A wireless passive fiber optic sensing system and its control method

Abstract

This application belongs to the field of fiber Bragg grating wireless sensing technology, specifically disclosing a wireless passive fiber optic sensing system and its control method. The system includes a demodulation module, a passive fiber Bragg grating sensing module, and a first optical transceiver module. The passive fiber Bragg grating sensing module includes a fiber Bragg grating sensor and a second optical transceiver module connected in sequence. Both the first and second optical transceiver modules receive optical signals through a multimode optical fiber with a conical lens at one end. The first and second optical transceiver modules are positioned relative to each other within a preset distance range, forming a non-axial transmitting and receiving optical path after beam alignment. The transmitting optical path receives the probe light output from the demodulation module and transmits it to the passive fiber Bragg grating sensing module. The receiving optical path receives the sensing optical signal from the passive fiber Bragg grating sensing module and transmits it to the demodulation module for demodulation. This application can significantly improve system detection efficiency while enhancing detection security.

Description

Technical Field

[0001] This application belongs to the field of fiber optic grating wireless sensing technology, and more specifically, relates to a wireless passive fiber optic sensing system and its control method. Background Technology

[0002] Fiber optic sensing is suitable for large-scale, long-distance sensing applications and is widely used in transportation (railways, highways, bridges), power communication (transmission cables), coal mines, oil and gas exploration, aerospace equipment, and urban security. It is a sensing technology with great market potential.

[0003] Traditional fiber Bragg grating sensing systems typically employ contact-based connection schemes, such as... Figure 1 As shown, multiple fiber Bragg grating sensors are connected in series and attached to the point being measured (such as the surface of a high-voltage electrical cabinet), and then physically connected to a demodulator via fiber optic patch cords. The demodulator has a built-in broadband light source, circulator, and demodulation unit for spectral analysis, and infers temperature changes by monitoring the reflected wavelength shift. However, the application of this physical connection system structure has significant limitations. For example, deploying this traditional sensing system in the power industry requires laying fiber optic cables from the personnel work area to the high-voltage area. If the fiber optic cable contains metal components, the high-voltage electrodes may be led along the cable to the personnel work area, posing a risk of electric shock.

[0004] Existing technologies also use wireless fixed single-beam fiber optic sensing solutions, which acquire sensing signals using only two fixed fiber optic collimators. Due to the extremely small spatial alignment tolerance between the fiber optic collimators, optical axis alignment is extremely difficult, and the installation and debugging are complex and lack flexibility, ultimately resulting in low detection efficiency of the fiber optic sensing system.

[0005] Therefore, how to better realize the application of fiber optic sensing systems has become a technical problem that the industry urgently needs to solve. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this application is to better realize the application of fiber optic sensing systems and to solve the problems of security risks and low detection efficiency in existing fiber optic sensing systems.

[0007] To achieve the above objectives, in a first aspect, this application provides a wireless passive fiber optic sensing system, comprising:

[0008] Demodulation module, passive fiber Bragg grating sensing module, and first optical transceiver module;

[0009] The passive fiber grating sensing module includes a fiber grating sensor and a second optical transceiver module connected in sequence; both the first and second optical transceiver modules receive optical signals through a multimode optical fiber with a conical lens at one end; the first optical transceiver module is connected to the demodulation module; the passive fiber grating sensing module is used to be deployed on the object to be measured.

[0010] The first optical transceiver module and the second optical transceiver module are arranged relative to each other within a preset distance range, and are used to form a transmitting optical path and a receiving optical path with different axes after the beam is aligned;

[0011] The transmitting optical path is used to receive the probe light output by the demodulation module and transmit the probe light to the passive fiber optic grating sensing module.

[0012] The receiving optical path is used to receive the sensing optical signal transmitted from the passive fiber optic grating sensing module and transmit the sensing optical signal to the demodulation module so that the demodulation module can demodulate and obtain the target perception information of the object under test.

[0013] Optionally, the first optical transceiver module includes a sensing optical receiving module and a beam alignment module;

[0014] The optical input end of the beam alignment module is connected to the optical output end of the demodulation module, and is used to receive the probe light output by the demodulation module, and transmit the probe light to the optical input end of the second optical transceiver module through the transmission optical path, so that the passive fiber grating sensing module reflects the sensing light signal.

[0015] The optical output terminal of the sensing optical receiving module is connected to the optical input terminal of the demodulation module, and is used to receive the sensing optical signal transmitted from the second optical transceiver module through the receiving optical path, and transmit the sensing optical signal to the demodulation module.

[0016] Optionally, the second optical transceiver module includes a first multimode fiber, a first fiber collimator, and a beam splitter;

[0017] The optical output end of the first multimode fiber is connected to the probe optical input end of the beam splitter, the optical input end of the first fiber collimator is connected to the sensor optical output end of the beam splitter, and the bidirectional port of the beam splitter is connected to the fiber grating sensor; the optical input end of the first multimode fiber is a conical lens, which serves as the optical input end of the second optical transceiver module.

[0018] The first multimode fiber and the beam alignment module are used to form the transmitting optical path, and the first fiber collimator and the sensing light receiving module are used to form the receiving optical path.

[0019] Optionally, the beam alignment module includes a second fiber collimator and a two-axis galvanometer module arranged sequentially.

[0020] The optical input end of the second fiber collimator serves as the optical input end of the beam alignment module, used to receive the probe light output by the demodulation module and transmit the probe light to the two-axis galvanometer module;

[0021] The two-axis galvanometer module is used to adjust the beam deflection direction of the probe light to align with the optical input end of the second optical transceiver module, thus forming the transmission optical path.

[0022] Optionally, the sensing light receiving module includes a second multimode fiber, an off-axis parabolic reflector, and a first moving platform;

[0023] The optical input end of the off-axis parabolic reflector serves as the optical input end of the sensing optical receiving module; the optical input end of the second multimode fiber is a conical lens, and the optical output end serves as the optical output end of the sensing optical receiving module; the second multimode fiber is arranged within the focal plane of the off-axis parabolic reflector and fixed on the first moving platform; the focused spot diameter of the off-axis parabolic reflector is smaller than the core diameter of the second multimode fiber;

[0024] The off-axis parabolic mirror is used to receive and reflect the sensing light signal transmitted from the second optical transceiver module;

[0025] The first mobile platform is used to perform planar motion according to the target scanning range, so as to drive the second multimode fiber to scan within the focal plane of the off-axis parabolic reflector; the target scanning range is determined based on the focal length of the off-axis parabolic reflector and the maximum angular deviation of the sensing light signal entering the off-axis parabolic reflector;

[0026] The second multimode optical fiber is used to receive the sensing optical signal and transmit the sensing optical signal to the demodulation module.

[0027] Optionally, the receiving angle of the conical lens is not less than the full field of view of the off-axis parabolic mirror.

[0028] Optionally, it also includes an image recognition unit, a control module, and multiple passive fiber Bragg grating sensing modules; each passive fiber Bragg grating sensing module is correspondingly deployed on a test object;

[0029] The image recognition unit, the demodulation module, and the first optical transceiver module are all mounted on a movable vehicle; the image recognition unit, the first optical transceiver module, and the demodulation module are all connected to the control module;

[0030] The image recognition unit is used to determine the position of the target second optical transceiver module on the target object under the control of the control module when the movable vehicle moves to the target position for detecting the target object under test.

