Method for determining physical characteristics of particles based on Mie scattering
By combining the interference effect of side and back scattering phase functions with Mie scattering, the synchronous measurement of particle size and refractive index was achieved, solving the problems of accuracy and equipment complexity in traditional light scattering technology, improving measurement accuracy and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-12
- Publication Date
- 2026-04-21
AI Technical Summary
Traditional light scattering techniques cannot avoid the interaction between multiple particles, which limits the accuracy and precision of particle characterization. Furthermore, existing equipment is complex and costly, affecting the accuracy of particle size and refractive index measurements and the feasibility of mass production.
A Mie scattering-based method is employed, in which a single particle is captured by a particle generation device. Lateral scattering phase function images are acquired using a side imaging objective and an optical camera. The lateral spherical scattering electric field distribution of the particle is calculated using Mie scattering theory. Interference-corrected backscattering phase function images are acquired using a back imaging objective and an optical camera. The particle size and refractive index are then jointly solved using the interference effect.
It achieves high-precision measurement of particle size and refractive index, avoids the interaction between different particles, reduces equipment complexity and cost, and improves measurement accuracy and resolution.
Smart Images
Figure CN121898963A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of particle physical property measurement technology, specifically to a method for determining particle physical properties based on Mie scattering. Background Technology
[0002] Particle characterization techniques have important applications in many fields such as biomedicine, industrial production, and environmental science. Light scattering technology characterizes particle properties such as size, refractive index, and shape by measuring the scattered light produced when a light beam is incident on the particle surface. It features fast measurement speed, wide applicability, and online measurement capabilities. However, traditional light scattering techniques cannot avoid the interactions between multiple particles, limiting the accuracy and precision of particle characterization. Optical tweezers systems, on the other hand, provide a powerful tool for in-situ particle characterization at the single-particle level, enabling particle characterization studies on a single particle scale.
[0003] The current conventional method involves capturing single particles using optical tweezers and measuring their Raman spectra by detecting the captured particles. However, this method requires a Raman spectrometer, which is complex and expensive, significantly impacting the production cost and mass production feasibility of particle size and refractive index measurement devices. Summary of the Invention
[0004] In view of this, this application provides a method for determining the physical properties of particles based on Mie scattering. It aims to solve or partially solve the problems existing in the prior art.
[0005] The first aspect of this application provides a method for determining the physical properties of particles based on Mie scattering, the method comprising: Particles are generated using a particle generating device, and individual particles are captured within them; By using a side imaging objective and a first optical camera, the side scattering phase function of the captured particles is imaged on the defocus plane to obtain the corresponding side scattering phase function image. The normalized first gray value distribution curve is extracted from the side scattering phase function image. The horizontal axis of the first gray value distribution curve is the distance between the data point in the side scattering phase function image and the center point of the image, and the vertical axis is the normalized gray value of the data point. Using Mie scattering theory, the distribution of the lateral spherical scattering electric field of the particle at the first target position is calculated under different particle physical property values. The first target position is the position where the lateral scattering phase function image is acquired. The lateral spherical scattering electric field is the scattering electric field when an x-polarized plane wave propagating along the z-axis is scattered by the particle. Based on the lateral spherical outward scattering electric field distribution corresponding to the particle physical property values, the corresponding first light intensity distribution curve is determined; Determine the first distance between the first gray value distribution curve and each of the first light intensity distribution curves; Determine the first target distance from all first distances that satisfies the first condition; The particle physical property value corresponding to the first target distance is determined as the first candidate physical property value of the captured particle; By using a back-facing imaging objective and a second optical camera, the interference-corrected backscattering phase function of the captured particle is imaged on the defocus plane to obtain the corresponding interference-corrected backscattering phase function image. The interference-corrected backscattering phase function image includes the interference effect between the backscattered light of the captured particle and the reflected light from a certain reflecting plane below the particle. The normalized second gray value distribution curve is extracted from the interferometric modified backscattering phase function image. The horizontal axis of the second gray value distribution curve is the distance between the data point in the interferometric modified backscattering phase function image and the center point of the image, and the vertical axis is the normalized gray value of the data point. Using Mie scattering theory, the distribution of the interference-corrected backscattered electric field at the second target position is calculated for different particle physical property values. The second target position is the position where the interference-corrected backscattering phase function image is acquired. The interference-corrected backscattered electric field consists of the backscattered electric field and the scattered electric field of the plane wave reflected by the reflecting plane below the captured particle in spherical coordinates. Based on the interference correction backscattering electric field distribution corresponding to the particle physical properties, the corresponding second light intensity distribution curve is determined. Determine the second distance between the second gray value distribution curve and each of the second light intensity distribution curves; Determine the second target distance from all second distances that satisfies the second condition; The particle physical property value corresponding to the second target distance is determined as the second candidate physical property value of the captured particle; The physical property values of the captured particles are determined based on all the first candidate physical property values and all the second candidate physical property values.
