Diffusion unit, transmission system, lidar and vehicle

Abstract

This invention relates to the technical field of lidar, specifically providing a diffusion unit, a transmitting system, lidar, and a vehicle, aiming to solve the problem of the large number of laser emitters used in existing transmitting systems. To this end, the diffusion unit of this invention includes a lens group comprising multiple lenses arranged sequentially. The refractive index of each lens is greater than the refractive index of the medium surrounding the lens. The lenses can refract and reflect incident light, producing refracted and reflected light. From the first end to the second end of the lens group, refracted light emitted from one lens can enter the next lens and undergo refraction and reflection. Laser light enters from the first end, passes through multiple lenses for refraction and reflection, and the reflected light generated by the multiple lenses forms a linear laser array, thereby reducing the number of laser emitters used in the transmitting system employing this diffusion unit.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicles, and particularly provides a diffusion unit, a transmitting system, a laser radar and a vehicle. BACKGROUND

[0002] The laser radar is a key component for realizing automatic driving. The laser radar can map objects around the vehicle body to form a high-precision 3D map, and the vehicle can automatically drive according to the map formed by the laser radar mapping. The laser radar includes a transmitting system and a receiving system. The transmitting system can emit a planar laser array to a specified direction. The laser is reflected after encountering an obstacle and is received by the receiving system. After receiving the reflected laser, the receiving system calculates the propagation distance between the transmitting system and the target object by the time of flight of the laser, and can also present the accurate three-dimensional structure information of the target object by detecting the energy size and the amplitude, frequency and phase of the reflected laser.

[0003] The laser radar is divided into three types according to the different transmitting systems, namely mechanical laser radar, semi-solid laser radar and solid-state laser radar. In the solid-state laser radar, the transmitting system includes a plurality of laser emitters arranged in a certain pattern to form a planar laser array. The number of laser emitters needs to support the diffusion angle of the planar laser array. When the same diffusion angle is achieved, the number of laser emitters used in this kind of transmitting system is relatively large.

[0004] Therefore, there is an urgent need for a diffusion unit, a transmitting system, a laser radar and a vehicle to solve the problem of a large number of laser emitters used in the existing transmitting system. SUMMARY

[0005] The present application aims to solve the above technical problems, i.e., to solve the problem of a large number of laser emitters used in the existing transmitting system.

[0006] In a first aspect, the present application provides a diffusion unit, which includes a lens group. The lens group includes a plurality of lenses arranged in sequence. The refractive index of the lens is greater than the refractive index of the medium around the lens. The lens can refract and reflect the incident light to produce refracted light and reflected light. From the first end to the second end of the lens group, the refracted light emitted from the previous lens can enter the next lens and be refracted and reflected.

[0007] In the specific embodiment of the diffusion unit, the plurality of lenses are arranged in sequence along a circular arc.

[0008] In the specific embodiment of the diffusion unit, the incident angle of the laser and the refracted light is the Brewster angle; and / or, the laser is P-type linearly polarized light.

[0009] In the specific embodiment of the diffusion unit, the lens comprises an incident surface, and at least part of the incident surface of the lens is attached with a light semi-permeable film; and / or, the thickness of the light semi-permeable film gradually increases from the first end to the second end.

[0010] In the specific embodiment of the diffusion unit, the incident surface of the lens at the second end is attached with a total reflection film.

[0011] In the specific embodiment of the diffusion unit, the diffusion unit comprises a first lens group and a plurality of second lens groups, the first lens group and the second lens groups have the same structure, and the plurality of lenses of the first lens group are arranged one by one corresponding to the plurality of second lens groups; the light emitted from the second end of the first lens group can be incident into the first end of the second lens group.

[0012] In the second aspect, the application provides a transmitting system, which comprises the diffusion unit and a laser transmitter, and the laser emitted by the laser transmitter is directed to the lens group.

[0013] In the specific embodiment of the transmitting system, the transmitting system further comprises a rotator, and the laser transmitter and the diffusion unit are both mounted on the rotator, and the rotator can rotate.

