Prism module, lidar optical system and frequency modulated continuous wave lidar

Abstract

This invention relates to the field of lidar technology, providing a prism module, a lidar optical system, and a frequency-modulated continuous wave lidar. The prism module has a first light-guiding region and a second light-guiding region. The first light-guiding region allows light to pass through in a first direction, while the second light-guiding region changes the propagation angle of the light, causing it to deflect towards or away from the side containing the first light-guiding region. The lidar optical system includes a lens module and the prism module provided in the above embodiments. The lens module and the prism module cooperate to collimate the output laser beam or split the echo signal into multiple beams and converge them into multiple spaced receiving regions. The prism module, lidar optical system, and frequency-modulated continuous wave lidar provided by this invention can effectively reduce the adverse effects of the walk-off effect on lidar detection accuracy.

Description

Technical Field

[0001] This invention belongs to the field of lidar technology, and particularly relates to a prism module, 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 a prism module, 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 prism module, a lidar optical system, and a frequency-modulated continuous wave lidar, which aims to mitigate energy loss caused by the walk-off effect.

[0004] The present invention is implemented as follows: In a first aspect, a prism module is provided for use in a lidar optical system. The prism module has a first light-guiding region and a second light-guiding region. The first light-guiding region is used to allow light to pass through in a first direction, and the second light-guiding region is used to change the propagation angle of the light so that the light is deflected toward a direction closer to or away from the side where the first light-guiding region is located. The first direction is the propagation direction of the light before entering the first light-guiding region, or a direction parallel to the propagation direction of the light before entering the first light-guiding region.

[0005] In an optional embodiment, the first light-guiding region is a through-hole that penetrates the prism module along the thickness direction;

[0006] Alternatively, the first light-guiding region may include two relatively parallel first planes.

[0007] In an optional embodiment, the second light-guiding region includes at least one second plane disposed at an acute or obtuse angle to the second direction;

[0008] When multiple second planes are provided on the same side of the second light guide area, the multiple second planes located on the same side of the second light guide area are connected in sequence, and the angle between the second plane and the second direction gradually decreases or increases from the side closer to the first light guide area to the side farther away from the first light guide area.

[0009] In an optional embodiment, the second light-guiding region includes two parts disposed on both sides of the first light-guiding region, each part having at least one second plane.

[0010] Secondly, a lidar optical system is provided, including a lens module and a prism module provided in the above embodiments. The lens module and the prism module are used to cooperate with each other to collimate the output of the emitted laser, or to divide the echo signal into multiple beams and converge the multiple beams into multiple receiving areas that are spaced apart.

[0011] In one optional embodiment, the lens module and the prism module are two separate devices, or the lens module and the prism module are an integrally formed structure.

[0012] Thirdly, 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, and the receiving medium is used to receive at least a portion of the echo light output from the first light-guiding region and / or the second light-guiding region.

[0013] In an optional embodiment, the transmitting medium is also used to receive signals, in which case the transmitting medium is one of the receiving media.

[0014] 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.

[0015] 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 two, with the receiving medium other than the emitting medium being disposed on both sides of the emitting medium.

[0016] In an optional embodiment, one of the transmitting media and at least one of the adjacent receiving media form a transceiver module, and one of the optical systems corresponds to one or more of the transceiver modules.

[0017] The technical advantages of the present invention compared to the prior art are as follows: The prism module, lidar optical system and frequency-modulated continuous wave lidar provided in the embodiments of the present invention have a first light guiding area and a second light guiding area, wherein the first light guiding area is used to allow light to pass through along a first direction, and the second light guiding area is used to change the propagation angle of the light propagating along the second direction, so that the light is deflected toward the side closer to or away from the first light guiding area. By using the prism module provided in this embodiment, the same echo energy before passing through the prism module can be split into multiple signals after passing through different light-guiding areas of the prism module. This allows the echo energy passing through the first light-guiding area to deviate from the central transmitting medium area after the walk-off effect occurs, and reach the receiving medium located on the side of the transmitting waveguide. At the same time, when the aforementioned echo energy does not reach the receiving medium on the side of the transmitting waveguide, the echo energy passing through other light-guiding areas can be received by the receiving medium. This can effectively reduce the risk of the echo signal falling into the gap between adjacent receiving media under the influence of the walk-off effect, thereby reducing the adverse impact of the walk-off effect on the detection accuracy of the lidar. This enables the frequency-modulated continuous wave lidar using the prism module provided in this embodiment to have good signal collection capabilities. Attached Figure Description

[0018] 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.

