Window for lidar and lidar

Abstract

A window for a laser radar and the laser radar, the laser radar comprising: a transceiver module and a scanning device; wherein the probe light generated by the transceiver module is deflected by the scanning device to form the emission light; the emission light transmits through the window and is emitted to the three-dimensional space; the emitted emission light is reflected by the target object to form the echo light; the echo light transmits through the window and is deflected by the scanning device to be collected by the transceiver module; the window comprises an attenuation part, and the attenuation part attenuates the stray light formed by the reflection of the emission light. The attenuation part of the window makes the stray light formed by the reflection of the emission light to be divergent or convergent after divergence to achieve attenuation, which can effectively overcome the noise problem, and further can effectively suppress the crosstalk phenomenon of the laser radar and improve the signal-to-noise ratio.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of laser detection, in particular to a window for a laser radar and the laser radar. BACKGROUND

[0002] The laser radar is a commonly used ranging sensor, which has the characteristics of long detection distance, high resolution, small environmental interference, etc., and is widely used in intelligent robots, unmanned aerial vehicles, unmanned driving and other fields. In recent years, the automatic driving technology has developed rapidly, and the laser radar, as the core sensor for distance perception, has become indispensable.

[0003] According to the layout mode of the emission light path and the receiving light path, the laser radar can be divided into non-coaxial transmission and reception and coaxial transmission and reception. The emission light path and the receiving light path of the non-coaxial transmission and reception are independent of each other, and are usually realized by different mirror groups, which respectively undertake the functions of laser emission and reception. The emission light path and the receiving light path of the coaxial transmission and reception share the same optical axis, and often share a transmission and reception mirror group, and the separation and combination of the emission beam and the receiving beam are realized by a splitting element (such as a beam splitter, a pinhole mirror, etc.).

[0004] As is known to all, the light beam will always reflect and / or transmit when passing through the surface of an optical device. When the window material of the laser radar reaches a certain reflectivity, the laser beam will be reflected multiple times inside the laser radar during transmission through the window, thereby forming multiple exit spots, and then easily forming noise points on the point cloud.

[0005] Specifically, the emission light beam generated by the emission device is reflected by the mirror and projected onto the window. The emission light beam is reflected and transmitted on the window, the transmitted light beam forms an exit main light beam exiting from the window, and the reflected light beam forms a stray light beam which, after being reflected by the mirror again, exits from another position of the window. The exit main light beam exiting from the window is reflected by the target object to form a return main light beam, and the stray light beam exiting from the other position of the window is reflected by another target object to form a stray return light beam. The return main light beam and the stray light beam are reflected by the mirror and can be received by the receiving device.

[0006] When the laser radar adopts a planar window, i.e. the shape of the window is a flat plate, the reflection angle of the window is fixed, i.e. the angle between the emission light beam and the stray light beam is fixed. Therefore, for the exit main light beam and the stray light beam formed by the same emission light beam, the return main light beam and the stray return light beam have the same path after being reflected by the mirror when received, i.e. the return main light beam and the stray return light beam are received by the same receiving device, thereby causing noise points on the point cloud.

[0007] When the laser radar utilizes non-coaxial optical path and rotating mirror, the transmitting device and the receiving device are separated up and down, so the transmitting beam generated by the transmitting device and the echo beam received by the receiving device are separated, that is, the transmission paths of the two beams are not the same.

[0008] However, the non-coaxial transmitting and receiving often cause the laser radar to have a large volume and an uncompact structure due to the need to have independent transmitting and receiving modules. In addition, the non-coaxial transmitting and receiving also have the problems of complex assembly and high cost. To avoid the noise points on the point cloud, another method is to use a special-shaped window with an asymmetric structure in the upper and lower parts. As shown in Figure 1 , the upper and lower part structures of the window are optimized to form a certain angle, so that the transmission paths of the echo main beam and the stray echo beam are different, so that the stray beam is not received by the same receiving device after being reflected by the rotating mirror, thereby avoiding the formation of noise points on the point cloud.

