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 receiving lens comprises a first lens group, a diaphragm and a second lens group which are sequentially arranged from the object side to the image side along the optical axis, and the first lens group has negative bending force and is used for receiving and deflecting echo light, so that edge light penetrates through the diaphragm at a small angle and is projected to the second lens group; the second lens group has a positive meandering force and is used for converging the echo light to the receiving surface of the receiver and correcting aberration; the receiving lens comprises a lens made of a glass material and a lens made of plastic, so that the lenses of the receiving lens can meet more imaging requirements, the number of the lenses of the receiving lens is reduced, the light transmittance of the receiving lens is improved, and the first lens group and the second lens group are combined to adjust light, so that the imaging quality is improved. Therefore, the receiving lens has a good imaging effect while having a large receiving field angle.

Description

Technical Field

[0001] This application relates to the technical field of lidar, and particularly 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 towards the target object. The receiving module receives the echo beam reflected by the target object and outputs a corresponding electrical signal. 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, thereby realizing the detection function.

[0003] In related technologies, the lenses of the laser receiving module in a lidar are all made of glass, and the cost is relatively high. Summary of the Invention

[0004] The embodiments of this application provide a laser receiving module and a lidar, which can solve the problem of the relatively small receiving field of view angle of the laser receiving module.

[0005] In a first aspect, the embodiments of this application provide a laser receiving module, which includes a receiver and a receiving lens. The receiver has a receiving surface for receiving the echo light reflected by the target object;

[0006] The receiving lens includes a first lens group, a diaphragm, and a second lens group arranged in sequence from the object side to the image side along the optical axis. The first lens group has a negative refractive power and includes at least one lens. The first lens group is used to receive the echo light and deflect it so that the marginal rays pass through the diaphragm at a small angle and are projected onto the second lens group. The second lens group has a positive refractive power and includes at least one lens. The second lens group is used to converge the echo light to the receiving surface and correct aberration;

[0007] The receiving lens includes lenses made of glass material and lenses made of plastic.

[0008] In some exemplary embodiments, 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. Both the third lens and the fourth lens have positive refractive power. The third lens is a spherical mirror, and the fourth lens is an aspherical lens. The fourth lens is made of plastic.

[0009] In some exemplary embodiments, the third lens has a positive refractive power. The object side surface and the image side surface of the third lens are both convex near the optical axis. The focal length of the third lens is f3, and 9.7mm ≤ f3 ≤ 11.6mm.

[0010] In some exemplary embodiments, the fourth lens has a positive refractive power. The object side surface and the image side surface of the fourth lens are both convex near the optical axis. The focal length of the fourth lens is f4, and 6.9 mm ≤ f4 ≤ 9.2 mm.

[0011] In some exemplary embodiments, the second lens group includes a third lens, a fifth lens, and a fourth lens arranged in sequence from the object side to the image side along the optical axis. The fifth lens is a spherical lens.

[0012] The third lens has a positive refractive power. The object side surface and the image side surface of the third lens are both convex near the optical axis. The focal length of the third lens is f3, and 10 mm ≤ f3 ≤ 13.5 mm.

[0013] The fourth lens has a positive refractive power. The object side surface and the image side surface of the fourth lens are both convex near the optical axis. The focal length of the fourth lens is f4, and 8.5 mm ≤ f4 ≤ 9.2 mm.

[0014] The fifth lens has a positive refractive power. The object side surface of the fifth lens is convex near the optical axis, and the image side surface is concave near the optical axis. The focal length of the fifth lens is f5, and 25 mm ≤ f5 ≤ 27 mm.

[0015] In some exemplary embodiments, 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.

[0016] The first lens has a negative refractive power. 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 -10.7 mm ≤ f1 ≤ -11.5 mm.

[0017] The second lens has a negative refractive power. The object side surface of the second lens is convex near the optical axis, and the image side surface is concave near the optical axis. The focal length of the second lens is f2, and -13.6 mm ≤ f2 ≤ -10.9 mm.

[0018] In some exemplary embodiments, the receiving lens satisfies the conditional formula: 1.22 ≤ h / f ≤ 1.48, where f is the effective focal length of the receiving lens, and h is the maximum image height of the laser receiving module.

