Fast and High-Precision Mirror Sweeping Interferometric Measurement Signal Processing Method

Abstract

A signal processing method for fast and high-precision mirror sweep frequency interference measurement, which relates to the technical field of target absolute distance measurement. During the mirror sweep frequency interference measurement process, there are measurement error problems caused by sweep frequency non-linearity, Doppler effect and chromatic dispersion mismatch, and the problem of low measurement efficiency due to the change of the target distance. To solve the above problems existing in the technology simultaneously, the technology provided by the present invention includes: respectively collecting the measurement signal and the auxiliary signal of the mirror sweep frequency; roughly measuring the frequency of the upward mirror sweep measurement signal to obtain the frequency down-conversion multiple; respectively mixing the mirror signals, mixing the mixing result with the modulation signal again, filtering the mixed signal, demodulating the phase of the filtered auxiliary signal to obtain the corrected phase, down-converting the measurement signal, and performing non-linear correction on the down-sampled measurement signal to obtain the down-sampled measurement signal frequency, so as to obtain the absolute distance of the target to be measured. It is suitable for high-precision ranging and precise positioning work.

Description

Technical Field

[0001] It relates to the technical field of target absolute distance measurement, and specifically relates to a signal processing method for fast and high-precision mirror swept-frequency interference measurement. Background Art

[0002] The swept-frequency interference measurement technology based on frequency-modulated continuous wave (FMCW) has the advantages of unambiguous ranging, no need for a guide rail, and high measurement accuracy, so it is widely used in fields such as aerospace and industrial manufacturing. Its basic principle is to use the frequency difference between the transmitted signal and the echo signal to determine the target absolute distance. An ideal linearly modulated continuous wave has the ability to measure with high range resolution. However, the measurement spectrum broadening caused by the nonlinearity of the laser frequency sweep will lead to a significant decrease in the absolute distance measurement accuracy. Therefore, "effectively correcting the frequency sweep nonlinearity" is an important guarantee for achieving high-precision swept-frequency interference absolute distance measurement.

[0003] The methods for correcting frequency modulation nonlinearity are mainly divided into the phase-locked loop method, the phase comparison method, and the optical frequency monitoring method. In 2009, Peter A Rose et al. from the University of Montana proposed a laser frequency modulation nonlinearity correction technology based on the heterodyne technique. This technology uses a complex phase-locked loop to correct the frequency modulation nonlinearity, which is not only difficult to physically implement but also cannot be applied to the full spectral range. In 2014, Dale et al. realized absolute distance measurement using the phase comparison method. This scheme uses the phase ratio relationship between the auxiliary interference signal and the measurement interference signal to determine the optical path difference of the measurement interferometer. However, this scheme requires a target to be set to obtain high-quality measurement signals, so it cannot measure non-cooperative targets.

[0004] Currently, the optical frequency monitoring method is usually used in the field to achieve frequency sweep nonlinearity correction. Its main idea is to use the linear relationship between the phase of the swept-frequency interference signal and the optical frequency. The frequency-domain sampling method based on the optical frequency monitoring idea was first proposed in 1993. Such methods require re-sampling the measurement interferometer signal. To ensure accuracy, the sampling rate of the re-sampled sequence is at least twice that of the measurement interferometer signal. However, as the target distance increases continuously, the increase in the sampling rate of the re-sampled sequence will bring pressure to the processing end, resulting in a decrease in measurement efficiency. Subsequently, in 2010, Jiang Yuesong et al. from Beihang University introduced nonlinearity using optical devices based on the idea of real-time optical frequency monitoring to suppress the frequency sweep nonlinearity. This scheme is the same as the phase-locked loop scheme and is difficult to physically implement, increasing the complexity of the system. In 2016, Liu Zhigang from Xi'an Jiaotong University proposed a method for real-time tracking of the optical frequency based on the non-stationary signal order tracking method. However, this method is still affected by the number of processing points and is not conducive to realizing fast measurement. Summary of the Invention

