LiDAR optical system and frequency modulated continuous wave lidar

Abstract

This invention relates to the field of lidar technology, providing a lidar optical system and a frequency-modulated continuous wave lidar. The lidar optical system includes a lens module with a first light-guiding region and a second light-guiding region. The first light-guiding region receives the emitted laser and collimates it for output, and also receives a first echo signal and converges it to a first receiving region. The second light-guiding region receives a second echo signal and converges it to a second receiving region. A gap exists between the second and first receiving regions. The first echo signal is the signal located in the central region of the echo signal, and the second echo signal is the signal in the echo signal excluding the first echo signal. The lidar optical system and frequency-modulated continuous wave lidar provided by this invention can effectively reduce the adverse effects of the walk-off effect.

Description

Technical Field

[0001] This invention belongs to the field of lidar technology, and particularly relates to a lidar optical system and a frequency-modulated continuous wave lidar. Background Technology

[0002] Existing frequency-modulated continuous wave (FMCW) lidar, employing a separate transmit / receive configuration, requires a free-space optical circulator. However, this device suffers from drawbacks such as large size, high cost, difficult assembly and adjustment, and unreliable performance in complex environments. Furthermore, when detecting distant targets, the scanning system experiences a deflection relative to the transmitting system during reception, causing a walk-off effect. This results in a positional shift of the optical signal at the receiving surface, making it difficult for the signal to couple effectively into fiber optic or waveguide detectors. Currently, methods to mitigate the energy loss caused by the walk-off effect, leading to difficulties in long-distance detection, include increasing the amount of fiber optic or waveguide at the receiving surface, forming fiber optic or waveguide arrays to improve the overall equivalent receiving surface of the detector. This allows the detector to still detect the signal even after the walk-off angular shift. However, this method significantly increases costs and places immense pressure on the backend hardware signal processing. Therefore, developing an optical system and frequency-modulated continuous wave lidar that can mitigate the energy loss caused by the walk-off effect is essential. Summary of the Invention

[0003] The purpose of this invention is to provide a lidar optical system and a frequency-modulated continuous wave lidar, which aims to mitigate the energy loss caused by the walk-off effect.

[0004] The present invention is implemented as follows: In a first aspect, a lidar optical system is provided, including a lens module. The lens module has a first light-guiding region and a second light-guiding region. The first light-guiding region is used to receive an emitted laser and collimate the emitted laser for output, and also to receive a first echo signal and converge the first echo signal to a first receiving region. The second light-guiding region is used to receive a second echo signal and converge the second echo signal to a second receiving region. There is a gap between the second receiving region and the first receiving region. The first echo signal is a signal located in the central region of the echo signal, and the second echo signal is a signal other than the first echo signal in the echo signal.

[0005] In an optional embodiment, the second light-guiding region is disposed around the first light-guiding region.

[0006] In an optional embodiment, the lens module includes a first convex lens and a second convex lens arranged sequentially along the emitted laser beam path. The principal optical axes of the first convex lens and the second convex lens are located on the same straight line. The aperture of the first convex lens is smaller than that of the second convex lens. The central regions of the first and second convex lenses are used to cooperate in receiving the emitted laser and collimating the emitted laser beam. The first convex lens is also used to receive the first echo signal and converge the first echo signal to the first receiving region. The second convex lens is also used to receive the first echo signal and the second echo signal, converge the first echo signal to the first convex lens, and converge the second echo signal to the second receiving region. The central regions of the first and second convex lenses combine to form the first light guiding region, and the edge region of the second convex lens forms the second light guiding region.

[0007] In an optional embodiment, the lens module includes an annular lens, the central region of which has a first convex structure and the edge region has a second convex structure, the focal length of the first convex structure being less than the focal length of the second convex structure, the central region of the annular lens forming the first light-guiding region, and the edge region of the annular lens forming the second light-guiding region.

[0008] In an optional embodiment, the lens module is a multifocal lens.

[0009] Secondly, a frequency-modulated continuous wave lidar is provided, including a laser generator, a transceiver module, an optical system, and a scanning module. The optical system is the lidar optical system provided in the above embodiments. The transceiver module is provided with a transmitting medium and a receiving medium. The transmitting medium is used to receive and output the emitted laser emitted by the laser generator. There are at least two receiving media, one of which is located in the first receiving area, and the remaining receiving media are located in the second receiving area.

[0010] In an optional embodiment, the transmitting medium is further used to receive the first echo signal or at least a portion of the second echo signal, in which case the transmitting medium is one of the receiving media.

