A high-resolution scattering spectrum particle size measurement method and system

Abstract

The present invention provides a high-resolution scattering spectrum particle size measurement method and system. The method comprises: based on Mie scattering theory, introducing an angular scattering efficiency factor to simulate the scattering spectrum of the particle to be measured; selecting the scattering spectrum peak and scattering angle to be observed based on the relationship between the peak shift in the scattering spectrum, the particle size, and the scattering angle; establishing a calibration model based on the relationship between the peak shift in the scattering spectrum, the particle size, and the scattering angle; measuring the scattering spectrum of the particle to be measured, and determining the particle size of the particle to be measured using the calibration model. The present invention achieves particle size measurement by simply locating the peak of the measured scattering spectrum, simplifying data processing, and achieving extremely high measurement resolution.

Description

Technical Field

[0001] The present invention relates to the technical field of particle size measurement, and in particular to a high-resolution scattering spectrum particle size measurement method and system. Background Art

[0002] Particle size is an important indicator of certain properties of particles and their interactions with other substances. In many cases, even small changes in particle size can lead to significant changes in their physical and chemical properties. For example, monitoring small changes in the nuclear size of dysplastic cells can aid in early cancer diagnosis; small changes in the particle size of micron-sized ceramic particles can significantly affect the microstructure and mechanical properties of metal-matrix composites in which they serve as reinforcement; and small changes in the particle size of nanoparticles can significantly alter their tissue penetration. Therefore, high-precision and high-resolution particle size measurement is crucial. Compared to non-optical methods for particle size measurement (such as sedimentation and sieving), light scattering offers the advantages of greater adaptability and a non-contact nature, making it the most widely used particle size measurement technique. Light scattering methods primarily include side scattering, light correlation spectroscopy, dynamic light scattering, dark-field microscopy, and light scattering spectroscopy. The range and accuracy of the side scattering method are limited by the "multi-value" problem; the scattering correlation spectroscopy and dynamic light scattering methods have a long measurement time and insufficient rapid response performance; the dark field microscopy technology has a complex optical path structure and harsh measurement conditions, making it difficult to achieve on-site measurement.

[0003] Studies have shown that even if the change in particle size is less than one-tenth of the wavelength of the incident light, the scattering spectrum can change significantly. Therefore, scattering spectroscopy has the characteristics of high precision, high sensitivity, and high resolution, and is widely used in particle size measurement. The oscillation characteristics of the scattering spectrum are closely related to the size of the particles, and this characteristic is most obvious at a scattering angle of 180°. Therefore, current scattering spectroscopy technology mainly determines the particle size by observing the oscillation characteristics of the backscattering spectrum. In order to analyze the oscillation characteristics of the spectrum, backscattering spectroscopy requires Fourier analysis, first-order derivative spectrum analysis, or power spectrum analysis of the scattering spectrum within a certain wavelength range to establish the relationship between a specific physical parameter and the particle size, thereby realizing the measurement of the particle size. The measurement accuracy and resolution are greatly affected by the selection of the spectral band. To improve measurement accuracy, the existing backscattering spectroscopy method combines the above-mentioned spectral processing method with correlation operations, performing one-by-one correlation operations on the actual measured backscattering spectrum and the theoretical scattering spectrum database, thereby improving the accuracy of particle size measurement. Therefore, the data processing process of the backscattering spectroscopy method based on spectral oscillation characteristic analysis is complex, which is not conducive to the realization of real-time measurement of particle size. Summary of the Invention

[0004] In response to the defects in the prior art, the purpose of the present invention is to provide a high-resolution scattering spectrum particle size measurement method and system based on the determination of the peak wavelength of the scattering spectrum. The particle size is measured by directly measuring the peak position of the scattering spectrum, eliminating the shortcomings of the particle size measurement technology based on the oscillation characteristics of the scattering spectrum, such as complex calculations and the measurement results being easily interfered by the spectral band selection. In addition, this method has a measurement resolution higher than other scattering spectrum technologies and microscopic imaging methods.

[0005] According to one aspect of the present invention, a method for measuring particle size using high-resolution scattering spectroscopy is provided, the method comprising:

[0006] Based on Mie scattering theory, the angular scattering efficiency factor is introduced to simulate the scattering spectrum of the particles to be measured. The scattering peak and scattering angle to be observed are selected according to the relationship between the peak shift in the scattering spectrum and the particle size and scattering angle.

[0007] According to the relationship between the peak shift in the scattering spectrum and the particle size and scattering angle, the relationship between the peak wavelength and the particle size is established as a calibration model;

[0008] The scattering spectrum of the particles to be measured is measured, and the particle size of the particles to be measured is determined using the calibration model.

