Laser receiving module and laser radar

Abstract

The invention discloses a laser receiving module and a laser radar. The laser receiving module comprises a receiver and a receiving lens, the receiver is provided with a receiving surface, and the receiving lens is used for receiving echo light reflected by a target object and is arranged corresponding to the receiving surface so that the echo light can reach the receiving surface; the receiving lens comprises at least one lens which has bending force to light and is sequentially arranged from the object side to the image side along the optical axis, the receiving lens meets the conditional expression that h / f is larger than or equal to 0.26 and smaller than or equal to 0.70, f is the effective focal length of the receiving lens, h is the maximum image height of the laser receiving module, and f is the effective focal length of the receiving lens. The size of the receiving surface of the receiver and the effective focal length of the receiving lens can be conveniently controlled in a proper range, so that the receiving lens has a large effective focal length under the condition that the receiving lens has a proper receiving field angle, the long-distance detection requirement of the laser radar is met, and meanwhile, the resolution of image information obtained by the receiving surface of the receiver is good.

Description

Technical Field

[0001] This application relates to the technical field of lidar, and in particular to a laser receiving module and a lidar. Background Art

[0002] A lidar is a radar system that detects the position, speed and other characteristic quantities of a target by emitting laser beams. A lidar generally includes a transmitting module, a receiving module and a signal processing device. The light source in the transmitting module emits a detection beam to the target object. The receiving module receives the echo beam reflected by the target object and outputs a corresponding electrical signal. Then, after the signal processing device processes the electrical signal, parameters such as the distance, azimuth, height, speed, attitude and shape of the target object are obtained, so as to realize the detection function.

[0003] Currently, in the related art, in order to meet the detection requirements of a large field of view angle, the focal length of the receiving module is small, and it is difficult to meet the long-distance detection requirements of the lidar. Summary of the Invention

[0004] The embodiments of this application provide a laser receiving module and a lidar, which can solve the problem of short detection distance of the lidar.

[0005] In a first aspect, the embodiments of this application provide a laser receiving module. The laser receiving module includes a receiver and a receiving lens. The receiver has a receiving surface. The receiving lens is used to receive the echo light reflected by the target object and is arranged corresponding to the receiving surface so that the echo light can reach the receiving surface.

[0006] The receiving lens includes at least one lens having a bending force on light rays arranged in sequence from the object side to the image side along the optical axis. The receiving lens satisfies the conditional formula: 0.26 ≤ h / f ≤ 0.70, where f is the effective focal length of the receiving lens, and h is the maximum image height of the laser receiving module.

[0007] In some exemplary embodiments, the receiving lens satisfies at least one of the following conditions:

[0008] (1) 0.9 ≤ F ≤ 1.1, where F is the F-number of the receiving lens;

[0009] (2) 5.0 mm ≤ f ≤ 12.0 mm;

[0010] (3) 3.5 mm ≤ h ≤ 4 mm;

[0011] (4) 10.0° ≤ CRA ≤ 20.0°, where CRA is the angle between the marginal ray entering the receiving surface and the optical axis;

[0012] (5) 7.5 ≤ TTL / h ≤ 8.0, where TTL is the distance between the object side of the lens of the receiving lens facing the target and the image side of the lens facing the receiving surface in the optical axis direction.

[0013] In some exemplary embodiments, the optical axis of the receiving lens passes through the geometric center of the receiving surface; the receiving lens satisfies the conditional formula: 1 ≤ Lx / Ly ≤ 5, where Lx is the size of the receiving surface in the horizontal direction and Ly is the size of the receiving surface in the vertical direction.

[0014] In some exemplary embodiments, the receiving lens includes a first lens group, a diaphragm, and a second lens group sequentially arranged from the object side to the image side along the optical axis;

[0015] The first lens group includes at least one lens having a refractive power for light rays, and the first lens group is used to deflect the light rays to make the light rays approach the optical axis so as to converge the light rays;

[0016] The second lens group includes at least one lens having a refractive power for light rays, and the second lens group is used to converge the light rays to the receiving surface and correct aberration.

[0017] In some exemplary embodiments, the first lens group includes a first lens and a second lens sequentially arranged from the object side to the image side along the optical axis, the first lens has a negative refractive power, and the second lens has a positive refractive power; the second lens group includes a third lens and a fourth lens sequentially arranged from the object side to the image side along the optical axis, and both the third lens and the fourth lens have positive refractive powers.

[0018] In some exemplary embodiments, the receiving lens satisfies the conditional formula: 0.45 ≤ h / f ≤ 0.70;

[0019] The object side of the first lens is convex near the optical axis, and the image side is concave near the optical axis. The focal length of the first lens is f1, and -11.0 mm ≤ f1 ≤ -11.7 mm;

[0020] The object side and the image side of the second lens are both convex near the optical axis. The focal length of the second lens is f2, and 17.9 mm ≤ f2 ≤ 18.5 mm;

[0021] The object side of the third lens is convex near the optical axis, and the image side is concave near the optical axis. The focal length of the third lens is f3, and 16.7 mm ≤ f3 ≤ 17.5 mm;

[0022] The object side of the fourth lens is convex near the optical axis, and the image side is concave near the optical axis. The focal length of the fourth lens is f4, and 17.2 mm ≤ f4 ≤ 17.9 mm.

[0023] In some exemplary embodiments, the receiving lens satisfies the conditional formula: 0.26 ≤ h / f ≤ 0.50;

[0024] The first lens group includes a first lens; the second lens group includes a second lens, a third lens, and a fourth lens arranged in sequence from the object side to the image side along the optical axis;

[0025] The first lens has a negative refractive power, and the object side of the first lens is convex near the optical axis and the image side is concave near the optical axis. The focal length of the first lens is f1, and -52.5 mm ≤ f1 ≤ -51.0 mm;

[0026] The second lens has a positive refractive power, and the object side of the second lens is convex near the optical axis and the image side is concave near the optical axis. The focal length of the second lens is f2, and 22.0 mm ≤ f2 ≤ 22.9 mm;

[0027] The third lens has a positive refractive power, and the object side of the third lens is convex near the optical axis and the image side is concave near the optical axis. The focal length of the third lens is f3, and 33.3 mm ≤ f3 ≤ 35.5 mm;

[0028] The fourth lens has a positive refractive power, and the object side of the fourth lens is convex near the optical axis and the image side is concave near the optical axis. The focal length of the fourth lens is f4, and 19.0 mm ≤ f4 ≤ 19.8 mm.

[0029] In some exemplary embodiments, the receiving lens satisfies the conditional formula 0.26 ≤ h / f ≤ 0.50;

[0030] The first lens group includes a first lens and a second lens arranged in sequence from the object side to the image side along the optical axis; the second lens group includes a third lens and a fourth lens arranged in sequence from the object side to the image side along the optical axis;

[0031] The first lens has a negative refractive power, and the object side of the first lens is convex near the optical axis and the image side is concave near the optical axis. The focal length of the first lens is f1, and -48.0 mm ≤ f1 ≤ -46.5 mm;

[0032] The second lens has a positive refractive power, and the object side of the second lens is convex near the optical axis and the image side is concave near the optical axis. The focal length of the second lens is f2, and 22.0 mm ≤ f2 ≤ 22.9 mm;

[0033] The third lens has a positive refractive power, and the object side surface of the third lens is convex near the optical axis, and the image side surface is concave near the optical axis. The focal length of the third lens is f3, and 35.3 mm ≤ f3 ≤ 37.5 mm;

[0034] The fourth lens has a positive refractive power, and the object side surface of the fourth lens is convex near the optical axis, and the image side surface is concave near the optical axis. The focal length of the fourth lens is f4, and 18.0 mm ≤ f4 ≤ 19.8 mm.

