Photoacoustic and speckle combined imaging system and method

Abstract

The application discloses a photoacoustic and speckle combined imaging system and method. The system comprises a laser assembly, an optical path assembly, a signal acquisition assembly and an imaging control assembly. The transducer and the image acquisition module in the signal acquisition assembly are in the same field of view. The application has the advantages of simple structure, relatively low signal processing complexity and the capability of photoacoustic and speckle combined imaging in the same field of view.

Description

Technical Field

[0001] This invention belongs to the technical field of biological tissue imaging, specifically relating to a photoacoustic and speckle combined imaging system and method. Background Technology

[0002] Microcirculation within biological tissues is closely related to the occurrence and development of diseases in living organisms, and imaging of microcirculatory structures in living organisms without damage is of great significance.

[0003] Currently, photoacoustic imaging and speckle imaging are used for non-destructive imaging of microcirculation structures in living biological tissues.

[0004] Speckle imaging is a non-invasive in vivo laser imaging technique, highly suitable for measuring blood microcirculation. It can measure microcirculation parameters such as vessel diameter, vessel density, blood flow velocity, and blood perfusion, thereby examining the structure, function, and metabolic activity of microcirculatory vessels. However, while speckle imaging utilizes the motion of scattering particles (red blood cells) to cause fluctuations in speckle intensity on the imaging surface and thus calculates relative motion velocity information, it cannot calculate blood oxygen saturation.

[0005] Photoacoustic imaging is a novel non-invasive and non-ionizing biomedical laser imaging method. When a pulsed laser irradiates the corresponding light absorption domain of a biological tissue, it will generate a photoacoustic signal (the phenomenon of generating ultrasound by a laser beam exciting biological tissue). The photoacoustic signal carries the light absorption characteristic information of the tissue. Through the photoacoustic signal, the light absorption distribution image in the tissue can be reconstructed, and information such as blood oxygen saturation can be obtained.

[0006] In existing technologies, devices combining photoacoustic imaging and speckle imaging typically superimpose images of photoacoustic and laser speckle imaging from different fields of view. Before superimposing the fields, additional signal or data processing is required to correct the field positions, resulting in low processing efficiency and difficulty in obtaining accurate multimodal biological tissue microcirculation physiological parameters. Furthermore, in some existing combined imaging devices, the photoacoustic imaging section often uses a single tunable wavelength nanosecond pulse laser to separately illuminate the sample and provide the computer with the signal to trigger the laser speckle imaging section. The laser illuminating the sample, the received photoacoustic image, and the laser speckle portion are mechanically scanned using an optoelectronic slip ring. This introduces signal synchronization issues, increasing processing time. The components driving and controlling the mechanical movement of the optoelectronic slip ring also increase the overall complexity of the device structure, raising the difficulty of coordinating signal processing within the device. Summary of the Invention

[0007] In order to overcome the defects and deficiencies of the existing technology, the first objective of the present invention is to provide a photoacoustic and speckle combined imaging system, and the second objective is to provide a photoacoustic and speckle combined imaging method for performing high-resolution and high-contrast combined imaging of tissue samples using laser photoacoustic signals and speckle image signals. Speckle imaging can provide information on large-sized blood vessels and blood flow velocity, while photoacoustic imaging can provide information on microvascular imaging and specific absorbers.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A photoacoustic and speckle combined imaging system includes a laser assembly, an optical path assembly, a signal acquisition assembly, and an imaging control assembly;

[0010] The laser assembly includes three lasers; one of the three lasers is used to emit a laser beam that produces a speckle image, and the other two are used to emit laser beams that produce a photoacoustic image.

[0011] The optical path assembly includes two dichroic mirrors and one objective lens; one of the two dichroic mirrors is located near the two corresponding photoacoustic images of the lasers, and is used to transmit and / or reflect the laser beams emitted by the two corresponding photoacoustic images of the lasers to the other dichroic mirror; the other of the two dichroic mirrors is located near the signal acquisition component, and is used to reflect the laser beam emitted from the dichroic mirror near the two corresponding photoacoustic images of the lasers, and / or transmit the speckle beam emitted after the laser beam emitted by the laser corresponding to the speckle image of the laser irradiates the living biological tissue; the objective lens is used to focus the laser beam reflected by the other dichroic mirror and / or focus the speckle beam;

[0012] The signal acquisition component includes an image acquisition module and a transducer; the image acquisition module is used to receive the speckle beam and acquire the corresponding speckle signal; the transducer is used to receive photoacoustic signals and convert them into electrical signals;

[0013] The objective lens is positioned at the center of the transducer;

[0014] The imaging control component is electrically connected to the image acquisition module and the transducer, respectively, and is used to convert speckle signals and / or photoacoustic signals into data and construct corresponding images of the microcirculation structure of blood in living biological tissues.

[0015] One preferred embodiment of the present invention is that the transducer is a hemispherical hollow ultrasonic transducer, the top of the hemispherical hollow ultrasonic transducer is provided with an opening, and the objective lens is disposed in the opening and penetrates the inner and outer sides of the hemispherical hollow ultrasonic transducer.

[0016] One preferred embodiment of the present invention is that the imaging control component is also electrically connected to the three lasers respectively, for sending timing control signals to the three lasers respectively.

[0017] One preferred embodiment of the present invention is that the laser used to emit the corresponding speckle image is a continuous light laser;

[0018] Two lasers are used to emit corresponding photoacoustic images, one of which is a nanosecond pulse laser and the other is a tunable wavelength nanosecond pulse laser;

[0019] A dichroic mirror is placed near two corresponding photoacoustic lasers to transmit the laser beam emitted by the tunable wavelength nanosecond pulse laser and to reflect the laser beam emitted by the nanosecond pulse laser.

[0020] One preferred embodiment of the present invention is that the optical path assembly further includes two fiber collimators and one optical fiber;

[0021] Each of the two fiber collimators is placed close to a dichroic mirror;

[0022] Two fiber collimators are connected by optical fibers to propagate a laser beam from one dichroic mirror to the other.

