Sweep frequency interference ranging Doppler effect correction system, method, program, device and storage medium

Abstract

The invention belongs to the technical field of laser interference measurement optical fiber sensing, and particularly relates to a frequency sweep interference ranging Doppler effect correction system, method, program and device and a storage medium. The problem of range finding precision degradation caused by Doppler effect interference is solved through a dual-optical-path cooperative detection and real-time dynamic compensation technology, Doppler displacement characteristics and original distance signals of a target object are synchronously captured through a light splitting design by adopting a dual-optical-path architecture, a displacement phase component is extracted in real time by adopting a carrier phase demodulation algorithm, and the distance finding precision of the target object is improved. And resolving and measuring the phase of the interferometer by combining a phase comparison method, and correcting the ranging error in real time based on the displacement phase. According to the designed double-optical-path dynamic displacement feedback mechanism, millisecond-level real-time compensation of Doppler interference is achieved through a closed-loop correction model of displacement phase distance measurement errors, and the compensation precision reaches the submicron level. Vibration and distance information are separated through heterogeneous optical path design, and an absolute distance value subjected to displacement compensation and real-time Doppler displacement of a target object are synchronously output.

Description

Technical Field

[0001] This invention belongs to the field of laser interferometry fiber optic sensing technology, specifically relating to a sweep frequency interferometric ranging Doppler effect correction system, method, program, equipment, and storage medium. Background Technology

[0002] Frequency-sweep interferometric ranging technology has been widely used in aerospace, industrial inspection, and precision motion control due to its advantages such as no ranging ambiguity, high precision, and strong anti-interference capability. In a typical frequency-modulated continuous wave (FMCW) lidar system, the target distance is calculated by obtaining the phase change of the interferometric signal through linear frequency sweeping of the light source. However, under actual operating conditions, minute vibrations of the platform or the object under test can be superimposed on the frequency-sweep ranging signal, generating additional phase perturbations and Doppler frequency shifts. This results in systematic errors at the micrometer or even sub-micrometer level in the ranging results, severely reducing ranging accuracy and stability.

[0003] In existing technologies, single-optical-path swept-frequency interferometry systems struggle to effectively distinguish between the target Doppler displacement and the true distance signal, leading to phase noise introduced by the Doppler effect directly coupling to the ranging results. Regarding error suppression, existing methods primarily suffer from the following technical bottlenecks:

[0004] Vibration-distance coupling interference: In a single-optical-path architecture, the Doppler frequency shift and sweep frequency nonlinear effect caused by target vibration produce cross-modulation, resulting in phase aliasing of the interference signal (CN119148154A). Traditional time-domain filtering methods are difficult to separate high-frequency vibration components, while motion compensation based on POS systems is limited by its positioning accuracy at the hundred-micrometer level (CN116699572A), and cannot meet the sub-micrometer ranging requirements.

[0005] Insufficient real-time monitoring of Doppler displacement: Doppler displacement compensation schemes based on iterative algorithms (such as Kalman filtering) require multi-cycle data modeling (CN116699572A), which has a delay of at least 10ms in dynamic vibration scenarios, making it difficult to track high-frequency vibration changes.

[0006] Noise in industrial environments is difficult to predict: a symmetrical sweep frequency signal is generated based on triangular wave frequency modulation (TFMCW), and vibration velocity is calculated and Doppler effect is compensated by frequency difference (CN116699572A). However, it relies heavily on the assumption that the target vibration velocity is constant, has poor adaptability to time-varying vibrations (such as shock and random vibration), and the compensation residual is more than 10%.

[0007] There is an urgent need in this field for a novel ranging system capable of achieving the following breakthroughs under strong vibration environments: physically isolating vibration and distance signals through innovative optical path design to eliminate cross-modulation interference; establishing a dynamic mapping model for Doppler phase ranging errors to achieve millisecond-level real-time compensation; and simultaneously outputting target vibration displacement characteristics while maintaining sub-micron level accuracy. Summary of the Invention

[0008] The purpose of this invention is to overcome the problem of limited measurement accuracy of existing single-path sweep frequency interferometric ranging systems under dynamic vibration environments, and to provide a sweep frequency interferometric ranging Doppler effect correction system, method, program, device and storage medium.

