Laser receiving system and lidar

Abstract

The application provides a laser receiving system and a laser radar, wherein the laser receiving system comprises a prism, a lens group and a detection device arranged in sequence, wherein the prism has opposite first and second side surfaces, the second side surface comprises a first surface and a second surface with an included angle, and the first side surface or the second side surface faces the lens group; the lens group comprises at least two lenses arranged from an object side to an image side, at least one of the lenses has a positive focal length, the object side is a side where the prism is located, the image side is a side where the detection device is located, and the prism and the lens closest to the object side in the lens group are located on the same optical axis. The application can reduce the volume of the laser receiving system while meeting the requirement of receiving multiple light rays with different angles.

Description

Technical Field

[0001] This application relates to the field of radar detection technology, and in particular to a laser receiving system and a lidar. Background Technology

[0002] As a weak-sensing detection system, radar technology can accurately detect the outline of targets and obtain their depth information, both day and night. In fields such as autonomous driving and robotics, compared to camera-based vision solutions, lidar offers advantages such as all-weather operation, higher measurement resolution, stronger anti-interference capabilities, and greater penetration power. It can autonomously perceive the road environment and assist vehicles in achieving predetermined goals. Therefore, lidar has a wide range of applications.

[0003] A lidar system typically includes a transmitting system and a receiving system. The transmitting system includes a reflector and multiple receiving modules arranged perpendicular to the optical path. The transmitting system emits a laser beam, which illuminates the target object and, after diffuse reflection, returns as an echo. This echo is reflected by the reflector and received by the multiple receiving modules. The echo typically contains multiple rays at different angles to the reflector's centerline, and each receiving module can receive rays at different angles.

[0004] Multiple receiving modules will result in a larger receiving system, thus increasing the size of the lidar. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a laser receiving system and a laser radar that can reduce the size of the laser receiving system while simultaneously receiving light from multiple different angles.

[0006] This application provides a laser receiving system, comprising: a prism, a lens group, and a detection device arranged in sequence, wherein: the prism has a first side and a second side opposite to each other, the second side includes a first surface and a second surface having an included angle, and the first side or the second side faces the lens group; the lens group includes at least two lenses arranged from the object side to the image side, and at least one lens has positive optical power, the object side is the side where the lens is located, the image side is the side where the detection device is located, and the prism and the lens closest to the object side in the lens group are located on the same optical axis.

[0007] In application, the laser receiving system of this application receives echo light diffusely reflected from the target object and illuminates a prism. The echo light then passes through a lens group to reach a detection device. The detection device receives the echo light and can obtain parameters of the target object based on it, thus completing the detection of the target object. Since the second side of the prism includes at least two surfaces, a first surface and a second surface, with an included angle, the first and second surfaces can receive echo light from different angles respectively. The lens group includes at least two lenses arranged from the object side to the image side, with the lens closest to the object side located on the same optical axis as the prism. Therefore, this application can use only one lens group instead of multiple receiving modules, thereby reducing the size of the laser receiving system. When at least one lens in the lens group has positive optical power, this lens can converge the echo light, allowing the detection device to receive as much echo light as possible.

[0008] In some possible implementations, the lens closest to the object side in the lens group has positive optical power. In this way, the lens closest to the object side can converge the light rays to compress the beam aperture of the other lenses in the lens group.

[0009] In some possible implementations, the extension direction of the first surface forms an angle with the extension direction of the first side surface, and the second surface is parallel to the first side surface. Thus, the echo rays illuminating the projection area of ​​the second surface onto the first side surface retain their propagation direction after reaching the second surface; the echo rays illuminating the first surface onto the projection area of ​​the first side surface change their field of view after exiting the first surface. Since all echo rays emitted from the laser receiving system can be received by the lens group, the laser receiving system can receive echo rays with a larger field of view.

[0010] In some possible implementations, there are at least two first surfaces. One portion of the first surface is located on a first side of a second surface, and another portion of the first surface is located on a second side of the second surface opposite to the first side. Thus, the second surface, located in the center of the prism, can receive light within a small angle range from the center of the echo beam and prevent this light from being deflected after passing through the prism. The first surfaces located on either side of the second surface can receive light within a larger angle range from the center of the echo beam and reduce the field of view of this portion of the light, thereby ensuring that all echo beams emitted from the prism can be received by the lens group. Therefore, the laser receiving system can receive echo beams with a larger field of view.

[0011] In some possible implementations, the prism further includes at least one third surface located on the side of the first surface away from the second surface. When there are multiple third surfaces, they are connected sequentially, with each pair of adjacent third surfaces forming an angle, and the third surface closest to the first surface forming an angle with the first surface. In this way, the first and third surfaces can receive light rays with different angles from the center in the echo, thereby enabling the laser receiving system to receive echo rays over a wider range and with a larger field of view. Furthermore, when there are multiple third surfaces, and each pair of adjacent third surfaces forms an angle, each pair of adjacent third surfaces can receive light rays with different angles from the center in the echo.

[0012] In some possible implementations, the distance between the third surface, which is furthest from the second surface, and the first side surface gradually increases from the end furthest from the second surface to the end closest to it. This allows the third surface, furthest from the second surface, to deflect the received echo light and reduce the field of view of the echo light, enabling the echo light to illuminate the lens closest to the object side in the lens group. Consequently, the laser receiving system can receive echo light with a larger field of view. Furthermore, it reduces the beam aperture of the lens closest to the prism.

[0013] In some possible implementations, the lens group includes a cylindrical mirror positioned between a lens with positive optical power and the detection device. Because the cylindrical mirror can scatter light in one direction, it can adjust rays with a constant field of view to rays with a non-constant field of view, or vice versa, to better suit the needs of the detection device.

[0014] In some possible implementations, the lens closest to the detection device in the lens group has positive optical power. This allows the lens with positive optical power to converge the light rays onto the individual detectors within the detection device.