[0035] In some exemplary embodiments, the fourth lens is an aspherical lens; the fourth lens is made of plastic, and the remaining lenses in the receiving lens are made of glass.

[0036] In a second aspect, an embodiment of the present application provides a lidar, including a laser emission module and a laser reception module. The laser emission module is configured to emit detection light to detect a target object; the laser reception module is configured to receive the reflected light wave formed by the target object reflecting the detection light.

[0037] Based on the laser reception module and the lidar of the embodiments of the present application, by setting the range of h / f to be 0.26 to 0.70, it is convenient to control both the size of the receiving surface of the receiver and the effective focal length of the receiving lens within a suitable range, so that when the receiving lens has a smaller receiving field angle and a larger effective focal length, it can meet the long-distance detection requirements of the lidar. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0039] Figure 1 Schematic structural diagram of the lens of the receiving lens in Embodiment 1;

[0040] Figure 2 Field curvature curve diagram of the receiving lens in Embodiment 1;

[0041] Figure 3 Distortion curve diagram of the receiving lens in Embodiment 1;

[0042] Figure 4 Modulation transfer function (MTF) curve diagram of the receiving lens in Embodiment 1;

[0043] Figure 5 Relative illuminance curve diagram of the receiving lens in Embodiment 1;

[0044] Figure 6 Schematic diagram of the lens of the receiving lens in the second embodiment;

[0045] Figure 7 Field curvature curve of the receiving lens in the second embodiment;

[0046] Figure 8 Distortion curve of the receiving lens in the second embodiment;

[0047] Figure 9 Modulation transfer function (MTF) curve of the receiving lens in the second embodiment;

[0048] Figure 10 Relative illumination curve of the receiving lens in the second embodiment;

[0049] Figure 11 Schematic diagram of the lens of the receiving lens in the third embodiment;

[0050] Figure 12 Field curvature curve of the receiving lens in the third embodiment;

[0051] Figure 13 Distortion curve of the receiving lens in the third embodiment;

[0052] Figure 14 Modulation transfer function (MTF) curve of the receiving lens in the third embodiment;

[0053] Figure 15 Relative illumination curve of the receiving lens in the third embodiment;

[0054] Figure 16 Schematic diagram of the lens of the receiving lens in the third embodiment;

[0055] Figure 17 Field curvature curve of the receiving lens in the third embodiment;

[0056] Figure 18 Distortion curve of the receiving lens in the third embodiment;

[0057] Figure 19 Modulation transfer function (MTF) curve of the receiving lens in the third embodiment;

[0058] Figure 20 Relative illumination curve of the receiving lens in the third embodiment.

[0059] Reference numerals:

[0060] 10. Receiving lens; 20. Receiver; 100. First lens group; 200. Second lens group; L1. First lens; L2. Second lens; L3. Third lens; L4. Fourth lens; SL. Filter; SP. Protective glass; M. Receiving surface; ST. Diaphragm. Detailed implementation manners

[0061] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0062] The inventors found that the ranging performance of vehicle-mounted lidar is affected by various factors, such as power, stray light, the size of the receiving aperture, focal length, field of view angle, etc. The transceiver lenses in related technologies are often designed with a field of view angle greater than 90 degrees to facilitate obtaining more target information, but this will reduce the ability to receive the reflected light, thereby resulting in a short detection distance of the lidar. Based on this, the embodiments of the present application provide a laser receiving module and a lidar to solve the problem of the short detection distance of the current lidar.

[0063] The lidar in the embodiments of the present application includes a laser emission module and a laser receiving module. The laser emission module is used to emit detection light to detect a target object, and the laser receiving module is used to receive the reflected light formed by the target object reflecting the detection light.

[0064] Specifically, the laser emission module includes a transmitter and a transmitting lens. The transmitter is used to emit detection light. The transmitting lens is disposed on the light-emitting side of the transmitter to receive the detection light emitted by the transmitter. The transmitting lens includes at least one lens that has a bending force on light to diverge the detection light and project it onto the target object within the transmitting field of view angle area. As Figures 1 - 12 shown, it is a schematic structural diagram and corresponding parameters of the laser receiving module in the embodiments of the present application. In the embodiments of the present application, the laser receiving module includes a receiver 20 and a receiving lens 10. The receiver 20 has a receiving surface M. The receiving lens 10 is disposed corresponding to the receiving surface M. The receiving lens 10 is used to receive the reflected light reflected by the target object within the receiving field of view angle area, and the receiving lens 10 includes at least one lens that has a bending force on light to converge the reflected light to the receiving surface M. The receiving surface M is used to receive the reflected light reflected by the target object. The area covered by the transmitting field of view angle of the laser emission module of the lidar and the area covered by the receiving field of view angle of the laser receiving module at least partially overlap, so that when the laser emission module emits outgoing laser to the target object located in the overlapping detection area, the reflected light after being reflected by the target object can be received by the laser receiving module.

[0065] The lidar may include multiple laser emission modules. The emission field of view of the lidar includes the total emission field of view of all the laser emission modules, that is, the combination of the emission field of views of multiple laser emission modules. The emitter of each laser emission module may include multiple light sources to jointly emit detection light, thereby illuminating a specific area outside the lidar. This area is the detection field of view corresponding to this laser emission module. The lidar may include multiple laser reception modules. The multiple laser reception modules correspond one-to-one with the multiple laser emission modules. Alternatively, each laser reception module corresponds to one or more of the laser emission modules. The reception field of view of the lidar includes the total reception field of view of all the laser reception modules, that is, the combination of the reception field of views of multiple laser reception modules. The receiver of each laser reception module may include multiple photodetectors to respectively receive the detection light emitted by the corresponding light sources.

[0066] Hereinafter, taking the lidar as a flash lidar and including only one laser reception module as an example for illustration. It can be understood that in other embodiments of the present application, multiple laser reception modules may also be included. Correspondingly, multiple laser emission modules may also be included.