[0014] In the third aspect, the application provides a laser radar, which comprises the transmitting system.

[0015] In the fourth aspect, the application provides a vehicle, which comprises the laser radar.

[0016] Compared with the prior art, the application has the following beneficial effects:

[0017] The diffusion unit provided by the application comprises a lens group, the lens group comprises a plurality of lenses arranged in sequence, the refractive index of the lens is greater than the refractive index of the medium around the lens, the lens can refract and reflect the incident light to generate refracted light and reflected light, and the refracted light emitted from the previous lens can be incident into the next lens and refracted and reflected from the first end to the second end of the lens group. The laser is incident from the first end, and the laser is refracted and reflected by the plurality of lenses in sequence, the reflected light generated at the plurality of lenses forms a linear array laser, thereby reducing the number of required laser transmitters, reducing the cost of the transmitting system, and making the structure of the transmitting system more simple.

[0018] Furthermore, the lens comprises an incident surface, the incident surface of the lens is attached with a light semi-permeable film, and the thickness of the light semi-permeable film gradually increases from the first end to the second end; the more the number of lenses through which the laser enters the lens group, the lower the energy of the light wave, the thicker the thickness of the light semi-permeable film corresponding to the incident light with weaker energy, and the greater the reflection coefficient of the reflected light, so that the energy of the reflected light generated by the plurality of lenses is as same as possible, thereby improving the performance of the laser radar.

[0019] Further, the incident angle of the laser and the refracted light is the Brewster angle, and the incident laser is P-type linearly polarized light; the P-type linearly polarized light is incident at the Brewster angle, and the refracted light and the reflected light generated after refraction or reflection are also P-type linearly polarized light, so that the reflection coefficient of the incident light can be reduced.

[0020] Further, the diffusion unit comprises a first lens group and a plurality of second lens groups, the first lens group and the second lens groups are the same in structure as the lens group, a plurality of lenses of the first lens group are arranged one by one corresponding to the plurality of second lens groups, the light emitted from the second end of the first lens group can be incident into the first end of the second lens group; the laser is incident from the first end of the first lens group, the reflected light generated by the reflection of the lens of the first lens group can be incident into the second lens group, and the reflected light generated at the plurality of second lens groups forms a surface array laser; the surface array laser can be formed by cooperation of one laser emitter, the first lens group and the plurality of second lens groups, so that the number of laser emitters is greatly reduced, and the structure of the emission system is simpler and the cost is lower. BRIEF DESCRIPTION OF DRAWINGS

[0021] The preferred embodiments of the present application will be described below with reference to the accompanying drawings, in which:

[0022] Figure 1 is a cross-sectional structure schematic diagram of the first lens group provided by the present application;

[0023] Figure 2 is a cross-sectional structure schematic diagram of the first lens provided by the present application;

[0024] Figure 3 is a structure schematic diagram of the diffusion unit provided by the second embodiment of the present application;

[0025] Figure 4 is Figure 3 is the A-A cross-sectional view in the

[0026] Figure 5 is a cross-sectional structure schematic diagram of the second lens provided by the second embodiment of the present application.

[0027] Explanation of reference signs:

[0028] 0, lens group; 01, lens; 011, incident surface; 012, exit surface; 02, reflected light; 03, refracted light; 1, first lens group; 11, first lens; 12, first reflected light; 13, first refracted light; 2, second lens group; 21, second lens; 211, second incident surface; 212, second exit surface; 22, second reflected light; 23, second refracted light. DETAILED DESCRIPTION

[0029] The preferred embodiments of the present application will be described below with reference to the accompanying drawings. Those skilled in the art will understand that the embodiments are only used to explain the technical principles of the present application and are not intended to limit the protection scope of the present application.

[0030] It should be noted that, in the description of the present application, the terms indicating the direction or positional relationship of "upper", "lower", "left", "right", "inner", "outer" and the like are based on the direction or positional relationship shown in the drawings, which is only for the convenience of description, and does not indicate or imply that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for the purpose of description and cannot be understood as indicating or implying relative importance.

