Sinusoidal phase external modulation vibration measurement light path structure based on carrier suppression and measurement method thereof

Abstract

The invention discloses a sinusoidal phase external modulation vibration measurement light path structure based on carrier suppression and a measurement method thereof, belongs to the technical field of target vibration measurement, and solves the problems that linear or nonlinear errors occur in a demodulation result due to the influence of factors such as light intensity, modulation depth and carrier phase delay in a phase generation carrier demodulation technology, and the measurement accuracy is high. And the measurement precision is reduced. According to the method, an interference signal is firstly obtained, then a high-frequency part is intercepted by using a Gaussian window function, a time-varying complex carrier function is constructed to suppress the carrier frequency, and the phase is solved through low-pass filtering, so that target vibration information is obtained. The method is simple in operation and easy to implement, and is not interfered by factors such as light intensity. A Gaussian window function and a double-core optical fiber are utilized to improve the signal-to-noise ratio, the carrier frequency is suppressed to facilitate signal processing, and target vibration information can be accurately obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of target vibration measurement, and in particular to a carrier suppression-based sinusoidal phase external modulation vibration measurement optical path structure and a measurement method thereof. Background Art

[0002] Phase-generated carrier (PGC) demodulation technology is a key signal processing method in the field of fiber-optic sensing and is widely used in the demodulation process of interferometric fiber-optic sensors. The core of this technology lies in introducing a high-frequency carrier signal through modulation, embedding the phase information to be measured into the sideband of the high-frequency carrier. Due to its advantages such as high sensitivity, wide dynamic range, and strong anti-interference capabilities, it has been widely used in the field of fiber-optic sensing signal demodulation. However, the PGC demodulation process is relatively complex, requiring the generation of a pair of orthogonal signals and extracting phase information through a series of signal processing steps such as mixing, filtering, differentiation, integration, and filtering. Furthermore, the design of low-pass and high-pass filters with appropriate parameters also increases the difficulty of implementing the system hardware and software. The PGC demodulation results are also susceptible to interference from multiple factors, such as light intensity variations, modulation depth fluctuations, and carrier phase delay. Therefore, simplifying the calculation process and effectively reducing or eliminating the impact of these factors on measurement accuracy are key factors in achieving high-precision fiber-optic sensing measurements.

[0003] To address these issues, the Institute of Semiconductors, Chinese Academy of Sciences, has been conducting research on the digitalization of phase-carrier demodulation algorithms since 2003, successfully developing a normalization algorithm based on differential multiplication and associated amplitude modulation effects. In 2010, He Jun and other researchers published their research on the PGC-DSM (Phase Generated Carrier-Differential Scaling) algorithm in the Journal of Lightwave Technology. To further reduce the impact of modulation depth on the phase-carrier demodulation algorithm, they proposed an innovative demodulation method that combines the PGC-Arctan demodulation algorithm with differential scaling techniques. In 2012, building on their previous work, the research team developed a new, highly stable phase-carrier demodulation algorithm to reduce harmonic distortion and the sensitivity of hydrophone systems to rapid fluctuations in light intensity. In 2017, Zhang Shihua et al. proposed a method for indirectly measuring and compensating for phase delay by adjusting the compensation phase in the carrier signal. Similar to the traditional PGC algorithm, this method first multiplies the interference signal by a reference signal and then low-pass filters it to produce a set of orthogonal signals. By adjusting the compensation phase until the amplitudes of the orthogonal signals reach their maximum values ​​simultaneously, it is determined that the phase delay has been compensated. However, this method requires gradually changing the compensation phase value to eliminate the influence of the phase delay. This process is time-consuming and makes it difficult to achieve accurate real-time compensation of phase delay when the phase changes in real time.

[0004] To address the above problems, the present invention proposes a sinusoidal phase external modulation measurement method based on carrier suppression. The interference signal is intercepted in the time domain using a Gaussian window function, and then a time-varying complex carrier function is constructed to match the frequency with the carrier, suppressing the carrier frequency so that the vibration phase term in the interference signal is moved to the baseband. The signal with suppressed carrier frequency is then low-pass filtered and the phase is solved to obtain the vibration information of the target. Summary of the Invention

[0005] This paper proposes a carrier-suppressed, sinusoidal phase externally modulated vibration measurement optical path structure and measurement method. First, an optical path is constructed using a laser, coupler, and electro-optical phase modulator to obtain an interference signal carrying target vibration information. A Gaussian window function is then used in the time domain to intercept the high-frequency portion of the interference signal. A time-varying complex carrier function is then constructed and multiplied with the carrier frequency to suppress the carrier frequency, shifting the vibration phase term to baseband. Finally, the processed signal is low-pass filtered and phase-decoded to obtain the target vibration information. This solves the problem in phase-generated carrier demodulation technology of linear or nonlinear errors in the demodulation result and reduced measurement accuracy caused by factors such as light intensity, modulation depth, and carrier phase delay.

[0006] A carrier-suppression-based sinusoidal phase external modulation vibration measurement optical path structure includes a target to be measured, a laser, a first coupler, a second coupler, an electro-optical phase modulator, a balanced detector, and an optical system. The laser is optically connected to the first coupler, and the output end of the first coupler is divided into a reference optical path and a measurement optical path. In the reference optical path, the first coupler, the electro-optical phase modulator, and the second coupler are optically connected in sequence; in the measurement optical path, the first coupler, the optical system, and the second coupler are optically connected in sequence, and the second coupler is optically connected to the balanced detector. The target to be measured is arranged on the output light side of the optical system.

