A high concentration nanoparticle backscatter enhancement measurement device and method

Abstract

The application discloses a high-concentration nanoparticle backscattering enhanced measurement device and method. A light splitting component forms measuring light and reference light homologous to the measuring light from a light source. A focusing adjusting component is used to change the measuring position of the measuring light in a sample to be measured. A backscattering receiving component makes the backscattering light generated by the measuring position coincide with the reference light in the effective detection area of a photodetector. A controller determines a target measuring position according to the detection signal quality corresponding to different measuring positions. During measurement, a dynamic light scattering detection signal is obtained at the target measuring position. Correlation processing is performed to obtain correlation attenuation information, and the diffusion coefficient and the hydrodynamic particle size of the nanoparticles are determined according to the correlation attenuation information. The application can shorten the light propagation path in the high-concentration sample and obtain effective backscattering signals, and improve the adaptability and stability of the dynamic light scattering measurement.

Description

Technical Field

[0001] This invention relates to the field of nanoparticle optical measurement technology. ， In particular, this invention relates to a high-concentration nanoparticle backscattering enhancement measurement device and method. Background Technology

[0002] Dynamic light scattering (DLS) is an optical measurement technique for particle size characterization based on the Brownian motion of particles. During measurement, a laser irradiates particles suspended in a liquid. The Brownian motion of the particles causes the intensity of the scattered light to fluctuate randomly over time. By processing the scattered light signal, attenuation information related to particle diffusion can be obtained, further determining the particle's diffusion coefficient and hydrodynamic particle size. DLS is widely used for particle size characterization in dispersion systems such as colloids, slurries, biological agents, and nanomaterials.

[0003] Existing dynamic light scattering measurement devices typically employ a perpendicular scattering detection method, aligning the direction of the scattered light detection with that of the incident light. The light propagation direction is approximately perpendicular, and the scattered light signal generated by the particles is obtained in a scattering direction of approximately 90°. This is suitable for low particle concentrations. At this time, the incident light can form a relatively well-defined illumination area inside the sample, and the scattered light received by the detector can mainly reflect... The light intensity fluctuations caused by the Brownian motion of particles can be used to obtain relevant attenuation information for particle size calculation.

[0004] As the particle concentration in the sample increases, the incident light needs to pass through a certain distance before reaching the 90° scattering detection region. The sample propagation path, with increased particle density, increases the probability of light being rescattered during propagation, affecting the detector's reception. The optical signal may simultaneously contain both primary scattered light and light signals formed through multiple propagations and scattering. Meanwhile, for absorption... For samples with strong optical properties or high turbidity, the incident and scattered light will undergo significant attenuation during propagation within the sample. The above factors will weaken the effective dynamic scattered signal reaching the detector and may reduce the correlation function baseline and correlation function. The intercept and attenuation characteristics change; when the optical thickness of the sample increases further, it becomes even more difficult to obtain the desired dynamic light output. Effective correlation signals are required for scattering analysis.

[0005] In addition, the particle concentration, particle size range, refractive index, light absorption characteristics, and dispersion medium of different high-concentration samples exist. Even with the same incident light power and detection conditions, the suitable effective measurement area may differ. Using a solid-state... When measuring within a fixed scattering detection area, it is impossible to determine the measurement based on the actual light propagation state and scattering signal quality of the current sample. The position is adjusted so that when the effective scattered signal is weak, the detector's own noise, stray light, and reflected light from the sample cell interface are reduced. The relative influence in the detection signal increases further, which can easily lead to a decrease in the stability of the related signal.

[0006] Therefore, how to reduce the impact of long light propagation paths and multiple scattering on dynamic light dispersion in high-concentration nanoparticle samples is crucial. This reduces the influence of the scattered signal, while simultaneously improving the detectability of the effective scattered signal and enabling the measurement to be tailored to different measurement locations. Determining the appropriate measurement location based on the quality of the detected signal becomes a technical problem that needs to be solved. Summary of the Invention

[0007] This application provides a high-concentration nanoparticle backscattering enhancement measurement device and method, which solves the problem of simultaneously shortening the light propagation path and obtaining effective backscattering signals in high-concentration samples, and realizes enhanced detection of backscattering signals and determination of measurement positions.

[0008] In a first aspect, the present invention provides a high-concentration nanoparticle backscattering enhanced measurement device, comprising a light source, a sample cell, a beam splitting component, a focusing adjustment component, a backscattering receiving component, a photodetector, and a controller; The beam splitter is disposed between the light source and the sample cell, and is used to form the laser output from the light source into a measurement light incident on the sample cell, and a reference light of the same origin as the measurement light; The focusing adjustment component is disposed on the propagation path of the measuring light and is used to change the measurement position of the measuring light in the sample to be tested; The backscatter receiving component is used to receive the backscattered light generated at the measurement position and to make the backscattered light coincide with the reference light within the effective detection area of ​​the photodetector; The controller is connected to the focusing adjustment component and the photodetector respectively, and is used to control the focusing adjustment component to change the measurement position, and determine the target measurement position according to the detection signal quality corresponding to different measurement positions.

[0009] Furthermore, the beam splitting component includes a central transmission area and a peripheral beam splitting area surrounding the central transmission area, and the light source output beam simultaneously covers the central transmission area and the peripheral beam splitting area; The central transmission region is used to transmit the central portion of the light beam output from the light source to form the measurement light, and the peripheral beam-splitting region is used to separate the reference light from the peripheral portion of the light beam output from the light source.

[0010] Furthermore, a reference reflector and an optical path adjustment element are provided in the propagation path of the reference light; The reference reflector is used to guide the reference light to the backscatter receiving component, and the optical path adjustment component is used to adjust the optical path difference between the reference light and the backscattered light, so that the reference light and the backscattered light form a superposition of light fields within the effective detection area of ​​the photodetector.

[0011] Furthermore, the focusing adjustment assembly includes a linear displacement mechanism and a focusing lens group disposed on the linear displacement mechanism; The linear displacement mechanism is used to move the focusing lens group along the incident optical axis of the measurement light, so that the measurement position can be adjusted between a position close to the incident side wall of the sample cell and a position far away from the incident side wall.

