CN113721221A - Frequency modulation continuous wave laser radar - Google Patents
Frequency modulation continuous wave laser radar Download PDFInfo
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- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
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Abstract
The embodiment of the invention discloses a frequency modulation continuous wave laser radar, which comprises: the system comprises N photoelectric modules, an optical signal multiplexing module, an optical signal transmission module, a signal processing module and a laser scanning module; each photoelectric module comprises a laser generator, an optical splitter, an optical coupler and a photoelectric detector; the laser generator is connected with the optical splitter; the optical splitter is connected with the optical signal multiplexing module; the optical splitter is connected with the optical coupler; the optical coupler is used for performing beat frequency processing, and a second input end of the optical coupler is connected with the optical signal multiplexing module; the optical coupler is connected with the photoelectric detector; the photoelectric detector is connected with the signal processing module; the optical signal multiplexing module is connected with the optical signal transmission module; the optical signal transmission module is connected with the laser scanning module. By adopting the wavelength division multiplexer, optical signals with various wavelengths are synthesized, and only one group of processing system is needed to complete the processing of the laser signals subsequently, so that the structure is optimized, and the cost is reduced.
Description
Technical Field
The invention relates to the field of radar structures, in particular to a frequency modulation continuous wave laser radar.
Background
The radar system of the laser radar for emitting laser beams to detect characteristic quantities such as the position, the speed and the like of a target is widely applied to the field of automatic driving. The working principle is that a detection signal (laser beam) is transmitted to a target, then a received signal (target echo) reflected from the target is compared with the transmitted signal, and after appropriate processing, relevant information of the target, such as target distance, direction, height, speed, attitude, even shape and other parameters, can be obtained, so that the target is detected, tracked and identified.
In the process of implementing the invention, the inventor finds that the prior art has at least the following problems: when the laser radar is applied to laser point cloud sampling, the sampling is more and more accurate, but the sampling rate is limited by the frequency of a carrier signal, so that the existing requirement cannot be met.
Thus, there is a need for a better solution to the problems of the prior art.
Disclosure of Invention
Therefore, the invention provides a frequency modulation continuous wave laser radar which simultaneously emits through a plurality of photoelectric modules, and increases the number of laser point clouds under the condition of not increasing carrier frequency; and a group of optical signal multiplexing processing modules are adopted, so that all laser receiving and transmitting signal processing work can be completed, a group of processing systems do not need to be arranged for each wavelength, the structure is optimized, a plurality of sets of combinations including optical fiber amplifiers, optical circulators and transceivers are not needed, the cost is effectively reduced, and the failure occurrence rate is also reduced.
Specifically, the present invention proposes the following specific examples:
the embodiment of the invention provides a frequency modulation continuous wave laser radar, which comprises: the system comprises N photoelectric modules, an optical signal multiplexing module, an optical signal transmission module, a signal processing module and a laser scanning module, wherein N is an integer greater than 1;
the N photoelectric modules respectively emit laser with different wavelengths;
the optical signal multiplexing module is used for multiplexing/demultiplexing N lasers with different wavelengths;
the laser scanning module is controlled by the signal processing module;
each photoelectric module comprises a laser generator, an optical splitter, an optical coupler and a photoelectric detector;
the output end of the laser generator is connected with the input end of the optical splitter;
the first output end of the optical splitter outputs a transmitting optical wave, and is connected with the optical signal multiplexing module;
the second output end of the optical splitter outputs a local oscillator optical wave, and is connected with the first input end of the optical coupler;
the optical coupler is used for carrying out beat frequency processing on the signals output by the local oscillator light wave of the optical branching device and the optical signal multiplexing module, and a second input end of the optical coupler is connected with the optical signal multiplexing module;
the output end of the optical coupler is connected with the input end of the photoelectric detector;
the output end of the photoelectric detector is connected with the input end of the signal processing module;
the optical signal multiplexing module is connected with the optical signal transmission module;
the optical signal transmission module is connected with the laser scanning module.