[0007] Furthermore, a laser is used to transmit a fixed frequency optical signal to the first coupler;

[0008] a first coupler for dividing the optical signal emitted by the laser into reference light and measurement light, wherein 10% of the optical signal enters the reference optical path as the reference light and 90% of the optical signal enters the measurement optical path as the measurement light;

[0009] An electro-optical phase modulator is used in the reference optical path to modulate the reference light into a high-frequency sinusoidal carrier signal under the action of an external voltage applied by a signal generator;

[0010] an optical system for emitting the measuring light in the measuring optical path onto the target to be measured so that the measuring light carries the low-frequency vibration information of the target to be measured, and receiving the light reflected from the target to be measured and transmitting it to the second coupler;

[0011] a second coupler, for coupling the reference light in the reference light path with the measurement light in the measurement light path, and outputting the coupled light to a balanced detector;

[0012] The balanced detector is used to receive the coupled reference light and measurement light output by the second coupler and generate an interference signal so as to perform subsequent signal processing to obtain target vibration information.

[0013] Furthermore, the first coupler is connected to the optical system via one core optical path of the dual-core optical fiber, and the optical system is connected to the second coupler via the other core optical path.

[0014] A carrier-suppressed sinusoidal phase external modulation vibration measurement method is based on the above-mentioned carrier-suppressed sinusoidal phase external modulation vibration measurement optical path structure, characterized in that the carrier-suppressed sinusoidal phase external modulation vibration measurement method includes the following steps:

[0015] S1. A laser is used to emit a fixed-frequency optical signal, which is then split into reference light and measurement light via a first coupler. 10% of the light, serving as the reference light, is modulated by an electro-optical phase modulator and a voltage applied by a signal generator into a high-frequency sinusoidal carrier signal. 90% of the light, serving as the measurement light, is emitted through an optical system onto the target to be measured and reflected and received. The measurement light carries the target's low-frequency vibration information. The reference and measurement lights are ultimately received by a balanced detector via a second coupler to produce an interference signal.

[0016] S2. Add a periodic Gaussian window function to the time domain of the interference signal obtained by the balanced detector to intercept the high-frequency part of the interference signal. The frequency of the Gaussian window function is twice the frequency of the interference signal, thereby improving the signal-to-noise ratio of the interference signal.

[0017] S3. First, the interference signal is expanded using the Euler formula. Then, a time-varying complex carrier function is constructed so that its frequency component matches the carrier frequency component in the interference signal. Then, the interference signal, the Gaussian window function, and the time-varying complex carrier function are multiplied together. Based on the "mixing" principle of signal processing, the carrier frequency component is suppressed, and the phase term containing the target vibration information is converted into a baseband signal. At this time, the signal spectrum contains the baseband signal and a term with twice the carrier frequency.

[0018] S4. Perform low-pass filtering on the signal processed by S1-S3 to remove the double carrier frequency term to obtain the phase term containing the target vibration information; then solve the phase term to obtain the target vibration information, and obtain the target vibration trajectory diagram and vibration error diagram through simulation.

[0019] Furthermore, in S1, the mathematical expression of the interference signal obtained by the balanced detector is as follows:

[0020]

[0021] In the formula, C is the modulation depth, ω m is the modulation frequency, ω0 is the initial angular frequency of the laser, c is the speed of light, d(t) is the vibration trajectory of the target, is the fixed phase difference caused by the optical path difference between the reference light and the measurement light, V, V π are the applied voltage and half-wave voltage of the electro-optic phase modulator respectively.

[0022] Furthermore, in S2, a periodic Gaussian window function is added to the interference signal time domain. The mathematical expression of the Gaussian window function is as follows:

[0023]

[0024] Where n is the number of cycles of the window function, σ is the Gaussian parameter, and T m is the modulation period.

[0025] Furthermore, in S3, the interference signal of formula (1) is expanded using the Euler formula to obtain:

[0026]

[0027] Construct a time-varying complex carrier function:

[0028] A(t)=exp[jC A cos(ω m t)] (5)

[0029] Where C A is the amplitude of the time-varying complex carrier function, let C A =C, and then multiply the interference signal, Gaussian window function, and time-varying complex carrier function to obtain:

[0030]

[0031] The spectrum of the signal Q(t) consists of two parts: one is the phase term containing the target vibration information, which is the baseband signal; the other is the double carrier frequency term.

[0032] Furthermore, the phase term containing the target vibration information is obtained by low-pass filtering formula (6), and then the vibration trajectory d(t) of the target is obtained.

[0033]

[0034] Where, LPF[ g ] represents low-pass filtering, real(g) and imag(g) represent the process of taking the real part and imaginary part of the signal respectively, so as to solve the vibration information of the target, and thus obtain the target vibration trajectory diagram and vibration error diagram.

[0035] A storage medium stores a computer program, which, when executed by a processor, implements the above-mentioned carrier-suppression-based sinusoidal phase external modulation vibration measurement method.

[0036] A computer device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the above-mentioned carrier-suppression-based sinusoidal phase external modulation vibration measurement method.