[0019] In some exemplary embodiments, the optical axis of the receiving lens passes through the geometric center of the receiving surface. The size H of the receiving surface of the receiver includes H1x and H1y. H1x is the size of the receiving surface in the horizontal direction, and H1y is the size of the receiving surface in the vertical direction. 4 / 3 ≤ H1x / H1y ≤ 2.

[0020] In some exemplary embodiments, the receiving lens satisfies at least one of the following conditions:

[0021] (1) 0.9 ≤ F ≤ 1.1, where F is the F-number of the receiving lens;

[0022] (2) 2.3 mm ≤ f ≤ 3.00 mm;

[0023] (3) 2.5 mm ≤ h ≤ 4 mm;

[0024] (4) 9.2 ≤ TTL / D ≤ 10.4, where TTL is the distance between the object side of the lens facing the target of the receiving lens and the image side of the lens facing the receiving surface in the optical axis direction, and D is the maximum effective aperture of the object side of the lens of the receiving lens facing the target;

[0025] (5) 2.54 mm ≤ TTL ≤ 28.6 mm.

[0026] In a second aspect, an embodiment of the present application provides a lidar, which includes a laser emission module and the laser receiving module as described above. The laser emission module is configured to emit detection light to detect a target object, and the laser receiving module is configured to receive the echo light formed by the target object reflecting the detection light.

[0027] Based on the laser receiving module and lidar of the embodiments of the present application, by setting the first lens group to have a negative refractive power, the receiving lens can receive incident light at a large angle, so that the laser receiving module has a large receiving field of view; by setting the second lens group to have a positive refractive power, the light is adjusted to converge to the receiving surface of the receiver at a small angle and the aberration is corrected. In this way, the receiving lens can adjust the light by combining the first lens group and the second lens group, so that while having a large receiving field of view, the receiving lens has a good imaging effect. In addition, the lenses of the receiving lens adopt a combination of glass and plastic; among them, glass is not prone to thermal deformation, and its influence on the rear lens after being affected by heat is small, so that the detection field of view of the laser receiving module can be ensured to be relatively stable. Plastic has a low cost and is easy to process spherical and aspherical surfaces to meet the corresponding optical performance requirements; therefore, adopting a combination of glass and plastic can save costs while meeting the optical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] 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 use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0029] Figure 1Schematic diagram of the lens of the receiving lens in the first embodiment;

[0030] Figure 2 Field curvature curve graph of the receiving lens in the first embodiment;

[0031] Figure 3 Modulation transfer function (MTF) curve graph of the receiving lens in the first embodiment;

[0032] Figure 4 Relative illumination curve graph of the receiving lens in the first embodiment;

[0033] Figure 5 Schematic diagram of the lens of the receiving lens in the second embodiment;

[0034] Figure 6 Field curvature curve graph of the receiving lens in the second embodiment;

[0035] Figure 7 Modulation transfer function (MTF) curve graph of the receiving lens in the second embodiment;

[0036] Figure 8 Relative illumination curve graph of the receiving lens in the second embodiment;

[0037] Figure 9 Schematic diagram of the lens of the receiving lens in the third embodiment;

[0038] Figure 10 Field curvature curve graph of the receiving lens in the third embodiment;

[0039] Figure 11 Modulation transfer function (MTF) curve graph of the receiving lens in the third embodiment;

[0040] Figure 12 Relative illumination curve graph of the receiving lens in the third embodiment.

[0041] Reference numerals:

[0042] 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; L5. Fifth lens; SL. Filter; SP. Protective glass; M. Receiving surface; ST. Diaphragm. Detailed implementation manners

[0043] In order to make the purpose, 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.

[0044] The inventors have found that the ranging performance of on-vehicle lidar is affected by various factors, such as power, stray light, the size of the receiving aperture, focal length, and field of view angle. The transceiver lens of lidar generally adopts an all-glass structure, but it has problems such as high cost, complex structure, and long optical length. The embodiment of the present application provides a solution for a large field-of-view lidar transceiver lens with a hybrid glass-plastic structure.

[0045] The lidar in the embodiment of the present application includes a laser emission module and a laser reception module. The laser emission module is used to emit detection light to detect a target object, and the laser reception module is used to receive the echo light formed by the target object reflecting the detection light.

