A MEMS laser radar light collimation ring scanning device and method

Abstract

The application discloses a MEMS laser radar light collimation ring scanning device, which comprises a first collimation unit, a second collimation unit, a micro-electro-mechanical system and a weak convergence unit. The first collimation unit comprises symmetrically arranged first and second taper surfaces, the first and second taper surfaces are provided with a light transmission hole near a geometric center, and the first and second taper surfaces are provided with an outer side surface away from the light transmission hole. The second collimation unit comprises a light converging surface and a collimation surface matched with the outer side surface. The angle relationship between the first and second taper surfaces and the second collimation unit are utilized to realize the convergence of laser in the vertical direction and the horizontal direction, so that the laser is kept collimated and horizontally emitted, and the radar ring scanning is realized by using less mechanical structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of radar scanning, in particular to a MEMS laser radar light collimation ring scanning device and method. BACKGROUND

[0002] In recent years, large field of view laser radar has a very large effect on automatic driving, and the commonly used method for realizing large field of view laser radar includes splicing through multiple small field of view laser radars, such as splicing a 360-degree radar through three 120-degree field of view laser radars. This method has a complex structure, and each small field of view laser radar contains many optical elements, and the structure is very complex.

[0003] Another type is to realize large field of view ring scanning through a rotating mirror. This method is a typical mechanical scanning radar, the mirror is large in size, the scanning speed is slow, and has an impact on the service life. Using a micro-electro-mechanical system (hereinafter referred to as MEMS) as a scanning element for ring scanning can overcome the shortcomings of the above two radars.

[0004] Compared with the prior art

Patent: 202110333307.3

[0005] In order to solve the shortcomings of the existing radar, the present application uses a MEMS laser radar light collimation ring scanning device and method, especially a first collimation unit and a second collimation unit. The method does not need to rotate the optical elements, has a fast scanning speed, a high light efficiency, and a small number of optical elements used, and effectively solves the shortcomings of the existing large field of view laser radar. SUMMARY

[0006] This part aims to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part and the abstract and title of the specification to avoid obscuring the purpose of this part, the abstract and the title. Such simplifications or omissions cannot be used to limit the scope of the present application.

[0007] In view of the above-mentioned problems of the existing MEMS laser radar, such as the need for a compensation prism and the need for coating to realize reflection, the present application is proposed.

[0008] Therefore, the purpose of the present application is to provide a MEMS laser radar light collimation ring scanning device and method, which aims to realize radar ring scanning with less mechanical structure.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a MEMS lidar optical collimation and scanning device, the device comprising a first collimation unit, which includes a first conical surface and a second conical surface symmetrically arranged, the first and second conical surfaces having a light-transmitting hole near their geometric centers, and the first and second conical surfaces having an outer surface on the side away from the light-transmitting hole; a second collimation unit, including a light-converging surface and a calibration surface cooperating with the outer surface; a microelectromechanical system (MEMS) disposed on one side of the light-transmitting hole, the straight section between the MEMS and the light-transmitting hole being a first section; and a weak convergence unit disposed on the side of the light-transmitting hole away from the MEMS.

[0010] As a preferred embodiment of the MEMS lidar optical collimation ring scanning device of the present invention, wherein: the plane perpendicular to the first section is a horizontal plane, the first conical surface forms a first angle with the horizontal plane, the second conical surface forms a second angle with the horizontal plane, and the microelectromechanical system forms a third angle with the horizontal plane.

[0011] In a preferred embodiment of the MEMS lidar optical collimation ring scanning device of the present invention, the first included angle and the third included angle satisfy the following relationship:

[0012]

[0013] Where n is the refractive index of the material used in the optical element to which the first conical surface belongs, and the second included angle and the third included angle satisfy the following relationship:

[0014]

[0015] To further control the laser beam emission mode to be horizontal, it is necessary to control the first included angle A1 and the third included angle to satisfy the following relationship:

[0016] .

[0017] As a preferred embodiment of the MEMS lidar optical collimation ring scanning device of the present invention, a laser is further provided on the first section to emit laser light to the first collimation unit, and the laser travel path passes through the light-transmitting hole along the weak convergence unit to reach the microelectromechanical system.

