An all-fiber based ultrasonic detection system and method

Abstract

The application discloses a kind of based on all-fiber ultrasonic detection system and method, it is related to photoacoustic detection technical field.System includes: photo-induced ultrasonic emission module, optical ultrasonic sensing module, all-optical ultrasonic probe (3);Photo-induced ultrasonic emission module includes: pulsed laser (1), first optical fiber (2);Optical ultrasonic sensing module includes: second optical fiber (5), third optical fiber (6), fourth optical fiber (7), circulator and isolator (8), photodetector (9), tunable laser (10), acquisition card (11), computer (12);All-optical ultrasonic probe (3) includes: optical fiber ultrasonic emission group (3-1) and optical ultrasonic sensing group (3-2).The application improves probe design, optimizes manufacturing process and system structure, improves the repeatability and performance consistency of manufacture, improves the contrast and resolution of imaging simultaneously, and reduces noise interference.

Description

TECHNICAL FIELD

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

[0002] In the field of modern medical imaging technology, photoacoustic imaging technology, as an innovative technology paradigm combining endoscopic acoustics and optics, provides a unique perspective and method for disease diagnosis. By irradiating tissue with a short pulse laser, the irradiated area expands due to thermal elasticity, generating ultrasonic signals that can be detected by ultrasonic sensors and reconstructed into tissue images. This technology can accurately diagnose and intervene in early-stage vulnerable plaques in blood vessels.

[0003] The essence of photoacoustic imaging technology and ultrasonic imaging technology is the detection of ultrasonic waves, i.e., the detection of echoes after ultrasonic interaction with tissue and the imaging of ultrasonic waves generated after optical interaction with tissue. Therefore, ultrasonic detection technology is a key part of ensuring imaging quality. According to the ultrasonic detection mechanism, the currently widely used ultrasonic detection schemes can be divided into piezoelectric transducers, micro-mechanical transducers, and 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 small size, high imaging contrast, simple sensor array structure, no need for a large number of wiring, and immunity to electromagnetic interference. An all-optical ultrasonic detection system generally consists of a photo-induced ultrasonic emitter made of optical fiber devices and an optical ultrasonic sensor. The photo-induced ultrasonic emitter can provide comparable or even higher acoustic pressure and wider bandwidth than piezoelectric transducers. The optical ultrasonic sensor has higher sensitivity and higher frequency response compared to piezoelectric elements of the same size. At the same time, benefiting from the light guiding property and electromagnetic interference resistance of optical fiber, all-optical ultrasonic detector devices are easy to combine with photoacoustic imaging systems, even with magnetic resonance imaging systems, and are suitable for complex clinical applications.

[0004] Despite the significant potential of all-optical ultrasound detection technology, its practical application in scenarios such as vascular disease detection still faces a series of serious challenges. From the perspective of probe design and manufacturing processes, traditional all-optical ultrasound probes have several shortcomings. First, their manufacturing process is complex and lacks standardized procedures, resulting in significant performance differences between different batches of probes, making repeatability and consistency difficult to guarantee. For example, when detecting minute lesions within blood vessels, these performance differences may lead to misjudgment or missed detection of lesion features, severely affecting diagnostic accuracy. Second, the structural design of traditional all-optical ultrasound probes is not optimized enough, resulting in relatively low imaging contrast and resolution, making it difficult to clearly distinguish different layers of the vascular wall and the detailed features of minute lesions, such as the lipid core and fibrous cap in vascular plaques. In addition, noise interference is a prominent problem in traditional all-optical ultrasound detection systems. External environmental noise as well as internal optical and electrical noise can easily mix into the ultrasound signal, reducing the signal-to-noise ratio and further deteriorating image quality, causing great difficulties for clinical diagnosis.

[0005] Therefore, proposing an all-fiber-based ultrasonic testing system and method to overcome the difficulties of existing technologies is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides an all-fiber ultrasonic testing system and method. By using optical fibers, the present invention improves probe design, optimizes manufacturing process and system structure, improves repeatability and performance consistency, enhances imaging contrast and resolution, and reduces noise interference.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] An all-fiber-based ultrasonic testing system includes: a photo-induced ultrasonic emission module, an optical ultrasonic sensing module, and an all-optical ultrasonic probe;

[0009] The photo-induced ultrasonic emission module includes: a pulsed laser and a first optical fiber;

[0010] The optical ultrasonic sensing module includes: a second optical fiber, a third optical fiber, a fourth optical fiber, a circulator and isolator, a photodetector, a tunable laser, a data acquisition card, and a computer;

[0011] The all-optical ultrasonic probe consists of: a fiber optic ultrasonic transmitter group and an optical ultrasonic sensor group;

[0012] The pulsed laser in the photo-induced ultrasonic emission module is connected to the fiber optic ultrasonic emission group of the all-optical ultrasonic probe via the first optical fiber.