[0031] The first optical transceiver module is used to align the light beam with the target second optical transceiver module under the control of the control module to form the transmitting optical path and the receiving optical path, and to detect the target perception information of the target object to be tested.

[0032] Optionally, the demodulation module includes a laser light source, a visible light light source, a wavelength division multiplexer, and a demodulation submodule;

[0033] The optical output terminals of the laser light source and the visible light source are both connected to the wavelength division multiplexer, and the optical output terminal of the wavelength division multiplexer is connected to the optical input terminal of the beam alignment module; the optical output terminal of the sensing light receiving module is connected to the optical input terminal of the demodulation submodule.

[0034] The wavelength division multiplexer is used to combine the laser light output from the laser source and the visible light output from the visible light source.

[0035] The beam alignment module is used to transmit the combined beam output by the wavelength division multiplexer to the optical input end of the target second optical transceiver module;

[0036] The light-sensing receiving module is used to align with the light-sensing output terminal of the second optical transceiver module under the control of the alignment mechanism after the second optical transceiver module outputs a visible light reflection signal, so as to receive the light-sensing signal transmitted from the second optical transceiver module and transmit the light-sensing signal to the demodulation submodule for demodulation.

[0037] Optionally, the alignment mechanism includes a background plate and a second moving platform; the light-sensing receiving module is fixedly connected to the second moving platform; the background plate and the second moving platform are disposed on the movable carrier, and the second moving platform is connected to the control module;

[0038] The background panel is used to display the light spot formed by the visible light reflection signal;

[0039] The image recognition unit is used to determine the position information of the light spot under the control of the control module;

[0040] The control module is used to control the second moving platform to move the sensing light receiving module based on the position information of the light spot, so that the sensing light receiving module is aligned with the sensing light output end of the target second optical transceiver module to form the receiving optical path.

[0041] Secondly, this application provides a control method applied to any of the aforementioned wireless passive fiber optic sensing systems, comprising:

[0042] Control the demodulation module to output probe light;

[0043] The first optical transceiver module and the second optical transceiver module are controlled to align their beams to form the transmitting optical path and the receiving optical path, and the sensing optical signal reflected back by the passive fiber optic grating sensing module is acquired.

[0044] The demodulation module is controlled to demodulate the sensing optical signal to obtain the target perception information of the object under test.

[0045] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art:

[0046] This application provides a wireless passive fiber optic sensing system and its control method. By introducing independent optical transceiver modules for transmitting and receiving optical signals at the system's signal demodulation end and passive sensing end, the spatial wireless optical path is decomposed into two independent and non-axial optical paths: a transmitting optical path and a receiving optical path. This avoids the security risks associated with traditional connection lines. Furthermore, by employing improved multimode fiber with a large receiving angle for optical signal reception, the system's spatial alignment tolerance is greatly improved, and the beam alignment difficulty between the signal demodulation side and the passive sensing side is reduced. This not only enhances detection security but also significantly improves system detection efficiency. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the structure of an existing fiber optic sensing system;

[0048] Figure 2 This is one of the structural schematic diagrams of the wireless passive fiber optic sensing system provided in the embodiments of this application;

[0049] Figure 3 This is a second schematic diagram of the structure of the wireless passive fiber optic sensing system provided in the embodiments of this application;

[0050] Figure 4 This is the third schematic diagram of the structure of the wireless passive fiber optic sensing system provided in the embodiments of this application;

[0051] Figure 5 This is a schematic diagram illustrating the operating principle of the optical sensing receiving module provided in the embodiments of this application;

[0052] Figure 6 This is a schematic diagram of the field-of-view matching between the off-axis parabolic reflector and the multimode fiber in the sensing optical receiving module provided in this application embodiment;

[0053] Figure 7This is the fourth schematic diagram of the wireless passive fiber optic sensing system provided in the embodiments of this application;

[0054] Figure 8 This is a flowchart illustrating the control method of the wireless passive optical fiber sensing system provided in the embodiments of this application.

[0055] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0056] 1 is a demodulation module; 11 is a laser source; 12 is a visible light source; 13 is a wavelength division multiplexer; 14 is a demodulation submodule; 2 is a passive fiber grating sensing module; 21 is a fiber grating sensor; 22 is a second optical transceiver module; 221 is a first multimode fiber; 222 is a first fiber collimator; 223 is a beam splitter; 3 is a first optical transceiver module; 31 is a sensing light receiving module; 311 is a second multimode fiber; 312 is an off-axis parabolic mirror; 313 is a first moving platform; 32 is a beam alignment module; 321 is a second fiber collimator; 322 is a two-axis galvanometer module; 4 is a movable carrier; 5 is an image recognition unit; 6 is an alignment mechanism; 61 is a background plate; 62 is a second moving platform. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0058] The terms "first" and "second," etc., used in the specification and claims of this application are used to distinguish different objects, not to describe a specific order of objects. For example, "first response message" and "second response message," etc., are used to distinguish different response messages, not to describe a specific order of response messages.

[0059] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0060] In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more, for example, multiple processing units means two or more processing units, multiple elements means two or more elements, etc.

[0061] The embodiments of this application are described below with reference to the accompanying drawings.

[0062] Figure 2 This is one of the structural schematic diagrams of the wireless passive fiber optic sensing system provided in the embodiments of this application, such as... Figure 2 As shown, the system includes:

[0063] Demodulation module 1, passive fiber Bragg grating sensing module 2, and first optical transceiver module 3;

[0064] The passive fiber grating sensing module 2 includes a fiber grating sensor 21 and a second optical transceiver module 22 connected in sequence; both the first optical transceiver module 3 and the second optical transceiver module 22 receive optical signals through a multimode optical fiber with a conical lens at one end; the first optical transceiver module 3 is connected to the demodulation module 1; the passive fiber grating sensing module 2 is used to be deployed on the object to be measured.

[0065] The first optical transceiver module 3 and the second optical transceiver module 22 are arranged relative to each other within a preset distance range, so as to form a transmitting optical path and a receiving optical path with different axes after the beam is aligned;

[0066] The transmitting optical path is used to receive the probe light output by the demodulation module 1 and transmit the probe light to the passive fiber optic grating sensing module 2.

[0067] The receiving optical path is used to receive the sensing optical signal from the passive fiber optic grating sensing module 2 and transmit the sensing optical signal to the demodulation module 1 so that the demodulation module 1 can demodulate and obtain the target perception information of the object under test.

[0068] Specifically, in the embodiments of this application, the wireless passive fiber optic sensing system may include a demodulation module, a passive fiber Bragg grating sensing module, and a first optical transceiver module. The passive fiber Bragg grating sensing module may specifically include a fiber Bragg grating sensor and a second optical transceiver module connected in sequence. It is understood that the first optical transceiver module is used to be arranged at the signal demodulation end, and the second optical transceiver module is used to be arranged at the passive sensing end.

[0069] In the embodiments of this application, the passive fiber Bragg grating sensing module includes a fiber Bragg grating sensor and a second optical transceiver module connected sequentially via single-mode optical fibers; the first optical transceiver module and the demodulation module can also be connected via single-mode optical fibers. Here, the demodulation module can adopt the demodulator structure in the prior art, or other demodulation modules capable of performing demodulation functions can be selected.