[0005] To solve the measurement problems existing in the prior art, such as the Doppler effect, chromatic dispersion mismatch, and low measurement efficiency during swept-frequency interference measurement, the technical solution provided by the present invention is as follows:

[0006] Fast and high-precision mirror swept-frequency interference measurement signal processing, the method comprising:

[0007] Steps of separately collecting measurement signals and auxiliary signals of mirror swept-frequency;

[0008] Steps of roughly measuring the frequency of the mirror upward swept-frequency measurement signal and obtaining the down-conversion multiple using the auxiliary signal frequency;

[0009] Steps of separately mixing the mirror signals, remixing the mixing results with the modulation signal again, and filtering the remixed signals;

[0010] Steps of phase-demodulating the auxiliary signal in the filtered signal, generating a down-converted signal using the down-conversion multiple, down-converting the measurement signal in the filtered signal, and down-sampling the phase of the down-converted signal and the auxiliary signal in the filtered signal;

[0011] Steps of nonlinearly correcting the down-sampled signal;

[0012] Steps of obtaining the absolute distance of the target to be measured through spectral analysis based on the signal after nonlinear correction.

[0013] Further, a preferred embodiment is provided, which includes steps of performing Fourier transform on part of the points or channel-separated processing Fourier transform on the mirror upward measurement signal to obtain the rough measurement value of the target frequency, and solving the down-conversion multiple using the auxiliary signal frequency.

[0014] Further, a preferred embodiment is provided, which includes steps of separately mixing the two mirror measurement signals and the two mirror auxiliary signals, remixing the two mixing results with the modulation signal generated by the computer again, and separately filtering the two remixed signals.

[0015] Further, a preferred embodiment is provided, which includes steps of phase-demodulating the auxiliary signal in the filtered signal to obtain the corrected phase, using the corrected phase and the down-converted signal generated by the down-conversion multiple to down-convert the measurement signal in the filtered signal, and down-sampling the phase of the down-converted signal and the auxiliary signal in the filtered signal.

[0016] Further, a preferred embodiment is provided, which includes nonlinearly correcting the real part of the down-converted result signal according to the corrected phase.

[0017] Further, a preferred embodiment is provided, in which the signal after non-linear correction is subjected to spectral analysis to obtain the signal frequency and frequency up-conversion processing is performed, and the absolute distance of the target to be measured is obtained by calculation.

[0018] Based on the same inventive concept, the present invention further provides a signal processing device for fast and high-precision mirror sweep frequency interference measurement, the device comprising:

[0019] A module for respectively collecting mirror measurement signals and auxiliary signals;

[0020] A module for roughly measuring the frequency of the mirror up-sweep measurement signal to obtain the down-conversion multiple;

[0021] A module for respectively mixing the mirror signals, mixing the mixing results with the modulation signal again respectively, and filtering the mixed signals;

[0022] A module for phase demodulating the auxiliary signal in the filtered signal, generating a down-converted signal by using the down-conversion multiple, performing down-conversion processing on the measurement signal in the filtered signal, and performing down-sampling on the phase of the down-converted signal and the auxiliary signal in the filtered signal;

[0023] A module for performing non-linear correction on the down-sampled signal;

[0024] A module for obtaining the absolute distance of the target to be measured according to the down-conversion result signal after non-linear correction;

[0025] Based on the same inventive concept, the present invention further provides a computer storage medium for storing a computer program, and when the computer program is read by a computer, the computer executes the method.

[0026] Based on the same inventive concept, the present invention further provides a computer, comprising a processor and a storage medium, and when the processor reads the computer program stored in the storage medium, the computer executes the method.

[0027] Based on the same inventive concept, the present invention further provides a computer program product, comprising a computer program, and when the computer program is executed by a processor, the method is implemented.

