Scanning device of single-photon laser radar three-dimensional imaging system for dynamic target

Abstract

The invention discloses a scanning device of a single-photon laser radar three-dimensional imaging system for a dynamic target, and belongs to the field of laser radar optical design. The system comprises a laser emission subsystem, a light path subsystem, a detection subsystem, a data acquisition and processing subsystem, a control subsystem and a two-dimensional rotary table, the laser emission subsystem generates laser beams, and the light path subsystem emits the laser beams to a detection target area and receives scattering echo signals; scattered echo signals are subjected to sum-frequency conversion and angle calculation to obtain point cloud information, the detection subsystem collects the point cloud information, and the data processing system reconstructs a dynamic three-dimensional image of a to-be-detected target according to two-dimensional scanning distribution information and the point cloud information. The device is used for carrying out three-dimensional laser imaging on a dynamic cooperative target under single-photon detection, the frequency up-conversion technology and the rapid scanning assembly are combined, the space scanning efficiency is improved, and the problem of long-distance dynamic target detection in existing single-photon detection is solved.

Description

Technical Field

[0001] The invention relates to a scanning device of a single-photon laser radar three-dimensional imaging system for dynamic targets, and belongs to the field of laser radar optical design. Background Art

[0002] Single-photon laser radar (also known as photon counting laser radar) can achieve photon-level echo response. Compared with traditional laser radar, it has higher detection sensitivity and has obvious advantages in long-distance and high-attenuation adverse environments. Single-photon laser radar emits narrow-pulse pulse laser with a certain repetition frequency to detect the weak reflection signal of the target. By accurately calculating the flight time of photons, it obtains the distribution of the probability of photon return in time, extracts the distance information of the target, and then reconstructs the three-dimensional image of the target. With the development of science and technology, tracking and ranging technology based on single-photon laser radar is increasingly widely used in aerospace and autonomous driving, and has important application value in target detection, tracking, and motion obstacle avoidance.

[0003] At present, single-photon laser 3D imaging technology is mainly used for the measurement of static targets. For dynamic target detection, existing single-photon laser radars are easily affected by detection devices and background noise. Especially when performing detection imaging at a relatively long distance, the echo signal that the imaging system can receive is very weak, the detection efficiency is limited, and the imaging quality is restricted, making it difficult to meet the application requirements of early warning detection of dynamic targets. In addition, due to the inherent resolution limit of the system, the spatial resolution of the system is severely limited at long distances. In terms of fast scanning and high-resolution capabilities, single-photon 3D imaging technology for detecting dynamic targets is still in urgent need of development. Summary of the invention

[0004] The purpose of the present invention is to provide a scanning device for a single-photon laser radar three-dimensional imaging system for dynamic targets, which is used for three-dimensional laser imaging of dynamic cooperative targets under single-photon detection. By combining frequency up-conversion technology with a fast scanning component, the spatial scanning efficiency of the system is improved, thereby compensating for the problem of long-distance dynamic target detection in existing single-photon detection.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A scanning device of a single-photon laser radar three-dimensional imaging system for dynamic targets of the present invention comprises a single-photon laser radar three-dimensional imaging system and a two-dimensional turntable;

[0007] The single-photon laser radar three-dimensional imaging system includes: a laser emission subsystem, an optical path subsystem, a detection subsystem, a data acquisition and processing subsystem, and a control subsystem;

[0008] Wherein, the laser emission subsystem is used to generate a laser beam and transmit it to the optical path subsystem; the optical path subsystem is used to emit the laser beam to the detection target area, receive the scattered echo signal of the target to be detected, and also use the near-infrared frequency up-conversion technology to perform sum-frequency conversion and angle resolution on the scattered echo signal of the target to be detected, so as to obtain the point cloud information of the target to be detected at different positions; the detection subsystem is used to collect the point cloud information of the target to be detected at different positions and transmit it to the data acquisition and processing subsystem; the data acquisition and processing subsystem is used to reconstruct a dynamic three-dimensional image of the target to be detected based on the two-dimensional scanning distribution information of the detection subsystem and the point cloud information of the target to be detected at different positions: the control subsystem is used to control the laser emission subsystem to generate a laser beam, and is also used to control the rotation state of the two-dimensional turntable;

[0009] The laser emission subsystem includes: a signal laser and a pump laser;

