A parallel frequency-modulated continuous wave laser radar ranging and velocity measuring system

Abstract

The application belongs to the technical field of laser radar, and discloses a parallel linear frequency modulation continuous wave laser radar ranging and velocity measuring system, wherein laser of different wavelengths is emitted by a narrow linewidth single frequency fiber laser array, enters an electro-optic modulator after passing through a wavelength division multiplexer, and laser carrier output after passing through a fiber coupler is modulated by an arbitrary waveform generator and a microwave amplifier through the electro-optic modulator; the modulated light is divided into two beams of light by a beam splitter, one is a local oscillation light, and the other is a detection light; the detection light enters a fiber loop after power amplification by an EDFA amplifier, is emitted to an object after dispersion by a three-prism, and the reflected detection light enters the loop after entering the three-prism, mixes with the local oscillation light to enter a fiber coupler, and the light after the wavelength division multiplexer is obtained by a photoelectric detector to obtain an intermediate frequency signal, and then real-time N-way parallel fast Fourier transform is carried out to realize N-way distance and speed synchronous measurement. The application improves laser radar data acquisition rate and image refresh rate, and expands the field of view angle of the laser radar.

Description

Technical Field

[0001] This invention belongs to the field of lidar technology and relates to a parallel linear frequency modulated continuous wave lidar ranging and velocity measurement system. Background Technology

[0002] Lidar (Light Detection and Ranging) is an active remote sensing technology that uses lasers for imaging, reconnaissance, and ranging. Because the wavelength of laser light is several orders of magnitude shorter than that of microwaves, lidar offers higher angular resolution, range resolution, and velocity resolution, a greater ranging range, stronger anti-jamming capabilities, and smaller size and mass compared to microwave radar, significantly expanding the application range of radar. Lidar works by actively illuminating a target area with a laser emitted by a transmitting system. The detection system then detects and processes the laser echo signal reflected from the target to obtain characteristic information such as the target's distance, velocity, and azimuth, enabling target detection, tracking, and identification. It is widely used in autonomous driving.

[0003] Traditional lidar typically measures only a single target, making simultaneous ranging and velocity measurement impossible, and it also suffers from blind spots. However, lidar applications often involve measuring multiple targets simultaneously, in which case traditional lidar struggles to meet the measurement requirements.

[0004] Frequency-modulated continuous wave (FM-CHW) lidar uses a modulated signal whose frequency varies with time for coherent measurement. It detects signals by measuring the frequency difference between the echo signal and the local oscillator signal. This allows for demodulation with a smaller receiver bandwidth, making it relatively easy to achieve higher measurement resolution. Furthermore, compared to traditional time-of-flight (TOF) methods using pulsed laser signals, FM-CHW lidar does not require high-precision timers and receivers, eliminates range blind spots, provides a wider ranging range, and offers higher resolution and sensitivity. Theoretically, it is unaffected by ambient light and other laser emitters, has a higher signal-to-noise ratio, and is safer for the human eye.

[0005] In the process of realizing this invention, the inventors discovered that the existing frequency-modulated continuous wave lidar technology has the following problems: when lidar is used for laser point cloud sampling, although the more samples taken, the more accurate the measurement results, the sampling rate cannot meet the current needs due to the limitations of the carrier signal frequency and scanning speed. Summary of the Invention

[0006] (I) Purpose of the Invention

[0007] The purpose of this invention is to solve the problems in the existing technology of frequency-modulated continuous wave lidar and realize simultaneous ranging and velocity measurement of multiple targets and multiple fields of view. It proposes a parallel linear frequency-modulated continuous wave lidar ranging and velocity measurement system, so as to realize the simultaneous measurement of distance and velocity of multiple targets in a certain field of view without mechanical galvanometer after parallel linear frequency modulation of multiple lasers.

[0008] (II) Technical Solution

[0009] To address the aforementioned technical problems, this invention provides a parallel linear frequency modulated continuous wave lidar ranging and velocity measurement system. By performing simple linear frequency modulation and prism dispersion on lasers of different wavelengths, the system can achieve fused detection of multiple targets within a certain field of view. Parallel linear frequency modulation can also significantly improve the lidar data sampling rate. Furthermore, relying on the dispersion of the prism, the system can simultaneously expand the field of view and improve the angular resolution in mirrorless scanning mode. This avoids the problem of traditional lidar requiring scanning galvanometers for large field of view detection, which places high demands on the mechanical structure, and also improves the overall system stability.

