CN116299309A

CN116299309A - Laser radar system and laser radar control method

Info

Publication number: CN116299309A
Application number: CN202111566154.3A
Authority: CN
Inventors: 牛犇; 汪敬; 颜世佳
Original assignee: Suteng Innovation Technology Co Ltd
Current assignee: Suteng Innovation Technology Co Ltd
Priority date: 2021-12-20
Filing date: 2021-12-20
Publication date: 2023-06-23

Abstract

The invention discloses a laser radar system and a laser radar control method, wherein the system comprises: a laser and at least one detection unit; in each detection unit, the circulator is used for receiving outgoing laser light from a first port of the circulator and outputting the outgoing laser light from a second port of the circulator; the beam splitting processing module is used for splitting the emergent laser into local oscillation light and emission light, emitting the emission light to the scanning module and emitting the local oscillation light to the second port of the circulator; the scanning module is used for transmitting the emitted light to the target object and receiving the received light returned after passing through the target object; the beam splitting module is used for carrying out beam splitting processing on the received light and the local oscillation light and outputting a first optical signal and a second optical signal; the balance detector is used for carrying out balance receiving on the first optical signal and the second optical signal and detecting the related information of the target object. The scheme ensures that the main polarization directions of the local oscillation light and the received light are the same, and adopts a balanced receiving mode, thereby effectively inhibiting common mode noise.

Description

Laser radar system and laser radar control method

Technical Field

The invention relates to the technical field of laser radars, in particular to a laser radar system and a laser radar control method.

Background

The Frequency Modulation Continuous Wave (FMCW) laser radar combines frequency modulation continuous wave ranging with a laser detection technology, has the advantages of large ranging range, high range resolution, capability of Doppler speed measurement, contribution to on-chip integration and the like, and has the capability of simultaneously detecting the distance and the speed of a target object. The basic principle of the FMCW laser radar is as follows: the continuous wave light source is subjected to triangular wave linear frequency modulation, the light source output is divided into local oscillation light and emission light, the emission light propagates to the surface of a target object through space and is reflected and scattered, and part of the reflected light and scattered light are received by the laser radar to become receiving light. The received light and the local oscillation light are mixed and coherently received. Since the frequencies of the received light and the local oscillation light are different, the frequency of the difference frequency signal obtained by mixing is the frequency difference between the two. Because of the chirping, the frequency difference between the two is proportional to the space back and forth propagation time of the emitted light and the received light, so the distance of the target object can be calculated by measuring the frequency of the difference frequency signal. In addition, if the target object has radial velocity, the difference frequency signal frequency obtained by the upper sweep frequency and the lower sweep frequency is different, and the radial velocity of the target object can be solved by calculating the difference between the upper sweep frequency and the lower sweep frequency. Fig. 1 shows a schematic diagram of the basic principle of an FMCW lidar, where fig. 1 includes upper, middle and lower 3 parts, and in the upper part, a solid line is a transmit light frequency waveform, a dotted line is a receive light frequency waveform, T is a modulation period, and B is a frequency bandwidth; in the partial graph, Δf _r ＝f _if -f _d ，Δf _f ＝f _if +f _d Wherein f _if Representing the frequency difference between the received light frequency and the transmitted light frequency caused by the target distance, f _d Representing the doppler shift caused by the target velocity.

Because the FMCW laser radar obtains the principle of the difference frequency signal through the interference of two beams of light, the polarization relation of the two beams of light has great influence on the coherent effect, the phase effect is best when the main polarization directions of the two beams of light are the same (namely parallel), and the power of the difference frequency signal is the largest; conversely, the phase effect is the worst when the main polarization directions of the two beams intersect (i.e., are perpendicular), and the power of the difference frequency signal is the smallest. Therefore, in the FMCW lidar, it is necessary to ensure that the main polarization directions of the local oscillation light and the received light are the same as much as possible. How to obtain better coherent effect of the system is a problem to be solved.

Disclosure of Invention

The present invention has been made in view of the above problems, and has as its object to provide a lidar system and a lidar control method that overcome or at least partially solve the above problems.

