An all-fiber liquid level measurement system and method based on dual optical comb phase decoupling and adaptive compensation

Abstract

This invention discloses an all-fiber liquid level measurement system and method based on dual-comb phase decoupling and adaptive compensation. The system includes a dual-comb light source module, an optical fiber coupling module, a signal acquisition and processing system, an adaptive compensation module, a measuring arm, and a reference arm. The optical fiber coupling module includes a polarization-maintaining fiber beam splitter and a polarization-maintaining fiber beam combiner. The signal acquisition and processing system includes a balanced detector, a lock-in amplifier, and a host computer connected sequentially from front to back. The lock-in amplifier is connected to the adaptive compensation module. The dual-comb light source module is connected to the measuring arm and the reference arm respectively through the polarization-maintaining fiber beam splitter. The measuring arm and the reference arm are respectively connected to the balanced detector through the polarization-maintaining fiber beam combiner. This invention combines interference signal intensity and phase information to solve the problem of reflectivity difference between transparent and opaque liquids, eliminates phase noise caused by environmental disturbances, and improves measurement stability. This invention achieves non-contact, real-time, and high-resolution measurement of liquid level, especially for measurement in high-pressure, high-temperature, or corrosive environments, expanding its application range.

Description

Technical Field

[0001] This invention belongs to the technical field of optical fiber liquid level measurement, specifically relating to an all-optical fiber liquid level measurement system and method based on dual optical comb phase decoupling and adaptive compensation. Background Technology

[0002] Liquid level measurement technology plays a crucial role in industrial control, energy storage, and fuel dispensing. This technology includes both contact and non-contact methods. For example, current contact-based liquid level measurement, primarily using float-type and capacitive sensors, requires direct contact with the liquid, making it susceptible to environmental conditions, costly to maintain, and unsuitable for measuring high-temperature, high-pressure, or corrosive media. Non-contact optical measurement, mainly using lidar and laser triangulation, relies on single-wavelength lasers, is easily affected by changes in liquid surface reflectivity, has limited resolution, and is sensitive to environmental factors such as air turbulence and vibration, requiring complex vibration isolation designs and calibrations. Microwave / ultrasonic sensing, on the other hand, suffers from errors amplified by changes in the dielectric constant or sound velocity of the medium, failing to meet sub-millimeter level measurement requirements, and is also challenging to detect at gas-liquid interfaces.

[0003] Currently, optical frequency combs have become an emerging tool for precision ranging due to their wide spectrum and high frequency stability. However, for liquid level measurement, optical frequency combs are easily affected by environmental disturbances (temperature, vibration), leading to fluctuations in the optical path of the measurement optical path and introducing phase noise, which can obscure the liquid level signal. At the same time, traditional dual optical combs require independent light sources and spatial optical paths, introducing multiple discrete components, which is not conducive to on-site deployment. When the liquid surface fluctuates or the refractive index changes, it will also be impossible to stably track the phase changes carrying liquid level information. Summary of the Invention

[0004] The purpose of this invention is to provide an all-fiber liquid level measurement system and method based on dual-comb phase decoupling and adaptive compensation, in order to solve the above-mentioned problems.

[0005] This invention is mainly achieved through the following technical solutions:

[0006] A fully fiber-optic liquid level measurement system based on dual-comb phase decoupling and adaptive compensation includes a dual-comb light source module, an optical fiber coupling module, a signal acquisition and processing system, an adaptive compensation module, a measuring arm, and a reference arm. The optical fiber coupling module includes a polarization-maintaining fiber beam splitter and a polarization-maintaining fiber beam combiner. The signal acquisition and processing system includes a balanced detector, a lock-in amplifier, and a host computer connected sequentially from front to back. The lock-in amplifier is connected to the adaptive compensation module. The dual-comb light source module is connected to the measuring arm and the reference arm respectively through the polarization-maintaining fiber beam splitter. The measuring arm and the reference arm are respectively connected to the balanced detector through the polarization-maintaining fiber beam combiner.

[0007] The dual-comb light source module is used to emit dual-comb laser light, and the polarization-maintaining fiber beam splitter is used to split the dual-comb laser light into reference light and measurement light, which are then input into the reference arm and measurement arm respectively.

[0008] The adaptive compensation module is used to control the reference arm based on the phase difference feedback from the lock-in amplifier, and adjust the dynamic compensation of the optical path of the reference light; the reference arm is used to output the compensated reference light to the polarization-maintaining fiber combiner.

