Multi-parameter sensing method and device

Abstract

The invention relates to the technical field of multi-parameter sensing, in particular to a multi-parameter sensing method and device. The multi-parameter sensing method comprises the following steps: sending detection light; the signals are sent to the coupler; modulating to obtain first detection light and second detection light; the first detection light is sent to the temperature detection module, and the second detection light is sent to the liquid level detection module; the first reflected light and the second reflected light are sent to a hot-wire type optical fiber, sound waves are generated, and the sound waves cause vibration of a quartz tuning fork and are converted into a first piezoelectric current signal and a second piezoelectric current signal; converting into a first voltage signal and a second voltage signal; demodulating the first voltage signal and the second voltage signal; and carrying out inversion on the temperature and the liquid level. According to the multi-parameter sensing method, multiple parameters can be monitored at the same time, and the detection precision can be improved.

Description

Technical Field

[0001] The present application relates to the field of multi-parameter sensing technology, and in particular to a multi-parameter sensing method and device. Background Art

[0002] In many fields such as aviation, petroleum, construction, and safety monitoring, it is necessary to monitor multiple parameters simultaneously. For example, reservoir dams are important engineering measures for regulating the spatial and temporal distribution of water resources and optimizing water resource allocation, and are also an important part of the river flood control engineering system. With the development of water conservancy and hydropower in various countries around the world, the safety issues of reservoir dams have become increasingly prominent. Therefore, the research on multi-parameter monitoring systems that can reflect dam safety has received high attention and importance.

[0003] In the existing multi-parameter monitoring system, multiple electronic sensors are usually used to collect various types of data, such as temperature, liquid level, displacement, pressure and other information. However, the use of electronic sensors to collect data is easily affected by signal interference, and there will be problems such as inaccurate data and delay, which leads to the inability to synchronize the transmission of different types of data, and the inability to ensure that the data from different sensors obtained at the current moment is the same, affecting the accuracy and real-time nature of the data. Fiber optic sensing technology is a high-tech technology that attracts attention in today's world, and it is also an important symbol of the development of contemporary science and technology. Compared with the measurement that traditional electronic sensors are not competent for in extreme environments, especially in the measurement of flammable and explosive, high temperature, high pressure, humidity, strong electromagnetic field, corrosive and other extreme conditions, fiber optic sensing technology highlights technical advantages, but most of the multi-parameter monitoring systems based on fiber optic sensing technology currently have the disadvantages of low detection accuracy and complex structure. Summary of the invention

[0004] The present application provides a multi-parameter sensing method and device to solve the technical problems of low detection accuracy and complex structure in existing multi-parameter monitoring systems.

[0005] The multi-parameter sensing method provided in the first aspect of the present application is applied to a multi-parameter sensing device, and the multi-parameter sensing method includes: a pump laser sends detection light to a circulator; wherein the detection light carries a low-frequency scanning signal; the circulator sends the detection light to a coupler; the coupler sends the detection light to a first acousto-optic modulator and a second acousto-optic modulator for modulation, respectively, to obtain a first detection light and a second detection light; the first acousto-optic modulator sends the first detection light to a temperature detection module, and the second acousto-optic modulator sends the second detection light to a liquid level detection module; wherein the temperature detection module includes a first grating, the liquid level detection module includes a second grating, the bottom of the liquid level detection module is in contact with the liquid surface, and the center wavelengths of the first grating and the second grating are both in the low-frequency scanning range. The circulator sends the first reflected light and the second reflected light to the hot-line optical fiber, the hot-line optical fiber receives the first reflected light and the second reflected light and generates sound waves, the sound waves cause the quartz tuning fork to vibrate, and the quartz tuning fork converts the first reflected light signal in the first reflected light into a first piezoelectric current signal, and converts the second reflected light signal in the second reflected light into a second piezoelectric current signal; wherein the first reflected light is formed by the first detection light being reflected by the first grating, and the second reflected light is formed by the second detection light being reflected by the second grating; the preamplifier converts the first piezoelectric current signal and the second piezoelectric current signal into a first voltage signal and a second voltage signal respectively; and the temperature and the liquid level are inverted according to the first voltage signal and the second voltage signal.

[0006] Optionally, the central wavelength of the first grating changes with temperature; the central wavelength of the second grating changes with the position of the liquid surface; wherein the central wavelengths of the first grating and the second grating are different.

[0007] Optionally, the frequencies of the first AOM and the second AOM are different, and the frequencies of the first AOM and the second AOM are both within the response curve of the quartz tuning fork.