[0019] Figure 1 This is a schematic diagram illustrating the usage state of the prism module and the corresponding lidar optical system provided in an embodiment of the present invention. Figure 1 The arrows in the figure indicate the direction of echo signal transmission, and the echo signal in the figure does not show any walk-off angle shift;

[0020] Figure 2 yes Figure 1 The diagram shows the usage status of the prism module and the corresponding lidar optical system. Figure 2 The arrows in the figure indicate the direction of echo signal transmission, and the echo signal in the figure shows a walk-off angle shift.

[0021] Figure 3This is a schematic diagram of the usage status of a prism module and a corresponding lidar optical system provided in another embodiment of the present invention. The arrows in the figure indicate the transmission direction of the echo signal, and the echo signal in the figure does not undergo walk-off angle shift.

[0022] Figure 4 yes Figure 3 Schematic diagram of the middle prism module;

[0023] Figure 5 This is a schematic diagram of the usage status of a prism module and a corresponding lidar optical system provided in another embodiment of the present invention. The arrows in the figure indicate the transmission direction of the echo signal, and the echo signal in the figure does not undergo walk-off angle shift.

[0024] Figure 6 yes Figure 5 Schematic diagram of the middle prism module;

[0025] Figure 7 This is a cross-sectional view of the prism module used in an embodiment of the present invention.

[0026] Figure 8 This is a schematic diagram of the prism module used in another embodiment of the present invention;

[0027] Figure 9 This is a schematic diagram of the prism module used in another embodiment of the present invention;

[0028] Figure 10 This is a schematic diagram of the prism module used in another embodiment of the present invention;

[0029] Figure 11 This is a schematic diagram of the prism module used in another embodiment of the present invention;

[0030] Figure 12 This is a schematic diagram of the prism module used in another embodiment of the present invention;

[0031] Figure 13 This is a schematic diagram of the structure of a lidar optical system used in another embodiment of the present invention;

[0032] Figure 14 This is a schematic diagram of the structure of a lidar optical system used in another embodiment of the present invention;

[0033] Figure 15 This is a schematic diagram of the use of a lidar optical system according to another embodiment of the present invention, where the arrows indicate the direction of beam propagation.

[0034] Figure 16 This is a schematic diagram of the distribution structure of the transceiver module and optical system used in an embodiment of the present invention;

[0035] Figure 17 This is a schematic diagram of the distribution structure of the transceiver module and optical system used in another embodiment of the present invention.

[0036] Explanation of reference numerals in the attached figures:

[0037] 100. LiDAR optical system; 110. Prism module; 111. Through hole; 112. First plane; 113. Second plane; 120. Lens module; 200. Transceiver module; 210. Transmitting medium; 220. Receiving medium; 300. Scanning module. Detailed Implementation

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] Please refer to Figures 1 to 6 As shown, in one embodiment of the present invention, a prism module 110 is provided, applied to a lidar optical system 100. The prism module 110 has a first light-guiding region and a second light-guiding region. The first light-guiding region is used to allow light to pass through along a first direction A. The second light-guiding region is used to change the propagation angle of the light, so that the light is deflected towards the side closer to or farther from the first light-guiding region. The first direction A is the propagation direction of the light before entering the first light-guiding region, or a direction parallel to the propagation direction of the light before entering the first light-guiding region.