[0009] When the laser radar utilizes coaxial transmitting and receiving and rotating mirror (mirror in the figure), even if the planar window is changed to a special-shaped window (as shown in Figure 1 ), that is, the upper and lower parts of the window form a certain angle, it will not change the noise point problem formed by the secondary reflection of the stray light through the window. This is because, when the laser radar adopts the coaxial transmitting and receiving scheme (as shown in Figure 2 ), the transmission paths of the transmitting beam 41a and the echo beam 43a are partially the same. The spots formed by the transmitting beam 41a and the echo beam 43a on the window partially overlap, so even if the window only has a certain angle in the upper and lower parts, the main beam and the stray beam still have the same path when received.

[0010] As shown in Figure 3 , in the scheme in which the laser radar adopts the rotating mirror 52, the secondary reflection between the window 53 and the rotating mirror 52 usually causes a target 50a located in one direction to form a false point 50c, that is, a noise point, in the direction of another target 50b at some angles.

[0011] Specifically, the signal detection capability of the noise point formed by the secondary reflection (coaxial transmitting and receiving device 51-rotating mirror 52-window 53-rotating mirror 52-window 53-target 50a) is about ρ 2 times of the main beam, where ρ is the reflectivity of the window, which is generally 2%-10%. For example, the reflectivity of a PC material window is 10%, and the reflectivity of a glass material window is 5%.

[0012] It can be seen that in the non-coaxial scheme, the angle between the corresponding windows of the transmitting module and the receiving module can be used to solve the problem, but in the coaxial scheme, this scheme does not work, that is, the existing laser radar that adopts coaxial transmitting and receiving has the problems of serious crosstalk, poor signal-to-noise ratio, and easy formation of noise points on the point cloud. SUMMARY

[0013] The problem solved by the present application is to provide a window for a laser radar and a laser radar to reduce crosstalk, improve signal-to-noise ratio and solve noise problem.

[0014] To solve the above problem, the present application provides a window for a laser radar, comprising:

[0015] The laser radar comprises a transceiver module and a scanning device; wherein the detection light generated by the transceiver module is deflected by the scanning device to form emission light; the emission light is transmitted through the window to exit into a three-dimensional space; the emitted emission light is reflected by a target object to form echo light; the echo light is transmitted through the window and deflected by the scanning device to be collected by the transceiver module; the window comprises an attenuation part, which attenuates the stray light formed by the reflection of the emission light.

[0016] Optionally, the attenuation part is curved.

[0017] Optionally, the curved shape is convex towards the outside space of the laser radar, and the stray light formed by the reflection of the emission light by the attenuation part is divergent after convergence to achieve attenuation.

[0018] Optionally, the curved shape is convex away from the inside space of the laser radar, and the stray light formed by the reflection of the emission light by the attenuation part is divergent to achieve attenuation.

[0019] Optionally, the stray light is transmitted through the window to exit into a three-dimensional space after being reflected by the scanning device; the emitted stray light is reflected by a target object to form stray echo light; the stray echo light is transmitted through the window and reflected by the scanning device to the attenuation part to achieve attenuation.

[0020] Optionally, the window further comprises a non-attenuation part, and the shape of the non-attenuation part is different from that of the attenuation part.

[0021] Optionally, the shape of the non-attenuation part is a flat plate or a curved shape convex towards the outside of the laser radar.

[0022] Optionally, the laser radar further comprises an optical system suitable for collimating the emission light; the smaller the focal length of the optical system, the greater the radius of curvature of the attenuation part.

[0023] Optionally, the radius of curvature of the attenuation part is in the range of 150mm to 400mm.

[0024] Optionally, the tangent plane at the position of the light spot of the emission light projected onto the attenuation part is oblique to the direction vector of the emission light.

[0025] Optionally, the field of view angle of the laser radar is 2θ; an included angle between a tangent plane of a position where a light spot of the emitted light is projected on the attenuation part and a normal plane of an optical axis of the laser radar is w; and w>θ.

[0026] Optionally, the material of the window is PC material.

