All-fiber mirror image frequency sweeping interference distance measuring device and method based on wavelength division multiplexing

Abstract

The invention discloses a wavelength division multiplexing-based all-fiber mirror image frequency sweeping interference distance measuring device and method, and relates to the technical field of absolute distance measurement. The objective of the invention is to solve the technical problems in the prior art that frequency spectrum aliasing, frequency sweep nonlinearity, Doppler effect and dispersion mismatch occur in frequency sweep interference measurement, and the measurement precision, the measurement efficiency and the reliability of an all-fiber mirror image frequency sweep interference ranging system cannot be ensured. According to the technical scheme provided by the invention, the wavelength division multiplexing-based all-fiber mirror image frequency sweeping interference distance measuring device comprises a laser unit used for outputting frequency sweeping light; the measurement interferometer light path is used for generating a measurement signal according to the sweep frequency light; the auxiliary interferometer light path is used for generating an auxiliary signal according to the sweep frequency light; the gas chamber calibration light path is used for carrying out auxiliary interferometer light path calibration according to the sweep frequency light; and the data acquisition and processing module is used for obtaining a distance measurement result according to the measurement signal, the auxiliary signal and the calibration signal. The method is applied to the work of all-fiber mirror image frequency sweeping interference distance measurement.

Description

Technical Field

[0001] The invention relates to the technical field of absolute distance measurement, and in particular to all-fiber mirror-image frequency-sweeping interferometry ranging based on wavelength division multiplexing. Background Art

[0002] Sweep frequency interferometry is an absolute distance measurement method. It has the advantages of no ranging ambiguity, strong anti-interference ability, high ranging accuracy and can be used for non-cooperative target measurement. It has gradually become an effective means of measuring the three-dimensional distance information of space targets. The research content of this ranging method mainly revolves around four key points, namely, sweep frequency nonlinear correction, large sweep frequency range, dispersion mismatch compensation and Doppler effect suppression.

[0003] Existing frequency sweep nonlinearity correction methods mainly include active correction method based on optoelectronic phase-locked loop and optical frequency resampling method. The active correction method based on optoelectronic phase-locked loop has the problem that the optoelectronic phase-locked loop has a complex structure, is difficult to implement, and currently cannot achieve full frequency sweep range correction. The optical frequency resampling method can use a simple all-fiber optical path to achieve real-time correction of frequency sweep nonlinearity in the full frequency sweep range, and can be used for non-cooperative target measurement.

[0004] In order to improve the measurement resolution, increasing the sweep range of the tunable laser is a direct and effective means. However, when the sweep range or measurement distance is too large, the dispersion mismatch will cause the target spectrum to be broadened, resulting in a decrease in measurement resolution. There are currently two solutions to dispersion mismatch. The first is to introduce a dispersion compensation medium, but this method usually cannot accurately compensate for the influence of dispersion mismatch. The other is to iteratively compensate for the second-order terms of dispersion mismatch in the measurement signal through an algorithm, which requires iterative calculations and is not conducive to fast measurement.

[0005] The Doppler effect introduced by the target motion will lead to the deterioration of the accuracy of the swept frequency interferometry measurement. In order to eliminate the influence of the Doppler effect, the first method is to eliminate the Doppler effect by measuring the signal frequency difference generated by the triangle wave modulated light source. This method requires the target movement speed to remain unchanged within a complete sweep cycle, and the measurement effect is not good for fast-changing targets. The second method is to use the signal generated by the mirror swept frequency light source to eliminate the Doppler effect. This method requires setting the two light sources to different sweep rates or using orthogonal polarization splitting to achieve the separation of the two signals. Among them, setting the light source to different sweep rates will introduce dispersion mismatch in the measurement signal, and in orthogonal polarization splitting, the use of a fiber polarization beam splitter (fiber PBS, extinction ratio 22dB) will cause crosstalk between the two signals. Although the use of a prism PBS can reduce the impact of crosstalk, it will increase the system volume and increase the difficulty of adjustment. In addition, the nonlinear correction process of the above-mentioned mirror sweep scheme has the problem of low efficiency, making it difficult to achieve fast measurement. Summary of the invention

[0006] In order to solve the technical problems in the prior art that spectrum aliasing, frequency sweeping nonlinearity, Doppler effect, dispersion mismatch and low measurement efficiency may occur in the frequency sweeping interferometry work, and the measurement accuracy and reliability of the all-fiber mirror frequency sweeping interferometry ranging system cannot be guaranteed, the technical solution provided by the present invention is as follows:

[0007] An all-fiber image frequency-sweeping interferometry ranging device based on wavelength division multiplexing, the device comprising:

[0008] A laser unit, used for outputting frequency-sweeping light;

[0009] A measuring interferometer optical path, used to generate a measurement signal according to the frequency-sweeping light;

[0010] An auxiliary interferometer optical path, used to generate an auxiliary signal according to the frequency-sweeping light;

[0011] An air chamber calibration optical path is used to calibrate the optical path of the auxiliary interferometer according to the swept frequency light;

[0012] The data acquisition and processing module is used to obtain the distance measurement result according to the measurement signal, auxiliary signal and calibration signal.

