Bessel photoacoustic microscopy based on surface plasmon sensing

Abstract

The present invention relates to a Bessel photoacoustic microscope based on surface plasmon sensing, wherein the excitation light of the ring-shaped Bessel-type beam generated by the excitation light generating component is irradiated on the sample to generate ultrasonic pressure waves, which change the refractive index of the plasma water film in the surface plasmon sensor, causing the intensity of the polarized light incident on the surface plasmon sensor to change, and the differential detection component receives the reflected polarized light with changed intensity, and eliminates the common mode noise by subtracting two optical input signals, thereby obtaining the detection information of the sample. The present invention utilizes the resonance effect of the surface plasmon sensor and the characteristics of the Bessel-type beam to improve the longitudinal resolution to the same micron level as the lateral resolution, while ensuring that the lateral resolution for detecting different depths of the sample remains unchanged, thereby improving the quality of the three-dimensional image, and the obtained three-dimensional image has isotropic, micron-level spatial resolution in the three-dimensional space.

Description

Technical Field

[0001] The invention relates to the technical field of photoacoustic microscopes, and in particular to a Bessel photoacoustic microscope based on surface plasmon sensing. Background Art

[0002] Photoacoustic microscopy can specifically measure the optical absorption characteristics of biological tissues, and has shown great application prospects in the fields of life sciences and clinical medicine. At present, there are two problems in most photoacoustic microscopy technologies and systems. First, piezoelectric ultrasonic transducers are generally used to detect photoacoustic signals. However, due to the limitations of the physical properties of piezoelectric materials themselves, the detection bandwidth of such transducers is limited, often in tens of megahertz, resulting in the longitudinal resolution of photoacoustic imaging being often limited to tens of microns, which is far worse than its micron-level lateral resolution, seriously affecting the reconstruction of three-dimensional photoacoustic images and causing inaccurate depth positioning of samples. Secondly, traditional photoacoustic microscopy systems use focused Gaussian beams to excite the signals of optical absorbers. However, the focal depth of the focused Gaussian beam is limited, and it can only maintain nearly equal lateral resolution within a shorter range (generally no more than 100 microns), resulting in significant differences in lateral resolution over the entire imaging depth (about 1 mm). Therefore, the existing photoacoustic microscopes have low spatial positioning accuracy for detecting samples, resulting in distortion of the observed three-dimensional images. Summary of the invention

[0003] The embodiment of the present application provides a Bessel photoacoustic microscope based on surface plasmon sensing, which aims to solve the problem of low spatial positioning accuracy of sample detection in the photoacoustic microscope in the prior art, resulting in distortion of the observed three-dimensional image.

[0004] The present invention is achieved through the following technical solutions:

[0005] A Bessel photoacoustic microscope based on surface plasmon sensing, comprising: a polarized light generating component, a surface plasmon sensor, an excitation light generating component and a differential detection component;

[0006] The polarized light generating component is used to generate polarized light and input the polarized light into the surface plasmon sensor;

[0007] The excitation light generating component is used to generate excitation light and illuminate the sample to generate ultrasonic pressure waves; wherein the excitation light is an annular Bessel-type light beam;

[0008] The surface plasmon sensor is used to receive the polarized light, and to use the reflected light beam that changes due to the influence of the ultrasonic pressure wave when the polarized light is reflected by the surface plasmon sensor as the reflected polarized light;

[0009] The differential detection component is used to receive the reflected polarized light and output detection information of the sample according to the reflected polarized light.

[0010] The Bessel photoacoustic microscope based on surface plasmon sensing, wherein the surface plasmon sensor includes a coated prism and a deionized water film arranged below the coated prism, and the sample is placed below the deionized water film.

[0011] In the Bessel photoacoustic microscope based on surface plasmon sensing, a reflective coating is provided on the bottom surface of the coated prism, the deionized water film contacts the reflective coating, and the reflective coating is used to reflect the polarized light to form the reflected polarized light.

