Photoacoustic spectrum signal detection system and detection method

Abstract

The application discloses a photoacoustic spectrum signal detection system and a detection method. The system comprises a signal acquisition device and a detection signal processing terminal. The signal acquisition device comprises an ultraviolet pulse laser, a first plano-convex lens, a second plano-convex lens, a focusing objective lens, a refractive prism, a helium-neon laser, an electric displacement platform, a polarization modulation assembly, a light splitting assembly and a differential detector. The photoacoustic spectrum signal detection system uses the specific absorption of cell nuclei to ultraviolet light, obtains a differential detection signal through the differential detector and generates an analysis spectrum. The light sensing assembly collects a light sensing signal of the sample and generates a microscopic image. The detection system can realize photoacoustic spectrum analysis of a cell nucleus level micro-sized absorber, thereby obtaining a high-resolution analysis spectrum and a microscopic image reflecting the physical properties inside the cell nuclei. The label-free and non-staining photoacoustic spectrum signal detection does not need staining and can save detection time, and the accuracy of cell detection on biological samples is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical microscopic imaging, and in particular to a photoacoustic spectrum signal detection system and a detection method. BACKGROUND

[0002] Photoacoustic microscopic imaging is a hybrid imaging technique that uses acoustics to detect optical contrast through photoacoustic effect. Photoacoustic imaging can provide structural, functional, molecular and kinetic information using endogenous contrast agents (such as hemoglobin, lipids, melanin and water) or various exogenous contrast agents, and achieves micrometer or even sub-micrometer lateral resolution, showing great potential in the field of biomedical imaging. The photoacoustic signal can not only be used for visualization of the structure of the absorbing body, but the acoustic spectrum of the photoacoustic signal also contains physical information of the absorbing body. Photoacoustic spectrum mechanism is photoacoustic effect, which converts time-domain photoacoustic wave into frequency-domain photoacoustic spectrum through Fourier transform. The center frequency and bandwidth of the photoacoustic spectrum of the optical absorber (such as cell nucleus) in biological tissue are closely related to the characteristics of the absorber. The morphology, size, density, sound speed and elasticity of the optical absorber will all cause differences in the photoacoustic spectrum characteristics.

[0003] In the study of photoacoustic spectrum of micro-absorbers, the bandwidth of the detection device in photoacoustic imaging technology becomes a crucial indicator for photoacoustic spectrum analysis. In pathological analysis, cell nucleus is the main research object, and its diameter is generally several micrometers. The traditional piezoelectric ultrasonic transducer widely used in photoacoustic signal detection is limited by its own physical properties, and the detection bandwidth is narrow (generally only several tens of megahertz), which is difficult to meet the requirements of photoacoustic spectrum analysis of micro-optical absorbers. In view of the above problems, we established a photoacoustic microscopic imaging system with large bandwidth detection capability. The system uses a phase-type total internal reflection (TIR) sensor as a photoacoustic wave detector, and realizes wideband and high-sensitivity detection of photoacoustic wave by analyzing the change of refractive index of the coupling medium caused by photoacoustic signal.

[0004] The general process of photoacoustic imaging is as follows: narrow-band pulsed laser radiation on the biological tissue, the absorber or chromophore inside the biological tissue absorbs the narrow-band pulsed light energy to excite photoacoustic waves, and the photoacoustic waves are detected on the surface of the biological tissue using an ultrasonic detector. The photoacoustic signal can not only be used for the visualization structure of the absorber, but also the acoustic spectrum contains the physical information of the absorber. The time-domain photoacoustic wave is converted into the frequency-domain photoacoustic spectrum by Fourier transform. The center frequency and bandwidth of the photoacoustic spectrum of the optical absorber in the biological tissue (such as the cell nucleus) are closely related to the characteristics of the absorber. The morphology, size, density, sound speed, and elasticity of the optical absorber will cause differences in the characteristics of the photoacoustic spectrum. The smaller the size of the absorber, the greater the bandwidth of the corresponding photoacoustic spectrum, and the more high-frequency information. Therefore, in the study of the photoacoustic spectrum of micro-absorbers, the bandwidth of the detection device in the photoacoustic imaging technology becomes an important indicator for photoacoustic spectrum analysis. In the process of pathological analysis, the cell nucleus is the main research object, and the diameter is generally several microns. Therefore, the large bandwidth response capability of the optical surface wave sensing system has great advantages in the pathological analysis of the photoacoustic spectrum of the cell nucleus. In the process of cell division and proliferation, the nucleic acid metabolism is more vigorous, and a large amount of The high-density transferrin receptor content of cancer cells is higher than that of normal cells, and the size of the cell nucleus is also different from that of normal cells. Adenoma is a precancerous state of colorectal adenocarcinoma. The normal colorectal mucosa becomes adenoma due to atypical hyperplasia, and eventually develops into adenocarcinoma, which is a continuous development process. Adenoma is divided into low-grade intraepithelial neoplasia and high-grade intraepithelial neoplasia according to the degree of atypical hyperplasia of the glandular epithelium, and high-grade intraepithelial neoplasia is only one step away from adenocarcinoma (if high-grade intraepithelial neoplasia occurs early cancer, it is colorectal adenocarcinoma). Therefore, in the clinical histopathological diagnosis, it is necessary to distinguish whether the high-grade intraepithelial neoplasia of adenoma has early canceration, in order to solve the problem of early diagnosis of colorectal adenocarcinoma. The cell morphological characteristics of high-grade intraepithelial neoplasia with / without early canceration are highly similar, and it is difficult to judge only by the morphological changes of H&E stained sections under an optical microscope, and often needs to be further assisted by immunohistochemical (IHC) staining method for auxiliary diagnosis. Before cell carcinogenesis, the cell nucleus has normal morphology and size, but DNA begins to replicate faster, nucleic acid metabolism is more vigorous than normal cells, and high-density transferrin receptor content increases, so the density and sound speed of the precancerous cell nucleus are greater than those of normal cells. These changes in the mechanical properties of the cells are difficult to visualize by photoacoustic imaging, but they are important factors that cause differences in photoacoustic spectrum. Based on the high-frequency information detection capability of the optical surface wave sensing system, the photoacoustic microscopic imaging system based on optical surface wave sensing can distinguish the photoacoustic spectrum differences of normal and cancerous cell nuclei, as well as cell nuclei at different stages of disease, which has important practical significance for accurate pathological diagnosis of cancerous tissues.