[0009] The measuring arm is used for liquid level measurement and outputs the measuring light reflected from the liquid surface to the polarization-maintaining fiber combiner.

[0010] The balanced photodetector is used to receive the interference signal output from the polarization-maintaining fiber combiner and output the beat frequency signal f. beat To a lock-in amplifier, the lock-in amplifier is used to extract the beat frequency signal f beat The phase difference.

[0011] To better realize the present invention, the adaptive compensation module further includes a PID controller and a PZT driver connected to each other. The reference arm includes an optical fiber circulator 1, a PZT optical fiber stretcher, and an optical fiber reflector connected sequentially from front to back. The PZT driver is connected to the PZT optical fiber stretcher. The optical fiber circulator 1 is connected to the dual-comb light source module and the polarization-maintaining optical fiber combiner, respectively, to realize that the reference light enters the optical fiber reflector through the optical fiber circulator 1 and the PZT optical fiber stretcher. The optical path of the reference light is fixed. After being reflected by the end face of the optical fiber reflector, it enters the polarization-maintaining optical fiber combiner through the optical fiber circulator 1.

[0012] To better realize the present invention, the measuring arm further includes an optical fiber circulator 2 and an optical fiber collimator connected to each other. The optical fiber circulator 2 is connected to a polarization-maintaining fiber splitter and a polarization-maintaining fiber combiner, respectively, so as to realize that the measuring light enters the optical fiber collimator through the optical fiber circulator 2, and after collimation, the emitted spatial light is sent to the liquid surface to be measured. After being reflected by the liquid surface, it returns to the optical fiber collimator, the optical fiber circulator 2 and the polarization-maintaining fiber combiner in sequence.

[0013] To better realize the present invention, both the fiber circulator 1 and the fiber circulator 2 are polarization-maintaining fiber circulators.

[0014] To better realize the present invention, the dual optical comb light source module is further connected to the polarization-maintaining fiber beam splitter via an optical fiber isolator.

[0015] To better realize the present invention, the splitting ratio of the polarization-maintaining fiber beam splitter and the polarization-maintaining fiber beam combiner is 50:50.

[0016] This invention is mainly achieved through the following technical solutions:

[0017] A method for measuring liquid level using an all-fiber optic cable based on dual-comb phase decoupling and adaptive compensation includes the following steps:

[0018] Step S1: Emit dual optical combs and split the beams to form a reference beam and a measurement beam;

[0019] Step S2: The measurement light is emitted to the surface of the liquid to be measured, and after being reflected by the liquid surface, it returns to the polarization-maintaining fiber combiner;

[0020] Step S3: The polarization-maintaining fiber combiner combines the received reference light and the measurement light, and the interference signal is received by the balanced photodetector, which outputs the beat frequency signal.

[0021] Where: N is the number of optical comb modes;

[0022] Δf r The difference in repetition frequency between the two optical combs;

[0023] The phase difference is caused by changes in liquid level;

[0024] t represents time;

[0025] Step S4: For the beat frequency signal f beat Perform a Fourier transform to extract the phase difference.

[0026] Step S5: If Based on phase difference Adjust the dynamic compensation of the reference light's optical path length; output the compensated reference light to the polarization-maintaining fiber combiner and proceed to step S3; if Then proceed to step S6;

[0027] in: This is the calibrated value for the phase difference;

[0028] ε is the set threshold;

[0029] Step S6: Calculate the change in liquid level height:

[0030]

[0031] Where: λ is the center wavelength of the optical comb;

[0032] n is the refractive index of the liquid.

[0033] To better realize the present invention, further, in step S5, the output signal V(t) drives the PZT fiber stretcher, whose axial expansion ΔLz = βV(t), where β is the expansion ratio coefficient; the reference optical path change ΔL ref =2ΔLz, to offset the ΔL introduced by environmental disturbances.nosie .

[0034] To better implement this invention, furthermore, the ΔL of each compensation is recorded. ref Given the output signal V(t) and the optimal PID parameters for different temperatures and refractive indices, machine learning is used to optimize the PID parameters and establish a lookup table to achieve self-optimization of the PID control parameters. For example, the existing technology CN105973544B can be used to optimize the PID parameters.

