Ultrasonic detection system and method based on all optical fibers

Abstract

The invention discloses an ultrasonic detection system and method based on all optical fibers, and relates to the technical field of photoacoustic detection. The system comprises a light-induced ultrasonic transmitting module, an optical ultrasonic sensing module and an all-optical ultrasonic probe (3), the photoinduced ultrasonic transmitting module comprises a pulse laser (1) and a first optical fiber (2); the optical ultrasonic sensing module comprises a second optical fiber (5), a third optical fiber (6), a fourth optical fiber (7), a circulator and isolator (8), a photoelectric detector (9), a tunable laser (10), an acquisition card (11) and a computer (12); and the all-optical ultrasonic probe (3) comprises an optical fiber ultrasonic transmitting group (3-1) and an optical ultrasonic sensing group (3-2). The probe design is improved, the manufacturing process and the system structure are optimized, the manufacturing repeatability and the performance consistency are improved, meanwhile, the contrast ratio and the resolution ratio of imaging are improved, and noise interference is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of photoacoustic detection, and in particular to an all-optical fiber-based ultrasonic detection system and method. Background Art

[0002] In the field of modern medical imaging technology, photoacoustic imaging technology, as an innovative technical paradigm combining endoacoustics and optics, provides a unique perspective and method for disease diagnosis. By irradiating tissue with short-pulse lasers, the irradiated area generates ultrasonic signals due to thermal elastic expansion. The ultrasonic sensor can detect the acoustic wave signals and reconstruct tissue images. This technology can accurately diagnose vulnerable plaques in blood vessels at an early stage and provide timely intervention.

[0003] The essence of both photoacoustic imaging technology and ultrasonic imaging technology is the detection of ultrasonic waves, that is, the echo detection after the interaction between ultrasound and tissue and the ultrasonic imaging generated after the interaction between light waves and tissue. Therefore, ultrasonic detection technology is the key part to ensure the quality of its imaging. According to the ultrasonic detection mechanism, the currently widely used ultrasonic detection schemes can be divided into piezoelectric transducers, micromechanical transducers and the emerging all-optical ultrasonic detection technology. Among them, all-optical ultrasonic detection technology has the potential to become the next generation of ultrasonic detection technology due to its advantages such as small size, high imaging contrast, simple sensor array structure, no need for a lot of wiring and no electromagnetic interference. The all-optical ultrasonic detection system is generally composed of a photoacoustic transmitter and an optical ultrasonic sensor made of optical fiber devices. The photoacoustic transmitter can provide sound pressure and wider bandwidth comparable to or even higher than that of a piezoelectric transducer. The optical ultrasonic sensor has higher sensitivity and higher frequency response than piezoelectric elements of the same size. At the same time, thanks to the light-guiding and anti-electromagnetic interference properties of optical fibers, the all-optical ultrasonic detection device is easy to combine with the photoacoustic imaging system and even with the magnetic resonance imaging system, which is suitable for complex clinical applications.

[0004] Although all-optical ultrasound detection technology has many potentials, it still faces a series of severe challenges when it is actually applied to scenarios such as vascular disease detection. From the perspective of probe design and manufacturing process, traditional all-optical ultrasound probes have many defects. First, its manufacturing process is complex and lacks standardized processes, resulting in large differences in performance between probes produced in different batches, and repeatability and consistency are difficult to guarantee. For example, when detecting micro-lesions in blood vessels, this performance difference may lead to misjudgment or omission of lesion characteristics, seriously affecting the accuracy of diagnosis. Secondly, the structural design of traditional all-optical ultrasound probes is not optimized enough, which makes its imaging contrast and resolution relatively low, making it difficult to clearly distinguish the different hierarchical structures in the vascular wall and the detailed features of micro-lesions, such as the lipid core and fibrous cap in vascular plaques. In addition, the noise interference problem is more prominent in traditional all-optical ultrasound detection systems. External environmental noise and optical and electrical noise inside the system are easily mixed into the ultrasound signal, reducing the signal-to-noise ratio, further deteriorating the imaging quality, and causing great trouble to clinical diagnosis.

