A non-contact polarization photoacoustic detection device and method for quality identification of traditional Chinese medicine

Abstract

The present invention provides a non-contact polarization photoacoustic detection device and method for quality identification of traditional Chinese medicines. The device uses a polarization-modulated pulsed excitation light beam to excite a traditional Chinese medicine sample, and uses a continuous-wave detection light beam confocal with the excitation light beam to measure the refractive index change caused by the photoacoustic initial pressure generated by the sample absorbing the energy of the excitation light pulse. By detecting the reflected component of the detection light beam, the device can obtain anisotropic optical absorption information of the traditional Chinese medicine. The polarization photoacoustic image of the traditional Chinese medicine and its anisotropic characteristic information obtained by the non-contact polarization photoacoustic detection device and method can be used to identify the quality of traditional Chinese medicine, and the entire process does not require destruction of the traditional Chinese medicine sample, thus realizing non-contact in-situ detection.

Description

Technical Field

[0001] The invention belongs to the field of non-destructive detection of traditional Chinese medicines, and is particularly suitable for non-contact detection of quality identification of traditional Chinese medicines. Background Art

[0002] As a core component of traditional Chinese medicine, Traditional Chinese Medicine (TCM) plays a vital role in disease treatment and healthcare. The quality of TCM materials, the material foundation of TCM, is directly related to the safety and efficacy of clinical medications. However, the diverse nature of TCM materials, their diverse sources, scattered production areas, and varying processing and storage conditions lead to varying quality. Therefore, effective quality identification and control measures are crucial to ensuring the quality and safety of TCM materials.

[0003] Currently, methods for identifying Chinese medicinal materials (TCMs) primarily include character identification, microscopic identification, and physicochemical identification. Character identification primarily assesses the quality of the medicinal material by observing its morphology, color, and flavor. This method relies heavily on the experience of the appraiser and can quickly provide preliminary identification of TCMs. However, it is highly subjective and lacks objective and unified standards, resulting in low efficiency and accuracy, making it difficult to effectively apply in large-scale production. Microscopic identification relies on standard optical microscopy techniques, but its application is limited, applicable only to imaging stained thin sections and powders. It also lacks intelligent analytical methods and is unsuitable for quantitative analysis of complex components. Physicochemical identification, including chromatography, mass spectrometry, and spectroscopy, utilizes characteristic spectral data to identify the authenticity and quality of TCMs. Chromatography can quantitatively analyze complex TCM components, but it requires time-consuming and complex pretreatment steps before sample analysis. This process can potentially destroy information about the distribution of compounds within the sample's internal structure, and it also carries high equipment and operating costs, requiring specialized technical support. Mass spectrometry has high sensitivity and high resolution, and is suitable for analyzing complex mixtures; however, the sample preparation and operation process are complicated, and it is sensitive to sample background, experimental environment, and operating conditions. The equipment is expensive and the analysis cost is high.

[0004] In recent years, spectral imaging has become an important means of detecting Chinese medicinal materials, covering a variety of technologies such as fluorescence spectroscopy, near-infrared spectroscopy, and laser-induced breakdown spectroscopy. Near-infrared spectroscopy has the advantages of convenient testing and rapid analysis, but its sensitivity is relatively low and it has difficulty distinguishing similar substances. Fluorescence spectroscopy has high sensitivity, but its application is limited by whether the medicinal materials contain fluorescent groups. The introduction of exogenous fluorescent probes may cause changes in the original state or efficacy of the medicinal materials. Laser-induced breakdown spectroscopy can provide qualitative information on elements, but it has difficulties in quantitative analysis and poor stability. It may cause ablation damage to Chinese medicinal materials, which is not conducive to achieving completely non-destructive detection.

[0005] Existing testing methods for Chinese medicinal materials cannot fully meet the rapid development needs of the industry. Therefore, how to achieve rapid, non-destructive and accurate testing of Chinese medicinal materials remains an urgent problem to be solved. Summary of the Invention

[0006] In order to overcome the shortcomings and deficiencies of existing Chinese medicinal materials detection technology, the present invention provides a non-contact polarization photoacoustic detection device and method for Chinese medicinal materials quality identification. Based on the macroscopic anisotropy caused by the orientation and arrangement differences of different internal tissue structures of Chinese medicinal materials at the microscale, an all-optical polarization photoacoustic system is used to detect optical absorption differences, thereby realizing non-contact in-situ detection of the internal structure of Chinese medicinal materials and their anisotropic characteristics. Combined with deep learning algorithms for data processing and analysis, the device and method can realize rapid and non-destructive quality identification of Chinese medicinal materials.