[0005] Photoacoustic spectroscopy is most common in the study of red blood cells, so many scholars have done theory and experiment on red blood cells. The quantitative detection of abnormal particles in a random particle mixture has important biomedical significance. For example, microthrombosis or aggregated red blood cells mixed in red blood cells are a major determinant of hemodynamics, including blood viscosity, blood microcirculation, etc. High aggregation can affect normal physiological function and is related to diabetes, thrombosis, rheumatoid arthritis, etc. Therefore, quantitative evaluation of these abnormal particles from normal red blood cells is of great significance for the evaluation of certain pathophysiological states. The existing technical method is limited by the detection capability of the detector, and the current research on photoacoustic spectroscopy is only used to obtain the photoacoustic spectroscopy signal of cancer tissue. The detection accuracy of the photoacoustic spectroscopy signal of biological tissue is limited, so it is difficult to accurately determine whether cancer occurs based on the photoacoustic spectroscopy signal of biological tissue. The photoacoustic spectroscopy analysis device for biological samples in the prior art method has the problem of low detection accuracy. SUMMARY

[0006] The embodiments of the present application provide a photoacoustic spectroscopy signal detection system and a detection method, which aim to solve the problem of low detection accuracy of the photoacoustic spectroscopy analysis device for biological samples in the prior art method.

[0007] In a first aspect, the embodiments of the present application provide a photoacoustic spectroscopy signal detection system, wherein the system comprises a signal acquisition device and a detection signal processing terminal, the signal acquisition device comprises an ultraviolet pulse laser, a first plano-convex lens, a second plano-convex lens, a focusing objective lens, a refractive prism, a helium-neon laser, a motorized displacement platform, a polarization modulation component, a light splitting component, and a differential detector.

[0008] The first plano-convex lens and the second plano-convex lens are arranged between the ultraviolet pulse laser and the focusing objective lens; the motorized displacement platform is arranged downstream of the focusing objective lens, a sample is placed on the motorized displacement platform, and the motorized displacement platform is used to drive the sample to move in three dimensions; and a first light path is formed between the focusing objective lens and the motorized displacement platform.

[0009] The polarization modulation component is arranged downstream of the helium-neon laser, and a second light path is formed between the polarization modulation component and the helium-neon laser.

[0010] The first light path and the second light path respectively penetrate the refractive prism from two directions; the light splitting component is arranged downstream of the polarization modulation component, and the differential detector is arranged downstream of the light splitting component; the differential detector receives two light splitting beams from the light splitting component and performs differential detection to obtain a differential detection signal.

[0011] The detection signal processing terminal is connected to the differential detector for data signal transmission. The detection signal processing terminal is used to perform signal analysis and processing on the differential detection signal to obtain the corresponding analysis spectrum.

[0012] The photoacoustic spectrum signal detection system, wherein the polarization modulation component includes a polarizer, a half-wave plate, a λ / 4 glass plate, a third plano-convex lens, and a fourth plano-convex lens;

[0013] The polarizer is located downstream of the helium-neon laser, the half-wave plate is located downstream of the polarizer, the λ / 4 glass plate is located downstream of the half-wave plate, the third plano-convex lens is located between the λ / 4 glass plate and the refractive prism, and the fourth plano-convex lens is located opposite to the third plano-convex lens on both sides of the refractive prism.