The above embodiment has the following beneficial effects: considering that the number of laser cloud points cannot be increased without limit by increasing the carrier frequency, the laser cloud points can be simultaneously emitted by a plurality of photoelectric modules in the scheme, and the number of the laser cloud points is increased under the condition of not increasing the carrier frequency; and through adopting the optical signal multiplexing processing module, can accomplish whole laser and receive and dispatch signal processing work, no longer need set up a set of processing system alone for every kind of wavelength, no longer need use many sets including the combination of fiber amplifier, optical circulator and transceiver, effectively reduced the cost, optimized the structure, reduced the fault incidence simultaneously.
In a specific embodiment, the number of the optical signal multiplexing modules is 2, which are respectively defined as a first optical signal multiplexing module and a second optical signal multiplexing module;
the first optical signal multiplexing module is used for multiplexing N lasers with different wavelengths, and N input ends of the first optical signal multiplexing module are respectively connected with first output ends of N optical splitters;
the second optical signal multiplexing module is used for demultiplexing N lasers with different wavelengths, and N output ends of the second optical signal multiplexing module are respectively connected with second input ends of the N optical couplers.
In a specific embodiment, the optical signal transmission module includes an optical transceiver, and the first optical signal multiplexing module is connected to the optical transceiver; the second optical signal multiplexing module is connected with the optical transceiver; the optical transceiver is connected with the laser scanning module.
In a specific embodiment, the optical signal transmission module comprises an optical fiber circulator, and a first end of the optical fiber circulator is connected with an output end of the first optical signal multiplexing module; the second end of the optical fiber circulator is connected with the input end of the second optical signal multiplexing module; and the third end of the optical fiber circulator is connected with one end of the optical transceiver.
In a specific embodiment, the optical signal transmission module comprises an optical fiber amplifier, and an input end of the optical fiber amplifier is connected with an output end of the first optical signal multiplexing module; and the output end of the optical fiber amplifier is connected with the first end of the optical fiber circulator.
In a specific embodiment, the laser scanning module comprises at least two laser emitters, and the laser emitting directions of the at least two laser emitters are different;
a polygon mirror including a first rotation axis extending in a first direction and a plurality of mirror facets surrounding the first rotation axis;
a swing mirror including a second rotation axis extending in a second direction and a reflection surface parallel to the second rotation axis;
wherein the second direction intersects the first direction; the laser transmitter and the swing mirror are respectively arranged on the light incident side and the light emergent side of the prism surface of the polygon prism;
the polygon prism rotates around the first rotating shaft, so that the prism surface reflects laser beams emitted by at least two laser emitters onto the reflecting surface; the oscillating mirror oscillates around the second rotating shaft, so that laser beams emitted by at least two laser emitters are emitted in different directions.
In a specific embodiment, the laser scanning module further comprises a polygon mirror driving unit and a swing mirror driving unit, wherein the polygon mirror driving unit is controlled by the signal processing module and is used for driving the polygon mirror to rotate around the first rotating shaft; the swing mirror driving unit is controlled by the signal processing module and is used for driving the swing mirror to swing around the second rotating shaft.
In a specific embodiment, the photodetector includes P receivers, P amplifying units and P sampling units, where P is a positive integer;
the receivers are used for receiving the reflected laser and converting optical signals into electric signals, and the output ends of the P receivers are respectively connected with the input ends of the P amplifying units;
the amplifying units are used for amplifying the electric signals, and the output ends of the P amplifying units are respectively connected with the input end of the sampling unit;
the sampling unit is used for sampling the amplified signals output by the amplifying unit, sampling data are transmitted to the signal processing module, and the P sampling units are respectively connected with the input end of the signal processing module.
In a specific embodiment, the laser generator includes: a laser and a laser driver; the laser driver is connected with the laser to drive the laser to emit laser; the laser is connected with the optical splitter.