[0011] In an optional embodiment, the scanning module includes a one-dimensional galvanometer and a one-dimensional rotating mirror. The one-dimensional galvanometer is used to control the emitted laser to scan along the Y direction, and the one-dimensional rotating mirror is used to control the emitted laser to scan along the X direction. The receiving medium, other than the emitting medium, is located on the same side of the emitting medium.

[0012] In an optional embodiment, the scanning module includes a two-dimensional galvanometer for controlling the emitted laser to perform two-dimensional scanning along the X and Y directions. The receiving medium is provided with at least three, with the receiving medium other than the emitting medium being disposed on both sides of the emitting medium.

[0013] In an optional embodiment, a transmitting medium and a receiving medium disposed on both sides of the transmitting medium form a transceiver module, and an optical system corresponds to one or more of the transceiver modules.

[0014] The technical advantages of this invention compared to the prior art are as follows: The lidar optical system and frequency-modulated continuous wave lidar provided in the embodiments of this invention are provided with a first light-guiding region and a second light-guiding region. The first echo signal located in the central region and the second echo signal located in the edge region can be converged into the first receiving region and the second receiving region respectively through the first light-guiding region and the second light-guiding region. The first receiving region and the second receiving region have a gap, but this gap can be a very small distance. The minimum gap can be adjusted to reach the minimum distance between two adjacent waveguides. This setting allows the echo signal to be divided into multiple parts and received by receiving media located in different regions. In this way, the lidar can achieve a larger receiving surface by setting multiple receiving media to receive more echo signals. This ensures that even if the walk-off effect occurs, the lidar using the lidar optical system provided in the embodiments of this invention still has good signal collection capability.

[0015] Furthermore, when the parameters of each light-guiding region in the lidar optical system provided in this embodiment are set reasonably, the distance between the first receiving region and the second receiving region can be adjusted to the minimum distance that two adjacent waveguides can reach. Thus, the lidar optical system provided in this embodiment can effectively reduce the adverse effects of the walk-off effect. Compared to setting a large-area waveguide array in the transceiver module, it can effectively reduce the number of receiving channels and signal processing complexity, simplify the hardware system of the lidar using the lidar optical system provided in this embodiment, reduce the size of the corresponding lidar, and improve the reliability of the lidar. In addition, the lidar optical system provided in this embodiment can also effectively reduce the complexity of the optomechanical system in the lidar and reduce the cost of unnecessary optical components. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention or the prior art 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.

[0017] Figure 1 This is a schematic diagram of the usage status of the lidar optical system provided in the embodiment of the present invention. Figure 1 The echo signal in the figure does not show any walk-off angle shift or the walk-off angle is small, and the lens module in the figure includes a first convex lens and a second convex lens. The arrow in the figure indicates the transmission direction of the echo signal.

[0018] Figure 2 This is a schematic diagram of the usage status of the lidar optical system provided in the embodiment of the present invention. Figure 2 The echo signal in the figure shows a walk-off angle shift, and the lens module in the figure includes a first convex lens and a second convex lens. The arrow in the figure indicates the transmission direction of the echo signal.

[0019] Figure 3 This is a schematic diagram of the usage status of the lidar optical system provided in the embodiment of the present invention. Figure 1 The echo signal in the figure does not show any walk-off angle shift or the walk-off angle is small, and the lens module in the figure includes a ring lens. The arrow in the figure indicates the transmission direction of the echo signal.

[0020] Figure 4 (a), (b), and (c) are schematic diagrams showing different arrangements of the lens module and transceiver module used in the embodiments of the present invention.

[0021] Explanation of reference numerals in the attached figures:

[0022] 100. Lens module; 110. First convex lens; 120. Second convex lens; 130. Ring lens; 131. First convex structure; 132. Second convex structure; 200. Transceiver module; 210. Transmitting medium; 220. Receiving medium; 300. Transceiver module; 400. Scanning module; 500. First echo signal; 500. Second echo signal. Detailed Implementation

[0023] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0024] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0026] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0028] Please refer to Figures 1 to 3 As shown, in one embodiment of the present invention, a lidar optical system is provided, including a lens module 100, which has a first light-guiding region and a second light-guiding region. The first light-guiding region is used to receive an emitted laser and collimate the emitted laser output, and also to receive a first echo signal 400 and converge the first echo signal 400 to a first receiving region. The second light-guiding region is used to receive a second echo signal 500 and converge the second echo signal 500 to a second receiving region. There is a gap between the second receiving region and the first receiving region. The first echo signal 400 is a signal located in the central region of the echo signal, and the second echo signal 500 is a signal in the echo signal other than the first echo signal 400.

