Coaxial laser radar system, transmitting module, paraxial laser radar system and automobile

Abstract

The invention provides a coaxial laser radar system, a transmitting module, a paraxial laser radar system and an automobile. The coaxial laser radar system comprises a laser, a first lens group, a second lens group, a third lens group, a hole digging reflector and a receiver, the laser is used for emitting laser beams; the third lens group is used for carrying out fast axis compression on the laser beam to obtain first emergent light; the second lens group is used for performing fast axis divergence on the first emergent light to obtain second emergent light; the hole-digging reflecting mirror comprises a light through hole, a first surface and a second surface, the first surface faces the second lens group, and the second surface is aligned with the receiver; the first lens group is used for receiving the second emergent light passing through the light through hole, refracting the second emergent light and then emitting a third emergent light, and the second surface is used for reflecting the reflected light of the third emergent light into the receiver again. The hole digging size of the hole digging reflecting mirror can be effectively reduced, the receiving energy loss is reduced, the receiving efficiency is improved, and then the application performance of a radar system is improved.

Description

Technical Field

[0001] This invention relates to the field of lidar technology, and in particular to a coaxial lidar system, a transmitting module, a paraxial lidar system, and an automobile. Background Technology

[0002] A lidar system consists of two parts: a laser transmitting system and an echo receiving system. It mainly includes two types: paraxial lidar systems with separate transmit and receive capabilities and coaxial lidar systems. Coaxial lidar systems are widely used because they can reduce the size of the radar window and scanning mirror.

[0003] Existing coaxial lidar systems typically employ either a method of combining the two optical paths into a rotating mirror and viewing window by placing angled, perforated mirrors in front of the transmitting and receiving lenses, or a method of increasing the receiving lens aperture and using a perforated mirror behind the lens for beam combining. However, while these beam combining methods are simple to implement, they both result in significant energy loss during reception. Furthermore, the latter can even negate the performance gains from increasing the aperture, leading to suboptimal radar performance. Therefore, there is an urgent need for a novel lidar system optical path design to reduce energy loss during reception and effectively improve radar performance. Summary of the Invention

[0004] To achieve the above objectives, it is necessary to address the aforementioned technical problems by providing a coaxial lidar system, a transmitting module, a paraxial lidar system, and an automobile.

[0005] In a first aspect, embodiments of the present invention provide a coaxial lidar system, the system comprising a laser, a first lens group, a second lens group, a third lens group, a punched reflector, and a receiver;

[0006] The laser has its emitting end aligned with the incident light side of the third lens group, and the laser is used to emit a laser beam;

[0007] The third lens group has its light-emitting side aligned with the light-incident side of the second lens group, and the third lens group is used to perform fast-axis compression on the received laser beam to obtain the first emitted light beam.

[0008] The second lens group has its light-emitting side aligned with the light-transmitting hole of the punched reflector, and the second lens group is used to perform fast-axis divergence on the received first emitted light to obtain a second emitted light.

[0009] The perforated reflector includes a first surface, a second surface, and a light-transmitting hole connecting the first surface and the second surface; wherein, the first surface faces the second lens group, the second surface faces the receiver, the first lens group is used to receive the second outgoing light rays passing through the light-transmitting hole and refract the second outgoing light rays to emit a third outgoing light ray, and the second surface is used to reflect the reflected light rays of the third outgoing light rays back into the receiver.

[0010] The coaxial lidar system provided in this embodiment reduces the size of system components such as the radar window and scanning mirror by adopting a coaxial and co-aperture design for transmitting and receiving. This makes the system smaller and more compact, while also effectively reducing the size of the punched mirror in the coaxial lidar system. This reduces the energy loss caused by excessive punch size and improves the receiving efficiency of the coaxial and co-aperture lidar system, thereby enhancing the application performance of the radar system and supporting better detection results.

[0011] Secondly, embodiments of the present invention provide a laser emitting module, the laser emitting module comprising a laser, a first lens group, a second lens group, and a third lens group;

[0012] The laser has its emitting end aligned with the incident light side of the third lens group, and the laser is used to emit a laser beam;

[0013] The third lens group has its light-emitting side aligned with the light-incident side of the second lens group, and the third lens group is used to perform fast-axis compression on the received laser beam to obtain the first emitted light beam.

[0014] The second lens group has its light-emitting side aligned with the light-incident side of the first lens group, and the second lens group is used to perform fast-axis divergence on the received first outgoing light to obtain a second outgoing light.

[0015] The first lens group has its light-emitting side facing the target object, and the first lens group is used to collimate the received second emitted light rays onto the target object.

[0016] The laser emitting module provided in this embodiment achieves a laser emission optical path design by sequentially setting a third lens group and a second lens group between the laser and the first lens group. This design allows the third lens group to first compress the laser beam along the fast axis, and then the second lens group to slightly diverge the laser beam with a reduced divergence angle along the fast axis before coupling it into the first lens group for collimation and illuminating the target object. This design effectively reduces the horizontal output aperture of the laser emitting module, ensuring that the required size of system components such as radar windows and scanning mirrors is effectively reduced without affecting the laser emission effect, making the laser emitting module smaller and more compact.

[0017] Thirdly, embodiments of the present invention also provide a paraxial lidar system, the system including the aforementioned laser emitting module and a separate laser receiving module;

[0018] The laser receiving module includes a fourth lens group and a receiver; the fourth lens group has its light-incident side aligned with the target object and its light-outceasing side facing the receiver, and the fourth lens group is used to converge the laser echo received from the target object into the receiver.

