A high-frequency microphone system and its operating point control method

Abstract

The present application discloses a high-frequency microphone system and a method for controlling its operating point. The system includes a sensing probe, an optical fiber interferometer, a photoelectric conversion module, an interference signal demodulation module, a light source compensation module, and a synchronization module. The optical fiber interferometer includes a scanning light source, a tunable light source, a beam combiner, a circulator, and a wavelength division multiplexer. The system includes a sensing optical path and a feedback optical path. Sensing optical path: The tunable light source emits a first light beam, which passes through the circulator and reaches the sensing probe. The acoustic signal is modulated onto the first light beam to obtain a modulated signal, which passes through the circulator and is converted into a first electrical signal by the photoelectric conversion module. The first electrical signal is input to the interference signal demodulation module to demodulate the acoustic signal and input it to the synchronization module to obtain the target acoustic signal. Feedback optical path: The scanning light source emits a second light beam, which passes through the circulator and reaches the sensing probe. After the second light beam interferes, it passes through the circulator and is converted into a second electrical signal by the photoelectric conversion module. The second electrical signal is input to the light source compensation module to generate a compensation light beam, which is injected into the interferometer to adjust the operating point.

Description

Technical Field

[0001] The present invention mainly relates to fiber optic acoustic sensing technology, and particularly to a high-frequency microphone system and a method for controlling its operating point. Background Art

[0002] As one of the most common tools for collecting sound signals in people's daily lives, since the invention of the microphone, after decades of development, with the technology of traditional electrical microphones becoming increasingly perfect and mature, microphones are no longer limited to the past application fields and have begun to undertake various new applications such as acoustic sensing, speech recognition, sonar detection, ultrasonic non-destructive testing, etc., and play an important role in fields such as people's livelihood, scientific research, medical treatment, and industry.

[0003] Traditional microphones convert acoustic wave vibrations into electrical signals based on the characteristics of coupling materials. Such microphones have certain limitations, such as low sensitivity, narrow frequency band, susceptibility to interference, easy introduction of noise, and poor confidentiality. In addition, in some complex environments, such as the strong magnetic field of nuclear magnetic resonance instruments and underwater environments, traditional electrical microphones cannot be used.

[0004] Therefore, how to design a microphone system with high sensitivity, large bandwidth, adaptable to complex environments, not easily interfered with, and good noise confidentiality is a technical problem to be solved. Summary of the Invention

[0005] Based on this, it is necessary to provide a high-frequency microphone system and a method for controlling its operating point in view of the problems of the prior art.

[0006] In a first aspect, an embodiment of the present application provides a high-frequency microphone system, including a sensing probe 1, an optical fiber interferometer 2, a photoelectric conversion module 3, an interference signal demodulation module 4, a light source compensation module 5, and a synchronization module 6; the optical fiber interferometer 2 includes a scanning light source 21, a tunable light source 22, a beam combiner 23, a circulator 24, and a wavelength division multiplexer 25;

[0007] The high-frequency microphone system includes a sensing optical path and a feedback optical path;

[0008] Among them, the sensing optical path is as follows: the tunable light source 22 emits a first light beam, the first light beam reaches the sensing probe 1 after passing through the circulator 24, the sensing probe 1 is used to modulate the collected acoustic signal onto the first light beam to obtain a modulated signal, the modulated signal reaches the photoelectric conversion module 3 through the circulator 24 and is converted into a first electrical signal, the first electrical signal is input to the interference signal demodulation module 4 to demodulate the acoustic signal, and the demodulated acoustic signal is input to the synchronization module 6 to output a target acoustic signal;

[0009] Among them, the feedback optical path is as follows: The scanning light source 21 emits a second light beam. The second light beam reaches the sensing probe 1 after passing through the circulator 24. After the second light beam interferes in the sensing probe 1, it reaches the photoelectric conversion module 3 through the circulator 24 and is converted into a second electrical signal. The second electrical signal is input into the light source compensation module 5 to generate a compensation light beam, and the compensation light beam is injected into the fiber optic interferometer 2 to adjust the operating point of the high-frequency microphone system.

[0010] Preferably, the sensing probe 1 is a high-reflectivity F-P cavity, including two high-reflectivity mirrors.

[0011] Preferably, the fiber optic interferometer 2 is a fiber optic F-P interferometer.