[0067] Specifically, in the embodiment of the present application, the size of the receiving surface M of the receiver 20 in the laser reception module in a single direction is H, the effective focal length of the receiving lens 10 is f, and the reception field of view of this laser reception module is Θ; the optical axis of the receiving lens 10 passes through the geometric center of the receiver 20. Therefore, the maximum image height h of this laser reception module in the above single direction satisfies h = H / 2, and the half field of view angle θ of the receiving lens 10 satisfies θ = Θ / 2. In this embodiment, h, f, and θ satisfy: h = f * θ. Based on this, when the size of the receiver 20 is relatively determined, the maximum image height h of this laser reception module is also correspondingly determined; at the same time, the half reception field of view angle θ (radian value) of each laser reception module is inversely proportional to the effective focal length f of the receiving lens 10. Therefore, by increasing the focal length f of the receiving lens 10 in the laser reception module, the above half field of view angle θ can be reduced, that is, the reception field of view Θ of the laser reception module can be increased. In this way, on the one hand, the angle corresponding to a single pixel (i.e., a single photodetector) of the receiver 20 can be reduced, that is, the resolution value is reduced, and the resolution ability is improved; on the other hand, since the field of view of the laser emission module corresponds to the field of view of the laser reception module, the field of view of the laser emission module will also be reduced, thereby reducing the angle corresponding to a single pixel of the emitter, and the emitted energy is more concentrated. Therefore, the detection distance of the lidar is increased, and the detection performance is improved.

[0068] More specifically, the receiving lens 10 includes at least one lens having a light-bending force, which is arranged in sequence from the object side to the image side along the optical axis. The receiving lens 10 satisfies the conditional formula: 0.26 ≤ h / f ≤ 0.70, where f is the effective focal length of the receiving lens 10, and h is the maximum image height of the laser receiving module, that is, half of the maximum linear dimension in a single direction of the receiving surface M of the receiver 20. By setting h / f within the range of 0.26 to 0.70, the half field of view angle of the laser receiving module can be made to be between 15° and 40°, that is, the field of view angle of the laser receiving module is between 30° and 80°, so that the lidar has a smaller field of view angle. For example, in some embodiments, the maximum image height of the laser receiving module is 3.7 mm; based on this, the focal length f of the receiving lens 10 can be controlled to be between 5.28 mm and 14.23 mm, and the receiver 200 is located on the focal plane of the receiving lens 10, so that the field of view angle of the laser receiving module is between 30° and 80°. Of course, in other embodiments, the maximum image height of the laser receiving module may not be 3.7 mm, but other values may be selected according to actual application situations; for example, in some other embodiments, the maximum image height of the laser receiving module may satisfy: 3.5 mm ≤ h ≤ 4 mm, based on this, correspondingly, the focal length f of the laser receiving module satisfies: 5.0 mm ≤ f ≤ 15.38 mm.

[0069] The receiving lens 10 also satisfies: 0.9 ≤ F ≤ 1.1, where F is the F-number of the receiving lens 10, that is, the F-number of the aperture stop ST of the receiving lens 10. It can be understood that the ranging of the lidar depends on the entrance pupil diameter of the receiving lens 10. The larger the entrance pupil diameter, the more light enters, and the better the imaging effect for long-distance detection. Among them, the entrance pupil diameter = f / F-number, and the entrance pupil diameter is proportional to the focal length f of the receiving lens 10. In the embodiments of the present application, in order to implement the design of a large entrance pupil diameter, the F-number of the receiving lens 10 is compressed to 0.9 to 1.1, so that while increasing the effective focal length f of the receiving lens 10, the entrance pupil diameter of the receiving lens 10 is increased. In this way, the light input can be increased while having a small field of view angle and a long detection distance, achieving the effect of a large entrance pupil diameter. Among them, the larger the entrance pupil diameter of the receiving lens 10, the larger the corresponding aberration. Setting the F-number in the range of 0.9 to 1.1 is convenient for controlling the entrance pupil diameter within a suitable range to prevent the aberration from being too large due to an overly large entrance pupil diameter. Optionally, the F-number is 1, so that the entrance pupil diameter is equal to the focal length.

[0070] Such as Figure 1As shown in the figure, the receiving lens 10 includes a first lens group 100, a diaphragm ST, and a second lens group 200 arranged in sequence from the object side to the image side along the optical axis. The first lens group 100 includes at least one lens having a bending force on light. The first lens group 100 is used to deflect light to converge the light beam, which helps the subsequent optical elements to converge light and correct aberrations. The first lens group 100 can also make the marginal rays of the field of view pass through the diaphragm ST at a small angle and project onto the second lens group 200, which helps to reduce aberrations such as field curvature and astigmatism when the light enters the second lens group 200. The second lens group 200 includes at least one lens having a bending force on light. The second lens group 200 is used to converge the light to the receiving surface M and correct aberrations. The second lens group 200 further adjusts the light after the first lens group 100. The two cooperate with each other to make the light project onto the receiving surface M of the receiver 20 at a small angle, having a good imaging effect. In this way, by receiving large-angle incident light through the first lens group 100 and adjusting the light in combination with the first lens group 100 and the second lens group 200, the receiving lens 10 has the ability of long-distance detection while having a good imaging effect.

[0071] Optionally, in some embodiments, the receiving lens 10 satisfies the conditional formula: 0.45 ≤ h / f ≤ 0.70. The receiving lens 10 can have a small field of view range, a large focal length, and a good imaging effect. Exemplarily, when h is 3.7 mm, the range of f is 5.28 mm to 8.22 mm. Within this range, the focal length of the receiving lens 10 is relatively large, and the field of view angle range of the receiving lens 10 is correspondingly 70° to 80°. Compared with the lidar with a field of view angle greater than 90 degrees in the related art, when this laser receiving module is applied to the lidar, the field of view angle of the lidar will be between 70° and 80°. Since the field of view angle is reduced, the detection distance and resolution of the lidar will be improved.

[0072] When the receiving lens 10 satisfies the conditional formula 0.45 ≤ h / f ≤ 0.70, optionally, as Figure 1 and Figure 6 shown, the first lens group 100 includes a first lens L1 and a second lens L2 arranged in sequence from the object side surface to the image side surface along the optical axis. The first lens L1 has a negative bending force, and the second lens L2 has a positive bending force, which adjusts the light to deflect toward the optical axis, helps to reduce the size of the rear lens group, and reduces the number of lens groups of the receiving lens 10. The second lens group 200 includes a third lens L3 and a fourth lens L4 arranged in sequence from the object side surface to the image side surface along the optical axis. Both the third lens L3 and the fourth lens L4 have positive bending forces, further adjusting the light, reducing aberrations such as field curvature and astigmatism, and making the light project onto the receiving surface M of the receiver 20 at a small angle, which helps to improve the imaging quality.

[0073] Specifically, the object side of the first lens L1 is convex near the optical axis, and the image side is concave near the optical axis. The focal length of the first lens L1 is f1, where -11.0 mm ≤ f1 ≤ -11.7 mm, enabling the receiving lens 10 to have a long focal length performance and allowing a distant target object to enter the receiving field of view area of the laser receiving module, thereby enabling the laser receiving module to have a long-distance detection performance. The object side of the second lens L2 is convex near the optical axis, and the image side is convex near the optical axis. The focal length of the second lens L2 is f2, where 17.9 mm ≤ f2 ≤ 18.5 mm. The object side of the third lens L3 is convex near the optical axis, and the image side is concave near the optical axis. The focal length of the third lens L3 is f3, where 16.7 mm ≤ f3 ≤ 17.5 mm. The object side of the fourth lens L4 is convex near the optical axis, and the image side is concave near the optical axis. The focal length of the fourth lens L4 is f4, where 17.2 mm ≤ f4 ≤ 17.9 mm. The second lens L2, the third lens L3, and the fourth lens L4 further adjust the light rays at the rear end of the first lens L1 to improve aberration.