[0012] In the Bessel photoacoustic microscope based on surface plasmon sensing, the reflective coating is a metal coating.

[0013] In the Bessel photoacoustic microscope based on surface plasmon sensing, the coated prism is a right-angle prism or a trapezoidal prism.

[0014] The Bessel photoacoustic microscope based on surface plasmon sensing, wherein the polarized light generating component includes a helium-neon laser generator, a polarizer and a half-wave plate;

[0015] The helium-neon laser generator is used to generate detection laser;

[0016] The polarizer is disposed between the helium-neon laser generator and the half-wave plate, and is used to modulate the detection laser to obtain a modulated detection laser;

[0017] The half wave plate is arranged between the polarizer and the surface plasmon sensor, and is used to adjust the P-polarization and S-polarization components of the modulated detection laser so as to use the adjusted modulated detection laser as the polarized light.

[0018] The Bessel photoacoustic microscope based on surface plasmon sensing, wherein the excitation light generating component comprises: a solid laser generator, an axicon, a first focusing lens, a first beam expanding lens and a second beam expanding lens;

[0019] The solid-state laser generator is used to generate pulsed excitation light;

[0020] The axicon is disposed between the solid-state laser generator and the first focusing lens, and is used to modulate the pulse excitation light to generate a Bessel-type beam and input the beam into the first focusing lens;

[0021] The first focusing lens is disposed between the axicon and the first beam expander lens, and the first focusing lens is used to focus the Bessel-type beam and then input the beam into the first beam expander lens;

[0022] The first beam expanding lens is arranged between the first focusing lens and the second beam expanding lens, and the second beam expanding lens is arranged between the first beam expanding lens and the sample. The first beam expanding lens and the second beam expanding lens are combined to expand the focused Bessel-type light beam to obtain the annular Bessel-type light beam.

[0023] The Bessel photoacoustic microscope based on surface plasmon sensing, wherein the excitation light generating component further includes an annular mask;

[0024] The annular mask is disposed between the first beam expanding lens and the second beam expanding lens, and is used to filter the Bessel-type beam output by the first beam expanding lens so as to input the filtered Bessel-type beam into the second beam expanding lens.

[0025] The Bessel photoacoustic microscope based on surface plasmon sensing, wherein the differential detection component includes a polarization beam splitter, a balanced amplification photodetector, a high-frequency amplifier and an imaging device;

[0026] The polarization beam splitter is arranged between the surface plasmon sensor and the balanced amplified photodetector, and is used to perform polarization beam splitting on the reflected polarized light to obtain a first polarized light and a second polarized light. The first input end of the balanced amplified photodetector receives the first polarized light, and the second input end receives the second polarized light. The polarization directions of the first polarized light and the second polarized light are perpendicular to each other.

[0027] The balanced amplified photodetector is disposed between the polarization beam splitter and the high-frequency amplifier, and is used to perform optical signal subtraction on the first polarized light and the second polarized light, thereby obtaining a signal containing ultrasonic pressure wave information of the sample, and outputting the signal obtained after the optical signal subtraction to the high-frequency amplifier;

[0028] The high-frequency amplifier is connected to the balanced amplification photodetector and the imaging device respectively. The high-frequency amplifier is used to amplify the acquired signal and output the amplified signal to the imaging device to display the detection information of the sample.

[0029] The Bessel photoacoustic microscope based on surface plasmon sensing, wherein, further comprises a first side reflector;

[0030] The first side reflector is disposed between the excitation light generating component and the surface plasmon sensor, and is used for adjusting the incident angle of the polarized light incident on the surface plasmon sensor.

