Frequency modulation continuous wave laser measurement method and system

Abstract

The invention provides a laser measurement method and system, and relates to the field of laser radar measurement. The method comprises the following steps: generating a frequency sweeping light beam; the sweep-frequency light beam is divided into a signal light beam and a local oscillator light beam; transmitting a signal light beam and obtaining a reflected light beam; performing frequency mixing on the local oscillation light beam and the reflection light beam; acquiring a beat frequency electric signal; sampling the beat frequency electric signal to obtain a first sampling signal sequence; generating a complex signal sequence according to the first sampling signal sequence; sampling the complex signal sequence to obtain a second sampling signal sequence; and generating a target beat frequency according to the first sampling signal sequence and the second sampling signal sequence. According to the scheme of the invention, the frequency resolution of the beat frequency signal can be improved under the condition that the modulation depth and the sweep frequency period are not changed, and the measurement precision of laser measurement is improved.

Description

Technical Field

[0001] The present invention relates to the field of laser radar measurement, and in particular to a frequency modulated continuous wave laser measurement method and system. Background Art

[0002] Frequency-Modulated Continuous Wave (FMCW) laser radar obtains the position (distance and angle), motion state (speed, vibration and posture) and other information of the target object based on the beat frequency signal between the local oscillator signal and the reflected signal. When obtaining information such as the distance and speed of the target object, the relevant ranging method needs to perform fast Fourier transform (FFT) on the beat frequency signal. The ranging accuracy is limited by the sampling rate of the fast Fourier transform, and high-precision ranging cannot be achieved. Summary of the invention

[0003] In view of this, the present invention provides a frequency modulated continuous wave laser measurement method and system to solve the technical problem that related laser measurement methods are limited by the sampling rate of fast Fourier transform and cannot achieve high-precision laser measurement.

[0004] In a first aspect, the present application provides a frequency modulated continuous wave laser measurement system, the laser measurement system comprising: a laser source configured to generate a swept frequency beam; a spectrometer configured to divide the swept frequency beam into a signal beam; a laser source configured to generate a swept frequency beam; a spectrometer configured to divide the swept frequency beam into a signal beam and a local oscillator beam; an optical transceiver configured to transmit the signal beam and obtain a reflected beam generated by the signal beam on a target object; a mixer configured to mix the local oscillator beam and the reflected beam of the frequency modulated continuous wave laser; a balanced detector configured to obtain a beat frequency electrical signal between the local oscillator beam and the reflected beam; a beat frequency acquirer configured to obtain the beat frequency electrical signal from the balanced detector; a first sampler configured to sample the beat frequency electrical signal to obtain a first sampling signal sequence; a complex exponential signal generator configured to generate a complex signal sequence according to the first sampling signal sequence; a second sampler configured to sample the complex signal sequence to obtain a second sampling signal sequence; and a frequency synthesizer configured to generate a target beat frequency according to the first sampling signal sequence and the second sampling signal sequence.

[0005] Optionally, the frequency modulated continuous wave laser measurement system also includes: a first Fourier transformer, configured to perform a first fast Fourier transform on the first sampling signal sequence to obtain a first target frequency; wherein the complex exponential signal generator is configured to generate a complex exponential signal, multiply the complex exponential signal with the first sampling signal sequence to obtain the complex signal sequence.

[0006] Optionally, the frequency modulated continuous wave laser measurement system further includes: a first low-pass filter configured to perform low-pass filtering on the complex signal sequence; wherein the second sampler is specifically configured to sample the complex signal sequence after low-pass filtering to obtain the second sampled signal sequence.

[0007] Optionally, the frequency modulated continuous wave laser measurement system further includes: a second Fourier transformer configured to perform a second fast Fourier transform on the second sampling signal sequence to obtain a second target frequency.

[0008] Optionally, the frequency synthesizer is configured to add the first target frequency and the second target frequency to generate a target beat frequency.