[0044] Specifically, the prism module 110 in this embodiment can be composed of a wedge prism, a combination of multiple wedge prisms, or other types of prisms, depending on the light output effect. The first light-guiding region in this embodiment can be a through-hole penetrating the prism module 110 along its thickness direction, a planar structure, etc., as long as it achieves the above functions; no single limitation is made here. Specifically, when the first light-guiding region is a through-hole penetrating the prism module 110 along its thickness direction, the first direction A is the propagation direction of light before it enters the first light-guiding region. When the first light-guiding region is a planar structure, the first direction A is a direction parallel to the propagation direction of light before it enters the first light-guiding region. However, when the planar structure is thin, the first direction A can be considered to be the same as the propagation direction of light before it enters the first light-guiding region. The second light-guiding region in this embodiment includes at least one inclined light-guiding surface. The inclination angle of the light-guiding surface can be set according to the light output effect requirements.

[0045] To facilitate understanding, the working principle of the prism module 110 provided in this embodiment of the invention will be explained using a lidar employing the prism module 110 as an example:

[0046] The lidar includes a laser generator, a transceiver module 200, a lens module 120, a prism module 110, and a scanning module 300 arranged sequentially. When using this lidar to detect a target, the laser generator emits an outgoing laser beam, which is transmitted through the transceiver module 200 to form an outgoing laser beam. This beam then illuminates the lens module 120, is collimated by the lens module 120, and then sequentially passes through the prism module 110 and the scanning module 300 to illuminate the target. The target then scatters and reflects the light to form an echo signal. The echo signal is then illuminated by the scanning module 300 at the location of the prism module 110. Part of the signal is illuminated by the first light guide area along a first direction A to the lens module 120, while another part of the signal changes its propagation direction through the second light guide area, either converging or diverging towards the signal output from the first light guide area. All of the above signals are then converged by the lens module 120 into the transceiver module 200, where they are received and processed by corresponding components to obtain corresponding electrical signals for subsequent processing.

[0047] In the above process, the signal passing through the first light-guiding region is generally the signal located in the central region of the echo signal, while the signal passing through the second light-guiding region is the remaining signal in the echo signal. By using the prism module 110 provided in this embodiment, the same beam of echo energy before passing through the prism module 110 can be split into multiple beams of signal after passing through different light-guiding regions of the prism module 110. This allows the echo energy passing through the first light-guiding region to deviate from the central transmitting medium region after the walk-off effect occurs, and reach the receiving medium located on the transmitting waveguide side. At the same time, when the echo energy does not reach the receiving medium (such as the receiving waveguide, optical fiber, etc.) on the transmitting waveguide side, the echo energy passing through other light-guiding regions can be received by the receiving medium. This can effectively reduce the risk of the echo signal falling into the gap between adjacent receiving media 220 under the influence of the walk-off effect, thereby reducing the adverse effect of the walk-off effect on the detection accuracy of the lidar.

[0048] The prism module 110 provided in this embodiment of the invention has a first light-guiding area and a second light-guiding area. The first light-guiding area is used to allow light to pass through in a first direction, and the second light-guiding area is used to change the propagation angle of light propagating in a second direction, so that the light deflects toward the side closer to or away from the first light-guiding area. By using the prism module 110 provided in this embodiment, the same echo energy before passing through the prism module 110 can be split into multiple signals after passing through different light-guiding areas of the prism module 110. This allows the echo energy passing through the first light-guiding area to deviate from the central transmitting medium area after the walk-off effect and reach the receiving medium located on the transmitting waveguide side. At the same time, when the echo energy does not reach the receiving medium (such as the receiving waveguide, optical fiber, etc.) on the transmitting waveguide side, the echo energy passing through other light-guiding areas can be received by the receiving medium. This can effectively reduce the risk of the echo signal falling into the gap between adjacent receiving media 220 under the influence of the walk-off effect, thereby reducing the adverse impact of the walk-off effect on the detection accuracy of the lidar. This makes the lidar using the prism module 110 provided in this embodiment have good signal collection capabilities, thereby improving the ranging capability.

[0049] Please refer to Figures 8 to 10 As shown, the prism module can take many forms, including right-angle prisms, tilted prisms, other deformed prisms, and various combinations thereof. For ease of understanding, the structure and working principle of the prism module 110 will be explained using a single wedge prism as an example: The central region of the wedge prism is a non-wedge-shaped parallel region, which can be perforated to allow light to enter directly. Alternatively, the central region of the wedge prism can be a flat glass or flat plastic structure, which ensures that the light from the transmitting waveguide can be output horizontally.