[0006] The method for determining particle physical properties based on Mie scattering provided in this application has the following advantages: This application provides a method for determining the physical properties of particles based on Mie scattering. First, particles are generated using a particle generation device, and individual particles are captured. Then, using a side-view imaging objective and a first optical camera, the side-scattering phase function of the captured particles is imaged on a defocus plane to obtain the corresponding side-scattering phase function image. A normalized first grayscale distribution curve is extracted from the side-scattering phase function image. The horizontal axis of the first grayscale distribution curve represents the distance between data points in the side-scattering phase function image and the image center point, and the vertical axis represents the normalized grayscale value of the data points. Finally, using Mie scattering theory, the side-scattering electric field at the first target location of the particle under different particle physical property values is calculated. The distribution is as follows: the first target position is the position where the lateral scattering phase function image is acquired; the lateral spherical scattering electric field is the scattering electric field when an x-polarized plane wave propagating along the z-axis is scattered by a particle; based on the lateral spherical scattering electric field distribution corresponding to the particle physical property values, the corresponding first light intensity distribution curve is determined; the first distance between the first gray value distribution curve and each of the first light intensity distribution curves is determined; the first target distance satisfying the first condition is determined from all the first distances; the particle physical property value corresponding to the first target distance is determined as the first candidate physical property value of the captured particle; based on all the first candidate physical property values, the physical property value of the captured particle is determined.
[0007] The particle physical property determination method based on Mie scattering provided in this application utilizes the interference effect between the backscattered light from the particle and the planar reflected light in the system. It simultaneously acquires the lateral scattering phase function and the interference-corrected backscattering phase function of the particle. Based on the interference-corrected Mie scattering theory, the particle size and refractive index are inverted in the back direction; based on the standard Mie scattering theory, the particle size and refractive index are inverted in the lateral direction. By jointly solving for both directions, more accurate measurements of particle size and refractive index can be achieved. Compared to traditional particle characterization schemes, this method offers the following advantages: It utilizes the interference effect between the backscattered light from the particle and the planar reflected light in the system to acquire and jointly solve the lateral scattering phase function and the interference-corrected backscattering phase function, achieving simultaneous measurement of particle size and refractive index; it employs an optical tweezers system to measure individual particles, effectively avoiding interactions between different particles and improving the accuracy and precision of particle characterization; it has a simple structure, short measurement time, and low cost, while also possessing significant advantages such as high resolution and high precision. Attached Figure Description
[0008] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0009] Figure 1 The flowchart illustrates a method for determining particle physical properties based on Mie scattering, as shown in one embodiment of this application. Figure 2 This is a schematic diagram of the lateral scattering phase function image in a particle physics property determination method based on Mie scattering, as shown in one embodiment of this application. Figure 3 This is another schematic diagram illustrating the lateral scattering phase function image in a method for determining particle physical properties based on Mie scattering, as shown in one embodiment of this application. Figure 4 This is a schematic diagram of an interferometrically modified backscattering phase function image in a method for determining particle physical properties based on Mie scattering, as illustrated in one embodiment of this application. Figure 5 This is another schematic diagram illustrating the interferometric correction of the backscattering phase function image in a particle physics property determination method based on Mie scattering, as shown in one embodiment of this application. Figure 6 This is another flowchart illustrating a method for determining particle physical properties based on Mie scattering, as shown in one embodiment of this application. Detailed Implementation
[0010] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0011] refer to Figure 1 , Figure 1 This is a flowchart illustrating a method for determining particle physical properties based on Mie scattering, as shown in one embodiment of this application. Figure 1 As shown, the method includes: Step S01: Generate particles using a particle generation device and capture individual particles within them.
[0012] In this embodiment, based on the discovery that the scattering phase function is highly correlated with the particle size and refractive index, this application proposes a method for determining the particle physical properties by inverting the scattering phase function of a particle. Specifically, spherical particles are first generated using a particle generation device. Since optical tweezers are subsequently used to capture individual particles from all the generated particles, the particle size of the spherical particles generated by the particle generation device can be any size that can be captured by optical tweezers. After the spherical particles are generated by the particle generation device, individual particles are captured from all the generated particles using optical tweezers for subsequent determination of their particle physical properties. These particle physical properties include at least particle size and refractive index.
[0013] Step S02: Using a side-view imaging objective and a first optical camera, image the side-scattering phase function of the captured particles on the defocus plane to obtain the corresponding side-scattering phase function image.
[0014] In this embodiment, after generating and capturing a single particle in step S01, the lateral scattering phase function of the captured particle is imaged on the defocus plane using a lateral imaging objective and a first optical camera. The image is then converted to grayscale to obtain the corresponding lateral scattering phase function image, as shown below. Figure 2 As shown, Figure 2 A schematic diagram of a side-scattering phase function image is shown. The first optical camera uses a CCD or CMOS sensor. The side-imaging objective captures the particle scattering phase function at an angle between 0° and 180°, preferably 90°.
[0015] Step S03: Extract the normalized first gray value distribution curve from the side scattering phase function image. The horizontal axis of the first gray value distribution curve is the distance between the data point in the side scattering phase function image and the center point of the image, and the vertical axis is the normalized gray value of the data point.