[0074] Optionally, in some other embodiments, the receiving lens 10 satisfies the conditional formula: 0.26 ≤ h / f ≤ 0.50, enabling the receiving lens 10 to have a small field of view range, a large focal length, and good imaging effects. Exemplarily, when h is 3.7 mm, the range of f is 7.4 mm to 14.23 mm. Within this range, the focal length of the receiving lens 10 is relatively large, and correspondingly, the field of view angle range of the receiving lens 10 is 30° to 40°. Compared with lidars in the related art with a field of view angle greater than 90 degrees, when this laser receiving module is applied to a lidar, the field of view angle of the lidar will be between 30° and 40°; since the field of view angle is significantly reduced, the detection distance and resolution of the lidar will be significantly improved.

[0075] When the receiving lens 10 satisfies the conditional formula 0.26 ≤ h / f ≤ 0.50, further optionally, in one embodiment, as Figure 11 shown, the first lens group 100 includes the first lens L1; the second lens group 200 includes the second lens L2, the third lens L3, and the fourth lens L4 arranged in sequence from the object side to the image side along the optical axis.

[0076] Specifically, the first lens L1 has a negative refractive power, and its object side is convex near the optical axis and its image side is concave near the optical axis. The focal length of the first lens L1 is f1, where -52.5 mm ≤ f1 ≤ -51.0 mm; the second lens L2 has a positive refractive power, and its object side is convex near the optical axis and its image side is concave near the optical axis. The focal length of the second lens L2 is f2, where 22.0 mm ≤ f2 ≤ 22.9 mm; the third lens L3 has a positive refractive power, and its object side is convex near the optical axis and its image side is concave near the optical axis. The focal length of the third lens L3 is f3, where 33.3 mm ≤ f3 ≤ 35.5 mm; the fourth lens L4 has a positive refractive power, and its object side is convex near the optical axis and its image side is concave near the optical axis. The focal length of the fourth lens L4 is f4, where 19.0 mm ≤ f4 ≤ 19.8 mm. In this way, the first lens L1 is set to have a long focal length performance, and the second lens L2, the third lens L3, and the fourth lens L4 further adjust the light rays at the rear end of the first lens L1 to improve aberration.

[0077] When the receiving lens 10 satisfies the conditional expression 0.26 ≤ h / f ≤ 0.50, further optionally, in another embodiment, as Figure 16 shown, the first lens group 100 includes a first lens L1 and a second lens L2 arranged in sequence from the object side to the image side along the optical axis; the second lens group 200 includes a third lens L3 and a fourth lens L4 arranged in sequence from the object side to the image side along the optical axis.

[0078] Specifically, the first lens L1 has a negative refractive power, and its object side is convex near the optical axis and its image side is concave near the optical axis. The focal length of the first lens L1 is f1, where -48.0 mm ≤ f1 ≤ -46.5 mm; the second lens L2 has a positive refractive power, and its object side is convex near the optical axis and its image side is concave near the optical axis. The focal length of the second lens L2 is f2, where 22.0 mm ≤ f2 ≤ 22.9 mm; the third lens L3 has a positive refractive power, and its object side is convex near the optical axis and its image side is concave near the optical axis. The focal length of the third lens L3 is f3, where 35.3 mm ≤ f3 ≤ 37.5 mm; the fourth lens L4 has a positive refractive power, and its object side is convex near the optical axis and its image side is concave near the optical axis. The focal length of the fourth lens L4 is f4, where 18.0 mm ≤ f4 ≤ 19.8 mm. Similarly, the sequentially arranged first lens L1 and the second lens L2 enable the receiving lens 100 to have a long focal length performance, and the third lens L3 and the fourth lens L4 further adjust the light rays at the rear end of the diaphragm ST to improve aberration.

[0079] Generally, aberrations are divided into spherical aberration, coma, astigmatism, field curvature, distortion, chromatic aberration, etc. Since the laser radar band is very narrow, chromatic aberration can be ignored. The other types of aberrations will increase as the aperture of the lens increases. To reduce aberrations, it is usually necessary to increase the number of lenses. However, increasing the number of lenses will lead to higher costs. At the same time, increasing the number of lenses will affect the transmittance of the lens, resulting in a decrease in ranging, an increase in stray light, and other factors. Conventional spherical lenses have only variables such as the radius of curvature, thickness, refractive index of the material, and Abbe number in the design dimension. Therefore, the effect of correcting aberrations is relatively limited. This solution considers using aspherical lenses instead of spherical lenses. In addition to the above variables, aspherical lenses have more than 10 higher-order coefficients to correct aberrations. Therefore, usually the number of one aspherical lens is equivalent to at least two spherical lenses. Therefore, this solution considers using aspherical lenses to reduce the number of lenses of the receiving lens 10 and improve the transmittance of the receiving lens 10. Optionally, the above fourth lens L4 is an aspherical lens, which is used to focus the return light to the receiving surface and correct the phase difference of the return light at the same time. The fourth lens L4 can adopt an even aspherical lens, and the specific parameters can refer to Tables 2, 4, 6, and 8 in the embodiments described below.

[0080] The optical axis of the receiving lens 10 passes through the geometric center of the receiving surface M. The size h of the receiving surface M of the receiver 20 includes Lx and Ly. Lx is the size of the receiving surface M in the horizontal direction, and Ly is the size of the receiving surface M in the vertical direction, where 1 ≤ Lx / Ly ≤ 5. From the above formula, it can be seen that when the focal length f is determined, the half field of view (or field of view) of the laser receiving module in a certain direction is positively correlated with the maximum image height in that direction. The above setting is designed to ensure that the field of view of the laser receiving module in the horizontal direction is greater than the field of view in the vertical direction, so as to obtain more target information in the horizontal direction, and the ratio of the field of view of the laser receiving module in the horizontal direction to the field of view in the vertical direction is between 1 and 5.

[0081] The receiving lens 10 also satisfies the conditional formula: 7.5 ≤ TTL / h ≤ 8.0, where TTL is the distance between the object side of the lens of the receiving lens 10 facing the target and the image side of the lens facing the receiving surface M in the optical axis direction. By setting TTL / h in the range of 7.5 to 8.0, while meeting the requirements of the arrangement spacing of each lens of the receiving lens 10, it is convenient to control the volume of the laser receiving module and prevent the volume of the lidar from being too large. Optionally, TTL satisfies: 27.0 mm ≤ TTL ≤ 30.0 mm.

[0082] The receiving lens 10 also satisfies: 10.0° ≤ CRA ≤ 20.0°, where CRA is the angle between the principal ray entering the receiving surface M and the optical axis. In this way, by controlling the angle of the principal ray not to be higher than 20.0°, the receiving efficiency of the principal ray can be relatively high; correspondingly, the receiving efficiency of the return light incident at the remaining angles with respect to the optical axis will also be improved accordingly.