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

the circulator is used for receiving the emergent laser from a first port of the circulator and outputting the emergent laser from a second port of the circulator;

the beam splitting processing module is arranged behind the circulator and is used for splitting the emergent laser into local oscillation light and emission light, emitting the emission light to the scanning module and emitting the local oscillation light to a second port of the circulator;

the scanning module is used for transmitting the emitted light to the target object and receiving the received light returned after passing through the target object;

the beam splitting module is used for carrying out beam splitting processing on the received light and the local oscillation light output from the third port of the circulator and outputting a first optical signal and a second optical signal;

and the balance detector is used for carrying out balance receiving on the first optical signal and the second optical signal and detecting the related information of the target object according to a balance receiving result.

Further, the spectral processing module includes: a partial mirror and an isolator;

the partial reflector is used for reflecting partial optical signals in the emergent laser to serve as local oscillation light, and other partial optical signals serving as emission light are continuously emitted to the isolator;

the isolator is arranged between the partial reflector and the scanning module and is used for enabling the emitted light to be transmitted to the scanning module in one way through the partial reflector.

Further, the spectral processing module further includes: and the collimator is used for carrying out collimation treatment on the emergent laser output from the second port of the circulator and the local oscillation light reflected by the partial reflector.

Further, the beam splitting module includes: a beam splitting prism and a reflecting mirror;

the beam splitting prism is used for carrying out beam splitting treatment on the received light and the local oscillation light to obtain a first optical signal and a second optical signal, and transmitting the first optical signal to the balance detector;

the reflecting mirror is used for changing the transmission direction of the second optical signal so as to transmit the second optical signal to the balance detector.

Further, the splitting ratio of the beam splitting prism was 50%.

Further, the system further comprises: and the optical amplifier is used for amplifying the laser emitted by the laser.

Further, when the system includes a plurality of detection units, the system further includes: a beam splitter;

the beam splitter is arranged between the laser and the plurality of detection units and is used for dividing the laser emitted by the laser into a plurality of emergent lasers so as to enable the plurality of detection units to detect target objects in a plurality of areas.

Further, the circulator is a polarization maintaining circulator.

According to another aspect of the present invention, there is provided a lidar control method applied to the lidar system described above, the method comprising:

dividing the emergent laser into cost vibration light and emission light;

transmitting the transmitted light to the target object and receiving the received light returned after passing through the target object;

carrying out beam splitting treatment on the received light and the local oscillator light, and outputting a first optical signal and a second optical signal;

and carrying out balanced receiving on the first optical signal and the second optical signal, and detecting the related information of the target object according to a balanced receiving result.

Further, dividing the outgoing laser light into the oscillating light and the emitted light further includes:

and reflecting part of optical signals in the emergent laser by using a part of reflecting mirror to serve as local oscillation light, taking other part of optical signals as emission light, and enabling the emission light to be transmitted unidirectionally by using an isolator.

Further, after dividing the outgoing laser light into the oscillating light and the emitted light, the method further comprises:

and carrying out collimation treatment on the local oscillation light and the emission light.

Further, performing beam splitting processing on the received light and the local oscillator light, and outputting a first optical signal and a second optical signal further includes:

and carrying out beam splitting treatment on the received light and the local oscillation light through a beam splitting prism to obtain a first optical signal and a second optical signal, and changing the transmission direction of the second optical signal through a reflecting mirror.

Further, the method detects the target object in the plurality of areas by a plurality of detection units.

According to the technical scheme provided by the invention, the main polarization directions of the local oscillation light and the received light are conveniently ensured to be the same, a double receiving link of a polarization diversity system is not required to be used, and the cost of the whole FMCW laser radar system is effectively reduced; and the balanced receiving mode is adopted, so that the effective utilization rate of the optical signal is improved, the better coherent effect is achieved, common mode noise can be effectively restrained, the signal-to-noise ratio of the difference frequency signal is improved, and the detection performance of the FMCW laser radar system is greatly improved.