[0035] The beneficial effects of this invention are as follows:

[0036] (1) This invention, based on the repetition frequency difference and phase decoupling algorithm of a dual optical comb and combined with adaptive optical path compensation, achieves non-contact, real-time, and high-resolution measurement of liquid level height. It is suitable for monitoring the liquid level of both transparent and opaque liquids, especially in high-pressure, high-temperature, or corrosive environments. This invention combines interference signal intensity and phase information to solve the problem of reflectivity differences between transparent and opaque liquids, thus expanding its application range. Specifically, this invention utilizes the repetition frequency difference (Δf) of the dual optical comb... r Phase difference caused by liquid level change The joint solution eliminates phase noise caused by environmental disturbances in traditional single-comb measurements, thus improving measurement stability.

[0037] (2) This invention employs an adjustable optical path delay device driven by piezoelectric ceramics to compensate for additional optical path differences caused by changes in temperature or liquid refractive index in real time, ensuring that measurement accuracy is not affected by environmental parameters. The core optical path of this invention uses polarization-maintaining fiber and a polarization-maintaining fiber coupler, avoiding the problem of spatial optical path sensitivity to vibration and enhancing the applicability to industrial environments. Attached Figure Description

[0038] Figure 1 This is a block diagram of the principle of the all-fiber liquid level measurement system based on dual optical comb phase decoupling and adaptive compensation of the present invention.

[0039] Figure 2 This is a flowchart of the adaptive compensation in Example 3. Detailed Implementation

[0040] Example 1:

[0041] A fully fiber optic liquid level measurement system based on dual-comb phase decoupling and adaptive compensation, such as... Figure 1 As shown, it includes a dual optical comb light source module, an optical fiber isolator, a polarization-maintaining fiber bundler, a polarization-maintaining fiber bundle combiner, an optical fiber collimator, an optical fiber mirror, an optical fiber circulator 1, an optical fiber circulator 2, an adaptive compensation module, a balanced photodetector, a lock-in amplifier, a host computer, a temperature sensor, and a refractive index sensor.

[0042] The fiber circulator 1, the PZT fiber stretcher, and the fiber reflector constitute the reference arm of the measurement system.

[0043] The fiber optic circulator 2, the fiber optic collimator, and the liquid level to be measured constitute the measuring arm of the measuring system;

[0044] The balanced photodetector, lock-in amplifier, and host computer constitute the signal acquisition and signal processing system of the measurement system.

[0045] The PID controller, PZT driver, and PZT fiber stretcher constitute an adaptive compensation module.

[0046] The dual-comb light source module outputs dual-comb laser light through a polarization-maintaining fiber. The polarization-maintaining fiber is connected to the input end of a polarization-maintaining fiber isolator, and the output end of the fiber isolator is then connected to the input end of a polarization-maintaining fiber beam splitter.

[0047] The output port 2 of the polarization-maintaining fiber beam splitter is connected to the reference arm. Specifically, in the reference arm, the output port 1 of the polarization-maintaining fiber beam splitter is connected to the port (1) of the fiber circulator 1, the port (2) of the fiber circulator 1 is connected to the PZT fiber stretcher, the other end of the PZT fiber stretcher is connected to the fiber reflector, and the port (3) of the fiber circulator 1 is connected to the input port 1 of the polarization-maintaining fiber combiner.

[0048] The output port 1 of the polarization-maintaining fiber beam splitter is connected to the measuring arm. Specifically, in the measuring arm, the output port 1 of the polarization-maintaining fiber beam splitter is connected to the port (1) of the fiber circulator 2, the port (2) of the fiber circulator 2 is connected to the fiber collimator, the fiber collimator is installed above the liquid surface to be measured, and the port (3) of the fiber circulator 2 is connected to the input port 2 of the polarization-maintaining fiber combiner.

[0049] The output end of the polarization-maintaining fiber combiner is connected to the input end of the balanced photodetector, the output end of the balanced photodetector is connected to the input end of the lock-in amplifier, the lock-in amplifier is then connected to the host computer and the PID controller, the PID controller is connected to the PZT driver, and the PZT controller is finally connected to the PZT fiber stretching machine.

[0050] In this invention, the dual-comb light source module provides dual-comb output throughout the measurement system, while the reference arm provides a stable phase reference. A fixed optical path design is employed, utilizing armored fiber and shock-absorbing encapsulation to reduce the impact of temperature and vibration on the fixed optical path. The reference arm incorporates an adaptive compensation module, using a lock-in amplifier to feed back the phase difference input to a PID controller for PZT fiber stretching, achieving dynamic compensation of the optical path and offsetting phase noise caused by environmental interference. An adaptive algorithm is also introduced to achieve rapid dynamic compensation of the optical path. The reference arm's phase is adjustable and can be used for system calibration and temperature drift correction. The measuring arm is used for direct liquid level measurement.

