A photoacoustic probe and photoacoustic imaging system

Abstract

This utility model discloses a photoacoustic probe and a photoacoustic imaging system. The photoacoustic probe includes a tube, a light guide, a signal line, a lens group, a reflective element, and an ultrasonic transducer. The light guide and the signal line pass through the tube along its axial direction. The signal line is electrically connected to the ultrasonic transducer. The lens group, reflective element, and ultrasonic transducer are all disposed within the tube and arranged sequentially along its axial direction. The lens group is located on the light-emitting side of the light guide and includes at least one curved lens. The light guide guides the light beam and directs it to the lens group. The lens group converges the light beam, directing it to the reflective element. The reflective element reflects the converged light beam, allowing it to pass through the tube and exit onto the target area within the imaging region. The ultrasonic transducer converts the ultrasonic waves received from the target area into electrical signals. By converging the light beam through the lens group, the size of the light spot illuminating the target area is reduced, thus improving the lateral resolution.

Description

Technical Field

[0001] This utility model relates to the field of photoacoustic imaging, and in particular to a photoacoustic probe and a photoacoustic imaging system. Background Technology

[0002] Compared to ultrasound probes, photoacoustic probes have the advantage of optical imaging resolution. Because the differences in light absorption characteristics of different components or structural forms of human tissue are much greater than the differences in sound reflection characteristics, photoacoustic imaging has higher grayscale resolution.

[0003] The imaging principle of the photoacoustic probe is as follows: the photoacoustic probe emits a light beam and illuminates the target area, the target area generates ultrasonic waves, the ultrasonic transducer of the photoacoustic probe converts the received ultrasonic waves into electrical signals, and an image can be generated based on the electrical signals; the photoacoustic probe is controlled to rotate to scan different positions around the cavity being inspected, and the signals obtained from scanning different positions around the circumference are stitched together in sequence to obtain a complete image.

[0004] When the spot size of the beam emitted by the photoacoustic probe is smaller than the lateral dimension of the ultrasonic transducer, the spot size of the beam determines the lateral resolution of the photoacoustic probe. In the prior art, in order to achieve a higher lateral resolution, photoacoustic probes use optical fibers with a small numerical aperture. The beam emitted from the optical fiber illuminates the target area after exiting the photoacoustic probe. However, the lateral resolution that can be achieved still cannot meet the expected application requirements. Utility Model Content

[0005] The purpose of this invention is to provide a photoacoustic probe and a photoacoustic imaging system that can improve lateral resolution.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A photoacoustic probe includes a tube, a light guide, a signal line, a lens group, a reflective element, and an ultrasonic transducer;

[0008] The light guide and the signal line pass through the tube body along the axial direction of the tube body, and the signal line is electrically connected to the ultrasonic transducer.

[0009] The lens group, the reflective element, and the ultrasonic transducer are all disposed within the tube and arranged sequentially along the axial direction of the tube. The lens group is disposed on the light-emitting side of the light guide and includes at least one curved lens.

[0010] The light guide is used to guide the transmission of the light beam and cause the light beam to be incident on the lens group. The lens group is used to converge the light beam so that the converged light beam is incident on the reflective element. The reflective element is used to reflect the converged light beam along a direction that forms a preset angle with the axis of the tube body, so that the converged light beam passes through the tube body and is emitted to the target part in the imaging area. The ultrasonic transducer is used to convert the ultrasonic waves received from the target part into electrical signals.

[0011] Optionally, the lens group includes a first curved lens and a second curved lens, wherein the focal length of one of the first curved lens and the second curved lens is positive and the focal length of the other is negative.

[0012] Optionally, the first curved lens and the second curved lens are arranged sequentially along the direction from the light guide to the reflective element, and the focal length of the first curved lens is negative and the focal length of the second curved lens is positive.

[0013] Optionally, there is a gap between the first curved lens and the second curved lens, and the gap is filled with air.

[0014] Optionally, the first curved lens and the second curved lens are sealed within the cylinder, with a gap between them, and the gap between them is filled with a medium whose refractive index is less than 1.33.

[0015] Optionally, the lens group includes a third curved lens, which is an aspherical lens.

[0016] Optionally, the lateral magnification of the lens group is greater than 2.