[0005] Therefore, it is an urgent problem for those skilled in the art to propose an all-fiber-based ultrasonic detection system and method to solve the difficulties existing in the prior art. Summary of the invention

[0006] In view of this, the present invention provides an all-optical fiber-based ultrasonic detection system and method, which uses optical fiber to improve probe design, optimize manufacturing process and system structure, improve manufacturing repeatability and performance consistency, while improving imaging contrast and resolution, and reducing noise interference.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] An all-optical ultrasonic detection system, comprising: a photo-ultrasonic emission module, an optical ultrasonic sensor module, and an all-optical ultrasonic probe;

[0009] The photo-ultrasound emission module includes: a pulse laser and a first optical fiber;

[0010] The optical ultrasonic sensor module includes: a second optical fiber, a third optical fiber, a fourth optical fiber, a circulator and an isolator, a photoelectric detector, a tunable laser, an acquisition card, and a computer;

[0011] The all-optical ultrasound probe includes: an optical fiber ultrasound transmitting group and an optical ultrasound sensing group;

[0012] The pulse laser in the photo-ultrasound transmitting module is connected to the optical fiber ultrasound transmitting group of the all-optical ultrasound probe through the first optical fiber;

[0013] The tunable laser in the optical ultrasonic sensing module is connected to the circulator and the isolator through the third optical fiber, the acquisition card is connected to the circulator and the isolator through the fourth optical fiber via the photoelectric detector, the computer is connected to the acquisition card through the fourth optical fiber, and the circulator and the isolator are connected to the optical ultrasonic sensing group of the all-optical ultrasonic probe through the second optical fiber.

[0014] In the above system, optionally, in the photo-ultrasound transmitting module, the pulse laser provides a pulse light source for the optical fiber ultrasound transmitting group;

[0015] The fiber-optic ultrasound transmitter group consists of four identical photo-induced ultrasound transmitters;

[0016] The first optical fiber is a multimode optical fiber, and the optical fiber ultrasonic transmitting groups are all based on the multimode optical fiber to construct a composite film layer;

[0017] The composite film layer comprises: polydimethylsiloxane, multi-walled carbon nanotubes and molybdenum disulfide materials, or polydimethylsiloxane, multi-walled carbon nanotubes and graphene materials;

[0018] Polydimethylsiloxane is a thermoelastic expansion layer;

[0019] The light absorbing coating in the photo-induced ultrasound composite film layer includes: light absorbing particles, thermal conductive materials and polydimethylsiloxane, the light absorbing particles and the thermal conductive materials exist in a mixed state, multi-walled carbon nanotubes or graphene are light absorbing particles, and molybdenum disulfide or graphene is used as thermal conductive materials.

[0020] In the above-mentioned system, optionally, the pulse laser emits a pulse laser, which acts on the light absorbing coating through the first optical fiber. Under the excitation of the incident pulse light, the light absorbing coating converts light energy into heat energy and quickly transfers it to the thermoelastic expansion layer. The thermoelastic expansion layer expands due to the heat, and when there is no light, the thermoelastic expansion layer begins to contract after the heat energy is no longer acted on, thereby converting the heat energy into ultrasonic mechanical energy.

[0021] In the above system, optionally, in the optical ultrasonic sensor module, the tunable laser is the detection light source of the optical ultrasonic sensor group, the acquisition card is used to collect ultrasonic echo signals, the computer is used for real-time three-dimensional imaging, the photodetector converts the optical signal into an electrical signal, and a circulator and an isolator are provided at the front end of the photodetector and the tunable laser;

[0022] The second optical fiber, the third optical fiber, and the fourth optical fiber are all single-mode optical fibers;

[0023] The optical ultrasonic sensor group consists of Fabry-Perot FP sensor and fiber Bragg grating FBG sensor;

[0024] The FP sensor is composed of single-mode optical fiber, hollow-core optical fiber, and vibration-sensitive membrane; the FBG sensor is composed of single-mode optical fiber and fiber grating;

[0025] In the optical FP sensor, the second optical fiber and the end face of the hollow-core optical fiber serve as the first reflection surface, the vibration sensitive film serves as the second reflection surface, and the hollow-core optical fiber serves as the light wave transmission path.

