Passive high-frequency all-optical ultrasonic microscopic imaging system and method

Abstract

The invention discloses a passive high-frequency all-optical ultrasonic microscopic imaging system and a passive high-frequency all-optical ultrasonic microscopic imaging method, which are used for solving the technical problem of poor sensitivity of all-optical ultrasonic imaging caused by the existing passive high-frequency all-optical ultrasonic microscopic imaging system. The system obtains an optical fiber coupling laser beam through an optical coupling assembly, the optical fiber coupling laser beam is transmitted to a photoacoustic transducer through a first optical fiber to be converted into an ultrasonic signal, and the ultrasonic signal is focused on a to-be-detected sample through a wave concentrator. A sample is immersed in the object carrying water tank moving platform and located at the second focus of the wave concentrator, and a generated enhanced echo signal is captured by the optical fiber hydrophone probe (arranged at the first focus of the wave concentrator together with the photoacoustic transducer) and transmitted to the imaging device through a second optical fiber. The fixed support ensures that the wave concentrator is stably located above a sample, the imaging device synchronously controls the optical coupling assembly and the mobile platform, and finally echo signals are processed into high-resolution ultrasonic microscopic images.

Description

Technical Field

[0001] The present invention relates to the field of microscopic imaging technology, and particularly to a passive high-frequency all-optical ultrasonic microscopic imaging system and method. Background Art

[0002] High-frequency ultrasonic imaging can achieve fine tissue visualization and become the core technology for superficial tissue diagnosis, dynamic monitoring, and minimally invasive intervention, with irreplaceable value in the medical, industrial, and scientific research fields. High-frequency ultrasonic imaging is usually realized using an electronic transducer.

[0003] While an all-optical ultrasonic transducer uses pulsed light and optical reception of tissue ultrasonic reflection to generate ultrasound and can be used as an alternative solution. The all-optical ultrasonic imaging technology adopts the technology of a laser-induced ultrasonic source, using the photoacoustic effect in a designed photoacoustic transducer as the ultrasonic source for imaging. Compared with traditional ultrasonic imaging, all-optical ultrasonic imaging uses a laser instead of electricity as the driving source, can achieve passivity and a higher bandwidth, and avoids the complexity of piezoelectric ultrasonic transducer assembly.

[0004] In existing passive high-frequency all-optical ultrasonic microscopic imaging systems, an optical fiber and a hydrophone are usually directly placed vertically above a sample to be measured, and ultrasound propagates downward to the surface of the received sample and returns an echo signal. Since ultrasonic waves will spread and attenuate during propagation, the sensitivity of all-optical ultrasonic imaging is poor. Summary of the Invention

[0005] The present invention provides a passive high-frequency all-optical ultrasonic microscopic imaging system and method to solve the technical problem that the existing passive high-frequency all-optical ultrasonic microscopic imaging system results in poor sensitivity of all-optical ultrasonic imaging.

[0006] A passive high-frequency all-optical ultrasonic microscopic imaging system provided in the first aspect of the present invention, the system includes an optical coupling assembly, a first optical fiber, a second optical fiber, an optical fiber hydrophone probe, a fixing bracket, a photoacoustic transducer, a focusing device, a sample to be measured, a moving platform for a water tank with the sample, and an imaging device;

[0007] The optical coupling assembly is connected to the photoacoustic transducer through the first optical fiber, and both the photoacoustic transducer and the optical fiber hydrophone probe are located at the first focal position of the focusing device;

[0008] The focusing device is fixed to the inner side of the moving platform for the water tank with the sample through the fixing bracket and is located above the sample to be measured;

[0009] The sample to be measured is immersed and fixed on the moving platform for the water tank with the sample and is located at the second focal position of the focusing device;

[0010] The imaging device is connected to the fiber optic hydrophone probe through the second optical fiber, and the imaging device is respectively connected to the optical coupling component and the movable platform of the water tank for holding samples.

[0011] The optical coupling component is used to obtain a fiber-coupled laser beam and transmit it to the photoacoustic transducer through the first optical fiber.

[0012] The photoacoustic transducer is used to convert the fiber-coupled laser beam into an ultrasonic signal and transmit it to the acoustic lens.

[0013] The acoustic lens is used to focus the ultrasonic signal on the sample to be measured, generate an enhanced echo signal and transmit it to the imaging device through the fiber optic hydrophone probe.

[0014] The imaging device is used to generate an ultrasonic microscopic image corresponding to the sample to be measured according to the enhanced echo signal.

[0015] Optionally, the optical coupling component includes a pulsed laser, a lens and a fiber optic coupler arranged horizontally in sequence.

[0016] The pulsed laser is connected to the imaging device.

[0017] The pulsed laser is used to generate a laser, which is focused by the lens and then transmitted to the fiber optic coupler.

[0018] The fiber optic coupler is used to couple the focused laser to generate a fiber-coupled laser beam and transmit it to the photoacoustic transducer through the first optical fiber.

