Optical module, laser radar and terminal

Abstract

An optical module (20), a laser radar and a terminal, which are applied to the technical field of detection. The optical module (20) comprises a transmitting optical module (201), a coaxial optical module (202), a scanning module (203) and a receiving optical module (204), and during transmission, the first light beam passes through the transmitting optical module (201), the coaxial optical module (202) and the scanning module (203) in sequence and is transmitted to an object space. During receiving, the first return light beam passes through the scanning module (203) and the coaxial optical module (202) in sequence and is transmitted to the receiving optical module (204), and a first included angle exists between the first light beam passing through the coaxial optical module (202) and the first return light beam before passing through the coaxial optical module (202). Wherein a first offset exists between the position of the receiving optical module (204) and an ideal receiving light beam of the first light beam, so that the angle offset of the first return light beam is compensated, and a light spot of the first return light beam is closer to an effective receiving area of the receiving optical module (204) and even coincides with the center of the effective receiving area. Signal loss caused by a walk off angle can be reduced, the effectiveness of echoes is improved, and the detection performance is improved.

Description

Optical module, laser radar and terminal Technical Field

[0001] The present application relates to the field of detection technology, and in particular to an optical module, a laser radar and a terminal. Background Art

[0002] With the development of information technology and computer vision, detection technology has made rapid progress. A wide variety of detection devices have brought great convenience to people's lives and travel. Detection devices can be thought of as the "eyes" that perceive the environment. They include vision sensors such as cameras and radar sensors such as millimeter-wave radar, lidar, and ultrasonic radar.

[0003] Lidar (light detection and ranging) has the advantages of high resolution, good detection performance, and strong concealment, playing a vital role in the process of equipment sensing the environment. Scanning Lidar is a widely used type of Lidar, which uses a scanning method to detect objects in space.

[0004] A scanning detection device consists of a transmitter, receiver, and scanning module. Because the scanning module rotates or oscillates, the scanner generates an offset angle between the light beam projected from the scanner to the target, reflected by the target, and then irradiated by the scanner. This offset angle between the transmitted and returned light beams caused by the scanner's movement is known as the walk-off angle in the detection field. The walk-off angle prevents the returned light beam from striking the center of the receiver, resulting in a decrease in return signal strength and poor ranging performance.

[0005] Summary of the Invention

[0006] The embodiments of the present application provide an optical module, a laser radar, and a terminal, which can reduce the signal loss caused by the walk-off angle, improve the effectiveness of the received echo signal, and improve the detection performance.

[0007] In a first aspect, an embodiment of the present application provides an optical module, comprising a transmitting optical module, a coaxial optical module, a scanning module, and a receiving optical module, wherein:

[0008] The transmitting optical module is used to transmit the first light beam emitted by the light source to the coaxial optical module;

[0009] The coaxial optical module is used to transmit the first light beam to the scanning module;

[0010] The scanning module is used to scan the first light beam into the object space, and is also used to transmit the first return light beam to the coaxial optical module, where the first return light beam is a return light beam of the first light beam;

[0011] The coaxial optical module is further configured to transmit the first return light beam to the receiving optical module, wherein a first angle exists between the first light beam after entering the coaxial optical module and the first return light beam before returning to the coaxial optical module, and the first angle is greater than 0° and less than 90°;

[0012] The receiving optical module is used to receive the first return light beam;

[0013] There is a first offset between the position of the receiving optical module and the ideal receiving beam of the first light beam, and the ideal receiving beam of the first returning light beam before returning to the coaxial optical module is parallel to the first light beam.

[0014] In the embodiment of the present application, the ideal receiving light beam is a return light beam that is parallel to the first light beam. In other words, if the scanner is stationary, the return light beam of the first light beam will propagate along the optical path of the ideal receiving light beam. As the scanner continuously scans, after the first light beam is propagated to the target object in the object space, it can be reflected by the target object in the object space to obtain a first reflected light beam. Since there is a certain distance between the target object in the object space and the scanner, the scanner has already rotated a certain angle when the first return light beam passes through the scanner. Therefore, the first return light beam no longer propagates along the ideal receiving light beam, that is, there is an offset angle between the first return light beam and the ideal receiving light beam.

[0015] On this basis, the present application deviates the receiving module from the optical path of the ideal receiving beam, thereby compensating for the offset of the first return beam compared to the ideal receiving beam, and reducing the signal loss caused by the walk-off angle. It is understandable that the offset angle between the first return beam and the ideal receiving beam (parallel to the first beam) is the first angle, and the receiving optical module is also offset compared to the ideal receiving beam. Therefore, the offset of the receiving optical module compensates for the offset of the first beam, so that the light spot of the first return beam can be closer to the effective receiving area of ​​the receiving optical module, and even coincide with the center of the effective receiving area. In this way, the receiving optical module can receive the first return beam more accurately, improve the effectiveness of the received echo signal, and improve the detection performance.

[0016] The effective receiving area refers to the area where the receiving module can be used to receive the first return light beam, including but not limited to the light-transmitting surface of the microlens array, the receiving mode field of the optical fiber, or the detector of the receiver.

[0017] In another possible implementation of the first aspect, the first offset is related to the first angle.

[0018] Among them, the first angle is the angle between the return light beam and the transmitted light beam. Through this angle and the distance of the optical path between the scanner and the receiving optical module, the offset of the first return light beam in propagating to the receiving optical module can be determined, so that the compensation amount of the receiving optical module can be designed, so that the receiving optical module can receive the first return light beam more accurately, thereby improving the effectiveness of the received echo signal and improving the detection performance.

[0019] In another possible implementation of the first aspect, the coaxial optical module includes a splitter module and a beam expansion module, and the splitter module is disposed between the emitting optical module and the beam expansion module.

[0020] Exemplarily, the "between" here refers to the middle of the optical path, that is, the first light beam is transmitted through the spectrometer module and the beam expander module to the scanning module, and the first return light beam is transmitted through the beam expander module and the spectrometer module to the receiving module.

[0021] Among them, the optical splitter module refers to an optical device that divides a light beam into multiple paths. For example, the optical splitter module may include a polarization beam splitter (PBS), a semi-transparent and semi-reflective beam splitter, or a combination of one or more thereof. In some scenarios, the optical splitter module may also include other modules for assisting in achieving optical splitting or improving optical splitting efficiency and beam quality. For example, the optical splitter module may also include one or more of a wave plate (such as a quarter wave plate, a half wave plate, or an eighth wave plate, etc.), an anti-reflection film, or a filter. Exemplarily, the optical splitter module may include a PBS and a quarter-wave plate (QWP). The first light beam passes through the PBS and the quarter wave plate in sequence, and the first return light beam passes through the quarter wave plate and the PBS in sequence. Since the quarter wave plate can change the polarization state, and the PBS can transmit or reflect the passing light beam according to the polarization state, the optical paths of the first light beam and the first return light beam can be separated to achieve coaxial transmission and reception.

