Lidar system and lidar control method

Abstract

The application discloses a laser radar system and a laser radar control method. The system comprises a laser and at least one detection unit. In each detection unit, a circulator is used to receive outgoing laser from a first port of the circulator and output the outgoing laser from a second port of the circulator; a light splitting processing module is used to split the outgoing laser into local laser and emission light, emit the emission light to a scanning module, and emit the local laser to the second port of the circulator; the scanning module is used to emit the emission light to a target object and receive receiving light returned after the target object; a beam splitting module is used to perform beam splitting processing on the receiving light and the local laser, and output first light signals and second light signals; and a balanced detector is used to perform balanced receiving on the first light signals and the second light signals, and detect related information of the target object. The scheme ensures that the main polarization directions of the local laser and the receiving light are the same, and the balanced receiving mode is adopted, so that common mode noise is effectively suppressed.

Description

Technical Field

[0001] This invention relates to the field of lidar technology, specifically to a lidar system and lidar control method. Background Technology

[0002] Frequency-modulated continuous-wave (FMCW) lidar combines frequency-modulated continuous-wave ranging with laser detection technology. It offers advantages such as a large ranging range, high distance resolution, Doppler velocimetry capabilities, and suitability for on-chip integration. It has the ability to simultaneously detect the distance and velocity of a target object. The basic principle of FMCW lidar is as follows: A continuous-wave light source is linearly frequency-modulated using a triangular wave, and the output is split into a local oscillator beam and a emitted beam. The emitted beam propagates through space to the surface of the target object, where it is reflected and scattered. A portion of the reflected and scattered light is received by the lidar. The received beam and the local oscillator beam are then mixed and coherently received. Since the received beam and the local oscillator beam have different frequencies, the frequency of the difference signal obtained from the mixing is the frequency difference between the two beams. Because it is linearly frequency-modulated, the frequency difference is proportional to the round-trip propagation time of the emitted and received beams. Therefore, the distance to the target object can be calculated by measuring the frequency of the difference signal. Furthermore, if the target object has a radial velocity, the difference frequency signals obtained from the up-sweep and down-sweep frequencies will be different. The radial velocity of the target object can be calculated by calculating the difference between the two. Figure 1 A schematic diagram illustrating the basic principle of FMCW lidar is shown. Figure 1 The diagram comprises three parts: upper, middle, and lower. In the upper part, the solid line represents the transmitted light frequency waveform, the dashed line represents the received light frequency waveform, T is the modulation period, and B is the frequency bandwidth. In the middle part, Δf... r =f if -f d , Δf f =f if +f d , where f if f represents the frequency difference between the received and transmitted light frequencies caused by the target distance. d This indicates the Doppler shift caused by the target velocity.

[0003] Since FMCW lidar obtains the difference frequency signal through the interference of two beams, the polarization relationship of the two beams significantly affects the coherence effect. The best coherence and maximum power of the difference frequency signal occur when the principal polarization directions of the two beams are the same (i.e., parallel); conversely, the worst coherence and minimum power of the difference frequency signal occur when the principal polarization directions of the two beams intersect (i.e., perpendicular). Therefore, in FMCW lidar, it is crucial to ensure that the principal polarization directions of the local oscillator beam and the received beam are as similar as possible. How to achieve optimal coherence in the system has become a pressing issue. Summary of the Invention

[0004] In view of the above problems, the present invention is proposed to provide a lidar system and lidar control method that overcomes or at least partially solves the above problems.

[0005] According to one aspect of the present invention, a lidar system is provided, the system comprising: a laser for emitting laser light and at least one detection unit; each detection unit comprising:

[0006] A circulator is used to receive the emitted laser from the first port of the circulator and output the emitted laser from the second port of the circulator.

[0007] The beam splitting module, located after the circulator, is used to split the outgoing laser into local oscillator light and emitted light, emit the emitted light to the scanning module, and emit the local oscillator light to the second port of the circulator.

[0008] The scanning module is used to emit light to the target object and receive the light that returns after passing through the target object;

[0009] The beam splitting module is used to split the received light and the local oscillator light output from the third port of the circulator, and output a first optical signal and a second optical signal.