[0070] In the embodiments of this application, the first optical transceiver module and the second optical transceiver module are arranged opposite each other within a preset distance range. Each can receive optical signals through its internally installed multimode optical fiber, which is used to form a non-axial transmission optical path and a reception optical path after the two modules align their beams. Here, one end of the multimode optical fiber is processed into a conical lens; the preset distance range can specifically be 0 to 5 meters.

[0071] Thus, through the optical path design described in the embodiments of this application, the traditional coaxial optical path can be split into a physically independent transmitting optical path and a receiving optical path. The transmitting optical path can be used to transmit broadband probe light to a passive sensing end; the receiving optical path can be used to receive the sensing light signal returned from the passive sensing end.

[0072] Compared to existing spatial optical alignment schemes based on two fiber collimators using single-mode fiber (which require 4-axis adjustment and are extremely difficult due to the invisible optical axis of the passive end), this application's spatial optical communication section separates the active end's transmitting and receiving optical path functions. It uses a multimode fiber with a tapered lens at one end to receive the spatial beam, significantly improving alignment tolerance and reducing the precision requirements for spatial alignment. Here, the multimode fiber can use various core diameters to meet the detection requirements.

[0073] In one specific embodiment of this application, a multimode fiber with a core diameter of 62.5 μm can be used, with one end processed into a conical lens, allowing a receiving angle of ±25°. This means that a spatial beam with a diameter of 1 mm can be incident on the conical lens from a range of -25° to +25°, and all the light from this spatial beam can enter the core of the multimode fiber. Furthermore, the amount of light received by the 62.5 μm core diameter of the multimode fiber is 48 times that of the single-mode fiber (approximately calculated based on area). Its large numerical aperture (NA) characteristic ensures that even with significant positioning errors in the moving platform used during alignment, the beam transmitted from the transmitter can still be efficiently captured.

[0074] It's important to explain the principle of fiber Bragg grating (FBG) sensing: When a change in an external physical quantity alters the refractive index period of the grating in the fiber Bragg grating sensor, the wavelength reflected by the grating will change accordingly. For example, a grating that normally reflects only 1550nm wavelength laser light might, if subjected to external forces such as tension or temperature, change its refractive index period and begin reflecting only 1551nm wavelength laser light. Based on this principle, the magnitude of the physical quantity causing the change can be inferred from the change in the reflected laser wavelength. Depending on the packaging design, some FBG sensors can be used to measure temperature, while others can be used to measure changes in force.

[0075] Furthermore, in the embodiments of this application, in the specific implementation of system detection, through pre-positioning and calibration, the first optical transceiver module of the system signal demodulation end can be moved to a target position within the allowable positioning error range to perform beam alignment with the second optical transceiver module of the passive sensing end. At the signal demodulation end, the demodulation module outputs broadband light as probe light through a built-in laser light source. The probe light is then directed towards the passive sensing end via the connected first optical transceiver module. Due to the multimode fiber with tapered lenses at both ends, rapid beam alignment between the first optical transceiver module and the second optical transceiver module of the passive sensing end can be achieved without complex and precise adjustments, thereby forming non-axial transmission and reception optical paths. Thus, through the transmission optical path, the first optical transceiver module can transmit the probe light to the passive fiber Bragg grating sensing module. The probe light passes through the fiber Bragg grating sensor in the passive fiber Bragg grating sensing module and is reflected by the grating to form a sensing light signal. It can be understood that the sensing light signal refers to the reflected light signal carrying sensing information.

[0076] Furthermore, in the embodiments of this application, through the receiving optical path, the sensing optical signal can be output by the passive fiber optic grating sensing module, and received and transmitted to the demodulation module through the first optical transceiver module. The demodulation module can then demodulate the sensing optical signal to finally obtain the target perception information of the object under test.

[0077] Here, the target perception information can be specifically determined based on the measurement target of the object to be measured. It can be the temperature change information of the object to be measured, or the pressure change information of the object to be measured, etc.

[0078] The wireless passive fiber optic sensing system of this application introduces independent optical transceiver modules for transmitting and receiving optical signals at the system signal demodulation end and the passive sensing end, respectively. This decomposes the spatial wireless optical path into two independent and non-axial optical paths: a transmitting optical path and a receiving optical path. This avoids the security risks associated with traditional connection lines. Furthermore, the use of improved multimode fiber with a large receiving angle for optical signal reception greatly improves the system's spatial alignment tolerance and reduces the difficulty of beam alignment between the signal demodulation side and the passive sensing side. This not only enhances detection security but also significantly improves system detection efficiency.

[0079] Figure 3 This is a second schematic diagram of the wireless passive fiber optic sensing system provided in the embodiments of this application, as shown below. Figure 3 As shown, as an optional embodiment, the first optical transceiver module 3 includes a sensing optical receiving module 31 and a beam alignment module 32;

[0080] The optical input end of the beam alignment module 32 is connected to the optical output end of the demodulation module 1 to receive the probe light output by the demodulation module 1, and transmit the probe light to the optical input end of the second optical transceiver module 22 through the transmission optical path so that the passive fiber optic grating sensing module 2 reflects the sensing light signal.

[0081] The optical output terminal of the optical receiving module 31 is connected to the optical input terminal of the demodulation module 1, and is used to receive the optical signal transmitted from the second optical transceiver module 22 through the receiving optical path, and transmit the optical signal to the demodulation module 1.

[0082] Specifically, in the embodiments of this application, the first optical transceiver module may be composed of a sensing light receiving module and a beam alignment module. It is understood that the sensing light receiving module is used to receive sensing light signals and is constructed based on a multimode optical fiber with a conical lens at one end.

[0083] In the embodiments of this application, the optical input end of the beam alignment module can be connected to the optical output end of the demodulation module through a single-mode optical fiber to receive the probe light output by the demodulation module, and align itself with the optical input end of the second optical transceiver module through self-adjustment to form a transmission optical path, transmitting the probe light to the optical input end of the second optical transceiver module, and then the probe light is reflected by the passive fiber optic grating sensing module to generate a sensing light signal.

[0084] In the embodiments of this application, the optical output end of the sensing optical receiving module can be connected to the optical input end of the demodulation module through a single-mode optical fiber. In this way, after the sensing optical receiving module and the sensing optical output end of the second optical transceiver module are aligned to form a receiving optical path, the sensing optical signal transmitted from the second optical transceiver module can be received through the receiving optical path, and the sensing optical signal can be transmitted to the demodulation module for signal demodulation.

[0085] Here, it can be understood that the sensing light output terminal of the second optical transceiver module is the light output terminal on the second optical transceiver module used to output the sensing light signal.

[0086] The system in this embodiment of the application considers splitting the old coaxial optical transceiver path into a physically independent transmitting optical path and a receiving optical path. Correspondingly, the first optical transceiver module is divided into a beam alignment module and a sensing light receiving module. The beam alignment module is used to transmit probe light to the passive sensing end, and the sensing light receiving module is used to receive the sensing light reflected back from the passive sensing end. By using a multi-module coordinated adjustment method, on the one hand, the signal interference present in the traditional single-optical-path communication method can be reduced, and on the other hand, the flexibility of actual installation and operation can be increased, which is conducive to expanding the application of fiber Bragg grating sensing.