[0037] Beneficial effects of the present invention:

[0038] 1. The present invention provides a carrier-suppressed sinusoidal phase external modulation vibration measurement optical path structure and its measurement method. Compared with the traditional phase-generated carrier demodulation algorithm, the present invention has a simple operation process, improves the signal processing efficiency, is easy to implement in terms of software and hardware, and is not affected by factors such as light intensity changes, modulation depth fluctuations, and carrier phase delays.

[0039] 2. The present invention uses a Gaussian window function to intercept the interference signal in the time domain, which can effectively retain the high-frequency part of the signal, improve the signal-to-noise ratio of the signal, and reduce measurement errors.

[0040] 3. The present invention utilizes a time-varying complex carrier function to suppress the carrier frequency in the interference signal, so that the phase term containing the target vibration information becomes a baseband signal, which is beneficial to subsequent signal processing and analysis.

[0041] 4. The optical path of the present invention utilizes dual-core optical fiber, thereby improving the signal-to-noise ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a structural diagram of a carrier-suppressed sinusoidal phase external modulation vibration measurement optical path structure according to the present invention;

[0043] Figure 2 is the relative position of the interference signal and the Gaussian window function;

[0044] Figure 3 is the frequency domain diagram before and after the interference signal is multiplied by the Gaussian window function, where Figure 3 (a) is the frequency domain diagram of the interference signal; Figure 3 (b) is the frequency domain diagram of the interference signal after multiplying the Gaussian window function;

[0045] Figure 4 It is the frequency domain diagram after the interference signal, Gaussian window function and time-varying complex carrier function are multiplied together;

[0046] Figure 5 is the target vibration information and measurement error, where Figure 5 (a) is the target vibration information; Figure 5 (b) is the measurement error. DETAILED DESCRIPTION

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0048] Reference Figure 1As shown, a carrier-suppressed sinusoidal phase external modulation vibration measurement optical path structure includes a target to be measured, a laser, a first coupler, a second coupler, an electro-optical phase modulator, a balanced detector and an optical system. The laser is optically connected to the first coupler, and the output end of the first coupler is divided into a reference optical path and a measurement optical path. In the reference optical path, the first coupler, the electro-optical phase modulator and the second coupler are optically connected in sequence; in the measurement optical path, the first coupler, the optical system and the second coupler are optically connected in sequence, and the second coupler is optically connected to the balanced detector. The target to be measured is provided on the output light side of the optical system.

[0049] Specifically, the carrier-suppressed sinusoidal phase external modulation vibration measurement optical path structure constructed by the present invention divides the optical signal emitted by the laser into reference light and measurement light through a unique optical path layout, laying the foundation for subsequent precise measurement. The reference light is modulated into a high-frequency sinusoidal carrier signal by an electro-optical phase modulator, and the measurement light carries the low-frequency vibration information of the target to be measured. After passing through the second coupler, the two interfere at the balanced detector, so that the interference signal carries the target vibration information. Among them, the optical system transmits the measurement light to the target to be measured and receives the reflected light. The incident light side is connected to the dual-core optical fiber. The use of the dual-core optical fiber further improves the signal-to-noise ratio of the signal, reduces the loss and interference during the signal transmission process, and makes the measurement results more stable and reliable. Relying on the dual-core optical fiber, the optical signals sent and received by the optical system to the target to be measured are two separate channels, which do not interfere with each other, thereby improving the signal-to-noise ratio of the signal. The light reflected back by the target to be measured is used as the measurement light. At the same time, due to the use of the dual-core optical fiber, the present invention avoids the use of a circulator and reduces one device, thereby reducing the interference caused by the device and making the entire optical path structure simpler. Compared to the complex optical paths and signal processing required by traditional phase-generated carrier demodulation techniques, the optical path structure of this invention significantly simplifies the overall architecture, reduces complex signal processing steps, lowers hardware costs and implementation complexity, and is easier to build and maintain. Furthermore, this optical path structure is unaffected by factors such as light intensity variations, modulation depth fluctuations, and carrier phase delays, ensuring stable and accurate acquisition of interference signals under diverse environmental conditions. This provides a solid optical foundation for subsequent precise measurement of target vibration information, effectively improving measurement accuracy and stability.

[0050] Furthermore, a laser is used to transmit a fixed frequency optical signal to the first coupler;

[0051] a first coupler for dividing the optical signal emitted by the laser into reference light and measurement light, wherein 10% of the optical signal enters the reference optical path as the reference light and 90% of the optical signal enters the measurement optical path as the measurement light;

[0052] An electro-optical phase modulator is used in the reference optical path to modulate the reference light into a high-frequency sinusoidal carrier signal under the action of an external voltage applied by a signal generator;

[0053] an optical system for emitting the measuring light in the measuring optical path onto the target to be measured so that the measuring light carries the low-frequency vibration information of the target to be measured, and receiving the light reflected from the target to be measured and transmitting it to the second coupler;

[0054] a second coupler, for coupling the reference light in the reference light path with the measurement light in the measurement light path, and outputting the coupled light to a balanced detector;

[0055] The balanced detector is used to receive the coupled reference light and measurement light output by the second coupler and generate an interference signal so as to perform subsequent signal processing to obtain target vibration information.