[0019] This embodiment employs a laser emitting module with a third lens group arranged sequentially between the laser and the first lens group to perform fast-axis compression of the laser beam, and a second lens group to perform fast-axis slight divergence of the laser beam with a reduced divergence angle. This is combined with a laser receiving module that is parallel to and independent of the optical axis of the laser emitting module to achieve a paraxial lidar system with separate transmission and reception. This effectively reduces the horizontal output aperture of the laser emitting module, ensuring that the required radar window and scanning mirror and other system components are reduced without affecting the laser transmission and reception performance. As a result, the entire paraxial lidar system is smaller and more compact.

[0020] Fourthly, embodiments of the present invention also provide an automobile having the coaxial lidar system described above deployed thereon.

[0021] Fifthly, embodiments of the present invention also provide a vehicle having the paraxial lidar system described above deployed thereon. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the coaxial lidar system in an embodiment of the present invention;

[0023] Figure 2 This is another structural schematic diagram of the coaxial lidar system in an embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of the extinction aperture arrangement of the coaxial lidar system in an embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of the imaging effect of the third lens group in an embodiment of the present invention;

[0026] Figure 5 This is a schematic diagram of the imaging effect of the second lens group in an embodiment of the present invention;

[0027] Figure 6 This is a schematic diagram of the optical path effect of the second and third lens groups of the coaxial lidar system in this embodiment of the invention, both of which are two-lens combination structures;

[0028] Figure 7This is a detailed optical path effect diagram of the coaxial lidar system in this embodiment of the invention, showing that both the second and third lens groups are two-lens combination structures.

[0029] Figure 8 This is a schematic diagram of the optical path effect of the coaxial lidar system in this embodiment of the invention, where both the second and third lens groups are single-lens combinations.

[0030] Figure 9 This is a detailed optical path effect diagram of the coaxial lidar system in this embodiment of the invention, where both the second and third lens groups are single-lens combinations.

[0031] Figure 10 This is a schematic diagram comparing the laser emission branches of an existing coaxial lidar system with the improved coaxial lidar system provided by this invention.

[0032] Figure 11 This is a schematic diagram of the optical path effect of adding a reflector to the first lens group in an embodiment of the present invention;

[0033] Figure 12 This is a schematic diagram of the optical path effect of adding a reflector between the second and third lens groups in the transmitting branch and adding a reflector behind the perforated reflector in the receiving branch in an embodiment of the present invention.

[0034] Figure 13 This is a detailed optical path effect diagram of adding a reflector between the second and third lens groups in the transmitting branch and adding a reflector behind the perforated reflector in the receiving branch in an embodiment of the present invention.

[0035] Figure 14 This is a schematic diagram of the structure of the laser emitting module in an embodiment of the present invention;

[0036] Figure 15 This is a schematic diagram of the optical path effect of the laser emitting module in an embodiment of the present invention;

[0037] Figure 16 This is a schematic diagram comparing the aperture of existing laser emitting modules with the improved laser emitting module provided by this invention;

[0038] Figure 17 This is a schematic diagram of the optical path effect of the paraxial lidar system in an embodiment of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and beneficial effects of this application clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Obviously, the embodiments described below are only part of the embodiments of the present invention and are used to illustrate the present invention, but are not intended to limit the scope of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0040] In some embodiments, such as Figure 1 As shown, a coaxial lidar system is provided, the system including a laser 1, a first lens group 2, a second lens group 3, a third lens group 4, a perforated reflector 5, and a receiver 6;

[0041] The laser 1 has its emitting end aligned with the incident light side of the third lens group 4, and the laser 1 is used to emit a laser beam;

[0042] The third lens group 4 has its light-emitting side aligned with the light-incident side of the second lens group 3, and the third lens group 4 is used to perform fast-axis compression on the received laser beam to obtain the first emitted light beam.

[0043] The second lens group 3 has its light-emitting side aligned with the light-transmitting hole 51 of the perforated reflector 5, and the second lens group 3 is used to perform fast-axis divergence on the received first emitted light to obtain a second emitted light.

[0044] The perforated reflector includes a first surface, a second surface, and a light-transmitting hole 51 connecting the first surface 52 and the second surface 53; wherein, the first surface 52 faces the second lens group 3, the second surface 53 is aligned with the receiver 6, the first lens group 2 is used to receive the second outgoing light rays passing through the light-transmitting hole 51 and refract the second outgoing light rays to emit a third outgoing light ray, and the second surface 53 is used to reflect the reflected light rays of the third outgoing light rays back into the receiver 6.

[0045] The coaxial lidar system provided in this embodiment reduces the size of system components such as radar windows and scanning mirrors by adopting a coaxial and co-aperture design, making the system smaller and more compact. At the same time, it can effectively reduce the size of the punched mirror in the coaxial lidar system, reduce the energy loss caused by excessive punch size, and improve the receiving efficiency of the coaxial and co-aperture lidar system, thereby improving the application performance of the radar system and supporting the provision of better detection results.