[0087] Continue to refer to Figure 3Based on the above embodiments, as an optional embodiment, the second optical transceiver module 22 includes a first multimode fiber 221, a first fiber collimator 222, and a beam splitter 223;

[0088] The optical output end of the first multimode fiber 221 is connected to the optical input end of the beam splitter 223, the optical input end of the first fiber collimator 222 is connected to the reflected light output end of the beam splitter 223, and the bidirectional port of the beam splitter 223 is connected to the fiber optic grating sensor 21; the optical input end of the first multimode fiber 221 is a conical lens, which serves as the optical input end of the second optical transceiver module 22.

[0089] The first multimode fiber and the beam alignment module are used to form the transmitting optical path, and the first fiber collimator and the sensing optical receiving module are used to form the receiving optical path.

[0090] Specifically, in the embodiments of this application, the second optical transceiver module can be composed of a first multimode fiber, a first fiber collimator, and a beam splitter. The optical output end of the first multimode fiber can be connected to the probe optical input end of the beam splitter via a single-mode fiber. The optical input end of the first fiber collimator can also be connected to the sensor optical output end of the beam splitter via a single-mode fiber. The bidirectional port at the tail of the beam splitter can be connected to a fiber Bragg grating sensor via a single-mode fiber. Here, the beam splitter can specifically be a beam splitter with a splitting ratio of 50%:50%.

[0091] Furthermore, in the embodiments of this application, the optical input end of the first multimode fiber is a conical lens, which serves as the optical input end of the second optical transceiver module and can be aligned with the beam alignment module in the first optical transceiver module to form a transmitting optical path; the optical output end of the first fiber collimator can serve as the sensing optical output end of the second optical transceiver module and can be aligned with the sensing optical receiving module in the first optical transceiver module to form a receiving optical path.

[0092] The system in this application embodiment constructs a second optical transceiver module by introducing multimode fiber, fiber collimator and beam splitter. This module, together with the sensing optical receiving module and beam alignment module of the signal demodulation end, forms a matching optical path design to decompose the spatial wireless optical path into two independent and non-axial optical paths: a transmitting optical path and a receiving optical path. In addition, the introduction of a large receiving angle multimode fiber improves the spatial alignment tolerance of the system, reduces the difficulty of aligning the spatial beam, and improves the beam alignment efficiency.

[0093] Figure 4 This is the third schematic diagram of the wireless passive fiber optic sensing system provided in the embodiments of this application, as shown below. Figure 4 As shown, based on the above embodiments, as an optional embodiment, the beam alignment module 32 includes a second fiber collimator 321 and a two-axis galvanometer module 322 arranged sequentially.

[0094] The optical input end of the second fiber collimator 321 serves as the optical input end of the beam alignment module 32, used to receive the probe light output by the demodulation module 1 and transmit the probe light to the two-axis galvanometer module 322.

[0095] The two-axis galvanometer module 322 is used to adjust the beam deflection direction of the probe light to complete the alignment with the optical input end of the second optical transceiver module 22, thus forming the transmission optical path.

[0096] Specifically, in the embodiments of this application, the beam alignment module may include a second fiber collimator and a two-axis galvanometer module arranged sequentially. The optical input end of the second fiber collimator serves as the optical input end of the beam alignment module, and is connected to the demodulation module via a single-mode fiber. It can be used to receive the probe light output by the demodulation module and transmit the probe light to the two-axis galvanometer module.

[0097] Here, the two-axis galvanometer module can specifically adopt a dual-axis galvanometer scanning structure. Its deflection adjustment function allows for precise adjustment of the deflection angle of the probe light directed towards the second optical transceiver module. Since the optical input end of the second optical transceiver module uses a multimode fiber with a tapered lens at one end for optical signal reception, it can provide a wide range of receiving angles, expanding the spatial alignment tolerance. This facilitates rapid positioning of the two-axis galvanometer module and quick alignment with the optical input end of the second optical transceiver module, forming a transmission optical path. This allows for efficient transmission of the probe light to the fiber Bragg grating sensor at the passive sensing end for signal perception.

[0098] The system in this embodiment of the application constructs a beam alignment module by using an optical fiber collimator and a two-axis galvanometer module. Combined with the flexibility of the two-axis galvanometer module's deflection adjustment and the large spatial alignment tolerance introduced by the passive sensing end, the effect of rapid beam alignment can be further improved, which is conducive to improving the efficiency of system sensing and detection.

[0099] Continue to refer to Figure 4 Based on the above embodiments, as an optional embodiment, the light sensing receiving module 31 includes a second multimode fiber 311, an off-axis parabolic reflector 312, and a first moving platform 313;

[0100] The optical input end of the off-axis parabolic mirror 312 serves as the optical input end of the sensing optical receiving module 31; the optical input end of the second multimode fiber 311 is a conical lens, and the optical output end serves as the optical output end of the sensing optical receiving module 31; the second multimode fiber 311 is arranged within the focal plane of the off-axis parabolic mirror 312 and fixed on the first moving platform 313; the focused spot diameter of the off-axis parabolic mirror 312 is smaller than the core diameter of the second multimode fiber 311;

[0101] The off-axis parabolic mirror 312 is used to receive and reflect the sensing light signal transmitted from the second optical transceiver module 22;

[0102] The first moving platform 313 is used to perform planar motion according to the target scanning range, so as to drive the second multimode fiber 311 to scan within the focal plane of the off-axis parabolic reflector 312; the target scanning range is determined based on the focal length of the off-axis parabolic reflector and the maximum angular deviation of the sensing light signal entering the off-axis parabolic reflector.

[0103] The second multimode fiber 311 is used to receive the sensing optical signal and transmit the sensing optical signal to the demodulation module 1.

[0104] Specifically, in the embodiments of this application, the sensing light receiving module can be composed of a second multimode fiber, a first moving platform, and an off-axis parabolic reflector. By abandoning the traditional lens group and introducing an off-axis parabolic reflector, light loss can be effectively reduced when focusing the beam, while providing a larger receiving field of view, further reducing the difficulty of alignment with the passive sensing end. The first moving platform can be a helical two-dimensional translation stage, a "Z"-shaped translation stage, or other translation stages that can cover the planar scanning range.

[0105] In a specific implementation, the optical input end of the off-axis parabolic mirror can be used as the optical input end of the sensing light receiving module. The optical input end of the second multimode fiber is processed into a conical lens, and its optical output end serves as the optical output end of the sensing light receiving module, connected to the demodulation module via a single-mode fiber. Simultaneously, the second multimode fiber is arranged within the focal plane of the off-axis parabolic mirror and fixed to the first moving platform. Furthermore, the focusing spot diameter of the off-axis parabolic mirror is smaller than the core diameter of the second multimode fiber. Thus, when the off-axis parabolic mirror receives the sensing light signal from the first fiber collimator in the second optical transceiver module, the first moving platform can perform planar motion according to the target scanning range, such as a spiral scanning motion, thereby driving the second multimode fiber to move synchronously and continuously scan within the focal plane of the off-axis parabolic mirror. This efficiently captures and couples the sensing light signal from the second optical transceiver module into the second multimode fiber, which then transmits the sensing light signal to the demodulation module for demodulation processing.