[0015] In some possible implementations, the ratio K1 between the dimension of the projection of the first surface onto the first side along the first direction and the dimension of the second surface along the first direction satisfies: 0.2 ≤ K1 ≤ 5; the first direction is the arrangement direction of the first and second surfaces. When K1 is 0.2, the dimension of the second surface located in the middle along the first direction is larger, and the dimension of the first surface along the first direction is smaller, which is suitable for echo light with a larger central range; when K1 is 5, the dimension of the first surface along the first direction is larger, and the dimension of the second surface located in the middle along the first direction is smaller, which is suitable for scenes with a large range of light and a large field of view, thus broadening the applicability of the laser receiving system.

[0016] In some possible implementations, the ratio K2 between the dimension of the projection of the third surface onto the first side along the first direction and the dimension of the second surface along the first direction satisfies: 0.2 ≤ K2 ≤ 5; the first direction is the alignment direction of the third and second surfaces. When K2 is 0.2, the dimension of the second surface in the middle along the first direction is larger, and the dimension of the third surface along the first direction is smaller, which is suitable for echo rays with a larger central range; when K2 is 5, the dimension of the third surface along the first direction is larger, and the dimension of the second surface in the middle along the first direction is smaller, which is suitable for scenes with a large range of light rays and a large field of view. Therefore, the laser receiving system has a wider range of applications.

[0017] In some possible implementations, the prism has opposing first and second end faces, with both the first and second side faces located between them. The ratio of the aperture D1 of the lens closest to the object side in the lens group to the aperture D0 of the prism satisfies: 0.8 ≤ D1 / D0 ≤ 2. The aperture of the prism is the distance between the first and second end faces. If the ratio of D1 to D0 is less than 0.8, the lens closest to the object side in the lens group will not receive the echo light output from the edge of the prism. If the ratio of D1 to D0 is greater than 2, a portion of the area of ​​the lens closest to the object side in the lens group will not receive the echo light output from the prism, resulting in waste of the lens. By adopting the above technical solution, the lens group can receive as much of the echo light output from the prism as possible, that is, the utilization rate of the echo light is improved. In addition, it can also reduce the waste of a large portion of the lens area.

[0018] In some possible implementations, the ratio of the prism's aperture D0 to its minimum thickness H satisfies: D0 / H ≤ 20; the minimum thickness is the minimum of the distances between the second surface and the first side surface, and between the first surface and the first side surface. If the ratio of D0 to H is greater than 20, while the prism's aperture D0 meets the requirements, the minimum thickness H is too small, which will lead to the prism being too thin and prone to cracking or breakage during use. Therefore, the above-described solution can reduce the occurrence of cracks or breakage in the prism.

[0019] In some possible implementations, the angle α1 between the extending direction of the first surface and the extending direction of the first side surface satisfies: α1 ≤ 45°. When the laser receiving system of this application is applied to a lidar, the angle between the extending direction of the first surface and the extending direction of the first side surface determines the receiving angle of the lidar. By adopting the above scheme, the basic receiving angle of the lidar can be satisfied, while also reducing the waste caused by an excessively large detection range due to an excessively large angle between the extending direction of the first surface and the extending direction of the first side surface.

[0020] In some possible implementations, the angle α2 between the extension direction of the third surface and the extension direction of the first side surface satisfies: α2 ≤ 45°. When the laser receiving system of this application is applied to a lidar, the angle between the extension direction of the third surface and the extension direction of the first side surface determines the receiving angle of the lidar. By adopting the above scheme, the basic receiving angle of the lidar can be satisfied, while also reducing the waste caused by an excessively large detection range due to an excessively large angle between the extension direction of the third surface and the extension direction of the first side surface.

[0021] In some possible implementations, the laser receiving system also includes a reflective element located between the prism and the detection device, which deflects the light. This reduces the length of the laser receiving system, thereby reducing its overall size.

[0022] In some possible implementations, the ratio of the distance L1 from the center of the reflecting surface of the reflective element to the detection surface of the detection device, to the distance L2 from the side of the prism facing away from the lens group to the center of the reflecting surface of the reflective element, satisfies the condition: 0.25 ≤ L1 / L2 ≤ 9. When the ratio of L1 to L2 is less than 0.25 or greater than 9, the difference between the distance from the center of the reflecting surface to the detection surface and the distance from the input surface of the prism to the center of the reflecting surface is large, resulting in a still large length or width dimension of the laser receiving system. Therefore, by adopting the above-described scheme, the length or width dimension of the laser receiving system can be reduced.

[0023] In some possible implementations, the detection device includes at least three detectors. At least three detectors can receive light rays with different angles to the center from the echo beam and perform detection; therefore, the laser receiving system can fulfill basic detection functions.

[0024] This application also provides a lidar system, including a laser emitting system and a laser receiving system as described above. The lidar system can achieve all the effects of the laser receiving system. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the lidar structure in the embodiments of this application;

[0027] Figure 2 This is a schematic diagram of the structure of a laser receiving system in related technologies;

[0028] Figure 3a This is a schematic diagram of the structure of a laser receiving system in one embodiment of this application;

[0029] Figure 3b for Figure 3a The diagram shows the propagation of echo rays in the laser receiving system.

[0030] Figure 4 for Figure 3a The diagram shows the structure of the prism in the laser receiving system shown.

[0031] Figure 5 A comparison diagram of rays with equal and non-equal field of view;

[0032] Figure 6a for Figure 3a The laser receiving system shown is a spot pattern of the detection surface corresponding to the first region.

[0033] Figure 6b for Figure 3a The laser receiving system shown is a spot pattern on the detection surface corresponding to the second region.

[0034] Figure 6c for Figure 3a The laser receiving system shown is a spot pattern of the detection surface corresponding to the third region.

