Anti-interference laser radar ranging system and method

Abstract

The invention discloses an anti-interference laser radar ranging system and method, and belongs to the technical field of laser detection. Comprising the steps that an optical annular feedback cavity integrated with an adjustable half-wave plate is constructed outside a VCSEL light source, the VCSEL works at a specific position by adjusting the angle of the half-wave plate and pumping current, and therefore a cross-polarization mode of the VCSEL is excited to generate a broadband and pseudo-random noise-like pulse pair serving as a detection signal. The signal receiving module collects echo signals reflected by a target and local reference signals through a photoelectric detector, processes the echo signals and the local reference signals through a cross-correlation algorithm, accurately extracts flight time from cross correlation of noise-like signals and deterministic signals, and then calculates the distance of the target. According to the invention, the anti-interference characteristic of a physical layer of a noise-like signal and the high gain of cross-correlation processing are utilized to synchronously realize high measurement precision, strong environment anti-interference capability and online adjustability of system performance, and a more reliable distance measurement solution is provided for complex scenes such as automatic driving and high-end security and protection.

Description

Technical Field

[0001] This invention belongs to the field of laser detection technology and relates to an anti-interference laser radar ranging system and method. Background Technology

[0002] LiDAR, as an important active detection technology, has played a crucial role in fields such as autonomous driving, intelligent robotics, and high-precision 3D mapping. Traditional LiDAR systems mostly employ pulsed light sources and the time-of-flight ranging principle. By emitting short-pulse lasers and measuring the time delay of their reflection from the target, the system can calculate the target distance and then construct a 3D point cloud.

[0003] However, as application scenarios evolve towards greater complexity and dynamism, two inherent contradictions have gradually emerged in the performance improvement of such pulsed light source-based systems. First, when increasing transmission power or deployment density to enhance detection capabilities, the system becomes susceptible to crosstalk from co-frequency devices and external malicious interference, resulting in poor environmental robustness. Second, limited by the pulse time-of-flight principle, it is difficult to balance measurement accuracy and response speed; high-precision measurement often comes at the cost of real-time performance. These contradictions have become key technical bottlenecks restricting the high-reliability, large-scale application of lidar in complex, highly dynamic scenarios.

[0004] In recent years, vertical-cavity surface-emitting lasers (VCSELs) have been considered ideal light sources for driving the development of lidar towards solid-state, chip-based, and low-cost applications due to their outstanding advantages such as small size, low power consumption, low manufacturing cost, good beam quality, and ease of large-scale two-dimensional array integration. Next-generation lidar systems based on VCSEL light sources have shown enormous application potential.

[0005] However, how to fully utilize the unique advantages of VCSELs to construct a new ranging system architecture and signal processing method, thereby simultaneously solving the inherent contradiction between poor interference robustness and the difficulty in balancing accuracy and speed faced by traditional systems, remains a core technical challenge that urgently needs to be overcome in this field. Summary of the Invention

[0006] The purpose of this invention is to solve the technical problem that existing lidar ranging systems often use pulsed light sources and time-of-flight ranging, resulting in poor anti-interference capabilities and an inability to simultaneously achieve measurement accuracy and response speed. The invention provides an anti-interference lidar ranging system and method.

[0007] To achieve the above objectives, the present invention employs the following technical solution: The first aspect of this invention provides an anti-interference lidar ranging system, comprising: Signal transmitting module, signal receiving module, and signal processing unit; The signal transmission module includes a VCSEL laser and an external delay feedback structure; the beam emitted by the VCSEL laser is emitted after passing through the external delay feedback structure. The signal receiving module receives the light beam emitted by the signal transmitting module, including a polarizing beam splitter PBS2, a photodetector PD1, and a photodetector PD2; The received beam is split by the polarizing beam splitter PBS2. The first beam is reflected by the target to the photodetector PD2 to obtain the echo signal; the second beam enters the photodetector PD1 to obtain the reference signal. The signal processing unit is used to calculate the target distance based on the echo signal and the reference signal using a cross-correlation algorithm.