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

[0014] Optionally, in the photo-induced ultrasonic emission module, the pulsed laser is a pulsed light source for the optical ultrasonic emission group.

[0015] The optical ultrasonic emission group is composed of four identical photo-induced ultrasonic emitters.

[0016] The first optical fiber is a multimode optical fiber, and the optical ultrasonic emission group is 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 material, or polydimethylsiloxane, multi-walled carbon nanotubes and graphene material.

[0018] The polydimethylsiloxane is a thermal-elastic expansion layer.

[0019] The light-absorbing coating in the photo-induced ultrasonic composite film layer comprises light-absorbing particles, heat-conducting material and polydimethylsiloxane, the light-absorbing particles and the heat-conducting material exist in a mixed state, the multi-walled carbon nanotubes or graphene are the light-absorbing particles, and the molybdenum disulfide or graphene is the heat-conducting material.

[0020] Optionally, the pulsed laser emits pulsed laser, the pulsed laser acts on the light-absorbing coating through the first optical fiber, the light-absorbing coating converts light energy into heat energy under the excitation of incident pulsed light and quickly transfers the heat energy to the thermal-elastic expansion layer, the thermal-elastic expansion layer expands under heat, and the thermal-elastic expansion layer starts to shrink after being free of heat energy under the action of light, and converts the heat energy into ultrasonic mechanical energy.

[0021] Optionally, in the optical ultrasonic sensing module, the tunable laser is a detection light source of the optical ultrasonic sensing group, the acquisition card is used to collect ultrasonic echo signals, the computer is used for real-time three-dimensional imaging, the photoelectric detector converts optical signals into electrical signals, and a circulator and an isolator are arranged in front of the photoelectric detector 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 sensing group is composed of a Fabry-Perot (FP) sensor and a fiber Bragg grating (FBG) sensor.

[0024] The FP sensor is composed of a single-mode optical fiber, a hollow optical fiber and a vibration-sensitive film, and the FBG sensor is composed of a single-mode optical fiber and a fiber Bragg grating.

[0025] The second optical fiber and the end face of the hollow core fiber in the optical FP sensor are used as the first reflecting surface, the vibration sensitive film is used as the second reflecting surface, and the hollow core fiber is used as the light wave transmission path.

[0026] The system can be optionally tuned to emit light from the laser through the third optical fiber, the circulator and the isolator, the second optical fiber, and the second optical fiber and the end face of the hollow core fiber in the optical FP sensor to generate the first reflection, the transmitted light is transmitted in the hollow core fiber to the vibration sensitive film to generate the second reflection, and the light is transmitted through the hollow core fiber and coupled back to the second optical fiber to interfere with the first reflected light.

[0027] When the side ultrasonic wave is applied to the FBG sensor, the mechanical vibration caused by the ultrasonic wave causes the single-mode optical fiber where the FBG sensor is located to be strained, resulting in changes in the period and effective refractive index of the fiber grating, and the reflected light wavelength changes accordingly.

[0028] The wavelength change information of the reflected light received by the plurality of FBG sensors at different positions is accurately collected and processed, and a specific imaging algorithm is used to reconstruct an optical image reflecting the internal structure or characteristic changes of the detected object.

[0029] A full-fiber-based ultrasonic detection method, comprising:

[0030] S1, the pulse laser emits a laser pulse;

[0031] S2, the fiber ultrasonic emission group is subjected to the action of the pulse laser to generate ultrasonic waves;

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

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

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

[0035] S6, the tunable laser emits a detection laser, and the reflected interference light is obtained by the photodetector and the acquisition card to obtain the ultrasonic echo signal;