[0035] Figure 7a This is a schematic diagram of the prism structure in another embodiment of this application;

[0036] Figure 7b This is a schematic diagram of the structure of the laser receiving system in another embodiment of this application;

[0037] Figure 8a This is a schematic diagram of the structure of the laser receiving system in another embodiment of this application;

[0038] Figure 8b for Figure 8a The diagram shows the propagation of echo rays in the laser receiving system.

[0039] Figure 9 for Figure 8a The diagram shows the structure of the prism in the laser receiving system shown.

[0040] Figure 10a for Figure 8a The laser receiving system shown is a spot pattern of the detection surface corresponding to the first region.

[0041] Figure 10b for Figure 8aThe laser receiving system shown is a spot pattern on the detection surface corresponding to the second region.

[0042] Figure 10c for Figure 8a The laser receiving system shown is a spot pattern of the detection surface corresponding to the third region.

[0043] Figure 10d for Figure 8a The laser receiving system shown is a spot pattern on the detection surface corresponding to the fourth region.

[0044] Figure 10e for Figure 8a The laser receiving system shown is a spot pattern on the detection surface corresponding to the fifth region.

[0045] Figure 11 This is a schematic diagram of the structure of a laser receiving system in another embodiment of this application;

[0046] Figure 12 This is a schematic diagram of the structure of a laser receiving system in another embodiment of this application.

[0047] Icons: 100-LiDAR; 10-Laser Emitting System; 20-Laser Receiving System; 201-Reflector; 202-Upper Receiving Module; 203-Middle Receiving Module; 204-Lower Receiving Module; 21-Prism; 211-First Side; 212-Second Side; 2121-First Surface; 2122-Second Surface; 2123-Third Surface; 2124-Fourth Surface; 2125-Fifth Surface; 2126-Sixth Surface; 2127-First Region; 2128-Second Region; 2129- Third region; 2130-Fourth region; 2131-Fifth region; 2132-First side; 2133-Second side; 2134-Seventh surface; 213-First end face; 214-Second end face; 22-Lens group; 221-First lens; 222-Second lens; 223-Third lens; 224-Fourth lens; 225-Fifth lens; 226-Sixth lens; 23-Detection device; 231-Detector; 232-Detection surface; 24-Reflective element; 241-Reflective surface; 30-Target object. Detailed Implementation

[0048] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0049] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0050] The terms "first" and "second," etc., used in the specification and claims of this application are used to distinguish different objects, not to describe a specific order of objects. For example, "first target object" and "second target object," etc., are used to distinguish different target objects, not to describe a specific order of target objects.

[0051] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0052] In the description of the embodiments in this application, unless otherwise stated, "multiple" means two or more. For example, multiple processing units means two or more processing units; multiple systems means two or more systems.

[0053] Radar technology, as a weak-sensing detection system, can accurately detect the outline of targets and obtain their depth information, both day and night. Compared to traditional technologies such as millimeter-wave radar and ultrasonic radar, lidar operates in a shorter wavelength band, thus significantly improving detection resolution and range. This makes lidar an indispensable technology in both military and civilian fields.

[0054] In fields such as autonomous driving and robotics, LiDAR offers advantages over camera-based vision solutions, including all-weather operation, higher measurement resolution, stronger anti-interference capabilities, and greater penetration. It enables autonomous perception of the road environment and assists vehicles in achieving predetermined goals. Therefore, LiDAR has broad application prospects in the future.

[0055] like Figure 1As shown, the lidar 100 includes a laser emitting system 10 and a laser receiving system 20. The laser emitting system 10 emits a laser line with a certain power, which is diffusely reflected by the target object 30 and returns as an echo, which is then received by the laser receiving system 20. As one of the most important modules in the lidar 100, the laser receiving system 20 is responsible for detecting the diffuse reflection echo signal of the object. Depending on the different laser emitting systems 10, the laser receiving system 20 needs to be customized to receive a sufficient amount of echo light. On this basis, it also needs to ensure a considerable signal-to-noise ratio to prevent optical system noise from affecting signal detection.

[0056] In related technologies, such as Figure 2 As shown, the laser receiving system 20 includes a reflector 201 and an upper receiving module 202, a middle receiving module 203, and a lower receiving module 204 arranged perpendicular to the optical path. The reflector 201 is used to reflect the echo light after diffuse reflection from the target object to each receiving module. The echo light reflected by the reflector 201 typically contains multiple sets of light rays at different angles to the optical path, and each receiving module can be used to receive the reflected light rays at different angles. Each receiving module consists of multiple optical lenses, requiring a significant amount of volume both along the optical path and perpendicular to it, resulting in a larger size for the laser receiving system 20 and thus increasing the size of the lidar 100. Furthermore, the structure of multiple receiving modules increases the complexity and cost of the laser receiving system 20, and the assembly process involves more steps, increasing the assembly difficulty.

[0057] Based on this, such as Figure 3a As shown, this application embodiment provides a laser receiving system 20, which includes a prism 21, a lens group 22, and a detection device 23 arranged sequentially. The lens group 22 includes at least two lenses arranged from the object side to the image side. In application, the laser receiving system 20 of this application embodiment receives the echo light after diffuse reflection from the target object, which then illuminates the prism 21, passes through the lens group 22, and reaches the detection device 23. After receiving the echo light, the detection device 23 can obtain parameters of the target object based on the echo light, thereby completing the detection of the target object. Since the second side surface 212 of the prism 21 includes at least two first surfaces 2121 and second surfaces 2122 with an included angle, the first surfaces 2121 and second surfaces 2122 can receive echo light at different angles respectively. The lens group 22 includes at least two lenses arranged along the optical path, eliminating the need for multiple receiving modules, thereby reducing the size of the laser receiving system 20. When at least one lens in the lens group 22 has positive optical power, the lens with positive optical power can converge the echo light, thereby enabling the detection device 23 to receive all the echo light as much as possible.