[0010] A balanced detector is used to receive the first and second optical signals in a balanced manner, and to detect relevant information about the target object based on the balanced reception results.

[0011] Furthermore, the beam splitting module includes: partial reflectors and isolators;

[0012] Some of the reflectors are used to reflect part of the light signal in the emitted laser as local oscillator light, while the other part of the light signal is emitted as transmitted light and sent to the isolator.

[0013] An isolator is placed between a partial reflector and a scanning module to allow emitted light to be transmitted unidirectionally from the partial reflector to the scanning module.

[0014] Furthermore, the beam splitting module also includes a collimator for collimating the emitted laser light output from the second port of the circulator and the local oscillator light reflected back from a portion of the mirror.

[0015] Furthermore, the beam-splitting module includes: a beam-splitting prism and a reflector;

[0016] The beam splitter is used to split the received light and the local oscillator light into beams to obtain a first optical signal and a second optical signal, and then transmits the first optical signal to the balanced detector.

[0017] The reflector is used to change the transmission direction of the second optical signal so that the second optical signal can be transmitted to the balanced detector.

[0018] Furthermore, the beam splitter has a beam splitting ratio of 50%.

[0019] Furthermore, the system also includes an optical amplifier for amplifying the laser emitted by the laser.

[0020] Furthermore, when the system includes multiple detection units, the system also includes: a beam splitter;

[0021] A beam splitter is positioned between the laser and multiple detection units to split the laser emitted by the laser into multiple outgoing laser beams, which can then be used by multiple detection units to detect target objects in multiple regions.

[0022] Furthermore, the circulator is a polarization-maintaining circulator.

[0023] According to another aspect of the present invention, a lidar control method is provided, which is applied to the aforementioned lidar system, the method comprising:

[0024] The emitted laser beam is divided into a local oscillating beam and an emitted beam;

[0025] The emitted light is directed to the target object, and the received light is received after passing through the target object and returning.

[0026] The received light and the local oscillator light are split into beams to output a first optical signal and a second optical signal.

[0027] The first and second optical signals are received in a balanced manner, and relevant information about the target object is detected based on the balanced reception results.

[0028] Furthermore, the emitted laser beam is further divided into oscillating light and emitted light, which include:

[0029] Part of the light signal in the emitted laser is reflected by a partial reflector to serve as the local oscillator light, while the remaining light signal is used as the emitted light, and the emitted light is transmitted unidirectionally through an isolator.

[0030] Furthermore, after separating the emitted laser beam into oscillating light and emitted light, the method further includes:

[0031] Collimation processing is performed on the local oscillator light and the emitted light.

[0032] Furthermore, the received light and the local oscillator light are split into beams to output a first optical signal and a second optical signal, which further include:

[0033] The received light and the local oscillator light are split by a beam splitter to obtain a first optical signal and a second optical signal. The transmission direction of the second optical signal is changed by a reflector.

[0034] Furthermore, this method uses multiple detection units to detect target objects in multiple regions.

[0035] According to the technical solution provided by the present invention, it is possible to conveniently ensure that the main polarization directions of the local oscillator light and the received light are the same, eliminating the need for a double receiving link in the polarization diversity system, thus effectively reducing the overall cost of the FMCW lidar system. Moreover, the balanced receiving method improves the effective utilization rate of the optical signal, has better coherence, effectively suppresses common-mode noise, improves the signal-to-noise ratio of the difference frequency signal, and greatly enhances the detection performance of the FMCW lidar system.

[0036] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0037] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0038] Figure 1 A schematic diagram illustrating the basic principle of FMCW lidar is shown.

[0039] Figure 2 A block diagram of the architecture of a lidar system according to Embodiment 1 of the present invention is shown;

[0040] Figure 3 A block diagram of the architecture of a lidar system according to Embodiment 2 of the present invention is shown;

[0041] Figure 4 A block diagram of the architecture of a lidar system according to Embodiment 3 of the present invention is shown;

[0042] Figure 5 A block diagram of the architecture of a lidar system according to Embodiment 4 of the present invention is shown;

[0043] Figure 6 A schematic flowchart of a lidar control method according to Embodiment 5 of the present invention is shown. Detailed Implementation

[0044] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0045] This invention provides a polarization-stabilized lidar system and its corresponding lidar control method. This system not only ensures that the main polarization directions of the local oscillator light and the received light are the same, but also employs a balanced receiving method, resulting in better coherence and effective suppression of common-mode noise, thus improving the signal-to-noise ratio. Specifically, the system includes a laser for emitting laser light and at least one detection unit. Each detection unit is used to detect information such as the distance and movement speed of a target object in a corresponding area. When the system includes multiple detection units, it can simultaneously detect target objects in multiple areas. Those skilled in the art can determine the number of detection units according to actual needs; no limitation is made here.