[0010] The parallel linear frequency modulated continuous wave lidar ranging and velocity measurement system of the present invention includes: a narrow linewidth single-frequency fiber laser array 1-1 to 1-N, an N×1 wavelength division multiplexer 2, an arbitrary waveform generator 3, a microwave amplifier 4, an electro-optic modulator 5, a 1×2 fiber beam splitter 6, an EDFA amplifier 7, a circulator 8, a prism 9, a target object 10, a 2×1 fiber coupler 11, a 1×N de-wavelength division multiplexer 12, a photodetector array 13-1 to 13-N, and a data acquisition and signal processing system 14.

[0011] The narrow-linewidth single-frequency fiber laser arrays 1-1 to 1-N emit continuous laser light. Their output ports are connected to the optical signal input ports of an N×1 wavelength division multiplexer 2. The waveform output port of an arbitrary waveform generator 3 is connected to the input port of a microwave amplifier 4. The output port of the microwave amplifier 4 is connected to the microwave signal input port of an electro-optic modulator 5. The optical signal output port of the electro-optic modulator 5 is connected to the input port of a 1×2 fiber beam splitter 6. After beam splitting, the 1×2 fiber beam splitter 6 forms two output beams, one as the local oscillator and the other as the probe beam. The local oscillator beam is connected to the input port of a 2×1 fiber coupler 11, and the probe beam is connected to the input port of an EDFA amplifier 7. The output port is connected to the first port of the circulator 8. The second port of the circulator 8 is connected to the prism 9 to disperse light of different wavelengths and emit it into space to detect the target object 10. The light reflected by the target object 10 is received by the prism 9. The received light signal is output through the third port of the circulator 8 and connected to the input port of the 2×1 fiber coupler 11. The output port of the 2×1 fiber coupler 11 is connected to the input port of the 1×N dewavelength division multiplexer 12. The output port of the 1×N dewavelength division multiplexer 12 is connected to the input ports of the photodetector arrays 13-1 to 13-N respectively. The output ports of the photodetector arrays 13-1 to 13-N are connected to the data acquisition and signal processing system 14 respectively.

[0012] An array 1-1 to 1-N, consisting of N narrow-linewidth single-frequency fiber lasers with different wavelengths, emits laser light with wavelengths of λ1 to λ2 respectively. N As attached Figure 2 (a) Numbered 15-1 to 15-N. The lasers emitted from laser arrays 1-1 to 1-N are combined into a single output after passing through an N×1 wavelength division multiplexer 2 and then enter an electro-optic modulator 5. An arbitrary waveform generator 3 and a microwave amplifier 4 modulate the laser carrier through the electro-optic modulator 5 to achieve a single-sideband linear frequency modulated signal under carrier suppression. The modulated time-frequency diagram is shown in the attached figure. Figure 2 As shown in (b), the beams are labeled 16-1 to 16-N. The modulated light 16-1 to 16-N, after passing through the electro-optic modulator 5, is split into two beams by the 1×2 fiber beam splitter 6. One beam is the local oscillator beam, and the other is the probe beam. The probe beam is amplified by the EDFA amplifier 7 and then enters the first port of the fiber circulator 8. After passing through the second port of the fiber circulator 8, the probe beams of different wavelengths are dispersed by the prism 9 and emitted onto the target object 10. The probe beams of different wavelengths reflected by the target object 10 return to the prism 9, resulting in an echo signal. The time-frequency diagram of the echo signal is shown in the attached figure. Figure 2As shown in (c), the labels are 17-1 to 17-N. The echo signal enters the third port of the circulator 8 and is then mixed with the local oscillator light by the 2×1 fiber coupler 11. The output light from the 2×1 fiber coupler 11 is processed by a 1×N demultiplexer to obtain N wavelength components. These are received by a photodetector to obtain an intermediate frequency signal. After filtering and sampling, a real-time N-channel parallel fast Fourier transform is performed. The data acquisition and signal processing system 14 can then be used to simultaneously measure the N channels of distance and velocity. This invention, based on parallel linear frequency modulation and prism dispersion in lidar, can significantly improve the data acquisition rate and radar resolution. The prism dispersion can also expand the lidar's field of view and improve its angular resolution in mirrorless scanning mode. Furthermore, the parallel linear frequency modulation mode can overcome the crosstalk problem in traditional multi-field detection processes.