[0013] Furthermore, a preferred embodiment is provided, wherein the optical path of the measuring interferometer includes two optical paths of unequal lengths, and the measuring signal is obtained by detecting interference information between the measuring light reflected by the target and the reference light transmitted through the optical fiber.

[0014] Furthermore, a preferred embodiment is provided, wherein the auxiliary interferometer optical path includes two optical paths of unequal lengths, and an auxiliary signal is obtained by detecting interference information between the measurement light transmitted by the long optical fiber and the reference light transmitted by the short optical fiber.

[0015] Furthermore, a preferred embodiment is provided, wherein the air chamber calibration optical path and the auxiliary interferometer share a portion of the optical path through a circulator, and the auxiliary interferometer optical path is calibrated.

[0016] Furthermore, a preferred embodiment is provided, wherein the measuring interferometer optical path comprises two balanced detectors for outputting the measuring signal, which are connected to the digital acquisition and processing module via a multiplier.

[0017] Furthermore, a preferred embodiment is provided, wherein the auxiliary interferometer optical path comprises two balanced detectors for outputting the auxiliary signal, which are connected to the digital acquisition and processing module via a multiplier.

[0018] Based on the same inventive concept, the present invention also provides an all-fiber image frequency scanning interferometry ranging method based on wavelength division multiplexing, which is implemented based on the device and includes:

[0019] The steps of collecting measurement signals, auxiliary signals and calibration signals; generating a reference signal, mixing and filtering the reference signal and the auxiliary signal to obtain a processed auxiliary signal; mixing and filtering and phase demodulating the processed auxiliary signal to obtain a phase correction interferometer signal; mixing the measurement signal, and obtaining a ranging result using the phase correction interferometer signal and the calibration signal.

[0020] Based on the same inventive concept, the present invention also provides an all-fiber image frequency scanning interferometry ranging method based on wavelength division multiplexing, which is implemented based on the device and includes:

[0021] The steps of collecting measurement signals, auxiliary signals and calibration signals; generating a reference signal, mixing and filtering the reference signal and the auxiliary signal and performing phase demodulation to obtain a correction interferometer signal phase; and obtaining a distance measurement result according to the measurement signal using the correction interferometer signal phase and the calibration signal.

[0022] Based on the same inventive concept, the present invention also provides a computer storage medium for storing a computer program, and when the computer program is read by a computer, the method described is implemented.

[0023] Based on the same inventive concept, the present invention also provides a computer, including a processor and a storage medium, and when the computer program stored in the storage medium is read by the processor, the described method is implemented.

[0024] Compared with the prior art, the technical solution provided by the present invention is beneficial in that:

[0025] The all-fiber mirror-image frequency-sweeping interferometric ranging device and method based on wavelength division multiplexing provided by the present invention adopts the mirror-image synchronous frequency-sweeping technology and uses two beams of frequency-sweeping light with a mirror relationship to perform measurement. The effective bandwidth of the light source is fully utilized to solve the problem of spectrum aliasing in multi-target measurement scenarios. Compared with the prior art, this method can more effectively separate and analyze the measurement signals of multiple targets to achieve high-precision distance measurement of multiple targets.

[0026] The all-fiber mirror-sweep interferometer ranging device and method based on wavelength division multiplexing provided by the present invention uses a wavelength division multiplexer to combine and separate two beams of swept light. It effectively improves the isolation of the dual-band and avoids the crosstalk of the dual-band light. Compared with the orthogonal polarization splitting method, this method has a simpler structure, less crosstalk, and improves the reliability and accuracy of the measurement.

[0027] The all-fiber mirror-sweep interferometric ranging device and method based on wavelength division multiplexing provided by the present invention adopts an all-fiber mirror-sweep structure. The system volume and complexity are reduced, and the adverse effects of spectrum broadening and dispersion mismatch caused by the target Doppler effect and large sweep range are immune. Compared with the traditional free space optical path, the all-fiber structure is more compact and more stable.

[0028] The all-fiber image frequency-sweeping interferometry ranging device and method based on wavelength division multiplexing provided by the present invention introduces an air chamber calibration optical path and calibrates through the absolute optical frequency and phase value of the air chamber absorption peak, thereby ensuring the stability and reliability of the measurement system benchmark and improving the measurement accuracy and long-term stability of the system.

[0029] The all-fiber image frequency-sweeping interferometer ranging device and method based on wavelength division multiplexing provided by the present invention use two different acquisition structures and use the dual reference frequency signal generated by the computer to quickly solve the auxiliary interferometer phase. The multi-target measurement and the number of data channels can be optimized according to the needs to improve the flexibility and adaptability of the system. In the signal processing part, while improving the measurement efficiency, it ensures high-precision measurement of the target.

[0030] The all-fiber mirror-image frequency-sweeping interferometry ranging device and method based on wavelength division multiplexing provided by the present invention are superior to the existing technologies in terms of reliability, system complexity and processing efficiency, and have significant advantages in solving the influence of spectrum aliasing, dispersion mismatch and Doppler effect.