[0056] Specifically, the laser emits a fixed-frequency optical signal, providing a stable light source for the entire measurement system and ensuring the consistency of the optical signal frequency during the measurement process, which is the basis for obtaining reliable measurement data. The first coupler divides the optical signal into reference light and measurement light in a specific ratio. This precise splitting design enables the reference light to generate a high-frequency sinusoidal carrier signal, and the measurement light to carry the target vibration information. The two work together to provide the necessary conditions for the subsequent generation and analysis of interference signals. The electro-optical phase modulator modulates the reference light into a high-frequency sinusoidal carrier signal under the action of an external voltage from a signal generator. This modulation process is one of the core technologies of the present invention. By introducing a high-frequency carrier, its characteristics are utilized to load the target's low-frequency vibration information onto the sideband of the high-frequency carrier, providing a key carrier for subsequent signal processing and vibration information extraction. The optical system is responsible for transmitting the measurement light to the target to be measured and receiving the reflected light, accurately realizing the interaction between the measurement light and the target, so that the measurement light carries the target's low-frequency vibration information. Its transmission of the measurement light and reception of the reflected light ensure that the target vibration information is accurately integrated into the optical signal. The second coupler couples the reference light and measurement light and transmits them to a balanced detector. The balanced detector generates an interference signal, which contains key information about the target's vibration. This interference signal is the core data source for measuring target vibration and provides raw data for subsequent signal processing. Its stable reception performance ensures the integrity of the interference signal, facilitating the acquisition of target vibration information through a series of signal processing steps. These components work closely together to create a fully functional, efficient, and stable measurement optical path architecture. This effectively simplifies the measurement process, improves measurement accuracy, and overcomes the interference issues that plague traditional measurement methods, ensuring stable and accurate acquisition of target vibration information.

[0057] Furthermore, the first coupler is connected to the optical system via one core optical path of the dual-core optical fiber, and the optical system is connected to the second coupler via the other core optical path.

[0058] Specifically, in the present invention, the first coupler is connected to the optical system through one core optical path of a dual-core optical fiber, and the optical system is connected to the second coupler through the other core optical path. This structure uses dual-core optical fiber to transmit optical signals, which can effectively improve the signal-to-noise ratio of the interference signal, thereby improving the accuracy of the target vibration measurement, while ensuring the stability of signal transmission, and laying a good foundation for subsequent signal processing and accurate acquisition of target vibration information. In the subsequent signal processing link, the interference signal with a high signal-to-noise ratio can reduce misjudgment and error. Whether it is adding a Gaussian window function to intercept the high-frequency part, or constructing a time-varying complex carrier function to suppress the carrier frequency component, or performing low-pass filtering to solve the phase and other operations, it can be based on a higher-quality original signal, thereby greatly improving the accuracy of obtaining the target vibration information, so that the final target vibration trajectory diagram can more truly reflect the actual vibration of the target.

[0059] A carrier-suppressed sinusoidal phase external modulation vibration measurement method is based on the above-mentioned carrier-suppressed sinusoidal phase external modulation vibration measurement optical path structure, characterized in that the carrier-suppressed sinusoidal phase external modulation vibration measurement method includes the following steps:

[0060] S1. A laser is used to emit a fixed-frequency optical signal, which is then split into reference light and measurement light via a first coupler. 10% of the light, serving as the reference light, is modulated by an electro-optical phase modulator and a voltage applied by a signal generator into a high-frequency sinusoidal carrier signal. 90% of the light, serving as the measurement light, is emitted through an optical system onto the target to be measured and reflected and received. The measurement light carries the target's low-frequency vibration information. The reference and measurement lights are ultimately received by a balanced detector via a second coupler to produce an interference signal.

[0061] S2. Add a periodic Gaussian window function to the time domain of the interference signal obtained by the balanced detector to intercept the high-frequency part of the interference signal. The frequency of the Gaussian window function is twice the frequency of the interference signal, thereby improving the signal-to-noise ratio of the interference signal.

[0062] S3. First, the interference signal is expanded using the Euler formula. Then, a time-varying complex carrier function is constructed so that its frequency component matches the carrier frequency component in the interference signal. Then, the interference signal, the Gaussian window function, and the time-varying complex carrier function are multiplied together. Based on the "mixing" principle of signal processing, the carrier frequency component is suppressed, and the phase term containing the target vibration information is converted into a baseband signal. At this time, the signal spectrum contains the baseband signal and a term with twice the carrier frequency.

[0063] S4. Perform low-pass filtering on the signal processed by S1-S3 to remove the double carrier frequency term to obtain the phase term containing the target vibration information; then solve the phase term to obtain the target vibration information, and obtain the target vibration trajectory diagram and vibration error diagram through simulation.

