Broadband high-power linear frequency modulation laser radar

Abstract

The utility model discloses a broadband high-power linear frequency modulation laser radar, and solves the problems that the measurement range of the conventional laser radar is limited and the measurement precision is low in practical application. Linear frequency modulation is carried out on the main oscillator VCO through triangular waves, fixed frequency selection is carried out on the local oscillator VCO through direct current level signals, phase synchronization is carried out on the main oscillator VCO and the local oscillator VCO through narrow pulse signals, frequency mixing is carried out on linear frequency modulation signals and fixed frequency signals, and reference signals are obtained after low-pass sampling; a return signal and a fixed frequency signal are subjected to frequency mixing, a difference frequency signal is obtained after passing through a frequency selection network, the difference frequency signal is collected through a multi-channel synchronous sampling ADC and sent to an external DSP processing circuit for data processing, and distance information can be calculated more accurately.

Description

Technical Field

[0001] The utility model relates to a laser radar, in particular to a broadband high-power linear frequency modulation laser radar. Background Art

[0002] With the continuous development and improvement of my country's scientific and technological level, high-precision radar sensors are no longer limited to military, aerospace, aviation and other large-scale industrial fields, but have gradually expanded to various fields such as civil industrial production, intelligent manufacturing, drone control, warehousing and logistics, smart home products, intelligent driving, unmanned driving, assisted driving and big data optimization. These radar sensors usually work in traditional electromagnetic wave technology radars in the millimeter wave band or micron wave band and laser radars working in the near-infrared band. Compared with millimeter wave radar and micron wave radar, laser radar has the advantages of high precision, small beam angle, and difficult to be detected. Especially in today's rapidly developing information age, radio spectrum resources are extremely scarce. Laser radar belongs to a new track and will inevitably develop rapidly and steadily. It will continue to better serve all walks of life. In many application scenarios, it has gradually replaced electromagnetic wave radar or assisted electromagnetic wave radar. After more than half a century of development, the current laser radar technology is still in the process of exploration and innovation. However, there are some areas in which laser radar needs to be improved and improved in practical applications, mainly in the following aspects:

[0003] (1) At present, laser radar mainly contains one-dimensional or multi-dimensional depth information (distance) and angle information. The angle information can be realized by rotating mechanical scanning or using a planar array detector to realize multi-angle reception, which is relatively mature. The acquisition of depth information (distance) is the core. There are currently two main working modes: one is that the laser works in pulse mode, and the distance is obtained by directly measuring the flight time between the emission pulse light and the reception pulse light, and the optical path difference is calculated to obtain the distance, which is referred to as D-TOF; the other is that the laser works in continuous modulation mode, and the phase difference is measured by the difference frequency method, and the flight time is indirectly measured, so as to calculate the optical path difference to obtain the distance, which is referred to as I-TOF. However, these two implementation methods can only obtain distance information, and cannot measure the relative speed information of the measured target;

[0004] (2) In the D-TOF working mode, the measurement speed is fast, but a higher laser pulse peak power is required, generally not less than 60W. At close distances or when the surface reflectivity of the measured object is high, the echo energy is strong, which usually causes the receiving system to saturate. The pulse front is very steep, and as the flight distance increases or when the surface reflectivity of the measured object is low, the echo pulse power decreases, the amplitude decreases, and the front slows down, increasing the difficulty of time identification. Therefore, when directly measuring the time difference of the front, the test error will increase with the increase of distance and the decrease of reflectivity, and the measurement range is also limited, generally tens of meters to hundreds of meters;