[0023] One preferred embodiment of the present invention is that the optical path component further includes an optical amplification module;

[0024] The optical magnification module is located between the image acquisition module and the dichroic mirror near the signal acquisition component, and is used to magnify the speckle beam.

[0025] A more preferred embodiment of the present invention is that the optical magnification module is a set of lenses for magnifying the light beam;

[0026] The line connecting the extension of the central axis of the lens group and the extension of the central axis of the objective lens is on the same straight line;

[0027] The dichroic mirror near the signal acquisition component has its geometric center located on the line connecting the extension of the central axis of the lens group and the extension of the central axis of the objective lens, with its central axis forming a 45° angle with the line connecting the extension of the central axis of the lens group and the extension of the central axis of the objective lens.

[0028] One preferred embodiment of the present invention is that the incident angle and / or exit angle and / or reflection angle of the laser beam transmitted and / or refracted on the two dichroic mirrors are both 45°.

[0029] The incident and / or exit angles of the speckle beam on the dichroic mirror are both 45°.

[0030] A more preferred embodiment of the present invention is that the imaging control component includes a signal processing module, a main control module, a timing control module, and a data processing imaging module;

[0031] The signal acquisition component also includes a two-dimensional scanning module; the two-dimensional scanning module is connected to the transducer and is used to drive the transducer to perform two-dimensional displacement;

[0032] The main control module is electrically connected to the signal processing module, timing control module, data processing imaging module, and two-dimensional scanning module, respectively, and is used to send instructions to the signal processing module, timing control module, data processing imaging module, and two-dimensional scanning module, respectively.

[0033] The signal processing module is electrically connected to the image acquisition module, the two-dimensional scanning module, and the data processing imaging module, respectively, and is used to receive speckle image signals and photoacoustic image signals, process them, and convert them into corresponding data;

[0034] The data processing imaging module is used to construct images of the blood microcirculation structure of living biological tissues based on the data from the signal processing module;

[0035] The timing control module is electrically connected to the three lasers respectively to generate timing control signals, so that the three lasers emit laser beams according to the timing control signals.

[0036] A photoacoustic and speckle combined imaging method includes the following steps:

[0037] The imaging control component generates a first timing signal for a laser used to generate a speckle image signal;

[0038] According to the first timing signal, the laser used to generate speckle image signals periodically emits laser light to irradiate the biological living tissue sample within a set time period to form speckle image signals; the imaging control component issues an instruction to control the acquisition component to acquire the corresponding speckle image signals, and then the imaging control component processes the speckle image signals and converts them into speckle image data.

[0039] After the speckle image data is generated, the imaging control component stops generating the first timing signal. Then, within another set time period, the imaging control component alternately generates a second timing signal for the tunable wavelength nanosecond pulse laser used to generate the photoacoustic signal and a third timing signal for another laser used to generate the photoacoustic signal.

[0040] A tunable wavelength nanosecond pulse laser used to generate photoacoustic signals and another laser used to generate photoacoustic signals are periodically and alternately irradiated onto a living biological tissue sample through an optical path component to form a photoacoustic image signal; the imaging control component controls the signal acquisition component to acquire the photoacoustic signal, and then the imaging control component processes the photoacoustic signal and converts it into photoacoustic image data;

[0041] After acquiring photoacoustic image data and speckle image data, the imaging control component constructs an image of the blood microcirculation structure of a living biological tissue from the photoacoustic image data and speckle image data.

[0042] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0043] Photoacoustic imaging and speckle imaging share a single objective lens through two dichroic mirrors. The optical paths of speckle imaging and photoacoustic imaging are coaxial when received, which can ensure the consistency of the imaging field of view and realize the function of joint imaging. This avoids the position verification step required by existing technologies when the field of view is superimposed, reduces the time consumed by the signal processing module and the data processing imaging module in signal and data processing, improves the imaging efficiency, and acquires information on large-sized blood vessels and blood flow velocity and high-resolution information on microvessels and specific absorbers under the same field of view.

[0044] The structure of setting the objective lens in the center of the transducer enables the photoacoustic signal and speckle image signal to be in the same field of view, avoiding the drawback of existing technologies that require photoelectric slip rings to separate the laser and speckle image signals of the photoacoustic signal. This simplifies the number of optical components and the complexity of the structure, and increases the reliability and ease of maintenance of the entire system.

[0045] After the two fiber collimators are connected by optical fiber, the diameter of the laser beam emitted from the dichroic mirror can be adjusted, which facilitates the laser of the photoacoustic signal to be focused by the objective lens and improves the accuracy of the photoacoustic signal.

[0046] Tunable wavelength lasers combined with fixed wavelength lasers for photoacoustic imaging can acquire blood oxygen saturation information and can further enable molecular probe imaging with specific optical absorption.

[0047] By using timing control signals, imaging operations are performed in an orderly manner, reducing the data synchronization requirements of the signal processing process and improving processing efficiency. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the structural framework of one embodiment of the photoacoustic and speckle combined imaging system of the present invention;

[0049] Figure 2 This is a schematic diagram of the structural framework of another embodiment of the photoacoustic and speckle combined imaging system of the present invention;

[0050] Figure 3 This is a flowchart of one embodiment of the photoacoustic and speckle combined imaging method of the present invention;

[0051] In the diagram: 1-First sample, 2-First laser, 3-Second laser, 4-Third laser, 5-First transducer, 6-First objective lens, 7-First dichroic mirror, 8-Second dichroic mirror, 9-First optical magnification module, 10-First image acquisition module, 11-First two-dimensional scanning module, 12-First signal processing module, 13-First main control module, 14-First timing control module, 15-First data processing and imaging module, 16-Second sample, 17-Fourth laser Optical device, 18-Fifth laser, 19-Sixth laser, 20-Second transducer, 21-Second objective lens, 22-Third dichroic mirror, 23-Fourth dichroic mirror, 24-Second optical magnification module, 25-Second image acquisition module, 26-Second two-dimensional scanning module, 27-Second signal processing module, 28-Second main control module, 29-Second timing control module, 30-Second data processing imaging module, 31-First fiber optic collimator, 32-Second fiber optic collimator. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0053] It should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this disclosure.

