Photoacoustic focusable endoscopic imaging device and method based on temperature control memory alloy

Abstract

The invention discloses a photoacoustic focusable endoscopic imaging device based on temperature control memory alloy and an imaging method. The photoacoustic focusable endoscopic imaging device comprises a bidirectional memory metal photoacoustic zoom module, the bidirectional memory metal optical-acoustic zoom module comprises an optical fiber fixing clamp, a gradient refractive index lens, a light-reflecting and sound-reflecting mirror, a transducer, a temperature control memory alloy spring and a temperature control deformation current controller, the optical fiber fixing clamp is used for clamping an optical fiber outer sleeve, and the bidirectional memory alloy spring is connected with the optical fiber fixing clamp; the optical fiber outer sleeve and the single-mode optical fiber penetrate through the center of the temperature control memory alloy spring, and the temperature control memory alloy spring can be controlled to deform through the temperature control deformation current controller, so that the position of the single-mode optical fiber relative to the gradual change refractive index lens is changed. By applying the temperature control memory alloy spring to photoacoustic endoscopy, dynamic infinitesimal displacement of an optical device is realized based on the characteristic that the temperature control memory alloy spring deforms differently at different temperatures, so that dynamic focusing is realized, and the limitation of depth of field is overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of photoacoustic endoscopy, and in particular to a photoacoustic focus-adjustable endoscopy imaging device and an imaging method based on a temperature-controlled memory alloy. Background Art

[0002] Photoacoustic imaging is an advanced biomedical imaging method that induces rapid temperature rise and expansion of light-absorbing media through short-pulse laser irradiation, generating photoacoustic signals. This signal carries the light absorption characteristic information of the tissue, and through detection and analysis, it can achieve non-invasive acquisition of high-resolution light absorption distribution images of biological tissues. Photoacoustic imaging technology combines the advantages of optics and ultrasound, with high selectivity, resolution and deep penetration capabilities. It has been successfully applied in the field of endoscopic imaging, providing strong support for biomedical research and clinical diagnosis, and expanding the in-depth understanding of the structure and function of biological tissues. With the development of technology, photoacoustic imaging will further promote innovation and progress in the field of medical imaging.

[0003] The challenges encountered in the practical application of photoacoustic endoscopic imaging technology are not only limited to high-resolution imaging in a focal or near-focus small area, but also involve the complexity of the beam characteristics. The focal length of the Gaussian beam is relatively small, so once the beam deviates from the focus, it will diverge rapidly, which puts forward severe requirements for precise imaging. The position deviation of the endoscope probe and the irregularity and asymmetry of the sample itself make it difficult to accurately position the Gaussian beam of fixed focal length in the tissue, which increases the complexity in actual operation. As a result, the imaging resolution outside the focus drops sharply, which seriously affects the imaging quality, and further reduces the signal-to-noise ratio of the imaging, limiting the accuracy of photoacoustic endoscopy in detecting subtle structures and lesions. Especially in the body, the complexity and changes of tissue structure introduce additional challenges, making high-resolution imaging more urgent.

[0004] Various methods have been proposed to overcome this limitation, but they are still a challenge due to the tiny size of the endoscope probe. A Bessel-like annular beam is generated in the endoscope with high lateral resolution and large degrees of freedom. However, the gain in depth of focus is very limited, resulting in a loss in light energy density. The multi-focus method can also achieve focal depth extension, but there is also a problem of light energy density loss. Liquid lenses and the like can be used in optically adjustable systems, but they still have difficulties in miniaturization, stability or high resolution for use in endoscope probes. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a photoacoustic adjustable focus endoscopic imaging device and imaging method based on a temperature-controlled memory alloy, which solves the problem that the prior art methods are difficult to image with high resolution.

[0006] The technical solution of the present invention is: a photoacoustic adjustable focus endoscopic imaging device based on temperature-controlled memory alloy, comprising:

[0007] Probe support structure, photoacoustic excitation and light transmission module, two-way memory metal photoacoustic zoom module, endoscopy drive scanning control module and signal acquisition and image reconstruction module;

[0008] The photoacoustic excitation and optical transmission module includes a pulse laser, a laser coupler, a single-mode optical fiber and a smooth ring. The laser coupler can couple the pulse laser emitted by the pulse laser into the single-mode optical fiber and emit it through the rotor end of the smooth ring. The single-mode optical fiber is provided with an optical fiber outer sleeve.