[0005] (3) In the I-TOF operating mode, the laser is modulated by a high-frequency sine wave or a continuous pulse wave with a higher frequency (> 10 MHz). The local oscillator signal is mixed with the received light to obtain a difference frequency signal. The time of flight is obtained through the phase difference information of the difference frequency signal, and then the distance information of the measured target is calculated. Compared with the D-TOF mode, this mode is not affected by the amplitude jitter of the echo and has higher accuracy, but the measurement speed is slower, generally a few Hertz to dozens of Hertz. In addition, since the phase information of the difference frequency signal is obtained by mixing, a single modulation frequency can only guarantee a certain measurement distance, which is called a "ruler". A higher modulation frequency is used for shorter distances, and a lower modulation frequency is used for longer distances. Generally, a single "ruler" is used in a general system, such as a handheld rangefinder, while a more complex system will use multiple "rulers" and switch at different distances, such as an airborne rangefinder. In addition, in the I-TOF mode, the average power of the laser is relatively low, generally a few milliwatts to dozens of milliwatts, and the attenuation is serious when used for ultra-long distances (greater than 1 km).

[0006] In summary, the current technical difficulties of lidar mainly focus on the lack of speed measurement function and the mutual balance among laser power, measurement distance, and measurement accuracy. Summary of the Invention

[0007] The purpose of the present invention is to provide a broadband high-power linearly frequency-modulated lidar to solve the technical problems that the measurement range of existing lidars is limited in actual applications, the measurement accuracy is relatively low, and they can only measure distance but not speed.

[0008] To achieve the above purpose, the present invention adopts the following technical solutions:

[0009] A broadband high-power linearly frequency-modulated lidar, characterized in that it includes a DDS circuit, a master oscillator VCO, a semiconductor laser, a local oscillator VCO, a reference mixing circuit, a photodetector, a receiving mixing circuit, and a multi-channel synchronous sampling ADC;

[0010] The first output terminal of the DDS circuit is connected to the voltage-controlled terminal of the master oscillator VCO, and its second output terminal is connected to the voltage-controlled terminal of the local oscillator VCO, and is used to transmit a triangular wave signal to the master oscillator VCO, a DC level signal and a narrow pulse signal to the local oscillator VCO;

[0011] The first output terminal of the master oscillator VCO is connected to the signal receiving terminal of the semiconductor laser, and its second output terminal is connected to the first input terminal of the reference mixing circuit, and is used to adjust the triangular wave signal into two in-phase continuous frequency-modulated sine signals, and then transmit them to the semiconductor laser and the reference mixing circuit respectively;

[0012] The output end of the semiconductor laser is used to emit laser light to the object to be measured;

[0013] The first output end of the local oscillator VCO is connected to the second input end of the reference mixing circuit, and its second output end is connected to the first input end of the receiving mixing circuit, and is used to adjust the DC level signal and the narrow pulse signal into two in-phase fixed-frequency sine signals, and then respectively transmit them to the reference mixing circuit and the receiving mixing circuit;

[0014] The output end of the reference mixing circuit is connected to the first input end of the multi-channel synchronous sampling ADC for signal mixing;

[0015] The detection end of the photodetector is used to receive the reflected laser light from the object to be measured and perform photoelectric conversion;

[0016] The second input end of the receiving mixing circuit is connected to the output end of the photodetector, and its output end is connected to the second input end of the multi-channel synchronous sampling ADC for signal mixing;

[0017] The multi-channel synchronous sampling ADC is used to perform analog-to-digital conversion on the mixed signals output by the reference mixing circuit and the receiving mixing circuit and then send them to an external DSP processing circuit for data processing.

[0018] Further, the photodetector is an avalanche photodetector;

[0019] The wavelength band of the semiconductor laser is 780nm, 808nm, 850nm, 905nm, 1064nm or 1550nm, and its average output power is greater than 2W.

[0020] Further, a linear drive circuit is also included;

[0021] The input end of the linear drive circuit is connected to the first output end of the master oscillator VCO, and its output end is connected to the signal receiving end of the semiconductor laser.

[0022] Further, the linear drive circuit adopts a class AB laser drive circuit, its continuous drive current is greater than 1A, and its working bandwidth is greater than 50MHz.

[0023] Further, a frequency selection network is also included;

[0024] The frequency selection network is connected between the receiving mixing circuit and the multi-channel synchronous sampling ADC.

