Non-contact polarized light acoustic detection device and method for identifying quality of traditional Chinese medicinal materials

Abstract

The invention provides a non-contact polarized light acoustic detection device and method for identifying the quality of traditional Chinese medicinal materials. According to the device, a traditional Chinese medicinal material sample is excited by using a polarization-modulated pulse excitation light beam, and refractive index change caused by photoacoustic initial pressure generated when the sample absorbs excitation light pulse energy is measured by using a continuous wave detection light beam confocal with the excitation light beam. By detecting the reflection component of the detection light beam, the device can obtain anisotropic optical absorption information of the traditional Chinese medicinal materials. The traditional Chinese medicinal material polarized light acoustic image and the anisotropic characteristic information thereof are obtained by using the non-contact polarized light acoustic detection device and method, the quality of the traditional Chinese medicinal material can be identified, the traditional Chinese medicinal material sample is not damaged in the whole process, and non-contact in-situ detection is realized.

Description

Technical Field

[0001] The invention belongs to the field of nondestructive 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, Chinese medicine plays a vital role in disease treatment and health care. As the material basis of Chinese medicine, the quality of Chinese medicinal materials is directly related to the safety and efficacy of clinical medication. However, Chinese medicinal materials are of various types, with a wide range of sources, scattered production areas, and different processing and storage conditions, resulting in uneven quality of medicinal materials. Therefore, in order to ensure the quality and safety of Chinese medicinal materials, it is crucial to take effective quality identification and control measures.

[0003] At present, the identification methods of Chinese herbal medicines mainly include property identification, microscopic identification and physical and chemical identification. Property identification mainly judges the quality of the herbal medicine by observing its morphology, color and taste. This method is highly dependent on the experience of the appraiser and can quickly make preliminary identification of Chinese herbal medicines, but it is highly subjective and lacks objective and unified standards, resulting in low efficiency and low accuracy, making it difficult to effectively apply in large-scale production. Microscopic identification relies on optical microscopy for standard testing, but its application range is limited. It is only applicable to the imaging of stained thin sections and powders, and lacks intelligent analysis methods, which is not suitable for quantitative analysis of complex components. Physical and chemical identification includes chromatography, mass spectrometry, spectroscopy and other detection methods. By obtaining the characteristic spectrum data of Chinese herbal medicines, the authenticity identification and quality detection of Chinese herbal medicines can be realized. Among them, chromatography can quantitatively analyze complex Chinese herbal medicine components, but time-consuming and complex pretreatment steps are required before sample analysis. This process may destroy the distribution information of compounds in the internal tissues of the sample, and the equipment and operation costs are high, requiring professional technical support. Mass spectrometry has high sensitivity and high resolution, and is suitable for analyzing complex mixtures; however, the sample preparation and operation process is 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 technology has the advantages of convenient testing and rapid analysis, but its sensitivity is relatively low and it has difficulties in distinguishing similar substances. Fluorescence spectroscopy technology 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 technology 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] The existing testing methods for Chinese medicinal materials cannot fully meet the rapid development needs of the industry. Therefore, how to achieve fast, 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 microscopic scale, the optical absorption difference is detected by an all-optical polarization photoacoustic system to achieve non-contact in-situ detection of the internal structure of Chinese medicinal materials and their anisotropic characteristics. The data is processed and analyzed in combination with a deep learning algorithm to achieve rapid and non-destructive quality identification of Chinese medicinal materials.

[0007] The invention provides a non-contact polarization photoacoustic detection device for identifying the quality of traditional Chinese medicine. The device comprises: an excitation light emitting module, a polarization modulation module, a detection light emitting 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 an 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 linear polarized light beam whose polarization direction is 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 linear polarized beam through a polarization beam splitter, and the second linear 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 light path.

[0013] The light scanning module is used to focus the combined first linear polarized light beam and the third circular 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 linear polarized light beam is focused on the Chinese herbal medicine sample and absorbed, and the third circular polarized light beam is reflected after passing through the Chinese herbal medicine sample and becomes a fourth circular polarized light beam with the opposite rotation direction. The fourth circular polarized light beam passes through the optical scanning module and is reflected by the dichroic mirror in the beam combining module. After passing through the quarter wave plate, it is converted into a fifth linear polarized light beam orthogonal to the polarization direction of the second linear polarized light beam. The fifth linear polarized light beam is reflected to the photoelectric detection module by the polarization beam splitter in the polarization control module.