[0009] Based on Mie scattering theory, the energy distribution of light scattered by particles when incident light is irradiated is related to the particle size, wavelength of incident light, relative refractive index of particle-environment, and scattering angle. The angular scattering efficiency factor β(θ, λ) is introduced to characterize the scattering intensity distribution in a certain scattering angle direction when incident light of a certain wavelength is irradiated on particles of a certain size. The scattering efficiency factor is Among them, E s is the scattered light energy per unit time, E0 is the incident light energy per unit time, I S is the scattered light intensity, I0 is the incident light intensity, dΩ is the unit solid angle, r is the particle radius, i1(α, m, θ) and i2(α, m, θ) are the scattering intensity distribution functions in the vertical and parallel polarization directions, respectively, α (α = 2πr / λ) is the particle size parameter, and m is the relative refractive index of the particle (i.e., the ratio of the refractive index of the particle to the refractive index of the surrounding medium).

[0010] The wavelength range λ is obtained by calculating the β(θ,λ) formula min ~λ max By using the angular scattering efficiency factor, the scattering spectrum can be obtained for a specific particle size, refractive index, and scattering angle. By varying the particle size and scattering angle, scattering spectra under different particle size and scattering angle conditions can be obtained. Based on the relationship between the peak shift of the scattering spectrum and the particle size and scattering angle, a relationship between the peak wavelength of the spectrum and the particle size can be established, which serves as a calibration model. Particle size can be measured using this calibration model and the measured scattering spectrum.

[0011] Furthermore, the selection of the scattering spectrum peak and scattering angle to be observed based on the relationship between the peak shift in the scattering spectrum and the particle size and scattering angle includes:

[0012] The peaks of the scattering spectrum are marked in descending order of peak width as: P1, P2, P3...P n According to the order of particle size measurement resolution from high to low, the scattering spectrum peaks to be observed are selected from the widest peak P1 to perform wavelength positioning and then measure the particle size; according to the order of particle size measurement range from large to small, the scattering spectrum peaks to be observed are selected from the narrowest peak P n The scattering spectrum peaks to be observed are selected in sequence for wavelength positioning and then the particle size is measured; the scattering spectrum peaks to be observed are determined based on the measurement resolution and range.

[0013] Furthermore, the step of selecting the scattering spectrum peak and scattering angle to be observed based on the relationship between the peak shift in the scattering spectrum and the particle size and scattering angle also includes:

[0014] Set the spectral range of the spectrometer used to measure the scattering spectrum to λ min ~λ max , with the lower limit of wavelength λ within the spectral range of the spectrometer min Able to measure the peak position S of the smallest particle min The corresponding scattering angle or the upper limit of the wavelength within the spectrometer's spectral range λ max The peak position S of the largest particle can be measured max The corresponding scattering angle is taken as the scattering angle θ to be observed m .

[0015] Furthermore, establishing the relationship between the peak wavelength of the spectrum and the particle size as a calibration model includes:

[0016] The peak shape factor method is used to determine the peak position wavelength of the scattering spectrum peak of several particle sizes within the particle size measurement range;

[0017] The peak wavelength-particle size calibration model was obtained by fitting the peak wavelength-particle size relationship curve.

[0018] Furthermore, the peak shape factor method is used to determine the peak position wavelength of the scattering spectrum peak of several particle sizes within the particle size measurement range, wherein the peak shape factor method includes:

[0019] The scattering spectrum β(θ m ,λ), obtain the selected scattering spectrum β(θ m ,λ) is the maximum point P, which corresponds to the extreme value β of the scattering spectrum. max , half of the maximum value of the peak Draw a straight line parallel to the wavelength axis and the scattering spectrum β(θ m ,λ) intersect at points A and C respectively, connect AC, draw a straight line through P perpendicular to AC and intersect AC at point B,λ BC is the length of line segment BC, λ AB is the length of line segment AB, and the peak shape factor γ is:

[0020] Solve the γ for the peak of the scattering spectrum of each selected particle size, and perform least square fitting on γ to obtain the optimal shape factor γ of the peak m :γ m =min∑ i (γ i -γ m ) 2 ;

[0021] Using the wavelength λ at point A A and the optimal shape factor γ m Calculate the peak wavelength λ of the scattering spectrum of each particle size selected peak :

[0022] Furthermore, the measuring of the scattering spectrum of the particles to be measured and determining the particle size of the particles to be measured using the calibration model includes:

[0023] Perform smoothing and filtering on the measured scattering spectrum;

[0024] The peak wavelength of the scattering spectrum after smoothing and filtering is measured using the peak shape factor method to obtain the peak wavelength;

[0025] Substituting the peak wavelength into the calibration model, the measured particle size is obtained.