[0031] The all-fiber image frequency-sweeping interferometry ranging device and method based on wavelength division multiplexing provided by the present invention can be applied to the work of all-fiber image frequency-sweeping interferometry ranging. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of structure 1 of an all-fiber image-sweeping interferometry ranging device based on wavelength division multiplexing;

[0033] Figure 2 It is a schematic diagram of structure 2 of an all-fiber mirror-image frequency-sweeping interferometry ranging device based on wavelength division multiplexing;

[0034] Figure 3 Based on Figure 1 a flowchart of the method to be implemented;

[0035] Figure 4 Based on Figure 2 a flowchart of the method to be implemented;

[0036] Figure 5 The experimental results of absolute distance measurement, where (a) is a schematic diagram of the distance spectrum of one measurement, and (b) is the measurement results of ten measurements. The repeatability of the ten measurement results is 3.9μm.

[0037] Among them, 1-first tuned laser source, 2-second tuned laser source, 3-first isolator, 4-second isolator, 5-first coupler, 6-first wavelength division multiplexing, 7-second coupler, 8-third coupler, 9-first circulator, 10-optical system, 11-target, 12-fourth coupler, 13-second wavelength division multiplexing, 14-third wavelength division multiplexing, 15-first balanced detector, 16-second balanced detector, 17-fifth coupler, 18-sixth coupler, 19-second circulator, 20-fourth wavelength division multiplexing, 21-fifth wavelength division multiplexing, 22-third balanced detector, 23-fourth balanced detector, 24-first detector, 25-gas chamber, 26-seventh coupler, 27-second detector, 28-data acquisition and data processing module, 29-first multiplier, 30-second multiplier. DETAILED DESCRIPTION

[0038] In order to make the advantages and benefits of the technical solution provided by the present invention more clearly reflected, the technical solution provided by the present invention is now further described in detail with reference to the accompanying drawings, specifically:

[0039] Embodiment 1: This embodiment provides an all-fiber mirror-image frequency-sweeping interferometry ranging device based on wavelength division multiplexing, the device comprising:

[0040] A laser unit, used for outputting frequency-sweeping light;

[0041] A measuring interferometer optical path, used to generate a measurement signal according to the frequency-sweeping light;

[0042] An auxiliary interferometer optical path, used to generate an auxiliary signal according to the frequency-sweeping light;

[0043] The air chamber calibrates the optical path, and is used to perform auxiliary interferometer optical path calibration according to the frequency-sweeping light;

[0044] The data acquisition and processing module is used to obtain the distance measurement result according to the measurement signal, the auxiliary signal and the calibration signal.

[0045] Specifically,

[0046] The all-fiber image frequency scanning interferometer ranging device based on wavelength division multiplexing includes:

[0047] A laser unit (I), comprising a first tunable laser source 1 and a second tunable laser source 2, for outputting a swept frequency light having a mirror image of a swept frequency range;

[0048] A measuring interferometer optical path (II) for generating a measuring signal;

[0049] Auxiliary interferometer optical path (III), used to assist signal generation and realize measurement signal correction;

[0050] Gas chamber calibration optical path (IV), used to calibrate the optical path of the auxiliary interferometer to ensure the accuracy of the measurement;

[0051] A data acquisition module, used for collecting measurement signals, auxiliary signals and calibration signals;

[0052] The digital signal processing module is used to process and analyze the collected signals.

[0053] Functions and relationships of each component

[0054] Laser unit (I):

[0055] The invention comprises a first tunable laser source 1 and a second tunable laser source 2, which are used for outputting frequency-sweeping light.

[0056] After the swept frequency light is combined by the wavelength division multiplexer, it enters the measurement interferometer optical path, the auxiliary interferometer optical path, and the gas chamber calibration optical path respectively.

[0057] Measuring interferometer optical path (II):

[0058] Receives the swept light from the laser unit and generates the measurement light and reference light for the measurement interferometer optical path.

[0059] The measurement light formed after being reflected by the target 11 through the optical system 10 interferes with the reference light transmitted by the optical fiber to generate a measurement signal.

[0060] The measurement signal is detected by a balanced detector.

[0061] Auxiliary interferometer optical path (III):

[0062] It also receives the swept light from the laser unit and generates the measurement light and reference light for the auxiliary interferometer optical path.

[0063] The measurement light transmitted through the long and short optical paths interferes with the reference light to generate auxiliary signals.

[0064] The auxiliary signal is detected by a balanced detector to assist in correcting the measurement signal.

[0065] Gas chamber calibration optical path (IV):

[0066] Receives frequency-sweep light from the laser unit to calibrate the absolute frequency of the light source.

[0067] The specific wavelength of light is absorbed by the gas cell, ensuring accurate absolute frequency measurement of the swept light.

[0068] The calibration signal is detected by the detector and used to calculate the auxiliary interferometer optical path.

[0069] Data acquisition module:

[0070] The signals from the measuring interferometer optical path, the auxiliary interferometer optical path and the gas cell calibration optical path are collected.