[0007] The present invention provides a non-contact polarization photoacoustic detection device for identifying the quality of traditional Chinese medicine. The device includes: an excitation light output module, a polarization modulation module, a detection light output module, a polarization control module, a beam combining module, a light scanning module, a test object module, a photoelectric detection module, and a data acquisition and image processing module.

[0008] The excitation light output module is used to provide the incident excitation light beam after collimation and expansion.

[0009] The polarization modulation module is used to modulate the incident excitation light beam to form a first linearly polarized light beam with a polarization direction switched among 0°, 45°, 90° and 135°.

[0010] The detection light output module is used to provide the incident detection light beam after collimation and expansion.

[0011] The polarization control module is used to change the polarization state of the incident detection beam. The incident detection beam is converted into a second linearly polarized beam through a polarization beam splitter, and the second linearly polarized beam is converted into a third circularly polarized beam through a quarter wave plate.

[0012] The beam combining module is used to combine the first linearly polarized light beam and the third circularly polarized light beam into the same optical path.

[0013] The light scanning module is used to focus the combined first linearly polarized light beam and the third circularly polarized light beam onto the Chinese medicinal material sample of the object to be tested module, and change its incident position on the sample within a certain range of a designated area to perform scanning imaging.

[0014] The test object module is used to carry and move Chinese medicinal material samples.

[0015] The first linearly polarized beam is focused onto the Chinese herbal medicine sample and absorbed. The third circularly polarized beam is reflected by the sample and converted into a fourth circularly polarized beam with an opposite rotational direction. The fourth circularly polarized beam passes through the optical scanning module and is reflected by the dichroic mirror in the beam combining module. After passing through a quarter-wave plate, it is converted into a fifth linearly polarized beam with a polarization direction orthogonal to that of the second linearly polarized beam. The fifth linearly polarized beam is then reflected by the polarization beam splitter in the polarization control module and directed to the photodetection module.

[0016] The photoelectric detection module is used to receive the fifth linearly polarized light beam reflected by the polarization beam splitter and convert the optical signal into an electrical signal.

[0017] The data acquisition and image processing module converts the electrical signal into a digital signal and processes it to generate polarized photoacoustic images and quality identification results of the Chinese medicinal material samples.

[0018] Specifically, after the Chinese herbal medicine sample absorbs the pulse energy of the first linearly polarized light beam, it generates an initial photoacoustic pressure based on the photoacoustic effect. The refractive index of the sample changes due to the photoelastic effect, which in turn causes a change in the reflection intensity of the third circularly polarized light beam. Therefore, after passing through the Chinese herbal medicine sample, the third circularly polarized light beam carries a polarized photoacoustic signal and is reflected. The reflected light beam is called the fourth circularly polarized light beam, and its rotation direction is opposite to that of the third circularly polarized light beam. After passing through the optical scanning module, the fourth circularly polarized light beam is reflected by the dichroic mirror in the beam combining module. After passing through the quarter-wave plate, it is converted into a fifth linearly polarized light beam with a polarization direction orthogonal to that of the second linearly polarized light beam. It is then reflected by the polarization beam splitter to the photodetection module. In the photodetection module, the fifth linearly polarized light beam passes through a focusing lens and a filter and is transmitted to a photodetector. The photodetector converts the optical signal into an electrical signal. Finally, the electrical signal is converted into a digital signal and processed by the data acquisition and image processing module to generate a polarized photoacoustic image of the Chinese herbal medicine sample and a quality identification result.

[0019] Specifically, the excitation light output module includes a nanosecond pulse laser and a collimating beam expander, which is used to provide an incident excitation light beam, wherein the nanosecond pulse laser includes an ultraviolet laser, a visible light laser, and a near-infrared laser.

[0020] The polarization modulation module includes a polarizer and a half-wave plate, and is used to modulate the linear polarization direction of the incident excitation light beam to switch between 0°, 45°, 90° and 135°.

[0021] The detection light output module includes a 1310nm superluminescent diode and a collimating beam expander, and is used to provide an incident detection light beam.

[0022] The polarization control module includes a polarization beam splitter and a quarter wave plate, which is used to control the polarization state of the incident detection beam to transmit the incident detection beam to the dichroic mirror and reflect the reflected detection beam returned by the sample to the photoelectric detection module.

[0023] The beam combining module includes a dichroic mirror, which is used to combine the incident excitation light beam and the incident detection light beam into the same light path.

[0024] The optical scanning module includes a two-dimensional scanning galvanometer and a focusing objective lens, which is used to focus the incident excitation light beam and the incident detection light beam onto the Chinese medicinal material sample, and change the incident position on the sample within a certain range of a specified area to perform scanning imaging.