[0064] Specifically, in the link of obtaining the interference signal, a fixed-frequency optical signal is emitted by a laser and divided into reference light and measurement light by a coupler. The reference light is modulated into a high-frequency sinusoidal carrier signal, and the measurement light carries the low-frequency vibration information of the target to be measured. After the two interfere with each other, they are received by a balanced detector. This process cleverly integrates the target vibration information into the interference signal, laying the foundation for subsequent measurements. Compared with traditional methods, this method of the present invention can more effectively capture subtle changes in the target vibration and greatly improve the measurement sensitivity. In the signal processing stage, a Gaussian window function is used to intercept the high-frequency part of the interference signal in the time domain, effectively improving the signal-to-noise ratio of the signal. This is because the Gaussian window function can accurately retain the key high-frequency information in the interference signal while suppressing noise interference, making the data quality based on which subsequent signal processing is based higher. In complex measurement environments, noise often affects measurement accuracy. Through this operation, the present invention significantly reduces the impact of noise on the measurement results and ensures the reliability of the measurement data. Constructing a time-varying complex carrier function and multiplying it with the interference signal to suppress the carrier frequency component is one of the core technical highlights of the present invention. Based on the "mixing" principle of signal processing, this method converts the phase term containing the target vibration information into a baseband signal, which is convenient for subsequent processing. It breaks the limitations of the complex signal processing process in traditional phase-generated carrier demodulation technology, simplifies the steps of extracting target vibration information from the interference signal, and improves signal processing efficiency. Moreover, this method is not affected by factors such as light intensity changes, modulation depth fluctuations, and carrier phase delays, ensuring that the target vibration information can be stably and accurately extracted under different measurement conditions. Finally, the processed signal is low-pass filtered to remove the double carrier frequency term, and then the phase term is solved to obtain the target vibration information. The target vibration trajectory diagram and vibration error diagram are obtained through simulation. The low-pass filtering operation further purifies the signal and removes unnecessary frequency components, making the acquired target vibration information more accurate. The vibration trajectory diagram and vibration error diagram present the measurement results in an intuitive manner, providing researchers and engineers with a clear reference for in-depth analysis of the target's vibration characteristics.

[0065] Furthermore, in S1, the mathematical expression of the interference signal obtained by the balanced detector is as follows:

[0066]

[0067] In the formula, C is the modulation depth, ω m is the modulation frequency, ω0 is the initial angular frequency of the laser, c is the speed of light, d(t) is the vibration trajectory of the target, is the fixed phase difference caused by the optical path difference between the reference light and the measurement light, V, V π are the applied voltage and half-wave voltage of the electro-optic phase modulator respectively.

[0068] Specifically, the above mathematical expression clearly demonstrates the close connection between the interference signal and multiple key parameters. Parameters such as the modulation depth C are integrated into the formula. This allows researchers to gain a deeper understanding of the generation mechanism and variation patterns of the interference signal by analyzing these parameters. For example, when studying the impact of the target vibration trajectory on the interference signal, researchers can use this formula to vary the target vibration trajectory while keeping other parameters relatively constant and observe the corresponding changes in the interference signal. This allows them to establish a quantitative relationship between the target vibration and the interference signal, providing a theoretical basis for accurately measuring target vibration information. From the perspective of improving measurement accuracy, this mathematical expression provides a powerful tool for signal processing and error analysis. In actual measurements, by measuring and controlling the various parameters in the formula, the characteristics of the interference signal can be more accurately predicted and adjusted. If errors are detected in the measurement results, the formula can be used to identify the inaccurate parameter or parameters, allowing targeted improvements to be made. For example, if the measured interference signal does not match expectations, by examining the discrepancies between the actual and theoretical values ​​of parameters such as the modulation depth and optical path difference, the problem can be quickly identified and corrected, effectively improving measurement accuracy and ensuring the authenticity and reliability of the acquired target vibration information. This formula also plays a crucial role in optimizing measurement systems. Based on this expression, researchers can optimize the design of the measurement optical path structure and signal processing flow. By adjusting the applied voltage of the electro-optical phase modulator and changing the layout of the optical system to optimize the optical path difference, the formula predicts the changes in the interference signal. This allows researchers to find the most optimal parameter combination and system configuration for measuring specific target vibrations, further improving the performance and adaptability of the measurement system.

[0069] Furthermore, in S2, a periodic Gaussian window function is added to the interference signal time domain. The mathematical expression of the Gaussian window function is as follows:

[0070]

[0071] Where n is the number of cycles of the window function, σ is the Gaussian parameter, and T m is the modulation period. The relative position of the interference signal and the Gaussian window function in the time domain is as follows: Figure 2 As shown in the figure, the spectrum of the interference signal before and after windowing is compared. Figure 3 (a) Figure 3 (b) shown.

[0072] Specifically, the mathematical expression of the Gaussian window function of the present invention provides a theoretical basis for accurately intercepting the high-frequency part of the interference signal. By adjusting the window function period number n, Gaussian parameter σ and modulation period T m, which can screen the interference signal in a targeted manner. In actual measurements, the interference signal is often interfered with by various noises, while the high-frequency portion usually contains important information closely related to the target vibration. Using the Gaussian window function determined by this mathematical expression, this high-frequency information can be effectively retained while suppressing low-frequency noise, greatly improving the signal-to-noise ratio of the interference signal. This enables subsequent signal analysis and processing to be based on higher-quality data, reduces the impact of noise on the measurement results, and improves measurement accuracy. The Gaussian window function of the present invention enables accurate extraction of target vibration information even in complex measurement environments. Due to the characteristics of the Gaussian window function, its application in the time domain can smooth the interference signal and avoid errors caused by signal mutations. In the construction of a time-varying complex carrier function to suppress the carrier frequency component and subsequent low-pass filtering operations, the interference signal processed by the Gaussian window function can participate in the calculation more stably, reducing the error propagation caused by signal fluctuations, thereby improving the accuracy of the target vibration information ultimately obtained, so that the target vibration trajectory diagram and vibration error diagram can more accurately reflect the actual vibration of the target. In addition, this mathematical expression also facilitates the optimization and expansion of measurement methods. Researchers can flexibly adjust the characteristics of the Gaussian window function by adjusting the parameters in the expression to meet different measurement requirements. This flexibility allows the measurement method to better adapt to different measurement scenarios and broaden its application range, playing an important role in vibration monitoring of precision instruments and vibration detection of equipment in complex industrial environments.