[0106] More specifically, in the embodiments of this application, by introducing a first moving platform to drive the second multimode fiber to perform active scanning, the alignment tolerance can be further significantly improved. This mechanism is based on the following two aspects:

[0107] 1) Physical redundancy basis: small focused spot size and large fiber core diameter.

[0108] Specifically, the focused spot diameter of the off-axis parabolic mirror It can be estimated as follows:

[0109] ;

[0110] in, λ The wavelength of light f Let be the focal length of the off-axis parabolic mirror. The diameter of the incident light beam.

[0111] In this embodiment, the core diameter of the second multimode fiber can be used. d core =62.5 μ m. Here, the parameters of a typical off-axis parabolic mirror (effective aperture) are used. D =50mm, focal length f Calculated using a beam diameter of 150mm and an incident beam diameter of 7mm, the focused spot diameter is... ≈40.5 μ m is smaller than the core diameter of the multimode fiber mentioned above. Even if there is a slight offset in the light spot, i.e., a micrometer-level offset, it can still fall completely within the core diameter range.

[0112] 2) Proactive error tolerance and compensation mechanism.

[0113] Specifically, in this embodiment, the second multimode fiber is mounted on a two-dimensional translation stage, such as... Figure 5 As shown, when the sensing beam returned by the passive sensing end has an angular deviation Δ α When the light spot formed on the focal plane of the off-axis parabolic mirror deviates from the focal point, the offset amount Δ x It can be determined by the following geometric relationship:

[0114] ;

[0115] Therefore, a two-dimensional translation stage can drive the second multimode fiber to perform XY-axis helical scanning motion within its focal plane. Let the target scanning range of the two-dimensional translation stage be Δ. x max The maximum angular deviation that the system can compensate for. for:

[0116] ;

[0117] With typical parameters (Δ) x max =10mm, f Calculation (=150mm): ≈arctan(10 / 150)≈3.8°. This angular tolerance is much larger than the positioning error of a typical AGV (Automated Guided Vehicle) or mobile robot (typically a translation error of ±10mm and an angular error of ±1°).

[0118] Therefore, even when there is a significant positioning deviation in the mobile vehicle, the active scanning mechanism described in this application embodiment can still reliably complete the optical path alignment, ensuring that the sensing optical signal is efficiently captured, which greatly improves the robustness and feasibility of the system in mobile inspection scenarios.

[0119] The system in this embodiment of the application, by introducing an optical path structure combination of an off-axis parabolic reflector and a conical lens multimode fiber, can overcome the slight divergence or angular deviation that may exist in the returned sensing beam and achieve extremely high optical coupling efficiency, forming a large field of view and high-efficiency optical receiving subsystem. It is particularly suitable for processing optical signal reception in mobile scenarios and can further improve the efficiency of system beam alignment and sensing detection.

[0120] Based on the above embodiments, as an optional embodiment, the receiving angle of the conical lens is not less than the full field of view of the off-axis parabolic mirror.

[0121] Specifically, in the embodiments of this application, before the first mobile platform drives the second multimode fiber to perform active scanning within the focal plane of the off-axis parabolic reflector, a second multimode fiber with a conical lens receiving angle not less than the full field of view of the off-axis parabolic reflector can be used to further achieve field-of-view matching and optimization between the off-axis parabolic reflector and the second multimode fiber.

[0122] like Figure 6 As shown, the combination of an off-axis parabolic mirror and a second multimode fiber with a conical lens at one end further enhances the efficiency of optical signal coupling. The key to this lies in matching the light-gathering field of view of the off-axis parabolic mirror with the receiving field of view of the multimode fiber. Here, the full field of view (FOV) of the off-axis parabolic mirror is determined by its effective aperture. D and focal length f The decision is made using the following formula:

[0123] ;

[0124] in, Ω The full field of view (in radians) of the off-axis parabolic mirror. Meanwhile, the second multimode fiber, due to its tapered lens structure at its end face, possesses a large receiving angle, denoted as . θ To ensure that the optical signal collected by the off-axis parabolic mirror throughout its entire field of view can be effectively received by the multimode fiber, the following matching conditions must be met:

[0125] θ ≥ Ω ;

[0126] When this condition is met, the combination of "off-axis parabolic mirror and second multimode fiber with a conical lens at one end" can give full play to the large field of view advantage of off-axis parabolic mirror, while ensuring that all light entering the field of view can be captured by the maximum receiving angle of multimode fiber, thereby maximizing the optical signal coupling efficiency and significantly reducing the transmission loss of sensing optical signal; on the other hand, it is also conducive to the demodulation end to scan and capture the sensing optical signal from the passive sensing end more quickly, thereby improving demodulation efficiency.

[0127] Figure 7 This is the fifth schematic diagram of the wireless passive fiber optic sensing system provided in the embodiments of this application, as shown below. Figure 7 As shown, based on the above embodiments, as an optional embodiment, the system further includes an image recognition unit 5, a control module (not shown), and multiple passive fiber Bragg grating sensing modules 2; each passive fiber Bragg grating sensing module 2 is correspondingly deployed on a test object;

[0128] The image recognition unit 5, the demodulation module 1, and the first optical transceiver module 3 are all mounted on the movable carrier 4; the image recognition unit 5, the first optical transceiver module 3, and the demodulation module 1 are all connected to the control module;

[0129] The image recognition unit 5 is used to determine the position of the second optical transceiver module 22 on the target object under the control of the control module when the movable carrier 4 moves to the target position for detecting the target object under test.

[0130] The first optical transceiver module 3 is used to align the light beam with the target second optical transceiver module 22 under the control of the control module to form a transmitting optical path and a receiving optical path, and to detect the target perception information of the target object to be measured.

[0131] Specifically, the system of this application embodiment can also be extended to mobile inspection scenarios. Specifically, the system further includes an image recognition unit, a control module, and multiple passive fiber Bragg grating sensing modules; each passive fiber Bragg grating sensing module is deployed on a corresponding object to be tested and is used to detect the target perception information of the corresponding object to be tested.

[0132] In a specific implementation, the image recognition unit, demodulation module, and first optical transceiver module can all be mounted on a mobile vehicle. This mobile vehicle can specifically include an AGV (Automated Guided Vehicle), drone, robotic dog, or other robots. Furthermore, the image recognition unit, first optical transceiver module, and demodulation module are all connected to a control module. Thus, when the mobile vehicle moves to the target location for detecting the target object, the control module can control the image recognition unit to perform visual recognition calculations, quickly locating the position of the target second optical transceiver module on the target object. Here, the target location can be a pre-set detection point for the mobile vehicle to dock; the target object can be any of multiple target objects; and it is understood that the target second optical transceiver module is the second optical transceiver module positioned on the target object.

[0133] It should be noted that, in the embodiments of this application, the control module can be set on a mobile vehicle or on a remote control terminal, and can be controlled by wired or wireless communication. This application does not make any specific limitations on this.

[0134] In embodiments of this application, the first optical transceiver module can align its beam with the target second optical transceiver module under the control of the control module to form a transmitting optical path and a receiving optical path, thereby detecting the target perception information of the target object. For example, the first optical transceiver module includes a second fiber collimator, a two-axis galvanometer module, a sensing optical receiving module, and an alignment mechanism for controlling the movement of the sensing optical receiving module. The two-axis galvanometer module and the alignment mechanism can be connected to the control module and operate under the control of the control module, thereby controlling the optical output end of the two-axis galvanometer module and the optical input end of the sensing optical receiving module to align their beams with the multimode fiber and the fiber collimator in the target second optical transceiver module, respectively, to form a transmitting optical path and a receiving optical path.