[0013] Furthermore, the laser emitted by the narrow linewidth single-frequency fiber lasers 1-1 to 1-N is continuous light, where N is an integer greater than or equal to 10, and the linewidth is less than 10kHz.

[0014] Furthermore: the wavelengths λ1 to λ2 of the narrow linewidth single-frequency fiber lasers 1-1 to 1-N are... N Arranged from largest to smallest, labeled 15-1 to 15-N, the wavelength array has 1550nm as the center wavelength, and the wavelength interval varies by no less than 100nm. This band is safe for the human eye and has low atmospheric transmission loss.

[0015] Furthermore, the N×1 wavelength division multiplexer 2 combines the emitted light of different wavelengths 15-1 to 15-N and outputs it as a single path.

[0016] Furthermore: the arbitrary waveform generator 3 outputs two orthogonal linear frequency modulated signals with waveforms of either triangular waves or sawtooth waves, with additional... Figure 2 Take a triangular wave as an example.

[0017] Furthermore, the microwave amplifier 4 amplifies the power of the two orthogonal linear frequency modulation signals emitted by the arbitrary waveform generator 3, thereby satisfying the input requirements of the electro-optic modulator 5 for microwave power.

[0018] Furthermore, the orthogonal linear frequency modulation signal emitted by the arbitrary waveform generator 3 is amplified by the microwave amplifier 4 to generate two orthogonal radio frequency signals, which drive the electro-optic modulator 5 to perform parallel suppression modulation on N laser carriers 15-1 to 15-N of different wavelengths. The modulated laser is a single-sideband modulated laser 16-1 to 16-N, which is composed of positive first-order sidebands or negative first-order sidebands.

[0019] Furthermore, the electro-optic modulator 5 is an IQ modulator (dual parallel Mach-Zehnder modulator). The electro-optic modulator 5 is used to perform parallel linear frequency modulation on the N emitted laser beams emitted by the narrow linewidth single-frequency fiber laser array 1-1 to 1-N, realizing single-sideband modulation under N-beam carrier suppression, denoted as 16-1 to 16-N. Compared with the Mach-Zehnder type modulator, it can achieve a larger sideband carrier suppression ratio and improve the signal-to-noise ratio of the system.

[0020] Furthermore, the bandwidths of the arbitrary waveform amplifier 3, microwave amplifier 4, and electro-optic modulator 5 are all greater than 15 GHz, wherein the arbitrary waveform generator 3 generates a triangular wave or sawtooth wave linear frequency modulated signal with a bandwidth greater than 15 GHz. The bandwidths of the photodetector arrays 13-1 to 13-N are greater than 1 GHz.

[0021] Furthermore, after being modulated by the electro-optic modulator 4, the power of the N single-sideband modulated lasers 16-1 to 16-N with different wavelengths is very weak, and the power of each wavelength component is usually less than 1mW.

[0022] Furthermore, the 1×2 fiber beam splitter 6 splits the modulated light into two beams with a power ratio of 90:10. 90% of the beam is used as the probe light, and 10% is used as the local oscillator light.

[0023] Furthermore, the EDFA amplifier 7 performs optical-to-optical amplification on the weak linear frequency modulated signals 16-1 to 16-N after passing through the 1×2 fiber beam splitter 6, and the modulated laser power of each channel after amplification is greater than or equal to 100mW.

[0024] Furthermore, the prism 9 disperses the modulated signal light 16-1 to 16-N of different wavelengths and emits it at a certain field of view as detection light. After being reflected by the target object 10, the light is incident on the prism 9 to obtain echo signals 17-1 to 17-N. The echo signals enter the receiving port of the circulator after passing through the prism. The prism 9 can also be replaced by a grating or a wedge prism.

[0025] Furthermore: the 2×1 fiber coupler 11 couples the local oscillator light 16-1~16-N and the echo signal 17-1~17-N and outputs them as a single channel.