[0008] Furthermore, the external delay feedback structure includes: a polarizing beam splitter PBS1 and several reflectors; The beam emitted by the VCSEL laser enters the polarizing beam splitter PBS1, is polarized, and is reflected by several mirrors to form a ring circuit. It then returns to the polarizing beam splitter PBS1 and is emitted to the polarizing beam splitter PBS2. A half-wave plate is provided on the ring circuit.

[0009] Furthermore, a beam splitter BS is disposed between the VCSEL laser and the polarizing beam splitter PBS1.

[0010] Furthermore, the half-wave plate is mounted on an electrically driven displacement stage.

[0011] Furthermore, both the photodetector PD2 and the photodetector PD1 are connected to an oscilloscope.

[0012] Furthermore, optical isolators (OIs) are provided between the first beam of light and the target, and between the second beam of light and the photodetector PD1.

[0013] A second aspect of the present invention provides an anti-interference lidar ranging method, comprising the following steps: The beam emitted by the VCSEL laser is emitted after passing through an external delay feedback structure; the external delay feedback structure is equipped with a half-wave plate. The received beam is split by the polarizing beam splitter PBS2. The first beam is reflected by the target to the photodetector PD2 to obtain the echo signal; the second beam enters the photodetector PD1 to obtain the reference signal. The target distance is calculated using a cross-correlation algorithm based on the echo signal and the reference signal.

[0014] Furthermore, by rotating the angle of the half-wave plate in front of the beam emitted by the VCSEL laser, the coupling strength and phase relationship between the two orthogonal linear polarization modes of the VCSEL laser are adjusted.

[0015] Furthermore, by adjusting the pump current of the VSCEL laser in front of the beam emitted by the VSCEL laser, the working range and pulse width of the noise-like pulse signal are adjusted.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses an anti-interference lidar ranging system that actively generates a noise-like detection signal with wide-spectrum, pseudo-random characteristics through the collaborative operation of a VCSEL and an external feedback structure. This signal has a unique morphology and extremely low correlation with conventional pulse signals, giving the system a natural ability to suppress crosstalk from common co-frequency devices and active malicious interference in the environment, thus maintaining stable and reliable ranging performance even in complex electromagnetic environments. The system uses a cross-correlation algorithm to process the noise-like signal, achieving an extremely sharp correlation peak in the time domain (equivalent to an extremely narrow detection pulse), thereby achieving high range resolution and high ranging accuracy. This accuracy improvement mainly relies on the back-end signal processing algorithm, which is relatively decoupled from the physical modulation speed of the light source. Therefore, the system achieves ultra-high ranging accuracy without sacrificing data update rate and response speed, meeting the real-time requirements of high-dynamic scenarios.

[0017] Furthermore, by adjusting the VCSEL pump current and optical adjustment (adjustable half-wave plate in the feedback structure), the time-domain / frequency-domain characteristics (such as pulse width and repetition frequency) of the generated noise-like signal can be controlled in real time and dynamically. This allows users to optimize the system's ranging range, basic resolution, and measurement speed online according to the actual application scenario (such as long-distance mapping or short-distance obstacle avoidance). Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a structural diagram of the anti-interference lidar ranging system of the present invention; Figure 2 This is a typical temporal dynamic characteristic of the TE mode and TM mode of a VCSEL laser in a signal transmission module according to an embodiment of the present invention; Figure 3 The measured signal and processing results of the system under the condition of target echo presence; Figure 4 (a) shows the offset of the anticorrelation peak in the cross-correlation function relative to zero time delay when the target object is at different distances; Figure 4Figure (b) shows the relationship between the amplitude of the inverse correlation peak and the rotation angle of the half-wave plate inside the annular cavity. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0022] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0023] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0024] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0025] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0026] The present invention will now be described in further detail with reference to the accompanying drawings: See Figure 1 This invention provides a lidar ranging system, comprising: The system comprises a signal transmitting module, a signal receiving module, and a signal processing unit; the signal transmitting module emits a beam toward the target; the signal receiving module receives the beam reflected by the target and performs mutual processing through the signal processing unit to achieve distance calculation; The signal transmission module includes a VCSEL laser and an external delay feedback structure; the beam emitted by the VCSEL laser is emitted after passing through the external delay feedback structure. The signal receiving module includes a polarizing beam splitter PBS2, a photodetector PD1, and a photodetector PD2; The received signal is split by the polarizing beam splitter PBS2. The first beam is reflected by the target to the photodetector PD2, and the second beam enters the photodetector PD1.

