Array type sensing system based on optical resonant cavity

Abstract

The invention belongs to the technical field of sound wave measurement, and particularly relates to an array type sensing system based on an optical resonant cavity, which comprises a laser light source, an optical switch device, a light splitting path optical device, the optical resonant cavity and a negative feedback module, the optical path splitting optical device comprises an optical fiber beam splitter, an optical path splitting delay line, an optical fiber circulator and a coupling device; the negative feedback module is connected with the optical fiber circulator and the laser light source; the laser light source emits laser beams, light pulses are generated through the optical switch device and equally divided into a plurality of split light beams through an optical fiber beam splitter in the light-path-splitting optical device, each split light beam enters the optical resonant cavity after being sequentially coupled through the light-path-splitting delay line, the optical fiber circulator and the coupling device, the optical resonant cavity reflects the split light beams along an original light path, and the light-path-splitting optical device outputs the reflected light beams. The reflected split light beams are coupled to the coupling device and then transmitted to the negative feedback module through the optical fiber circulator, and the negative feedback module processes split light beam signals reflected by the optical fiber circulator and then inputs the split light beam signals to the laser light source for compensation of the laser beams.

Description

Technical Field

[0001] This invention belongs to the field of acoustic wave measurement technology, specifically relating to an array-type sensing system based on an optical resonant cavity. Background Technology

[0002] In the field of acoustic wave measurement, optical acoustic wave measurement devices are an important technical means. Among them, membrane-free optical acoustic measurement devices sense sound waves by measuring changes in the refractive index of air. This technology has significant advantages: because it does not rely on inertial components, it can effectively avoid measurement errors caused by the characteristics of inertial components; the measured acoustic wave signals do not exhibit tailing distortion; and its frequency range for measuring acoustic waves can reach the MHz level, showing unique potential in high-frequency acoustic wave measurement.

[0003] However, most existing membrane-free optical acoustic measurement devices employ a single-probe design. This single-probe structure limits their performance in terms of sound field coverage and measurement efficiency, resulting in low measurement efficiency. Furthermore, single probes are insufficient in terms of the richness and accuracy of information acquired, leading to low measurement precision and making it difficult to meet the needs of some applications requiring high accuracy and efficiency in sound wave measurement. Summary of the Invention

[0004] This invention provides an array-type sensing system based on an optical resonant cavity. A laser beam is divided into multiple beams using an optical fiber beam splitter, and then coupled through optical components in the splitting path before entering the optical resonant cavity to form an acoustic wave measurement array. This allows the individual beams to generate multi-beam interference within the optical resonant cavity, facilitating accurate analysis of changes in air refractive index caused by the acoustic waves, thereby achieving multi-point synchronous acoustic wave measurement. Through multi-element collaborative design, a more uniform and wider sound field coverage can be provided to improve detection efficiency and achieve higher detection and imaging resolution. The entire optical acoustic measurement system exhibits low loss and strong anti-interference capability.

[0005] An array-type sensing system based on an optical resonant cavity includes: The system includes a laser source, an optical switching device, a beam splitter optical component, an optical resonator, and a negative feedback module; the beam splitter optical component includes an optical fiber beam splitter, a beam splitter delay line, an optical fiber circulator, and a coupling device; the negative feedback module connects the optical fiber circulator and the laser source. The laser source emits a laser beam, which is converted into an optical pulse by the optical switch device and then split into multiple beams by the fiber optic beam splitter in the beam splitting optical device. Each beam is sequentially coupled through the beam splitting delay line, the fiber optic circulator, and the coupling device before entering the optical resonant cavity. The optical resonant cavity reflects the beam along the original optical path, and the reflected beam is then coupled back to the coupling device. It is then transmitted through the fiber optic circulator to the negative feedback module. The negative feedback module processes the beam signal reflected by the fiber optic circulator and inputs it to the laser source for laser beam compensation.

[0006] By employing an optical fiber beam splitter to divide the laser beam into multiple beams, which are then coupled through optical components in the splitting path and enter an optical resonant cavity to form an acoustic wave measurement array, the beams generate multi-beam interference within the optical resonant cavity. This facilitates accurate analysis of the air refractive index changes caused by the acoustic waves, thereby enabling multi-point synchronous acoustic wave measurement. Through multi-element collaborative design, a more uniform and wider sound field coverage can be provided to improve detection efficiency and achieve higher detection and imaging resolution. The entire optical acoustic measurement system has low loss and strong anti-interference capability.

[0007] Furthermore, the coupling device includes a beam splitter collimator for collimating and coupling the received split beam.