[0027] Optionally, the window and the shell of the laser radar are fixed by screws; the screws pass through the bottom surface of the shell of the laser radar and are fixed on the shell of the laser radar on both sides of the window.

[0028] Correspondingly, the application further provides a laser radar, comprising: a transceiver module, the emitting module is suitable for generating probe light and is also suitable for collecting the echo light; a scanning device, the scanning device is suitable for deflecting the probe light generated by the transceiver module; and a window, the window is the window of the application.

[0029] Optionally, the scanning device comprises one of a rotating mirror and a vibrating mirror.

[0030] Optionally, the part of the light path of the transceiver module for generating probe light and the part of the light path of the transceiver module for collecting the echo light are on the same optical axis.

[0031] Compared with the prior art, the technical scheme of the application has the following advantages:

[0032] In the technical scheme of the application, the attenuation part of the window makes the stray light formed after the reflection of the emitted light to be divergent or convergent to achieve attenuation, which can effectively overcome the noise problem and further effectively suppress the crosstalk phenomenon of the laser radar and improve the signal-to-noise ratio.

[0033] In the optional scheme of the application, the stray light is transmitted to the three-dimensional space through the window after being reflected by the scanning device; the stray echo light is formed after the stray light is reflected by a target object; and the stray echo light is reflected to the attenuation part by the scanning device after being transmitted through the window to achieve attenuation. The attenuation part can also effectively improve the secondary reflection of the window on the light, further reduce the noise on the point cloud, and improve the interference problem of the laser radar signal.

[0034] In the optional scheme of the application, the window further comprises a non-attenuation part in the form of a flat plate or a curved shape protruding outward of the laser radar. The non-attenuation part in the form of a flat plate or a curved shape protruding outward of the laser radar can ensure the size of the internal space of the laser radar.

[0035] In an optional embodiment of the present invention, the lidar further includes an optical system adapted to collimate the emitted light; the smaller the focal length of the optical system, the larger the radius of curvature of the attenuation section. The radius of curvature of the attenuation section is adapted to the focal length of the optical system, thereby ensuring the ranging capability of the lidar while overcoming stray light interference.

[0036] In an optional embodiment of the present invention, the window is fixed to the housing of the lidar by screws; the screws pass through the bottom surface of the lidar housing and are fixedly connected to the lidar housing on both sides of the window. Compared with the glue fixing method, fixing the window with screws is more secure, more reliable, and easier to disassemble. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the optical path structure of a lidar that uses an irregularly shaped window;

[0038] Figure 2 This is a schematic diagram of the optical path structure of a lidar that uses coaxial transceiver.

[0039] Figure 3 This is a schematic diagram of the optical path structure for noise generation in a lidar system that uses coaxial transceiver.

[0040] Figure 4 This is a schematic diagram of the structure of a window for lidar according to an embodiment of the present invention;

[0041] Figure 5 yes Figure 4 The diagram shows the relationship between the field of view and the focal length of the optical system in a lidar system using a windowed embodiment.

[0042] Figure 6 yes Figure 4 The diagram shows a structural schematic of the tilt angle of the window in a lidar system using a window embodiment.

[0043] Figure 7 yes Figure 4 A schematic diagram of the three-dimensional structure of the window in the lidar shown;

[0044] Figure 8 yes Figure 4 The diagram shows the structure of the view window and the housing of the lidar.

[0045] Figure 9 This is a schematic diagram of another embodiment of the window used in lidar according to the present invention;

[0046] Figure 10 This is a schematic diagram of the optical path structure of the scanning device in the initial position in one embodiment of the lidar of the present invention;

[0047] Figure 11 is Figure 10 is a schematic diagram of the optical path structure when the scanning device rotates clockwise from the initial position in the laser radar embodiment shown in

[0048] Figure 12 is Figure 10 is a schematic diagram of the optical path structure when the scanning device rotates clockwise from the initial position in the laser radar embodiment shown in DETAILED DESCRIPTION

[0049] As known from the background, the laser radar in the prior art has a noise problem.