[0051] Example 2:

[0052] An all-fiber optic liquid level measurement system based on dual-comb phase decoupling and adaptive compensation is proposed for measuring the liquid level in a fuel tank. The measurement system is modularized, such as... Figure 1 As shown, the system mainly includes a dual-comb light source module, a reference arm, a measurement arm, an optical fiber coupling module, a signal acquisition and processing system, and an adaptive compensation module. The optical fiber coupling module includes a polarization-maintaining fiber splitter and a polarization-maintaining fiber combiner. All modules are packaged in a single chassis, with an optical fiber collimator serving as the measurement probe. The optical fiber collimator is connected to the system chassis via a pigtail, allowing for adaptation to different installation scenarios and making the invention suitable for various harsh measurement environments.

[0053] Preferably, the fiber optic circulator 1, the PZT fiber stretcher, and the fiber optic reflector constitute the reference arm of the measurement system;

[0054] The fiber optic circulator 2, the fiber optic collimator, and the liquid level to be measured constitute the measuring arm of the measuring system;

[0055] The balanced photodetector, lock-in amplifier, and host computer constitute the signal acquisition and signal processing system of the measurement system.

[0056] The PID controller, PZT driver, and PZT fiber stretcher constitute an adaptive compensation module.

[0057] The dual-comb light source module outputs dual-comb laser light through a polarization-maintaining fiber. The polarization-maintaining fiber is connected to the input end of a polarization-maintaining fiber isolator, and the output end of the fiber isolator is then connected to the input end of a polarization-maintaining fiber beam splitter.

[0058] Preferably, in this embodiment, the chassis of the measurement system can be placed in a more balanced environment. The fiber optic collimator is connected to the measurement system via optical fiber. The fiber optic collimator can be designed as a through-wall sealed connector, directly inserted into the matching access window above the oil tank. For transparent liquids, the collimator is installed perpendicular to the liquid surface; for non-transparent liquids, the collimator is installed at an angle to obtain stronger liquid surface reflection.

[0059] In use, the dual-comb light source module emits dual optical combs, which pass through an optical fiber isolator (to prevent reflected light from damaging the light source) and enter the polarization-maintaining fiber beam splitter, forming a reference beam and a measurement beam. The reference beam passes through an optical fiber circulator 1 and a PZT fiber stretcher to a fiber optic mirror. With a fixed optical path, the reference beam is reflected from the end face of the optical fiber mirror and then passes through an optical fiber circulator 1 to enter the polarization-maintaining fiber combiner. The measurement beam passes through an optical fiber circulator 2 to a fiber collimator. After collimation, it emits spatial light onto the surface of the liquid to be measured. After reflection from the liquid surface, it returns sequentially to the optical fiber collimator, optical fiber circulator 2, and the polarization-maintaining fiber combiner. The reference beam and measurement beam are then combined by the polarization-maintaining fiber combiner, and the interference signal is received by a balanced photodetector, which outputs a beat frequency signal. Where N is the number of optical comb modes, The phase difference Δf is caused by the change in liquid level. r The repetition frequency difference between the two optical combs. A lock-in amplifier extracts the beat frequency signal f. beat The phase information is processed by the host computer for signal processing and liquid level calculation. If This triggers the adaptive compensation module.

[0060] Preferably, the adaptive compensation module is used to perform optical path compensation on the reference light. It employs a piezoelectric ceramic (PZT) driver, with the PID controller outputting a signal V(t) to drive the PZT driver, causing the axial extension / retraction of the PZT fiber stretcher to be ΔLz = βV(t), where β is the extension / retraction ratio coefficient. At this time, the optical path change of the reference arm is ΔL. ref =2ΔLz, to offset the ΔL introduced by environmental disturbances. nosie .

[0061] After compensation, retesting like If the compensation is successful, then the PID controller is executed iteratively until convergence. The optimal PID parameters for each compensation (ΔLz and V(t)) under different operating conditions (environmental parameters provided by temperature and refractive index sensors) are recorded. Through machine learning, the PID parameters are optimized, a lookup table is built, and the control parameters are self-optimized for further improvement.