[0071] The signal is transmitted to the digital signal processing module for further processing.

[0072] Digital signal processing module:

[0073] Analyze and process the collected measurement signals, auxiliary signals and calibration signals.

[0074] Correct the errors caused by nonlinearity and calculate the final distance measurement results.

[0075] Each component is connected in series and in parallel through optical fibers and optical elements to form a complete measurement system, and cooperates with each other to complete high-precision interference ranging tasks.

[0076] The frequency sweeping light output by the laser unit is combined by the wavelength division multiplexer and then enters the measuring interferometer optical path and the auxiliary interferometer optical path respectively; the measuring interferometer optical path irradiates the target 11 through the optical system 10, and the measuring light reflected by the target 11 interferes with the reference light transmitted by another optical fiber to generate a measuring signal; the auxiliary interferometer optical path interferes with the reference light transmitted by the measuring light transmitted by the optical paths of different lengths to generate an auxiliary signal; the air chamber calibration optical path is calibrated by absorbing light of a specific wavelength; the data acquisition module collects the signal and transmits it to the digital signal processing module to generate the final distance measurement result

[0077] Implementation method 2. This implementation method is a further limitation of the all-fiber mirror-sweeping interferometer ranging device based on wavelength division multiplexing provided in implementation method 1. The measuring interferometer optical path includes two optical paths of unequal lengths. The measurement signal is obtained by detecting the interference information formed by the interference between the measuring light reflected by the target 11 and the reference light transmitted through the optical fiber.

[0078] Implementation method three. This implementation method is a further limitation of the all-fiber mirror-sweeping interferometer ranging device based on wavelength division multiplexing provided in implementation method one. The auxiliary interferometer optical path includes two optical paths of unequal lengths. The auxiliary signal is obtained by detecting the interference information formed by the interference between the measurement light transmitted through the long optical fiber and the reference light transmitted through the short optical fiber.

[0079] Implementation method 4. This implementation method further limits the all-fiber mirror-sweeping interferometer ranging device based on wavelength division multiplexing provided in implementation method 1. The air chamber calibration optical path and the auxiliary interferometer optical path share part of the optical path through a circulator, and the auxiliary interferometer optical path is calibrated.

[0080] Implementation method five: This implementation method further limits the all-fiber mirror-sweeping interferometer ranging device based on wavelength division multiplexing provided in implementation method one. The measuring interferometer optical path includes two balanced detectors for outputting the measuring signal, which are connected to the digital acquisition and processing module through a multiplier.

[0081] Implementation method six: This implementation method is a further limitation of the all-fiber mirror-sweeping interferometer ranging device based on wavelength division multiplexing provided in implementation method five. The auxiliary interferometer optical path includes two balanced detectors for outputting the auxiliary signal, which are connected to the digital acquisition and processing module through a multiplier.

[0082] Embodiment 7: This embodiment provides an all-fiber mirror-sweep interferometry ranging method based on wavelength division multiplexing. The method is implemented based on the device provided in embodiment 1, and includes:

[0083] The steps of collecting measurement signals, auxiliary signals and calibration signals; generating a reference signal, mixing and filtering the reference signal and the auxiliary signal to obtain a processed auxiliary signal; mixing and filtering and phase demodulating the processed auxiliary signal to obtain a phase correction interferometer signal; mixing the measurement signal, and obtaining a ranging result using the phase correction interferometer signal and the calibration signal.

[0084] Specific:

[0085] Method 1 is based on wavelength division multiplexing technology and realizes high-precision all-fiber image frequency scanning interferometry ranging through optical path and signal processing steps. Its steps include signal acquisition, mixing processing, bandpass filtering, phase demodulation and final ranging calculation.

[0086] Signal acquisition

[0087] Input: Multiple signals to be processed, including measurement signals, auxiliary signals and calibration signals.

[0088] Output: collected signal data.

[0089] Detailed process: The computer receives the signals to be processed from the measuring interferometer, auxiliary interferometer and gas cell calibration optical path. These signals are collected by sensors and recorded in the time domain.

[0090] Mixing Process

[0091] Input: collected signal data.

[0092] Output: mixed signal.

[0093] Detailed process: A reference signal is generated by a computer, and mixed with the two collected auxiliary signals to obtain a mixed signal.

[0094] Mixing processing, bandpass filtering

[0095] Input: The mixed signal.

[0096] Output: Mixed and filtered signal.

[0097] Detailed process: The mixed signal is mixed again, and then the signal used to correct nonlinearity is filtered through a bandpass filter to obtain a bandpass filtered signal. The purpose of this step is to extract useful frequency components to improve the accuracy of the signal.

[0098] Phase Demodulation

[0099] Input: Bandpass filtered signal.

[0100] Output: Corrected interferometer signal phase.

[0101] Detailed process: Phase demodulate the signal after bandpass filtering to obtain the demodulated signal phase, that is, correct the interferometer signal phase. This step is to extract the phase information of the signal, which is then used for subsequent distance calculation.