[0016] In this embodiment, after obtaining the lateral scattering phase function image of the captured particle in step S02, a normalized first grayscale value distribution curve is extracted from the grayscale image of the lateral scattering phase function image, as shown below. Figure 3 As shown, the specific process for extracting the normalized first gray value distribution curve is as follows: A straight line is selected from the center point of the lateral scattering phase function image to the image edge (e.g., ...). Figure 3The white dashed line in the image represents the data points. Data points are taken along this line, and their positions and grayscale values are recorded. After recording the positions and grayscale values of all data points, the grayscale values of all data points are normalized to obtain their respective normalized grayscale values. Then, based on the distance between each data point and the image center point, and the normalized grayscale value, a corresponding first grayscale value distribution curve is generated. In this first grayscale value distribution curve, the horizontal axis represents the distance between the data point in the lateral scattering phase function image and the image center point, and the vertical axis represents the normalized grayscale value of the data point. One optional method for taking data points is to treat each pixel on the selected line as a data point, and the distance between the data point and the image center point is the corresponding pixel distance, such as a data point being 3 pixels away from the image center point.
[0017] Step S04: Using Mie scattering theory, calculate the lateral spherical scattering electric field distribution of the particle at the first target position under different particle physical property values. The first target position is the position where the lateral scattering phase function image is acquired. The lateral spherical scattering electric field is the scattering electric field when an x-polarized plane wave propagating along the z-axis is scattered by the particle.
[0018] In this embodiment, this application uses standard Mie scattering theory to calculate the lateral out-of-sphere scattered electric field distribution of particles at a first target location under different particle physical property values, thereby obtaining the lateral out-of-sphere scattered electric field distribution corresponding to each particle physical property value. The first target location is the position where the lateral scattering phase function image is acquired. The lateral out-of-sphere scattered electric field distribution of the particles is the scattered electric field when an x-polarized plane wave propagating along the z-axis is scattered by the particles. Specifically, when the particle physical properties include particle size and refractive index, calculating the lateral out-of-sphere scattered electric field distribution of particles at the first target location under one particle physical property value is essentially calculating the lateral out-of-sphere scattered electric field distribution of particles at the first target location under both a particle size value and a refractive index value.
[0019] Step S05: Determine the corresponding first light intensity distribution curve based on the lateral spherical outward scattering electric field distribution corresponding to the particle physical property values.
[0020] In this embodiment, this application finds that the laser light intensity acquired by the optical camera is proportional to the square of the scattered electric field outside the particle. Therefore, this application uses the square of the lateral spherical scattered electric field of the data point in the lateral spherical scattered electric field distribution determined in step S04 as the light intensity of that data point. Thus, based on a lateral spherical scattered electric field distribution result, a corresponding first light intensity distribution curve can be determined. In the first light intensity distribution curve, the horizontal axis records the distance of the data point from the image center position of the plane where the first target position is located, and the vertical axis records the light intensity of the data point. Step S04 calculates the lateral spherical scattered electric field distribution under multiple different particle physical property values. Therefore, this application will determine a first light intensity distribution curve corresponding to itself for each particle physical property value.
[0021] In this embodiment, since the first light intensity distribution curve calculated by this application will be used to calculate the distance with the first grayscale value distribution curve, the number of data points in the first light intensity distribution curve determined by this application is the same as the number of data points in the first grayscale value distribution curve. Correspondingly, the number of data points in each lateral spherical outward scattered electric field distribution calculated in step S04 is also the same as the number of data points in the first grayscale value distribution curve.
[0022] Step S06: Determine the first distance between the first gray value distribution curve and each of the first light intensity distribution curves.
[0023] In this embodiment, after obtaining the first light intensity distribution curve corresponding to each particle's physical characteristic value through step S05, the first distance between the actual first grayscale value distribution curve and each of the first light intensity distribution curves is determined, thereby obtaining the first distance for each particle's physical characteristic value. The first distance is the Euclidean distance.
[0024] Step S07: Determine the first target distance that satisfies the first condition from all first distances.
[0025] In this embodiment, after obtaining the first distance corresponding to each particle's physical property value through step S06, a first target distance that meets the first condition is selected from all the first distances based on a preset first condition. Optionally, the first condition includes: sorting all the first distances from largest to smallest and selecting a preset number of first distances at the end of the sort to determine the first target distance, or determining the first distances below a preset threshold among all the first distances as the first target distance.
[0026] Step S08: Determine the particle physical characteristic value corresponding to the first target distance as the first candidate physical characteristic value of the captured particle.
[0027] In this embodiment, after determining the first target distance through step S07, the particle physical property value corresponding to the first target distance is determined as the first candidate physical property value of the captured particle.
[0028] Step S09: Using a back-facing imaging objective and a second optical camera, image the interference-corrected backscattering phase function of the captured particle on the defocus plane to obtain the corresponding interference-corrected backscattering phase function image. The interference-corrected backscattering phase function image includes the interference effect between the backscattered light of the captured particle and the reflected light from a certain reflecting plane below the particle.
