CN114152327B - Vibration detection method based on cavity ring-down technology - Google Patents
Vibration detection method based on cavity ring-down technology Download PDFInfo
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- CN114152327B CN114152327B CN202111518691.0A CN202111518691A CN114152327B CN 114152327 B CN114152327 B CN 114152327B CN 202111518691 A CN202111518691 A CN 202111518691A CN 114152327 B CN114152327 B CN 114152327B
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- 238000001514 detection method Methods 0.000 title claims abstract description 40
- 238000005516 engineering process Methods 0.000 title claims abstract description 26
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- 230000003287 optical effect Effects 0.000 claims abstract description 38
- 238000001228 spectrum Methods 0.000 claims abstract description 25
- 230000007613 environmental effect Effects 0.000 claims abstract description 10
- 238000012544 monitoring process Methods 0.000 claims abstract description 10
- 238000012545 processing Methods 0.000 claims description 8
- 238000004458 analytical method Methods 0.000 claims description 5
- 230000005540 biological transmission Effects 0.000 claims description 5
- 238000011896 sensitive detection Methods 0.000 claims description 5
- 230000000737 periodic effect Effects 0.000 claims description 4
- 238000005311 autocorrelation function Methods 0.000 claims description 3
- 238000010586 diagram Methods 0.000 claims description 3
- 238000004364 calculation method Methods 0.000 claims description 2
- 238000012512 characterization method Methods 0.000 claims description 2
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- 230000001052 transient effect Effects 0.000 abstract description 6
- 238000011897 real-time detection Methods 0.000 abstract description 2
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- 239000009759 San-Chi Substances 0.000 description 1
- 238000000862 absorption spectrum Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000000180 cavity ring-down spectroscopy Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
Abstract
The invention provides a vibration detection method based on an optical cavity ring-down technology, which comprises the following steps: setting up a ring-down cavity structure, adjusting the ring-down cavity to output a stable optical cavity output signal with certain intensity, monitoring the change dynamics of the optical cavity output signal, collecting the optical cavity output signal, analyzing and extracting environmental vibration information by using a signal vibration resolving method, outputting a vibration detection result, and realizing high-sensitivity detection of the environmental vibration information. The method is based on the optical cavity ring-down system for detecting the environmental vibration, and can rapidly and qualitatively judge the vibration type and quantitatively obtain information such as vibration frequency spectrum and the like through monitoring and analyzing the optical cavity output signal, so that the real-time detection of transient micro-vibration can be realized.
Description
Technical Field
The invention relates to the field of vibration signal detection, in particular to a vibration detection method based on an optical cavity ring-down technology.
Background
Vibration signal detection is increasingly important in the fields of geological disaster prevention, engineering structure monitoring, experimental environment vibration detection and the like, but the conventional vibration sensor has more problems, such as poor detection precision and low sensitivity in a mechanical detection method, large influence of a light source on a distributed sensor, complex detection and monitoring structure system and the like. The Cavity ring-down (CRD) technology is a high-sensitivity and high-precision optical detection technology, and is widely applied to the fields of absorption spectrum measurement, high-reflectivity measurement, optical fiber sensing and the like. (Abhijit Maity, sanchi Maithani, manik Pradhan, "Cavity Ring-Down Spectroscopy: recent Technological Advancements, techniques, and Applications", analytical Chemistry,2021, 93, 388-416; licheng, yuan, review of Cavity Ring-down high reflectance measurement Techniques, laser and optoelectronics progress, 2010, 47:021203). The high sensitivity and high definition characteristics of the cavity ring-down technology can also play a certain value in the field of vibration signal detection. Based on early experimental observation and theoretical research, the invention provides a vibration detection method based on an optical cavity ring-down technology. The theoretical basis of the method is as follows: in a vibration detection system based on the optical cavity ring-down technology, the environment micro-vibration can cause transient micro-detuning of the ring-down cavity system, so that the cavity loss is slightly changed, and finally, the vibration information is amplified and displayed in an optical cavity resonance output signal. Because the cavity ring-down signal is extremely sensitive to cavity loss change caused by fine cavity imbalance, and the environment vibration is extremely easy to cause disturbance of the cavity imbalance of the ring-down cavity, the sensitive detection of the environment vibration information can be realized based on the cavity ring-down technology.
Once the vibration detection system based on the ring-down cavity structure is built, the whole ring-down cavity structure can be used as a sensor to comprehensively sense the environmental vibration. In addition, the method can rapidly and qualitatively judge the vibration type and quantitatively obtain information such as vibration frequency spectrum and the like through real-time monitoring and analysis processing of the ring-down output signal of the optical cavity, and realizes high-sensitivity detection of transient micro-vibration.
Disclosure of Invention
The invention aims to solve the technical problems that: the conventional vibration sensor in the field of vibration signal detection has the problems of poor detection precision, low sensitivity, complex detection monitoring structure system and the like, and a vibration detection method with simple and novel structure and high detection precision and sensitivity is required.