In a specific embodiment, the signal processing module includes: the device comprises an amplifier, a low-pass filter, an analog-to-digital conversion module and a processor;
the photoelectric detector, the amplifier, the low-pass filter and the analog-to-digital conversion module in each photoelectric module are sequentially connected with the processor.
Therefore, the wavelength division multiplexing technology is adopted, the optical signals with multiple paths of different wavelengths are synthesized, the transmission of multiple paths of laser signals can be completed only by a group of transmission systems subsequently, the technical problem that the sampling rate of the laser point cloud cannot be increased rapidly is solved, and the technical effect that the sampling rate of the laser point cloud is improved without greatly improving the carrier frequency is achieved.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings required to be used in the embodiments will be briefly described below, and it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope of the present invention. Like components are numbered similarly in the various figures.
Fig. 1 shows a schematic structural diagram of a frequency modulated continuous wave lidar according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a second frequency-modulated continuous wave lidar according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a third frequency modulated continuous wave lidar according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a fourth frequency-modulated continuous wave lidar according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a fifth frequency-modulated continuous wave lidar according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a laser scanning module according to an embodiment of the present invention;
fig. 7 shows a schematic structural diagram of a sixth frequency-modulated continuous wave lidar according to an embodiment of the present invention.
Description of the figures
100-a photovoltaic module; 110-a laser generator; 111-an optical splitter; 112-an optical coupler;
113-a photodetector; 1131 — a receiver; 1132 — an amplifying unit; 1133, a sampling unit;
101-an optical signal multiplexing module; 1011-a first optical signal multiplexing module; 1012-a second optical signal multiplexing module;
102-an optical signal transmission module; 103-laser scanning module; 104-a signal processing module; 105-an optical transceiver; 106-fiber optic circulator; 107-fiber amplifier;
210-a laser emitter; 220-a polygon prism; 230-a swing mirror; 21-a first direction; 22-a second direction; 2100-a first axis of rotation; 2200-a second rotation axis; 221-prism facets; 231-reflecting surface.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.
The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
Hereinafter, the terms "including", "having", and their derivatives, which may be used in various embodiments of the present invention, are only intended to indicate specific features, numbers, steps, operations, elements, components, or combinations of the foregoing, and should not be construed as first excluding the existence of, or adding to, one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing.
Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments of the present invention belong. The terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning that is consistent with their contextual meaning in the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein in various embodiments of the present invention.
Example 1
Embodiment 1 of the present invention discloses a frequency modulated continuous wave lidar, as shown in fig. 1, including: the system comprises N photoelectric modules 100, an optical signal multiplexing module 101, an optical signal transmission module 102, a signal processing module 104 and a laser scanning module 103, wherein N is an integer greater than 1;
the N photoelectric modules 100 respectively emit laser beams with different wavelengths;
the optical signal multiplexing module 101 is configured to perform multiplexing/demultiplexing on N laser beams with different wavelengths;
the laser scanning module 103 is controlled by the signal processing module 104;
each optoelectronic module 100 includes a laser generator 110, an optical splitter 111, an optical coupler 112, and a photodetector 113;
the output end of the laser generator 110 is connected with the input end of the optical splitter 111;
the first output end of the optical splitter 111 outputs the emission light wave, and the first output end of the optical splitter 111 is connected with the optical signal multiplexing module 101;
the second output end of the optical splitter 111 outputs the local oscillator optical wave, and the second output end of the optical splitter 111 is connected with the first input end of the optical coupler 112;
the optical coupler 112 is configured to perform beat frequency processing on the local oscillator optical wave of the optical splitter 111 and the signal output by the optical signal multiplexing module 101, and a second input end of the optical coupler 112 is connected to the optical signal multiplexing module 101;
the output end of the optical coupler 112 is connected with the input end of the photodetector 113;
the output end of the photoelectric detector 113 is connected with the input end of the signal processing module 104;
the optical signal multiplexing module 101 is connected with the optical signal transmission module 102;
the optical signal transmission module 102 is connected to the laser scanning module 103.