[0046] Specifically, the laser emission module includes a transmitter and a transmitting lens. The transmitter is used to emit detection light, and the transmitting lens is arranged 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 rays to diverge the detection light and project it onto a target object within the transmitting field-of-view angle region. As Figures 1 - 12 shown, it is a schematic structural diagram and corresponding parameters of the laser reception module in each embodiment of the present application. In each embodiment of the present application, the laser reception module includes a receiver 20 and a receiving lens 10. The receiver 20 has a receiving surface M. The receiving lens 10 is arranged corresponding to the receiving surface M. The receiving lens 10 is used to receive the echo light reflected by a target object located within the receiving field-of-view angle region, and the receiving lens 10 includes at least one lens that has a bending force on light rays to converge the echo light to the receiving surface M. The receiving surface M is used to receive the echo light reflected by the target object. The region covered by the transmitting field-of-view angle of the laser emission module of the lidar and the region covered by the receiving field-of-view angle of the laser reception module at least partially overlap, so that when the laser emission module emits outgoing laser to a target object located within the overlapping detection region, the echo light after being reflected by the target object can be received by the laser reception module.

[0047] The receiving lens 10 includes a first lens group 100, a stop ST, and a second lens group 200 that are sequentially arranged along the optical axis O from the object side to the image side. The optical axis O is the optical axis O of the lens in the first lens group 100 that is closest to the target object, and this lens is coaxial with the other lenses in the first lens group 100, the stop ST, and the lenses in the second lens group 200.

[0048] Among them, the first lens group 100 has a negative refractive power and includes at least one lens. The first lens group 100 is configured to receive the reflected light and deflect the reflected light, so that the marginal rays pass through the aperture ST at a smaller angle and are projected onto the second lens group 200. In this way, when the reflected light is projected into the first lens group 100, the first lens group 100 can condense the reflected light and adjust the reflected light entering the first lens group 100 to be projected onto the second lens group 200 at a small angle, which helps the subsequent optical elements to further process the reflected light. At the same time, in cooperation with the aperture ST, by adjusting the aperture of the aperture ST, the light flux entering the second lens group 200 can be adjusted to prevent the marginal rays passing through the first lens group 100 from interfering with the subsequent lenses.

[0049] The second lens group 200 has a positive refractive power and includes at least one lens to adjust the light rays to be projected onto the receiving surface M of the receiver 20 at a small angle. The second lens group 200 is configured to converge the reflected light onto the receiving surface M and correct aberrations. In this way, the first lens group 100 can receive incident light at a large angle, and by combining the first lens group 100 and the second lens group 200 to adjust the light rays, the receiving lens 10 has a large receiving field of view angle while having a good imaging effect.

[0050] The glass lens has good heat resistance stability and is not easily deformed by heat, and has good optical stability. However, the plasticity of the glass lens is poor and it is usually processed into a spherical lens. The spherical lens has 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, making it difficult for the glass lens to meet various optical performances. In the related art, the receiving lens 10 of the lidar all uses glass lenses, which not only has a high cost but also is difficult to achieve a good imaging effect. Of course, the imaging performance can also be improved by increasing the number of lenses, but on the one hand, this will further increase the cost, and on the other hand, it will also increase the volume of the receiving lens 10.

[0051] The plastic lens has good plasticity and can be processed into an aspherical surface with a complex surface shape, so that the same lens can meet various 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. By using a combination of glass and plastic, the number of lenses of the receiving lens 10 is reduced, the light transmittance of the receiving lens 10 is improved, and it is also convenient for the lenses of the receiving lens 10 to meet more imaging requirements, so that the receiving lens 10 has a large receiving field of view angle while having a good imaging effect.

[0052] The lenses in the first lens group 100 are all made of glass, which makes the optical performance of the first lens group 100 stable and not easily affected by temperature. It can be understood that along the optical axis O from the object side to the image side, for the lens placed at the front end, due to thermal expansion, the light rays will deflect abnormally, and the lens located at the rear end will continue to transmit the abnormally deflected light rays, and other abnormal deflections may also occur, resulting in a deteriorated imaging effect. When the first lens group 100 made of glass is placed at the front end, the first lens group 100 is not easily thermally deformed, and its influence on the rear-end lens after being affected by heat is small. Therefore, the detection field of view of this laser receiving module can be guaranteed to be relatively stable. Among them, the lenses in the first lens group 100 can all be glass spherical lenses.