[0018] As a preferred embodiment of the MEMS lidar optical collimation ring scanning device of the present invention, a deep aperture stop is further provided in the laser travel direction, and the deep aperture stop is disposed in conjunction with the weak convergence unit on the side away from the light-transmitting hole.

[0019] As a preferred embodiment of the MEMS lidar optical collimation and scanning device of the present invention, wherein: the diameter of the light-transmitting aperture is smaller than the diagonal length of the microelectromechanical system, and the beam aperture of the laser is smaller than the diagonal length of the microelectromechanical system; the laser is disposed outside the front focal point of the weak convergence unit, and its vertical distance is L, 1mm≤L≤5mm.

[0020] Another technical problem to be solved by the present invention is to provide a method for collimating and scanning a MEMS lidar, the purpose of which is to generate collimated laser light by operating the above-mentioned device.

[0021] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a MEMS lidar optical collimation ring scanning method, which employs the above-mentioned optical collimation ring scanning device and further includes the following steps:

[0022] Determine appropriate experimental parameters, including selecting the materials of the optical elements to which the first and second conical surfaces belong;

[0023] Calculate the size of the first included angle, the second included angle, and the third included angle based on the selected material, and then calculate the curvature of the first cone surface and the second cone surface;

[0024] Based on the horizontal divergence of the laser as it passes through the light-transmitting hole and reaches the microelectromechanical system, the aperture size of the deep aperture stop is set, and the deep aperture stop intercepts the large-angle light.

[0025] Based on the horizontal divergence of the laser light when it is reflected by the microelectromechanical system and reaches the first conical surface, the lens curvature of the weak converging unit is set to achieve the convergence of the horizontally diverging light of the laser light, thereby compensating for the horizontal divergence of the laser light after it reaches the first conical surface.

[0026] Based on the vertical divergence of the laser beam when it passes through the first collimating unit and reaches the second collimating unit, the lens curvature of the light converging surface is set to achieve the convergence of the vertically diverging light of the laser beam.

[0027] Adjust the calibration surface to provide the laser's arrival position after one interception and two convergences to achieve the best surround scanning effect.

[0028] As a preferred embodiment of the MEMS lidar optical collimation ring scanning method of the present invention, the relationship between the third included angle and the second included angle is adjusted so that the laser can be transmitted when it reaches the second conical surface.

[0029] As a preferred embodiment of the MEMS lidar optical collimation ring scanning method of the present invention, the relationship between the third included angle and the first included angle is adjusted so that the laser can undergo total reflection when it reaches the first conical surface.

[0030] As a preferred embodiment of the MEMS lidar optical collimation ring scanning method of the present invention, in the adjustment process, the third angle between the microelectromechanical system and the horizontal plane is first coarsely adjusted so that the laser reaches the second collimation unit, and the vertical height of the second collimation unit is determined to provide a carrier for the laser to travel.

[0031] By finely adjusting the first and second included angles, the direction of the laser after passing through the first collimation unit is made parallel to the horizontal direction, and the second collimation unit is used to determine that the laser is in a collimated state.

[0032] The beneficial effects of this invention are:

[0033] This invention utilizes the angular relationship between the first and second conical surfaces and sets up a second collimation unit to achieve laser convergence in the vertical and horizontal directions, keeping the laser collimated and emitted horizontally, thus achieving radar ring scanning with fewer mechanical structures. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0035] Figure 1 This is a schematic diagram of the angular relationship of the MEMS lidar optical collimation ring scanning device of the present invention.

[0036] Figure 2 This is a partial structural schematic diagram of the MEMS lidar optical collimation ring scanning device of the present invention.

[0037] Figure 3 This is a schematic diagram of the first collimation unit structure of the MEMS lidar optical collimation ring scanning device of the present invention.

[0038] Figure 4 This is a schematic diagram of the deep aperture and weak convergence unit structure of the MEMS lidar optical collimation ring scanning device of the present invention.