In this embodiment, the most direct way to increase the number of laser point clouds is to directly increase the frequency of the carrier wave. However, because the frequency of the carrier wave can not be increased without limit, the requirement of the number of laser point clouds can be met by simultaneously using multiple paths of laser for detection.
In addition, in the embodiment, by adopting the wavelength division multiplexing technology, multiple paths of optical signals with different wavelengths are synthesized, and then the transmission of the laser signals can be completed only by one group of transmission systems, and a group of transmission systems do not need to be arranged for the laser with each wavelength, so that the hardware structure is optimized, and the hardware cost is reduced.
Finally, a plurality of optoelectronic modules 100 may be provided to generate a plurality of light beam signals with different wavelengths at the same time, and since a wavelength division multiplexing module is used, the wavelength division multiplexing module combines a series of light signals which carry information and have different wavelengths into one light beam and transmits the light beam along a single optical fiber; and a communication element for separating the optical signals with different wavelengths at the receiving end. According to the scheme, the wavelength division multiplexing module is adopted to synthesize optical signals with various wavelengths, only one group of processing systems are needed to complete the processing of the laser signals subsequently, a group of processing systems do not need to be arranged for each wavelength, the structure is optimized, the cost is reduced, and the fault rate is also reduced.
It should be noted that the number N of laser emitting components provided in this embodiment is an integer greater than 1. In practical operation, the value of N is not limited.
It should be noted that the optical coupler provided in this embodiment only needs to have a function of combining two input optical signals into one output optical signal, and other optical couplers having more than two control inputs can also meet the above requirements. In practical operation, no limitation is made on the type, size and type of the optical coupler.
It should be noted that the optical splitter provided in this embodiment only needs to have a function of splitting one input optical signal into two output optical signals, and other optical splitters that have two or more controlled outputs can also meet the above requirements. In practical operation, no limitation is made on the type, size and type of the optical splitter.
Specifically, the laser generator 110 is configured to generate a laser beam. Further, the laser generator 110 may include: a laser and a laser driver; the laser driver is connected with the laser to drive the laser to emit laser; specifically, the laser includes a 1550nm laser. Assuming that the frequency of the modulation signal output by each 1550nm laser is 500Khz, and the wavelengths output by the 1550nm lasers are λ 1, λ 2, λ 3, λ 4, and λ 5, respectively, the emission frequency of the laser radar is equivalent to 500Khz × 5 ═ 2.5Mhz, that is, the laser point cloud sampling rate of the frequency modulated continuous wave laser is 2.5 Mhz. In the present embodiment, an optical signal multiplexing module 101 is provided, and the optical signal multiplexing module 101 is configured to wavelength-division-multiplex the 5 wavelength transmission light waves λ 1, λ 2, λ 3, λ 4, and λ 5, for example, with 5 wavelengths.
In practical application, a 1550nm laser can be selected to generate a 1550nm narrow-linewidth wavelength-adjustable continuous wave laser beam; of course, lasers with other wavelengths can be selected to generate laser beams with other wavelengths; the laser generator 110 is used to generate a linear triangular wave shaped current for modulating the output frequency of the laser. The laser is a narrow linewidth linear frequency modulation continuous wave laser light source, the generated output light beam is continuous coherent laser with frequency linear modulation, symmetrical triangular wave linear modulation is adopted, the frequency of a modulation signal changes in a symmetrical triangular shape along with time, in a period, the front half part is in positive frequency modulation, and the rear half part is in negative frequency modulation.
In a specific embodiment, as shown in fig. 2, the number of the optical signal multiplexing modules 101 is optionally 2, which are defined as a first optical signal multiplexing module 1011 and a second optical signal multiplexing module 1012.