[0026] In the above system, optionally, a tunable laser emits a light source, which passes through a third optical fiber, a circulator and an isolator, and a second optical fiber. In the optical FP sensor, the second optical fiber and the end face of the hollow-core optical fiber are reflected for the first time, and the transmitted light is transmitted in the hollow-core optical fiber to the vibration-sensitive film for the second time. The light is coupled back to the second optical fiber again through the hollow-core optical fiber transmission, and interferes with the first reflected light. When the front ultrasonic wave acts on the vibration-sensitive film of the optical FP sensor, the vibration-sensitive film in the non-fixed area will be deformed, and the sensor cavity length will also change accordingly, thereby realizing the modulation of the interference spectrum.

[0027] When ultrasonic waves are applied to the FBG sensor from the side, the mechanical vibration induced by the ultrasonic waves causes strain in the single-mode optical fiber where the FBG sensor is located, resulting in changes in the period and effective refractive index of the fiber grating, and corresponding changes in the wavelength of the reflected light.

[0028] The wavelength change information of reflected light received by multiple FBG sensors at different positions is accurately collected and processed, and an optical image reflecting the changes in the internal structure or characteristics of the detected object is reconstructed using a specific imaging algorithm.

[0029] An all-optical fiber-based ultrasonic detection method, comprising:

[0030] S1, pulse laser emits laser pulses;

[0031] S2, the fiber optic ultrasound transmitting group generates ultrasound waves under the action of pulsed laser;

[0032] S3, the ultrasonic wave acts on the sample to be tested, and the sample to be tested radiates part of the ultrasonic wave;

[0033] S4, the divergent ultrasonic wave is received by the optical ultrasonic sensor group, and at the same time, the tunable laser emits a detection laser to act on the optical ultrasonic sensor group to receive;

[0034] S5, the FP cavity length and the period and effective refractive index of the fiber grating are changed to achieve modulation of the interference spectrum;

[0035] S6, the tunable laser emits a detection laser, and the reflected interference light is used to obtain an ultrasonic echo signal via a photoelectric detector and an acquisition card;

[0036] S7. The computer analyzes and processes the ultrasonic echo signal to perform three-dimensional imaging.

[0037] It can be seen from the above technical solutions that, compared with the prior art, the present invention provides an all-optical fiber-based ultrasound detection system and method, which has the following beneficial effects: 1) The all-optical ultrasound probe produced by the present invention is divided into a photo-ultrasound transmitting group and an optical ultrasound sensing group. The diameter of the all-optical ultrasound probe is less than 1.5 mm, and the size is small. The improved probe design realizes integrated transmission and reception, which is suitable for the detection of vascular diseases; 2) The photo-ultrasound transmitting group is composed of four photo-ultrasound transmitting probes. When the ultrasound wave is excited, the photo-ultrasound transmitting group can realize the superposition of the emitted ultrasound wave, which can improve the image contrast and make the acoustic impedance difference between the target object and the surrounding tissue more obvious, which is conducive to the imaging of vascular plaques; 3) It can enhance the signal strength and resolution, and accurately capture details such as the boundary and internal echo of thyroid nodules; 4) It can reduce noise interference, so as to make the image clearer, reduce blur and artifacts, and contribute to more accurate ultrasound diagnosis; 5) The system structure and manufacturing process are optimized, the manufacturing process is simple, and the repeatability of the later device manufacturing and the consistency of performance are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0039] Figure 1 An overall schematic diagram of an all-optical fiber-based ultrasonic detection system provided by the present invention;

[0040] Figure 2 A schematic diagram of the working principle of an all-optical fiber-based ultrasonic detection system provided by the present invention;

[0041] Figure 3 A flow chart of an all-optical fiber-based ultrasonic detection method provided by the present invention;

[0042] Description of reference numerals:

[0043] 1 is a pulsed laser; 2 is a first optical fiber; 3 is an all-optical ultrasonic probe, 3-1 is an optical fiber ultrasonic transmitting group, 3-2 is an optical ultrasonic sensing group; 4 is a sample to be tested; 5 is a second optical fiber; 6 is a third optical fiber; 7 is a fourth optical fiber; 8 is a circulator and an isolator; 9 is a photodetector; 10 is a tunable laser; 11 is an acquisition card; 12 is a computer; 13 is a light absorbing coating; 14 is a thermoelastic expansion layer; 15 is a first reflecting surface; 16 is a hollow core optical fiber; 17 is a vibration sensitive film; and 18 is a fiber grating. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] In this application, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, the elements defined by the sentence "comprise one..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0046] Reference Figure 1 As shown, the present invention discloses an all-optical ultrasonic detection system, comprising: a photo-induced ultrasonic emission module, an optical ultrasonic sensing module, and an all-optical ultrasonic probe 3;