[0062] Example 3:

[0063] A method for measuring liquid level using an all-fiber optic cable based on dual-comb phase decoupling and adaptive compensation includes the following steps:

[0064] (1) When there is no change in liquid level, record the initial phase difference between the reference arm and the measuring arm. Adjust the optical path of the reference arm using the PZT fiber stretcher, so that Approaching zero, eliminating static errors in the system;

[0065] (2) Real-time adaptive compensation of the reference arm optical path based on changes in ambient temperature to ensure Caused solely by changes in liquid level.

[0066] (3) The change in liquid level height Δh causes a change in the optical path length of the measuring arm ΔL=2nΔh, resulting in a phase difference. The phase difference is extracted after the output signal of the balanced photodetector is Fourier transformed. Based on the real-time monitored liquid refractive index n (via an auxiliary temperature sensor or refractometer), the liquid level height is calculated as follows:

[0067]

[0068] Where: λ is the center wavelength of the optical comb;

[0069] Δf r The difference in repetition frequency between the two optical combs;

[0070] The phase difference is caused by changes in liquid level;

[0071] n is the refractive index of the liquid;

[0072] t represents time.

[0073] Preferably, such as Figure 2 As shown, the adaptive compensation of the reference arm optical path includes the following steps:

[0074] A1: Environmental parameter monitoring (temperature, refractive index): The ambient temperature T and liquid refractive index n are collected in real time by the temperature sensor and refractive index sensor in the system to provide prior parameters for optical path compensation. The temperature change ΔT will cause the optical fiber to expand ΔL1=α·L·ΔT; the optical path change caused by the refractive index change is ΔL2=LΔn.

[0075] Where: α is the coefficient of thermal expansion;

[0076] L is the length of the optical fiber.

[0077] A2: Phase difference detection: The interference signal output by the balanced photodetector is used to extract the real-time phase difference through a digital lock-in amplifier.

[0078] A3: Detect the presence of phase perturbation, i.e., if The additional phase noise is determined to be caused by environmental disturbance, triggering compensation. Proceed to step A4. Otherwise, maintain the current optical path and proceed to step (3) to further calculate the liquid level height information.

[0079] in: The initial phase difference between the reference arm and the measuring arm when there is no change in liquid level; βV(t)=ΔLz=ΔL1+ΔL2 is the optical path length compensated by PID regulation.

[0080] ε can be dynamically adjusted based on the liquid type (transparent / opaque).

[0081] A4: Generate control signal V(t), optical path adjustment is ΔLz=βV(t), reference arm optical path change ΔL ref =2ΔLz, to offset the ΔL introduced by environmental disturbances. nosie Proceed to step A2.

[0082] Where β is the scaling factor.

[0083] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for measuring liquid level using an all-fiber optic cable based on dual-comb phase decoupling and adaptive compensation, comprising a system for measuring liquid level using a dual-comb phase decoupling and adaptive compensation, characterized in that... The all-fiber liquid level measurement system includes a dual-comb light source module, an optical fiber coupling module, a signal acquisition and processing system, an adaptive compensation module, a measurement arm, and a reference arm. The optical fiber coupling module includes a polarization-maintaining fiber beam splitter and a polarization-maintaining fiber beam combiner. The signal acquisition and processing system includes a balanced detector, a lock-in amplifier, and a host computer connected sequentially from front to back. The lock-in amplifier is connected to the adaptive compensation module. The dual-comb light source module is connected to the measurement arm and the reference arm respectively through the polarization-maintaining fiber beam splitter. The measurement arm and the reference arm are respectively connected to the balanced detector through the polarization-maintaining fiber beam combiner. The dual-comb light source module is used to emit dual-comb laser light, and the polarization-maintaining fiber beam splitter is used to split the dual-comb laser light into reference light and measurement light, which are then input into the reference arm and measurement arm respectively. The adaptive compensation module is used to control the reference arm based on the phase difference feedback from the lock-in amplifier, and adjust the dynamic compensation of the optical path of the reference light; the reference arm is used to output the compensated reference light to the polarization-maintaining fiber combiner. The measuring arm is used for liquid level measurement and outputs the measuring light reflected from the liquid surface to the polarization-maintaining fiber combiner. The balanced detector is used to receive the interference signal output from the polarization-maintaining fiber combiner and output the beat frequency signal. f beat To a lock-in amplifier, the lock-in amplifier is used to extract the beat frequency signal. f beat The phase difference; The all-fiber liquid level measurement method includes the following steps: Step S1: Emit dual optical combs and split the beams to form a reference beam and a measurement beam; Step S2: The measurement light is emitted to the surface of the liquid to be measured, and after being reflected by the liquid surface, it returns to the polarization-maintaining fiber combiner; Step S3: The polarization-maintaining fiber combiner combines the received reference light and the measurement light, and the balanced detector receives the interference signal and outputs the beat frequency signal. f beat =NΔ f r ±Δ φ ( t ) / 2π; Where: N is the number of optical comb modes; Δ f r The difference in repetition frequency between the two optical combs; Δ φ ( t The phase difference is caused by the change in liquid level. t represents time; Step S4: Match the beat frequency signal f beat Perform a Fourier transform to extract the phase difference Δ φ ( t ); Step S5: If |Δ φ ( t )- φ 0|≥ ε, Based on the phase difference Δ φ ( t Adjust the dynamic compensation of the reference light's optical path length; output the compensated reference light to the polarization-maintaining fiber combiner and proceed to step S3; if |Δ φ ( t )- φ 0|< ε Then proceed to step S6; in: φ 0 represents the calibrated value of the phase difference; ε To set a threshold; Step S6: Calculate the change in liquid level height: ； Where: λ is the center wavelength of the optical comb; n is the refractive index of the liquid.