[0053] Optionally, as Figure 1 , Figure 5 and Figure 9 shown, the first lens group 100 includes a first lens L1 and a second lens L2 arranged in sequence along the optical axis O from the object side to the image side. The first lens L1 has a negative refractive power. The object side surface of the first lens L1 is convex near the optical axis O, and the image side surface is concave near the optical axis O. The focal length of the first lens L1 is f1, and -10.7mm ≤ f1 ≤ -11.5mm, so that large-angle marginal light rays can enter the first lens L1, thereby enabling the receiving lens 10 to have a large receiving field angle. The first lens L1 can also adjust the light rays so that the light rays are transmitted to the second lens L2, and further enable the light rays to propagate in a small range in the rear-end lens, which helps to reduce the size of the rear-end lens.

[0054] The second lens L2 has a negative refractive power. The object side surface of the second lens L2 is convex near the optical axis O, and the image side surface is concave near the optical axis O. The focal length of the second lens L2 is f2, and -13.6mm ≤ f2 ≤ -10.9mm. The second lens L2 further adjusts the light rays so that the angle of the light rays incident on the second lens group 200 is smaller, and further reduces the included angle of the light rays projected onto the receiving surface M. The solution of combining the first lens L1 and the second lens L2 in the embodiment of the present application is beneficial to improving the overall field of view angle of this laser receiving module.

[0055] The second lens group 200 includes lenses made of plastic, and the lenses made of plastic are placed at the rear end in the length direction of the receiving lens 10. Even when the lenses made of plastic are deformed due to the influence of thermal expansion, the influence on the field of view size is relatively small. Optionally, the second lens group 200 includes at least two lenses, where the lens adjacent to the receiving surface M is made of plastic, and the remaining lenses are made of glass. In this way, the influence of lens thermal expansion on the optical path can be minimized.

[0056] Optionally, in some embodiments, as Figure 1 and Figure 5As shown, 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 O. The third lens L3 has a positive refractive power, the third lens L3 is a spherical mirror and is made of glass; the object side surface and the image side surface of the third lens L3 are both convex near the optical axis O, and the focal length of the third lens L3 is f3, where 9.7 mm ≤ f3 ≤ 11.6 mm. The fourth lens L4 has a positive refractive power, the fourth lens L4 is an aspherical lens and is made of plastic; the object side surface and the image side surface of the fourth lens L4 are both convex near the optical axis O, and the focal length of the fourth lens L4 is f4, where 6.9 mm ≤ f4 ≤ 9.2 mm. The propagation direction of the light is further corrected by these two lenses, the third lens L3 and the fourth lens L4, so that the marginal rays are projected onto the receiving surface M of the receiver 20 at a small angle, and at the same time, aberrations such as astigmatism and field curvature are further corrected.

[0057] Optionally, in some other embodiments, as Figure 9 As shown, the second lens group 200 includes a third lens L3, a fifth lens L5 and a fourth lens L4 arranged in sequence from the object side to the image side along the optical axis O. The third lens L3 has a positive refractive power, the third lens L3 is a spherical mirror and is made of glass; the object side surface and the image side surface of the third lens L3 are both convex near the optical axis O, and the focal length of the third lens L3 is f3, where 10 mm ≤ f3 ≤ 13.5 mm. The fifth lens L5 has a positive refractive power, the fifth lens L5 is a spherical mirror and is made of glass; the object side surface of the fifth lens L5 is convex near the optical axis O and the image side surface is concave near the optical axis, and the focal length of the fifth lens L5 is f5, where 25 mm ≤ f5 ≤ 27 mm. The fourth lens L4 has a positive refractive power, the fourth lens L4 is an aspherical mirror and is made of plastic; the object side surface and the image side surface of the fourth lens L4 are both convex near the optical axis O, and the focal length of the fourth lens L4 is f4, where 8.5 mm ≤ f4 ≤ 9.2 mm. Among them, the third lens L3 and the fifth lens L5 are in the middle region of the receiving lens 10 and can correct the light; the fifth lens L5 can slightly diverge the light when emitting the back-reflected light, so that the marginal rays can reach the fourth lens L4 at a small angle, so that the marginal rays are projected onto the receiving surface M of the receiver 20 at a small angle when the fourth lens L4 converges the light. In this way, both the aberrations such as astigmatism and field curvature of the back-reflected light can be corrected, and the back-reflected light can be received by the receiver 20 with higher efficiency.