[0029] In this embodiment, this application found that determining the particle physical property values of the captured particles from the lateral angle in steps S02 to S08 exhibits periodicity, resulting in multiple candidate physical property values that meet the conditions, i.e., multiple solutions appear simultaneously. This application conceived of combining the lateral and back-angle angles to break the periodicity of a single lateral dimension, thereby obtaining more accurate measurement results. However, this application further found that the fringes of the backscattering phase function image are very shallow, with a low signal-to-noise ratio and weak signal strength, making it unfavorable to solve for the particle physical properties of the captured particles using methods similar to those described above. Therefore, based on this, this application further performs interferometry processing on the back-angle to enhance the signal-to-noise ratio of the back-angle, making the back-angle fringes deeper, thereby facilitating the use of methods similar to those described above to solve for more accurate particle physical properties of the captured particles at the back-angle. Specifically, after generating and capturing a single particle in step S01, this application acquires the interferometric correction backscattering phase function at the same time as acquiring the side scattering phase function. The acquisition process involves imaging the interferometric correction backscattering phase function of the captured particle captured in step S01 on the defocus plane using a back-facing imaging objective and a second optical camera, and then performing grayscale processing on the image to obtain the corresponding interferometric correction backscattering phase function image. This interferometric correction backscattering phase function image includes the interference effect between the backscattered light of the captured particle and the reflected light from a certain reflecting plane below the captured particle, such as... Figure 4 As shown, Figure 4 A schematic diagram of an interferometrically corrected backscattering phase function image is shown. The second optical camera uses either a CCD or CMOS sensor. The acquisition angle for the interferometrically corrected backscattering phase function image is 180°.
[0030] Step S010: Extract the normalized second gray value distribution curve from the interferometric modified backscattering phase function image. The horizontal axis of the second gray value distribution curve is the distance between the data point in the interferometric modified backscattering phase function image and the center point of the image, and the vertical axis is the normalized gray value of the data point.
[0031] In this embodiment, after obtaining the interferometric modified backscattering phase function image of the captured particles in step S09, a normalized second grayscale value distribution curve is extracted from the grayscale image of the interferometric modified backscattering phase function image, as shown below. Figure 5 As shown, the specific process for extracting the normalized second grayscale value distribution curve is as follows: A straight line is selected from the center point of the interferometric modified backscattering phase function image to the image edge (e.g., ...). Figure 5 The white dashed line in the image represents the data points. Data points are taken along this line, and their positions and grayscale values are recorded. After recording the positions and grayscale values of all data points, the grayscale values of all data points are normalized to obtain the normalized grayscale values for each data point. Then, based on the distance between each data point and the image center point, and the normalized grayscale value, a corresponding second grayscale value distribution curve is generated. In this second grayscale value distribution curve, the horizontal axis represents the distance between the data point in the interferometric modified backscattering phase function image and the image center point, and the vertical axis represents the normalized grayscale value of the data point. One optional method for taking data points is to treat each pixel on the selected line as a data point, and the distance between the data point and the image center point is the corresponding pixel distance.
[0032] Step S011: Using Mie scattering theory, calculate the interference-corrected backscattering electric field distribution of the particle at the second target position under different particle physical property values. The second target position is the position where the interference-corrected backscattering phase function image is acquired. The interference-corrected backscattering electric field consists of the backscattering electric field and the scattering electric field of the plane wave reflected by the reflecting plane below the captured particle in spherical coordinates.
[0033] In this embodiment, this application uses the interferometric modified Mie scattering theory to calculate the interferometric modified backscattering electric field distribution of particles at the second target location under different particle physical property values, thereby obtaining the interferometric modified backscattering electric field distribution corresponding to each particle physical property value. The second target location is the location where the interferometric modified backscattering phase function image is acquired. The interferometric modified backscattering electric field of the particle consists of the backscattering electric field and the scattered electric field of the plane wave reflected by the reflecting plane below the captured particle in spherical coordinates. Specifically, when the particle physical properties include particle size and refractive index, calculating the interferometric modified backscattering electric field distribution of particles at the second target location under a given particle physical property value is essentially calculating the interferometric modified backscattering electric field distribution of particles at the second target location under both a given particle size value and a given refractive index value.
[0034] Step S012: Determine the corresponding second light intensity distribution curve based on the interference correction back spherical scattering electric field distribution corresponding to the particle physical property values.
[0035] In this embodiment, this application finds that the laser light intensity acquired by the optical camera is proportional to the square of the scattered electric field outside the particle. Therefore, this application uses the square of the interferometrically corrected backspherical scattered electric field of the data point in the interferometrically corrected backspherical scattered electric field distribution determined in step S011 as the light intensity of that data point. Thus, based on an interferometrically corrected backspherical scattered electric field distribution result, a corresponding second light intensity distribution curve can be determined. In the second light intensity distribution curve, the horizontal axis records the distance of the data point from the image center position of the plane where the second target position is located, and the vertical axis records the light intensity of the data point. Step S011 calculates and obtains the interferometrically corrected backspherical scattered electric field distribution under multiple different particle physical property values. Therefore, this application will determine a second light intensity distribution curve corresponding to each particle physical property value.
[0036] In this embodiment, since the second light intensity distribution curve calculated by this application will be used to calculate the distance with the second gray value distribution curve, the number of data points in the second light intensity distribution curve determined by this application is the same as the number of data points in the second gray value distribution curve. Correspondingly, the number of data points in each interference-corrected backscattered electric field distribution obtained in step S011 is also the same as the number of data points in the second gray value distribution curve.
[0037] Step S013: Determine the second distance between the second gray value distribution curve and each of the second light intensity distribution curves.
[0038] In this embodiment, after obtaining the second light intensity distribution curve corresponding to each particle's physical characteristic value through step S012, the second distance between the actual second grayscale value distribution curve and each of the second light intensity distribution curves is determined, thereby obtaining the second distance for each particle's physical characteristic value. The second distance is the Euclidean distance.