[0008] Optionally, before the pump laser sends the detection light to the circulator, the multi-parameter sensing method further includes: a laser driver sends a driving signal to the pump laser; wherein the driving signal controls the pump laser to send the detection light through temperature and current.

[0009] Optionally, the temperature and liquid level are inverted according to the first voltage signal and the second voltage signal, including: a phase-locked amplifier demodulates the first voltage signal and the second voltage signal respectively; and the temperature and liquid level are inverted according to the demodulated first voltage signal and the demodulated second voltage signal.

[0010] Optionally, the liquid level detection module also includes a shell, a cantilever beam and an elastic diaphragm; wherein the second grating is pasted on the cantilever beam, one end of the cantilever beam is fixed on the top of the shell, and the other end is connected to the elastic diaphragm, the elastic diaphragm is arranged at the bottom of the shell, and the elastic diaphragm is in contact with the liquid surface.

[0011] Optionally, the temperature and liquid level are inverted according to the demodulated first voltage signal and the demodulated second voltage signal, including: inverting the real-time temperature value according to the demodulated first voltage signal; inverting the real-time liquid level value by comparing the demodulated second voltage signal with the initial liquid level signal; wherein the initial liquid level signal is a voltage signal under the initial liquid level state.

[0012] The multi-parameter sensing method provided by the present application controls the laser to emit a low-frequency scanning signal. The low-frequency scanning signal causes the light of different wavelengths output by the laser to have different light intensities. The measured parameter directly or indirectly causes the temperature around the grating or the stress acting on the grating to change. The temperature or stress change will cause the central wavelength of the grating to drift. The grating can reflect the light at the central wavelength. Since the light intensity is different at different wavelengths, the wavelength change of the grating can be converted into the light intensity change. After the light intensity change is converted into a voltage signal, the voltage signal is demodulated using the phase-locked amplification technology that can demodulate weak signals, thereby improving the detection accuracy of the multi-parameter sensing method.

[0013] The multi-parameter sensing device provided in the second aspect of the present application adopts the multi-parameter sensing method provided in the first aspect, and the multi-parameter sensing device includes: a pump laser, configured to send detection light; wherein the detection light carries a low-frequency scanning signal; a circulator, a first end of which is connected to the pump laser and configured to receive the detection light; a coupler, one end of which is connected to the second end of the circulator and configured to receive the detection light transmitted by the circulator; a first acousto-optic modulator and a second acousto-optic modulator, respectively connected to the other end of the coupler, the first acousto-optic modulator is configured to modulate the detection light to obtain the first detection light, and the second acousto-optic modulator is configured to modulate the detection light to obtain the second detection light; a temperature detection module, connected to the first acousto-optic modulator, the temperature detection module includes a first grating; a liquid level detection module, connected to the second acousto-optic modulator, the liquid level detection module includes a shell, a cantilever beam, a second grating and an elastic diaphragm; wherein one end of the cantilever beam is fixed to the shell, and the other end is connected to the elastic diaphragm, the second grating is attached to the cantilever beam, and the first grating and the central wavelength of the second grating are both within the wavelength range of the low-frequency scanning signal; the hot-wire optical fiber is connected to the third end of the circulator, and is configured to receive the first reflected light and the second reflected light and generate sound waves; wherein the first reflected light is formed by the first detection light being reflected by the first grating, and the second reflected light is formed by the second detection light being reflected by the second grating; the quartz tuning fork is close to the hot-wire optical fiber, and is configured to vibrate with the generation of the sound wave, and convert the first reflected light signal in the first reflected light into a first piezoelectric current signal, and convert the second reflected light signal in the second reflected light into a second piezoelectric current signal; the preamplifier is connected to the quartz tuning fork, and is configured to convert the first piezoelectric current signal and the second piezoelectric current signal into a first voltage signal and a second voltage signal, respectively; the phase-locked amplifier is connected to the preamplifier, and is configured to demodulate the first voltage signal and the second voltage signal, respectively; the oscilloscope is connected to the phase-locked amplifier, and is configured to invert the temperature and the liquid level according to the demodulated first voltage signal and the demodulated second voltage signal.

[0014] Optionally, the multi-parameter sensing device further includes: a laser driver connected to the pump laser and configured to send a driving signal to the pump laser; wherein the driving signal controls the pump laser to send detection light through temperature and current.