[0019] Optionally, the movable platform of the water tank for holding samples includes a stepper motor, an electric platform and a water tank for holding samples.

[0020] The stepper motor is respectively connected to the electric platform and the imaging device.

[0021] The water tank for holding samples is placed on the upper surface of the electric platform.

[0022] The acoustic lens is fixed inside the water tank for holding samples through a fixed bracket, and the sample to be measured is immersed and fixed in the water tank for holding samples.

[0023] The stepper motor is used to control the movement of the electric platform.

[0024] Optionally, the acoustic lens includes a first parabolic reflector and a second parabolic reflector.

[0025] The focal position of the second parabolic reflector is at the second focal position of the acoustic lens.

[0026] The first focal position of the polywave concentrator is the focal position of the first parabolic reflector;

[0027] The first parabolic reflector and the second parabolic reflector are arranged facing each other inside the load water tank through the fixed bracket, and are both located above the sample to be measured;

[0028] The first parabolic reflector is configured to convert the ultrasonic signal into a first parallel wave signal and transmit it to the second parabolic reflector, and focus the received second parallel wave signal transmitted by the second parabolic reflector to generate an enhanced echo signal and transmit it to the imaging device through the fiber optic hydrophone probe;

[0029] The second parabolic reflector is configured to focus the first parallel wave signal transmitted by the first parabolic reflector and then reflect it to the sample to be measured, and convert the echo signal generated by the sample to be measured based on the focused first parallel wave signal into a second parallel wave signal, and transmit the second parallel wave signal to the first parabolic reflector.

[0030] Optionally, the imaging device includes a fiber optic hydrophone, a signal amplifier, a data acquisition card, a control card, and a computer connected in sequence;

[0031] The computer is respectively connected to the pulsed laser and the stepper motor in the load water tank moving platform;

[0032] The fiber optic hydrophone is configured to transmit the received enhanced echo signal to the signal amplifier;

[0033] The signal amplifier is configured to amplify the enhanced echo signal to generate an amplified enhanced echo signal and transmit it to the data acquisition card;

[0034] The data acquisition card is configured to digitally process the amplified enhanced echo to generate a digital enhanced signal and transmit it to the computer through the control card;

[0035] The computer is configured to perform imaging processing on the digital enhanced signal to generate an ultrasonic microscopic image corresponding to the sample to be measured.

[0036] A passive high-frequency all-optical ultrasonic microscopic imaging method provided in the second aspect of the present invention is applied to the passive high-frequency all-optical ultrasonic microscopic imaging system described above. The method includes:

[0037] In response to an imaging request, obtain a fiber-coupled laser beam and convert the fiber-coupled laser beam into an ultrasonic signal;

[0038] The ultrasonic signal is focused on the sample to be measured by a wave concentrator in a passive high-frequency all-optical ultrasonic microscopy system to generate an enhanced echo signal;

[0039] An ultrasonic microscopy image corresponding to the sample to be measured is generated according to the enhanced echo signal.

[0040] Optionally, the generating an ultrasonic microscopy image corresponding to the sample to be measured according to the enhanced echo signal includes:

[0041] Amplify the enhanced echo signal to generate an amplified enhanced echo signal;

[0042] Perform digital processing on the amplified enhanced echo to generate a digital enhanced signal;

[0043] Perform imaging processing on the digital enhanced signal to generate an ultrasonic microscopy image corresponding to the sample to be measured.

[0044] A computer device provided in the third aspect of the present invention includes a memory and a processor. A computer program is stored in the memory. When the computer program is executed by the processor, the processor executes the steps of the passive high-frequency all-optical ultrasonic microscopy method described in any one of the above.

[0045] A computer-readable storage medium provided in the fourth aspect of the present invention stores a computer program thereon. When the computer program is executed, the steps of the passive high-frequency all-optical ultrasonic microscopy method described in any one of the above are implemented.

[0046] A computer program product provided in the fifth aspect of the present invention includes a computer program stored on a non-transitory computer-readable storage medium. The computer program includes program instructions. When the program instructions are executed by a computer, the computer executes the steps of the passive high-frequency all-optical ultrasonic microscopy method described in any one of the above.