[0029] Specifically, the lens module 100 in this embodiment can be a combination of multiple lenses, or it can be a ring lens 130, a bifocal lens, or a multifocal lens, etc., which can be flexibly selected according to the application needs, and there is no unique limitation here. The first light guiding area and the second light guiding area can each correspond to an independent lens, or they can each correspond to different parts of the same lens, as long as the above functions can be achieved. The specific selection can be flexibly selected according to the application needs, and there is no unique limitation here. In addition, the first light guiding area and the second light guiding area in this embodiment can each be a continuous whole area, or they can each be composed of multiple spaced-apart separate areas. The specific selection can be flexibly selected according to the application needs, and there is no unique limitation here.

[0030] In this embodiment, the first receiving area is generally a continuous receiving surface, but in special cases it can also be multiple receiving surfaces arranged at intervals. The second receiving area can be a continuous receiving surface or multiple separately arranged receiving surfaces. When the second receiving area includes multiple separately arranged receiving surfaces, the multiple receiving surfaces can surround the first receiving area, or partially surround the first receiving area, or all be located on one side of the first receiving area, or be arranged in other ways. When the multiple receiving surfaces are located on one side of the first receiving area, they can be distributed at intervals along a preset path, or arranged in an array according to a preset arrangement, or arranged irregularly. The specific arrangement can be flexibly selected according to the needs of use, and there is no unique limitation here.

[0031] For ease of description, the term "laser radar optical system" will be simplified to "optical system" in some parts of the following text. Those skilled in the art should know that both "laser radar optical system" and "optical system" in the following text refer to the laser radar optical system provided in the embodiments of the present invention.

[0032] Specifically, the lidar optical system provided in this embodiment of the invention has a co-located transmit and receive structure. For ease of understanding, the working principle of the lidar optical system provided in this embodiment of the invention will be explained using a lidar system applying the lidar optical system provided in this embodiment as an example:

[0033] In use, the optical system is placed between the laser generating component and the scanning module 300. The laser generating component includes a laser generator and a transceiver module 200. The laser generator emits a laser beam, and the transceiver module 200 includes a transmitting medium 210 for receiving and outputting the emitted laser beam, and a receiving medium 220 for receiving echo signals. Specifically, multiple receiving media 220s are provided. More specifically, in some embodiments, the transmitting medium 210 can also be used to receive a first echo signal 400 or a second echo signal 500, i.e., the transmitting medium 210 is one of the receiving media 220s. In other embodiments, the transmitting medium 210 is only used for transmitting signals and not for receiving echo signals. When the transmitting medium 210 can be used as a receiving medium 220, the receiving medium 220 includes, in addition to the transmitting medium 210, at least one waveguide solely for receiving echo signals; when the transmitting medium 210 is only used for transmitting signals, at least two waveguides solely for receiving echo signals are provided.

[0034] Before detection, the relative positions of the various light-guiding areas, laser generator, transceiver module 200, and scanning module 300 in the optical system need to be adjusted so that the beam output from the transmitting medium 210 in the transceiver module 200 can be collimated and emitted through the first light-guiding area. Simultaneously, the beam converged by the first and second light-guiding areas can propagate to or pass through the location of the receiving medium 220. In other words, the receiving medium 220 needs to be located within either the first or second receiving area. Since there are multiple receiving media 220s, the requirement that the receiving medium 220 be located within the first or second receiving area means that at least one of the multiple receiving media 220s is located within the first receiving area, and the remaining receiving media 220s are located within the second receiving area.

[0035] When a target needs to be detected, the various devices in the lidar system are activated. The laser generator emits a laser beam (i.e., the emitted laser). The transmitting medium 210 in the transceiver module 200 receives and outputs the emitted laser. The emitted laser is collimated by the first light-guiding area in the lidar optical system provided in this embodiment of the invention. The collimated beam is redirected by the scanning module 300 to perform a two-dimensional scan of the target. The echo signal reflected back from the target is then converged sequentially by the scanning module 300 and the first or second light-guiding area to the corresponding receiving medium 220 located in the first or second receiving area. Each receiving medium 220 couples the received echo signal to the silicon photonics detection chip for subsequent signal processing. Specifically, the signal located in the central region of the echo signal (i.e., the first echo signal 400) is converged by the first light-guiding area to the receiving medium 220 located in the first receiving area, and the signal other than the first echo signal 400 (i.e., the second echo signal 500) is converged by the second light-guiding area to the receiving medium 220 located in the second receiving area.