[0047] The photo-ultrasound emission module comprises: a pulse laser 1, a first optical fiber 2;

[0048] The optical ultrasonic sensor module includes: a second optical fiber 5, a third optical fiber 6, a fourth optical fiber 7, a circulator and an isolator 8, a photodetector 9, a tunable laser 10, an acquisition card 11, and a computer 12;

[0049] The all-optical ultrasound probe 3 includes: an optical fiber ultrasound transmitting group 3-1 and an optical ultrasound sensing group 3-2;

[0050] The pulse laser 1 in the photo-ultrasound transmitting module is connected to the optical fiber ultrasound transmitting group 3-1 of the all-optical ultrasound probe 3 through the first optical fiber 2;

[0051] The tunable laser 10 in the optical ultrasonic sensing module is connected to the circulator and isolator 8 through the third optical fiber 6, the acquisition card 11 is connected to the circulator and isolator 8 through the fourth optical fiber 7 via the photodetector 9, the computer 12 is connected to the acquisition card 11 through the fourth optical fiber 7, and the circulator and isolator 8 is connected to the optical ultrasonic sensing group 3-2 of the all-optical ultrasonic probe 3 through the second optical fiber 5.

[0052] Further, in the photo-ultrasound transmitting module, the pulse laser 1 provides a pulse light source for the fiber optic ultrasound transmitting group 3-1, and the excitation frequency range of the pulse laser is 400nm-1100nm, the current range is 50mA-600mA, the pulse width range is 5ns-50ns, and the repetition frequency range is 10Hz-1 MHz;

[0053] The optical fiber ultrasound transmitter group 3-1 is composed of 4 identical photo-ultrasound transmitters;

[0054] The first optical fiber 2 is a multimode optical fiber, and the optical fiber ultrasonic transmitting group 3-1 uses the multimode optical fiber as a substrate to construct a composite film layer, and the thickness of the composite film layer is 15um-25um;

[0055] The composite film layer includes: polydimethylsiloxane, multi-walled carbon nanotubes and molybdenum disulfide (the ratio of multi-walled carbon nanotubes to molybdenum disulfide is 1 to 1.5:1) materials, or polydimethylsiloxane, multi-walled carbon nanotubes and graphene materials (the ratio of multi-walled carbon nanotubes to graphene materials is 1:1 to 2);

[0056] Polydimethylsiloxane is the base material of the photo-induced ultrasound composite film layer and is the thermoelastic expansion layer 14;

[0057] The light absorbing coating 13 in the photo-induced ultrasound composite film layer comprises: light absorbing particles, a thermal conductive material and polydimethylsiloxane, the light absorbing particles and the thermal conductive material are in a mixed state, multi-walled carbon nanotubes or graphene are light absorbing particles, molybdenum disulfide or graphene is used as a thermal conductive material, and the thickness of the light absorbing coating 13 is 8um-10um;

[0058] Furthermore, the combination of multi-walled carbon nanotubes and graphene can improve the efficiency of light-to-heat conversion and can also conduct heat. After the two are combined, on the one hand, they can increase the area and path of light absorption, broaden the absorption spectrum range through complementary effects, and absorb more photon energy; on the other hand, they can build an efficient heat conduction channel, convert the absorbed light energy into heat energy more quickly and effectively transfer it, reduce heat loss, and thus improve the overall efficiency of light-to-heat conversion;

[0059] Furthermore, the proportion of polydimethylsiloxane (PDMS) in the light absorbing coating 13 is less than 10%. The role of polydimethylsiloxane (PDMS) is to wrap the light absorbing particles and the thermal conductive material, and to firmly coat the light absorbing coating 13 on the end face of the optical fiber. When the proportion of PDMS is less than 10%, on the one hand, the transparency of the PDMS material is very high, and a small proportion will not affect the transmission of the pulsed laser. On the other hand, the light absorbing particles and the thermal conductive material play a role similar to a crossbeam support inside the light absorbing coating 13. They cooperate with an appropriate amount of PDMS to jointly construct a stable and reasonable coating structure. At the same time, a small proportion of PDMS can significantly reduce the deformation ability of the light absorbing layer due to heat, which has a positive significance for maintaining the performance stability of the light absorbing coating under different working conditions.