[0102] Final distance calculation

[0103] Input: interferometer signal phase correction, measurement signal, calibration signal.

[0104] Output: The measured distance value.

[0105] Detailed process: By correcting the interferometer signal phase and calibrating the signal, the mixed measurement signal is processed by a specific algorithm, and the distance of the target 11 is calculated. This step combines the results of all previous steps and outputs the final distance measurement result.

[0106] Embodiment 8: This embodiment provides an all-fiber mirror-image frequency-sweeping interferometry ranging method based on wavelength division multiplexing, which is implemented based on the device provided in embodiment 5 and includes:

[0107] The steps of collecting measurement signals, auxiliary signals and calibration signals; generating a reference signal, mixing and filtering the reference signal and the auxiliary signal and performing phase demodulation to obtain a correction interferometer signal phase; and obtaining a distance measurement result according to the measurement signal using the correction interferometer signal phase and the calibration signal.

[0108] Specific:

[0109] Method 2 is also based on wavelength division multiplexing technology, and further improves the accuracy and efficiency of ranging through improved signal processing and correction methods. Its steps include signal acquisition, mixing processing, bandpass filtering, phase demodulation and final ranging calculation.

[0110] Signal acquisition

[0111] Input: Multiple signals to be processed, including measurement signals, auxiliary signals and calibration signals.

[0112] Output: collected signal data.

[0113] Detailed process: The computer receives the signals to be processed from the measuring interferometer, auxiliary interferometer and gas chamber calibration optical path. These signals are collected by the acquisition card and recorded in the time domain.

[0114] Mixing Process

[0115] Input: collected auxiliary signal.

[0116] Output: mixed signal.

[0117] Detailed process: Use a computer to generate a reference signal, mix it with the collected auxiliary signal, and obtain a mixed signal.

[0118] Bandpass filtering

[0119] Input: Auxiliary signal after mixing.

[0120] Output: Bandpass filtered signal.

[0121] Detailed process: The mixed auxiliary signal is passed through a bandpass filter to filter out the signal used to correct nonlinearity and obtain a bandpass filtered signal. The purpose of this step is to extract useful frequency components to improve the accuracy of the signal.

[0122] Phase Demodulation

[0123] Input: Bandpass filtered signal.

[0124] Output: Corrected interferometer signal phase.

[0125] Detailed process: Phase demodulate the signal after bandpass filtering to obtain the demodulated signal phase, that is, correct the interferometer signal phase. This step is to extract the phase information of the signal, which is then used for subsequent distance calculation.

[0126] Final distance calculation

[0127] Input: interferometer signal phase correction, measurement signal, calibration signal.

[0128] Output: The measured distance value.

[0129] Detailed process: By correcting the interferometer signal phase and calibrating the signal, the measurement signal is processed by a specific algorithm, and the distance of the target 11 is obtained by calculation. This step combines the results of all the previous steps and outputs the final distance measurement result.

[0130] Embodiment 9: This embodiment provides a computer storage medium for storing a computer program. When the computer program is read by a computer, the method provided in embodiment 7 or 8 is implemented.

[0131] Embodiment 10: This embodiment provides a computer, including a processor and a storage medium. When a computer program stored in the storage medium is read by the processor, the method provided in embodiment 7 or 8 is implemented.

[0132] Embodiment eleven: This embodiment provides a computer program product, which stores a computer program. When the computer program is read by a processor, the method provided in embodiment seven or eight is implemented.

[0133] Implementation Method 12: Combination Figure 1-5 This embodiment is described in detail by using specific examples to further describe the technical solution provided above. Specifically:

[0134] This embodiment provides an all-fiber mirror-image frequency-sweeping interferometry ranging device and method based on wavelength division multiplexing;

[0135] The all-fiber image scanning interferometer ranging device based on wavelength division multiplexing includes:

[0136] The laser unit 1 includes a first tuned laser source 1, a second tuned laser source 2, a first isolator 3, a second isolator 4, a first coupler 5, a first wavelength division multiplexer 6, and a second coupler 7. The first and second tuned laser sources respectively output sweeping light with a sweeping range mirror image, and the two sweeping lights can be separated by a wavelength division multiplexer. The detection light output by the first tuned laser source 1 passes through the first isolator 3, and is split by the first coupler 5 to enter the gas chamber calibration optical path 4 and the first wavelength division multiplexer 6 respectively. The detection light output by the second tuned laser source 2 also enters the first wavelength division multiplexer 6 through the second isolator 4. The two sweeping lights are combined through the first wavelength division multiplexer 6 and enter the second coupler 7. After being split by the second coupler 7, they enter the measurement interferometer 2 and the auxiliary interferometer 3 respectively.