[0028] Compared with the prior art, the beneficial effects of the technical solution provided by the present invention are as follows:

[0029] The fast and high-precision mirror sweep frequency interference measurement signal processing method provided by the present invention uses the interference signals generated by two lasers with mirror sweep frequency, effectively suppresses the influence of the Doppler effect on the measurement accuracy, and improves the accuracy of distance measurement. Compared with single sweep frequency interference measurement, the mirror sweep frequency technology can more accurately process the frequency change caused by the high-speed movement of the target, thereby reducing errors.

[0030] The fast and high-precision mirror sweep frequency interference measurement signal processing method provided by the present invention performs a fast Fourier transform (FFT) on a partial number of points or a channelized FFT on the mirror upward sweep measurement signal to obtain a rough measurement frequency value, providing an accurate frequency reference for subsequent signal processing and ensuring the accuracy of signal processing. Compared with traditional methods, this frequency rough measurement is faster, reducing the signal processing time.

[0031] The fast and high-precision mirror sweep frequency interference measurement signal processing method provided by the present invention generates a modulation signal and modulates the measurement signal and the auxiliary signal to obtain the filtered results of the mirror measurement and the auxiliary signal, enhancing the signal-to-noise ratio of the signal and creating conditions for the implementation of the down-conversion step.

[0032] The fast and high-precision mirror sweep frequency interference measurement signal processing method provided by the present invention performs phase demodulation and down-conversion processing on the filtered auxiliary signal, achieving the down-conversion of the signal, making subsequent signal processing and analysis more convenient, and reducing the computational complexity. The traditional method of directly processing high-frequency signals has a large amount of calculation, while through down-conversion processing, the calculation efficiency is greatly improved.

[0033] The fast and high-precision mirror sweep frequency interference measurement signal processing method provided by the present invention, while ensuring high-efficiency measurement, simultaneously realizes the correction of non-linearity, and simultaneously eliminates the problems of chromatic dispersion mismatch and Doppler effect, ensuring the measurement accuracy.

[0034] The fast and high-precision mirror sweep frequency interference measurement signal processing method provided by the present invention performs spectrum analysis on the corrected signal, and uses methods such as the all-phase time-shifted phase difference spectrum analysis method to quickly and accurately calculate the frequency of the signal, thereby accurately measuring the absolute distance of the target. Compared with traditional spectrum analysis methods, the all-phase time-shifted phase difference spectrum analysis method and the channelized FFT method can extract frequency information faster and more accurately.

[0035] The fast and high-precision mirror sweep frequency interference measurement signal processing method provided by the present invention solves the problems of Doppler effect and chromatic dispersion mismatch in mirror sweep frequency interference measurement, and improves the speed and accuracy of signal processing. Compared with other existing studies, the specific effects are as follows: achieving fast processing with high precision: frequency rough measurement and down-conversion processing significantly reduce the calculation time and improve the overall measurement speed. Reliability: The orderly processing of each step and the signal enhancement technology improve the reliability and stability of signal processing.

[0036] The fast and high-precision mirror sweep frequency interference measurement signal processing method provided by the present invention is suitable for applications in high-precision ranging and precise positioning work. Description of the Drawings

[0037] Figure 1 It is a schematic structural diagram of a mirror sweep frequency interference measurement device;

[0038] Figure 2 is a signal processing flow chart;

[0039] Figure 3 is a uniform polyphase filter bank channelization structure (upper figure), sub-channel time domain diagram (middle figure), and sub-channel frequency domain diagram (lower figure);

[0040] Figure 4 is a schematic diagram of the simulation result of absolute distance measurement. Specific implementation manners

[0041] To make the advantages and beneficial effects of the technical solution provided by the present invention more clearly reflected, the technical solution provided by the present invention will be further described in detail below with reference to the accompanying drawings. Specifically:

[0042] Embodiment 1. This embodiment provides a signal processing method for fast and high-precision mirror sweep interferometric measurement. The method includes:

[0043] Steps of respectively collecting the measurement signal and the auxiliary signal of mirror sweep;

[0044] Steps of roughly measuring the frequency of the upward mirror measurement signal to obtain the down-conversion multiple;

[0045] Modules for respectively mixing the mirror signals, mixing the mixing results with the modulation signal again, and filtering the mixed signals;

[0046] Modules for phase demodulating the auxiliary signal in the filtered signal, generating a down-converted signal using the down-conversion multiple, down-converting the measurement interferometer signal in the filtered signal, and down-sampling the phase of the down-converted signal and the auxiliary signal in the filtered signal;

[0047] Steps of non-linearly correcting the down-sampled signal;

[0048] Steps of obtaining the absolute distance of the target to be measured according to the down-converted result signal after non-linear correction.

[0049] Specifically, the technical solution provided by this embodiment includes:

[0050] Step 1: Signal reception

[0051] Brief description: Receive the mirror sweep measurement signal and the auxiliary signal through a balanced detector. Detailed description:

[0052] Receive two mirror measurement signals i m_up (t), i m_down (t).

[0053] Receive two mirror auxiliary signals i f_up(t), i f_down (t).

[0054] Output: The received mirror measurement signal and the auxiliary signal.

[0055] Step 2: Coarse frequency measurement

[0056] Brief description: Coarsely measure the frequency of the mirror up-sweeping measurement signal to obtain the coarse measured value of the target frequency Detailed description:

[0057] Perform a partial-point fast Fourier transform (FFT) or channelized FFT on the mirror up-sweeping measurement signal.

[0058] Calculate the coarsely measured frequency value of the measured interferometer signal

[0059] Use the known frequency f of the up-sweeping auxiliary interferometer signal f , calculate the frequency down-conversion multiple m required to reduce the frequency of the measured interferometer signal to f o when.

[0060] Output: The frequency down-conversion multiple m.

[0061] Step 3: Signal processing

[0062] Brief description: Generate a modulation signal and process the auxiliary signal to obtain the filtered result of the mirror auxiliary signal. Detailed description:

[0063] Generate the modulation signal i s (t) = exp(-j2πf s t).

[0064] Multiply the mirror measurement signal and multiply the mirror auxiliary signal.

[0065] Multiply the above product results with the modulation signal and perform filtering to obtain the signals i fs (t) and i ms (t).

[0066] Generate the modulation signal at the frequency f s .

[0067] Output: The filtered mirror auxiliary signal i fs (t) and the mirror measurement signal i ms (t).

[0068] Step 4: Phase demodulation and frequency down-conversion

[0069] Brief description: Perform phase demodulation and frequency down-conversion processing on the filtered auxiliary signal. Detailed description:

[0070] For the filtered i fs(t) Perform phase demodulation and downsampling to obtain its phase

[0071] Use the downsampling multiple m and Generate the downsampled signal i fm (t).

[0072] Downsample and multiply i ms (t) with i fm (t) to obtain the downsampled result i′ m (t).

[0073] Use the rough frequency measurement value in generating the downsampled signal and downsampling process

[0074] Output: The downsampled result i′ m (t).

[0075] Step 5: Nonlinear correction

[0076] Brief description: Use the correction phase to perform nonlinear correction on the signal. Detailed description:

[0077] Use Generate the correction phase

[0078] Use the correction phase to perform nonlinear correction on the real part of i′ m (t) to obtain the corrected signal i′ m (k).

[0079] Output: The corrected signal i′ m (k).

[0080] Step 6: Spectrum analysis

[0081] Brief description: Perform spectrum analysis on the corrected signal, calculate the signal frequency and perform upsampling processing to obtain the absolute distance of the target to be measured. Detailed description:

[0082] Perform spectrum analysis on i′ m (k) using fast spectrum analysis methods such as the all-phase time-shifted phase difference spectrum analysis method.

[0083] Calculate the frequency f m of the signal i′ m , and perform upsampling processing on this frequency.