[0012] Furthermore, the controller is configured to acquire at least two quality parameters among the correlation function intercept, correlation function baseline, detection signal intensity, and correlation function fitting residual corresponding to different measurement locations, eliminate measurement locations that do not meet the preset validity conditions based on the quality parameters, and determine the target measurement location from the remaining measurement locations.

[0013] Furthermore, a polarization adjustment component is provided in the propagation path of the measurement light. The controller is used to obtain the estimated particle size of the sample to be tested, determine the target polarization state corresponding to the estimated particle size according to the correspondence between the preset particle size range and the polarization state, and control the polarization adjustment component to switch the measurement light to the target polarization state.

[0014] Secondly, a method for measuring backscattering enhancement using high-concentration nanoparticles includes: Laser light from the same light source is used to form a measurement light incident on the sample to be tested, and a reference light of the same source as the measurement light is used. The backscattered light generated at the measurement position of the measurement light coincides with the reference light in the same detection area to obtain a detection signal. By changing the measurement position of the measuring light in the sample to be tested, the detection signals corresponding to multiple candidate measurement positions are obtained, and the measurement quality parameters corresponding to each candidate measurement position are determined. The target measurement location is determined based on the measured quality parameters, and a dynamic light scattering detection signal is acquired at the target measurement location. The dynamic light scattering detection signal is subjected to correlation processing to obtain relevant attenuation information. The diffusion coefficient of the nanoparticles is determined based on the relevant attenuation information, and the hydrodynamic particle size of the nanoparticles is determined based on the diffusion coefficient.

[0015] Furthermore, the process of determining the target measurement location based on the measurement quality parameters includes initial screening of the candidate measurement locations; The measurement quality parameters include at least two of the following: correlation function intercept, correlation function baseline, probe signal strength, and correlation function fitting residual; According to the first position interval, the measurement quality parameters corresponding to multiple candidate measurement positions are obtained within the preset measurement range. Based on the measurement quality parameters, it is determined whether each candidate measurement position meets the preset validity conditions. The measurement quality parameters corresponding to the candidate measurement positions that meet the preset validity conditions are normalized and weighted to obtain the measurement quality score. Candidate measurement areas are determined based on the measurement quality score.

[0016] Furthermore, determining the target measurement location also includes: According to a second position interval less than the first position interval, the detection signals corresponding to multiple subdivided measurement positions are acquired within the candidate measurement area, and the relevant attenuation information corresponding to each subdivided measurement position is determined; The stable measurement region is determined based on the changes in correlation attenuation information between adjacent subdivided measurement locations; The target measurement location is determined from the stable measurement area based on the measurement quality score corresponding to each subdivided measurement location within the stable measurement area.

[0017] Furthermore, after determining the target measurement position, the target polarization state is determined based on the estimated particle size of the sample to be tested; according to the correspondence between the preset particle size range and the polarization state, the polarization adjustment component is controlled to adjust the polarization state of the measurement light, and the dynamic light scattering detection signal is acquired at the target measurement position and under the target polarization state.

[0018] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages: 1. This invention forms a measurement light and a reference light by using laser light output from the same light source, and superimposes the backscattered light generated by the sample under test with the reference light in the effective detection area of ​​the photodetector. This allows the weak backscattered light to form a detectable light intensity change with the assistance of the reference light, thereby improving the detectability of weak backscattered signals and providing effective detection conditions for obtaining dynamic light scattering signals of high-concentration, high-absorption, or high-turbidity samples.

[0019] 2. This invention changes the measurement position of the measuring light in the sample by adjusting the focusing component, and determines the target measurement position according to the detection signal quality corresponding to different measurement positions. This allows the measurement position to be adjusted according to the actual scattering state of the sample. It adapts to the relationship between shortening the light propagation path by being close to the incident side wall of the sample cell and obtaining an effective detection signal that meets the requirements of dynamic light scattering analysis. This reduces the limitations of fixed measurement positions on the measurement of samples with different concentrations, turbidity and light absorption characteristics, and improves the adaptability and stability of dynamic light scattering measurement.

[0020] 3. This invention, by setting up a polarization adjustment component and switching the polarization state of the measurement light according to the estimated particle size of the sample to be tested and the correspondence between the preset particle size range and the polarization state, enables the polarization state of the measurement light to be adapted to the scattering response corresponding to particles of different particle size ranges. This improves the acquisition conditions of backscattered signals under the corresponding particle size range and, in conjunction with the target measurement position and reference light-assisted detection, enhances the effectiveness of dynamic light scattering signals used for subsequent correlation analysis and particle size calculation. Attached Figure Description

[0021] Figure 1 This is a schematic diagram illustrating the backscattering enhancement measurement principle of high-concentration nanoparticles in Embodiment 1 of this application; Figure 2 This is a schematic diagram of the stray light filtering optical path arrangement in Embodiment 1 of this application; Figure 3 This is a schematic diagram of the device in Embodiment 1 of this application; Figure 4 This is a top perspective view of the device in Embodiment 1 of this application; Figure 5 This is a perspective view of the device in Embodiment 1 of this application; Figure 6 This is a flowchart of the method in Embodiment 2 of this application.

[0022] Figure 7 This is a schematic diagram of the measurement process for determining the particle size of nanoparticles based on the measurement location in Embodiment 2 of this application.

[0023] Figure 8 The logic diagram for determining the candidate positions in Embodiment 2 of this application.

[0024] 1. Light source; 2. Sample cell; 3. Spectrometer; 4. Focusing adjustment assembly; 5. Backscatter receiver assembly; 6. Photodetector; 7. Polarization adjustment assembly; 8. Reference reflector; 9. Optical path adjustment assembly; 10. Narrow-band filter; 11. First-stage pinhole aperture; 12. Second-stage pinhole aperture; 13. Analyzer; 14. Annular high-reflectivity reflector. Detailed Implementation

[0025] The overall technology chain of this application is as follows: a light source outputs laser light; a beam splitter 3 forms a measurement light and a reference light from the same source; a focusing adjustment component changes the measurement position of the measurement light in the sample to be tested; a backscattering receiving component 5 receives the backscattered light generated at the corresponding measurement position and makes the backscattered light coincide with the reference light within the effective detection area of ​​the photodetector; a controller changes the measurement position and acquires the detection signal at each measurement position, evaluates the measurement position using at least two parameters among the correlation function intercept, correlation function baseline, detection signal intensity, and correlation function fitting residual, and determines the target measurement position; a dynamic light scattering detection signal is acquired at the target measurement position, and correlation attenuation information related to particle translational diffusion is obtained through correlation processing, thereby determining the hydrodynamic particle size.