[0025] The test object module includes a three-dimensional movable sample stage for carrying and moving Chinese medicinal material samples.

[0026] The photoelectric detection module includes a filter, a focusing lens and a photoelectric detector, which is used to receive the reflected detection light beam carrying the polarized photoacoustic signal returned by the Chinese medicinal material sample and convert the optical signal into an electrical signal.

[0027] The data acquisition and image processing module, including a bandpass filter, a data acquisition card and computer equipment, is used to collect the signals output by the photoelectric detection module, convert the electrical signals into digital analog signals, and transmit them to the computer for data processing, imaging reconstruction and identification and classification.

[0028] Specifically, a nanosecond pulsed laser emits an incident excitation beam of ultraviolet and / or visible light and / or near-infrared light. This beam is collimated and expanded by a collimating beam expander of the corresponding wavelength. After passing through a polarizer, the incident excitation beam becomes linearly polarized light. A half-wave plate is used to change the linear polarization direction of the incident excitation beam. A 1310nm superluminescent diode emits an incident probe beam. After collimation and expansion by the collimating beam expander, the incident probe beam becomes linearly polarized light by a polarizing beam splitter. After passing through a quarter-wave plate, its polarization state is changed from linear polarization to circular polarization. A dichroic mirror transmits the incident excitation beam and reflects the incident probe beam into the same optical path. The combined incident excitation and probe beams are reflected by a scanning galvanometer into an achromatic objective lens and ultimately focused onto a Chinese medicinal material sample on a three-dimensional movable sample stage. After the Chinese medicinal material sample absorbs the energy of the incident excitation beam pulses of different linear polarization directions, the initial pressure changes due to the photoacoustic effect. This, in turn, causes a change in the refractive index due to the photoelastic effect, which in turn changes the reflectivity of the Chinese medicinal material sample to the incident probe beam. The reflected probe beam, after passing through the TCM sample, carries the polarized photoacoustic signal of the TCM sample, with a circular polarization direction opposite to that of the incident probe beam. After passing through the achromatic objective, scanning galvanometer, and dichroic mirror, the reflected probe beam reaches a quarter-wave plate, where it becomes linearly polarized light orthogonal to the polarization direction of the linearly polarized incident probe beam. This light is then reflected by a polarizing beam splitter and directed to a focusing lens. After being focused by the focusing lens, it passes through a filter and is ultimately received by a photodetector. The photodetector converts the optical signal into an electrical signal, which is then passed through a bandpass filter and a data acquisition card to a computer for data processing and image display.

[0029] Specifically, the present invention also provides a non-contact polarization photoacoustic detection method for identifying the quality of traditional Chinese medicine, which specifically includes the following steps:

[0030] S1. Select a Chinese medicinal material sample and place it on the sample table of the test object module.

[0031] S2. Configure the excitation light source in the excitation light output module and the detection light source in the detection light output module, adjust the optical path so that the incident excitation light beam and the incident detection light beam are combined to achieve coaxial transmission and confocus to the same position of the Chinese medicinal material sample through the optical scanning module, and synchronously configure the optical scanning module and the photoelectric detection module to ensure accurate excitation and collection of polarized photoacoustic signals in the corresponding area.

[0032] S3. Adjust the polarization modulation module so that the linear polarization direction of the incident excitation beam switches between 0°, 45°, 90° and 135°, and obtain the polarized photoacoustic signals of the Chinese medicinal materials in the corresponding areas under the four linear polarization directions of the incident excitation beam one by one.

[0033] S4. Import the collected polarized photoacoustic signals of Chinese medicinal materials into MATLAB for data processing to generate polarized photoacoustic images of Chinese medicinal materials.

[0034] S5. Use deep learning networks to segment and classify polarized photoacoustic images of Chinese medicinal materials to identify their varieties and origins.

[0035] S6. Output the quality identification results of Chinese medicinal materials.