[0050] To solve the technical problem, the application provides a window for a laser radar, the laser radar comprising: a transceiving module and a scanning device; wherein the detection light generated by the transceiving module forms emission light after being deflected by the scanning device; the emission light transmits through the window and is emitted to a three-dimensional space; the emitted emission light forms echo light after being reflected by a target object; the echo light transmits through the window and is deflected by the scanning device to be collected by the transceiving module; the window comprises an attenuation part, and the attenuation part attenuates stray light formed after the emission light is reflected thereby.

[0051] The attenuation part of the window makes the stray light formed after the emission light is reflected thereby to be divergent or convergent after divergence to achieve attenuation, which can effectively overcome the noise problem and further effectively suppress the crosstalk phenomenon of the laser radar and improve the signal-to-noise ratio.

[0052] To make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the specific embodiments of the application are described in detail below with reference to the drawings.

[0053] Reference Figure 4 is a schematic diagram of the structure of an embodiment of the window for a laser radar of the application.

[0054] It should be noted that Figure 4 is a schematic diagram of the optical path structure of a laser radar using the window embodiment.

[0055] Specifically, the laser radar comprises: a transceiving module 110 and a scanning device 120; wherein the detection light generated by the transceiving module 10 forms emission light 110a (such as Figure 4 indicated by the thick arrow in the figure) after being deflected by the scanning device 120; the emission light 110 transmits through the window 130 and is emitted to a three-dimensional space; the emitted emission light 110a forms echo light 110b (such as Figure 4The echo light 110b is deflected by the scanning device 120 to be collected by the transceiver module 110 after transmitting through the viewing window 130. The viewing window comprises an attenuation part 131 which attenuates the stray light 110c formed by the reflection of the emitted light 110a.

[0056] In some embodiments of the present application, the attenuation part 131 is curved. Specifically, the curved shape comprises at least one of a curved shape protruding towards the external space of the laser radar and a curved shape protruding towards the internal space of the laser radar. As shown in the embodiment, the curved shape is a curved shape protruding towards the external space of the laser radar. The attenuation part 131 reflects the stray light 110c formed by the emitted light 110a to be divergent after convergence to achieve attenuation. Figure 4

[0057] The attenuation part 131 of the viewing window makes the stray light 110c formed by the reflection of the emitted light 110a to be divergent or divergent after convergence to achieve attenuation, which can effectively overcome the noise problem, and further effectively suppress the crosstalk phenomenon of the laser radar and improve the signal-to-noise ratio.

[0058] The attenuation part of the viewing window in a curved shape can greatly attenuate the noise points formed by secondary reflection. The reason is that: since the attenuation part 131 is curved, the stray light formed by the reflection of the attenuation part 131 is directly divergent or convergent first and then divergent. When the curved shape of the attenuation part 131 protrudes towards the external space of the laser radar, the inner surface of the attenuation part 131 towards the internal space of the laser radar and the outer surface of the attenuation part 131 towards the external space of the laser radar are both curved surfaces protruding towards the external space of the laser radar. The inner surface and the outer surface of the attenuation part 131 make the stray light 110c formed by the reflection of the emitted light 110a to be convergent first and then divergent.

[0059] It should be noted that, Figure 4 Only the stray light 110c formed by the reflection of the emitted light 110a towards the inner surface of the attenuation part 131 towards the internal space of the laser radar is shown. The stray light formed by the reflection of the stray light 110a towards the outer surface of the attenuation part 131 towards the external space of the laser radar is not shown in Figure 4 .

[0060] The stray light 110c is reflected by the scanning device 120 and then transmitted through the viewing window to be projected on the target 101. Since the stray light 110c is convergent first and then divergent, the intensity of the stray light 110c projected on the target 101 is small (compared with Figure 6 ​Compared to the stray light formed by the mid-plane viewing window, the intensity of the stray echo light (not shown in the figure) formed by the stray light 110c reflected by the target 101 is also smaller, and the stray echo light returns along the original path. After being reflected by the scanning device 120, the stray echo light is projected again onto the attenuation part 131. The stray echo light reflected by the attenuation part 131 still exhibits a propagation mode of first converging and then diverging, thereby attenuating the intensity of the stray echo light again, thus achieving the purpose of suppressing noise formation. Moreover, the effect of the attenuation part in suppressing noise formation becomes more obvious as the detection distance increases.