[0026] The overall technology chain of this application is as follows: a light source outputs laser light; a beam splitter 3 forms a measurement light and a reference light from the same source; a focusing adjustment component changes the measurement position of the measurement light in the sample to be tested; a backscattering receiving component 5 receives the backscattered light generated at the corresponding measurement position and makes the backscattered light coincide with the reference light within the effective detection area of ​​the photodetector; a controller changes the measurement position and acquires the detection signal at each measurement position, and evaluates the measurement position by at least two parameters among the correlation function intercept, correlation function baseline, detection signal intensity, and correlation function fitting residual to determine the target measurement position; a polarization adjustment component controls the switching of the target polarization state according to the estimated particle size of the sample to be tested and the correspondence between the preset particle size range and the polarization state; dynamic light scattering detection signals are acquired at the target measurement position and target polarization state, and relevant attenuation information related to particle translation and diffusion is obtained through correlation processing, thereby determining the hydrodynamic particle size.

[0027] It should be understood that the "measurement position" in this embodiment refers to the location of the detection volume formed by the intersection of the effective illumination volume formed by the measurement light in the sample and the backscattering receiving field of view, which can be characterized by the distance from the center of the detection volume to the inner wall of the sample cell on the incident side; "backscattered light" refers to scattered light whose scattering direction is near the opposite direction of the incident light and can enter the backscattering receiving component, and it is not required to be strictly opposite and collinear with the incident light; "reference light" is a beam of light separated from the same light source as the measurement light, used to mix with the backscattered light in front of the detector for reference light-assisted light field mixing. The following description uses an optical path with an effective backscattering angle of 170° to 178°, preferably about 173°, as an example.

[0028] Example 1 Reference Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 This embodiment provides a high-concentration nanoparticle backscattering enhanced measurement device, including a light source, a sample cell, a beam splitter, a focusing adjustment component, a backscatter receiving component, a photodetector, and a controller. The beam splitter is disposed between the light source and the sample cell, and is used to form the laser light output from the light source into a measurement light incident on the sample cell and a reference light of the same origin as the measurement light. The focusing adjustment component is disposed on the propagation path of the measurement light, and is used to change the measurement position of the measurement light in the sample to be tested. The backscatter receiving component is used to receive the backscattered light generated at the measurement position and to make the backscattered light coincide with the reference light within the effective detection area of ​​the photodetector. The controller is connected to both the focusing adjustment component and the photodetector, and is used to control the focusing adjustment component to change the measurement position and determine the target measurement position based on the detection signal quality corresponding to different measurement positions.

[0029] The backscattering receiving component can be a beam combiner lens, which is disposed on the incident light side of the photodetector. It receives the reference light transmitted via the reference reflector 8 and the optical path adjustment element 9, as well as the backscattered light returned from the sample under test, and converges the reference light and the backscattered light towards the same effective detection area of ​​the photodetector. In this embodiment, the beam combiner lens can be a cemented doublet lens, preferably a cemented doublet achromatic lens; other lens groups with equivalent converging effect can also be used if the reference light and the backscattered light can achieve spatial overlap within the effective detection area of ​​the photodetector.

[0030] The light source is preferably a single-mode, narrow-linewidth, or continuous laser with a coherence length sufficient for the measurement. As a set of specific implementation parameters, a working wavelength of 632.8 nm or 532 nm can be used; other working wavelengths can also be selected within the range of 405 nm to 980 nm, depending on the absorption characteristics of the sample under test, the optical element film system, and the spectral response of the photodetector. For a 632.8 nm light source, 5 mW to 10 mW can be used as the initial calibration power range. The actual working power should be calibrated based on the sample absorption characteristics, optical path loss, reference light intensity, detector gain, and the upper limit of detector linearity, ensuring that the photodetector still operates within the linear range after the reference light is applied. The above power values ​​are specific calibration parameters and do not constitute fixed values ​​necessary for the implementation of this application.

[0031] The output end of the light source can be sequentially equipped with a narrowband interference filter, a collimating or beam-expanding optics, and a polarization adjustment component 7. The center wavelength of the narrowband interference filter corresponds to the operating wavelength of the light source, and is used to reduce the probability of ambient light or other non-operating wavelength light entering the subsequent optical path. The collimating or beam-expanding optics are used to adjust the spot size of the incident beam splitter, so that the beam cross-section simultaneously covers the central transmission area and the peripheral beam splitting area described later, to ensure that measurement light and reference light can be formed simultaneously from the same beam spatial distribution.

[0032] The sample cell is used to contain the suspension of nanoparticles to be tested. As a specific structure, a standard quartz sample cell with an optical path of 10 mm can be used; for industrial online measurements, a flow cell or process pipeline measurement cavity with a quartz optical window can be used. The incident optical window of the sample cell is preferably treated with anti-reflection to match the working wavelength; without affecting the focusing of the measurement light, the window normal can also be offset by a small angle relative to the incident principal optical axis, causing the specular reflected light to deviate from the main receiving aperture of the backscattering receiving component, thereby reducing static stray light formed by specular reflection from the cell wall.

[0033] The representative design range of this embodiment includes a sample mass fraction of 0.001 wt% to 10 wt% and a particle size range of approximately 1 nm to 1000 nm. For equipment with higher optical power margin, lower noise detectors, or dedicated optical path configurations, further calibration with higher concentrations or wider particle size ranges can be performed. It should be noted that the actual measurable upper limit of high-concentration samples is not only affected by the mass fraction, but also by the particle refractive index, absorption coefficient, particle size, morphology, dispersion medium viscosity, and interparticle interactions. Therefore, this embodiment uses whether a dynamic light scattering signal that meets the validity conditions described later as the criterion for outputting an effective particle size result, rather than using a single mass fraction as an absolute measurement upper limit applicable to all materials.