[0027] The specific implementation of the above embodiments is as follows: The system includes a signal transmitting module and a signal receiving module. The signal transmitting module includes a semiconductor VCSEL light source and an external ring cavity, inside which a half-wave plate is placed; the signal receiving module includes a target object and a photodetector. In the signal transmission module, the beam emitted by the semiconductor VCSEL laser is collimated and then split into two paths by a beam splitter prism (BS, 50:50): a reference path and a feedback probe path. The reference path is a beam that is directly fed into the receiving module as a local reference signal. The feedback probe path is a beam that enters the external optical ring cavity. This beam first passes through a polarization-maintaining beam splitter prism (PBS1), separating it according to its orthogonal polarization states (TE mode and TM mode). Subsequently, the two polarized beams propagate clockwise and counterclockwise along the ring cavity, respectively. An adjustable half-wave plate (λ / 2) is installed inside the cavity; as the beam passes through, its polarization state rotates by 90 degrees (TE and TM modes switch). Finally, after a delay, the two beams are coupled back into the VCSEL laser cavity. This feedback process can be precisely controlled by a computer via an automatic rotation device that adjusts the angle of the half-wave plate. The external annular cavity of the signal transmission module is constructed using polarization-maintaining optical elements (such as a polarization-maintaining beam splitter) to feed a portion of the laser output from the VCSEL back into its resonant cavity, forming an external resonant circuit with specific delay and feedback strength. The polarization-maintaining beam splitter ensures that the TE mode and TM mode maintain independent transmission and controllable coupling during the feedback process.

[0028] The half-wave plate is precisely positioned within the optical path of the external annular cavity. By precisely rotating its angle, the relative phase and intensity ratio between the TE and TM modes propagating in the feedback optical path can be continuously and dynamically adjusted, which is crucial for exciting and controlling specific laser dynamics.

[0029] In the signal receiving module, the reference light from the signal transmitting module is first polarized by a polarization-maintaining beam splitter prism (PBS2): the TM mode, after passing through an optical isolator (OI), is received by photodetector PD1 as a reference signal. The TE mode, after passing through an optical isolator (OI), is directed towards the target object, and its reflected echo is received by photodetector PD2 as a detection signal. The electrical signals output by the two detectors are finally synchronously acquired and recorded by a digital oscilloscope.

[0030] The specific method and steps for the signal transmission module to generate noise-like pulses are as follows: First, the pump current of the VCSEL is set so that the TE mode operates as the dominant mode in the linear region, while the TM mode is suppressed near or below the threshold. At this operating point, the half-wave plate is adjusted, thereby controlling the coupling strength and phase of the two polarization modes, resulting in continuous competition and energy exchange between the two orthogonal polarization modes.

[0031] Under these conditions, the TM mode output exhibits a dynamic, random, and wide-spectrum noise-like pulse sequence. This sequence possesses excellent autocorrelation characteristics (sharp peaks) and weak cross-correlation, making it an ideal anti-interference detection signal. By coordinating the adjustment of the pump current (changing the operating point) and the half-wave plate angle (changing the coupling strength), the width, repetition frequency, and energy distribution of this type of noise pulse can be tuned, thereby enabling the reconfigurability of key parameters such as the system's ranging range and fundamental resolution.

