Real-time detection device and method for particles influencing water Raman spectrum in suspension droplets

Abstract

The invention relates to a real-time detection device and method for particles influencing a water Raman spectrum in suspension droplets, and the device comprises a constant temperature test box which is used for placing the suspension droplets and receiving detection laser; the laser receiving unit is used for receiving scattering echo signals generated by the particles influencing the water Raman spectrum; the light splitting unit is used for splitting the scattered echo signals into scattered echo signals under a first specific detection wavelength and a second specific detection wavelength; the laser detection unit comprises a first laser detection assembly used for detecting a scattering echo signal under a first specific detection wavelength and a second laser detection assembly used for detecting a scattering echo signal under a second specific detection wavelength; and the data processing unit is used for obtaining the concentration value of the particles influencing the water Raman spectrum according to signals obtained by the first laser detection assembly and the second laser detection assembly. On the basis of the laser Raman spectrum and in combination with the laser radar technology, real-time detection of the concentration of the particles influencing the water Raman spectrum in the suspension droplets is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser radar, and in particular relates to a real-time detection device and method for particles in suspended droplets that affect the Raman spectrum of water. Background Art

[0002] Chloride ions are widely distributed in nature. Almost all natural water contains chloride ions, mainly in the form of calcium, magnesium and sodium salts. Salt combines with suspended water droplets in the air to produce chloride ions that can destroy the passivation film on the metal surface and promote the electrochemical corrosion process. Industrial equipment and mechanical parts are more susceptible to corrosion in a high concentration of chloride ions, increasing maintenance costs; metal particles produced during the corrosion process may pollute soil and water sources and affect the ecosystem; damage caused by corrosion may increase the economic burden on enterprises and society. High concentrations of chloride ions may have a negative impact on human health. By monitoring the concentration of chloride ions in the air, the degree of air pollution can be assessed, especially in areas related to salt spray, industrial pollution and traffic emissions. Usually, the detection method of chloride ions in the air is mainly based on contact measurement and non-real-time measurement methods such as ion chromatography and electrochemical method, which do not meet the current detection needs. Similarly, the detection of other particles that affect the Raman spectrum of water does not meet the current detection needs.

[0003] According to actual needs, it is necessary to design a sensor that can perform non-invasive real-time measurement of particles affecting water Raman spectroscopy in a closed container. Specific requirements include: a. Non-contact detection through the surface of the container; b. Measurement in a gas state, with the sample in the form of atomized droplets; c. High measurement accuracy requirements, able to accurately detect particles affecting water Raman spectroscopy in the container. Summary of the invention

[0004] In order to solve the above technical problems and provide hardware support for solving the above problems, the present invention proposes a real-time detection device and method for particles affecting water Raman in suspended droplets. The specific technical solution is as follows:

[0005] A real-time detection device for particles in a suspended droplet that affect the Raman spectrum of water includes:

[0006] A constant temperature test box, used for placing the suspended droplets and receiving the detection laser;

[0007] A laser receiving unit, used for receiving scattered echo signals generated by the particles affecting the water Raman spectrum;

[0008] A light splitting unit, used for splitting the scattered echo signal into scattered echo signals at a first specific detection wavelength and a second specific detection wavelength;

[0009] A laser detection unit, comprising a first laser detection component for detecting a scattered echo signal at a first specific detection wavelength, and a second laser detection component for detecting a scattered echo signal at a second specific detection wavelength;

[0010] The device also includes a data processing unit, which is used to obtain the concentration value of the particles affecting the water Raman spectrum according to the signals obtained by the first laser detection component and the second laser detection component.

[0011] Furthermore, it also includes a detection laser generating unit, which is used to generate a detection laser for detecting the particles affecting the water Raman spectrum; the detection laser generator includes:

[0012] A laser, used for emitting fundamental frequency laser light to the particles affecting the water Raman spectrum being detected;

[0013] The emission optical path is used to change the wavelength of the fundamental frequency laser to obtain output light of a set wavelength.