[0026] According to another aspect of the present invention, a high-resolution scattering spectrum particle size measurement system is provided for implementing the above-mentioned high-resolution scattering spectrum particle size measurement method. The system comprises:

[0027] A spectrometer, used for detecting a scattered light intensity spectrum and a transmitted light intensity spectrum, and for obtaining a scattered light spectrum;

[0028] A light source, used to provide incident light whose spectrum covers the detection spectrum range of the spectrometer;

[0029] Optical fiber, used for transmission and coupling of transmitted and scattered light;

[0030] Collimating lens, used to collimate and expand the incident light transmitted by the optical fiber into parallel incident light;

[0031] A rotating focusing lens is used to collect scattered light and transmitted light;

[0032] The rotating platform is used to adjust the scattering angle of the detection light;

[0033] Data processing system, used for spectrum acquisition and spectrum calculation;

[0034] The sample pool is used to hold the particle solution to be tested.

[0035] Furthermore, the rotating platform includes a sample pool limiting groove and a rotating disk; the sample pool limiting groove is used to fix the sample pool; the rotating focusing lens is fixed on the rotating disk and moves with the rotating disk to adjust the direction of the scattering angle of the collected scattered light; the rotating disk is provided with a rotation angle scale for displaying the size of the scattering angle.

[0036] According to another aspect of the present invention, a high-resolution scattering spectrum particle size measurement system is provided for implementing the above-mentioned high-resolution scattering spectrum particle size measurement method. The system comprises:

[0037] A spectrometer, used for detecting a scattered light intensity spectrum and a transmitted light intensity spectrum, and for obtaining a scattered light spectrum;

[0038] A light source, used to provide incident light whose spectrum covers the detection spectrum range of the spectrometer;

[0039] Optical fiber, used for transmission and coupling of transmitted and scattered light;

[0040] Fixed focusing lens, used to focus the incident light transmitted by the optical fiber into a small measurement area;

[0041] A rotating focusing lens is used to collect scattered light and transmitted light;

[0042] The rotating platform is used to adjust the scattering angle of the detection light;

[0043] Data processing system, used for spectrum acquisition and spectrum calculation;

[0044] The sample flow cell is used to allow the particles to pass through the measurement area one by one, so as to achieve the measurement of the single particle scattering spectrum.

[0045] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0046] 1. The present invention only needs to measure the scattered spectrum to determine the peak wavelength position. The calculation process is only to determine the peak wavelength, and there is no need to process the scattered spectrum of the entire band. The calculation is simple and fast.

[0047] 2. Using a spectrometer with a resolution of 0.8 nm, the present invention can measure the particle size of polystyrene beads with a resolution of 8.3 nm for particles of 1-10 μm and 1.1 nm for particles of 0.25-1 μm. Therefore, the present invention can significantly improve the resolution of particle size measurement.

[0048] 3. The present invention can measure the particle sizes of particles of different materials by changing the refractive index of the material in theoretical simulation and performing theoretical calibration on particles of different materials, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0050] Figure 1 Schematic diagram of the process of a high-resolution scattering spectrum particle size measurement method in one embodiment of the present invention;

[0051] Figure 2 Schematic diagram of a shape factor method for determining a spectral peak in one embodiment of the present invention;

[0052] Figure 3 Schematic diagram of a sample pool type particle size measurement system according to one embodiment of the present invention;

[0053] Figure 4 Schematic diagram of a sample flow cell type particle size measurement system according to one embodiment of the present invention;

[0054] Figure 5 Schematic diagram of a scattering spectrum simulation calculation model in one embodiment of the present invention;

[0055] Figure 6 Schematic diagram of the variation of the scattering spectrum peak with particle size in one embodiment of the present invention;

[0056] Figure 7 Schematic diagram of the variation of the scattering spectrum peak with the scattering angle in one embodiment of the present invention;

[0057] Figure 8 A calibration curve showing the relationship between the scattering spectrum peak and the particle size in one embodiment of the present invention;

[0058] Figure 9 1 is the measurement result of the scattering spectrum peak of particles with different particle sizes in one embodiment of the present invention. DETAILED DESCRIPTION

[0059] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0060] The embodiment of the present invention provides a high-resolution scattering spectrum particle size measurement method, specifically a particle size measurement method based on the peak wavelength determination of the scattering spectrum (specifically the angular scattering efficiency factor spectrum), referring to Figure 1 , the method comprising:

[0061] Step 1: Based on Mie scattering theory, the angular scattering efficiency factor β(θ,λ) is introduced to simulate the scattering spectrum of the particles to be measured. The scattering peak and scattering angle to be observed are selected based on the relationship between the peak shift in the scattering spectrum and the particle size and scattering angle.

[0062] Based on Mie scattering theory, the energy distribution of light scattered by particles when incident light is irradiated is related to the particle size, wavelength of incident light, relative refractive index between particle and environment, and scattering angle. The angular scattering efficiency factor β(θ,λ) is introduced to characterize the scattering intensity distribution in a certain scattering angle direction when incident light of a certain wavelength is irradiated on particles of a certain size. The angular scattering efficiency factor is Among them, E s is the scattered light energy per unit time, E0 is the incident light energy per unit time, I s is the scattered light intensity, I0 is the incident light intensity, dΩ is the unit solid angle, r is the particle radius, i1(α, m, θ) and i2(α, m, θ) are the scattering intensity distribution functions in the vertical and parallel polarization directions, respectively, α (α = 2πr / λ) is the particle size parameter, and m is the relative refractive index of the particle (i.e., the ratio of the refractive index of the particle to the refractive index of the surrounding medium).