[0031] Beneficial Effects

[0032] Compared with the existing technology, the present invention has the following outstanding advantages and effects: an excitation light generating component is used to generate an annular Bessel-type light beam to irradiate the sample to generate an ultrasonic pressure wave, the ultrasonic pressure wave changes the refractive index of the plasma water film in the surface plasmon sensor, resulting in a change in the intensity of the polarized light incident on the surface plasmon sensor, the differential detection component receives the reflected polarized light with changed intensity, and the common mode noise is eliminated by subtracting the optical input signals of two different polarization components, thereby obtaining a signal containing the ultrasonic pressure wave information of the sample as the detection information of the sample, and has the characteristic of a wide detection bandwidth, which solves the problem that the longitudinal resolution and the lateral resolution of the traditional photoacoustic microscope are not at the same level, and can be used to clearly image the microcirculation structure of capillaries and even red blood cells. At the same time, the present invention combines the resonance effect of the surface plasmon sensor and the characteristics of the Bessel-type light beam, and ensures that the lateral resolution for detecting different depths of the sample remains unchanged on the basis of improving the longitudinal resolution to the same micron level as the lateral resolution, thereby improving the quality of the three-dimensional image obtained by photoacoustic imaging. The obtained three-dimensional image has an isotropic, micron-level spatial resolution capability in the three-dimensional space, which greatly improves the positioning accuracy for detecting different depths of the sample. The obtained three-dimensional image has an isotropic, micron-level spatial resolution capability in the three-dimensional space, which solves the problem of low spatial positioning accuracy for detecting samples existing in traditional photoacoustic microscopes. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The overall structure diagram of the Bessel photoacoustic microscope based on surface plasmon sensing of the present invention;

[0034] Figure 2 A partial structural diagram of the Bessel photoacoustic microscope based on surface plasmon sensing of the present invention;

[0035] Figure 3 A partial structural diagram of the Bessel photoacoustic microscope based on surface plasmon sensing of the present invention;

[0036] Figure 4 A partial structural diagram of the Bessel photoacoustic microscope based on surface plasmon sensing of the present invention;

[0037] Figure 5 It is a schematic structural diagram of the Bessel photoacoustic microscope based on surface plasmon sensing of the present invention;

[0038] Figure 6It is a schematic diagram of the local structure of the Bessel photoacoustic microscope based on surface plasmon sensing of the present invention. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0041] The following descriptions of the embodiments are made with reference to the attached drawings to illustrate specific embodiments of the present invention that can be implemented. The directional terms mentioned in the present invention, such as "upper", "lower", "front", "back", "left", "right", "inner", "outer", "side", etc., are only with reference to the directions of the attached drawings. Therefore, the directional terms used are used to illustrate and understand the present invention, but are not used to limit the present invention.