[0014] Furthermore, the emission optical path includes a frequency doubling crystal and a frequency tripling crystal which are arranged in sequence.

[0015] Furthermore, the first laser detection component includes a first narrowband filter and a first laser detector APD1 arranged in sequence along the optical path, and the second laser detection component includes a second narrowband filter and a second laser detector APD2 arranged in sequence along the optical path; the first narrowband filter and the second narrowband filter are used to filter out interference light.

[0016] Furthermore, the bandwidths of the first narrowband filter and the second narrowband filter do not exceed half of the interval between the first specific detection wavelength and the second specific detection wavelength.

[0017] The present application also provides another inventive concept, a real-time detection method of particles in a suspended droplet that affect the Raman spectrum of water, comprising:

[0018] After emitting a single-wavelength detection laser into a constant temperature test box containing suspended droplets, a scattered echo signal at a first specific detection wavelength and a scattered echo signal at a second specific detection wavelength are obtained;

[0019] Acquire a first ratio of the scattered echo signal at the first specific detection wavelength to the scattered echo signal at the second specific detection wavelength, and acquire a second ratio of the Raman scattering cross section of water at the first specific detection wavelength to the Raman scattering cross section of water at the second specific detection wavelength;

[0020] Based on the linear function relationship between the first ratio and the second ratio, combined with the Raman scattering cross section of water at a fixed detection wavelength and the concentration function relationship of the particles affecting the Raman spectrum of water, the concentration value of the particles affecting the Raman spectrum of water is obtained.

[0021] Furthermore, the step of acquiring the scattered echo signal at the first specific detection wavelength and the scattered echo signal at the second specific detection wavelength includes:

[0022] The scattered echo signal at the first specific detection wavelength and the scattered echo signal at the second specific detection wavelength are acquired by time-division differential detection or simultaneous detection.

[0023] Furthermore, before acquiring the scattered echo signal at the first specific detection wavelength and the scattered echo signal at the second specific detection wavelength, the method further includes:

[0024] Obtaining Raman spectra of solutions corresponding to different concentrations of the particles that affect the water Raman spectrum;

[0025] In the Raman spectrum, two wavelengths that are most affected by the solution corresponding to the particle concentration affecting the water Raman spectrum are selected as the first specific detection wavelength and the second specific detection wavelength respectively.

[0026] Furthermore, the scattered echo signal at the first specific detection wavelength and the scattered echo signal at the second specific detection wavelength are obtained, and both meet the formula:

[0027]

[0028] In the formula, The laser radar detects wavelength λ at distance z R The echo signal of 0,λR is the emitted laser power; K λR is the laser radar system constant; is the laser radar system geometric factor; for the same laser radar system, is a constant; β λR (λ) Wavelength λ R The backscattering coefficient is sensitive to Raman scattering and the concentration of particles in water affects the Raman spectrum. Its backscattering cross section The product of At the incident wavelength λ0 and the detection wavelength λ R The extinction coefficient, incident wavelength λ0 and detection wavelength λ R When determined, it is only related to the gas molecules and aerosol distribution.

[0029] Further, the method of obtaining a first ratio of the scattered echo signal at the first specific detection wavelength to the scattered echo signal at the second specific detection wavelength, and obtaining a second ratio of the Raman scattering cross section at the first specific detection wavelength to the Raman scattering cross section at the second specific detection wavelength, based on a constant temperature test chamber, wherein the first ratio and the second ratio form a linear function relationship, includes:

[0030] Based on the constant temperature test box, a first ratio P of the scattered echo signal at the first specific detection wavelength to the scattered echo signal at the second specific detection wavelength is obtained. λ1 / P λ2 , where λ1 is the first specific detection wavelength λ2 is the second specific detection wavelength, P λ1 is the scattered echo signal at the first specific detection wavelength, P λ2 is a scattered echo signal at a second specific detection wavelength;