[0010] The signal laser is used to provide signal light, and the pump laser is used to provide pump light;

[0011] The optical path subsystem includes: a polarization-maintaining module, a fast scanning module, a fiber focusing lens, a Cassegrain system, a dichroic mirror, a slow delay line, a BBO crystal assembly, a polarization receiving module, a collimator and a polarization-maintaining fiber;

[0012] The polarization-maintaining module includes: a λ / 4 wave plate, a λ / 2 wave plate and a polarization controller;

[0013] The fast scanning module includes: a voice coil motor and a beam return mirror;

[0014] The voice coil motor is used as a motion device of the fast scanning module. After starting, it is in a continuous high-speed motion state without pause, and is used to achieve high-precision and large-range delay adjustment of the signal light pulse;

[0015] The BBO crystal assembly is used to perform frequency up-conversion on the pump light and the signal light to generate sum frequency light;

[0016] The polarization receiving module includes: a bandpass filter, an objective lens and a multimode optical fiber;

[0017] The detection subsystem includes: a single photon detector and a time-to-digital converter;

[0018] The data acquisition and processing subsystem includes: FPGA, hard disk and high-speed data acquisition card;

[0019] The two-dimensional turntable includes: a support base, a scanning system base, an optical lens, a horizontal rotation platform, a vertical rotation platform, a data cable and a cable interface;

[0020] The signal light emitted by the signal laser is linearly polarized light, which first passes through a polarization-maintaining module to adjust the polarization state and power of the laser in the rear optical path, and then passes through the fast scanning module and the fiber focusing lens in turn to irradiate the surface of the target to be measured, and the reflected light from the surface of the target to be measured is received by the Cassegrain system coaxially placed behind the fiber focusing lens;

[0021] When the signal light is incident on the beam return mirror, the beam return mirror of the fast delay line performs continuous linear motion under the uniform speed drive of the voice coil motor. The change of the reflection point will produce a change in the optical delay position. According to the optical path relationship between the reflected light and the incident light, the generated optical delay distance L is twice the change of the reflection point along the movement direction of the voice coil motor, as shown in formula (1):

[0022] L=2·x (1)

[0023] Wherein, x is the distance change of the reflection point on the beam return mirror along the moving direction of the voice coil motor;

[0024] According to the motion relationship, the optical delay time τ is shown in formula (2):

[0025] τ=2·v·t / c (2)

[0026] Wherein, v is the movement speed of the voice coil motor, c is the speed of light, and t is the movement time of the beam return mirror;

[0027] When the voice coil motor moves at a constant speed, the optical delay time is linearly related to the movement time of the beam return mirror. When the optical delay time τ of scanning is a fixed value, when the running speed v of the voice coil motor is increased, the movement time t of the beam return mirror will decrease accordingly, and vice versa.

[0028] The reciprocal of the beam return mirror movement time t is the scanning frequency f of the fast delay line, as shown in formula (3):

[0029] f=1 / t=v / x (3)

[0030] Wherein, v is the movement speed of the voice coil motor, and x is the change amount of the reflection point on the beam return mirror along the movement direction of the voice coil motor;

[0031] The voice coil motor platform generates a trigger pulse for the high-speed data acquisition card while completing the above-mentioned movement process. After receiving the pulse, the high-speed data acquisition card starts analog-to-digital conversion and collects single-photon signals to achieve rapid detection of single photons.

[0032] The pump light emitted by the pump laser also first passes through a polarization-maintaining module to achieve power and polarization state adjustment. The pump light passes through the slow delay line to achieve delay matching with the signal light, ensuring that within the adjustment range of the slow delay line, the signal light pulse and the pump light pulse can overlap in the BBO crystal component, and pass through the dichroic mirror to be coupled into the polarization-maintaining optical fiber together;

[0033] The signal light and the pump light enter the BBO crystal component together, and the sum frequency photons generated after the frequency conversion are filtered out by the polarization receiving module, and then the sum frequency photons are coupled into the polarization-maintaining optical fiber and detected by the single photon detector. The readout signal of the single photon detector is connected to the time-to-digital converter, and the time-to-digital converter is synchronized with the pump light pulse through an electrical signal, and time-correlated single photon measurement is performed;

[0034] The polarization-maintaining module is used in combination with the polarization receiving module as a necessary noise reduction means in the optical path subsystem to improve imaging accuracy;

[0035] The signal light and the pump light are both linearly polarized lights with high extinction ratios. After being reflected by the detection target, they are generally depolarized into partially polarized lights and reach the polarization receiving module. The linearly polarized echo component enters the detector through the analyzer, and other polarization state components containing background noise are suppressed, so as to realize the processing of low signal-to-noise ratio echoes, remove the background noise in the optical path subsystem 2, improve the signal-to-noise ratio, and improve the imaging quality of the laser radar.