[0058] In the embodiments of the present application, in the laser receiving module, the size of the receiver 20 in a single direction is H, the focal length of the receiving lens 10 is f, and the receiving field of view angle of the laser receiving 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 the laser receiving 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 the laser receiving module is also correspondingly determined; at the same time, the half receiving field of view angle θ (radian value) of each laser receiving module is inversely proportional to the focal length f of the receiving lens 10. Therefore, by reducing the focal length f of the receiving lens 10 in the laser receiving module, the above half field of view angle θ can be increased, that is, the receiving field of view angle Θ of the laser receiving module can be increased.

[0059] Optionally, the laser receiving module satisfies the conditional formula: 1.22 ≤ h / f ≤ 1.48. By controlling h / f within the range of 1.22 to 1.48, the half field of view angle of the laser receiving module is between 70° and 85°, that is, the field of view angle of the laser receiving module is between 140° and 170°, so that the lidar has a larger 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 2.50 mm and 3.00 mm, and the receiver 200 falls on the focal plane of the receiving lens 10, so that the field of view angle of the laser receiving module is between 140° and 170°. 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: 2.5 mm ≤ h ≤ 4 mm, and based on this, correspondingly, the focal length f of the laser receiving module satisfies: 2.3 mm ≤ f ≤ 3.00 mm.

[0060] As described above, the optical axis O 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 H1x and H1y, where H1x is the size of the receiving surface M in the horizontal direction, and H1y is the size of the receiving surface M in the vertical direction. The laser receiving module satisfies: 4 / 3 ≤ H1x / H1y ≤ 2. From the above formula, it can be seen that when the focal length f is determined, the half field of view angle (or field of view angle) of the laser receiving module is positively correlated with the maximum image height; the above setting is designed to ensure that the field of view angle of the laser receiving module in the horizontal direction is greater than the field of view angle in the vertical direction, so as to obtain more target information in the horizontal direction, and the ratio of the field of view angle of the laser receiving module in the horizontal direction to the field of view angle in the vertical direction is between 4 / 3 and 2.

[0061] Optionally, the receiving lens 10 satisfies: 0.9 ≤ F ≤ 1.1, where F is the F-number of the receiving lens 10. Among them, the entrance pupil diameter D of the receiving lens 10 satisfies: D = f / F. In the embodiments of the present application, the F-number of the receiving lens is compressed to 0.9 to 1.1. When the receiving lens 10 has a small focal length, the receiving lens 10 can also have a relatively large entrance pupil diameter D, thereby increasing the amount of incident light. In addition, by setting the second lens group 200 to include an aspherical lens, the receiving lens can have a large effective aperture, thereby increasing the amount of incident light and ensuring a relatively high marginal illuminance, even if the relative illuminance change is more gentle. By setting the F-number of the receiving lens 10 to be relatively small, the receiving lens 10 has a relatively large luminous flux. When the receiving lens 10 has a large receiving angle of view, more light can reach the receiving surface M of the receiver 20, which helps to improve the imaging effect.

[0062] Optionally, the receiving lens 10 satisfies: 9.2 ≤ TTL / D ≤ 10.4, 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 direction of the optical axis O, that is, the total optical length of the receiving lens 10, and D is the entrance pupil diameter. By setting TTL / D in the range of 9.2 to 10.4, it is convenient to meet the requirement of the luminous flux entering the receiving lens 10 while preventing the head size of the receiving lens 10 from being too large, and the size of the entire receiving lens 10 in the direction of the optical axis O is appropriate, which is convenient to meet the light adjustment requirements of the multiple lenses of the receiving lens 10.

[0063] Furthermore, 2.54 mm ≤ TTL ≤ 28.6 mm, so that the total optical length of the receiving lens 10 is within a suitable range, which can not only meet the distance requirements between the multiple lenses of the receiving lens, but also prevent the size of the receiving lens 10 from being too large.

[0064] The receiving lens 10 further includes a lens barrel. 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 installed 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.

[0065] 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 bandwidth of the return light rays, so as 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 for protecting the receiver 20. The filter SL and the protective glass SP can be assembled together with the respective lenses as a part of the receiving lens 10. For example, in some embodiments, the respective lenses in the receiving lens 10 are mounted in a 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 together. 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.

