An arrayed sensing system based on optical resonators

Abstract

The application belongs to the technical field of acoustic 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 path splitting optical device, an optical resonant cavity and a negative feedback module. The light path splitting optical device comprises a fiber beam splitter, a light path splitting delay line, a fiber loop and a coupling device. The negative feedback module is connected with the fiber loop and the laser light source. The laser light source emits a laser beam, generates an optical pulse through the optical switch device, and splits the optical pulse into multiple light beams through the fiber beam splitter in the light path splitting optical device. Each light beam enters the optical resonant cavity after being coupled by the light path splitting delay line, the fiber loop and the coupling device in turn. The optical resonant cavity reflects the light beams along the original light path. The reflected light beams are coupled to the coupling device again, transmitted to the negative feedback module through the fiber loop, and then input to the laser light source for compensation of the laser beam after being processed by the negative feedback module.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of acoustic wave measurement, and particularly relates to an array type sensing system based on an optical resonant cavity. BACKGROUND

[0002] In the field of acoustic wave measurement, optical acoustic wave measurement devices are an important technical means. Among them, the membrane-free optical acoustic measurement device realizes the sensing of acoustic waves based on the change of the measurement of air refractive index. This technology has significant advantages, as it does not rely on inertial elements, effectively avoiding measurement errors caused by the characteristics of inertial elements, and the measured acoustic wave signal has no tail deformation phenomenon, and its measurement frequency range of acoustic waves can reach MHz level, showing unique potential in high-frequency acoustic wave measurement.

[0003] However, the existing membrane-free optical acoustic measurement device mostly adopts a single probe design. This single probe structure limits its performance in terms of acoustic field coverage and measurement efficiency, resulting in low measurement efficiency. At the same time, the single probe has insufficient information acquisition richness and accuracy, making the measurement accuracy not high, and it is difficult to meet the needs of some application scenarios that require high acoustic wave measurement accuracy and efficiency. SUMMARY

[0004] The application provides an array type sensing system based on an optical resonant cavity, which divides a laser beam into multiple sub-beams by using a fiber beam splitter, and then couples the sub-beams into an optical resonant cavity through a sub-beam optical device to form an acoustic wave measurement array, so that each sub-beam produces multiple sub-beam interference in the optical resonant cavity, facilitating accurate analysis of the change in air refractive index caused by acoustic waves, and further realizing multi-point synchronous acoustic wave measurement. Through the cooperative design of multiple array elements, more uniform and larger range of acoustic 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.

[0005] An array type sensing system based on an optical resonant cavity, comprising:

[0006] a laser light source, an optical switch device, a sub-beam optical device, an optical resonant cavity, and a negative feedback module; the sub-beam optical device includes a fiber beam splitter, a sub-beam delay line, a fiber ring, and a coupling device; the negative feedback module is connected to the fiber ring and the laser light source;

[0007] The laser light source emits a laser beam, generates an optical pulse through the optical switch device, and is equally divided into multiple partial beams through the optical fiber beam splitter in the optical path splitting optical device. Each partial beam enters the optical resonant cavity in turn after being coupled through the optical path splitting delay line, the optical fiber ring, and the coupling device. The optical resonant cavity reflects the partial beam along the original optical path. The reflected partial beam is coupled to the coupling device again, transmitted to the negative feedback module through the optical fiber ring, and the negative feedback module processes the reflected partial beam signal of the optical fiber ring and inputs it to the laser light source for compensation of the laser beam.

[0008] By using an optical fiber beam splitter to equally divide the laser beam into multiple partial beams, and then coupling them into an optical resonant cavity through an optical path splitting optical device, an acoustic wave measurement array is formed. The multiple partial beams in the optical resonant cavity produce multiple partial beam interference, which facilitates accurate analysis of the change in air refractive index caused by acoustic waves, and further realizes multi-point synchronous acoustic wave measurement. Through multi-array collaborative design, more uniform and larger range of acoustic 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.

[0009] Further, the coupling device includes an optical path splitting collimator for collimating and coupling the received partial beam.

[0010] Further, the coupling device includes multiple groups; the number of coupling devices is the same as the number of partial beams equally divided by the optical fiber beam splitter, and is set one-to-one.