[0036] Furthermore, when the photon laser radar imaging detection system performs imaging detection in a rapid scanning imaging mode, the following steps are performed:

[0037] Step 1: Setting the laser emission subsystem parameters through the control subsystem to adjust the repetition rate, pulse width and power of the signal light and the pump light;

[0038] Step 2: Setting the parameters of the two-dimensional turntable through the control subsystem, controlling the rotation direction of the two-dimensional turntable, and aligning the single-photon radar system with a scene area containing the dynamic cooperative target to be measured;

[0039] Step 3: Control the scanning mode of the two-dimensional turntable and the automatic focusing of the Cassegrain system through the control subsystem, so that the optical path subsystem starts scanning the dynamic cooperative target to be measured and collects its optical information data;

[0040] Step 4: Collect optical information through the detection subsystem, collect the synchronization signal of the single-photon radar system, and the echo signal and angle information of the measured target at different positions;

[0041] Step 5: Transmit the echo signal and angle information in step 4 to the data processing subsystem, record the TOF, peak value and angle, and obtain the point cloud information of the dynamic target under test at different positions;

[0042] Step 6: Process the three-dimensional point cloud information through the data processing subsystem to reconstruct a dynamic three-dimensional image of the dynamic target being measured.

[0043] Beneficial effects:

[0044] 1. The scanning device of the single-photon laser radar three-dimensional imaging system for dynamic targets of the present invention combines spectral filtering technology with near-infrared frequency up-conversion detection technology, which can effectively filter out background noise signals and improve the quality of single-photon imaging.

[0045] 2. The scanning device of the single-photon laser radar three-dimensional imaging system for dynamic targets of the present invention is constructed using a compact optical path module and a small number of electronic components, which can achieve miniaturization and lightweight of the system.

[0046] 3. The scanning device of a single-photon laser radar three-dimensional imaging system for dynamic targets of the present invention applies time delay technology to match frequency up-conversion technology in single-photon detection imaging to improve time resolution performance, system real-time performance and imaging refresh rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A block diagram of a scanning device of a single-photon laser radar three-dimensional imaging system for dynamic targets of the present invention;

[0048] Among them, 1-laser emission subsystem, 2-optical path subsystem, 3-detection subsystem, 4-data acquisition and processing subsystem, 5-control subsystem and 6-two-dimensional turntable;

[0049] Figure 2 This is a composition diagram of a scanning device of a single-photon laser radar three-dimensional imaging system for dynamic targets of the present invention;

[0050] Among them, 1-1-signal laser, 1-2-pump laser, 2-1-polarization-maintaining module, 2-2-fast scanning module, 2-3-fiber focusing lens, 2-4-Cassegrain system, 2-5-dichroic mirror, 2-6-slow delay line, 2-7-BBO crystal assembly, 2-8-polarization receiving module, 2-9-collimator and polarization-maintaining fiber, 3-1-single photon detector, 3-2-time-to-digital converter, 4-1-FPGA, 4-2-hard disk and 4-3-high-speed data acquisition card;

[0051] Figure 3 It is a schematic diagram of a two-dimensional turntable of a scanning device of a single-photon laser radar three-dimensional imaging system for dynamic targets of the present invention;

[0052] Among them, 6-1-support base, 6-2-scanning system base, 6-3-optical lens, 6-4-horizontal rotation platform, 6-5-vertical rotation platform, 6-6-data cable and 6-7-cable interface;

[0053] Figure 4 The present invention is a flow chart of detecting a three-dimensional point cloud image of a dynamic target. DETAILED DESCRIPTION

[0054] In order to better illustrate the purpose and advantages of the present invention, the invention is further described below with reference to the accompanying drawings and examples.