[0014] The photoacoustic spectrum signal detection system, wherein the beam splitting component includes a beam splitting prism, a third plane mirror, a first analyzer, and a second analyzer;

[0015] The beam splitter splits the beam from the second optical path into a first beam splitter and a second beam splitter; the first beam splitter is reflected by the third plane mirror and then enters the first analyzer.

[0016] The second beam splitter directly enters the second analyzer;

[0017] The two beams emitted from the first and second analyzers simultaneously enter the differential detector.

[0018] The photoacoustic spectrum signal detection system further includes a fifth plano-convex lens and a sixth plano-convex lens in the beam-splitting component.

[0019] The fifth plano-convex lens is disposed between the first analyzer and the differential detector, and the sixth plano-convex lens is disposed between the second analyzer and the differential detector.

[0020] In the photoacoustic spectrum signal detection system, the deflection directions of the first analyzer and the second analyzer are respectively along the minor axis and major axis of the elliptically polarized beam emitted from the second optical path.

[0021] In the aforementioned photoacoustic spectrum signal detection system, the refracting prism is an isosceles trapezoidal refracting prism;

[0022] The beam of the second optical path enters the isosceles trapezoidal refracting prism and exits after total internal reflection at the wider base of the isosceles trapezoidal refracting prism; the beam of the first optical path enters the isosceles trapezoidal refracting prism and intersects with the beam of the second optical path at the wider base of the isosceles trapezoidal refracting prism.

[0023] In the aforementioned photoacoustic spectrum signal detection system, the refractive index of the isosceles trapezoidal refracting prism is 1.45-1.6.

[0024] The photoacoustic spectrum signal detection system further includes a photomultiplier tube between the detection signal processing terminal and the differential detector.

[0025] The photomultiplier tube amplifies the differential detection signal from the differential detector and outputs it to the detection signal processing terminal.

[0026] On the other hand, embodiments of the present invention also provide a photoacoustic spectrum signal detection method, wherein the photoacoustic spectrum signal detection method is applied to the above-mentioned photoacoustic spectrum signal detection system, and the method includes:

[0027] Adjust the polarization modulation component to make it emit an elliptically polarized beam of light to the refractive prism;

[0028] Adjust the beam splitter so that it emits two beams of equal energy with perpendicular polarization directions;

[0029] The detection signal processing terminal receives the differential detection signal for continuous frequency band detection of the sample and draws the corresponding analysis spectrum.

[0030] The photoacoustic spectral signal detection method, wherein the detection signal processing terminal receives differential detection signals for continuous frequency band detection of the sample and plots the corresponding analytical spectrum, including:

[0031] Calculate the signal difference between the two sets of signals in the differential detection signal at each frequency in the continuous frequency band;

[0032] Plot the corresponding analysis spectrum with the signal difference as the vertical axis and the frequency values ​​in the continuous frequency band as the horizontal axis.

[0033] This invention provides a photoacoustic spectral signal detection system and method. The system includes a signal acquisition device and a detection signal processing terminal. The signal acquisition device includes an ultraviolet pulsed laser, a first plano-convex lens, a second plano-convex lens, a focusing objective lens, a refractive prism, a helium-neon laser, an electric displacement platform, a polarization modulation component, a beam splitting component, and a differential detector. The aforementioned photoacoustic spectral signal detection system utilizes the specific absorption of ultraviolet light by the cell nucleus. A differential detector acquires the differential detection signal and generates an analytical spectrum; a photosensitive component acquires the photosensitive signal of the sample and generates a microscopic image. Based on a high-bandwidth surface wave detector, this detection system can achieve photoacoustic spectral analysis of microscopic absorbers at the cell nucleus level, thereby obtaining high-resolution analytical spectra and microscopic images reflecting the internal physical properties of the cell nucleus. Through label-free and stain-free photoacoustic spectral signal detection, staining is unnecessary, saving time in biological sample detection and significantly improving the accuracy of cell detection in biological samples. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the photoacoustic spectrum signal detection system provided in an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram illustrating the effect of the photoacoustic spectrum signal detection system provided in an embodiment of the present invention;

[0037] Figure 3 This is another schematic diagram illustrating the effect of the photoacoustic spectrum signal detection system provided in an embodiment of the present invention;

[0038] Figure 4 A flowchart illustrating the photoacoustic spectrum signal detection method provided in this embodiment of the invention.