[0009] The bidirectional memory metal optical-acoustic zoom module includes an optical fiber fixing clamp, a gradient refractive index lens, a reflective acoustic mirror, a transducer, a temperature-controlled memory alloy spring and a temperature-controlled deformation current controller. The optical fiber fixing clamp is arranged in the probe support structure. The optical fiber fixing clamp is used to clamp the optical fiber outer sleeve. The temperature-controlled memory alloy spring is respectively connected to the optical fiber fixing clamp and the single-mode optical fiber. The optical fiber outer sleeve and the single-mode optical fiber pass through the center of the temperature-controlled memory alloy spring. The temperature-controlled deformation current controller can control the temperature-controlled memory alloy spring to produce deformation so that the single-mode optical fiber The position of the optical fiber relative to the gradient refractive index lens changes, the gradient refractive index lens is arranged in the probe support structure and is located on the side of the output end face of the single-mode optical fiber, the single-mode optical fiber and the gradient refractive index lens are arranged coaxially, the reflective acoustic mirror is arranged obliquely in the probe support structure and is located on the side of the gradient refractive index lens away from the single-mode optical fiber, the reflective acoustic mirror is used to make the laser emit from the probe support structure, the transducer is located between the gradient refractive index lens and the reflective acoustic mirror, and the transducer is used to receive the acoustic signal reflected by the reflective acoustic mirror;

[0010] The endoscope drive scanning control system comprises a stepper motor, a rotary motor, a transmission torsion coil, a transmission rod and a motor driver; the motor driver is electrically connected to the stepper motor and the rotary motor respectively, the stepper motor and the rotary motor are both connected to the transmission torsion coil, the rotary motor is connected to the transmission rod, one end of the transmission torsion coil is connected to the transmission rod, and the other end is connected to the probe support structure, the rotor end of the smooth ring rotates with the transmission rod, and the stepper motor is used to drive the probe support structure to move;

[0011] The signal acquisition and image reconstruction module includes a transmission signal line, an electric slip ring, a signal amplifier, a filter and an acquisition card; the transmission signal line is connected to the transducer, the electric slip ring, the signal amplifier, the filter and the acquisition card, the electric slip ring is located outside the slip ring, and the rotor end of the electric slip ring is connected to the probe support structure.

[0012] Furthermore, the temperature-controlled deformation current controller can control the temperature-controlled memory alloy spring to expand and contract along the axial direction of the single-mode optical fiber, so that the position of the single-mode optical fiber relative to the gradient refractive index lens changes, thereby changing the laser focus position.

[0013] Furthermore, the transducer is a hollow focusing transducer or a multi-focus telephoto transducer, and the transducer is coaxial with the single-mode optical fiber, the gradient refractive index lens and the reflective acoustic mirror to make the photoacoustic signal coaxial.

[0014] Furthermore, the reflective acoustic mirror has no light window, so that the exit end face of the gradient refractive index lens, the transducer and the reflective surface of the reflective acoustic mirror are placed in a water environment.

[0015] Furthermore, the inclination angle of the light-reflecting and sound-reflecting mirror is 45°.

[0016] The present application also provides another technical solution: the imaging method of the above-mentioned photoacoustic adjustable focus endoscopic imaging device based on temperature-controlled memory alloy comprises the following steps:

[0017] Step S1: Excitation and transmission, the pulse laser emitted by the pulse laser is incident into the single-mode optical fiber through the laser coupler, transmitted in the single-mode optical fiber, passes through the smooth ring, and is emitted from the optical fiber at the rotor end of the smooth ring, and a focused light beam is emitted through the gradient refractive index lens. The focused light beam propagates in the water environment, is reflected by the reflective acoustic mirror to the probe support structure, and is irradiated onto the sample to excite a photoacoustic signal;

[0018] Step S2: data acquisition, the photoacoustic signal generated by the sample absorbing light energy is transmitted to the reflective acoustic mirror in the water environment, reflected by the reflective acoustic mirror to the surface of the transducer, and detected by the transducer. The photoacoustic signal is sequentially transmitted to the rotor end of the electric slip ring, the stator end of the electric slip ring, the signal amplifier, the filter and the acquisition card through the transmission signal line, and finally the signal is converted by the AC / DC conversion module of the signal acquisition circuit on the acquisition card;