[0036] Based on the macroscopic anisotropy caused by differences in the orientation and arrangement of different tissue structures within traditional Chinese medicines (TCMs), this paper develops a non-contact polarization photoacoustic detection device for rapid, non-destructive testing of the structural characteristics of TCMs. By detecting the optical absorption anisotropy of TCMs, internal structural information, including tissue characteristics, microstructure, and degree of dryness, can be revealed. This information provides important evidence for the quality control and identification of TCMs. The non-contact polarization photoacoustic detection device uses an all-optical system combining polarization-modulated pulsed light excitation and continuous light detection to image the anisotropic structures of TCMs. A polarization-modulated pulsed excitation beam excites the sample, while a continuous-wave probe beam, confocal with the excitation beam, measures the local refractive index change caused by the photoacoustic initial pressure generated by the sample's absorption of the excitation light pulse energy. The reflected component of the probe beam contains information about the sample's anisotropic optical absorption. The combined use of these two beams overcomes the need for a coupling agent in traditional photoacoustic systems, achieving true non-contact imaging. The present invention relies solely on optical absorption, avoiding the interference of optical scattering on imaging accuracy. Non-contact polarization photoacoustic imaging technology has the advantages of high signal-to-noise ratio, optical sectioning, no need for labeling and complex preprocessing, avoiding physical damage to Chinese medicinal materials and ensuring in situ detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0038] Figure 1 The figure is a structural diagram of a non-contact polarization photoacoustic detection device for quality identification of traditional Chinese medicine.

[0039] Figure 2 This is a schematic diagram of the structure of another non-contact polarization photoacoustic detection device used for quality identification of traditional Chinese medicine.

[0040] Figure 3 The figure is a flow chart of a non-contact polarization photoacoustic detection method for quality identification of traditional Chinese medicine.

[0041] Figure 4 The figure is the experimental result.

[0042] Figure 5 This is a diagram showing the regional classification results of Sinomene Atractylodes lancea according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0043] In the following description, specific details such as particular system structures and techniques are provided for purposes of illustration, not limitation, to facilitate a thorough understanding of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

[0044] The present invention will be further described in detail below with reference to the accompanying drawings.

[0045] The present invention provides a non-contact polarization photoacoustic detection device for identifying the quality of Chinese medicinal materials. Figure 1 The device includes: an excitation light output module, a polarization modulation module, a detection light output module, a polarization control module, a beam combining module, a light scanning module, a test object module, a photoelectric detection module, and a data acquisition and image processing module.

[0046] The excitation light output module is used to provide the incident excitation light beam after collimation and expansion.

[0047] The polarization modulation module is used to modulate the incident excitation light beam to form a first linearly polarized light beam with a polarization direction switched among 0°, 45°, 90° and 135°.

[0048] The detection light output module is used to provide the incident detection light beam after collimation and expansion.

[0049] The polarization control module is used to change the polarization state of the incident detection beam. The incident detection beam is converted into a second linearly polarized beam through a polarization beam splitter, and the second linearly polarized beam is converted into a third circularly polarized beam through a quarter wave plate.

[0050] The beam combining module is used to combine the first linearly polarized light beam and the third circularly polarized light beam into the same optical path.

[0051] The light scanning module is used to focus the combined first linearly polarized light beam and the third circularly polarized light beam onto the Chinese medicinal material sample of the object to be tested module, and change its incident position on the sample within a certain range of a designated area to perform scanning imaging.

[0052] The test object module is used to carry and move Chinese medicinal material samples.

[0053] The first linearly polarized beam is focused onto the Chinese herbal medicine sample and absorbed. The third circularly polarized beam is reflected by the sample and converted into a fourth circularly polarized beam with an opposite rotational direction. The fourth circularly polarized beam passes through the optical scanning module and is reflected by the dichroic mirror in the beam combining module. After passing through a quarter-wave plate, it is converted into a fifth linearly polarized beam with a polarization direction orthogonal to that of the second linearly polarized beam. The fifth linearly polarized beam is then reflected by the polarization beam splitter in the polarization control module and directed to the photodetection module.

[0054] The photoelectric detection module is used to receive the fifth linearly polarized light beam reflected by the polarization beam splitter and convert the optical signal into an electrical signal.

[0055] The data acquisition and image processing module converts the electrical signal into a digital signal and processes it to generate polarized photoacoustic images and quality identification results of the Chinese medicinal material samples.

[0056] Specifically, after the Chinese herbal medicine sample absorbs the pulse energy of the first linearly polarized light beam, it generates an initial photoacoustic pressure based on the photoacoustic effect. The refractive index of the sample changes due to the photoelastic effect, which in turn causes a change in the reflection intensity of the third circularly polarized light beam. Therefore, after passing through the Chinese herbal medicine sample, the third circularly polarized light beam carries a polarized photoacoustic signal and is reflected. The reflected light beam is called the fourth circularly polarized light beam, and its rotation direction is opposite to that of the third circularly polarized light beam. After passing through the optical scanning module, the fourth circularly polarized light beam is reflected by the dichroic mirror in the beam combining module. After passing through the quarter-wave plate, it is converted into a fifth linearly polarized light beam with a polarization direction orthogonal to that of the second linearly polarized light beam. It is then reflected by the polarization beam splitter to the photodetection module. In the photodetection module, the fifth linearly polarized light beam passes through a focusing lens and a filter and is transmitted to a photodetector. The photodetector converts the optical signal into an electrical signal. Finally, the electrical signal is converted into a digital signal and processed by the data acquisition and image processing module to generate a polarized photoacoustic image of the Chinese herbal medicine sample and a quality identification result.