[0031] In addition, it should also be noted that, in the description of the present application, unless otherwise explicitly specified and limited, the terms "mounting", "setting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0032] Embodiment one

[0033] To solve the problem of too many laser emitters used in the existing transmission system, the embodiment of the present application provides a vehicle. The vehicle is installed with a laser radar, which can map the objects around the vehicle to form a high-precision 3D map, and the vehicle can be automatically driven according to the map formed by the laser radar mapping. The laser radar includes a transmission system and a receiving system, the transmission system can emit a planar array laser to a specified direction, and the laser will be reflected after encountering an obstacle, and then be received by the receiving system. After receiving the reflected laser, the receiving system calculates the propagation distance between the transmission system and the target object through the flight time of the laser, and the receiving system can also present the accurate three-dimensional structure information of the target object by detecting the energy size of the reflected laser and the amplitude, frequency and phase of the wave. The transmission system at least includes a laser emitter and a diffusion unit, the laser emitted by the laser emitter is initial light, the initial light is parallel laser, and the initial light is directly or indirectly reflected into the diffusion unit after reflection, and the range of laser emission is increased after passing through the diffusion unit.

[0034] As Figure 1As shown, the diffusion unit includes a lens group 0, which comprises multiple lenses 01 arranged sequentially and mounted on a fixed plate. The lens group 0 has a first end and a second end. The multiple lenses 01 in the lens group 0 are arranged sequentially from the first end to the second end. The laser beam is incident from the first end of the lens group 0. The refractive index of the lens 01 is greater than the refractive index of the medium surrounding the lens 01, so that the light rays incident on the lens 01 can be reflected and refracted at the lens 01, thereby generating reflected light 02 and refracted light 03. From the first end to the second end of the lens group 0, the refracted light 03 emitted from the previous lens 01 can enter the next lens 01 and undergo refraction and reflection, and so on, until the laser beam passes through all the lenses 01. The laser beam passing through all the lenses 01 generates reflected light 02, and the multiple beams of reflected light 02 generated by the multiple lenses 01 combine to form a linear laser array. Therefore, a linear laser array can be formed by cooperating with a laser emitter and a diffusion unit, thereby reducing the number of laser emitters required, reducing the cost of the emission system, and simplifying the structure of the emission system.

[0035] Lens 01 is made of transparent material. Lens group 0 is generally placed in the air. Therefore, the refractive index of lens 01 only needs to be greater than 1.

[0036] Multiple lenses 01 are arranged sequentially, specifically along an arc of radius R, with the same distance and angle between adjacent lenses 01, making the reflected light 02 generated by the lenses 01 in the lens group 0 more evenly distributed. Of course, in other embodiments, the multiple lenses 01 can be arranged in other trajectories, as long as the initial light is refracted and reflected within the lens group 0 to form multiple beams of reflected light 02 and refracted light 03.

[0037] like Figure 2 As shown, lens 01 has a right-angled trapezoidal cross-section. Lens 01 includes an incident surface 011 and an exit surface 012, which are positioned opposite each other. The incident surface 011 has a right-angled side, and the exit surface 012 has a hypotenuse. The angle between the incident surface 011 and the exit surface 012 is α. For most lenses 01, incident light (initial light or refracted light 03) strikes the incident surface 011, where it is reflected and refracted for the first time. The reflected light forms reflected light 02, and the first refracted light forms refracted light that strikes the exit surface 012. A second refracting occurs at the exit surface 012, forming refracted light 03. In other embodiments, lens 01 can also have other shapes, as long as the incident surface 011 and the exit surface 012 are opposite each other and the angle between them is α.