[0026] Furthermore: the 1×N dewavelength division multiplexer 12 outputs light from the 2×1 fiber coupler 11 according to wavelength λ1~λ N It is decomposed into N outputs.

[0027] Furthermore, the parallel linear frequency modulated continuous wave lidar ranging and velocimetry system described herein does not contain any optical isolation devices. This allows the system to receive the light signal reflected from the moving object using the fiber optic circulator 8 and prism 9 after laser emission, achieving simultaneous transmission and reception and reducing system complexity.

[0028] Furthermore, the data acquisition and signal processing system 14 includes an amplifier, a low-pass filter, an analog-to-digital converter, and a processing module.

[0029] Furthermore, in the parallel linear frequency modulated continuous wave lidar ranging and velocity measurement system, apart from the prism 9 at the transmitting and receiving ends, all other components are fiber optic devices and are connected by fiber optics to facilitate handling and miniaturization of the system.

[0030] This invention utilizes an array 1-1 to 1-N composed of N narrow-linewidth single-frequency fiber lasers to perform simple linear frequency modulation and prism dispersion beam splitting, achieving parallel multi-field linear frequency modulated continuous wave lidar ranging and velocity measurement without the need for mechanical galvanometer scanning.

[0031] (III) Beneficial Effects

[0032] The parallel linear frequency modulated continuous wave lidar ranging and velocity measurement system provided by the above technical solution avoids introducing frequency modulation nonlinearity by using an arbitrary waveform generator 3, a microwave amplifier 4, and an electro-optic modulator 5 to modulate the laser carrier. Through simple parallel linear frequency modulation and prism dispersion of laser arrays of different wavelengths, the lidar data acquisition rate, image refresh rate, and field of view can be significantly improved. Parallel multi-field linear frequency modulated continuous wave laser ranging and velocity measurement can be achieved without mechanical components such as galvanometer scanning. This system provides lidar with the possibility of achieving large-scale parallel and ultra-high data acquisition. Attached Figure Description

[0033] Figure 1 This invention relates to a parallel linear frequency modulated continuous wave lidar ranging and velocity measurement system.

[0034] Figure 2 yes Figure 1 Schematic diagram of a parallel lidar ranging and velocity measurement system.

[0035] Figure 1 The following are labeled: (1) Narrow linewidth single-frequency fiber laser array, labeled 1-1 to 1-N; (2) N×1 wavelength division multiplexer; (3) Arbitrary waveform generator; (4) Microwave amplifier; (5) Electro-optic modulator; (6) 1×2 fiber beam splitter; (7) EDFA amplifier; (8) Circulator; (9) Prism; (10) Target object; (11) 2×1 fiber coupler; (12) 1×N dewavelength division multiplexer; (13) Photodetector array, labeled 13-1 to 13-N; (14) Data acquisition and signal processing system.

[0036] Figure 2The following are labeled: (a) Wavelength arrays emitted by narrow-linewidth single-frequency lasers, with wavelengths ranging from λ1 to λN and labeled 15-1 to 15-N; (b) Time-frequency diagrams of N linear frequency modulated continuous wave arrays after modulation, labeled 16-1 to 16-N; (c) Time-frequency diagrams of probe light and echo of N linear frequency modulated continuous wave arrays, with echo time-frequency labels 17-1 to 17-N. Detailed Implementation

[0037] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0038] like Figure 1 As shown, in this embodiment of the parallel linear frequency modulated continuous wave lidar ranging and velocity measurement system, there are narrow linewidth single-frequency fiber laser arrays 1-1 to 1-N, an N×1 wavelength division multiplexer 2, an arbitrary waveform generator 3, a microwave amplifier 4, an electro-optic modulator 5, a 1×2 fiber beam splitter 6, an EDFA amplifier mode, a circulator 8, a prism 9, a target object 10, a 2×1 fiber coupler 11, a 1×N de-wavelength division multiplexer 12, photodetector arrays 13-1 to 13-N, and a data acquisition and signal processing system 14.