[0031] Based on the constant temperature environment of the thermostat, the first specific detection wavelength and the second specific detection wavelength, the linear function of the particle concentration and the refractive index affecting the water Raman spectrum is obtained according to the refractive index n being a function of the particle concentration S affecting the water Raman spectrum, the temperature t and the wavelength λ, wherein the refractive index n is:

[0032]

[0033] Where n i is the fitting coefficient, and is a value that can be found in the literature;

[0034] The local field correction factor L is obtained according to the refractive index n, and the formula is expressed as:

[0035] L=(n s / n0)*(n s 2 +2) 2 (n0 2 +2) 2 / 81 (3)

[0036] Where n s and n0 are the refractive indices at wavelength v0 and wavelength v0-v respectively;

[0037] The Raman scattering cross section of the suspended droplet is obtained according to the local field correction factor L, and the formula is:

[0038]

[0039] Where b is zero-point amplitude, g is initial state degeneracy factor, h is Planck constant, c is speed of light, k is Boltzmann constant, T is temperature, S is standard intensity, α' 2 and γ' 2 are the average invariant value of the polarizability tensor and the directional invariant, both of which are known quantities that can be found in the literature;

[0040] Obtain a second ratio of the Raman scattering cross section at the first specific detection wavelength to the Raman scattering cross section at the second specific detection wavelength where dσ λ1 / dΩ is the Raman scattering cross section at the first specific detection wavelength, dσ λ2 / dΩ is the Raman scattering cross section at the second specific detection wavelength;

[0041] Based on the linear function relationship between the first ratio and the second ratio, that is:

[0042]

[0043] Among them, K is the system function;

[0044] By combining formula (1) to formula (5), the concentration value of the particles affecting the water Raman spectrum is obtained.

[0045] The advantages of the present invention are: the present application is based on laser Raman spectroscopy and combined with laser radar technology to achieve real-time detection of the concentration of particles that affect the Raman spectrum of water in suspended droplets. The present invention will improve the real-time detection capability of the concentration of particles that affect the Raman spectrum of water in suspended droplets, and promote the application of laser radar in the concentration detection of particles that affect the Raman spectrum of water in industrial production and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Schematic diagram of the structure of the real-time detection device for particles in suspended droplets that affect the water Raman spectrum.

[0047] Figure 2 Flow chart of the method for real-time detection of particles in suspended droplets that affect the Raman spectrum of water.

[0048] Figure 3 Raman spectra of OH stretching vibration bands of NaCl solutions with different concentrations.

[0049] Figure 4 Assuming the temperature of the constant temperature test box is 25 degrees Celsius and the detection wavelength is 406nm, the relationship between salinity and refractive index is shown.

[0050] In the figure:

[0051] 1. Laser; 2. Transmitting optical path; 3. Constant temperature test chamber; 4. Receiving telescope; 5. Collimating lens; 6. Data acquisition system. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application. In the description of the embodiments of the present application, it should be understood that the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0053] Traditional methods for analyzing and measuring the concentration of particles that affect the Raman spectrum of water, including titration, electrochemistry, photometry, and chromatography, cannot meet actual needs. It is necessary to develop a non-invasive, non-contact method to achieve real-time detection of the concentration of particles that affect the Raman spectrum of water in salt spray suspension droplets.

[0054] Titration is widely used for chloride detection in water due to its good repeatability and wide detection range; the detection accuracy of the electrochemical method is slightly lower than that of the titration method, but it is more convenient; spectrophotometry is sensitive and can be used for low-concentration detection, but the use of mercury reagents is harmful to the environment; ion chromatography has high sensitivity and selectivity, and its analysis cost is high. Chromatography is prone to adsorb impurities, and this permanent adsorption will lead to a decrease in the adsorption capacity of the separation column, making it difficult to promote. Paper-based microfluidic technology is a fast, low-cost, real-time detection method that mainly uses colorimetric analysis to determine the concentration of the substance being tested.

