A method and device for measuring the three-dimensional distribution of the particle size of nanoparticles in a solution

Abstract

The present invention discloses a method for measuring the three-dimensional distribution of the particle size of nanoparticles in a solution: irradiating the nanoparticles with a laser beam, and the scattered light formed interferes with a reference light modulated by an optical path to form holographic interference fringes, which are recorded on a camera to obtain a digital hologram of the nanoparticles; performing three-dimensional reconstruction on the digital hologram to obtain a focused image of the nanoparticles; and obtaining the particle size of the nanoparticles based on the scattered signal in the focused image, the principle of dynamic light scattering, and the correlation between the particle size and the diffusion coefficient of the nanoparticles. The present invention also discloses an apparatus for measuring the three-dimensional distribution of the particle size of nanoparticles in a solution: a signal emission unit, including a continuous laser and an optical path adjustment section; a signal receiving unit, including a camera for recording the holographic interference fringes; and a signal processing unit, connected after the signal receiving unit, for processing the digital hologram of the nanoparticles. The method and the apparatus achieve in-situ measurement of the instantaneous particle size distribution of nanoparticles at three-dimensional positions in a sample cell.

Description

Technical Field

[0001] The present invention relates to the field of nanoparticle size measurement, and particularly to a method and device for measuring the three-dimensional distribution of nanoparticle sizes in a solution. Background Art

[0002] Nanotechnology is a new interdisciplinary technology based on a variety of modern advanced scientific and technological fields, and has now been successfully applied in fields such as medicine, pharmacy, environmental governance, biological detection, optics, and national defense. The nanomaterials produced by nanotechnology have attracted wide attention in various disciplines. For example, nanoscale carbon materials represented by graphene and carbon nanotubes can be successfully applied to capacitors, energy storage batteries, etc.; composite nanomaterials represented by nano zero-valent iron show important advantages in the field of remediation of organic pollutants and heavy metals in soil and groundwater due to their unique adsorption and reduction properties; nanomaterials in biomedicine can be well applied to the specific recognition and highly sensitive detection of cancer cells; the mixing of nanoparticles with rocket metal propellants can significantly improve the combustion characteristics and increase the combustion efficiency and speed.

[0003] The prerequisite for nanoparticles to exert their specific advantages is the controllable preparation of nanoparticle materials. The particle size of the material is a key factor determining its performance. Currently, the methods for measuring particle size are mainly divided into offline methods and online methods. The offline methods mainly include screening method, sedimentation method, and microscopy method. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are commonly used characterization methods for nanoparticles, with a resolution of up to 1 nm or even smaller sizes. The data is intuitive and easy to understand, but in-situ real-time measurement cannot be achieved. Not only is the sampling amount small, but the sample preparation process will have a serious impact on the results; the online methods mainly include electrical method, acoustic method, and optical method. The laser particle size analyzer is the most widely used method in optics. The laser particle size analyzer measures nanoparticles mainly based on the principle of dynamic light scattering (photon correlation spectroscopy). The nanoparticles in the liquid mainly perform Brownian motion. By measuring the migration rate of the nanoparticles dispersed in the liquid, the corresponding particle size distribution can be obtained. However, its sampling usually uses a photomultiplier tube, and the measurement takes about 1.5 minutes. Moreover, the intensity of Brownian motion is related to factors such as temperature, particle size, and liquid viscosity. The measurement time is long, a temperature control device is required, the instrument structure is complex, the price is expensive, and the particle size distribution in the instantaneous three-dimensional space field cannot be obtained.

[0004] Online digital holography technology is a real-time three-dimensional measurement technology. It can not only achieve the characteristics of full-field, non-calibration, and non-contact by optical means, but also measure the three-dimensional position of particles simultaneously with a single camera. When a laser beam is incident, the light beam passing through the particle field is scattered into object light, and the unscattered light is reference light. The object light and the reference light interfere to form a hologram (interference fringes), which is recorded by a CCD or CMOS camera. The obtained signal contains amplitude and phase information. Compared with traditional chemical silver halide dry plates, numerical signal transmission of the holographic image can be achieved, and the depth of the particles can be obtained through numerical reconstruction, thereby realizing the measurement of the particle size distribution of nanoparticles in the medium. Compared with the traditional method of using only CCD or CMOS to record the dynamic light scattering signal of the whole field, the method of digital holography can obtain the light scattering signals of each cross-section of the whole field by taking a single picture, greatly improving the accuracy and efficiency of nanoparticle size measurement. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and device for measuring the three-dimensional distribution of nanoparticle size in a solution, which solves the problem of difficult in-situ real-time measurement of the three-dimensional distribution of nanoparticle size in a solution.