[0054] Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Similarly, words such as "a," "one," or "the" do not indicate a quantity limitation but rather that at least one exists. Words such as "including" or "contains" mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, without excluding other elements or objects. Words such as "connected" or "linked" are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect.

[0055] Example 1

[0056] like Figure 1 As shown, in Figure 1The propagation path and process of light are represented by line segments with arrows. The photoacoustic and speckle combined imaging system provided in this embodiment 1 uses three lasers to image the photoacoustic signal and speckle image signal of the laser on the first sample 1. The first sample 1 is the tissue of a living biological organism, such as the tip of a human finger or toe, or the skin tissue covering a human joint.

[0057] The photoacoustic and speckle combined imaging system provided in Embodiment 1 includes a laser assembly, an optical path assembly, a signal acquisition assembly, and an imaging control assembly. The laser assembly includes a first laser 2, a second laser 3, and a third laser 4. The optical path assembly includes a first objective lens 6, a first dichroic mirror 7, a second dichroic mirror 8, and a first optical magnification module 9. The signal acquisition assembly includes a first transducer 5, a first image acquisition module 10, and a first two-dimensional scanning module 11. The imaging control assembly includes a first signal processing module 12, a first main control module 13, a first timing control module 14, and a first data processing imaging module 15.

[0058] In this embodiment, the relative positions of the first laser 2, the second laser 3, the first dichroic mirror 7, the second dichroic mirror 8, the first optical magnification module 9, the first objective lens 6, the first transducer 5, and the first image acquisition module 10 are preferably kept unchanged. In other embodiments, only the relative positions of the first laser 2, the second laser 3, the first dichroic mirror 7, the second dichroic mirror 8, the first objective lens 6, and the first transducer 5 may be kept unchanged.

[0059] In the laser assembly, the first laser 2 is a nanosecond pulse laser, and for the purpose of generating photoacoustic images, the wavelength of its emitted laser beam is preferably selected between 500 and 550 nanometers in this embodiment; the second laser 3 is a tunable wavelength nanosecond pulse laser, and for the purpose of generating photoacoustic images, the tunable wavelength range of its emitted laser beam is preferably between 400 and 1500 nanometers in this embodiment; the third laser 4 is a continuous light laser, and for the purpose of generating speckle images, the wavelength of its emitted laser beam is preferably selected between 750 and 800 nanometers in this embodiment; the first laser 2, the second laser 3, and the third laser 4 are all electrically connected to the first timing control module 14 via signal lines, and each receives timing control signals issued by the first timing control module 14, and each performs controlled emission of laser beams according to the corresponding timing control signals; the first laser 2 and the second laser 3 are used to emit laser beams corresponding to photoacoustic signals, and the third laser 4 is used to emit laser beams corresponding to speckle image signals; the first laser 2 and the third laser 4 are both fixed wavelength lasers.

[0060] In the optical path assembly, a first dichroic mirror 7 is positioned close to the first laser 2 and the second laser 3. The central axis of the first dichroic mirror 7 forms a 45° angle with the extended central axes of the first laser 2 and the second laser 3, respectively. One side of the first dichroic mirror 7 closest to the first laser 2 is used for the incident laser beam emitted by the first laser 2, while the opposite side furthest from the first laser 2 is used for the incident laser beam emitted by the second laser 3, the exit laser beam emitted by the first laser 2, and the exit laser beam emitted by the second laser 3. The laser beam is reflected; the laser beam emitted by the first laser 2, after exiting the first dichroic mirror 7, and the laser beam emitted by the second laser 3, after being reflected by the first dichroic mirror 7, both enter the second dichroic mirror 8; the second dichroic mirror 8 is located near the first objective lens 6 and the first transducer 5; the central axis of the second dichroic mirror 8 forms a 45° angle with the extension of the central axis of the first objective lens 6; one side of the second dichroic mirror 8 near the first objective lens 6 is used to reflect the laser beam incident from the first dichroic mirror 7 into the first objective lens 6. The laser beam incident from the first sample 1 is a speckled beam; the second dichroic mirror 8, located on the opposite side away from the first objective lens 6, is used to output the speckled beam to the first optical magnification module 9; the first objective lens 6 is positioned at the center of the first transducer 5, with its top end close to the second dichroic mirror 8 and its bottom end close to the first sample 1. The laser beam reflected by the second dichroic mirror 8 passes through the first objective lens 6 from top to bottom and irradiates the first sample 1. The laser speckled beam emitted from the first sample 1 passes through the first objective lens 6 from bottom to top and is focused to irradiate the first optical magnification module 9. Block 9; The first optical magnification module 9 is a lens group with optical magnification function, used to receive laser speckle and propagate it to the first image acquisition module 10. The central axis extension line of the first optical magnification module 9 forms a 45° angle with the central axis of the second dichroic mirror 8. The line connecting the central axis extension line of the first optical magnification module 9 and the central axis extension line of the first objective lens 6 is on the same straight line. The geometric center point of the second dichroic mirror 8 is located on the line connecting the central axis extension line of the first optical magnification module 9 and the central axis extension line of the first objective lens 6.

[0061] The dichroic mirror near the signal acquisition component has its center point located on the line connecting the extended central axis of the lens group and the extended central axis of the objective lens, with its axis forming a 45° angle with the line connecting the extended central axis of the lens group and the extended central axis of the objective lens.