[0012] Preferably, the sensing probe 1 is used to modulate the collected acoustic signal onto the first light beam to obtain a first modulation signal, including:

[0013] The sensing probe 1 acquires an external acoustic signal. The acoustic signal causes a change in the air refractive index in the high-reflectivity F-P cavity, resulting in a change in the phase of the first light beam. Then, interference occurs in the sensing probe 1 to form a first modulation signal.

[0014] Preferably, the photoelectric conversion module includes a first photodetector and a second photodetector.

[0015] Preferably, both the first electrical signal and the second electrical signal are analog electrical signals.

[0016] In a second aspect, an embodiment of the present application provides a method for controlling the operating point of a high-frequency microphone system as described in the first aspect, including the following steps:

[0017] S1: Control the scanning light source 21 to perform wavelength scanning within a frequency band range, and collect the output light intensity of the light beam passing through the sensing probe 1;

[0018] S2: Based on the correspondence between the scanning wavelength of the scanning light source 21 and the output light intensity, obtain the actual operating point wavelength of the sensing probe 1;

[0019] S3: Based on the actual operating point wavelength and the initial calibrated operating point wavelength, obtain the wavelength deviation of the sensor operating point;

[0020] S4: Based on the wavelength deviation, configure the frequency band range of the tunable light source 22 so that the high-frequency microphone system is always at the operating point.

[0021] Preferably, step S2 includes:

[0022] S21: Based on the correspondence between the scanning wavelength of the scanning light source 21 and the output light intensity, plot the reflection spectrum of the high-reflectivity F-P cavity;

[0023] S22: Determine all maximum points of the reflection spectrum of the high-reflectivity F-P cavity;

[0024] S23: Obtain the wavelengths corresponding to all maximum points at 75% output optical intensity, and obtain multiple intermediate wavelengths;

[0025] S24: Take the mean value of the multiple intermediate wavelengths as the actual working point wavelength of the sensing probe 1.

[0026] Compared with the prior art, the high-frequency optical microphone of the present invention directly uses a light beam to detect the change in air refractive index caused by sound waves to achieve dynamic detection of sound waves. Based on intensity demodulation technology, it converts the change in interference spectrum intensity into a voltage signal for demodulation, and has the advantages of fast demodulation speed, good real-time dynamics, simple system, high sensitivity, etc., and has the following beneficial effects:

[0027] (1) High-sensitivity F-P cavity acoustic wave sensing

[0028] The high-sensitivity F-P cavity is composed of two high-reflectivity surfaces, forming an optical resonant cavity. When a sound wave enters the cavity, it will cause a change in the air refractive index between the mirrors, thereby changing the phase of the output light. The change in the intensity of the output light is related to the frequency and intensity of the sound wave. A systematic mathematical model is established for the high-reflectivity F-P cavity for acoustic sensing, and the design of the F-P cavity can be completed quickly and in detail according to requirements.

[0029] (2) Dynamic negative feedback intensity interference demodulation

[0030] By dynamically adjusting the working state of the interferometer, the sensitivity of the sensor is maintained at the maximum and unchanged, so as to track the changes caused by sound waves in real time. A wavelength-division dual-path interference system is adopted, one path is used for acoustic wave detection, and the other path is used for working point adjustment. Combining a high-speed signal processing board and PID negative feedback software control constitutes a dynamic negative feedback system to ensure the effective extraction of interference signals in a rapidly changing acoustic wave environment.

[0031] (3) High-speed acoustic wave signal processing

[0032] The demodulation performance of high-speed acoustic wave signals mainly depends on the suppression of phase noise. The phase noise of active devices in the whole system will be superimposed on the finally output acoustic signal. By establishing a systematic noise transfer model and combining techniques such as differential signal suppression of high-speed demodulation boards and noise suppression of optical active devices, the background noise of the high-frequency optical microphone instrument is effectively controlled, and the signal-to-noise ratio of the output signal is improved. Description of the Drawings

[0033] The exemplary embodiments of the present invention can be more fully understood by referring to the accompanying drawings below. The drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. They are used together with the embodiments of the present application to explain the present invention and do not constitute a limitation to the present invention. In the drawings, the same reference numerals generally represent the same components or steps.

[0034] Figure 1 Schematic structural diagram of a high-frequency microphone system provided by an embodiment of the present application;

[0035] Figure 2 Schematic working principle diagram of a sensing probe provided by an embodiment of the present application;

[0036] Figure 3 Schematic structural diagram of an optical fiber interferometer provided by an embodiment of the present application;

[0037] Figure 4 Flowchart of a working point control method for a high-frequency microphone system provided by an embodiment of the present application;

[0038] Figure 5 Schematic diagram of working point control of a high-frequency microphone system provided by an embodiment of the present application;

[0039] Figure 6 Schematic working principle diagram of working point control of a high-frequency microphone system provided by an embodiment of the present application.