[0006] The present invention provides the following technical solutions:

[0007] A method for measuring the three-dimensional distribution of nanoparticle size in a solution, the method comprising the following steps:

[0008] (1) Irradiate the nanoparticles in the sample cell with a laser beam. The scattered light formed by the nanoparticles interferes with the reference light modulated by the optical path to form holographic interference fringes, and the holographic interference fringes are recorded on the photosensitive chip of the camera at a time interval of Δτ and an angle of θ, obtaining a series of digital holograms of nanoparticles undergoing Brownian motion during the measurement period;

[0009] (2) Perform three-dimensional reconstruction on the digital holograms of the nanoparticles recorded in step (1) to obtain a focused image of the nanoparticles in the sample cell on any x-y cross-section, where the x-y cross-section is a cross-section perpendicular to the incident light;

[0010] (3) According to the scattering signal in the focused image in step (2), based on the principle of dynamic light scattering, and according to the correlation between the particle size d of the nanoparticles and the diffusion coefficient D T the particle size d of the nanoparticles in the cross-section is obtained.

[0011] Wherein, in step (1), Δτ is adjusted according to the measured particle size range, the angle θ can be 10°, and can be adjusted according to the frame rate of the camera.

[0012] In step (1), the brightness fringes of the digital holograms of the nanoparticles are:

[0013] I H= |O + R| 2 = I O + I R + OR * + O * R

[0014] When using the same light beam as the original reference light to reconstruct the holographic image, the holographic reconstruction image satisfies:

[0015] I H R = |OO * |R + |RR * |R + |RR * |O + O * |RR * |

[0016] Wherein, O is the complex amplitude distribution of the scattered light; R is the reference light; the first and second terms are the DC phases; the third term forms the imaginary phase; the fourth term forms the real image.

[0017] The method for performing three-dimensional reconstruction on the nanoparticle digital hologram in step (2) to obtain the focused image of the nanoparticles in any x-y cross-section in the sample cell is as follows:

[0018] Using the convolution reconstruction method for three-dimensional reconstruction, the third term |RR in the holographic reconstruction image * |O contains the object light information. The complex amplitude distribution for reconstructing the hologram using the Rayleigh-Sommerfeld diffraction formula can be expressed as:

[0019]

[0020] Where (x, y) and (u, v) are the coordinates of the holographic plane and the reconstruction plane respectively, z r is the reconstruction distance, and Γ represents the complex amplitude distribution of the reconstructed light field;

[0021] Rewrite the above formula into a convolution form:

[0022]

[0023] Where g(u, v, z r ) is:

[0024]

[0025] Perform two Fourier transforms and inverse Fourier transforms on the above formula for numerical calculation:

[0026]

[0027] Obtain the focused image of the x-y cross-section at different reconstruction distances z r of the hologram.

[0028] In step (3), the method for obtaining the particle size d of the nanoparticles in the cross-section is as follows:

[0029] (3-1) Obtain the autocorrelation function from the scattering signal of the focused image of the x-y cross-section:

[0030] The correlation analysis coefficient G(τ) is:

[0031] G(τ) = exp(-2Γτ)

[0032] where Γ is the decay linewidth and τ is the decay time;

[0033] Γ satisfies the equation:

[0034]

[0035] where D T is the particle diffusion coefficient; q is the scattering vector; θ is the scattering angle; λ is the wavelength of light in vacuum; n is the refractive index of the dispersion medium;

[0036] (3-2) Taking the autocorrelation function as the baseline, obtain the relationship between the particle size and the diffusion coefficient from the Stokes-Einstein equation:

[0037] The particle diffusion coefficient D T :

[0038]

[0039] where K B is the Boltzmann constant; T is the absolute temperature; η is the viscosity; d is the particle size of the nanometer particles to be measured;

[0040] (3-3) According to the relationship between the particle size and the diffusion coefficient, obtain the particle size d of the nanoparticles:

[0041]

[0042] Finally, obtain the particle size distribution of the nanoparticles in each cross-section of the sample pool.