[0083] In the embodiment of the present application, in order to minimize the distortion of the point cloud image as much as possible, by adjusting the focal lengths of the lenses of the receiving lens 10, the distances between the lenses, and the materials of the lenses, the distortion of the receiving lens 10 is controlled within 15.4%, and the distortion of the image is controlled within an acceptable range.

[0084] The receiving lens 10 further includes a lens barrel, and both the first lens group 100 and the second lens group 200 are disposed in the light passing hole of the lens barrel. The aperture stop ST is a variable aperture stop, and the aperture stop ST is mounted on the lens barrel and is located between the image side of the first lens group 100 and the object side of the second lens group 200.

[0085] The laser receiving module further includes a protective glass SP and a filter SL. The filter SL and the protective glass SP are disposed between the image side of the second lens group 200 and the receiving surface M. The filter SL can be a band-pass filter, which allows the return light to pass through so that the return light can reach the receiving surface of the receiver 20; at the same time, the filter SL blocks the interference light signals outside the return light bandwidth to reduce the proportion of the interference light falling on the receiver 20, thereby reducing the influence of the receiver 20 on the reception of the return light. The protective glass SP is disposed adjacent to the receiving surface M of the receiver 20 to protect the receiver 20. The filter SL and the protective glass SP can be assembled together with the lenses as a part of the receiving lens 10; for example, in some embodiments, the lenses in the receiving lens 10 are mounted in the lens barrel, and the filter SL and the protective glass SP are mounted at the image end of the lens barrel. Of course, the filter SL and the protective glass SP can also be elements that do not belong to the receiving lens 10. In this case, the filter SL and the protective glass SP can be installed between the laser receiving module assembled by the receiving lens 10 and the photosensitive element and the receiver 20 when the receiving lens 10 and the photosensitive element are assembled into the laser receiving module. As for the setting position of the filter SL, in fact, it is flexible and changeable. It can be disposed adjacent to the protective glass SP or on the object side of the first lens group 100. The present application does not limit the specific position of the filter SL.

[0086] In the embodiment of the present application, the transmitting lens includes at least one lens having a bending force on the light. The lenses of the transmitting lens can include at least one of a glass lens and a plastic lens, and the surface type of the lenses of the transmitting lens can also include at least one of a spherical surface and an aspherical surface. The present application does not limit the type and number of the lenses of the transmitting lens, and can be specifically selected according to the type of the receiving lens 10. In addition, the laser transmitting module can further include a protective glass for protecting the transmitter. It should be noted that the field of view angle corresponding to the laser transmitting module composed of the transmitting lens and the transmitter (such as a laser) is matched with the field of view angle corresponding to the laser receiving module. In addition, similar to the receiving lens, the lens close to the transmitter in the transmitting lens can be made of plastic, and the remaining lenses can be made of glass.

[0087] The assembly structure of the receiving lens 10 of the present technical solution and the corresponding implementation results in each specific implementation manner will be introduced below with reference to the drawings and tables and in combination with specific numerical values.

[0088] The meanings of the marks shown in each embodiment are as follows.

[0089] S1, S3, S5, S7, and S9 are the numbers of the object sides of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the filter SL, respectively, and S2, S4, S6, S8, and S10 are the numbers of the image sides of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the filter SL, respectively.

[0090] When the object side or the image side of the fourth lens L4 is an even aspherical surface, the even aspherical surface satisfies the aspherical formula of Mathematical Formula 1:

[0091] Mathematical Formula 1:

[0092]

[0093] Wherein, K is the conic constant, and "A2", "A4", "A6", "A8", "A10", "A12", "A14", and "A16" respectively represent the aspherical coefficients of the 2nd order, 4th order, 6th order, 8th order, 10th order, 12th order, 14th order, and 16th order; r is the distance from any point on the aspherical surface to the optical axis; c is the curvature of the near optical axis at the vertex of the aspherical surface; Z is the vector height of the distance from the vertex of the aspherical surface when the aspherical surface is at a position with a height of r along the optical axis direction.

[0094] Embodiment 1

[0095] The structural schematic diagram of the receiving lens 10 in this embodiment is referred to Figure 1 As shown, the receiving lens 10 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a filter SL arranged in sequence from the object side to the image side along the optical axis. The receiving surface M is located on the side of the filter SL away from the fourth lens L4. The aperture stop ST is arranged between the image side S4 of the second lens L2 and the object side S5 of the third lens L3. The filter SL is a band-pass filter SL.

[0096] Among them, the first lens L1 has a negative refractive power. The object side surface S1 of the first lens L1 is convex near the optical axis, and the image side surface S2 is concave near the optical axis. The second lens L2 has a positive refractive power. Both the object side surface S3 and the image side surface S4 of the second lens L2 are convex near the optical axis. The third lens L3 has a positive refractive power. The object side surface S5 of the third lens L3 is convex near the optical axis, and the image side surface S6 is concave near the optical axis. The fourth lens L4 has a positive refractive power. The object side surface S7 of the fourth lens L4 is convex near the optical axis, and the image side surface S8 is concave near the optical axis.

[0097] In Embodiment 1, the effective focal length, refractive index, and Abbe number of the receiving lens 10 are referenced with light of a wavelength of 0.9200 μm. The relevant parameters of the receiving lens 10 are shown in Table 1.

[0098] Among them, in Table 1 and the following Tables 3, 5, and 7, f is the effective focal length of the receiving lens 10, FNO is the aperture value (F value), θ is half of the maximum field of view angle of the receiving lens 10, H1y is half of the maximum linear dimension of the receiving surface of the receiver 20, Dm is the maximum effective clear aperture diameter of the object side surface S1 of the first lens L1, D is the entrance pupil diameter of the receiving lens 10, and TTL is the total optical length of the receiving lens 10.

[0099] In addition, regarding the parameters in the column of thickness d in Table 1 and the following Tables 3, 5, and 7, each lens includes two thickness parameters from top to bottom. The first thickness parameter of each lens is the thickness of the lens on the optical axis, and the second thickness parameter of each lens is the distance from the image side surface of the lens to the object side surface of the next optical device in the optical axis direction.

[0100] Table 1

[0101]

[0102] The conic constants K and aspheric coefficients corresponding to the surfaces of each lens in Embodiment 1 are shown in Table 2.

[0103] Table 2

[0104] Surface number k A4 A6 A8 A10 A12 A14 A16 S7 -2.42E-01 -9.54E-04 1.27E-04 -2.63E-05 2.12E-06 -9.33E-08 1.62E-09 0 S8 1.60E+00 1.17E-03 -5.10E-05 -7.79E-06 8.59E-07 -6.98E-08 2.32E-09 0

[0105] Figure 2 is the field curvature curve graph of the receiving lens 10 in Embodiment 1. The abscissa of the field curvature curve graph represents the focus shift, and the ordinate represents the field of view angle. Figure 2 The focus shifts of the sagittal image plane and the meridional image plane of the astigmatism curve of the receiving lens 10 given are within ±0.12 mm at each wavelength, indicating that the astigmatism of the receiving lens 10 in this embodiment is small and the imaging quality is good.