[0135] The system in this application embodiment, by integrating a wireless passive fiber optic sensing system onto mobile vehicles such as AGVs and robots, can effectively achieve a technological leap from traditional fixed monitoring to mobile inspection, greatly expanding the application scenarios of wireless passive fiber optic grating sensing technology.

[0136] Continue to refer to Figure 7 Based on the above embodiments, as an optional embodiment, the demodulation module 1 includes a laser light source 11, a visible light light source 12, a wavelength division multiplexer 13, and a demodulation submodule 14;

[0137] The optical output terminals of the laser light source 11 and the visible light source 12 are both connected to the wavelength division multiplexer 13, and the optical output terminal of the wavelength division multiplexer 13 is connected to the optical input terminal of the beam alignment module 32; the optical output terminal of the sensing light receiving module 31 is connected to the optical input terminal of the demodulation submodule 14.

[0138] The wavelength division multiplexer 13 is used to combine the laser light output from the laser source 11 and the visible light output from the visible light source 12.

[0139] The beam alignment module 32 is used to transmit the combined beam output from the wavelength division multiplexer 13 to the optical input end of the target second optical transceiver module 22;

[0140] The light receiving module 31 is used to align with the light receiving output end of the second light transceiver module 22 under the control of the alignment mechanism 6 after the second light transceiver module 22 outputs a visible light reflection signal, so as to receive the light receiving signal transmitted from the second light transceiver module 22 and transmit the light receiving signal to the demodulation submodule 14 for demodulation.

[0141] Specifically, in the embodiments of this application, the demodulation module can adopt an improved structure that differs from the structure of existing demodulators. It can specifically consist of a laser source, a visible light source, a wavelength division multiplexer (WDM), and a demodulation submodule. Specifically, the optical output ends of both the laser source and the visible light source can be connected to the WDM via single-mode optical fibers. The optical output end of the WDM is then connected to the optical input end of the beam alignment module via a single-mode optical fiber. Finally, the optical output end of the sensing light receiving module is connected to the optical input end of the demodulation submodule via a single-mode optical fiber.

[0142] Thus, when the demodulation module starts working, after the laser source outputs laser light and the visible light source outputs visible light, a wavelength division multiplexer can combine the laser light from the laser source and the visible light from the visible light source into a single beam. The combined beam is then transmitted as probe light to the beam alignment module. After beam alignment, the beam alignment module can transmit the combined beam to the optical input end of the target's second optical transceiver module. After reflection by the fiber Bragg grating sensor connected to the target's second optical transceiver module, a beam is formed that combines the visible light reflection signal and the sensor light signal.

[0143] It should be noted that multiple sensors can be pre-set and connected in sequence inside the fiber Bragg grating sensor, and the fiber Bragg grating at each sensor can reflect the corresponding wavelength.

[0144] For example, such as Figure 7As shown, broadband light in the wavelength range of 1520nm-1570nm is emitted from laser source 11, and 650nm visible light is emitted from visible light source 12. The two beams are combined by wavelength division multiplexer 13 and emitted from beam alignment module 32 through single-mode fiber to form a spatial beam with a diameter of 1 mm. The fiber optic grating sensor 21 connected to the target second optical transceiver module has four sensors pre-set from bottom to top. The first sensor reflects a wavelength of 1530nm, the second sensor reflects a wavelength of 1540nm, the third sensor reflects a wavelength of 1550nm, and the last sensor on the fiber reflects 650nm visible light. After the combined beam is transmitted to the target second optical transceiver module 22, the three wavelengths of light and the 650nm visible light are reflected back to the beam splitter 223 by the fiber grating at the corresponding sensor. One of them reaches the first fiber collimator 222 through the single-mode fiber. The three wavelengths of light plus the 650nm visible light are emitted from the first fiber collimator 222 to form a spatial light with a diameter of 1 mm, that is, the output visible light reflection signal and the sensing light signal.

[0145] Furthermore, in the embodiments of this application, when the target second optical transceiver module outputs a visible light reflection signal, the position of the visible light reflection signal on the movable carrier can be identified by combining the image recognition unit and the pre-set alignment mechanism, and the sensing light receiving module can be controlled to move to the position of the light spot, thereby aligning the light beam with the sensing light output end of the target second optical transceiver module to form a receiving optical path, thereby receiving the sensing light signal transmitted from the target second optical transceiver module, and transmitting the sensing light signal to the demodulation submodule for demodulation.

[0146] The system of this application embodiment introduces a visible indicator light source into the laser light source of the demodulation module, and introduces a wavelength division multiplexer to combine the probe light and the visible indicator light, so that the invisible passive sensing end light receiving path becomes visible, solving the problem of the invisible optical axis of the passive end. This enables a more accurate beam alignment process, further greatly improving the efficiency of system installation, debugging and moving alignment, and significantly improving the efficiency of system sensing and detection.

[0147] Continue to refer to Figure 7 Based on the above embodiments, as an optional embodiment, the alignment mechanism 6 includes a background plate 61 and a second moving platform 62; the light-sensing receiving module 31 is fixedly connected to the second moving platform 62; the background plate 61 and the second moving platform 62 are disposed on the movable carrier 4, and the second moving platform 62 is connected to the control module.

[0148] Background panel 61 is used to display the light spot formed by the reflected visible light signal;

[0149] The image recognition unit 5 is used to determine the position information of the light spot under the control of the control module;

[0150] The control module is used to control the second moving platform 62 to move the sensing light receiving module 31 based on the position information of the light spot, so that the sensing light receiving module 31 is aligned with the sensing light output end of the target second optical transceiver module 22 to form a receiving optical path.

[0151] Specifically, in this embodiment, the alignment mechanism for controlling the movement of the light-receiving module can be composed of a background plate and a second moving platform. The second moving platform can be a robotic arm or a two-dimensional translation stage, etc.; the background plate can be a whiteboard for easy and rapid identification of colored light spots.

[0152] In a specific implementation, the light-receiving module can be fixedly connected to the second mobile platform, and both the second mobile platform and the background plate can be fixed to the movable carrier. The background plate can be configured based on the spatial distribution between the movable carrier and the second optical transceiver module during measurement, ensuring that the visible light beam output by the second optical transceiver module falls on the background plate. Simultaneously, the second mobile platform is electrically connected to the control module. Thus, when the visible light reflection signal output by the target second optical transceiver module is directed towards the background plate, a light spot formed by the reflected signal can be displayed on the background plate. The control module can then control the image recognition unit to identify the light spot and quickly determine its location.

[0153] Furthermore, in the embodiments of this application, the control module can control the second moving platform to continuously move the sensing light receiving module toward the position of the light spot based on the position information of the light spot, until the moving sensing light receiving module reaches the position of the light spot, so that the light input end of the sensing light receiving module is aligned with the sensing light output end of the target second optical transceiver module to form a receiving optical path.