[0055] Embodiment 1:

[0056] The scanning device of the single-photon laser radar three-dimensional imaging system for dynamic targets disclosed in this embodiment is as follows: Figure 1 As shown, it includes a single-photon laser radar three-dimensional imaging system and a two-dimensional turntable 6;

[0057] like Figure 1 As shown, the single-photon laser radar three-dimensional imaging system includes: a laser emission subsystem 1, an optical path subsystem 2, a detection subsystem 3, a data acquisition and processing subsystem 4, and a control subsystem 5;

[0058] Among them, the laser emission subsystem 1 is used to generate a laser beam and transmit it to the optical path subsystem 2; the optical path subsystem 2 is used to emit the laser beam to the detection target area, receive the scattered echo signal of the target to be detected, and also use the near-infrared frequency up-conversion technology to perform sum-frequency conversion and angle resolution on the scattered echo signal of the target to be detected, and obtain the point cloud information of the target to be detected at different positions; the detection subsystem 3 is used to collect the point cloud information of the target to be detected at different positions and transmit it to the data acquisition and processing subsystem 4; the data acquisition and processing subsystem 4 is used to reconstruct a dynamic three-dimensional image of the target to be detected based on the two-dimensional scanning distribution information of the detection subsystem 3 and the point cloud information of the target to be detected at different positions; the control subsystem 5 is used to control the laser emission subsystem 1 to generate a laser beam, and is also used to control the rotation state of the two-dimensional turntable 6;

[0059] like Figure 2 As shown, the laser emission subsystem 1 includes: a signal laser 1-1 and a pump laser 1-2, the signal laser 1-1 is used to provide signal light, and the pump laser 1-2 is used to provide pump light. In the embodiment, the signal laser 1-1 is a laser with a wavelength of 1550nm and a maximum output power of 10mW, and the pump laser 1-2 is a semiconductor laser with a wavelength of 1064nm, a maximum output power of 6.19W, a power stability of 0.19%, a beam diameter of 2mm, and a beam divergence angle of 1.2mrad;

[0060] like Figure 2 As shown, the optical path subsystem 2 includes: a polarization-maintaining module 2-1, a fast scanning module 2-2, a fiber focusing lens 2-3, a Cassegrain system 2-4, a dichroic mirror 2-5, a slow delay line 2-6, a BBO crystal assembly 2-7, a polarization receiving module 2-8, and a collimator and a polarization-maintaining fiber 2-9;

[0061] The polarization-maintaining module 2-1 includes: a λ / 4 wave plate, a λ / 2 wave plate and a polarization controller;

[0062] The fast scanning module 2-2 includes: a voice coil motor and a beam return mirror. The voice coil motor is used as a motion device of the fast scanning module. After starting, it is in a continuous high-speed motion state without pause, and is used to achieve high-precision and large-range delay adjustment of the signal light pulse;

[0063] The BBO crystal component 2-7 is used to perform frequency up-conversion on the pump light and the signal light to generate sum frequency light;

[0064] The polarization receiving module 2-8 includes: a bandpass filter, an objective lens and a multimode optical fiber;

[0065] The detection subsystem 3 includes: a single photon detector 3-1 and a time-to-digital converter 3-2;

[0066] The data acquisition and processing subsystem 4 includes: FPGA 4-1, hard disk 4-2 and high-speed data acquisition card 4-3;

[0067] like Figure 3 As shown, the two-dimensional turntable 6 includes: a support base 6-1, a scanning system base 6-2, an optical lens 6-3, a horizontal rotation platform 6-4, a vertical rotation platform 6-5, a data cable 6-6 and a cable interface 6-7;

[0068] The scanning system base 6-2 contains the laser emission subsystem 1, the detection subsystem 3, the data acquisition and processing subsystem 4, and the polarization-maintaining module 2-1, the fast scanning module 2-2, the dichroic mirror 2-5, the slow delay line 2-6, the BBO crystal assembly 2-7, the polarization receiving module 2-8, the collimator and the polarization-maintaining optical fiber 2-9 of the optical path subsystem 2;

[0069] The optical lens 6-3 is provided with a fiber focusing lens 2-3 and a Cassegrain system 2-4;

[0070] The signal light emitted by the signal laser 1-1 is linearly polarized light, which first passes through a polarization-maintaining module 2-1 to adjust the polarization state and power of the laser in the rear optical path. The signal light passes through the fast scanning module 2-2 and the fiber focusing lens 2-3 in turn to irradiate the surface of the target to be measured. The reflected light from the surface of the target to be measured is received by the Cassegrain system 2-4 coaxially placed behind the fiber focusing lens 2-3.