[0022] A beam expansion module is a module used to increase or decrease the diameter of a beam. For example, the beam expansion module can be a telescope beam expansion module, which achieves beam expansion / contraction by setting at least two groups of lenses.

[0023] In this embodiment, the beam expansion module is positioned at the rear end. During transmission, the light beam is split and then expanded. Therefore, the diameter of the first light beam is relatively small when it passes through the beam splitting module. After expansion, the diameter of the beam increases, resulting in a larger light spot in the object space and improving detection efficiency. During reception, the diameter of the returning light beam decreases after passing through the beam expansion unit, making it easier for the light receiving unit to receive it, thereby improving the effectiveness of the received signal. Furthermore, because the path of a thin light beam is more controllable than that of a thicker beam, it can easily solve the technical problem of off-axis transmission and reception.

[0024] In addition, in this case, the transmitting beam and the receiving beam can share the same set of beam expansion lenses, which improves the integration of the device and reduces the size of the module.

[0025] In another possible implementation of the first aspect, the receiving optical module includes a first microlens array, and the first microlens array is used to receive the first return light beam after passing through the light splitting module;

[0026] There is a third angle between the optical axis of the first microlens array and the ideal received light beam, and the third angle is less than or equal to the second angle and greater than or equal to one half of the second angle;

[0027] The second angle is related to the maximum offset angle and the beam expansion factor of the beam expansion module, and the maximum offset angle is related to the farthest detection distance of the optical module and the scanning speed of the scanning module.

[0028] Optionally, the beam expansion factor of the beam expansion module can also be replaced by the focal length of the lens in the beam expansion module. Optionally, the first microlens array can be used to converge the first return light beam, so that the receiver can receive the first return light beam more accurately.

[0029] In the above embodiment, when the first microlens array is placed, its optical axis is angularly offset from the optical path of the ideal received light beam, thereby compensating for the angular offset of the first return light beam, improving the effectiveness of the received echo signal, and enhancing the detection performance.

[0030] Among them, the third angle θ can fall within the following range, λ max is the second angle, and the second angle and the maximum offset angle (expressed as ), the magnification of the beam expander module. The magnification of the beam expander module can also be replaced by the focal length of the two lens groups in the beam expander module.

[0031] In some scenarios, since there are many possible distances between the target object in the object space and the optical module, the offset angle (i.e., the first angle) between the first return light beam and the ideal receiving light beam will change as the distance between the target object and the optical module changes. The maximum offset angle is the maximum value of the first angle, that is, the maximum offset angle is the angle between the first return light beam (referred to as the maximum offset light beam) formed by the first light beam reflected by the target object at the farthest detection distance and the ideal receiving light beam. In other words, the maximum offset angle is the angle between the maximum offset light beam and the static receiving light beam, and the maximum offset light beam is the light beam formed by the first light beam reflected by the target object at the farthest detection distance of the optical module. Among them, the farthest detection distance can be the farthest detection distance of the optical module, that is, the farthest detection distance of the detection device where the optical module is located, which can be predefined or pre-designed.

[0032] For example, the second angle may satisfy the following formula: Furthermore, the magnification factor = D2 / D1, where D2 is the diameter of the first light beam after passing through the beam expansion module, and D1 is the diameter of the first light beam before passing through the beam expansion module.

[0033] Optionally, the maximum offset angle is related to the maximum detection distance and the scanning speed of the scanning module. The following formula can be satisfied: Where v is the angular velocity of the scanner, c is the speed of light, and D is the maximum detection distance. k is a coefficient used to convert mechanical angle to optical angle due to the correlation between mechanical angle and optical angle. For example, if the optical angle is twice the mechanical angle, and the light beam passes through the scanner twice, k can be 4, that is:

[0034] In another possible implementation of the first aspect, the beam expansion module includes two groups of lenses, the two groups of lenses have different focal lengths, and the focal length of the lens close to the object space is larger than the focal length of the lens far from the object space.

[0035] In another possible implementation of the first aspect, the beam expansion module includes a second microlens array and a collimation lens (CL), wherein the second microlens array and the collimation lens have a common first focal plane. Optionally, the second microlens array is disposed between the beam splitting module and the collimation lens.

[0036] Furthermore, the focal length of the second microlens array is smaller than the focal length of the collimator. Optionally, the magnification of the beam expander module is related to the focal length of the second microlens array and the focal length of the collimator.

[0037] For example, Wherein, D2 is the diameter of the light beam after passing through the beam expansion module, D1 is the diameter of the light beam before passing through the beam expansion module, fc is the focal length of the collimator, and f2 is the focal length of the second microlens array.

[0038] In some scenarios, the aforementioned second angle and the maximum offset angle The focal length of the second microlens array is related to the focal length of the collimator. For example, the second angle can satisfy the following formula:

[0039] In this way, by expanding the beam through the front and rear groups of lenses (or called a telescope beam expansion module), the process tolerance of the optical module to achieve coaxial transmission and reception is increased, and the feasibility is better.

[0040] In another possible embodiment of the first aspect, the first offset distance between the first microlens array and the ideal received light beam is related to the third angle, the distance between the first microlens array and the spectrometer module, the distance between the spectrometer module and the beam expansion module, and the second offset of the light spot of the first return light beam on the first focal plane.

[0041] Optionally, the second offset is the distance between the light spot of the first return light beam and the light spot of the ideal receiving light beam of the first return light beam on the first focal plane when the first angle is the maximum offset angle.

[0042] Exemplarily, the second offset is related to the third angle and the focal lengths of the two lens groups in the beam expansion module. For example, the second offset Δy satisfies the following equation:

[0043] Wherein, fc is the focal length of the collimating lens, f2 is the focal length of the second microlens array, and θ is the third angle.

[0044] Exemplarily, the first offset distance Δx satisfies the following formula: Δx=|(d1+d2)*tanθ-Δy|

[0045] Wherein, d1 is the distance between the first microlens array and the light splitting module, d2 is the distance between the light splitting module and the beam expansion module (or the second microlens array), θ is the third angle, and Δy is the second offset.

[0046] In another possible implementation of the first aspect, the receiving optical module further includes a receiving optical element, and the receiving optical element is used to receive the first return light beam passing through the first microlens array.

[0047] Optionally, the distance between the receiving optical element and the ideal receiving light beam is a second offset distance, and the second offset distance is related to the third angle, the distance between the first microlens array and the spectrometer module, the distance between the spectrometer module and the beam expansion module, the focal length of the second microlens array, the focal length of the collimating lens, and the third offset of the light spot of the first return light beam on the first focal plane.

