A scanning laser radar

Abstract

The application provides a scanning laser radar, which comprises a transmitting unit, a light path deflection unit, a scanning unit and a receiving unit; the transmitting unit comprises a light source and a transmitting lens, and is used for emitting light as a transmitting light signal; the light path deflection unit is used for reflecting the incident transmitting light signal to the scanning unit and then to a space region, and a return wave reflected by a target is incident to the receiving unit through the scanning unit; wherein the center of the transmitting lens and the center of the light path deflection unit are located on a main optical axis, the center of the scanning unit is not located on the main optical axis, and the distance between the transmitting lens and the light path deflection unit corresponds to the distance from the center of the transmitting lens to an entrance pupil. By setting the relative position relationship and the distance of the transmitting lens, the light path deflection unit and the scanning unit, the volume of the laser radar is small, and the structure is compact; meanwhile, the transmitting and receiving efficiency of the laser radar is improved, the best laser scanning angle is obtained, and the ranging performance of the laser radar is improved.

Description

Technical Field

[0001] This application relates to the field of lidar technology, and more particularly to a scanning lidar. Background Technology

[0002] LiDAR is a device that uses laser beams to sense surrounding objects, reflecting the position and shape of surrounding objects in the form of point cloud data. It has the characteristics of high measurement resolution, fast speed, small size and light weight.

[0003] In existing technologies, scanning lidar systems are typically divided into two types: separate transmit / receive structures and coaxial transmit / receive structures. The separate transmit / receive structure stacks the transmitting unit and receiving module vertically, resulting in a larger lidar size and less compact structure. Furthermore, the transmit and receive fields of view do not overlap, easily creating blind spots and reducing detection efficiency. The coaxial transmit / receive structure, on the other hand, uses a single transceiver mirror, making the transmit and receive optical paths coaxial. For example, a reflector is used to project the transmitted beam and receive the reflected beam, and a rotating mirror is used to deflect the beam to achieve scanning detection of the spatial area. However, incorrect placement of optical components in a coaxial system can cause light signal blockage, leading to energy loss in the received beam, affecting the lidar's detection efficiency and scanning range. This significantly impacts the lidar's ranging performance, laser transmission and reception efficiency, and overall size.

[0004] Therefore, existing technologies still need to be improved and developed to address the aforementioned shortcomings. Summary of the Invention

[0005] The main objective of this application is to provide a scanning lidar that aims to partially solve the problems existing in the prior art.

[0006] To achieve the above objectives, a first aspect of this application provides a scanning lidar comprising: a transmitting unit, an optical path deflection unit, a scanning unit, and a receiving unit; the transmitting unit includes a light source and a transmitting lens for emitting light as an emitted light signal; the optical path deflection unit is used to reflect the incident emitted light signal to the scanning unit; the scanning unit is used to reflect the emitted light signal into a spatial region and receive echoes reflected by targets in the spatial region; the receiving unit includes a pixel array and a receiving lens for receiving the echoes and outputting electrical signals; wherein the center of the transmitting lens and the center of the optical path deflection unit are both located on the principal optical axis, the center of the scanning unit is not located on the principal optical axis, and the distance between the transmitting lens and the optical path deflection unit corresponds to the distance from the center of the transmitting lens to the entrance pupil.

[0007] In some embodiments, the scanning unit includes a rotating mirror, the rotating mirror including at least one reflective surface. The optical path deflection unit is offset from the rotating mirror by a preset distance in a direction perpendicular to the principal optical axis, and the critical value of the preset distance satisfies:

[0008]

[0009] Where f is the focal length of the emitting lens. Let β be the divergence angle of the emitted beam from the light source, β be the acute angle between the diagonals of the rotating mirror, and α be determined based on the maximum scanning angle of the scanning unit. The critical length of the rotating mirror is: By optimizing the positional relationship between the optical path deflection unit and the scanning unit mirror, the best laser scanning angle and light utilization efficiency can be obtained.

[0010] In some embodiments, the light source includes a laser array, and the distance between the laser array and the emitting lens is the focal length of the emitting lens; the minimum diameter of the emitting lens is determined based on the size of the laser array, the beam divergence angle, and the focal length of the emitting lens. By limiting the size of the emitting lens, the component is made small enough to reduce the overall size of the device, while ensuring that the transmitted optical signal meets the requirements.