[0046] In some embodiments, to meet the needs of more coaxial lidar system construction scenarios, the punched-hole reflector 5 is obtained by punching holes or by regional coating. That is, in practical applications, the light-transmitting hole 51 connecting the first surface 52 and the second surface 53 in the punched-hole reflector 5 can be obtained by actually punching holes in the reflector. Alternatively, a circular anti-reflection film and a reflective film are provided at the center of the second surface 53 of the punched-hole reflector 5. That is, a high reflectivity film layer is coated on the area that needs to reflect laser light, and a regional coating method with or without anti-reflection film is used to achieve a similar punched-hole light transmission effect, so as to avoid the punching holes affecting the structural strength of the reflector 5 and thus affecting the laser transmission quality.

[0047] In practical applications, the punched-out reflector 5 only needs to be tilted to the optical axis of the laser beam, and the angle between it and the optical axis can be set according to the actual application requirements. For example, considering the need to compress space, the angle α between the punched-out reflector 5 and the optical axis of the laser beam can generally be set in the range of 30° to 60°. In some embodiments, it can also be set to 40° to 50°, and can be further set to 45°, so as to ensure that while saving the layout space, reducing the punched-out size of the punched-out reflector 5 and not affecting the first lens group 2 to receive the laser beam, the punched-out reflector 5 can also effectively transmit the laser echo reflected by the target object received by the first lens group 2 to the receiver 6.

[0048] In some embodiments, such as Figure 2 As shown, an extinction stop can be further placed on the light-incident side of receiver 6 corresponding to the focal plane of the first lens group 2 to minimize the risk of interference from other stray light rays to the laser signal reflected back from the target object processed by receiver 6. It should be noted that the method of placing the extinction stop at receiver 6 can refer to existing technologies, such as using... Figure 3 The fence-like layout shown is not specifically limited here.

[0049] In some embodiments, the light-incident side of the third lens group 4 is further arranged to be close to the emitting end of the laser 1, so as to control the aperture of the lens group and ensure that the third lens group 4 performs fast-axis compression on the laser beam in the laser emitting branch, thereby minimizing the divergence angle of the laser beam and reducing the opening size of the perforated reflector 5.

[0050] In some embodiments, the light-emitting side of the second lens group 3 is further configured to be in close contact with the first surface 52 of the perforated reflector 5. This ensures that the size of the opening of the perforated reflector is not affected when the second lens group 3 slightly diverges the laser beam after the divergence angle θ is compressed, and also ensures that the laser beam can be better coupled into the first lens group 2.

[0051] In some embodiments, the first lens group 2 is a positive lens group used for both transmission and reception; the first lens group 2 is composed of one or more lenses; the surface type of the lens includes spherical mirrors, aspherical mirrors, microlens arrays, and metasurface lenses. For example... Figure 1 and Figure 2 As shown, the first lens group 2 is the main lens of the coaxial co-aperture lidar system. It serves both as the transmitting lens, receiving the reflected laser light transmitted through the opening of the perforated reflector 5 and collimating it onto the target, and as the receiving lens, receiving the laser echo reflected from the target and focusing it onto the receiver 6. In this embodiment, the focal length of the shared main lens for collimating the emitted light can be selected to be 15mm or more, resulting in better collimation performance. Compared to the paraxial (dual-lens) lidar optical path system with separate transmitting and receiving, this coaxial co-aperture optical path, because it shares a single lens, can compensate for energy loss by appropriately increasing the lens aperture within the same size, thereby achieving a smaller rotating mirror, a more compact system size, and better detection performance with a smaller viewing window opening.

[0052] In some embodiments, such as Figure 4 and Figure 5 As shown, the third lens group 4 is a positive cylindrical lens group, which is a positive lens group that collimates the laser beam emitted by the laser and is used to significantly compress the aperture of the reflecting mirror; the second lens group 3 is a negative cylindrical lens group, which is used to slightly diverge the excessively compressed collimated light so that it can be coupled into the main lens (first lens group 2). The cooperation between the third lens group 4 and the second lens group 3 can ensure that the emitted light and the received light are coupled into the shared main lens at the same time without affecting their respective image quality, and improve the receiving efficiency. It should be noted that in this embodiment, the slight divergence condition of the second lens group 3 is to diverge the divergence angle to match the image-side aperture angle θ1 of the first lens group 2, and the specific matching range is approximately 0.7θ1 to 2θ1. This image-side aperture angle θ1 = atan(1 / (2F / #)), where F / # represents the aperture of the first lens group, and the range of F / # is 0.9 to 3.0; taking F / # = 1.3 as an example, θ1 = 21°. That is, the 12° divergence angle beam collimated by the third lens needs to be diverged to between 15° and 42°.

[0053] In practical applications, lidar systems can be further divided into single-point scanning lidar systems and multi-beam scanning lidar systems, depending on their purpose. For different types of lidar systems, to ensure the application effect in the corresponding scenarios, the lens combination methods of the third lens group 4 and the second lens group 3, introduced in the above embodiments to achieve fast-axis compression and fast-axis divergence effects, differ. In some embodiments, when the lidar system is a single-point scanning lidar system, the second lens group 3 is a concave cylindrical lens group or a concave spherical lens, and the third lens group 4 is a convex cylindrical lens group or a convex spherical lens. In some embodiments, when the lidar system is a multi-beam scanning lidar system, the second lens group 3 is a concave cylindrical lens group, and the third lens group 4 is a convex cylindrical lens group. In this embodiment, considering that the third lens group 4 is a convex cylindrical mirror, it only changes the optical path in the fast axis direction and does not change it in the slow axis direction, while the first lens group 2 is a spherical mirror group, the receiving optical path requires the focal points of the fast and slow axes to be consistent. Therefore, the combined lens group consisting of the third lens group 4 and the first lens group 2 will have inconsistent focal points in the fast and slow axis directions. To address this problem, the laser 1 can only be placed between the focal points of the fast and slow axes, resulting in poor collimation in both directions. However, by adding the second lens group 3 to the transmitting branch, the back focal point in the fast axis direction is adjusted back to the slow axis position, ensuring that the focal points of the combined lens group are consistent in the fast and slow axis directions, so that the collimation effect of the laser 1 in both directions reaches the optimal level. That is, by using the second lens group 3 to correct the non-rotational symmetry effect of the third lens group 4 on the optical path, it is possible to effectively ensure that the emitted light and received light can be coupled into the shared main lens simultaneously.