[0043] The present invention also provides a device for measuring the three-dimensional distribution of the particle size of nanoparticles in a solution. The device includes a signal transmitting unit, a signal receiving unit, and a signal processing unit;

[0044] The signal transmitting unit includes a continuous laser and an optical path adjustment section. A part of the laser beam generated by the continuous laser is converged and irradiated on the nanoparticles to form scattered light, and another part of the laser beam is used as a reference light through the optical path adjustment section. The scattered light and the reference light interfere to form holographic interference fringes;

[0045] The signal receiving unit includes a camera that records holographic interference fringes at time intervals of Δτ to obtain a series of digital holograms of nanoparticles undergoing Brownian motion during the measurement period.

[0046] The signal processing unit is connected after the signal receiving unit and is used for processing the digital holograms of nanoparticles: including removing background noise; performing three-dimensional reconstruction on the digital holograms of nanoparticles to obtain focused images of nanoparticles on any x-y cross-section; based on the scattering signals given by the focused images, according to the dynamic light scattering principle, and based on the correlation between the particle size d of the nanoparticles and the diffusion coefficient D T the particle size of the cross-sectional nanoparticles is obtained.

[0047] Preferably, the laser wavelength of the continuous laser is in the visible light band of 350 nm - 700 nm, and the power is 1 - 500 mW. Among them, the continuous laser can adjust the laser wavelength and power according to the scattering characteristics of the nanoparticles.

[0048] Preferably, the laser beam generated by the continuous laser is split into a first laser beam and a second laser beam by a first beam splitter. The first laser beam is converged by a convex lens and then irradiates the nanoparticles to form scattered light; the second laser beam forms a reference light after passing through a reflecting mirror, a spatial filter, a collimating lens, and an attenuator in sequence; the scattered light and the reference light are adjusted to be on the same main optical axis by a second beam splitter.

[0049] The spatial filter consists of a microscope objective and a pinhole.

[0050] Among them, the first beam splitter splits the laser beam into a first laser beam and a second laser beam with the same energy. The reflecting mirror, the spatial filter, the collimating lens, and the attenuator form an optical path adjustment section: the spatial filter consists of a microscope objective and a pinhole to improve the beam quality of the laser refracted by the reflecting mirror; the collimating lens collimates the diffused light into a parallel beam, and then an attenuator is connected to attenuate the laser energy, avoiding the situation that the reference light energy is too strong to interfere with the scattered light to form clear holographic interference fringes, and also avoiding damage to the CCD or CMOS camera photosensitive chip due to too strong laser energy. Finally, the second beam splitter makes the reference light adjusted by the optical path and the measured scattered light on the same main optical axis.

[0051] Preferably, the camera is a CCD or CMOS high-speed camera, the sampling frequency is 20 kHz - 50 kHz, and the exposure time is less than 500 ns. The photosensitive chip of the CCD or CMOS high-speed camera is perpendicular to the propagation direction of the scattered light.

[0052] The present invention utilizes digital holography technology to perform three-dimensional reconstruction at different reconstruction distances, and can obtain the scattered light intensity distribution of nanoparticles in each cross-section of the sample cell at a certain moment; through holography technology, the spatial light field is segmented and intercepted, and the light field information at different positions in space is restored using a single image. A high-speed camera is used to record the holographic fringes of the particles at time intervals of Δτ, and the dynamic light scattering signals of each cross-section of the sample cell are reconstructed. Since the pulsation of the light scattering signal is generated by the Brownian motion of the nanoparticles, and the scattering pulsation frequency is related to the particle diffusion coefficient, the particle size distribution of nanoparticles at different spatial positions in the solution can be obtained.

[0053] The method and device for measuring the three-dimensional distribution of nanoparticle sizes in a solution proposed by the present invention have the beneficial effect of realizing the in-situ measurement of the instantaneous nanoparticle size distribution at three-dimensional positions in the sample cell. After digital holographic three-dimensional reconstruction and dynamic light scattering correlation algorithm processing, the measurement time can be shortened to the microsecond level. This measurement method can extend the measurement accuracy of holography technology to the nanometer level. Compared with the traditional photon correlation spectroscopy (PCS) nanoparticle size analyzer based on the principle of dynamic light scattering, it realizes the in-situ instantaneous particle size measurement of nanoparticles at specific three-dimensional positions in terms of measurement speed and dimension. Description of the Drawings