[0106] Figure 3The distortion curve graph of the receiving lens 10 in the first embodiment. The abscissa of the distortion curve graph represents the distortion rate, and the ordinate represents the field of view angle. As Figure 3 shown, the distortion rate of the marginal field of view angle at a wavelength of 0.9200 μm given by the distortion curve is less than 16%, indicating that the distortion of the receiving lens 10 in this embodiment is well corrected and the imaging quality is good.

[0107] Figure 4 The modulation transfer function (MTF) curve graph of the receiving lens 10 in the first embodiment. Figure 4 The modulation transfer function (MTF) curves of the receiving lens 10 at the meridional image plane and the sagittal image plane at the image height positions of 0.00 mm, 0.36 mm, 0.72 mm, 0.00 mm, 1.08 mm, 1.44 mm, 1.80 mm, 2.16 mm, 2.52 mm, 2.88 mm, 3.24 mm, 3.60 mm, and 3.70 mm are given. Among them, the solid line is the MTF curve of the meridional image plane, and the dashed line is the MTF curve of the sagittal image plane. Since there are a large number of lines, some lines in the figure overlap. However, by combining Figure 4 it can be found that when the maximum field of view angle is 17 lp / mm, the MTF value > 0.58, and the imaging quality of the receiving lens 10 in the first embodiment is good.

[0108] Figure 5 The relative illumination curve graph of the receiving lens 10 in the first embodiment. Among them, the illumination of the 0° field of view is 1, and the illumination of the marginal field of view is as close to 1 as possible. The flatter the relative illumination curve changes, the more uniform the light distribution between the middle region and the edge region projected onto the receiving surface M, and the better the imaging quality. According to Figure 5 it can be seen that before the field of view of 2.96, the relative illumination of the receiving lens 10 > 82%, and the imaging quality of the receiving lens 10 in the first embodiment is good.

[0109] According to Figures 2 - 5 it can be known that the receiving lens 10 in the first embodiment can achieve good imaging effects.

[0110] Second Embodiment

[0111] The structural schematic diagram of the receiving lens 10 in this embodiment is referred to Figure 6 as shown. The receiving lens 10 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a filter SL arranged in sequence from the object side to the image side along the optical axis. The receiving surface M is located on the side of the filter SL away from the fourth lens L4. The aperture stop ST is arranged between the image side surface S4 of the second lens L2 and the object side surface S5 of the third lens L3. The filter SL is a band-pass filter SL.

[0112] Among them, the first lens L1 has a negative refractive power. The object side S1 of the first lens L1 is convex near the optical axis, and the image side S2 is concave near the optical axis. The second lens L2 has a positive refractive power. Both the object side S3 and the image side S4 of the second lens L2 are convex near the optical axis. The third lens L3 has a positive refractive power. The object side S5 of the third lens L3 is convex near the optical axis, and the image side S6 is concave near the optical axis. The fourth lens L4 has a positive refractive power. The object side S7 of the fourth lens L4 is convex near the optical axis, and the image side S8 is concave near the optical axis.

[0113] In Embodiment 2, the effective focal length, refractive index, and Abbe number of the receiving lens 10 are referenced with light of a wavelength of 0.9200 μm. The relevant parameters of the receiving lens 10 are shown in Table 3.

[0114] Table 3

[0115]

[0116]

[0117] The conic constants K and aspheric coefficients corresponding to the surfaces of each lens in Embodiment 2 are shown in Table 4.

[0118] Table 4

[0119] Surface number k A4 A6 A8 A10 A12 A14 A16 S7 -3.70E-01 -8.95E-04 1.13E-04 -2.49E-05 2.09E-06 -9.58E-08 1.72E-09 0 S8 1.65E+00 9.50E-04 -5.24E-05 -1.01E-05 1.08E-06 -7.63E-08 2.33E-09 0

[0120] Figure 7 is the field curvature curve graph of the receiving lens 10 in Embodiment 2. Figure 7 The focal point offsets of the sagittal image plane and the meridional image plane of the astigmatism curve of the receiving lens 10 given at each wavelength are all within ±0.12 mm, indicating that the astigmatism of the receiving lens 10 in this embodiment is small and the imaging quality is good.

[0121] Figure 8 is the distortion curve graph of the receiving lens 10 in Embodiment 2. From Figure 8 the given distortion curve shows that the distortion rate of the edge field angle at a wavelength of 0.9200 μm is lower than 16%, indicating that the distortion of the receiving lens 10 in this embodiment is well corrected and the imaging quality is good.

[0122] Figure 9 is the modulation transfer function (MTF) curve graph of the receiving lens 10 in Embodiment 2. Figure 9The modulation transfer function (MTF) curves of the receiving lens 10 given at the meridional image plane and the sagittal image plane at image height positions of 0.00 mm, 0.36 mm, 0.72 mm, 0.00 mm, 1.08 mm, 1.44 mm, 1.80 mm, 2.16 mm, 2.52 mm, 2.88 mm, 3.24 mm, 3.60 mm, and 3.70 mm are shown. Among them, the solid line is the MTF curve of the meridional image plane, and the dashed line is the MTF curve of the sagittal image plane. Combining Figure 4 it can be found that when the maximum field of view angle is 17 lp / mm, the MTF value > 0.64, and the imaging quality of the receiving lens 10 in the second embodiment is good.

[0123] Figure 10 The relative illumination curve of the receiving lens 10 in the second embodiment is shown. According to Figure 10 it can be seen that before the field of view of 2.96, the relative illumination of the receiving lens 10 > 85%, and the imaging quality of the receiving lens 10 in the second embodiment is good.

[0124] According to Figures 7 - 10 it can be known that the receiving lens 10 in the second embodiment can achieve good imaging effects.

[0125] Embodiment Three

[0126] The structural schematic diagram of the receiving lens 10 in this embodiment is shown in Figure 11 the figure. The receiving lens 10 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a filter SL arranged in sequence from the object side to the image side along the optical axis. The receiving surface M is located on the side of the filter SL away from the fourth lens L4. The aperture stop ST is arranged between the image side surface S2 of the first lens L1 and the object side surface S3 of the second lens L2. The filter SL is a band-pass filter SL.

[0127] Among them, the first lens L1 has a negative refractive power. The object side surface S1 of the first lens L1 is convex near the optical axis, and the image side surface S2 is concave near the optical axis. The second lens L2 has a positive refractive power. The object side surface S3 of the second lens L2 is convex near the optical axis, and the image side surface S4 is concave near the optical axis. The third lens L3 has a positive refractive power. The object side surface S5 of the third lens L3 is convex near the optical axis, and the image side surface S6 is concave near the optical axis. The fourth lens L4 has a positive refractive power. The object side surface S7 of the fourth lens L4 is convex near the optical axis, and the image side surface S8 is concave near the optical axis.

[0128] For the receiving lens 10 in Embodiment Three, the effective focal length, refractive index, and Abbe number are referenced with light rays of a wavelength of 0.9200 gm. The relevant parameters of the receiving lens 10 are shown in Table 5.

[0129] Table 5

[0130]

[0131]

[0132] In Example 3, the conic constants K and aspheric coefficients corresponding to the surfaces of each lens are shown in Table 6.