[0058] To facilitate understanding of the laser receiving system 20 provided in the embodiments of this application, the relevant terms used in this application are explained as follows:

[0059] Positive focal length refers to having a positive focal length and the effect of converging light.

[0060] The object side refers to the direction in which the echo light enters the laser receiving system 20.

[0061] Image side refers to the direction from which the echo light is emitted from the laser receiving system 20.

[0062] The aperture of a lens refers to the diameter of the lens.

[0063] For ease of description, three directions can be defined: the first direction (Y-axis), the second direction (Z-axis), representing the direction of the optical path of the laser receiving system 20; and the third direction (X-axis). Figure 3a (not shown in the image) indicates directions perpendicular to the Z and Y directions, respectively.

[0064] The components of the laser receiving system 20 according to the embodiments of this application will now be described in detail.

[0065] like Figure 4 As shown, the prism 21 has opposing first side surface 211, second side surface 212, and opposing first end surface 213 and second end surface 214, wherein the first side surface 211 and the second side surface 212 are both located between the first end surface 213 and the second end surface 214.

[0066] like Figure 3b As shown, in this embodiment, the first side surface 211 is the input surface of the echo light, and the second side surface 212 is the output surface of the echo light. The first side surface 211 can be a plane.

[0067] like Figure 4 As shown, the second side surface 212 includes a first surface 2121 and a second surface 2122, with an included angle between the first surface 2121 and the second surface 2122. The number of first surfaces 2121 is at least two, with a portion of the first surfaces 2121 located on a first side 2132 of the second surface 2122, and another portion of the first surfaces 2121 located on a second side 2133 of the second surface 2122. For example, as... Figure 4 As shown, there are two first surfaces 2121, one of which is located on the first side 2132 of the second surface 2122, and the other is located on the second side 2133 of the second surface 2122. Both the first surface 2121 and the second surface 2122 are planar.

[0068] like Figure 4As shown, the extending directions of the two first surfaces 2121 form an angle with the extending direction of the first side surface 211, and the second surface 2122 is parallel to the first side surface 211. Thus, the second surface 2122 is located in the center of the prism 21, and can receive light within a small angle range from the center of the echo beam, ensuring that the light within this small angle range is not deflected after passing through the prism 21. The first surfaces 2121 located on either side of the second surface 2122 can receive light within a larger angle range from the center of the echo beam, reducing the field of view of this portion of the light, thereby ensuring that all echo beams emitted from the prism 21 can be received by the lens group 22. Therefore, the laser receiving system 20 can receive echo beams with a larger field of view.

[0069] like Figure 4 As shown, the angle α1 between the extending direction of the first surface 2121 and the extending direction of the first side surface 211 is less than or equal to 45°. For example, the angle α1 can specifically be 19°, 22°, 25°, or 45°. When the laser receiving system 20 of this embodiment is applied to the lidar 100, the angle between the extending direction of the first surface 2121 and the extending direction of the first side surface 211 affects the detection range of the lidar 100. By adopting the above solution, the basic detection range of the lidar 100 can be satisfied, while also reducing the waste caused by an excessively large detection range due to an excessively large angle between the extending direction of the first surface 2121 and the extending direction of the first side surface 211. When the angle between the extending direction of the first surface 2121 and the extending direction of the first side surface 211 is 19°, the angle range between the center of the echo light received by the first surface 2121 and the center of the echo light reflected to the first side surface 211 is greater than or equal to 9.4° and less than or equal to 8.6°. The second surface 2122 is capable of receiving an angle between the center of the echo light reflected to the first side surface 211 and the center of the echo light, which is less than or equal to 1.5°.

[0070] like Figure 4 As shown, the distance between the first surface 2121 and the first side surface 211 gradually increases from the end furthest from the second surface 2122 to the end closest to the second surface 2122. In other words, the prism 21 is thicker in the middle and thinner at both ends. This allows the first surface 2121, furthest from the second surface 2122, to deflect the received echo light and reduce the field of view of the echo light, thus enabling the echo light to illuminate the lens closest to the object side in the lens group 22. Consequently, the laser receiving system 20 can receive echo light with a larger field of view. Furthermore, it also reduces the beam aperture of the lens closest to the prism 21.

[0071] like Figure 4As shown, the ratio K1 between the first dimension L5 of the projection of the first surface 2121 onto the first side surface 211 along the Y direction and the second dimension L6 of the second surface 2122 along the Y direction satisfies: 0.2 ≤ K1 ≤ 5. For example, the ratio K can specifically take values ​​of 0.2, 0.35, 0.7, 1, 4, or 5. Figure 4 As can be seen, the first direction is also the arrangement direction of the first surface 2121 and the second surface 2122. When K1 is 0.2, the second surface 2122 in the middle has a larger dimension along the first direction, while the first surface 2121 has a smaller dimension along the first direction, which is suitable for echo light with a larger range in the middle. When K1 is 5, the first surface 2121 has a larger dimension along the first direction, while the second surface 2122 in the middle has a smaller dimension along the first direction, which is suitable for scenarios with a large range of light and a large field of view. Therefore, the laser receiving system 20 has a wider range of applications.

[0072] like Figure 3a As shown, the ratio of the first aperture D0 of prism 21 to the minimum thickness H of prism 21 satisfies: D0 / H ≤ 20. For example, this ratio can specifically be 3.5, 4.28, 10, 15, or 20. The minimum thickness is the minimum value among the distances between the second surface 2122 and the first side surface 211, and between the first surface 2121 and the first side surface 211. The aperture of prism 21 refers to the distance from the first end face 213 to the second end face 214. If the ratio of D0 to H is greater than 20, while the aperture D0 of prism 21 meets the requirements, the minimum thickness H of prism 21 is too small. This will cause prism 21 to crack or break during use due to its excessive thinness. Therefore, the above solution can reduce the occurrence of cracks or breakage in prism 21.