[0042] The present invention provides a Bessel photoacoustic microscope based on surface plasmon sensing. To make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0043] See also Figure 1-Figure 6 , Figure 1 The overall structure diagram of the Bessel photoacoustic microscope based on surface plasmon sensing of the present invention; Figure 2 A partial structural diagram of the Bessel photoacoustic microscope based on surface plasmon sensing of the present invention; Figure 3 A partial structural diagram of the Bessel photoacoustic microscope based on surface plasmon sensing of the present invention; Figure 4 A partial structural diagram of the Bessel photoacoustic microscope based on surface plasmon sensing of the present invention; Figure 5 It is a schematic structural diagram of the Bessel photoacoustic microscope based on surface plasmon sensing of the present invention; Figure 6The schematic diagram of the partial structure of the Bessel photoacoustic microscope based on surface plasmon sensing of the present invention is shown in the figure. As shown in the figure, the embodiment of the present invention provides a Bessel photoacoustic microscope based on surface plasmon sensing, which includes: a polarized light generating component 1, a surface plasmon sensor 2, an excitation light generating component 3 and a differential detection component 4; the polarized light generating component 1 is used to generate polarized light and input the polarized light into the surface plasmon sensor 2; the excitation light generating component 3 is used to generate excitation light and irradiate the sample 10 to generate ultrasonic pressure waves; wherein the excitation light is an annular Bessel-type beam; the surface plasmon sensor 2 is used to receive the polarized light, and when the polarized light is reflected by the surface plasmon sensor 2, the reflected light beam that changes due to the influence of the ultrasonic pressure wave is used as the reflected polarized light; the differential detection component 4 is used to receive the reflected polarized light and output the detection information of the sample according to the reflected polarized light. The Bessel beam is a non-diffracting beam, which means that it does not diffract or diverge when propagating; a true Bessel beam cannot be generated in nature because the Bessel beam is unbounded and requires an infinite amount of energy, but a Bessel-type beam that approximates the Bessel beam can be obtained through the axicon 32. The conventional photoacoustic microscope uses a Gaussian beam as the excitation light, and the Gaussian beam can be focused at the contact point with the surface of the sample 10. However, the focal depth of the focused Gaussian beam is limited, and generally can only maintain nearly equal lateral resolution at the order of hundreds of microns, while the depth of the sample 10 is usually not less than 1 mm, which is much larger than the focal depth of the focused Gaussian beam, resulting in a low lateral resolution for detecting different depths of the sample 10, resulting in a significant difference in lateral resolution over the entire imaging depth of the sample, and finally the acquired three-dimensional photoacoustic image is severely distorted. Using an annular Bessel-type light beam as the excitation light can ensure that after the excitation light irradiates the sample 10, the excitation light will not diverge in the entire imaging depth of the sample 10, that is, the lateral resolution of the excitation light for detecting the entire imaging depth of the sample 10 will not change, thereby greatly improving the sensitivity of detecting different depths of the sample, thereby accurately revealing the microscopic morphological and structural characteristics of the tissue at the cellular level, providing new and reliable technical support for biomedical research.

[0044] The polarized light used may be linear polarized light, circular polarized light or elliptically polarized light. The excitation light generating component 3 generates excitation light to illuminate the sample 10, and the excitation light is a circular Bessel-type beam. The sample 10 absorbs the excitation light and generates an ultrasonic pressure wave corresponding to the optical absorption characteristics of the sample 10 based on the thermoelastic effect. The regions with different densities and structures in the sample 10 have different optical absorption characteristics, so different ultrasonic pressure waves will be generated. Based on the difference in ultrasonic pressure waves, the density, structure and other information of the sample can be deeply detected. The sample 10 may be living animal tissues such as blood vessels, skin, and internal organs, and may also be biological materials such as cells and plant tissues. The above-mentioned Bessel photoacoustic microscope may also include an electric displacement platform 5, on which the sample 10 may be placed, and the electric platform drives the sample 10 to move along the X-axis, Y-axis and Z-axis directions to perform all-round dynamic detection of the sample 10.

[0045] In a more specific embodiment, the surface plasmon sensor 2 includes a coated prism 21 and a deionized water film 22 disposed below the coated prism 21, and the sample 10 is placed below the deionized water film 22. Specifically, a reflective coating 211 is provided on the bottom surface of the coated prism 21, and the deionized water film 22 contacts the reflective coating 211, and the reflective coating 211 is used to reflect the polarized light to form the reflected polarized light. Specifically, the reflective coating 211 is a metal coating, wherein the coated prism 21 is a right-angle prism or a trapezoidal prism. The deionized water film 22 is composed of deionized water, so the deionized water film 22 does not contain any impurities, which can prevent the impurities from affecting the detection results and improve the detection accuracy of the sample 10. The bottom surface of the coated prism 21 is provided with a reflective coating 211. When polarized light is incident on the coated prism 21, the angle between the incident direction of the polarized light and the direction of the plumb line is the incident angle A of the polarized light. The metal used in the reflective coating 211 and the incident angle A must correspond to the wavelength of the polarized light. The incident angle A must be greater than the total reflection angle of the reflective coating 211 to allow the polarized light to be totally reflected on the surface of the reflective coating 211 to obtain reflected polarized light. The thickness of the reflective coating 211 is not less than the preset thickness to avoid the situation where part of the polarized light is not reflected. More specifically, metal coatings such as gold coating, silver coating, tin coating, and lead coating can be selected as the reflective coating 211. Other coatings with reflective effects can also be selected as the reflective coating 211. The incident angle A can be 60-80°, and the preset thickness can be 30nm.