[0050] When this wedge prism is applied to the aforementioned lidar, during reception, such as Figure 1 As shown, due to the reversibility of the optical path, when there is no walk-off angle in the central region of the echo signal, the optical signal will return to the transceiver module 200 along the original path. At this time, the transceiver module 200 has no optical signal. However, the received optical signal outside the central region will generate an offset angle after passing through the wedge prism. This offset light will generate an offset distance relative to the position of the transceiver module 200 after passing through the lens group. Therefore, the echo optical signal (pre-offset optical path) can be coupled to the transceiver module 200 placed at this distance, completing the detection of the entire system in the case of no walk-off angle or a small angle at close range. Figure 2As shown, after the walk-off angle shift occurs, the echo signal will have a certain relative angle with respect to the prism module 110, resulting in a certain displacement of the light spot generated in the pre-offset optical path and the central optical path on the end face of the transceiver module 200. The prism module 110 and the optical system can ensure that the transceiver module 200 always has a light signal from the pre-offset optical path or the central optical path during the entire detection process, even under the condition of a changing walk-off angle, thereby completing the detection of the entire system.

[0051] In addition, changes in the thickness and slope of the prism module can control the position of the received light spot on the image plane; the energy ratio between the center and the pre-offset optical path can be adjusted by controlling the size of the central region of the prism module, that is, the ratio of the echo signals passing through the first and second light guiding regions, thereby rationally distributing the energy reception.

[0052] Assume the solid angle Ω subtended by the receiving system for the target object r for:

[0053]

[0054] Where d is the aperture of the optical system and D is the distance between the receiving system and the target object; it should be noted that those skilled in the art should understand that the optical system mentioned here is not the lidar optical system described in this article.

[0055] The efficiency of the receiving system is η r The intensity of the laser radiation scattered from the target object, transmitted through the atmosphere, and reaching the receiving system is I. θ Then the received laser power P r for:

[0056]

[0057] As can be seen from the formula, the echo energy is higher at close range. This can be addressed by appropriately reducing the coupling efficiency at close range and pre-setting the higher coupling efficiency at a lower echo energy location at a longer distance. That is, the initial position of the light spot in the pre-offset optical path does not need to be located in the center region of the receiving medium; it can start from the edge and gradually shift towards the center of the receiving medium in the transceiver module as the detection distance increases. Afterward, the echo energy of the optical path in the center region is also coupled by the receiving medium. It should be noted that if the transmitting medium in the transceiver module used in the above process has a receiving function, then the receiving medium can also be the transmitting medium.

[0058] Therefore, by using the prism module and lidar optical system provided in the embodiments of the present invention, the echo energy can be fully utilized by focusing the pre-offset optical path, which can reduce the transmission power to a certain extent and alleviate the negative impact of high power at the transmitting end.

[0059] The aforementioned first light-guiding region can take various forms. In one optional embodiment, please refer to... Figure 7 As shown, the first light-guiding region is a through-hole 111 that penetrates the prism module 110 along the thickness direction. The cross-sectional shape of the through-hole 111 can be circular, rectangular, or other shapes, and can be flexibly set according to the application requirements. There is no unique limitation here. The first light-guiding region adopts this structure, which is simple and easy to process. In this embodiment, the first direction A is the propagation direction of light before entering the first light-guiding region.

[0060] Please refer to Figures 8 to 10 As shown, in another optional embodiment, the first light-guiding region includes two relatively parallel first planes 112. In this case, the first light-guiding structure is a planar structure. Light passing through this region will be refracted at the two first planes 112, ultimately exiting in a direction parallel to the propagation direction of the light before entering the first light-guiding region. That is, in this embodiment, the first direction A is parallel to the propagation direction of the light before entering the first light-guiding region. It should be noted that when the distance between the two first planes 112 is small, i.e., the thickness of the prism module is thin, the first direction A in this embodiment can be considered to be the same as the propagation direction of the light before entering the first light-guiding region. This structure ensures that light can pass through along the first direction, reduces the influence of stray light from the inner wall caused by the perforation, and facilitates processing.