The foregoing description is only an overview of the present invention, and is intended to be implemented in accordance with the teachings of the present invention in order that the same may be more clearly understood and to make the same and other objects, features and advantages of the present invention more readily apparent.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to designate like parts throughout the figures. In the drawings:

fig. 1 shows a schematic diagram of the basic principle of an FMCW lidar;

FIG. 2 shows a block diagram of a lidar system according to a first embodiment of the invention;

FIG. 3 shows a block diagram of the architecture of a lidar system according to a second embodiment of the invention;

fig. 4 shows an architecture block diagram of a lidar system according to a third embodiment of the invention;

FIG. 5 shows a block diagram of the architecture of a lidar system according to a fourth embodiment of the invention;

fig. 6 shows a schematic flow chart of a lidar control method according to a fifth embodiment of the present invention.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below 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 embodied 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.

The invention provides a laser radar system with stable polarization and a corresponding laser radar control method, which not only can ensure that the main polarization directions of local oscillation light and received light are the same, but also adopts a balanced receiving mode, has a better coherent effect, can effectively inhibit common-mode noise and improves signal to noise ratio. Specifically, the system comprises a laser for emitting laser light and at least one detection unit, each detection unit being used for detecting relevant information such as distance, moving speed and the like of a target object in a corresponding area. When the system comprises a plurality of detection units, the system may detect target objects in a plurality of areas simultaneously. The number of detection units can be determined by one skilled in the art according to actual needs, and is not limited herein.

Fig. 2 shows a block diagram of a lidar system according to a first embodiment of the present invention, and as shown in fig. 2, the system includes: a laser 210 for emitting laser light and a detection unit 220. Wherein the detecting unit 220 includes: circulator 221, beam splitting processing module 222, scanning module 223, beam splitting module 224, and balance detector 225.

The laser 210 emits modulated laser light. Circulator 221 is disposed at the output of laser 210. The circulator 221 includes 3 ports, which are a first port, a second port, and a third port, respectively. The circulator 221 is configured to receive the outgoing laser light from a first port of the circulator 221 and output the outgoing laser light from a second port of the circulator 221. In the first embodiment, the outgoing laser is the laser output by the laser 210, that is, the laser emitted by the laser 210 enters the first port of the circulator 221 as the outgoing laser. Alternatively, the circulator 221 may be a polarization maintaining circulator, which is used to ensure that the main polarization directions of the received light and the local oscillation light are the same.

The beam splitting processing module 222 is disposed behind the circulator 221, and is configured to split the outgoing laser beam output from the second port of the circulator 221 into the local oscillation beam and the emission beam, and emit the emission beam to the scanning module 223 and the local oscillation beam to the second port of the circulator 221. The local oscillation light will be used in the subsequent mixing process. The beam-splitting processing module 222 may specifically include: a partial mirror 2221 and an isolator 2222. The partial mirror 2221 is configured to reflect a part of the optical signals in the outgoing laser beam, take the reflected part of the optical signals as local oscillation light, and continuously transmit other part of the optical signals as transmission light to the isolator 2222. An isolator 2222 is disposed between the partial mirror 2221 and the scanning module 223 for unidirectionally transmitting the emitted light from the partial mirror 2221 to the scanning module 223.

In order to obtain a better optical signal transmission effect, the optical splitting processing module 222 may further include: a collimator 2223. A collimator 2223 may be disposed between the circulator 221 and the partial mirror 2221, and is configured to collimate the outgoing laser light output from the second port of the circulator 221 and the local oscillation light reflected by the partial mirror 2221. That is, the outgoing laser light outputted from the second port of the circulator 221 enters the collimator 2223 and is emitted to the space, in which the outgoing laser light is first reflected into local oscillation light by a part of the optical signals (i.e., part of the optical signals) in the outgoing laser light through one of the partial reflectors 2221, and the rest of the optical signals (i.e., the other part of the optical signals) continue to be emitted as emission light, and then hits the target object through the isolator 2222 and the scanning module 223. The local oscillation light is input from the second port of the circulator 221 after passing through the collimator 2223, and is output from the third port of the circulator 221.