[0046] In the transmission mode photoacoustic imaging system, the polarized light needs to enter from one side of the sample and pass through the sample and exit from the other side of the sample. Therefore, the conventional transmission mode photoacoustic imaging system can only image in vitro cell samples. In the reflection mode photoacoustic microscope designed by using the surface plasmon sensor 2, the polarized light, the excitation light and the reflected polarized light are all located on the same side of the sample 10 to produce effects (in this embodiment, the polarized light, the excitation light and the reflected polarized light are all located on the same side of the sample 10 to produce effects). Figure 6 The polarized light and the excitation light shown in the figure are both incident from the upper side of the sample 10, and the reflected polarized light is emitted from the upper side of the sample 10), so the human brain, eyes and other internal organs can be imaged. It has good universality and can solve the problem that the traditional photoacoustic imaging system using the transmission mode can only image in vitro cell samples but cannot image the human brain, eyes and other internal organs.

[0047] For example, when the wavelength of polarized light is 633nm, the power of polarized light is 10mw, a gold coating is used as the reflective coating 211 on the bottom surface of the coated prism 21, the thickness of the gold coating is 45nm, and the incident angle A is selected to be 72.5°. The polarized light is incident on the gold coating of the coated prism 21 from one side of the coated prism 21, excites the surface plasma and causes total reflection, and produces a plasma resonance effect that is very sensitive to the change in refractive index. At this time, the ultrasonic pressure wave propagates to the surface of the gold coating through the deionized water film 22, and the aqueous solution near the gold coating is compressed or stretched by the ultrasonic pressure wave, causing the refractive index of the deionized water film 22 to change and further causing the electromagnetic field of the surface plasma to change, so that the polarized light reflected by the surface plasma has a slight intensity change, and the polarized light with intensity change is emitted from the coated prism 21 as reflected polarized light.

[0048] Traditional photoacoustic microscopes are all made of piezoelectric ultrasonic transducers, which convert the received ultrasonic signals into electrical signals for output. Due to the constraints of the piezoelectric material's own properties, the detection bandwidth of the piezoelectric transducer is narrow, usually 50-60MHz, and the detection sensitivity is also relatively low (noise equivalent sound pressure: about 1kPa). Based on the above example, the plasma resonance effect, which is extremely sensitive to the refractive index, can be used to produce a Bessel photoacoustic microscope that is superior to the existing technology. The above Bessel photoacoustic microscope can increase the detection bandwidth to more than 200MHz and the detection sensitivity to 0.1kPa (noise equivalent sound pressure, the smaller the value, the higher the detection sensitivity), which is superior to the traditional photoacoustic microscope using piezoelectric ultrasonic transducers in both detection bandwidth and detection sensitivity.

[0049] In a more specific embodiment, the polarized light generating component 1 includes a helium-neon laser generator 11, a polarizer 12 and a half-wave plate 13; the helium-neon laser generator 11 is used to generate a detection laser; the polarizer 12 is arranged between the helium-neon laser generator 11 and the half-wave plate 13, and the polarizer 12 is used to modulate the detection laser to obtain a modulated detection laser; the half-wave plate 13 is arranged between the polarizer 12 and the surface plasmon sensor 2, and the half-wave plate 13 is used to adjust the P-polarization and S-polarization components of the modulated detection laser to use the adjusted modulated detection laser as the polarized light. The polarizer 12 is used to modulate the polarization direction of the detection laser to obtain a modulated detection laser, and the half wave plate 13 is used to adjust the P-polarization and S-polarization components of the modulated detection laser to obtain polarized light, wherein when the light penetrates the surface of an optical element (such as a polarizer or a beam splitter) at a non-vertical angle, the reflection and transmission characteristics are dependent on the polarization phenomenon. In this case, the coordinate system used is defined by the plane containing the input and reflected light beams, the P-polarization component is the portion of the light polarization vector passing through this plane, and the S-polarization component is the portion of the light polarization vector perpendicular to this plane.