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

[0037] Compared with the prior art, the application provides an all-fiber-based ultrasonic detection system and method, which has the following beneficial effects: 1) the all-optical ultrasonic probe made by the application is divided into an optical ultrasonic emission group and an optical ultrasonic sensing group, the all-optical ultrasonic probe has a diameter of less than 1.5 mm, and the size is small; the improved probe design realizes the integration of transmission and reception, and is suitable for the detection of vascular diseases; 2) the optical ultrasonic emission group is composed of four optical ultrasonic emission probes, and when ultrasonic waves are excited, the optical ultrasonic emission group can realize the superposition of the emitted ultrasonic waves, improve the image contrast, and make the target object and the surrounding tissue have more obvious acoustic impedance differences, which is beneficial to vascular plaque imaging; 3) the signal strength and resolution can be enhanced, and details such as the boundary and internal echo of thyroid nodules can be accurately captured; 4) noise interference can be reduced, so that the image is clearer, the blur and artifacts are reduced, and more accurate ultrasonic diagnosis is helpful; 5) the system structure and manufacturing process are optimized, the manufacturing process is simple, and the repeatability and performance consistency of the later device manufacturing are improved. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only embodiments of the application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of the provided drawings.

[0039] Figure 1 A whole schematic diagram of an all-fiber-based ultrasonic detection system provided by the application;

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

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

[0042] BRIEF DESCRIPTION OF DRAWINGS

[0043] 1 is a pulse laser; 2 is a first optical fiber; 3 is an all-optical ultrasonic probe, 3-1 is an optical ultrasonic emission group, and 3-2 is an optical ultrasonic sensing group; 4 is a sample to be measured; 5 is a second optical fiber; 6 is a third optical fiber; 7 is a fourth optical fiber; 8 is a circulator and isolator; 9 is a photoelectric detector; 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 optical fiber; 17 is a vibration-sensitive film; and 18 is an optical fiber grating. DETAILED DESCRIPTION

[0044] Clearly, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0045] In the present application, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or sequence between the entities or operations, the term "include", "contain" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitation, the element defined by the sentence "including a" does not exclude the presence of another same element in the process, method, article or equipment including the element.

[0046] Referring to Figure 1 As shown in the figure, the present application discloses a kind of based on all-optical fiber ultrasonic detection system, comprising: photo-induced ultrasonic emission module, optical ultrasonic sensing module, all-optical ultrasonic probe 3;

[0047] Photo-induced ultrasonic emission module includes: pulsed laser 1, first optical fiber 2;

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

[0049] All-optical ultrasonic probe 3 includes: optical fiber ultrasonic emission group 3-1 and optical ultrasonic sensing group 3-2;

[0050] Pulsed laser 1 in photo-induced ultrasonic emission module is connected with optical fiber ultrasonic emission group 3-1 of all-optical ultrasonic probe 3 by first optical fiber 2;

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

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

[0053] The optical fiber ultrasonic emission group 3-1 is composed of four identical photo-induced ultrasonic emitters;

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

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

[0056] The polydimethylsiloxane is the base material of the photo-induced ultrasonic composite film layer, and is a thermoelastic expansion layer 14;

[0057] The light-absorbing coating 13 in the photo-induced ultrasonic composite film layer includes: light-absorbing particles, heat-conducting materials, and polydimethylsiloxane, the light-absorbing particles and the heat-conducting materials exist in a mixed state, the multi-walled carbon nanotubes or the graphene are the light-absorbing particles, and the molybdenum disulfide or the graphene are the heat-conducting materials, and the thickness of the light-absorbing coating 13 is 8 um-10 um;

[0058] Further, the combination of the multi-walled carbon nanotubes and the graphene, the graphene can improve the efficiency of photo-thermal conversion and can conduct heat, after the combination of the two, on the one hand, the area and the way of light absorption can be increased, the absorption spectrum range can be widened through the complementary effect, and more photon energy can be absorbed; on the other hand, they can construct an efficient heat conduction channel, the absorbed light energy can be converted into heat energy more quickly and be effectively transmitted, the heat loss can be reduced, and thus the overall efficiency of photo-thermal conversion can be improved;

[0059] Further, the proportion of polydimethylsiloxane (PDMS) in the light-absorbing coating 13 is less than 10%, and the polydimethylsiloxane (PDMS) is used to wrap the light-absorbing particles and the heat-conducting material, and to stably 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 PDMS material has high transparency, and a small proportion will not affect the transmission of the pulsed laser, and on the other hand, the light-absorbing particles and the heat-conducting material play a role similar to a beam support inside the light-absorbing coating 13, and they cooperate with the appropriate amount of PDMS to jointly build a stable and reasonable coating structure, and 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 realize accurate and effective coating operation, the present application selects a 20-50 mesh screen based on the screen printing method, pours the mixture (polydimethylsiloxane and multi-walled carbon nanotubes & graphene, or polydimethylsiloxane and multi-walled carbon nanotubes & molybdenum disulfide, the proportion of polydimethylsiloxane (PDMS) is less than 10%) of a certain proportion of the light-absorbing layer on the screen, uses a squeegee to remove the excess part, retains the mixture in the screen grid, and then uses a three-dimensional adjusting frame to pass the optical fiber through the grid, so that the mixture is transferred to the end face of the optical fiber, thereby the thickness of the light-absorbing coating 13 can be controlled, and the production of the thermoelastic expansion layer 14 (polydimethylsiloxane) also adopts this method. This coating method and the matching control means not only improve the repeatability of the production of related coatings, but also ensure the consistency of the performance of the emitter in different batches of production, which plays an important role in promoting the reliability and standardized production of the entire device.