[0047] It can be seen from the above technical solutions that the present invention has the following advantages:

[0048] In the first aspect of the above technical solution of the present invention, a passive high-frequency all-optical ultrasonic microscopy imaging system is provided. The system includes an optical coupling component, a first optical fiber, a second optical fiber, a fiber optic hydrophone probe, a fixing bracket, a photoacoustic transducer, a focusing device, a sample to be measured, a moving platform for the water tank, and an imaging device. Among them, the optical coupling component is connected to the photoacoustic transducer through the first optical fiber. The photoacoustic transducer and the fiber optic hydrophone probe are both located at the first focal position of the focusing device. The focusing device is fixed inside the moving platform for the water tank through the fixing bracket and is located above the sample to be measured. The sample to be measured is immersed and fixed on the moving platform for the water tank and is located at the second focal position of the focusing device. The imaging device is connected to the fiber optic hydrophone probe through the second optical fiber and is connected to the optical coupling component. The optical coupling component is used to obtain a fiber-coupled laser beam and transmit it to the photoacoustic transducer through the first optical fiber. The photoacoustic transducer is used to convert the fiber-coupled laser beam into an ultrasonic signal and transmit it to the focusing device. The focusing device is used to focus the ultrasonic signal on the sample to be measured, generate an enhanced echo signal, and transmit it to the imaging device through the fiber optic hydrophone probe. The imaging device is used to generate an ultrasonic microscopy image corresponding to the sample to be measured according to the enhanced echo signal. Based on the above solution, the present invention uses the focusing device to focus the ultrasonic signal on the sample to be measured, which can enhance the intensity of the received signal. Then, combined with the imaging device, according to the generated enhanced echo signal, an ultrasonic microscopy image corresponding to the sample to be measured is generated, thereby realizing a higher-sensitivity imaging function.

[0049] In the second aspect of the above technical solution of the present invention, a passive high-frequency all-optical ultrasonic microscopy imaging method is provided. When passive high-frequency all-optical ultrasonic microscopy imaging is required, a fiber-coupled laser beam is obtained and converted into an ultrasonic signal. The ultrasonic signal is focused on the sample to be measured through the focusing device in the passive high-frequency all-optical ultrasonic microscopy imaging system to generate an enhanced echo signal. An ultrasonic microscopy image corresponding to the sample to be measured is generated according to the enhanced echo signal. Based on the above solution, the present invention uses the focusing device in the passive high-frequency all-optical ultrasonic microscopy imaging system to focus the ultrasonic signal on the sample to be measured, which can enhance the intensity of the received signal. Then, according to the generated enhanced echo signal, an ultrasonic microscopy image corresponding to the sample to be measured is generated, thereby realizing a higher-sensitivity imaging function. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0051] Figure 1Schematic diagram of the structure of a passive high-frequency all-optical ultrasonic microscopy imaging system provided in the first embodiment of the present invention;

[0052] Figure 2 Schematic diagram of the structure of the photoacoustic transducer provided in the first embodiment of the present invention;

[0053] Figure 3 Schematic diagram of the simulation settings of the condenser in the matlab software provided in the first embodiment of the present invention;

[0054] Figure 4 Three-dimensional structure diagram of the condenser provided in the first embodiment of the present invention;

[0055] Figure 5 Three-dimensional structure diagram of the first parabolic reflector (the first parabolic reflector) in the condenser provided in the first embodiment of the present invention;

[0056] Figure 6 Three-dimensional structure diagram of the second parabolic reflector (the second parabolic reflector) in the condenser provided in the first embodiment of the present invention;

[0057] Figure 7 Simulation result diagram of focusing on the focus of another part of the parabolic reflector after enhancement by the condenser provided in the first embodiment of the present invention;

[0058] Figure 8 Comparison result of enhancement with and without the condenser in the matlab simulation provided in the first embodiment of the present invention;

[0059] Figure 9 Flowchart of the steps of a passive high-frequency all-optical ultrasonic microscopy imaging method provided in the second embodiment of the present invention;

[0060] Figure 10 Schematic diagram of the process of a passive high-frequency all-optical ultrasonic microscopy imaging method provided in the second embodiment of the present invention.

[0061] Among them, the meanings of the reference signs of the drawings are as follows:

[0062] 1. Computer; 2. Pulse laser; 3. Lens; 4. Fiber optic coupler; 5. First optical fiber; 6. Fixed bracket; 7. Condenser; 8. Photoacoustic transducer; 9. Sample to be measured; 10. Carrying water tank; 11. Electric platform; 12. Stepper motor; 13. Fiber optic hydrophone; 14. Signal amplifier; 15. Data acquisition card; 16. Second optical fiber; 17. First parabolic reflector; 18. Second parabolic reflector; S1. Optical fiber; S2. Photoacoustic transducer; S3. Glass substrate; S4. PDMS layer (Polydimethylsiloxane Layer); S5. Light absorption layer. Detailed implementation manners

[0063] An embodiment of the present invention provides a passive high-frequency all-optical ultrasonic microscopy imaging system and method, which are used to solve the technical problem that the existing passive high-frequency all-optical ultrasonic microscopy imaging system results in poor sensitivity of all-optical ultrasonic imaging.

[0064] In order to make the invention purpose, features, and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described below are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0065] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of a passive high-frequency all-optical ultrasonic microscopy imaging system provided in Embodiment 1 of the present invention.