[0050] In a more specific embodiment, the excitation light generating component 3 includes: a solid laser generator 31, an axicon 32, a first focusing lens 33, a first beam expanding lens 34 and a second beam expanding lens 35; the solid laser generator 31 is used to generate pulsed excitation light; the axicon 32 is arranged between the solid laser generator 31 and the first focusing lens 33, and the axicon 32 is used to focus the pulsed excitation light to generate a Bessel-type beam and input it into the first focusing lens 33; the first focusing lens 33 is arranged between the axicon 32 and the first beam expanding lens 34, and the first focusing lens 33 is used to focus the Bessel-type beam and then input it into the first beam expanding lens 34; the first beam expanding lens 34 is arranged between the first focusing lens 33 and the second beam expanding lens 35, and the second beam expanding lens 35 is arranged between the first beam expanding lens 34 and the sample 10, and the first beam expanding lens 34 and the second beam expanding lens 35 are combined to expand the focused Bessel-type beam to obtain the annular Bessel-type beam. Preferably, the excitation light generating component 3 further includes an annular mask 36; the annular mask 36 is disposed between the first beam expanding lens 34 and the second beam expanding lens 35, and the annular mask 36 is used to filter the Bessel-type light beam output by the first beam expanding lens 34, so as to input the filtered Bessel-type light beam into the second beam expanding lens 35. Wherein, the solid laser generator 31 is used to generate short pulse excitation light, and for different samples 10, the wavelength of the pulse excitation light and the bottom cone angle B of the axicon can be appropriately adjusted so that the sample 10 can absorb the pulse excitation light more efficiently and generate a stronger signal containing ultrasonic pressure wave information. For example, a pulse excitation light with a wavelength of 532nm can be used to detect a blood vessel sample 10, and an axicon 32 with a bottom cone angle B of 0.5° can be used.

[0051] Preferably, the photoacoustic microscope further includes a first side reflector 37; the first side reflector 37 is disposed between the excitation light generating component 3 and the surface plasmon sensor 2, and is used to adjust the incident angle of the polarized light incident on the surface plasmon sensor 2. The first side reflector is provided to facilitate adjustment of the incident angle A of the polarized light incident on the surface plasmon sensor 2, so that the polarized light enters the surface plasmon sensor 2 at a suitable incident angle A and undergoes total reflection. More specifically, a second side reflector 38 corresponding to the first side reflector 37 may also be provided, the second side reflector 38 being disposed between the excitation light generating component 3 and the differential detection component 4, the second side reflector 38 and the first side reflector 37 being mirror images of each other, and the second side reflector 38 being used to adjust the direction of the reflected polarized light after it is emitted from the plasmon sensor 2, so that the reflected polarized light enters the differential detection component 4 in the correct direction.