[0009] A sweep frequency interferometric ranging Doppler effect correction system includes a vibration measurement sweep frequency light source, a distance measurement sweep frequency light source, a first wavelength division multiplexer (WDM), an auxiliary interferometer, a fiber optic probe with a reference surface, a circulator, and a second WDM. The optical signal output from the vibration measurement sweep frequency light source is input to the first WDM after passing through a first optical isolator. The optical signal output from the distance measurement sweep frequency light source is input to the first WDM and the auxiliary interferometer after passing through a second optical isolator and a coupler, respectively. The optical signal output from the first WDM is transmitted through the circulator, with one path leading to the target object via the fiber optic probe with a reference surface, and the other path leading to the second WDM. The second WDM receives the optical signal reflected back to the circulator from the target object.

[0010] Furthermore, it also includes a synchronous clock signal source module, used to synchronize the vibration measurement sweep frequency light source and the distance measurement sweep frequency light source to generate optical frequency scanning laser; the synchronous clock signal source module includes an external clock source and an arbitrary waveform generator board (AWG).

[0011] Furthermore, it also includes a signal acquisition and processing module. The external clock source provides an external clock for the arbitrary waveform generator (AWG) board and the signal acquisition and processing module, so that the modulation signals of the vibration measurement sweep frequency light source and the distance measurement sweep frequency light source are synchronized with the signals received by the signal acquisition and processing module.

[0012] Furthermore, the modulation signal of the vibration measurement sweep frequency light source is a sine wave; the modulation signal of the distance measurement sweep frequency light source is a triangular wave.

[0013] A method for correcting the Doppler effect in frequency sweep interferometric ranging includes the following steps:

[0014] Step 1: Adjust the modulation signal of the vibration measurement sweep frequency light source and set the carrier phase modulation depth;

[0015] Step 2: The vibration measurement sweep frequency light source and the distance measurement sweep frequency light source synchronously generate optical frequency scanning lasers to acquire the reference signal output by the auxiliary interferometer. Determine the reference signal phase ; Obtain the distance measurement signal between the target object output by the second wavelength division multiplexer and the fiber optic probe containing the reference plane. Determine the distance measurement signal phase ;

[0016]

[0017] Step 3: Employ a dynamically optimized carrier phase demodulation algorithm to extract the Doppler displacement phase component in real time, and perform phase compensation on the fundamental frequency signal and second harmonic signal in the modulation signal of the distance measurement sweep frequency light source;

[0018] Acquire the vibration measurement signal output from the second wavelength division multiplexer. Vibration measurement signal The signals are mixed with the phase-compensated fundamental frequency signal and the second harmonic signal respectively, and then filtered out for high-frequency components by a low-pass filter to obtain two non-strictly orthogonal signals. and Calculate the vibration phase ;

[0019] Step 4: Based on the vibration phase Correct distance measurement signal phase The corrected distance measurement signal phase is obtained. ;

[0020] Step 5: Based on the phase of the corrected distance measurement signal The distance between the target object and the fiber optic probe containing the reference surface is calculated based on data from the auxiliary interferometer. .

[0021] Furthermore, in step 1, the carrier phase modulation depth C is set to be near the theoretical optimal value, i.e. This ensures that the amplitudes of the first and second harmonic components of the interference output signal are consistent, suppressing harmonic distortion introduced by the nonlinearity of the Bessel function.

[0022] Furthermore, step 5 specifically includes:

[0023]

[0024] in, To assist in the arm length difference of the interferometer; The refractive index of the fiber used in the auxiliary interferometer; The refractive index of air.

[0025] A computer device includes a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the above-described sweep frequency interferometric ranging Doppler effect correction method.

[0026] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described sweep frequency interferometric ranging Doppler effect correction method.

[0027] A computer program product includes computer instructions that, when executed by a processor, implement the steps of the above-described sweep frequency interferometric ranging Doppler effect correction method.

[0028] The beneficial effects of this invention are as follows:

[0029] This invention designs a dual-optical-path dynamic displacement feedback mechanism. Through a closed-loop correction model of displacement phase ranging error, it achieves millisecond-level real-time compensation for Doppler interference with sub-micron level accuracy. This invention separates vibration and distance information through heterogeneous optical path design, synchronously outputting the displacement-compensated absolute distance value and the real-time Doppler displacement of the target object. Experiments show that even under the 200Hz Doppler effect, it can still maintain sub-micron level measurement accuracy, and the dynamic measurement stability is improved by more than 3 times compared to traditional methods, making it suitable for high-precision industrial inspection and motion control scenarios. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a sweep frequency interferometric ranging Doppler effect correction system according to the present invention.

[0031] Figure 2 This is a time-domain signal diagram of Doppler interference in the environment measured during system verification and testing of this invention, with a vibration amplitude of approximately 25 nm.