[0016] The photoelectric detection module is used to receive the fifth linear 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 the polarized photoacoustic image 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. Due to the photoelastic effect, the refractive index of the sample changes, which in turn causes a change in the reflection intensity of the third circularly polarized light beam. Therefore, the third circularly polarized light beam is reflected by the Chinese herbal medicine sample with a polarized photoacoustic signal, and 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, and is converted into a fifth linearly polarized light beam orthogonal to the polarization direction of the second linearly polarized light beam after passing through a quarter-wave plate, and then is reflected to the photoelectric detection module by the polarization beam splitter. In the photoelectric detection module, the fifth linearly polarized light beam is transmitted to the photodetector after passing through a focusing lens and a filter. The photodetector converts the optical signal into an electrical signal, and finally converts the electrical signal into a digital signal and processes it through the data acquisition and image processing module to generate a polarized photoacoustic image and quality identification result of the Chinese herbal medicine sample.

[0019] Specifically, the excitation light output module includes a nanosecond pulse laser and a collimating beam expander, which are 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 comprises 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 comprises 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 designated area to perform scanning imaging.

[0025] The test object module includes a three-dimensional movable sample stage for carrying and moving the 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 a computer device, 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 pulse laser emits an incident excitation beam of ultraviolet and / or visible light and / or near-infrared, which 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, and a half-wave plate is used to change the linear polarization direction of the incident excitation beam. A 1310nm superluminescent diode emits an incident detection beam, which is collimated and expanded by a collimating beam expander, and then becomes linearly polarized light through a polarizing beam splitter, and then changes its polarization state from linear polarization to circular polarization after passing through a quarter-wave plate. A dichroic mirror 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 a scanning galvanometer into an achromatic objective lens, and finally focused on a Chinese herbal medicine sample on a three-dimensional moving sample stage. After the Chinese herbal medicine sample absorbs the pulse energy of the incident excitation beam of different linear polarization directions, the initial pressure changes due to the photoacoustic effect, and the refractive index changes based on the photoelastic effect, which in turn causes the reflectivity of the Chinese herbal medicine sample to the incident detection beam to change. The reflected detection beam after passing through the Chinese herbal medicine sample carries the polarized photoacoustic signal of the Chinese herbal medicine, and its circular polarization rotation direction is opposite to that of the incident detection beam. After being reflected by the achromatic objective, scanning galvanometer, and dichroic mirror, the reflected detection beam reaches the quarter-wave plate and becomes a linearly polarized light orthogonal to the polarization direction of the linearly polarized incident detection beam. It is reflected by the polarization beam splitter to the focusing lens, focused by the focusing lens, and then passes through the filter and is finally received by the photodetector. The photodetector converts the optical signal into an electrical signal, which enters the computer through a bandpass filter and a data acquisition card 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 cofocus 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 to switch the linear polarization direction of the incident excitation light beam between 0°, 45°, 90° and 135°, and obtain polarized photoacoustic signals of the Chinese medicinal materials in the corresponding areas under the four linear polarization directions of the incident excitation light 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 the varieties and origins of Chinese medicinal materials.

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

[0036] Based on the macroscopic anisotropy caused by the orientation and arrangement differences of different tissue structures inside Chinese medicinal materials at the microscopic scale, the present invention develops a non-contact polarization photoacoustic detection device for rapid non-destructive detection of the structural characteristics of Chinese medicinal materials. By detecting the optical absorption anisotropy of Chinese medicinal materials, its internal structural information, including tissue characteristics, microstructure and degree of dryness, etc., can be revealed. This information can provide an important basis for the quality control and identification of Chinese medicinal materials. The non-contact polarization photoacoustic detection device uses an all-optical system of polarization-modulated pulse light excitation and continuous light detection to image the anisotropic structure of Chinese medicinal materials. The sample is excited by a polarization-modulated pulse excitation beam, and a continuous wave detection beam confocal with the excitation beam is used to measure the local refractive index change caused by the photoacoustic initial pressure generated by the sample absorbing the energy of the excitation light pulse. The reflected component of the detection beam contains the anisotropic optical absorption information of the sample. The combined use of two beams of light overcomes the need for coupling agents in traditional photoacoustic systems and realizes true non-contact imaging. The present invention only relies 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 the in situ nature of the detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative labor.