[0038] like Figure 1 and Figure 2As shown, the incident angle of the incident light is θ, the refraction angle of the incident light is i, the incident angle of the first refracted light is ii, the exit angle of the refracted light 03 is Ω, the refractive index of the lens 01 is K, and the interval distance between the adjacent lenses 01 is D. According to the refraction law of light, Sinθ / Sin i = K = SinΩ / Sin ii = SinΩ / Sin(i-α), wherein θ-Ω>0, and θ-Ω>α is obtained from the characteristics of the sine function. Since the lenses 01 are arranged along a circular arc with a radius R, 0.5D / R = Sin0.5(θ-Ω-α) is obtained. Thus, the relationship between the angle between the incident surface 011 and the exit surface 012, the incident angle θ of the incident light, the exit angle Ω of the refracted light 03, the arrangement radius R of the lens group 0, and the interval distance D between the lenses 01 is obtained, so as to facilitate the design of the shape of the lens 01 and the arrangement of the lens group 0.

[0039] The initial light emitted by the laser emitter is incident from the incident surface 011 of the first lens 01 of the lens group 0, and the reflection and refraction occur at the incident surface 011 to generate the reflected light 02 and the refracted light 03. The refracted light 03 emitted from the first lens 01 is incident as incident light to the second lens 01, and new reflected light 02 and refracted light 03 are generated at the incident surface 011 of the second lens 01. The refracted light 03 emitted from the second lens 01 continues to be incident as incident light to the next lens 01, and so on, until the laser passes through all the lenses 01. After the laser is incident into the lens group 0, a beam of reflected light 02 is generated after passing through each lens 01, and all the reflected light 02 generated after the laser passes through the lens group 0 is combined to form a linear array laser.

[0040] When the laser is reflected and refracted each time, part of the energy is lost and absorbed, and the remaining energy is converted into reflected light energy and refracted light energy. The ratio of the lost and absorbed energy to the incident light energy is the absorption coefficient, the ratio of the reflected light energy to the incident light energy is the reflection coefficient, and the ratio of the refracted light energy to the incident light energy is the transmission coefficient. For the same lens 01, the sum of the absorption coefficient, the reflection coefficient, and the transmission coefficient is 1. The smaller the reflection coefficient, the smaller the proportion of the energy of each reflected light 02 to the total energy of the laser, and the more the maximum number of reflected lights 02 that can be set. The more the number of reflected lights 02, the more the number of light emitting points of the linear array laser, and the higher the scanning accuracy of the laser radar.

[0041] The initial light emitted by the laser emitter is P-type linearly polarized light, and the incident angle of the initial light and the refracted light 03 as incident light is the Brewster angle. The P-type linearly polarized light is incident at the Brewster angle, and after refraction, the reflected light and the refracted light generated are also P-type linearly polarized light, which can reduce the reflection coefficient of the incident light, and the reflection coefficient of the incident light can be reduced to below 1%.

[0042] At least a portion of the incident surface 011 of the lens 01 is covered with a semi-transparent film, which can filter light waves. By changing the thickness of the semi-transparent film attached to the lens 01, the reflection coefficient can be changed; the thicker the semi-transparent film, the greater the reflection coefficient.

[0043] The incident surface 011 of lens 01, located at the second end of lens group 0, is covered with a total internal reflection film. The total internal reflection film can completely reflect the incident light. The incident surfaces 011 of the other lenses 01 are covered with semi-transparent films. When the laser light reaches lens 01 at the second end of lens group 0 after multiple refractions, the energy of the incident light is already relatively weak. Total internal reflection of this incident light beam can convert it all into reflected light 02 for use, thus avoiding the waste of the energy of the incident light beam.

[0044] In the design of lidar, it is essential to maintain the same energy for each emitted laser beam, meaning the energy of each reflected light beam (O2) should be as similar as possible. To achieve this, the thickness of the semi-transparent film attached to lens 01 gradually increases from the first end to the second end of lens group 0. As the laser beam enters lens group 0 from the first to the second end, the more lenses 01 the laser passes through, the lower the energy of the light wave. Furthermore, the increasing thickness of the semi-transparent film attached to lens 01 along the laser incidence direction means that the film is thicker for weaker incident light, resulting in a higher reflection coefficient. This ensures that the energy of the reflected light (O2) is as uniform as possible, thereby improving the performance of the lidar.