[0040] Reference numerals

[0041] 1 - Sensing probe, 2 - Optical fiber interferometer, 3 - Photoelectric conversion module, 4 - Interference signal demodulation module, 5 - Light source compensation module, 6 - Synchronization module, 21 - Scanning light source, 22 - Tunable light source, 23 - Beam combiner, 24 - Circulator, 25 - Wavelength division multiplexer. Detailed implementation manners

[0042] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art.

[0043] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0044] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0045] Example 1

[0046] Reference Figure 1 This embodiment discloses a high-frequency microphone system, including a sensor probe 1 and a demodulator, wherein the main body of the demodulator includes a fiber interferometer 2, a photoelectric conversion module 3, an interference signal demodulation module 4, a light source compensation module 5, and a synchronization module 6; the demodulator also includes a power supply, an interface and a device control module.

[0047] Specifically, the sensing probe 1 is a high reflectivity FP cavity, including two high reflectivity mirrors to form an optical resonant cavity. Figure 2 The working principle of the sensor probe of the present application is given. An FP cavity is formed between two reflecting surfaces. The refractive index of the air in the cavity changes under the pressure or pressure of the outside world, which is equivalent to the change of the optical path of the light in the FP cavity. In this way, the size of the external sound wave can be obtained by demodulating the optical path of the FP. When the sound wave enters the cavity, it will cause the change of the refractive index of the air between the reflectors, thereby changing the intensity of the output light. The present invention realizes the detection of sound signals based on the small change of the refractive index of the air caused by the FP cavity detecting the sound wave.

[0048] Reference Figure 3, the fiber optic interferometer 2 of the present application is a fiber optic F-P interferometer, including a scanning light source 21, a tunable light source 22, a beam combiner 23, a circulator 24, and a wavelength division multiplexer (i.e., WDM) 25. The fiber optic interferometer 2 is based on the structure of a classical fiber optic F-P interferometer. Using wavelength division multiplexing technology, the light of two light sources with different wavelengths is coupled into the optical fiber and combined, and then reaches the sensing probe through the circulator. The reflected light of the sensing probe is wave-division split by the WDM 25 after passing through the fiber optic circulator, and then enters different photodetectors. The scanning light source 21 continuously outputs laser with changing wavelengths for real-time scanning of the reflection spectrum of the F-P cavity. The tunable light source 22 outputs narrow linewidth laser, and its wavelength range can be 1528 - 1532 nm, which is used for sensing the refractive index change of the F-P cavity. The beam combiner and the WDM are used for wavelength combining and splitting of the two light sources respectively, and the circulator plays the role of optical path conversion in the optical path. The wavelengths of the two light sources in this embodiment belong to the C band and can both be transmitted in a wavelength division multiplexing system composed of single-mode fiber optic devices without crosstalk.

[0049] Specifically, the photoelectric conversion module 3 includes a first photodetector and a second photodetector.

[0050] Specifically, the interference signal demodulation module 4 demodulates the sound signal from the first interference electrical signal. In a preferred embodiment, the interference signal demodulation module 4 can be a structure with a ZYQN main control chip as the core, and its peripherals are equipped with peripherals such as AD, DA, network ports, serial ports, and IO ports to implement functions such as photoelectric conversion, digital-to-analog conversion, analog-to-digital conversion, communication, and control.

[0051] Among them, the device control module realizes the control of internal active devices. The power supply supplies power to internal devices. The interface module realizes communication with the outside.

[0052] The high-frequency microphone system of this embodiment includes a sensing optical path and a feedback optical path:

[0053] (1) The sensing optical path is as follows: The tunable light source 22 emits a first light beam. The first light beam reaches the sensing probe 1 after passing through the circulator 24. The sensing probe 1 is used to modulate the collected acoustic signal onto the first light beam to obtain a modulated signal. The modulated signal reaches the photoelectric conversion module 3 through the circulator 24 and is converted into a first electrical signal. The first electrical signal is input to the interference signal demodulation module 4 to demodulate the acoustic signal, and the demodulated acoustic signal is input to the synchronization module 6 to obtain the target acoustic signal; when the system operates at the Q point, within the centered on the Q point, the acoustic signal is proportional to the light intensity. Therefore, in the acoustic signal demodulation module of this system, only by dividing the collected light intensity by a coefficient can the acoustic phase signal be obtained.