[0073] Lens group 22 includes at least two lenses arranged from the object side to the image side. For example, such as... Figure 3a As shown, the lens group 22 contains six lenses. For ease of description, the six lenses from the object side to the image side are named first lens 221, second lens 222, third lens 223, fourth lens 224, fifth lens 225, and sixth lens 226, respectively. The first lens 221 is the lens closest to the object side and has positive optical power. Therefore, the first lens 221 can converge light rays to compress the beam aperture of the other lenses in the lens group 22. Furthermore, the first lens 221 and the prism 21 are located on the same optical axis.

[0074] The sixth lens 226 is the lens closest to the image side, and it can also have positive optical power. In this way, the sixth lens 226 can converge the light rays to each detector 231 in the detection device 23.

[0075] like Figure 3a As shown, the ratio of the aperture D1 of the first lens 221 to the aperture D0 of the prism 21 satisfies: 0.8 ≤ D1 / D0 ≤ 2. For example, this ratio can specifically be 0.8, 1, 1.5, or 2. The aperture of the prism 21 is the distance between the first end face 213 and the second end face 214. If the ratio of D1 to D0 is less than 0.8, the lens closest to the object side in the lens group 22 will not receive the echo light output from the edge of the prism 21. If the ratio of D1 to D0 is greater than 2, a portion of the lens closest to the object side in the lens group 22 will not receive the echo light output from the prism 21, resulting in wastage of the lens. By adopting the above technical solution, the lens group 22 can receive as much of the echo light output from the prism 21 as possible, thus improving the utilization rate of the echo light and reducing the waste of a large portion of the lens area.

[0076] Of the multiple lenses in lens group 22, at least one is a cylindrical lens, and the others are spherical lenses. The cylindrical lens is located between the lens with positive optical power and the detection device 23; that is, the cylindrical lens is located between the first lens 221 and the detection device 23. For example, as shown... Figure 3a As shown, there are two cylindrical mirrors: the third lens 223 and the fourth lens 224 are both cylindrical mirrors, located between the second lens 222 and the fifth lens 225. In other embodiments, the number of cylindrical mirrors can be one, three, or more, and the cylindrical mirrors can be located closest to the image side. Since cylindrical mirrors can scatter light in one direction, they can adjust ray rays with a constant field of view to rays with a non-constant field of view, or vice versa, to better meet the needs of the detection device 23.

[0077] It should be noted that equal field-of-view rays refer to rays with the same field of view in two perpendicular directions. For example, such as... Figure 5 As shown, Figure 5 The diagram on the left shows the projection of rays with equal field of view onto the receiving surface. The field of view is the same in both the X and Y directions, at 0.4°. Rays with non-equal field of view refer to rays with different field of view in two perpendicular directions. For example, ... Figure 5 As shown, Figure 5 The diagram on the right shows the projection of rays with non-uniform field of view onto the receiving surface. The field of view of the rays differs in the X and Y directions; the field of view in the X direction is 0.8°, and in the Y direction it is 0.4°. Figure 3aAs shown, the detection device 23 includes multiple detectors 231, each detector 231 having a detection surface 232, which can be rectangular or square. When the detection surface 232 is rectangular, it indicates that the dimensions of the detection surface 232 are different in the X and Y directions. Therefore, the echo light emitted from the lens group 22 is required to be non-uniform field-of-view light. If the light incident on the prism 21 is uniform field-of-view light, the cylindrical mirror can adjust the uniform field-of-view light into non-uniform field-of-view light. If the echo light incident on the prism 21 is non-uniform field-of-view light and the detection surface 232 is square, the echo light emitted from the lens group 22 is required to be uniform field-of-view light. The cylindrical mirror can then adjust the non-uniform field-of-view light into uniform field-of-view light. In this embodiment, the two cylindrical mirrors can scatter light in the same direction.

[0078] like Figure 3a As shown, the ratio of the distance L3 from the third lens 223 to the detector surface 232 to the distance TTL from the first side surface 211 of the prism 21 to the detector surface 232 satisfies: L3 / TTL=0.55, and the ratio of the distance L4 from the fourth lens 224 to the detector surface 232 to the distance TTL from the first side surface 211 of the prism 21 to the detector surface 232 satisfies: L4 / TTL=0.46.

[0079] Table 1 shows the surface type, radius of curvature, thickness, spacing between adjacent lenses, refractive index, and Abbe number of each lens in lens group 22. In Table 1, surfaces S0-S13 refer to: the object-side surface S1 of the first lens 221, the image-side surface S2 of the first lens 221, the object-side surface S3 of the second lens 222, the image-side surface S4 of the second lens 222, the object-side surface S5 of the third lens 223, the image-side surface S6 of the third lens 223, the object-side surface S7 of the fourth lens 224, the image-side surface S8 of the fourth lens 224, the object-side surface S9 of the fifth lens 225, the image-side surface S10 of the fifth lens 225, the object-side surface S11 of the sixth lens 226, the image-side surface S12 of the sixth lens 226, and the image plane S13. The third lens 223 and the fourth lens 224 are both cylindrical mirrors, and their scattering direction is the X-axis. The image plane refers to the detector surface 232. The radius of curvature in Table 1 is Infinity, indicating infinity.

[0080] Table 1

[0081]

[0082]

[0083] Table 2 shows the basic parameters of prism 21. For ease of description, as follows: Figure 4As shown, each of the first surfaces 2121 can be named the third surface 2123 and the fourth surface 2124 along the Y direction, where the third surface 2123 is the first surface 2121 closest to the first end face 213. In Table 2, the first region 2127 refers to the region between the third surface 2123 and its projection on the first side face 211; the second region 2128 refers to the region between the second surface 2122 and its projection on the first side face 211; and the third region 2129 refers to the region between the fourth surface 2124 and its projection on the first side face 211. The diameter of the region refers to its size along the Y direction. The surface tilt angle of the first region 2127 refers to the angle between the extension direction of the third surface 2123 and the extension direction of the first side surface 211. The surface tilt angle of the third region 2129 refers to the angle between the extension direction of the fourth surface 2124 and the extension direction of the first side surface 211. The sign of the surface tilt angle is used to indicate the extension direction. When the angle is negative, it indicates that the surface extends from the second surface 2122 toward the first end face 213. When the angle is positive, it indicates that the surface extends from the second surface 2122 toward the second end face 214.