[0054] Figure 1 Schematic diagram of holographic reconstruction of nanoparticle scattering signals;

[0055] Figure 2 Schematic diagram of the structure of the device for measuring the three-dimensional distribution of nanoparticles in a solution provided by the present invention;

[0056] Among them, 1. Laser, 2. First beam splitter, 3. Convex lens, 4. First reflector, 5. Second reflector, 6. Microscopic objective lens, 7. Pinhole, 8. Collimating lens, 9. Attenuator, 10. Second beam splitter, 11. Sample cell, 12. High-speed camera. Detailed Embodiment

[0057] The present invention provides a method and device for measuring the three-dimensional distribution of nanoparticle sizes in a solution, and the specific implementation steps of the technology of the present invention are given in detail in combination with the accompanying drawings.

[0058] Example 1

[0059] As Figure 1 and Figure 2 shown, the method for measuring the three-dimensional distribution of nanoparticle sizes in a solution using the device provided by the present invention includes the following steps:

[0060] Step 1: Turn on the laser 1, and the laser beam is split into two beams by the first beam splitter 2. One beam is converged by the convex lens 3 and irradiated on the nanoparticles to generate scattered light, as Figure 1As shown in a of ; another beam forms a reference light after passing through a spatial filter composed of a microscopic objective lens 6 and a pinhole 7 by a first reflector 4 and a second reflector 5, and then passing through a collimating lens 8 and an attenuation sheet 9; the scattered light and the reference light are adjusted to the same axis in front of the sample cell 11 by a second beam splitter 10, and the scattered light generated by the nanoparticles forms holographic interference fringes as an object light interfering with a reference parallel light beam at an angle θ, and is recorded by a high-speed camera 12. Recorded by a CCD high-speed camera at time intervals of Δτ, the camera sampling frequency is 20 kHz, and a holographic signal map at each moment is obtained, as shown in Figure 1 b of .

[0061] Wherein: the laser wavelength of the laser 1 is in the visible light band of 350 nm - 700 nm, and the power is 1 - 500 mW. The laser wavelength and power can be adjusted according to the scattering characteristics of the nanoparticles. The first beam splitter 2 divides the laser into two beams, and the second beam splitter 10 adjusts the reference light to be on the same axis as the scattered light of the measured scattering angle. The convex lens 3 converges the laser to avoid too low laser energy and unable to measure the scattered light generated by the nanoparticles. The spatial filter includes a microscopic objective lens 6 and a pinhole 7. The magnification of the microscopic objective lens is 10× - 50×, and the pinhole aperture is 5 μm - 10 μm. The spatial filter can filter out light of other spatial frequencies and improve the beam quality. The collimating lens 8 collimates the diffused light into a parallel light beam. The light transmittance of the attenuation sheet 9 is selected from 1% - 35%, which matches the laser intensity, the exposure time of the high-speed camera, and the visibility of the hologram. In the sample cell 11, there are nanoparticles containing a known medium. The high-speed camera 12 is a CCD or CMOS high-speed camera. The photosensitive chip is perpendicular to the propagation direction of the measured scattered light, and the sampling frequency is 20 kHz - 50 kHz, and the exposure time is less than 500 ns.

[0062] Step 2: The high-speed camera 12 transmits the holographic signal map to the signal processing unit for processing:

[0063] Step 2-1: Remove background noise and DC phase.

[0064] Step 2-2: Perform three-dimensional reconstruction on the digital hologram of the nanoparticles to obtain a focused image of the nanoparticles on any x-y cross-section, as shown in Figure 1 c of .

[0065] Specifically, the convolution reconstruction method is used for three-dimensional reconstruction. In the holographic reconstruction image formula, |RR * |O contains object light information. Using the Rayleigh-Sommerfeld diffraction formula, the complex amplitude distribution for reconstructing the hologram can be expressed as:

[0066]

[0067] Where (x,y) and (u,v) are the coordinates of the holographic plane and the reconstruction plane respectively, and z rLet \(z\) be the reconstruction distance, and \(\Gamma\) represent the complex amplitude distribution of the reconstructed light field;

[0068] Rewrite the above formula into a convolution form:

[0069]

[0070] where \(g(u, v, z r ) is:

[0071]

[0072] Perform two Fourier transforms and an inverse Fourier transform on the above formula for numerical calculation:

[0073]

[0074] Obtain the focused images of the x - y cross - sections of the hologram at different reconstruction distances \(z r .