[0045] Let m be the number of light-emitting points of reflected light 02, and ρ be the luminous flux of each reflected light 02. The ratio of the absorption coefficient to the transmission coefficient of lens 01 with a semi-transparent film is the same and δ. δ is determined by the material, shape, and light source of the medium used in lens 01. Since each lens 01 uses the same material, has the same shape, and uses a laser emitter as the light source, δ is the same and constant for each lens 01. The smaller the ratio δ of the absorption coefficient to the transmission coefficient of lens 01, the more light-emitting points m of reflected light 02; the smaller the luminous flux ρ of each reflected light 02, the more light-emitting points m of reflected light 02.

[0046] This embodiment illustrates the relationship between the ratio δ of the absorption coefficient to the transmission coefficient of lens 01, the luminous flux ρ of each reflected light 02, and the number of light-emitting points m of the reflected light 02 through the following three examples.

[0047] Example 1: Suppose the energy of the incident light generated by the laser emitter is 1. When δ = 0.1 and ρ = 0.02, m = 18. The specific calculation steps are shown in Table 1.

[0048] Example 2: Suppose the energy of the incident light generated by the laser emitter is 1. When δ = 0.05 and ρ = 0.02, m = 25. The specific calculation steps are shown in Table 2.

[0049] Example 3: Suppose the energy of the incident light generated by the laser emitter is 1. When δ = 0.05 and ρ = 0.01, m = 36. The specific calculation steps are shown in Table 3.

[0050] Table 1

[0051]

[0052] Table 2

[0053]

[0054]

[0055] Table 3

[0056]

[0057]

[0058] In addition, by increasing the energy of the incident light generated by the laser emitter, the number of emission points m of the reflected light O2 can also be increased.

[0059] In summary, the specific working principle of the diffusion unit provided in this embodiment is as follows:

[0060] The initial light generated by the laser emitter is incident on the incident surface 011 of lens 01 at the first end of lens group 0. Reflection and refraction occur at the incident surface 011, producing reflected light 02 and refracted light 03. The refracted light 03 from the first lens 01 is incident on the second lens 01, generating new reflected light 02 and refracted light 03 at the incident surface 011 of the second lens 01. The refracted light 03 from the second lens 01 continues to be incident on the next lens 01, and so on, until the laser has passed through all lenses 01. The incident light undergoes total internal reflection at the last lens 01. After the laser enters lens group 0, a beam of reflected light 02 is generated after each lens 01. All the reflected light 02 generated after the laser passes through lens group 0 combines to form a linear laser array.

[0061] The emission system comprises multiple laser emitters and multiple diffusion units. Each laser emitter corresponds to one diffusion unit. The laser emitted by each emitter is refracted and reflected in its corresponding diffusion unit to form a linear laser array. Multiple laser emitters and their corresponding diffusion units can form multiple linear laser arrays, and multiple linear laser arrays can be combined to form an area laser array. In this emission system, each group of linear laser arrays forming an area laser array uses only one laser emitter, which significantly reduces the number of laser emitters required. The lidar using this emission system is a solid-state lidar, which is structurally stable and highly reliable. Furthermore, this emission system can relatively easily generate array lasers with a large number of light spots, enabling the construction of area laser arrays with more scanning points at a lower cost, thereby improving the scanning accuracy of the lidar.

[0062] It is worth noting that the diffusion unit described in this invention can be applied not only to solid-state lidar but also to mechanical lidar in other embodiments. Specifically, the emission system includes a laser emitter, a diffusion unit, and a rotator. The laser emitted by the laser emitter is refracted and reflected by the corresponding diffusion unit to form a linear laser array. Both the laser emitter and the diffusion unit are mounted on the rotator, and the arrangement direction of the linear laser array is parallel to the rotation axis of the rotator. When the rotator drives the laser emitter and the diffusion unit to rotate, it can convert the linear laser array into a planar laser array. The lidar using this emission system is a mechanical lidar, which can generate a linear laser array with fewer laser emitters and a larger number of emission points. The number of scanning points of the lidar is the number of scanning points of the planar laser array in space, which is related to the scanning frequency and the number of emission points. The higher the scanning frequency and the more emission points, the more scanning points. Under the premise of the same scanning frequency, compared with traditional mechanical lidar, if the rotation speed of the rotator is the same, since the number of light emission points of the linear laser array formed by the laser passing through the diffusion unit is larger, the lidar generated after the rotator rotates can obtain more scanning points and achieve higher scanning accuracy. In addition, if the lidar has the same number of scanning points, since the number of light emission points of the linear laser array formed by the laser passing through the diffusion unit is larger, the rotator in this embodiment can rotate at a lower speed, thereby increasing the lifespan of the rotator.