[0154] For example, when the sensing light receiving module includes a fixed second multimode fiber and an off-axis parabolic reflector, the second moving platform is controlled to continuously move the sensing light receiving module towards the light spot position until it reaches the light spot position, aligning the off-axis parabolic reflector with the first fiber collimator in the target second optical transceiver module to form a receiving optical path. At this time, the light spot and the combined sensing light signal can be projected onto the off-axis parabolic reflector together, thus ensuring that the sensing light signal is reflected to the second multimode fiber until it is transmitted to the demodulation module for signal demodulation.

[0155] The system of this application embodiment utilizes the visual field of view achieved by the passive sensing end receiving and receiving light path, and adopts image recognition method to quickly locate the visible light spot, thereby realizing the rapid alignment of the sensing light receiving module and the sensing light output end of the second optical transceiver module. The method is reliable and convenient, which is conducive to further improving the efficiency and stability of the system's sensing detection.

[0156] Continue to refer to Figure 7 In one specific embodiment of this application, the object under test is a high-voltage electrical cabinet, and the system is used to detect the temperature at points on the high-voltage electrical cabinet. A wireless passive fiber optic grating sensing module 2 (and...) is installed on the object under test. Figure 3 , Figure 4 (The passive fiber Bragg grating sensor module 2 is the same as that in the example). For instance, if there are four high-voltage electrical cabinets in a substation that require temperature measurement, four passive fiber Bragg grating sensor modules 2 are installed on these four high-voltage electrical cabinets respectively, and each grating sensor is attached to the point where temperature measurement is required.

[0157] In this embodiment, a stop point for the AGV is pre-set in front of each high-voltage electrical cabinet. Typically, the distance between the AGV and the passive fiber optic grating sensing module 2 is approximately 2-5 meters. When inspection is required, the AGV stops at this point. The industry standard for AGV parking positioning accuracy is generally ±10mm, plus an angular offset of ±1°. At this accuracy, achieving alignment of two 1mm beams using existing fiber optic collimators with invisible passive optical axes is extremely difficult.

[0158] Furthermore, in this embodiment, after the AGV vehicle stops, the image recognition unit 5 identifies the position of the second optical transceiver module 22 in the passive fiber optic grating sensing module 2, and then activates the laser source 11 in the demodulation module 1 to emit broadband light in the wavelength range of 1530nm-1570nm, and the visible light source 12 to emit 650nm visible light; the two beams of light are combined by the wavelength division multiplexer 13, transmitted through the single-mode fiber to the second fiber collimator 321, and emitted after adjusting the two-axis galvanometer module 322 to form a spatial beam with a diameter of 1 mm. At the same time, the two-axis galvanometer module 322 deflects the combined beam of 650nm visible light and 1530nm-1570nm broadband light emitted from the second fiber collimator 321, and aligns it with the first multimode fiber 221 in the second optical transceiver module 22 to form a transmission optical path, thereby transmitting the light into the first multimode fiber 221. Because the conical lens at the front end of the multimode fiber has a large receiving angle, the parking accuracy of the AGV does not affect the receiving angle of the conical lens. Here, since the synthesized beam contains visible light with a wavelength of 650nm, the spatial position of the beam is easily identified. Therefore, the aforementioned method of setting a background plate and identifying the light spot can be used to further perform high-precision beam alignment.

[0159] For example, after the image recognition unit 5 identifies the position of the second optical transceiver module 22, a red beam is emitted from the two-axis galvanometer module 322, which will create a noticeable red spot near the second optical transceiver module 22. The deviation between the spot and the second optical transceiver module 22 is calculated through visual recognition, and then the two-axis galvanometer module 322 is driven to change the position of the spot until the spot is aligned with the receiving end of the second optical transceiver module 22.

[0160] Furthermore, when the synthesized light beam reaches each grating, the light of the corresponding wavelength is reflected back, forming a sensing light signal. This signal is then directed to the AGV vehicle via the first fiber collimator 222 of the second optical transceiver module 22. Since this sensing light signal also carries visible light with a wavelength of 650nm, its spatial position is easily identified using the aforementioned recognition method. For example, a 0.3m x 0.3m background board 61, such as a whiteboard, can be placed near the robotic arm 62. The position of the reflected red light spot on the whiteboard can be determined by the image recognition unit 5 through visual recognition calculations. This information is then sent to the robotic arm 62 to drive the sensing light receiving module 31 to move to the beam alignment position for beam alignment, forming a receiving optical path to receive the sensing light signal.

[0161] Finally, the sensing light signal beam can be output from the second multimode fiber 311 in the sensing light receiving module 31 and reach the demodulation submodule 14 in the demodulation module 1. The physical values, such as temperature values, at each grating sensor in the passive fiber optic grating sensing module 2 are obtained through signal demodulation.

[0162] The control method of the wireless passive optical fiber sensing system provided in this application is described below. The control method of the wireless passive optical fiber sensing system described below can be referred to in correspondence with the wireless passive optical fiber sensing system described above.

[0163] Figure 8 This is a flowchart illustrating the control method of the wireless passive fiber optic sensing system provided in this application embodiment, which can be applied to any of the aforementioned wireless passive fiber optic sensing systems, such as... Figure 8 As shown, the method includes:

[0164] Step S10: Control the demodulation module to output probe light;

[0165] Step S20: Control the first optical transceiver module and the second optical transceiver module to align the beams to form a transmitting optical path and a receiving optical path, and acquire the sensing optical signal reflected back by the passive fiber optic grating sensing module.

[0166] Step S30: Control the demodulation module to demodulate the sensing optical signal to obtain the target perception information of the object under test.

[0167] It is understood that detailed implementation methods for each of the above steps can be found in the descriptions of the various functional modules in the aforementioned system embodiments, and will not be repeated here.

[0168] The control method of the wireless passive fiber optic sensing system in this application introduces independent optical transceiver modules for transmitting and receiving optical signals at the system signal demodulation end and the passive sensing end, respectively. This decomposes the spatial wireless optical path into two independent and non-axial optical paths: a transmitting optical path and a receiving optical path. This avoids the security risks associated with traditional connection lines. Furthermore, the use of improved multimode fiber with a large receiving angle for optical signal reception greatly improves the system's spatial alignment tolerance and reduces the difficulty of beam alignment between the signal demodulation side and the passive sensing side. This not only enhances detection security but also significantly improves system detection efficiency.

[0169] Based on the methods in the above embodiments, this application provides a computer-readable storage medium storing a computer program that, when run on a processor, causes the processor to execute the methods in the above embodiments.

[0170] Based on the methods in the above embodiments, this application provides a computer program product that, when run on a processor, causes the processor to execute the methods in the above embodiments.

[0171] It is understood that the processor in the embodiments of this application can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor can be a microprocessor or any conventional processor.

[0172] The method steps in this application embodiment can be implemented in hardware or by a processor executing software instructions. The software instructions can consist of corresponding software modules, which can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, portable hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can reside in an ASIC.

[0173] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state disk (SSD)).

[0174] It is understood that the various numerical designations used in the embodiments of this application are merely for the convenience of description and are not intended to limit the scope of the embodiments of this application.