[0019] Step S3: zoom scanning, the motor driver controls the rotating motor to work, the rotating motor drives the transmission rod to rotate, and the transmission rod drives the probe support structure to rotate through the transmission torsion coil. Every time it rotates a certain angle, the temperature-controlled deformation current controller adjusts the current passing through the temperature-controlled memory alloy spring to make the temperature-controlled memory alloy spring expand and contract, driving the single-mode optical fiber to move back and forth along the axial direction, so that the focus performs a back-and-forth scan. After completing a 360° scan at the current position, the stepper motor drives the probe support structure forward to perform a 360° scan at the next position;

[0020] Step S4: Image reconstruction and display. The computer stores and processes the collected data to complete the photoacoustic image reconstruction.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention applies a temperature-controlled memory alloy spring to photoacoustic endoscopy. Based on the characteristics of different deformations of the temperature-controlled memory alloy spring at different temperatures, the dynamic micro-displacement of the optical device is realized, thereby achieving dynamic focusing to overcome the depth of field limitation. The photoacoustic focus-adjustable endoscopy imaging device based on the temperature-controlled memory alloy can provide imaging with a large scanning range, high resolution and no sensitivity loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of the photoacoustic adjustable focus endoscopic imaging device of the present invention.

[0024] Figure 2 It is a schematic diagram of the extended state of the temperature-controlled memory alloy spring of the present invention.

[0025] Figure 3 It is a schematic diagram of the contraction state of the temperature-controlled memory alloy spring of the present invention.

[0026] Figure 4 Schematic diagram of the workflow of the imaging method of the present invention.

[0027] 1-reflective and acoustic mirror, 2-transducer, 3-gradient refractive index lens, 4-probe support structure, 5-single-mode optical fiber, 6-temperature-controlled memory alloy spring, 7-transmission torsion coil, 8-optical fiber fixing clamp, 9-computer, 10-acquisition card, 11-temperature-controlled deformation current controller, 12-motor driver, 13-pulse laser, 14-electric slip ring, 15-filter, 16-rotating motor, 17-slip ring, 18-sample, 19-signal amplifier. DETAILED DESCRIPTION

[0028] In order to facilitate the understanding of the present invention, the present invention is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on the other element, or there can be one or more centered elements therebetween. When an element is described as "connected to" another element, it can be directly connected to the other element, or there can be one or more centered elements therebetween. The terms "upper", "lower", "left", "right", "inside", "outside" and similar expressions used in this specification are for illustrative purposes only.

[0029] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification and in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0030] In order to solve the problem that existing methods are difficult to image with high resolution, the present application provides a photoacoustic adjustable focus endoscopic imaging device based on a temperature-controlled memory alloy.

[0031] In some embodiments, Figure 1 , Figure 2 and Figure 3 As shown, a photoacoustic adjustable focus endoscopic imaging device based on a temperature-controlled memory alloy is provided, comprising:

[0032] Probe support structure 4, photoacoustic excitation and light transmission module, two-way memory metal photoacoustic zoom module, endoscopy drive scanning control module and signal acquisition and image reconstruction module;

[0033] The photoacoustic excitation and optical transmission module includes a pulse laser 13, a laser coupler, a single-mode optical fiber 5 and a smooth ring 17. The laser coupler can couple the pulse laser emitted by the pulse laser 13 into the single-mode optical fiber 5 and emit it through the rotor end of the smooth ring 17. The single-mode optical fiber 5 is provided with an optical fiber outer sleeve.