[0063] Example 2

[0064] like Figure 3 As shown, the diffusion unit provided in this embodiment includes a first lens group 1 and a plurality of second lens groups 2. The first lens group 1 and the second lens group 2 have the same structure as the lens group 0 described in Embodiment 1. Both the first lens group 1 and the second lens group 2 are mounted on a fixed plate.

[0065] The lenses in the first lens group 1 are first lenses 11, and the lenses in the second lens group 2 are second lenses 21. Each first lens 11 in the first lens group 1 corresponds one-to-one with a second lens group 2, meaning each second lens group 2 corresponds to one first lens 11. Laser light enters from the first end of the first lens group 1, is reflected and refracted at the first lens 11, generating first reflected light 12 and first refracted light 13. Each first reflected light 12 is reflected by each first lens 11. Each beam of first reflected light 12 is directed to the first end of a second lens group 2, and is refracted and reflected sequentially by the multiple second lenses 21 of the second lens group 2, generating multiple beams of second reflected light 22 and multiple beams of second refracted light 23. The second reflected light 22 generated at a single second lens group 2 forms a linear laser array, and the multiple linear laser arrays generated by multiple second lens groups 2 combine to form a planar laser array. This embodiment can form a planar laser array by using a single laser emitter, a first lens group 1, and multiple second lens groups 2, greatly reducing the number of laser emitters and thus simplifying the structure of the emission system and lowering its cost.

[0066] The first lens group 1 has the same structure and settings as the lens group 0 described in Embodiment 1. The second lens group 2 has the same structure as the lens group 0 described in Embodiment 1, but the specific settings are slightly different.

[0067] In each second lens group 2, multiple second lenses 21 are arranged sequentially along an arc of radius W, with the same distance and angle between adjacent second lenses 21, making the distribution of the second reflected light 22 generated by the second lenses 21 in each second lens group 2 more uniform. Of course, in other embodiments, the multiple second lenses 21 in each second lens group 2 can be arranged in other trajectories, as long as the laser is refracted and reflected within the second lens group 2 to form multiple beams of second reflected light 22 and second refracted light 23.

[0068] The first lens group 1 has the same arrangement radius R as the second lens group 2, and the first lens 11 and the second lens 21 are arranged on a spherical surface. Of course, in other embodiments, the arrangement radius R of the first lens group 1 and the arrangement radius W of the second lens group 2 may be different.

[0069] The second lens 21 has the same structure and is made of the same material as the first lens 11, to avoid confusion between the first lens 11 and the second lens 21 during installation. Since the first lens 11 and the second lens 21 are made of the same material, they have the same refractive index, K.

[0070] like Figure 5As shown, the second lens 21 includes a second incident surface 211 and a second exit surface 212, which are arranged opposite to each other. The included angle between the second incident surface 211 and the second exit surface 212 is also α. Each beam of first reflected light 12 is directed toward the second lens 21 at the first end of the corresponding second lens group 2. The second refracted light 23 emitted from the first second lens 21 is directed as incident light toward the second second lens 21 in the group, and a new second reflected light 22 and second refracted light 23 are generated in the second second lens 21. The second refracted light 23 emitted from the second second lens 21 is directed as incident light toward the next second lens 21 in the group, and so on, until the laser passes through all the second lenses 21. After the laser enters a second lens group 2, a beam of second reflected light 22 is generated each time it passes through a second lens 21. The second reflected light 22 generated after the laser passes through a second lens group 2 forms a linear array laser, and the linear array lasers generated by multiple second lens groups 2 are combined to form a planar array laser.

