DESCRIPTION

[0026] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is particularly noted that the following embodiments are only used to illustrate the present application and do not limit the scope of the present application. Similarly, the following embodiments are only some embodiments of the present application and not all embodiments. All other embodiments obtained by ordinary technicians in this field without making creative efforts 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 understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of such features. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified as optional. All directional indications in the embodiments of this application (such as up, down, left, right, front, back...) are only used to explain the relative positional relationship, movement, etc. between the components under a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. 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 that are not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0028] Reference herein to an "embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it refer to independent or alternative embodiments that are mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0029] In the related art, the laser radar includes a shell, a window and a laser transceiver module. The window is installed in the shell and enclosed with the shell to form a containing space. The laser transceiver module is set in the containing space and is used to transmit laser and receive reflected laser. The laser emitted by the laser transceiver module is emitted to the object to be measured after passing through the window. The reflected laser formed by the object to be measured is incident on the laser transceiver module after passing through the window. The laser radar calculates the information between the laser radar and the object to be measured by the time difference between emitting laser and receiving reflected laser, such as the distance, direction, height, speed, attitude, and even shape of the object to be measured. The window of the laser radar is usually a cylindrical window, and the cylindrical window has a relatively large influence on the dispersion angle and spot size of the emitted laser and the signal amplitude of the reflected laser. Figures 1 to 6 As shown, Figure 1 This is the effect diagram of the light beam spot emitted by the laser radar with a window; Figure 2 This is the effect diagram of the light beam spot emitted by the laser radar without a window; Figure 3 This is the dispersion angle spectrum of the light beam emitted by the laser radar with a window; Figure 4 This is the angular dispersion spectrum of the light beam emitted by the laser radar without a window; Figure 5 This is the energy distribution diagram of the reflected laser received by the laser radar with a window;

[0030] Figure 6 This is the energy distribution diagram of the reflected laser received by the laser radar without a window. Figures 1 to 6 It can be seen that the presence of the cylindrical window will increase the divergence angle and spot size of the emitted laser and increase the attenuation of the amplitude of the reflected laser signal, thereby resulting in inaccurate detection results of the lidar.

[0031] In order to solve the influence of the cylindrical window on the laser radar, the present application provides a laser radar 10, such as Figures 7 to 9As shown, the laser radar 10 includes a laser transceiver module 100, a correction mirror 200 and a window 300. The laser transceiver module 100 is used to transmit laser light and receive reflected laser light. The laser light emitted by the laser transceiver module 100 passes through the correction mirror 200 and the window 300 in turn and is emitted to the object to be measured. The reflected laser light formed by the object to be measured passes through the window 300 and the correction mirror 200 in turn and is incident on the laser transceiver module 100. The correction mirror 200 and the 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 the related art, the laser radar 10 provided in the present 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 correction mirror 200 and the window 300, so as to improve the accuracy of the detection result of the laser radar 10.

[0032] Specifically, the 4f system can Figure 1 、 Figure 3 and Figure 5 The outgoing laser and the reflected laser are shown to be optimally close. Figure 2 、 Figure 4 and Figure 6 The outgoing laser and the reflected laser are shown as Figure 8 and Figure 9 The outgoing laser and reflected laser of the laser radar 10 provided in this application are shown.

[0033] For example, 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 is used to emit 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 through the window 300 before being emitted to the object under test. The laser receiving plate 140 is used to receive the reflected laser light. The reflected laser light formed by the object under test is refracted by the window 300, refracted by the correction mirror 200, and transmitted through the transmitting reflector 130 before being incident on the laser receiving plate 140.

[0034] The laser radar 10 calculates the information between the laser radar and the object to be measured, such as the distance, direction, height, speed, posture, and even shape of the object to be measured, through the time difference between the laser emitting plate 110 emitting the laser and the laser receiving plate 140 receiving the reflected laser.

[0035] The 4f system formed by the correction mirror 200 and the 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 laser radar 10.