[0032] Figure 3 This is the power spectral density diagram of the Doppler interference signal present in the environment, measured during system verification and testing of this invention. The vibration amplitude is approximately 25 nm.

[0033] Figure 4 This is a vibration spectrum diagram of the environment measured during system verification and testing of this invention. The vibration frequency is approximately 120Hz.

[0034] Figure 5 The distance value before compensation was demodulated during system verification and testing of this invention, with an accuracy of 1.23 μm.

[0035] Figure 6 This is the compensated distance value demodulated during system verification and testing of this invention, with an accuracy of 446nm. Detailed Implementation

[0036] The present invention will now be further described with reference to the accompanying drawings.

[0037] like Figure 1 As shown, the present invention provides a swept-frequency interferometric ranging Doppler effect correction system, comprising:

[0038] Synchronous clock signal source module 1: External clock source 11, arbitrary waveform generator board AWG12;

[0039] Dual-channel sweep frequency interferometric optical path module 2: vibration measurement sweep frequency light source 21, distance measurement sweep frequency light source 22, first optical isolator 23, second optical isolator 24, first wavelength division multiplexer 25, coupler 26, auxiliary interferometer 27, fiber optic probe with reference plane 28, target object 29, circulator 210, second wavelength division multiplexer 211;

[0040] Signal acquisition and processing module 3: Detector 31, Acquisition card DAQ 32, Computer 33;

[0041] The optical signal output from the vibration measurement sweep frequency light source 21 is input to the first wavelength division multiplexer 25 after passing through the first optical isolator 23; the optical signal output from the distance measurement sweep frequency light source 22 is input to the first wavelength division multiplexer 25 and the auxiliary interferometer 27 respectively after passing through the second optical isolator 24 and the coupler 26; the optical signal output from the first wavelength division multiplexer 25 is transmitted to the target object 29 through the circulator 210, and the other path is transmitted to the second wavelength division multiplexer 211, where the second wavelength division multiplexer 211 receives the optical signal reflected back to the circulator 210 from the target object 29.

[0042] The synchronous clock signal source module 1 is used to synchronize the optical frequency scanning laser generated by the vibration measurement sweep frequency light source 21 and the distance measurement sweep frequency light source 22. The external clock source 11 provides an external clock for the arbitrary waveform generator board AWG12 and the signal acquisition and processing module 3, ensuring that the modulation signals input to the vibration measurement sweep frequency light source 21 and the distance measurement sweep frequency light source 22, as well as the signals received by the signal acquisition and processing module 3, are synchronized. The modulation signal of the vibration measurement sweep frequency light source 21 is a sine wave; the modulation signal of the distance measurement sweep frequency light source 22 is a triangular wave.

[0043] A method for correcting the Doppler effect in frequency sweep interferometric ranging includes the following steps:

[0044] Step 1: Adjust the modulation signal of the vibration measurement sweep frequency light source 21, and preset and lock the carrier phase modulation depth (balance coefficient C) near its theoretical optimal value under the corresponding conditions. , (in radians) to make the amplitudes of the first and second harmonic components of the interference output signal consistent, thereby fundamentally suppressing the harmonic distortion introduced by the nonlinearity of the Bessel function.

[0045] Step 2: The vibration measurement sweep frequency light source 21 and the distance measurement sweep frequency light source 22 synchronously generate optical frequency scanning lasers to acquire the reference signal output by the auxiliary interferometer 27. The distance measurement signal between the target object 29 and the fiber optic probe 28 containing the reference plane, output by the second wavelength division multiplexer 211, is obtained. The Hilbert transform is used to determine the reference signal. phase With distance measurement signal phase ;

[0046] Step 3: Employ a dynamically optimized carrier phase demodulation algorithm to extract the Doppler displacement phase component in real time, and perform phase compensation on the fundamental frequency signal and second harmonic signal in the modulation signal of the distance measurement sweep frequency light source 22;

[0047] Acquire the vibration measurement signal output by the second wavelength division multiplexer 211 Vibration measurement signal The signals are mixed with the phase-compensated fundamental frequency signal and the second harmonic signal respectively, and then filtered out for high-frequency components by a low-pass filter to obtain two non-strictly orthogonal signals. and Calculate the vibration phase ;

[0048]

[0049] Step 4: Based on the vibration phase Correct distance measurement signal phase The corrected distance measurement signal phase is obtained. ;

[0050]

[0051] When the light source modulation is in an up-sweep mode, i.e., the frequency increases, it is a plus sign; when the light source frequency is in a down-sweep mode, i.e., the frequency decreases, it is a minus sign.