[0009] In a second aspect, the present application provides a frequency modulated continuous wave laser measurement method, which includes: generating a swept frequency beam; dividing the swept frequency beam into a signal beam and a local oscillator beam; emitting the signal beam and obtaining a reflected beam generated by the signal beam on a target object; optically mixing the local oscillator beam and the reflected beam; obtaining a beat frequency electrical signal between the local oscillator beam and the reflected beam of the frequency modulated continuous wave laser; sampling the beat frequency electrical signal to obtain a first sampling signal sequence; generating a complex signal sequence based on the first sampling signal sequence; sampling the complex signal sequence to obtain a second sampling signal sequence; and generating a target beat frequency based on the first sampling signal sequence and the second sampling signal sequence.

[0010] Optionally, the frequency modulated continuous wave laser measurement method also includes: before generating the complex signal sequence, performing a first fast Fourier transform on the first sampling sequence to obtain a first target frequency; wherein, generating a complex signal sequence based on the first sampling signal sequence includes: generating a complex exponential signal; multiplying the complex exponential signal with the first sampling signal sequence to obtain the complex signal sequence.

[0011] Optionally, the frequency modulated continuous wave laser measurement method further includes: before sampling the complex signal sequence, low-pass filtering the complex signal sequence; sampling the complex signal sequence after low-pass filtering to obtain the second sampling signal sequence.

[0012] Optionally, the frequency modulated continuous wave laser measurement method further includes: performing a second fast Fourier transform on the second sampling signal sequence to obtain a second target frequency.

[0013] Optionally, the frequency modulated continuous wave laser measurement method further includes: adding the first target frequency and the second target frequency to generate a target beat frequency.

[0014] In a third aspect, the solution of the present application provides an autonomous mobile device, which includes the frequency modulated continuous wave laser measurement system of the above first aspect.

[0015] The solution of the present application can improve the frequency resolution of the beat frequency signal without changing the modulation depth and the sweep frequency period, thereby improving the measurement accuracy of the laser measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the structure of a continuous wave laser radar of the present application is shown;

[0017] Figure 2A The schematic diagram of measuring a stationary object using an existing triangular wave linear frequency modulation continuous wave laser radar is shown;

[0018] Figure 2B The schematic diagram of measuring a moving object using an existing triangular wave linear frequency modulation continuous wave laser radar is shown;

[0019] Figure 3 A flow chart of the laser measurement method of the present application is shown;

[0020] Figure 4A A schematic diagram of the structure of a laser radar used in the laser measurement system of the present application is shown;

[0021] Figure 4B A schematic diagram of the structure of the laser measurement system of the present application is shown;

[0022] Figure 5A and Figure 5B A schematic diagram of an autonomous vehicle including the laser measurement system of the present application is shown. DETAILED DESCRIPTION

[0023] Below, the specific embodiments of the present application will be described in detail in conjunction with the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. In the following exemplary embodiments, the described embodiments are not all embodiments of the present application. On the contrary, they are only examples of devices and methods consistent with some aspects of the present application as detailed in the attached claims. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0024] refer to Figure 1 , Figure 1It is a schematic diagram of the structure of the frequency-modulated continuous wave (FMCW) laser radar of the present application. The FMCW laser radar 1 of the present application adopts the working principle of coherent reception. By comparing the instantaneous beat frequency relationship between the reflected light beam reflected from the target object 2 and the local oscillator light beam of the laser radar 1, information such as the distance between the target object 2 and the laser radar 1 and the speed of the target object can be given at the same time.

[0025] refer to Figure 2A , Figure 2A The schematic diagram of the FMCW laser radar using a triangular wave linear frequency modulation to measure a stationary object is shown. Figure 2A In the figure, the solid triangle wave is the instantaneous time-frequency relationship of the radar signal beam or local oscillator beam, and the dotted triangle wave is the instantaneous time-frequency relationship of the reflected beam of the stationary target object, where τ is the delay of the reflected beam of the stationary target object, and f 1 、f 2 are the beat frequencies of the reflected beam of the stationary object in the up-sweep part and the down-sweep part (i.e., the beat frequency in the up-sweep stage and the beat frequency in the down-sweep stage between the reflected beam and the local oscillator beam), T is a cycle formed by a complete up-sweep and down-sweep, f B It is the sweep bandwidth of the linear frequency modulation (i.e. modulation depth). Figure 2A In the above example, the beat frequencies of the reflected light beam in the up-conversion stage and the down-conversion stage are:

[0026]

[0027]

[0028] Assuming the distance between the target object and the laser radar is R, then R = τ*c / 2, where c is the speed of light and λ is the laser wavelength. Figure 2A In the time-frequency relationship diagram, the relationship between the beat frequency of the reflected light beam in the up-conversion phase and the beat frequency in the down-conversion phase and the distance between the target object and the laser radar is shown in the following formula 2:

[0029]

[0030] Figure 2B The schematic diagram shows the principle of measuring an object moving towards the direction of the laser radar using an FMCW laser radar with a related triangle wave modulation. Figure 2B In the figure, the solid triangle wave is the instantaneous time-frequency relationship of the radar signal beam or local oscillator beam, and the dotted triangle wave is the reflected beam of the target object moving towards the direction of the lidar, where τ is the delay of the reflected beam of the target object, and f 1 、f 2are the beat frequencies of the reflected light beam of the target object in the upper sweep part and the lower sweep part, T is the period of the upper sweep and the lower sweep, and f B is the sweep bandwidth of the linear frequency modulation, f d =(f 2 -f 1 ) / 2. Figure 2B In the above example, the beat frequencies of the reflected light beam in the up-conversion stage and the down-conversion stage are:

[0031]

[0032]

[0033] The distance R and speed ν of the target object are as follows:

[0034]

[0035] When using the above formula 2 and formula 4 to calculate the distance R and speed ν of the target object, it is necessary to use the beat frequency f in the upscaling stage 1 and the beat frequency f in the frequency reduction stage 2 The beat frequency f in the upconversion stage 1 and the beat frequency f in the frequency reduction stage 2 is the intermediate frequency signal. When the signal processing method is used to adjust the beat frequency f in the frequency upscaling stage, 1 and the beat frequency f in the frequency reduction stage 2 When performing analog-to-digital conversion (ADC), discrete sampling, and fast Fourier transform (FFT), the resolution of the fast Fourier transform (FFT) determines the accuracy of the frequency resolution that can be obtained. For example, when the sampling frequency is f s , the number of sampling points is N (N is a positive integer), the sampling time is T / 2, and the sampling time interval is t s =1 / f s , the frequency resolution can be expressed as:

[0036]

[0037] The distance resolution can be expressed as

[0038]

[0039] Therefore, the method of improving the ranging accuracy (i.e. reducing ΔR) can be achieved by increasing f B Or reduce Δf to achieve. This application improves the ranging accuracy by reducing Δf without changing the modulation depth f B .

[0040] In this application, frequency resolution refers to the ability to separate two adjacent spectrum peaks on the spectrum by performing Fourier transform on the intermediate frequency digital signal. In practical applications, it refers to the minimum interval for distinguishing two signals of different frequencies.

[0041] In some embodiments, the present disclosure provides a laser measurement method. The laser measurement method can be applied to frequency modulated continuous wave (FMCW) laser radar, such as Figure 3 As shown, the laser measurement method includes the following steps S301-S305.

[0042] Step S301: Generate a frequency-sweeping light beam.

[0043] Specifically, the swept frequency beam can be generated by a laser light source. The laser light source can be directly modulated by a chirp signal drive of an optical signal. For example, a driving signal for controlling the laser light source can be input to the laser light source with an intensity that varies with time, so that the laser light source generates and outputs a swept frequency beam, i.e., a beam whose frequency varies within a predetermined range.

[0044] In some embodiments, the laser light source may further include a modulator that receives a modulation signal. The modulator may be configured to modulate the light beam based on the modulation signal to generate and output a frequency-sweeping light beam, the frequency of which varies within a predetermined range, and the frequency-sweeping light beam may have a triangular waveform or a sawtooth waveform, as shown in FIG2 . The principle of generating a frequency-sweeping light beam by an FMCW laser radar is well known to those skilled in the art. In order to save space, this article will not be further described here.