[0036] Optional, such as Figure 7 As shown, the collimation module 120 includes a first aperture 121, a fast-axis collimator 122, a prism 123, a slow-axis collimator 124, and a second aperture 125. The optical axis of the first aperture 121 coincides with the optical axis of the fast-axis collimator 122, and the optical axis of the slow-axis collimator 124 coincides with the optical axis of the second aperture 125. The laser emitted by the laser emitting plate 110 is sequentially restricted by the first aperture 121, collimated by the fast-axis collimator 122, reflected by the prism 123, collimated by the slow-axis collimator 124, and restricted by the second aperture 125 to obtain a laser beam shape and light intensity distribution that meets specific requirements, and then emitted to the emitting reflector 130.

[0037] Specifically, the laser emitted by the laser emitting plate 110 is first restricted and filtered out by the first aperture 121 to select the appropriate laser. The first aperture 121 can be an aperture aperture or a field aperture. When the laser restricted and filtered by the first aperture 121 is emitted to the fast-axis collimator 122, the fast-axis collimator 122 can focus the laser in the fast-axis direction to suppress the direction in which the laser diverges most severely, thereby reducing the lens area used subsequently and reducing the spot size. When the laser collimated by the fast-axis collimator 122 is emitted to the prism 123, the prism 123 reflects the laser twice and reflects the laser to the slow-axis collimator 124. The function of the prism 123 is to fold the optical path so that the laser radar 10 can meet the miniaturization requirements. When the laser reflected by the prism 123 is emitted to the slow-axis collimator 124, the slow-axis collimator 124 can focus the laser in the slow-axis direction, so that the laser has better linearity and reduces the spot size. The laser light collimated by the slow axis collimator 124 is emitted to the second aperture 125 , which further limits and filters the laser light to obtain a laser light with high quality, small divergence angle and small spot.

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

[0039] Optionally, the emitting reflector 130 is a semi-transparent and semi-reflective mirror, which is 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 through the correction mirror 200. Therefore, the emitting optical path and the receiving optical path of the laser radar 10 partially overlap, and the other part does not overlap, so that the laser radar 10 can more effectively utilize the laser energy and improve the 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 passing through the transmitting reflector 130 is sequentially transmitted through the receiving lens 150 and reflected by the receiving reflector 160 to be incident on the laser receiving plate 140. The function of the receiving reflector 160 is to fold the optical path so that the laser radar 10 can meet the miniaturization requirements.

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

[0042] Optionally, the window 300 is made of PC material, that is, the window 300 is made of PC material, and the focal length of the window 300 is greater than or equal to 1000 mm and less than or equal to 1200 mm. For example, the focal length of the window 300 can be 1000 mm, 1020 mm, 1040 mm, 1060 mm, 1080 mm, 1100 mm, 1120 mm, 1140 mm, 1160 mm, 1180 mm, or 1200 mm. By adjusting the focal length of the window 300, the 4f system can better adjust the emitted and reflected lasers, and can also adjust the lasers emitted by different laser emitting panels 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 correction lens 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 1150 mm, the focal length of the correction lens 200 should be greater than or equal to 1150 mm and less than or equal to 1300 mm. By adjusting the relationship between the focal lengths of the correction lens 200 and the viewing window 300, the 4f system can better adjust the transmitted and reflected laser light. It will be appreciated that the focal lengths of the correction lens 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 each other, with the first surface 310 facing the object to be measured, and the first surface 310 is a cylindrical surface, while the second surface 320 is a spherical surface. That is, the viewing window 300 is a columnar shape with a receiving space formed therein, with its outer surface being a cylindrical surface and its inner surface (the sidewall of the receiving space) being a spherical surface. It should be noted that in other embodiments, the first surface 310 may also be a spherical surface.

[0045] Furthermore, the laser radar 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 anti-reflection film includes an anti-reflection film with a transmittance greater than 99.5% for the wavelength band used by the laser, so as to improve the light output rate of the laser radar 10.

[0047] Optionally, the hydrophobic film includes a hydrophobic film with a water drop angle greater than 100°, thereby reducing the accumulation of dust, rain, etc. on the window 300. Without the need for wipers, dust and debris will slide down the window 300 by themselves and will not accumulate, thereby reducing interference from external signals and improving the ability of the wind measuring lidar to collect signals.