[0137] The second measuring interferometer comprises a third coupler 8, a first circulator 9, an optical system 10, a target 11, a fourth coupler 12, a second wavelength division multiplexer 13, a third wavelength division multiplexer 14, a first balanced detector 15, and a second balanced detector 16. The swept light from the second coupler 7 is split by the third coupler 8 to obtain the measuring light and the reference light of the measuring interferometer. The measuring light passes through the first circulator 9 and the optical system 10, and after being reflected on the surface of the target 11 to be measured, it returns to the optical system 10 along the original path, is output from the other end of the first circulator 9, and is combined with the reference light obtained by another splitting of the third coupler 8 at the fourth coupler 12. After being output by the fourth coupler 12, they are respectively passed into the second wavelength division multiplexer 13 and the third wavelength division multiplexer 14, and the swept light with two detection lights as light sources can be obtained respectively, which are detected by the first balanced detector 15 and the second balanced detector 16 respectively, and two measuring interferometer signals generated by the detection light are obtained.

[0138] The auxiliary interferometer 3 includes a fifth coupler 17, a sixth coupler 18, a second circulator 19, a fourth wavelength division multiplexer 20, a fifth wavelength division multiplexer 21, a third balanced detector 22, and a fourth balanced detector 23. The swept light outputted from the second coupler 7 is received and split by the fifth coupler 17 to obtain the measurement light and reference light of the auxiliary interferometer. The measurement light and the reference light pass through a longer optical fiber path and a shorter optical fiber path respectively, and are combined by the sixth coupler 18. The swept light outputted by the sixth coupler 18 passes through the second circulator 19, the fourth wavelength division multiplexer 20, and the fifth wavelength division multiplexer 21 respectively, and the swept light with two detection lights as light sources can be obtained respectively, which are detected by the third balanced detector 22 and the fourth balanced detector 23 respectively, and two auxiliary interferometer signals generated by the detection light can be obtained.

[0139] The air chamber calibration optical path 4 includes the first detector 24, the air chamber 25, the seventh coupler 26, the second detector 27, the fifth coupler 17, the sixth coupler 18, and the second circulator 19. The swept frequency light obtained by the first coupler 5 is input into the air chamber calibration optical path 4, and is split by the seventh coupler 26. A part of the split light beam passes through the air chamber 25 and is detected by the first detector 24, and the other part passes through the second circulator 19, and is divided into the measurement light and the reference light through the sixth coupler 18. The light passes through the longer optical fiber path and the shorter optical fiber path respectively, and is combined by the fifth coupler 17. The output light is detected by the second detector 27. The air chamber calibration signal can be obtained through the first and second detectors 24 and 27.

[0140] There are two structures in the data collection part:

[0141] There are two connection structures between the measuring interferometer 2, the auxiliary interferometer 3 and the data acquisition and data processing module 28, one of which is directly connected, such as Figure 1, and the second is to establish a connection relationship with the second multiplier 30 via the first multiplier 29, such as Figure 2 .

[0142] like Figure 3 and 4 As shown,

[0143] The method comprises the following steps:

[0144] Step 1: The steps described above have different processing methods according to different structures.

[0145] In step 1 of structure 1, the computer receives a signal to be processed i 1m (t), i 2m (t), i 1f (t), i 2f (t), i c (t), i gc (t); When the distance measuring device is structure 2, the computer receives the signal to be processed i m (t), i f (t), i c (t), i gc (t). Where t is the sampling clock.

[0146] Step 2: The steps described above have different processing methods according to different structures.

[0147] Step 2 of the structure 1, using a computer to generate a signal i aux1 (t), i aux2 (t) and the mirror-sweep auxiliary signal i obtained in step 1 of structure 1 respectively 1f (t), i 2f (t) Mixing is performed to obtain signal i′ 1f (t), i′ 2f (t), the signal i′ 1f (t), i′ 2f (t) Mix again to get signal i′ f (t), for i′ f (t) Bandpass filtering can be performed to filter out the signal i″ used to correct the nonlinearity of the measurement interferometer signal f (t), for i″ f (t) Perform phase demodulation to obtain the corrected interferometer signal phase

[0148] Step 2 of the structure 2, using a computer to generate a signal i aux (t) and the auxiliary signal i obtained in step 1 of structure 2 f (t) Mixing is performed to obtain signal i′ f (t), for i′ f(t) Bandpass filtering can be performed to filter out the signal i″ used to correct the nonlinearity of the measurement interferometer signal f (t), for i″ f (t) Perform phase demodulation to obtain the corrected interferometer signal phase

[0149] Step 3: The image frequency sweep measurement signal i obtained in step 1 of structure 1 1m (t), i 2m (t) Mixing is performed to obtain signal i m (t), the swept frequency measurement signal i obtained in step 1 of structure 2 m (t), using the corrected interferometer signal phase obtained in step 2 to i m (t) Perform nonlinear correction, and obtain signal i′ after nonlinear correction m (k), where k = 0, 1, 2, L, K, K is i′ m (k) Total points.

[0150] Step 4: The air chamber absorption signal i obtained in step 1 gc (t) Filter and record the absolute optical frequency and sampling point number corresponding to the gas cell absorption peak. Solve for the signal i corresponding to the sampling number c The phase value of (t) is obtained by fitting the absolute optical frequency f of the gas cell absorption peak. c1 ,f c2 ,L f cM With phase value L, The auxiliary interferometer length L can be obtained from the slope f .