[0066] A passive high-frequency all-optical ultrasonic microscopy imaging system provided by the present invention includes an optical coupling component, a first optical fiber 5, a second optical fiber 16, a fiber optic hydrophone 13 probe, a fixing bracket 6, a photoacoustic transducer 8, a condenser 7, a sample to be measured 9, a carrier water tank 10 moving platform, and an imaging device;

[0067] The optical coupling component is connected to the photoacoustic transducer 8 through the first optical fiber 5, and both the photoacoustic transducer 8 and the fiber optic hydrophone 13 probe are located at the first focal position of the condenser 7; the condenser 7 is fixed inside the carrier water tank 10 moving platform through the fixing bracket 6 and is located above the sample to be measured 9; the sample to be measured 9 is immersed and fixed on the carrier water tank 10 moving platform and is located at the second focal position of the condenser 7; the imaging device is connected to the fiber optic hydrophone 13 probe through the second optical fiber 16, and the imaging device is respectively connected to the optical coupling component and the carrier water tank 10 moving platform;

[0068] The optical coupling component is used to obtain a fiber-coupled laser beam and transmit it to the photoacoustic transducer 8 through the first optical fiber 5;

[0069] The photoacoustic transducer 8 is used to convert the fiber-coupled laser beam into an ultrasonic signal and transmit it to the condenser 7;

[0070] The condenser 7 is used to focus the ultrasonic signal on the sample to be measured 9, generate an enhanced echo signal and transmit it to the imaging device through the fiber optic hydrophone 13 probe;

[0071] The imaging device is used to generate an ultrasonic microscopy image corresponding to the sample to be measured 9 according to the enhanced echo signal.

[0072] The fiber-coupled laser beam has a uniform spot intensity and is a Gaussian-distributed beam.

[0073] It should be noted that first, the sample to be detected is placed and fixed. The sample to be detected is placed in the loading water tank and immersed in water. Next, the system is set up. The fiber coupler is adjusted to ensure that the pulsed laser is correctly coupled to the optical fiber. The collimator is placed and fixed at the set position. One end of the optical fiber equipped with the photoacoustic transducer is vertically immersed in water through the collimator and the end of the fiber optic hydrophone probe, that is, the photoacoustic transducer and the end of the fiber optic hydrophone probe are vertically immersed in water and fixed at the focal position of the first parabolic reflector in the collimator. The pulsed laser is turned on to emit laser, and the laser is coupled through a lens and a fiber coupler in sequence. The generated fiber-coupled laser beam is transmitted to the photoacoustic transducer through the first optical fiber 5, exciting the photoacoustic transducer to emit ultrasonic signals and focusing on the sample to be detected through the collimator. At the same time, the electric platform starts to move to complete the scan. The enhanced echo signal generated by the sample to be detected is received by the fiber optic hydrophone probe and transmitted to the fiber optic hydrophone through the second optical fiber. After the signal is amplified by the signal amplifier 14, it is collected by the data acquisition card 15. Finally, after signal processing of the collected enhanced echo signal, the ultrasonic microscopy image corresponding to the sample to be detected is obtained.

[0074] Furthermore, please refer to Figure 2 , a photoacoustic transducer 8 of an appropriate size is fabricated according to the optical fiber. After the coupled laser is transmitted to the photoacoustic transducer 8 through the optical fiber, at this time, the fiber-coupled laser beam irradiates on the light absorption layer of the photoacoustic transducer 8, and the light energy is absorbed and converted into heat energy, resulting in a local temperature rise of the photoacoustic transducer 8. The PDMS layer of the photoacoustic transducer 8 expands and emits ultrasonic signals.

[0075] As a further improvement, the optical coupling component includes a pulsed laser 2, a lens 3, and a fiber coupler 4 arranged horizontally in sequence;

[0076] The pulsed laser 2 is connected to the imaging device;

[0077] The pulsed laser 2 is used to generate laser, and after being focused by the lens 3, it is emitted to the fiber coupler 4;

[0078] The fiber coupler 4 is used to couple the focused laser, generate a fiber-coupled laser beam, and transmit it to the photoacoustic transducer 8 through the first optical fiber 5.

[0079] It should be noted that the pulsed laser 2 is connected to the imaging device. The pulsed laser 2 emits laser light, which is coupled to the optical fiber through the lens 3 and the fiber optic coupler 4 in sequence. The other end of the optical fiber is equipped with a photoacoustic transducer 8. The fiber-coupled laser beam is transmitted through the optical fiber to the other end and is converted into an ultrasonic signal by the photoacoustic transducer 8 and emitted to the condenser 7. The ultrasonic signal is focused on the sample to be measured 9 by the condenser 7, and scanning is started to generate an enhanced echo signal. Finally, the imaging device generates an ultrasonic microscopic image corresponding to the sample to be measured 9 according to the enhanced echo signal.

[0080] It is worth mentioning that the fiber optic hydrophone 13 is used to transmit the detected enhanced echo signal to the imaging device. The enhanced echo signal is detected by the fiber optic hydrophone 13 and transmitted to the data acquisition card 15 in the imaging device for storage, and finally processed for imaging.