[0025] Further, a high-pass filter circuit is also included;

[0026] The high-pass filter circuit is connected between the photodetector and the receiving mixing circuit.

[0027] Further, a low-noise amplifier circuit is also included;

[0028] The low-noise amplification circuit is connected between the photodetector and the high-pass filter circuit, and its noise at a gain of 10 6 is less than 2 mV.

[0029] Furthermore, it further includes an emission collimation optical system;

[0030] The emission collimation optical system is arranged at the output end of the semiconductor laser, and its focal plane coincides with the light-emitting surface of the semiconductor laser, which can make the laser spot circular and the half-width divergence angle < 10 mrad.

[0031] Furthermore, it further includes a receiving optical system;

[0032] The receiving optical system is arranged at the detection end of the photodetector, its focal plane covers the receiving target surface of the photodetector, and an antireflection film is coated on its working surface, which is used to collect and converge the reflected laser.

[0033] Furthermore, the DDS circuit, the master oscillator VCO, the local oscillator VCO, the reference mixing circuit, the receiving mixing circuit, and the multi-channel synchronous sampling ADC are all arranged on the first circuit board;

[0034] The linear drive circuit and the semiconductor laser are both arranged on the second circuit board; the emission collimation optical system is detachably connected to the second circuit board;

[0035] The photodetector and the low-noise amplification circuit are both arranged on the third circuit board; the receiving optical system is detachably connected to the third circuit board;

[0036] The master oscillator VCO is connected to the linear drive circuit through a high-frequency flexible coaxial cable;

[0037] The low-noise amplification circuit is connected to the high-pass filter circuit through a high-frequency flexible coaxial cable.

[0038] The beneficial effects of the present utility model:

[0039] 1. The utility model linearly frequency-modulates the master oscillator VCO through a triangular wave, selects a fixed frequency for the local oscillator VCO through a DC level signal, synchronizes the phases of the master oscillator VCO and the local oscillator VCO through a narrow pulse signal, mixes the linearly frequency-modulated signal with the fixed-frequency signal, and obtains a reference signal after low-pass sampling; the return signal is mixed with the fixed-frequency signal, and a difference frequency signal is obtained after passing through a frequency selection network. The difference frequency signal is collected by a multi-channel synchronous sampling ADC and sent to the data processing of an external DSP processing circuit to obtain the phase difference between the reference optical signal and the reflected optical signal, and the distance information can be calculated more accurately; at the same time, the DSP processing circuit performs frequency-domain analysis on the collected frequency selection signal to obtain the Doppler frequency shift, which can not only realize speed measurement but also realize speed measurement.

[0040] 2. The lidar provided by the utility model adopts a broadband linear frequency modulation mode, avoiding the complex structure of traditional phase rangefinders that require multiple measuring scales, meeting the test requirements for both short and long distances, and being unrestricted by the measurement range.

[0041] 3. The lidar provided by the utility model performs high-pass filtering on the mixed signal through a high-pass filter circuit, avoiding the influence of frequency leakage of the modulated triangular wave signal on ranging and speed measurement, and improving the accuracy of measurement.

[0042] 4. The lidar provided by the utility model has a high integration level and can be extended to applications such as handheld lidar, vehicle-mounted lidar, and airborne lidar, with a wide range of applications.

[0043] 5. The lidar provided by the utility model adopts a class AB laser linear drive circuit, which is especially suitable for driving and amplifying sine signal amplitude modulation and frequency modulation signals, and the continuous drive current is greater than 1A.

[0044] 6. The lidar provided by the utility model adopts a semiconductor laser with an average output power greater than 2W, which can meet the application requirements for long distances. Description of the Drawings

[0045] Figure 1 It is a schematic structural diagram of an embodiment of a broadband high-power linearly frequency-modulated lidar of the utility model.