[0071] When the signal light is incident on the beam return mirror, the beam return mirror of the fast delay line performs continuous linear motion under the uniform speed drive of the voice coil motor. The change of the reflection point will produce a change in the optical delay position. According to the optical path relationship between the reflected light and the incident light, the generated optical delay distance is twice the change of the reflection point along the direction of movement of the voice coil motor, as shown in formula (1):

[0072] L=2·x (1)

[0073] Where L is the optical delay distance, x is the distance change of the reflection point on the beam return mirror along the direction of movement of the voice coil motor; according to the motion relationship, the optical delay time τ is shown in formula (2):

[0074] τ=2·v·t / c (2)

[0075] Among them, τ is the optical delay time, v is the movement speed of the voice coil motor, c is the speed of light, and t is the movement time of the beam return mirror;

[0076] When the voice coil motor moves at a constant speed, the optical delay time is linearly related to the movement time of the beam return mirror. When the optical delay time τ of the scan is fixed, when the running speed v of the voice coil motor is increased, the movement time t of the beam return mirror will decrease accordingly, and vice versa.

[0077] The reciprocal of the beam return mirror movement time t is the scanning frequency f of the fast delay line, as shown in formula (3):

[0078] f=1 / t=v / x (3)

[0079] Among them, v is the movement speed of the voice coil motor, and x is the change of the reflection point on the beam return mirror along the movement direction of the voice coil motor;

[0080] The voice coil motor platform generates a trigger pulse for the high-speed data acquisition card 4-3 while completing the above movement process. After receiving the pulse, the high-speed data acquisition card 4-3 starts analog-to-digital conversion and collects single-photon signals to achieve rapid detection of single photons.

[0081] The pump light emitted by the pump laser 1-2 also first passes through a polarization-maintaining module 2-1 to achieve power and polarization state adjustment. The pump light passes through a slow delay line 2-6 to achieve delay matching with the signal light, ensuring that within the adjustment range of the slow delay line 2-6, the signal light pulse and the pump light pulse can overlap in the BBO crystal component 2-7, and pass through the dichroic mirror 2-5 to be coupled into the polarization-maintaining fiber 2-1 together;

[0082] The signal light and the pump light enter the BBO crystal component 2-7 together, and the sum frequency photons generated after the frequency conversion are filtered out by the polarization receiving module 2-9. The sum frequency photons are coupled into the collimator and the polarization-maintaining fiber 2-9, and detected by the single photon detector 3-1. The readout signal of the single photon detector 3-1 is connected to the time digital converter 3-2. The time digital converter 3-2 is synchronized with the pump light pulse through the electrical signal, and the time-correlated single photon measurement is performed.

[0083] The polarization-maintaining module 2-1 is used in combination with the polarization receiving module 2-8 as a necessary noise reduction means in the optical path subsystem 2 to improve the imaging accuracy;

[0084] The signal light and the pump light are both linearly polarized lights with high extinction ratio. After being reflected by the detection target, they are generally depolarized into partially polarized lights and reach the polarization receiving module 2-8. The linearly polarized echo component enters the detector through the analyzer, and other polarization state components containing background noise will be suppressed, so as to realize the processing of low signal-to-noise ratio echoes, remove the background noise in the optical path subsystem 2, improve the signal-to-noise ratio, and improve the imaging quality of the laser radar.