[0039] Figure 5 This is a schematic diagram of the overall structure of the MEMS lidar optical collimation ring scanning device of the present invention.

[0040] Figure 6This is a schematic diagram of the laser's movement within the MEMS lidar optical collimation and scanning device of the present invention.

[0041] Figure 7 This is a schematic diagram of the second unit of the MEMS lidar optical collimation and circular scanning device of the present invention.

[0042] Figure 8 The image shows the laser path and collimation effect from the front view of the MEMS lidar optical collimation ring scanning device of the present invention.

[0043] Figure 9 The image shows the laser path and collimation effect from a top view of the MEMS lidar optical collimation ring scanning device of the present invention.

[0044] Figure 10 This is a simplified schematic diagram of the MEMS lidar optical collimation ring scanning device of the present invention. Detailed Implementation

[0045] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0046] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0047] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0048] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0049] Example 1

[0050] Reference Figures 1-5The first embodiment of the present invention provides a MEMS lidar optical collimation ring scanning device. This device includes a first collimation unit 100, which includes a first conical surface 101 and a second conical surface 102 symmetrically arranged. A light-transmitting hole 103 is opened on the first conical surface 101 and the second conical surface 102 near the geometric center. An outer surface 104 is provided on the side of the first conical surface 101 and the second conical surface 102 away from the light-transmitting hole 103.

[0051] The second collimation unit 200 includes a light-converging surface 201 and a calibration surface 202 that cooperate with the outer surface 104; a microelectromechanical system 300 that is disposed on one side of the light-transmitting hole 103, the straight section between the microelectromechanical system 300 and the light-transmitting hole 103 being the first section Q; and a weak convergence unit 400 that is disposed on the side of the light-transmitting hole 103 away from the microelectromechanical system 300, the first section Q also being provided with a laser 500 that emits laser X to the first collimation unit 100.

[0052] The first unit 100, the second unit 200, and the weakly converging unit 400 are all rotationally symmetric structures, which can be derived from... Figure 1 The cross-sectional profile is obtained by rotating it about the central axis as follows Figure 5 The 3D structure diagram shown.

[0053] The microelectromechanical system 300 can rotate around the center line of the first segment Q under the guidance of a debugged program. The rotation of the microelectromechanical system 300, in conjunction with the first unit 100, enables the laser beam to scan in the horizontal direction.

[0054] The microelectromechanical system 300 can rotate around the straight line where the first segment Q is located in the debugged program. The first collimation unit 100 provides reflection for the laser X. With the rotation of the microelectromechanical system 300 and the cooperation of the first collimation unit 100, the laser X is scanned by the microelectromechanical system 300 after passing through the light-transmitting hole 103. The scanned beam is emitted by the second collimation unit 200, hits the surrounding objects, and is reflected to the detector to form a point cloud, so as to realize the lidar detection.

[0055] During use, a second collimation unit 200 is also provided to cooperate with the first collimation unit 100. The second collimation unit 200 is arranged around the outside of the first collimation unit 100. No matter what angle the microelectromechanical system 300 deflects, the second collimation unit 200 can further focus the laser X reflected by the microelectromechanical system 300 to achieve a better beam collimation effect. At this time, the ray detection distance is longer and the radar resolution is higher.

[0056] In this embodiment, to achieve more accurate detection and a longer device lifespan with less material, the following restrictions are imposed on the angular relationship between the first conical surface 101, the second conical surface 102, and the microelectromechanical system 300:

[0057] The plane perpendicular to the first section Q is the horizontal plane M. The first conical surface 101 forms a first angle A1 with the horizontal plane M, the second conical surface 102 forms a second angle A2 with the horizontal plane M, and the microelectromechanical system 300 forms a third angle A3 with the horizontal plane M.

[0058] The first included angle A1 and the third included angle A3 satisfy the following relationship:

[0059]

[0060] Where n is the refractive index of the material used in the optical element of the first conical surface 101, and the second included angle A2 and the third included angle A3 satisfy the following relationship:

[0061]

[0062] The laser 500 is positioned outside the front focal point of the weak focusing unit 400, with a vertical distance of L, where 1mm ≤ L ≤ 5mm. (Due to the small size, it is not shown in the illustration. The position of the laser 500 is set based on the front focal point of the actual weak focusing unit 400.)