[0081] Furthermore, the main material in the used photoacoustic transducer 8 provides a high coefficient of thermal expansion, allowing efficient generation of photoacoustic pressure, which can simplify the manufacturing technology, reduce costs, and further miniaturize the imaging technology.

[0082] As a further improvement, the moving platform of the sample cell 10 includes a stepper motor 12, an electric platform 11, and a sample cell 10;

[0083] The stepper motor 12 is respectively connected to the electric platform 11 and the imaging device;

[0084] The sample cell 10 is placed on the upper surface of the electric platform 11;

[0085] The condenser 7 is fixed to the inside of the sample cell 10 through a fixing bracket 6, and the sample to be measured 9 is fixed and immersed in the sample cell 10;

[0086] The stepper motor 12 is used to control the movement of the electric platform 11.

[0087] It should be noted that the sample cell 10 is placed on the electric platform 11, the sample to be measured 9 is fixedly immersed in the water tank, the condenser 7 is fixed at a set position inside the sample cell 10 through the fixing bracket 6, and the probe of the fiber optic hydrophone 13 and the photoacoustic transducer 8 on the second optical fiber 16 are fixed at the focal position of the condenser 7, that is, both the photoacoustic transducer 8 and the probe of the fiber optic hydrophone 13 are located at the first focal position of the condenser 7.

[0088] As a further improvement, the condenser 7 includes a first parabolic reflector 17 and a second parabolic reflector 18;

[0089] The focal position of the second parabolic reflector 18 is at the second focal position of the condenser 7;

[0090] The focal position of the first parabolic reflector 17 is at the first focal position of the condenser 7;

[0091] The first parabolic reflector 17 and the second parabolic reflector 18 are arranged facing each other inside the loading water tank 10 through the fixing bracket 6, and are both located above the sample to be measured 9;

[0092] The first parabolic reflector 17 is used to convert the ultrasonic signal into a first parallel wave signal and transmit it to the second parabolic reflector 18, and focus the second parallel wave signal received and transmitted by the second parabolic reflector 18 to generate an enhanced echo signal, which is transmitted to the imaging device through the probe of the fiber optic hydrophone 13;

[0093] The second parabolic reflector 18 is used to focus the first parallel wave signal transmitted by the first parabolic reflector 17 and then reflect it to the sample to be measured 9, and convert the echo signal generated by the sample to be measured 9 based on the focused first parallel wave signal into a second parallel wave signal, and transmit the second parallel wave signal to the first parabolic reflector 17.

[0094] It should be noted that, please refer to Figures 3 - 6 , the concentrator 7 used in the present invention is made of a high acoustic impedance material. The concentrator 7 consists of two parts (the first parabolic reflector 17 and the second parabolic reflector 18), and the shape of each part is a reflector conforming to a parabola. The parabolic reflector can reflect the parallel incident ultrasonic waves to the focus of the parabola or convert the ultrasonic waves emitted from the focus into parallel waves and emit them; the photoacoustic transducer 8 is placed at the focus position of the first parabolic reflector (the first parabolic reflector 17). After being reflected and converted into parallel waves and emitted, it is incident on the second parabolic reflector (the second parabolic reflector 18) and reflected to its focus, achieving the effect of increasing the focal sound intensity. Similarly, the echo signal reflected by the sample to be measured 9 is converted into parallel waves by the second parabolic reflector and propagated to the first parabolic reflector and reflected back to the focus of the first parabolic reflector. The probe of the fiber optic hydrophone 13 receives the echo signal (enhanced echo signal) after signal enhancement at the focus. Among them, Figure 5 the circle in indicates the focus position of the first parabolic reflector 17, Figure 6 the circle in indicates the focus position of the second parabolic reflector 18.

[0095] Furthermore, as Figure 7 shown in the simulation result of the enhanced and focused on the focus of the other part of the parabolic reflector after passing through the concentrator 7, and as Figure 8 shown in the comparison result of the enhancement with the concentrator 7 and without the concentrator 7 in the matlab simulation.

[0096] It is worth mentioning that the concentrator 7 can be fixed at different positions according to actual measurement needs to achieve the functions of different focusing positions and signal enhancement degrees.

[0097] As a further improvement, the imaging device includes a fiber optic hydrophone 13, a signal amplifier 14, a data acquisition card 15, a control card, and a computer 1 connected in sequence;

[0098] The computer 1 is respectively connected to the pulsed laser 2 and the stepper motor 12 in the sample tank moving platform;

[0099] The fiber optic hydrophone 13 is used to transmit the received enhanced echo signal to the signal amplifier 14;

[0100] The signal amplifier 14 is used to amplify the enhanced echo signal, generate an amplified enhanced echo signal and transmit it to the data acquisition card 15;

[0101] The data acquisition card 15 is used to digitally process the amplified enhanced echo, generate a digital enhanced signal and transmit it to the computer 1 through the control card;

[0102] The computer 1 is used to perform imaging processing on the digital enhanced signal to generate an ultrasonic microscopy image corresponding to the sample to be measured 9.