[0039] Reference numerals: 1. Ultraviolet pulsed laser; 2. First plano-convex lens; 3. Second plano-convex lens; 4. First plane mirror; 5. Focusing objective; 6. Helium-neon laser; 7. Polarizer; 8. Half-glass slide; 9. λ / 4 glass slide; 10. Third plano-convex lens; 11. Refractive prism; 12. Fourth plano-convex lens; 13. Second plane mirror; 14. Beam splitter prism; 15. Third plane mirror; 16. First analyzer; 17. Second analyzer; 18. Fifth plano-convex lens; 19. Sixth plano-convex lens; 20. Differential detector; 21. Sample; 22. Electrodynamic displacement platform; 23. Photomultiplier tube; 30. Detection signal processing terminal. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0042] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0043] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0044] In this embodiment, please refer to Figure 1 , Figure 1This is a schematic diagram of the photoacoustic spectrum signal detection system provided in an embodiment of the present invention. As shown in the figure, the present invention provides a photoacoustic spectrum signal detection system, which includes a signal acquisition device and a detection signal processing terminal 30. The signal acquisition device includes an ultraviolet pulsed laser 1, a first plano-convex lens 2, a second plano-convex lens 3, a focusing objective lens 5, a refractive prism 11, a helium-neon laser 6, an electric displacement platform 22, a polarization modulation component, a beam splitting component, and a differential detector 20. The first plano-convex lens 2 and the second plano-convex lens 3 are disposed between the ultraviolet pulsed laser 1 and the focusing objective lens 5. The electric displacement platform 22 is disposed downstream of the focusing objective lens 5, and a sample 21 is placed on the electric displacement platform 22. The electric displacement platform 22 is used to drive the sample 21 to perform three-dimensional movement. The focusing objective lens 5 and the electric displacement platform 22 are connected to the focusing objective lens 5. A first optical path is formed between the displacement platforms 22; the polarization modulation component is disposed downstream of the helium-neon laser 6, and a second optical path is formed between the polarization modulation component and the helium-neon laser 6; the first optical path and the second optical path pass through the refractive prism 11 from two directions respectively; the beam splitting component is disposed downstream of the polarization modulation component, and the differential detector 20 is disposed downstream of the beam splitting component; the differential detector 20 receives two beams from the beam splitting component and performs differential detection to obtain a differential detection signal; the detection signal processing terminal 30 is communicatively connected to the differential detector 20 for data signal transmission, and the detection signal processing terminal 30 is used to perform signal analysis processing on the differential detection signal to obtain the corresponding analysis spectrum. The photoacoustic spectrum signal detection system includes a polarization modulation component comprising a polarizer 7, a half-wave plate, a λ / 4 glass plate 9, a third plano-convex lens 10, and a fourth plano-convex lens 12. The polarizer 7 is located downstream of the helium-neon laser 6, the half-wave plate is located downstream of the polarizer 7, the λ / 4 glass plate 9 is located downstream of the half-wave plate, the third plano-convex lens 10 is located between the λ / 4 glass plate 9 and the refractive prism 11, and the fourth plano-convex lens 12 is located opposite to the third plano-convex lens 10 on both sides of the refractive prism 11.

[0045] The system includes an ultraviolet pulsed laser 1 for generating ultraviolet pulsed laser light (also known as ultraviolet excitation light), which can produce wavelengths of 210-290 nm. The wavelength can be varied depending on the sample 21, with the wavelength chosen to maximize the absorption coefficient and generate the strongest light signal. For example, for the biological sample 21 of colorectal tissue, the wavelength of the ultraviolet pulsed laser generated by the ultraviolet pulsed laser 1 is 266 nm. A helium-neon laser 6 generates a probe beam with a wavelength of 530-750 nm, corresponding to different excitation angles. A polarization modulation component modulates the polarization component of the probe beam generated by the helium-neon laser 6, changing the ratio of s-rays to p-rays and adjusting the beam output from the second optical path to elliptically polarized light. A first plano-convex lens 2 and a second plano-convex lens 3 expand the ultraviolet excitation light beam. A photosensitive component collects the photosensitive signal generated by the ultraviolet excitation light irradiating the sample 21. A detection signal processing terminal 30 processes the photosensitive signal to obtain a cellular-level microscopic image of the sample 21. The focusing objective 5 focuses the ultraviolet excitation light. The beam splitter is used to split the probe beam output from the second optical path into two beams with different polarization directions, which are then output to the differential detector 20. The differential detector 20 performs differential detection on the two split beams to obtain a differential detection signal. The differential detector includes two receiving ports, each corresponding to one split beam. The differential detector 20 can automatically process the split beams from the two receiving ports and output a differential detection signal. Both the first plane mirror 4 and the second plane mirror 13 are used to reflect the beam to change its transmission path.

[0046] In the process of probing biological samples, the cell nucleus can be considered as a sphere, with an assumed radius of 1. If the center of the microsphere is located at the origin of the spherical coordinate system, then the photoacoustic pressure inside the microsphere and the photoacoustic pressure outside the microsphere can be expressed by formula (1) and formula (2) respectively:

[0047] (1);

[0048] (2);

[0049] Among them, P s P is the wavenumber within the microsphere (cell nucleus). f k is the wavenumber outside the microsphere (cytoplasm). s Let k be the amplitude within the microsphere. f ω represents the amplitude outside the microsphere, r represents the radial coordinate of the cell nucleus, ω is the angular frequency, and t represents time. The wavenumber inside the microsphere, Let i be the wave number outside the microsphere, and i be an imaginary number.