[0063] The wavelength range λ is obtained by calculating the β(θ,λ) formula min ~λ max The angular scattering efficiency factor can be used to obtain the scattering spectrum under a certain particle size, refractive index, and scattering angle. By changing the particle size and scattering angle, scattering spectra under different particle size and scattering angle conditions can be obtained. Based on the relationship between the scattering spectrum peak shift and the particle size and scattering angle, the scattering spectrum peak and scattering angle to be observed can be selected.

[0064] It should be noted that β(θ, λ) is the angular scattering efficiency factor at a single wavelength. The angular scattering efficiency factors of multiple wavelengths are put into a curve to form the angular scattering efficiency factor spectrum, which is referred to as the scattering spectrum.

[0065] Step 2: Based on the relationship between the peak shift in the scattering spectrum and the particle size and scattering angle, the relationship between the peak wavelength and the particle size is established as a calibration model;

[0066] Based on the relationship between the peak shift of the scattering spectrum and the particle size and scattering angle, the relationship between the peak wavelength of the spectrum and the particle size can be established, which can be used as a calibration model; the particle size can be measured using the calibration model and the measured scattering spectrum.

[0067] Step 3: Measure the scattering spectrum of the particles to be measured and determine the particle size of the particles to be measured using the calibration model.

[0068] The embodiment of the present invention only needs to measure the scattered spectrum to determine the peak wavelength position. The calculation process is only for determining the peak wavelength, and there is no need to process the scattered spectrum of the entire band. The calculation is simple and fast.

[0069] In some embodiments, in step 1, selecting the scattering spectrum peak and scattering angle to be observed based on the relationship between the peak shift in the scattering spectrum and the particle size and scattering angle includes:

[0070] According to the theoretical refractive index of the particles to be measured and the surrounding medium, the angular scattering efficiency factor of the particles to be measured at different wavelengths is solved to obtain the scattering spectrum, namely the angular scattering efficiency factor spectrum. Specifically, under the conditions of incident wavelength λ and scattering angle θ, the angular scattering efficiency factor spectrum β(θ, λ) is:

[0071]

[0072] Among them, E s is the scattered light energy per unit time, E0 is the incident light energy per unit time, I S is the scattered light intensity, I0 is the incident light intensity, dΩ is the unit solid angle, r is the particle radius, i1(α, m, θ) and i2(α, m, θ) are the scattering intensity distribution functions in the vertical and parallel polarization directions, respectively, α (α = 2πr / λ) is the particle size parameter, and m is the relative refractive index of the particle (i.e., the ratio of the refractive index of the particle to the refractive index of the surrounding medium).

[0073] The peak of the scattering spectrum will redshift as the particle size increases, and for the same particle size change, the larger the peak width, the greater the redshift. Set the wavelength range of the scattering spectrum simulation to λ min ~λ max , mark the peaks of the scattering spectrum in descending order of peak width as: P1, P2, P3...P n ;

[0074] The measurement resolution and range are a pair of contradictions. The higher the resolution, the smaller the range. According to the order of particle size measurement resolution from high to low, the spectrum peaks are selected from the widest peak P1 as the scattering spectrum peaks to be observed for wavelength positioning and then the particle size is measured; according to the order of particle size measurement range from large to small, the spectrum peaks are selected from the narrowest peak P n The spectrum peaks are selected in sequence as the scattering spectrum peaks to be observed for wavelength positioning and then the particle size is measured; if a higher particle size measurement resolution is to be obtained, the widest peak P1 can be selected for wavelength positioning and then the particle size is measured; if a larger particle size measurement range is to be obtained, the second widest peak P2 or the third widest peak P3 can be selected for wavelength positioning and then the particle size is measured; the scattering spectrum peaks to be observed are determined based on the measurement resolution and range.

[0075] In some embodiments, in step 1, the scattering spectrum peak and scattering angle to be observed are selected based on the relationship between the peak shift in the scattering spectrum and the particle size and scattering angle, and the method further includes: the scattering spectrum peak will redshift with the increase of the scattering angle, and the spectral range of the spectrometer used to measure the scattering spectrum is set to λ min ~λ max , with the lower limit of wavelength λ within the spectral range of the spectrometer min Able to measure the peak position S of the smallest particle min The corresponding scattering angle or the upper limit of the wavelength within the spectrometer's spectral range λ max The peak position S of the largest particle can be measured max The corresponding scattering angle is the observed scattering angle θ m .