[0008] Furthermore, the coupling device comprises multiple sets; the number of the coupling devices is the same as the number of beams split by the fiber optic beam splitter, and they are arranged in a one-to-one correspondence.

[0009] By designing multiple sets of beam splitter collimators that are the same number as and matched with the number of split beams, the split beams can be collimated and coupled before entering the optical resonant cavity in an array.

[0010] Furthermore, the optical path of the fiber optic circulator is multiplexed with that of the beam splitter collimator; the optical path of the beam splitter collimator is multiplexed with that of the optical resonant cavity.

[0011] Optical path multiplexing design enables system miniaturization and reduces system cost.

[0012] Furthermore, the coupling device includes: A beam splitter, which is connected to the fiber optic circulator, is used to divide the received beam into multiple sub-beams. The secondary beam splitter delay fiber is connected to the beam splitter and is used to delay the secondary beam. The secondary beam collimator connects the secondary beam delay fiber and the optical resonant cavity, and is used to collimate and couple the received secondary beam.

[0013] By setting up coupling devices containing beam splitters, secondary optical path delay fibers, and secondary optical path collimators, the secondary beams can be combined and processed collaboratively in time. Through the same secondary optical path design, the system structure is simplified, and the sensitivity differences caused by the influence of external interference on different detection elements are avoided, thus improving the accuracy of acoustic beam control. By combining the beam splitting design and the secondary optical path design, a time-division and space-division combined approach can be adopted to combine and process the secondary beams collaboratively in time and space, thereby enabling the secondary beams to enter the optical resonant cavity in a large-scale array form, improving the accuracy of multi-point synchronous acoustic wave measurement.

[0014] Furthermore, the coupling device comprises multiple sets; the number of the coupling devices is the same as the number of sub-beams equally divided by the beam splitter, and they are arranged in a one-to-one correspondence.

[0015] By designing multiple sets of collimators for the sub-splitting optical paths that are the same number as and matched with the sub-splitting beams, the sub-splitting beams can be collimated and coupled before entering the optical resonant cavity in an array.

[0016] Furthermore, the optical path of the fiber circulator is multiplexed with that of the beam splitter; the optical path of the beam splitter is multiplexed with that of the secondary beam splitter delay fiber; the optical path of the secondary beam splitter delay fiber is multiplexed with that of the secondary beam splitter collimator; and the optical path of the secondary beam splitter collimator is multiplexed with that of the optical resonator.

[0017] Optical path multiplexing design enables system miniaturization and reduces system cost.

[0018] Furthermore, the negative feedback module includes: A photodetector, connected to the fiber optic circulator, is used to convert the reflected beam splitting signal fed back by the fiber optic circulator into a voltage signal. An analog-to-digital converter unit, connected to the photodetector, is used to convert the voltage signal output by the photodetector into a digital signal; A microcontroller unit, connected to the analog-to-digital converter, is used to convert the digital signal output by the analog-to-digital converter into an acoustic signal; A negative feedback unit, which is connected to the microcontroller unit and the laser source, is used to adjust and compensate the laser beam emitted by the laser source according to the acoustic signal output by the microcontroller unit.

[0019] By setting up a negative feedback module, the resonant cavity is compensated in real time, thereby keeping the resonant cavity constantly at the operating point, maintaining constant sensitivity, and avoiding sensitivity decrease caused by external environmental interference.

[0020] Furthermore, the microcontroller unit is connected to the beam splitting delay line to control the delay time of each beam splitter in order to control the received signal of the corresponding beam splitter.

[0021] By connecting and controlling the beam splitter extension line through a microcontroller unit, the sound pressure sensitivity of each beam splitter can be controlled, thereby enabling control of the receiving sound beam.

[0022] The beneficial effects of this invention are as follows: This invention utilizes an optical fiber beam splitter to divide a laser beam into multiple beams, which are then coupled through optical components in the beam splitter path and enter an optical resonant cavity to form an acoustic wave measurement array. This allows the individual beams to generate multi-beam interference within the optical resonant cavity, facilitating accurate analysis of changes in the air refractive index caused by the acoustic waves, thereby enabling multi-point synchronous acoustic wave measurement. Through a multi-element collaborative design, a more uniform and wider sound field coverage can be provided to improve detection efficiency and achieve higher detection and imaging resolution. By combining beam splitter and sub-beam splitter designs, a time-division and space-division combined approach can be used for merging and collaborative processing in time and space. This allows the sub-beams to enter the optical resonant cavity in a large-scale array, improving the accuracy of multi-point synchronous acoustic wave measurement. The entire optical acoustic measurement system exhibits low loss and strong anti-interference capabilities. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a system structure containing a beam splitter. Figure 2 This is a schematic diagram of a system structure containing a beam splitter and a sub-beam splitter. Figure 3 This is a schematic diagram of a system structure containing a secondary optical splitter. Figure 4 This is a schematic diagram of sound beam control; Figure 5 This is a schematic diagram of the negative feedback module. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using other structures and / or functionalities besides one or more of the aspects set forth herein.