[0054] The structures of the third lens group 4 and the second lens group 3 used in the above embodiments can be selected according to requirements and corresponding functions, supporting more lens combination design scenarios. In some embodiments, the third lens group 4 can be composed of one or more lenses, which can be a single convex cylindrical mirror directly attached to the laser, or a convex cylindrical lens group obtained by combining multiple convex cylindrical mirrors; for example, if the third lens group 4 is obtained by combining two convex cylindrical mirrors, the combined focal length is f3 = (f a *f b ) / (f a +f b -d ab ), f a and f b Let f represent the focal lengths of the two convex cylindrical mirrors, respectively. To simplify the calculation, we can directly take f as the focal length. a ≈f b ;d ab This represents the spacing between two lenses. For closely spaced lenses, it can be taken as 0. Therefore, the method for combining two convex cylindrical lenses into a closely spaced convex cylindrical lens is f3 = f a f b / (fa+ f b In some embodiments, the simplest convex cylindrical mirror assembly is further designed as f. a =f b =2f3.

[0055] Similarly, the second lens group 3 can also be composed of one or more lenses. In practical applications, considering the relatively small optical power of the second lens group 3, a single concave cylindrical lens is generally sufficient. Of course, a concave cylindrical lens group composed of multiple concave cylindrical lenses can also be used. For example, if the second lens group 3 is composed of two concave cylindrical lenses, referring to the example of the third lens group 4 above, the combined focal length can also be obtained as f2 = (f c *f d ) / (f c +f d -d cd ), f c and f d Let f represent the focal lengths of the two concave cylindrical mirrors, respectively. To simplify the calculation, we can directly take f as the focal length. c ≈f d ;d cd This represents the spacing between two lenses. For closely spaced lenses, it can be taken as 0. Therefore, the method for combining two concave cylindrical lenses into a closely spaced concave cylindrical lens is f2 = (f...). c *f d ) / (f c +f d The simplest concave cylindrical mirror assembly obtained through further design is f. c =f d =2f2.

[0056] In some embodiments, such as Figure 6 As shown, a simple lens combination design can be further adopted, combining a second lens group 3 obtained by combining two concave cylindrical mirrors with a third lens group 4 obtained by combining two convex cylindrical mirrors, to achieve the desired fast-axis compression and fast-axis divergence effects. The corresponding detailed optical path effects are as follows: Figure 7 As shown.

[0057] In some embodiments, to ensure better transmit / receive coupling based on the first lens group 2, such as Figure 8 As shown, the first lens group 2 is further configured with four lenses arranged in the order of convex mirror, concave mirror, and convex mirror, with corresponding optical powers of positive-positive-negative-positive. Meanwhile, the second lens group 3 uses a single convex cylindrical mirror, thus ensuring that the optical power ratio between the first lens group 2 and the second lens group 3 satisfies the following relationship:

[0058] f1:f2≥1.5:-1

[0059] In the formula, f1 and f2 respectively represent the focal lengths of the first lens group 2 and the second lens group 3, and the range of f1 is 5 mm to 1000 mm, and the range of f2 is 0 mm to 800 mm; it should be noted that in practical applications, the optical power of the first lens group 2 and the second lens group 3 can be configured in the manner of f1:f2 = 2: -1.

[0060] In some embodiments, in order to ensure that the combined design of the second lens group 3 and the third lens group 4 can achieve the optimal fast-axis compression and fast-axis divergence effects, as Figure 8 shown, the second lens group 3 is further provided with a convex cylindrical lens and the third lens group 4 is provided with a concave cylindrical lens, so that the optical power ratio of the second lens group 3 and the third lens group 4 satisfies the following relational expression:

[0061] f2:f3 ≈ -d2:d3

[0062] In the formula, f2 and f3 respectively represent the focal lengths of the second lens group 3 and the third lens group 4, and the range of f2 is 0 mm to 800 mm, and the range of f3 is 0 mm to 10 mm; d2 represents the distance between the second lens group 3 and the third lens group 4, and 0 mm < d2 ≤ 200 mm; d3 represents the distance between the third lens group 4 and the laser 1, and 0 mm < d3 ≤ 2 mm; it should be noted that in practical applications, in order to ensure the optimal fast-axis compression effect of the laser beam, d3 ≤ 2 mm can be further set.