[0085] like Figure 4 As shown, when the photon laser radar imaging detection system performs imaging detection in the fast scanning imaging mode, the following steps are performed:

[0086] Step 1: Setting the parameters of the laser emission subsystem 1 through the control subsystem 5 to adjust the repetition rate, pulse width and power of the signal light and the pump light;

[0087] Step 2: Setting the parameters of the two-dimensional turntable 6 through the control subsystem 5 and controlling the rotation direction of the two-dimensional turntable 6 so that the single-photon radar system is aimed at the scene area containing the dynamic cooperative target to be measured;

[0088] Step 3: Control the scanning mode of the two-dimensional turntable 6 and the automatic focusing of the Cassegrain system 2-4 through the control subsystem 5, so that the optical path subsystem 2 starts scanning the dynamic cooperative target to be measured and collects its optical information data;

[0089] Step 4: Collect optical information through the detection subsystem 3, collect the synchronization signal of the single-photon radar system, and the echo signal and angle information of the measured target at different positions;

[0090] Step 5: Transmit the echo signal and angle information in step 4 to the data processing subsystem 4, record the TOF, peak value and angle, and obtain the point cloud information of the dynamic target under test at different positions;

[0091] Step 6: Process the three-dimensional point cloud information through the data processing subsystem 4 to reconstruct a dynamic three-dimensional image of the dynamic target being measured.

[0092] The specific description above further illustrates the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A scanning device for a single-photon laser radar three-dimensional imaging system for dynamic targets, characterized in that: include: Laser emission subsystem (1), optical path subsystem (2), detection subsystem (3), data acquisition and processing subsystem (4), control subsystem (5) and two-dimensional turntable (6); The laser emission subsystem (1) generates a laser beam and transmits it to the optical path subsystem (2); the optical path subsystem (2) emits the laser beam to the detection target area, receives the scattered echo signal of the target to be detected, and uses the near-infrared frequency up-conversion technology to perform sum-frequency conversion and angle calculation on the scattered echo signal of the target to be detected, thereby obtaining point cloud information of the target to be detected at different positions; the detection subsystem (3) collects the point cloud information of the target to be detected at different positions and transmits it to the data acquisition and processing subsystem (4); The data acquisition and processing subsystem (4) reconstructs a dynamic three-dimensional image of the target to be detected based on the two-dimensional scanning distribution information of the detection subsystem (3) and the point cloud information of the target to be detected at different positions; the control subsystem (5) controls the laser emission subsystem (1) to generate a laser beam and controls the rotation state of the two-dimensional turntable (6).