[0062] Preferably, in this embodiment, the laser beam emitted from the first laser 2, upon reaching one side of the first dichroic mirror 7, forms an incident angle of 45° with the first dichroic mirror 7, and after passing through the first dichroic mirror 7, forms an exit angle of 45° with the opposite side of the first dichroic mirror 7. Preferably, in this embodiment, the laser beam emitted from the second laser 3, upon reaching the opposite side of the first dichroic mirror 7, forms an incident angle of 45° with the first dichroic mirror 7, and after reflection, forms an exit angle of 45° with the opposite side of the first dichroic mirror 7. Preferably, in this embodiment, on the side of the second dichroic mirror 8 near the first objective lens 6, the incident angle of the incident laser beam, the reflection angle of the reflected laser beam, and the incident angle of the incident speckle beam are all 45°. On the side of the second dichroic mirror 8 opposite the first objective lens 6, the exit angle of the outgoing speckle beam is 45°.

[0063] In the signal acquisition component, the first image acquisition module 10 is used to receive the speckle beam propagated from the first optical amplification module 9. The first image acquisition module 10 is electrically connected to the first signal processing module 12 via a signal line, thereby transmitting the electrical signal corresponding to the speckle beam to the first signal processing module 12. In this embodiment, the first image acquisition module 10 is preferably an image signal acquisition device composed of an area array image sensor (CMOS camera or CCD camera) and a multi-channel analog signal acquisition circuit. The first transducer 5 is electrically connected to the first signal processing module 12. The first transducer 5 is used to receive the photoacoustic signal generated by the first sample 1 (i.e., the ultrasonic wave generated after the first sample 1 is irradiated by laser) and convert it into an electrical signal before sending it to the first signal processing module 12. In this embodiment, the first transducer 5 is preferably a hemispherical hollow ultrasonic transducer with an opening at the top. The first objective lens 6 is located at the top opening of the hemispherical transducer. The hole penetrates the inner and outer sides of the hemispherical hollow ultrasonic transducer, and the first sample 1 is placed directly below the inner side of the hemispherical hollow ultrasonic transducer. The first two-dimensional scanning module 11 is mechanically connected to the first transducer 5. In this embodiment, the first two-dimensional scanning module 11 is preferably a piezoelectric displacement stage. The first two-dimensional scanning module 11 drives the first transducer 5 to perform two-dimensional displacement mechanical scanning on the first sample 1 according to the instructions of the first main control module 13. After receiving the photoacoustic signal, the first transducer 5 transmits it to the first signal processing module 12. According to the positional arrangement of the two dichroic mirrors, one objective lens and one transducer in this embodiment, it can be seen that the field of view of speckle imaging is the same as that of photoacoustic imaging, and the reception of photoacoustic signal and speckle image signal will be coaxial. The first signal processing module 12 is electrically connected to the first main control module 13 through a signal line and is used to receive photoacoustic signal and speckle image signal according to the corresponding instructions of the first main control module 13.

[0064] In the imaging control assembly, the first signal processing module 12 is also electrically connected to the first image acquisition module 10, and is used to receive photoacoustic signals and speckle image signals, and convert them into corresponding data formats that can be processed by a computer after signal processing. The signal processing performed by the first signal processing module 12 includes one or more of detection, filtering, transformation, modulation, and noise reduction. The first data processing imaging module 15 is electrically connected to the first signal processing module 12 through a data line or digital electronic circuit, and is used to reconstruct the microcirculation structure image of the biological tissue blood of the first sample 1 from the corresponding photoacoustic signal data and speckle image signal data converted by the first signal processing module 12. The first main control module 13 is connected to the first timing control module through a data line or digital electronic circuit. Block 14, the first signal processing module 12, the first data processing imaging module 15, and the first two-dimensional scanning module 11 are electrically connected and used to control the operation of the first timing control module 14, the first signal processing module 12, the first data processing imaging module 15, and the first two-dimensional scanning module 11 respectively. The first timing control module 14 is used to generate multiple timing control signals according to the instructions of the first main control module 13, and control the laser beam emission process of the first laser 2, the second laser 3, and the third laser 4 respectively, so that the laser beam emission of the first laser 2, the second laser 3, and the third laser 4 corresponds to the signal acquisition and reception of the first signal processing module 12, thereby enabling the first data processing imaging module 15 to synchronize relevant data in an orderly manner.

[0065] In a further preferred embodiment, the first laser 2, the second laser 3, the first dichroic mirror 7, the second dichroic mirror 8, the first optical magnification module 9, the first objective lens 6, the first transducer 5, and the first image acquisition module 10 maintain their relative positions through mechanical connections with one or more rigid components, so that the reception of photoacoustic signals and speckle signals can always remain coaxial when the first two-dimensional scanning module 11 drives the first transducer 5 to move.

[0066] In a further preferred embodiment, the imaging control components are integrated into a personal computer, and the first signal processing module 12, the first data processing imaging module 15, the first timing control module 14, and the first main control module 13 are all implemented through the combination of relevant hardware and software within the personal computer.

[0067] The photoacoustic and speckle combined imaging system of this embodiment 1 operates as follows: The first main control module 13 sends an instruction to the first timing control module 14, issuing a timing control signal to control the third laser 4 to emit light independently for a certain period of time. Simultaneously, the first main control module 13 controls the first signal processing module 12 to receive the speckle image signal. Before the third laser 4 emits light independently, or after the first signal processing module 12 has received the speckle image signal, the first main control module 13 issues an instruction to the first timing control module 14 to generate a timing control signal that controls the first laser 2 and the tunable wavelength second laser 3 to emit light alternately. The first main control module 13 simultaneously controls the first two-dimensional scanning module 11 to drive the first transducer 5 to perform mechanical two-dimensional scanning and acquire photoacoustic signals, and the first signal processing module 12 receives the photoacoustic signals; after completing the reception of one photoacoustic signal and speckle image signal, the first signal processing module 12 converts the received signals to obtain corresponding photoacoustic imaging data and speckle imaging data; the first data processing imaging module 15 reconstructs the biological tissue blood microcirculation structure image of the first sample 1 based on the photoacoustic imaging data and speckle imaging data of the first signal processing module 12.