[0054] (2) The feedback optical path is as follows: The scanning light source 21 emits a second light beam. After passing through the circulator 24, the second light beam reaches the sensing probe 1. After interference occurs in the sensing probe 1, the second light beam passes through the circulator 24 and reaches the photoelectric conversion module 3, where it is converted into a second electrical signal. The second electrical signal is input into the light source compensation module 5 to generate a compensation light beam, and the compensation light beam is injected into the fiber optic interferometer 2 to adjust the operating point of the high-frequency microphone system.

[0055] Compared with the prior art, the high-frequency optical microphone of the present invention directly uses a light beam to detect the change in air refractive index caused by sound waves to achieve dynamic detection of sound waves. Based on the intensity demodulation technology, it converts the change in interference spectrum intensity into a voltage signal for demodulation, and has the advantages of fast demodulation speed, good real-time dynamics, simple system, high sensitivity, etc., and has the following effective effects:

[0056] (1) High-sensitivity F-P cavity acoustic wave sensing

[0057] The high-sensitivity F-P cavity is composed of two high-interference-reflectivity mirror surfaces, forming an optical resonant cavity. When a sound wave enters the cavity, it causes a change in the air refractive index between the mirrors, thereby changing the phase of the output light. The change in the intensity of the output light is related to the frequency and intensity of the sound wave. A systematic mathematical model is established for the high-reflectivity F-P cavity for acoustic sensing, and the design of the F-P cavity can be completed quickly and in detail according to requirements.

[0058] (2) Dynamic negative feedback intensity interference demodulation

[0059] By dynamically adjusting the operating state of the interferometer, the sensitivity of the sensor is maintained at the maximum and unchanged, so as to track the changes caused by sound waves in real time. A wavelength-division dual-path interference system is adopted, one path is used for acoustic wave detection, and the other path is used for operating point adjustment. Combining a high-speed signal processing board and PID negative feedback software control constitutes a dynamic negative feedback system to ensure the effective extraction of interference signals in a rapidly changing acoustic wave environment.

[0060] (3) High-speed acoustic wave signal processing

[0061] The demodulation performance of high-speed acoustic wave signals mainly depends on the suppression of phase noise. The phase noise of active devices in the entire system will be superimposed on the finally output acoustic signal. By establishing a systematic noise transfer model and combining technologies such as differential signal suppression of high-speed demodulation boards and noise suppression of optical active devices, the background noise of the high-frequency optical microphone instrument is effectively controlled, and the signal-to-noise ratio of the output signal is improved.

[0062] Embodiment 2

[0063] Based on the above embodiment, referring to Figure 4 , this embodiment provides a method for controlling the operating point of a high-frequency microphone, including the following steps:

[0064] S1: Control the scanning light source 21 to perform wavelength scanning within the frequency band range, and collect the output light intensity of the light beam passing through the sensing probe 1;

[0065] S2: Based on the correspondence between the scanning wavelength of the scanning light source 21 and the output light intensity, obtain the actual operating point wavelength of the sensing probe 1;

[0066] S3: Based on the actual operating point wavelength and the initial calibrated operating point wavelength, obtain the wavelength deviation of the sensor operating point;

[0067] S4: Configure the frequency band range of the tunable light source 22 based on the wavelength deviation, so that the high-frequency microphone system is always at the operating point.

[0068] Among them, when calculating the actual operating point wavelength, the wavelength deviation corresponding to its wavelength can be obtained by calculating the peak value of the scanning light source 21 under the influence of different environments such as temperature , and a total wavelength deviation is finally formed based on multiple different wavelength deviations.

[0069] Among them, step S2 includes:

[0070] S21: Based on the correspondence between the scanning wavelength of the scanning light source 21 and the output light intensity, draw the reflection spectrum of the high-reflectivity F-P cavity;

[0071] S22: Determine all the maximum points of the reflection spectrum of the high-reflectivity F-P cavity;

[0072] S23: Obtain the wavelengths corresponding to all the maximum points at 75% of the output light intensity, and obtain multiple intermediate wavelengths;

[0073] S24: Take the average value of the multiple intermediate wavelengths as the actual operating point wavelength of the sensing probe 1.