[0048] The third offset is the distance between the spot of the first return beam on the first focal plane and the spot of the maximum offset beam on the focal plane, and the maximum offset beam is the first return beam when the first angle is the maximum offset angle.

[0049] Exemplarily, the third offset and the maximum offset angle The focal length f2 of the second microlens array, the focal length fc of the collimating lens, and the third angle θ are related. For example, the third offset (Δy′) satisfies the following equation:

[0050] Exemplarily, the second offset distance (Δx′) satisfies the following formula:

[0051] In another possible implementation of the first aspect, a clear aperture of the first microlens array is related to at least one of the first offset distance and the second offset distance and a diameter of the first light beam before passing through the beam expansion unit.

[0052] Exemplarily, the clear aperture w3 of the first microlens array satisfies the following formula: w3≥2*max(Δx,Δx′)+D1

[0053] Wherein, max() represents the maximum value, D1 is the beam diameter of the first light beam before passing through the beam expansion module or the beam diameter of the first return light beam after passing through the beam expansion module, and the other parameters are as mentioned above.

[0054] In another possible implementation of the first aspect, the period p of the first microlens array is related to a transition zone of the first microlenses, a first offset distance, a second offset distance, and a beam diameter of the first light beam before passing through the beam expansion module. The beam diameter of the first light beam before passing through the beam expansion module can be replaced by the beam diameter of the first return light beam after passing through the beam expansion module.

[0055] Exemplarily, the period p of the first microlens array satisfies the following formula: p=w3+δ w3≥2*max(Δx, Δx′)+D1

[0056] Wherein, δ is the transition zone of the first microlens array, and the parameters are as mentioned above.

[0057] In another possible implementation of the first aspect, the emission optical module includes a waveguide or an optical fiber.

[0058] In another possible implementation of the first aspect, the receiving optical module includes a waveguide or an optical fiber.

[0059] In another possible implementation of the first aspect, the transmitting optical module, the receiving optical module, and the spectroscopic module are packaged on a glass base to form a first optical assembly, and a light-transmitting window of the first optical assembly is aligned with a light-transmitting surface of the beam expansion unit.

[0060] In another possible implementation of the first aspect, the transmitting optical module, the receiving optical module, the splitting module and the second microlens array are packaged on a glass base to form a second optical assembly, and the light-transmitting window of the second optical assembly is aligned with the light-transmitting surface of the collimating lens.

[0061] In another possible implementation of the first aspect, the coaxial optical module includes a polarization beam splitter (PBS) and a quarter-wave plate.

[0062] In a second aspect, an embodiment of the present application provides a laser radar, which includes the optical module described in any one of the first aspects.

[0063] In a possible implementation of the second aspect, the laser radar further includes a light source, for example, a laser.

[0064] In another possible implementation of the second aspect, the laser radar further includes a detector configured to obtain an electrical signal based on the light beam.

[0065] In a third aspect, an embodiment of the present application provides a terminal, which includes the optical module described in any one of the first aspects, or the terminal includes the laser radar described in any one of the second aspects.

[0066] Optionally, the terminal can be an intelligent terminal or transportation tool such as a vehicle, a drone, or a robot. Of course, the terminal can also be replaced by industrial equipment, entertainment and leisure equipment, etc. Intelligent terminals include mobile phones, tablet computers, laptops, smart bracelets, smart watches, or smart glasses. Transportation tools include vehicles, ships, aircraft, or logistics robots. Industrial equipment includes industrial robots and robotic arms. Leisure and entertainment equipment includes virtual reality (VR) equipment, mixed reality (MR) equipment, massage chairs, or 4D cinema cabins. This application does not impose strict restrictions on the devices to which the electrical connector can be applied. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The following is a brief introduction to the drawings used in describing the embodiments.

[0068] FIG1 is a schematic diagram of a detection process;

[0069] FIG2 is a schematic structural diagram of an optical module provided in an embodiment of the present application;

[0070] FIG3 is a schematic structural diagram of another optical module provided in an embodiment of the present application;

[0071] FIG4 is a schematic structural diagram of another optical module provided in an embodiment of the present application;

[0072] FIG5 is a schematic structural diagram of another transmitting module provided in an embodiment of the present application;

[0073] FIG6A is a schematic structural diagram of another optical module provided in an embodiment of the present application;

[0074] FIG6B is a schematic diagram of an optical path of an optical module provided in an embodiment of the present application;

[0075] FIG6C is a schematic diagram of parameters of an optical module provided in an embodiment of the present application;

[0076] FIG7 is a schematic diagram of a possible simulation result provided by an embodiment of the present application;

[0077] FIG8 is a schematic diagram of a possible simulation result provided by an embodiment of the present application;

[0078] FIG9 is a schematic diagram of the structure and optical path of another optical module provided in an embodiment of the present application;

[0079] FIG10 is a schematic structural diagram of another optical module provided in an embodiment of the present application;

[0080] FIG11 is a schematic structural diagram of an optical module provided in an embodiment of the present application. DETAILED DESCRIPTION

[0081] The embodiments of the present application will be described below with reference to the accompanying drawings.

[0082] A scanning detection device uses a scanning mechanism to scan the object space, thereby detecting the entire field of view. Scanning detection devices typically project transmitted signals into the object space at multiple angles through the movement of the scanning mechanism (e.g., swinging or rotating), so the scanning mechanism is constantly active. When the lidar is operating, the high-speed rotation (or swinging) of the scanning mechanism causes a deviation angle between the time the light beam is emitted, hits the target, and then reflects back.

[0083] Figure 1 illustrates the detection process. The scanning mechanism is constantly moving, creating an offset angle between the transmitted light beam (indicated by the solid arrow) and the return light beam (indicated by the dashed arrow), known as the walk-off angle. The magnitude of the walk-off angle is directly related to the angular velocity of the scanning mechanism and the beam's flight time in object space. The longer the beam's flight time and the faster the scanning mechanism's angular velocity, the larger the walk-off angle. This offset angle causes the beam to shift at the receiving position, preventing the return beam from striking the center of the receiver. This reduces the signal strength of the received return beam, lowering the signal-to-noise ratio and affecting the measured distance.

[0084] Especially for detection devices that incorporate optical fibers, waveguides, and other components, the walkoff angle of the return beam can cause it to deviate from the receiving mode field, significantly reducing the return beam's signal and impacting detection performance. For example, for a detection device using single-mode fiber (SMF) for both transmission and reception, the return beam's offset distance at the receiving end is Δx = f*tanγ, where f is the focal length of the receiving lens and γ is the walkoff angle. At a 150m detection distance and a scanning speed of 3000 revolutions per minute (r / min), γ is approximately 0.036°. For automotive LiDAR, f is typically in the tens to hundreds of millimeters (mm) due to transmission angle and receiving aperture requirements. This results in Δx ranging from a few to tens of microns. The SMF mode spot is typically around 10 microns. Therefore, the return beam's offset at the receiving end is very likely to exceed the SMF mode spot, significantly reducing the return beam's signal strength and significantly impacting detection performance.