[0076] In some embodiments, in step 2, based on the relationship between the peak shift in the scattering spectrum and the particle size and scattering angle, a relationship between the peak wavelength and the particle size is established as a calibration model, including:

[0077] Step 21: Determine the peak position wavelength of the scattering spectrum peak for several particle sizes within the particle size measurement range using a peak shape factor method; wherein the peak shape factor method includes:

[0078] like Figure 2 As shown, the scattering spectrum β(θ m ,λ), obtain the selected scattering spectrum β(θ m ,λ) is the maximum point P, which corresponds to the extreme value β of the scattering spectrum. max Right now Figure 2 S in max , half of the maximum value of the peak Right now Figure 2 Draw a straight line parallel to the wavelength axis in Smax / 2, and the scattering spectrum β(θ m,λ) intersect at points A and C respectively, connect AC, draw a straight line through P perpendicular to AC and intersect AC at point B,λ BC is the length of line segment BC, λ AB is the length of line segment AB, and the peak shape factor γ is:

[0079] Perform the above operation to solve γ for the peak of the scattering spectrum of each selected particle size (the peak is the peak selected in step 1), and perform least square fitting on γ to obtain the optimal shape factor γ of the peak. m : γ m =min∑ i (γ i -γ m ) 2 ;

[0080] Using the wavelength λ at point A A and the optimal shape factor γ m Calculate the peak wavelength λ of the scattering spectrum of each particle size selected peak :

[0081] Step 22: Fit the peak wavelength and particle size relationship curve to obtain a peak wavelength-particle size calibration model.

[0082] In some embodiments, in step 3, measuring the particle size using the calibration model and the measured scattering spectrum includes:

[0083] Step 31: performing smoothing filtering on the measured scattering spectrum;

[0084] Step 32: Using a spectral peak shape factor method to measure the peak wavelength of the scattering spectrum after smoothing and filtering to obtain the peak wavelength; wherein the spectral peak shape factor method is the same as the spectral peak shape factor method in step 21;

[0085] Step 33: Substitute the peak wavelength into the calibration model to obtain the measured particle size.

[0086] The embodiment of the present invention simulates the scattering spectrum of the particles to be measured through a simulation method to obtain the optimal spectral peak and scattering angle for particle size measurement, adopts the shape factor method to obtain the peak wavelength of the scattering spectrum, calibrates the particle size, and obtains a calibration model for measurement; particle size measurement can be achieved by simply locating the spectral peak of the measured scattering spectrum, which simplifies data processing and has extremely high measurement resolution.

[0087] The embodiment of the present invention also provides a high-resolution scattering spectrum particle size measurement system for implementing the above-mentioned high-resolution scattering spectrum particle size measurement method, the system includes a spectrometer, a light source, an optical fiber, a collimating lens, a rotating focusing lens, a rotating platform, a data processing system and a sample pool, wherein: the spectrometer is used to detect the scattered light intensity spectrum and the transmitted light intensity spectrum, and is used to obtain the scattering spectrum (i.e., the angular scattering efficiency factor spectrum); the light source is used to provide incident light with a spectral band covering the spectrum range detected by the spectrometer; the optical fiber is used for transmitting and coupling the transmitted light and the scattered light; the collimating lens is used to collimate and expand the incident light transmitted by the optical fiber into parallel incident light; the rotating focusing lens is used to collect the scattered light and the transmitted light; the rotating platform is used to adjust the scattering angle of the detection light; the data processing system is used for spectral acquisition and spectral calculation; the sample pool is used to hold the particle solution to be measured; the sample pool type measurement system is as follows Figure 3 shown.

[0088] In some embodiments, the rotating platform includes a sample pool limiting groove and a rotating disk; the sample pool limiting groove is used to fix the sample pool; the rotating focusing lens is fixed on the rotating disk and moves with the rotating disk to adjust the direction of the scattering angle of the collected scattered light; the rotating disk is provided with a rotation angle scale for displaying the size of the scattering angle.

[0089] Another embodiment of the present invention provides a high-resolution scattering spectrum particle size measurement system for implementing the above-mentioned high-resolution scattering spectrum particle size measurement method. The difference from the particle size measurement system in the above-mentioned embodiment is that: in order to achieve the measurement of the scattering spectrum of a single particle, the following is adopted: Figure 4 The measurement system of the sample flow cell shown does not use a collimating lens to collimate the incident light. Instead, it uses a fixed focusing lens, i.e., a converging lens, to converge the incident light transmitted by the optical fiber into a tiny measurement area. The sample cell uses a sample flow cell, and the particles to be measured pass through the tiny measurement area one by one.