[0060] Specifically, the light absorbing coating 13 and the thermoelastic expansion layer 14 both contain PDMS. In order to achieve accurate and effective coating operation, the present invention is based on the screen printing method, selects a 20-50 mesh screen, and casts a mixture of a certain proportion of the light absorbing layer (polydimethylsiloxane and multi-walled carbon nanotubes & graphene, or polydimethylsiloxane and multi-walled carbon nanotubes & molybdenum disulfide, polydimethylsiloxane (PDMS) accounts for less than 10%) on the screen, removes the excess with a scraper, retains the mixture in the screen grid, and stands for 3-5 minutes at 60-80°C, then uses a three-dimensional adjustment frame to pass the optical fiber through the grid, so that the mixture is transferred to the end face of the optical fiber, thereby controlling the thickness of the light absorbing coating 13, and the thermoelastic expansion layer 14 (polydimethylsiloxane) is also made by this method. This coating method and the supporting control means not only improve the repeatability of the production capability when making the relevant coating, but also ensure the consistency of the performance of the transmitter in the production process of different batches, which plays an important role in improving the reliability of the entire device and standardized production.

[0061] Further, see Figure 2 As shown, the pulse laser 1 emits a pulse laser, which acts on the light absorbing coating 13 through the first optical fiber 2. The light absorbing coating 13 converts light energy into heat energy under the excitation of the incident pulse light, and quickly transfers it to the thermoelastic expansion layer 14. The thermoelastic expansion layer 14 expands due to the heat. When there is no light, the thermoelastic expansion layer 14 begins to contract after there is no heat energy, and converts the heat energy into ultrasonic mechanical energy.

[0062] Further, in the optical ultrasonic sensor module, the tunable laser 10 is the detection light source of the optical ultrasonic sensor group 3-2, the acquisition card 11 is used to display the ultrasonic echo signal, the photodetector 9 converts the optical signal into an electrical signal, and a circulator and an isolator 8 are provided at the front end of the photodetector 9 and the tunable laser 10;

[0063] The second optical fiber 5, the third optical fiber 6, and the fourth optical fiber 7 are all single-mode optical fibers;

[0064] The optical ultrasonic sensor group 3-2 is composed of Fabry-Perot FP sensors and fiber Bragg grating 18FBG sensors. The FP and FBG sensors are arranged alternately, with a total of 8 sensors. The FP sensor detects the front ultrasonic wave, and the FBG sensor receives the side ultrasonic wave. In this way, real-time three-dimensional imaging can be performed by only giving the probe a certain forward step.

[0065] The FP sensor is composed of a single-mode optical fiber, a hollow-core optical fiber 16, and a vibration-sensitive membrane 17; the FBG sensor is composed of a single-mode optical fiber and a fiber grating 18;

[0066] In the optical FP sensor, the second optical fiber 5 and the end surface of the hollow core optical fiber 16 serve as the first reflection surface 14, the vibration sensitive film 17 serves as the second reflection surface, and the hollow core optical fiber 16 serves as the light wave transmission path;

[0067] The hollow core optical fiber 16 forms a FP cavity, the cavity length is 40um-80um, and has a light guiding function;

[0068] The vibration sensitive membrane 17 is made of polydimethylsiloxane (PDMS) material, and the membrane thickness is 10um-15um; the vibration sensitive membrane 17 can also be a gold and silver film, a polytetrafluoroethylene (PTFE) film, and the effect of the polydimethylsiloxane (PDMS) film is the best;

[0069] The end faces of the single-mode optical fiber and the hollow-core optical fiber 16 are constructed by using optical fiber fusion splicing technology, the vibration sensitive film 17 is fixed to the end face of the hollow-core optical fiber 16 by fusion splicing or bonding, and the sensor constructed by the single-mode optical fiber-hollow-core optical fiber 16-vibration sensitive film 17 is encapsulated by a flat-end needle tube, so that the sensor has a higher spectral extinction ratio;