[0061] Please refer to Figures 7 to 12 As shown, in an optional embodiment, the second light-guiding region includes at least one second plane 113 disposed at an acute or obtuse angle to the second direction B. The second direction B here is generally the propagation direction of the emitted light, but can also be the propagation direction of the echo light when the walk-off effect does not occur. It should be understood that the acute or obtuse angle between the second plane 113 and the second direction B means that the second plane forms an acute or obtuse angle with the positive direction of the second direction B. Specifically, as shown... Figures 7 to 10 As shown, Figure 7 and Figure 8 There is only one second plane 113, which is set at an obtuse angle to the second direction B; Figure 9 There are two second planes 113. The second plane 113 on the left is set at an acute angle to the second direction B, and the second plane 113 on the right is set at an obtuse angle to the second direction B. Figure 10 There are two second planes 113, and both second planes 113 on both sides are set at acute angles to the second direction B. Specifically, when the first light guiding area includes the first plane 112, the second plane 113 is set at an obtuse angle to the first plane 112.

[0062] Please refer to Figure 11 and Figure 12As shown, when multiple second planes 113 are provided on the same side of the second light guiding region, the multiple second planes 113 located on the same side of the second light guiding region are connected in sequence, and the angle between the second plane 113 and the second direction gradually decreases or increases from the side closer to the first light guiding region to the side farther away from the first light guiding region.

[0063] Specifically, when the second planes 113 on the same side of the second light guide structure are all set at an acute angle to the second direction B, the angle between the second planes 113 and the second direction gradually decreases from the side closer to the first light guide area to the side farther away from the first light guide area; when the second planes 113 on the same side of the second light guide structure are all set at an obtuse angle to the second direction B, the angle between the second planes 113 and the second direction gradually increases from the side closer to the first light guide area to the side farther away from the first light guide area.

[0064] The second light-guiding region has two light-guiding surfaces in the light propagation direction. Each light-guiding surface can be composed of at least one plane, and at least one of these planes is set at an acute angle to the second direction. These inclined planes are the second plane 113. Furthermore, the structures of the two light-guiding surfaces can be the same or different, and they can be symmetrically or asymmetrically arranged. A single light-guiding surface can be axially symmetric or non-axially symmetric, depending on the application requirements; no single limitation is imposed here. The prism module 110 adopts the structure of this embodiment, which is simple and easy to manufacture.

[0065] Please refer to Figures 7 to 10 As shown, in an optional embodiment, the prism module 110 can be a right-angle prism or a wedge prism. In this case, the light-incident surface and the light-exit surface of the prism module 110 are both planar structures. A first plane 112 is prepared on the two oppositely arranged sides of the prism module 110 to form a first light-guiding region, and the remaining part forms a second light-guiding region. Alternatively, a through hole 111 is opened in the middle of the prism module 110 to penetrate the two oppositely arranged sides to form a first light-guiding region, and the remaining part forms a second light-guiding region.

[0066] Please refer to Figure 11 and Figure 12As shown, in another optional embodiment, the light-incident surface or light-exit surface of the prism module 110 is a non-planar structure. In this case, the second light-guiding region includes two parts disposed on both sides of the first light-guiding region, each part having at least one second plane 113. Specifically, the number of second planes 113 in each part can be the same or different, and the two parts can be symmetrical, identical, or different structures, which can be set according to the usage requirements. At the same time, when multiple second planes 113 are provided in the same part, the multiple second planes 113 are connected sequentially, and the angle between the second plane 113 and the second direction B gradually decreases or increases from the side closer to the first light-guiding region to the side farther away from the first light-guiding region. By adopting this structure, the prism module 110 can divide the echo signal into multiple beams according to the usage requirements, and design different deflection angles according to the characteristics of each beam, so that more echo signals can be received by the receiving medium 220 in the transceiver module 200, thereby ensuring that the detection accuracy of the lidar using the prism module 110 provided in this embodiment is high.