[0090] In a preferred embodiment, the measurement system includes a spectrometer, a light source, an optical fiber, a collimating lens, a rotating focusing lens, a rotating platform, a data processing system, and a sample cell; wherein the spectrometer is used to detect the scattered light intensity spectrum and the transmitted light intensity spectrum, the detection spectrum range is 200-1100nm, and the spectral resolution is 0.8nm; the light source is used to provide incident light with a wide spectrum covering the detection range of the spectrometer, and a halogen tungsten lamp is selected with an output light power of 5w; the optical fiber is used for light transmission and coupling, the aperture is 200μm, and the numerical aperture NA is 0.32; the collimating lens is used to collimate and expand the incident light transmitted by the optical fiber into parallel incident light; and the rotating focusing lens is used to collect the scattered light. The cross-section of the collimating lens and the focusing lens barrel is 5mm, and the focal length of the lens is 10mm; the rotating platform is used to adjust the scattering angle of the detection light, that is, the scattered light collected by the rotating focusing lens. The rotating platform includes a sample pool limit groove, a rotation angle scale, and a rotating disk. The focusing collection barrel is fixed to the rotating disk and can move with the rotating disk to adjust the scattering angle of the collected scattered light; the data processing system is used to collect the scattered light intensity spectrum and the transmitted light intensity spectrum of the sample, and at the same time calculate the scattered light intensity spectrum and the transmitted light intensity spectrum to obtain the scattering spectrum of the particles (angular scattering efficiency factor spectrum); the sample pool is used to hold the particle solution to be tested.

[0091] In one embodiment, the sample to be measured is a solution of polystyrene beads of different particle sizes, with a mass concentration of 0.025 g / ml, which needs to be diluted before use. The measurement process is as follows:

[0092] Add 15ml of water to the sample cell and 6μl of the polystyrene stock solution of the particle size to be measured; turn the receiving lens of the rotary focusing lens to a scattering angle of 0° and measure the transmitted light flux Φ t :

[0093]

[0094] Then measure the scattered light Φ at a certain scattering angle sg_mea (θ0):

[0095]

[0096] The angular scattering spectrum β at different scattering angles is obtained by dividing the measured scattered light by the transmitted light. g (λ j ,θ0):

[0097]

[0098] Where E0 is the incident parallel beam intensity in the measurement area; θ0 is the scattering angle, V(θ0) is the volume of the scattering area; Φ sg_mea (θ0) is the measured scattered light flux, Φ tis the measured transmitted light flux; l2 is the distance from the transmitted light and scattered light detection position to the center of the sample cell (center of the detection area); the particles of the monodisperse particle system are assumed to have equal particle size, and the angular scattering coefficient of particles of this size is β(θ0); the particle number concentration is N; K ext is the extinction coefficient of the solution in the sample cell.

[0099] The above formula shows that this method can also be used to measure a monodisperse particle system composed of multiple particles of equal size. While polystyrene is used as an example, if you want to measure the particle size of particles of other materials, you only need to change the refractive index in the simulation to obtain a theoretical calibration curve. By changing the refractive index of the material in the theoretical simulation and performing theoretical calibration on particles of different materials, you can measure the particle size of different materials, which has a wide range of applications.

[0100] To avoid interference from stray light, the entire experiment was conducted in a darkroom to ensure consistent testing conditions. For each sample group, five spectra were collected at each scattering angle (i.e., the scattering angle to be observed) and the averaged results were used as the measurement result at that position. Each sample was measured five times at each scattering angle.

[0101] Taking the particle size measurement of polystyrene beads as an example, the high-resolution scattering spectrum particle size measurement method and system in the embodiment of the present invention are further explained.

[0102] The particle size of polystyrene beads ranging from 1 to 8 μm was measured using a 200-1100 nm spectrometer according to the following steps:

[0103] Step 1: Calculate the angular scattering efficiency factor of polystyrene beads suspended in water at different wavelengths to obtain the scattering spectrum of the polystyrene beads. Study the scattering spectra of polystyrene beads of different particle sizes and at different scattering angles to determine the observed scattering spectrum peak and observation angle.

[0104] The solution of angular scattering efficiency factor is as follows Figure 5 , the calculation formula is as follows:

[0105]

[0106] Among them, E s is the scattered light energy per unit time, E0 is the incident light energy per unit time, I s is the scattered light intensity, I0 is the incident light intensity, dΩ is the unit solid angle, r is the particle radius, i1(α, m, θ) and i2(α, m, θ) are the scattering intensity distribution functions in the vertical and parallel polarization directions, respectively, α (α = 2πr / λ) is the particle size parameter, and m is the relative refractive index of the particle (i.e., the ratio of the refractive index of the particle to the refractive index of the surrounding medium).

[0107] Through theoretical simulation calculations, it is known that the peak width of each scattering spectrum decreases from the long-wave band to the short-wave band. The peaks are named "Peak 1", "Peak 2", "Peak 3", ... "Peak n" in descending order of peak width. Under the condition of constant scattering angle, the peak of the scattering spectrum shifts to the long-wave band as the particle size increases. For the same particle size change, the peak shift is more obvious when the peak width is larger, such as Figure 6 At the same time, when the particle size is constant, the scattering spectrum peak moves toward the long-wave band as the scattering angle increases, such as Figure 7 .