[0063] By applying the above constraints, the following laser X-ray travel path can be achieved:

[0064] As laser X propagates along the path to the microelectromechanical system 300, it undergoes its first convergence due to the influence of the weak convergence unit 400. After reaching the reflective surface of the microelectromechanical system 300, the laser X reaches the side of the second conical surface 102 closest to the microelectromechanical system 300, determined by the rotation direction of the microelectromechanical system 300 at a certain moment.

[0065] At this point, the second included angle A2 and the third included angle A3 satisfy the following relationship:

[0066]

[0067] When laser X reaches the second conical surface 102, laser X is perpendicular to the second conical surface 102. Laser X is transmitted into the first collimating unit 100, and the optical path direction hardly changes. The transmittance of the incident beam is highest in this direction. The laser beam passes through the second conical surface 102 and is incident on the first conical surface 101. At this time, because (1) the refractive index of the first collimating unit 100 is greater than that of the outside; (2) the first included angle A1 and the third included angle A3 satisfy the following relationship:

[0068]

[0069] The incident angle of the laser beam when it reaches the first conical surface 101 satisfies the condition that the first conical surface 101 causes total internal reflection of the laser beam. To further control the laser beam exit mode to be horizontal, the first included angle A1 and the third included angle A3 need to satisfy the following relationship:

[0070] .

[0071] In this embodiment, by reasonably controlling the aforementioned angles, laser X enters the second conical surface 102, where the beam is almost perpendicular to it, resulting in the highest beam transmittance. Laser X then strikes the first conical surface 101, where total internal reflection occurs, resulting in the highest beam reflectivity. This high reflectivity does not require a high-reflectivity optical film, and laser X exits horizontally. Based on the same MEMS laser ring scanning principle, this device avoids light spillage and achieves the laser X ring scanning effect with fewer mechanical structures.

[0072] Example 2

[0073] Reference Figures 5-8 This is the second embodiment of the present invention. This embodiment aims to further explain the collimation effect of the device. In order to achieve long-distance detection, lidar requires that the final output laser beam has very good collimation. However, lasers, especially vertical cavity surface lasers (VCSELs) commonly used in lidar, have relatively large divergence angles. Therefore, it is necessary to collimate the laser output. In this invention, a first unit deep aperture stop 105 and a weak focusing unit 400 are used to reduce the laser divergence angle.

[0074] The laser beam is not fully collimated here, but rather a small convergence angle is maintained. When the laser beam passes through the second conical surface 102 and the first conical surface 101, due to the curvature of the conical surfaces in the horizontal direction, the horizontal beam will have a certain divergence angle when the fully collimated laser beam passes through the conical surfaces. Therefore, a weak convergence unit is needed to converge the laser beam before it reaches the conical surface.

[0075] like Figure 6 As shown, the left side is a 3D view of the laser X traveling inside the device, and the right side is a front view of the process. The 3D view shows that if a fully collimated beam passes through the second conical surface 102 and is then reflected by the first conical surface 101, the beam will diverge significantly in the horizontal direction, while maintaining collimation in the vertical direction. To solve this problem, a weak converging element is used to compensate for the horizontal divergence caused by the first conical surface 101.

[0076] Thus, after compensation by the weak converging unit 400, the beam becomes collimated in the horizontal direction after reflection from the first conical surface 101. Figure 6As can be seen from the front view on the right, the fully collimated beam does not diverge or converge in the vertical direction after being reflected by the first conical surface 101. This indicates that the first conical surface 101 only affects the divergence or convergence of the beam in the horizontal direction, but does not affect the divergence or convergence in the vertical direction.