The first optical signal multiplexing module 1011 is configured to multiplex N lasers with different wavelengths, and N input ends of the first optical signal multiplexing module 1011 are respectively connected to first output ends of the N optical splitters 111;
the second optical signal multiplexing module 1012 is configured to demultiplex the N laser beams with different wavelengths, and N output ends of the second optical signal multiplexing module 1012 are respectively connected to second input ends of the N optical couplers 112.
Further, as shown in fig. 3, optionally, the optical signal transmission module 102 includes an optical transceiver 105, and the first optical signal multiplexing module 1011 is connected to the optical transceiver 105; the second optical signal multiplexing module 1012 is connected to the optical transceiver 105; the optical transceiver 105 is connected to the laser scanning module 103.
As shown in fig. 4, optionally, the optical signal transmission module 102 includes an optical fiber circulator 106, where a first end of the optical fiber circulator 106 is connected to an output end of the first optical signal multiplexing module 1011; the second end of the fiber circulator 106 is connected to the input end of the second optical signal multiplexing module 1012; the third end of the fiber circulator 106 is connected to one end of the optical transceiver 105.
Specifically, the optical fiber circulator 106 is used to connect the first optical signal multiplexing module 1011, the second optical signal multiplexing module 1012, and the optical transceiver 105, and to realize signal transmission of these 3.
As shown in fig. 5, optionally, the optical signal transmission module 102 includes an optical fiber amplifier 107, and an input end of the optical fiber amplifier 107 is connected to an output end of the first optical signal multiplexing module 1011; the output of the fiber amplifier 107 is connected to a first end of a fiber circulator 106. Specifically, the optical fiber amplifier 107 is configured to perform intensity amplification and noise suppression on the received signal, which is beneficial to performing subsequent processing and improves the accuracy of the overall signal processing.
Further, the laser radar includes: at least two laser transmitters 210, wherein the laser emitting directions of the at least two laser transmitters 210 are different; as shown in fig. 6, the present invention further includes:
a polygon mirror 220 including a first rotation axis 2100 extending in the first direction 21 and a plurality of mirror facets 221 surrounding the first rotation axis 2100;
the oscillating mirror 230 includes a second rotation axis 2200 extending in the second direction 22 and a reflection surface 231 parallel to the second rotation axis 2200.
Wherein the second direction 22 and the first direction 21 intersect; the laser transmitter 210 and the swing mirror 230 are respectively arranged on the light-in side and the light-out side of the prism surface 221 of the polygon prism 220;
the polygon 220 rotates around the first rotation axis 2100, so that the prism surface 221 reflects the laser beams emitted from the at least two laser emitters 210 onto the reflection surface 231; the oscillating mirror 230 oscillates around the second rotation axis 2200 to make the laser beams emitted from the at least two laser emitters 210 emit in different directions.
The specific first direction can be a horizontal direction, the second direction can be a vertical direction, and the direction can be reversed, so that the large-view-field high-angle resolution scanning of the emitted light beams is realized through the combination of the polygon mirror and the vibrating mirror.
Further, the laser scanning module 103 further includes a polygon mirror driving unit and a swing mirror driving unit, the polygon mirror driving unit is controlled by the signal processing module 104 and is configured to drive the polygon mirror to rotate around the first rotation axis; the swing mirror driving unit is controlled by the signal processing module 104 and is used for driving the swing mirror to swing around a second rotating shaft.
Specifically, as shown in fig. 7, the photodetector 113 includes P receivers 1131, P amplifying units 1132 and P sampling units 1133, where P is a positive integer;
the receivers 1131 are configured to receive the reflected laser light and convert the optical signals into electrical signals, and output ends of the P receivers 1131 are respectively connected to input ends of the P amplifying units 1132;
the amplifying units 1132 are used for amplifying the electrical signals, and output ends of the P amplifying units 1132 are respectively connected with input ends of the sampling units 1133;
the sampling unit 1133 is configured to sample the amplified signal output by the amplifying unit 1132, transmit the sampled data to the signal processing module 104, and the P sampling units 1133 are respectively connected to an input end of the signal processing module 104.