[0032] The signal receiving module is used to capture the weak echo signal reflected by the target and perform distance calculation. Its core components include: Photodetector: A high-sensitivity detector used to convert received optical echo signals into electrical signals.

[0033] Signal Processing Unit: The core algorithm of this unit is cross-correlation processing. It first acquires and stores a raw, untransmitted noise-like pulse signal coupled out from the transmitting module as a reference template. Then, it performs a high-speed cross-correlation operation between the echo signal converted by the photodetector and this reference template. Due to the unique randomness and sharp autocorrelation peak of the noise-like signal, the cross-correlation function exhibits a significant peak value. The time delay (τ) corresponding to this peak value directly corresponds to the round-trip flight time of the laser pulse to the target. Finally, according to the formula: Distance = c τ / 2 Where c is the speed of light, the precise target distance is calculated.

[0034] In summary, this system actively generates a noise-like detection signal with physical layer anti-interference capabilities through the synergistic effect of VCSEL, external delay feedback loop, and adjustable half-wave plate. Combined with cross-correlation signal processing technology, it ensures the simultaneous realization of high sensitivity and strong anti-interference capability at both the hardware and algorithm levels, effectively breaking through the technical bottleneck of traditional lidar.

[0035] One embodiment of the present invention provides a specific implementation of a high-precision, highly interference-resistant lidar ranging method. The core of this system lies in using a tunable external polarization feedback loop to excite a VCSEL to generate unique noise-like pulse pairs, and utilizing their cross-correlation characteristics to achieve high-precision, interference-resistant time-of-flight ranging.

[0036] The system consists of a signal transmitting module, a signal receiving module, and a signal processing unit working together.

[0037] The transmitting module is responsible for generating and transmitting the detection signal. Its core components are a VCSEL light source and an external optical ring feedback cavity containing an adjustable half-wave plate (λ / 2). The receiving module receives and separates the echo signal from the target from the local reference signal, converting them into electrical signals via photodetectors (PD1, PD2). The signal processing unit acquires the electrical signals and extracts the time of flight by calculating the cross-correlation function between the echo signal and the reference signal, ultimately determining the target distance.

[0038] (1) Semiconductor VCSEL light source and its stabilization To achieve stable and controllable laser output, a VCSEL (Vibration Voltage Spectrometer) semiconductor with an infrared center wavelength was selected as the light source. The key to its implementation lies in precise environmental control: temperature control employs a high-precision thermoelectric cooler (TEC) and temperature sensor to form a closed-loop control system, stabilizing the VCSEL chip's operating temperature within ±0.001°C to suppress wavelength drift and mode switching. Current control utilizes a low-noise, high-stability laser driver to provide pump current to the VCSEL, with current control accuracy better than 0.01 mA, ensuring long-term stability of laser output power and threshold voltage.

[0039] (2) Construction of external delay feedback ring cavity To achieve control over the polarization dynamics of VCSELs, an external optical fiber or free-space optical ring cavity was constructed.

[0040] Optical path configuration: The collimated beam from the VCSEL is guided into the annular cavity by a beam splitter (BS). Inside the cavity, a polarization-maintaining beam splitter (PBS1), an adjustable half-wave plate, a mirror, and an optical delay line are sequentially arranged to form a closed loop.

[0041] Polarization separation and feedback: The beam is first separated by PBS1 according to its orthogonal linear polarization states (TE mode and TM mode). Thereafter, the two beams propagate independently in opposite directions (such as clockwise and counterclockwise) within the cavity.

[0042] Mode switching mechanism: The half-wave plate is the key tunable element within this cavity. When the TE and TM mode beams pass through the half-wave plate, their polarization directions rotate by 90 degrees; that is, the TE mode converts to the TM mode, and the TM mode converts to the TE mode. The rotated beams then propagate and converge again at PBS1, ultimately feeding back into the VCSEL's resonant cavity. This feedback process introduces controllable delay and polarization coupling.