[0084] Finally, calculate the absolute distance R m of the target to be measured.

[0085] Output: The absolute distance R m of the target to be measured.

[0086] Embodiment 2. This embodiment further limits the fast and high-precision mirror sweep frequency interference measurement signal processing method provided in Embodiment 1. Take a partial number of points Fourier transform or channelized Fourier transform on the mirror up-sweep measurement signal to obtain the down-conversion multiple.

[0087] Embodiment 3. This embodiment further limits the fast and high-precision mirror sweep frequency interference measurement signal processing method provided in Embodiment 1. A module that mixes the mirror signals separately, mixes the mixing results with the modulation signal again respectively, and filters the mixed signals.

[0088] Embodiment 4. This embodiment further limits the fast and high-precision mirror sweep frequency interference measurement signal processing method provided in Embodiment 1. A module that performs phase demodulation on the auxiliary signal in the filtered signal, generates a down-converted signal using the down-conversion multiple, performs down-conversion processing on the measurement interferometer signal in the filtered signal, and performs down-sampling on the phase of the down-converted signal and the auxiliary signal in the filtered signal.

[0089] Embodiment 5. This embodiment further limits the fast and high-precision mirror sweep frequency interference measurement signal processing method provided in Embodiment 1. Nonlinearly correct the real part of the down-sampled signal according to the calibration phase.

[0090] Embodiment 6. This embodiment further limits the fast and high-precision mirror sweep frequency interference measurement signal processing method provided in Embodiment 1. Perform spectrum analysis on the signal after nonlinear correction to obtain the signal frequency, and perform up-conversion processing on the signal frequency to obtain the absolute distance of the target to be measured.

[0091] Embodiment 7. This embodiment provides a fast and high-precision mirror sweep frequency interference measurement signal processing device, and the device includes:

[0092] A module for separately collecting mirror measurement signals and auxiliary signals;

[0093] A module for roughly measuring the frequency of the mirror up-sweep measurement signal to obtain the down-conversion multiple;

[0094] A module for separately mixing the mirror signals, mixing the mixing results with the modulation signal again respectively, and filtering the mixed signals;

[0095] A module for performing phase demodulation on the auxiliary signal in the filtered signal, generating a down-converted signal using the down-conversion multiple, performing down-conversion processing on the measurement signal in the filtered signal, and performing down-sampling on the phase of the down-converted signal and the auxiliary signal in the filtered signal;

[0096] A module for nonlinearly correcting the down-sampled signal;

[0097] A module that obtains the absolute distance of a target to be measured through spectral analysis based on the signal after non-linear correction.

[0098] Embodiment 8. This embodiment provides a computer storage medium for storing a computer program. When the computer program is read by a computer, the computer executes the method provided in Embodiment 1.

[0099] Embodiment 9. This embodiment provides a computer, including a processor and a storage medium. When the processor reads the computer program stored in the storage medium, the computer executes the method provided in Embodiment 1.

[0100] Embodiment 10. This embodiment provides a computer program product, including a computer program. When the computer program is executed by a processor, the method provided in Embodiment 1 is implemented.

[0101] Embodiment 11. In combination with Figures 1-4 This embodiment is described. Through specific embodiments, the above-provided technical solutions are further described in detail. Specifically:

[0102] The Doppler effect introduced by the target motion will lead to the deterioration of the accuracy of swept-frequency interference measurement. 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 a triangular-wave modulated light source. This method requires that the target motion speed remains unchanged within a complete swept-frequency period, and the measurement effect for fast-changing targets is not good. The second method is to use the signal generated by a mirror-swept light source to eliminate the Doppler effect. This method eliminates the influence of the Doppler effect on swept-frequency interference measurement by performing a mixing operation on two mirror signals with the same Doppler effect through methods such as optical filters. This solution can simultaneously have the advantages of suppressing the Doppler effect and being immune to chromatic dispersion mismatch.