[0061] Further, referring to Figure 2 As shown in the figure, the pulsed laser 1 emits pulsed laser, the pulsed laser 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 incident pulsed light, and quickly transmits to the thermoelastic expansion layer 14, the thermoelastic expansion layer 14 expands under heat, and when there is no light, the thermoelastic expansion layer 14 starts to shrink after being free of heat energy, and converts heat energy into ultrasonic mechanical energy.

[0062] Further, in the optical ultrasonic sensing module, the tunable laser 10 is the detection light source of the optical ultrasonic sensing group 3-2, the acquisition card 11 is used to display the ultrasonic echo signal, the photoelectric detector 9 converts the optical signal into an electrical signal, and a circulator and an isolator 8 are arranged in front of the photoelectric detector 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] Optical ultrasonic sensor group 3-2 is composed of Fabry-Perot (FP) sensors and fiber Bragg grating (FBG) sensors, the FP and FBG sensors are arranged alternately, and there are 8 sensors in total, wherein the FP sensors detect the front ultrasonic waves, and the FBG sensors receive the side ultrasonic waves, so that only a certain forward step of the probe is needed to realize real-time three-dimensional imaging;

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

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

[0067] The hollow optical fiber 16 forms an FP cavity, and the cavity length is 40-80 um, which has a light guiding effect.

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

[0069] The single-mode optical fiber and the end face of the hollow optical fiber 16 are constructed by using the optical fiber fusion technology, the vibration sensitive film 17 is fixed on the end face of the hollow optical fiber 16 by fusion or adhesion, and the flat needle tube is used for packaging the sensor constructed by the single-mode optical fiber, the hollow optical fiber 16 and the vibration sensitive film 17, so that the sensor has a high spectral extinction ratio.

[0070] In order to further improve the mechanical strength of the optical ultrasonic sensor group 3-2, in combination with the application environment of the sensor, the flat needle tube with an inner diameter of 0.5 mm is used for packaging the sensors of the two kinds of films.

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

[0072] Further, refer to Figure 2As shown, the tunable laser 10 emits light source, through the third optical fiber 6, the isolator and the circulator 8, the second optical fiber 5, the second optical fiber 5 and the end face of the hollow core fiber 16 in the optical FP sensor occur the first reflection, the transmission light transmits in the hollow core fiber 16 to the vibration sensitive film 17 to occur the second reflection, and the transmission via the hollow core fiber 16 is coupled back to the second optical fiber 5 again, and the interference with the first reflected light occurs, when the front surface 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 also changes, realizing the modulation of the interference spectrum;

[0073] When the side surface ultrasonic wave is applied to the FBG sensor, the mechanical vibration caused by the ultrasonic wave makes the single mode optical fiber where the FBG sensor is located produce strain, resulting in the change of the period and the effective refractive index of the fiber grating 18, and the corresponding change of the reflected light wavelength;

[0074] The reflected light wavelength change information received by the plurality of FBG sensors at different positions is accurately collected and processed, and a specific imaging algorithm is used to reconstruct an optical image reflecting the internal structure or characteristic change of the detected object.

[0075] Referring to Figure 3 As shown, a full-fiber-based ultrasonic detection method comprises:

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

[0077] S2, the fiber ultrasonic emission group 3-1 produces ultrasonic waves under the action of the pulse laser;

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

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

[0080] S5, the FP cavity length, the period and the effective refractive index of the fiber grating 18 change, realizing the modulation of the interference spectrum;

[0081] S6, the tunable laser 10 emits a detection laser, and the reflected interference light obtains an ultrasonic echo signal via the photodetector 9 and the acquisition card 11;