[0085] In view of this, the embodiments of the present application provide an optical module, a laser radar and a terminal, which can reduce the signal loss caused by the walk-off angle, improve the effectiveness of the received echo signal, and improve the detection performance.

[0086] Please refer to Figure 2, which is a schematic diagram of the structure of an optical module provided in an embodiment of the present application. The optical module 20 includes a transmitting optical module 201, a coaxial optical module 202, a scanning module 203 and a receiving optical module 204. Among them:

[0087] The emitting optical module 201 is used to transmit the first light beam emitted by the light source (as shown in the solid line with an arrow in FIG2 ) to the coaxial optical module 202. The emitting optical module 201 may include a lens, an optical fiber, a waveguide, etc. The light source may be a laser, such as a laser diode (LD), a vertical cavity surface emitting laser (VCSEL), a distributed feedback laser diode (DFB-LD), a distributed Bragg reflection laser diode (DBR-LD), a grating coupled sampling reflection laser diode (GCSR-LD), a micro opto electro mechanical system laser diode (MOEMS-LD), and other light-emitting devices. The first light beam may be, for example, a frequency modulated continuous wave (FMCW) beam, and its waveform may be a sawtooth, triangular, or sinusoidal wave.

[0088] The coaxial optical module 202 is used to transmit the first light beam to the scanning module 203. The coaxial optical module 202 is used to achieve coaxial transmission and reception. In some scenarios, coaxial transmission and reception can be understood as the transmitted light beam and the received light beam passing through some optical components together, for example, the transmitted light beam and the received light beam pass through the scanning module 203 and the coaxial optical module 202 together. In other scenarios, coaxial transmission and reception can be understood as the main optical axis of the transmitted light beam and the main optical axis of the returned light beam are parallel. Of course, the parallelism here refers to the ideal situation (such as when the activity of the scanner is not considered). For example, the coaxial optical module 202 can include lenses, beam splitters, wave plates, etc.

[0089] Scanning module 203 is used to scan the first light beam into the object space. That is, scanning module 203 can swing or rotate to project the light beam into the object space at different angles. Scanning module 203 is also used to transmit a first return light beam (as shown by the dotted arrow line in Figure 2) to the coaxial optical module. The first return light beam is the return light beam of the first light beam. Exemplarily, the first light beam propagates to a target object in the object space and is reflected by the target object to form a reflection signal. The first return light beam includes the reflection signal of the first light beam.

[0090] There is a first angle γ between the first light beam after entering the coaxial optical module 202 and the first returning light beam before returning to the coaxial optical module 202. The first angle is the walkoff angle. Optionally, the first angle is greater than 0° and less than 90°, that is, 0°<γ<90°.

[0091] Coaxial optical module 202 is also configured to transmit the first return beam to receiving optical module 204. Exemplarily, coaxial optical module 202 includes a polarization beam splitter (PBS) and a quarter-wave plate (QWP). The first beam passes through the PBS and reaches the QWP. After passing through the QWP, the polarization state of the first return beam changes, causing it to be reflected by the PBS and propagated to receiving optical module 204.

[0092] In the embodiment of the present application, the position of the receiving optical module 204 is offset from the ideal receiving beam of the first light beam (see the dashed line without an arrow in FIG2 ). The ideal receiving beam of the first return light beam before returning to the coaxial optical module 202 is parallel to the first light beam. That is, the ideal receiving beam is a beam whose principal optical axis is parallel to the first light beam. When the walkoff angle is 0°, for example, when the scanner is stationary (or not rotating), the return light beam corresponding to the first light beam propagates along the optical path of the ideal receiving beam.

[0093] In other words, if the walkoff angle is 0°, the return beam of the first light beam will propagate along the optical path of the ideal receiving beam. However, since the scanner is constantly moving, after the first light beam is propagated to the target object in the object space and reflected by the target object in the object space to obtain the first reflected light beam, since there is a certain distance between the target in the object space and the scanner, when the first return light beam passes through the scanner, the scanner has already rotated a certain angle. Therefore, the first return light beam no longer propagates along the ideal receiving light beam, that is, there is an offset angle between the first return light beam and the ideal receiving light beam. On this basis, the present application deviates the receiving module from the optical path of the ideal receiving light beam, so as to compensate for the offset of the first return light beam compared to the ideal receiving light beam, and reduce the signal loss caused by the walk off angle. As shown in Figure 1, the receiving point of the ideal receiving light beam (that is, the translation position point of the receiving optical module 204) is described by a black solid semicircle, and the receiving optical module 204 is offset from the receiving point of the ideal receiving light beam.

[0094] Understandably, the first return beam is offset from the ideal receiving beam (parallel to the first beam) by a first angle, and the receiving optical module is also offset from the ideal receiving beam. Therefore, the offset of the receiving optical module compensates for the offset of the first beam, allowing the light spot of the first return beam to be closer to or coincide with the center of the receiving optical module. In this way, the receiving optical module can more accurately receive the first return beam, improving the validity of the received echo signal and enhancing detection performance.

[0095] In another possible implementation of the first aspect, the first offset is related to a first angle. The first angle is a walkoff angle between the return beam and the transmitted beam. This angle and the distance of the optical path between the scanner and the receiving optical module can be used to determine an offset of the return beam as it propagates to the receiving optical module. This allows for designing a compensation amount for the receiving optical module, enabling the receiving optical module to more accurately receive the first return beam, thereby improving the validity of the received echo signal and enhancing detection performance.

[0096] For example, the maximum value of the first angle can be the angle between the light beam returned from the farthest detection distance and the emitted light beam (such as the first light beam), which is called the maximum deviation angle for the convenience of description and is expressed as Please refer to FIG3, which is a structural diagram of another optical module provided by an embodiment of the present application. When the offset between the returned light beam and the ideal received light beam at the receiving point (i.e., the translation position of the receiving optical module) is x, the offset between the receiving optical module 204 and the receiving point of the ideal received light beam can be between x / 2 and x. As shown in FIG3 , the offset between the receiving optical module 204 and the receiving point of the ideal received light beam can be x / 2. In this case, if the offset angle between the first returned light beam and the ideal received light beam is relatively large, it is actually closer to the center of the optical axis of the receiving optical module, which is beneficial for improving the ranging accuracy during long-distance detection.

[0097] Alternatively, the offset between the receiving optical module 204 and the receiving point of the ideal receiving light beam may be between 0 and x / 2, so as to ensure the ranging accuracy during close-range detection.