[0068] Compared with the prior art, the advantages of this embodiment 1 are as follows:

[0069] Photoacoustic imaging and speckle imaging share the first objective lens 6 through the second dichroic mirror 8. The optical paths of speckle imaging and photoacoustic imaging are coaxial when they are received, which can ensure the consistency of the field of view of the imaging and realize the function of joint imaging. This avoids the position verification step required by the existing technology when the field of view is superimposed, reduces the time consumed by the first signal processing module 12 and the first data processing imaging module 15 in signal and data processing, improves the imaging efficiency, and obtains information on large-sized blood vessels and blood flow velocity and high-resolution microvessels and specific absorbers under the same field of view.

[0070] The structure of the first objective lens 6 being positioned at the center of the first transducer 5 enables the photoacoustic signal and speckle image signal to be in the same field of view, avoiding the drawbacks of existing technologies that require photoelectric slip rings to separate the laser and speckle image signals of the photoacoustic signal. This simplifies the number of optical components and the complexity of the structure, and increases the reliability and ease of maintenance of the entire system.

[0071] The second laser 3 and the first laser 2 perform photoacoustic imaging, which can obtain blood oxygen saturation information and further realize molecular probe imaging with specific optical absorption.

[0072] Example 2

[0073] like Figure 2 As shown, in Figure 2The propagation path and process of light are represented by line segments with arrows. The photoacoustic and speckle combined imaging system provided in this Embodiment 2 uses three lasers to image the photoacoustic signal and the speckle image signal of the second sample 16. The second sample 16 is the tissue of a biological living body, such as the fingertip of a human, etc.

[0074] The photoacoustic and speckle combined imaging system provided in this Embodiment 2 includes a laser component, an optical path component, a signal acquisition component, and an imaging control component. The laser component includes a fourth laser 17, a fifth laser 18, and a sixth laser 19. The optical path component includes a second objective lens 21, a third dichroic mirror 22, a fourth dichroic mirror 23, a second optical amplification module 24, a first fiber collimator 31, and a second fiber collimator 32. The signal acquisition component includes a second transducer 20, a second image acquisition module 25, and a second two-dimensional scanning module 26. The imaging control component includes a second signal processing module 27, a second main control module 28, a second timing control module 29, and a second data processing and imaging module 30.

[0075] In this Embodiment, it is preferred that the relative positions among the fourth laser 17, the fifth laser 18, the third dichroic mirror 22, the fourth dichroic mirror 23, the second optical amplification module 24, the second objective lens 21, the second transducer 20, and the second image acquisition module 25 remain unchanged.

[0076] In the laser component, the fourth laser 17 is a nanosecond pulsed laser, and in this Embodiment, it is preferred that the wavelength of the emitted laser beam is 532 nanometers; the fifth laser 18 is a tunable wavelength nanosecond pulsed laser, and in this Embodiment, it is preferred that the tunable wavelength range of the emitted laser beam is between 400 and 1500 nanometers; the sixth laser 19 is a continuous wave laser, and in this Embodiment, it is preferred that the wavelength of the emitted laser beam is 785 nanometers; the fourth laser 17, the fifth laser 18, and the sixth laser 19 are respectively electrically connected to the second timing control module 29 through signal lines, each receives the timing control signal issued by the second timing control module 29, and each performs controlled emission of the laser beam according to the corresponding timing control signal; the fourth laser 17 and the fifth laser 18 are used to emit laser beams corresponding to the photoacoustic signal, and the sixth laser 19 is used to emit a laser beam corresponding to the speckle image signal; the fourth laser 17 and the sixth laser 19 are both lasers with fixed wavelengths.

[0077] In the optical path assembly, the third dichroic mirror 22 is positioned near the fourth laser 17 and the fifth laser 18. The central axis of the third dichroic mirror 22 forms a 45° angle with the extended central axes of the fourth laser 17 and the fifth laser 18, respectively. One side of the third dichroic mirror 22 near the fourth laser 17 is used for the incident laser beam emitted by the fourth laser 17, and the opposite side away from the fourth laser 17 is used for the incident laser beam emitted by the fifth laser 18, the exit laser beam emitted by the fourth laser 17, and the reflection laser beam emitted by the fifth laser 18. The laser beam emitted by the fourth laser 17 exits through the third dichroic mirror 22, and the laser beam emitted by the fifth laser 18 is reflected. The laser beam emitted by laser 18, after being reflected by the third dichroic mirror 22, is perpendicularly incident into the first fiber collimator 31. The first fiber collimator 31 and the second fiber collimator 32 are connected by an optical fiber, within which the laser beam emitted from the third dichroic mirror 22 propagates. After adjusting the incident laser beam, the first fiber collimator 31 propagates the laser beam into the optical fiber, and then the laser beam exits perpendicularly from the second fiber collimator 32. The laser beam exiting perpendicularly from the second fiber collimator 32 propagates to the fourth dichroic mirror 23. The fourth dichroic mirror 23 is positioned close to the second objective lens 21 and the second transducer 20. The central axis of the fourth dichroic mirror 23... The fourth dichroic mirror 23 forms a 45° angle with the extension of the central axis of the second objective lens 21; one side of the fourth dichroic mirror 23 is close to the second objective lens 21 and is used to reflect the laser beam incident from the second fiber collimator 32 into the second objective lens 21, and to incident the speckle beam propagating from the second sample 16; the opposite side of the fourth dichroic mirror 23 away from the second objective lens 21 is used to exit the speckle beam to the second optical magnification module 24; the second objective lens 21 is located at the center of the second transducer 20, with its top end close to the fourth dichroic mirror 23 and its bottom end close to the second sample 16. The laser beam reflected by the fourth dichroic mirror 23 passes through the second objective lens 21 from top to bottom and irradiates the second sample 16. The laser speckle emitted from the two samples 16 passes through the second objective lens 21 from bottom to top and is focused onto the second optical magnification module 24. The second optical magnification module 24 is a lens group with optical magnification function, used to receive the laser speckle and propagate it to the second image acquisition module 25. The extension of the central axis of the second optical magnification module 24 forms a 45° angle with the central axis of the fourth dichroic mirror 23. The line connecting the extension of the central axis of the second optical magnification module 24 and the extension of the central axis of the second objective lens 21 is on the same straight line. The geometric center point of the fourth dichroic mirror 23 is located on the line connecting the extension of the central axis of the second optical magnification module 24 and the extension of the central axis of the second objective lens 21.