2. The all-fiber liquid level measurement method based on dual-comb phase decoupling and adaptive compensation according to claim 1, characterized in that, The adaptive compensation module includes a PID controller and a PZT driver connected to each other. The reference arm includes an optical fiber circulator 1, a PZT fiber stretcher, and an optical fiber reflector connected sequentially from front to back. The PZT driver is connected to the PZT fiber stretcher. The optical fiber circulator 1 is connected to the dual-comb light source module and the polarization-maintaining fiber combiner, respectively, to enable the reference light to enter the optical fiber reflector through the optical fiber circulator 1 and the PZT fiber stretcher. The optical path of the reference light is fixed. After being reflected by the end face of the optical fiber reflector, it enters the polarization-maintaining fiber combiner through the optical fiber circulator 1.

3. The all-fiber liquid level measurement method based on dual-comb phase decoupling and adaptive compensation according to claim 2, characterized in that, The measuring arm includes an interconnected fiber optic circulator 2 and a fiber optic collimator. The fiber optic circulator 2 is connected to a polarization-maintaining fiber optic splitter and a polarization-maintaining fiber optic combiner, respectively, to enable the measuring light to enter the fiber optic collimator through the fiber optic circulator 2. After collimation, the light is emitted to the surface of the liquid to be measured. After reflection from the liquid surface, the light returns sequentially to the fiber optic collimator, the fiber optic circulator 2, and the polarization-maintaining fiber optic combiner.

4. The all-fiber liquid level measurement method based on dual-comb phase decoupling and adaptive compensation according to claim 3, characterized in that, Both fiber optic circulator 1 and fiber optic circulator 2 are polarization-maintaining fiber optic circulators.

5. The all-fiber liquid level measurement method based on dual-comb phase decoupling and adaptive compensation according to claim 1, characterized in that, The dual-comb light source module is connected to the polarization-maintaining fiber beam splitter via an optical fiber isolator.

6. The all-fiber liquid level measurement method based on dual-comb phase decoupling and adaptive compensation according to claim 1, characterized in that, The splitting ratio of both the polarization-maintaining fiber beam splitter and the polarization-maintaining fiber beam combiner is 50:

50.

7. The all-fiber liquid level measurement method based on dual-comb phase decoupling and adaptive compensation according to claim 1, characterized in that, In step S5, the output signal V ( t The PZT fiber stretcher is driven by an axial expansion / contraction amount Δ. Lz = βV ( t ), in, β The scaling factor is Δ; the optical path length variation of the reference light is Δ. L ref =2Δ Lz, To offset the Δ introduced by environmental disturbances L nosie .

8. The all-fiber liquid level measurement method based on dual-comb phase decoupling and adaptive compensation according to claim 7, characterized in that, Record the Δ for each compensation. L ref and output signal V (t), and the optimal PID parameters for environmental parameters with different temperatures and refractive indices, are obtained. The PID parameters are optimized based on machine learning methods, and a lookup table is established to achieve self-optimization of PID control parameters.

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