[0075] Step 2 - 3: Based on the scattering signals given by the focused images, according to the principle of dynamic light scattering, and relying on the correlation between the nanoparticle size \(d\) and the diffusion coefficient \(D T , obtain the size of the cross - section nanoparticles.

[0076] Specifically:

[0077] (2 - 3 - 1) Obtain the autocorrelation function from the scattering signals of the focused images of the x - y cross - section:

[0078] The correlation analysis coefficient \(G(\tau)\) is:

[0079] \(G(\tau)=\exp(-2\Gamma\tau)

[0080] where \(\Gamma\) is the decay linewidth and \(\tau\) is the decay time;

[0081] \(\Gamma\) satisfies the equation:

[0082]

[0083] where \(D T is the particle diffusion coefficient; \(q\) is the scattering vector; \(\theta\) is the scattering angle; \(\lambda\) is the wavelength of light in vacuum; \(n\) is the refractive index of the dispersion medium;

[0084] (2 - 3 - 2) Using the autocorrelation function as the baseline, from the Stokes - Einstein equation, obtain the relationship between the particle size and the diffusion coefficient:

[0085] The particle diffusion coefficient \(D T is:

[0086]

[0087] Among them, K B is the Boltzmann constant; T is the absolute temperature; η is the viscosity; d is the particle size of the nanoparticle to be measured;

[0088] (2-3-3) According to the relationship between the particle size and the diffusion coefficient, the nanoparticle size d is obtained:

[0089]

[0090] Finally, the nanoparticle size distribution of each cross-section in the sample pool is obtained.

[0091] The above is a detailed description of the present invention in combination with the implementation cases. However, the implementation mode of the present invention is not limited by the above implementation cases. For example, the scattering angle measured in step 1 is 10°. With the change of the sampling frequency of the high-speed CCD or CMOS camera, the recorded scattering angle θ can be adjusted, but at the same time, the mirror angle needs to be adjusted to ensure that the object light and the reference light are on the same axis. The holographic three-dimensional reconstruction algorithm in step 2 is not limited to the convolution reconstruction method. Any changes, replacements, combinations, simplifications, etc. made under the core guiding ideology of this invention patent are included in the protection scope of this invention patent.

Claims

1. A method for measuring the three-dimensional distribution of the particle size of nanoparticles in a solution, characterized in that, the method comprises the following steps: (1) Irradiate the nanoparticles in the sample cell with a laser beam. The scattered light formed by the nanoparticles interferes with the reference light modulated by the optical path to form holographic interference fringes, and the holographic interference fringes are recorded on the photosensitive chip of the camera at a time interval of Δτ and an angle θ, obtaining a series of digital holograms of the nanoparticles undergoing Brownian motion during the measurement period; (2) Perform three-dimensional reconstruction on the digital holograms of the nanoparticles recorded in step (1) to obtain a focused image of the nanoparticles in the sample cell on any x-y cross-section, where the x-y cross-section is a cross-section perpendicular to the incident light; (3) Based on the scattering signals in the focused image in step (2), according to the principle of dynamic light scattering, and based on the correlation between the particle size d of the nanoparticles and the diffusion coefficient D T the particle size d of the nanoparticles in the cross-section is obtained; The method for performing three-dimensional reconstruction on the digital holograms of the nanoparticles in step (2) to obtain a focused image of the nanoparticles in the sample cell on any x-y cross-section is as follows: Three-dimensional reconstruction is performed using the convolution reconstruction method. The third term |RR in the holographic reconstruction image * |O contains the object light information. The reconstruction of the complex amplitude distribution of the hologram using the Rayleigh-Sommerfeld diffraction formula is expressed as: where (x, y) and (u, v) are the coordinates of the holographic plane and the reconstruction plane respectively, z r is the reconstruction distance, and Γ represents the complex amplitude distribution of the reconstructed light field; Rewrite the above formula into a convolution form: where g(u, v, z r ) is as follows: Perform two Fourier transforms and an inverse Fourier transform on the above formula for numerical calculation: Γ(m,n) = F -1 {F{U R I H}}·F{g}}(m,n) Obtain the focused images of the x-y cross-sections of the hologram at different reconstruction distances z r ​ 2. The method for measuring the three-dimensional distribution of the particle size of nanoparticles in a solution according to claim 1, characterized in that, in step (1), the bright fringes of the digital holograms of the nanoparticles are: I H = |O + R| 2 = I O + I R + OR * + O * R When using the same beam as the original reference light to reconstruct the holographic image, the holographic reconstruction image satisfies: I H R = |OO * |R + |RR * |R + |RR * |O + O * |RR * | where O is the complex amplitude distribution of the scattered light; R is the reference light; the first and second terms are the DC phases; the third term forms an imaginary phase; the fourth term forms a real image.