[0039] like Figure 2 As shown in the diagram, the principle of a lidar ranging and velocity measurement system uses a triangular wave as an example. A narrow-linewidth single-frequency laser emits a wavelength array with wavelengths ranging from λ1 to λ2. N The time-frequency diagrams of the N linear frequency modulated continuous wave signal arrays are labeled 15-1 to 15-N; the time-frequency diagrams of the probe light and echo of the N linear frequency modulated continuous wave arrays are labeled 16-1 to 16-N; and the time-frequency diagrams of the echo signal are labeled 17-1 to 17-N.

[0040] The narrow-linewidth single-frequency fiber lasers 1-1 to 1-N are used to generate N wavelengths λ1 to λ2, which are eye-safe wavelengths around 1550nm. N The seed light source, after being modulated by arbitrary waveform generator 3, microwave amplifier 4, and electro-optic modulator 5, has carrier suppression in the signal. The modulated laser is a single-sideband modulated laser 16-1 to 16-N, composed of positive first-order sidebands or negative first-order sidebands.

[0041] The single-sideband modulated light output from N wavelength laser beams after passing through electro-optic modulator 5 is 16-1 to 16-N, with wavelength λ. i The positive first-order sideband intensity and negative first-order sideband intensity of the modulated laser are as follows:

[0042] f i =c / n i λ i

[0043] S + =-E i exp[j2πf i t+jθ(t)]J1(β)

[0044] S _ =-E i exp[j2πf i t-jθ(t)]J1(β)

[0045] In the formula, i takes the value of an integer from 1 to N, and E i The output wavelength of the narrow linewidth single-frequency laser array 1-1 to 1-N coupled by wavelength division multiplexer 2 is λ. i Light intensity, f i n is the carrier frequency of the laser. i For wavelength λ i The refractive index of light in the optical fiber, the carrier frequency J1(β) of the laser is a first-order Bessel function, β is the modulation depth, which is related to the bias voltage and half-wave voltage ratio of the electro-optic modulator, and θ(t) is a linear frequency modulated signal of a triangular wave or sawtooth wave emitted by an arbitrary waveform generator.

[0046] The modulated light is split into two beams by a 1×2 fiber beam splitter 6. One beam is a probe beam, used to detect the distance and speed of the moving object; the other beam is a local oscillator beam, used for coherent detection of the received echo signal. The distance and speed of the object are calculated based on the frequency difference between the echo signal 17-1~17-N and the local oscillator beam 16-1~16-N.

[0047] This system uses a prism 9 to disperse probe light of different wavelengths 16-1 to 16-N, illuminating the target object 10 with a specific field of view, and receives the echo signals 17-1 to 17-N reflected by the moving object. This achieves simultaneous transmission and reception of multiple fields of view without the need for a scanning galvanometer with mechanical structures. The moving object 10 can be selected from targets such as moving cars. It should be noted that simultaneous ranging and speed measurement can be achieved for any target within the scattering angle.

[0048] The detected echo signals 17-1 to 17-N are received by prism 9 and then pass through the third port of fiber optic circulator 8. They then enter a 2×1 fiber optic coupler with the local oscillator light 16-1 to 16-N for coherent mixing. The mixed light is then processed by a 1×N dewavelength division multiplexer 12 according to the optical wavelength λ1 to λ2. N It is decomposed into N outputs, which are then received by a photodetector to obtain the intermediate frequency signal.

[0049] Perform Fourier transforms on the received echo signal 17-i of the i-th wavelength component in the rising and falling frequency bands of the triangular wave, respectively, and obtain the two beat frequencies f. i-1 with f i-2Substitute it into the distance and velocity formula:

[0050]

[0051]

[0052] From the above formula, it is possible to simultaneously measure distance and velocity in N directions using a parallel linear frequency modulated continuous wave lidar, and obtain the horizontal angle information of the i-th ranging target. In the formula, T is the modulation period of the linear frequency modulated triangular wave signal, B is the modulation bandwidth of the linear frequency modulated signal, and λ... i Let θ be the center wavelength of the i-th laser emission from a narrow-linewidth single-frequency fiber laser array 1-1 to 1-N. i For the wavelength λ of the prism i The dispersion angle, also known as the horizontal angle of the target object, is shown in the attached figure. Figure 1 As shown.