[0055] With the development of science and technology, the detection requirements for the concentration of particles that affect the Raman spectrum of water have become higher, and often require the ability to measure in real time and contactlessly. Spectral detection technology is a non-invasive analysis method that can be used to obtain information on the molecular structure and chemical composition of substances. Since some substances do not have the Raman scattering effect, they have an absorption effect in deep ultraviolet light, but deep ultraviolet lasers 1 and detection equipment are difficult to manufacture, bulky, and expensive. However, since particles that do not have the Raman scattering effect will change the spectra of other substances in the space where the particles are located, indirect means are currently used to detect particles that affect the Raman spectrum of water.

[0056] At present, the commonly used methods for measuring the spectrum of particles that affect the Raman spectrum of water include surface enhanced Raman scattering, which is applicable to solids such as metals, X-ray method and laser induced breakdown spectroscopy. Surface enhanced Raman scattering is applicable to the detection of solids and other materials with surfaces, while laser induced breakdown spectroscopy requires a large laser energy to achieve air breakdown, which has a high actual application cost and has a breakdown and damage effect on the sample.

[0057] In order to solve the above problems, Figure 1 As shown, the present application discloses a real-time detection device for particles in a suspended droplet that affect the Raman spectrum of water, comprising:

[0058] A constant temperature test box 3, used for placing the suspended droplets and receiving the detection laser;

[0059] A laser receiving unit, used for receiving scattered echo signals generated by the particles affecting the water Raman spectrum;

[0060] A light splitting unit, used for splitting the scattered echo signal into scattered echo signals at a first specific detection wavelength and a second specific detection wavelength;

[0061] A laser detection unit, comprising a first laser detection component for detecting a scattered echo signal at a first specific detection wavelength, and a second laser detection component for detecting a scattered echo signal at a second specific detection wavelength;

[0062] The device also includes a data processing unit, which is used to obtain the concentration value of the particles affecting the water Raman spectrum according to the signals obtained by the first laser detection component and the second laser detection component.

[0063] The present application adopts a constant temperature test box 3, and obtains a first specific detection wavelength and a second specific detection wavelength through a spectroscopic unit. The data processing unit provides hardware support for obtaining the concentration value detection of particles affecting the water Raman spectrum based on the detection signals corresponding to the first specific detection wavelength and the second specific detection wavelength.

[0064] Specifically, the real-time detection device for particles in suspended droplets that affect the Raman spectrum of water further includes a detection laser generating unit, the detection laser generating unit is used to generate a detection laser for detecting the particles that affect the Raman spectrum of water; the detection laser generator includes:

[0065] Laser 1, used for emitting fundamental frequency laser to the particles affecting the water Raman spectrum to be detected;

[0066] The emission optical path 2 is used to change the wavelength of the fundamental frequency laser to obtain output light of a set wavelength.

[0067] In one embodiment, the laser 1 is a YAG laser 1. The output power of the YAG laser 1 is flexibly adjustable and has good beam quality.

[0068] The laser receiving unit comprises a receiving telescope 4 and a collimating lens 5 , and is used to receive laser signals from the suspended droplets in the constant temperature test box 3 .

[0069] In one embodiment, the emission optical path 2 includes a frequency doubling crystal and a frequency tripling crystal which are sequentially arranged, and the frequency doubling crystal and the frequency tripling crystal double the fundamental frequency laser output by the YAG laser 1 to finally obtain an output light of 355 nm.

[0070] In one of the embodiments, the light splitting unit is a 50:50 light splitter, which splits the large scattered echo signal received by the laser receiving unit into two identical signals.

[0071] In one embodiment, the first laser detection assembly includes a first narrowband filter and a first laser detector APD1 arranged in sequence along an optical path, and the second laser detection assembly includes a second narrowband filter and a second laser detector APD2 arranged in sequence along an optical path; the first narrowband filter and the second narrowband filter are used to filter out interfering light (not shown in the figure). The first laser detection assembly is used to receive a scattered echo signal at a first specific detection wavelength, and the second laser detection assembly is used to receive a scattered echo signal at a second specific detection wavelength.