[0103] It should be noted that the computer 1 controls the data acquisition card 15 to collect and save the amplified enhanced echo through the control card, and controls the pulsed laser 2 to turn on and the operation of the electric platform 11.

[0104] As a comparison of technical effects, reference can be made in combination with the prior art. As a non-destructive, fast and convenient biomedical imaging technology, the all-optical photoacoustic ultrasound imaging technology can achieve passive and high-frequency ultrasound imaging and provide good tissue visualization ability by combining fiber optic sensing technology. However, in existing all-optical ultrasound imaging, the optical fiber and the hydrophone are usually directly placed vertically above the sample to be measured, and the ultrasound propagates downward to the receiving sample surface and returns an echo signal. Since the ultrasonic wave will spread and attenuate during propagation, the all-optical ultrasound imaging will have the disadvantage of insufficient sensitivity.

[0105] In view of the above problems, the present invention provides a passive high-frequency all-optical ultrasonic microscopy imaging system. The system includes an optical coupling component, a first optical fiber, a second optical fiber, a fiber optic hydrophone probe, a fixing bracket, a photoacoustic transducer, a focusing device, a sample to be measured, a moving platform for the water tank with the sample, and an imaging device; a pulsed laser is connected to the imaging device. The pulsed laser emits laser light that is coupled to the optical fiber through a lens and an optical fiber coupler in sequence. The other end of the optical fiber is equipped with a photoacoustic transducer. The fiber-coupled laser beam is transmitted through the optical fiber to the other end and is converted into an ultrasonic signal by the photoacoustic transducer and emitted to the focusing device. The ultrasonic signal is focused on the sample to be measured by the focusing device, and scanning starts to generate an enhanced echo signal. Finally, the imaging device generates an ultrasonic microscopy image corresponding to the sample to be measured according to the enhanced echo signal. By using the method of the focusing device to reduce the attenuation of ultrasonic wave transmission, the intensity of the received signal can be enhanced, and the imaging functions of higher sensitivity and higher resolution can be realized, thereby realizing passive, high-frequency, and miniaturized imaging of the system, and solving the existing technical problem of low sensitivity.

[0106] In an embodiment of the present invention, the present invention provides a passive high-frequency all-optical ultrasonic microscopy imaging system. The system includes an optical coupling component, a first optical fiber, a second optical fiber, a fiber optic hydrophone probe, a fixing bracket, a photoacoustic transducer, a focusing device, a sample to be measured, a moving platform for the water tank with the sample, and an imaging device; wherein, the optical coupling component is connected to the photoacoustic transducer through the first optical fiber. Both the photoacoustic transducer and the fiber optic hydrophone probe are located at the first focal position of the focusing device; the focusing device is fixed inside the moving platform for the water tank with the sample through the fixing bracket and is located above the sample to be measured; the sample to be measured is immersed and fixed on the moving platform for the water tank with the sample and is located at the second focal position of the focusing device; the imaging device is connected to the fiber optic hydrophone probe through the second optical fiber, and the imaging device is connected to the optical coupling component; the optical coupling component is used to obtain a fiber-coupled laser beam and transmit it to the photoacoustic transducer; the photoacoustic transducer is used to convert the fiber-coupled laser beam into an ultrasonic signal and emit it to the focusing device; the focusing device is used to focus the ultrasonic signal on the sample to be measured, generate an enhanced echo signal, and transmit it to the imaging device through the fiber optic hydrophone probe; the imaging device is used to generate an ultrasonic microscopy image corresponding to the sample to be measured according to the enhanced echo signal; based on the above solution, the present invention uses the focusing device to focus the ultrasonic signal on the sample to be measured, which can enhance the intensity of the received signal. Combined with the imaging device generating an ultrasonic microscopy image corresponding to the sample to be measured according to the generated enhanced echo signal, the imaging function of higher sensitivity can be realized.

[0107] Please refer to Figure 9 , Figure 9 which is a flowchart of the steps of a passive high-frequency all-optical ultrasonic microscopy imaging method provided in Embodiment 2 of the present invention.

[0108] A passive high-frequency all-optical ultrasonic microscopy imaging method provided by the present invention includes:

[0109] Step 901: In response to an imaging request, obtain a fiber-coupled laser beam and convert the fiber-coupled laser beam into an ultrasonic signal.

[0110] Step 902: Focus the ultrasonic signal on the sample to be measured through a concentrator in a passive high-frequency all-optical ultrasonic microscopy imaging system to generate an enhanced echo signal.

[0111] Step 903: Generate an ultrasonic microscopy image corresponding to the sample to be measured based on the enhanced echo signal.