[0045] Step S302: Splitting the frequency-sweeping beam into a signal beam and a local oscillator beam.

[0046] In some examples, a beam splitter may be used to split the swept frequency beam into a signal beam and a local oscillator beam. The signal beam and the local oscillator beam have the same frequency at any point in time, that is, the frequency modulation waveforms of the signal beam and the local oscillator beam are exactly the same. In some examples, the beam splitter may be a specific wavelength coupler (splitter) for wavelengths of 445 to 2100 nm, such as a 1X2 beam splitter on an optical chip and a beam splitter of the SMC series. In other examples, other beam splitters known to those skilled in the art that can split the swept frequency beam into a signal beam and a local oscillator beam may also be used.

[0047] Step S303: emitting the signal light beam, and receiving a reflected light beam generated when the signal light beam encounters a target object.

[0048] In some examples, an optical transmitter and receiver or an optical transceiver is used to emit the signal light beam at a predetermined angle, and a light receiver or the optical transceiver is used to receive a reflected light beam reflected by a target object.

[0049] Step S304: Mix the local oscillator light beam and the reflected light beam to obtain an optical mixing signal between the local oscillator light beam and the reflected light beam.

[0050] Specifically, the received reflected light beam is optically mixed with the local oscillator light beam to obtain an optical mixing signal. An optical mixer can be used for optical mixing. The mixer can be a coupler, such as a 2×2 optical coupler, and the mixing signal is a coherent signal generated by the interference between the local oscillator light beam and the corresponding reflected light beam. The mixer or coupler can be a mixer and a coupler well known to those skilled in the art. In order to save space, this application will not be described in detail.

[0051] Step S305: Acquire the beat frequency electrical signal between the local oscillator light beam and the reflected light beam.

[0052] Specifically, the beat frequency electrical signal may include a beat frequency electrical signal in a frequency increasing stage and a beat frequency electrical signal in a frequency decreasing stage. The beat frequency electrical signal in the frequency increasing stage and the beat frequency electrical signal in the frequency decreasing stage are intermediate frequency signals.

[0053] Specifically, a balanced detector can be used to measure the beat frequency of the local oscillator light beam and the reflected light beam. The balanced detector can be a photoelectric detector.

[0054] Step S306: performing analog-to-digital conversion (ADC) and sampling on the beat frequency signal in the frequency up-conversion phase and the beat frequency electrical signal in the frequency down-conversion phase to obtain a sampling sequence x[n].

[0055] Specifically, the beat frequency signal in the frequency-up phase and the beat frequency electrical signal in the frequency-down phase are respectively subjected to ADC and first sampling to obtain a first sampling sequence x 1 [n] and the second sampling sequence x 2 [n] In this application, for the first sampling sequence x 1 [n] and the second sampling sequence x 2 The processing method and principle of [n] are the same, and are described as sampling sequence x[n] in the following description of this application.

[0056] In some examples, the sampling frequency is f s , the number of sampling points is N, N is a positive integer. Therefore, the sampling sequence x[n] is obtained, n = 0, 1, ..., N-1. In this case, the initial frequency resolution of the sampled signal is

[0057]

[0058] Step S307: Perform the first FFT transformation on the sampling sequence x[n] to obtain the first target frequency f 0 ,

[0059]

[0060] Specifically, the first target frequency above can be selected as the frequency center, and the frequency range to be further processed can be selected as (f 0 -Δf,f 0+Δf).

[0061] Step S308: Generate a unit complex exponential signal The unit complex exponential signal Multiply it with the sampling sequence x[n] to convert the real signal sequence into a complex signal sequence.

[0062] Specifically, by transforming the unit complex exponential signal Multiply by the sample sequence x[n] Change the center frequency of the sampling signal from the first target frequency f 0 Move to zero frequency.

[0063] Step S309: low-pass filtering the complex signal sequence using a low-pass anti-aliasing filter to filter out high-frequency components.

[0064] The specific content and parameters of the low-pass anti-aliasing filter can refer to the relevant technology, and this application will not be described in detail here. The parameters of the low-pass anti-aliasing filter can be designed according to actual needs. Optionally, the parameter design of the low-pass anti-aliasing filter needs to filter out high-frequency components that exceed more than half of the sampling frequency.