[0071] The incident angle of the first reflected light 12 is Brewster's angle. After the incident light is incident at Brewster's angle, the resulting reflected and refracted light are both P-type linearly polarized light. The initial light emitted by the laser emitter is P-type linearly polarized light, therefore the first refracted light 13 incident on the second lens group 2 is also P-type linearly polarized light. When the first refracted light 13 and the second refracted light 23 are incident at Brewster's angle, the second reflected light 22 and the second refracted light 23 generated by reflection and refraction through each second lens 21 in the second lens group 2 are also P-type linearly polarized light. This reduces the reflection coefficient of the incident light to below 1%.

[0072] Combination Figure 4 and Figure 5 As shown, the first lens 11 and the second lens 21 have the same refractive index K and the same structure. The laser beam and the first refracted light 13 are incident on the first lens 11 at Brewster's angle. The first reflected light 12 and the second refracted light 23 are incident on the second lens 21 at Brewster's angle. Therefore, the incident angles θ of the first lens 11 and the second lens 21 are the same, the angles of refraction i of the incident light are the same, the angles of refraction ii of the first refracted light are the same, and the exit angles Ω of the first refracted light 13 and the second refracted light 23 are also the same. Let the distance between adjacent second lenses 21 in each group of second lens groups 2 be S. Therefore, 0.5S / W = Sin0.5(θ-Ω-α). From this, we can understand the relationship between the angle α between the second incident surface 211 and the second exit surface 212, the incident angle θ of the incident light, the exit angle Ω of the second refracted light 23, the arrangement radius W of the second lens group 2, and the distance S between the second lenses 21, to facilitate the arrangement of the second lens group 2.

[0073] At least a portion of the second incident surface 211 of the second lens 21 is covered with a semi-transparent film, which filters light waves. By changing the thickness of the semi-transparent film attached to the second lens 21, the reflection coefficient can be changed; the thicker the semi-transparent film, the greater the reflection coefficient. From the first end to the second end of the second lens group 2, the thickness of the semi-transparent film attached to the second lens 21 gradually increases. After the first reflected light 12 is incident on the corresponding first end of the second lens group 2, the more second lenses 21 it passes through, the lower the energy of the light wave. Since the thickness of the semi-transparent film attached to the second lens 21 gradually increases from the first end to the second end of the second lens group 2, the weaker the incident light, the thicker the semi-transparent film, resulting in a greater reflection coefficient. This ensures that the energy of the second reflected light 22 is as uniform as possible, thereby improving the performance of the lidar.

[0074] A total internal reflection film is attached to the second incident surface 211 of the second lens 21 located at the second end of each second lens group 2. The total internal reflection film can reflect the incident light completely. The second incident surface 211 of the other second lenses 21 in this second lens group 2 is attached to a semi-transparent film. When the first reflected light 12 reaches the second lens 21 located at the second end of the second lens group 2 after multiple refractions, the energy of the incident light is already relatively weak. Total internal reflection of this beam of incident light can convert all of the incident light into the second reflected light 22 for use, so as not to waste the energy of the incident light.

[0075] In summary, the specific working principle of the diffusion unit provided in this embodiment is as follows:

[0076] The initial light generated by the laser emitter is directed towards the first lens 11 located at the first end of the first lens group 1. The first refracted light 13 emitted from the first first lens 11 is incident as the second first lens 11, generating a new first reflected light 12 and a new first refracted light 13 at the second first lens 11. The first refracted light 13 emitted from the second first lens 11 continues as the incident light to the next first lens 11, and so on, until the laser has passed through all the first lenses 11. The incident light undergoes total internal reflection at the last first lens 11. After the laser enters the first lens group 1, a beam of first reflected light 12 is generated after each first lens 11.