[0011] By designing multiple groups of optical path splitting collimators that are the same as and matched with the number of partial beams, the partial beams can be collimated and coupled into the optical resonant cavity in an array form.

[0012] Further, the optical fiber ring and the optical path splitting collimator are multiplexed; the optical path splitting collimator and the optical resonant cavity are multiplexed.

[0013] Through optical path multiplexing design, the system structure can be miniaturized, and the system cost can be reduced.

[0014] Further, the coupling device includes:

[0015] A beam splitter connected to the optical fiber ring for equally dividing the received partial beam into multiple secondary partial beams;

[0016] A secondary optical path delay fiber connected to the beam splitter for delaying the secondary partial beam;

[0017] A secondary optical path collimator connected to the secondary optical path delay fiber and the optical resonant cavity for collimating and coupling the received secondary partial beam.

[0018] By setting the coupling device containing the beam splitter, the secondary light path delay optical fiber, and the secondary light path collimator, the secondary light beams can be combined and processed in time, the system structure is simplified through the same secondary light path design, and the sensitivity difference caused by the influence of external interference on different detection elements is avoided, thereby improving the precision of the acoustic beam control. Through the combination of the light path design and the secondary light path design, the time and space can be combined and processed in a time and space combined manner, and then the secondary light beams can enter the optical resonant cavity in the form of a large-scale array, thereby improving the accuracy of the multi-point synchronous acoustic wave measurement.

[0019] Further, the coupling device includes multiple groups, and the number of the coupling devices is the same as the number of the secondary light beams split by the beam splitter and is set in one-to-one correspondence.

[0020] By designing multiple groups of secondary light path collimators that are the same as and matched with the number of secondary light beams, the secondary light beams can be collimated and coupled into the optical resonant cavity in the form of an array.

[0021] Further, the optical fiber circulator is multiplexed with the beam splitter optical path, the beam splitter is multiplexed with the secondary light path delay optical fiber, the secondary light path delay optical fiber is multiplexed with the secondary light path collimator, and the secondary light path collimator is multiplexed with the optical resonant cavity.

[0022] Through the optical path multiplexing design, the system structure can be miniaturized, and the system cost can be reduced.

[0023] Further, the negative feedback module includes:

[0024] A photodetector connected to the optical fiber circulator, configured to convert the reflected light beam signal fed back by the optical fiber circulator into a voltage signal;

[0025] An analog-to-digital conversion unit connected to the photodetector, configured to convert the voltage signal output by the photodetector into a digital signal;

[0026] A micro control unit connected to the analog-to-digital conversion unit, configured to convert the digital signal output by the analog-to-digital conversion unit into an acoustic signal;

[0027] A negative feedback unit connected to the micro control unit and the laser light source, configured to regulate and compensate the laser beam emitted by the laser light source according to the acoustic signal output by the micro control unit.

[0028] By setting the negative feedback module, the resonant cavity is compensated in real time, so that the resonant cavity is constantly at the operating point, the sensitivity remains unchanged, and the sensitivity decline caused by the external environmental interference is avoided.

[0029] Further, the micro control unit is connected to the light splitting path delay line, and is used for controlling the delay time of each light splitting beam to control the received signal of the corresponding light splitting path.

[0030] By connecting and controlling the light splitting path extension line through the micro control unit, the sound pressure sensitivity control of each light splitting path can be realized, and the control of the received sound beam is further realized.

[0031] The beneficial effects of the present application are:

[0032] The present application divides the laser beam into multiple light splitting beams by using the optical fiber beam splitter, and then enters the optical resonant cavity after coupling through the light splitting path optical device, to form a sound wave measurement array, so that each light splitting beam generates multi-beam interference in the optical resonant cavity, which is convenient for accurately analyzing the air refractive index change caused by the sound wave, and further realizes the multi-point synchronous sound wave measurement; through the collaborative design of multiple array elements, more uniform and larger range of sound field coverage can be provided to improve the detection efficiency and realize higher detection and imaging resolution; by combining the light splitting path design and the sub-light splitting path design, time division and space division can be combined to perform merging and collaborative processing in time and space, so that the sub-light splitting beam can enter the optical resonant cavity in the form of a large-scale array, and the accuracy of multi-point synchronous sound wave measurement is improved. The whole optical sound measurement system has small loss and strong anti-interference ability. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is a system structure schematic diagram containing a light splitting path;