[0133] Table 6

[0134] Surface number k A4 A6 A8 A10 A12 A14 A16 S7 -7.97E-01 -4.10E-04 7.34E-05 -2.05E-05 1.63E-06 -8.08E-08 1.69E-09 0 S8 3.88E+00 8.09E-04 -9.58E-05 3.31E-06 -1.79E-06 1.34E-07 -3.24E-09 0

[0135] Figure 12 is the field curvature curve of the receiving lens 10 in Example 3. Figure 12 The focus offsets of the astigmatism curves of the receiving lens 10 given at each wavelength between the sagittal image plane and the meridional image plane are within ±0.16 mm, indicating that the astigmatism of the receiving lens 10 in this example is small and the imaging quality is good.

[0136] Figure 13 is the distortion curve of the receiving lens 10 in Example 3. From Figure 13 The distortion curve given shows that the distortion rate of the marginal field angle at a wavelength of 0.9200 μm is less than 3%, indicating that the distortion of the receiving lens 10 in this example is well corrected and the imaging quality is good.

[0137] Figure 14 is the modulation transfer function (MTF) curve of the receiving lens 10 in Example 3. Figure 14 The modulation transfer function (MTF) curves of the meridional image plane and the sagittal image plane of the receiving lens 10 given at image height positions of 0.00 mm, 0.36 mm, 0.72 mm, 0.00 mm, 1.08 mm, 1.44 mm, 1.80 mm, 2.16 mm, 2.52 mm, 2.88 mm, 3.24 mm, 3.60 mm, and 3.70 mm are shown. Among them, the solid line is the MTF curve of the meridional image plane, and the dashed line is the MTF curve of the sagittal image plane. Since there are a large number of lines, some lines in the figure overlap. However, in combination with Figure 14 it can be found that when the maximum field angle is 17 lp / mm, the MTF value > 0.55, indicating that the imaging quality of the receiving lens 10 in Example 3 is good.

[0138] Figure 15 is the relative illumination curve of the receiving lens 10 in Example 3. According to Figure 15 it can be seen that before the field of view of 2.96, the relative illumination of the receiving lens 10 > 82%, indicating that the imaging quality of the receiving lens 10 in Example 3 is good.

[0139] According to Figures 12 - 15 it can be known that the receiving lens 10 in Example 3 can achieve good imaging effects.

[0140] Embodiment 4

[0141] The structural schematic diagram of the receiving lens 10 in this embodiment is referred to Figure 16 as shown. The receiving lens 10 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a filter SL arranged in sequence from the object side to the image side along the optical axis. The receiving surface M is located on the side of the filter SL away from the fourth lens L4. The aperture stop ST is arranged between the image side surface S4 of the second lens L2 and the object side surface S5 of the third lens L3. The filter SL is a band-pass filter SL.

[0142] Among them, the first lens L1 has a negative refractive power. The object side surface S1 of the first lens L1 is convex near the optical axis, and the image side surface S2 is concave near the optical axis. The second lens L2 has a positive refractive power. The object side surface S3 of the second lens L2 is convex near the optical axis, and the image side surface S4 is concave near the optical axis. The third lens L3 has a positive refractive power. The object side surface S5 of the third lens L3 is convex near the optical axis, and the image side surface S6 is concave near the optical axis. The fourth lens L4 has a positive refractive power. The object side surface S7 of the fourth lens L4 is convex near the optical axis, and the image side surface S8 is concave near the optical axis.

[0143] In Embodiment 4, the effective focal length, refractive index, and Abbe number of the receiving lens 10 are referenced with light of a wavelength of 0.9200 μm. The relevant parameters of the receiving lens 10 are shown in Table 7.

[0144] Table 7

[0145]

[0146] The conic constants K and aspheric coefficients corresponding to the surfaces of each lens in Embodiment 4 are shown in Table 8.

[0147] Table 8

[0148] Surface number k A4 A6 A8 A10 A12 A14 A16 S7 -1.87E-01 -7.34E-04 7.84E-05 -2.23E-05 1.99E-06 -1.01E-07 2.01E-09 0 S8 4.99E+00 8.93E-04 -2.37E-05 -1.04E-05 -1.43E-07 3.71E-08 -8.49E-10 0

[0149] Figure 17 is the field curvature curve graph of the receiving lens 10 in Embodiment 4. Figure 17 The focal point offsets of the sagittal image plane and the meridional image plane of the astigmatism curve of the receiving lens 10 given are within ±0.1 mm at each wavelength, indicating that the astigmatism of the receiving lens 10 in this embodiment is small and the imaging quality is good.

[0150] Figure 18 is the distortion curve graph of the receiving lens 10 in Embodiment 4. From Figure 18 the given distortion curve, it shows that the distortion rate of the marginal field angle at a wavelength of 0.9200 μm is less than 3%, indicating that the distortion of the receiving lens 10 in this embodiment is well corrected and the imaging quality is good.

[0151] Figure 19 The modulation transfer function (MTF) curve graph of the receiving lens 10 in the fourth embodiment Figure 19 The provided receiving lens 10 respectively gives the modulation transfer function (MTF) curves of the meridional image plane and the sagittal image plane at the image height positions of 0.00 mm, 0.36 mm, 0.72 mm, 0.00 mm, 1.08 mm, 1.44 mm, 1.80 mm, 2.16 mm, 2.52 mm, 2.88 mm, 3.24 mm, 3.60 mm, and 3.70 mm. Among them, the solid line is the MTF curve of the meridional image plane, and the dashed line is the MTF curve of the sagittal image plane. Due to the large number of lines, some lines in the figure overlap with each other, but combined Figure 19 it can be found that when the maximum field of view angle is 171 p / mm, the MTF value > 0.46, and the imaging quality of the receiving lens 10 in the fourth embodiment is good.

[0152] Figure 20 The relative illumination curve graph of the receiving lens 10 in the fourth embodiment. According to Figure 20 it can be seen that before the field of view of 2.96, the relative illumination of the receiving lens 10 > 83%, and the imaging quality of the receiving lens 10 in the fourth embodiment is good.

[0153] According to Figures 17 - 20 it can be known that the receiving lens 10 in the fourth embodiment can achieve good imaging effects.

[0154] In addition, it is worth mentioning that plastic lenses have good plasticity, and it is easy to process aspherical surfaces with complex surface shapes, so that the same lens can meet multiple optical requirements, which helps to save the number of lens groups. In the embodiment of the present application, the receiving lens 10 includes a lens made of glass material and a lens made of plastic; this combination of glass and plastic reduces the number of lenses of the receiving lens 10, can improve the light transmittance of the receiving lens 10 to a certain extent, and also facilitates the lenses of the receiving lens 10 to meet more imaging requirements, so that while the receiving lens 10 has a large receiving field of view angle, it has good imaging effects.