[0034] The beam splitting assembly includes a central transmission region and a peripheral beam splitting region surrounding the central transmission region. The light source output beam, after collimation or beam expansion, simultaneously covers both the central transmission region and the peripheral beam splitting region. The central transmission region is used to transmit the central portion of the beam to form the measurement light, while the peripheral beam splitting region is used to separate the reference light from the outer portion of the beam.

[0035] The central transmission region can be a physical via formed on the beam-splitting substrate, or it can be a high-transmission area without a beam-splitting film. As a set of specific implementation parameters, the beam-splitting component can use K9 glass or a quartz substrate. The equivalent light transmission diameter of the central transmission region is 0.5 mm to 1.0 mm, preferably about 0.8 mm. The peripheral beam-splitting region is coated with a partial reflective film, and its reflection ratio of the working wavelength can be 5% to 12%, preferably about 8%. Here, 5% to 12% refers to the proportion of reference light separated from the light energy incident on the peripheral beam-splitting region. The actual power of the reference light is also related to the spatial energy distribution of the incident light spot, the size of the central transmission region, and the effective area of ​​the peripheral beam-splitting region.

[0036] When using physical vias, the edges of the vias and the non-effective optical surfaces of the beam splitter can be treated to reduce edge diffraction and secondary reflection from the substrate surface from entering the receiving optical path. When using a high-transmission region, an anti-reflection film can be used in the central transmission region, or no beam splitter film can be used. Unintended reflections between the central region and the outer beam splitter region can be reduced through the transition design of the film system boundaries.

[0037] The above structure avoids the situation where "all incident light only passes through the central aperture, and the peripheral beam-splitting areas do not receive light energy and thus cannot form a reference beam." During actual assembly and adjustment, the diameter of the incident light spot should be larger than the diameter of the central transmission area, and the size of the incident light spot, the size of the central transmission area, and the reflection ratio of the peripheral beam-splitting areas should be adjusted according to the required measured optical power and reference optical power.

[0038] The reference light propagation path is provided with a reference reflector and an optical path adjustment component. The reference reflector can be a dielectric high-reflectivity mirror, mounted on a two-dimensional angle fine-tuning frame or a frame with micro-displacement adjustment function, used to change the propagation direction of the reference light and guide it to the beam combining region of the backscattering receiving component. The optical path adjustment component can be a reference reflector that moves along the optical axis of the reference light, a parallel glass compensator, a wedge-shaped compensator, or other optical components capable of changing the equivalent optical path of the reference light.

[0039] In the reference optical path, intensity adjustment devices, such as adjustable neutral density attenuators, electrically controlled attenuators, or variable apertures, can be set to adjust the intensity of the reference light reaching the photodetector. The goal of this adjustment is not to make the reference light as strong as possible, but to ensure that the reference light and backscattered light can form a recognizable mixture while keeping the total incident light power below the linear operating limit of the photodetector and its front-end circuitry.

[0040] To establish stable reference-assisted detection conditions, the reference light and backscattered light should at least satisfy the following conditions: sufficient spatial overlap within the effective detection region of the photodetector; non-zero projections of the polarization components to be detected in both; and an optical path difference within the allowable range of the effective coherence length of the light source. The equivalent optical path of the reference light is denoted as... The equivalent optical path length of the backscattered light is denoted as The effective coherence length of the light source is denoted as When adjusting, it is preferable to satisfy the following: in, , and Use the same unit of length.

[0041] When the reference light field and the backscattered light field coincide at the photodetector, the instantaneous light intensity received by the detector can be expressed as: in, This represents the total light intensity received by the photodetector. Reference light intensity; This represents the intensity of backscattered light. Let be the instantaneous phase difference between the reference light and the backscattered light. In the formula, the first two terms correspond to the light intensities of the two beams, and the third term corresponds to the cross term generated by the superposition of the light fields.

[0042] In this embodiment, the reference light and the measurement light are formed from the same source. Without acousto-optic modulators, electro-optic modulators, or other frequency shifters, a fixed beat frequency is not required; therefore, this is called "coherent hybrid enhancement assisted by the same source reference light" or "reference light-assisted detection." If a known frequency shift is further set in the reference optical path... This can form a heterodyne implementation with a defined beat frequency; this optional implementation does not constitute a necessary condition for the basic solution of this application.

[0043] It needs further clarification that coherent origin does not automatically guarantee stable coherent superposition. If the optical path difference exceeds the coherence length, the two beams do not achieve effective spatial overlap in the detection region, or the polarization components to be detected are nearly orthogonal, the cross term will weaken. Therefore, the reference reflector, optical path adjustment device, beam combining optics, and polarization state all jointly affect the reference light-assisted detection effect.

[0044] The focusing adjustment assembly includes a linear displacement mechanism and a focusing lens group disposed on the linear displacement mechanism. The focusing lens group can be a cemented doublet achromatic lens or a multi-lens group with equivalent focusing capability. The linear displacement mechanism drives the focusing lens group to move along the incident optical axis of the measurement light, causing the waist of the measurement beam and the overlapping area of ​​the measurement light illumination volume and the receiving field of view to move within the sample, thereby changing the measurement position.

[0045] Define the position coordinates corresponding to the inner wall of the incident side of the sample cell as follows: The direction in which the measuring light enters the sample is Positive axis direction. In actual measurement, it is not required that the effective measurement volume be exactly located in the positive axis direction. Instead, it is located in a place that avoids the main peak of the specular reflection from the pool wall and can form an effective scattering volume. to Adjustments between them.

[0046] As a set of specific structural parameters, the mechanical stroke of the linear displacement mechanism can be 0mm to 5mm; depending on the sample cell size and focusing optical structure, it can also be set to 0mm to 8mm. The stepping or positioning resolution can be set to 0.005mm to 0.02mm, with a preferred positioning accuracy of no more than 0.01mm. The linear displacement mechanism can employ a closed-loop stepping translation stage, a servo linear module, or a piezoelectric displacement mechanism. When using a closed-loop stepping or servo structure, the current position is confirmed through feedback from an encoder or driver; when using an open-loop stepping structure, it is preferable to set an origin switch and a travel limit switch, and to perform a zero-return operation when the device is powered on, in order to establish repeatable position coordinates.