[0084] Table 2

[0085]

[0086] The detection device 23 includes at least three detectors 231, exemplarily, such as... Figure 3a As shown, there are 10 detectors 231, among which, as Figure 3b As shown, the two detectors 231 at both ends are mainly used to receive the echo light emitted from the first surface 2121 and after passing through the lens group 22, while the eight detectors 231 in the middle are mainly used to receive the echo light emitted from the second surface 2122 and after passing through the lens group 22. The detectors 231 in the detection device 23 can be one or more of the following: avalanche diode, silicon photomultiplier tube, avalanche diode array, multi-pixel photon counter, photomultiplier tube, and single-photon avalanche diode.

[0087] like Figure 3bAs shown, the echo light rays diffusely reflected by the target object enter from the first side 211 of the prism 21 and exit from the second side 212, which reduces the field of view of the echo light rays. The echo light rays exiting from the second side 212 illuminate the first lens 221, and after being converged by the first lens 221, they illuminate the second lens 222. After being converged again by the second lens 222, they pass through the third lens 223 and the fourth lens 224 in sequence, adjusting the equiproportional field of view light rays into non-equiproportional field of view light rays before reaching the fifth lens 225. The fifth lens 225 scatters the non-equiproportional field of view light rays and illuminates the sixth lens 226. The sixth lens 226 can converge the non-equiproportional field of view light rays into 10 groups of light rays. Each group of light rays illuminates each detector 231 of the detection device 23. After receiving the light rays, the detector 231 can obtain the parameters of the target object 30 based on the light rays.

[0088] The following is a simulation experiment of the laser receiving system 20 according to an embodiment of this application. Figure 6a , Figure 6b and Figure 6c This is a simulation experiment result image (spot image). For example... Figure 6a As shown, the first region 2127, the second region 2128, and the third region 2129 receive echo rays from different field-of-view angles. The size of the detection surface 232 corresponding to the first region 2127 and the third region 2129 is 1.3 × 1.1 mm, and the size of the detection surface 232 corresponding to the second region 2128 is 1.3 × 20 mm. (From Figure 6a...) Figure 6b and Figure 6c As can be seen, most of the echo light rays can illuminate the detector surface 232, and only a very small number of echo light rays fail to illuminate the detector surface 232. According to specific calculations and analysis, more than 95% of the echo light rays can illuminate the detector surface 232. Therefore, the laser receiving system 20 of this embodiment has a high efficiency in receiving echo light rays.

[0089] In other embodiments of this application, with Figure 3a The difference in the illustrated embodiment lies in the structure of the second side surface 212 of the prism 21. In this embodiment, as... Figure 7a As shown, the second side surface 212 includes a second surface 2122 and two first surfaces 2121 located on both sides of the second surface 2122. The distance between the two first surfaces 2121 and the first side surface 211 gradually decreases from the first end face 213 toward the direction of connection with the second surface 2122.

[0090] In other embodiments of this application, with Figure 3a The difference in the illustrated embodiment lies in the different orientation of the prism 21. Specifically, in Figure 3aIn the illustrated embodiment, the first side surface 211 is the input surface of the echo light, and the second side surface 212 is the output surface of the echo light; that is, the second side surface 212 faces the lens group 22. In this embodiment, as... Figure 7b As shown, the first side surface 211 is the output surface of the echo light, that is, the first side surface 211 faces the lens group 22, and the second side surface 212 is the input surface of the echo light.

[0091] In other embodiments of this application, such as Figure 8a and Figure 8b As shown, with Figure 3a The difference in the embodiments shown is that the structure of the second side surface 212 of the prism 21, the structure of the lens group 22, and the number of detectors 231 in the detection device 23 are different.

[0092] Specifically, such as Figure 3a As shown, the prism 21 includes two first surfaces 2121 and one second surface 2122. In this embodiment, as... Figure 9 As shown, the prism 21 includes two first surfaces 2121 and one second surface 2122, as well as at least one third surface 2123, located on the side of the first surface 2121 away from the second surface 2122. For example, there are two third surfaces 2123, one located on the first side 2132 and the other on the second side 2133. In other embodiments, there are three, four, five, or more third surfaces 2123, and the number of third surfaces 2123 on both sides of the second surface 2122 may be the same or different. When there are multiple third surfaces 2123 on the first side 2132, the multiple third surfaces 2123 can be connected sequentially, and each pair of adjacent third surfaces 2123 has an included angle.

[0093] The ratio K2 between the dimension of the projection of the third surface 2123 onto the first side surface 211 along the first direction and the dimension of the second surface 2122 along the first direction satisfies: 0.2 ≤ K2 ≤ 5; the first direction is the arrangement direction of the third surface 2123 and the second surface 2122. When K2 is 0.2, the dimension of the second surface 2122 in the middle along the first direction is larger, and the dimension of the third surface 2123 along the first direction is smaller, which is suitable for echo light with a larger range in the middle; when K2 is 5, the dimension of the third surface 2123 along the first direction is larger, and the dimension of the second surface 2122 in the middle along the first direction is smaller, which is suitable for scenes with a larger range of light and a larger field of view. Therefore, the laser receiving system 20 has a wider range of applications.

[0094] The angle α2 between the extending direction of the third surface 2123 and the extending direction of the first side surface 211 satisfies: α2 ≤ 45°. When the laser receiving system 20 of this application is applied to the lidar 100, the angle between the extending direction of the third surface 2123 and the extending direction of the first side surface 211 determines the receiving angle of the lidar 100. By adopting the above scheme, the basic receiving angle of the lidar 100 can be satisfied, while also reducing the waste caused by an excessively large detection range of the lidar 100 due to an excessively large angle between the extending direction of the third surface 2123 and the extending direction of the first side surface 211.