[0067] Please refer to Figure 1 , Figure 2 , Figure 3 , Figure 5 , Figure 13 , Figure 14 and Figure 15 As shown, in another embodiment of the present invention, a lidar optical system 100 is provided, including a lens module 120 and a prism module 110 provided in the above embodiments. The lens module 120 and the prism module 110 are used to cooperate with each other to collimate the output of the emitted laser, or to divide the echo signal into multiple beams and converge the multiple beams of signals to multiple receiving areas that are spaced apart.

[0068] The lens module 120 in this embodiment may include one or more convex lenses, or the lens module 120 may be composed of convex lenses, concave lenses, combined lenses, or other lenses. The specific configuration can be flexibly set according to usage requirements, and no single limitation is made here. The lens module 120 may be placed with its principal optical axis parallel to the second direction B, or it may be placed at an angle to the second direction B, i.e., the lens module 120 may be tilted. The specific choice can be flexibly made according to the light output effect requirements.

[0069] The working principle of the lidar optical system 100 provided in this embodiment of the invention is as follows:

[0070] When it is necessary to emit an outgoing laser to a target, the laser generator emits an outgoing laser, which is then irradiated by the transceiver module 200 to the lens module 120. The beam is collimated by the lens module 120 and then output. The collimated beam is then output to the scanning module 300 while maintaining the first direction through the first light guide area. The scanning module 300 changes the propagation direction to perform a two-dimensional scan of the target.

[0071] When the echo signal scattered or reflected by the target object returns to the prism module 110 via the scanning module 300, part of the signal continues to be output in the first direction via the first light guide area, and the other part is output in the first direction via the second light guide area, so that the original echo signal is divided into at least multiple beams of signal. Then, the multiple beams of signal are converged by the lens module 120 to multiple receiving areas that are spaced apart.

[0072] It should be noted that the above process only describes one optical path propagation mode. In this embodiment, the positions of the lens module 120 and the prism module 110 can be interchanged. That is, the emitted laser can pass through the prism module 110 first and then the lens module 120, and the echo signal can pass through the lens first and then the prism module 110.

[0073] In the above process, since the prism module 110 can split the echo signal into multiple beams with different propagation directions, these multiple beams can be converged by the lens module 120 to different areas of the transceiver module 200, so that they can be received by different receiving media 220 located in the corresponding areas. Specifically, when the second light-guiding area is used to deflect the received echo signal toward the side closer to the first light-guiding area, the multiple beams split by the prism module 110 can be first converged to the same point by the lens module 120, and then continue to be transmitted to multiple different receiving media 220. When the second light-guiding area is used to deflect the received echo signal toward the side farther from the first light-guiding area, the multiple beams split by the prism module 110 can be converged by the lens module 120 in a dispersed manner to multiple receiving media 220.

[0074] Furthermore, when designing the specific structure of the lidar optical system 100 provided in this embodiment of the invention, the light output effect can be changed by adjusting the parameters of each light guide surface in the prism module 110 and the lens module 120. This allows the lidar optical system 100 to adapt to different arrangements and design requirements of the transmitting medium 210 and receiving medium 220 in the transceiver module 200, making the lidar system design using the lidar optical system 100 provided in this embodiment more flexible.

[0075] The lidar optical system 100 provided in this embodiment of the invention employs the prism module 110 provided in the above embodiments, and also provides a lens module 120. This allows the echo signal received by the lidar optical system 100 to be split and focused into multiple receiving media 220 spaced apart. As a result, the lidar can achieve a larger receiving surface by setting multiple receiving media 220, so as to receive 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 capability.

[0076] Furthermore, when the parameters of each light-guiding region in the aforementioned lidar optical system 100 are set reasonably, the spacing between the convergence regions of multiple signals can be reduced to the minimum spacing achievable by two adjacent receiving media 220. Thus, the lidar optical system 100 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 also effectively reduce the number of receiving channels and signal processing complexity in the transceiver module 200. This simplifies the hardware system of the frequency-modulated continuous wave lidar using the lidar optical system 100 provided in this embodiment, reduces its size, improves its system reliability, and effectively reduces the complexity of the optomechanical system in the frequency-modulated continuous wave lidar, reducing the cost of unnecessary optical components.