[0057] Specifically, the excitation light output module includes a nanosecond pulse laser and a collimating beam expander, which is used to provide an incident excitation light beam, wherein the nanosecond pulse laser includes an ultraviolet laser, a visible light laser, and a near-infrared laser.

[0058] The polarization modulation module includes a polarizer and a half-wave plate, and is used to modulate the linear polarization direction of the incident excitation light beam to switch between 0°, 45°, 90° and 135°.

[0059] The detection light output module includes a 1310nm superluminescent diode and a collimating beam expander, and is used to provide an incident detection light beam.

[0060] The polarization control module includes a polarization beam splitter and a quarter wave plate, which is used to control the polarization state of the incident detection beam to transmit the incident detection beam to the dichroic mirror and reflect the reflected detection beam returned by the sample to the photoelectric detection module.

[0061] The beam combining module includes a dichroic mirror, which is used to combine the incident excitation light beam and the incident detection light beam into the same light path.

[0062] The optical scanning module includes a two-dimensional scanning galvanometer and a focusing objective lens, which is used to focus the incident excitation light beam and the incident detection light beam onto the Chinese medicinal material sample, and change the incident position on the sample within a certain range of a specified area to perform scanning imaging.

[0063] The test object module includes a three-dimensional movable sample stage for carrying and moving Chinese medicinal material samples.

[0064] The photoelectric detection module includes a filter, a focusing lens and a photoelectric detector, which is used to receive the reflected detection light beam carrying the polarized photoacoustic signal returned by the Chinese medicinal material sample and convert the optical signal into an electrical signal.

[0065] The data acquisition and image processing module, including a bandpass filter, a data acquisition card and computer equipment, is used to collect the signals output by the photoelectric detection module, convert the electrical signals into digital analog signals, and transmit them to the computer for data processing, imaging reconstruction and identification and classification.

[0066] Specifically, a nanosecond pulsed laser emits an incident excitation beam of ultraviolet and / or visible light and / or near-infrared light. This beam is collimated and expanded by a collimating beam expander of the corresponding wavelength. After passing through a polarizer, the incident excitation beam becomes linearly polarized light. A half-wave plate is used to change the linear polarization direction of the incident excitation beam. A 1310nm superluminescent diode emits an incident probe beam. After collimation and expansion by the collimating beam expander, the incident probe beam becomes linearly polarized light by a polarizing beam splitter. After passing through a quarter-wave plate, its polarization state is changed from linear polarization to circular polarization. A dichroic mirror transmits the incident excitation beam and reflects the incident probe beam into the same optical path. The combined incident excitation and probe beams are reflected by a scanning galvanometer into an achromatic objective lens and ultimately focused onto a Chinese medicinal material sample on a three-dimensional movable sample stage. After the Chinese medicinal material sample absorbs the energy of the incident excitation beam pulses of different linear polarization directions, the initial pressure changes due to the photoacoustic effect. This, in turn, causes a change in the refractive index due to the photoelastic effect, which in turn changes the reflectivity of the Chinese medicinal material sample to the incident probe beam. The reflected probe beam, after passing through the TCM sample, carries the polarized photoacoustic signal of the TCM sample, with a circular polarization direction opposite to that of the incident probe beam. After passing through the achromatic objective, scanning galvanometer, and dichroic mirror, the reflected probe beam reaches a quarter-wave plate, where it becomes linearly polarized light orthogonal to the polarization direction of the linearly polarized incident probe beam. This light is then reflected by a polarizing beam splitter and directed to a focusing lens. After being focused by the focusing lens, it passes through a filter and is ultimately received by a photodetector. The photodetector converts the optical signal into an electrical signal, which is then passed through a bandpass filter and a data acquisition card to a computer for data processing and image display.