[0095] like Figure 9 As shown, for ease of description, the surfaces on the second side surface 212 along the Y direction can be named as: seventh surface 2134, fourth surface 2124, fifth surface 2125, and sixth surface 2126, where the seventh surface 2134 is the third surface 2123 closest to the first end face 213. The distance between the two third surfaces 2123 (i.e., the seventh surface 2134 and the sixth surface 2126) located at both ends of the prism 21 and the first side surface 211 gradually increases from the end away from the second surface 2122 to the end closer to the second surface 2122; the distance between the two third surfaces 2123 (i.e., the fourth surface 2124 and the fifth surface 2125) near the middle of the prism 21 and the first side surface 211 gradually increases from the end away from the second surface 2122 to the end closer to the second surface 2122. Thus, as Figure 8b As shown, the two first surfaces 2121 and the two third surfaces 2123 can respectively receive echo rays with a large angle between them and the center, and deflect them to reduce the angle between them and the center, so that this part of the echo rays can be received by the lens group 22; the second surface 2122 receives light rays with a small angle between them and the center, and keeps this part of the echo rays from being deflected, so that this part of the echo rays can be received by the lens group 22. When the surface area of ​​the target object 30 is large, it reflects more echo rays, and multiple different echo rays have different centers. Therefore, the prism 21 of this embodiment can receive more echo rays with different centers, thereby making the laser receiving system 20 of this embodiment suitable for target objects 30 with more complex surfaces.

[0096] like Figure 8bAs shown, lens group 22 includes four lenses, namely, first lens 221, second lens 222, third lens 223, and fourth lens 224 from the object side to the image side. The light input and output surfaces of the first lens 221, second lens 222, third lens 223, and fourth lens 224 are all spherical. When the echo ray incident on prism 21 is a ray with a uniform field of view, and the detector surface 232 is also square, then both the echo ray incident on and exiting from lens group 22 are rays with a uniform field of view.

[0097] Table 3 shows the basic parameters of the lens group 22 in this embodiment. In Table 3, surfaces S0-S9 refer to: the object-side surface of the first lens 221 (S1), the image-side surface of the first lens 221 (S2), the object-side surface of the second lens 222 (S3), the image-side surface of the second lens 222 (S4), the object-side surface of the third lens 223 (S5), the image-side surface of the third lens 223 (S6), the object-side surface of the fourth lens 224 (S7), the image-side surface of the fourth lens 224 (S8), and the image plane (S9). In Table 1, the radius of curvature is "Infinity," indicating infinity, and the image plane refers to the detection surface 232.

[0098] Table 3

[0099]

[0100]

[0101] Table 4 shows the basic parameters of prism 21. Among them, such as... Figure 9As shown, the first region 2127 refers to the region between the seventh surface 2134 and its projection onto the first side surface 211; the second region 2128 refers to the region between the fourth surface 2124 and its projection onto the first side surface 211; the third region 2129 refers to the region between the second surface 2122 and its projection onto the first side surface 211; the fourth region 2130 refers to the region between the fifth surface 2125 and its projection onto the first side surface 211; and the fifth region 2131 refers to the region between the sixth surface 2126 and its projection onto the first side surface 211. The aperture of a region refers to its dimension along the Y direction. The surface tilt angle of the first region 2127 refers to the angle between the extension direction of the third surface 2123 and the extension direction of the first side surface 211. The sign of the surface tilt angle indicates the extension direction. When the angle is negative, it indicates that the surface extends from the second surface 2122 toward the first end face 213; when the angle is positive, it indicates that the surface extends from the second surface 2122 toward the second end face 214. The surface tilt angles of other regions have similar meanings to the surface tilt angle of the first region 2127, and will not be repeated here.

[0102] Table 4

[0103]

[0104]

[0105] In this embodiment, as Figure 8b As shown, the detection device 23 has five detectors 231, which are used to receive the echo light emitted from the seventh surface 2134, the fourth surface 2124, the second surface 2122, the fifth surface 2125 and the sixth surface 2126, respectively.

[0106] The following is a simulation experiment of the laser receiving system 20 in this embodiment. Figure 10a , Figure 10b , Figure 10c , Figure 10d and Figure 10e This is a simulation experiment result image (spot image). For example... Figure 10a As shown, the first region 2127, the second region 2128, the third region 2129, the fourth region 2130, and the fifth region 2131 receive echo rays from different field-of-view angles. The size of the detection surface 232 corresponding to the first region 2127, the second region 2128, the fourth region 2130, and the fifth region 2131 is 0.4 × 0.2 mm, while the size of the detection surface 232 corresponding to the third region 2129 is 0.5 × 0.3 mm. Figure 10aAs can be seen in Figure 10e, most of the echo light can illuminate the detector surface 232, and only a very small number of echo light rays do not illuminate the detector surface 232. According to specific calculation and analysis, more than 95% of the echo light rays can illuminate the detector surface 232. It can be seen that the laser receiving system 20 of this application embodiment has a high reception efficiency for echo light rays.

[0107] In other embodiments of this application, such as Figure 11 As shown, with Figure 3a The difference in the illustrated embodiment lies in the structure of the lens group 22. Specifically, in this embodiment, the lens group 22 is removed. Figure 3a The two cylindrical mirrors shown (third lens 223 and fourth lens 224), that is, the lens group 22 in this embodiment includes a first lens 221, a second lens 222, a fifth lens 225, and a sixth lens 226. The first lens 221, the second lens 222, the fifth lens 225, and the sixth lens 226 are all spherical lenses. In this embodiment, the lens group 22 is capable of receiving and emitting light rays with an equal field of view.