[0078] Preferably, in this embodiment, the laser beam emitted from the fourth laser 17, upon reaching one side of the third dichroic mirror 22, forms an incident angle of 45° with the third dichroic mirror 22. After passing through the third dichroic mirror 22, it forms an exit angle of 45° with the opposite side of the third dichroic mirror 22. Preferably, in this embodiment, the laser beam emitted from the fifth laser 18, upon reaching the opposite side of the third dichroic mirror 22, forms an incident angle of 45° with the third dichroic mirror 22. After reflection, it forms an exit angle of 45° with the opposite side of the third dichroic mirror 22. Preferably, in this embodiment, on the side of the fourth dichroic mirror 23 near the second objective lens 21, the incident angle of the incident laser beam, the reflection angle of the reflected laser beam, and the incident angle of the incident speckle beam are all 45°. On the side of the fourth dichroic mirror 23 opposite to the second objective lens 21, the exit angle of the outgoing speckle beam is 45°.

[0079] In the signal acquisition assembly, the second image acquisition module 25 is used to receive the speckle beam propagated from the second optical amplification module 24. The second image acquisition module 25 is electrically connected to the second signal processing module 27 via a signal line, thereby transmitting the electrical signal corresponding to the speckle beam to the second signal processing module 27. In this embodiment, the second image acquisition module 25 is preferably an image signal acquisition device composed of an area array image sensor (CMOS camera or CCD camera) and a multi-channel analog signal acquisition circuit. The second transducer 20 is electrically connected to the second signal processing module 27. The system connects to receive the photoacoustic signal generated by the second sample 16. In this embodiment, the second transducer 20 is preferably a hemispherical hollow ultrasonic transducer with an opening at its top. The second objective lens 21 is located at the top opening of the hemispherical shape and penetrates both the inner and outer sides of the hemispherical shape. The inner side of the hemispherical hollow ultrasonic transducer is directly below where the second sample 16 is placed. The second two-dimensional scanning module 26 is mechanically connected to the second transducer 20. In this embodiment, the second two-dimensional scanning module 26 is preferably a piezoelectric displacement scanning stage. The photoacoustic signal received by the second transducer 20 is converted into an electrical signal. Simultaneously, the second transducer 20, driven by the piezoelectric displacement scanning stage, performs a two-dimensional displacement scan of the second sample 16. Based on the positional arrangement of the two dichroic mirrors, one objective lens, and one transducer in this embodiment, it can be seen that the field of view for speckle imaging is the same as that for photoacoustic imaging, and the reception of the photoacoustic signal and the speckle image signal will be coaxial. The second two-dimensional scanning module 26 is electrically connected to the second main control module 28 via a signal line or data line. The second signal processing module 27 is electrically connected to the second main control module 28 via a signal line, and is used to process data according to the second main control module 28. The corresponding instructions receive photoacoustic signals and speckle image signals; when the second two-dimensional scanning module 26 moves the second transducer 20 to a position on the second sample 16, the second transducer 20 collects photoacoustic signals at that position. Since the distance between the second sample 16 and the second transducer 20 is known and fixed, the optical absorption information of the second sample 16 in the depth direction can be calculated based on the time it takes for the photoacoustic signal to reach the second transducer 20, and the optical absorption information in the depth direction of each point on the two-dimensional plane can be obtained, thereby obtaining the three-dimensional optical absorption information of the sample.

[0080] In the imaging control assembly, the second signal processing module 27 is also electrically connected to the second image acquisition module 25. It receives photoacoustic signals and speckle image signals, processes them, and converts them into corresponding data formats suitable for computer processing. The signal processing performed by the second signal processing module 27 includes one or more of detection, filtering, transformation, modulation, and noise reduction. The second data processing imaging module 30 is electrically connected to the second signal processing module 27 via a data line or digital electronic circuitry. It constructs an image of the biological tissue blood microcirculation structure corresponding to the second sample 16 from the corresponding photoacoustic signal data and speckle image signal data converted by the second signal processing module 27. The second main control module 28 is connected to the second timing control module 25 via a data line and / or digital electronic circuitry. 9. The second signal processing module 27, the second data processing imaging module 30, and the second two-dimensional scanning module 26 are electrically connected and are used to control the operation of the second timing control module 29, the second signal processing module 27, the second data processing imaging module 30, and the second two-dimensional scanning module 26 respectively. The second timing control module 29 is used to generate multiple timing control signals according to the instructions of the second main control module 28, and to control the laser beam emission process of the fourth laser 17, the fifth laser 18, and the sixth laser 19 respectively, so that the laser beam emission of the fourth laser 17, the fifth laser 18, and the sixth laser 19 corresponds to the signal acquisition and reception of the second signal processing module 27, thereby enabling the second data processing imaging module 30 to synchronize relevant data in an orderly manner.

[0081] In a further preferred embodiment, the fourth laser 17, the fifth laser 18, the third dichroic mirror 22, the fourth dichroic mirror 23, the second optical magnification module 24, the second objective lens 21, the second transducer 20, and the second image acquisition module 25 maintain their relative positions through mechanical connections with one or more rigid components, or they are all fixedly connected inside the same housing to maintain their relative positions. This ensures that the photoacoustic signal and speckle signal reception remain coaxial when the second two-dimensional scanning module 26 moves the second transducer 20. Alternatively, the second two-dimensional scanning module 26 can directly drive these rigid components or the housing to move the second transducer 20 in two dimensions and maintain the coaxial reception of the photoacoustic signal and speckle signal.

[0082] In a further preferred embodiment, the imaging control components are integrated into a personal computer, and the second signal processing module 27, the second data processing imaging module 30, the second timing control module 29, and the second main control module 28 are all implemented through the combination of relevant hardware and software within the personal computer.