The scanning module 223 is configured to emit emitted light to a target object and receive received light returned after passing through the target object. Wherein the target object refers to an object to be detected. Specifically, the scanning module 223 may include a scanning element, a magnifying glass lens module, and the like (not shown). The scanning element may be in particular a Micro-Electro-Mechanical System (MEMS) galvanometer or the like. The emitted light enters the angle-expanding lens module after passing through the scanning element and then is emitted to the target object. The scanning element can realize small-angle space light beam scanning, and the angle-expanding lens module can further enlarge the scanning angle of emitted light emitted from the scanning element, so that a laser radar system with a large field of view is realized. After being emitted to the target object, the emitted light is reflected and scattered by the target object to form received light, the received light returns in the original way, and the received light enters the beam splitting module 224 after passing through the scanning module 223.

Optionally, between the scanning module 223 and the beam splitting module 224, another collimator 226 may be disposed, where the collimator 226 collimates the received light returned by the scanning module 223.

Due to the isolator 2222, a part of light reflected by the target object will not pass through the original light path where the partial reflector 2221 is located again, but is received by the collimator 226 and then transmitted to the beam splitting module 224 in a spatial mode, so as to protect the original light path and reduce noise generated by reflection.

The beam splitting module 224 is configured to perform beam splitting processing on the received light and the local oscillation light output from the third port of the circulator 221, and output a first optical signal and a second optical signal. The beam splitting module 224 in this embodiment corresponds to an optical mixer. Specifically, beam splitting module 224 includes: a beam splitting prism 2241 and a mirror 2242. The beam splitter prism 2241 may be specifically a beam splitter prism with a splitting ratio of 50%, and is configured to split the received light output by the collimator 226 and the local oscillation light output from the third port of the circulator 221, to obtain a first optical signal and a second optical signal, and transmit the first optical signal to the balance detector 225. As shown in fig. 2, the received light output from the collimator 226 is input to one end of the beam splitter prism 2241, the local oscillation light output from the third port of the circulator 221 is input to the other end of the beam splitter prism 2241, the beam splitter prism 2241 splits the received light and the local oscillation light, the received light and the local oscillation light interfere with each other, and two optical signals, i.e., a first optical signal and a second optical signal, are output. In view of the difference between the transmission direction of the first optical signal and the transmission direction of the second optical signal, in order to facilitate the reception of the balance detector 225, a mirror 2242 is further disposed in the beam splitting module 224, and the mirror 2242 is configured to change the transmission direction of the second optical signal so as to transmit the second optical signal to the balance detector 225.

The first optical signal and the second optical signal output by the beam splitting module 224 are input to the balance detector 225, and the balance detector 225 receives the first optical signal and the second optical signal in a balanced manner, and detects the relevant information of the target object according to the result of the balanced reception. The balanced detector 225 is adopted, so that the power of the input optical signal is basically and completely utilized, the effective utilization rate of the optical signal is improved, a large part of noise can be counteracted, common mode noise is effectively restrained, and the signal to noise ratio is improved.

On the basis of the architecture shown in fig. 2, an optical amplifier may be further added between the laser 210 and the circulator 221, as shown in fig. 3, where the optical amplifier 230 is disposed between the laser 210 and the circulator 221, and is used to amplify the laser emitted by the laser 210, so as to effectively improve the output power of the laser 210, further improve the power of the local oscillation light, the emitted light and the received light, and increase the intensity of the final difference frequency signal. In the second embodiment, since the optical amplifier 230 is disposed in the optical path before the detection unit 220, the polarization relationship between the local oscillation light and the received light is not changed by adding the optical amplifier 230, so that the optical amplifier 230 itself does not need polarization maintaining, and the main polarization directions between the local oscillation light and the received light are ensured to be the same.

When the laser radar system comprises a plurality of detection units, the system also comprises a beam splitter, wherein the beam splitter is arranged between the laser and the plurality of detection units and is used for dividing laser emitted by the laser into a plurality of emergent lasers so as to enable the plurality of detection units to detect target objects in a plurality of areas. By arranging a plurality of detection units, the space view angle which can be detected by the laser radar system is effectively increased, so that target objects in different areas can be detected. And the system architecture can still ensure that the main polarization directions between the local oscillation light and the receiving light are the same.