[0017] Optionally, the light guide includes a core layer and a cladding layer covering the outside of the core layer, wherein the refractive index of the core layer is greater than that of the cladding layer, so that the light beam is transmitted along the core layer, and the diameter of the core layer is not less than 50 μm.

[0018] Optionally, the length direction of the ultrasonic transducer is arranged along the axial direction of the tube body.

[0019] A photoacoustic imaging system, comprising:

[0020] A light source for emitting a light beam, which is then transmitted into a light guide of the photoacoustic probe;

[0021] The photoacoustic probe described in any of the above embodiments is used to emit the light beam and illuminate the target area within the imaging region, and to convert the ultrasonic waves received from the target area into electrical signals.

[0022] The host module is electrically connected to the signal line of the photoacoustic probe and is used to receive the electrical signals transmitted back by the photoacoustic probe.

[0023] As can be seen from the above technical solution, the photoacoustic probe provided by this utility model includes a tube body, a light guide, a signal line, a lens group, a reflective element, and an ultrasonic transducer. The light guide and the signal line pass through the tube body along the axial direction, and the signal line is electrically connected to the ultrasonic transducer. The lens group, the reflective element, and the ultrasonic transducer are all disposed in the tube body and arranged sequentially along the axial direction of the tube body. The lens group is disposed on the light-emitting side of the light guide and includes at least one curved lens. The light guide is used to guide the transmission of the light beam and cause the light beam to be incident on the lens group. The lens group is used to converge the light beam so that the converged light beam is incident on the reflective element. The reflective element is used to reflect the converged light beam so that the converged light beam is reflected along a direction that forms a preset angle with the axial direction of the tube body, so that the converged light beam passes through the tube body and is emitted to the target part in the imaging area. The ultrasonic transducer is used to convert the ultrasonic waves received from the target part into electrical signals. In the photoacoustic probe of this invention, the light beam emitted from the light guide passes through a lens group, which converges the light beam so that the converged light beam exits from the tube and irradiates the target area. By converging the light beam through the lens group, the size of the light spot irradiating the target area is smaller, thus improving the lateral resolution.

[0024] The photoacoustic imaging system provided by this utility model can achieve the above-mentioned beneficial effects. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of an existing photoacoustic probe;

[0027] Figure 2 This is a schematic diagram of the structure of a photoacoustic probe according to an embodiment of the present invention;

[0028] Figure 3 A schematic diagram of light propagation of a photoacoustic probe provided in an embodiment of this utility model;

[0029] Figure 4 This is a schematic diagram of a photoacoustic imaging system provided in an embodiment of the present invention.

[0030] The reference numerals in the accompanying drawings include:

[0031] 100 - Cavity under test, 101 - Probe sheath, 102 - Optical fiber, 103 - Reflecting prism, 104 - Single-element ultrasonic transducer, 201 - Tube body, 202 - Light guide, 203 - Lens group, 304 - First curved lens, 305 - Second curved lens, 206 - Reflecting element, 207 - Ultrasonic transducer, A - Beam, B - Sound beam range, C - Beam spot on the cavity under test, D - Main plane of the lens group. Detailed Implementation

[0032] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this utility model.

[0033] The imaging principle of the photoacoustic probe is as follows: the photoacoustic probe emits a light beam and illuminates the target area, which generates ultrasonic waves. The ultrasonic transducer of the photoacoustic probe converts the received ultrasonic waves into electrical signals, and an image can be generated based on the electrical signals. The photoacoustic probe is controlled to rotate to scan different positions around the cavity being inspected. The signals obtained from scanning different positions around the circumference are then stitched together to obtain a complete image.

[0034] The lateral resolution of a photoacoustic probe is determined by either the lateral dimensions of the ultrasonic transducer or the spot size of the beam emitted by the photoacoustic probe. If the spot size of the beam emitted by the photoacoustic probe is large, the lateral resolution of the photoacoustic probe is approximately equal to the lateral dimensions of the ultrasonic transducer. If the spot size of the beam emitted by the photoacoustic probe is smaller than the lateral dimensions of the ultrasonic transducer, then the lateral resolution of the photoacoustic probe is equal to the spot size of the beam emitted by the photoacoustic probe.