[0098] Furthermore, the maximum offset angle is related to the maximum detection distance and the angular velocity of the scanning module 203. For example, the maximum offset angle The following formula can be satisfied: Where v is the angular velocity of the scanner, c is the speed of light, and D is the maximum detection distance. k is a coefficient used to convert mechanical angle to optical angle due to the correlation between mechanical angle and optical angle. For example, if the optical angle is twice the mechanical angle, and the light beam passes through the scanner twice, k can be 4, that is: The maximum detection distance may be predefined (or specified) or pre-set by a manufacturer, a standard organization, a user, or a device.

[0099] In a possible implementation, the coaxial optical module includes a light splitting module and a beam expanding module, and the light splitting module is arranged between the transmitting optical module and the beam expanding module.

[0100] Among them, the beam expansion module refers to a module used to increase or reduce the diameter of the light beam. The spectrometer module refers to an optical device that divides the light beam into multiple paths. For example, the spectrometer module may include a polarization beam splitter (PBS) and a combination of one or more of a semi-transparent and semi-reflective spectrometer. In some scenarios, the spectrometer module may also include other modules for assisting in achieving spectrometry or improving spectrometry efficiency and beam quality. For example, the spectrometer module may also include one or more of a wave plate, an anti-reflection film, or a filter. Exemplarily, the spectrometer module may include a PBS and a quarter-wave plate. The first light beam passes through the PBS and the quarter-wave plate in sequence, and the first return light beam passes through the quarter-wave plate and the PBS in sequence. Since the quarter-wave plate can change the polarization state, and the PBS can transmit or reflect the passing light beam according to the polarization state, the optical paths of the first light beam and the first return light beam can be separated to achieve coaxial transmission and reception.

[0101] Please refer to Figure 4, which is a schematic diagram of the structure of another optical module provided in an embodiment of the present application. The coaxial optical module 202 includes a beam splitter module 2021 and a beam expander module 2022. The beam splitter module 2021 is arranged between the transmitting optical module 201 and the beam expander module 2022. It can be seen that the "between" here refers to the middle of the optical path, that is, the first light beam propagates through the beam splitter module 2021 and the beam expander module 2022 to the scanning module 203, and the first return light beam propagates through the beam expander module 2022 and the beam splitter module 2021 to the receiving optical module 204.

[0102] In this embodiment, the beam expansion module 2022 is arranged at the rear end. During transmission, the light beam is split and then expanded. Therefore, the diameter of the first light beam is relatively small when it passes through the splitting module. After expansion, the diameter of the light beam becomes larger, making the light spot propagated to the object space larger, thereby improving the detection efficiency. During reception, the diameter of the returning light beam is reduced after passing through the beam expansion unit, making it easier to be received by the light receiving unit, thereby improving the effectiveness of the received signal. Moreover, since the path of a thin light beam is more controllable than that of a thick light beam, it is easy to solve the technical problem of off-axis at the transmitting and receiving ends. In addition, in this case, the transmitting light beam and the receiving light beam can share the same beam expansion system, thereby improving the integration of the device and reducing the volume of the module.

[0103] Because the beam expansion module expands (or converges) the light beam, the angle between the first return beam and the ideal received beam after passing through the beam expansion module may change. Referring to FIG. 4 , the angle between the first return beam after passing through the beam expansion module 2022 and the ideal received beam can be represented as λ. Optionally, the angle λ is greater than 0° and less than 90°, i.e., 0° < λ < 90°.

[0104] Optionally, λ is related to the first angle and the magnification of the beam expansion module 2022. For example, λ satisfies the following formula: In some scenarios, the magnification is related to the diameter of the beam before and after expansion, for example: D2 is the diameter of the emitted light beam (such as the first light beam) after passing through the beam expansion module 2022 , and D1 is the diameter of the emitted light beam before passing through the beam expansion module 2022 .

[0105] In some scenarios, the beam expansion module may include two sets of lenses. The two sets of lenses are placed front and back along the optical path of the first light beam and are connected by a focal plane, where the focal plane can be a real focal plane or a virtual focal plane. In this case, the magnification of the beam expansion module is related to the focal length of the two lenses (described below). In this case, the relationship between λ and the first angle and the magnification of the beam expansion module 2022 can also be replaced by: λ is related to the first angle and the focal length of the two lenses.

[0106] In a possible implementation, the receiving optical module 204 includes a lens, and the lens is used to receive the first return light beam after passing through the light splitting module.

[0107] Exemplarily, the lens can be a microlens array (MLA), which is conveniently distinguished as a first microlens array, denoted as MLA1. Please refer to Figure 5, which is a schematic diagram of another transmitting module provided in an embodiment of the present application. The receiving optical module 204 includes a first microlens array 2041 and a receiving optical element 2042. There is a third angle θ between the optical axis of the first microlens array 2041 (i.e., the optical axis shown in Figure 5) and the ideal received light beam, and the third angle θ is less than or equal to the second angle and greater than or equal to half of the second angle.

[0108] The second angle is the angle between the return beam at the maximum deviation angle after passing through the beam expansion module and the static receiving beam. In other words, the angle between the return beam obtained by reflecting the first beam from the farthest detection distance and the static receiving beam after passing through the scanning module and the beam expansion module is the second angle. In other words, the second angle is the maximum value of λ, which is conveniently expressed as λ max .

[0109] Accordingly, the third angle θ can fall within the following range: λ max is the second angle, and the second angle and the maximum offset angle (expressed as ), the focal length of the collimating lens is related to the focal length of the second microlens array.

[0110] In some scenarios, since there are many possible distances between the target object in the object space and the optical module, the offset angle (i.e., the first angle) between the first return light beam and the ideal receiving light beam will change as the distance between the target object and the optical module changes. The maximum offset angle is the maximum value of the first angle, that is, the maximum offset angle is the angle between the first return light beam (referred to as the maximum offset light beam) formed by the first light beam reflected by the target object at the farthest detection distance and the ideal receiving light beam. In other words, the maximum offset angle is the angle between the maximum offset light beam and the static receiving light beam, and the maximum offset light beam is the light beam formed by the first light beam reflected by the target object at the farthest detection distance of the optical module. Among them, the farthest detection distance can be the farthest detection distance of the optical module, that is, the farthest detection distance of the detection device where the optical module is located, which can be predefined or pre-designed.

[0111] For example, the second angle may satisfy the following formula: Furthermore, the magnification factor = D2 / D1, where D2 is the diameter of the first light beam after passing through the beam expansion module, and D1 is the diameter of the first light beam before passing through the beam expansion module.

[0112] As mentioned above, the beam expansion module can include two sets of lenses. In one possible embodiment, the beam expansion module includes a lens and a collimator. For example, the lens can be a microlens array, which is referred to as the second microlens array for easy distinction.