[0047] For high-concentration or high-absorbency samples with a large optical thickness, moving the measurement position closer to the incident side of the cell wall can shorten the propagation path of the measurement light entering the sample and the backscattered light returning to the receiving light path. For samples with weak scattering or a small optical thickness, the measurement position can be moved further inside the sample to increase the effective illumination volume. In this embodiment, a specific position is not fixed directly based on a pre-given concentration value. Instead, the controller determines the target measurement position by comparing the actual detection signal quality at different positions.

[0048] The backscattering receiver is used to receive backscattered light generated at the measurement location. In one embodiment, the center scattering angle of the receiving optical path is 173°; depending on the sample cell structure, incident beam, and receiving numerical aperture, the effective receiving angle can be set within the range of 170° to 178°.

[0049] The returned backscattered light can return along the same path via the focusing lens group, or it can enter the beam combining region through an independent receiving lens that works in conjunction with the focusing lens group. The reference light enters the same beam combining region via the reference reflector. The two beams are incident on the beam combining doublet lens or equivalent beam combining optics and achieve spatial overlap at the photosensitive surface of the photodetector or at the spatial coupling aperture in front of the detector.

[0050] The receiving optical path can be configured with a multi-stage stray light suppression structure. In a specific implementation, it may include: a narrowband filter 10 corresponding to the operating wavelength of the light source, used to suppress ambient light; an extinction coating in the central transmission region or the non-effective area of ​​the beam splitter, used to absorb stray light reflected from the structural components; a first-stage pinhole stop 11 or a second-stage pinhole stop 12 located at conjugate positions, used to limit pool wall reflection light that does not meet the receiving spatial mode; and a polarizer 13 located in the receiving optical path, used to select the polarization component to be detected. The diameters of the two conjugate pinholes can be 100 μm and 200 μm, respectively, with an selectable aperture range of 50 μm to 300 μm. The actual aperture is determined based on the focal length, image magnification, effective detection volume, and effective detector area.

[0051] An optical trap can also be set in the direction of the transmitted light in the sample cell to absorb the direct transmitted light that is not involved in the measurement. The inner wall of the device housing and the non-working mechanical surfaces can be treated with an anti-glare coating to reduce the probability of secondary reflections entering the rearward receiving optical path.

[0052] The photodetector can be a photomultiplier tube (PMT) or an avalanche photodiode (APD). When using photon counting, the photodetector converts the received mixed light signal into a pulse sequence, and the digital correlator or controller calculates the correlation function based on the pulse arrival time or a preset delay channel. When using analog mode, the photodetector output is amplified, filtered, and converted from analog to digital to form a light intensity time sequence, and the controller or host computer calculates the correlation function.

[0053] When a single PMT or single APD receives the mixed signal of reference light and backscattered light, the detector generates a mixed light intensity time series, which is then subjected to autocorrelation or reference-light-assisted mixed correlation analysis. Cross-correlation of the two independent detection signals is only performed when two independent detection channels are used. Therefore, this embodiment does not consider the direct generation of cross-correlation curves by a single detector as a necessary process.

[0054] The controller is connected to the focus adjustment component and the photodetector, and can be further connected to the polarization adjustment component, the reference photoelectric attenuator, the digital correlator, and the host computer. As a hardware implementation, the controller can include one or more of an STM32 series microcontroller, FPGA, embedded processor, and host computer. The microcontroller is responsible for driving the translation stage, reading origin and limit signals, driving the polarization actuator, triggering data acquisition, and managing device status; the digital correlator, FPGA, or host computer is responsible for calculating correlation functions, extracting quality parameters, measuring quality scoring, and calculating particle size. Internal communication within the device can be via USB or Ethernet; in industrial online implementations, an RS-485 interface can be further configured for communication with a PLC or DCS system.

[0055] The relevant functions and measured quality parameters are as follows: For the Measurement locations The controller acquires the time series of light intensity output from the photodetector. The normalized second-order light intensity correlation function can be expressed as: in, For delay time; This indicates that the statistical average is calculated within the current data collection time window. It is a dimensionless quantity.

[0056] Baseline of related functions This can be obtained by averaging the long-delay stable interval of the relevant curve: in, This represents the total number of effective delay channels used for related calculations; The number of channels used to estimate the long-delay baseline. For a normalized correlation function, the ideal long-delay baseline is close to 1, but actual measurements are affected by finite sampling, dark noise, static stray light, and instrument response; therefore, it is not included. As the sole condition for validity.

[0057] The intercept of the correlation function uses the effective intercept. This indicates that, to avoid abnormally fast noise from detector dead time, after-pulse, or the shortest delay channel, the minimum effective delay after excluding abnormal channels can be selected. and define: in, It was determined by the detector datasheet, dark signal testing, and correlation curves of standard samples.

[0058] Detect signal strength The photon count rate per unit time can be used, or the root mean square value of the AC signal after dark signal subtraction and gain correction can be used. For position comparisons within the same round, the same signal strength definition and the same detector gain are used for each position to avoid direct comparison of values ​​with different dimensions or different gain states.

[0059] Correlation function fitting residuals It can be represented as: in, The effective delay channels involved in the fitting; This is the measured normalized correlation function; To fit the correlation function. Since both are dimensionless quantities, therefore It is also a dimensionless quantity.

[0060] For a typical monodisperse approximation DLS without reference light, the autocorrelation function can be written as: in, Let be the field-correlated attenuation rate, in units of seconds. For a single probe channel with assisted mixing from a common reference beam, when the reference beam is stable and the main dynamic component is a single translational diffusion attenuation component, the following equivalent fitting form can be used: in, The coefficients corresponding to the mixture of reference light and dynamic scattering field; These are the coefficients corresponding to the intensity-related terms of the scattered light itself. This serves as the baseline. Actual equipment should be calibrated using standard samples with and without the reference light to ensure the model matches the actual detection mode, avoiding the misinterpretation of ordinary intensity autocorrelation. Attenuation and reference light-assisted hybrid Attenuation confusion.