[0050] Based on the boundary conditions, formulas (3) and (4) can be derived:

[0051] (3);

[0052] (4);

[0053] Further, we obtain formulas (5) and (6):

[0054] (5);

[0055] (6);

[0056] Where a is the radius of the microsphere.

[0057] Define density separately speed of sound , wave number Further, we obtain formulas (7) and (8):

[0058] (7);

[0059] (8);

[0060] Where, ρ s ρ is the density inside the microsphere. f The density outside the microspheres, The ratio of the density inside and outside of the microsphere. This is the ratio of the sound velocity coefficients inside and outside the microsphere.

[0061] Solving the above formulas simultaneously, the acoustic-optical pressure outside the microsphere is expressed by formula (9):

[0062] (9);

[0063] in, For isobaric specific heat capacity, Coefficient of thermal expansion, optical absorption coefficient Light intensity optical absorption coefficient , For light intensity, A dimensionless variable related to frequency, For a dimensionless variable that is related to time, The time delay starting from the edge of the microsphere is represented by the correlation coefficient, which can be expressed using formulas (10) and (11):

[0064] (10);

[0065] (11).

[0066] The aforementioned photoacoustic spectrum signal detection system can obtain a series of signals from... , and The determined photoacoustic spectrum, combined with the detection bandwidth response of the photoacoustic spectrum signal detection system, yields the relationship between density, sound velocity, microsphere diameter, and photoacoustic spectrum. Formula (9) above demonstrates the influence of the density and sound velocity differences between the sample and the medium on the photoacoustic spectrum. Therefore, a universal conclusion can be drawn: the characteristics of the photoacoustic spectrum are determined by the shape and size of the light absorber and its differences in density and sound velocity with the medium. For cells at different pathological stages, such as normal, precancerous, and cancerous cells, the size, density, and sound velocity of their nuclei differ. Therefore, obtaining the acoustic spectrum analysis information of the sample through photoacoustic spectrum analysis can serve as an accurate basis for pathological diagnostic analysis, proving the theoretical feasibility of conducting case diagnostic analysis using the obtained analytical spectra and microscopic images.

[0067] The specific calculation results obtained based on the above formula (9) are as follows: Figure 2 As shown, Figure 2 Figure (a) shows the calculated photoacoustic spectra of microspheres with different radii; Figure 2 Figure (b) shows the calculated photoacoustic spectra of microspheres with different densities; Figure 2 Figure (c) shows the calculated photoacoustic spectrum of microspheres with different sound velocities.

[0068] In a more specific embodiment, the polarization modulation assembly includes a polarizer 7, a half-wave plate, a λ / 4 glass plate 9, a third plano-convex lens 10, and a fourth plano-convex lens 12; the polarizer 7 is disposed downstream of the helium-neon laser 6, the half-wave plate is disposed downstream of the polarizer 7, the λ / 4 glass plate 9 is disposed downstream of the half-wave plate, the third plano-convex lens 10 is disposed between the λ / 4 glass plate 9 and the refractive prism 11, and the fourth plano-convex lens 12 is disposed opposite to the third plano-convex lens 10 on both sides of the refractive prism 11.

[0069] Specifically, polarizer 7 polarizes the probe beam; a half-wave plate modulates the polarization component of the probe beam, thereby changing the ratio of s-rays to p-rays; and a λ / 4 glass plate 9 adjusts the probe beam into elliptically polarized light. A third plano-convex lens 10 focuses the beam so that it concentrates into the refracting prism 11, and a fourth plano-convex lens 12 expands the beam. In practical applications, rotating the half-glass plate 8 adjusts the ratio of s-rays to p-rays in the probe beam to 1:1; rotating the λ / 4 glass plate 9 adjusts the probe beam into elliptically polarized light, with the elliptically polarized light making an angle of π / 4 with the optical axis.

[0070] In a more specific embodiment, the beam-splitting assembly includes a beam-splitting prism 14, a third plane mirror 15, a first analyzer 16, and a second analyzer 17. The beam-splitting prism 14 splits the beam from the second optical path into a first split beam and a second split beam. The first split beam is reflected by the third plane mirror 15 and then enters the first analyzer 16. The second split beam directly enters the second analyzer 17. The two split beams emitted from the first analyzer 16 and the second analyzer 17 simultaneously enter the differential detector 20. Specifically, the beam-splitting assembly also includes a fifth plano-convex lens 18 and a sixth plano-convex lens 19. The fifth plano-convex lens 18 is disposed between the first analyzer 16 and the differential detector 20, and the sixth plano-convex lens 19 is disposed between the second analyzer 17 and the differential detector 20. The deflection directions of the first analyzer 16 and the second analyzer 17 are respectively along the minor axis and major axis of the elliptically polarized beam emitted from the second optical path.