[0011] In some embodiments, the optical path deflection unit includes a reflector or a semi-transparent mirror; wherein the semi-transparent mirror includes a reflecting region and a transmitting region. The minimum area of ​​the reflecting region of the optical path deflection unit is: In the system, the smaller the area (size) of the optical path deflection unit, the less it blocks the echo signal, and the ranging accuracy and range will be effectively improved.

[0012] In some embodiments, the lidar further includes a rectangular tube reflector, through which the emitted light signal is transmitted to the optical path deflection unit. The distance between the rectangular tube reflector and the emitting lens is the distance from the center of the emitting lens to the entrance pupil, and the minimum length and width of the opening of the rectangular tube reflector are:

[0013]

[0014]

[0015] in, Let f be the beam divergence angle of the laser, and f be the focal length of the emitting lens.

[0016] In summary, the scanning lidar proposed in this application includes a transmitting unit, an optical path deflection unit, a scanning unit, and a receiving unit. The transmitting unit includes a light source and a transmitting lens for emitting light as a transmitted light signal. The optical path deflection unit reflects the incident transmitted light signal to the scanning unit. The scanning unit reflects the transmitted light signal into a spatial region and receives the echo reflected by a target in the spatial region. The receiving unit includes a pixel array and a receiving lens for receiving the echo and outputting an electrical signal. The center of the transmitting lens and the center of the optical path deflection unit are both located on the principal optical axis, while the center of the scanning unit is not located on the principal optical axis. The distance between the transmitting lens and the optical path deflection unit corresponds to the distance from the center of the transmitting lens to the entrance pupil. By implementing the scheme of this application, the relative positional relationship and distance between the transmitting lens, the optical path deflection unit, and the scanning unit are set, ensuring that the lidar is small in size and compact in structure. Simultaneously, the transmission and reception efficiency of the lidar is improved, the optimal laser scanning angle is obtained, and the ranging performance of the lidar is enhanced. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art 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.

[0018] Figure 1 This is a schematic diagram of a preferred embodiment of the lidar of this application;

[0019] Figure 2 This is a schematic diagram showing the position of the scanning unit in a preferred embodiment of this application;

[0020] Figure 3 This is a schematic diagram of beam scanning in a preferred embodiment of this application.

[0021] Figure 4 This is a schematic diagram of the beam projection process in a preferred embodiment of this application. Detailed Implementation

[0022] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of this application with unnecessary detail.

[0023] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0024] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0025] 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 a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0026] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0027] Figure 1 The diagram shows the principle of the scanning lidar of this application. The scanning lidar includes: a transmitting unit 1, an optical path deflection unit 2, a scanning unit 3, and a receiving unit 4. Specifically, the transmitting unit 1 emits light as a transmitted light signal. The transmitted light signal is incident on the optical path deflection unit 2, reflected by the optical path deflection unit 2, and then transmitted along the main optical axis k to the scanning unit 3. The scanning unit 3 reflects the light signal and projects it into a spatial region. The transmitted light signal reflected by the target portion in the spatial region forms an echo, which is reflected by the scanning unit 3 and transmitted along the main optical axis k, and then passes through the optical path deflection unit 2 to the receiving unit 4. By setting the optical path deflection unit 2 and the scanning unit 3, the transmission optical path of the transmitted light signal and the reflected echo partially overlap. Generally, a scanning lidar also includes a control and processing unit (not shown). The control and processing unit is connected to the transmitting unit 1 and the receiving unit 4 and synchronously controls the activation of the transmitting unit 1 and the receiving unit 4. It also processes the signal output by the receiving unit 4 to obtain the flight time of the optical signal between the lidar and the target in the space area. Furthermore, the distance between the target and the lidar can be calculated based on the flight time.

[0028] The emitting unit 1 includes a light source 101 and an emitting lens 102. The light source 101 is used to emit optical signals; it can be a single light source or an array of multiple light sources. In a typical embodiment, the light source 101 is configured as a column light source consisting of multiple light sources, used to emit a linear beam with a first field of view significantly larger than a second field of view. In another typical embodiment, the light source 101 is configured as an array of multiple column light sources, arranged alternately along a first direction. This arrangement increases the spatial density of the light sources, thereby obtaining denser point cloud data. The first direction corresponds to the first field of view. The emitting lens 102 is used to collimate and process the transmitted optical signal before directing it to the optical path deflection unit 2.