[0061] The controller first eliminates unusable measurement locations based on preset validity conditions. These preset validity conditions may include: the correlation function baseline is within the allowable range; the effective intercept is not lower than the minimum intercept; the detected signal strength is higher than the minimum effective signal and lower than the detector saturation or nonlinearity upper limit; and the correlation function fitting residual does not exceed the allowable value. This can be expressed as: The above conditions do not require all parameters to be enabled simultaneously in every device configuration, but the quality parameters involved in the comparison shall be no less than two as defined in the claims.

[0062] Each threshold is determined during the equipment calibration phase. With the laser off or the measurement optical path blocked, the dark signal from the photodetector is repeatedly acquired to obtain the dark count or the average dark output. and standard deviation The minimum effective signal can be determined using the following formula: in, This is the noise margin coefficient, determined by repeated measurements of standard samples. The linear response of the photodetector, preamplifier circuit, and analog-to-digital converter is determined based on tests, and a safety margin is preferably maintained before the rated linear upper limit.

[0063] Relevant baseline allowable range Minimum effective intercept and upper limit of fitting residual This can be determined by repeated measurements using a blank dispersion medium and standard samples of known particle size. For example, the baseline center value can be obtained first under standard operating conditions where there is no significant multiple scattering. The intercept and residual statistical distributions are analyzed, and then each threshold is determined based on the allowable repeatability range. The thresholds are stored in conjunction with the current light source wavelength, sample cell, detector gain, sampling time, and correlator configuration, and are recalibrated when the corresponding configurations change.

[0064] A polarization adjustment component is provided on the optical path of the measurement light. The polarization adjustment component may include an electrically controlled rotating polarizer and a quarter-wave plate that can be cut in or out. The electrically controlled rotating polarizer can change the linear polarization direction within the range of 0° to 360°, and the specific step angle can be 1° or set according to the actuator resolution; the quarter-wave plate, in conjunction with the linearly polarized light, can form a circularly polarized or elliptically polarized state.

[0065] Because particles of different sizes exhibit different scattering responses under given operating wavelength and scattering angle conditions, this embodiment determines the polarization state based on the estimated particle size of the sample to be tested. The estimated particle size is an initial estimate of the particle size obtained before formal measurement. It can be derived from historical measurement results of similar samples, sample preparation or nominal parameters, or it can be formed from relevant attenuation information that meets preset validity conditions during the coarse scanning stage. The controller pre-stores the correspondence between particle size ranges and polarization states, and controls the polarization adjustment component to switch to the corresponding target polarization state according to the particle size range to which the estimated particle size belongs. As a specific set of implementation parameters, under visible light operating wavelength conditions, when the estimated particle size is less than approximately 50 nm, it can switch to circular polarization; when the estimated particle size is in the range of approximately 50 nm to 1000 nm, it can switch to orthogonal linear polarization. The orthogonal linear polarization state refers to the linear polarization direction being orthogonal to the reference polarization direction set during assembly. The above particle size cutoff values ​​are used to illustrate an feasible polarization switching strategy. The actual cutoff values ​​can be adjusted according to the light source wavelength, particle refractive index, sample type, and standard sample calibration results, and are not intended as a fixed limit applicable to all samples.

[0066] When switching the polarization state based on the estimated particle size, it should be ensured that the polarization components to be detected in both the reference light and the backscattered light have non-zero projections at the photodetector. If a polarizer is installed in the receiving optical path, the polarizer angle can be linked to the target polarization state, or maintained at a position that can receive the required scattered polarization components without causing the reference light projection to disappear. After the polarization state switching is completed, at least two parameters from the correlation function baseline, correlation function intercept, detection signal strength, and correlation function fitting residual can be used to verify the effectiveness of the switched detection state. This verification is used to determine whether an effective detection signal can be formed under the current polarization state without changing the basic control relationship for determining the target polarization state based on the estimated particle size.

[0067] Without altering the basic optical path, a detachable annular high-reflectivity element 14 can be installed around the measurement area of ​​the sample cell to recover a portion of the obliquely backscattered light that does not directly enter the receiving aperture of the backscattering receiver. The annular high-reflectivity element can be positioned outside the sample window or adjacent to the flow cell window, with its reflective surface facing the measurement area. The tilt direction or curvature of the reflective surface is set according to the ray tracing relationship, ensuring that the reflected target scattered light enters the numerical aperture range of the backscattering receiver.

[0068] As a set of specific implementation parameters, the annular high-reflectivity element can cover the spatial region corresponding to the 160°–180° oblique backscattering direction, and its working wavelength reflectivity can be set to 90%–98%, preferably not less than 95%. The reflector can be fixedly installed or detachably installed; if an electrically operated entry and exit structure is used, the controller can bring it into the working position when it is necessary to increase the amount of oblique backscattered light collected. For fixedly installed passive reflectors, the scattered light is recovered by its installation state within the working optical path.

[0069] The measuring device can also form an independent optical module, with standardized optical flanges or positioning interfaces at both ends, allowing it to be assembled between the laser emission end and the sample assembly of an existing dynamic light scattering host. The module internally houses the beam splitter, reference reflector, focusing adjustment assembly, beam combining optics, and photodetector, maintaining the alignment of the principal optical axis through positioning pins, reference surfaces, or coaxial adjustment structures. For industrial online implementations, the standard sample cell can be replaced with a through-flow cell, and an RS-485 interface can be provided for communication with a PLC or DCS system. For dark, high-absorption samples, wavelengths of 532nm, 632.8nm, or other wavelengths selected based on the sample absorption spectrum can be used, and the filters, reflective films, and reference light attenuation can be rematched.