[0077] Each beam of first reflected light 12 is directed toward the second lens 21 at the first end of the corresponding second lens group 2. The second refracted light 23 emitted from the first second lens 21 is incident on the second second lens 21 in the same group, and generates new second reflected light 22 and second refracted light 23 after passing through the second second lens 21. The second refracted light 23 emitted from the second second lens 21 is incident on the next second lens 21 in the same group, and so on, until the laser has passed through all the second lenses 21. After the laser enters a second lens group 2, it generates a beam of second reflected light 22 after passing through each second lens 21. The second reflected light 22 generated after the laser passes through a second lens group 2 forms a linear laser array, and the linear laser arrays generated by multiple second lens groups 2 are combined to form a planar laser array.

[0078] The emission system, including a laser emitter and a diffusion unit, is directly applied to lidar. This type of lidar is a solid-state lidar, which uses a single laser emitter. The single laser beam emitted by the laser emitter is diffused by the diffusion unit to directly form a planar laser array. This significantly reduces the number of laser emitters required, enabling the formation of a planar laser array at a lower cost. Furthermore, as a solid-state lidar, this type of lidar does not include an actuation unit, resulting in a stable structure and high reliability.

[0079] It is worth noting that the diffusion unit described in this invention can be applied not only to solid-state lidar but also to mechanical lidar in other embodiments. Specifically, the emission system includes a laser emitter, a diffusion unit, and a rotator. The laser emitted by the laser emitter is refracted and reflected by the diffusion unit to form a linear laser array. The rotator can rotate. Both the laser emitter and the diffusion unit are mounted on the rotator. When the rotator drives the laser emitter and the diffusion unit to rotate, it can expand the scanning range of the area laser array emitted by the diffusion unit. The diffusion unit can diffuse a single laser beam into an area laser array with multiple emission points. Under the premise of the same scanning frequency, compared with traditional mechanical lidar, if the rotation speed of the rotator is the same, since the number of emission points of the area laser array formed by the laser passing through the diffusion unit is larger, the lidar can obtain more scanning points and a larger scanning range after the rotator rotates, resulting in higher scanning accuracy. In addition, if the lidar has the same number of scanning points, since the number of emission points of the area laser array formed by the laser passing through the diffusion unit is larger, the rotator in this embodiment can rotate at a lower speed, thereby increasing the lifespan of the rotator.

[0080] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A diffusion unit, characterized by, The lens group (0) comprises a plurality of lenses (01) arranged in sequence, the refractive index of the lens (01) being greater than the refractive index of the medium around the lens (01); The lens (01) can refract and reflect the incident light, and generate refracted light (03) and reflected light (02), from the first end to the second end of the lens group (0), the refracted light (03) emitted from the last lens (01) can enter the next lens (01) and be refracted and reflected; The diffusion unit comprises a first lens group (1) and a plurality of second lens groups (2), the first lens group (1) and the second lens group (2) are the same structure as the lens group (0), the plurality of lenses (01) of the first lens group (1) are one-to-one corresponding to the plurality of second lens groups (2). The light emitted from the second end of the first lens group (1) can enter the first end of the second lens group (2).

2. Diffusion unit according to claim 1, characterized in that The plurality of lenses (01) are arranged in sequence along an arc.

3. The diffusion unit of claim 1, wherein The incident angle of the laser and the refracted light (03) is Brewster's angle; and / or The laser is P-type linearly polarized light.

4. The diffusion unit of claim 1, wherein The lens (01) comprises an incident surface (011), and the incident surface (011) of at least part of the lens (01) is attached with a light semi-permeable film; and / or From the first end to the second end, the thickness of the light semi-permeable film gradually increases.

5. Diffusion unit according to claim 4, characterized in that The incident surface (011) of the lens (01) at the second end is attached with a total reflection film.

6. A transmitting system characterized by, Comprise: The diffusion unit according to any one of claims 1 to 5; A laser emitter, which emits laser towards the diffusion unit.

7. The launch system of claim 6, wherein, The emission system further comprises a rotator, the laser emitter and the diffusion unit are both mounted on the rotator, and the rotator can drive the laser emitter and the diffusion unit to rotate.

8. A lidar, comprising: Comprise the emission system according to claim 6 or 7.

9. A vehicle characterized by comprising: Comprise the laser radar according to claim 8.

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