[0113] Please refer to Figure 6A, which is a structural schematic diagram of another optical module provided in an embodiment of the present application. The optical module 20 includes an emitting optical module, a polarization beam splitter PBS, a quarter-wave plate QWP, a second microlens array MLA2, a collimator, a scanning module, and a first microlens array MLA1. Among them, PBS and QWP are an exemplary spectroscopic module, and MLA22 and the collimator are an exemplary beam expansion module. MLA1 is included in the receiving optical module. MLA2 is arranged between the spectroscopic module and the collimator. In combination with Figure 6A, MLA2 can be specifically arranged between the QWP and the collimator. Optionally, a lens is also provided between the emitting module and the beam splitting module, such as a microlens array, such as MLA3 shown in Figure 6A.

[0114] Please refer to Figure 6B, which is a schematic diagram of the optical path of an optical module provided in an embodiment of the present application. Taking the second microlens array MLA2 as an example, MLA2 and the collimator have a common focal plane P1 (which can be a continuous focal plane or a real focal plane). Furthermore, the focal length of MLA2 is less than the focal length of the collimator. Optionally, the magnification of the beam expander module is related to the focal length of the second microlens array and the focal length of the collimator.

[0115] See Figure 6C, which is a parameter diagram of an optical module provided in an embodiment of the present application. The structure and optical path of the optical module can be seen in Figures 6A and 6B, respectively. The focal length of MLA2 is represented as f2, the focal length of the collimator is fc, the diameter of the first light beam before passing through MLA2 (and / or after MLA3) is D1, and the width of the output light beam from the collimator is D2. The distance from the center of the PBS to MLA1 is represented as d1, the distance from the center of the PBS to MLA2 is represented as d2, and the offset distance between the transmitted and received signals on the P1 plane is represented as Δy.

[0116] As shown in FIG6C , D2 is the diameter of the light beam after passing through the beam expansion module, D1 is the diameter of the light beam before passing through the beam expansion module, fc is the focal length of the collimator, and f2 is the focal length of MLA2. Indicates the magnification of the beam expander module. Combined with Figure 6C, it is not difficult to see that: tanγ*fc=tanλ*f2,

[0117] In addition, In the case of max The following formula can be satisfied:

[0118] As a possible implementation, the distance between the first microlens array in the receiving module and the ideal received light beam may be referred to as a first offset distance.

[0119] Optionally, the first offset distance satisfies the following conditions: when the offset angle between the first return light beam after passing through the splitter module and the ideal receiving light beam after passing through the splitter module is a third angle θ, the center of the light spot of the first return light beam coincides with the center of the first microlens array, or the optical axis of the first return light beam is consistent with the optical axis of the first microlens.

[0120] As a possible implementation, the first offset distance between the first microlens array and the ideal received light beam is related to the third angle, the distance between the first microlens array and the spectrometer module, the distance between the spectrometer module and the beam expansion module, and the second offset of the light spot of the first return light beam on the first focal plane.

[0121] Optionally, the second offset is the distance between the light spot of the first return light beam and the light spot of the ideal receiving light beam of the first return light beam on the first focal plane when the first angle is the maximum offset angle.

[0122] Exemplarily, the second offset is related to the third angle and the focal lengths of the two lens groups in the beam expansion module.

[0123] For example, the second offset Δy satisfies the following equation:

[0124] Wherein, fc is the focal length of the collimating lens, f2 is the focal length of the second microlens array, and θ is the third angle.

[0125] Exemplarily, the first offset distance Δx satisfies the following formula: Δx=|(d1+d2)*tanθ-Δy|

[0126] Wherein, d1 is the distance between the first microlens array and the light splitting module, d2 is the distance between the light splitting module and the beam expansion module (or the second microlens array), θ is the third angle, and Δy is the second offset.

[0127] In a possible implementation, the receiving optical module further includes a receiving optical element, and the receiving optical element is used to receive the first return light beam passing through the first microlens array.

[0128] When the detection distance is 0 to D, the walk-off angle (i.e., γ angle) is 0 to Since the offset angle of the optical axis of MLA3 is θ relative to the ideal receiving beam, when the detection distance is 0 to D, the angular offset of the first return beam after passing through MLA3 relative to the ideal receiving beam is respectively

[0129] In one possible implementation, the distance between the receiving optical element and the ideal received light beam is a second offset distance, and the second offset distance is related to the third angle, the distance between the first microlens array and the beam splitting module, the distance between the beam splitting module and the beam expanding module, the focal length of the second microlens array, the focal length of the collimator, and the third offset of the light spot of the first return light beam on the first focal plane. The third offset is the distance between the light spot of the first return light beam on the first focal plane and the light spot of the maximum offset light beam on the focal plane. The maximum offset light beam is the first return light beam when the first angle is the maximum offset angle.

[0130] Exemplarily, the third offset and the maximum offset angle The focal length f2 of the second microlens array, the focal length fc of the collimating lens, and the third angle θ are related.

[0131] For example, the third offset (Δy′) satisfies the following equation:

[0132] Exemplarily, the second offset distance (Δx′) satisfies the following formula:

[0133] The explanation of each parameter can be found above.

[0134] In a possible implementation, the clear aperture of the first microlens array is related to at least one of the first offset distance and the second offset distance and a diameter of the first light beam before passing through the beam expansion unit.

[0135] Exemplarily, the clear aperture w3 of the first microlens array satisfies the following formula: w3≥2*max(Δx,Δx′)+D1

[0136] Wherein, max() represents the maximum value, D1 is the beam diameter of the first light beam before passing through the beam expansion module or the beam diameter of the first return light beam after passing through the beam expansion module, and the other parameters are as mentioned above.

[0137] In one possible implementation, the period p of the first microlens array is related to the transition zone of the first microlenses, the first offset distance, the second offset distance, and the beam diameter of the first light beam before passing through the beam expansion module. The beam diameter of the first light beam before passing through the beam expansion module can be replaced by the beam diameter of the first return light beam after passing through the beam expansion module.

[0138] Exemplarily, the period p of the first microlens array satisfies the following formula: p=w3+δ w3≥2*max(Δx, Δx′)+D1

[0139] Wherein, δ is the transition zone of the first microlens array, and the parameters are as mentioned above.

[0140] For ease of understanding, two combinations of parameters of the optical module are described below as examples.

[0141] As another possible example, combined with the installation order of each component in Figure 6B, the parameters of each component are as follows: the focal lengths of MLA2 and MLA3 are f1, f2, and f3, respectively, where f1 = f2 = f3 = 1.4 mm. The focal length of the collimator lens is fc = 16 mm, and the transition zone p and the clear aperture w3 of MLA1 are: p = 0.5 mm, w3 = 0.48 mm. The diameter of the emitted light beam passing through MLA3 is D1 = 0.28 mm, and the emitted light beam passing through the beam expander module is D2 = 3.2 mm. The maximum deviation angle is The third angle θ = 0.228°. The distance d1 between MLA1 and PBS and the distance d2 between PBS and MLA2 satisfy the following equation: d1 + d2 = 10 mm. The first offset distance Δx = 0.034 mm, and the second offset distance Δx′ = 0.034 mm. A simulation was performed based on the above parameters. FIG7 is a schematic diagram of a possible simulation result provided by an embodiment of the present application. If receiving compensation is not used, the loss of the return beam is large. However, through the solution of the present application, compensation is performed at the receiving end, which can greatly reduce the loss and improve the effectiveness of the signal.