[0066] In the embodiments of the present application, the transmitting lens includes at least one lens having a bending force on light. The lens of the transmitting lens can include at least one of a glass lens and a plastic lens. Moreover, the surface type of the lens of the transmitting lens can also include at least one of a spherical surface and an aspherical surface. The embodiments of the present application do 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 may 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 formed by 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.

[0067] Hereinafter, with reference to the drawings and tables, the assembly structure of the receiving lens 10 in each specific embodiment of the present technical solution and the corresponding implementation results will be introduced in combination with specific numerical values.

[0068] The meanings of the marks shown in each embodiment are as follows.

[0069] S1, S3, S5, S7, S9, S11, S13 are the numbers of the object sides of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the filter SL, and the protective glass SP respectively, and S2, S4, S6, S8, S10, S12, S14 are the numbers of the image sides of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the filter SL, and the protective glass SP respectively.

[0070] 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:

[0071] Mathematical Formula 1:

[0072]

[0073] Wherein, K is the conic constant (Conic Conant), and "A2", "A4", "A6", "A8", "A10", "A12", "A14", "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 O; c is the curvature of the near optical axis O 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 along the optical axis O at a position with a height of r.

[0074] Embodiment 1

[0075] 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 O. 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 of the second lens L2 and the object side of the third lens L3. The filter SL is a band-pass filter.

[0076] 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 O, and the image side S2 is concave near the optical axis O. The second lens L2 has a negative refractive power. The object side S3 of the second lens L2 is convex near the optical axis O, and the image side S4 is concave near the optical axis O. The third lens L3 has a positive refractive power. Both the object side S5 and the image side S6 of the third lens L3 are convex near the optical axis O. The fourth lens L4 has a positive refractive power. Both the object side S7 and the image side S8 of the fourth lens L4 are convex near the optical axis O.

[0077] In Embodiment 1, the effective focal length, refractive index, and Abbe number of the receiving lens 10 are referenced with light having a wavelength of 0.9200 μm. The relevant parameters of the receiving lens 10 are shown in Table 1.

[0078] Among them, in Table 1 and Tables 3 and 5 below, 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 size of the receiving surface M of the receiver 20 in the vertical direction, D is the entrance pupil diameter of the receiving lens. TTL is the total optical length of the receiving lens 10. In addition, regarding the parameter of thickness d in Table 1 and Tables 3 and 5 below, 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 O, and the second thickness parameter of each lens is the distance from the object side to the image side of the lens in the optical axis direction to the next optical device.

[0079] Table 1

[0080]

[0081] The conic constants K and aspheric coefficients corresponding to the surfaces of each lens in Embodiment 1 are shown in Table 2.

[0082] Table 2

[0083]

[0084] Figure 2 is the field curvature curve of the receiving lens 10 in Embodiment 1. The abscissa of the field curvature curve 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.

[0085] Figure 3 is the modulation transfer function (MTF) curve of the receiving lens 10 in Embodiment 1. The closer the modulation transfer function MTF is to 1, the better the imaging effect. Figure 3 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. When the maximum field of view angle is 17 lp / mm, the MTF value > 0.45, indicating that the imaging quality of the receiving lens 10 in Embodiment 1 is good.

[0086] Figure 4 The relative illumination curve graph of the receiving lens 10 of Example 1, where the illumination of the 0° field of view is 1, and the illumination of the edge 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 area and the edge area projected onto the receiving surface M, and the better the imaging quality. According to Figure 4 It can be seen that the relative illumination of the receiving lens 10 is >80% before the field of view of 2.96, and the imaging quality of the receiving lens 10 of Example 1 is better.

[0087] According to Figures 2 - 4 It can be known that the receiving lens 10 in Example 1 can achieve good imaging effects.

[0088] Example 2

[0089] The structural schematic diagram of the receiving lens 10 in this embodiment is referred to Figure 5 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 O. 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 of the second lens L2 and the object side surface of the third lens L3. The filter SL is a band-pass filter.