[0053] The intermediate frequency signals obtained from the above N-channel parallel linear frequency modulation transmission / reception are filtered and sampled, and then subjected to real-time N-channel parallel fast Fourier transform. The data acquisition and signal processing system is used to realize the synchronous measurement of distance and speed of the N channels.

[0054] The detection field of view of this invention is the difference between the minimum wavelength and the maximum wavelength after dispersion by a prism.

[0055] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A parallel linear frequency modulated continuous wave lidar ranging and velocity measurement system, characterized in that, include: Narrow linewidth single-frequency fiber laser array (1-1~1-N), N×1 wavelength division multiplexer (2), arbitrary waveform generator (3), microwave amplifier (4), electro-optic modulator (5), 1×2 fiber beam splitter (6), EDFA amplifier (7), circulator (8), prism (9), target object (10), 2×1 fiber coupler (11), 1×N dewavelength division multiplexer (12), photodetector array (13-1~13-N), data acquisition and signal processing system (14). The narrow-linewidth single-frequency fiber laser array (1-1~1-N) emits laser light, and its output port is connected to the optical signal input port of the N×1 wavelength division multiplexer (2). The waveform output port of the arbitrary waveform generator (3) is connected to the input port of the microwave amplifier (4). The output port of the microwave amplifier (4) is connected to the microwave signal input port of the electro-optic modulator (5). The optical signal output port of the electro-optic modulator (5) is connected to the input port of the 1×2 fiber beam splitter (6). After splitting, the 1×2 fiber beam splitter (6) forms two output beams, one of which is used as the local oscillator beam and the other as the probe beam. The local oscillator beam is connected to the input port of the 2×1 fiber coupler (11), and the probe beam is connected to the input port of the EDFA amplifier (7). The output port of the EDFA amplifier (7) is... The first port of the circulator (8) is connected to the second port of the circulator (8) and the second port of the circulator (8) is connected to the prism (9). The light of different wavelengths is dispersed and emitted into space to detect the target object (10). The light reflected by the target object (10) is received by the prism (9). The received light signal is output through the third port of the circulator (8) and connected to the input port of the 2×1 fiber coupler (11). The output port of the 2×1 fiber coupler (11) is connected to the input port of the 1×N dewavelength division multiplexer (12). The output port of the 1×N dewavelength division multiplexer (12) is connected to the input port of the photodetector array (13-1~13-N). The output port of the photodetector array (13-1~13-N) is connected to the data acquisition and signal processing system (14). The narrow-linewidth single-frequency fiber laser array (1-1~1-N) emits laser light with wavelengths of λ1~λ2 respectively. N The lasers emitted by the laser array (1-1~1-N) are combined into a single output after passing through an N×1 wavelength division multiplexer (2) and then enter the electro-optic modulator (5). The arbitrary waveform generator (3) and the microwave amplifier (4) modulate the laser carrier through the electro-optic modulator (5) to realize a single-sideband linear frequency modulation signal under carrier suppression. The modulated light (16-1~16-N) after passing through the electro-optic modulator (5) is split into two beams after passing through a 1×2 fiber beam splitter (6), one of which is the local oscillator light and the other is the probe light. The probe light is amplified by the EDFA amplifier (7) and then enters the first port of the fiber circulator (8). After passing through the second port of the fiber circulator (8), The prism (9) disperses the probe light of different wavelengths and emits it onto the target object (10). The probe light of different wavelengths reflected by the target object (10) returns to the prism (9) and generates echo signals (17-1~17-N). The echo signals (17-1~17-N) enter the third port of the circulator (8) and are output to be mixed with the local oscillator light into the 2×1 fiber coupler (11). The output light of the 2×1 fiber coupler (11) is processed by a 1×N dewavelength division multiplexer to obtain light with N wavelength components. The intermediate frequency signal is received by the photodetector and after filtering and sampling, it is subjected to real-time N-channel parallel fast Fourier transform. The data acquisition and signal processing system (14) is used to realize the synchronous measurement of N-channel distance and speed. In the modulated light (16-1~16-N) after passing through the electro-optic modulator (5), the wavelength is λ i The positive first-order sideband intensity and negative first-order sideband intensity of the modulated laser are as follows: In the formula, i The value of is an integer from 1 to N. The output wavelength of the narrow linewidth single-frequency fiber laser array (1-1~1-N) coupled by wavelength division multiplexer (2) is λ. i Light intensity, The carrier frequency of the laser. For wavelength λ i The refractive index of light in the optical fiber, the carrier frequency of the laser. It is a first-order Bessel function. The modulation depth is related to the bias voltage and half-wave voltage ratio of the electro-optic modulator (5). A linear frequency modulated signal, such as a triangular wave or a sawtooth wave, generated by an arbitrary waveform generator; For the first i The echo signal 17-i received by the light of each wavelength component is subjected to Fourier transform in the rising and falling frequency bands of the triangular wave, respectively, and the two beat frequencies are... and Substitute it into the distance and velocity formula: Based on the above formula, the parallel linear frequency modulated continuous wave lidar method achieves simultaneous ranging and velocity measurement in N directions, obtaining the horizontal angle information of the i-th ranging target; where, The modulation period of the linear frequency modulated signal of the triangular wave is . The modulation bandwidth of the linear frequency modulated signal. For the narrow linewidth single-frequency fiber laser array (1-1~1-N) i The center wavelength of the laser emission, For the wavelength of the prism The dispersion angle, which is also the horizontal angle of the target object.