[0142] As a possible example, combined with the installation order of each component in Figure 6B, the parameters of each component are as follows: the focal lengths of MLA2 and MLA3 are f1, f2, and f3, respectively, where f1 = f2 = f3 = 1.4 mm. The focal length of the collimator lens is fc = 36 mm, and the transition zone p and the clear aperture w3 of MLA1 are: p = 0.5 mm, w3 = 0.48 mm. The diameter of the emitted light beam passing through MLA3 is D1 = 0.28 mm, and the emitted light beam passing through the beam expander module is D2 = 3.2 mm. The maximum deviation angle is The third angle θ = 0.514°. The distance d1 between MLA1 and PBS and the distance d2 between PBS and MLA2 satisfy the following equation: d1 + d2 = 10 mm. The first offset distance Δx = 0.084 mm, and the second offset distance Δx′ = 0.084 mm. A simulation is performed based on the above parameters. FIG8 is a schematic diagram of a possible simulation result provided by an embodiment of the present application. If receiving compensation is not used, the loss of the return beam is large. However, through the solution of the present application, compensation is performed at the receiving end, which can greatly reduce the loss and improve the effectiveness of the signal.

[0143] In one possible implementation, the transmitting optical module includes a waveguide or an optical fiber. And / or the receiving optical module includes a waveguide or an optical fiber. For example, the receiving optical element 2042 shown in FIG5 can be a waveguide or an optical fiber.

[0144] It is understandable that in optical modules using waveguides or optical fibers as the receiving end, the receiving mode field of waveguides and optical fibers is relatively small and more sensitive to the walkoff angle, so the return beam can easily deviate from the receiving mode field. However, the embodiments of the present application can compensate for the walkoff angle of the return beam, significantly reducing the signal loss caused by the walkoff angle, improving the effectiveness of the received echo signal, and enhancing detection performance.

[0145] Please refer to Figure 9, which is a schematic diagram of the structure and optical path of another optical module provided in an embodiment of the present application. The optical module may include an emitting optical module, a lens (such as MLA1, MLA2, MLA3, etc.), a PBS, a quarter wave plate (QWP), a collimation lens (CL), an optical receiving module and a scanner. Among them, PBS and QWP are exemplary beam splitting modules, and MLA2 and CL are exemplary beam expansion modules. Among them, the emitting optical module may include one or more of a fiber array unit (FAU), a waveguide (WG), etc. The optical receiving module may also include one or more of FAU, WG, etc. Optionally, some devices in the emitting optical module and the receiving optical module may be integrated together, for example, the waveguides may be integrated together, for example, integrated on a silicon photonic chip.

[0146] As shown in Figure 9, the optical module separates the receiving and emitting paths using the PBS and QWP. The beam expander expands the transmitted beam and converges the return beam. The position of the optical receiving module is offset from the ideal received beam. The offset distance (or, in other words, the position of the optical receiving module) and the angle are related to the walk-off angle, the distance from the center of the PBS to MLA2, and the distance from the center of the PBS to MLA1.

[0147] Furthermore, the aperture of MLA2 is related to the emission spot size and translation position.

[0148] It should be noted that the optical module components shown in this application are exemplary. In specific implementations, the optical module may include more or fewer optical components than those shown in the embodiments of this application. For example, in the following scheme, reflectors, lenses, filters, etc. may be added to the optical module to assist in light splitting, assist in beam expansion, improve light splitting efficiency, improve beam quality, and enhance device integration.

[0149] As a possible example, please refer to Figure 10, which is a schematic diagram of the structure of another optical module provided in an embodiment of the present application. By adding a reflector between the PBS and the waveguide, the position of the receiving optical element can be brought closer to the position of the transmitting optical module, thereby improving the integration of the device. For example, when the transmitting module and the receiving optical module transmit light through an optical fiber (or waveguide), the waveguide (or waveguides) can be integrated together, for example, on the same silicon photonic chip, to improve the integration of the device and reduce the volume of the optical module.

[0150] In some scenarios, some optical elements in an optical module can be packaged into an integral module, thereby further improving the stability of the optical elements, increasing the device integration, and improving the output beam quality.

[0151] In a possible implementation, the transmitting optical module, the receiving optical module, and the optical splitting module are packaged to form a first optical assembly. Furthermore, the light-transmitting window of the first optical assembly is aligned with the light-transmitting surface of the beam expansion unit.

[0152] Exemplarily, as shown in Figure 9, the optical elements in area 901, namely PBS, QWP, FAU (or WG), MLA1, MLA3, etc., can be integrated and packaged to form a group of optical components, which are conveniently distinguished as the first optical component. The optical elements in area 902, namely MLA2, CL, etc. can be integrated and packaged to form another optical component, which are conveniently distinguished as the third optical component. The light-transmitting window of the first optical component is aligned with the light-transmitting window of the third optical component. Optionally, during packaging, a material with a thermal expansion coefficient close to that of the optical elements in the optical module can be used as a supporting component to achieve high-precision alignment between the optical elements and improve the stability of the system. Among them, the supporting components include but are not limited to a base, a substrate, a gasket, etc. For example, the material of the gasket supporting optical elements such as MLA and PBS can be glass, crystal, ceramic, etc.

[0153] For example, as shown in FIG10 , the optical components in region 1001, namely, the PBS, QWP, FAU (or WG), MLA1, MLA3, MLA2, etc., can be integrated and packaged to form a set of optical assemblies, which are referred to as the second optical assembly for ease of distinction. The optical components in region 1002, namely, the CL, etc., can be integrated and packaged to form another optical assembly, which are referred to as the fourth optical assembly for ease of distinction. The light-transmitting window of the third optical assembly is aligned with the light-transmitting window of the fourth optical assembly.

[0154] Optionally, during packaging, the first and third optical elements can be packaged on the same metal base. Please refer to Figure 11, which is a schematic diagram of the structure of an optical module provided in an embodiment of the present application, in which the FAU (or WG), MLA3, PBS, MLA2, etc. can be packaged on a glass substrate. If the optical axes of the optical elements cannot be aligned, glass spacers can be used for support or filling. The first optical element and the CL with a metal barrel can be packaged on a metal base, making the optical module integrated as a whole and improving stability.