[0034] The bidirectional memory metal light-acoustic zoom module includes an optical fiber fixing clamp 8, a gradient refractive index lens 3, a reflective acoustic mirror 1, a transducer 2, a temperature-controlled memory alloy spring 6 and a temperature-controlled deformation current controller 11. The optical fiber fixing clamp 8 is arranged in the probe support structure 4. The optical fiber fixing clamp 8 is used to clamp the optical fiber outer sleeve. The temperature-controlled memory alloy spring 6 is respectively connected to the optical fiber fixing clamp 8 and the single-mode optical fiber 5. The optical fiber outer sleeve and the single-mode optical fiber 5 pass through the center of the temperature-controlled memory alloy spring 6. The temperature-controlled deformation current controller 11 can control the temperature-controlled memory alloy spring 6 to produce deformation so that the single-mode optical fiber 5 The position of the optical fiber 5 relative to the gradient refractive index lens 3 changes, the gradient refractive index lens 3 is arranged in the probe support structure 4, and is located on the side of the output end face of the single-mode optical fiber 5, the single-mode optical fiber 5 and the gradient refractive index lens 3 are coaxially arranged, the reflective acoustic mirror 1 is tiltedly arranged in the probe support structure 4, and is located on the side of the gradient refractive index lens 3 away from the single-mode optical fiber 5, the reflective acoustic mirror 1 is used to make the laser emit from the probe support structure 4, the transducer 2 is located between the gradient refractive index lens 3 and the reflective acoustic mirror 1, and the transducer 2 is used to receive the acoustic signal reflected by the reflective acoustic mirror 1;

[0035] The endoscope drive scanning control system includes a stepper motor, a rotary motor 16, a transmission torsion coil 7, a transmission rod and a motor driver 12; the motor driver 12 is electrically connected to the stepper motor and the rotary motor 16 respectively, the stepper motor and the rotary motor 16 are both connected to the transmission torsion coil 7, the rotary motor 16 drives the transmission rod to rotate, one end of the transmission torsion coil 7 is connected to the transmission rod, and the other end is connected to the probe support structure 4, the rotor end of the smooth ring 17 rotates with the transmission rod, and the stepper motor is used to drive the probe support structure 4 to move;

[0036] The signal acquisition and image reconstruction module includes a transmission signal line, an electric slip ring 14, a signal amplifier 19, a filter 15 and an acquisition card 10; the transmission signal line is connected to the transducer 2, the electric slip ring 14, the signal amplifier 19, the filter 15 and the acquisition card 10, the electric slip ring 14 is located outside the slip ring 17, and the rotor end of the electric slip ring 14 is connected to the probe support structure 4.

[0037] In some embodiments, Figure 1 , Figure 2 and Figure 3As shown, the temperature-controlled deformation current controller 11 can control the temperature-controlled memory alloy spring 6 to expand and contract along the axial direction of the single-mode optical fiber 5, so that the position of the single-mode optical fiber 5 relative to the gradient refractive index lens 3 changes, thereby changing the laser focus position. The lattice structure of the metal is related to the temperature, and the lattice structure can be changed by changing the temperature.

[0038] In other embodiments, the temperature-controlled memory alloy spring 6 may not deform along the axial direction of the single-mode optical fiber 5, as long as the temperature-controlled memory alloy spring 6 can drive the optical fiber fixing clamp 8 to move when deformed, and no limitation is made here.

[0039] In some embodiments, the temperature-controlled memory alloy spring 6 is made of nickel and titanium.

[0040] In some embodiments, Figure 1 , Figure 2 and Figure 3 As shown, the transducer 2 is a hollow focusing transducer or a multi-focus telephoto transducer, and the transducer 2 is coaxial with the single-mode optical fiber 5, the gradient refractive index lens 3 and the reflective acoustic mirror 1 to make the photoacoustic signal coaxial.

[0041] In some embodiments, Figure 1 , Figure 2 and Figure 3 As shown, the reflective acoustic mirror 1 has no light window, so that the exit end surface of the gradient refractive index lens 3, the transducer 2 and the reflective surface of the reflective acoustic mirror 1 are placed in a water environment.

[0042] In some embodiments, Figure 1 As shown, the inclination angle of the light-reflecting and sound-reflecting mirror 1 is 45°.

[0043] In some embodiments, the transmission torsion coil is made of stainless steel, and the transmission torsion coil is used to enable the transmission rod to drive the probe support structure to rotate in a 1:1 ratio.