[0108] The spectrometer used can detect the spectral range of 200-1100nm, which is a fixed value. If the peak width of the spectrum to be observed is larger, the peak position of the spectrum peak will change greatly within a smaller particle size range, which may lead to the limited particle size measurement range of the spectrometer. In order to expand the range, you can select "Peak 2" for tracking, such as Figure 6 When selecting the scattering angle, the scattering angle should be adjusted so that the spectrum peak of 1μm (the lower limit of the measured particle size) is located at around 200nm (the lower limit of the spectrum range of the spectrometer). Therefore, by simulating the scattering spectra of different scattering angles of 1μm, the scattering angle is determined to be 5°, such as Figure 7 .

[0109] Step 2: Establish a calibration model for the particle size and spectral peak position of particles in the particle size range to be measured.

[0110] The particle size of 1-8μm is discretized, and the scattering spectra of polystyrene beads of 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm and 8μm are simulated. The peak position wavelength of the scattering spectrum of each particle size is solved using the peak shape factor method.

[0111] The peak position and the above particle size are fitted to obtain the calibration model, such as Figure 8 In the figure, y represents the peak wavelength and x represents the particle size. The peak position wavelength of the second scattering spectrum of polystyrene beads of 1-8 μm solved by the peak shape factor method and the particle size meet an excellent linear relationship. The relationship between the peak wavelength and the particle size is fitted as follows:

[0112] y=96.24x+109.2

[0113] And r 2=0.9999, y is the peak wavelength in nm, x is the particle size in μm, and every 0.1 μm change in particle size will produce a 9.624 nm shift in the spectrum peak. When the spectrometer resolution is 0.8 nm, the resolution of the particle size measurement is 8.3 nm, which is much higher than other traditional measurement methods such as microscopy.

[0114] Step 3: Measure the scattering spectrum of the sample to be tested, use the shape factor method to solve the peak wavelength of the selected spectrum peak, substitute the measured peak position into the calibration model to solve the particle size. Figure 9 The scattering spectrum peaks and particle size scattering points of the polystyrene ball sample solutions with five different particle sizes are located near the calibration curve, indicating that this method can achieve high-resolution measurement of particle size.

[0115] The particle size measurement method and system based on scattering spectrum peak determination (or location) in the above-described embodiments of the present invention detects particle size solely by the location of the scattering spectrum peak. Using a spectrometer with a spectral resolution of 0.8 nm and a spectral range of 200-1100 nm, the system achieves a resolution of 8.3 nm for particles 1-8 μm and a resolution of 1.1 nm for polystyrene spheres 0.25-1 μm. The measurement process is simple, the calculations are straightforward, and the size of other spherical particles can be measured by varying the simulated material's refractive index.

[0116] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various modifications or variations within the scope of the claims without affecting the essence of the present invention. The above preferred features may be used in any combination as long as they do not conflict with each other.

Claims

1. A high-resolution scattering spectrum particle size measurement method, characterized in that: include: Based on Mie scattering theory, the angular scattering efficiency factor is introduced to simulate the scattering spectrum of the particles to be measured. The scattering peak and scattering angle to be observed are selected according to the relationship between the peak shift in the scattering spectrum and the particle size and scattering angle. According to the relationship between the peak shift in the scattering spectrum and the particle size and scattering angle, the relationship between the peak wavelength and the particle size is established as a calibration model; Measuring the scattering spectrum of the particles to be measured, and determining the particle size of the particles to be measured using the calibration model; The method of selecting the scattering spectrum peak and scattering angle to be observed based on the relationship between the peak shift in the scattering spectrum and the particle size and scattering angle includes: The peaks of the scattering spectrum are marked in descending order of peak width as: P1, P2, P3...P n According to the order of particle size measurement resolution from high to low, the scattering spectrum peaks to be observed are selected from the widest peak P1 to perform wavelength positioning and then measure the particle size; according to the order of particle size measurement range from large to small, the scattering spectrum peaks to be observed are selected from the narrowest peak P n The scattering spectrum peaks to be observed are selected in sequence for wavelength positioning and then the particle size is measured; the scattering spectrum peaks to be observed are determined based on the measurement resolution and range.

2. The high-resolution scattering spectrum particle size measurement method according to claim 1, characterized in that: The method of selecting the scattering spectrum peak and scattering angle to be observed based on the relationship between the peak shift in the scattering spectrum and the particle size and scattering angle also includes: Set the spectral range of the spectrometer used to measure the scattering spectrum to λ min ~λ max , with the lower limit of wavelength λ within the spectral range of the spectrometer min Able to measure the peak position S of the smallest particle min The corresponding scattering angle or the upper limit of the wavelength within the spectrometer's spectral range λ max The peak position S of the largest particle can be measured max The corresponding scattering angle is taken as the scattering angle θ to be observed m .