[0074] Specifically, the operating point is the positive intersection point (Q point) where the interference spectral slope is the largest, and the FPI exhibits linear response and maximum sensitivity. During the signal demodulation process, the operating wavelength of the input light should be maintained at the Q point to achieve high sensitivity and linear response of the system. The current operating point control is to enable the system to stably operate at the Q point position without external acoustic signal input.

[0075] In this embodiment, the operating point control method uses two scanning light sources. Control the tunable light source 22 to perform wavelength scanning within the specified range, and at the same time collect the output light intensity after passing through the F-P cavity; find the wavelength corresponding to 75% of the maximum light intensity according to the correspondence between the scanning wavelength and the output light intensity, and then the operating point wavelength of the F-P cavity acoustic sensing can be obtained; configure the calculated operating point wavelength to the scanning light source 21, and the system can work at the operating point Q.

[0076] Figure 5 and Figure 6 The working point control principle is schematically shown and specifically includes the following steps:

[0077] (1) Two scanning light sources are used in the working point control method. The tunable light source 22 is controlled to perform wavelength scanning within a specified range, and at the same time, the output light intensity after passing through the F-P cavity is collected. The relationship curve between the scanning wavelength and the light intensity can be as Figure 5 shown. The wavelength range of the scanning light source used in this system is 4 nm, so multiple peaks can be scanned;

[0078] (2) According to the corresponding relationship between the scanning wavelength and the output light intensity, the working point wavelength of the F-P cavity acoustic sensor can be obtained by finding the wavelength corresponding to 75% of the maximum light intensity, as shown by the circle in Figure 6 ;

[0079] (3) Calculate the periodic mean value of the working point wavelength through multiple peaks;

[0080] (4) According to the working point wavelength period, calculate the wavelength value configured on the scanning light source 21 so that the system works at the working point Q.

[0081] The working point control in this embodiment is specifically implemented in software with two schemes: (1) knowing the output light intensity corresponding to the Q point ; (2) not knowing the output light intensity corresponding to the Q point , and it can only be obtained by calculating 75% of the maximum light intensity. The difference between the two is the presence or absence of the working point Q module. In the specific implementation process of the software, a light source working wavelength module, a mean value calculation module, a maximum value point module, a working wavelength period module, a working point Q module, and a working wavelength determination module are set.

[0082] Light source working wavelength module: It is used to indicate which wavelength position the current scanning light source is working at. Its input is two level pins of the light source, and the wavelength is determined by counting the number of pulses;

[0083] Mean value module: The input is the light intensity after the scanning light source is reflected by the probe. In this system, the sampling rate is much greater than the scanning frequency of the light source. Therefore, a mean value module is used to reduce the interference of noise;

[0084] Maximum value point module: The calculated mean value is passed through a maximum value point module to find each peak value point in Figure 5 , and the working wavelength period of the system can be determined through each peak value point;

[0085] Working wavelength period module: Since there are multiple peak value points, multiple peak value periods will be calculated, and there will be a certain error in each period. To reduce this error, this module will take the mean value of each peak value period as the output, which is used as the working wavelength period output by the current system scanning period;

[0086] Operating point Q module: It is used to calculate the light intensity value after the emission wavelength is reflected by the probe when the system operates at point Q. This value is theoretically 75% of the maximum value. Figure 5 It can be seen that multiple maximum points will be scanned, and there will be errors in 75% of each maximum value. To reduce this error, this module will take the average value of the light intensity values calculated from each peak as the output, which is used as the light intensity value corresponding to the operating wavelength output in the current system scanning period, and will output the wavelength corresponding to the last light intensity value as the operating wavelength;

[0087] Operating wavelength determination module: With the operating wavelength and the operating wavelength period, the operating wavelength period can be accumulated until the wavelength value reaches the scanning wavelength range of the tunable light source 22, and this wavelength value will be output. The lower-level module will configure this value to the scanning light source 21.

[0088] In this embodiment, the high-frequency optical microphone is based on the optical interference intensity demodulation - operating point control method. This demodulation method converts the change in the interference spectrum intensity into a voltage signal for demodulation based on the spectral sideband filtering technology. It has the characteristics of fast demodulation speed, good real-time dynamics, simple system, high sensitivity, etc., and is widely used in the demodulation of high-sensitivity and wide-frequency band signals.

[0089] When the operating wavelength operates at the positive intersection point (Q point) with the maximum slope of the interference spectrum, the FPI presents a linear response and maximum sensitivity. If the operating wavelength drifts to the peak or decline of the interference spectrum, the sensitivity and linearity of the FPI will deteriorate significantly. During the signal demodulation process, the operating wavelength of the input light should always be controlled at the Q point to achieve the high sensitivity and linear response of the system.