[0112] Specifically, step 903 may include the following sub-steps S31 - S33:

[0113] Step S31: Amplify the enhanced echo signal to generate an amplified enhanced echo signal;

[0114] Step S32: Digitally process the amplified enhanced echo to generate a digital enhanced signal;

[0115] Step S33: Perform imaging processing on the digital enhanced signal to generate an ultrasonic microscopy image corresponding to the sample to be measured.

[0116] It should be noted that please refer to Figure 10 , first place and fix the sample to be inspected, place the sample to be inspected in the loading water tank and immerse it in water; next, perform system settings, adjust the fiber coupler to ensure that the pulsed laser is correctly coupled to the optical fiber; place the concentrator and fix it at the set position; through the collimator, vertically immerse one end of the optical fiber equipped with the photoacoustic transducer and the end of the fiber hydrophone probe in water, that is, vertically immerse the photoacoustic transducer and the end of the fiber hydrophone probe in water and fix them at the focal position of the first parabolic reflector in the concentrator; turn on the pulsed laser, make the pulsed laser emit laser, and perform laser coupling through the lens and the fiber coupler in sequence, emit the generated fiber-coupled laser beam to the photoacoustic transducer, stimulate the photoacoustic transducer to emit ultrasonic signals and focus them on the sample to be measured through the concentrator, and at the same time, the electric platform starts to move to complete the scan, use the fiber hydrophone probe to receive the enhanced echo signals generated by the sample to be measured, transmit them to the fiber hydrophone through the second optical fiber, and collect them through a data acquisition card; finally, after signal processing of the collected enhanced echo signals, obtain an ultrasonic microscopy image corresponding to the sample to be measured.

[0117] In an embodiment of the present invention, a passive high-frequency all-optical ultrasonic microscopy imaging method is provided. When passive high-frequency all-optical ultrasonic microscopy imaging is required, a fiber-coupled laser beam is obtained and converted into an ultrasonic signal; the ultrasonic signal is focused on a sample to be measured by a condenser in the passive high-frequency all-optical ultrasonic microscopy imaging system to generate an enhanced echo signal; according to the enhanced echo signal, an ultrasonic microscopy image corresponding to the sample to be measured is generated; based on the above solution, the present invention uses the condenser in the passive high-frequency all-optical ultrasonic microscopy imaging system to focus the ultrasonic signal on the sample to be measured, which can enhance the intensity of the received signal, and then generates an ultrasonic microscopy image corresponding to the sample to be measured according to the generated enhanced echo signal, thereby realizing a higher-sensitivity imaging function; it can use a photoacoustic transducer as a small ultrasonic source to realize passive high-frequency ultrasonic imaging; a condenser with a specific shape is designed, and a method for reducing the attenuation of ultrasonic wave transmission by using the condenser is proposed, which can enhance the intensity of the received signal and realize a higher-sensitivity and higher-resolution imaging function, and solve the technical problems of low sensitivity and difficulty in performing high-resolution imaging in the case of tissue and equipment movement in the prior art.

[0118] An embodiment of the present invention also provides a computer device, including a memory and a processor, and a computer program is stored in the memory; when the computer program is executed by the processor, the processor executes the steps of the passive high-frequency all-optical ultrasonic microscopy imaging method in any of the above embodiments.

[0119] An embodiment of the present invention also provides a computer-readable storage medium, on which a computer program / instructions are stored, and when the computer program / instructions are executed by the processor, the steps of the passive high-frequency all-optical ultrasonic microscopy imaging method in any of the above embodiments are realized.

[0120] An embodiment of the present invention also provides a computer program product, including a computer program / instructions, and when the computer program / instructions are executed by the processor, the steps of the passive high-frequency all-optical ultrasonic microscopy imaging method in any of the above embodiments are realized.

[0121] In several embodiments provided in the present application, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection between each other can be through some interfaces, and the indirect coupling or communication connection of devices or units can be in electrical, mechanical or other forms.

[0122] The unit described as a separation component may or may not be physically separated. The component shown as a unit may or may not be a physical unit, that is, it may be located in one place or may be distributed across multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0123] As mentioned above, the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or equivalently replace some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A passive high-frequency all-optical ultrasonic microscopy imaging system, characterized in that The system includes an optical coupling component, a first optical fiber, a second optical fiber, an optical fiber hydrophone probe, a fixing bracket, a photoacoustic transducer, a wave concentrator, a sample to be measured, a moving platform for the water tank, and an imaging device; The optical coupling component is connected to the photoacoustic transducer through the first optical fiber, and both the photoacoustic transducer and the optical fiber hydrophone probe are located at the first focal position of the wave concentrator; The wave concentrator is fixed inside the moving platform for the water tank through the fixing bracket and is located above the sample to be measured; The sample to be measured is immersed and fixed on the moving platform for the water tank and is located at the second focal position of the wave concentrator; The imaging device is connected to the optical fiber hydrophone probe through the second optical fiber, and the imaging device is respectively connected to the optical coupling component and the moving platform for the water tank; The optical coupling component is used to obtain a fiber-coupled laser beam and transmit it to the photoacoustic transducer through the first optical fiber; The photoacoustic transducer is used to convert the fiber-coupled laser beam into an ultrasonic signal and transmit it to the wave concentrator; The wave concentrator is used to focus the ultrasonic signal on the sample to be measured, generate an enhanced echo signal and transmit it to the imaging device through the optical fiber hydrophone probe; The imaging device is used to generate an ultrasonic microscopic image corresponding to the sample to be measured according to the enhanced echo signal.