[0026] In addition, specific details are provided in the following description to facilitate a thorough understanding of the examples, and those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0027] Example 1 Figure 1 The system shown is an array-type sensing system based on an optical resonant cavity. It includes a laser source, optical switching devices, beam splitting optics, an optical resonant cavity, and a negative feedback module. The laser beam is divided into multiple beams by an optical fiber beam splitter, and then coupled through the beam splitting optics before entering the optical resonant cavity to form an acoustic wave measurement array. This allows for multi-beam interference within the optical resonant cavity, facilitating accurate analysis of changes in air refractive index caused by the acoustic waves, thereby enabling multi-point synchronous acoustic wave measurement. Through multi-element collaborative design, it can provide more uniform and wider sound field coverage to improve detection efficiency and achieve higher detection and imaging resolution. The entire optical acoustic measurement system exhibits low loss and strong anti-interference capability.

[0028] Specifically, a laser source is used to emit a laser beam; Specifically, an optical switch device is placed in the optical path of a laser source to control the on / off state of the laser beam and the generation of optical pulses. By switching the switch state, it can generate optical pulse signals with specific time characteristics, thereby facilitating subsequent measurement needs.

[0029] Specifically, the optical components for beam splitting include: An optical fiber beam splitter is installed in the output optical path of an optical switching device to divide its output optical pulse into multiple beams, thereby providing a basis for multi-channel parallel measurement. The beam splitter delay line is connected to the fiber optic beam splitter and is used to delay the split beam in the beam splitter. In this embodiment, the beam splitter delay line is an electrically driven delay line.

[0030] Fiber optic circulators connect to the delay lines of the optical splitter path to ensure unidirectional transmission of optical signals and prevent reflected light from interfering with the system. A coupling device used to couple a split beam into an optical resonant cavity after optical processing.

[0031] In this embodiment, the coupling device is a beam splitter collimator, and includes multiple sets; the number of beam splitters is the same as the number of beams split by the fiber beam splitter, and they are set in a one-to-one correspondence, used to collimate and couple the received beams into the optical resonant cavity in an array.

[0032] Among them, the optical path of the fiber optic circulator is multiplexed with that of the beam splitter collimator; the optical path of the beam splitter collimator is multiplexed with that of the optical resonator. Through the optical path multiplexing design, the system structure can be miniaturized and the system cost can be reduced.

[0033] In this embodiment, as Figure 2 As shown, the coupling device includes a beam splitter, a secondary optical path delay fiber, and a secondary optical path collimator, and includes multiple sets of secondary beams that are the same number as the number of beams split by the beam splitter and are set in a one-to-one correspondence. By designing multiple sets of secondary optical path collimators that are the same number as the number of secondary beams and are matched, the secondary beams can be collimated and coupled and then enter the optical resonant cavity in an array.

[0034] The system comprises a beam splitter connected to an optical fiber circulator to equally divide the received beam into multiple sub-beams. Multiple beam splitters are used to continuously divide the beam into multiple sub-beams. A secondary beam splitter delay fiber is connected to the beam splitter to delay the sub-beams. A secondary beam splitter collimator connects the secondary beam splitter delay fiber and the optical resonator to collimate and couple the received sub-beams. By incorporating coupling devices containing beam splitters, secondary beam splitter delay fibers, and secondary beam splitter collimators, the sub-beams can be combined and processed in time. The identical secondary beam splitter design simplifies the system structure and avoids sensitivity differences caused by external interference affecting different detection elements, thus improving the accuracy of acoustic beam control. By combining the beam splitter and sub-beam splitter designs, a time-division and space-division combined approach can be used for combined and processed in both time and space. This allows the sub-beams to enter the optical resonator in a large-scale array, improving the accuracy of multi-point synchronous acoustic wave measurements.

[0035] Among them, the optical paths of the fiber circulator and the beam splitter are multiplexed; the optical paths of the beam splitter and the secondary optical path delay fiber are multiplexed; the optical paths of the secondary optical path delay fiber and the secondary optical path collimator are multiplexed; and the optical paths of the secondary optical path collimator and the optical resonator are multiplexed. Through the optical path multiplexing design, the system structure can be miniaturized and the system cost can be reduced.