[0065] Step S310: Sampling the low-pass filtered signal sequence for the second time to obtain a new signal sequence

[0066] Specifically, the sampling frequency of the second sampling can be Where M is the multiple by which the frequency of the low-pass filtered signal sequence is refined as needed. M can be an integer multiple of 2 M = 1, 2, 4..., 2 m , that is, the value of M can be selected to refine the frequency resolution by M times, thereby increasing the distance resolution that the FMCW laser radar can detect by M times (see Formula 6). The new signal sequence x after the second sampling c (n) includes N / M discrete signals.

[0067] Step S311: Expand the N / M discrete signals and expand the number of sampling points to N.

[0068] Specifically, the sampling points of the N / M discrete signals can be supplemented by interpolation or zero padding. The interpolation and zero padding methods can refer to the interpolation or zero padding methods used by ordinary technicians in the field of digital signal processing. The frequency resolution of the expanded N discrete signals is

[0069]

[0070] Step S312: Perform a second FFT transformation on the expanded N discrete signals to obtain a second target frequency f 1 .

[0071] Among them, f 1 =b*Δf x ,b∈(-M,M) is an integer.

[0072] Step S313: Set the first target frequency f 0 and the second target frequency f 1 Add together to obtain the refined target signal frequency f beat

[0073] f beat =f 0 +f 1 =a*Δf+b*Δf x =(a*M+b)*Δf x Formula 9

[0074] Step S314: Using the obtained refined target frequency f beat The distance and speed of the target object are calculated according to Formula 3 and Formula 4.

[0075] Through the above method, the spectrum resolution is refined by M times, and the ranging resolution is improved by M times. The solution of the present application can improve the frequency resolution of the beat frequency signal without changing the modulation depth and the sweep frequency period, thereby improving the calculation accuracy of the ranging.

[0076] Figure 4A The schematic diagram of the structure of the FMCW laser radar of the present application is shown. In this embodiment, the laser radar includes a laser light source 401, which is configured to generate a swept frequency beam, and the swept frequency beam can be a swept frequency beam with a triangular waveform or a swept frequency beam with a sawtooth waveform; and a beam splitter 402, which is configured to split the swept frequency beam into a signal beam and a local oscillator beam.

[0077] Specifically, the laser light source 401 can be driven by a chirp signal of an optical signal for direct modulation. For example, a driving signal for controlling the laser light source 401 can be input to the laser light source 401 with an intensity that varies with time, so that the laser light source 401 generates and outputs a swept frequency beam, that is, a beam whose frequency varies within a predetermined range. The laser light source 401 may also include a modulator that receives a modulation signal. The modulator may be configured to modulate the light beam based on the modulation signal to generate and output a swept frequency beam, the frequency of which varies within a predetermined range. The laser light source 401 may be a laser source commonly used in FMCW laser radars, and in order to save space, this application will not be described in detail.

[0078] The optical splitter 402 is configured to split the swept frequency beam into a signal beam and a local oscillator beam. The signal beam and the local oscillator beam have the same frequency at any time point, that is, the frequency modulation waveforms of the signal beam and the local oscillator beam are exactly the same. In some examples, the optical splitter 402 can be specifically a specific wavelength coupler (optical splitter) for wavelengths of 445 to 2100 nm, such as an SMC series optical splitter. In other examples, other optical splitters known to those skilled in the art that can split the swept frequency beam into a signal beam and a local oscillator beam can also be used.

[0079] The laser radar also includes: an optical transceiver 403, configured to transmit a signal light beam, and receive a reflected light beam generated by the signal light beam reflecting from a target object 404; a mixer 405, configured to couple the local oscillator light beam and the reflected light beam and output the coupled light beam to a balanced detector 406; the balanced detector 406, configured to detect and obtain an electrical signal of the beat frequency in the up-conversion phase and the beat frequency in the down-conversion phase between the local oscillator light beam and the reflected light beam, and output the obtained beat frequency electrical signal to a signal processing device 407; and the signal processing device 407, configured to refine the beat frequency, thereby obtaining a refined target beat frequency.