[0063] It should be noted that the selection of the optical power ratio of the first lens group 2 and the second lens group 3, and the optical power ratio of the second lens group 3 and the third lens group 4 in the above embodiments is determined according to the light-emitting characteristics of the light source. The following takes a VCSEL line laser with a beam divergence angle of 24° and a light-emitting surface size of 2.5 * 0.08 mm as an example for illustration:

[0064] First, calculate the parameters of the third lens group 4. Since the third lens group 4 is a convex cylindrical lens group that plays a focusing role, the closer it is to the laser, the smaller the focused spot diameter, and the imaging effect of the corresponding third lens group 4 is as Figure 4As shown; in actual setup, space needs to be left for dispensing adhesive, so the distance d3 between the third lens group 4 and the laser 1 is generally around 0.1mm, which can be taken as d3 = 0.07mm. Then the divergence angle of the light spot after the third lens group 4 is focused can be between 0° and 24°. That is, the divergence angle of the light spot formed after focusing the laser divergence angle of 10° to 60° is 0° to 24°. To facilitate implementation, the divergence angle can be directly reduced by half, i.e., 12°. At this time, the third lens group 4 forms a virtual image of the laser 1 and the virtual image is located behind the actual laser 1. The corresponding virtual image distance is l'3 = -d3*tan(12) / tan(6). Then, according to the Gaussian formula 1 / l'3 - 1 / l3 = 1 / f3, where l3 = d3, the focal length f3 of the third lens group 4 can be obtained.

[0065] The second lens group 3 is primarily designed to better couple the compressed beam to the first lens group 2; the corresponding theoretical model involves imaging the focal point of the first lens group 2 onto the virtual image point of the third lens group 4. For example... Figure 5 As shown, during the imaging process, the object distance l2≈-d2, and the corresponding virtual image distance is l'2≈-d2+l3. Then, according to the Gaussian formula 1 / l'2-1 / l2=1 / f2, the focal length f2 of the second lens group 3 can be obtained.

[0066] Meanwhile, since the second lens group 3 is behind the first lens group 2 and the punched-out reflector 5, d2 is closer to the focal length of the first lens group 2. Certain relationships must be satisfied, while also considering leaving enough space to place the lens groups; that is, the distance d2 between the second lens group 3 and the third lens group 4 should be approximately within... Within the range.

[0067] In some embodiments, the size of the laser spot generated after compression of the laser beam emitted by the laser 1 can be adjusted by adjusting the optical power ratio and the lens group spacing in the above embodiments. The maximum size of the laser spot is (d2+d3)*tan(θ), and the minimum size of the laser spot is d3*tan(θ), where θ represents the divergence angle (D86 divergence angle) of the laser 1. Since the punched-hole reflector 5 needs to be placed tilted to the optical axis in practical applications, the range of the aperture size of the punched-hole reflector 5 is expressed as follows:

[0068] R size =[d3*tan(θ) / sin(α),(d2+d3)*tan(θ) / sin(α)]

[0069] Among them, R size Indicates the range of light aperture size, 0mm <R size≤30 mm; α represents the angle between the挖孔mirror 5 and the optical axis of the laser beam, 30° ≤ α ≤ 50°; θ represents the divergence angle of the laser 1, 10° ≤ θ ≤ 60°; d2 represents the distance between the second lens group 3 and the third lens group 4, 0 mm < d2 ≤ 200 mm; d3 represents the distance between the third lens group 4 and the laser 1, 0 mm < d3 ≤ 5 mm.

[0070] For the convenience of explaining the optical path effect when the coaxial and common-aperture lidar system designed in the above embodiments is applied, in the following embodiments, the first lens group 2 (lens group) shared for transmitting and receiving, which consists of 4 lenses (the combination order of the four lenses is a convex mirror, a convex mirror, a concave mirror, and a convex mirror in sequence, and the corresponding optical powers are positive, positive, negative, and positive), is taken as an example for detailed description:

[0071] As Figure 8 shown, behind the first lens group 2 is the挖孔mirror 5, which is placed at an angle of 45 degrees. There is a slit (or area-coated) in the middle of the mirror 5. The middle slit part can transmit the beam, and other areas can only reflect the beam; behind the挖孔mirror 5, there are the second lens group 3 and the third lens group 4 in the emission branch. The corresponding detailed optical path is as Figure 9 shown; from Figure 4 it can be seen that when the second lens group 3 is a concave cylindrical mirror and the third lens group is a convex cylindrical mirror, due to their combined effect, the horizontal angle of the beam emitted by the laser 1 is greatly compressed, and only a relatively small挖孔slit is required on the mirror to enter the first lens group 2, thereby reducing the received energy loss caused by the挖孔.

[0072] To verify the reception efficiency of the coaxial and common-aperture lidar system provided in the above embodiments, taking the miniaturized coaxial and common-aperture optical path as an example, the Figure 10 existing coaxial and common-aperture lidar system shown in Figure (a) in which the second lens group 3 and the third lens group 4 combination design given in the above embodiments of the present application is not introduced in the emission branch, and the Figure 10 improved coaxial and common-aperture lidar system shown in Figure (b) in the above embodiments of the present application, which introduces the combination design of the second lens group 3 and the third lens group 4, are subjected to the following simulation experiment analysis:

[0073] The angles between the挖孔mirror 5 and the optical axis in both the existing coaxial and common-aperture lidar system and the improved coaxial and common-aperture lidar system are set to 45°, the distance from the挖孔mirror 5 to the laser 1 is 5 mm, the laser 1 uses a linear array VCSEL emitter, and the divergence angle is 24°;

[0074] As Figure 10As shown in Figure (a), for existing coaxial co-aperture lidar systems without the second lens group 3 and the third lens group 4, the cutout width on the perforated reflector 5 needs to be 3.1 mm, resulting in an energy loss of approximately 40% and a reduction in detection range of approximately 23%; while as Figure 10 As shown in Figure (b), for the improved coaxial co-aperture lidar system with the introduction of the second lens group 3 and the third lens group 4, the divergence angle after compression by the second lens group 3 and the third lens group 4 is about 12°, the width of the hole in the hole-punched reflector 5 is reduced to 1.5 mm, resulting in an energy loss of about 19% and a reduction of about 10% in the detection range.