[0015] Optionally, the central wavelength of the first grating changes with temperature; the central wavelength of the second grating changes with the position of the liquid surface; wherein the central wavelengths of the first grating and the second grating are different.

[0016] The multi-parameter sensing device provided in the second aspect of the present application uses a single light source and a single quartz tuning fork demodulation system to monitor multiple parameters at the same time, has a simple structure, and can effectively reduce the volume of the multi-parameter detection system. During use, the grating wavelength change caused directly or indirectly by the multi-parameter change can be converted into a light intensity change, the hot-wire optical fiber receives the reflected light and generates sound waves, the light intensity change causes the sound wave change, and a single quartz tuning fork is used to demodulate signals of different frequencies, thereby improving the detection accuracy and expanding the application range of the multi-parameter sensing device. The multi-parameter sensing device can be widely used in aviation, petroleum, construction, safety monitoring and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0018] Figure 1 It is a flowchart of a multi-parameter sensing method provided in an embodiment of the present application; Figure 2 is a structural schematic diagram of a multi-parameter sensing device provided in an embodiment of the present application; Figure 3 A grating reflection spectrum and a laser output signal provided in an embodiment of the present application; Figure 4 is the response frequency curve of the quartz tuning fork and the modulation frequency of the acousto-optic modulator provided in the embodiment of the present application; Figure 5 is the relationship between the temperature and the amplitude of the first voltage signal provided in the embodiment of the present application; Figure 6 This is the relationship between the liquid level change and the second voltage signal amplitude provided in the embodiment of the present application.

[0019] Graphic marking: 100-multi-parameter sensing device; 11-pump laser, 12-circulator; 121-first end; 122-second end, 123-third end; 13-coupler; 14-first acousto-optic modulator; 15-second acousto-optic modulator; 16-temperature detection module; 161-first grating; 17-liquid level detection module; 171-second grating; 172-housing; 173-cantilever beam; 174-elastic diaphragm; 18-hot-wire optical fiber; 19-quartz tuning fork; 20-preamplifier; 21-phase-locked amplifier; 22-oscilloscope; 23-laser driver. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described clearly below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments of the present application, other embodiments obtained by ordinary technicians in this field without making creative work all belong to the protection scope of the present application.

[0021] In the following, the terms "first", "second", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0022] In addition, in the present application, directional terms such as "upper", "lower", "inner" and "outer" are defined relative to the orientation of the components schematically placed in the drawings. It should be understood that these directional terms are relative concepts. They are used for relative description and clarification, and they can change accordingly according to the changes in the orientation of the components placed in the drawings.

[0023] The embodiment of the present application provides a multi-parameter sensing method, which is applied in a multi-parameter sensing device. The multi-parameter sensing method uses a single light source and a single quartz tuning fork to achieve simultaneous detection of multiple parameters, simplifies the device structure, and improves the detection accuracy.

[0024] See also Figure 1 and Figure 2 The multi-parameter sensing method provided in the embodiment of the present application is implemented by the following steps S100 to S700.

[0025] Step S100 : the pump laser 11 sends detection light to the circulator 12 .

[0026] The circulator 12 is arranged on the optical path of the detection light emitted by the pump laser 11, and the first end 121 of the circulator 12 is connected to the pump laser 11. The pump laser 11 can be controlled by the laser driver 23 to send the detection light, and the detection light carries a low-frequency scanning signal.

[0027] Step S200 : the circulator 12 sends the detection light to the coupler 13 .

[0028] The second end 122 of the circulator 12 may be connected to the coupler 13 .

[0029] Step S300: the coupler 13 sends the detection light to the first acousto-optic modulator 14 and the second acousto-optic modulator 15 for modulation, respectively, to obtain the first detection light and the second detection light.

[0030] The coupler 13 divides one beam of detection light into two beams to obtain two beams of detection light, and sends the two beams of detection light to the first acousto-optic modulator 14 and the second acousto-optic modulator 15 respectively.

[0031] Step S400 : the first AOM 14 sends the first detection light to the temperature detection module 16 , and the second AOM 15 sends the second detection light to the liquid level detection module 17 ; wherein the temperature detection module 16 includes a first grating 161 , and the liquid level detection module 17 includes a second grating 171 .

[0032] The first acousto-optic modulator 14 is connected to the temperature detection module 16, and the temperature detection module 16 is provided with a first grating 161. The first acousto-optic modulator 14 sends the modulated first detection light to the temperature detection module 16. After the first detection light enters the temperature detection module 16, it will be incident on the first grating 161, and the first grating 161 reflects the first detection light to obtain a first reflected light.