[0072] In one embodiment, the bandwidth of the first narrowband filter and the second narrowband filter does not exceed half of the interval between the first specific detection wavelength and the second specific detection wavelength, and the filter bandwidth is as small as possible. Considering the cost, the bandwidth of the first narrowband filter and the second narrowband filter can be selected to be 0.5nm.

[0073] In one embodiment, the data processing unit includes a data acquisition system 6 and a computer PC for

[0074] Take the real-time detection of chloride ions in salt mist suspension droplets as an example. Salt mist is a tiny droplet of NaCl solution suspended in the air. NaCl is dissolved in water and then forms a + , Cl - and NaCl exist in three forms. In NaCl aqueous solution, Cl - OH to water molecules - The stretching vibration band has an impact, which is specifically manifested as affecting the Raman spectrum of water. The first specific detection wavelength is 400.4nm, and the second specific detection wavelength is 405.7nm, wherein the telescope can receive the stretching vibration Raman scattering echo signals of water molecules at the first specific detection wavelength and the second specific detection wavelength.

[0075] The above device provides hardware support for real-time detection of the concentration of particles in suspended droplets that affect the water Raman spectrum.

[0076] The present application also discloses a real-time detection method of particles in a suspended droplet that affect the Raman spectrum of water, comprising:

[0077] After emitting a single-wavelength detection laser into the constant temperature test box 3 containing the suspended droplets, a scattered echo signal at a first specific detection wavelength and a scattered echo signal at a second specific detection wavelength are obtained;

[0078] Acquire a first ratio of the scattered echo signal at the first specific detection wavelength to the scattered echo signal at the second specific detection wavelength, and acquire a second ratio of the Raman scattering cross section of water at the first specific detection wavelength to the Raman scattering cross section of water at the second specific detection wavelength;

[0079] Based on the linear function relationship between the first ratio and the second ratio, combined with the Raman scattering cross section of water at a fixed detection wavelength and the concentration function relationship of the particles affecting the water Raman spectrum, the concentration value of the particles affecting the water Raman spectrum is obtained.

[0080] This application is based on laser Raman spectroscopy and combined with laser radar technology to achieve real-time detection of the concentration of particles that affect the Raman spectrum of water in suspended droplets. It will also improve the real-time detection capability of the concentration of particles that affect the Raman spectrum of water in suspended droplets, and promote the application of laser radar in the detection of the concentration of particles that affect the Raman spectrum of water in industrial production and other fields.

[0081] In one embodiment, acquiring the scattered echo signal at the first specific detection wavelength and the scattered echo signal at the second specific detection wavelength includes:

[0082] The scattered echo signal at the first specific detection wavelength and the scattered echo signal at the second specific detection wavelength are obtained by time-sharing differential detection or simultaneous detection. If the first specific detection wavelength and the second specific detection wavelength are detected by time-sharing differential detection, the time interval between the two measurements of the first specific detection wavelength and the second specific detection wavelength is very short, and it can be approximately considered that the state of the suspended droplet remains unchanged during the two measurements. If the first specific detection wavelength and the second specific detection wavelength are detected simultaneously, the splitting ratio of the first specific detection wavelength and the second specific detection wavelength must remain unchanged.

[0083] In one embodiment, before acquiring the scattered echo signal at the first specific detection wavelength and the scattered echo signal at the second specific detection wavelength, the method further includes:

[0084] Obtaining Raman spectra of solutions corresponding to different concentrations of the particles that affect the water Raman spectrum;

[0085] In the Raman spectrum, the two wavelengths that are most affected by the solution corresponding to the particle concentration that affects the water Raman spectrum are selected as the first specific detection wavelength and the second specific detection wavelength. 3. The emission wavelength of laser 1 is 355nm, which is emitted into a constant temperature box filled with salt mist through the emission optical path 2. After the interaction between light and matter, the two wavelengths in the Raman scattering spectrum are received by the receiving optical path. 2900cm -1 To 3345cm -1 Range and 3345cm -1 To 3600cm -1 The Raman spectrum of water changes in the opposite direction due to the influence of NaCl concentration. Select two wavelengths with the largest difference in the influence of NaCl. For example, the scattering wavelength is 3210cm -1 and 3520cm -1 The two channels are respectively passed through narrow-band filters with central wavelengths of 400.6nm and 405.7nm and a bandwidth of 0.5nm and then received by the photodetector.