[0046] Reference Numerals in the Drawings

[0047] 1 - DSP processing circuit, 2 - DDS circuit, 3 - master oscillator VCO, 4 - linear drive circuit, 5 - semiconductor laser, 6 - transmitting collimating optical system, 7 - local oscillator VCO, 8 - reference mixing circuit, 9 - receiving optical system, 10 - photodetector, 11 - low-noise amplifier circuit, 12 - high-pass filter circuit, 13 - receiving mixing circuit, 14 - frequency selection network, 15 - multi-channel synchronous sampling ADC. Detailed Embodiment

[0048] The technical solution of the present utility model will be clearly and completely described below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0049] A broadband high-power linear frequency modulation lidar provided by an embodiment of the present utility model, as Figure 1 shown, is composed of a DSP processing circuit (Digital Signal Processing, abbreviated as DSP, that is, a digital signal processing circuit) 1, a DDS circuit (Direct Digital Synthesis, abbreviated as DDS, that is, a direct digital frequency synthesizer) 2, a master oscillator VCO (Voltage Controlled Oscillator, abbreviated as VCO, that is, a voltage controlled oscillator) 3, a linear drive circuit 4, a semiconductor laser 5, a transmitting collimating optical system 6, a local oscillator VCO 7, a reference mixing circuit 8, a receiving optical system 9, a photodetector 10, a low-noise amplifier circuit 11, a high-pass filter circuit 12, a receiving mixing circuit 13, a frequency selection network 14, and a multi-channel synchronous sampling ADC (Analog-to-Digital Converter, abbreviated as ADC, that is, an analog-to-digital converter) 15.

[0050] Among them, the DSP processing circuit 1, DDS circuit 2, master oscillator VCO 3, local oscillator VCO 7, reference mixing circuit 8, high-pass filter circuit 12, receiving mixing circuit 13, frequency selection network 14 and multi-channel synchronous sampling ADC 15 are located on the first circuit board. The input end of the DSP processing circuit 1 and the DDS circuit 2 are connected through the traces on the first circuit board. The first output end of the DDS circuit 2 and the voltage control end of the master oscillator VCO 3 are connected through the traces on the first circuit board. The second output end of the DDS circuit 2 and the voltage control end of the local oscillator VCO 7 are connected through the traces on the first circuit board. The first output end of the local oscillator VCO 7 and the second input end of the reference mixing circuit 8 are connected through the traces on the first circuit board. The second output end of the local oscillator VCO 7 and the first input end of the receiving mixing circuit 13 are connected through the traces on the first circuit board. The second output end of the master oscillator VCO 3 and the first input end of the reference mixing circuit 8 are connected through the traces on the first circuit board. The output end of the reference mixing circuit 8 and the first input end of the multi-channel synchronous sampling ADC 15 are connected through the traces on the first circuit board. The output end of the high-pass filter circuit 12 and the second input end of the receiving mixing circuit 13 are connected through the traces on the first circuit board. The output end of the receiving mixing circuit 13 and the input end of the frequency selection network 14 are connected through the traces on the first circuit board. The output end of the frequency selection network 14 and the second input end of the multi-channel synchronous sampling ADC 15 are connected through the traces on the first circuit board. The multi-channel synchronous sampling ADC 15 and the DSP processing circuit 1 are connected through the traces on the first circuit board.

[0051] The linear drive circuit 4 and the semiconductor laser 5 are located on the second circuit board and are connected through the traces on the second circuit board. The second circuit board is rigidly connected to the emission collimation optical system 6 by screws, and the light emitting surface of the semiconductor laser 5 is located at the focal plane position of the emission collimation optical system 6.

[0052] The photodetector 10 and the low-noise amplifier circuit 11 are located on the third circuit board and are connected through the traces on the third circuit board. The third circuit board is rigidly connected to the receiving optical system 9 by screws, and the focal plane of the receiving optical system 9 covers the receiving target surface of the photodetector 10; the photodetector 10 is an avalanche photodetector; the first output end of the master oscillator VCO 3 is connected to the input end of the linear drive circuit 4 through a high-frequency flexible coaxial cable; the output end of the low-noise amplifier circuit 11 is connected to the input end of the high-pass filter circuit 12 through a high-frequency flexible coaxial cable.