[0151] Step 5: For the signal i′ obtained in step 3 m (k) Perform spectrum analysis and determine the frequency f corresponding to the highest spectrum energy according to the signal spectrum distribution. IF , use step 4 to get the auxiliary interferometer optical path L f , the frequency f IF Converted into the absolute distance measurement value R of the target to be measured m .

[0152] Preferably, step 1 of structure 1 is specifically:

[0153] The image frequency sweep measurement signal i output by the measuring interferometer optical path 1m (t), i 2m (t) and the mirror-image frequency-sweep auxiliary signal i output by the auxiliary interferometer optical path 1f (t), i 2f (t) can be expressed by the following formula, ignoring the amplitude:

[0154]

[0155] Among them, f 01 、f 02 are the initial optical frequencies of the frequency modulation of the tuned lasers 1 and 2, respectively; Δf1(t) and Δf2(t) are the frequency modulation curves of the tuned lasers 1 and 2, respectively (for simplicity, they are written as Δf1 and Δf2 in the formula), n air is the refractive index of air, The fiber refractive index corresponding to the initial optical frequency of the tuned lasers 1 and 2, d f is the fiber dispersion coefficient within the frequency sweep range, c is the speed of light, R m is the absolute distance of the target to be measured, ΔR(t) is the motion change curve introduced by the target motion (for simplicity, it is written as ΔR in the formula), R f It is used to measure the optical transmission distance difference between the auxiliary interferometer measurement path and the reference path.

[0156] Step 1 of the structure 2 is specifically as follows:

[0157]

[0158] The gas chamber calibration signal i output by the gas chamber calibration optical path c (t) can be expressed by the following formula:

[0159]

[0160] Signal i gc (t) represents the air cell absorption signal.

[0161] Preferably, step 2 of the structure 1 is specifically as follows:

[0162] The reference signal i is generated by computer simulation as shown below aux1 (t), i aux2 (t):

[0163] i aux1 (t) = exp(j2πf aux1 t);

[0164] i aux2 (t) = exp(j2πf aux2 t);

[0165] Among them, f aux1 、f aux2 are signal i aux1 (t), i aux2 The frequency of the above generated signal i aux1 (t), i aux2 (t) respectively with signal i 1f(Δf1), i 2f (Δf2) and we can get the signal i′ 1f (t), i′ 2f (t), as shown in the following formula:

[0166]

[0167] in, i 1f (t), i 2f The phase of the signal i′ generated above 1f (t), i′ 2f (t) Mix again, and after mixing, the signal i′ can be obtained f (t):

[0168]

[0169] Step 2 of the structure 2 is specifically as follows:

[0170] The reference signal i is generated by computer simulation as shown below aux (t):

[0171] i aux (t) = exp[j2π(f aux1 -f aux 2)t];

[0172] The above generated signal i aux1 (t) and signal i f (t) and we can get the same signal i′ as step 2 of structure 2. f (t).

[0173] The following content structure 1 has the same processing flow as structure 2. f (t) is filtered to obtain i″ f (t), the specific form is shown as follows:

[0174]

[0175] Among them, A″ f is the signal i″ f (t) amplitude, for signal i″ f (t) to solve the phase, using the known term 2π(f aux1 -f aux2 )tThe interferometer signal phase can be corrected by signal operation Since the sweep rate of the two light sources and the refractive index of the initial light frequency are similar, the phase As shown below:

[0176]

[0177] Preferably, the step 3 is specifically:

[0178] The signal i obtained in step 1 of structure 1 1m (Δf1,ΔR),i 2m (Δf2, ΔR) is mixed to obtain the signal i m (t) is shown as follows: (Step 1 of Structure 2 can directly obtain i m (t), no need to perform the following calculation)

[0179]

[0180] in, i 1m (Δf1,ΔR),i 2m The phase of (Δf2,ΔR).

[0181] Using the signal phase obtained in step 2 For i m (t) Nonlinear correction: After nonlinear correction, the signal i′ is obtained. m (k), as shown below:

[0182]

[0183] Where k = 0, 1, 2, L, K, K is i′ m (k) Total number of points, signal i′ m The phase of the second term of (k) can be further expanded and expressed as follows:

[0184]

[0185] Among them, L f is the auxiliary interferometer optical path, is the auxiliary interferometer phase Equally spaced interpolation steps.

[0186] Preferably, the step 4 is specifically:

[0187] The air cell absorption signal i obtained in step 1 gc (t) Filter and record the absolute light frequency and sampling point number corresponding to the gas cell absorption peak.

[0188] Solve the signal i corresponding to the sampling number c The phase value of (t) is obtained by fitting the absolute optical frequency f of the gas cell absorption peak. c1 ,f c2 ,L f cM With phase value L, L can be obtained from the slope f .