Specifically, each receiving unit (here, the receiver 1131) is a pixel point on the image, and a single laser beam is received by a plurality of receiving units, which means that the area covered by the irradiation of the laser beam is characterized by more pixel points, so that not only is the number of laser point clouds increased, but also the information representation of the target area is more thorough.
The laser generator 110 includes: a laser and a laser driver; the laser driver is connected with the laser to drive the laser to emit laser; the laser is connected to an optical splitter 111.
Specifically, the laser emitting module comprises a driver and a laser; wherein the driver is connected to the laser to modulate the output frequency of the laser. The laser is a laser emitting module which generates continuous wave laser beams with adjustable wavelengths. In one specific embodiment, a 1550nm laser can be selected to generate a 1550nm narrow linewidth wavelength tunable continuous wave laser beam; of course, lasers with other wavelengths can be selected to generate laser beams with other wavelengths; as for the driver, it is used to generate a current in the shape of a linear triangular wave for modulating the output frequency of the laser. The driver may include: a laser diode modulator, or a laser electric field amplitude external modulator, or a phase modulator. Thus, the corresponding modulation mode can be laser diode direct modulation, laser electric field amplitude external modulation or optical external modulation implemented by a phase modulator.
In a particular embodiment, the signal processing module 104 includes: the device comprises an amplifier, a low-pass filter, an analog-to-digital conversion module and a processor;
the photodetector 113, the amplifier, the low-pass filter, and the analog-to-digital conversion module in each optoelectronic module 100 are connected to the processor in sequence. The signal processing module 104 performs amplification, filtering, gain control, analog-to-digital conversion and signal processing on each path of electric signals after photoelectric conversion; meanwhile, the laser driver is used for completing data communication, controlling the laser driver and the like.
Therefore, the embodiment of the invention provides a frequency modulation continuous wave laser radar, and the embodiment of the invention synthesizes a plurality of paths of optical signals with different wavelengths by adopting a wavelength division multiplexing technology, can complete the transmission of the laser signals subsequently only by a group of transmission systems, does not need to set a group of transmission systems for the laser with each wavelength, not only optimizes the hardware structure, but also reduces the hardware cost.
In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method can be implemented in other ways. The apparatus embodiments described above are merely illustrative and, for example, the flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a portion of a module; it should also be noted that, in alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams, and combinations of blocks in the block diagrams, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
In addition, each functional module or unit in each embodiment of the present invention may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and the changes or substitutions should be covered within the scope of the present invention.
Claims (10)
1. A frequency modulated continuous wave lidar comprising: the system comprises N photoelectric modules, an optical signal multiplexing module, an optical signal transmission module, a signal processing module and a laser scanning module, wherein N is an integer greater than 1;
the N photoelectric modules respectively emit laser with different wavelengths;
the optical signal multiplexing module is used for multiplexing/demultiplexing N lasers with different wavelengths;
the laser scanning module is controlled by the signal processing module;
each photoelectric module comprises a laser generator, an optical splitter, an optical coupler and a photoelectric detector;
the output end of the laser generator is connected with the input end of the optical splitter;
the first output end of the optical splitter outputs a transmitting optical wave, and is connected with the optical signal multiplexing module;
the second output end of the optical splitter outputs a local oscillator optical wave, and is connected with the first input end of the optical coupler;
the optical coupler is used for carrying out beat frequency processing on the signals output by the local oscillator light wave of the optical branching device and the optical signal multiplexing module, and a second input end of the optical coupler is connected with the optical signal multiplexing module;
the output end of the optical coupler is connected with the input end of the photoelectric detector;
the output end of the photoelectric detector is connected with the input end of the signal processing module;
the optical signal multiplexing module is connected with the optical signal transmission module;
the optical signal transmission module is connected with the laser scanning module.