[0073] Furthermore, in S3, the interference signal of formula (1) is expanded using the Euler formula to obtain:

[0074]

[0075] Construct a time-varying complex carrier function:

[0076] A(t)=exp[jC A cos(ω m t)] (5)

[0077] Where C A is the amplitude of the time-varying complex carrier function, let C A =C, and then multiply the interference signal, Gaussian window function, and time-varying complex carrier function to obtain:

[0078]

[0079] The spectrum of the signal Q(t) is as follows Figure 4 As shown in the figure, the spectrum of the signal Q(t) contains two parts. One part is the phase term containing the target vibration information, which is the baseband signal; the other part is the double carrier frequency term.

[0080] Specifically, the interference signal is expanded using the Euler formula, making the mathematical form of the interference signal clearer and providing convenience for subsequent processing. Through this expansion method, the originally complex interference signal is decomposed into multiple parts with clear physical meanings, which helps researchers to deeply understand the composition structure of the signal, so as to more accurately analyze and extract the target vibration information therein. Constructing a time-varying complex carrier function and matching its frequency component with the carrier frequency component in the interference signal is one of the core innovations of the present invention. The time-varying complex carrier function is multiplied by the interference signal and the Gaussian window function, and the carrier frequency component is suppressed based on the "mixing" principle of signal processing, and the phase term containing the target vibration information is successfully converted into a baseband signal. This transformation is of great significance. In traditional measurement methods, the carrier frequency component often interferes with the extraction of target vibration information. The present invention transfers the target vibration information to the baseband signal in this clever way, making subsequent signal processing simpler and more efficient. The processing difficulty of the baseband signal is relatively low, and the target vibration information can be obtained more directly, which greatly improves the accuracy and efficiency of the measurement. After multiplying the three, the signal spectrum consists of the baseband signal and a term at twice the carrier frequency. This spectral structure provides a clear target for subsequent low-pass filtering. Low-pass filtering can specifically remove the term at twice the carrier frequency, retaining only the baseband signal containing the target vibration information. This further purifies the signal and reduces interference from unnecessary frequency components on the measurement results. This method ultimately yields purer and more accurate target vibration information, laying a solid foundation for obtaining precise target vibration trajectory and vibration error maps.

[0081] Furthermore, the phase term containing the target vibration information is obtained by low-pass filtering formula (6), and then the vibration trajectory d(t) of the target is obtained.

[0082]

[0083] In the formula, LPF[g] represents low-pass filtering, real(g) and imag(g) represent the process of taking the real part and imaginary part of the signal respectively. According to the above process, the vibration information of the target can be solved. The above process is simulated, and the simulation results are as follows: Figure 5 As shown, Figure 5 (a) is the target vibration trajectory diagram, Figure 5 (b) is the vibration error diagram.

[0084] Specifically, the low-pass filtering operation of the present invention further optimizes and purifies the signal. While the previous step suppresses the carrier frequency component by constructing a time-varying complex carrier function, converting the phase term containing the target vibration information into a baseband signal, the signal still contains undesirable components such as the double carrier frequency term. Low-pass filtering accurately removes these interfering terms, retaining only the phase term containing the target vibration information, significantly improving signal purity. This is like precisely filtering out the most critical information from a pool of mixed information, making subsequent acquisition of target vibration information more accurate and reliable. In actual measurements, interfering signals can cause deviations in measurement results, but low-pass filtering effectively addresses this issue, ensuring that the measurement results truly reflect the target's vibration conditions. Solving for the phase term containing the target vibration information and obtaining the target vibration trajectory based on this information provides intuitive and critical data for studying the target's vibration characteristics. Accurate phase determination enables in-depth analysis of target vibration parameters such as frequency, amplitude, and phase, leading to a comprehensive understanding of the target's vibration state. For example, in mechanical engineering, for vibration monitoring of rotating machinery, an accurate vibration trajectory can help engineers determine whether the equipment is faulty, as well as the type and location of the fault. This is crucial for equipment maintenance and upkeep, as it can identify potential problems in advance, avoid losses caused by equipment failure, and improve production efficiency and equipment reliability. Based on the solved vibration trajectory, a target vibration trajectory diagram and a vibration error diagram are plotted, providing researchers and engineers with a visual analysis tool. The vibration trajectory diagram can clearly display the changes in the target's vibration position at different times, allowing people to intuitively observe the target's vibration patterns. The vibration error diagram quantifies the difference between the measurement results and the true value, helping to evaluate the accuracy of the measurement. By analyzing these two diagrams, problems in the measurement process, such as deviations in the optical path system and deficiencies in the signal processing algorithm, can be promptly discovered, allowing targeted improvements and optimizations to continuously improve the accuracy and reliability of the measurement method.

[0085] A storage medium stores a computer program, which, when executed by a processor, implements the above-mentioned carrier-suppression-based sinusoidal phase external modulation vibration measurement method.