[0155] It can be understood that along the direction of the optical axis H from the object side to the image side, for the lens placed at the front end, due to thermal expansion, the light will be abnormally deflected, and the lens located at the rear end will continue to transmit the abnormally deflected light, and other abnormal deflections may also occur, resulting in a deterioration of the imaging effect. In the embodiment of the present application, the lenses in the first lens group 100 are all made of glass, and the lens in the second lens group 200 adjacent to the receiving surface M of the receiver 20 is made of plastic; in this way, while the first lens group 100 can receive the backscattered light with a large field of view angle and is less affected by thermal deformation and does not cause a change in the field of view, the overall length and volume of the second lens group 200 can be reduced, thereby reducing the length and volume of the receiving lens. AsFigure 1 , Figure 6 , Figure 11 and Figure 16 As shown in Figure 1 , Figure 6 , Figure 11 and Figure 16 , optionally, the fourth lens L4 is an aspherical lens. The fourth lens L4 can be made of plastic, and the remaining lenses in the receiving lens 10 are made of glass. The fourth lens L4 made of plastic is placed at the rear end. The fourth lens L4 has a small influence range on light, and can improve the imaging effect under the condition of hardly affecting the detection field of view.

[0156] In the drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components; in the description of the present application, it should be understood that if there are terms such as "upper", "lower", "left", "right", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and cannot be understood as a limitation of this patent. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0157] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A laser receiving module, characterized in that, The laser receiving module includes a receiver and a receiving lens. The receiver has a receiving surface. The receiving lens is used to receive the reflected return light of the target object and is arranged corresponding to the receiving surface so that the return light can reach the receiving surface; The receiving lens includes at least one lens having a refractive power for light rays, which are arranged in sequence from the object side to the image side along the optical axis. The receiving lens satisfies the conditional formula: 0.26 ≤ h / f ≤ 0.70, where f is the effective focal length of the receiving lens, and h is the maximum image height of the laser receiving module.

2. The laser receiving module according to claim 1, wherein The receiving lens satisfies at least one of the following conditions: (1) 0.9 ≤ F ≤ 1.1, where F is the F-number of the receiving lens; (2) 5.0 mm ≤ f ≤ 15.38 mm; (3) 3.5 mm ≤ h ≤ 4 mm; (4) 10.0° ≤ CRA ≤ 20.0°, where CRA is the angle between the chief ray entering the receiving surface and the optical axis; (5) 7.5 ≤ TTL / h ≤ 8.0, where TTL is the distance between the object side surface of the lens of the receiving lens facing the target object and the image side surface of the lens facing the receiving surface in the optical axis direction.

3. The laser receiving module according to claim 1, wherein The optical axis of the receiving lens passes through the geometric center of the receiving surface; The receiving lens satisfies the conditional formula: 1 ≤ Lx / Ly ≤ 5, where Lx is the size of the receiving surface in the horizontal direction, and Ly is the size of the receiving surface in the vertical direction.

4. The laser receiving module according to claim 1, wherein The receiving lens includes a first lens group, a diaphragm, and a second lens group, which are arranged in sequence from the object side to the image side along the optical axis; The first lens group includes at least one lens having a refractive power for light rays. The first lens group is used to deflect light rays to condense the light rays; The second lens group includes at least one lens having a refractive power for light rays. The second lens group is used to converge the light rays to the receiving surface and correct aberration.

5. The laser receiving module according to claim 4, wherein: The first lens group includes a first lens and a second lens, which are arranged in sequence from the object side surface to the image side surface along the optical axis. The first lens has a negative refractive power, and the second lens has a positive refractive power; The second lens group includes a third lens and a fourth lens, which are arranged in sequence from the object side surface to the image side surface along the optical axis. Both the third lens and the fourth lens have a positive refractive power.

6. The laser receiving module according to claim 5, characterized in that, The receiving lens satisfies the conditional formula: 0.45 ≤ h / f ≤ 0.70; The object side surface of the first lens is convex near the optical axis, and the image side surface is concave near the optical axis. The focal length of the first lens is f1, and -11.0 mm ≤ f1 ≤ -11.7 mm; The object side surface and the image side surface of the second lens are both convex near the optical axis. The focal length of the second lens is f2, and 17.9 mm ≤ f2 ≤ 18.5 mm; The object side surface of the third lens is convex near the optical axis, and the image side surface is concave near the optical axis. The focal length of the third lens is f3, and 16.7 mm ≤ f3 ≤ 17.5 mm; The object side surface of the fourth lens is convex near the optical axis, and the image side surface is concave near the optical axis. The focal length of the fourth lens is f4, and 17.2 mm ≤ f4 ≤ 17.9 mm.

7. The laser receiving module according to claim 4, wherein: The receiving lens satisfies the conditional formula: 0.26 ≤ h / f ≤ 0.50; The first lens group includes a first lens, and the second lens group includes a second lens, a third lens, and a fourth lens arranged in sequence from the object side to the image side along the optical axis; The first lens has a negative refractive power, and the object side of the first lens is convex near the optical axis and the image side is concave near the optical axis. The focal length of the first lens is f1, -52.5 mm ≤ f1 ≤ -51.0 mm; The second lens has a positive refractive power, and the object side of the second lens is convex near the optical axis and the image side is concave near the optical axis. The focal length of the second lens is f2, 22.0 mm ≤ f2 ≤ 22.9 mm; The third lens has a positive refractive power, and the object side of the third lens is convex near the optical axis and the image side is concave near the optical axis. The focal length of the third lens is f3, 33.3 mm ≤ f3 ≤ 35.5 mm; The fourth lens has a positive refractive power, and the object side of the fourth lens is convex near the optical axis and the image side is concave near the optical axis. The focal length of the fourth lens is f4, 19.0 mm ≤ f4 ≤ 19.8 mm.

8. The laser receiving module according to claim 4, wherein: The receiving lens satisfies the conditional formula 0.26 ≤ h / f ≤ 0.50; The first lens group includes a first lens and a second lens arranged in sequence from the object side to the image side along the optical axis; the second lens group includes a third lens and a fourth lens arranged in sequence from the object side to the image side along the optical axis; The first lens has a negative refractive power, and the object side of the first lens is convex near the optical axis and the image side is concave near the optical axis. The focal length of the first lens is f1, -48.0 mm ≤ f1 ≤ -46.5 mm; The second lens has a positive refractive power, and the object side of the second lens is convex near the optical axis and the image side is concave near the optical axis. The focal length of the second lens is f2, 22.0 mm ≤ f2 ≤ 22.9 mm; The third lens has a positive refractive power, and the object side of the third lens is convex near the optical axis and the image side is concave near the optical axis. The focal length of the third lens is f3, 35.3 mm ≤ f3 ≤ 37.5 mm; The fourth lens has a positive refractive power, and the object side of the fourth lens is convex near the optical axis and the image side is concave near the optical axis. The focal length of the fourth lens is f4, 18.0 mm ≤ f4 ≤ 19.8 mm.

9. The laser receiving module according to any one of claims 5-8, characterized in that, The fourth lens is an aspherical lens; The fourth lens is made of plastic, and the remaining lenses in the receiving lens are made of glass.

10. A lidar, characterized in that, Including: A laser emitting module for emitting detection light to detect a target object; And The laser receiving module according to any one of claims 1-9 above, the laser receiving module being used to receive the echo light formed by the target object reflecting the detection light.

Images