[0034] Figure 2 It is a system structure schematic diagram containing a light splitting path and a sub-light splitting path;

[0035] Figure 3 It is a system structure schematic diagram containing a sub-light splitting path;

[0036] Figure 4 It is a sound beam control schematic diagram;

[0037] Figure 5 It is a principle schematic diagram of a negative feedback module. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0039] It is to be appreciated that various aspects described herein are described in the context of examples that are within the scope of the claims. It is to be understood that the aspects described herein can be implemented in a wide variety of forms and that any particular structure and / or function described herein is merely illustrative. Based on the teachings provided herein one skilled in the art will appreciate that one or more aspects described herein can be implemented independently of any other aspects described herein. One skilled in the art will appreciate that an aspect described herein can be implemented in any of a variety of forms. Additionally, an aspect described herein can be implemented in a combination of different aspects described herein. This disclosure is not limited to the aspects described herein, but rather the intent is to cover any aspect or combination of aspects within the scope of the claims.

[0040] In addition, in the following description, specific details are given to provide thorough understanding of examples, and one skilled in the art will understand that the specific details need not be kept to specific aspects in this application.

[0041] Embodiment 1

[0042] Figure 1 It is shown that an array type sensing system based on optical resonant cavity, laser light source, optical switch device, light path splitting optical device, optical resonant cavity, negative feedback module, by using fiber beam splitter, the laser beam is equally divided into multiple split beams, and then coupled into the optical resonant cavity through the light path splitting optical device, an acoustic wave measurement array is formed, so that each split beam produces multi-split beam interference in the optical resonant cavity, which is convenient for accurately analyzing the change of air refractive index caused by acoustic wave, and then realizing multi-point synchronous acoustic wave measurement; through the cooperative design of multiple array elements, more uniform and larger range of acoustic field coverage can be provided to improve the detection efficiency and realize higher detection and imaging resolution; the whole optical acoustic measurement system has small loss and strong anti-interference ability.

[0043] Specifically, the laser light source is used to emit a laser beam.

[0044] Specifically, the optical switch device is arranged on the light output path of the laser light source, and is used to control the on-off of the laser beam and the generation of the optical pulse. By switching the switch state, an optical pulse signal with specific time characteristics can be generated, which is convenient for subsequent measurement requirements.

[0045] Specifically, the light path splitting optical device includes:

[0046] The fiber beam splitter is arranged on the light output path of the optical switch device, and is used to equally divide the output optical pulse into multiple split beams, thereby providing a basis for multi-channel parallel measurement.

[0047] The light path splitting delay line is connected to the fiber beam splitter, and is used to time delay the split beams of the light path splitting.

[0048] In the embodiment, the light-splitting path delay line is an electric delay line.

[0049] The fiber circulator is connected to the light-splitting path delay line, and is used to ensure unidirectional transmission of the optical signal and avoid interference of reflected light on the system.

[0050] The coupling device is used to optically process the light-splitting beams and couple them into the optical resonant cavity.

[0051] In the embodiment, the coupling device is a light-splitting path collimator, and includes multiple groups; the number of the light-splitting path collimators is the same as the number of the light-splitting beams equally divided by the fiber beam splitter, and is arranged in one-to-one correspondence, and is used to collimate and couple the received light-splitting beams into the optical resonant cavity in an array form.

[0052] The fiber circulator is multiplexed with the light-splitting path collimator; the light-splitting path collimator is multiplexed with the optical resonant cavity, and through the multiplexing design of the optical paths, the system structure can be miniaturized, and the system cost can be reduced.

[0053] In the embodiment, as shown in Figure 2 The coupling device includes the beam splitter, the secondary light-splitting path delay fiber, and the secondary light-splitting path collimator, and includes multiple groups, and the number of the secondary light-splitting beams equally divided by the beam splitter is the same as the number of the secondary light-splitting path collimators arranged in one-to-one correspondence, and then through the design of the multiple groups of the secondary light-splitting path collimators matching the number of the secondary light-splitting beams, the secondary light-splitting beams can be collimated and coupled into the optical resonant cavity in an array form.