[0103] To solve the technical problems existing in the prior art, this embodiment proposes a fast and high-precision mirror-swept interference measurement signal processing method.

[0104] Specifically:

[0105] Figure 1The figure shows the mirror-swept frequency interference measurement device adopted in this embodiment, which mainly consists of an auxiliary interferometer (red frame ①) and a measurement interferometer (red frame ②). The combined laser beam output by the two lasers with the mirror-swept frequency direction passes through an isolator and a coupler 1, where 99% of the laser enters the measurement interferometer and 1% of the laser enters the auxiliary interferometer. 99% of the laser is divided into the measurement light and the reference light of the measurement interferometer by a coupler 2. The measurement light enters port Ⅰ of the circulator, then enters the optical transmitting and receiving system from port Ⅱ of the circulator and is emitted to the target surface. After being reflected by the target surface, the retroreflective light passes through the optical transmitting and receiving system and enters port Ⅱ of the circulator, and is emitted from port Ⅲ of the circulator and combined with the reference light at the coupler 5 to form an interference signal. After passing through the optical filter, the mirror measurement signal can be obtained respectively, and is detected separately by a balanced detector. The laser entering the auxiliary interferometer is divided into the measurement light and the reference light of the auxiliary interferometer by a coupler 3. The measurement light and the reference light pass through the measurement arm and the reference arm respectively and are combined at the coupler 4 to form an interference signal. After passing through the optical filter, the mirror auxiliary signal can be obtained respectively. The optical frequencies of the mirror auxiliary signals are synchronized with the optical frequencies of the mirror measurement signals respectively, and can be applied to the non-linear correction of the measurement interferometer.

[0106] As Figure 2 shown in the mirror-swept frequency interference measurement device, the method includes the following steps:

[0107] Step 1: The mirror-swept frequency measurement signals i m_up (t), i m_down (t), the upper and lower swept frequency auxiliary signals i f_up (t), i f_down (t) are received by the balanced detector.

[0108] Step 2: Coarse frequency measurement is performed on the mirror upper swept measurement signal to obtain the coarse measured value of the target frequency Using the known frequency f f of the mirror upper swept auxiliary signal, the down-conversion multiple m required to reduce the measurement signal frequency to f o can be calculated.

[0109] Step 3: First, a modulation signal i s (t) is generated by a computer, multiply i m_up (t), i m_down (t) obtained in Step 1, multiply i f_up (t), i f_down (t) obtained in Step 1. Multiply the two obtained product results by i s (t) and perform filtering to obtain the signals i fs (t), i ms (t).

[0110] Step 4: For ifs (t) First, perform phase demodulation and downsampling to obtain its phase Using the downsampling multiple m obtained in step 2 and A downsampling signal i for implementing the downsampling of the measurement signal can be generated fm (t), and use the i obtained in step 3 ms (t) and i fm (t) Perform downsampling and multiplication to obtain the downsampled result i' m (t).

[0111] Step 5: Using the Obtained in step 4 to generate a calibration phase Using the calibration phase Perform non-linear calibration on the real part of i'(t) obtained in step 4 to obtain the calibrated signal i' m (k), perform spectral analysis on the signal i'(k), and calculate the frequency f of the signal i' m (k) m (k), perform upsampling on this frequency, and the absolute distance R of the target to be measured can be obtained m (k) m m .

[0112] Preferably, step 1 is specifically:

[0113] The balanced detector receives the measurement signals i m_up (t), i m_down (t) of the mirror sweep frequency, the mirror sweep frequency auxiliary signals i f_up (t), i f_down (t), and the mathematical expressions are as shown in the formula:

[0114]

[0115] Where A f_up , A f_down Are respectively the amplitudes of the mirror sweep frequency auxiliary signals, A m_up , A m_down Are respectively the amplitudes of the mirror sweep frequency measurement signals, f up (t), f down (t) Are respectively the optical frequency quantities of the mirror sweep frequency under the influence of sweep non-linearity, L m (t) Is the optical path of the measurement interferometer in the case of target movement, L f Is the optical path of the auxiliary interferometer, Is the optical fiber dispersion modulation term of the auxiliary interferometer, Is the air dispersion modulation term of the measurement interferometer, and c is the speed of light.