[0077] After introducing the weak converging unit, the beam begins to converge after passing through it, eventually converging into a very small spot. As it continues to propagate, the beam begins to diverge. The first conical surface 101 only affects the horizontal divergence or convergence of the beam, not its vertical divergence or convergence. Thus, the beam has already traveled a relatively long optical path from the weak converging unit 400 to the first conical surface 101, resulting in some vertical divergence.

[0078] To address the unresolved issue of vertical laser beam divergence, a second unit 200 is arranged around the first unit 100. This unit includes a beam-converging surface 201 and a calibration surface 202. The beam-converging surface 201 has curvature in the vertical direction, enabling the laser beam to converge vertically. The laser beam passes through the weak-converging unit 400, the second conical surface 102, and the first conical surface 101, converging vertically before diverging. The beam-converging surface 201 compensates for the vertical divergence, thus achieving vertical laser collimation. The calibration surface 202 guides the laser beam outwards.

[0079] Figure 7 In the diagram, the top image is the front view of the second unit 200, and the bottom image is the top view of the second unit 200. From the top view, it can be seen that the horizontal radii of curvature of the convergence surface 201 and the calibration surface 202 of the second unit 200 are Rconvergence and Rcalibration, respectively. h1 and R h2 The thickness between the two surfaces is very thin, so R h1 R h2 It is very small. When viewed horizontally, the optical power is almost zero. After passing through these two surfaces, the convergence and divergence of light rays in the horizontal direction remain basically unchanged.

[0080] As can be seen from the front view, the vertical radii of curvature of the convergence surface 201 and the calibration surface 202 of the second unit 200 are R and R, respectively. v1 and R v2 , where R v2 The radius is infinite, meaning the curvature of surface 202 in the vertical direction is zero. The converging surface 201 and the outer surface 202 act as a ring-shaped convex lens in the vertical direction, converging or diverging light. In short, the second unit only changes the convergence or divergence of the light beam in the vertical direction, having no effect on the convergence or divergence of the light beam in the horizontal direction.

[0081] The laser beam exits from the outer surface of the first unit 104, maintaining excellent collimation in the horizontal direction. However, in the vertical direction, due to the influence of the weak focusing unit 400, the laser beam diverges after traveling a long optical path. Therefore, the second unit 200 only provides vertical focusing for the laser beam to compensate for the divergence caused by the weak focusing unit 400 after traveling a long optical path, thus ensuring collimation in the vertical direction as well. Finally, after exiting from the surface of the second unit 202, the laser beam exhibits excellent collimation in both directions.

[0082] To achieve better collimation of the laser beam, a deep aperture stop 105 is provided on the side of the weak convergence unit 400 opposite to the light-transmitting aperture 103, so as to directly absorb the large-angle laser beam emitted by the laser 500. To make the device more reasonable, the diameter of the light-transmitting aperture 103 is smaller than the diagonal length of the microelectromechanical system 300 in the laser beam propagation path, and the beam aperture of the laser beam is smaller than the diagonal length of the microelectromechanical system 300.

[0083] In this embodiment, the weak converging system can be a spherical lens, an aspherical lens, or a group of spherical lenses (2-4 lenses), a group of aspherical lenses (2-4 lenses), or a group of mixed spherical and aspherical lenses (2-4 lenses). The inner and outer surfaces of the deep aperture are coated with black to absorb large-angle light emitted from the laser.

[0084] The remaining structure is the same as that in Example 1.

[0085] Example 3

[0086] Combined with appendix Figures 1-10 The third embodiment of the present invention proposes a MEMS lidar optical collimation ring scanning method. This imaging method uses the above-mentioned optical collimation ring scanning device and further includes the following steps:

[0087] Determine appropriate experimental parameters, including selecting the material of the conical lens formed by the first conical surface 101, the second conical surface 102, 103 and the outer surface 104 of the first unit. Commonly used materials are glass or plastic. Determine the edge thickness and maximum aperture of the conical lens.

[0088] Select the angle A3 between the microelectromechanical system and the horizontal plane. This angle is usually 5-8 degrees. This will determine the range of the first included angle A1.

[0089]

[0090] Then, based on the following formula for controlling the horizontal emission of the laser beam, determine the first included angle A1.