[0175] It should be understood that expressions such as “comprising” and “may include” used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as “comprising” and / or “having” are to be interpreted as indicating a particular characteristic, number, operation, constituent element, component, or combination thereof, but not to exclude the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0176] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. "Fixed connection" refers to a connection where the relative positional relationship remains unchanged after connection. "Rotary connection" refers to a connection where the components can rotate relative to each other after connection. "Sliding connection" refers to a connection where the components can slide relative to each other after connection. The directional terms mentioned in the embodiments of this application, such as "top," "bottom," "inner," "outer," "left," and "right," are only for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of this application, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0177] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A wireless passive fiber optic sensing system, characterized in that, include: Demodulation module, passive fiber Bragg grating sensing module, and first optical transceiver module; The passive fiber grating sensing module includes a fiber grating sensor and a second optical transceiver module connected in sequence; both the first and second optical transceiver modules receive optical signals through a multimode optical fiber with a conical lens at one end; the first optical transceiver module is connected to the demodulation module; the passive fiber grating sensing module is used to be deployed on the object to be measured. The first optical transceiver module and the second optical transceiver module are arranged relative to each other within a preset distance range, and are used to form a transmitting optical path and a receiving optical path with different axes after the beam is aligned; The transmitting optical path is used to receive the probe light output by the demodulation module and transmit the probe light to the passive fiber optic grating sensing module. The receiving optical path is used to receive the sensing optical signal transmitted from the passive fiber optic grating sensing module and transmit the sensing optical signal to the demodulation module so that the demodulation module can demodulate and obtain the target perception information of the object under test.

2. The wireless passive fiber optic sensing system according to claim 1, characterized in that, The first optical transceiver module includes a sensing optical receiving module and a beam alignment module; The optical input end of the beam alignment module is connected to the optical output end of the demodulation module, and is used to receive the probe light output by the demodulation module, and transmit the probe light to the optical input end of the second optical transceiver module through the transmission optical path, so that the passive fiber grating sensing module reflects the sensing light signal. The optical output terminal of the sensing optical receiving module is connected to the optical input terminal of the demodulation module, and is used to receive the sensing optical signal transmitted from the second optical transceiver module through the receiving optical path, and transmit the sensing optical signal to the demodulation module.

3. The wireless passive fiber optic sensing system according to claim 2, characterized in that, The second optical transceiver module includes a first multimode fiber, a first fiber collimator, and a beam splitter; The optical output end of the first multimode fiber is connected to the probe optical input end of the beam splitter, the optical input end of the first fiber collimator is connected to the sensor optical output end of the beam splitter, and the bidirectional port of the beam splitter is connected to the fiber grating sensor; the optical input end of the first multimode fiber is a conical lens, which serves as the optical input end of the second optical transceiver module. The first multimode fiber and the beam alignment module are used to form the transmitting optical path, and the first fiber collimator and the sensing light receiving module are used to form the receiving optical path.

4. The wireless passive fiber optic sensing system according to claim 2, characterized in that, The beam alignment module includes a second fiber collimator and a two-axis galvanometer module arranged sequentially. The optical input end of the second fiber collimator serves as the optical input end of the beam alignment module, used to receive the probe light output by the demodulation module and transmit the probe light to the two-axis galvanometer module; The two-axis galvanometer module is used to adjust the beam deflection direction of the probe light to align with the optical input end of the second optical transceiver module, thus forming the transmission optical path.

5. The wireless passive fiber optic sensing system according to claim 2, characterized in that, The sensing light receiving module includes a second multimode fiber, an off-axis parabolic reflector, and a first moving platform. The optical input end of the off-axis parabolic reflector serves as the optical input end of the sensing optical receiving module; the optical input end of the second multimode fiber is a conical lens, and the optical output end serves as the optical output end of the sensing optical receiving module; the second multimode fiber is arranged within the focal plane of the off-axis parabolic reflector and fixed on the first moving platform; the focused spot diameter of the off-axis parabolic reflector is smaller than the core diameter of the second multimode fiber; The off-axis parabolic mirror is used to receive and reflect the sensing light signal transmitted from the second optical transceiver module; The first mobile platform is used to perform planar motion according to the target scanning range, so as to drive the second multimode fiber to scan within the focal plane of the off-axis parabolic reflector; the target scanning range is determined based on the focal length of the off-axis parabolic reflector and the maximum angular deviation of the sensing light signal entering the off-axis parabolic reflector; The second multimode optical fiber is used to receive the sensing optical signal and transmit the sensing optical signal to the demodulation module.

6. The wireless passive fiber optic sensing system according to claim 5, characterized in that, The receiving angle of the conical lens is not less than the full field of view of the off-axis parabolic mirror.

7. The wireless passive fiber optic sensing system according to any one of claims 2-6, characterized in that, It also includes an image recognition unit, a control module, and multiple passive fiber Bragg grating sensing modules; each passive fiber Bragg grating sensing module is correspondingly deployed on a test object; The image recognition unit, the demodulation module, and the first optical transceiver module are all mounted on a movable vehicle; the image recognition unit, the first optical transceiver module, and the demodulation module are all connected to the control module; The image recognition unit is used to determine the position of the target second optical transceiver module on the target object under the control of the control module when the movable vehicle moves to the target position for detecting the target object under test. The first optical transceiver module is used to align the light beam with the target second optical transceiver module under the control of the control module to form the transmitting optical path and the receiving optical path, and to detect the target perception information of the target object to be tested.

8. The wireless passive fiber optic sensing system according to claim 7, characterized in that, The demodulation module includes a laser light source, a visible light light source, a wavelength division multiplexer, and a demodulation submodule; The optical output terminals of the laser light source and the visible light source are both connected to the wavelength division multiplexer, and the optical output terminal of the wavelength division multiplexer is connected to the optical input terminal of the beam alignment module; the optical output terminal of the sensing light receiving module is connected to the optical input terminal of the demodulation submodule. The wavelength division multiplexer is used to combine the laser light output from the laser source and the visible light output from the visible light source. The beam alignment module is used to transmit the combined beam output by the wavelength division multiplexer to the optical input end of the target second optical transceiver module; The light-sensing receiving module is used to align with the light-sensing output terminal of the second optical transceiver module under the control of the alignment mechanism after the second optical transceiver module outputs a visible light reflection signal, so as to receive the light-sensing signal transmitted from the second optical transceiver module and transmit the light-sensing signal to the demodulation submodule for demodulation.

9. The wireless passive fiber optic sensing system according to claim 8, characterized in that, The alignment mechanism includes a background plate and a second moving platform; the light-sensing receiving module is fixedly connected to the second moving platform; the background plate and the second moving platform are disposed on the movable carrier, and the second moving platform is connected to the control module. The background panel is used to display the light spot formed by the visible light reflection signal; The image recognition unit is used to determine the position information of the light spot under the control of the control module; The control module is used to control the second moving platform to move the sensing light receiving module based on the position information of the light spot, so that the sensing light receiving module is aligned with the sensing light output end of the target second optical transceiver module to form the receiving optical path.

10. A control method applied to a wireless passive fiber optic sensing system as described in any one of claims 1-9, characterized in that, include: Control the demodulation module to output probe light; The first optical transceiver module and the second optical transceiver module are controlled to align their beams to form the transmitting optical path and the receiving optical path, and the sensing optical signal reflected back by the passive fiber optic grating sensing module is acquired. The demodulation module is controlled to demodulate the sensing optical signal to obtain the target perception information of the object under test.

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