[0029] The optical path deflection unit 2 is used to change the transmission direction of the emitted optical signal so that the emitted optical signal can be incident on a suitable position of the scanning unit 3, so that the scanning unit 3 can further deflect the light beam and incident it into the spatial region, and the reflected echo passes through the scanning unit 3 and the optical path deflection unit 2 and is incident on the receiving unit 4. In some embodiments, the optical path deflection unit 2 can be a reflector, which reflects the emitted optical signal so that it is transmitted to the scanning unit 3, and the reflected echo passes through both sides of the optical path deflection unit 2 and is incident on the receiving unit 4. However, since the optical path deflection unit 2 is also located on the transmission optical path of the echo signal, the reflector will block part of the echo signal. The size of the reflector needs to be reasonably designed to reduce the obstruction of the echo while ensuring that the transmission meets the requirements. In other embodiments, the optical path deflection unit 2 can be a semi-transparent mirror, meaning the mirror surface includes a reflective region and a transmission region. Preferably, the reflective region is located in the middle region. The reflective region is used to transmit the transmitted signal, and the transmission region is used to allow the echo to pass through. However, the reflective region will also block the echo, so the size of the reflective region also needs to be designed appropriately. It is understood that the size of the reflector in the mirror is equivalent to the size of the reflective region in the semi-transparent mirror. In the following description of specific embodiments, the size of the reflector will be the primary focus.

[0030] The scanning unit 3 is controllably rotatable, used to regulate the direction of the emitted light signal projected onto the spatial region and to receive the corresponding echo. When the scanning unit 3 rotates to a preset position, it transmits the emitted signal to the corresponding position in the spatial region and transmits the corresponding echo signal. Through continuous rotation, it completes the detection of different positions in the spatial region to achieve scanning of the spatial region in a second direction. The first direction and the second direction are perpendicular. If the light signal emitted by the emitting unit 1 extends along the first direction, the scanning unit 3 is configured to deflect the emitted light signal by rotation, so that the emitted light signal is scanned in the horizontal direction. Conversely, if the emitted light signal extends along the horizontal direction, the scanning unit 3 regulates the emitted light signal to extend along the first direction. The horizontal direction and the first direction are relative to the horizontal and vertical fields of view detected by the lidar. The scanning unit 3 can be a rotating mirror, which includes at least one reflective mirror that rotates clockwise or counterclockwise around a rotation axis under the drive of a motor; it can also be a galvanometer that can reciprocate along a fixed angle. In the following description of specific embodiments, the scanning unit will be mainly described using a rotating mirror.

[0031] The receiving unit 4 includes a pixel array and a receiving lens. The receiving lens is used to image the reflected light signal onto the pixel array. The pixel array is used to receive the echo signal and generate an electrical signal. The pixel array includes multiple pixels that collect photons and can be one of the single-photon devices that collect photons, such as APD, SPAD, or SiPM. In some embodiments, the receiving unit is an image sensor specifically designed for measuring the time of flight of light, where the pixel array can also be an integrated photosensitive chip specifically designed for time-of-flight measurement. Generally, the receiving unit 4 also includes a readout circuit composed of one or more of the following devices connected to the pixel array: a signal amplifier, a time-to-digital converter (TDC), and an analog-to-digital converter (ADC). The readout circuit is used to receive the electrical signal output by the pixel array and process it to obtain the time of flight of the light signal. The readout circuit can be integrated with the pixel array as part of the receiving unit 4, or it can be part of a control and processing unit; no specific limitations are made in this application.

[0032] The control and processing unit can be a separate dedicated circuit, such as an independent circuit with computing capabilities within the lidar itself; it can also include general-purpose processing circuitry, for example, when the lidar is integrated into terminal devices such as mobile phones, robots, or automobiles, the processor in the terminal can execute the functions of the control and processing unit. In this application, for ease of description, the control and processing unit is referred to as part of the lidar.

[0033] As described above, in a scanning lidar system, the optical path partially overlaps with the scanning unit. However, the position of the optical path deflection unit and its positional relationship with the scanning unit affect the transmission and reception of the optical signal, leading to energy loss in the received beam and impacting the lidar's detection efficiency and scanning range. For example, haphazard placement of the reflector can cause the scanning range of the rotating mirror to fall short of requirements, or the start / end angle of the scan to deviate from the region of interest. Both of these factors can result in low efficiency or even failure of the lidar ranging system. Therefore, the placement of the reflector and rotating mirror in the system is particularly important.

[0034] This application provides an optimized scanning lidar system through the design of the positions of various components. Specifically, the center of the emitting lens and the center of the optical path deflection unit are both located on the main optical axis, while the center of the scanning unit is not located on the main optical axis. The distance between the emitting lens and the optical path deflection element corresponds to the distance from the center of the emitting lens to the entrance pupil. The central axis of the laser's emitting surface is the main optical axis. Preferably, the distance between the emitting lens and the optical path deflection element is approximately equal to the focal length of the emitting lens.