[0036] The lidar optical system provided in this embodiment of the invention includes a first light-guiding region and a second light-guiding region. These regions converge a first echo signal 400 located in the central region and a second echo signal 500 located in the edge region into the first receiving region and the second receiving region, respectively. The first and second receiving regions are spaced apart, but this distance can be very small, at least the minimum distance achievable by adjusting to the distance between two adjacent waveguides. This arrangement allows the echo signal to be divided into multiple parts, which are received by receiving media 220 located in different regions. Furthermore, by using multiple receiving media 220, the lidar can achieve a larger receiving surface area, receiving more echo signals. This ensures that even if a walk-off effect occurs, the lidar using the lidar optical system provided in this embodiment of the invention still has good signal collection capabilities.

[0037] Furthermore, when the parameters of each light-guiding region in the lidar optical system provided in this embodiment are set reasonably, the distance between the first receiving region and the second receiving region can be adjusted to the minimum distance that two adjacent waveguides can reach. Thus, the lidar optical system provided in this embodiment can effectively reduce the adverse effects of the walk-off effect. Compared to setting a large-area waveguide array in the transceiver module 200, it can effectively reduce the number of receiving channels and signal processing complexity, simplify the hardware system of the lidar using the lidar optical system provided in this embodiment, reduce the size of the corresponding lidar, and improve the reliability of the lidar. In addition, the lidar optical system provided in this embodiment can also effectively reduce the complexity of the optomechanical system in the lidar and reduce the cost of unnecessary optical components.

[0038] Since the second echo signal 500 is generally distributed on both sides of or around the first echo signal 400, in an optional embodiment, to ensure that the second light guide region can receive a large proportion of the second echo signal 500, the second light guide region is arranged around the first light guide region. Specifically, the second light guide region can be a ring structure or include multiple separate structures. The specific choice can be flexibly made according to the distribution of the second echo signal 500 and the first echo signal 400 and the required reception accuracy; no single limitation is imposed here.

[0039] There are various ways to implement the first and second light-guiding areas mentioned above. Please refer to the examples provided. Figure 1 and Figure 2 As shown, in an optional embodiment, the lidar optical system includes a first convex lens 110 and a second convex lens 120 arranged sequentially along the emitted laser beam path. The principal optical axes of the first convex lens 110 and the second convex lens 120 are located on the same straight line. The aperture of the first convex lens 110 is smaller than that of the second convex lens 120, and the central regions of the first convex lens 110 and the second convex lens 120 are used to cooperate in receiving the emitted laser and collimating the emitted laser output. The first convex lens 110 is also used to receive a first echo signal 400 and converge the first echo signal 400 to a first receiving region. The second convex lens 120 is also used to receive the first echo signal 400 and a second echo signal 500, converge the first echo signal 400 to the first convex lens 110, and converge the second echo signal 500 to a second receiving region. The central regions of the first convex lens 110 and the second convex lens 120 combine to form a first light guiding region, and the edge region of the second convex lens 120 forms a second light guiding region.

[0040] In this embodiment, the aperture of the first convex lens 110 and the second convex lens 120 can be determined according to the energy of the echo signal, and the focal length can be determined by the interval between each receiving medium 220 in the adapted transceiver module 200 and the walk-off angle.

[0041] When the lens module 100 uses a single ordinary convex lens, the transmitting medium 210 in the transceiver module 200 is placed at the focal point of the convex lens. Because the optical path is reversible, when there is no walk-off angle, the echo signal returns along the same path and is received by the transmitting medium 210, while the adjacent receiving medium 220 has no optical signal to couple with. However, when a walk-off angle shift occurs, the receiving light spot moves. Since there is a gap between the transmitting medium 210 and the adjacent receiving medium 220, if the light spot moves into this gap, neither the transmitting medium 210 nor the adjacent receiving medium 220 will emit an echo signal. If the walk-off angle increases at this point, the light spot will be received when it shifts to the adjacent receiving medium 220. Therefore, during the entire detection process, when the receiving light spot moves into the gap between the transmitting medium 210 and the receiving medium 220, the distance and velocity information of the target object will be lost because the receiving light spot cannot receive signals. To avoid this phenomenon, the solution provided in this embodiment can generate a positional difference on the optical axis between the convergence points of the central region and other regions. This difference can be positive or negative, thereby dividing the echo signal into different parts and causing the echo signals of different parts to fall on different regions of the same plane, thereby increasing the receiving spot area of ​​the echo signal falling on the transceiver module 200, so that it can be received by different receiving media 220.