[0080] refer to Figure 4B The signal processing device 407 specifically includes: a beat frequency acquirer 4071, configured to acquire the beat frequency electrical signal between the local oscillator beam and the reflected beam of the frequency modulated continuous wave FMCW laser radar from the balanced detector 406; a first sampler 4072, configured to sample the beat frequency electrical signal to obtain a first sampling signal sequence x[n]; a complex exponential signal generator 4073, configured to generate a complex signal sequence according to the first sampling signal sequence x[n] The second sampler 4074 is configured to sample the complex signal sequence Sampling is performed to obtain a second sampling signal sequence The frequency synthesizer 4075 is configured to generate a target beat frequency f for the first sampling signal sequence and the second sampling signal sequence. beat =f 0 +f 1 =a*Δf+b*Δf x =(a*M+b)*Δf x .

[0081] Optionally, the signal processing device 407 further includes: a first Fourier transformer 4076, configured to perform a first fast Fourier transform on the first sampling sequence x[n] to obtain a first target frequency f 0 ; Wherein the complex exponential signal generator 4073 is configured to generate a complex exponential signal The complex exponential signal Multiply the complex signal sequence x[n] by the first sampling signal sequence x[n] to obtain the complex signal sequence

[0082] Optionally, the signal processing device 407 further includes: a first low-pass filter 4077 configured to process the complex signal sequence low-pass filtering; wherein the second sampler 4074 is specifically configured to perform low-pass filtering on the complex signal sequence Sampling is performed to obtain the second sampling signal sequence x c (n).

[0083] Optionally, the signal processing device 407 further includes: a second Fourier transformer 4078 configured to transform the second sampling signal sequence x c (n) Perform a second fast Fourier transform to obtain a second target frequency f 1 , f 1 =b*Δf x , b∈(-M,M).

[0084] Optionally, the frequency synthesizer 4075 is configured to convert the first target frequency f 0 and the second target frequency f 1 Add together to generate the target beat frequency f beat =f 0 +f 1 =a*Δf+b*Δf x =(a*M+b)*Δf x ,

[0085] Optionally, the signal processing device 407 further includes: a processing device 4076 configured to obtain a target beat frequency f from the frequency synthesizer 4075 beat , and use the target beat frequency f beat Calculate the distance and speed of the target object.

[0086] The device of the present application can implement the relevant steps of the above method embodiment. The same description can be found in the relevant description of the above method. In order to save space, the present application will not repeat the description here.

[0087] Figure 5A and Figure 5B An example autonomous vehicle 500 according to an embodiment of the present application is illustrated, which may include any of the components of the LIDAR device shown in FIG4 of the present application. The autonomous vehicle 500 shown includes a sensor array configured to capture one or more objects of the external environment of the autonomous vehicle and generate sensor data related to the captured one or more objects for controlling the operation of the autonomous vehicle 500. Figure 5A Sensors 501 , 502 , 503 , 504 , 505 , 506 , 507 , 508 , and 509 are illustrated. Figure 5B Shown is a top view of an autonomous vehicle 500. Any one of sensors 501, 502, 503, 504, 505, 506, 507, 508, and 509 may include the laser radar device shown in FIG. 4 of the present application, which includes any LIDAR component of FIG. 4. The autonomous vehicle may include a powertrain including a prime mover powered by an energy source and capable of providing power to a transmission system. The autonomous vehicle may also include a control system including direction control, powertrain control, and brake control. The autonomous vehicle may be implemented as any number of different vehicles, including vehicles capable of transporting people and / or cargo and capable of traveling in a variety of different environments. It should be understood that the above-mentioned components can vary widely based on the type of vehicle utilizing these components.

[0088] The details of this embodiment of the present invention can be referred to the description of the aforementioned method embodiment. To avoid repetition, the present invention will not be described again here.