[0061] Reference Figure 5 In some embodiments of the present invention, the lidar further includes: an optical system 140, the optical system 140 being adapted to target the emitted light 110a (e.g., ... Figure 4 (as shown) collimation is performed; the smaller the focal length f of the optical system 140, the more appropriate the attenuation unit 131 (as shown) is. Figure 4 The radius of curvature of the attenuation section 131 (as shown) can be set to be larger. The radius of curvature of the attenuation section 131 is adapted to the focal length f of the optical system 140, thereby ensuring the ranging capability of the lidar while overcoming stray light interference. Specifically, the radius of curvature of the attenuation section 131 is in the range of 150mm to 400mm.

[0062] The function of the attenuation section 131 is to make the stray light 110c formed by the window reflection converge and then diverge or diverge, so that the signal energy of the stray echo light that forms noise is less than the signal energy of the echo light. If the signal energy of the stray echo light is greater than the signal energy of the echo light, the stray echo light will cause serious signal interference to the echo light.

[0063] The smaller the radius of curvature of the attenuation section 131, the more diffuse the stray light is formed, and the lower the energy of the stray echo light is formed. It can be seen that minimizing the radius of curvature of the attenuation section 131 can effectively reduce the energy of the stray echo light and effectively reduce the probability of noise formation. For example, the radius of curvature of the attenuation section 131 can be made to be less than 400mm, so that the energy of the stray echo light is less than the energy of the echo light.

[0064] On the other hand, the radius of curvature of the attenuation section 131 is also related to the parameters of the optical system 140, including the near-field spot size and the far-field divergence angle. The near-field is the detection range within 1m, and the far-field is the detection range beyond 100 meters. When the far-field divergence angle is a fixed value, the smaller the near-field spot size, the smaller the radius of curvature of the attenuation section 131 can be; conversely, when the near-field spot size is a fixed value, the smaller the radius of curvature, the larger the far-field divergence angle. Therefore, the radius of curvature needs to be above 150mm to prevent divergence angle degradation and avoid affecting the distance measurement capability.

[0065] In some embodiments of the present application, the tangent plane at the position where the light spot of the emitted light 110a projected on the attenuation portion 131 is oblique to the direction vector of the emitted light 110a, that is, the tangent plane 131b at the position of the incident point 131a of the emitted light 110a on the inner surface or the outer surface of the attenuation portion 131 is not perpendicular to the direction vector of the emitted light 110a, thereby avoiding the stray light formed by the reflection of the emitted light 110a on the attenuation portion 131 returning to the original path.

[0066] Specifically, as shown in Figure 6 , the window has an inclination angle w, so that the included angle between the tangent plane at the position where the light spot of the emitted light 110a projected on the attenuation portion 131 and the vertical plane of the optical axis of the laser radar is the inclination angle w. When the vertical field of view angle of the laser radar is 2θ, w>θ. The length of the attenuation portion 131 along the inclination angle w increases with the increase of the inclination angle w, that is, the length of the projection of the attenuation portion 131 in the tangent plane increases with the increase of the inclination angle w, therefore the inclination angle w should be reduced as much as possible to reduce the area of the window, preferably, w is greater than θ by 5% or less.

[0067] As shown in Figure 5 , the optical path of the laser radar has a relationship: f*tanθ*(1+DiMx)=h, where f is the focal length of the optical system 140 of the laser radar, 2θ is the field of view angle of the laser radar, DiMx is the error (such as aberration, etc.) of the optical system 140 of the laser radar, and h is the maximum distance between the position of the light source in the transceiver module and the optical axis. The above relationship can be simplified as: f*θ=h. It can be seen that, in the case of fixed light source size, the field of view angle 2θ is inversely proportional to the focal length f of the optical system 140, when the focal length f of the optical system 140 increases, the field of view angle 2θ decreases, accordingly, the inclination angle w of the window decreases, therefore the inclination angle w of the window can be reduced by increasing the focal length of the optical system 140, thereby reducing the area of the window.