[0043] (3) Excitation and modulation of noise-like impulses Setting and adjusting the system's operating point is crucial for generating the desired signal. The specific steps are as follows: Setting the operating point: First, adjust the pump current of the VCSEL so that the dominant TE mode operates above the linear region, while the TM mode is suppressed near the threshold. At this point, the TE mode output exhibits regular relaxation oscillations (e.g., ...). Figure 2 (a) is shown.

[0044] Achieving frequency resonance: Finely adjust the pump current or fine-tune the cavity length of the external ring cavity (e.g., by moving a mirror inside the cavity) to make the relaxation oscillation frequency of the TE mode resonate with the eigenfrequency of the external ring cavity. This is a prerequisite for exciting nonlinear dynamics.

[0045] Excitation and modulation of noise-like pulses: Under the aforementioned resonance conditions, a half-wave plate within the ring cavity is rotated. By changing its angle, the intensity ratio and relative phase of the TE and TM modes in the feedback optical path can be continuously adjusted. When the coupling conditions are suitable, strong polarization mode competition and nonlinear interactions are excited, causing the output of the TM mode to transition from a steady state to a wide-spectrum, noise-like pulse sequence (e.g., ...). Figure 2 (b) shows that the dynamics of the TE mode are also modulated. By programmatically controlling the half-wave plate angle, the statistical characteristics of this type of noise pulse can be adjusted in real time.

[0046] (4) Signal reception and distance calculation The optical signal generated by the transmitting module is split into two paths by a beam splitter (BS): one path is used as probe light and directed toward the target; the other path is used as reference light and directly enters the receiving module.

[0047] Signal Separation and Detection: In the receiving module, another polarization-maintaining beam splitter prism (PBS2) is used to separate the beam containing the echo and the reference beam according to their polarization states. One polarization component (such as the TM mode) is detected by PD1 as a local reference signal; the echo of the other orthogonally polarized component (such as the TE mode) after reflection from the target is detected by PD2 as a detection signal. An optical isolator (OI) is used to suppress unwanted back reflections.

[0048] Cross-correlation processing and ranging: The digital oscilloscope simultaneously acquires the electrical signals output from PD1 and PD2. The signal processing unit (which can be an embedded processor or a computer) executes the following core algorithms: 1. Extract a segment of the reference signal and an echo signal .

[0049] 2. Calculate the cross-correlation function between the two. .

[0050] 3. Due to the characteristics of noise-like signals, this cross-correlation function has a specific time delay. A sharp inverse correlation peak will appear at this point (e.g.) Figure 2 (c) and 3(c) are shown.

[0051] 4. The offset of this peak position relative to zero delay This refers to the round-trip flight time of the light pulse to the target. Target distance. From the formula The calculation shows that, among which It is the speed of light. Figure 4 As shown in (a), the measured distance and time delay are highly linearly related, which verifies the accuracy of the distance measurement.

[0052] 5. By monitoring the amplitude of the inverse correlation peak (e.g. Figure 4 (b) can be used to evaluate signal quality and control the angle of the half-wave plate through feedback, so that the system always works at the best resolution and accuracy.

[0053] The above embodiments demonstrate that the present invention, through precise hardware configuration and specific control methods, has successfully achieved high-performance lidar ranging based on VCSEL-type noise pulses.

[0054] Figure 2 The typical time-domain dynamics of the TE and TM modes of the VCSEL laser in the signal transmission module are shown. Figures (a) and (b) show the time-domain waveforms of the TE and TM modes, respectively. It can be seen that the TE mode exhibits regular relaxation oscillations, while the TM mode displays noise-like pulse behavior. Figure (c) shows the cross-correlation function curves of the TE and TM signals. At zero time delay (τ=0), a very sharp anti-correlation peak appears, which is the core characteristic of the signal used in this invention.