[0155] Optionally, at the viewing angle shown in FIG. 11 , MLA1 and PBS may be arranged along a direction passing through the paper (or perpendicular to the paper), and the reflected light beam reaches MLA1 along a direction passing through the paper after passing through the PBS.

[0156] An embodiment of the present application further provides a laser radar, comprising the optical module described in any one of the first aspects. Furthermore, the laser radar further comprises a light source, such as a laser. Optionally, the frequency of the light beam emitted by the light source can be continuously variable, such as a frequency modulated continuous wave (FMCW) laser.

[0157] Furthermore, the laser radar also includes a detector for obtaining an electrical signal based on the light beam. For example, the detector may include a photodiode (PD) capable of detecting light energy, such as an InGaAs PD, an InP PD, or a germanium PD.

[0158] The embodiment of the present application further provides a terminal, which includes the aforementioned optical module. Alternatively, the terminal includes the aforementioned laser radar.

[0159] Optionally, the terminal can be an intelligent terminal or transportation tool such as a vehicle, a drone, or a robot. Of course, the terminal can also be replaced by industrial equipment, entertainment and leisure equipment, etc. Intelligent terminals include mobile phones, tablet computers, laptops, smart bracelets, smart watches, or smart glasses. Transportation tools include vehicles, ships, aircraft, or logistics robots. Industrial equipment includes industrial robots and robotic arms. Leisure and entertainment equipment includes virtual reality (VR) equipment, mixed reality (MR) equipment, massage chairs, or 4D cinema cabins. This application does not impose strict restrictions on the devices to which the electrical connector can be applied.

[0160] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, a conflicting connection or an integrated connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0161] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described in this application as "exemplary" or "for example" should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0162] The “at least one” mentioned in the embodiments of this application refers to one or more, and “plurality” refers to two or more. “At least one of the following items” or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c can represent: a, b, c, (a and b), (a and c), (b and c), or (a and b and c), where a, b, c can be single or multiple. “And / or” describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character “ / ” generally indicates that the previous and next associated objects are in an “or” relationship.

[0163] Furthermore, unless otherwise specified, ordinal numbers such as "first" and "second" in the embodiments of this application are used to distinguish multiple objects and are not used to define the order, timing, priority, or importance of multiple objects. For example, the first BMU and the second BMU are only used to facilitate the description of the BMUs in the battery unit and do not indicate differences in structure, importance, etc. between the first and second BMUs.

Claims

1. An optical module, characterized in that: The optical module includes a transmitting optical module, a coaxial optical module, a scanning module and a receiving optical module, wherein: The transmitting optical module is used to transmit the first light beam emitted by the light source to the coaxial optical module; The coaxial optical module is used to transmit the first light beam to the scanning module; The scanning module is used to scan the first light beam to the object space, and is also used to transmit the first return light beam to the coaxial optical module, wherein the first return light beam is a return light beam of the first light beam; The coaxial optical module is further used to transmit the first return light beam to the receiving optical module, wherein there is a first angle between the first light beam after entering the coaxial optical module and the first return light beam before returning to the coaxial optical module, and the first angle is greater than 0° and less than 90°; The receiving optical module is used to receive the first returning light beam; There is a first offset between the position of the receiving optical module and the ideal receiving beam of the first beam, and the ideal receiving beam of the first returning beam before returning to the coaxial optical module is parallel to the first beam.

2. The optical module according to claim 1, characterized in that: The first offset is related to the first angle.

3. The optical module according to claim 1, characterized in that: The coaxial optical module includes a light splitting module and a beam expanding module, and the light splitting module is arranged between the transmitting optical module and the beam expanding module.

4. The optical module according to claim 3, characterized in that: The receiving optical module comprises a first microlens array, and the first microlens array is used to receive the first returning light beam after passing through the light splitting module; There is a third angle between the optical axis of the first microlens array and the ideal received light beam, and the third angle is less than or equal to the second angle and greater than or equal to one half of the second angle; The second angle is related to the maximum offset angle and the beam expansion multiple of the beam expansion module, and the maximum offset angle is related to the farthest detection distance of the optical module and the scanning speed of the scanning module.

5. The optical module according to claim 3, characterized in that: The beam expansion module comprises a second microlens array and a collimator, the second microlens array and the collimator have a common first focal plane, and the second microlens array is arranged between the light splitting module and the collimator.

6. The optical module according to claim 5, characterized in that: The first offset distance between the first microlens array and the ideal received light beam is related to the third angle, the distance between the first microlens array and the light splitting module, the distance between the light splitting module and the beam expanding module, and the second offset of the light spot of the first return light beam on the first focal plane; The second offset is a distance between a light spot of the first return light beam and a light spot of an ideal receiving light beam of the first return light beam on the first focal plane when the first angle is the maximum offset angle.

7. The optical module according to claim 6, characterized in that: The receiving optical module further comprises a first receiving optical element, and the receiving optical element is used to receive a first returning light beam passing through the first microlens array; The distance between the receiving optical element and the ideal receiving light beam is a second offset distance, and the second offset distance is related to the third angle, the distance between the first microlens array and the light splitting module, the distance between the light splitting module and the beam expanding module, the focal length of the second microlens array, the focal length of the collimator, and the third offset of the light spot of the first return light beam on the first focal plane; The third offset is the distance between the spot of the first return beam on the first focal plane and the spot of the maximum offset beam on the focal plane, and the maximum offset beam is the first return beam when the first angle is the maximum offset angle.

8. The optical module according to claim 7, characterized in that: The clear aperture of the first microlens array is related to at least one of the first offset distance and the second offset distance and a diameter of the first light beam before passing through the beam expansion unit.

9. The optical module according to any one of claims 3 to 8, characterized in that: The transmitting optical module, the receiving optical module and the light splitting module are packaged on a glass base to form a first optical component, and a light-transmitting window of the first optical component is aligned with a light-transmitting surface of the beam expansion unit.

10. The optical module according to any one of claims 5 to 7, characterized in that: The transmitting optical module, the receiving optical module, the light splitting module and the second microlens array are packaged on a glass base to form a second optical component, and the light-transmitting window of the second optical component is aligned with the light-transmitting surface of the collimating lens.

11. The optical module according to any one of claims 1 to 10, characterized in that: The coaxial optical module includes a polarization beam splitter PBS and a quarter wave plate.

12. The optical module according to any one of claims 1 to 11, characterized in that: The transmitting optical module is a waveguide or an optical fiber; The receiving optical module includes a waveguide or an optical fiber.

13. A laser radar, characterized in that: The laser radar comprises an optical module as described in any one of claims 1-12.

14. A terminal, characterized in that: The terminal includes the optical module as described in any one of claims 1-12 or includes the laser radar as described in claim 13.

15. The terminal according to claim 14, characterized in that: The terminal is a vehicle, a drone or a robot.

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