[0090] It should be noted that the flowcharts and block diagrams in the accompanying drawings show the possible architectures, functions, and operations of systems, methods, and computer program products according to multiple embodiments of the present application. In this regard, each block in the flowchart or block diagram may represent a module, a program segment, or a part of code, and the module, program segment, or part of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than marked in the accompanying drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, and the combination of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system for performing the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0091] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, devices, and units described above can refer to the corresponding processes in the foregoing method embodiments, and will not be elaborated herein.

[0092] In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there may be other division methods in actual implementation. For another example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection between each other can be through some communication interfaces, and the indirect coupling or communication connection of the devices or units can be in electrical, mechanical or other forms.

[0093] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place, or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered by the scope of the claims and the description of the present application.

Claims

1. A high-frequency microphone system, characterized in that, It includes a sensing probe (1), an optical fiber interferometer (2), a photoelectric conversion module (3), an interference signal demodulation module (4), a light source compensation module (5), and a synchronization module (6); the optical fiber interferometer (2) includes a scanning light source (21), a tunable light source (22), a beam combiner (23), a circulator (24), and a wavelength division multiplexer (25); The high-frequency microphone system includes a sensing optical path and a feedback optical path; Among them, the sensing optical path is as follows: the tunable light source (22) emits a first light beam, the first light beam reaches the sensing probe (1) after passing through the circulator (24), the sensing probe (1) is used to modulate the collected acoustic signal onto the first light beam to obtain a modulation signal, the modulation signal reaches the photoelectric conversion module (3) through the circulator (24) and is converted into a first electrical signal, the first electrical signal is input to the interference signal demodulation module (4) to demodulate the acoustic signal, and the demodulated acoustic signal is input to the synchronization module (6) to obtain a target acoustic signal; Among them, the feedback optical path is as follows: the scanning light source (21) emits a second light beam, the second light beam reaches the sensing probe (1) after passing through the circulator (24), the second light beam interferes at the sensing probe (1) and then reaches the photoelectric conversion module (3) through the circulator (24) and is converted into a second electrical signal, the second electrical signal is input to the light source compensation module (5), and the light source compensation module (5) is used to adjust the working wavelength of the tunable light source (22) to adjust the working point of the high-frequency microphone system; Among them, the sensing probe (1) is used to modulate the collected acoustic signal onto the first light beam to obtain a modulation signal, including: The sensing probe (1) acquires an external acoustic signal, the acoustic signal causes a change in the air refractive index in the high-reflectivity F-P cavity to cause a change in the phase of the first light beam, and then interferes at the sensing probe (1) to form a modulation signal; The sensing probe (1) is a high-reflectivity F-P cavity, including two high-reflectivity mirrors.

2. The system according to claim 1, characterized in that, The optical fiber interferometer (2) is an optical fiber F-P interferometer.

3. The system according to claim 2, characterized in that The photoelectric conversion module includes a first photodetector and a second photodetector.

4. The system according to claim 3, wherein Both the first electrical signal and the second electrical signal are analog electrical signals.

5. A method for controlling the working point of a high-frequency microphone system as described in any one of claims 1-4, including the following steps: S1: Control the scanning light source (21) to perform wavelength scanning within a frequency band range, and collect the output light intensity of the light beam passing through the sensing probe (1); S2: Based on the corresponding relationship between the scanning wavelength of the scanning light source (21) and the output light intensity, obtain the actual working point wavelength of the sensing probe (1); S3: Based on the actual working point wavelength and the initial calibrated working point wavelength, obtain the wavelength deviation of the sensor working point; S4: Configure the working wavelength of the tunable light source (22) based on the wavelength deviation so that the high-frequency microphone system is always at the working point.

6. The method according to claim 5, characterized in that Step S2 includes: S21: Based on the corresponding relationship between the scanning wavelength of the scanning light source (21) and the output light intensity, draw the reflection spectrum of the high-reflectivity F-P cavity; S22: Determine all the maximum value points of the reflection spectrum of the high-reflectivity F-P cavity; S23: Obtain the wavelengths corresponding to all maximum points at 75% of the output light intensity, and obtain multiple intermediate wavelengths; S24: Take the mean value of the multiple intermediate wavelengths as the actual working point wavelength of the sensing probe (1).

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