[0046] Figure 2 A block diagram of the architecture of a lidar system according to Embodiment 1 of the present invention is shown, as follows: Figure 2 As shown, the system includes a laser 210 for emitting laser light and a detection unit 220. The detection unit 220 includes a circulator 221, a beam splitting module 222, a scanning module 223, a beam splitting module 224, and a balancing detector 225.

[0047] Laser 210 emits modulated laser light. A circulator 221 is disposed at the output end of laser 210. Circulator 221 includes three ports: a first port, a second port, and a third port. Circulator 221 receives the emitted laser light from its first port and outputs the emitted laser light from its second port. In embodiment one, the emitted laser light is the laser light output by laser 210, meaning the laser light emitted by laser 210 enters the first port of circulator 221 as the emitted laser light. Optionally, circulator 221 can specifically be a polarization-maintaining circulator to ensure that the received light and the local oscillator light have the same principal polarization direction.

[0048] The beam splitting module 222, located after the circulator 221, splits the emitted laser light output from the second port of the circulator 221 into a local oscillator beam and an emitted beam. The emitted beam is then transmitted to the scanning module 223, while the local oscillator beam is transmitted back to the second port of the circulator 221. The local oscillator beam is used in subsequent mixing processing. Specifically, the beam splitting module 222 may include a partial reflector 2221 and an isolator 2222. The partial reflector 2221 reflects a portion of the emitted laser light signal, using the reflected portion as the local oscillator beam and transmitting the remaining portion as the emitted beam to the isolator 2222. The isolator 2222 is positioned between the partial reflector 2221 and the scanning module 223, allowing the emitted beam to be transmitted unidirectionally from the partial reflector 2221 to the scanning module 223.

[0049] To achieve better optical signal transmission, the beam splitting module 222 may further include a collimator 2223. The collimator 2223 can be positioned between the circulator 221 and the partial reflector 2221 to collimate the emitted laser light output from the second port of the circulator 221 and the local oscillator light reflected back from the partial reflector 2221. Specifically, the emitted laser light output from the second port of the circulator 221 enters the collimator 2223 and is emitted into space. In space, the emitted laser light first passes through a partial reflector 2221, causing a small portion of the optical signal (i.e., partial optical signal) to be reflected as local oscillator light. The remaining portion of the optical signal (i.e., other optical signals) continues to be emitted as emitted light, passing through the isolator 2222 and the scanning module 223 before striking the target object. The local oscillator light, after passing through the collimator 2223, enters from the second port of the circulator 221 and exits from the third port of the circulator 221.

[0050] The scanning module 223 is used to emit light to a target object and receive the received light returning after passing through the target object. The target object refers to the object to be detected. Specifically, the scanning module 223 may include a scanning element and an expanding lens module (not shown in the figure). The scanning element may specifically be a micro-electro-mechanical system (MEMS) galvanometer. The emitted light passes through the scanning element and then enters the expanding lens module, before being emitted to the target object. The scanning element enables small-angle spatial beam scanning, and the expanding lens module further amplifies the scanning angle of the emitted light emitted from the scanning element, thereby realizing a large field-of-view lidar system. After the emitted light reaches the target object, it is reflected and scattered by the target object to form received light, which returns along the same path. After passing through the scanning module 223, the received light enters the beam splitter module 224.

[0051] Optionally, another collimator 226 may be provided between the scanning module 223 and the beam splitting module 224. The collimator 226 performs collimation processing on the received light returned by the scanning module 223.