2. The scanning device of a single-photon laser radar three-dimensional imaging system for dynamic targets according to claim 1, characterized in that: The laser emission subsystem (1) comprises: a signal laser (1-1) and a pump laser (1-2); The optical path subsystem (2) includes: a polarization-maintaining module (2-1), a fast scanning module (2-2), a fiber focusing lens (2-3), a Cassegrain system (2-4), a dichroic mirror (2-5), a slow delay line (2-6), a BBO crystal assembly (2-7), a polarization receiving module (2-8), a collimator and a polarization-maintaining optical fiber (2-9); The polarization-maintaining module (2-1) comprises: a λ / 4 wave plate, a λ / 2 wave plate and a polarization controller; The fast scanning module (2-2) comprises: a voice coil motor and a beam return mirror; The polarization receiving module (2-8) comprises: a bandpass filter, an objective lens and a multimode optical fiber; The detection subsystem (3) includes: a single photon detector (3-1) and a time-to-digital converter (3-2); The data acquisition and processing subsystem (4) includes: FPGA (4-1), hard disk (4-2) and high-speed data acquisition card (4-3); The two-dimensional turntable (6) comprises: a support base (6-1), a scanning system base (6-2), an optical lens (6-3), a horizontal rotation platform (6-4), a vertical rotation platform (6-5), a data cable (6-6) and a cable interface (6-7); The signal laser (1-1) is used to provide signal light, and the pump laser (1-2) is used to provide pump light; The voice coil motor is used as a motion device of the fast scanning module (2-2). After being started, it is in a continuous high-speed motion state without pause, and is used to achieve high-precision and large-range delay adjustment of the signal light pulse; The BBO crystal component (2-7) is used to perform frequency up-conversion on the pump light and the signal light to generate sum frequency light; The signal light emitted by the signal laser (1-1) is linearly polarized light, which first passes through a polarization-maintaining module (2-1) to adjust the polarization state and power of the laser in the rear optical path, and then passes through a fast scanning module (2-2) and a fiber focusing lens (2-3) in sequence to irradiate the surface of the target to be measured, and the reflected light from the surface of the target to be measured is received by a Cassegrain system (2-4) coaxially placed behind the fiber focusing lens (2-3); When the signal light is incident on the beam return mirror, the beam return mirror of the fast delay line performs continuous linear motion under the uniform speed drive of the voice coil motor. The change of the reflection point will produce a change in the optical delay position. According to the optical path relationship between the reflected light and the incident light, the generated optical delay distance L is twice the change of the reflection point along the direction of movement of the voice coil motor, as shown in formula (1): L=2·x (1) Where x is the distance change of the reflection point on the beam return mirror along the direction of movement of the voice coil motor; According to the motion relationship, the optical delay time τ is as shown in formula (2): τ=2·v·t / c (2) Among them, v is the movement speed of the voice coil motor, c is the speed of light, and t is the movement time of the beam return mirror; When the voice coil motor moves at a constant speed, the optical delay time is linearly related to the movement time of the beam return mirror. When the optical delay time τ of the scan is fixed, when the running speed v of the voice coil motor is increased, the movement time t of the beam return mirror will decrease accordingly, and vice versa. The reciprocal of the beam return mirror movement time t is the scanning frequency f of the fast delay line, as shown in formula (3): f=1 / t=v / x (3) Among them, v is the movement speed of the voice coil motor, and x is the change of the reflection point on the beam return mirror along the movement direction of the voice coil motor; While completing the above movement process, the voice coil motor platform generates a trigger pulse for the high-speed data acquisition card. After receiving the pulse, the high-speed data acquisition card starts analog-to-digital conversion and collects single-photon signals to achieve rapid detection of single photons. The pump light emitted by the pump laser (1-2) also first passes through a polarization-maintaining module (2-1) to achieve power and polarization state adjustment. The pump light passes through a slow delay line (2-6) to achieve delay matching with the signal light, ensuring that within the adjustment range of the slow delay line (2-6), the signal light pulse and the pump light pulse can overlap in the BBO crystal component (2-7), pass through a dichroic mirror (2-5), and are coupled into a collimator and a polarization-maintaining optical fiber (2-9). The signal light and the pump light enter the BBO crystal component (2-7) together, and the sum frequency photons generated after the frequency conversion are filtered out by the polarization receiving module (2-8). The sum frequency photons are coupled into the collimator and the polarization-maintaining optical fiber (2-9) and detected by the single photon detector (3-1). The readout signal of the single photon detector (3-1) is connected to the time digital converter (3-2). The time digital converter (3-2) is synchronized with the pump light pulse through the electrical signal, and the time-correlated single photon measurement is performed. The polarization-maintaining module (2-1) and the polarization receiving module (2-8) are used in combination as a necessary noise reduction means in the optical path subsystem to improve imaging accuracy; The signal light and the pump light are both linearly polarized lights with high extinction ratios. After being reflected by the detection target, they are generally depolarized into partially polarized lights and reach the polarization receiving module (2-8). The linearly polarized echo component passes through the analyzer and enters the single-photon detector (3-1). Other polarization state components including background noise will be suppressed, thereby realizing the processing of low signal-to-noise ratio echoes, removing background noise in the optical path subsystem (2), improving the signal-to-noise ratio, and improving the imaging quality of the laser radar.

3. The scanning device of a single-photon laser radar three-dimensional imaging system for dynamic targets according to claim 1, characterized in that: The imaging detection is carried out in the following steps: Step 1: Setting the parameters of the laser emission subsystem (1) through the control subsystem (5) to adjust the repetition rate, pulse width and power of the signal light and the pump light; Step 2: Setting the parameters of the two-dimensional turntable (6) through the control subsystem (5) and controlling the rotation direction of the two-dimensional turntable (6) so that the single-photon radar system is aimed at a scene area containing the dynamic cooperative target to be detected; Step 3: The control subsystem (5) controls the scanning mode of the two-dimensional turntable (6) and the automatic focusing of the Cassegrain system (2-4), so that the optical path subsystem (2) starts scanning the dynamic cooperative target to be measured and collects its optical information data; Step 4: Collect optical information through the detection subsystem (3), collect the synchronization signal of the single photon radar system, and the echo signal and angle information of the target at different positions; Step 5: Transmit the echo signal and angle information in step 4 to the data processing subsystem (4), record the TOF, peak value and angle, and obtain the point cloud information of the dynamic target under test at different positions; Step 6: Process the three-dimensional point cloud information through the data processing subsystem (4) to reconstruct a dynamic three-dimensional image of the dynamic target being measured.

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