[0039] Step S014: Determine the second target distance that satisfies the second condition from all the second distances.
[0040] In this embodiment, after obtaining the second distance corresponding to each particle's physical property value through step S013, a second target distance that meets the second condition is selected from all the second distances based on a preset second condition. Optionally, the second condition includes: sorting all the second distances from largest to smallest and selecting a preset number of second distances at the end of the sorted list as the second target distance, or selecting the second distances below a preset threshold from all the second distances as the second target distance.
[0041] Step S015: Determine the particle physical property value corresponding to the second target distance as the second candidate physical property value of the captured particle.
[0042] In this embodiment, after determining the second target distance through step S014, the particle physical property value corresponding to the second target distance is determined as the second candidate physical property value of the captured particle.
[0043] Step S016: Determine the physical property value of the captured particle based on all the first candidate physical property values and all the second candidate physical property values.
[0044] In this embodiment, each value in all the first candidate physical property values is compared with each value in all the second candidate physical property values to determine the candidate physical property value that is closest to each other, and the closest candidate physical property value is determined as the physical property value of the captured particle.
[0045] The particle physical property determination method based on Mie scattering provided in this application utilizes the interference effect between the backscattered light from the particle and the planar reflected light in the system. It simultaneously acquires the lateral scattering phase function and the interference-corrected backscattering phase function of the particle. Based on the interference-corrected Mie scattering theory, the particle size and refractive index are inverted in the back direction; based on the standard Mie scattering theory, the particle size and refractive index are inverted in the lateral direction. By jointly solving for both directions, more accurate measurements of particle size and refractive index can be achieved. Compared to traditional particle characterization schemes, this method offers the following advantages: It utilizes the interference effect between the backscattered light from the particle and the planar reflected light in the system to acquire and jointly solve the lateral scattering phase function and the interference-corrected backscattering phase function, achieving simultaneous measurement of particle size and refractive index; it employs an optical tweezers system to measure individual particles, effectively avoiding interactions between different particles and improving the accuracy and precision of particle characterization; it has a simple structure, short measurement time, and low cost, while also possessing significant advantages such as high resolution and high precision. The purpose of this application is to overcome the current problems of insufficient methods for simultaneous measurement of single-particle size and refractive index, difficulty in accurate decoupling of scattering signals, complex and costly equipment, and susceptibility of experimental results to subjective input and signal processing methods. This application proposes a new method based on the diffraction imaging theory of the scattered light from the captured particle and the interference effect between the particle's backscattered light and the plane reflected light in the system. A single-beam optical tweezers is used to capture a single particle, and an imaging objective and an optical camera are used to simultaneously acquire the particle's lateral scattering phase function and the interference-corrected backscattering phase function. An inversion method for particle size and refractive index based on the interference-corrected Mie scattering theory is established. The lateral and interference-corrected backscattering phase functions of the same particle are jointly solved, and a fitting method is used to achieve high-precision measurement and decoupling of particle size and refractive index.
[0046] In conjunction with the above embodiments, in one implementation, this application also provides a method for determining particle physical properties based on Mie scattering. In this method, step S01 may include: generating particles using a particle generation device; activating a laser source to emit a laser beam; and focusing the laser beam using a vertically placed back-facing imaging objective lens to capture individual particles near the beam focus from below using optical force.
[0047] In this embodiment, particles are first generated using a particle generation device. Then, a laser light source is activated to emit a laser beam. The laser beam is focused by a vertically placed back-facing imaging objective, thereby using optical force to capture one of the generated particles near the focal point of the beam from below. This back-facing imaging objective is a high numerical aperture microscope objective, whose numerical aperture ensures stable particle capture, such as an oil immersion objective. The wavelength of the laser light source avoids the wavelengths where the particles strongly absorb light.
[0048] In conjunction with the above embodiments, in one implementation, this application also provides a method for determining particle physical properties based on Mie scattering. In this method, step S09 may include: placing a cover glass between the front end of a back-facing imaging objective and the captured particle, so that the backscattered light from the captured particle and the reflected light from the cover glass form an interference effect; and imaging the interference-corrected backscattering phase function of the captured particle onto a second optical camera through the back-facing imaging objective to obtain an interference-corrected backscattering phase function image.
[0049] In this embodiment, the core of the interferometric modified backscatter phase function image in this application lies in the interference effect formed between the backscattered light from the captured particle and the reflected light from a reflective plane below the captured particle. There are many ways to achieve this reflection effect; here, a low-cost implementation is described: a cover glass is placed between the front end of the back-imaging objective and the captured particle, causing an interference effect between the backscattered light from the captured particle and the reflected light from the cover glass below the captured particle. Then, the interferometric modified backscatter phase function of the captured particle is imaged onto a second optical camera through the back-imaging objective, thereby obtaining the interferometric modified backscatter phase function image.