[0070] In order to further improve the mechanical strength of the optical ultrasonic sensor group 3-2, combined with the application environment of the sensor, the present invention uses a flat-head needle tube with an inner diameter of 0.5 mm to encapsulate the sensors of the above two diaphragms;

[0071] In the optical ultrasonic sensor group 3 - 2 , the second optical fiber 5 and the end face of the hollow-core optical fiber 16 serve as the first reflection surface 15 , the vibration sensitive film 17 serves as the second reflection surface, and the hollow-core optical fiber 16 serves as the light wave transmission path.

[0072] Further, see Figure 2As shown, the tunable laser 10 emits a light source, which passes through the third optical fiber 6, the circulator and the isolator 8, and the second optical fiber 5. In the optical FP sensor, the second optical fiber 5 and the end face of the hollow-core optical fiber 16 are reflected for the first time, and the transmitted light is transmitted to the vibration sensitive film 17 in the hollow-core optical fiber 16 and reflected for the second time. The light is transmitted through the hollow-core optical fiber 16 and coupled back to the second optical fiber 5 again, and interferes with the first reflected light. When the front ultrasonic wave acts on the vibration sensitive film 17 of the optical FP sensor, the vibration sensitive film 17 in the non-fixed area will be deformed, and the sensor cavity length will also change accordingly, thereby realizing the modulation of the interference spectrum.

[0073] When ultrasonic waves are applied to the FBG sensor from the side, the mechanical vibration induced by the ultrasonic waves causes strain in the single-mode optical fiber where the FBG sensor is located, resulting in changes in the period and effective refractive index of the fiber grating 18, and corresponding changes in the wavelength of the reflected light;

[0074] The wavelength change information of reflected light received by multiple FBG sensors at different positions is accurately collected and processed, and an optical image reflecting the changes in the internal structure or characteristics of the detected object is reconstructed using a specific imaging algorithm.

[0075] Reference Figure 3 As shown, an all-fiber-based ultrasonic detection method includes:

[0076] S1, pulse laser 1 emits laser pulses;

[0077] S2, the fiber optic ultrasound transmitting group 3-1 generates ultrasound waves under the action of pulsed laser;

[0078] S3, the ultrasonic wave acts on the sample 4 to be tested, and the sample 4 to be tested radiates part of the ultrasonic wave;

[0079] S4, the divergent ultrasonic wave is received by the optical ultrasonic sensor group 3-2, and at the same time, the tunable laser 10 emits a detection laser to act on the optical ultrasonic sensor group 3-2 for receiving;

[0080] S5, the length of the FP cavity and the period and effective refractive index of the fiber grating 18 are changed to achieve modulation of the interference spectrum;

[0081] S6, the tunable laser 10 emits a detection laser, and the reflected interference light is transmitted through the photoelectric detector 9 and the acquisition card 11 to obtain an ultrasonic echo signal;

[0082] S7. The computer 12 analyzes and processes the ultrasonic echo signal to perform three-dimensional imaging.

[0083] In a specific embodiment, a pulse laser 1 is used to emit a pulse laser with a wavelength of 532nm, a current range of 300mA, a pulse width range of 5ns, and a repetition frequency range of 10Hz; the fiber optic ultrasonic transmitting group 3-1 generates ultrasonic waves under the action of the pulse laser, wherein the thickness of the light absorption coating 13 is 8um, and the thickness of the composite film layer is 15um; the all-optical ultrasonic probe is placed inside the sample, and the ultrasonic waves are superimposed and act on the sample 4 to be tested, and the ultrasonic waves are reflected from the sample to carry the sample information; at the same time, a tunable laser 10 is used to emit a detection laser to act on the optical ultrasonic sensor group. Since the ultrasonic waves carrying the sample information are received by the optical ultrasonic sensor group, the reflected interference light is demodulated through the photoelectric detector 9 and the acquisition card 11, and the interference spectrum is finally analyzed and processed by the computer 12 to perform three-dimensional imaging.