[0189] Preferably, the step 5 is specifically:

[0190] For the signal i′ obtained in step 3 m (k) Perform spectrum analysis and determine the frequency f corresponding to the highest spectrum energy according to the signal spectrum distribution. IF , the frequency can be expressed as follows:

[0191]

[0192] Use step 4 to get L f , the absolute distance measurement value R of the target to be measured can be obtained m :

[0193]

[0194] This implementation has the following gain effects:

[0195] Compared with the prior art, this embodiment:

[0196] The use of mirror synchronous frequency sweeping can not only make full use of the effective bandwidth of the light source, but also solve the problem of spectrum aliasing in multi-target measurement scenarios. The dual-band isolation can be effectively improved through wavelength division multiplexing cascade, avoiding crosstalk in dual-band light. The use of mirror synchronous frequency sweeping fiber structure can not only effectively reduce the system volume to reduce system complexity, but also can be immune to the adverse effects of spectrum broadening and dispersion mismatch caused by the target Doppler effect in a large frequency sweeping range. In the process of setting up the measurement system, a calibration system temperature control system is proposed on the basis of the mirror synchronous frequency sweeping fiber structure to ensure the stability and reliability of the measurement system benchmark; in the acquisition part, this system can use two acquisition structures, which can be selected according to the needs, and can achieve the optimization goals of multi-target and data channel number respectively; in the signal processing part, it is proposed that the dual reference frequency signal generated by the computer can be used to achieve the rapid solution of the auxiliary interferometer phase. In summary, this system with the above advantages can realize all-fiber high-precision frequency sweeping interferometry.

[0197] The technical solution provided by the present invention is further described in detail above through several specific implementation modes in order to highlight the advantages and benefits of the technical solution provided by the present invention. However, the several specific implementation modes described above are not intended to be used as limitations on the present invention. Any reasonable modification and improvement of the present invention, combination of implementation modes and equivalent substitution within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An all-fiber image frequency scanning interferometry ranging device based on wavelength division multiplexing, characterized in that: The device comprises: A laser unit, used for outputting frequency-sweeping light; A measuring interferometer optical path, used to generate a measurement signal according to the frequency-sweeping light; An auxiliary interferometer optical path, used to generate an auxiliary signal according to the frequency-sweeping light; An air chamber calibration optical path is used to calibrate the optical path of the auxiliary interferometer according to the swept frequency light; The data acquisition and processing module is used to obtain the distance measurement result according to the measurement signal, the auxiliary signal and the calibration signal.

2. The all-fiber image frequency scanning interferometry ranging device based on wavelength division multiplexing according to claim 1, characterized in that: The optical path of the measuring interferometer includes two optical paths of unequal lengths, and a measuring signal is obtained by detecting interference information between the measuring light reflected by the target and the reference light transmitted by the optical fiber.

3. The all-fiber image frequency scanning interferometry ranging device based on wavelength division multiplexing according to claim 1, characterized in that: The auxiliary interferometer optical path includes two optical paths of unequal lengths, and an auxiliary signal is obtained by detecting interference information between the measuring light transmitted through the long optical fiber and the reference light transmitted through the short optical fiber.

4. The all-fiber image frequency scanning interferometry ranging device based on wavelength division multiplexing according to claim 1, characterized in that: The air chamber calibration optical path and the auxiliary interferometer optical path share part of the optical path through a circulator, and the auxiliary interferometer optical path is calibrated.

5. The all-fiber image frequency scanning interferometry ranging device based on wavelength division multiplexing according to claim 1, characterized in that: The measuring interferometer optical path comprises two balanced detectors for outputting the measuring signal, which are connected to the digital acquisition and processing module via a multiplier.

6. The all-fiber image frequency scanning interferometry ranging device based on wavelength division multiplexing according to claim 5, characterized in that: The auxiliary interferometer optical path includes two balanced detectors for outputting the auxiliary signal, which are connected to the digital acquisition and processing module through a multiplier.

7. An all-fiber image frequency scanning interferometry ranging method based on wavelength division multiplexing, characterized in that: The method is implemented based on the device according to claim 1, and includes: The steps of collecting measurement signals, auxiliary signals and calibration signals; generating a reference signal, mixing and filtering the reference signal and the auxiliary signal to obtain a processed auxiliary signal; mixing and filtering and phase demodulating the processed auxiliary signal to obtain a phase correction interferometer signal; mixing the measurement signal, and obtaining a ranging result using the phase correction interferometer signal and the calibration signal.

8. An all-fiber image frequency scanning interferometry ranging method based on wavelength division multiplexing, characterized in that: The method is implemented based on the device according to claim 5, and includes: The steps of collecting measurement signals, auxiliary signals and calibration signals; generating a reference signal, mixing and filtering the reference signal and the auxiliary signal and performing phase demodulation to obtain a correction interferometer signal phase; and obtaining a distance measurement result according to the measurement signal using the correction interferometer signal phase and the calibration signal.

9. A computer storage medium for storing a computer program, characterized in that: When the computer program is read by a computer, the method according to claim 7 or 8 is implemented.

10. A computer, comprising a processor and a storage medium, characterized in that: When the computer program stored in the storage medium is read by a processor, the method of claim 7 or 8 is implemented.

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