2. The passive high-frequency all-optical ultrasonic microscopy imaging system according to claim 1, wherein The optical coupling component includes a pulsed laser, a lens and a fiber coupler arranged horizontally in sequence; The pulsed laser is connected to the imaging device; The pulsed laser is used to generate a laser, and after being focused by the lens, it is emitted to the fiber coupler; The fiber coupler is used to couple the focused laser, generate a fiber-coupled laser beam and transmit it to the photoacoustic transducer through the first optical fiber.

3. The passive high-frequency all-optical ultrasonic microscopy imaging system according to claim 1, characterized in that The moving platform for the water tank includes a stepping motor, an electric platform and a water tank; The stepping motor is respectively connected to the electric platform and the imaging device; The water tank is placed on the upper surface of the electric platform; The wave concentrator is fixed inside the water tank through the fixing bracket, and the sample to be measured is immersed and fixed in the water tank; The stepping motor is used to control the movement of the electric platform.

4. The passive high-frequency all-optical ultrasonic microscopy imaging system according to claim 3, characterized in that, The wave concentrator includes a first parabolic reflector and a second parabolic reflector; The second focal position of the wave concentrator is the focal position of the second parabolic reflector; The first focal position of the wave concentrator is the focal position of the first parabolic reflector; The first parabolic reflector and the second parabolic reflector are arranged facing each other inside the water tank through the fixing bracket and are both located above the sample to be measured; The first parabolic reflector is used to convert the ultrasonic signal into a first parallel wave signal and transmit it to the second parabolic reflector, and focus the second parallel wave signal received from the second parabolic reflector to generate an enhanced echo signal and transmit it to the imaging device through the optical fiber hydrophone probe; The second parabolic reflector is configured to focus the first parallel wave signal emitted by the first parabolic reflector and then reflect it to the sample under test, and convert the echo signal generated by the sample under test based on the focused first parallel wave signal into a second parallel wave signal, and emit the second parallel wave signal to the first parabolic reflector.

5. The passive high-frequency all-optical ultrasonic microscopy imaging system according to claim 2, characterized in that, The imaging device includes a fiber optic hydrophone, a signal amplifier, a data acquisition card, a control card, and a computer, which are connected in sequence. The computer is respectively connected to the pulsed laser and the stepper motor in the carrier water tank moving platform. The fiber optic hydrophone is configured to transmit the received enhanced echo signal to the signal amplifier. The signal amplifier is configured to amplify the enhanced echo signal, generate an amplified enhanced echo signal, and transmit it to the data acquisition card. The data acquisition card is configured to perform digital processing on the amplified enhanced echo, generate a digital enhanced signal, and transmit it to the computer through the control card. The computer is configured to perform imaging processing on the digital enhanced signal to generate an ultrasonic microscopic image corresponding to the sample under test.

6. A passive high-frequency all-optical ultrasonic microscopy imaging method, characterized in that, Applied to the passive high-frequency all-optical ultrasonic microscopic imaging system according to claim 1, the method includes: In response to an imaging request, obtain a fiber-coupled laser beam and convert the fiber-coupled laser beam into an ultrasonic signal. Focus the ultrasonic signal on the sample under test through a wave concentrator in the passive high-frequency all-optical ultrasonic microscopic imaging system to generate an enhanced echo signal. Generate an ultrasonic microscopic image corresponding to the sample under test according to the enhanced echo signal.

7. The passive high-frequency all-optical ultrasonic microscopic imaging method according to claim 6, wherein The generating an ultrasonic microscopic image corresponding to the sample under test according to the enhanced echo signal includes: Amplify the enhanced echo signal to generate an amplified enhanced echo signal. Perform digital processing on the amplified enhanced echo to generate a digital enhanced signal. Perform imaging processing on the digital enhanced signal to generate an ultrasonic microscopic image corresponding to the sample under test.

8. A computer device, characterized in that, It includes a memory and a processor. When the computer program stored in the memory is executed by the processor, the processor executes the steps of the passive high-frequency all-optical ultrasonic microscopic imaging method according to any one of claims 1-6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed, it implements the passive high-frequency all-optical ultrasonic microscopic imaging method according to any one of claims 1-6.

10. A computer program product, characterized in that, The computer program product includes a computer program stored on a non-transitory computer-readable storage medium. The computer program includes program instructions. When the program instructions are executed by a computer, the computer executes the passive high-frequency all-optical ultrasonic microscopic imaging method according to any one of claims 1-6.

Images