[0083] The photoacoustic and speckle combined imaging system of this embodiment 2 operates as follows: The second main control module 28 sends an instruction to the second timing control module 29, issuing a timing control signal to control the sixth laser 19 to emit light independently for a certain period of time. Simultaneously, the second main control module 28 controls the second signal processing module 27 to receive the speckle image signal. Before the sixth laser 19 emits light independently, or after the second signal processing module 27 has received the speckle image signal, the second main control module 28 sends an instruction to the second timing control module 29 to generate control over the alternating operation of the fourth laser 17 and the tunable wavelength fifth laser 18. The timing control signal for light emission is used to simultaneously control the second two-dimensional scanning module 26 to drive the second transducer 20 to collect photoacoustic signals and the second signal processing module 27 to receive photoacoustic signals. After completing the reception of one photoacoustic signal and speckle image signal, the second signal processing module 27 converts the received signals to obtain corresponding photoacoustic imaging data and speckle imaging data. The second data processing imaging module 30 constructs an image of the biological tissue blood microcirculation structure of the second sample 16 based on the photoacoustic imaging data and speckle imaging data of the second signal processing module 27.

[0084] Compared with the prior art, the advantages of this embodiment 2 are as follows:

[0085] Photoacoustic imaging and speckle imaging share the second objective lens 21 through the fourth dichroic mirror 23. The optical paths of speckle imaging and photoacoustic imaging are coaxial when they are received, which can ensure the consistency of the field of view of the imaging and realize the function of joint imaging. This avoids the position verification step required by the existing technology when the field of view is superimposed, reduces the time consumed by the second signal processing module 27 and the second data processing imaging module 30 in signal and data processing, improves the imaging efficiency, and obtains information on large-sized blood vessels and blood flow velocity and high-resolution microvessels and specific absorbers under the same field of view.

[0086] The structure of the second objective lens 21 positioned at the center of the second transducer 20 enables the photoacoustic signal and speckle image signal to be in the same field of view. This avoids the drawback of existing technologies that require photoelectric slip rings to separate the laser and speckle image signals of the photoacoustic signal. It simplifies the number of optical components and the complexity of the structure, and increases the reliability and ease of maintenance of the entire system.

[0087] After the first fiber collimator 31 and the second fiber collimator 32 are connected by optical fiber, the diameter of the laser beam emitted from the third dichroic mirror 22 can be adjusted, which makes it easier for the laser of the photoacoustic signal to be focused by the second objective lens 21 and improves the accuracy of the photoacoustic signal.

[0088] The fifth laser 18 and the fourth laser 17 with tunable wavelengths can perform photoacoustic imaging to obtain blood oxygen saturation information, and can also be further combined with the second objective lens 21 and the second transducer 20 to make a molecular probe.

[0089] Example 3

[0090] Combination Figure 3 As shown. The photoacoustic and speckle combined imaging method provided in this embodiment can be executed based on the system of Embodiment 1 or Embodiment 2. The photoacoustic and speckle combined imaging method of this embodiment includes the following steps:

[0091] S1. The main control module in the imaging control component issues a command to control the signal processing module in the imaging control component to enter the working state and wait to receive speckle image signals and photoacoustic signals.

[0092] S2. The main control module sends an instruction to the timing control module in the imaging control component, and the timing control module generates a first timing signal for a laser used to generate speckle image signals.

[0093] S3. Speckle Imaging Stage: The laser used to generate the speckle image signal periodically emits laser light to irradiate the living biological tissue sample within a set time period according to the first timing signal, forming a speckle image signal. The rising edge of the high-level interval of the first timing signal is used as the trigger signal for laser emission. After the timing control module generates the first timing signal, the main control module issues instructions to control the image acquisition module in the signal acquisition component to acquire the corresponding speckle image signal, and to control the signal processing module to process the speckle image signal and convert it into speckle image data. The emission period and the proportion of the high-level interval in the emission period can be set according to requirements.

[0094] S4. After the speckle image data is formed, the main control module sends an instruction to the timing control module to stop generating the first timing signal. Then, the timing control module alternately generates the second timing signal for the tunable wavelength nanosecond pulse laser used to generate the photoacoustic signal and the third timing signal for another laser used to generate the photoacoustic signal within another set time period.

[0095] S5. Photoacoustic Imaging Stage: A tunable wavelength nanosecond pulse laser used to generate photoacoustic signals and another laser used to generate photoacoustic signals are periodically and alternately emitted through an optical path component to irradiate the living biological tissue sample, forming a photoacoustic image signal. The laser corresponding to the third timing signal emits light first, with the rising edge of the high-level interval serving as the trigger signal. After the high-level interval of the first cycle of the third timing signal generated by the timing control module ends, i.e., after the photoacoustic signal generated by irradiating the living biological tissue sample first reaches the transducer, the main control module issues a command to control the two-dimensional scanning module to drive the transducer to perform two-dimensional displacement scanning of the photoacoustic signal received by the living biological tissue sample. The control signal processing module processes the photoacoustic signal and converts it into photoacoustic image data. The alternating light emission period and the proportion of the high-level interval in the alternating light emission period can be set according to requirements.

[0096] S6. After obtaining photoacoustic image data and speckle image data, the main control module issues instructions to control the data processing imaging module in the imaging control component. Based on the characteristic that the speckle signal and photoacoustic signal are in the same field of view, the module constructs an image of the blood microcirculation structure of biological living tissue from the photoacoustic image data and speckle image data.

[0097] Compared with the prior art, the advantages of this embodiment 3 are as follows:

[0098] Photoacoustic imaging and speckle imaging, being coaxial during reception, ensure consistent field of view, enabling joint imaging. This avoids the position verification steps required by existing technologies when overlaying fields of view, reducing the time spent on signal and data processing in the signal processing and imaging modules, thus improving imaging efficiency. It acquires information on large-sized blood vessels and blood flow velocity, as well as high-resolution information on microvessels and specific absorbers within the same field of view, while simultaneously acquiring blood oxygen saturation information. By using timing control signals, imaging operations are performed in an orderly manner, reducing the data synchronization requirements of the signal processing process and improving processing efficiency.