Fig. 4 shows a block diagram of the architecture of a lidar system according to the third embodiment of the present invention, and as shown in fig. 4, the system includes: a laser 210, a beam splitter 240 and two detection units 220. The beam splitter 240 is disposed between the laser 210 and the two detecting units 220, and is configured to split the laser light emitted by the laser 210 into two outgoing laser light, and the two outgoing laser light are respectively transmitted to the two detecting units 220, so that each detecting unit 220 can detect an object by using the incoming outgoing laser light. The arrangement and the functions of each device in the detecting unit 220 in the third embodiment are the same as those of each device in the detecting unit 220 in the first embodiment, and are not described here again. In addition, in the third embodiment, since the beam splitter 240 is disposed in the optical path before each detection unit 220, the polarization relationship between the local oscillation light and the received light is not changed by adding the beam splitter 240, so that the beam splitter 240 itself does not need polarization maintaining, and the main polarization directions between the local oscillation light and the received light can be ensured to be the same.

On the basis of the architecture shown in fig. 4, an optical amplifier may be further added between the laser 210 and the beam splitter 240, as shown in fig. 5, where the optical amplifier 230 is disposed between the laser 210 and the beam splitter 240, and is used to amplify the laser emitted by the laser 210, so as to effectively increase the output power of the laser 210, further increase the power of the local oscillation light, the emitted light and the received light, and increase the intensity of the final difference frequency signal. The optical amplifier 230 itself does not need polarization maintaining, and can ensure that the main polarization directions between the local oscillation light and the receiving light are the same.

According to the laser radar system provided by the invention, the main polarization directions of local oscillation light and received light can be conveniently ensured to be the same, a double receiving link of a polarization diversity system is not required to be used, and the cost of the whole FMCW laser radar system is effectively reduced; the balanced receiving mode is adopted, so that the effective utilization rate of the optical signal is improved, the good coherent effect is achieved, common mode noise can be effectively restrained, the signal-to-noise ratio of the difference frequency signal is improved, and the detection performance of the FMCW laser radar system is greatly improved; in addition, when the optical amplifier is added in the system, the optical amplifier does not need polarization maintaining, and when the optical splitter does not need polarization maintaining during multiplexing optical splitting, the main polarization directions between the local oscillation light and the receiving light are ensured to be the same, so that the cost of the whole FMCW laser radar system is reduced.

Fig. 6 is a schematic flow chart of a lidar control method according to a fifth embodiment of the present invention, which is applied to the lidar system of the above embodiments, as shown in fig. 6, and includes the following steps:

step S601, the outgoing laser is divided into the oscillation light and the emission light.

The outgoing laser light can be split into the oscillation light and the emission light by the beam splitting processing module in each of the above embodiments. And the partial reflector is used for reflecting partial optical signals in the emergent laser to serve as local oscillation light, other partial optical signals serve as emission light, and the emission light is transmitted unidirectionally through the isolator. Optionally, after dividing the outgoing laser light into the local oscillation light and the emission light, the local oscillation light and the emission light may be collimated.

Step S602, the emitted light is emitted to the target object, and the received light returned after passing through the target object is received.

Step S603, performing beam splitting processing on the received light and the local oscillation light, and outputting a first optical signal and a second optical signal.

The beam splitting module in each embodiment can perform beam splitting processing on the received light and the local oscillation light. Specifically, the beam splitting prism is used for carrying out beam splitting processing on the received light and the local oscillation light to obtain a first optical signal and a second optical signal, and the transmission direction of the second optical signal is changed through the reflecting mirror.

In step S604, the first optical signal and the second optical signal are received in a balanced manner, and the relevant information of the target object is detected according to the result of the balanced reception.

Alternatively, the method may detect the target object in a plurality of regions by a plurality of detection units.

According to the laser radar control method provided by the invention, the main polarization directions of local oscillation light and received light can be conveniently ensured to be the same, and a balanced receiving mode is adopted, so that the effective utilization rate of optical signals is improved, a better coherent effect is achieved, common-mode noise can be effectively inhibited, the signal-to-noise ratio of difference frequency signals is improved, and the detection performance of an FMCW laser radar system is greatly improved.