[0116] Preferably, step 2 is specifically:

[0117] Coarsely measure the frequency of the measured interferometer signal obtained in step 1. The method of this coarse frequency measurement can be, but is not limited to, fast coarse frequency measurement methods such as "taking a partial number of points for FFT" and "performing FFT by channel". After the coarse frequency measurement, the coarse measurement frequency value of the measured interferometer signal can be obtained. Utilize the known frequency f of the auxiliary interferometer signal f The down-conversion multiple m required to reduce the frequency of the measured interferometer signal to f can be calculated: o

[0118]

[0119] Preferably, step 3 is specifically as follows:

[0120] First, generate a modulation signal i s (t) by a computer:

[0121] i s (t) = exp(-j2πf s t),

[0122] where f s is the modulation signal frequency. Multiply i m_up (t) obtained in step 1 by i m_down (t), multiply i f_up (t) obtained in step 1 by i f_down (t). Multiply the two obtained product results by the modulation signal i s (t) generated by the computer and perform filtering to obtain signals i fs (t), i ms (t):

[0123]

[0124] where BFP is a band-pass filter, and A ms , A fs are the signal amplitudes of i ms (t), i fs (t) respectively. It can be observed that the fiber dispersion in the auxiliary interferometer signal and the air dispersion in the measured interferometer can be ignored, and the Doppler effect introduced by the target movement in the measured signal and its influence on ranging can also be ignored.

[0125] Preferably, step 4 is specifically as follows:

[0126] First, perform phase demodulation and downsampling on i fs (t) obtained in step 3 to obtain its phase

[0127] ​

[0128] Using the frequency reduction multiple m obtained in step 2 and a frequency reduction signal i(t) for implementing the measurement signal frequency reduction can be generated: fm (t):

[0129]

[0130] Downsample and multiply i(t) obtained in step 3 with i(t) to obtain the frequency-reduced result i'(t): ms (t) and i fm (t), and the amplitude A' of the signal i'(t) is obtained: m (t):

[0131]

[0132] where A' m is the amplitude of the signal i'(t). m (t).

[0133] Preferably, step 5 is specifically:

[0134] Using the obtained in step 4 to generate a correction phase

[0135]

[0136] Using the correction phase to perform non-linear correction on the real part of i'(t) obtained in step 4 to obtain the corrected signal i'(k): m (t) m (k):

[0137]

[0138] Perform spectrum analysis on the signal i'(k). The spectrum analysis method can adopt but is not limited to fast spectrum analysis methods such as the all-phase time-shifted phase difference spectrum analysis method. After spectrum analysis, the frequency f of the signal i'(k) can be calculated, and by performing up-frequency processing on this frequency, the absolute distance R of the target to be measured can be obtained: m (k) m (k) m , and m :

[0139]

[0140] Figure 3 is the uniform polyphase filter bank channelization structure (upper figure), sub-channel time domain diagram (middle figure), and sub-channel frequency domain diagram (lower figure).

[0141] Figure 4It is a simulation result diagram for absolute distance measurement; the deviation between the measured value and the true value is at the nanometer level. Compared with the traditional method, in the case of the same measurement range, when the present invention is applied, the measurement speed is significantly improved.

[0142] The method of phase-unwrapping and frequency-downconversion proposed in this embodiment significantly reduces the number of data points and the number of FFT points for subsequent signal processing compared with traditional spectrum analysis, and improves the measurement efficiency; combined with a fast frequency rough measurement scheme, it further improves the processing efficiency of the phase-unwrapping and frequency-downconversion scheme in this embodiment; the optical path structure adopts a mirror frequency-sweeping interference structure, which ensures that the frequency-sweeping interference measurement is not affected by chromatic dispersion mismatch and target movement on the basis of improving the processing efficiency. The above advantages enable the method proposed in this embodiment to achieve high precision and fast measurement at the same time.