The technical scheme adopted for solving the technical problems is as follows: a vibration detection method based on an optical cavity ring-down technology is provided, and a vibration detection system based on the optical cavity ring-down technology is established. Firstly, a ring-down cavity is built, the ring-down cavity is regulated to output a stable optical cavity output signal with certain intensity, the change dynamics of the optical cavity output signal is monitored, the optical cavity output signal is collected, the environmental vibration information is analyzed and extracted by using a signal vibration resolving method, a vibration detection result is output, and the high-sensitivity and high-precision detection of the environmental vibration information is realized.
The specific implementation steps are as follows:
and (1) constructing a ring-down cavity structure, and monitoring a ring-down cavity transmission signal by using a Photoelectric Detector (PD).
The ring-down cavity structure is various ring-down cavity system structures, including traditional ring-down cavity structures, on-chip or chip microcavity structures and the like, and the adopted ring-down Cavity (CRD) technology comprises a pulse ring-down cavity technology (P-CRD), a phase-shift ring-down cavity technology (PS-CRD), a narrow-spectrum continuous ring-down cavity technology (NBCW-CRD), an optical feedback ring-down cavity technology (OF-CRD) and the like.
And (2) adjusting the ring-down cavity to form a stable cavity resonance output signal, collecting the cavity output signal and obtaining signal spectrum information.
The cavity adjustment stage process does not have specific requirements on cavity imbalance states, and certain cavity imbalance amounts such as cavity mirror inclination or cavity axis offset can exist, so long as the adjusted optical cavity resonance output signals are stable.
The resonant output signal of the optical cavity is a relevant characterization parameter which directly or indirectly reflects the cavity loss, such as an optical cavity ring-down curve, a ring-down cavity transmitted light intensity signal, a ring-down cavity transmitted light spot form, a ring-down cavity transmitted spectrum and the like. The cavity adjusting result requires stable resonant output signals of the optical cavity, and reduces the influence of vibration errors caused by factors of the system.
And (3) processing and analyzing the signal spectrum information by using a signal vibration resolving method, extracting the environment vibration information, outputting a vibration detection result, and finishing the sensitive detection of the environment vibration information.
The signal vibration resolving method can be any spectrum resolving analysis algorithm, including a periodic chart method, an autocorrelation function method, a maximum entropy estimating method and the like. And modified periodogram methods include Bartlett and Welch method spectral estimation.
The vibration detection results include vibration type, vibration frequency, vibration intensity, vibration duration, and the like.
The principle of the invention is as follows: in a vibration detection system based on the optical cavity ring-down technology, the environment micro-vibration can cause transient micro-detuning of the ring-down cavity system, so that the cavity loss is slightly changed, and finally, the vibration information is amplified and displayed in an optical cavity resonance output signal. Because the cavity ring-down signal is extremely sensitive to cavity loss change caused by fine cavity imbalance, and the environment vibration is extremely easy to cause disturbance of the cavity imbalance of the ring-down cavity, the sensitive detection of the environment vibration information can be realized based on the cavity ring-down technology.
Compared with the prior art, the invention has the following advantages: the method can rapidly and qualitatively judge the vibration type and quantitatively obtain information such as vibration frequency spectrum and the like through monitoring and analyzing the output signals of the optical cavity, and can realize real-time detection of transient micro-vibration.
Drawings
FIG. 1 is a schematic diagram of an optical cavity ring-down system according to the present invention;
FIG. 2 is a graph of the optical cavity output signal for the present invention without environmental vibrations;
FIG. 3 is a graph of the optical cavity output signal in the presence of an environmental transient micro-vibration of the present invention.
Detailed Description
The invention is further described below with reference to the drawings and detailed description.
As shown in fig. 1, a specific implementation method of the vibration detection method based on the cavity ring-down technology of the present invention is as follows:
and (1) constructing a traditional two-cavity mirror straight ring-down cavity structure, and adding a Photoelectric Detector (PD) at the tail end of the ring-down cavity, wherein the PD is used for monitoring a transmitted light intensity signal of the ring-down cavity.
Wherein the cavity mirror M1 and the cavity mirror M2 are concave high-reflection mirrors, and the curvature radius of the concave surfaces is 1M. The cavity length is 0.6m, and the stable cavity condition is satisfied. The laser beam is injected into the ring down cavity coaxially with the ring down cavity. The Photodetector (PD) receives the transmitted beam ring down signal of the cavity mirror M2. In this embodiment, the laser source is a continuous semiconductor laser with a center wavelength OF 635nm, and the cavity ring-down technique is an optical feedback cavity ring-down technique (OF-CRD).