[0033] Since the first grating 161 is used to sense temperature changes, the central wavelength of the first grating 161 can change with the change of temperature, and the change of the central wavelength causes the intensity of the light reflected by the first grating 161 to change. For example, the higher the temperature, the longer the central wavelength of the first grating 161, and the greater the intensity of the first reflected light. The lower the temperature, the shorter the central wavelength of the first grating 161, and the weaker the intensity of the first reflected light.

[0034] The second acousto-optic modulator 15 is connected to the liquid level detection module 17, and a second grating 171 is provided in the liquid level detection module 17. The second acousto-optic modulator 15 sends the modulated second detection light to the liquid level detection module 17. After the second detection light enters the liquid level detection module 17, it will be incident on the second grating 171. The second grating 171 reflects the second detection light to obtain a second reflected light.

[0035] Specifically, the liquid level detection module 17 is disposed in the liquid, and the bottom of the liquid level detection module 17 may be lower than the liquid level surface.

[0036] In a specific implementation, the liquid level detection module 17 may include a housing 172, a cantilever beam 173 disposed in the housing 172, a second grating 171 bonded to the cantilever beam 173, and an elastic diaphragm 174 attached to the bottom of the housing 172. One end of the cantilever beam 173 is fixed to the inner wall at the top of the housing 172, and the other end is connected to the elastic diaphragm 174, which is located at the bottom of the housing 172. The elastic diaphragm 174 can be in contact with the liquid surface and has elasticity. The change in liquid level can cause the elastic diaphragm 174 to deform, and the deformation of the elastic diaphragm 174 drives the cantilever beam 173 to bend, thereby causing the second grating 171 attached to the cantilever beam 173 to be stretched, and the second grating 171 is stretched to cause the central wavelength to change, and the change in the central wavelength causes the light intensity in the light reflected by the second grating 171 to change.

[0037] The extension direction of the second grating 171 may be the same as or perpendicular to the extension direction of the cantilever beam 173. It is only necessary to ensure that the central wavelength of the second grating 171 becomes longer when the cantilever beam 173 changes in length under pressure.

[0038] Among them, since the second grating 171 is used to sense the change of liquid level, the central wavelength of the second grating 171 will also change when the liquid level changes. For example, when the liquid level rises, the pressure on the second grating 171 increases, the longer the central wavelength, the greater the light intensity of the second reflected light. When the liquid level drops, the pressure on the second grating 171 decreases, the central wavelength decreases, and the light intensity of the second reflected light decreases.

[0039] In a specific implementation, the central wavelength of the first grating 161 may be 1550.16 nm, and the central wavelength of the second grating 171 may be 1550.36 nm.

[0040] See also Figure 3 , the laser output signal includes the central wavelengths of the first grating 161 and the second grating 171 .

[0041] Step S500: The circulator 12 sends the first reflected light and the second reflected light to the hot-line optical fiber 18. The hot-line optical fiber 18 can receive the first reflected light and the second reflected light and generate sound waves. The sound waves cause the quartz tuning fork 19 to vibrate. The quartz tuning fork 19 converts the first reflected light signal in the first reflected light into a first piezoelectric current signal, and converts the second reflected light signal in the second reflected light into a second piezoelectric current signal.

[0042] The first reflected light is reflected to the circulator 12 along the first acousto-optic modulator 14 and the coupler 13 in sequence, and the second reflected light is reflected to the circulator 12 along the second acousto-optic modulator 15 and the coupler 13 in sequence. The third end 123 of the circulator 12 is connected to the hot-line optical fiber 18, so that the first reflected light and the second reflected light can be incident on the hot-line optical fiber 18 through the third end 123 of the circulator 12. Due to the thermal effect of the hot-line optical fiber 18 itself, the light energy can be converted into heat energy, so that the surrounding temperature changes periodically, and then the surrounding pressure changes periodically, generating sound waves, causing the vibration of the quartz tuning fork 19. After the quartz tuning fork 19 converts the first reflected light signal carried in the first reflected light into a first piezoelectric current signal and converts the second reflected light signal carried in the second reflected light into a second piezoelectric current signal, the quartz tuning fork 19 sends the first piezoelectric current signal and the second piezoelectric current signal to the preamplifier 20, wherein the output end of the quartz tuning fork 19 is connected to the input end of the preamplifier 20.