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

[0083] In one embodiment, the pulsed laser 1 emits pulsed laser with wavelength of 532 nm, current range of 300 mA, pulse width range of 5 ns, and repetition frequency range of 10 Hz; the optical fiber ultrasonic emission group 3-1 generates ultrasonic waves under the action of the pulsed laser, wherein the light-absorbing coating 13 has a thickness of 8 um, and the composite film layer has a thickness of 15 um; the all-optical ultrasonic probe is placed inside the sample, the ultrasonic waves are superimposed and then act on the sample to be measured 4, and the ultrasonic waves reflected from the sample carry sample information; meanwhile, the tunable laser 10 emits probe laser to act on the optical ultrasonic sensing group, the ultrasonic waves carrying sample information are received by the optical ultrasonic sensing group, the reflected interference light is passed through the photodetector 9 and the acquisition card 11, the interference spectrum is demodulated, and finally the computer 12 analyzes and processes the ultrasonic echo signal to perform three-dimensional imaging.

[0084] In another embodiment, the pulsed laser 1 emits pulsed laser with wavelength of 1064 nm, current range of 300 mA, pulse width range of 5 ns, and repetition frequency range of 10 Hz; the optical fiber ultrasonic emission group 3-1 generates ultrasonic waves under the action of the pulsed laser, wherein the light-absorbing coating 13 has a thickness of 8 um, and the composite film layer has a thickness of 15 um; the all-optical ultrasonic probe is placed inside the sample, the ultrasonic waves are superimposed and then act on the sample to be measured 4, and the ultrasonic waves reflected from the sample carry sample information; meanwhile, the tunable laser 10 emits probe laser to act on the optical ultrasonic sensing group, the ultrasonic waves carrying sample information are received by the optical ultrasonic sensing group, the reflected interference light is passed through the photodetector 9 and the acquisition card 11, 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 embodiment, the pulsed laser 1 emits pulsed laser with wavelength of 1064 nm, current range of 400 mA, pulse width range of 20 ns, and repetition frequency range of 100 Hz; the optical fiber ultrasonic emission group 3-1 generates ultrasonic waves under the action of the pulsed laser, wherein the light-absorbing coating 13 has a thickness of 10 um, and the composite film layer has a thickness of 15 um; the all-optical ultrasonic probe is placed inside the sample, the ultrasonic waves are superimposed and then act on the sample to be measured 4, and the ultrasonic waves reflected from the sample carry sample information; meanwhile, the tunable laser 10 emits probe laser to act on the optical ultrasonic sensing group, the ultrasonic waves carrying sample information are received by the optical ultrasonic sensing group, the reflected interference light is passed through the photodetector 9 and the acquisition card 11, the interference spectrum is demodulated, and finally the computer 12 analyzes and processes the ultrasonic echo signal to perform three-dimensional imaging.

[0086] The various embodiments described in this specification are described with reference to a particular sequence or order, but the order of the steps can be modified so that particular sequences or orders make no significant contribution to the progress of the art. Moreover, certain features and subcombinations are of utility and can be employed without reference to other features and subcombinations. For purposes of clarity, not every embodiment or feature in this specification is described or shown. Embodiments that provide real benefits can include any embodiment or combination of features described in this specification— even if the range of benefits realized is not the full range of benefits. Those of ordinary skill can understand that information and signals can be represented using any of a variety of technologies and techniques. For the purposes of this description, the terms "information" and "signals" can be regarded as synonymous. Those of ordinary skill can appreciate that the signals can be analog or digital, and the like.

[0087] The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An all-fiber based ultrasonic detection system, characterized by, Comprise: Optical ultrasonic emission module, optical ultrasonic sensing module, all-optical ultrasonic probe (3); The optical ultrasonic emission module comprises: a pulsed laser (1), a first optical fiber (2); In the optical ultrasonic emission module, the pulsed laser (1) provides a pulsed light source for the optical fiber ultrasonic emission group (3-1); The optical fiber ultrasonic emission group (3-1) is composed of four identical optical ultrasonic emitters; The first optical fiber (2) is a multimode optical fiber, and the optical fiber ultrasonic emission group (3-1) is based on a multimode optical fiber to construct a composite film layer; The composite film layer comprises: polydimethylsiloxane, multi-walled carbon nanotubes and molybdenum disulfide material, or polydimethylsiloxane, multi-walled carbon nanotubes and graphene material; The polydimethylsiloxane is a thermoelastic expansion layer (14); The light-absorbing coating (13) in the optical ultrasonic composite film layer comprises: light-absorbing particles, heat-conducting materials and polydimethylsiloxane, the light-absorbing particles and the heat-conducting materials exist in a mixed state, the multi-walled carbon nanotubes or the graphene are the light-absorbing particles, and the molybdenum disulfide or the graphene are the heat-conducting materials; 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 photodetector (9), a tunable laser (10), a collection card (11), and a computer (12); The all-optical ultrasonic probe (3) comprises: an optical fiber ultrasonic emission group (3-1) and an optical ultrasonic sensing group (3-2); the optical ultrasonic sensing group (3-2) is composed of a Fabry-Perot (FP) sensor and a fiber Bragg grating (FBG) sensor; The pulsed laser (1) in the optical ultrasonic emission module is connected with the optical fiber ultrasonic emission group (3-1) of the all-optical ultrasonic probe (3) through the first optical fiber (2); The tunable laser (10) in the optical ultrasonic sensing module is connected with the circulator and isolator (8) through the third optical fiber (6), the collection card (11) is connected with the circulator and isolator (8) through the photodetector (9) and the fourth optical fiber (7), the computer (12) is connected with the collection card (11) through the fourth optical fiber (7), and the circulator and isolator (8) are connected with the optical ultrasonic sensing group (3-2) of the all-optical ultrasonic probe (3) through the second optical fiber (5).