[0052] Because of the presence of isolator 2222, a portion of the light reflected by the target object will not pass through the original optical path where the partial reflector 2221 is located again. Instead, it is received by collimator 226 and transmitted spatially to beam splitter 224, thus protecting the original optical path and reducing noise generated by reflection.

[0053] Beam splitting module 224 is used to split the received light and the local oscillator light output from the third port of circulator 221, outputting a first optical signal and a second optical signal. In this embodiment, beam splitting module 224 is equivalent to an optical mixer. Specifically, beam splitting module 224 includes a beam splitting prism 2241 and a reflector 2242. Beam splitting prism 2241 can specifically be a beam splitting prism with a splitting ratio of 50%, used to split the received light output from collimator 226 and the local oscillator light output from the third port of circulator 221 to obtain a first optical signal and a second optical signal, and transmit the first optical signal to balanced detector 225. Figure 2 As shown, the received light output from collimator 226 is input to one end of beam splitter prism 2241, and the local oscillator light output from the third port of circulator 221 is input to the other end of beam splitter prism 2241. Beam splitter prism 2241 splits the received light and local oscillator light into beams, causing interference between their light fields and outputting two optical signals, namely the first optical signal and the second optical signal. Considering that the transmission directions of the first optical signal and the second optical signal formed after beam splitting are different, a reflector 2242 is also provided in beam splitter module 224 to facilitate reception by balanced detector 225. The reflector 2242 is used to change the transmission direction of the second optical signal so that it can be transmitted to balanced detector 225.

[0054] The first and second optical signals output from the beam splitter module 224 are input to the balanced detector 225. The balanced detector 225 performs balanced reception of the first and second optical signals and detects relevant information about the target object based on the balanced reception result. Because of the use of the balanced detector 225, the power of the input optical signal is almost fully utilized, improving the effective utilization rate of the optical signal. Furthermore, it can cancel out a large portion of the noise, effectively suppressing common-mode noise and improving the signal-to-noise ratio.

[0055] exist Figure 2 Based on the architecture shown, an optical amplifier can also be added between the laser 210 and the circulator 221, such as... Figure 3As shown, the optical amplifier 230 is positioned between the laser 210 and the circulator 221 to amplify the laser emitted by the laser 210, effectively increasing the output power of the laser 210, thereby increasing the power of the local oscillator light, the emitted light, and the received light, and increasing the intensity of the final difference frequency signal. In Embodiment 2, since the optical amplifier 230 is positioned in the optical path before the detection unit 220, the addition of the optical amplifier 230 does not change the polarization relationship between the local oscillator light and the received light. Therefore, the optical amplifier 230 itself does not need to maintain polarization to ensure that the principal polarization directions of the local oscillator light and the received light are the same.

[0056] When a lidar system includes multiple detection units, it also needs a beam splitter. The beam splitter is positioned between the laser and the multiple detection units to split the emitted laser beam into multiple output laser beams, allowing the multiple detection units to detect target objects in multiple areas. By using multiple detection units, the spatial field of view that the lidar system can detect is effectively increased, enabling it to detect target objects in different areas. Furthermore, this system architecture still ensures that the principal polarization directions of the local oscillator light and the received light are the same.

[0057] Figure 4 A block diagram of the architecture of a lidar system according to Embodiment 3 of the present invention is shown, as follows: Figure 4 As shown, the system includes a laser 210, a beam splitter 240, and two detection units 220. The beam splitter 240 is positioned between the laser 210 and the two detection units 220, splitting the laser emitted by the laser 210 into two outgoing laser beams. These two outgoing laser beams are transmitted to the two detection units 220 respectively, allowing each detection unit 220 to use the input outgoing laser beams for object detection. The components in the detection unit 220 in Embodiment 3 are arranged and function the same as those in the detection unit 220 in Embodiment 1, and will not be described again here. Furthermore, in Embodiment 3, since the beam splitter 240 is positioned in the optical path before each detection unit 220, its addition does not change the polarization relationship between the local oscillator light and the received light. Therefore, the beam splitter 240 itself does not need to maintain polarization to ensure that the principal polarization directions of the local oscillator light and the received light are the same.