[0075] Based on the above comparative analysis, it can be seen that the improved coaxial co-aperture lidar system provided in this application, compared with the existing coaxial co-aperture lidar system, achieves a reduction in the size of system components such as radar windows and scanning mirrors based on the coaxial co-aperture design. This makes the system smaller and more compact, while also effectively reducing the hole size of the punched mirror in the coaxial lidar system. This reduces the energy loss caused by excessively large hole size and improves the receiving efficiency of the coaxial co-aperture lidar system, thereby enhancing the application performance of the radar system and supporting the provision of better detection results.

[0076] To minimize the size of the coaxial lidar system described in the above embodiments without affecting the receiving efficiency and detection performance of the radar system, in some embodiments, the optical path system is folded by adding a reflector to the coaxial lidar system. This further involves adding a reflector to the laser emission branch composed of the laser 1, the first lens group 2, the second lens group 3, and the third lens group 4, and / or adding a reflector to the laser receiving branch composed of the first lens group 2, the perforated reflector 5, and the receiver 6. In practical applications, such as... Figure 11 As shown, if the first lens group 2 consists of multiple lenses, the light path can be folded by arranging reflectors between the lenses in the first lens group 2; simultaneously, as Figures 12-13 As shown, a reflector can also be placed between the second lens group 3 and the third lens group 4 in the laser emitting branch, and / or a reflector can be inserted behind the perforated reflector 5 in the laser receiving branch to fold the optical path.

[0077] Furthermore, based on the concept that the transmitting branch of the aforementioned coaxial co-aperture lidar system can effectively reduce the output aperture, the laser transmitting module is redesigned. In some embodiments, such as... Figure 14 As shown, a laser emitting module is provided, which includes a laser 1, a first lens group 2, a second lens group 3, and a third lens group 4;

[0078] The laser 1 has its emitting end aligned with the incident light side of the third lens group 4, and the laser 1 is used to emit a laser beam;

[0079] The third lens group 4 has its light-emitting side aligned with the light-incident side of the second lens group 3, and the third lens group 4 is used to perform fast-axis compression on the received laser beam to obtain the first emitted light beam.

[0080] The second lens group 3 has its light-emitting side aligned with the light-incident side of the first lens group 2, and the second lens group 3 is used to perform fast-axis divergence on the received first outgoing light to obtain a second outgoing light.

[0081] The first lens group 2 has its light-emitting side facing the target object, and the first lens group 2 is used to collimate the received second emitted light rays onto the target object.

[0082] It should be noted that the lens type selection, lens position setting, and optical power ratio of each lens group in the above embodiments can all refer to the relevant setting description in the above coaxial lidar system, and will not be repeated here.

[0083] The laser emitting module provided in this embodiment achieves a laser emitting optical path design by sequentially setting a third lens group 4 and a second lens group 3 between the laser 1 and the first lens group 2. This design allows the third lens group 4 to first compress the laser beam along the fast axis, and then the second lens group 3 to slightly diverge the laser beam with a reduced divergence angle along the fast axis before coupling it into the first lens group 2 for collimation and illuminating the target object. This design effectively reduces the horizontal output aperture of the laser emitting module and ensures that the required size of system components such as radar windows and scanning mirrors is effectively reduced without affecting the laser emitting effect, making the laser emitting module smaller and more compact.

[0084] To facilitate the explanation of the optical path effect when the laser emitting module designed in the above embodiments is applied, the following embodiments will use the first lens group 2 (emitting lens) composed of 4 lenses (the combination order of the four lenses is convex mirror, convex mirror, concave mirror and convex mirror, and the corresponding optical powers are positive positive negative positive) as an example for detailed explanation:

[0085] like Figure 15As shown, in the laser emitting module, a second lens group 3 and a third lens group 4 are arranged behind the first lens group 2. The second lens group 3 is a concave cylindrical mirror, and the third lens group 4 is a convex cylindrical mirror. Under the combined effect of the two, the horizontal angle of the laser beam emitted by the laser 1 is significantly compressed, thereby effectively reducing the horizontal aperture of the first lens group 2 in the emitting lens. To verify its application effect, an aperture comparison analysis is performed between an existing standalone emitting module without the second lens group 3 and the third lens group 4 provided in this embodiment and the laser emitting module with the second lens group 3 and the third lens group 4. Figure 16 As shown, the aperture of the laser emitting module provided in this embodiment is compressed to 4mm, while the aperture of existing standalone emitting modules requires 6mm, meaning the improved laser emitting module aperture is reduced by 33%. It should be noted that... Figure 15 The second lens group 3 can be replaced by multiple concave cylindrical mirrors instead of a single concave cylindrical mirror, and / or the third lens group 4 can be replaced by multiple convex cylindrical mirrors instead of a single convex cylindrical mirror. This can also effectively reduce the horizontal aperture of the first lens group 2 in the transmitting lens.