And (2) adjusting the ring-down cavity to form a stable ring-down output signal of the optical cavity, wherein the ring-down signal is acquired and transmitted to a computer (PC) for analysis and processing by a data acquisition card (M2i.3010, 80MHz, spectrum) to acquire signal spectrum information. Because the formation of optical cavity resonance in the optical cavity ring-down system is not particularly sensitive to cavity detuning states, the cavity tuning standard can be properly relaxed in the embodiment, and certain cavity detuning amounts such as cavity mirror inclination and the like can exist in the cavity tuning process. The resonant output signal of the optical cavity in the embodiment is a ring-down cavity transmission light intensity signal, and the acquisition time is 20ms.
And (3) processing and analyzing signal spectrum information by utilizing any spectrum resolving analysis algorithm such as a periodic chart method, an autocorrelation function method, a maximum entropy estimation method and the like, extracting environment vibration information, outputting vibration detection results such as vibration type, vibration frequency, vibration intensity, vibration duration and the like, and finishing sensitive detection of the environment vibration information. In this embodiment, the signal vibration calculation method is an improved periodogram Welch method, and the signal vibration region point data x is first calculated N (n) dividing into L segments, processing, each segment having length M, overlapping data between segments, and recording power spectrum of each segment as In->Is a normalization factor and d (n) is a window function. Then, the power spectrum estimation obtained by the periodic graph method in the L-section signal vibration area is summed and averaged to obtain the whole signal vibration area x N The power spectrum of (n) is estimated as +.>The window function for each piece of data processing in this embodiment is a rectangular window function. And finally, analyzing environmental vibration information such as vibration frequency, vibration intensity, vibration duration and the like from the obtained power spectrum estimation diagram.
What is not described in detail in the present specification belongs to the prior art known to those skilled in the art.
Claims (6)
1. The vibration detection method based on the cavity ring-down technology is characterized by comprising the following implementation steps:
step (1), constructing a ring-down cavity structure, and monitoring a ring-down cavity transmission signal by using a Photoelectric Detector (PD);
step (2), adjusting the ring-down cavity to form a stable cavity resonance output signal, and collecting the cavity output signal to obtain signal spectrum information;
step (3), processing and analyzing signal spectrum information by using a signal vibration resolving method, extracting environment vibration information, outputting a vibration detection result, and finishing sensitive detection of the environment vibration information;
the adopted signal vibration calculation method is an improved periodogram Welch method, and firstly, the signal vibration region point data x is calculated N (n) dividing into L segments, processing, each segment having length M, overlapping data between segments, and recording power spectrum of each segment as In->Is a normalization factor, d (n) is a window function, and then the power spectrum estimation obtained by a periodic graph method of the L-section signal vibration region is summed and averaged to obtain the whole signal vibration region x N The power spectrum of (n) is estimated as +.>And finally, analyzing the vibration frequency, the vibration intensity and the vibration duration environmental vibration information from the obtained power spectrum estimation diagram.
2. The vibration detection method based on the cavity ring-down technique according to claim 1, wherein: the ring-down cavity structure in the step (1) is various cavity ring-down system structures, including a traditional ring-down cavity structure, an on-chip or chip microcavity structure, and the cavity ring-down (CRD) technology adopted comprises a pulse cavity ring-down technology (P-CRD), a phase-shift cavity ring-down technology (PS-CRD), a narrow-spectrum continuous cavity ring-down technology (NBCW-CRD) and an optical feedback cavity ring-down technology (OF-CRD).
3. The vibration detection method based on the cavity ring-down technique according to claim 1, wherein: the cavity adjustment stage process in the step (2) does not have specific requirements on the cavity imbalance state, and a certain cavity imbalance amount can exist, including cavity mirror inclination and cavity axis offset, as long as the adjusted resonant output signal of the optical cavity is stable.
4. The vibration detection method based on the cavity ring-down technique according to claim 1, wherein: the resonant output signal of the optical cavity in the step (2) is a relevant characterization parameter which directly or indirectly reflects the cavity loss, and comprises an optical cavity ring-down curve, a ring-down cavity transmission light intensity signal, a ring-down cavity transmission light spot form, a ring-down cavity transmission spectrum and a cavity adjustment result, wherein the resonant output signal of the optical cavity is required to be stable, and the influence of vibration errors caused by factors of the system is reduced.
5. The vibration detection method based on the cavity ring-down technique according to claim 1, wherein: the signal vibration resolving method in the step (3) can be any spectrum resolving analysis algorithm, including a periodogram method, an autocorrelation function method, a maximum entropy estimating method, and a modified periodogram method including Bartlett method and Welch method spectrum estimation.
6. The vibration detection method based on the cavity ring-down technique according to claim 1, wherein: the vibration detection result in the step (3) comprises vibration type, vibration frequency, vibration intensity and vibration duration.
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| CN114720402A (en) * | 2022-03-31 | 2022-07-08 | 中国科学院光电技术研究所 | Calibration device for composite sensing passive cavity |
| CN114719953A (en) * | 2022-03-31 | 2022-07-08 | 中国科学院光电技术研究所 | Straight cavity vibration detection device |
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