[0068] In combination with reference to Figure 7 , a perspective structural schematic view of the window embodiment shown in Figure 4 is shown.

[0069] The window 130 includes not only the attenuation portion 131, but also a non-attenuation portion 132, that is, the window 130 further includes a non-attenuation portion 132 which is different in shape from the attenuation portion.

[0070] As shown in Figure 7As shown, in some embodiments of the present application, the non-attenuation portion 132 is in a flat plate shape. In other embodiments of the present application, the non-attenuation portion can also be in a curved shape protruding outwardly from the lidar. By setting the non-attenuation portion in a flat plate shape or a curved shape protruding outwardly from the lidar, the internal space of the lidar can be effectively increased to facilitate the utilization of space.

[0071] In some embodiments of the present application, the material of the window is PC material, i.e., the material of the attenuation portion 131 and the non-attenuation portion 132 can be PC material. In other embodiments of the present application, the material of the window can also be glass or other materials.

[0072] In some embodiments of the present application, as shown in Figure 8 The window 130 is fixed with the housing 150 of the lidar by screws 151. The cavity surrounded by the housing 150 and the window 130 is used to accommodate components. Specifically, the screws 151 pass through the bottom surface of the housing 150 of the lidar and are fixed with the housing 150 of the lidar on both sides of the window 130. Compared with the glue fixing method, the window fixed by screws is more secure, has stronger reliability, and is convenient for disassembling the window.

[0073] Referring to Figure 9 , another embodiment of the structure of the window for the lidar of the present application is shown.

[0074] It should be noted that the same parts of the present embodiment and the foregoing embodiments are not described herein. The difference between the present embodiment and the foregoing embodiments is that, in the present embodiment, the curved shape protrudes towards the internal space of the lidar, and the stray light 210c formed by the reflection of the emitted light 210a by the attenuation portion 231 is in a divergent shape to achieve attenuation.

[0075] As shown in Figure 9 When the curved shape of the attenuation portion 231 protrudes towards the internal space of the lidar, the inner surface of the attenuation portion 231 towards the internal space of the lidar and the outer surface of the attenuation portion 231 towards the external space of the lidar are both curved surfaces protruding towards the internal space of the lidar, and the stray light 210c formed by the reflection of the emitted light 210a by the inner surface and the outer surface of the attenuation portion 231 is both in a divergent shape.

[0076] It should be noted that, Figure 9 Only the stray light 210c formed by the reflection of the emitted light 210a by the inner surface of the attenuation portion 231 towards the internal space of the lidar is shown. The stray light formed by the reflection of the emitted light 210a by the outer surface of the attenuation portion 231 towards the external space of the lidar is not shown in Figure 9 .

[0077] The stray light 210c is reflected by the scanning device 220 and then transmitted through the window again to project on the target 201. Since the stray light 210c is divergent, the light intensity of the stray light 210c projected on the target 201 is weak (compared with the stray light formed by the middle plane window). Figure 6 Correspondingly, the intensity of the stray echo light (not shown in the figure) formed by the target 201 reflecting the stray light 210c is also small, and the stray echo light returns along the original path. The stray echo light returning along the original path is reflected by the scanning device 220 again to project on the attenuation part 231, and the stray echo light reflected by the attenuation part 231 again is still radial, and the light intensity of the stray echo light is attenuated again, so that the purpose of suppressing the formation of noise points can be achieved. Moreover, with the increase of the detection distance, the effect of the attenuation part in suppressing the formation of noise points is more obvious.

[0078] Correspondingly, the application also provides a laser radar.

[0079] Reference Figure 10 , a structural schematic diagram of an embodiment of the laser radar of the application is shown.

[0080] The laser radar comprises a transceiving module 310, the transmitting module is suitable for generating detection light and is also suitable for collecting the echo light; a scanning device 320, the scanning device is suitable for deflecting the detection light generated by the transceiving module; and a window 330, the window 330 is the window of the application.