[0086] In one specific embodiment, the obtaining of Raman spectra of solutions corresponding to different concentrations of the particles affecting the water Raman spectrum includes obtaining Raman spectra of OH stretching vibration bands of NaCl solutions of different concentrations by consulting literature, or by direct measurement, such as Figure 3 shown.

[0087] In one embodiment, the scattered echo signal at the first specific detection wavelength and the scattered echo signal at the second specific detection wavelength are obtained, and both meet the formula:

[0088]

[0089] In the formula, The laser radar detects wavelength λ at distance z R The echo signal of 0,λR is the emitted laser power; K λR is the laser radar system constant; is the laser radar system geometric factor; for the same laser radar system, is a constant; β λR (λ) Wavelength λ R The backscattering coefficient is sensitive to Raman scattering and the concentration of particles in water affects the Raman spectrum. Its backscattering cross section The product of At the incident wavelength λ0 and the detection wavelength λ R The extinction coefficient, incident wavelength λ0 and detection wavelength λ RWhen determined, it is only related to the gas molecules and aerosol distribution.

[0090] In one embodiment, the incident wavelength λ0 is 355 nm and the detection wavelength λ R The first specific detection wavelength and the second specific detection wavelength are 400.6 nm and 405.7 nm respectively.

[0091] In one embodiment, the method of obtaining a first ratio of a scattered echo signal at the first specific detection wavelength to a scattered echo signal at the second specific detection wavelength, and obtaining a second ratio of a Raman scattering cross section at the first specific detection wavelength to a Raman scattering cross section at the second specific detection wavelength, based on the constant temperature test chamber 3, wherein the first ratio and the second ratio form a linear function relationship, comprises:

[0092] Based on the constant temperature test box 3, a first ratio P of the scattered echo signal at the first specific detection wavelength to the scattered echo signal at the second specific detection wavelength is obtained. λ1 / P λ2 , where λ1 is the first specific detection wavelength λ2 is the second specific detection wavelength, P λ1 is the scattered echo signal at the first specific detection wavelength, P λ2 is a scattered echo signal at a second specific detection wavelength;

[0093] Based on the constant temperature environment of the constant temperature water tank, the first specific detection wavelength and the second specific detection wavelength, the linear function of the particle concentration and the refractive index affecting the water Raman spectrum is obtained according to the refractive index n as a function of the particle concentration S affecting the water Raman spectrum, the temperature t and the wavelength λ, wherein the refractive index n is:

[0094]

[0095] Where n i is the fitting coefficient and is a known value. The specific value can be found in the literature. If the temperature distribution of the detection range is known or a constant temperature test box 3 is used, and the laser emission wavelength has been determined, the refractive index is only related to the salinity chloride ion concentration. Assuming that the temperature of the constant temperature test box 3 is 25 degrees Celsius and the detection wavelength is 406nm, the relationship between salinity and refractive index is as follows: Figure 4 shown.