[0050] In conjunction with the above embodiments, in one implementation, this application also provides a method for determining particle physical properties based on Mie scattering. In this method, step S06 may include: calculating the first distance between the first grayscale value distribution curve and each of the first light intensity distribution curves using a first distance algorithm; The expression for the first distance algorithm is: ,in, The first distance is the distance between the first grayscale value distribution curve and the corresponding lateral spherical outward scattered electric field distribution. The normalized gray value of the j-th data point in the first gray value distribution curve. For the light intensity corresponding to the j-th data point in the first light intensity distribution curve, , Let P be the lateral spherical outward scattered electric field at the j-th data point in the lateral spherical outward scattered electric field distribution, and let P be the total number of data points.
[0051] In this embodiment, the present application pre-constructs a first distance algorithm for calculating the first distance between the first gray value distribution curve and each of the first light intensity distribution curves. The algorithm uses Euclidean distance to calculate the first distance between the two curves.
[0052] In conjunction with the above embodiments, in one implementation, this application also provides a method for determining particle physical properties based on Mie scattering. In this method, step S013 may include: calculating the second distance between the second grayscale value distribution curve and each of the second light intensity distribution curves using a second distance algorithm; The expression for the second distance algorithm is: ,in, This represents the second distance between the second grayscale value distribution curve and the corresponding interferometric correction backscattered electric field distribution. This represents the normalized gray value of the j-th data point in the second gray value distribution curve. For the light intensity corresponding to the j-th data point in the second light intensity distribution curve, , The interference correction for the backspherical external scattered electric field distribution is given by P, where P is the total number of data points.
[0053] In this embodiment, this application pre-constructs a second distance algorithm for calculating the distances between the second grayscale value distribution curve and each of the second light intensity distribution curves. This algorithm uses Euclidean distance to calculate the second distance between the two curves. Interference correction of the backscattered electric field distribution on the sphere. ,in, Lateral spherical external scattered electric field and phase difference, The phase difference introduced by the optical path difference between the trapped particles and the upper surface of the coverslip. The electric field scattered by the plane wave reflected by the reflecting plane below the trapped particle in spherical coordinates.
[0054] In conjunction with the above embodiments, in one implementation, this application also provides a method for determining particle physical properties based on Mie scattering. In this method for determining particle physical properties based on Mie scattering, before step S04, the method further includes: determining the lateral observation distance corresponding to the first grayscale value distribution curve; and determining the first imaging range of the first optical camera, wherein the lateral observation distance is the distance from the first optical camera's sharp focusing position to the position where the lateral scattering phase function image is acquired; and determining the scattering angle and azimuth angle based on the lateral observation distance, the first imaging range, and the size of the lateral scattering phase function image for calculating the lateral outward scattering electric field distribution.
[0055] In this embodiment, the scattering angle and azimuth angle are required to calculate the lateral outward scattering electric field distribution using standard Mie scattering theory. These values are obtained based on the lateral observation distance corresponding to the first grayscale distribution curve, the first imaging range of the first optical camera, and the size of the lateral scattering phase function image. Therefore, before calculating the lateral outward scattering electric field distribution in step S04, the lateral observation distance corresponding to the first grayscale distribution curve and the first imaging range of the first optical camera are determined. The lateral observation distance is the distance from the clear focusing position of the first optical camera to the position where the lateral scattering phase function image is acquired. Then, based on this lateral observation distance, the first imaging range, and the size of the lateral scattering phase function image, the scattering angle and azimuth angle required for the standard Mie scattering theory calculation are determined for use in calculating the lateral outward scattering electric field distribution.
[0056] In conjunction with the above embodiments, in one implementation, this application also provides a method for determining particle physical properties based on Mie scattering. In this method for determining particle physical properties based on Mie scattering, before step S011, the method further includes: determining the back-view distance corresponding to the second grayscale value distribution curve; and determining the second imaging range of the second optical camera, wherein the back-view distance is the distance from the clear focusing position of the second optical camera to the acquisition position of the interferometric modified backscattering phase function image; and determining the scattering angle and azimuth angle based on the back-view distance, the second imaging range, and the size of the interferometric modified backscattering phase function image, for use in calculating the interferometric modified backscattering spherical electric field distribution.
[0057] In this embodiment, similarly, the scattering angle and azimuth angle are required in the calculation of the interferometric correction backscattered electric field distribution using standard Mie scattering theory. These values can be calculated based on the back-viewing distance corresponding to the second grayscale distribution curve, the second imaging range of the second optical camera, and the size of the interferometric correction backscattering phase function image. Therefore, before calculating the interferometric correction backscattered electric field distribution in step S011, the back-viewing distance corresponding to the second grayscale distribution curve and the second imaging range of the second optical camera are determined. The back-viewing distance is the distance from the clear focusing position to the acquisition position of the interferometric correction backscattering phase function image. Then, based on the back-viewing distance, the second imaging range, and the size of the interferometric correction backscattering phase function image, the scattering angle and azimuth angle required for the standard Mie scattering theory calculation are determined for use in the calculation of the interferometric correction backscattered electric field distribution.
[0058] In conjunction with the above embodiments, in one implementation, this application also provides a method for determining particle physical properties based on Mie scattering. In this method, step S016 may include: traversing and comparing all first candidate physical property values and all second candidate physical property values to determine the distance between each pair of candidate physical property values; and determining the physical property value of the captured particle based on the first candidate physical property value and the second candidate physical property value corresponding to the minimum distance value.