[0052] In a more specific embodiment, the differential detection component 4 includes a polarization beam splitter 41, a balanced amplified photodetector 42, a high-frequency amplifier 43 and an imaging device 44; the polarization beam splitter 41 is arranged between the surface plasmon sensor 2 and the balanced amplified photodetector 42, and the polarization beam splitter 41 is used to polarize the reflected polarized light to obtain a first polarized light and a second polarized light, and the first input end 421 of the balanced amplified photodetector 42 receives the first polarized light, and the second input end 422 receives the second polarized light, and the polarization directions of the first polarized light and the second polarized light are perpendicular to each other; the balanced amplified photodetector The detector 42 is arranged between the polarization beam splitter 41 and the high-frequency amplifier 43. The balanced amplified photodetector 42 is used to perform optical signal subtraction on the first polarized light and the second polarized light, so as to obtain a signal containing the ultrasonic pressure wave information of the sample, and output the signal obtained after the optical signal subtraction to the high-frequency amplifier 43; the high-frequency amplifier 43 is respectively connected to the balanced amplified photodetector 42 and the imaging device 44, and the high-frequency amplifier 43 is used to amplify the obtained signal, and output the amplified signal to the imaging device 44 to display the detection information of the sample 10. Among them, the polarization beam splitter 41 can be a polarization beam splitter prism (Polarization Beam Spliter, PBS), and can also be a Wollaston prism. Among them, the high-frequency amplifier 43 and the balanced amplified photodetector 42 and the imaging device 44 are all connected by optical fiber. The imaging device 44 can be a terminal device with imaging function such as a desktop computer, a laptop computer, a tablet computer or a mobile phone. The detected signal is transmitted by optical fiber, which can reduce the loss in signal transmission, avoid the disturbance of the signal caused by changes in the external environment, and improve the stability of the signal. Specifically, the balanced amplified photodetector 42 receives the first polarized light and the second polarized light, and based on the measured light intensity of the first polarized light and the light intensity of the second polarized light, eliminates the common mode noise by subtracting the two optical input signals, that is, obtains a signal containing the ultrasonic pressure wave information of the sample, that is, obtains the detection information of the sample 10, amplifies the signal and outputs it to the imaging device 44, so that the detection information of the sample 10 can be displayed.

[0053] The Bessel photoacoustic microscope based on surface plasmon sensing disclosed by the present invention adopts an excitation light generating component to generate an annular Bessel-type light beam to irradiate a sample to generate an ultrasonic pressure wave. The ultrasonic pressure wave changes the refractive index of a plasma water film in the surface plasmon sensor, causing the intensity of the polarized light incident on the surface plasmon sensor to change. The differential detection component receives the reflected polarized light with the changed intensity, eliminates the common mode noise by subtracting the optical input signals of two different polarization components, and then obtains a signal containing the ultrasonic pressure wave information of the sample as the detection information of the sample. The microscope has the characteristic of a wide detection bandwidth, solves the problem that the longitudinal resolution and the lateral resolution of the traditional photoacoustic microscope are not at the same level, and can be used to clearly image the microcirculation structure of capillaries and even red blood cells. At the same time, the present invention combines the resonance effect of the surface plasmon sensor and the characteristics of the Bessel-type beam, and ensures that the lateral resolution of the different depths of the sample is detected unchanged on the basis of increasing the longitudinal resolution to the same micron level as the lateral resolution, thereby improving the quality of the three-dimensional image obtained by photoacoustic imaging, and the obtained three-dimensional image has an isotropic, micron-level spatial resolution capability in the three-dimensional space, which greatly improves the positioning accuracy of the different depths of the sample. The obtained three-dimensional image has an isotropic, micron-level spatial resolution capability in the three-dimensional space, and solves the problem of low spatial positioning accuracy of the sample detection existing in the traditional photoacoustic microscope. Therefore, the above-mentioned reflective Bessel photoacoustic microscope can accurately reveal the microscopic morphological and structural characteristics of the tissue from the cellular level, providing a new and reliable technical support for biomedical research.