[0042] The working principle of the optical system provided in this embodiment is as follows:

[0043] When the echo signal has no walk-off angle shift, the optical signal at close range can be effectively received by the transmitting medium 210. When a certain walk-off angle is generated, the light spot in the central region (i.e., the first echo signal 400) shifts to the space between the two waveguides, while the optical signal in other regions can still cover the adjacent receiving medium 220. As the walk-off angle continues to increase, the light spot in the central region can shift to the adjacent receiving medium 220, thereby achieving good signal energy collection throughout the entire detection range.

[0044] Furthermore, the focal length f3 of the lens module provided in this embodiment can be calculated using the focal length f1 of the first convex lens, the focal length f2 of the second convex lens, and the distance d between them. Combined with the formula for calculating the Airy disk radius, it can be concluded that by controlling the size and spacing of the echo spot on the transceiver module 200, and coordinating this with the distribution of the receiving medium 220 and the transmitting medium 210, a high coupling efficiency can be achieved. In use, by controlling the apertures of the first and second convex lenses 120, the energy ratio of the first echo signal 400 and the second echo signal 500 can be rationally allocated.

[0045] Formula for calculating combined focal length:

[0046] f3 = (f1 * f2) / (f1 + f2 - d);

[0047] Formula for calculating the radius of an Airy disk:

[0048] R Airy =1.22*(λ / D)*f.

[0049] In the formula, λ is the wavelength of the echo signal; D is the aperture of the optical system; f is the focal length of the lens module, i.e., f3 mentioned above; R Airy The radius of the Airy disk is given. It should be noted that those skilled in the art should understand that the optical system mentioned here is not the same as the lidar optical system described herein. The Airy disk radius is the maximum achievable spot size of the system; the spot radius illuminating the receiving medium 220 is greater than or equal to the Airy disk radius.

[0050] This structure simplifies the overall optical system and makes it easy to adjust the position between the first convex lens 110 and the second convex lens 120 according to the light output effect.

[0051] Furthermore, multiple first convex lenses 110 and multiple second convex lenses 120 can be provided, with the multiple first convex lenses 110 and multiple second convex lenses 120 arranged sequentially along the emission optical path of the emitted laser. Specifically, the exact number of first convex lenses 110 and second convex lenses 120 can be flexibly selected according to the proportion of received echo signals and the detection accuracy requirements of the lidar, and is not limited here.

[0052] Please refer to Figure 3As shown, in another optional embodiment, the lidar optical system includes an annular lens 130. A first convex structure 131 is formed in the central region of the annular lens 130, and a second convex structure 132 is formed in the edge region. It should be noted that the edge region refers to the region of the annular lens 130 other than the central region. The first convex structure 131 and the second convex structure 132 respectively form convex lens structures, which can be composed of an annular surface, a plane, and a structure between the two surfaces, or they can be composed of two annular surfaces and a structure between the two surfaces. The specific configuration can be flexibly set according to the application requirements, and no unique limitation is made here.

[0053] The focal length of the first convex structure 131 is smaller than that of the second convex structure 132. The central region of the annular lens 130 (i.e., the region where the first convex structure 131 is located) forms a first light-guiding region, and the central region of the annular lens 130 (i.e., the region where the second convex structure 132 is located) forms a second light-guiding region. In this embodiment, the focal length of the first convex structure 131 and the second convex structure 132 can be controlled by adjusting the curvature and other characteristics of the convex surfaces in their respective structures.

[0054] The working principle of the optical system provided in this embodiment for receiving echo signals is as follows:

[0055] The echo signals reflected back from the target object are as follows: the first echo signal 400 located in the center is focused by the first light guide area and then illuminated by the first receiving area, and received by the receiving medium 220 located in the first receiving area; the second echo signal 500 located at the edge is focused by the second light guide area and then illuminated by the second receiving area, and received by the receiving medium 220 located in the second receiving area.