[0084] In another specific embodiment, a pulse laser 1 is used to emit a pulse laser with a wavelength of 1064nm, a current range of 300mA, a pulse width range of 5ns, and a repetition frequency range of 10Hz; the optical fiber ultrasonic transmitting group 3-1 generates ultrasonic waves under the action of the pulse laser, wherein the thickness of the light absorption coating 13 is 8um, and the thickness of the composite film layer is 15um; the all-optical ultrasonic probe is placed inside the sample, and the ultrasonic waves are superimposed and act on the sample 4 to be tested, and the ultrasonic waves are reflected from the sample to carry the sample information; at the same time, a tunable laser 10 is used to emit a detection laser to act on the optical ultrasonic sensor group, and the optical ultrasonic sensor group carrying the sample information receives the reflected interference light through the photoelectric detector 9 and the acquisition card 11, and the interference spectrum is demodulated, and finally the computer 12 analyzes and processes the ultrasonic echo signal to perform three-dimensional imaging.

[0085] In another specific embodiment, a pulse laser 1 is used to emit a pulse laser with a wavelength of 1064nm, a current range of 400mA, a pulse width range of 20ns, and a repetition frequency range of 100Hz; the optical fiber ultrasonic transmitting group 3-1 generates ultrasonic waves under the action of the pulse laser, wherein the thickness of the light absorption coating 13 is 10um, and the thickness of the composite film layer is 15um; the all-optical ultrasonic probe is placed inside the sample, and the ultrasonic waves are superimposed and act on the sample 4 to be tested, and the ultrasonic waves are reflected from the sample to carry the sample information; at the same time, a tunable laser 10 is used to emit a detection laser to act on the optical ultrasonic sensor group. Since the ultrasonic waves carrying the sample information are detected by the optical ultrasonic sensor group, the reflected interference light is demodulated through the photoelectric detector 9 and the acquisition card 11, and the interference spectrum is finally analyzed and processed by the computer 12 to perform three-dimensional imaging.

[0086] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without creative work.

[0087] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An all-fiber-based ultrasonic detection system, characterized in that: include: Photo-induced ultrasound emission module, optical ultrasound sensing module, all-optical ultrasound probe (3); The photo-ultrasound emission module comprises: a pulse laser (1), a first optical fiber (2); The optical ultrasonic sensor module comprises: a second optical fiber (5), a third optical fiber (6), a fourth optical fiber (7), a circulator and an isolator (8), a photoelectric detector (9), a tunable laser (10), an acquisition card (11), and a computer (12); The all-optical ultrasonic probe (3) comprises: an optical fiber ultrasonic transmitting group (3-1) and an optical ultrasonic sensing group (3-2); The pulse laser (1) in the photo-ultrasound emission module is connected to the optical fiber ultrasound emission group (3-1) of the all-optical ultrasound probe (3) via a first optical fiber (2); The tunable laser (10) in the optical ultrasonic sensor module is connected to the circulator and the isolator (8) through a third optical fiber (6), the acquisition card (11) is connected to the circulator and the isolator (8) through a fourth optical fiber (7) via a photoelectric detector (9), the computer (12) is connected to the acquisition card (11) through the fourth optical fiber (7), and the circulator and the isolator (8) are connected to the optical ultrasonic sensor group (3-2) of the all-optical ultrasonic probe (3) through a second optical fiber (5).

2. The all-fiber-based ultrasonic detection system according to claim 1, characterized in that: In the photo-ultrasound emission module, a pulse laser (1) provides a pulse light source for the optical fiber ultrasound emission group (3-1); The optical fiber ultrasound transmitting group (3-1) is composed of four identical photo-induced ultrasound transmitters; The first optical fiber (2) is a multimode optical fiber, and the optical fiber ultrasonic transmitting group (3-1) uses the multimode optical fiber as a substrate to construct a composite film layer; The composite film layer comprises: polydimethylsiloxane, multi-walled carbon nanotubes and molybdenum disulfide materials, or polydimethylsiloxane, multi-walled carbon nanotubes and graphene materials; Polydimethylsiloxane is a thermoelastic expansion layer (14); The light absorbing coating (13) in the photo-induced ultrasound composite film layer comprises: light absorbing particles, a heat conducting material and polydimethylsiloxane, wherein the light absorbing particles and the heat conducting material exist in a mixed state, multi-walled carbon nanotubes or graphene are the light absorbing particles, and molybdenum disulfide or graphene is used as the heat conducting material.