The algorithms and displays presented herein are not inherently related to any particular computer, virtual system, or other apparatus. Various general-purpose systems may also be used with the teachings herein. The required structure for a construction of such a system is apparent from the description above. In addition, the present invention is not directed to any particular programming language. It will be appreciated that the teachings of the present invention described herein may be implemented in a variety of programming languages, and the above description of specific languages is provided for disclosure of enablement and best mode of the present invention.

In the description provided herein, numerous specific details are set forth. However, it is 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 in order not to obscure an understanding of this description.

Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, the disclosed method should not be construed as reflecting the intention that: i.e., the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Those skilled in the art will appreciate that the modules in the apparatus of the embodiments may be adaptively changed and disposed in one or more apparatuses different from the embodiments. The modules or units or components of the embodiments may be combined into one module or unit or component and, furthermore, they may be divided into a plurality of sub-modules or sub-units or sub-components. Any combination of all features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or units of any method or apparatus so disclosed, may be used in combination, except insofar as at least some of such features and/or processes or units are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.

Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features but not others included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments may be used in any combination.

Various component embodiments of the invention may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. Those skilled in the art will appreciate that some or all of the functions of some or all of the components in accordance with embodiments of the present invention may be implemented in practice using a microprocessor or Digital Signal Processor (DSP). The present invention can also be implemented as an apparatus or device program (e.g., a computer program and a computer program product) for performing a portion or all of the methods described herein. Such a program embodying the present invention may be stored on a computer readable medium, or may have the form of one or more signals. Such signals may be downloaded from an internet website, provided on a carrier signal, or provided in any other form.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The use of the words first, second, third, etc. do not denote any order. These words may be interpreted as names.

Claims

1. A lidar system, the system comprising: a laser for emitting laser light and at least one detection unit; each detection unit comprises:

the circulator is used for receiving outgoing laser from a first port of the circulator and outputting the outgoing laser from a second port of the circulator;

the scanning module is used for transmitting the emitted light to a target object and receiving the received light returned after passing through the target object;

2. The system of claim 1, wherein the spectral processing module comprises: a partial mirror and an isolator;

the isolator is arranged between the partial reflector and the scanning module and is used for enabling the emitted light to be transmitted to the scanning module in a unidirectional mode through the partial reflector.

3. The system of claim 2, wherein the spectral processing module further comprises: and the collimator is used for carrying out collimation treatment on the emergent laser output from the second port of the circulator and the local oscillation light reflected by the partial reflector.

4. A system according to any one of claims 1-3, wherein the beam splitting module comprises: a beam splitting prism and a reflecting mirror;

the beam splitting prism is used for carrying out beam splitting processing on the received light and the local oscillation light to obtain a first optical signal and a second optical signal, and transmitting the first optical signal to the balance detector;

5. The system of claim 4, wherein the splitting ratio of the splitting prism is 50%.

6. The system of any one of claims 1-5, wherein the system further comprises: and the optical amplifier is used for amplifying the laser emitted by the laser.

7. The system of any one of claims 1-6, wherein when the system comprises a plurality of detection units, the system further comprises: a beam splitter;

8. The system of any one of claims 1-7, wherein the circulator is a polarization maintaining circulator.

9. A lidar control method, characterized in that the method is applied to the lidar system of any of claims 1 to 8, the method comprising:

dividing the emergent laser into cost vibration light and emission light;

transmitting the transmitted light to a target object and receiving the received light returned after passing through the target object;

carrying out beam splitting treatment on the received light and the local oscillation light, and outputting a first optical signal and a second optical signal;

10. The method of claim 9, wherein dividing the outgoing laser light into the oscillating light and the emitted light further comprises:

and reflecting part of the optical signals in the emergent laser by using a part of reflecting mirror to serve as local oscillation light, taking other part of the optical signals as emission light, and enabling the emission light to be transmitted unidirectionally by using an isolator.

11. The method of claim 9, wherein after said dividing the outgoing laser light into the oscillating light and the emitted light, the method further comprises:

12. The method according to any one of claims 9 to 11, wherein the splitting the received light and the local oscillator light to output a first optical signal and a second optical signal further comprises:

13. The method according to any one of claims 9-12, wherein the method detects target objects in a plurality of areas by a plurality of detection units.