[0071] The beam splitter prism 14 splits the probe beam into two beams. One beam is reflected by the third plane mirror 15 and enters the first analyzer 16, while the other beam directly enters the second analyzer 17. The deflection directions of the first and second analyzers 16 and 17 can be set along the minor and major axes of the elliptically polarized light, respectively, to maximize the sensitivity of the acquired differential detection signal, thus putting the detection system in its most sensitive state. To further improve detection accuracy, a fifth plano-convex lens 18 can be placed between the first analyzer 16 and the differential detector 20, and a sixth plano-convex lens 19 can be placed between the second analyzer 17 and the differential detector 20. The fifth and sixth plano-convex lenses 18 and 19 focus the two beams, thereby further improving the sensitivity of the differential detector 20 in detecting the split beams, and thus improving the accuracy of the obtained differential detection signal.

[0072] In a more specific embodiment, the refractive prism 11 is an isosceles trapezoidal refractive prism; the light beam of the second optical path enters the isosceles trapezoidal refractive prism and exits after total internal reflection at the wider base of the isosceles trapezoidal refractive prism; the light beam of the first optical path enters the isosceles trapezoidal refractive prism and intersects with the light beam of the second optical path at the wider base of the isosceles trapezoidal refractive prism. The refractive index of the isosceles trapezoidal refractive prism is 1.45-1.6.

[0073] In practical applications, the refractive prism 11 can be configured as an isosceles trapezoidal refractive prism. The detection beam in the second optical path enters from one side of the isosceles trapezoidal prism and exits from the other side, with the entry and exit directions of the detection beam being consistent. This reduces transmission loss of the detection beam and further improves the accuracy of acquiring the differential detection signal. In practical applications, to ensure total internal reflection of the detection beam on the wider base of the isosceles trapezoidal refractive prism, the refractive index of the isosceles trapezoidal refractive prism can be set to 1.45-1.6. For example, in this embodiment, the refractive prism is made of BK7 glass with a refractive index of 1.517.

[0074] In a more specific embodiment, a photomultiplier tube 23 is further provided between the detection signal processing terminal 30 and the differential detector 20; the photomultiplier tube 23 amplifies the differential detection signal from the differential detector 20 and outputs it to the detection signal processing terminal 30.

[0075] To further improve the detection effect of the differential detector 20, a photomultiplier tube 23 can be installed between the differential detector 20 and the detection signal processing terminal 30. The differential detection signal obtained by the photomultiplier tube 23 is amplified and processed to obtain a clearer differential detection signal.

[0076] The aforementioned photoacoustic spectral signal detection system is an ultraviolet photoacoustic system based on phase-mode total internal reflection (TIR) ​​optical surface wave sensing. It can achieve high-sensitivity, broadband detection of pathological tissue signals. Combining photoacoustic imaging with photoacoustic spectral analysis, the system can be used as preliminary detection information for pathological diagnostic analysis. This invention provides a high-bandwidth photoacoustic spectral analysis technique, employing a phase-mode total internal reflection optical surface wave sensor to detect photoacoustic signals. Compared to traditional photoacoustic microscopy, the photoacoustic spectral analysis of the aforementioned system not only reveals differences in the structure of microscopic absorbers but can also distinguish between microscopic absorbers with the same morphology but different mechanical properties—a capability lacking in traditional photoacoustic imaging.

[0077] Based on the aforementioned photoacoustic spectral signal detection system, colorectal pathological tissues at three different pathological stages—normal, adenoma (precancerous), and adenocarcinoma—were imaged. The obtained microscopic images and analytical maps are as follows: Figure 3 As shown. Among them, Figure 3 Figure (a) shows a microscopic image of a normal cell obtained using the aforementioned photoacoustic spectroscopy signal detection system. Figure 3 Figure (b) shows a microscopic image of adenoma cells. Figure 3 Figure (c) shows a microscopic image of adenocarcinoma cells. Different types of differential detectors 20 can all acquire analytical maps that differentiate between normal cells, adenocarcinoma cells, and adenocarcinoma cells. Figure 3Figure (d) shows the analytical maps corresponding to normal cells, adenoma cells, and adenocarcinoma cells obtained by the differential detector 20, which is an optical surface wave sensor. Figure 3 Figure (e) shows the analytical atlases corresponding to normal cells, adenoma cells, and adenocarcinoma cells obtained by a differential detector 20 using a piezoelectric ultrasonic transducer. From the above microscopic images and analytical atlases, it can be concluded that the aforementioned photoacoustic spectral signal detection system can accurately distinguish between normal cells, adenoma cells, and adenocarcinoma cells based on photoacoustic spectral detection information, thereby improving the accuracy of classifying different cell types based on the photoacoustic spectral detection information obtained by the system.