[0077] In some embodiments, the lens module 120 and the prism module 110 are independently configured, i.e., they are two separate devices. This configuration facilitates manufacturing and allows for individual replacement or relocation of the lens module 120 and the prism module 110. In other embodiments, the lens module 120 and the prism module 110 are integrally formed, such as a special form where one side of a lens is a prism and the other side is a spherical or aspherical mirror, or a combination of this special form with a lens group. This structure ensures that the positional relationship between the lens module 120 and the prism module 110 remains unchanged, resulting in stable optical performance.

[0078] Please refer to Figure 1 , Figure 2 , Figure 3 and Figure 5 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 100 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, propagate, and output the emitted laser emitted by the laser generator. The receiving medium 220 is used to receive at least a portion of the echo light output from the first light-guiding region and / or the second light-guiding region.

[0079] Specifically, in this embodiment, the laser generator is used to emit outgoing laser light, and the scanning module 300 is used to form a 2D spatial scan of the outgoing laser light output from the optical system with the transmitter and receiver located in the same position, and to collect the laser light scattered and reflected by the target object and send it back to the optical system. 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 selection can be made according to the scanning needs, and there is no unique limitation here.

[0080] 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. The transmitting medium 210 and receiving medium 220 in this embodiment may 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 flexible according to the application requirements and is not limited here. The transmitting medium 210 in this embodiment may be used only for emitting laser light, or it may be used for both emitting laser light and receiving echo signals. The receiving medium 220 in this embodiment is used to receive the first echo signal or the second echo signal transmitted by the optical system, and then coupled to the detector in the transceiver module 200 for subsequent signal processing.

[0081] The frequency-modulated continuous wave lidar provided in this embodiment of the invention employs the lidar optical system 100 provided in the above embodiments. It uses the waveguide array integrated in the transceiver module 200 as input and output, and achieves lidar ranging and velocity measurement through the optical system and scanning module 300 with co-located transceiver. This setting allows the echo signal to be divided into multiple parts and received by the receiving medium 220 located in different areas or different areas of the receiving medium 220, so as to receive more echo signals and ensure 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 capability. Furthermore, when the parameters of each light-guiding region in the aforementioned lidar optical system 100 are set reasonably, the spacing between the convergence regions of multiple signals can be reduced to the minimum spacing achievable by two adjacent receiving media 220. Thus, the lidar optical system 100 provided in this embodiment can effectively reduce the adverse effects of walk-off effects, such as energy loss and decreased ranging capability. Compared to increasing the equivalent receiving surface of the entire detector through the waveguide array in the transceiver module 200, it can also effectively reduce the number of receiving channels and signal processing complexity in the transceiver module 200, 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 through the adjacent receiving medium 220 and achieves good coupling efficiency at near, medium, and long distances.

[0082] In some embodiments, the transmitting medium is used only for receiving, propagating, and outputting the emitted laser from the laser generator. In this case, the echo energy at close range needs to be carefully controlled in terms of the spot size in 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 the non-central region gradually shifts away from the adjacent receiving waveguide, while the spot in the central region gradually moves closer to the adjacent receiving waveguide, thus fulfilling the detection requirement. This scheme can further reduce hardware overhead.

[0083] Please refer to Figures 1 to 3 As shown, in some embodiments, the transmitting medium 210 is also used to receive signals, in which case the transmitting medium 210 is one of the receiving media 220. Specifically, in this embodiment, the transmitting medium 210 is 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, ensuring short-range reception.

[0084] In one optional embodiment, the transmitting waveguide is a single-mode waveguide used to transmit the laser signal generated by the laser generator (also known as a frequency-modulated light source), which is then collimated into parallel light output by the optical system. The output light is then transmitted to the target object via an external scanning module, and after reflection and scattering by the target object, it returns along the same path. The receiving waveguides located on one or both sides of the transmitting waveguide are used to couple the echo signal received by the optical system.

[0085] The frequency modulated continuous wave (FMCW) lidar provided in this embodiment is a low-cost FMCW lidar system that improves the walk-off effect. It uses a single-mode waveguide as the transmitting waveguide in the center of a planar waveguide chip, and places single-mode planar waveguides, multi-mode to single-mode planar waveguides, or multi-mode to single-mode planar waveguides with the same or different mode fields on one or both sides as receiving waveguides. Combined with the same optical system, it forms a transmit-receive co-location optical path, and then forms the entire lidar optical system scheme through a scanning module.