[0036] It should be noted that, as Figure 3As shown, in practical applications, when only time-based merging is required, the optical components of the beam splitting path include an optical fiber circulator, a beam splitter, a secondary beam splitting delay fiber, and a secondary beam splitting collimator. The optical pulses generated by the optical switching device are transmitted to the beam splitter for equal division via the optical fiber circulator. Multiple beam splitters are set according to the optical beam splitting requirements to continuously divide the beam equally. This allows the secondary beams of each secondary beam splitting path to sequentially pass through the secondary beam splitting delay fiber and the secondary beam splitting collimator before entering the optical resonant cavity in an array, thereby improving the accuracy of the acoustic beam control.

[0037] Specifically, an optical resonant cavity is used to reflect the input laser beam multiple times, forming beam interference and thus enhancing the photoacoustic effect.

[0038] Specifically, the negative feedback module, connecting the fiber optic circulator and the laser source, is used to compensate the resonant cavity in real time, thereby keeping the resonant cavity constantly at its operating point, maintaining constant sensitivity, and avoiding sensitivity degradation caused by external environmental interference. This includes: A photodetector, connected to an optical fiber circulator, is used to convert the reflected beam signal fed back by the optical fiber circulator into a voltage signal. An analog-to-digital converter unit, which is connected to a photodetector, is used to convert the voltage signal output by the photodetector into a digital signal; The microcontroller unit, which is connected to the analog-to-digital converter unit, is used to convert the digital signal output by the analog-to-digital converter unit into an audio signal; In this embodiment, as Figure 4 As shown, the microcontroller unit is connected to the beam splitter delay line to control the delay time of each beam splitter in order to control the received signal of the corresponding beam splitter, thereby realizing the sound pressure sensitivity control of each beam splitter and thus realizing the control of the received sound beam.

[0039] The negative feedback unit, which connects the microcontroller unit and the laser source, is used to adjust and compensate the laser beam emitted by the laser source based on the acoustic signal output by the microcontroller unit.

[0040] It should be noted that in practical applications, it is only necessary to process any one of the acoustic signals to adjust and compensate the laser beam emitted by the laser source.

[0041] Figure 5 shows a schematic diagram of the control principle of the negative feedback unit. The voltage signal is compared with the reference bias voltage at the operating point of the optical resonant cavity. The wavelength offset of the optical resonant cavity's operating point is determined using the pre-calibrated relationship between the wavelength offset and the voltage difference. Then, the wavelength of the laser source is tuned and compensated by controlling the wavelength of the laser source through the negative feedback unit, ensuring that the wavelength of the laser source remains at the operating point of the optical resonant cavity.

[0042] Example 2 In this embodiment, based on the same design concept, an array-type sensing system based on an optical resonant cavity is provided to achieve acoustic detection under different requirements.

[0043] like Figure 1 As shown, when the optical components of the beam splitter include an optical fiber beam splitter, a beam splitter delay line, an optical fiber circulator, and a coupling device, and the coupling device is a beam splitter collimator, the optical path design is as follows: A laser source emits a laser beam, which is converted into an optical pulse by an optical switch and then split into multiple beams by an optical fiber beam splitter. Each beam is coupled sequentially through a beam splitter delay line, an optical fiber circulator, and a beam splitter collimator before entering an optical resonant cavity. The optical resonant cavity reflects the beam along the original optical path. The reflected beam is then coupled back to the beam splitter collimator and transmitted through the optical fiber circulator to a negative feedback module. The negative feedback module processes the beam signal reflected by the optical fiber circulator and inputs it back to the laser source for wavelength compensation of the laser beam.

[0044] like Figure 2 As shown, when the optical components of the beam splitter include a fiber beam splitter, a beam splitter delay line, a fiber circulator, and a coupling device, and the coupling device includes a beam splitter, a secondary beam splitter delay fiber, and a secondary beam splitter collimator, the optical path design is as follows: A laser source emits a laser beam, which is converted into light pulses by an optical switch and then split into multiple beams by an optical fiber beam splitter. Each beam is sequentially time-extended by a delay line in the splitter path, then input into the beam splitter via an optical fiber circulator for further splitting. Multiple beam splitters are used to form multiple sub-beams. Each sub-beam in the sub-splitter path is sequentially coupled through a delay fiber and a collimator in the sub-splitter path before entering an optical resonant cavity. The optical resonant cavity reflects the sub-beam along the original optical path. The reflected sub-beam is then coupled back to the collimator in the sub-splitter path, and then transmitted through an optical fiber circulator to a negative feedback module. The negative feedback module processes the beam signal reflected by the optical fiber circulator and inputs it back to the laser source for wavelength compensation of the laser beam.