[0048] Furthermore, the size of the hydrophobic film is larger than the size of the anti-reflection film, so that the hydrophobic film is attached to the anti-reflection film, covers the anti-reflection film and is attached to the first surface 310, thereby sealing the anti-reflection film to prevent water vapor from entering between the anti-reflection film and the first surface 310, further improving the performance stability of the laser radar 10.

[0049] Optionally, the anti-fog film is a heating film. When the laser radar 10 is in cold weather, the anti-fog film can heat the window 300 to prevent the window 300 from fogging, thereby enabling the laser radar 10 to have a certain active anti-interference capability to ensure the performance stability of the laser radar 10 in severe weather environments.

[0050] Optionally, the laser radar 10 further includes a wedge mirror 400, which is disposed in the optical path between the correction lens 200 and the window 300. The wedge mirror 400 is an aphotic element and does not affect the 4f system formed by the correction lens 200 and the window 300. The wedge mirror 400 can deflect the transmitted and reflected laser light toward the thicker side of the wedge mirror 400. By adjusting the angle and position of the wedge mirror 400, the propagation direction of the transmitted and reflected laser light can be precisely controlled to adjust and optimize the propagation path of the optical path, reduce aberrations and distortion, and further improve the accuracy of the detection results of the laser radar 10. In addition, the wedge mirror 400 can also be used to shape the laser light passing through the correction lens 200, thereby achieving precise control of the laser profile, for example, shaping an elliptical laser light into a circular laser light to meet the requirements of a specific optical system.

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

[0052] The above description is only part of the implementation methods of the present application, and does not limit the scope of protection of the present application. Any equivalent device or equivalent process transformation made using the contents of the description and drawings of this application, or directly or indirectly used in other related technical fields, are also included in the scope of patent protection of this application.

Claims

1. A laser radar, characterized in that: The laser transceiver module comprises a laser transceiver module, a correction mirror and a window. The laser transceiver module is used to transmit laser light and receive reflected laser light. The laser light passes through the correction mirror and the window in turn and is then emitted to the object to be measured. The reflected laser light formed by the object to be measured passes through the window and the correction mirror in turn and is then incident on the laser transceiver module. The correction mirror and the window form a 4f system, and the 4f system is used to reduce the divergence angle and spot size of the laser and reduce the signal amplitude attenuation of the reflected laser.

2. The laser radar according to claim 1, wherein The viewing window has a first surface and a second surface opposite to each other, the first surface faces the object to be measured, and the first surface is a cylindrical surface or a spherical surface, and the second surface is a spherical surface.

3. The laser radar according to claim 2, wherein: A 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.

4. The laser radar according to claim 3, wherein The focal length of the window is greater than or equal to 1000 mm and less than or equal to 1200 mm.

5. The laser radar according to claim 4, wherein: The focal length of the correction mirror is greater than or equal to 1100 mm and less than or equal to 1300 mm.

6. The laser radar according to claim 2, wherein: The laser radar further includes an anti-reflection film, a hydrophobic film and an anti-fog film. The anti-reflection film is stacked on the first surface, the hydrophobic film is stacked on the anti-reflection film, and the anti-fog film is stacked on the second surface.

7. The laser radar according to claim 1, wherein The laser radar further includes a wedge mirror, which is arranged on an optical path between the correction mirror and the viewing window.

8. The laser radar according to claim 7, wherein: The laser radar further includes a reflector, which is used to reflect the laser light passing through the wedge-shaped mirror to the viewing window, and the reflector is also used to reflect the reflected laser light passing through the viewing window to the wedge-shaped mirror.

9. The laser radar according to claim 1, wherein The laser transceiver module includes a laser emitting plate, a collimation module, a transmitting reflector and a laser receiving plate. The laser emitting plate is used to emit laser, and the laser passes through the collimation module and the transmitting reflector in turn and is emitted to the correction mirror; the laser receiving plate is used to receive the reflected laser, and the reflected laser passes through the correction mirror and is emitted into the laser receiving plate after passing through the transmitting reflector.

10. The laser radar according to claim 9, wherein: The collimation module includes a first aperture, a fast axis collimator, a slow axis collimator and a second aperture. The laser is sequentially directed to the emitting reflector after passing through the first aperture, the fast axis collimator, the slow axis collimator and the second aperture.

Images