[0059] In this embodiment, all first candidate physical characteristic values and all second candidate physical characteristic values are iterated and compared. Specifically, each first candidate physical characteristic value is compared with each second candidate physical characteristic value to obtain a distance value between a pair of candidate physical characteristic values. For example, if all first candidate physical characteristic values include A1 and A2, and all second candidate physical characteristic values include B1 and B2, the iterative comparison will obtain a corresponding distance value between A1 and B1, A1 and B2, A2 and B1, and A2 and B2. After completing the iterative comparison, the physical characteristic value of the captured particle is determined based on the pair of first and second candidate physical characteristic values corresponding to the minimum distance value. One optional determination method is to take the average of the pair of first and second candidate physical characteristic values corresponding to the minimum distance value as the physical characteristic value of the captured particle.
[0060] In this embodiment, when the particle physical properties include particle size and reflectivity, a candidate physical property value corresponds to a candidate data set including both particle size and reflectivity values. Accordingly, during the traversal comparison, this application performs a traversal comparison of all first candidate data sets for all first candidate physical property values and all second candidate data sets for all second candidate physical property values. Each pair of candidate data sets is compared based on the values of the same type of physical property. Therefore, each pair of candidate data sets will yield two distance values after comparison. After completing the traversal comparison, this application normalizes all distance values corresponding to the same type of physical property, and then adds the normalized distance values of the compared pair of candidate data sets to obtain the comprehensive distance value for that pair. Finally, based on the first and second candidate data sets corresponding to the minimum comprehensive distance value, the values of various physical properties of the captured particles are determined.
[0061] In this embodiment, as Figure 6 As shown, the particle physical property determination method based on Mie scattering provided in this application first captures a single particle using optical tweezers. Then, at the same time, it acquires the side scattering phase function and the interference-corrected backscattering phase function of the single particle, and generates a first gray-scale value distribution curve and a second gray-scale value distribution curve based on these two functions, respectively. Then, it calculates the first light intensity distribution curves for multiple particle physical property values using standard Mie scattering theory, and calculates the second light intensity distribution curves for multiple particle physical property values using interference-corrected Mie scattering theory. For the multiple first light intensity distribution curves obtained, it identifies the first light intensity distribution curve whose distance from the first gray-scale value distribution curve satisfies a first condition, and determines the particle physical property value corresponding to this first light intensity distribution curve as the corresponding candidate solution. Simultaneously, for the multiple second light intensity distribution curves obtained, it identifies the second light intensity distribution curve whose distance from the second gray-scale value distribution curve satisfies a second condition, and determines the particle physical property value corresponding to this second light intensity curve as the corresponding candidate solution. Based on all the obtained candidate solutions, it performs calculations to obtain the final particle size and refractive index values of the currently captured single particle.
[0062] It should be noted that, for the sake of simplicity, the method embodiments are all described as a series of actions. However, those skilled in the art should understand that the embodiments of this application are not limited to the described order of actions, because according to the embodiments of this application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also understand that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily necessary for the embodiments of this application.
[0063] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0064] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, embodiments of this application can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, embodiments of this application can take the form of computer program products implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.
[0065] This application describes embodiments with reference to flowchart illustrations and / or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.
[0066] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing terminal device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.
[0067] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal equipment, causing a series of operational steps to be performed on the computer or other programmable terminal equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable terminal equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.
[0068] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.
[0069] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.
[0070] The above provides a detailed description of a method for determining particle physical properties based on Mie scattering. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and its core ideas. At the same time, those skilled in the art will recognize that there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.
Claims
1. A method for determining the physical properties of particles based on Mie scattering, characterized in that, The method includes: Particles are generated using a particle generating device, and individual particles are captured within them; By using a side imaging objective and a first optical camera, the side scattering phase function of the captured particles is imaged on the defocus plane to obtain the corresponding side scattering phase function image. The normalized first gray value distribution curve is extracted from the side scattering phase function image. The horizontal axis of the first gray value distribution curve is the distance between the data point in the side scattering phase function image and the center point of the image, and the vertical axis is the normalized gray value of the data point. Using Mie scattering theory, the distribution of the lateral spherical scattering electric field of the particle at the first target position is calculated under different particle physical property values. The first target position is the position where the lateral scattering phase function image is acquired. The lateral spherical scattering electric field is the scattering electric field when an x-polarized plane wave propagating along the z-axis is scattered by the particle. Based on the lateral spherical outward scattering electric field distribution corresponding to the particle physical property values, the corresponding first light intensity distribution curve is determined; Determine the first distance between the first gray value distribution curve and each of the first light intensity distribution curves; Determine the first target distance from all first distances that satisfies the first condition; The particle physical property value corresponding to the first target distance is determined as the first candidate physical property value of the captured particle; By using a back-facing imaging objective and a second optical camera, the interference-corrected backscattering phase function of the captured particle is imaged on the defocus plane to obtain the corresponding interference-corrected backscattering phase function image. The interference-corrected backscattering phase function image includes the interference effect between the backscattered light of the captured particle and the reflected light from a certain reflecting plane below the particle. The normalized second gray value distribution curve is extracted from the interferometric modified backscattering phase function image. The horizontal axis of the second gray value distribution curve is the distance between the data point in the interferometric modified backscattering phase function image and the center point of the image, and the vertical axis is the normalized gray value of the data point. Using Mie scattering theory, the distribution of the interference-corrected backscattered electric field at the second target position is calculated for different particle physical property values. The second target position is the position where the interference-corrected backscattering phase function image is acquired. The interference-corrected backscattered electric field consists of the backscattered electric field and the scattered electric field of the plane wave reflected by the reflecting plane below the captured particle in spherical coordinates. Based on the interference correction backscattering electric field distribution corresponding to the particle physical properties, the corresponding second light intensity distribution curve is determined. Determine the second distance between the second gray value distribution curve and each of the second light intensity distribution curves; Determine the second target distance from all second distances that satisfies the second condition; The particle physical property value corresponding to the second target distance is determined as the second candidate physical property value of the captured particle; The physical property values of the captured particles are determined based on all the first candidate physical property values and all the second candidate physical property values.