[0052] Step 5: Based on the phase of the corrected distance measurement signal The distance between the target object 29 and the fiber optic probe 28 containing the reference surface is calculated based on the data from the auxiliary interferometer 27. ;

[0053]

[0054] in, To assist in the arm length difference of interferometer 27; The refractive index of the optical fiber in the auxiliary interferometer 27; The refractive index of air.

[0055] Example 1:

[0056] In this embodiment, the external clock source 11 uses a 10MHz crystal oscillator. The 10MHz crystal oscillator 11 provides an external clock for the arbitrary waveform generator board AWG and the acquisition card DAQ, so that the modulation signal of the light source is synchronized with the signal received by the acquisition card.

[0057] Both the first wavelength division multiplexer 25 and the second wavelength division multiplexer 211 employ 2×1 wavelength division multiplexing (WDM) technology. Based on wavelength selectivity, they achieve heterogeneous optical signal separation, performing directional coupling and wavelength routing for the optical signals in the 21 band of the vibration measurement swept frequency source and the 22 band of the distance measurement swept frequency source, respectively. This ensures that the two swept frequency beams transmit independently in the interference optical path without aliasing interference.

[0058] The fiber optic probe 28 with a reference surface internally includes a reference reflective surface with a reflectivity of 3% to 6%, and the remaining optical surfaces are coated with anti-reflection films to reduce stray reflections. Furthermore, its common-path structure effectively reduces optical path difference disturbances introduced by non-sensor units, improving the instrument's anti-interference capability.

[0059] Distance measurement signal It can be represented as:

[0060]

[0061] in , , , The light intensity of the measuring arm and the reference arm. denoted as the photoelectric conversion coefficient. For modulation frequency, The phase difference between the two beams is the phase difference to be measured.

[0062] By employing dual-optical-path collaborative detection technology, the vibration displacement signal and the original distance signal are separated, and the ranging error is dynamically corrected based on the vibration phase, achieving real-time compensation for vibration interference. Through heterogeneous optical path design, wavelength routing is performed on the Doppler displacement signal and the distance measurement signal separately to ensure that the two signals are transmitted independently without cross-interference, and strict timing alignment between signal generation and acquisition is achieved through a synchronous clock module.

[0063] A dynamically optimized carrier phase demodulation algorithm is employed to extract the Doppler shift phase component in real time. This is applied to the carrier's fundamental frequency signal. and second harmonic signal Phase compensation is performed to obtain .

[0064] Vibration measurement signal The signals are mixed with the fundamental frequency signal and the second harmonic signal of the obtained carrier wave, respectively, and then the high-frequency components are filtered out by a low-pass filter to obtain two non-strictly orthogonal signals. and :

[0065]

[0066]

[0067] Among them, the amplitude and angular frequency of the carrier fundamental frequency signal are respectively and The amplitude and angular frequency of the carrier frequency-doubled signal are respectively and Dividing these two signals yields:

[0068]

[0069] To ensure the amplitude of the local carrier Select As the optimal C value for the PGC-Arctan demodulation algorithm, it guarantees... This reduces nonlinear distortion. After obtaining the vibration phase... By combining a closed-loop feedback mechanism, the ranging phase is corrected in real time to suppress Doppler frequency shift and phase noise caused by the environment.

[0070] By adaptively adjusting carrier signal parameters, the amplitude relationship between the fundamental frequency and harmonic frequencies is balanced, reducing nonlinear distortion during demodulation and improving phase calculation accuracy. Non-uniformly sampled vibration signals are standardized and reconstructed, including phase normalization mapping, unique phase point extraction, and piecewise interpolation, generating uniformly spaced Doppler displacement sequences to ensure real-time correction and stability. Phase unfolding and signal alignment techniques eliminate timing discrepancies between the vibration signal and the ranging signal, and combined with reference interferometer parameters, the corrected phase values ​​are converted into absolute distance output.