[0053] The above lidar linearly frequency-modulates the master oscillator VCO 3 through a triangular wave. The frequency-modulated continuous wave signal drives the semiconductor laser 5 through the linear drive circuit 4 to output an optical signal, which is output after passing through the transmitting collimating optical system 6. The local oscillator VCO 7 outputs a stable single-frequency signal. At the same time, the frequency-modulated continuous wave signal is mixed with the local oscillator signal, and a reference signal is obtained after low-pass sampling. The return optical signal enters the receiving optical system 9, converges on the receiving target surface of the avalanche photodetector to be converted into a photocurrent signal, and a return signal is obtained after I / V conversion, low-noise amplification circuit and filtering. The return signal is mixed with the local oscillator frequency through the mixing circuit, and a difference frequency signal is obtained after passing through the frequency selection network 14. The difference frequency signal is collected by the multi-channel synchronous sampling ADC 15. Through the data processing of the DSP processing circuit, the phase difference between the reference signal and the return signal is obtained, the flight time is calculated, and then the distance information is calculated; at the same time, the DSP processing circuit performs frequency-domain analysis on the collected frequency selection signal to obtain the Doppler frequency shift and calculate the speed information relative to the lidar.

[0054] The specific working process is as follows:

[0055] S1. The above broadband high-power linearly frequency-modulated lidar is powered on and initialized. The DSP processing circuit 1 completes the initial configuration of the DDS circuit 2 and the multi-channel synchronous sampling ADC 15. The DDS circuit 2 outputs three signals. One is a triangular wave with an amplitude changing from 0 to 5V and a frequency of 5kHz. One is a stable DC level signal. One is a narrow pulse signal. The triangular wave signal is sent to the voltage control terminal of the master oscillator VCO 3, and the stable DC level signal is sent to the voltage control terminal of the local oscillator VCO 7; the narrow pulse signal is sent to the output gating of the local oscillator VCO 7 for phase synchronization of the signals output by the master oscillator VCO 3 and the local oscillator VCO 7; the multi-channel synchronous sampling ADC 15 is configured in a dual-channel simultaneous sampling mode. One is a reference channel to collect the output of the reference mixing circuit 8, and the other is a measurement channel to collect the output of the frequency selection network 14;

[0056] S2. The master oscillator VCO 3 outputs two in-phase continuous frequency-modulated sine signals, whose frequency change range is 0.1MHz - 9.9MHz, and the center frequency is 5MHz; preferably, continuous frequency modulation is performed with a bandwidth of 4.9MHz;

[0057] S3. The local oscillator VCO 7 outputs two in-phase fixed-frequency sine signals of 4.9MHz;

[0058] S4. One of the continuous frequency-modulated sine signals output by the master oscillator VCO 3 is mixed with one of the fixed-frequency sine signals output by the local oscillator VCO 7 through the reference mixing circuit 8;

[0059] S5. The reference channel of the multi-channel synchronous sampling ADC 15 performs low-pass sampling on the mixed-frequency signal output by the reference mixing circuit 8 to obtain a 0.1 MHz difference-frequency signal as a reference;

[0060] S6. Another continuous frequency-modulated sine signal output by the master oscillator VCO 3 is fed into the input terminal of the linear drive circuit 4. The linear drive circuit 4 is a high-power linear drive circuit with a class AB structure, the drive current is greater than 1 A, and the working bandwidth is greater than 50 MHz;

[0061] S7. The linear drive circuit 4 drives the semiconductor laser 5 to emit laser, with a wavelength band of 905 nm and an average power > 2 W; The semiconductor laser 5 can also use common near-infrared wavelength bands such as 780 nm, 808 nm, 850 nm, 1064 nm, 1550 nm, etc.;

[0062] S8. The laser is emitted into the distance through the emission collimation optical system 6, the light spot is circular, and the half-width divergence angle < 10 mrad;. When the emitted laser encounters the object to be measured, reflection occurs;