[0070] After the device is powered on, the controller first executes the linear displacement mechanism to return to zero, and after establishing the position coordinates, moves the translation stage to the preset initial center position. Simultaneously, it completes the dark signal reading of the photodetector, the conservative attenuation setting of the reference light, and the initialization of the polarization component. Subsequently, the controller controls the focusing adjustment component to change the measurement position within the preset measurement range. At each measurement position, after the linear displacement mechanism stabilizes, the detection signal is acquired for a predetermined time, and at least two quality parameters are calculated from the following: correlation function intercept, correlation function baseline, detection signal intensity, and correlation function fitting residual.

[0071] The controller eliminates measurement locations with weak signals, detectors entering nonlinear or saturated regions, abnormal baselines, insufficient effective intercepts, or excessive fitting residuals based on preset validity conditions. It then performs coarse scanning scoring and fine scanning stability region judgment on the remaining measurement locations to determine the target measurement location. After determining the target measurement location, the controller acquires the estimated particle size of the sample and controls the polarization adjustment component to switch to the target polarization state based on the preset correspondence between particle size range and polarization state. The controller then verifies the validity of the switched detection state. When using a motor-operated ring-shaped high-reflectivity element, the controller can also put the ring-shaped high-reflectivity element into its working position before formal acquisition; when using a fixed-installation ring-shaped high-reflectivity element, it is in the scattered light recovery state after the device is assembled. Finally, the controller maintains the target measurement location, target polarization state, detector gain, and reference light state stable to acquire the formal dynamic light scattering detection signal.

[0072] If no valid measurement position exists within the preset measurement range, the controller may perform at least one of the following actions: move the measurement position towards the sample cell incident side wall to shorten the propagation optical path; decrease or increase the reference light attenuation; adjust the photodetector gain; extend the pre-acquisition time; and re-determine and switch the polarization state based on the currently estimated particle size. If no valid signal is obtained after re-acquisition, the controller outputs a status message indicating that there is no valid measurement position for the current sample under the current optical configuration, and does not force the output of particle size results.

[0073] The technical solutions in the above embodiments of this application have at least the following technical effects or advantages: First, by forming measurement light and reference light from the same light source, and making the reference light and backscattered light coincide within the effective area of ​​the detector, the weak backscattering changes under short optical path conditions near the pool wall can be mixed with the reference light and enter the detector output, which is beneficial to improving the detectability of weak backscattering signals; Second, by changing the measurement position through the focusing adjustment component, and selecting the target measurement position based on the actual relevant signal quality obtained at different positions, the measurement position can be adapted to the optical thickness and scattering state of different samples; Third, by switching the polarization state according to the correspondence between the estimated particle size of the sample to be measured and the preset particle size range, the polarization state of the measurement light can be adapted to the scattering response of the corresponding particle size range, and by verifying the validity of the switched signal, the formal dynamic light scattering measurement is established on the basis of the detection signal that meets the preset quality conditions.

[0074] Example 2 Reference Figure 6 , Figure 7 and Figure 8This embodiment provides a method for enhancing backscattering measurement using high-concentration nanoparticles. This method can be executed by the measurement device described in Embodiment 1, or by a measurement system with equivalent optical path, detection, and control capabilities. Figure 8 This paper illustrates a specific measurement process from module initialization, coarse scanning, assessment of multiple scattering effects, focus adjustment, polarization state switching based on estimated particle size, operation of the annular high-reflectivity element, reference light-assisted detection, to particle size distribution output.

[0075] S100: Initialization and Device Calibration The controller controls the linear displacement mechanism to return to zero, establishes the measurement position coordinates, and moves the translation stage to the preset initial center position after returning to zero, which serves as the starting reference position for subsequent coarse scanning; dark signals are acquired under the condition of laser off or measurement optical path blocked, and the mean and standard deviation of the dark signals are obtained; the baseline, effective intercept, and statistical range of the correlation function fitting residual under normal working conditions are obtained using blank dispersion medium or standard samples with known particle size; the saturation or nonlinearity upper limit of the detection signal is determined based on the linear response test of the photodetector and its front-end circuit.

[0076] Subsequently, the reference reflector, beam combiner, and optical path adjustment mechanism are adjusted to ensure that the reference light and the backscattering receiving light path spatially coincide within the effective region of the photodetector, and that the optical path difference between them is less than the effective coherence length of the light source. The reference light intensity adjustment mechanism is then adjusted to ensure that the photodetector remains in its linear operating region after the reference light is added.

[0077] Calibration parameters obtained under the same optical configuration can be stored as a device parameter template. When the light source wavelength, sample cell type, detector gain, correlator delay channel, or main optical components change, the corresponding calibration should be re-performed.

[0078] S200: Generates measurement light and reference light, and acquires the current position detection signal. Laser light from the same source is split into a measurement beam and a reference beam of the same origin by a beam-splitting component. The measurement beam is focused and adjusted by a focusing component to establish the current measurement position in the sample. Brownian motion of particles within this position generates backscattered light that fluctuates over time. The backscattered light is received by a backscattering receiving component and aligned with the reference beam within the same effective detection area of ​​the photodetector to obtain the detection signal at the current measurement position.

[0079] If PMT or APD photon counting methods are used, the current position detection signal can be represented as a photon pulse time series or a unit time count sequence; if analog detection methods are used, the current position detection signal can be represented as a light intensity time series obtained through amplification, filtering, and analog-to-digital conversion. Subsequent position comparisons use the same sampling frequency, sampling duration, and detector gain.

[0080] S300: Coarse scan and extraction of measurement quality parameters Using the inner wall of the sample cell incident side as the position reference point, within the preset measurement range The inner intervals are based on the first position. Perform a coarse scan. As a set of specific implementation parameters, within a mechanical travel range of 0 mm to 5 mm, a first position interval on the order of 0.2 mm to 1.0 mm can be selected; the starting measurement position should avoid the main peak of specular reflection from the cell wall, and the ending position should not exceed the effective measurement area allowed by the current sample cell and focusing optical structure.

[0081] For each candidate measurement location After the focusing adjustment component is in place and stable, the controller acquires the detection signal and calculates the intercept of the correlation function. Baseline of correlation function Detection signal strength and correlation function fitting residuals At least two quality parameters in the sample.

[0082] First, a rigorous initial screening is conducted based on preset validity criteria. Candidate positions that do not meet the baseline allowable range, effective intercept lower limit, effective signal intensity range, or fitting residual upper limit are not included in the subsequent scoring.