[0067] Specific as Figure 2As shown in the figure, a nanosecond pulsed laser 1-1 emits an incident excitation beam of ultraviolet and / or visible light and / or near-infrared light. This beam is collimated and expanded by a collimating beam expander 1-2 of the corresponding wavelength. A polarizer 2-1 converts the incident excitation beam into linearly polarized light, and a half-wave plate 2-2 modulates the linear polarization direction of the incident excitation beam between 0°, 45°, 90°, and 135°. A 1310nm superluminescent diode 3-1 emits an incident probe beam, which is collimated and expanded by a collimating beam expander 3-2. After passing through a polarizing beam splitter 4-1, the incident probe beam becomes linearly polarized light. A quarter-wave plate 4-2 changes the polarization state of the incident probe beam from linear polarization to circular polarization. A dichroic mirror 5-1 transmits the incident excitation beam and reflects the incident probe beam back into the same optical path. The combined incident excitation and probe beams are reflected by a scanning galvanometer 6-1 into an achromatic objective lens 6-2, ultimately focusing onto a Chinese herbal medicine sample on a three-dimensional movable sample stage 7-1. After the Chinese herbal medicine sample absorbs the energy of the incident excitation beam pulses of different linear polarization directions, the initial pressure changes due to the photoacoustic effect. This, in turn, causes a change in the refractive index due to the photoelastic effect, which in turn changes the reflectivity of the Chinese herbal medicine sample to the incident probe beam. After passing through the Chinese herbal medicine sample, the reflected probe beam carries the Chinese herbal medicine's polarized photoacoustic signal, with a circular polarization direction opposite to that of the incident probe beam. After passing through the achromatic objective lens 6-2 and the scanning galvanometer 6-1, the reflected probe beam reaches the dichroic mirror 5-1. It is reflected by the dichroic mirror 5-1 and then onto the quarter-wave plate 4-2, becoming linearly polarized light orthogonal to the linear polarization direction of the incident probe beam. It is then reflected by the polarization beam splitter 4-1 and then onto the focusing lens 8-1. After being focused by the focusing lens 8-1, it passes through the filter 8-2 and is ultimately received by the photodetector 8-3. The photodetector 8-3 converts the optical signal into an electrical signal, which then passes through the bandpass filter 9-1 and the data acquisition card 9-2 and enters the computer 9-3 for data processing and image display.

[0068] The initial pressure p generated by the photoacoustic effect after the sample absorbs the incident excitation beam pulse energy can be expressed as:

[0069] p=Γη th μF (1)

[0070] Where Γ is the Grüneisen parameter, η th is the light-to-heat conversion efficiency, μ is the optical absorption coefficient, and F is the luminous flux.

[0071] The Chinese herbal medicine sample has anisotropy, so the optical absorption coefficient μ changes with the polarization direction of the incident excitation beam. When the anisotropic Chinese medicinal materials interact with the target area, the optical absorption coefficient is expressed as:

[0072]

[0073] Using μ || 、μ ⊥ Represents the optical absorption coefficient in the parallel and perpendicular directions respectively. Define the optical axis direction of Chinese medicinal materials The angle between the incident excitation beam and the linear polarization direction φ is θ, that is, Therefore, the initial photoacoustic pressure p generated by the anisotropic Chinese medicinal material sample under the excitation of the linearly polarized incident excitation beam is related to θ and can be expressed as:

[0074]

[0075] Assuming that the refractive index of the Chinese herbal medicine sample is n2, after being modulated by the initial photoacoustic pressure p, a refractive index perturbation δn2 will be generated at the interface with the non-absorbing medium (such as air) with a refractive index of n1. According to the photoelastic effect, this perturbation is expressed as:

[0076]

[0077] Where ε is the elastic coefficient, ρ is the material density, ν s is the sound velocity of the medium. Then, the change in the refractive index causes the change in the reflectivity of the incident probe beam to be:

[0078]

[0079] If the sample refractive index n2 is a real number and the first-order Taylor expansion approximation is used, the reflectivity change caused by the initial photoacoustic pressure can be expressed as:

[0080]

[0081] The polarized photoacoustic signal of Chinese herbal medicine is the change in the intensity of the reflected detection beam caused by the photoelastic effect after the sample absorbs the pulse energy of the linearly polarized incident excitation beam. Therefore, the polarized photoacoustic signal of Chinese herbal medicine satisfies the following requirements:

[0082]

[0083] The amplitude of the polarized photoacoustic signal of the Chinese medicinal materials under the excitation of the incident excitation beam with polarization directions of 0°, 45°, 90° and 135° is defined as I H , I P , I V , I M These amplitudes are used to quantify the degree of anisotropy (DOA) of the Chinese herbal medicine samples, and the expression is:

[0084]

[0085] According to this formula, the polarized photoacoustic signals of Chinese medicinal materials obtained after excitation by incident excitation beams with different polarization directions are processed, and the DOA value of each pixel point is calculated to quantify the anisotropy of the Chinese medicinal materials samples.

[0086] In addition, the present invention provides a non-contact polarization photoacoustic detection method for quality identification of Chinese medicinal materials, such as Figure 3 As shown, the steps include:

[0087] Step S1: Select a Chinese medicinal material sample and place it on the sample table of the test object module.