[0071] This invention solves the problem of ranging accuracy degradation caused by Doppler effect interference by using dual-optical-path collaborative detection and real-time dynamic compensation technology. It adopts a dual-optical-path architecture to simultaneously capture the Doppler displacement characteristics and original distance signal of the target object through beam splitting design, uses a carrier phase demodulation algorithm to extract the displacement phase component in real time, combines the phase comparison method to calculate the phase of the measuring interferometer, and corrects the ranging error in real time based on the displacement phase.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the 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. A frequency-sweep interferometric range-finding Doppler effect correction system characterized by: It includes vibration measurement sweep frequency light source (21), distance measurement sweep frequency light source (22), first wave division multiplexer (25), auxiliary interferometer (27), reference surface fiber probe (28), circulator (210) and second wave division multiplexer (211); the light signal output by the vibration measurement sweep frequency light source (21) is input to the first wave division multiplexer (25) after passing through the first optical isolator (23); the light signal output by the distance measurement sweep frequency light source (22) is input to the first wave division multiplexer (25) and the auxiliary interferometer (27) respectively after passing through the second optical isolator (24) and the coupler (26); the light signal output by the first wave division multiplexer (25) is transmitted to the target object (29) through the reference surface fiber probe (28) after passing through the circulator (210), and the other is transmitted to the second wave division multiplexer (211), and the second wave division multiplexer (211) receives the light signal reflected by the target object (29) to the circulator (210).

2. The swept-frequency interferometric range-finding Doppler effect correction system of claim 1, wherein: It also includes a synchronous clock signal source module (1) for synchronizing the vibration measurement sweep frequency light source (21) and the distance measurement sweep frequency light source (22) to generate light frequency scanning laser; the synchronous clock signal source module (1) includes an external clock source (11) and an arbitrary waveform generation board card AWG (12).

3. The swept-frequency interferometric range-finding Doppler effect correction system of claim 2, wherein: It also includes a signal acquisition and processing module (3), and the external clock source (11) provides an external clock for the arbitrary waveform generation board card AWG (12) and the signal acquisition and processing module (3), so that the modulation signal of the vibration measurement sweep frequency light source (21) and the distance measurement sweep frequency light source (22) and the signal received by the signal acquisition and processing module (3) are synchronized.

4. The swept-frequency interferometric range-finding Doppler effect correction system of claim 1, wherein: The modulation signal of the vibration measurement sweep frequency light source (21) is a sine wave; the modulation signal of the distance measurement sweep frequency light source (22) is a triangular wave.

5. A method based on the sweep frequency interferometric distance measurement Doppler effect correction system of claim 1, characterized in that: Step 1: adjust the modulation signal of the vibration measurement sweep frequency light source (21) and set the carrier phase modulation depth; Step 2: the vibration measurement swept source (21) and the distance measurement swept source (22) are synchronized to generate a light frequency scanning laser, and a reference signal output by an auxiliary interferometer (27) is acquired , the phase of the reference signal is determined; a distance measurement signal between the target object (29) and the reference surface fiber probe (28) output by the second wavelength division multiplexer (211) is acquired , the phase of the distance measurement signal is determined; Step 3: use a dynamic optimization carrier phase demodulation algorithm to extract the Doppler displacement phase component in real time, and perform phase compensation on the fundamental frequency signal and the second harmonic signal in the modulation signal of the distance measurement sweep frequency light source (22); acquire the vibration measurement signal output by the second wavelength division multiplexer (211) , mix the vibration measurement signal with the phase-compensated fundamental signal and the phase-compensated second-harmonic signal respectively, and filter high-frequency components through low-pass filters to obtain two non-strictly orthogonal signals and , calculate the vibration phase ; Step 4: determining the phase of the vibration correcting the phase of the distance measurement signal to obtain a corrected phase of the distance measurement signal ;​ Step 5: Phase of the modified distance measurement signal The distance between the target object (29) and the reference-facet fiber probe (28) is calculated based on the data of the auxiliary interferometer (27) .

6. The method of claim 5, wherein: In step 1, the carrier phase modulation depth C is set to be near the theoretical optimal value, i.e. The first and second harmonic components of the interference output signal are made consistent in amplitude, and harmonic distortion introduced by the nonlinearity of the Bessel function is suppressed.

7. The method of claim 6, wherein: The step 5 is specifically: wherein, is the arm length difference of the auxiliary interferometer (27); is the fiber refractive index of the auxiliary interferometer (27); is the air refractive index.

8. A computer device comprising a memory, a processor, and a computer program stored on the memory, wherein: The processor executes the computer program to realize the steps of the method of any one of claims 5 to 7.

9. A computer readable storage medium having stored thereon a computer program, characterized in that: The computer program is executed by the processor to realize the steps of the method of any one of claims 5 to 7.

10. A computer program product comprising computer instructions, characterized in that: The computer program is executed by the processor to realize the steps of the method of any one of claims 5 to 7.

Images