[0054] The beam splitter is connected to the fiber circulator, and is used to equally divide the received light-splitting beams, and form multiple secondary light-splitting beams through the multiple beam splitters; the secondary light-splitting path delay fiber is connected to the beam splitter, and is used to delay the secondary light-splitting beams; the secondary light-splitting path collimator is connected to the secondary light-splitting path delay fiber and the optical resonant cavity, and is used to collimate and couple the received secondary light-splitting beams. Through the design of the coupling device including the beam splitter, the secondary light-splitting path delay fiber, and the secondary light-splitting path collimator, the secondary light-splitting beams can be combined and cooperatively processed in time, the system structure can be simplified through the same secondary light-splitting path design, the sensitivity difference caused by the influence of external interference on different detection elements can be avoided, and the precision of the acoustic beam control is improved; through the combination of the light-splitting path design and the secondary light-splitting path design, the secondary light-splitting beams can be combined and cooperatively processed in time and space in a time-division and space-division combined manner, and then the secondary light-splitting beams can be coupled into the optical resonant cavity in a large-scale array form, and the accuracy of the multi-point synchronous acoustic wave measurement is improved.

[0055] The fiber circulator is multiplexed with the beam splitter; the beam splitter is multiplexed with the secondary light-splitting path delay fiber; the secondary light-splitting path delay fiber is multiplexed with the secondary light-splitting path collimator; and the secondary light-splitting path collimator is multiplexed with the optical resonant cavity, and through the multiplexing design of the optical paths, the system structure can be miniaturized, and the system cost can be reduced.

[0056] It should be noted that, as Figure 3 shown in the actual application, when only the time needs to be combined, the light splitting path optical device includes a fiber optic circulator, a beam splitter, a secondary light splitting path delay fiber, and a secondary light splitting path collimator. By transmitting the light pulses generated by the optical switch device to the beam splitter through the fiber optic circulator for equal division, and setting multiple beam splitters according to the light equalization requirements to continuously divide the light beams, the secondary light beams of each secondary light splitting path are coupled in array form into the optical resonant cavity after passing through the secondary light splitting path delay fiber and the secondary light splitting path collimator, thereby improving the accuracy of sound beam control.

[0057] Specifically, the optical resonant cavity is used to reflect the input laser beam multiple times to form beam interference and enhance the photoacoustic effect.

[0058] Specifically, the negative feedback module is connected to the fiber optic circulator and the laser light source, and is used to compensate the resonant cavity in real time, so that the resonant cavity is constantly at the operating point, the sensitivity remains unchanged, and the sensitivity decline caused by external environmental interference is avoided. Specifically includes:

[0059] The photoelectric detector is connected to the fiber optic circulator, and is used to convert the reflected light beam signal fed back by the fiber optic circulator into a voltage signal;

[0060] The analog-to-digital conversion unit is connected to the photoelectric detector, and is used to convert the voltage signal output by the photoelectric detector into a digital signal;

[0061] The micro control unit is connected to the analog-to-digital conversion unit, and is used to convert the digital signal output by the analog-to-digital conversion unit into an acoustic signal;

[0062] In this embodiment, as Figure 4 shown, the micro control unit is connected to the light splitting path delay line, which is used to control the delay time of each light beam to control the received signal of the corresponding light splitting path, thereby realizing the sound pressure sensitivity control of each light splitting path, and realizing the control of the received sound beam.

[0063] The negative feedback unit is connected to the micro control unit and the laser light source, and is used to regulate and compensate the laser beam emitted by the laser light source according to the acoustic signal output by the micro control unit.

[0064] It should be noted that in actual application, only any sound signal needs to be processed to realize the regulation and compensation of the laser beam emitted by the laser light source.

[0065] 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.

[0066] Example 2

[0067] 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.

[0068] 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:

[0069] 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.

[0070] 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:

[0071] 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.

[0072] The light beams on each light splitting path are split into n secondary light beams by n beam splitters, and n x n sound signals are output after processing by the negative feedback module. The light beams on the fiber ring are processed to be output to the laser source for wavelength compensation.