[0058] exist Figure 4 Based on the architecture shown, an optical amplifier can also be added between the laser 210 and the beam splitter 240, such as... Figure 5As shown, the optical amplifier 230 is positioned between the laser 210 and the beam splitter 240 to amplify the laser emitted by the laser 210, effectively increasing the output power of the laser 210, thereby increasing the power of the local oscillator light, the emitted light, and the received light, and increasing the intensity of the final difference frequency signal. The optical amplifier 230 itself does not require polarization maintenance, ensuring that the principal polarization directions of the local oscillator light and the received light are the same.

[0059] The lidar system provided by this invention can conveniently ensure that the main polarization directions of the local oscillator light and the received light are the same, eliminating the need for a double receiving link in a polarization diversity system and effectively reducing the overall cost of the FMCW lidar system. Furthermore, the balanced receiving method improves the effective utilization of the optical signal, exhibits better coherence, effectively suppresses common-mode noise, and improves the signal-to-noise ratio of the difference frequency signal, significantly enhancing the detection performance of the FMCW lidar system. In addition, when an optical amplifier is added to the system, the optical amplifier does not need to maintain polarization, and when multiple beams are split, the beam splitter also does not need to maintain polarization, thus ensuring that the main polarization directions of the local oscillator light and the received light are the same, which helps to reduce the overall cost of the FMCW lidar system.

[0060] Figure 6 A flowchart illustrating a lidar control method according to Embodiment 5 of the present invention is shown. This method is applied to the lidar systems of the above embodiments, such as... Figure 6 As shown, the method includes the following steps:

[0061] Step S601: The emitted laser beam is divided into oscillating light and emitted light.

[0062] The emitted laser beam can be split into local oscillator light and emitted light using the beam splitting processing module in the above embodiments. Specifically, a portion of the light signal in the emitted laser beam is reflected by a partial reflector to serve as the local oscillator light, while the remaining portion serves as the emitted light. An isolator ensures unidirectional transmission of the emitted light. Optionally, after splitting the emitted laser beam into local oscillator light and emitted light, collimation processing can be performed on the local oscillator light and emitted light.

[0063] Step S602: The emitted light is emitted to the target object, and the received light that returns after passing through the target object is received.

[0064] Step S603: Perform beam splitting on the received light and the local oscillator light to output the first optical signal and the second optical signal.

[0065] The received light and the local oscillator light can be split into beams using the beam-splitting modules in the above embodiments. Specifically, the received light and the local oscillator light are split into beams using a beam-splitting prism to obtain a first optical signal and a second optical signal, and the transmission direction of the second optical signal is changed by a reflector.

[0066] Step S604: Balance the reception of the first optical signal and the second optical signal, and detect relevant information of the target object based on the balanced reception result.

[0067] Alternatively, the method can detect target objects in multiple regions using multiple detection units.

[0068] The lidar control method provided by the present invention can conveniently ensure that the main polarization directions of the local oscillator light and the received light are the same, and the balanced receiving method improves the effective utilization rate of the optical signal, has better coherence effect, can effectively suppress common-mode noise, improve the signal-to-noise ratio of the difference frequency signal, and greatly enhance the detection performance of the FMCW lidar system.

[0069] The algorithms and displays provided herein are not inherently related to any particular computer, virtual system, or other device. Various general-purpose systems can also be used in conjunction with the teachings herein. The required structure for constructing such systems is apparent from the above description. Furthermore, this invention is not directed to any particular programming language. It should be understood that the contents of the invention described herein can be implemented using various programming languages, and the above description of specific languages ​​is for the purpose of disclosing the best mode of implementation of the invention.

[0070] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0071] Similarly, it should be understood that, in order to streamline this disclosure and aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.

[0072] Those skilled in the art will understand that modules in the device of the embodiments can be adaptively changed and placed in one or more devices different from that embodiment. Modules, units, or components in the embodiments can be combined into a single module, unit, or component, and further, they can be divided into multiple sub-modules, sub-units, or sub-components. Except where at least some of such features and / or processes or units are mutually exclusive, any combination can be used to combine all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or units of any method or device so disclosed. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature that serves the same, equivalent, or similar purpose.

[0073] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features but not others included in other embodiments, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments can be used in any combination.