[0096] The local field correction factor L is obtained according to the refractive index n, and the formula is expressed as:

[0097] L=(n s / n0)*(n s 2 +2) 2 (n0 2 +2) 2 / 81 (3)

[0098] Where n s and n0 are the refractive indices at wavelength v0 and wavelength v0-v respectively;

[0099] The Raman scattering cross section of the suspended droplet is obtained according to the local field correction factor L, and the formula is:

[0100]

[0101] Where, b is zero-point amplitude, g is initial state degeneracy factor, h is Planck constant, c is speed of light, k is Boltzmann constant, T is temperature, S is standard intensity, α' 2 and γ' 2 are the average invariant value and directional invariant of the polarizability tensor, both of which are known quantities that can be found in the literature;

[0102] Obtain a second ratio of the Raman scattering cross section at the first specific detection wavelength to the Raman scattering cross section at the second specific detection wavelength where dσ λ1 / dΩ is the Raman scattering cross section at the first specific detection wavelength, dσ λ2 / dΩ is the Raman scattering cross section at the second specific detection wavelength;

[0103] Based on the linear function relationship between the first ratio and the second ratio, that is:

[0104]

[0105] Among them, K is the system function;

[0106] Combined with formula (1) to formula (5), the concentration value of the particles that affect the water Raman spectrum is obtained. Taking salt mist suspension droplets as an example, by configuring salt mist suspension droplets of different concentrations to be placed in an experimental box for detection and system calibration, theoretically, the salinity (chloride ion concentration) in salt mist can be detected.

[0107] In the description of this specification, the description with reference to the terms "some embodiments" or "examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0108] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention.

Claims

1. A real-time detection device for particles in suspended droplets that affect the Raman spectrum of water, characterized in that: Including the following settings according to the optical path: A constant temperature test box, used for placing the suspended droplets and receiving the detection laser; A laser receiving unit, used for receiving scattered echo signals generated by the particles affecting the water Raman spectrum; A light splitting unit, used for splitting the scattered echo signal into scattered echo signals at a first specific detection wavelength and a second specific detection wavelength; A laser detection unit, comprising a first laser detection component for detecting a scattered echo signal at a first specific detection wavelength, and a second laser detection component for detecting a scattered echo signal at a second specific detection wavelength; The device also includes a data processing unit, which is used to obtain the concentration value of the particles affecting the water Raman spectrum according to the signals obtained by the first laser detection component and the second laser detection component.

2. The real-time detection device according to claim 1, characterized in that: It also includes a detection laser generating unit, which is used to generate a detection laser for detecting the particles that affect the water Raman spectrum; the detection laser generator includes: A laser, used for emitting fundamental frequency laser light to the particles affecting the water Raman spectrum being detected; The emission optical path is used to change the wavelength of the fundamental frequency laser to obtain output light of a set wavelength.

3. The real-time detection device according to claim 2, characterized in that: The emission light path includes a frequency doubling crystal and a frequency tripling crystal which are arranged in sequence.

4. The real-time detection device according to claim 1, characterized in that: The first laser detection assembly includes a first narrowband filter and a first laser detector APD1 arranged in sequence along the optical path, and the second laser detection assembly includes a second narrowband filter and a second laser detector APD2 arranged in sequence along the optical path; the first narrowband filter and the second narrowband filter are used to filter out interference light.

5. The real-time detection device according to claim 4, characterized in that: The bandwidths of the first narrowband filter and the second narrowband filter do not exceed half of the interval between the first specific detection wavelength and the second specific detection wavelength.

6. A method for real-time detection of particles in suspended droplets that affect the Raman spectrum of water, characterized in that: include: After emitting a single-wavelength detection laser into a constant temperature test box containing suspended droplets, a scattered echo signal at a first specific detection wavelength and a scattered echo signal at a second specific detection wavelength are obtained; Acquire a first ratio of the scattered echo signal at the first specific detection wavelength to the scattered echo signal at the second specific detection wavelength, and acquire a second ratio of the Raman scattering cross section of water at the first specific detection wavelength to the Raman scattering cross section of water at the second specific detection wavelength; Based on the linear function relationship between the first ratio and the second ratio, combined with the Raman scattering cross section of water at a fixed detection wavelength and the concentration function relationship of the particles affecting the Raman spectrum of water, the concentration value of the particles affecting the Raman spectrum of water is obtained.