[0143] The technical solutions provided by the present invention are further described in detail through several specific embodiments above to highlight the advantages and beneficial effects of the technical solutions provided by the present invention. However, the several specific embodiments described above are not used as a limitation to the present invention. Any reasonable modifications and improvements to the present invention, combinations of embodiments, and equivalent substitutions within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. A fast and high-precision image frequency scanning interferometry measurement signal processing method, characterized in that: The method comprises: The steps of collecting the mirror image frequency sweep measurement signal and the auxiliary signal respectively; The steps of roughly measuring the frequency of the up-sweep measurement signal and obtaining the frequency reduction multiple by using the auxiliary frequency; The steps of mixing the image measurement and the auxiliary signal respectively, mixing the mixing results with the modulation signal again respectively, and filtering the mixed signals; Downsampling the measurement signal in the filtered signal; performing phase demodulation and downsampling on the auxiliary signal in the filtered signal to obtain its phase, using the phase and the downsampling multiple to generate a down-frequency signal, and performing downsampling on the down-sampled measurement signal in the filtered signal to obtain a down-frequency result signal; A step of performing nonlinear correction on the down-conversion result signal; The step of obtaining the absolute distance of the target to be measured by spectrum analysis according to the signal after nonlinear correction.

2. The fast and high-precision image frequency scanning interferometry measurement signal processing method according to claim 1 is characterized in that: The step of performing a Fourier transform of a part of the points or a Fourier transform of the channel-by-channel processing on the upper frequency sweep measurement signal to obtain the rough measurement value of the target frequency, and solving the frequency reduction multiple by using the auxiliary signal frequency.

3. The fast and high-precision image frequency scanning interferometry measurement signal processing method according to claim 1 is characterized in that: The steps of mixing the two image measurement signals and the two image auxiliary signals respectively, mixing the two mixing results again with the modulation signals generated by the computer respectively, and filtering the two mixed signals respectively.

4. The fast and high-precision image frequency scanning interferometry measurement signal processing method according to claim 1 is characterized in that: The real part of the down-conversion result signal is subjected to nonlinear correction according to the correction phase.

5. The fast and high-precision image frequency scanning interferometry measurement signal processing method according to claim 1, characterized in that: The signal after nonlinear correction is subjected to spectrum analysis to obtain the signal frequency, and the signal frequency is subjected to frequency up-conversion processing to obtain the absolute distance of the target to be measured.

6. Fast and high-precision image frequency scanning interferometry signal processing device, characterized in that: The device comprises: Modules for collecting mirror-image frequency sweep measurement signals and auxiliary signals respectively; A module that performs a rough frequency measurement on the up-scan measurement signal to obtain the frequency reduction multiple; A module for mixing the mirror signals respectively, mixing the mixing results with the modulated signals again respectively, and filtering the mixed signals; Downsampling the measurement signal in the filtered signal; performing phase demodulation and downsampling on the auxiliary signal in the filtered signal to obtain its phase, using the phase and the downsampling multiple to generate a down-frequency signal, and performing downsampling on the down-sampled measurement signal in the filtered signal to obtain a down-frequency result signal; A device for performing nonlinear correction on the down-conversion result signal; A module that obtains the absolute distance of the target to be measured through spectrum analysis based on the signal after nonlinear correction.

7. A computer storage medium for storing a computer program, characterized in that: When the computer program is read by a computer, the computer executes the method of claim 1 .

8. A computer, comprising a processor and a storage medium, characterized in that: When the processor reads the computer program stored in the storage medium, the computer executes the method of claim 1 .

9. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the method of claim 1 is implemented.

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