[0086] In some embodiments, a paraxial lidar system is provided, the system including the laser emitting module provided in the above examples, and a separate laser receiving module;

[0087] The laser receiving module includes a fourth lens group and a receiver; the fourth lens group has its light-incident side aligned with the target object and its light-outceasing side facing the receiver, and the fourth lens group is used to converge the laser echo received from the target object into the receiver; wherein, the receiver may also be equipped with an extinction stop to minimize the risk of interference from other stray light rays to the receiver processing the laser signal reflected back from the target object.

[0088] It should be noted that the specific limitations of the laser emitting module in this paraxial lidar system can be found in the relevant description of the laser emitting module designed in the above embodiments, and will not be repeated here.

[0089] This embodiment employs a laser emitting module consisting of a third lens group 4 for fast-axis compression of the laser beam and a second lens group 3 for fast-axis slight divergence of the laser beam with a reduced divergence angle, arranged sequentially between the laser 1 and the first lens group 2. This is paired with a laser receiving module parallel to and independent of the laser emitting module's optical axis, achieving a transceiver separation system. This effectively reduces the horizontal output aperture of the laser emitting module, ensuring that the required radar window and scanning mirror size are reduced without affecting the laser transceiver performance, resulting in a smaller and more compact overall paraxial lidar system.

[0090] In principle, any lens group 7 in the aforementioned paraxial lidar system can be selected to meet the laser receiving function. However, in order to effectively reduce the size of system components such as the required radar window and scanning mirror, making the entire paraxial lidar system smaller and more compact, while also reducing the cost of building the lidar system, in some embodiments, the fourth lens group 7 in the laser receiving module uses the same lens combination as the first lens group 2 in the laser emitting module. The only difference between the two is the different tangent diameter of the lenses. It should be noted that both the first lens group 2 and the fourth lens group 7 can be composed of one or more lenses, and no specific limitation is made here.

[0091] To facilitate the explanation of the optical path effect when the paraxial lidar system designed in the above embodiments is applied, the following embodiments will use the first lens group 2 (transmitting lens) and the fourth lens group 7 (receiving lens), which are composed of the same four lenses (the combination order of the four lenses is convex mirror, convex mirror, concave mirror and convex mirror, and the corresponding optical powers are positive positive negative positive), as examples for detailed explanation:

[0092] like Figure 17 As shown, both the transmitting and receiving lenses are composed of the aforementioned four lenses. The only difference between the transmitting and receiving lenses is the tangential diameter of the lenses. In the laser transmitting module of the paraxial lidar system, the first lens group 2 is followed by the second lens group 3 and the third lens group 4. The second lens group 3 is a concave cylindrical mirror, and the third lens group 4 is a convex cylindrical mirror. Under the combined effect of these two lenses, the horizontal angle of the laser beam is significantly compressed, thereby reducing the horizontal diameter of the first lens group in the transmitting lens.

[0093] In practical applications, in a paraxial lidar system, the laser emitting module and laser receiving module only need to ensure that the optical axes of the receiving lens and the emitting lens are parallel. This allows for a smaller horizontal output aperture in the laser emitting module, thereby reducing the size of components such as the radar window and scanning mirror. Based on this, in some embodiments, the laser emitting module and laser receiving module are arranged parallel vertically and horizontally to ensure that the optical axes of the first lens group and the fourth lens group are parallel.

[0094] In some embodiments, a vehicle is provided, characterized in that it is equipped with the coaxial lidar system provided in the above embodiments.

[0095] In some embodiments, a vehicle is provided, characterized in that it is equipped with the paraxial lidar system provided in the above embodiments.

[0096] The various embodiments in this specification are described in a progressive manner. For directly identical or similar parts of the various embodiments, refer to each other. Each embodiment focuses on its differences from other embodiments. It should be noted that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as these combinations of technical features do not contradict each other, they should be considered within the scope of this specification.

[0097] The embodiments described above are merely preferred embodiments of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various improvements and substitutions without departing from the technical principles of this invention, and these improvements and substitutions should also be considered within the scope of protection of this application. Therefore, the scope of protection of this patent application should be determined by the scope of the claims.

Claims

1. A coaxial lidar system, characterized in that, The system includes a laser, a first lens group, a second lens group, a third lens group, a perforated reflector, and a receiver; The laser, whose emission end is aligned with the incident light side of the third lens group, is used to emit a laser beam; The third lens group, whose emission light side is aligned with the incident light side of the second lens group, is used to perform fast-axis compression on the laser beam emitted by the laser to obtain a first emitted light ray; The second lens group, whose emission light side is aligned with the through hole of the perforated reflector, is used to perform fast-axis divergence on the received first emitted light ray to obtain a second emitted light ray; The perforated reflector includes a first surface, a second surface, and a through hole connecting the first surface and the second surface; wherein, the first surface faces the second lens group, the second surface is aligned with the receiver, the first lens group is used to receive the second emitted light ray passing through the through hole and refract the second emitted light ray to emit a third emitted light ray, and the second surface is used to reflect the reflected light ray of the third emitted light ray back into the receiver again.

2. The coaxial lidar system as described in claim 1, characterized in that, A circular anti-reflection film and a reflection film arranged around the circular anti-reflection film are provided at the center position of the second surface of the perforated reflector.

3. The coaxial lidar system as described in claim 1, characterized in that, The included angle α between the perforated reflector and the laser beam ranges from 30° to 60°.

4. The coaxial lidar system as described in claim 1, characterized in that, An extinction diaphragm is arranged on the incident light side of the receiver, and the extinction diaphragm is arranged at the focal plane position of the first lens group.