[0044] like Figure 1 and Figure 4 As shown, the present application also provides an imaging method of the above-mentioned photoacoustic adjustable focus endoscopic imaging device based on the temperature-controlled memory alloy, comprising the following steps:

[0045] Step S1: excitation and transmission, the pulse laser emitted by the pulse laser 13 is incident into the single-mode optical fiber 5 through the laser coupler, transmitted in the single-mode optical fiber 5, passes through the smooth ring 17, and is emitted from the optical fiber at the rotor end of the smooth ring 17, and a focused light beam is emitted through the gradient refractive index lens 3, and the focused light beam propagates in the water environment, is reflected by the reflective acoustic mirror 1 to the probe support structure 4, and the focused light beam is irradiated onto the sample 18 to excite a photoacoustic signal;

[0046] Step S2: data acquisition, the photoacoustic signal generated by the sample 18 absorbing light energy is transmitted to the reflective acoustic mirror 1 in the water environment, reflected by the reflective acoustic mirror 1 to the surface of the transducer 2, and detected by the transducer 2. The photoacoustic signal is sequentially transmitted to the rotor end of the electric slip ring 14, the stator end of the electric slip ring 14, the signal amplifier 19, the filter 15 and the acquisition card 10 through the transmission signal line, and finally the signal is converted by the AC / DC conversion module of the signal acquisition circuit on the acquisition card 10;

[0047] Step S3: zoom scanning, the motor driver 12 controls the rotating motor 16 to work, the rotating motor 16 drives the transmission rod to rotate, and the transmission rod drives the probe support structure 4 to rotate through the transmission torsion coil 7. Every time it rotates a certain angle, the temperature-controlled deformation current controller 11 adjusts the current passing through the temperature-controlled memory alloy spring 6 to make the temperature-controlled memory alloy spring 6 expand and contract, driving the single-mode optical fiber 5 to move back and forth along the axial direction, so that the focus performs a back-and-forth scan. After completing a 360° scan of the current position, the stepper motor drives the probe support structure 4 forward to perform a 360° scan of the next position;

[0048] Step S4: Image reconstruction and display. The computer 9 stores and processes the collected data to complete the photoacoustic image reconstruction.

[0049] The present application applies the temperature-controlled memory alloy spring 6 to photoacoustic endoscopy, and based on the characteristics of different deformations of the temperature-controlled memory alloy spring 6 at different temperatures, realizes dynamic micro-displacement of the optical device, thereby realizing dynamic focusing to overcome the depth of field limitation. The photoacoustic focus-adjustable endoscopy imaging device based on the temperature-controlled memory alloy can provide imaging with a large scanning range, high resolution, and no sensitivity loss.

[0050] It should be noted that the preferred embodiments of the present invention are given in the specification and drawings of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. These embodiments are not used as additional limitations on the content of the present invention. The purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive. In addition, the above-mentioned technical features continue to be combined with each other to form various embodiments not listed above, which are all regarded as the scope of the present invention; further, for ordinary technicians in this field, they can be improved or transformed according to the above description, and all these improvements and transformations should belong to the protection scope of the claims attached to the present invention.

Claims

1. A photoacoustic adjustable focus endoscopic imaging device based on a temperature-controlled memory alloy, characterized in that: include, Probe support structure, photoacoustic excitation and light transmission module, two-way memory metal photoacoustic zoom module, endoscopy drive scanning control module and signal acquisition and image reconstruction module; The photoacoustic excitation and optical transmission module includes a pulse laser, a laser coupler, a single-mode optical fiber and a smooth ring. The laser coupler can couple the pulse laser emitted by the pulse laser into the single-mode optical fiber and emit it through the rotor end of the smooth ring. The single-mode optical fiber is provided with an optical fiber outer sleeve. The bidirectional memory metal optical-acoustic zoom module includes an optical fiber fixing clamp, a gradient refractive index lens, a reflective acoustic mirror, a transducer, a temperature-controlled memory alloy spring and a temperature-controlled deformation current controller. The optical fiber fixing clamp is arranged in the probe support structure. The optical fiber fixing clamp is used to clamp the optical fiber outer sleeve. The temperature-controlled memory alloy spring is respectively connected to the optical fiber fixing clamp and the single-mode optical fiber. The optical fiber outer sleeve and the single-mode optical fiber pass through the center of the temperature-controlled memory alloy spring. The temperature-controlled deformation current controller can control the temperature-controlled memory alloy spring to produce deformation so that the single-mode optical fiber The position of the optical fiber relative to the gradient refractive index lens changes, the gradient refractive index lens is arranged in the probe support structure and is located on the side of the output end face of the single-mode optical fiber, the single-mode optical fiber and the gradient refractive index lens are arranged coaxially, the reflective acoustic mirror is arranged obliquely in the probe support structure and is located on the side of the gradient refractive index lens away from the single-mode optical fiber, the reflective acoustic mirror is used to make the laser emit from the probe support structure, the transducer is located between the gradient refractive index lens and the reflective acoustic mirror, and the transducer is used to receive the acoustic signal reflected by the reflective acoustic mirror; The endoscope drive scanning control system comprises a stepper motor, a rotary motor, a transmission torsion coil, a transmission rod and a motor driver; the motor driver is electrically connected to the stepper motor and the rotary motor respectively, the stepper motor and the rotary motor are both connected to the transmission torsion coil, the rotary motor is connected to the transmission rod, one end of the transmission torsion coil is connected to the transmission rod, and the other end is connected to the probe support structure, the rotor end of the smooth ring rotates with the transmission rod, and the stepper motor is used to drive the probe support structure to move; The signal acquisition and image reconstruction module includes a transmission signal line, an electric slip ring, a signal amplifier, a filter and an acquisition card; the transmission signal line is connected to the transducer, the electric slip ring, the signal amplifier, the filter and the acquisition card, the electric slip ring is located outside the slip ring, and the rotor end of the electric slip ring is connected to the probe support structure.