[0088] Step S2: configure the excitation light source in the excitation light output module and the detection light source in the detection light output module, adjust the optical path so that the incident excitation light beam and the incident detection light beam are combined to achieve coaxial transmission and confocus to the same position of the Chinese medicinal material sample through the optical scanning module, and synchronously configure the optical scanning module and the photoelectric detection module to ensure accurate excitation and collection of the polarized photoacoustic signal of the corresponding area.

[0089] Step S3, adjust the polarization modulation module to switch the linear polarization direction of the incident excitation beam between 0°, 45°, 90° and 135°, and obtain the polarized photoacoustic signals of the Chinese medicinal materials in the corresponding areas under the four linear polarization directions of the incident excitation beam one by one.

[0090] Step S4: importing the collected polarized photoacoustic signals of the Chinese medicinal materials into MATLAB for data processing to generate polarized photoacoustic images of the Chinese medicinal materials.

[0091] Step S5: Use a deep learning network to segment and classify the polarized photoacoustic image of the Chinese medicinal materials to identify the variety and origin of the Chinese medicinal materials.

[0092] Step S6: output the Chinese medicinal material quality identification result.

[0093] Figure 4 This is the result of anisotropic imaging of Sinomene Herba Cibotii slices using the non-contact polarization photoacoustic detection device of the present invention. By using the anisotropy obtained from processing the polarized photoacoustic signal from the Chinese medicinal material as a contrast parameter, the present invention not only clearly characterizes the microstructure of Sinomene Herba Cibotii, such as rays and xylem vessels, but also effectively captures anisotropic information within the plant.

[0094] Figure 5 This is the result of using the non-contact polarization photoacoustic detection method of the present invention to distinguish the origin of Sinomene Herba Sinensis. Non-contact polarization photoacoustic imaging results were collected for Sinomene Herba Sinensis slices from Guangxi, Henan, Hubei, and Yunnan. Using a preliminary developed algorithm for identifying the origin of Chinese medicinal materials, the prediction accuracy reached 91.6%.

[0095] It should also be noted that, in this specification, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or apparatus comprising the element.

[0096] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

[0097] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

[0098] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A non-contact polarization photoacoustic detection device for identifying the quality of traditional Chinese medicine, characterized in that: The detection device includes the following modules: The excitation light output module is used to provide the incident excitation light beam after collimation and expansion; A polarization modulation module, configured to modulate an incident excitation light beam into a first linearly polarized light beam; A detection light output module is used to provide a collimated and expanded incident detection light beam; a polarization control module, configured to change the polarization state of the incident probe beam to obtain a third circularly polarized beam; a beam combining module, configured to combine the first linearly polarized light beam and the third circularly polarized light beam into the same optical path; The optical scanning module is used to focus the combined first linearly polarized light beam and the third circularly polarized light beam onto the Chinese medicinal material sample in the object to be tested module, and change its incident position on the sample within a certain range in a designated area to perform scanning imaging; The object to be tested module is used to carry and move the Chinese medicinal material sample; the first linearly polarized light beam is focused on the Chinese medicinal material sample and absorbed, the third circularly polarized light beam is reflected after passing through the Chinese medicinal material sample and becomes a fourth circularly polarized light beam with the opposite rotation direction; the fourth circularly polarized light beam passes through the light scanning module, is reflected by the beam combining module, and is reflected by the polarization control module to the photoelectric detection module; Photoelectric detection module, converting optical signals into electrical signals; The data acquisition and image processing module converts the electrical signal into a digital signal and processes it to generate polarized photoacoustic images and quality identification results of the Chinese medicinal material samples.

2. According to the non-contact polarization photoacoustic detection device of claim 1, the polarization control module includes a polarization beam splitter and a quarter-wave plate, which are used to change the polarization state of the incident detection beam, and the incident detection beam is converted into a second linearly polarized beam by the polarization beam splitter, and the second linearly polarized beam is converted into a third circularly polarized beam by the quarter-wave plate.

3. According to the non-contact polarization photoacoustic detection device according to claim 1, the fourth circularly polarized light beam is reflected by the dichroic mirror in the beam combining module after passing through the optical scanning module, and is converted into a fifth linearly polarized light beam whose polarization direction is orthogonal to that of the second linearly polarized light beam after passing through the quarter-wave plate; the fifth linearly polarized light beam is reflected to the photoelectric detection module by the polarization beam splitter in the polarization control module. 4 . The non-contact polarization photoacoustic detection device according to claim 3 , wherein the photoelectric detection module comprises a filter, a focusing lens and a photodetector, and is configured to receive the fifth linearly polarized light beam reflected by the polarization beam splitter and convert the optical signal into an electrical signal. 5 . The non-contact polarization photoacoustic detection device according to claim 1 , wherein the polarization modulation module comprises a polarizer and a half-wave plate, and is configured to modulate the linear polarization direction of the incident excitation light beam to switch between 0°, 45°, 90°, and 135°.