2. The parallel linear frequency modulated continuous wave lidar ranging and velocity measurement system as described in claim 1, characterized in that, The laser emitted by the narrow linewidth single-frequency fiber laser (1-1~1-N) is continuous light, where N is an integer greater than or equal to 10, and the linewidth is less than 10 kHz.

3. The parallel linear frequency modulated continuous wave lidar ranging and velocity measurement system as described in claim 2, characterized in that, The arbitrary waveform generator (3) emits two orthogonal linear frequency modulation signals with waveforms of triangular waves or sawtooth waves.

4. The parallel linear frequency modulated continuous wave lidar ranging and velocity measurement system as described in claim 3, characterized in that, The orthogonal linear frequency modulation signal emitted by the arbitrary waveform generator (3) is amplified by the microwave amplifier (4) to generate two orthogonal radio frequency signals, which drive the electro-optic modulator (5) to perform parallel suppression modulation on N laser carriers (15-1~15-N) of different wavelengths. The modulated laser is a single-sideband modulated laser (16-1~16-N), which is composed of positive first-order sidebands or negative first-order sidebands.

5. The parallel linear frequency modulated continuous wave lidar ranging and velocity measurement system as described in claim 4, characterized in that, The electro-optic modulator (5) is an IQ modulator. The electro-optic modulator (5) performs parallel linear frequency modulation on the N emitted laser beams emitted by the narrow linewidth single-frequency fiber laser array (1-1~1-N) to achieve single-sideband modulation under N-beam carrier suppression.

6. The parallel linear frequency modulated continuous wave lidar ranging and velocity measurement system as described in claim 5, characterized in that, The bandwidth of the arbitrary waveform generator (3), microwave amplifier (4), and electro-optic modulator (5) is greater than 15 GHz, and the bandwidth of the photodetector array (13-1~13-N) is greater than 1 GHz.

7. The parallel linear frequency modulated continuous wave lidar ranging and velocity measurement system as described in claim 6, characterized in that, The 1×2 fiber beam splitter (6) splits the modulated light into two beams with a power ratio of 90:10, of which 90% of the beam is used as the probe light and 10% of the beam is used as the local oscillator light.

8. The parallel linear frequency modulated continuous wave lidar ranging and velocity measurement system as described in claim 7, characterized in that, The EDFA amplifier (7) performs optical-to-optical amplification on the weak linear frequency modulated signal (16-1~16-N) after passing through the 1×2 fiber beam splitter (6), and the modulated laser power of each channel after amplification is greater than or equal to 100 mW.

9. The parallel linear frequency modulated continuous wave lidar ranging and velocity measurement system as described in claim 8, characterized in that, The 2×1 fiber coupler (11) couples the local oscillator light (16-1~16-N) and the echo signal (17-1~17-N) and outputs them as a single channel; the 1×N dewavelength division multiplexer (12) divides the output light of the 2×1 fiber coupler (11) into wavelengths λ1~λ2. N It is decomposed into N outputs.

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