[0086] 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.

[0087] 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 Y 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 addition, it can effectively utilize optical energy and reduce back-end hardware resources.

[0088] In another optional embodiment, the scanning module includes a two-dimensional galvanometer, which controls the emitted laser to perform two-dimensional scanning along the Y-direction and the Y-direction. At least two receiving media are provided, with the receiving media other than the emitting medium located on opposite sides of the emitting medium. In this embodiment, the two-dimensional galvanometer can be a two-dimensional MEMS (Micro-Electro-Mechanical System) galvanometer.

[0089] 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. That is, the transmitting medium can be located at the center of the medium array composed of the transmitting and receiving media, or other arrangements can be used, which can be set according to the usage requirements. At the same time, the mode field diameter of the receiving medium located on the transmitting medium side can be the same as or different from that of the transmitting medium. In addition, the transmitting medium in this embodiment can be located on the main optical axis of the optical system as required, and can be placed at equal or unequal intervals with other receiving media. By adopting the solution provided in this embodiment, it can be ensured that the received energy always meets the minimum requirements of the system, so as to ensure that the detection accuracy of the frequency-modulated continuous wave lidar meets the usage requirements.

[0090] 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 the design process, designers can customize the spacing between the waveguides as needed.

[0091] Please refer to Figure 16 and Figure 17 As shown, in an optional embodiment, a transmitting medium 210 and at least one adjacent receiving medium 220 form a transceiver module, and an optical system corresponds to one or more transceiver modules.

[0092] 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 to meet different field-of-view requirements.

[0093] 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, It includes a lens module and a prism module, which are used to cooperate with each other to collimate the output of the emitted laser, or to split the echo signal into multiple beams and converge the multiple beams into multiple receiving areas that are spaced apart. The prism module has a first light-guiding area and a second light-guiding area. The first light-guiding area is used to allow light to pass through in a first direction, and the second light-guiding area is used to change the propagation angle of the light so that the light is deflected toward the side closer to or away from the first light-guiding area. The first direction is the propagation direction of the light before entering the first light-guiding area, or a direction parallel to the propagation direction of the light before entering the first light-guiding area. The light includes the emitted laser and the echo signal. The first light-guiding area is a through hole that penetrates the prism module along the thickness direction; Alternatively, the first light-guiding region may include two relatively parallel first planes; The second light guiding area includes at least one second plane that is set at an acute or obtuse angle to the second direction; When multiple second planes are provided on the same side of the second light guide area, the multiple second planes located on the same side of the second light guide area are connected in sequence, and the angle between the second plane and the second direction gradually decreases or increases from the side closer to the first light guide area to the side farther away from the first light guide area.

2. The lidar optical system as described in claim 1, characterized in that, The second light guiding region includes two parts located on both sides of the first light guiding region, and each part is provided with at least one second plane.

3. The lidar optical system as described in claim 1 or 2, characterized in that, The lens module and the prism module are two separate devices, or the lens module and the prism module are an integrally formed structure.

4. 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 lidar optical system according to any one of claims 1-3. 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 light from the laser generator. The receiving medium is used to receive at least a portion of the echo light output from the first light-guiding region and / or the second light-guiding region.

5. The frequency-modulated continuous wave lidar as described in claim 4, characterized in that, The transmitting medium is also used to receive signals, in which case the transmitting medium is one of the receiving media.

6. The frequency-modulated continuous wave lidar as described in claim 5, 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 Y direction. The receiving medium, other than the emitting medium, is located on the same side of the emitting medium.

7. The frequency-modulated continuous wave lidar as described in claim 5, 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 Y direction and the Y direction. There are at least two receiving media, which are disposed on both sides of the emitting medium except for the emitting medium.

8. The frequency-modulated continuous wave lidar as described in any one of claims 4-7, characterized in that, A transmitting medium and at least one adjacent receiving medium form a transceiver module, and an optical system corresponds to one or more of the transceiver modules.

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