2. The photoacoustic adjustable focus endoscopic imaging device based on temperature-controlled memory alloy according to claim 1, characterized in that: The temperature-controlled deformation current controller can control the temperature-controlled memory alloy spring to expand and contract along the axial direction of the single-mode optical fiber, so that the position of the single-mode optical fiber relative to the gradient refractive index lens changes, thereby changing the laser focus position.

3. The photoacoustic adjustable focus endoscopic imaging device based on temperature-controlled memory alloy according to claim 1, characterized in that: The transducer is a hollow focusing transducer or a multi-focus telephoto transducer, and the transducer is coaxial with the single-mode optical fiber, the gradient refractive index lens and the reflective acoustic mirror to make the photoacoustic signal coaxial.

4. The photoacoustic adjustable focus endoscopic imaging device based on temperature-controlled memory alloy according to claim 1, characterized in that: The light-reflecting and sound-reflecting mirror has no light window, so that the exit end surface of the gradient refractive index lens, the transducer and the reflecting surface of the light-reflecting and sound-reflecting mirror are placed in a water environment.

5. The photoacoustic adjustable focus endoscopic imaging device based on temperature-controlled memory alloy according to claim 1, characterized in that: The inclination angle of the light-reflecting and sound-reflecting mirror is 45°.

6. The imaging method of the photoacoustic adjustable focus endoscopic imaging device based on the temperature-controlled memory alloy according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step S1: Excitation and transmission, the pulse laser emitted by the pulse laser is incident into the single-mode optical fiber through the laser coupler, transmitted in the single-mode optical fiber, passes through the smooth ring, and is emitted from the optical fiber at the rotor end of the smooth ring, and a focused light beam is emitted through the gradient refractive index lens. The focused light beam propagates in the water environment, is reflected by the reflective acoustic mirror to the probe support structure, and is irradiated onto the sample to excite a photoacoustic signal; Step S2: data acquisition, the photoacoustic signal generated by the sample absorbing light energy is transmitted to the reflective acoustic mirror in the water environment, reflected by the reflective acoustic mirror to the surface of the transducer, and detected by the transducer. The photoacoustic signal is sequentially transmitted to the rotor end of the electric slip ring, the stator end of the electric slip ring, the signal amplifier, the filter and the acquisition card through the transmission signal line, and finally the signal is converted by the AC / DC conversion module of the signal acquisition circuit on the acquisition card; Step S3: zoom scanning, the motor driver controls the rotating motor to work, the rotating motor drives the transmission rod to rotate, and the transmission rod drives the probe support structure to rotate through the transmission torsion coil. Every time it rotates a certain angle, the temperature-controlled deformation current controller adjusts the current passing through the temperature-controlled memory alloy spring to make the temperature-controlled memory alloy spring expand and contract, driving the single-mode optical fiber to move back and forth along the axial direction, so that the focus performs a back-and-forth scan. After completing a 360° scan at the current position, the stepper motor drives the probe support structure forward to perform a 360° scan at the next position; Step S4: Image reconstruction and display. The computer stores and processes the collected data to complete the photoacoustic image reconstruction.

Images