[0090] 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 O, and the image side surface S2 is concave near the optical axis O. The second lens L2 has a negative refractive power. The object side surface S3 of the second lens L2 is convex near the optical axis O, and the image side surface S4 is concave near the optical axis O. The third lens L3 has a positive refractive power. The object side surface S5 and the image side surface S6 of the third lens L3 are both convex near the optical axis O. The fourth lens L4 has a positive refractive power. The object side surface S7 and the image side surface S8 of the fourth lens L4 are both convex near the optical axis O.

[0091] For the receiving lens 10 in Example 2, the effective focal length, refractive index, and Abbe number are referenced with light of a wavelength of 0.9200 μm. The relevant parameters of the receiving lens 10 are shown in Table 3.

[0092] Table 3

[0093]

[0094]

[0095] The conic constants K and aspheric coefficients corresponding to the surfaces of each lens in Example 2 are shown in Table 4.

[0096] Table 4

[0097]

[0098] Figure 6 It is the field curvature curve graph of the receiving lens 10 in the second embodiment. Figure 6 The given astigmatism curve of the receiving lens 10 shows that the focus offsets of the sagittal image plane and the meridional image plane at each wavelength are within 0.15 mm, indicating that the astigmatism of the receiving lens 10 in this embodiment is small and the imaging quality is good.

[0099] Figure 7 It is the modulation transfer function (MTF) curve graph of the receiving lens 10 in the second embodiment. Figure 7 The given modulation transfer function (MTF) curves of the receiving lens 10 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 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. When the maximum field of view angle is 17 lp / mm, the MTF value > 0.40, indicating that the imaging quality of the receiving lens 10 in the second embodiment is good.

[0100] Figure 8 It is the relative illumination curve graph of the receiving lens 10 in the second embodiment. According to Figure 8 it can be seen that the relative illumination of the receiving lens 10 is > 75% before the field of view of 2.96, indicating that the imaging quality of the receiving lens 10 in the second embodiment is good.

[0101] According to Figures 6 - 8 it can be known that the receiving lens 10 in the second embodiment can achieve good imaging effects.

[0102] Embodiment Three

[0103] The structural schematic diagram of the receiving lens 10 in this embodiment is referred to Figure 9 as shown. The receiving lens 10 includes a first lens L1, a second lens L2, a third lens L3, a fifth lens L5, a fourth lens L4, and a filter SL arranged in sequence from the object side to the image side along the optical axis O. 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 of the second lens L2 and the object side surface of the third lens L3. The filter SL is a band-pass filter.

[0104] 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 O, and the image side S2 is concave near the optical axis O. The second lens L2 has a negative refractive power. The object side S3 of the second lens L2 is convex near the optical axis O, and the image side S4 is concave near the optical axis O. The third lens L3 has a positive refractive power. Both the object side S5 and the image side S6 of the third lens L3 are convex near the optical axis O. The fifth lens L5 has a positive refractive power. The object side S9 of the fifth lens L5 is convex near the optical axis O, and the image side S10 is concave near the optical axis O. The fourth lens L4 has a positive refractive power. Both the object side S7 and the image side S8 of the fourth lens L4 are convex near the optical axis O.

[0105] In Embodiment 3, 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 5.

[0106] Table 5

[0107]

[0108]

[0109] For Embodiment 3, the conic constants K and aspheric coefficients corresponding to the surfaces of each lens are shown in Table 6.

[0110] Table 6

[0111]

[0112] Figure 10 is the field curvature curve graph of the receiving lens 10 in Embodiment 3. Figure 10 The given astigmatism curve of the receiving lens 10 shows that the focus offsets of the sagittal image plane and the meridional image plane at each wavelength are within 0.10 mm, indicating that the astigmatism of the receiving lens 10 in this embodiment is small and the imaging quality is good.

[0113] Figure 11 is the modulation transfer function (MTF) curve graph of the receiving lens 10 in Embodiment 3. Figure 11 The given modulation transfer function (MTF) curves of the meridional image plane and the sagittal image plane of the receiving lens 10 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 presented. 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. When the maximum field of view angle is at 17 lp / mm, the MTF value > 0.40, indicating that the imaging quality of the receiving lens 10 in Embodiment 3 is good.

[0114] Figure 12 The relative illuminance curve of the receiving lens 10 in the third embodiment. According to Figure 12 It can be seen that the relative illuminance of the receiving lens 10 is > 80% before the field of view of 2.96, and the imaging quality of the receiving lens 10 in the third embodiment is good.