[0038] Figure 1 The present invention is a schematic diagram of the structure 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 This is the experimental result diagram.

[0042] Figure 5 This is a diagram showing the results of the regional classification of Caulis Sinomenii in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0043] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

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

[0045] The present invention provides a non-contact polarization photoacoustic detection device for identifying the quality of traditional Chinese medicine. Figure 1 The device includes: an excitation light emitting module, a polarization modulation module, a detection light emitting 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 an 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 linear polarized light beam whose polarization direction is 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 linear polarized beam through a polarization beam splitter, and the second linear 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 light path.

[0051] The light scanning module is used to focus the combined first linear polarized light beam and the third circular 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 linear polarized light beam is focused on the Chinese herbal medicine sample and absorbed, and the third circular polarized light beam is reflected after passing through the Chinese herbal medicine sample and becomes a fourth circular polarized light beam with the opposite rotation direction. The fourth circular polarized light beam passes through the optical scanning module and is reflected by the dichroic mirror in the beam combining module. After passing through the quarter wave plate, it is converted into a fifth linear polarized light beam orthogonal to the polarization direction of the second linear polarized light beam. The fifth linear polarized light beam is reflected to the photoelectric detection module by the polarization beam splitter in the polarization control module.

[0054] The photoelectric detection module is used to receive the fifth linear 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 the polarized photoacoustic image 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. Due to the photoelastic effect, the refractive index of the sample changes, which in turn causes a change in the reflection intensity of the third circularly polarized light beam. Therefore, the third circularly polarized light beam is reflected by the Chinese herbal medicine sample with a polarized photoacoustic signal, and 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, and is converted into a fifth linearly polarized light beam orthogonal to the polarization direction of the second linearly polarized light beam after passing through a quarter-wave plate, and then is reflected to the photoelectric detection module by the polarization beam splitter. In the photoelectric detection module, the fifth linearly polarized light beam is transmitted to the photodetector after passing through a focusing lens and a filter. The photodetector converts the optical signal into an electrical signal, and finally converts the electrical signal into a digital signal and processes it through the data acquisition and image processing module to generate a polarized photoacoustic image and quality identification result of the Chinese herbal medicine sample.

[0057] Specifically, the excitation light output module includes a nanosecond pulse laser and a collimating beam expander, which are 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 comprises 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 comprises 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 designated area to perform scanning imaging.

[0063] The test object module includes a three-dimensional movable sample stage for carrying and moving the 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 a computer device, 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 pulse laser emits an incident excitation beam of ultraviolet and / or visible light and / or near-infrared, which 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, and a half-wave plate is used to change the linear polarization direction of the incident excitation beam. A 1310nm superluminescent diode emits an incident detection beam, which is collimated and expanded by a collimating beam expander, and then becomes linearly polarized light through a polarizing beam splitter, and then changes its polarization state from linear polarization to circular polarization after passing through a quarter-wave plate. A dichroic mirror 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 a scanning galvanometer into an achromatic objective lens, and finally focused on a Chinese herbal medicine sample on a three-dimensional moving sample stage. After the Chinese herbal medicine sample absorbs the pulse energy of the incident excitation beam of different linear polarization directions, the initial pressure changes due to the photoacoustic effect, and the refractive index changes based on the photoelastic effect, which in turn causes the reflectivity of the Chinese herbal medicine sample to the incident detection beam to change. The reflected detection beam after passing through the Chinese herbal medicine sample carries the polarized photoacoustic signal of the Chinese herbal medicine, and its circular polarization rotation direction is opposite to that of the incident detection beam. After being reflected by the achromatic objective, scanning galvanometer, and dichroic mirror, the reflected detection beam reaches the quarter-wave plate and becomes a linearly polarized light orthogonal to the polarization direction of the linearly polarized incident detection beam. It is reflected by the polarization beam splitter to the focusing lens, focused by the focusing lens, and then passes through the filter and is finally received by the photodetector. The photodetector converts the optical signal into an electrical signal, which enters the computer through a bandpass filter and a data acquisition card for data processing and image display.