7. The real-time detection method according to claim 6, characterized in that: The acquiring of the scattered echo signal at the first specific detection wavelength and the scattered echo signal at the second specific detection wavelength comprises: The scattered echo signal at the first specific detection wavelength and the scattered echo signal at the second specific detection wavelength are acquired by time-division differential detection or simultaneous detection.

8. The real-time detection method according to claim 7, characterized in that: Before acquiring the scattered echo signal at the first specific detection wavelength and the scattered echo signal at the second specific detection wavelength, the method further includes: Obtaining Raman spectra of solutions corresponding to different concentrations of the particles that affect the water Raman spectrum; In the Raman spectrum, two wavelengths that are most affected by the solution corresponding to the particle concentration affecting the water Raman spectrum are selected as the first specific detection wavelength and the second specific detection wavelength respectively.

9. The real-time detection method according to claim 6, characterized in that: The scattered echo signal at the first specific detection wavelength and the scattered echo signal at the second specific detection wavelength are obtained, and both conform to the formula: In the formula, The laser radar detects wavelength λ at distance z R The echo signal of 0,λR is the emitted laser power; K λR is the laser radar system constant; is the laser radar system geometric factor; for the same laser radar system, is a constant; β λR (λ) Wavelength λ R The backscattering coefficient is sensitive to Raman scattering and the concentration of particles in water affects the Raman spectrum. Its backscattering cross section The product of At the incident wavelength λ0 and the detection wavelength λ R The extinction coefficient, incident wavelength λ0 and detection wavelength λ R When determined, it is only related to the gas molecules and aerosol distribution.

10. The real-time detection method according to claim 9, characterized in that: The method of obtaining a first ratio of a scattered echo signal at the first specific detection wavelength to a scattered echo signal at the second specific detection wavelength, and obtaining a second ratio of a Raman scattering cross section at the first specific detection wavelength to a Raman scattering cross section at the second specific detection wavelength, based on a constant temperature test chamber, wherein the first ratio and the second ratio form a linear function relationship, comprises: Based on the constant temperature test box, a first ratio P of the scattered echo signal at the first specific detection wavelength to the scattered echo signal at the second specific detection wavelength is obtained. λ1 / P λ2 , where λ1 is the first specific detection wavelength λ2 is the second specific detection wavelength, P λ1 is the scattered echo signal at the first specific detection wavelength, P λ2 is a scattered echo signal at a second specific detection wavelength; Based on the constant temperature environment of the thermostat, the first specific detection wavelength and the second specific detection wavelength, the linear function of the particle concentration and the refractive index affecting the water Raman spectrum is obtained according to the refractive index n being a function of the particle concentration S affecting the water Raman spectrum, the temperature t and the wavelength λ, wherein the refractive index n is: where n i is the fitting coefficient, and is a value that can be found in the literature; The local field correction factor L is obtained according to the refractive index n, and the formula is expressed as: L=(n s / n0)*(n s 2 +2) 2 (n0 2 +2) 2 / 81 (3) where n s and n0 are the refractive indices at wavelength v0 and wavelength v0-v respectively; The Raman scattering cross section of the suspended droplet is obtained according to the local field correction factor L, and the formula is: Where b is zero-point amplitude, g is initial state degeneracy factor, h is Planck constant, c is speed of light, k is Boltzmann constant, T is temperature, S is standard intensity, α' 2 and γ' 2 are the average invariant value of the polarizability tensor and the directional invariant, both of which are known quantities that can be found in the literature; Obtain a second ratio of the Raman scattering cross section at the first specific detection wavelength to the Raman scattering cross section at the second specific detection wavelength where dσ λ1 / dΩ is the Raman scattering cross section at the first specific detection wavelength, dσ λ2 / dΩ is the Raman scattering cross section at the second specific detection wavelength; Based on the linear function relationship between the first ratio and the second ratio, that is: Among them, K is the system function; By combining formula (1) to formula (5), the concentration value of the particles affecting the water Raman spectrum is obtained.

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