2. A frequency modulated continuous wave lidar according to claim 1, wherein the number of optical signal multiplexing modules is 2, defined as a first optical signal multiplexing module and a second optical signal multiplexing module respectively,
the first optical signal multiplexing module is used for multiplexing N lasers with different wavelengths, and N input ends of the first optical signal multiplexing module are respectively connected with first output ends of N optical splitters;
the second optical signal multiplexing module is used for demultiplexing N lasers with different wavelengths, and N output ends of the second optical signal multiplexing module are respectively connected with second input ends of the N optical couplers.
3. A fm cw lidar as claimed in claim 2, wherein the optical signal transmission module includes an optical transceiver, and the first optical signal multiplexing module is coupled to the optical transceiver; the second optical signal multiplexing module is connected with the optical transceiver; the optical transceiver is connected with the laser scanning module.
4. A frequency modulated continuous wave lidar according to claim 3, wherein the optical signal transmission module comprises a fiber optic circulator, a first end of the fiber optic circulator being connected to an output of the first optical signal multiplexing module; the second end of the optical fiber circulator is connected with the input end of the second optical signal multiplexing module; and the third end of the optical fiber circulator is connected with one end of the optical transceiver.
5. A frequency modulated continuous wave lidar according to claim 4, wherein the optical signal transmission module comprises a fiber amplifier, an input end of the fiber amplifier being connected to an output end of the first optical signal multiplexing module; and the output end of the optical fiber amplifier is connected with the first end of the optical fiber circulator.
6. A frequency modulated continuous wave lidar according to any of claims 1 to 5, wherein the laser scanning module comprises at least two laser emitters, the laser emission directions of at least two of the laser emitters being different;
a polygon mirror including a first rotation axis extending in a first direction and a plurality of mirror facets surrounding the first rotation axis;
a swing mirror including a second rotation axis extending in a second direction and a reflection surface parallel to the second rotation axis;
wherein the second direction intersects the first direction; the laser transmitter and the swing mirror are respectively arranged on the light incident side and the light emergent side of the prism surface of the polygon prism;
the polygon prism rotates around the first rotating shaft, so that the prism surface reflects laser beams emitted by at least two laser emitters onto the reflecting surface; the oscillating mirror oscillates around the second rotating shaft, so that laser beams emitted by at least two laser emitters are emitted in different directions.
7. A frequency modulated continuous wave lidar according to claim 6, wherein the laser scanning module further comprises a polygon mirror driving unit and a swing mirror driving unit, the polygon mirror driving unit being controlled by the signal processing module for driving the polygon mirror to rotate around the first rotation axis; the swing mirror driving unit is controlled by the signal processing module and is used for driving the swing mirror to swing around the second rotating shaft.
8. A frequency modulated continuous wave lidar according to claim 1, 2, 3, 4, 5, or 7, wherein the photodetector comprises P receivers, P amplification units, and P sampling units, wherein P is a positive integer;
the receivers are used for receiving the reflected laser and converting optical signals into electric signals, and the output ends of the P receivers are respectively connected with the input ends of the P amplifying units;
the amplifying units are used for amplifying the electric signals, and the output ends of the P amplifying units are respectively connected with the input end of the sampling unit;
the sampling unit is used for sampling the amplified signals output by the amplifying unit, sampling data are transmitted to the signal processing module, and the P sampling units are respectively connected with the input end of the signal processing module.
9. A frequency modulated continuous wave lidar according to claim 1, wherein the laser generator comprises: a laser and a laser driver; the laser driver is connected with the laser to drive the laser to emit laser; the laser is connected with the optical splitter.
10. A frequency modulated continuous wave lidar according to claim 1, 2, 3, 5, 7, or 9, wherein the signal processing module comprises: the device comprises an amplifier, a low-pass filter, an analog-to-digital conversion module and a processor;
the photoelectric detector, the amplifier, the low-pass filter and the analog-to-digital conversion module in each photoelectric module are sequentially connected with the processor.
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