[0043] The frequencies of the first AOM 14 and the second AOM 15 are different, and the frequencies of the first AOM 14 and the second AOM 15 are both within the response curve of the quartz tuning fork 19, thereby ensuring the detection accuracy.

[0044] In a specific implementation, see Figure 4 The frequency of the response curve of the quartz tuning fork 19 is greater than 32.65 kHz and less than 32.85 kHz. The frequency of the first AOM 14 can be about 32.744 kHz; the frequency of the second AOM 15 can be about 32.755 kHz.

[0045] Step S600: the preamplifier 20 converts the first piezoelectric current signal and the second piezoelectric current signal into a first voltage signal and a second voltage signal respectively.

[0046] Specifically, the preamplifier 20 can convert the first piezoelectric current signal into a first voltage signal, and can also convert the second piezoelectric current signal into a second voltage signal, to facilitate subsequent calculations.

[0047] Step S700: inverting the temperature and the liquid level according to the first voltage signal and the second voltage signal.

[0048] Specifically, step S700 can be implemented by the following steps S701 and S702.

[0049] Step S701: The lock-in amplifier 21 demodulates the first voltage signal and the second voltage signal respectively.

[0050] The input end of the lock-in amplifier 21 is connected to the output end of the preamplifier 20. The lock-in amplifier 21 can receive the first voltage signal and the second voltage signal transmitted by the preamplifier 20.

[0051] In a specific implementation, the reference frequency of the lock-in amplifier 21 can be 32.744kHz and 32.755kHz, and when demodulating the first voltage signal and the second voltage signal, it can be done by switching between 32.744kHz and 32.755kHz. Of course, different from the above implementation, in another specific implementation, the lock-in amplifier 21 may include a first channel and a second channel, the first channel is used to receive and demodulate the first voltage signal, and the second channel is used to receive and demodulate the second voltage signal.

[0052] Among them, since the intensity of the light incident on the grating is different at different wavelengths, when the central wavelength of the first grating 161 and the second grating 171 changes, the intensity of the light reflected by the first grating 161 and the second grating 171 changes, resulting in a change in the voltage signal demodulated by the lock-in amplifier 21. According to the demodulated voltage signal and by comparing it with the initial signal, it is convenient to calculate the temperature, liquid level and other information at this time. The initial signal can be the signal reflected by the second grating 171 at the initial liquid level.

[0053] Step S702: inverting the temperature and the liquid level according to the demodulated first voltage signal and the demodulated second voltage signal.

[0054] Among them, step S702 can be implemented by the following steps S702a and step S702b.

[0055] Step S702a: Invert the real-time temperature value according to the demodulated first voltage signal.

[0056] Step S702b: Invert the real-time liquid level value by comparing the demodulated second voltage signal with the initial liquid level signal; wherein the initial liquid level signal is a voltage signal under the initial liquid level state.

[0057] There is no specific requirement for the execution order between step S702a and step S702b, and the execution order can be adjusted according to actual circumstances.

[0058] The output end of the lock-in amplifier 21 is connected to the input end of the oscilloscope 22, and the magnitudes of different parameter signals at different times can be observed and recorded on the oscilloscope 22. The temperature can be obtained by inverting the demodulated first voltage signal, and the liquid level information can be obtained by inverting the second voltage signal.

[0059] See also Figure 5It can be seen that the temperature is positively correlated with the signal amplitude of the first voltage signal. In this way, the change trend of the temperature can be seen from the change of the signal amplitude of the first voltage signal.

[0060] See also Figure 6 It can be seen that the liquid level change is positively correlated with the signal amplitude of the second voltage signal. In this way, the change trend of the liquid level change can be seen through the change of the signal amplitude of the second voltage signal.

[0061] In a specific implementation, a multi-parameter sensing method provided in an embodiment of the present application may further include the following steps S001: S001 : The laser driver 23 sends a driving signal to the pump laser 11 .

[0062] The driving signal controls the detection light sent by the pump laser 11 through temperature and current, and the driving signal includes the central wavelengths of the first grating 161 and the second grating 171 .

[0063] Specifically, the laser driver 23 can drive the pump laser 11 to send detection light containing multiple grating center wavelengths, and the wavelength range of the detection light can be 1550nm-1550.5nm. The driving signal can be a low-frequency sawtooth signal with a frequency of 1Hz, so that the detection light controlled by it is also a low-frequency signal.