[0091]

[0092] The range of values ​​for the second included angle A2 is calculated using the following formula.

[0093] A2=A3

[0094] Based on the above conditions, the conical lens formed by the first conical surface 101, the second conical surface 102, 103 and the outer surface 104 of the first unit can be determined.

[0095] Based on the horizontal divergence of laser X when it passes through the light-transmitting aperture 103 and reaches the microelectromechanical system 300, the aperture size of the deep aperture stop 105 is set, and the large-angle aperture stop is intercepted by the deep aperture stop 105.

[0096] Based on the horizontal divergence of laser X when it is reflected by the microelectromechanical system 300 to the first conical surface 101, the lens curvature of the weak converging unit 400 is optimized to achieve the convergence of the horizontally diverging light of laser X, thereby compensating for the horizontal divergence of laser X when it reaches the first conical surface 101.

[0097] Fine-tune the curvature of the first conical surface 101 and the second conical surface 102 to achieve horizontal collimation of laser X. Adjust the relationship between the third included angle A3 and the second included angle A2 so that laser X can be transmitted when it reaches the second conical surface 102.

[0098] Adjust the relationship between the third included angle A3 and the first included angle A1 so that the laser X can undergo total reflection when it reaches the first conical surface 101.

[0099] Based on the vertical divergence of laser X when it passes through the first collimating unit 100 and reaches the second collimating unit 200, the lens curvature of the light converging surface 201 is set to achieve the convergence of the diverging light of laser X in the vertical direction.

[0100] Adjust the calibration surface 202 to provide the arrival position of the laser X after one interception and two convergences to achieve the best surround scanning effect.

[0101] During the adjustment process, the third angle A3 between the microelectromechanical system 300 and the horizontal plane is first coarsely adjusted so that the laser X reaches the second collimation unit 200, and the vertical height of the second collimation unit 200 is determined to provide a carrier for the laser X to travel.

[0102] By finely adjusting the first included angle A1 and the second included angle A2, the direction of laser X after passing through the first collimation unit 100 is made parallel to the horizontal direction, and the second collimation unit 200 is used to determine that laser X is in a collimated state.

[0103] Referring to Figures 1-10, by focusing on the travel path of laser X, we can understand the structure of the device and the beneficial effects achieved. For ease of description, we define the direction of the first section Q as the vertical direction, with the position of laser 500 as above and the position of microelectromechanical system 300 as below. Laser X is emitted downward from the downward-facing laser 500 and first reaches the deep aperture stop 105. The deep aperture stop 105 intercepts the large-angle stop. At this time, laser X reaches the weak focusing unit 400, which focuses laser X to keep it collimated.

[0104] The microelectromechanical system 300 is controlled by software and rotates around the straight line containing the first segment Q. At a certain moment, the laser X reaches the microelectromechanical system 300 and is reflected, reaching the lower surface of the second conical surface 102. Since the laser X is perpendicular to the second conical surface 102, the laser X is transmitted into the first collimation unit 100 and reaches the first conical surface 101 at the original incident angle. The incident angle when the laser X reaches the first conical surface 101 is sufficient to satisfy the total internal reflection of the laser X by the first conical surface 101, and the laser X is emitted horizontally.

[0105] At this time, laser X reaches the second collimation unit 200, and the light converging surface 201 converges laser X again to keep laser X collimated. At this time, laser X passes through the calibration surface 202 and is collimated outward. During the dynamic process, the microelectromechanical system 300 rotates about the straight line where the first segment Q is located. The position of laser X changes with the rotation of the microelectromechanical system 300. The beam emitted from the second collimation unit 200 hits the surrounding objects and is reflected to the detector to form a point cloud, so as to realize the lidar detection.

[0106] During this process, in response to the horizontal divergence of laser X upon reaching the first conical surface 101, the weak converging unit 400 converges laser X in advance to achieve divergence compensation when laser X reaches the first conical surface 101, thereby achieving horizontal collimation of laser X.