[0035] In a scanning lidar system, the optical signal needs to be reflected by a mirror, incident on a rotating mirror, and then transmitted to the spatial region by the scanning mirror. Therefore, the relative positional relationship between the mirror and the rotating mirror significantly affects the detection efficiency of the lidar system. If the optical path deflection unit is placed arbitrarily, the scanning range of the scanning unit may not meet the requirements. Therefore, this application optimizes the positional relationship between the optical path deflection unit and the rotating mirror of the scanning unit to obtain the best laser scanning angle and light utilization efficiency. Combined with... Figure 1 and Figure 2 As shown, the rotating mirror and the reflecting mirror are offset by a preset distance in the direction perpendicular to the principal optical axis, and a critical value H is set for the offset distance. Within the critical value H, the larger the offset distance h, the higher the detection efficiency of the corresponding lidar system, and it can ensure a sufficient scanning angle to meet the field of view requirements. The critical value h satisfies the following relationship:

[0036]

[0037] Where f is the focal length of the emitting lens. Let α be the divergence angle of the emitted beam from the light source, β be the acute angle between the diagonals of the rotating mirror (determined by the shape and aspect ratio of the mirror), and α be determined by the maximum scanning angle of the scanning unit (π-2α is the maximum scanning angle). For different maximum scanning angles, α takes different values, and the critical values ​​also differ.

[0038] Furthermore, the critical length of the rotating mirror is defined as:

[0039]

[0040] like Figure 3 The illustrated beam scanning diagram shows that, within the critical range, the larger the offset distance, the larger the scanning range. Both the starting and ending scanning angles increase linearly. Specifically, the starting and ending scanning angles are as follows:

[0041] A Start =K Start *h+b Start

[0042] A End =K End *h+b End

[0043] Among them, A Start K is the starting scan angle. Start b is the slope of the initial scan line. Start A is the intercept of the starting scan line. End To terminate the scan angle, K End b is the slope of the terminating scan line. End The intercept of the final scan line is given by h, which is the offset distance. Correspondingly, the larger the offset distance, the larger the effective scanning angle and the larger the scanning range.

[0044] A Effectivity =(K Start -K End )*h+(b Start -b End )

[0045] Among them, A Effectivity For an effective scanning angle, K Start b is the slope of the initial scan line. Start A is the intercept of the starting scan line. End To terminate the scan angle, K End b is the slope of the terminating scan line. End The offset is the intercept of the final scan line, and h is the offset distance. According to the above formula, the larger the offset distance, the larger the scan area. Therefore, in this application, the offset distance h should be as large as possible within the critical value.

[0046] like Figure 4 In the schematic diagram of the emitted beam projection process shown, in one embodiment, the light source 101 is configured as a laser array comprising a plurality of lasers, the length of which is L. laser Width is W laser The radius of the aperture of each laser is R, and the beam divergence angle is... The laser array is located at the focal plane of the emitting lens, meaning the distance between the laser array and the emitting lens is the focal length f of the emitting lens. After collimation by the emitting lens, the light becomes parallel and illuminates the optical path deflection unit 2, forming a projected light spot (elliptical or circular). The shape and size of the light spot are determined by factors such as the aperture radius and divergence angle of the laser, the focal length of the emitting lens, and the tilt angle of the optical path deflection unit. In one embodiment of this application, the size of the emitting lens is first limited to ensure that the component is small enough to reduce the overall size of the device while still ensuring that the transmitted emitted light signal meets the requirements. Specifically, the minimum diameter of the emitting lens is determined based on the size of the laser array, the beam divergence angle, and the focal length of the emitting lens. In one embodiment, the emitting lens can be elliptical, and the minimum diameter of the emitting lens is:

[0047]

[0048] Among them, W laser For the length of the laser array, L laser Let φ be the width of the laser array, φ be the divergence angle of the laser array, f be the focal length of the collimating lens, and D be the focal length of the collimating lens. CollimatingLens This is the diameter of the collimating lens. In another embodiment, the emitting lens is circular, then the minimum diameter of the emitting lens is: This ensures that the entire emitted optical signal is covered while keeping the component size to a minimum, which is beneficial for device miniaturization.