[0056] It should be noted that, since the focal length of the first convex structure 131 is shorter than that of the second convex structure 132, the first receiving area mentioned in the above receiving process can be the area corresponding to the focal point of the first convex structure 131, or it can be the area corresponding to a certain position between the focal point of the first convex structure 131 and the first convex structure 132, as long as the receiving medium 220 can receive the vast majority of the first echo signals 400 in this area. The second receiving area is generally not the area corresponding to the focal point of the second convex structure 132, but rather the area corresponding to a certain position between the focal point of the second convex structure 132 and the second convex structure 132. The specific location can be determined based on the reception effect of the second echo signal 500.

[0057] The optical system provided in this embodiment has a simple structure and is easy to install and position.

[0058] Furthermore, the aforementioned annular lens can be either a double-ring lens or a multi-ring lens. When the annular lens is a double-ring lens, the convex structure at the center is the first convex structure, and the convex structures on the outer periphery are the second convex structures. When the annular lens is a multi-ring lens, at least one convex structure at the center is the first convex structure, and the remaining convex structures surrounding the first convex structure form the second convex structure. The number of rings and the curvature of each convex surface within the annular lens can be flexibly selected based on the reception effect of the echo signal and the detection accuracy requirements of the lidar; no single limitation is imposed here.

[0059] In another optional embodiment, the lens module is a multifocal lens. Specifically, the multifocal lens can be a bifocal lens, a trifocal lens, a quadfocal lens, etc., which can be selected according to the application requirements. For example, if the echo signal can be divided into two parts by a bifocal lens to achieve the reception of all or a large proportion of the echo signal and meet the detection accuracy requirements, then a bifocal lens can be used. If the reception effect of a bifocal lens is not satisfactory, a lens with more focal points can be used until the reception effect meets the requirements.

[0060] In the above embodiments, by controlling the combination of lenses with different focal lengths or the different focal lengths of the ring lens, different focal length differences are achieved in the entire optical system. This allows for the rational distribution of the echo signal spot on the transceiver module, enabling the transceiver module to collect the echo signal at different walk-off angles. This effectively reduces the walk-off effect and simplifies the opto-electro-mechanical system and the complexity of back-end signal processing in the corresponding lidar. Furthermore, by adjusting parameters such as the focal length of each lens, the spacing between lenses, the aperture of the lenses, and the curvature of the ring lens, different arrangements and designs of the transmitting and receiving waveguides at the transceiver end can be adapted, making the adjustment of lidars using the optical systems provided in the above embodiments more flexible.

[0061] Please refer to Figures 1 to 3 As shown, in another embodiment of the present invention, a frequency-modulated continuous wave lidar is provided, including a laser generator, a transceiver module 200, an optical system, and a scanning module 300. The optical system is the lidar optical system provided in the above embodiments. The transceiver module 200 is provided with a transmitting medium 210 and a receiving medium 220. The transmitting medium 210 is used to receive and output the emitted laser emitted by the laser generator. There are at least two receiving media 220, with one receiving medium 220 located in a first receiving area and the remaining receiving media 220 located in a second receiving area.

[0062] Specifically, in this embodiment, the laser generator emits an outgoing laser beam, and the scanning module 300 forms a two-dimensional spatial scan of the outgoing laser beam output from the optical system with co-located transmitter and receiver, and collects and sends back the laser beam scattered and reflected by the target object to the optical system. The outgoing laser beam is controlled to perform a two-dimensional scan along the X and Y directions. In this embodiment, the scanning module 300 may include a one-dimensional galvanometer and a one-dimensional rotating mirror, or it may include a two-dimensional galvanometer; the specific choice depends on the scanning requirements and is not limited here.

[0063] The transceiver module 200 in this embodiment may include a PLC chip, spaced waveguides or optical fibers, or a coherent receiving module, which may be a silicon photonics chip.

[0064] In this embodiment, the transmitting medium 210 and the receiving medium 220 can be waveguides, optical fibers, etc. When the transmitting medium 210 and / or the receiving medium 220 are waveguides, a planar lightwave circuit (PLC) or a rectangular waveguide can be used. The specific choice can be made flexibly according to the application requirements, and no single limitation is made here. In this embodiment, the receiving medium 220 is used to receive the first echo signal 400 or the second echo signal 500 transmitted by the optical system, and then coupled to the detector in the transceiver module 200 for subsequent signal processing.

[0065] The frequency-modulated continuous wave lidar provided in this embodiment of the invention employs the lidar optical system provided in the above embodiments. It uses the waveguide array integrated in the transceiver module 200 as input and output, and achieves ranging and velocity measurement via the optical system and scanning module 300 with co-located transceiver. This configuration allows the echo signal to be divided into multiple parts, which are received by receiving media 220 located in different areas. This allows the lidar to achieve a larger receiving surface by setting multiple receiving media 220, thus receiving more echo signals. This ensures that even if the walk-off effect occurs, the frequency-modulated continuous wave lidar provided in this embodiment of the invention still has good signal collection capabilities.