[0067] Specific as Figure 2As shown. The 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 collimating beam expander 1-2 of the corresponding wavelength. The polarizer 2-1 is used to convert the incident excitation beam into linearly polarized light. The half-wave plate 2-2 modulates the linear polarization direction of the incident excitation beam to switch between 0°, 45°, 90° and 135°. The 1310nm superluminescent diode 3-1 emits an incident detection beam, which is collimated and expanded by the collimating beam expander 3-2. After passing through the polarization beam splitter 4-1, the incident detection beam is converted into linearly polarized light. 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 into the achromatic objective lens 6-2 through the scanning galvanometer 6-1, and finally focused on the Chinese herbal medicine sample on the three-dimensional movable sample stage 7-1. After the Chinese herbal medicine sample absorbs the pulse energy of the incident excitation beam with different linear polarization directions, the initial pressure changes due to the photoacoustic effect, and the refractive index changes based on the photoelastic effect, which in turn causes the reflectivity of the Chinese herbal medicine sample to the incident detection beam to change. The reflected detection beam after passing through the Chinese herbal medicine sample carries the polarized photoacoustic signal of the Chinese herbal medicine, and its circular polarization rotation direction is opposite to that of the incident detection beam. The reflected detection beam reaches the dichroic mirror 5-1 after passing through the achromatic objective lens 6-2 and the scanning galvanometer 6-1, and is reflected by the dichroic mirror 5-1 to the quarter-wave plate 4-2, becoming a linear polarized light orthogonal to the linear polarization direction of the incident detection beam, and is reflected by the polarization beam splitter 4-1 to the focusing lens 8-1, and after being focused by the focusing lens 8-1, it 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 enters the computer 9-3 through the bandpass filter 9-1 and the data acquisition card 9-2 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 photothermal conversion efficiency, μ is the optical absorption coefficient, and F is the luminous flux.

[0071] The Chinese herbal medicine sample is anisotropic, 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 disturbance 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, the disturbance is expressed as:

[0076]

[0077] Where ε is the elastic coefficient, ρ is the material density, ν s is the medium sound speed. Then, the change in refractive index causes the change in 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:

[0082]

[0083] The amplitude of polarized photoacoustic signal of Chinese herbal medicine under the excitation of 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 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 light beams in 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 herbal medicines, 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 polarized photoacoustic signals in the corresponding area.

[0089] Step S3, adjusting the polarization modulation module to switch the linear polarization direction of the incident excitation light 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 light 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, using a deep learning network to segment and classify the polarized photoacoustic image of the Chinese medicinal materials, and identify the variety and origin of the Chinese medicinal materials.

[0092] Step S6, outputting the Chinese medicinal material quality identification result.

[0093] Figure 4 This is the result of anisotropic imaging of Caulis Sinomenii slices using the non-contact polarization photoacoustic detection device of the present invention. By using the anisotropy obtained by processing the polarization photoacoustic signal of the Chinese herbal medicine as a contrast parameter, the present invention can not only clearly characterize the microstructure of Caulis Sinomenii, such as rays, xylem vessels, etc., but also effectively obtain the anisotropy information inside Caulis Sinomenii.

[0094] Figure 5 The results of using the non-contact polarization photoacoustic detection method of the present invention to classify the origin of Caulis Sinensis Chinese herbal medicine. The non-contact polarization photoacoustic imaging results of Caulis Sinensis Chinese herbal medicine pieces from Guangxi, Henan, Hubei and Yunnan were collected, and the prediction accuracy reached 91.6% using the initially developed Chinese herbal medicine origin identification algorithm.