[0035] However, existing photoacoustic probes use optical fibers with small numerical apertures. The beam emitted from these fibers illuminates the target area, and the lateral resolution achievable still cannot meet the desired application requirements. For example, see reference... Figure 1 , Figure 1The diagram shows a schematic of an existing photoacoustic probe. A reflecting prism 103 and a single-element ultrasonic transducer 104 are housed within the probe sheath 101. An optical fiber 102 passes through the probe sheath 101. A laser beam exits from the optical fiber 102, is reflected by the reflecting prism 103, and then exits from the probe sheath 101, illuminating the cavity 100 under test. Assuming the numerical aperture of the optical fiber 102 is NA, and the distance of the laser beam from the optical fiber 102 to the cavity 100 under test is L, neglecting the effects of tilt caused by other components (such as the reflecting prism 103 and the sheath wall) and the refractive index of the liquid environment, the lateral dimension φ of the laser beam in the cavity 100 under test can be expressed as: φ≈2*L*NA. Commonly, NA is taken as 0.11, and L as 4.5 mm, then the lateral dimension φ of the laser beam in the cavity 100 under test is approximately 0.99 mm. Figure 1 As shown, the size of the light spot C on the cavity 100 under inspection is relatively large, and it is close to the size corresponding to the sound beam range B of the single-element ultrasonic transducer 104, that is, the lateral dimension of the single-element ultrasonic transducer 104.

[0036] To address this issue, this invention provides a photoacoustic probe and a photoacoustic imaging system that can improve lateral resolution.

[0037] This embodiment provides a photoacoustic probe, including a tube, a light guide, a signal line, a lens group, a reflective element, and an ultrasonic transducer. The light guide and the signal line pass through the tube along the axial direction of the tube, and the signal line is electrically connected to the ultrasonic transducer.

[0038] The lens group, the reflective element, and the ultrasonic transducer are all disposed within the tube and arranged sequentially along the axial direction of the tube. The lens group is disposed on the light-emitting side of the light guide and includes at least one curved lens.

[0039] The light guide is used to guide the transmission of the light beam and cause the light beam to be incident on the lens group. The lens group is used to converge the light beam so that the converged light beam is incident on the reflective element. The reflective element is used to reflect the converged light beam along a direction that forms a preset angle with the axis of the tube body, so that the converged light beam passes through the tube body and is emitted to the target part in the imaging area. The ultrasonic transducer is used to convert the ultrasonic waves received from the target part into electrical signals.

[0040] The curved lens includes a first surface and a second surface, allowing a light beam to be refracted into the curved lens from the first surface and refracted out from the second surface. At least one of the first and second surfaces is curved. In the photoacoustic probe of this embodiment, the light beam emitted from the light guide passes through a lens group, which converges the light beam, causing the converged beam to exit from the tube and illuminate the target area. By converging the light beam through the lens group, the size of the light spot illuminating the target area is reduced, thus improving the lateral resolution.

[0041] In this embodiment, the number of curved lenses included in the lens group and the surface shape of the curved lenses are not limited. In some embodiments, the lens group may include at least two curved lenses. Using multiple curved lenses can effectively focus the light beam, resulting in a smaller beam spot size illuminating the target area and improving lateral resolution. Any curved lens can be a spherical lens, where both the first and second surfaces are spherical. Spherical lenses are easier to manufacture and have lower costs. If a single spherical lens is used, its aberrations are large, and it cannot effectively focus the light beam. In contrast, using two or more spherical lenses can achieve a better focusing effect on the light beam.

[0042] In some embodiments, the lens group may include a first curved lens and a second curved lens, wherein one of the first and second curved lenses has a positive focal length and the other has a negative focal length; that is, one is a positive lens and the other is a negative lens. The spherical aberration of the negative lens is opposite to that of the positive lens, and their combined use can correct spherical aberration and reduce beam spread. Using too many curved lenses will increase the length of the lens group and the size of the photoacoustic probe, which is not conducive to the miniaturization of the photoacoustic probe. Using two curved lenses can avoid making the photoacoustic probe too large while achieving good beam focusing. The positive lens can be a biconvex lens or a plano-convex lens, and the negative lens can be a biconcave lens or a plano-concave lens.