3. The method for measuring the three-dimensional distribution of the particle size of nanoparticles in a solution according to claim 1, characterized in that, the method for obtaining the particle size d of the nanoparticles in the cross-section in step (3) is: (3-1) Obtain the autocorrelation function from the scattering signal of the focused image of the x-y cross-section: The correlation analysis coefficient G(τ) is: G(τ) = exp(-2Γτ) where Γ is the decay linewidth and τ is the decay time; Γ satisfies the equation: Γ = D T q 2 、 where D T is the particle diffusion coefficient; q is the scattering vector; θ is the scattering angle; λ is the wavelength of light in vacuum; n is the refractive index of the dispersion medium; (3-2) Using the autocorrelation function as the baseline, obtain the relationship between the particle size and the diffusion coefficient from the Stokes-Einstein equation: Particle diffusion coefficient D T : where K B is the Boltzmann constant; T is the absolute temperature; η is the viscosity; d is the particle size of the nanoparticle to be measured; (3-3) According to the relationship between the particle size and the diffusion coefficient, obtain the particle size d of the nanoparticles: Finally, obtain the particle size distribution of the nanoparticles in each cross-section of the sample cell.

4. The method for measuring the three-dimensional distribution of the particle size of nanoparticles in a solution according to claim 1, characterized in that, the device for measuring the three-dimensional distribution of the particle size of nanoparticles in a solution comprises a signal emission unit, a signal reception unit and a signal processing unit; the signal emission unit includes a continuous laser and an optical path adjustment section. A part of the laser beam generated by the continuous laser is converged and irradiated on the nanoparticles to form scattered light, and the other part of the laser beam passes through the optical path adjustment section as the reference light. The scattered light and the reference light interfere to form holographic interference fringes; the signal reception unit includes a camera, which records the holographic interference fringes at a time interval of Δτ, obtaining a series of digital holograms of the nanoparticles undergoing Brownian motion during the measurement period; the signal processing unit is connected after the signal reception unit and is used for processing the digital holograms of the nanoparticles: including removing background noise; Perform three-dimensional reconstruction on the digital hologram of nanoparticles to obtain the focused images of nanoparticles on any x-y cross-section; based on the scattering signals given by the focused images, according to the principle of dynamic light scattering, and based on the correlation between the particle size d of nanoparticles and the diffusion coefficient D T , the particle size of the cross-section nanoparticles is obtained.

5. The method for measuring the three-dimensional distribution of the particle size of nanoparticles in a solution according to claim 4, It is characterized in that the laser wavelength of the continuous laser is in the visible light band of 350 nm - 700 nm, and the power is 1 - 500 mW.

6. The method for measuring the three-dimensional distribution of nanoparticle size in a solution according to claim 5, It is characterized in that the laser beam generated by the continuous laser is split into a first laser beam and a second laser beam by a first beam splitter. The first laser beam is converged by a convex lens and then irradiates the nanoparticles to form scattered light; the second laser beam forms a reference light after passing through a reflector, a spatial filter, a collimating lens and an attenuation sheet in sequence; the scattered light and the reference light are adjusted to be on the same main optical axis by a second beam splitter.

7. The method for measuring the three-dimensional distribution of nanoparticle size in a solution according to claim 6, It is characterized in that the spatial filter is composed of a microscope objective lens and a pinhole.

8. The method for measuring the three-dimensional distribution of nanoparticle size in a solution according to claim 4, It is characterized in that the camera is a CCD or CMOS high-speed camera, the sampling frequency is 20 kHz - 50 kHz, and the exposure time is less than 500 ns.

9. The method for measuring the three-dimensional distribution of nanoparticle size in a solution according to claim 8, It is characterized in that the photosensitive chip of the CCD or CMOS high-speed camera is perpendicular to the propagation direction of the scattered light.

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