2. The all-fiber ultrasonic detection system according to claim 1, wherein the pulsed laser (1) emits pulsed laser, the pulsed laser 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 incident pulsed light, and rapidly transfers the heat energy to the thermoelastic expansion layer (14), the thermoelastic expansion layer (14) expands under the heat, and the thermoelastic expansion layer (14) starts to shrink after being free of heat energy, and converts the heat energy into ultrasonic mechanical energy.

3. The all-fiber ultrasonic detection system according to claim 1, wherein ​ In the optical ultrasonic sensing module, the tunable laser (10) is the detection light source of the optical ultrasonic sensing group (3-2), the acquisition card (11) is used for collecting ultrasonic echo signals, the computer (12) is used for real-time three-dimensional imaging, the photoelectric detector (9) converts optical signals into electrical signals, and a circulator and an isolator (8) are arranged in front of the photoelectric detector (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 FP sensor is composed of a single-mode optical fiber, a hollow optical fiber (16) and a vibration sensitive film (17); and the FBG sensor is composed of a single-mode optical fiber and a fiber grating (18). In the optical FP sensor, the end face of the second optical fiber (5) and the hollow optical fiber (16) serve as a first reflecting surface, the vibration sensitive film (17) serves as a second reflecting surface, and the hollow optical fiber (16) serves as an optical wave transmission path.

4. The all-fiber ultrasonic detection system according to claim 3, characterized in that, 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), and is reflected for the first time at the end face of the second optical fiber (5) and the hollow optical fiber (16) in the optical FP sensor; the transmitted light is transmitted in the hollow optical fiber (16) to the vibration sensitive film (17) to be reflected for the second time, is transmitted through the hollow optical fiber (16) again, is coupled back to the second optical fiber (5), and interferes with the light reflected for the first time; when a 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, the sensor cavity length will also change, and the interference spectrum is modulated; When a side ultrasonic wave is applied to the FBG sensor, the mechanical vibration caused by the ultrasonic wave causes the single-mode optical fiber where the FBG sensor is located to produce strain, the period and effective refractive index of the fiber grating (18) are changed, and the reflected light wavelength is changed correspondingly; The wavelength change information of the reflected light received by the multiple FBG sensors at different positions is accurately collected and processed, a specific imaging algorithm is used, and an optical image reflecting the internal structure or characteristic change of the detected object is reconstructed.

5. An all-fiber ultrasonic detection method, applied to the all-fiber ultrasonic detection system of any one of claims 1-4, comprising: S1, the pulsed laser (1) emits a laser pulse; S2, the fiber ultrasonic emission group (3-1) generates ultrasonic waves under the action of the pulsed laser; S3, the ultrasonic wave acts on the sample to be detected (4), and the sample to be detected (4) diverges part of the ultrasonic wave; S4, the divergent ultrasonic wave is received by the optical ultrasonic sensing group (3-2), and the tunable laser (10) emits a detection laser to act on the optical ultrasonic sensing group (3-2); S5, the FP cavity length and the period and effective refractive index of the fiber grating (18) are changed, and the interference spectrum is modulated; S6, the tunable laser (10) emits a detection laser, and the reflected interference light is obtained through the photoelectric detector (9) and the acquisition card (11) to obtain an ultrasonic echo signal. S7, analyzing and processing the ultrasonic echo signals by the computer (12) to perform three-dimensional imaging.

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