[0064] The multi-parameter sensing method provided in the embodiment of the present application controls the laser to emit a low-frequency scanning signal. The low-frequency scanning signal causes the light of different wavelengths output by the pump laser 11 to have different light intensities. The measured parameter directly or indirectly causes the temperature around the grating or the stress acting on the grating to change. The temperature or stress change will cause the central wavelength of the grating to drift. The grating can reflect the light at the central wavelength. Since the light intensity is different at different wavelengths, the wavelength change of the grating can be converted into the light intensity change. After the light intensity change is converted into a voltage signal, the voltage signal is demodulated using the phase-locked amplification technology that can demodulate weak signals, thereby improving the detection accuracy of the multi-parameter sensing method.

[0065] Corresponding to the embodiment of the aforementioned multi-parameter sensing method, the present application also provides an embodiment of a multi-parameter sensing device 100. The multi-parameter sensing device 100 includes a pump laser 11, a circulator 12, a coupler 13, a first acousto-optic modulator 14, a second acousto-optic modulator 15, a temperature detection module 16, a liquid level detection module 17, a hot-wire optical fiber 18, a quartz tuning fork 19, a preamplifier 20, a lock-in amplifier 21 and an oscilloscope 22.

[0066] The pump laser 11 is used to emit detection light, wherein the detection light carries a low-frequency scanning signal.

[0067] That is, the pump laser 11 can be used to perform step S100 in the above multi-parameter sensing method embodiment.

[0068] The first end 121 of the circulator 12 is connected to the pump laser 11 , and is used for receiving the detection light sent by the pump laser 11 , and sending the detection light to the coupler 13 .

[0069] That is to say, the circulator 12 can be used to execute step S200 in the above multi-parameter sensing method embodiment.

[0070] One end of the coupler 13 is connected to the second end 122 of the circulator 12, and is used to receive the detection light sent by the circulator 12. The other end of the coupler 13 is connected to the first acousto-optic modulator 14 and the second acousto-optic modulator 15, respectively. The coupler 13 is used to divide the received detection light into two beams, and send them to the first acousto-optic modulator 14 and the second acousto-optic modulator 15 for modulation, respectively, to obtain the first detection light and the second detection light after modulation.

[0071] That is to say, the coupler 13 can be used to perform step S300 in the above multi-parameter sensing method embodiment.

[0072] The first acousto-optic modulator 14 sends the first detection light to the temperature detection module 16 for temperature detection. The temperature detection module 16 includes a first grating 161. After the first detection light is sent to the temperature detection module 16, it will be incident on the first grating 161, and the first grating 161 will reflect the first detection light to form a first reflected light.

[0073] The first grating 161 is used to detect temperature, and the central wavelength of the first grating 161 changes with the change of temperature.

[0074] The second acousto-optic modulator 15 sends the second detection light to the liquid level detection module 17 to detect the liquid level information. Among them, the liquid level detection module 17 includes a housing 172, a cantilever beam 173, a second grating 171 and an elastic diaphragm 174. One end of the cantilever beam 173 is fixed on the housing 172, and the other end is connected to the elastic diaphragm 174. The second grating 171 is attached to the cantilever beam 173, and the elastic diaphragm 174 is arranged at the bottom of the housing 172, and the elastic diaphragm 174 is in contact with the liquid surface. After the second detection light is sent to the liquid level detection module 17, it will be incident on the second grating 171, and the second grating 171 will reflect to form a second reflected light. When the liquid level rises, the pressure acting on the elastic diaphragm 174 increases, causing the cantilever beam 173 to pull the second grating 171, so that the central wavelength of the second grating 171 increases.

[0075] The second grating 171 is used to detect the liquid level, and the central wavelength of the second grating 171 changes with the change of the liquid level. The central wavelengths of the first grating 161 and the second grating 171 are different.

[0076] That is to say, the first AOM 14 and the second AOM 15 can perform step S400 in the above multi-parameter sensing method embodiment.

[0077] The hot-wire optical fiber 18 is connected to the third end 123 of the circulator 12, and is used to receive the first reflected light and the second reflected light returned by the circulator 12 and generate sound waves. Specifically, due to the thermal effect of the hot-wire optical fiber 18 itself, light energy can be converted into heat energy, so that the surrounding temperature changes periodically, and then the surrounding pressure changes periodically, generating sound waves. The quartz tuning fork 19 is close to the hot-wire optical fiber 18. After the hot-wire optical fiber 18 generates sound waves, the quartz tuning fork 19 vibrates with the generation of the sound waves, and converts the first reflected light signal in the first reflected light into a first piezoelectric current signal, and converts the second reflected light signal in the second reflected light into a second piezoelectric current signal.