[0115] According to Figures 10 - 12 It can be known that the receiving lens 10 in the third embodiment can achieve a good imaging effect.

[0116] In the attached drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components; in the description of this application, it should be understood that if there are terms such as "upper", "lower", "left", "right", etc. indicating the orientation or positional relationship, it is based on the orientation or positional relationship shown in the attached drawings. It is only for the convenience of describing this 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 attached 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.

[0117] The above is only the preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of this application shall be included in the protection scope of this 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 for receiving the reflected return light of the target object. The receiving lens includes a first lens group, a diaphragm, and a second lens group arranged in sequence from the object side to the image side along the optical axis. The first lens group has a negative refractive power and includes at least one lens. The first lens group is used to receive the return light and deflect it so that the marginal rays pass through the diaphragm at a small angle and are projected onto the second lens group. The second lens group has a positive refractive power and includes at least one lens. The second lens group is used to converge the return light to the receiving surface and correct aberration. The receiving lens includes lenses made of glass material and lenses made of plastic.

2. The laser receiving module according to claim 1, wherein The lenses in the first lens group are all made of glass, and the second lens group includes lenses made of plastic.

3. The laser receiving module according to claim 2, characterized in that, 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. Both the third lens and the fourth lens have positive refractive power. The third lens is a spherical lens, and the fourth lens is an aspherical lens. The fourth lens is made of plastic.

4. The laser receiving module according to claim 3, wherein The third lens has a positive refractive power. The object side surface and the image side surface of the third lens are both convex near the optical axis. The focal length of the third lens is f3, and 9.7 mm ≤ f3 ≤ 11.6 mm. The fourth lens has a positive refractive power. The object side surface and the image side surface of the fourth lens are both convex near the optical axis. The focal length of the fourth lens is f4, and 6.9 mm ≤ f4 ≤ 9.2 mm.

5. The laser receiving module according to claim 3, characterized in that, The second lens group includes a third lens, a fifth lens, and a fourth lens arranged in sequence from the object side to the image side along the optical axis. The fifth lens is a spherical lens. The third lens has a positive refractive power. The object side surface and the image side surface of the third lens are both convex near the optical axis. The focal length of the third lens is f3, and 10 mm ≤ f3 ≤ 13.5 mm. The fourth lens has a positive refractive power. The object side surface and the image side surface of the fourth lens are both convex near the optical axis. The focal length of the fourth lens is f4, and 8.5 mm ≤ f4 ≤ 9.2 mm. The fifth lens has a positive refractive power. The object side surface of the fifth lens is convex near the optical axis, and the image side surface is concave near the optical axis. The focal length of the fifth lens is f5, and 25 mm ≤ f5 ≤ 27 mm.

6. The laser receiving module according to claim 1, wherein, 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 first lens has a negative refractive power. 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 -10.7 mm ≤ f1 ≤ -11.5 mm. The second lens has a negative refractive power. The object side surface of the second lens is convex near the optical axis, and the image side surface is concave near the optical axis. The focal length of the second lens is f2, and -13.6 mm ≤ f2 ≤ -10.9 mm.

7. The laser receiving module according to claim 1, wherein, The receiving lens satisfies the conditional formula: 1.22 ≤ h / f ≤ 1.48, where f is the effective focal length of the receiving lens, and h is the maximum image height of the laser receiving module.

8. The laser receiving module according to claim 7, wherein The optical axis of the receiving lens passes through the geometric center of the receiving surface. The size H of the receiving surface of the receiver includes H1x and H1y. H1x is the size of the receiving surface in the horizontal direction, and H1y is the size of the receiving surface in the vertical direction. 4 / 3 ≤ H1x / H1y ≤ 2.

9. The laser receiving module according to claim 7, 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) 2.3 mm ≤ f ≤ 3.00 mm; (3) 2.5 mm ≤ h ≤ 4 mm; (4) 9.2 ≤ TTL / D ≤ 10.4, 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, and D is the maximum effective aperture of the object side of the lens of the receiving lens facing the target; (5) 2.54 mm ≤ TTL ≤ 28.6 mm.

10. A lidar, characterized in that, It includes: a laser emission module for emitting detection light to detect a target; and the laser receiving module according to any one of the above claims 1-9, the laser receiving module being configured to receive the echo light formed by the target reflecting the detection light.

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