[0078] Please see Figure 4 , Figure 4 This is a schematic flowchart of the photoacoustic spectrum signal detection method provided in an embodiment of the present invention. The present invention also provides a photoacoustic spectrum signal detection method, wherein the photoacoustic spectrum signal detection method is applied to the aforementioned photoacoustic spectrum signal detection system, such as... Figure 4 As shown, the method includes steps S110-S140.

[0079] S110. Adjust the polarization modulation component to make the polarization modulation component emit an elliptically polarized beam to the refractive prism.

[0080] Specifically, the polarizer polarizes the probe beam; the half-wave plate modulates the polarization component of the probe beam, thereby changing the ratio of s-rays to p-rays; the λ / 4 plate adjusts the probe beam into elliptically polarized light. The third plano-convex lens focuses the beam so that the probe beam is concentrated into the refracting prism, and the fourth plano-convex lens expands the beam. In practical applications, rotating the half-wave plate adjusts the ratio of s-rays to p-rays in the probe beam to 1:1; rotating the λ / 4 plate adjusts the probe beam into elliptically polarized light, with the elliptically polarized light making an angle of π / 4 with the optical axis.

[0081] S120. Adjust the beam splitter so that it emits two beams of equal energy and perpendicular polarization direction.

[0082] The beam splitter is used to split the probe beam into two beams. One beam is reflected by the third plane mirror and enters the first analyzer, while the other beam enters the second analyzer directly. The deflection directions of the first and second analyzers can be set along the minor axis and major axis of the elliptical polarized light, respectively, so as to maximize the sensitivity of the acquired differential detection signal, that is, to put the detection system in the most sensitive state.

[0083] S130, The detection signal processing terminal receives the differential detection signal for continuous frequency band detection of the sample and draws the corresponding analysis spectrum.

[0084] This allows the probe beam to continuously probe the sample within a specific frequency band; different types of differential detectors use different detection frequency bands. By plotting the differential detection signals corresponding to the continuous frequency bands, an analytical spectrum can be obtained, as shown in the image. Figure 3 As shown in Figures (d) and (e), the detection frequency band can be determined based on the differences in the samples to be detected and the type of differential detector selected. The detected differential detection signal must be able to clearly distinguish the differences between the spectral lines of the differential detection signals of different types of cell samples. For example, for a differential detector of the optical surface wave sensor type, the frequency band of the detection beam can be set to 0-200MHz; for a differential detector of the piezoelectric ultrasonic transducer type, the frequency band of the detection beam can be set to 0-100MHz.

[0085] The specific process of obtaining the analysis spectrum includes calculating the signal difference between the two sets of signals in the differential detection signal at each frequency in the continuous frequency band, that is, subtracting the two sets of signals in the detection signal; and plotting the corresponding analysis spectrum with the signal difference as the vertical axis and each frequency value in the continuous frequency band as the horizontal axis.

[0086] S140, The detection signal processing terminal receives the photosensitive signal collected by the photosensitive component and performs imaging to obtain a microscopic image.

[0087] The detection signal processing terminal can also receive the photosensitive signals collected by the photosensitive components, and perform imaging based on the photosensitive signals to obtain cell-level microscopic images.

[0088] This invention provides a photoacoustic spectral signal detection system and method. The system includes a signal acquisition device and a detection signal processing terminal. The signal acquisition device includes an ultraviolet pulsed laser, a first plano-convex lens, a second plano-convex lens, a focusing objective, a refractive prism, a helium-neon laser, an electric displacement platform, a polarization modulation component, a beam splitting component, and a differential detector. The aforementioned photoacoustic spectral signal detection system utilizes the specific absorption of ultraviolet light by the cell nucleus. A differential detector acquires a differential detection signal and generates an analytical spectrum; a photosensitive component acquires the photosensitive signal of the sample and generates a microscopic image. Based on a high-bandwidth surface wave detector, this detection system can achieve photoacoustic spectral analysis of microscopic absorbers at the cell nucleus level, thereby obtaining high-resolution analytical spectra and microscopic images reflecting the internal physical properties of the cell nucleus. Through label-free and stain-free photoacoustic spectral signal detection, staining is unnecessary, saving time in biological sample detection and significantly improving the accuracy of cell detection in biological samples.