[0078] That is, the hot-wire optical fiber 18 and the quartz tuning fork 19 can perform step S500 in the above multi-parameter sensing method embodiment.

[0079] The input end of the preamplifier 20 is connected to the output end of the quartz tuning fork 19 , and the preamplifier 20 is used to convert the first piezoelectric current signal transmitted by the quartz tuning fork 19 into a first voltage signal, and convert the second piezoelectric current signal into a second voltage signal.

[0080] That is, the preamplifier 20 can execute step S600 in the above multi-parameter sensing method embodiment.

[0081] An input end of the lock-in amplifier 21 is connected to an output end of the preamplifier 20 and is used to demodulate the first voltage signal and the second voltage signal.

[0082] That is, the lock-in amplifier 21 can execute step S701 in the above parameter sensing method embodiment.

[0083] The input end of the oscilloscope 22 is connected to the output end of the lock-in amplifier 21, and is used to display the demodulated first voltage signal and the demodulated second voltage signal. By comparing the demodulated first voltage signal, the demodulated second voltage signal and the initial liquid level signal, the temperature and the liquid level can be calculated.

[0084] That is, the oscilloscope 22 can execute step S702 in the above multi-parameter sensing method embodiment.

[0085] In some feasible implementations, the multi-parameter sensing device 100 also includes a laser driver 23, which is connected to the pump laser 11 and is used to send a driving signal to the pump laser 11, and the driving signal controls the parameters of the detection light sent by the pump laser 11 through temperature and current, wherein the parameters include wavelength, and the central wavelengths of the first grating 161 and the second grating 171 are both within the wavelength range of the driving signal.

[0086] The multi-parameter sensing device 100 provided in the embodiment of the present application uses a single light source and a single quartz tuning fork 19, can monitor multiple parameters simultaneously, has a simple structure, and can effectively reduce the overall volume. During use, the grating wavelength change caused directly or indirectly by the multi-parameter change can be converted into a light intensity change, the hot-wire optical fiber 18 receives the reflected light and generates sound waves, the light intensity change causes the sound wave change, and a single quartz tuning fork 19 is used to demodulate signals of different frequencies, thereby improving the detection accuracy and expanding the application scope of the multi-parameter sensing device 100. The multi-parameter sensing device 100 can be widely used in aviation, petroleum, construction, safety monitoring and other fields.

[0087] It should be noted that those skilled in the art will easily think of other embodiments of the present application after considering the specification and practicing the application disclosed herein. The present application is intended to cover any variation, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary technical means in the art that are not disclosed in the present application.

[0088] It should be understood that the present application is not limited to the precise construction that has been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof, the true scope being indicated by the present application.

Claims

1. A multi-parameter sensing method, characterized in that: Applied to a multi-parameter sensing device, the multi-parameter sensing method comprises: The pump laser sends detection light to the circulator; wherein the detection light carries a low-frequency scanning signal; The circulator sends the detection light to the coupler; The coupler sends the detection light to the first acousto-optic modulator and the second acousto-optic modulator for modulation respectively, so as to obtain the first detection light and the second detection light; The first acousto-optic modulator sends the first detection light to the temperature detection module, and the second acousto-optic modulator sends the second detection light to the liquid level detection module; wherein the temperature detection module includes a first grating, the liquid level detection module includes a second grating, the bottom of the liquid level detection module is in contact with the liquid surface, and the central wavelengths of the first grating and the second grating are both within the wavelength range of the low-frequency scanning signal; The circulator sends the first reflected light and the second reflected light to the hot-line optical fiber, the hot-line optical fiber receives the first reflected light and the second reflected light and generates sound waves, the sound waves cause the quartz tuning fork to vibrate, and the quartz tuning fork converts the first reflected light signal in the first reflected light into a first piezoelectric current signal, and converts the second reflected light signal in the second reflected light into a second piezoelectric current signal; wherein the first reflected light is formed by the first detection light being reflected by the first grating, and the second reflected light is formed by the second detection light being reflected by the second grating; The preamplifier converts the first piezoelectric current signal and the second piezoelectric current signal into a first voltage signal and a second voltage signal respectively; The temperature and the liquid level are inverted according to the first voltage signal and the second voltage signal.