[0086] Specifically, the storage medium, as a carrier of the computer program, greatly enhances the dissemination and reusability of the measurement method of the present invention. In scientific research and industry, numerous researchers and engineers may need to apply this measurement method in different projects or scenarios. The storage medium enables this complex measurement technology to be shared and transferred in a convenient manner. Whether it's a cross-regional scientific research collaboration project or an application for equipment vibration monitoring across different companies, simply accessing the computer program on the storage medium allows the measurement method of the present invention to be quickly implemented on the corresponding computing device, avoiding the tedious process of repeated development and debugging, saving significant manpower, material resources, and time. From the perspective of technological inheritance, the storage medium ensures the long-term preservation and continuation of the technology of the present invention. While research teams and personnel may change over time, the computer program on the storage medium fully records the technical details of the present invention, including every key step, from optical path structure construction to signal processing algorithms. New researchers or engineers can quickly master and apply the technology by reading the program on the storage medium, ensuring the continuity and inheritance of the technology and preventing technology loss due to personnel changes. In terms of technological optimization and innovation, the storage medium facilitates subsequent improvements. Researchers can conduct secondary development based on computer programs stored in storage media, tailored to new research needs and technological trends. For example, they can optimize existing programs by incorporating emerging sensor technologies or signal processing algorithms to further improve measurement accuracy or expand the scope of application of measurement methods. This optimization and innovation based on existing programs can fully leverage previous research results, accelerate technological iteration and upgrades, and promote technological advancement in the entire vibration measurement field, enabling it to better meet evolving practical needs.

[0087] A computer device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the above-mentioned carrier-suppression-based sinusoidal phase external modulation vibration measurement method.

[0088] Specifically, from the perspective of measurement convenience, this computer device greatly simplifies the measurement process. Researchers and engineers no longer need to manually build complex signal processing systems or write tedious code to implement measurement methods. Simply connect the target to the optical path and start the computer device. The computer program stored in the memory, executed by the processor, automatically completes a series of complex operations, from interferometric signal acquisition, Gaussian window function processing, carrier suppression, to vibration information interpretation, ultimately directly outputting target vibration trajectory and vibration error maps. This significantly lowers the barrier to entry for measurement technology, allowing even those with limited technical knowledge to quickly master high-precision vibration measurements. In terms of computing performance, the processor's powerful data processing capabilities ensure efficient measurement. The carrier-suppressed sinusoidal phase external modulation vibration measurement method involves complex signal processing operations, such as mathematical transformation of the interferometric signal, construction of a time-varying complex carrier function, and extensive numerical calculations. The computer device's processor can rapidly process this data, shortening measurement time and meeting the requirements for real-time measurement. When performing real-time vibration monitoring on equipment on industrial production lines, rapid measurement response can promptly detect abnormal vibrations, prevent further escalation of equipment failures, and ensure continuous and stable production. Memory provides stable data storage and access support for the measurement process. During the measurement process, everything from the optical signal parameters emitted by the laser and interference signal data to various data generated during intermediate processing must be stored. Memory reliably stores this data, preventing data loss or corruption and ensuring measurement accuracy and repeatability. Furthermore, fast data access enables the processor to obtain required data promptly, further improving the fluidity and efficiency of the measurement process. Furthermore, the deep integration of computer equipment and measurement method programs facilitates technological expansion and upgrades. As technology continues to evolve, when measurement methods need to be improved or new features added, R&D personnel can modify and optimize the stored programs directly on the computer equipment and quickly apply them to actual measurements. This convenient upgrade method enables measurement technology to keep pace with scientific and technological development, continuously improving measurement accuracy and adaptability, better serving various fields requiring precise vibration measurement, such as scientific research, industry, and healthcare, and promoting technological progress and development in related industries.

[0089] The carrier-suppressed sinusoidal phase external modulation vibration measurement optical path structure and measurement method proposed in this invention utilize a unique optical path design, using components such as lasers and couplers to obtain interference signals. The interference signals are then processed using a Gaussian window function, a time-varying complex carrier function, and low-pass filtered. This simplifies the computational process, making it unaffected by factors such as light intensity and modulation depth, effectively improving signal processing efficiency and making it easy to implement in both software and hardware. Furthermore, this method utilizes a Gaussian window function to improve the signal-to-noise ratio, further optimizes signal quality using dual-core optical fiber, and reduces the carrier frequency to make the vibration phase term a baseband signal, facilitating subsequent processing. Ultimately, the method accurately acquires target vibration information and generates trajectory and error maps, providing reliable measurement support for multiple fields.

[0090] While the specific embodiments of the present invention have been described in detail above, these are intended to be exemplary only, and the present invention is not limited thereto. Any equivalent modifications or substitutions to the present invention that would be apparent to those skilled in the art are also within the scope of the present invention. Therefore, any equivalent modifications or substitutions made without departing from the spirit and scope of the present invention are intended to be encompassed within the scope of the present invention.

Claims

1. A carrier-suppressed sinusoidal phase external modulation vibration measurement optical path structure, comprising a target to be measured, characterized in that: The device also includes a laser, a first coupler, a second coupler, an electro-optical phase modulator, a balanced detector and an optical system. The laser is optically connected to the first coupler. The output end of the first coupler is divided into a reference optical path and a measurement optical path. In the reference optical path, the first coupler, the electro-optical phase modulator and the second coupler are optically connected in sequence; in the measurement optical path, the first coupler, the optical system and the second coupler are optically connected in sequence, and the second coupler is optically connected to the balanced detector. A target to be measured is provided on the output light side of the optical system.