[0063] S9. The receiving optical system 9 collects and converges the reflected laser on the receiving target surface of the avalanche photodetector 10. The optical system is coated with an antireflection film of 905 nm and includes a filter to avoid the influence of stray light; The photodetector 10 operates in a non-avalanche mode and can achieve linear photoelectric conversion;

[0064] S10. The low-noise amplifier circuit 11 includes a two-stage amplifier circuit, which respectively converts the weak photocurrent signal output by the photodetector 10 into a voltage signal and amplifies the voltage signal. The noise is not greater than 2 mV at a gain of 10 6 gain;

[0065] S11. The high-pass filter circuit 12 performs high-pass filtering on the output signal of the low-noise amplifier circuit 11 to filter out the leakage frequency components of the modulated triangular wave and avoid affecting the later ranging and speed measurement data processing; The output signal of the high-pass filter circuit 12 and another fixed-frequency sine signal output by the local oscillator VCO 7 are mixed by the receiving mixing circuit 13;

[0066] S12. After being mixed by the receiving mixing circuit 13, the signal only retains the measurement signal with a 3 dB cut-off frequency not greater than 2.1 MHz through the frequency selection network 14;

[0067] S13. The measurement channel of the multi-channel synchronous sampling ADC 15 collects the measurement signal output by the frequency selection network 14;

[0068] The DSP processing circuit 1 reads and processes the acquisition data of the multi-channel synchronous sampling ADC 15 to obtain the distance D and the speed information v. The calculation of the distance information is shown in Equation (1), and the calculation of the speed information is shown in Equation (2):

[0069]

[0070] In the formula, φ is the phase difference between the reference channel data and the measurement channel data, c is the speed of light, and f m is the modulation frequency.

[0071]

[0072] In the formula, f b- is the difference between the modulation bandwidth and the Doppler shift, f b+ is the sum of the modulation bandwidth and the Doppler shift, c is the speed of light, and f0 is the center frequency.

[0073] Repeating the above steps can achieve continuous measurement.

[0074] Through actual outdoor measurement, accurate distance measurement from 2m to 800m can be achieved, and the maximum absolute error is not greater than 2‰ of the range; speed measurement from 10m / s to 110m / s can be achieved.

[0075] The above is only the specific implementation manner of the present utility model, but the protection scope of the present utility model is not limited thereto. Any change or replacement within the technical scope disclosed by the present utility model should be covered by the protection scope of the present utility model. Therefore, the protection scope of the present utility model should be subject to the protection scope of the claimed rights.

Claims

1. A broadband high-power linear frequency modulation laser radar, characterized in that: It includes a DDS circuit (2), a master oscillator VCO (3), a semiconductor laser (5), a local oscillator VCO (7), a reference mixer circuit (8), a photodetector (10), a receiving mixer circuit (13) and a multi-channel synchronous sampling ADC (15); The first output end of the DDS circuit (2) is connected to the voltage control end of the master oscillator VCO (3), and the second output end is connected to the voltage control end of the local oscillator VCO (7), and is used to transmit a triangle wave signal to the master oscillator VCO (3) and a DC level signal and a narrow pulse signal to the local oscillator VCO (7); The first output end of the master oscillator VCO (3) is connected to the signal receiving end of the semiconductor laser (5), and the second output end is connected to the first input end of the reference mixer circuit (8), so as to adjust the triangle wave signal into two continuous frequency modulated sinusoidal signals with the same phase, and then transmit them to the semiconductor laser (5) and the reference mixer circuit (8) respectively; The output end of the semiconductor laser (5) is used to emit laser light to the object to be measured; The first output end of the local oscillator VCO (7) is connected to the second input end of the reference mixer circuit (8), and the second output end thereof is connected to the first input end of the receiving mixer circuit (13), and is used to adjust the DC level signal and the narrow pulse signal into two fixed-frequency sinusoidal signals with the same phase, and then transmit them to the reference mixer circuit (8) and the receiving mixer circuit (13) respectively; The output end of the reference mixing circuit (8) is connected to the first input end of the multi-channel synchronous sampling ADC (15) for signal mixing; The detection end of the photoelectric detector (10) is used to receive the reflected laser light from the object to be detected and perform photoelectric conversion; The second input end of the receiving mixing circuit (13) is connected to the output end of the photodetector (10), and the output end thereof is connected to the second input end of the multi-channel synchronous sampling ADC (15) for signal mixing; The multi-channel synchronous sampling ADC (15) is used to perform analog-to-digital conversion on the mixing signals output by the reference mixing circuit (8) and the receiving mixing circuit (13), and then send the converted signals to the external DSP processing circuit (1) for data processing.