[0074] The various component embodiments of the present invention can be implemented in hardware, or as software modules running on one or more processors, or a combination thereof. Those skilled in the art will understand that microprocessors or digital signal processors (DSPs) can be used in practice to implement some or all of the functions of some or all of the components according to the embodiments of the present invention. The present invention can also be implemented as a device or apparatus program (e.g., a computer program and computer program product) for performing part or all of the methods described herein. Such programs implementing the present invention can be stored on a computer-readable medium, or can be in the form of one or more signals. Such signals can be downloaded from an Internet website, provided on a carrier signal, or provided in any other form.

[0075] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

Claims

1. A lidar system, characterized in that, The system includes: a laser for emitting laser light and at least one detection unit; each detection unit includes: A circulator is used to receive the emitted laser from a first port of the circulator and output the emitted laser from a second port of the circulator; the circulator is a polarization-maintaining circulator. A beam splitting module, located after the circulator, is used to split the emitted laser into a local oscillator beam and an emitted beam, transmit the emitted beam to the scanning module, and transmit the local oscillator beam to the second port of the circulator; The scanning module is used to emit the emitted light to the target object and receive the received light that returns after passing through the target object; The beam splitting module is used to split the received light and the local oscillator light output from the third port of the circulator, and output a first optical signal and a second optical signal. A balanced detector is used to receive the first optical signal and the second optical signal in a balanced manner, and to detect relevant information of the target object based on the balanced reception result.

2. The system according to claim 1, characterized in that, The beam splitting module includes: a partial reflector and an isolator; The partial reflector is used to reflect part of the light signal in the emitted laser as local oscillator light, and to emit the other part of the light signal as emitted light to the isolator. The isolator is disposed between the partial reflector and the scanning module to enable the emitted light to be transmitted unidirectionally from the partial reflector to the scanning module.

3. The system according to claim 2, characterized in that, The beam splitting processing module further includes a collimator for collimating the emitted laser light output from the second port of the circulator and the local oscillator light reflected back by the partial reflector.

4. The system according to any one of claims 1-3, characterized in that, The beam splitting module includes: a beam splitting prism and a reflector; The beam splitter is used to split the received light and the local oscillator light to obtain a first optical signal and a second optical signal, and transmit the first optical signal to the balanced detector. The reflector is used to change the transmission direction of the second optical signal so as to transmit the second optical signal to the balanced detector.

5. The system according to claim 4, characterized in that, The beam splitter has a splitting ratio of 50%.

6. The system according to any one of claims 1-3, characterized in that, The system further includes an optical amplifier for amplifying the laser emitted by the laser.

7. The system according to any one of claims 1-3, characterized in that, When the system includes multiple detection units, the system further includes: a beam splitter; The beam splitter is positioned between the laser and the multiple detection units to split the laser emitted by the laser into multiple outgoing lasers, which are then used by the multiple detection units to detect target objects in multiple regions.

8. A lidar control method, characterized in that, The method is applied to the lidar system according to any one of claims 1-7, and the method includes: The emitted laser beam is divided into a local oscillating beam and an emitted beam; The emitted light is emitted to the target object, and the received light returning after passing through the target object is received; The received light and the local oscillator light are split into beams to output a first optical signal and a second optical signal. The first optical signal and the second optical signal are received in a balanced manner, and relevant information of the target object is detected based on the balanced reception result.

9. The method according to claim 8, characterized in that, The step of separating the emitted laser beam into oscillating light and emitted light further includes: A portion of the emitted laser light is reflected by a partial reflector to serve as the local oscillator light, while the remaining portion is used as the emitted light. The emitted light is then transmitted unidirectionally via an isolator.

10. The method according to claim 8, characterized in that, After separating the emitted laser beam into local oscillator light and emitted light, the method further includes: The local oscillator light and the emitted light are collimated.

11. The method according to any one of claims 8-10, characterized in that, The step of splitting the received light and the local oscillator light to output a first optical signal and a second optical signal further includes: The received light and the local oscillator light are split by a beam splitter to obtain a first optical signal and a second optical signal, and the transmission direction of the second optical signal is changed by a reflector.

12. The method according to any one of claims 8-10, characterized in that, The method uses multiple detection units to detect target objects in multiple regions.

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