[0089] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A photoacoustic spectrum signal detection system, characterized in that, The system includes a signal acquisition device and a detection signal processing terminal. The signal acquisition device includes an ultraviolet pulsed laser, a first plano-convex lens, a second plano-convex lens, a focusing objective lens, a refractive prism, a helium-neon laser, an electric displacement platform, a polarization modulation component, a beam splitting component, and a differential detector. The ultraviolet pulsed laser generated by the ultraviolet pulsed laser has a wavelength of 210-290 nm; The The photoacoustic spectrum signal detection system is an ultraviolet photoacoustic system based on phase mode total internal reflection optical surface wave sensing; The first plano-convex lens and the second plano-convex lens are disposed between the ultraviolet pulsed laser and the focusing objective lens; The electric displacement platform is located downstream of the focusing objective, and the sample is placed on the electric displacement platform. The electric displacement platform is used to drive the sample to move in three dimensions; a first optical path is formed between the focusing objective and the electric displacement platform. The polarization modulation component is disposed downstream of the helium-neon laser, and a second optical path is formed between the polarization modulation component and the helium-neon laser; The first optical path and the second optical path pass through the refractive prism from two directions respectively; the beam splitting component is disposed downstream of the polarization modulation component, and the differential detector is disposed downstream of the beam splitting component; the differential detector receives the two beams split from the beam splitting component and performs differential detection to obtain a differential detection signal; The detection signal processing terminal is connected to the differential detector and the photosensitive component on the electric displacement platform for data signal transmission. The detection signal processing terminal is used to image the photosensitive signal collected by the photosensitive component to obtain a microscopic image, and to perform signal analysis processing on the differential detection signal to obtain a corresponding analysis spectrum. The polarization modulation assembly includes a polarizer, a half-wave plate, a λ / 4 glass plate, a third plano-convex lens, and a fourth plano-convex lens. The polarizer is located downstream of the helium-neon laser, the half-wave plate is located downstream of the polarizer, the λ / 4 glass plate is located downstream of the half-wave plate, the third plano-convex lens is located between the λ / 4 glass plate and the refractive prism, and the fourth plano-convex lens is located opposite to the third plano-convex lens on both sides of the refractive prism; the λ / 4 glass plate adjusts the probe beam into elliptically polarized light, and the angle between the elliptically polarized light and the optical axis is π / 4. The refracting prism is an isosceles trapezoidal refracting prism; The beam of the second optical path enters the isosceles trapezoidal refracting prism and exits after total internal reflection at the wider base of the isosceles trapezoidal refracting prism; the beam of the first optical path enters the isosceles trapezoidal refracting prism and intersects with the beam of the second optical path at the wider base of the isosceles trapezoidal refracting prism.

2. The photoacoustic spectrum signal detection system according to claim 1, characterized in that, The beam-splitting assembly includes a beam-splitting prism, a third plane mirror, a first polarizer, and a second polarizer; The beam splitter splits the beam from the second optical path into a first beam and a second beam; the first beam is reflected by the third plane mirror and then enters the first analyzer; the second beam directly enters the second analyzer. The two beams emitted from the first and second analyzers simultaneously enter the differential detector.

3. The photoacoustic spectrum signal detection system according to claim 2, characterized in that, The beam-splitting assembly also includes a fifth plano-convex lens and a sixth plano-convex lens; The fifth plano-convex lens is disposed between the first analyzer and the differential detector, and the sixth plano-convex lens is disposed between the second analyzer and the differential detector.

4. The photoacoustic spectrum signal detection system according to claim 2, characterized in that, The deflection directions of the first analyzer and the second analyzer are respectively along the minor axis and major axis of the elliptically polarized beam emitted from the second optical path.

5. The photoacoustic spectrum signal detection system according to claim 4, characterized in that, The refractive index of the isosceles trapezoidal refracting prism is 1.45-1.

6.

6. The photoacoustic spectrum signal detection system according to any one of claims 1-3, characterized in that, A photomultiplier tube is also provided between the detection signal processing terminal and the differential detector; The photomultiplier tube amplifies the differential detection signal from the differential detector and outputs it to the detection signal processing terminal.

7. A method for detecting photoacoustic spectrum signals, characterized in that, The photoacoustic spectrum signal detection method is applied to the photoacoustic spectrum signal detection system as described in any one of claims 1-6, and the method includes: Adjust the polarization modulation component to make it emit an elliptically polarized beam of light to the refractive prism; Adjust the beam splitter so that it emits two beams of equal energy with perpendicular polarization directions; The detection signal processing terminal receives the differential detection signal for continuous frequency band detection of the sample and draws the corresponding analysis spectrum. The detection signal processing terminal receives the photosensitive signal collected by the photosensitive component and performs imaging to obtain a microscopic image.

8. The photoacoustic spectrum signal detection method according to claim 7, characterized in that, The detection signal processing terminal receives the differential detection signal for continuous frequency band detection of the sample and plots the corresponding analytical spectrum, including: Calculate the signal difference between the two sets of signals in the differential detection signal at each frequency in the continuous frequency band; Plot the corresponding analysis spectrum with the signal difference as the vertical axis and the frequency values ​​in the continuous frequency band as the horizontal axis.

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