[0099] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A photoacoustic and speckle combined imaging system, characterized in that, This includes laser components, optical path components, signal acquisition components, and imaging control components; The laser assembly includes three lasers; one of the three lasers is used to emit a laser beam that generates a speckle image, and the other two are used to emit laser beams that generate a photoacoustic image. The optical path assembly includes two dichroic mirrors and one objective lens; one of the two dichroic mirrors is located near the two lasers corresponding to the photoacoustic images, and is used to transmit and / or reflect the laser beams emitted by the lasers corresponding to the photoacoustic images to the other dichroic mirror; the other of the two dichroic mirrors is located near the signal acquisition component, and is used to reflect the laser beam emitted from the dichroic mirror near the lasers corresponding to the photoacoustic images, and / or transmit the speckle beam emitted after the laser beam emitted by the laser corresponding to the speckle image irradiates the living biological tissue; the objective lens is used to focus the laser beam reflected by the other dichroic mirror and / or focus the speckle beam; The optical path assembly also includes two fiber collimators and one optical fiber; Each of the two fiber collimators is positioned close to a dichroic mirror; Two fiber collimators are connected via the fiber and are used to propagate a laser beam from one of the dichroic mirrors to the other. The optical path components also include an optical amplification module; The optical magnification module is located between the image acquisition module and the dichroic mirror near the signal acquisition component, and is used to magnify the speckle beam. The optical magnification module is a set of lenses used to magnify the light beam; The line connecting the extension of the central axis of the lens group and the extension of the central axis of the objective lens is on the same straight line; The dichroic mirror near the signal acquisition component has its geometric center point located on the line connecting the extension of the central axis of the lens group and the extension of the central axis of the objective lens, wherein the axis forms a 45° angle with the line connecting the extension of the central axis of the lens group and the extension of the central axis of the objective lens. The incident angle and / or exit angle and / or reflection angle of the laser beam transmitted and / or refracted on the two dichroic mirrors are both 45°. The incident angle and / or exit angle of the speckle beam on the dichroic mirror are both 45°. The signal acquisition component includes an image acquisition module and a transducer; the image acquisition module is used to receive the speckle beam and acquire the corresponding speckle signal; the transducer is used to receive photoacoustic signals and convert them into electrical signals; the signal acquisition component also includes a two-dimensional scanning module; the two-dimensional scanning module is connected to the transducer and is used to drive the transducer to perform two-dimensional displacement; The objective lens is located in the center of the transducer. Specifically, the transducer is a hemispherical hollow ultrasonic transducer. The top of the hemispherical hollow ultrasonic transducer has an opening. The objective lens is located in the opening and penetrates the inner and outer sides of the hemispherical hollow ultrasonic transducer. The imaging control component is electrically connected to the image acquisition module and the transducer, respectively, and is used to convert speckle signals and / or photoacoustic signals into data and construct corresponding images of the microcirculation structure of blood in living biological tissues.

2. The photoacoustic and speckle combined imaging system according to claim 1, characterized in that, The imaging control component is also electrically connected to each of the three lasers to send timing control signals to each of the three lasers.

3. The photoacoustic and speckle combined imaging system according to claim 1, characterized in that, The laser used to emit the corresponding speckle pattern is a continuous light laser; Two lasers are used to emit corresponding photoacoustic images, one of which is a nanosecond pulse laser and the other is a tunable wavelength nanosecond pulse laser; A dichroic mirror is placed near two corresponding photoacoustic lasers to transmit the laser beam emitted by the tunable wavelength nanosecond pulse laser and to reflect the laser beam emitted by the nanosecond pulse laser.

4. The photoacoustic and speckle combined imaging system according to any one of claims 1-3, characterized in that, The imaging control component includes a signal processing module, a main control module, a timing control module, and a data processing imaging module; The main control module is electrically connected to the signal processing module, timing control module, data processing imaging module, and two-dimensional scanning module, respectively, and is used to send instructions to the signal processing module, timing control module, data processing imaging module, and two-dimensional scanning module, respectively. The signal processing module is electrically connected to the image acquisition module, the two-dimensional scanning module, and the data processing imaging module, respectively, and is used to receive speckle image signals and photoacoustic image signals, process them, and convert them into corresponding data; The data processing imaging module is used to construct images of the blood microcirculation structure of living biological tissues based on the data from the signal processing module. The timing control module is electrically connected to the three lasers respectively, and is used to generate timing control signals so that the three lasers emit laser beams according to the timing control signals.

5. A photoacoustic and speckle combined imaging method, characterized in that, The photoacoustic and speckle combined imaging system according to any one of claims 1-4 includes the following steps: The imaging control component generates a first timing signal for a laser used to generate a speckle image signal; According to the first timing signal, the laser used to generate speckle image signals periodically emits laser light to irradiate the biological living tissue sample within a set time period to form speckle image signals; the imaging control component issues an instruction to control the acquisition component to acquire the corresponding speckle image signals, and then the imaging control component processes the speckle image signals and converts them into speckle image data. After the speckle image data is generated, the imaging control component stops generating the first timing signal. Then, within another set time period, the imaging control component alternately generates a second timing signal for the tunable wavelength nanosecond pulse laser used to generate the photoacoustic signal and a third timing signal for another laser used to generate the photoacoustic signal. A tunable wavelength nanosecond pulse laser used to generate photoacoustic signals and another laser used to generate photoacoustic signals are periodically and alternately irradiated onto a living biological tissue sample through an optical path component to form a photoacoustic image signal; the imaging control component controls the signal acquisition component to acquire the photoacoustic signal, and then the imaging control component processes the photoacoustic signal and converts it into photoacoustic image data; After acquiring photoacoustic image data and speckle image data, the imaging control component constructs an image of the blood microcirculation structure of a living biological tissue from the photoacoustic image data and speckle image data.

Images