[0043] In some embodiments, a first curved lens and a second curved lens are sequentially arranged along the direction from the light guide to the reflective element, with the first curved lens having a negative focal length and the second curved lens having a positive focal length. To ensure that the axial length of the photoacoustic probe is not excessively long, the foremost lens of the lens group needs to be placed close to the light guide. If the foremost lens is a positive lens, it will converge the light beam, failing to amplify the beam emitted from the light guide. Without amplification, the beam cannot be refocused at a distance, hindering the achievement of a deeper imaging depth. Therefore, in this embodiment, a negative lens is used for the foremost lens close to the light guide, which helps the photoacoustic probe achieve a deeper imaging depth.

[0044] For example, refer to Figure 2 , Figure 2 A schematic diagram of a photoacoustic probe according to one embodiment is shown in the figure. A light guide 202 extends into the tube 201 along its axial direction. A lens group 203, a reflective element 206, and an ultrasonic transducer 207 are all disposed within the tube 201 and arranged sequentially along its axial direction. The lens group 203 includes a first curved lens 204 and a second curved lens 205. The first curved lens 204 is a negative lens, and the second curved lens 205 is a positive lens. (See reference...) Figure 3 , Figure 3The figure shows a schematic diagram of light propagation in a photoacoustic probe according to one embodiment. The light beam emitted from the light guide 202 passes through the lens group 203, which converges the beam. After being reflected by the reflective element 206, the beam exits the tube 201 at a certain angle to the axis of the tube 201 and converges onto the cavity 100 under test. The size of the light spot C on the cavity 100 is much smaller than the size corresponding to the sound beam range B of the ultrasonic transducer 207, i.e., the lateral dimension of the ultrasonic transducer 207.

[0045] In some embodiments, the first curved lens 204 is a spherical lens, that is, both the first and second surfaces of the first curved lens 204 are spherical, and the second curved lens 205 is a spherical lens, that is, both the first and second surfaces of the second curved lens 205 are spherical.

[0046] In some embodiments, a gap exists between the first curved lens 204 and the second curved lens 205. The gap distance is the product of the geometrical optical path length of the gap and the refractive index of the filling medium within the gap. The geometrical optical path length of the gap is limited by the structural dimensions of the photoacoustic probe; therefore, the smaller the refractive index of the filling medium, the smaller the gap distance. Accordingly, in some embodiments, the gap can be filled with air, and the refractive index of air is close to the vacuum refractive index, i.e., close to 1. In some embodiments, a gap exists between the first curved lens 204 and the second curved lens 205, and this gap is filled with a medium whose refractive index is less than 1.33. The filling medium can be a medium with a uniform refractive index.

[0047] In some embodiments, the first curved lens 204 and the second curved lens 205 are sealed within the cylindrical body, with a gap between them filled with a medium. The first curved lens 204 and the second curved lens 205 are assembled into the cylindrical body to fix their relative positions. Adhesive can be used to bond the first curved lens 204 and the second curved lens 205 to the cylindrical body, forming a sealed gap filled with air or other media.

[0048] In some embodiments, the lens group may include a third curved lens, which is an aspherical lens. The first and second surfaces of the aspherical lens are both aspherical. An aspherical lens can focus all passing light rays onto a single point by freely designing the curvature of all points on its surface, ensuring the focused light spot is not blurred by aberrations. Lens group 203 may use a single aspherical lens.

[0049] In some implementations, the lateral magnification of the lens group 203 is greater than 2, which can ensure that the axial dimension of the photoacoustic probe is small enough and the imaging depth is large enough.

[0050] In some embodiments, the light guide 202 includes a core layer and a cladding covering the outside of the core layer. The refractive index of the core layer is greater than that of the cladding layer, allowing the light beam to propagate along the core layer. The diameter of the core layer is not less than 50 μm. Because a lens group 203 is provided on the light-emitting side of the light guide 202 to converge the light beam, a light guide 202 with a larger core diameter can be used, increasing the energy of the emitted light beam and improving the energy utilization efficiency of the light output from the light source. The light guide 202 can be made of optical fiber, specifically multimode fiber. The mode field diameter of a single-mode fiber is typically no greater than 10 μm, and its cross-sectional area is at most 1 / 25 that of a multimode fiber, resulting in a difference in the utilization efficiency of the light output from the light source of at least 25 times.