3. The high-resolution scattering spectrum particle size measurement method according to claim 1, characterized in that: The establishing of the relationship between the peak wavelength of the spectrum and the particle size as a calibration model includes: The peak shape factor method is used to determine the peak position wavelength of the scattering spectrum peak of several particle sizes within the particle size measurement range; The peak wavelength-particle size calibration model was obtained by fitting the peak wavelength-particle size relationship curve.

4. The high-resolution scattering spectrum particle size measurement method according to claim 3, characterized in that: The peak shape factor method is used to determine the peak position wavelength of the scattering spectrum peak of several particle sizes within the particle size measurement range, wherein the peak shape factor method includes: The scattering spectrum β(θ m ,λ), obtain the selected scattering spectrum β(θ m ,λ) is the maximum point P, which corresponds to the extreme value β of the scattering spectrum. max , half of the maximum value of the peak Draw a straight line parallel to the wavelength axis and the scattering spectrum β(θ m ,λ) intersect at points A and C respectively, connect AC, draw a straight line through P perpendicular to AC and intersect AC at point B,λ BC is the length of line segment BC, λ AB is the length of line segment AB, and the peak shape factor γ is: Solve the γ for the peak of the scattering spectrum of each selected particle size, and perform least square fitting on γ to obtain the optimal shape factor γ of the peak m : c m =min∑ i (c i -c m ) 2 ; Using the wavelength λ at point A A and the optimal shape factor γ m Calculate the peak wavelength λ of the scattering spectrum of each particle size selected peak :

5. The high-resolution scattering spectrum particle size measurement method according to claim 3, characterized in that: The measuring of the scattering spectrum of the particles to be measured and determining the particle size of the particles to be measured using the calibration model includes: Perform smoothing and filtering on the measured scattering spectrum; The peak wavelength of the scattering spectrum after smoothing and filtering is measured using a spectral peak shape factor method to obtain the peak wavelength; the spectral peak shape factor method includes: The scattering spectrum β(θ m ,λ), obtain the selected scattering spectrum β(θ m ,λ) is the maximum point P, which corresponds to the extreme value β of the scattering spectrum. max , half of the maximum value of the peak Draw a straight line parallel to the wavelength axis and the scattering spectrum β(θ m ,λ) intersect at points A and C respectively, connect AC, draw a straight line through P perpendicular to AC and intersect AC at point B,λ BC is the length of line segment BC, λ AB is the length of line segment AB, and the peak shape factor γ is: Solve the γ for the peak of the scattering spectrum of each selected particle size, and perform least square fitting on γ to obtain the optimal shape factor γ of the peak m : c m =min∑ i (c i -c m ) 2 ; Using the wavelength λ at point A A and the optimal shape factor γ m Calculate the peak wavelength λ of the scattering spectrum of each particle size selected peak : Substituting the peak wavelength into the calibration model, the measured particle size is obtained.

6. A high-resolution scattering spectrum particle size measurement system, used to implement the high-resolution scattering spectrum particle size measurement method according to any one of claims 1 to 5, characterized in that: include: A spectrometer, used for detecting a scattered light intensity spectrum and a transmitted light intensity spectrum, and for obtaining a scattered light spectrum; A light source, used to provide incident light whose spectrum covers the detection spectrum range of the spectrometer; Optical fiber, used for transmission and coupling of transmitted and scattered light; Collimating lens, used to collimate and expand the incident light transmitted by the optical fiber into parallel incident light; A rotating focusing lens is used to collect scattered light and transmitted light; The rotating platform is used to adjust the scattering angle of the detection light; Data processing system, used for spectrum acquisition and spectrum calculation; The sample pool is used to hold the particle solution to be tested.

7. The high-resolution scattering spectrum particle size measurement system according to claim 6, characterized in that: The rotating platform includes a sample pool limiting groove and a rotating disk; the sample pool limiting groove is used to fix the sample pool; the rotating focusing lens is fixed on the rotating disk and moves with the rotating disk to adjust the direction of the scattering angle of the collected scattered light; the rotating disk is provided with a rotation angle scale for displaying the size of the scattering angle.

8. A high-resolution scattering spectrum particle size measurement system, used to implement the high-resolution scattering spectrum particle size measurement method according to any one of claims 1 to 5, characterized in that: include: A spectrometer, used for detecting a scattered light intensity spectrum and a transmitted light intensity spectrum, and for obtaining a scattered light spectrum; A light source, used to provide incident light whose spectrum covers the detection spectrum range of the spectrometer; Optical fiber, used for transmission and coupling of transmitted and scattered light; Fixed focusing lens, used to focus the incident light transmitted by the optical fiber into a small measurement area; A rotating focusing lens is used to collect scattered light and transmitted light; The rotating platform is used to adjust the scattering angle of the detection light; Data processing system, used for spectrum acquisition and spectrum calculation; The sample flow cell is used to allow the particles to pass through the measurement area one by one, so as to achieve the measurement of the single particle scattering spectrum.

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