[0055] Figure 3 The measured signal and processing results of the system are shown under the condition of target echo presence. Figures (a) and (b) show the time-domain waveforms of the TE mode and TM mode, respectively. Figure (c) shows their cross-correlation function curves. Figure 2 (c) As can be seen from the comparison, the position of the anticorrelation peak shifts from τ=0 to τ=13.0 ns. This time delay corresponds to the round-trip flight time of the light pulse, and the target distance is calculated to be 1.95 meters, which directly verifies the ranging capability of the system.

[0056] Figure 4 Figure (a) shows the offset of the anticorrelation peak in the cross-correlation function relative to zero time delay when the target object is at different distances. The data shows that the measured time delay has a strictly linear relationship with the target distance, proving that the system possesses excellent ranging linearity and accuracy. Figure (b) shows the relationship between the amplitude of the anticorrelation peak and the rotation angle of the half-wave plate within the annular cavity. The results indicate that by adjusting the angle of the half-wave plate, the detection performance of the system can be effectively controlled, thus providing a direct basis for flexibly optimizing measurement resolution and accuracy.

[0057] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An anti-interference lidar ranging system, characterized in that, include: Signal transmitting module, signal receiving module, and signal processing unit; The signal transmission module includes a VCSEL laser and an external delay feedback structure; the beam emitted by the VCSEL laser is emitted after passing through the external delay feedback structure. The signal receiving module receives the light beam emitted by the signal transmitting module, including a polarizing beam splitter PBS2, a photodetector PD1, and a photodetector PD2; The received beam is split by the polarizing beam splitter PBS2. The first beam is reflected by the target to the photodetector PD2 to obtain the echo signal; the second beam enters the photodetector PD1 to obtain the reference signal. The signal processing unit is used to calculate the target distance based on the echo signal and the reference signal using a cross-correlation algorithm.

2. The anti-interference lidar ranging system according to claim 1, characterized in that, The external delay feedback structure includes: a polarizing beam splitter PBS1 and several mirrors; The beam emitted by the VCSEL laser enters the polarizing beam splitter PBS1, is polarized, and is reflected by several mirrors to form a ring circuit. It then returns to the polarizing beam splitter PBS1 and is emitted to the polarizing beam splitter PBS2. A half-wave plate is provided on the ring circuit.

3. The anti-interference lidar ranging system according to claim 2, characterized in that, A beam splitter BS is disposed between the VCSEL laser and the polarizing beam splitter PBS1.

4. The anti-interference lidar ranging system according to claim 2, characterized in that, The half-wave plate is mounted on an electrically operated displacement stage.

5. The anti-interference lidar ranging system according to claim 1, characterized in that, Both photodetector PD2 and photodetector PD1 are connected to an oscilloscope.

6. The anti-interference lidar ranging system according to claim 1, characterized in that, An optical isolator (OI) is provided between the second beam of light and the photodetector PD1.

7. The anti-interference lidar ranging system according to claim 1, characterized in that, An optical isolator (OI) is provided between the first beam of light and the target.

8. An anti-interference lidar ranging method, characterized in that, Includes the following steps: The beam emitted by the VCSEL laser is emitted after passing through an external delay feedback structure; the external delay feedback structure is equipped with a half-wave plate. The received beam is split by the polarizing beam splitter PBS2. The first beam is reflected by the target to the photodetector PD2 to obtain the echo signal; the second beam enters the photodetector PD1 to obtain the reference signal. The target distance is calculated using a cross-correlation algorithm based on the echo signal and the reference signal.

9. The anti-interference lidar ranging method according to claim 8, characterized in that, By rotating the angle of the half-wave plate in front of the beam emitted by the VCSEL laser, the coupling strength and phase relationship between the two orthogonal linear polarization modes of the VCSEL laser are adjusted.

10. The anti-interference lidar ranging method according to claim 8, characterized in that, In front of the beam emitted by the VCSEL laser, the working range and pulse width of the noise-like pulse signal are adjusted by regulating the pump current of the VCSEL laser.

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