[0051] Examples can be combined with references Figure 3 If the light guide 202 uses optical fiber, assuming the fiber end face diameter is φ1, the distance from the fiber end face to the principal plane D of the lens group is L1, the diameter of the focused spot is φ2, and the distance from the focused spot to the principal plane D of the lens group is L2, ignoring lens aberrations and the refractive index effect of the liquid environment, according to the principle of constant optical spread, we have the following relationship: φ1 / L1 = φ2 / L2. For an optical fiber with a fixed end face diameter φ1, to obtain a smaller focused spot size φ2, we can increase L1 or decrease L2. This can be achieved by optimizing the position of the principal plane of the lens group, moving the principal plane of the lens group away from the fiber end face.

[0052] When the lateral magnification of lens group 203 is greater than 2, i.e., L2 / L1 > 2, it can be ensured that L1 is small enough, resulting in a short axially inflexible length of the photoacoustic probe, while L2 is large enough, allowing for a longer imaging depth. Furthermore, the first curved lens 204 in lens group 203 is a negative lens, which can amplify the beam emitted from the optical fiber, allowing it to refocus at a great distance, thus achieving L2 much larger than L1 and enabling a deeper imaging depth.

[0053] If a Green lens is placed on the light-emitting side of the light guide 202, the light beam will be focused by the Green lens. The Green lens is cylindrical, with its front and rear planes serving as light-transmitting surfaces. The refractive index gradually decreases radially along the central axis of the cylinder, and the rate of decrease gradually increases, meaning that light rays farther from the central axis are bent more severely, ultimately focusing the light beam. Compared to using a Green lens, which relies on changes in axial length and refractive index to focus the light beam, in this embodiment, the lens group 203 uses a curved lens. The curved lens focuses the light beam by refracting light through its curved surface. The main plane of the lens group can be as far away from the fiber end face as possible, thus enabling a smaller spot size of the focused emitted beam, thereby improving lateral resolution.

[0054] In some embodiments, the length direction of the ultrasonic transducer 207 is arranged along the axial direction of the tube body 201, which avoids the length direction of the ultrasonic transducer 207 being arranged along the radial direction of the tube body 201. This allows for a smaller diameter of the photoacoustic probe, and ensures that ultrasonic waves in the imaging area can still be received even with reduced installation accuracy requirements.

[0055] This embodiment also provides a photoacoustic imaging system, including:

[0056] A light source for emitting a light beam, which is then transmitted into a light guide of the photoacoustic probe;

[0057] The photoacoustic probe described in any of the above embodiments is used to emit the light beam and illuminate the target area within the imaging region, and to convert the ultrasonic waves received from the target area into electrical signals.

[0058] The host module is electrically connected to the signal line of the photoacoustic probe and is used to receive the electrical signals transmitted back by the photoacoustic probe.

[0059] The host module generates an image based on the electrical signal transmitted from the photoacoustic probe. The generated image can be output to a display. In the photoacoustic imaging system of this embodiment, the light beam emitted from the light guide in the photoacoustic probe passes through a lens group, which converges the light beam, causing the converged beam to exit from the tube and illuminate the target area. By converging the light beam through the lens group, the size of the light spot illuminating the target area is reduced, thus improving the lateral resolution.

[0060] This photoacoustic imaging system may also include a photoelectric slip ring, through which the light beam emitted from the light source is transmitted to the photoacoustic probe. The system may also include a motor control module and a motor drive module. The motor control module is connected to the main unit module, and the motor drive module is connected to both the motor control module and the photoelectric slip ring. The motor drive module drives the photoelectric slip ring to rotate, thereby driving the photoacoustic probe to rotate. The system may also include an image processing module for processing the acquired signals to generate an image.

[0061] For example, refer to Figure 4 , Figure 4 This is a schematic diagram of a photoacoustic imaging system according to one embodiment. The photoacoustic imaging system may further include: an ultrasonic transmitting module for emitting ultrasonic waves to irradiate a target area; and an ultrasonic receiving module connected to a host module for converting the ultrasonic waves from the target area into electrical signals. The host module generates an image based on the electrical signals transmitted from the ultrasonic receiving module, and the generated image can be output to a display.