[0045] In this process, the beam splitting on each beam splitting path is further divided into n sub-beam splitting by n beam splitters. After processing by the negative feedback module, n×n acoustic signals are output. The beam splitting signals fed back by the fiber optic circulator 1 are then processed and output to the laser source for wavelength compensation.

[0046] like Figure 3 As shown, when the optical components of the beam splitter include an optical fiber circulator, a beam splitter, a secondary beam splitter delay fiber, and a secondary beam splitter collimator, the optical path design is as follows: A laser source emits a laser beam, which is then converted into light pulses by an optical switch. These pulses are then fed into a beam splitter via a fiber optic circulator for equal division. Multiple beam splitters are used to create multiple sub-beams. Each sub-beam is sequentially coupled through a sub-beam delay fiber and a sub-beam collimator before entering an optical resonant cavity. The optical resonant cavity reflects the sub-beam along the original optical path. The reflected sub-beam is then coupled back to the sub-beam collimator and transmitted through a fiber optic circulator to a negative feedback module. The negative feedback module processes the beam signal reflected from the fiber optic circulator and inputs it back to the laser source for wavelength compensation.

[0047] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0048] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An array-type sensing system based on an optical resonant cavity, characterized in that, include: Laser source, optical switching device, beam splitter optical device, optical resonator, negative feedback module; The optical components of the beam splitter include an optical fiber beam splitter, a beam splitter delay line, an optical fiber circulator, and a coupling device; the negative feedback module connects the optical fiber circulator and the laser source. The laser source emits a laser beam, which is converted into an optical pulse by the optical switch device and then split into multiple beams by the fiber optic beam splitter in the beam splitting optical device. Each beam is sequentially coupled through the beam splitting delay line, the fiber optic circulator, and the coupling device before entering the optical resonant cavity. The optical resonant cavity reflects the beam along the original optical path, and the reflected beam is then coupled back to the coupling device. It is then transmitted through the fiber optic circulator to the negative feedback module. The negative feedback module processes the beam signal reflected by the fiber optic circulator and inputs it to the laser source for laser beam compensation.

2. The array-type sensing system based on an optical resonant cavity according to claim 1, characterized in that, The coupling device includes a beam splitter collimator for collimating and coupling the received split beam.

3. The array-type sensing system based on an optical resonant cavity according to claim 2, characterized in that, The coupling device comprises multiple sets; the number of the coupling devices is the same as the number of beams split by the fiber optic beam splitter, and they are set in a one-to-one correspondence.

4. The array-type sensing system based on an optical resonant cavity according to claim 2, characterized in that, The optical fiber circulator and the optical path collimator are multiplexed; the optical path collimator and the optical resonator are multiplexed.

5. The array-type sensing system based on an optical resonant cavity according to claim 1, characterized in that, The coupling device includes: A beam splitter, which is connected to the fiber optic circulator, is used to divide the received beam into multiple sub-beams. The secondary beam splitter delay fiber is connected to the beam splitter and is used to delay the secondary beam. The secondary beam collimator connects the secondary beam delay fiber and the optical resonant cavity, and is used to collimate and couple the received secondary beam.

6. The array-type sensing system based on an optical resonant cavity according to claim 5, characterized in that, The coupling device comprises multiple sets; the number of the coupling devices is the same as the number of sub-beams equally divided by the beam splitter, and they are arranged in a one-to-one correspondence.

7. The array-type sensing system based on an optical resonant cavity according to claim 5, characterized in that, The optical path of the fiber circulator is multiplexed with that of the beam splitter; the optical path of the beam splitter is multiplexed with that of the secondary beam splitter delay fiber; the optical path of the secondary beam splitter delay fiber is multiplexed with that of the secondary beam splitter collimator; and the optical path of the secondary beam splitter collimator is multiplexed with that of the optical resonator.

8. An array-type sensing system based on an optical resonant cavity according to claim 2 or 5, characterized in that, The negative feedback module includes: A photodetector, connected to the fiber optic circulator, is used to convert the reflected beam splitting signal fed back by the fiber optic circulator into a voltage signal. An analog-to-digital converter unit, connected to the photodetector, is used to convert the voltage signal output by the photodetector into a digital signal; A microcontroller unit, connected to the analog-to-digital converter, is used to convert the digital signal output by the analog-to-digital converter into an acoustic signal; A negative feedback unit, which is connected to the microcontroller unit and the laser source, is used to adjust and compensate the laser beam emitted by the laser source according to the acoustic signal output by the microcontroller unit.

9. The array-type sensing system based on an optical resonant cavity according to claim 8, characterized in that, The microcontroller unit is connected to the beam splitter delay line and is used to control the delay time of each beam to control the received signal of the corresponding beam splitter.

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