[0049] The optical path deflection unit 2 reflects the emitted beam to the scanning unit 3 and then transmits it to the spatial region. The echo reflected by the target in the spatial region travels along the same optical path, is reflected by the scanning unit 3, and then incident on the receiving lens and into the pixel array. In this process, the smaller the area (size) of the optical path deflection unit, the less it obstructs the echo signal, effectively improving ranging accuracy and range. The following explanation uses a reflector as an example. When setting the optical path, the reflector and the emitting lens are aligned in the same straight line in the light transmission direction. The distance between the reflector and the emitting lens corresponds to the distance from the optical center of the emitting lens to the entrance pupil. Assuming the reflecting surface of the reflector is elliptical, the minimum major and minor axes of the ellipse are:

[0050]

[0051]

[0052] in, Let f be the divergence angle of the laser array, f be the distance between the reflector and the emitting lens, and θ be the acute angle between the reflector and the principal optical axis. Preferably, the angle between the optical path deflection unit and the principal optical axis is 45°. Then, the minimum area of ​​the reflective region of the reflector is:

[0053]

[0054] In one specific embodiment, the optical path deflection unit can be a semi-transparent and semi-reflective mirror. In order to provide better support for the optical path deflection unit, a reflective film and an anti-reflective film can be coated on a transparent medium to form a reflective area and a projection area. The reflective area is set according to the minimum area of ​​the aforementioned reflective mirror, and the transmission area can be designed according to specific circumstances. No specific limitations are imposed in this application.

[0055] Understandably, in the aforementioned lidar system design, the distance between various electronic components, such as the transmitting and receiving units, is set relatively close. To ensure effective communication of electrical signals between different components, better resist electromagnetic interference, and ensure operational redundancy, it is necessary to flexibly adjust the distance between the light source and the optical path deflection unit. Generally, the greater the distance between the light source and the optical path deflection unit, the more effectively the interference problem can be solved. However, the greater the distance, the larger the area of ​​the reflection region, meaning the size of the optical path deflection unit needs to be increased, which will block the echo signal and prevent the lidar from effectively measuring the target's distance information.

[0056] To resolve this contradiction, this embodiment proposes including a rectangular tube reflector in the scanning lidar. The rectangular tube reflector has reflective areas surrounding its interior, which can reflect the light signal and change the transmission direction of the light path. This extends the transmission distance of the light signal from the laser to the optical path deflection unit without increasing the area of ​​the reflective areas. Furthermore, it effectively extends the distance between the transmitting and receiving units, preventing the laser's heat dissipation from affecting the photoelectric performance of the pixel array. The rectangular tube reflector is placed at the conjugate object of the light source and the transmitting lens. The distance between the rectangular tube reflector and the transmitting lens is the distance from the center of the transmitting lens to the entrance pupil, which is approximately the focal length f of the transmitting lens. The emitted light signal, collimated by the transmitting lens, enters the rectangular tube reflector and is continuously reflected within it before being output to the optical path deflection unit. Preferably, the optical path deflection unit is located at the light outlet of the rectangular tube reflector. The minimum length and width of the rectangular tube reflector's opening are:

[0057]

[0058]

[0059] in, Let f be the laser beam divergence angle, and f be the focal length of the collimating lens. The length of the rectangular tube can be adjusted according to the system electronics, module volume, and electromagnetic interference resistance. The length and width of the rectangular tube opening are both minimum values, and the beam diameter at the exit of the rectangular tube is the same as the size of the tube opening. Following the aforementioned design principle of minimum reflector area, the reflector area is minimized. When the incident beam passes through the rectangular tube and enters the reflector, the reflector's obstruction area is minimized, thus minimizing obstruction of the echo signal beam. Optionally, the rectangular tube can be configured as a multi-section bent structure, which can also extend the optical path length while minimizing reflector obstruction. In practical applications, considering processing and assembly tolerances, the length and width of the rectangular tube should be slightly larger than the minimum values, and the reflector should be placed close to the exit of the rectangular tube.

[0060] In some embodiments, the laser array is configured as an array of at least one column of light sources, each column including a plurality of lasers arranged along a first direction, each laser projecting a spot beam uniformly distributed and shaped into a line beam along the first direction. In a typical embodiment, to ensure a uniform distribution of the spot scanning angle along the first direction, the distances between each laser and the center of the laser array satisfy the following relationship:

[0061] L N，Laser =tan(N*Δγ)*f;

[0062] Among them, L N，Laser Let N be the distance between each laser and the center of the laser array, N be the laser number arranged in the first direction from the array center, Δγ be the scanning angular resolution in the first direction, and f be the focal length of the emitting lens. In another typical embodiment, to ensure uniform spatial distribution of the scanning positions in the first direction, the positions of each laser from the center of the laser array satisfy the following:

[0063]

[0064] Among them, L N，Laser Where N is the distance of each point light source from the center of the laser array, N is the laser number arranged in the first direction from the center of the array, f is the focal length of the emitting lens, and FOV is the field of view angle in the object space direction where the line light source is located. maxThis refers to the density of point light sources along the scanning direction of half a light source array. In summary, this application proposes a lidar and a target object scanning method based on lidar. The lidar includes: a transmitting unit, an optical path deflection unit, a scanning unit, and a receiving unit. The transmitting unit emits a transmitted beam, which is incident on the optical path deflection unit through a lens. The optical path deflection unit reflects the incident transmitted beam to the scanning unit. The vertical distance between the center of the optical path deflection unit and the optical center of the lens is the vertical distance from the optical center of the lens to the incident pupil. The area of ​​the optical path deflection unit is smaller than the area of ​​the scanning unit used to receive the transmitted beam. The scanning unit reflects the incident transmitted beam to the target object to obtain the reflected beam, and then reflects the reflected beam through the optical path deflection unit to the receiving unit. In this application, a coaxial transmitting and receiving structure is used to ensure that the reflected beam is incident on the receiving unit through the optical path deflection unit, thus ensuring a small lidar size and compact structure. Simultaneously, the vertical distance between the center of the optical path deflection unit and the optical center of the lens is limited to adapt to the optimal laser scanning angle and improve the working efficiency of the lidar.

[0065] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0066] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions are not in essence a departure from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A scanning lidar, characterized by, Comprise: a transmitting unit, a light path deflection unit, a scanning unit and a receiving unit; the transmitting unit comprises a light source and a transmitting lens, for emitting light as a transmitting light signal; the light path deflection unit is used for reflecting the incident transmitting light signal to the scanning unit; the scanning unit is used for reflecting the transmitting light signal to a spatial region, and receiving a echo reflected by a target in the spatial region; the scanning unit comprises a rotating mirror, and the rotating mirror comprises at least one reflecting surface; the plan view of the rotating mirror is quadrilateral; the light path deflection unit and the rotating mirror are offset by a preset distance in the direction of the vertical principal optical axis, and the critical value of the preset distance satisfies: ； wherein, is a focal length of the emission lens, is a divergence angle of the light beam emitted by the light source, is an acute angle subtended by a diagonal of the turning mirror, is determined from a maximum scan angle of the scan unit; the receiving unit comprises a pixel array and a receiving lens, for receiving the echo and outputting an electrical signal; wherein, the center of the transmitting lens and the center of the light path deflection unit are both on the principal optical axis, the center of the scanning unit is not on the principal optical axis, and the distance between the transmitting lens and the light path deflection unit corresponds to the distance from the center of the transmitting lens to the entrance pupil.

2. The lidar of claim 1, wherein, The critical length of the rotating mirror: .

3. The lidar of claim 1, wherein, The light source comprises a laser array, and the distance between the laser array and the transmitting lens is the focal length of the transmitting lens; The minimum diameter of the transmitting lens is determined according to the size of the laser array, the beam divergence angle and the focal length of the transmitting lens.

4. The lidar of claim 3, wherein, The light path deflection unit comprises a reflecting mirror or a half-mirror; wherein, the half-mirror comprises the reflecting region and the transmitting region.

5. The lidar of claim 4, wherein, The minimum area of the reflection region of the light path deflection unit is: .

6. The lidar of claim 3, wherein, The laser radar further comprises a rectangular tube mirror, and the transmitting light signal is transmitted to the light path deflection unit via the rectangular tube mirror.

7. The lidar of claim 6, wherein, The distance between the rectangular tube mirror and the transmitting lens is the distance between the center of the transmitting lens and the entrance pupil, and the minimum length and width of the tube opening of the rectangular tube mirror are respectively: L_Tube=2f*tan(φ / 2) W_Tube=2f*tan(φ / 2) wherein, is the beam divergence angle of the laser, is the focal length of the emission lens.

8. The lidar of claim 3, wherein, The laser array is configured to comprise a plurality of column light sources, each of which comprises a plurality of lasers arranged in a first direction, and each of the lasers is a distance from the center of the laser array: ； wherein L N，Laser is the distance of each laser from the center of the laser array, N is the serial number of the laser arranged at the distance from the center of the array in the first direction, γ is the scanning angle resolution in the first direction, is the focal length of the emission lens.

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