[0062] The photoacoustic imaging system of this embodiment can be used for photoacoustic-ultrasound dual-modal imaging. The host module provides the control timing, and the light source emits a laser beam in the form of pulses. During the interval between two adjacent laser pulses, the ultrasonic emission module emits ultrasonic waves. The laser beam and ultrasonic waves sequentially irradiate the target area. The ultrasonic waves generated by the target area are independently received by the ultrasonic receiving module. After image processing, the image is displayed on the monitor as a fused image of the photoacoustic and ultrasonic signals, providing users with high-resolution images of the target area with a large imaging depth. The motor control module controls the motor drive module, which drives the motor to rotate, thereby rotating the photoelectric slip ring and the photoacoustic probe to complete a 360° scan of the inspected cavity to form a two-dimensional image. Combined with periodic retraction actions, a three-dimensional stereoscopic image of the inspected cavity is achieved.

[0063] The photoacoustic probe and photoacoustic imaging system provided by this utility model have been described in detail above. Specific examples have been used to illustrate the principle and implementation of this utility model. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core idea of ​​this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principle of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

Claims

1. A photoacoustic probe, characterized in that, It includes the tube body, light guide, signal line, lens group, reflective element, and ultrasonic transducer; The light guide and the signal line pass through the tube body along the axial direction of the tube body, and the signal line is electrically connected to the ultrasonic transducer. The lens group, the reflective element, and the ultrasonic transducer are all disposed within the tube and arranged sequentially along the axial direction of the tube. The lens group is disposed on the light-emitting side of the light guide and includes at least one curved lens. The light guide is used to guide the transmission of the light beam and cause the light beam to be incident on the lens group. The lens group is used to converge the light beam so that the converged light beam is incident on the reflective element. The reflective element is used to reflect the converged light beam along a direction that forms a preset angle with the axis of the tube body, so that the converged light beam passes through the tube body and is emitted to the target part in the imaging area. The ultrasonic transducer is used to convert the ultrasonic waves received from the target part into electrical signals.

2. The photoacoustic probe according to claim 1, characterized in that, The lens group includes a first curved lens and a second curved lens, wherein the focal length of one of the first curved lens and the focal length of the second curved lens is positive and the focal length of the other is negative.

3. The photoacoustic probe according to claim 2, characterized in that, The first curved lens and the second curved lens are arranged sequentially along the direction from the light guide to the reflective element, and the focal length of the first curved lens is negative and the focal length of the second curved lens is positive.

4. The photoacoustic probe according to claim 2, characterized in that, The first curved lens and the second curved lens are spaced apart and the space is filled with air.

5. The photoacoustic probe according to claim 2, characterized in that, The first curved lens and the second curved lens are sealed inside the cylinder, with a gap between them. The gap between the first curved lens and the second curved lens is filled with a medium whose refractive index is less than 1.

33.

6. The photoacoustic probe according to claim 1, characterized in that, The lens group includes a third curved lens, which is an aspherical lens.

7. The photoacoustic probe according to any one of claims 1 to 6, characterized in that, The lateral magnification of the lens group is greater than 2.

8. The photoacoustic probe according to any one of claims 1 to 6, characterized in that, The light guide includes a core layer and a cladding layer covering the outside of the core layer. The refractive index of the core layer is greater than that of the cladding layer, so that the light beam is transmitted along the core layer. The diameter of the core layer is not less than 50 μm.

9. The photoacoustic probe according to any one of claims 1 to 6, characterized in that, The length of the ultrasonic transducer is arranged along the axial direction of the tube body.

10. A photoacoustic imaging system, characterized in that, include: A light source for emitting a light beam, which is then transmitted into a light guide of the photoacoustic probe; The photoacoustic probe according to any one of claims 1 to 9 is used to emit the light beam and illuminate the target part within the imaging area, and to convert the ultrasonic waves received from the target part into electrical signals; The host module is electrically connected to the signal line of the photoacoustic probe and is used to receive the electrical signals transmitted back by the photoacoustic probe.

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