[0107] In this scenario, if a fully collimated beam passes through the second conical surface 102 and is then reflected by the first conical surface 101, the beam will exhibit significant horizontal divergence while maintaining collimation in the vertical direction. To address this issue, a weak converging element 400 is used to compensate for the horizontal divergence caused by the first conical surface 101. After compensation by the weak converging element 400, the beam becomes collimated in the horizontal direction after reflection from the first conical surface 101.

[0108] In this case, a fully collimated beam, after reflection by the first conical surface 101, exhibits no divergence or convergence in the vertical direction. This indicates that the first conical surface 101 only affects the horizontal divergence or convergence of the beam, not its vertical divergence or convergence. With the introduction of the weak converging unit, the beam begins to converge after passing through it, eventually converging into a very small spot after propagating a certain optical path. Upon further propagation, the beam begins to diverge. Since the first conical surface 101 only affects the horizontal divergence or convergence of the beam, and not its vertical divergence or convergence, the beam has already traveled a relatively long optical path from the weak converging unit 400 to the first conical surface 101, resulting in some vertical divergence.

[0109] To address the unresolved issue of vertical laser beam divergence, a second unit 200 is arranged around the first unit 100. This unit includes a beam-converging surface 201 and a calibration surface 202. The beam-converging surface 201 has curvature in the vertical direction, enabling the laser beam to converge vertically. The laser beam passes through the weak-converging unit 400, the second conical surface 102, and the first conical surface 101, initially converging into a line in the vertical direction before diverging. The beam-converging surface 201 compensates for the vertical divergence, thus achieving vertical laser collimation. The calibration surface 202 guides the laser beam outwards.

[0110] The laser beam exits from the outer surface of the first unit 104, maintaining excellent collimation in the horizontal direction. However, in the vertical direction, due to the influence of the weak focusing unit 400, the laser beam diverges after traveling a long optical path. Therefore, the second unit 200 only provides vertical focusing for the laser beam to compensate for the divergence caused by the weak focusing unit 400 after traveling a long optical path, thus ensuring collimation in the vertical direction as well. Finally, after exiting from the surface of the second unit 202, the laser beam exhibits excellent collimation in both directions.

[0111] This system only requires the MEMS to rotate during the scanning process to achieve a 360-degree scan of the surroundings. No optical components in the entire system need to rotate. The system is small in size, simple in structure, long in service life, and lightweight, and it is relatively easy to achieve rotational scanning.

[0112] On the other hand, by setting the angle of the first conical surface 101 and the second conical surface 102, the laser beam can be transmitted through the second conical surface 102 with high transmittance, and total internal reflection occurs at the first conical surface 101. There is no need to coat the conical surface 101, which simplifies the coating process. Moreover, the laser beam can be horizontally emitted through the outer side of the first unit with only one transmission and one reflection. The number of reflections and refractions is small, and the light efficiency is high.

[0113] In MEMS lidar, to maintain the collimation of the laser, a weak convergence unit 400 and a second collimation unit 200 are set up to converge the diverging laser beam. The weak convergence unit 400 and the second collimation unit 200 cooperate with each other to ensure that the laser X is collimated in the vertical and horizontal directions and emitted horizontally.

[0114] To further simplify the device, the biconical lens of the first unit can be integrated with the second unit, such as... Figure 10 As shown.