[0073] As shown in Figure 3 When the light splitting path optical device includes a fiber ring, a beam splitter, a secondary light path delay fiber, and a secondary light path collimator, the optical path design is as follows:

[0074] The laser source emits a laser beam, which is converted into a light pulse by an optical switch device, and then input into the beam splitter through the fiber ring. A plurality of secondary light beams are formed by a plurality of beam splitters. The secondary light beams on each secondary light path are coupled into the optical resonant cavity in turn after passing through the secondary light path delay fiber and the secondary light path collimator. The optical resonant cavity reflects the secondary light beams along the original optical path. The reflected secondary light beams are coupled into the secondary light path collimator, transmitted to the negative feedback module through the fiber ring, and then processed by the negative feedback module. The processed light beams are input into the laser source for wavelength compensation of the laser beam.

[0075] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0076] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. An arrayed sensing system based on optical resonators, characterized in that, The application relates to a laser light source, an optical switch device, a light path splitting optical device, an optical resonant cavity and a negative feedback module. The light path splitting optical device comprises a fiber beam splitter, a light path splitting delay line, a fiber loop and a coupling device; the negative feedback module is connected with the fiber loop and the laser light source. The laser light source emits a laser beam, generates an optical pulse through the optical switch device, and splits the optical pulse into multiple sub-beams through the fiber beam splitter in the light path splitting optical device; each sub-beam is sequentially coupled into the optical resonant cavity through the light path splitting delay line, the fiber loop and the coupling device; the optical resonant cavity reflects the sub-beams along the original light path; the reflected sub-beams are coupled to the coupling device again, transmitted to the negative feedback module through the fiber loop, and then input into the laser light source to compensate the laser beam. The coupling device comprises a light path splitting collimator for collimating and coupling the received sub-beams. The coupling device comprises multiple groups; the number of the coupling devices is the same as the number of the sub-beams split by the fiber beam splitter, and each coupling device corresponds to one sub-beam.

2. An arrayed optical resonator-based sensing system according to claim 1, wherein, The fiber loop and the light path splitting collimator are multiplexed in the light path; the light path splitting collimator and the optical resonant cavity are multiplexed in the light path.

3. An arrayed optical resonator-based sensing system according to claim 1, wherein, The coupling device comprises:

4. An arrayed optical resonator-based sensing system according to claim 1, wherein, a beam splitter connected with the fiber loop, for splitting the received sub-beams into multiple secondary sub-beams; a secondary light path delay fiber connected with the beam splitter, for delaying the secondary sub-beams; a secondary light path collimator connected with the secondary light path delay fiber and the optical resonant cavity, for collimating and coupling the received secondary sub-beams. The coupling device comprises multiple groups; the number of the coupling devices is the same as the number of the secondary sub-beams split by the beam splitter, and each coupling device corresponds to one secondary sub-beam.

5. An arrayed optical resonator-based sensing system according to claim 4, wherein, The fiber loop and the beam splitter are multiplexed in the light path; the beam splitter and the secondary light path delay fiber are multiplexed in the light path; the secondary light path delay fiber and the secondary light path collimator are multiplexed in the light path; the secondary light path collimator and the optical resonant cavity are multiplexed in the light path.

6. An arrayed optical resonator-based sensing system according to claim 4, wherein, The negative feedback module comprises:

7. An arrayed optical resonator-based sensing system according to claim 1 or 4, wherein, a photodetector connected with the fiber loop, for converting the reflected sub-beam signal fed back by the fiber loop into a voltage signal; an analog-to-digital conversion unit connected with the photodetector, for converting the voltage signal output by the photodetector into a digital signal; a micro control unit connected with the analog-to-digital conversion unit, for converting the digital signal output by the analog-to-digital conversion unit into an acoustic signal; a negative feedback unit connected with the micro control unit and the laser light source, for regulating and compensating the laser beam emitted by the laser light source according to the acoustic signal output by the micro control unit. The micro control unit is connected with the light path splitting delay line, for controlling the delay time of each sub-beam to control the received signal of the corresponding light path.

8. An arrayed optical resonator-based sensing system according to claim 7, wherein, ​

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