5. The coaxial lidar system as described in claim 1, characterized in that, The incident light side of the third lens group is closely attached to the emission end of the laser.

6. The coaxial lidar system as described in claim 1, characterized in that, The emission light side of the second lens group is closely attached to the first surface of the perforated reflector.

7. The coaxial lidar system as described in claim 1, characterized in that, The first lens group is a positive lens group for both transmission and reception.

8. The coaxial lidar system as described in claim 1 or 5, characterized in that, The third lens group is a positive lens group; the second lens group is a negative lens group.

9. The coaxial lidar system as described in claim 8, characterized in that, The third lens group is a convex cylindrical lens group.

10. The coaxial lidar system as described in claim 8, characterized in that, The second lens group is a concave cylindrical mirror group.

11. The coaxial lidar system as described in claim 1, characterized in that, The divergence angle range of the second lens group is [0.7θ1, 2θ1], where θ1 is the image-side aperture angle of the first lens group, θ1 = atan(1 / (2F / #)), F / # represents the aperture of the first lens group, and the range of F / # is 0.9 to 3.

0.

12. The coaxial lidar system as described in claim 9, characterized in that, The convex cylindrical lens group is composed of a single convex cylindrical mirror; or, The convex cylindrical lens group consists of a first convex cylindrical lens and a second convex cylindrical lens, wherein the combined focal length is f3, and f3 = f a / 2=f b / 2,f a f represents the focal length of the first convex cylindrical mirror. b This indicates the focal length of the second convex cylindrical mirror.

13. The coaxial lidar system as described in claim 10, characterized in that, The concave cylindrical lens group is composed of a single concave cylindrical mirror; or, The concave cylindrical lens group consists of a first concave cylindrical lens and a second concave cylindrical lens, wherein the combined focal length is f2, and f2 = f c / 2=f d / 2,f c f represents the focal length of the first concave cylindrical mirror. d This indicates the focal length of the second concave cylindrical mirror.

14. The coaxial lidar system as described in any one of claims 1, 6, or 7, characterized in that, The optical power ratio between the first lens group and the second lens group satisfies the following relational expression: f1:f2 ≥ 1.5: -1 In the formula, f1 represents the focal length of the first lens group, and the range of f1 is 5 mm to 1000 mm; f2 represents the focal length of the second lens group, and the range of f2 is 0 mm to 800 mm.

15. The lidar system as described in any one of claims 1, 5, or 6, characterized in that, The optical power ratio between the second lens group and the third lens group satisfies the following relational expression: f2:f3 ≈ -d2:d3 In the formula, f2 represents the focal length of the second lens group, and the range of f2 is 0 mm to 800 mm; f3 represents the focal length of the third lens group, and the range of f3 is 0 mm to 10 mm; d2 represents the distance between the second lens group and the third lens group, and 0 mm < d2 ≤ 200 mm; d3 represents the distance between the third lens group and the laser, and 0 mm < d3 ≤ 2 mm.

16. The coaxial lidar system as described in any one of claims 1, 5, or 6, characterized in that, The third lens group focuses the laser divergence angle of the laser beam from 10° to 60° to form a divergence angle range of 0° to 24°.

17. The coaxial lidar system as described in claim 1, characterized in that, The range of light-transmitting aperture sizes for the perforated reflector is expressed as follows: R size =[d3*tan(θ) / sin(α),(d2+d3)*tan(θ) / sin(α)] Among them, R size represents the size range of the light passing hole, 0 mm < R size ≤ 30 mm; α represents the angle between the hole-drilled mirror and the optical axis of the laser beam, 30° ≤ α ≤ 60°; θ represents the divergence angle of the laser, 10° ≤ θ ≤ 60°; d2 represents the distance between the second lens group and the third lens group, 0 mm < d2 ≤ 200 mm; d3 represents the distance between the third lens group and the laser, 0 mm < d3 ≤ 2 mm.

18. A laser emitting module, characterized in that, The laser emitting module includes a laser, a first lens group, a second lens group, and a third lens group; The laser has its emitting end aligned with the incident light side of the third lens group, and the laser is used to emit a laser beam; The third lens group has its light-emitting side aligned with the light-incident side of the second lens group, and the third lens group is used to perform fast-axis compression on the laser beam emitted by the laser to obtain the first outgoing light beam. The second lens group has its light-emitting side aligned with the light-incident side of the first lens group, and the second lens group is used to perform fast-axis divergence on the received first outgoing light to obtain a second outgoing light. The first lens group has its light-emitting side facing the target object, and the first lens group is used to collimate the received second emitted light rays onto the target object.

19. A paraxial lidar system, characterized in that, The system includes the laser emitting module as described in claim 18, and a separate laser receiving module; The laser receiving module includes a fourth lens group and a receiver; the fourth lens group has its light-incident side aligned with the target object and its light-outceasing side facing the receiver, and the fourth lens group is used to converge the laser echo received from the target object into the receiver.

20. The paraxial lidar system as described in claim 18, characterized in that, The fourth lens group has the same lens combination as the first lens group, but the cut edge diameter of the lens is different.

21. The paraxial lidar system as described in claim 18, characterized in that, The optical axes of the first lens group and the fourth lens group are parallel.

22. A car, characterized in that, It is equipped with a coaxial lidar system as described in any one of claims 1 to 17.

23. A car, characterized in that, It is equipped with a paraxial lidar system as described in any one of claims 19 to 21.

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