6. The non-contact polarization photoacoustic detection device according to claim 2, wherein the third circularly polarized light beam carries a polarized photoacoustic signal and is reflected by the Chinese medicinal material sample to obtain a fourth circularly polarized light beam, the fourth circularly polarized light beam is reflected by the dichroic mirror in the beam combining module after passing through the optical scanning module, converted into a fifth linearly polarized light beam after passing through a quarter-wave plate, and then reflected by the polarization beam splitter to the photoelectric detection module. 7 . The non-contact polarized photoacoustic detection device according to claim 6 , wherein the fourth circularly polarized light beam has a rotation direction opposite to that of the third circularly polarized light beam; and the fifth linearly polarized light beam and the second linearly polarized light beam have polarization directions orthogonal to each other.

8. A non-contact polarization photoacoustic detection device for identifying the quality of Chinese medicinal materials, characterized in that: The detection device comprises the following structure: A nanosecond pulse laser (1-1) emits an ultraviolet and / or visible light and / or near-infrared incident excitation beam, which is collimated and expanded by a first collimating beam expander (1-2) of corresponding wavelength. A polarizer (2-1) is used to convert the incident excitation beam into linearly polarized light. A half-wave plate (2-2) modulates the linear polarization direction of the incident excitation beam to switch between 0°, 45°, 90°, and 135°. The superluminescent diode (3-1) emits an incident detection beam, which is collimated and expanded by a second collimating beam expander (3-2), and then becomes linearly polarized light after passing through a polarization beam splitter (4-1). The quarter-wave plate (4-2) changes the polarization state of the incident detection beam from linear polarization to circular polarization. The dichroic mirror (5-1) transmits the incident excitation beam and reflects the incident detection beam to the same optical path; The combined incident excitation beam and incident detection beam are reflected by the scanning galvanometer (6-1) into the achromatic objective lens (6-2), and are finally focused onto the Chinese medicinal material sample on the three-dimensional movable sample stage (7-1) to obtain a reflected detection beam after passing through the Chinese medicinal material sample; The reflected detection beam passes through the achromatic objective lens (6-2) and the scanning galvanometer (6-1) and reaches the dichroic mirror (5-1), is reflected by the dichroic mirror (5-1) to the quarter-wave plate (4-2), and becomes linearly polarized light orthogonal to the linear polarization direction of the incident detection beam. It is reflected by the polarization beam splitter (4-1) to the focusing lens (8-1), is focused by the focusing lens (8-1), passes through the filter (8-2), and is finally received by the photodetector (8-3); the photodetector (8-3) converts the optical signal into an electrical signal, which passes through the bandpass filter (9-1) and the data acquisition card (9-2) and enters the computer (9-3) for data processing and image display.

9. A non-contact polarization photoacoustic detection method for identifying the quality of traditional Chinese medicine, the detection method being implemented based on the apparatus of claim 1, characterized in that: The detection method specifically comprises the following steps: S1. Select a Chinese herbal medicine sample and place it on the sample table of the test module; S2. Configure the excitation light source in the excitation light output module and the detection light source in the detection light output module, adjust the optical path so that the incident excitation light beam and the incident detection light beam are combined and coaxially transmitted and confocused to the same position of the Chinese medicinal material sample through the optical scanning module, and synchronously configure the optical scanning module and the photoelectric detection module to ensure accurate excitation and acquisition of polarized photoacoustic signals in the corresponding area; S3, adjusting the polarization modulation module to switch the linear polarization direction of the incident excitation beam between 0°, 45°, 90°, and 135°, and acquiring polarized photoacoustic signals of the Chinese medicinal materials in the corresponding areas under the four linear polarization directions of the incident excitation beam one by one; S4, processing the collected polarization photoacoustic signals of the Chinese medicinal materials to generate polarization photoacoustic images of the Chinese medicinal materials; S5. Segment and classify the polarized photoacoustic images of Chinese medicinal materials to identify the species and origin of the Chinese medicinal materials; S6. Output the quality identification results of Chinese medicinal materials. 10 . The non-contact polarization photoacoustic detection method according to claim 9 , wherein in step S5 , a deep learning network is used to perform image segmentation and classification on the polarization photoacoustic image of the Chinese medicinal materials.

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