[0066] Furthermore, when the parameters of each light-guiding region in the lidar optical system provided in this embodiment are set reasonably, the distance between the first receiving region and the second receiving region can be adjusted to the minimum distance that two adjacent waveguides can reach. Thus, the lidar optical system provided in this embodiment can effectively reduce the adverse effects of the walk-off effect. Compared to setting a large-area waveguide array in the transceiver module 200, it can effectively reduce the number of receiving channels and the complexity of signal processing, simplifying the hardware system of the frequency-modulated continuous wave lidar provided in this embodiment, reducing its size, improving system reliability, and effectively reducing the complexity of the optomechanical system in the lidar, thus reducing the cost of unnecessary optical components. Simultaneously, the frequency-modulated continuous wave lidar provided in this embodiment, without sacrificing the performance of the laser transmitter, adds the function of collecting echo signals from the adjacent receiving medium 220, achieving better coupling efficiency at near, medium, and long distances.

[0067] In some embodiments, the transmitting medium is used only for receiving and outputting the emitted laser. In this case, the echo energy at close range needs to be carefully controlled in terms of the spot size of the transceiver module. Without walk-off, the spot should cover the adjacent receiving waveguide. Once a certain walk-off angle is achieved, the spot in other areas gradually shifts away from the adjacent receiving waveguide, while the spot in the central area gradually moves closer to the adjacent receiving waveguide, thus fulfilling the detection requirement. This scheme can further reduce hardware overhead.

[0068] Please refer to Figures 1 to 3 As shown, in some embodiments, the transmitting medium 210 is also used to receive the first echo signal 400 or at least a portion of the second echo signal 500, in which case the transmitting medium 210 is one of the receiving media 220. Specifically, when the transmitting medium 210 is used for both transmission and reception, it can be a single-mode waveguide with a different mode field, used to transmit the frequency-modulated laser signal and receive the echo signal. In this embodiment, the receiving medium 220 other than the transmitting medium 210 can be a single-mode planar waveguide, a few-mode to single-mode planar waveguide, or a multi-mode to single-mode planar waveguide with the same or different mode fields. The transmitting medium 210 can be used for both transmission and reception, which can reduce the number of waveguides in the transceiver module 200, making its structure more compact and smaller in size, while also reducing its manufacturing cost.

[0069] Since there are multiple options for the scanning module depending on the usage requirements, there are also multiple options for the arrangement of the corresponding receiving medium. Here are some examples.

[0070] In an optional embodiment, the scanning module includes a one-dimensional galvanometer and a one-dimensional rotating mirror. The one-dimensional galvanometer controls the emitted laser to scan along the Y direction, and the one-dimensional rotating mirror controls the emitted laser to scan along the X direction. The receiving medium, excluding the emitting medium, is located on the same side of the emitting medium. When the scanning module adopts the structure provided in this embodiment, the walk-off angle offset of the echo signal caused by the scanning module is unidirectional. In this case, the receiving medium, excluding the emitting medium, only needs to be placed on the same side of the emitting medium, which can effectively reduce the number of receiving media and avoid material waste.

[0071] In another optional embodiment, the scanning module includes a two-dimensional galvanometer for controlling the emitted laser to perform two-dimensional scanning along the X and Y directions. At least three receiving media are provided, with the receiving media other than the emitting medium located on both sides of the emitting medium. In this embodiment, the two-dimensional galvanometer can be a two-dimensional MEMS (Micro-Electro-Mechanical System) galvanometer.

[0072] When the scanning module adopts the structure provided in this embodiment, the walk-off angle offset of the echo signal caused by the scanning module is bidirectional. Therefore, receiving media must be placed on both sides of the transmitting medium, and one or more receiving media can be placed on either side of the transmitting medium. Simultaneously, the mode field diameter of the receiving media located on the transmitting medium side can be the same as or different from that of the transmitting medium. Furthermore, in this embodiment, the transmitting medium can be located on the principal optical axis of the optical system, and can be placed at equal or unequal intervals with other receiving media, depending on requirements. Using the solution provided in this embodiment, a large echo signal reception ratio can be ensured, thereby ensuring that the detection accuracy of the frequency-modulated continuous wave lidar meets the usage requirements.