[0089] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

Claims

1. A frequency modulated continuous wave laser measurement system, characterized in that: The frequency modulated continuous wave laser measurement system comprises: a laser source configured to generate a swept beam; A beam splitter configured to split the frequency-sweeping beam into a signal beam and a local oscillator beam; an optical transceiver configured to transmit the signal light beam and obtain a reflected light beam generated by the signal light beam on a target object; A mixer configured to perform optical mixing between the local oscillator beam and the reflected beam of the frequency modulated continuous wave laser; A balanced detector configured to obtain a beat frequency electrical signal between the local oscillator light beam and the reflected light beam; a beat frequency acquirer, configured to obtain the beat frequency electrical signal from the balanced detector; A first sampler is configured to sample the beat frequency electrical signal to obtain a first sampling signal sequence; a complex exponential signal generator, configured to generate a complex signal sequence according to the first sampling signal sequence; A second sampler is configured to sample the complex signal sequence to obtain a second sampled signal sequence; A frequency synthesizer is configured to generate a target beat frequency according to the first sampling signal sequence and the second sampling signal sequence.

2. The frequency modulated continuous wave laser measurement system according to claim 1, characterized in that: The frequency modulated continuous wave laser measurement system also includes: a first Fourier transformer configured to perform a first fast Fourier transform on the first sampling sequence to obtain a first target frequency; The complex exponential signal generator is configured to generate a complex exponential signal, and multiply the complex exponential signal by the first sampling signal sequence to obtain the complex signal sequence.

3. The frequency modulated continuous wave laser measurement system according to claim 2, characterized in that: The frequency modulated continuous wave laser measurement system also includes: A first low-pass filter, configured to perform low-pass filtering on the complex signal sequence; The second sampler is specifically configured to sample the complex signal sequence that has been low-pass filtered to obtain the second sampled signal sequence.

4. The frequency modulated continuous wave laser measurement system according to claim 3, characterized in that: The frequency modulated continuous wave laser measurement system also includes: The second Fourier transformer is configured to perform a second fast Fourier transform on the second sampling signal sequence to obtain a second target frequency.

5. The frequency modulated continuous wave laser measurement system according to claim 4, characterized in that: The frequency synthesizer is configured to add the first target frequency and the second target frequency to generate a target beat frequency.

6. A frequency modulated continuous wave laser measurement method, characterized in that: The frequency modulated continuous wave laser measurement method comprises: generating a swept beam; Splitting the frequency-sweeping beam into a signal beam and a local oscillator beam; emitting the signal light beam and obtaining a reflected light beam generated by the signal light beam on a target object; Performing optical mixing on the local oscillator light beam and the reflected light beam; Acquiring a beat frequency electrical signal between the local oscillator beam and the reflected beam of the frequency modulated continuous wave laser; Sampling the beat frequency electrical signal to obtain a first sampling signal sequence; generating a complex signal sequence according to the first sampling signal sequence; Sampling the complex signal sequence to obtain a second sampled signal sequence; A target beat frequency is generated according to the first sampling signal sequence and the second sampling signal sequence.

7. The frequency modulated continuous wave laser measurement method according to claim 6, characterized in that: The frequency modulated continuous wave laser measurement method further comprises: Before generating the complex signal sequence, the first sampling signal sequence is subjected to a first fast Fourier transform to obtain a first target frequency; The step of generating a complex signal sequence according to the first sampling signal sequence includes: Generate complex exponential signals; The complex exponential signal is multiplied by the first sampling signal sequence to obtain the complex signal sequence.

8. The frequency modulated continuous wave laser measurement method according to claim 6, characterized in that: The frequency modulated continuous wave laser measurement method further comprises: Before sampling the complex signal sequence, low-pass filtering the complex signal sequence; The complex signal sequence that has been subjected to low-pass filtering is sampled to obtain the second sampled signal sequence.

9. The frequency modulated continuous wave laser measurement method according to claim 8, characterized in that: The frequency modulated continuous wave laser measurement method further comprises: Perform a second fast Fourier transform on the second sampling signal sequence to obtain a second target frequency.

10. The frequency modulated continuous wave laser measurement method according to claim 9, characterized in that: The frequency modulated continuous wave laser measurement method further includes: adding the first target frequency and the second target frequency to generate a target beat frequency.

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