[0054] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A Bessel photoacoustic microscope based on surface plasmon sensing, characterized in that: include: Polarized light generating component, surface plasmon sensor, excitation light generating component and differential detection component; The polarized light generating component is used to generate polarized light and input the polarized light into the surface plasmon sensor; The excitation light generating component is used to generate excitation light and illuminate the sample to generate ultrasonic pressure waves; wherein the excitation light is an annular Bessel-type light beam; The surface plasmon sensor is used to receive the polarized light, and to use the reflected light beam that changes due to the influence of the ultrasonic pressure wave when the polarized light is reflected by the surface plasmon sensor as the reflected polarized light; The differential detection component is used to receive the reflected polarized light and output detection information of the sample according to the reflected polarized light; The surface plasmon sensor includes a coated prism and a deionized water film arranged below the coated prism, and the sample is placed below the deionized water film; the Bessel photoacoustic microscope also includes an electric displacement platform; the sample is placed on the electric displacement platform, and the electric displacement platform drives the sample to move along the X-axis, Y-axis and Z-axis directions; A reflective coating is provided on the bottom surface of the coated prism, the deionized water film contacts the reflective coating, and the reflective coating is used to reflect the polarized light to form the reflected polarized light; The polarized light generating assembly includes a helium-neon laser generator, a polarizer and a half-wave plate; The helium-neon laser generator is used to generate detection laser; The polarizer is disposed between the helium-neon laser generator and the half-wave plate, and is used to modulate the detection laser to obtain a modulated detection laser; The half wave plate is disposed between the polarizer and the surface plasmon sensor, and is used to adjust the P-polarization and S-polarization components of the modulated detection laser so as to use the adjusted modulated detection laser as the polarized light; The differential detection assembly includes a polarization beam splitter, a balanced amplification photodetector, a high-frequency amplifier and an imaging device; The polarization beam splitter is arranged between the surface plasmon sensor and the balanced amplified photodetector, and is used to perform polarization beam splitting on the reflected polarized light to obtain a first polarized light and a second polarized light. The first input end of the balanced amplified photodetector receives the first polarized light, and the second input end receives the second polarized light. The polarization directions of the first polarized light and the second polarized light are perpendicular to each other. The balanced amplified photodetector is disposed between the polarization beam splitter and the high-frequency amplifier, and is used to perform optical signal subtraction on the first polarized light and the second polarized light, thereby obtaining a signal containing ultrasonic pressure wave information of the sample, and outputting the signal obtained after the optical signal subtraction to the high-frequency amplifier; The high-frequency amplifier is connected to the balanced amplification photodetector and the imaging device respectively. The high-frequency amplifier is used to amplify the acquired signal and output the amplified signal to the imaging device to display the detection information of the sample.

2. The Bessel photoacoustic microscope based on surface plasmon sensing according to claim 1, characterized in that: The reflective coating is a metal coating.

3. The Bessel photoacoustic microscope based on surface plasmon sensing according to claim 1 or 2, characterized in that: The coated prism is a right-angle prism or a trapezoidal prism.

4. The Bessel photoacoustic microscope based on surface plasmon sensing according to claim 1 or 2, characterized in that: The excitation light generating assembly comprises: a solid laser generator, an axicon, a first focusing lens, a first beam expanding lens and a second beam expanding lens; The solid-state laser generator is used to generate pulsed excitation light; The axicon is disposed between the solid-state laser generator and the first focusing lens, and is used to modulate the pulse excitation light to generate a Bessel-type beam and input the beam into the first focusing lens; The first focusing lens is disposed between the axicon and the first beam expander lens, and the first focusing lens is used to focus the Bessel-type beam and then input the beam into the first beam expander lens; The first beam expanding lens is arranged between the first focusing lens and the second beam expanding lens, and the second beam expanding lens is arranged between the first beam expanding lens and the sample. The first beam expanding lens and the second beam expanding lens are combined to expand the focused Bessel-type light beam to obtain the annular Bessel-type light beam.

5. The Bessel photoacoustic microscope based on surface plasmon sensing according to claim 4, characterized in that: The excitation light generating component further includes an annular mask; The annular mask is disposed between the first beam expanding lens and the second beam expanding lens, and is used to filter the Bessel-type beam output by the first beam expanding lens so as to input the filtered Bessel-type beam into the second beam expanding lens.

6. The Bessel photoacoustic microscope based on surface plasmon sensing according to claim 1 or 2, characterized in that: Also includes a first side reflector; The first side reflector is disposed between the excitation light generating component and the surface plasmon sensor, and is used for adjusting the incident angle of the polarized light incident on the surface plasmon sensor.

Images