[0108] In other embodiments of this application, such as Figure 12 As shown, with Figure 3a The difference in the illustrated embodiment is that, in this embodiment, in Figure 3a The illustrated embodiment includes the addition of a reflective element 24. Specifically, as shown... Figure 12 As shown, the laser receiving system 20 includes a prism 21, a lens group 22, a reflecting element 24, and a detection device 23. The reflecting element 24 is located between the prism 21 and the detection device 23, and is used to deflect the echo light. This reduces the length of the laser receiving system 20, thereby reducing its overall size.

[0109] The reflecting element 24 can be a mirror, for example, a plane mirror. A first optical path can be formed between the prism 21 and the reflecting surface 241 of the reflecting element 24, and a second optical path can be formed between the reflecting surface 241 and the detecting surface 232 of the detecting device 23. When the reflecting element 24 is a plane mirror 201, the angle between the incident light ray of the reflecting element 24 and the reflecting surface 241 can be 45°, so that the angle between the first optical path and the second optical path is 90°, thereby minimizing the size of the laser receiving system 20.

[0110] The ratio of the distance L1 from the center of the reflecting surface 241 of the reflecting element 24 to the detection surface 232 of the detection device 23, to the distance L2 from the input surface of the prism 21 to the center of the reflecting surface 241 of the reflecting element 24, satisfies the condition: 0.25 ≤ L1 / L2 ≤ 9. When the ratio of L1 to L2 is less than 0.25 or greater than 9, the difference between the distance from the center of the reflecting surface 241 to the detection surface 232 and the distance from the input surface of the prism 21 to the center of the reflecting surface 241 is large, resulting in a still large length or width dimension of the laser receiving system 20. Therefore, by adopting the above-described scheme, the length or width dimension of the laser receiving system 20 can be reduced.

[0111] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A laser receiving system, characterized in that, It includes a prism, a lens group, and a detection device arranged in sequence, wherein: The prism has a first side and a second side, the second side comprising a first surface and a second surface having an included angle, the first side or the second side facing the lens group; the prism is used to receive the echo light after diffuse reflection from the target object. The lens group includes at least two lenses arranged from the object side to the image side, and at least one of the lenses has positive optical power. The object side is the side where the prism is located, and the image side is the side where the detection device is located. The prism and the lens in the lens group that is closest to the object side are located on the same optical axis.

2. The laser receiving system according to claim 1, characterized in that, The lens closest to the object side in the lens group has positive optical power.

3. The laser receiving system according to claim 1, characterized in that, The first surface extends at an angle to the first side surface, and the second surface is parallel to the first side surface.

4. The laser receiving system according to claim 1, characterized in that, The number of the first surfaces is at least two, with a portion of the first surfaces located on a first side of the second surface and another portion of the first surfaces located on a second side of the second surface opposite to the first side.

5. The laser receiving system according to claim 4, characterized in that, The prism further includes at least one third surface, wherein at least one third surface is located on the side of the first surface away from the second surface; When there are multiple third surfaces, the multiple third surfaces are connected in sequence, and every two adjacent third surfaces have an angle between them. The third surface closest to the first surface has an angle between it and the first surface.

6. The laser receiving system according to claim 5, characterized in that, The distance between the third surface, which is furthest from the second surface, and the first side surface gradually increases from the end furthest from the second surface to the end closest to the second surface.

7. The laser receiving system according to any one of claims 2-6, characterized in that, The lens group includes a cylindrical mirror, which is located between the lens with positive optical power and the detection device.

8. The laser receiving system according to any one of claims 1-6, characterized in that, The lens closest to the detection device in the lens group has positive optical power.

9. The laser receiving system according to any one of claims 1-6, characterized in that, The ratio K1 between the dimension of the projection of the first surface onto the first side surface along the first direction and the dimension of the second surface along the first direction satisfies: 0.2≤K1≤5； The first direction is the arrangement direction of the first surface and the second surface.

10. The laser receiving system according to claim 5 or 6, characterized in that, The ratio K2 of the projection of the third surface onto the first side surface along the first direction to the dimension of the second surface along the first direction satisfies: 0.2≤K2≤5； The first direction is the arrangement direction of the third surface and the second surface.

11. The laser receiving system according to any one of claims 1-6, characterized in that, The prism has a first end face and a second end face, and the first side face and the second side face are both located between the first end face and the second end face. The ratio of the aperture D1 of the lens closest to the object side in the lens group to the aperture D0 of the prism satisfies: 0.8≤D1 / D0≤2; The aperture of the prism is the distance between the first end face and the second end face.

12. The laser receiving system according to any one of claims 1-6, characterized in that, The ratio of the aperture D0 of the prism to the minimum thickness H of the prism satisfies: D0 / H≤20; The minimum thickness is the minimum value among the distances between the second surface and the first side surface, and the distances between the first surface and the first side surface.

13. The laser receiving system according to any one of claims 1-6, characterized in that, The angle α1 between the extending direction of the first surface and the extending direction of the first side surface satisfies: a1≤45°。 14. The laser receiving system according to claim 5 or 6, characterized in that, The angle α2 between the extending direction of the third surface and the extending direction of the first side surface satisfies: a2≤45°。 15. The laser receiving system according to any one of claims 1-6, characterized in that, The laser receiving system also includes a reflective element located between the prism and the detection device, which is used to deflect light.

16. The laser receiving system according to claim 15, characterized in that, The ratio of the distance L1 from the center of the reflecting surface of the reflecting element to the detection surface of the detection device to the distance L2 from the side of the prism facing away from the lens group to the center of the reflecting surface of the reflecting element satisfies the following condition: 0.25≤L1 / L2≤9.

17. The laser receiving system according to any one of claims 1-6, 16, characterized in that, The detection device includes at least three detectors.

18. A lidar system, characterized in that, It includes a laser emitting system and a laser receiving system as described in any one of claims 1-17.

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