3. The all-fiber-based ultrasonic detection system according to claim 2, characterized in that: The pulse laser (1) emits pulse laser light, which acts on the light absorbing coating (13) through the first optical fiber (2). The light absorbing coating (13) converts light energy into heat energy under the stimulation of the incident pulse light, and quickly transfers it to the thermoelastic expansion layer (14). The thermoelastic expansion layer (14) expands due to the heat. When there is no light effect, the thermoelastic expansion layer (14) begins to contract after the heat energy is no longer acted on, and converts the heat energy into ultrasonic mechanical energy.

4. The all-fiber-based ultrasonic detection system according to claim 1, characterized in that: In the optical ultrasonic sensor module, a tunable laser (10) is a detection light source of an optical ultrasonic sensor group (3-2), an acquisition card (11) is used to collect ultrasonic echo signals, a computer (12) is used for real-time three-dimensional imaging, a photodetector (9) converts optical signals into electrical signals, and a circulator and an isolator (8) are arranged at the front end of the photodetector (9) and the tunable laser (10); The second optical fiber (5), the third optical fiber (6), and the fourth optical fiber (7) are all single-mode optical fibers; The optical ultrasonic sensor group (3-2) is composed of a Fabry-Perot FP sensor and a fiber grating (18) FBG sensor; The FP sensor is composed of a single-mode optical fiber, a hollow-core optical fiber (16), and a vibration sensitive film (17); the FBG sensor is composed of a single-mode optical fiber and a fiber grating (18); In the optical FP sensor, the second optical fiber (5) and the end surface of the hollow core optical fiber (16) serve as the first reflection surface (14), the vibration sensitive film (17) serves as the second reflection surface, and the hollow core optical fiber (16) serves as the light wave transmission path.

5. The all-fiber-based ultrasonic detection system according to claim 4, characterized in that: The tunable laser (10) emits a light source, which passes through a third optical fiber (6), a circulator and an isolator (8), and a second optical fiber (5). In the optical FP sensor, the second optical fiber (5) and the end face of a hollow-core optical fiber (16) are reflected for the first time. The transmitted light is transmitted in the hollow-core optical fiber (16) to a vibration sensitive film (17) and is reflected for the second time. The light is coupled back to the second optical fiber (5) again through the hollow-core optical fiber (16) and interferes with the first reflected light. When the front ultrasonic wave acts on the vibration sensitive film (17) of the optical FP sensor, the vibration sensitive film (17) in the non-fixed area will be deformed, and the sensor cavity length will also change accordingly, thereby realizing modulation of the interference spectrum. When ultrasonic waves are applied to the FBG sensor from the side, the mechanical vibration induced by the ultrasonic waves causes strain in the single-mode optical fiber where the FBG sensor is located, resulting in changes in the period and effective refractive index of the fiber grating (18), and corresponding changes in the wavelength of the reflected light; The wavelength change information of reflected light received by multiple FBG sensors at different positions is accurately collected and processed, and an optical image reflecting the changes in the internal structure or characteristics of the detected object is reconstructed using a specific imaging algorithm.

6. An all-fiber-based ultrasonic detection method, applied to an all-fiber-based ultrasonic detection system according to any one of claims 1 to 5, comprising: S1, a pulse laser (1) emits laser pulses; S2, the optical fiber ultrasonic transmitting group (3-1) generates ultrasonic waves under the action of pulsed laser; S3, the ultrasonic wave acts on the sample to be tested (4), and the sample to be tested (4) radiates part of the ultrasonic wave; S4, the divergent ultrasonic wave is received by the optical ultrasonic sensor group (3-2), and at the same time, the tunable laser (10) emits a detection laser to act on the optical ultrasonic sensor group (3-2) for receiving; S5, the length of the FP cavity and the period and effective refractive index of the fiber grating (18) are changed to achieve modulation of the interference spectrum; S6, the tunable laser (10) emits a detection laser, and the reflected interference light is transmitted through the photoelectric detector (9) and the acquisition card (11) to obtain an ultrasonic echo signal; S7. The computer (12) analyzes and processes the ultrasonic echo signal to perform three-dimensional imaging.

Images