2. The broadband high-power linear frequency modulation laser radar according to claim 1, characterized in that: The photoelectric detector (10) is an avalanche photoelectric detector; The wavelength band of the semiconductor laser (5) is 780nm, 808nm, 850nm, 905nm, 1064nm or 1550nm, and its average output power is greater than 2W.

3. The broadband high-power linear frequency modulation laser radar according to claim 1 or 2, characterized in that: Also includes a linear drive circuit (4); The input end of the linear drive circuit (4) is connected to the first output end of the master oscillator VCO (3), and the output end is connected to the signal receiving end of the semiconductor laser (5).

4. The broadband high-power linear frequency modulation laser radar according to claim 3, characterized in that: The linear drive circuit (4) adopts a Class AB laser drive circuit, and its continuous drive current is greater than 1A and its operating bandwidth is greater than 50MHz.

5. The broadband high-power linear frequency modulation laser radar according to claim 4, characterized in that: Also included is a frequency selection network (14); The frequency selection network (14) is connected between the receiving mixing circuit (13) and the multi-channel synchronous sampling ADC (15).

6. The broadband high-power linear frequency modulation laser radar according to claim 5, characterized in that: Also includes a high pass filter circuit (12); The high-pass filter circuit (12) is connected between the photodetector (10) and the receiving mixer circuit (13).

7. The broadband high-power linear frequency modulation laser radar according to claim 6, characterized in that: Also includes a low noise amplifier circuit (11); The low-noise amplifier circuit (11) is connected between the photodetector (10) and the high-pass filter circuit (12). 6 Noise is less than 2mV at full gain.

8. The broadband high-power linear frequency modulation laser radar according to claim 7, characterized in that: Also included is a transmission collimating optical system (6); The emission collimating optical system (6) is arranged at the emission end of the semiconductor laser (5), and its focal plane coincides with the light emitting surface of the semiconductor laser (5), so that the laser spot is circular and the half-width divergence angle is less than 10 mrad.

9. The broadband high-power linear frequency modulation laser radar according to claim 8, characterized in that: Also includes a receiving optical system (9); The receiving optical system (9) is arranged at the detection end of the photodetector (10), its focal plane covers the receiving target surface of the photodetector (10), and its active surface is coated with an anti-reflection film for collecting and converging reflected laser light.

10. The broadband high-power linear frequency modulation laser radar according to claim 9, characterized in that: The DDS circuit (2), the master oscillator VCO (3), the local oscillator VCO (7), the reference mixer circuit (8), the receiving mixer circuit (13) and the multi-channel synchronous sampling ADC (15) are all arranged on a first circuit board; The linear drive circuit (4) and the semiconductor laser (5) are both arranged on a second circuit board; the emission collimating optical system (6) is detachably connected to the second circuit board; The photodetector (10) and the low-noise amplifier circuit (11) are both arranged on a third circuit board; the receiving optical system (9) is detachably connected to the third circuit board; The master oscillator VCO (3) is connected to the linear drive circuit (4) via a high-frequency soft coaxial cable; The low-noise amplifier circuit (11) is connected to the high-pass filter circuit (12) via a high-frequency soft coaxial cable.

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