[0115] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A MEMS lidar optical collimation and circular scanning device, characterized in that: include, The first collimation unit (100) includes a first conical surface (101) and a second conical surface (102) arranged symmetrically. The first conical surface (101) and the second conical surface (102) have a light-transmitting hole (103) near their geometric center. The first conical surface (101) and the second conical surface (102) have an outer surface (104) on the side away from the light-transmitting hole (103). The second collimation unit (200) includes a light converging surface (201) and a calibration surface (202) that cooperate with the outer surface (104). A microelectromechanical system (300) is disposed on one side of the light-transmitting hole (103), and the straight section between the microelectromechanical system (300) and the light-transmitting hole (103) is a first section (Q); and, A weak convergence unit (400) is provided on the side of the light-transmitting hole (103) away from the microelectromechanical system (300); The plane perpendicular to the first section (Q) is the horizontal plane (M). The first conical surface (101) forms a first angle A1 with the horizontal plane (M), the second conical surface (102) forms a second angle A2 with the horizontal plane (M), and the microelectromechanical system (300) forms a third angle A3 with the horizontal plane (M). The first included angle A1 and the third included angle A3 satisfy the following relationship: Where n is the refractive index of the material used in the optical element to which the first conical surface (101) belongs, and the second included angle A2 and the third included angle A3 satisfy the following relationship: To further control the laser beam emission mode to be horizontal, it is necessary to control the first included angle A1 and the third included angle A3 to satisfy the following relationship: 。 2. The MEMS lidar optical collimation and circular scanning device according to claim 1, characterized in that: The first section (Q) is also provided with a laser (500) that emits laser (X) to the first collimation unit (100). The laser (X) travels along the weak focusing unit (400), passes through the light-transmitting hole (103), and reaches the microelectromechanical system (300).

3. The MEMS lidar optical collimation and circular scanning device according to claim 2, characterized in that: A deep aperture stop (105) is also provided in the direction of laser (X) travel. The deep aperture stop (105) is provided in conjunction with the weak convergence unit (400) on the side away from the light-transmitting hole (103).

4. The MEMS lidar optical collimation and circular scanning device according to claim 3, characterized in that: The diameter of the light-transmitting hole (103) is smaller than the diagonal length of the microelectromechanical system (300), and the beam aperture of the laser (X) is smaller than the diagonal length of the microelectromechanical system (300). The laser (500) is located outside the front focal point of the weak focusing unit (400), with a vertical distance of L, where 1mm≤L≤5mm.

5. A method for optical collimation and circular scanning of a MEMS lidar, characterized in that: The MEMS lidar optical collimation and circular scanning device according to any one of claims 2-4 includes: Determine appropriate experimental parameters, including selecting the materials for the first conical surface (101) and the second conical surface (102); Calculate the size of the first included angle A1, the second included angle A2, and the third included angle A3 based on the selected material, and then calculate the curvature of the first conical surface (101) and the second conical surface (102); Based on the horizontal divergence of the laser (X) when it passes through the light-transmitting hole (103) and reaches the microelectromechanical system (300), the aperture size of the deep aperture stop (105) is set, and the large-angle aperture is intercepted by the deep aperture stop (105). Based on the horizontal divergence of the laser (X) when it is reflected by the microelectromechanical system (300) to the first conical surface (101), the lens curvature of the weak converging unit (400) is set to achieve the convergence of the horizontally diverging light of the laser (X), thereby achieving compensation after the laser (X) diverges horizontally when it reaches the first conical surface (101). Based on the vertical divergence of the laser (X) when it passes through the first collimating unit (100) and reaches the second collimating unit (200), the lens curvature of the light converging surface (201) is set to achieve the convergence of the vertically diverging light of the laser (X); Adjust the calibration surface (202) to provide the laser (X) arrival position after one interception and two convergences to achieve the best surround scanning effect.

6. The MEMS lidar optical collimation and circular scanning method according to claim 5, characterized in that: Adjust the relationship between the third included angle A3 and the second included angle A2 so that the laser (X) can have the highest transmittance when passing through the second conical surface (102).

7. The MEMS lidar optical collimation and circular scanning method according to claim 6, characterized in that: Adjust the relationship between the third included angle A3 and the first included angle A1 so that the laser (X) can undergo total internal reflection when it reaches the first conical surface (101).

8. The MEMS lidar optical collimation and circular scanning method according to claim 7, characterized in that: During the adjustment process, the third angle A3 between the microelectromechanical system (300) and the horizontal plane is first coarsely adjusted so that the laser (X) reaches the second collimation unit (200), and the vertical height of the second collimation unit (200) is determined to provide a carrier for the laser (X); By finely adjusting the first included angle A1 and the second included angle A2, the direction of the laser (X) after passing through the first collimation unit (100) is made parallel to the horizontal direction, and the second collimation unit (200) is used to determine that the laser (X) is in a collimated state.

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