[0081] The window 330 is the window of the application. The specific technical solutions of the window 330 are referred to the aforementioned embodiments of the window, which will not be described herein again. Specifically, in some embodiments of the application, the window 330 comprises attenuation parts 331 and non-attenuation parts 332 with different shapes.

[0082] In some embodiments of the application, the scanning device 320 comprises a rotating mirror. In other embodiments of the application, the scanning device can also comprise a vibrating mirror. The detection light generated by the transceiving module is reflected by the scanning device 320 to form transmitting light.

[0083] Specifically, the laser radar is a laser radar adopting coaxial transmission and reception. Specifically, the part of the light path of the transceiving module generating detection light and the part of the light path of the transceiving module collecting the echo light are on the same optical axis.

[0084] In some embodiments of the present application, the position of the scanning device 320 corresponds to the position of the junction of the attenuated portion 331 and the non-attenuated portion 332 of the window 330. Specifically, when the scanning device 320 is in the initial position, the light spot formed by the emitted light projected on the window 330 is located on the attenuated portion 331. The initial position of the scanning device 320 refers to the position of the scanning device 320 when the emitted light reflected by the scanning device 320 is perpendicular to the non-attenuated portion in the horizontal field of view. Preferably, when the probe light is incident on the rotating mirror of the scanning device 320 at an angle of 45°, the emitted light reflected by the rotating mirror is perpendicular to the non-attenuated portion in the horizontal field of view, i.e., the position of the rotating mirror at which the probe light is incident at an angle of 45° is the initial position.

[0085] As shown in FIG. 6, when the rotating mirror rotates counterclockwise, the incident angle of the probe light is greater than 45°, and the emitted light formed is projected on the attenuated portion 331 of the window. The stray light formed is reflected by the attenuated portion 331 and the rotating mirror in sequence and then exits the three-dimensional space outside the lidar through the non-attenuated portion 332 of the window. The stray light reflected by the attenuated portion 331 propagates in a state of converging first and then diverging. The energy of the stray light projected on the target is low, and the stray echo light formed by the reflection of the target returns along the original path. After being reflected by the attenuated portion 331 again, the light intensity of the stray echo light is further weakened, thereby effectively reducing the possibility of forming noise points. Figure 11 As shown in FIG. 7, when the rotating mirror rotates clockwise, the incident angle of the probe light is less than 45°, and the emitted light formed is directly projected on the non-attenuated portion 332 far away from the scanning device 320. The stray light formed by the reflection of the non-attenuated portion 332 propagates in a direction away from the scanning device 320 and will not be projected on the scanning device 320 again, so it will not form noise points.

[0086] Figure 12 In some embodiments of the present application, the attenuated portion 331 of the window is close to the scanning device 320, and the non-attenuated portion is far away from the scanning device 320. As shown in FIG. 7, when the rotating mirror rotates clockwise, the incident angle of the probe light is less than 45°, and the emitted light formed is directly projected on the non-attenuated portion 332 far away from the scanning device 320. The stray light formed by the reflection of the non-attenuated portion 332 propagates in a direction away from the scanning device 320 and will not be projected on the scanning device 320 again, so it will not form noise points.

[0087] In summary, the attenuated portion of the window causes the stray light formed by the reflection of the emitted light to be divergent or divergent after convergence to achieve attenuation, which can effectively overcome the noise problem and further effectively suppress the crosstalk phenomenon of the lidar and improve the signal-to-noise ratio.

[0088] ​And, in an optional solution, the stray light is transmitted to the three-dimensional space through the window after being reflected by the scanning device; the stray light forms stray echo light after being reflected by the target object; the stray echo light is transmitted through the window and then reflected by the scanning device to the attenuation part to achieve attenuation. The attenuation part can also effectively improve the secondary reflection of the window to light, further reduce the noise points on the point cloud, and improve the interference problem of the lidar signal.