2. The multi-parameter sensing method according to claim 1, characterized in that: The central wavelength of the first grating changes with temperature; The central wavelength of the second grating changes with the change of the liquid surface position; wherein the central wavelengths of the first grating and the second grating are different.

3. The multi-parameter sensing method according to claim 1, characterized in that: The frequencies of the first AOM and the second AOM are different, and the frequencies of the first AOM and the second AOM are both within the response curve of the quartz tuning fork.

4. The multi-parameter sensing method according to claim 1, characterized in that: Before the pump laser sends the detection light to the circulator, the multi-parameter sensing method further includes: The laser driver sends a driving signal to the pump laser; wherein the driving signal controls the pump laser to send the detection light through temperature and current.

5. The multi-parameter sensing method according to claim 1, characterized in that: Inverting the temperature and the liquid level according to the first voltage signal and the second voltage signal includes: A lock-in amplifier demodulates the first voltage signal and the second voltage signal respectively; The temperature and the liquid level are inverted according to the demodulated first voltage signal and the demodulated second voltage signal.

6. The multi-parameter sensing method according to claim 1, characterized in that: The liquid level detection module also includes a shell, a cantilever beam and an elastic diaphragm; wherein the second grating is pasted on the cantilever beam, one end of the cantilever beam is fixed to the top of the shell, and the other end is connected to the elastic diaphragm, the elastic diaphragm is arranged at the bottom of the shell, and the elastic diaphragm is in contact with the liquid surface.

7. The multi-parameter sensing method according to claim 5, characterized in that: Inverting the temperature and the liquid level according to the demodulated first voltage signal and the demodulated second voltage signal, comprising: Inverting a real-time temperature value according to the demodulated first voltage signal; The real-time liquid level value is inverted by comparing the demodulated second voltage signal with the initial liquid level signal; wherein the initial liquid level signal is a voltage signal under the initial liquid level state.

8. A multi-parameter sensing device, characterized in that: The multi-parameter sensing method according to any one of claims 1 to 7 is adopted, wherein the multi-parameter sensing device comprises: A pump laser is configured to send a detection light; wherein the detection light carries a low-frequency scanning signal; a circulator, a first end of which is connected to the pump laser and configured to receive the detection light; a coupler, one end of which is connected to the second end of the circulator and configured to receive the detection light transmitted by the circulator; A first acousto-optic modulator and a second acousto-optic modulator are respectively connected to the other end of the coupler, the first acousto-optic modulator is configured to modulate the detection light to obtain a first detection light, and the second acousto-optic modulator is configured to modulate the detection light to obtain a second detection light; A temperature detection module connected to the first acousto-optic modulator, wherein the temperature detection module comprises a first grating; A liquid level detection module is connected to the second acousto-optic modulator, and the liquid level detection module includes a housing, a cantilever beam, a second grating and an elastic diaphragm; wherein one end of the cantilever beam is fixed to the housing, and the other end is connected to the elastic diaphragm, the second grating is attached to the cantilever beam, and the central wavelengths of the first grating and the second grating are both within the wavelength range of the low-frequency scanning signal; a hot-wire optical fiber connected to the third end of the circulator, configured to receive the first reflected light and the second reflected light and generate an acoustic wave; wherein the first reflected light is formed by the first detection light being reflected by the first grating, and the second reflected light is formed by the second detection light being reflected by the second grating; a quartz tuning fork, close to the hot-wire optical fiber, configured to vibrate with the generation of the sound wave, and convert a first reflected light signal in the first reflected light into a first piezoelectric current signal, and convert a second reflected light signal in the second reflected light into a second piezoelectric current signal; a preamplifier connected to the quartz tuning fork and configured to convert the first piezoelectric current signal and the second piezoelectric current signal into a first voltage signal and a second voltage signal, respectively; a lock-in amplifier, connected to the preamplifier, and configured to demodulate the first voltage signal and the second voltage signal respectively; An oscilloscope is connected to the lock-in amplifier and is configured to invert the temperature and the liquid level according to the demodulated first voltage signal and the demodulated second voltage signal.

9. The multi-parameter sensing device according to claim 8, characterized in that: The multi-parameter sensing device also includes: A laser driver is connected to the pump laser and is configured to send a driving signal to the pump laser; wherein the driving signal controls the pump laser to send the detection light through temperature and current.

10. The multi-parameter sensing device according to claim 9, characterized in that: The central wavelength of the first grating changes with temperature; The central wavelength of the second grating changes with the change of the liquid surface position; wherein the central wavelengths of the first grating and the second grating are different.

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