2. The method for determining particle physical properties based on Mie scattering according to claim 1, characterized in that, The process involves generating particles using a particle generating device and capturing individual particles therein, including: Particles are generated using a particle generation device; The laser source is turned on to emit a laser beam, which is then focused by a back-facing imaging objective placed vertically to capture individual particles near the beam focal point from below using optical forces.
3. The method for determining particle physical properties based on Mie scattering according to claim 1, characterized in that, Using a back-facing imaging objective and a second optical camera, the interferometric modified backscattering phase function of the captured particles is imaged on the defocus plane to obtain the corresponding interferometric modified backscattering phase function image, including: A cover glass is placed between the front end of the back-facing imaging objective and the captured particle to create an interference effect between the backscattered light of the captured particle and the reflected light of the cover glass. The interference-corrected backscattering phase function of the captured particles is imaged onto a second optical camera using a back-facing imaging objective, thus obtaining an image of the interference-corrected backscattering phase function.
4. The method for determining particle physical properties based on Mie scattering according to claim 1, characterized in that, Determining the first distance between the first grayscale value distribution curve and each of the first light intensity distribution curves includes: The first distance between the first gray value distribution curve and each of the first light intensity distribution curves is calculated using the first distance algorithm. The expression for the first distance algorithm is: ,in, The first distance is the distance between the first grayscale value distribution curve and the corresponding lateral spherical outward scattered electric field distribution. The normalized gray value of the j-th data point in the first gray value distribution curve. For the light intensity corresponding to the j-th data point in the first light intensity distribution curve, , Let P be the lateral spherical outward scattered electric field at the j-th data point in the lateral spherical outward scattered electric field distribution, and let P be the total number of data points.
5. The method for determining particle physical properties based on Mie scattering according to claim 1, characterized in that, Determining the second distance between the second grayscale value distribution curve and each of the second light intensity distribution curves includes: The second distance between the second gray value distribution curve and each of the second light intensity distribution curves is calculated using the second distance algorithm. The expression for the second distance algorithm is: ,in, This represents the second distance between the second grayscale value distribution curve and the corresponding interferometric correction backscattered electric field distribution. This represents the normalized gray value of the j-th data point in the second gray value distribution curve. For the light intensity corresponding to the j-th data point in the second light intensity distribution curve, , The interference correction for the backspherical external scattered electric field distribution is given by P, where P is the total number of data points.
6. The method for determining particle physical properties based on Mie scattering according to claim 1, characterized in that, Before calculating the lateral outward scattering electric field distribution of a particle at a first target location under different particle physical property values using Mie scattering theory, where the first target location is the location where the lateral scattering phase function image is acquired, the method further includes: The lateral observation distance corresponding to the first gray value distribution curve is determined, and the first imaging range of the first optical camera is determined, wherein the lateral observation distance is the distance from the clear focus position of the first optical camera to the side scattering phase function image acquisition position; Based on the lateral observation distance, the first imaging range, and the size of the lateral scattering phase function image, the scattering angle and azimuth angle are determined for the calculation of the lateral spherical scattering electric field distribution.
7. The method for determining particle physical properties based on Mie scattering according to claim 1, characterized in that, Before calculating the interferometric correction backscattering electric field distribution of particles at the second target location under different particle physical property values using Mie scattering theory, where the second target location is the location where the interferometric correction backscattering phase function image is acquired, the method further includes: Determine the back-view distance corresponding to the second gray value distribution curve, and determine the second imaging range of the second optical camera, wherein the back-view distance is the distance from the clear focus position of the second optical camera to the image acquisition position of the interference-corrected backscattering phase function; Based on the back-view distance, the second imaging range, and the size of the interferometric correction backscattering phase function image, the scattering angle and azimuth angle are determined for the calculation of the interferometric correction backscattering electric field distribution.
8. The method for determining particle physical properties based on Mie scattering according to claim 1, characterized in that, Based on all the first candidate physical property values and all the second candidate physical property values, the physical property values of the captured particles are determined, including: All the first candidate physical characteristic values and all the second candidate physical characteristic values are traversed and compared to determine the distance value between each pair of candidate physical characteristic values; The physical property values of the captured particles are determined based on the first candidate physical property value and the second candidate physical property value corresponding to the minimum distance value.
9. The method for determining particle physical properties based on Mie scattering according to claim 1, characterized in that, The particle physical properties include at least particle size and refractive index.