[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 device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0096] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be 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 will not be limited to the embodiments shown herein, but rather 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 equivalent replacement methods and are included in the protection scope 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 the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A non-contact polarization photoacoustic detection device for quality identification of traditional Chinese medicine, characterized in that: The detection device comprises the following modules: An excitation light output module, used for providing an incident excitation light beam after collimation and expansion; A polarization modulation module, used for modulating an incident excitation light beam to form a first linearly polarized light beam; A detection light output module, used for providing a collimated and expanded incident detection light beam; A polarization control module, used for changing the polarization state of the incident detection beam to obtain a third circularly polarized beam; A beam combining module, used for combining the first linearly polarized light beam and the third circularly polarized light beam into the same light path; The optical scanning module is used to focus the combined first linear polarized light beam and third circular polarized light beam onto the Chinese medicinal material sample of the object to be tested module, and change the incident position on the sample within a certain range of the 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 linear polarized light beam is focused on the Chinese medicinal material sample and then absorbed; the third circular polarized light beam is reflected after passing through the Chinese medicinal material sample and becomes a fourth circular polarized light beam with the opposite rotation direction; the fourth circular polarized light beam passes through the light scanning module and then is reflected by the beam combining module and then passes through the polarization control module and then is reflected 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 the polarized photoacoustic image and quality identification results of the Chinese medicinal material samples.

2. According to the non-contact polarization photoacoustic detection device according to 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 linear polarized beam through the polarization beam splitter, and the second linear polarized beam is converted into a third circularly polarized beam through 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 light scanning module, and is converted into a fifth linearly polarized light beam whose polarization direction is orthogonal to the second linearly polarized light beam after passing through a 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 1 , 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, which are used to modulate the linear polarization direction of the incident excitation light beam to switch between 0°, 45°, 90° and 135°.

6. According to the non-contact polarization photoacoustic detection device of claim 2, the third circularly polarized light beam carries the polarized photoacoustic signal after being 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, and is converted into a fifth linearly polarized light beam after passing through a quarter wave plate, and then is reflected by the polarization beam splitter to the photoelectric detection module.

7. According to the non-contact polarization photoacoustic detection device of claim 6, the fourth circularly polarized light beam has a rotation direction opposite to that of the third circularly polarized light beam; and the polarization directions of the fifth linearly polarized light beam and the second linearly polarized light beam are orthogonal to each other.

8. A non-contact polarization photoacoustic detection device for quality identification of traditional Chinese medicine, 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 light beam, which is collimated and expanded by a collimating beam expander (1-2) of a corresponding wavelength. A polarizer (2-1) is used to convert the incident excitation light beam into linearly polarized light. A half-wave plate (2-2) modulates the linear polarization direction of the incident excitation light 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 collimating beam expander (3-2), and becomes linearly polarized light after passing through a polarizing 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 light beam and reflects the incident detection light beam to the same optical path; The combined incident excitation light beam and incident detection light beam are reflected by the scanning galvanometer (6-1) into the achromatic objective lens (6-2), and finally focused onto the Chinese medicinal material sample on the three-dimensional movable sample stage (7-1) to obtain the reflected detection light beam after passing through the Chinese medicinal material sample; The reflected detection light 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), becomes linear polarized light orthogonal to the linear polarization direction of the incident detection light beam, 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 photoelectric detector (8-3); the photoelectric detector (8-3) converts the optical signal into an electrical signal, which enters the computer (9-3) through the bandpass filter (9-1) and the data acquisition card (9-2) for data processing and image display.

9. A non-contact polarization photoacoustic detection method for quality identification of traditional Chinese medicine, the detection method is implemented based on the device in claim 1, characterized in that: The detection method specifically comprises the following steps: S1. Select a Chinese medicinal material sample and place it on the sample table of the test object 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 to achieve coaxial transmission and cofocus 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; S3, adjusting the polarization modulation module to switch the linear polarization direction of the incident excitation light beam between 0°, 45°, 90° and 135°, and obtaining polarized photoacoustic signals of the Chinese medicinal materials in the corresponding areas under the four linear polarization directions of the incident excitation light beam one by one; S4, performing data processing on the collected polarized photoacoustic signals of the Chinese medicinal materials to generate polarized photoacoustic images of the Chinese medicinal materials; S5. Segment and classify the polarized photoacoustic images of Chinese medicinal materials to identify the varieties and origins 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 traditional Chinese medicine.

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