[0073] Based on the above embodiments, to ensure the ease of use of the frequency-modulated continuous wave lidar, in one optional embodiment, the spacing between the waveguides is adjustable. Thus, during use, the user can flexibly adjust the spacing between the waveguides according to usage needs and the reception effect of the echo signal.

[0074] Please refer to Figure 4 As shown, in an optional embodiment, a transmitting medium 210 and receiving mediums 220 disposed on both sides of the transmitting medium 210 form a transceiver module, and an optical system corresponds to one or more transceiver modules.

[0075] Specifically, the same optical system can correspond to a single transceiver module or multiple transceiver modules, and their arrangement can be periodic, arbitrary, or spaced out. This allows for dynamic adjustment of the transceiver field of view and direction for each channel according to requirements.

[0076] The above description is merely a preferred embodiment of the present invention and only specifically describes the technical principles of the present invention. These descriptions are only for explaining the principles of the present invention and should not be construed as limiting the scope of protection of the present invention in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention, as well as other specific embodiments of the present invention that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of the present invention.

Claims

1. A lidar optical system, characterized in that, The system includes a lens module having a first light-guiding area and a second light-guiding area. The first light-guiding area is used to receive an emitted laser and collimate the emitted laser for output, and also to receive a first echo signal and converge the first echo signal to a first receiving area. The second light-guiding area is used to receive a second echo signal and converge the second echo signal to a second receiving area. There is a gap between the second receiving area and the first receiving area. The first echo signal is a signal located in the central region of the echo signal, and the second echo signal is a signal other than the first echo signal in the echo signal. The lens module includes a first convex lens and a second convex lens arranged sequentially along the emitted laser beam path. The principal optical axes of the first convex lens and the second convex lens are on the same straight line. The aperture of the first convex lens is smaller than that of the second convex lens. The central regions of the first and second convex lenses are used to cooperate in receiving the emitted laser and collimating the emitted laser beam. The first convex lens is also used to receive the first echo signal and converge the first echo signal to the first receiving region. The second convex lens is also used to receive the first echo signal and the second echo signal, converge the first echo signal to the first convex lens, and converge the second echo signal to the second receiving region. The central regions of the first and second convex lenses combine to form the first light guiding region, and the edge region of the second convex lens forms the second light guiding region.

2. The lidar optical system as described in claim 1, characterized in that, The second light-guiding area is arranged around the first light-guiding area.

3. The lidar optical system as described in claim 1, characterized in that, The lens module includes an annular lens, with a first convex structure formed in the central region and a second convex structure formed in the edge region. The focal length of the first convex structure is smaller than the focal length of the second convex structure. The central region of the annular lens forms the first light-guiding region, and the edge region of the annular lens forms the second light-guiding region.

4. The lidar optical system as described in claim 1, characterized in that, The lens module is a multifocal lens.

5. A frequency-modulated continuous wave lidar, characterized in that, The system includes a laser generator, a transceiver module, an optical system, and a scanning module. The optical system is the laser radar optical system according to any one of claims 1-4. The transceiver module is provided with a transmitting medium and a receiving medium. The transmitting medium is used to receive and output the emitted laser emitted by the laser generator. There are at least two receiving media, one of which is located in the first receiving area, and the remaining receiving media are located in the second receiving area.

6. The frequency-modulated continuous wave lidar as described in claim 5, characterized in that, The transmitting medium is also used to receive the first echo signal or at least a portion of the second echo signal, in which case the transmitting medium is one of the receiving media.

7. The frequency-modulated continuous wave lidar as described in claim 6, characterized in that, The scanning module includes a one-dimensional galvanometer and a one-dimensional rotating mirror. The one-dimensional galvanometer is used to control the emitted laser to scan along the Y direction, and the one-dimensional rotating mirror is used to control the emitted laser to scan along the X direction. The receiving medium, other than the emitting medium, is located on the same side of the emitting medium.

8. The frequency-modulated continuous wave lidar as described in claim 6, characterized in that, The scanning module includes a two-dimensional galvanometer, which is used to control the emitted laser to perform two-dimensional scanning along the X and Y directions. The receiving medium is provided with at least three, and the receiving medium other than the emitting medium is disposed on both sides of the emitting medium.

9. The frequency-modulated continuous wave lidar as described in any one of claims 5-8, characterized in that, A transmitting medium and a receiving medium disposed on both sides of the transmitting medium form a transceiver module, and an optical system corresponds to one or more transceiver modules.

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