2. The carrier-suppressed sinusoidal phase external modulation vibration measurement optical path structure according to claim 1 is characterized in that: a laser, configured to transmit a fixed-frequency optical signal to the first coupler; a first coupler for dividing the optical signal emitted by the laser into reference light and measurement light, wherein 10% of the optical signal enters the reference optical path as the reference light and 90% of the optical signal enters the measurement optical path as the measurement light; An electro-optical phase modulator is used in the reference optical path to modulate the reference light into a high-frequency sinusoidal carrier signal under the action of an external voltage applied by a signal generator; an optical system for emitting the measuring light in the measuring optical path onto the target to be measured so that the measuring light carries the low-frequency vibration information of the target to be measured, and receiving the light reflected from the target to be measured and transmitting it to the second coupler; a second coupler, for coupling the reference light in the reference light path with the measurement light in the measurement light path, and outputting the coupled light to a balanced detector; The balanced detector is used to receive the coupled reference light and measurement light output by the second coupler and generate an interference signal so as to perform subsequent signal processing to obtain target vibration information.

3. The carrier-suppressed sinusoidal phase external modulation vibration measurement optical path structure according to claim 2, characterized in that: The first coupler is connected to the optical system through one core optical path of the dual-core optical fiber, and the optical system is connected to the second coupler through the other core optical path.

4. A carrier-suppressed sinusoidal phase external modulation vibration measurement method, based on the carrier-suppressed sinusoidal phase external modulation vibration measurement optical path structure according to any one of claims 1 to 3, characterized in that: The carrier suppression-based sinusoidal phase external modulation vibration measurement method comprises the following steps: S1. A laser is used to emit a fixed-frequency optical signal, which is then split into reference light and measurement light via a first coupler. 10% of the light, serving as the reference light, is modulated by an electro-optical phase modulator and a voltage applied by a signal generator into a high-frequency sinusoidal carrier signal. 90% of the light, serving as the measurement light, is emitted through an optical system onto the target to be measured and reflected and received. The measurement light carries the target's low-frequency vibration information. The reference and measurement lights are ultimately received by a balanced detector via a second coupler to produce an interference signal. S2. Add a periodic Gaussian window function to the time domain of the interference signal obtained by the balanced detector to intercept the high-frequency part of the interference signal. The frequency of the Gaussian window function is twice the frequency of the interference signal, thereby improving the signal-to-noise ratio of the interference signal. S3. First, the interference signal is expanded using the Euler formula. Then, a time-varying complex carrier function is constructed so that its frequency component matches the carrier frequency component in the interference signal. Then, the interference signal, the Gaussian window function, and the time-varying complex carrier function are multiplied together. Based on the "mixing" principle of signal processing, the carrier frequency component is suppressed, and the phase term containing the target vibration information is converted into a baseband signal. At this time, the signal spectrum contains the baseband signal and a term at twice the carrier frequency. S4. Perform low-pass filtering on the signal processed by S1-S3 to remove the double carrier frequency term to obtain the phase term containing the target vibration information; then solve the phase term to obtain the target vibration information, and obtain the target vibration trajectory diagram and vibration error diagram through simulation.

5. The carrier suppression-based sinusoidal phase external modulation vibration measurement method according to claim 4, characterized in that: In S1, the mathematical expression of the interference signal obtained by the balanced detector is as follows: In the formula, C is the modulation depth, ω m is the modulation frequency, ω0 is the initial angular frequency of the laser, c is the speed of light, d(t) is the vibration trajectory of the target, is the fixed phase difference caused by the optical path difference between the reference light and the measurement light, V, V π are the applied voltage and half-wave voltage of the electro-optic phase modulator respectively.

6. The carrier suppression-based sinusoidal phase external modulation vibration measurement method according to claim 5, characterized in that: In S2, a periodic Gaussian window function is added to the interference signal time domain. The mathematical expression of the Gaussian window function is as follows: Where n is the number of cycles of the window function, σ is the Gaussian parameter, and T m is the modulation period.

7. The carrier suppression-based sinusoidal phase external modulation vibration measurement method according to claim 6, characterized in that: In S3, the interference signal of formula (1) is expanded using the Euler formula to obtain: Construct a time-varying complex carrier function: A(t)=exp[jC A cos(ω m t)] (5) Where C A is the amplitude of the time-varying complex carrier function, let C A =C, and then multiply the interference signal, Gaussian window function, and time-varying complex carrier function to obtain: The spectrum of the signal Q(t) consists of two parts: one is the phase term containing the target vibration information, which is the baseband signal; the other is the double carrier frequency term.

8. The carrier suppression-based sinusoidal phase external modulation vibration measurement method according to claim 7, characterized in that: After low-pass filtering formula (6), the phase term containing the target vibration information is obtained, and then the vibration trajectory d(t) of the target is obtained. Where LPF[g] represents low-pass filtering, real(g) and imag(g) represent the process of taking the real part and imaginary part of the signal, respectively, so as to obtain the vibration information of the target and thus obtain the target vibration trajectory map and vibration error map.

9. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the carrier suppression-based sinusoidal phase external modulation vibration measurement method according to any one of claims 4 to 8 is implemented.

10. A computer device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the carrier-suppressed sinusoidal phase external modulation vibration measurement method according to any one of claims 4 to 8.

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