[0089] In addition, in an optional solution, the window further comprises a non-attenuation part in the form of a flat plate or a curved shape protruding outward from the lidar. The non-attenuation part in the form of a flat plate or a curved shape protruding outward from the lidar can ensure the size of the internal space of the lidar.

[0090] In addition, in an optional solution, the lidar further comprises an optical system suitable for collimating the emitted light; the smaller the focal length of the optical system, the larger the radius of curvature of the attenuation part. The radius of curvature of the attenuation part is adapted to the focal length of the optical system, so that the ranging capability of the lidar can be ensured while overcoming the problem of stray light interference.

[0091] Further, in an optional solution, the window is fixed to the shell of the lidar by a screw; the screw passes through the bottom surface of the shell of the lidar and is fixed to the shell of the lidar on both sides of the window. Compared with the glue fixing method, the screw fixing method is more secure and reliable, and the window is easier to disassemble.

[0092] Although the present application is disclosed as above, the present application is not limited thereto. Any person skilled in the art, without departing from the spirit and scope of the present application, can make various changes and modifications, therefore the protection scope of the present application should be subject to the scope defined by the claims.

Claims

1. A lidar, comprising: The application relates to a laser radar, which comprises a transceiver module, a scanning device and a window. The transceiver module is suitable for generating probe light and collecting echo light. The scanning device is suitable for deflecting the probe light generated by the transceiver module, and the reflecting surface of the scanning device is a plane. The probe light generated by the transceiver module forms emitting light after being deflected by the scanning device, and the part of the light path of the probe light generated by the transceiver module is the same as the part of the light path of the echo light collected by the transceiver module. The emitting light transmits through the window and is emitted to a three-dimensional space. The emitted emitting light forms echo light after being reflected by a target object. The echo light transmits through the window and is deflected by the scanning device to be collected by the transceiver module. The window comprises an attenuation part and a non-attenuation part, the attenuation part is curved, the shape of the non-attenuation part is different from that of the attenuation part, and the attenuation part is closer to the scanning device than the non-attenuation part. The emitting light reflected by the attenuation part is incident on the scanning device at different angles, so that the stray light reflected by the scanning device is dispersed and incident on the environment. The reflected light reflected by the non-attenuation part deviates from the scanning device. The curved shape is convex towards the external space of the laser radar, and the stray light formed by the attenuation part reflecting the emitting light is converged and then diverged to achieve attenuation. Alternatively, the curved shape is convex towards the internal space of the laser radar, and the stray light formed by the attenuation part reflecting the emitting light is diverged to achieve attenuation. The stray light is emitted to a three-dimensional space after being deflected by the scanning device; the emitted stray light forms stray echo light after being reflected by a target object; and the stray echo light is deflected by the scanning device to the attenuation part to achieve attenuation after transmitting through the window.

2. The lidar of claim 1, wherein, The shape of the non-attenuation part is a flat plate or a curved shape convex towards the external space of the laser radar.

3. The lidar of claim 1, wherein, The laser radar further comprises an optical system suitable for collimating the emitting light.

4. The lidar of claim 1, wherein, The smaller the focal length of the optical system is, the greater the radius of curvature of the attenuation part is. The radius of curvature of the attenuation part is in the range of 150 mm to 400 mm.

5. The lidar of claim 4, wherein, The tangent plane at the position of the light spot of the emitting light projected on the attenuation part is oblique to the direction vector of the emitting light.

6. The lidar of claim 1, wherein, The field of view angle of the laser radar is 2theta.

7. The lidar of claim 6, wherein, The included angle between the tangent plane at the position of the light spot of the emitting light projected on the attenuation part and the perpendicular plane of the optical axis of the laser radar is w. Wherein, w>theta. The material of the window is PC material.

8. The lidar of claim 1, wherein, The window and the shell of the laser radar are fixed by screws.

9. The lidar of claim 1, wherein, The screws pass through the bottom surface of the shell of the laser radar and are fixed on the two sides of the window and the shell of the laser radar. The scanning device comprises one of a rotating mirror and a vibrating mirror.

10. The lidar of claim 1, wherein, ​

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