[0083] As with Figure 8 The control method corresponding to the process shown can also be used to classify and evaluate the degree of multiple scattering influence of the current sample based on at least two of the following: the deviation of the correlation function baseline obtained from the coarse scan from the calibration baseline, the change in the effective intercept, the intensity of the probe signal, and the residual of the correlation function fitting. Figure 8 The term "locking the optimal scattering focus" can be understood as obtaining an initial preferred focus or candidate focus based on the coarse scan results. This focus is used to determine the starting position for subsequent focus adjustment and does not replace the determination of the final target measurement position in S500. When the sample preparation information indicates a high-concentration sample, or when the coarse scan results indicate a strong influence of multiple scattering, the controller prioritizes moving the measurement position towards the incident wall of the sample cell to shorten the propagation path of the measurement light and the returned scattered light. When the sample is a low-concentration sample or the influence of multiple scattering is weak, the measurement position can be prioritized to move towards the interior or central region of the sample cell to obtain a larger effective scattering volume. The aforementioned high concentration, low concentration, and degree of multiple scattering influence are only used to determine the preferred direction of focus search; the final target measurement position is still determined according to the measurement quality parameters and related attenuation stability.

[0084] S400: Quality parameter normalization, weighted scoring, and candidate measurement region determination For candidate measurement locations that pass the initial screening, the mass parameters involved in the scoring are converted into dimensionless mass quantities in the range of 0 to 1.

[0085] For the effective intercept, if It can be defined as: in, To obtain a good reference intercept using standard samples, This is the lowest effective intercept.

[0086] For the relevant function baseline, to calibrate the baseline For the target, we can define: in, This represents the maximum allowable baseline deviation.

[0087] Regarding the detection signal strength, since both excessively weak and excessively strong signals are not ideal, it is possible to... Define segmented mass quantity under the following conditions: in, The optimal operating strength is selected through standard sample testing within the linear region of the detector.

[0088] For the fitting residuals, in Under these conditions, we can define: in, This is the reference fitting residual for the standard sample under normal conditions.

[0089] The dimensionless mass quantities involved in the scoring are uniformly denoted as... Comprehensive measurement quality score It can be represented as: in, The number of quality parameters used in the scoring; The corresponding weights are used. For initial calibration, equal weights can be used as the starting value, and then the weights can be adjusted using repeated measurements of standard samples of known particle sizes at different measurement locations. The goal of weight adjustment is to ensure that high-scoring locations simultaneously have a stable correlation baseline, a sufficiently effective intercept, appropriate signal intensity, and low fitting residuals, rather than simply maximizing the detected signal intensity.

[0090] Determine the highest score in the coarse scan After that, it can satisfy The continuous set of locations was determined as the candidate measurement region, where The measurement location is determined by the normal fluctuation range of the quality score measured during repeated scanning of the standard sample; alternatively, the candidate measurement area can be defined by taking the highest score position as the center and defining at least one first position interval to the left and right of it. This step is only used to complete the initial screening of candidate measurement positions and narrow down the search range, and does not directly determine the highest score position of the coarse scan as the final target measurement position.

[0091] S500: Fine scanning, stable measurement area determination, and target measurement location determination. Within the candidate measurement area, according to the second position interval Perform a fine scan and satisfy the following conditions: When the positioning resolution of the linear displacement mechanism is no greater than 0.01mm, the second position interval can be set to the order of 0.01mm to 0.10mm, depending on the focal depth of the focusing lens, the width of the candidate area, and the allowable measurement time.

[0092] For each subdivided measurement location Reacquire the detection signal, calculate the same measurement quality parameters and measurement quality score. The field-correlation attenuation rate is obtained by fitting a model using the correlation function corresponding to the current detection mode. .

[0093] To reduce the likelihood of anomalous attenuation locations caused by local specular reflection, accidental strong signals, or severe multiple scattering being selected as the final measurement location, this embodiment further compares the relevant attenuation information of adjacent subdivided measurement locations. The attenuation change between adjacent locations can be defined as a symmetrical relative rate of change: in, It is a small positive quantity with the dimension of one second, used to avoid the denominator from approaching zero; It is a dimensionless quantity.

[0094] When the rate of change of adjacent attenuation corresponding to at least three consecutive subdivision measurement locations all satisfy: When all the subdivided measurement positions meet the preset validity conditions, the corresponding continuous position segments are determined as stable measurement areas. .in, The attenuation rate was determined by the normal fluctuation of the standard sample with known particle size under repeated positioning and collection conditions.

[0095] If multiple stable measurement regions are formed, the baseline deviation, effective intercept, and highest measurement quality score of each stable region can be compared first to determine the final stable region to participate in the location selection. The target measurement location can be determined according to the following formula: That is, the effective location with the highest measurement quality score is selected from the stable measurement region as the target measurement location. Thus, the target measurement location simultaneously satisfies two conditions: stable local correlation attenuation and superior overall signal quality.

[0096] S600: Polarization state switching based on estimated particle size After determining the target measurement location, the controller acquires the estimated particle size of the sample to be measured. This estimated particle size can be obtained from historical measurement results of similar samples, sample preparation, or nominal parameters. Alternatively, it can be formed using relevant attenuation information that meets preset validity conditions during the coarse or fine scan stages to create an initial particle size estimate. This estimated particle size is used to determine the polarization state before formal acquisition and is not equivalent to the final hydrodynamic particle size output by the S700.

[0097] The controller pre-stores the correspondence between particle size ranges and polarization states, and generates polarization switching commands based on the estimated particle size range to control the polarization adjustment component to form the corresponding target polarization state. As a set of specific implementation parameters, under visible light operating wavelengths, when the estimated particle size is less than approximately 50 nm, circular polarization can be used; when the estimated particle size is in the range of approximately 50 nm to 1000 nm, orthogonal linear polarization can be used. The orthogonal linear polarization state refers to the linear polarization direction of the measured light being orthogonal to the preset reference polarization direction. The aforementioned particle size boundary values ​​can be calibrated and adjusted using repeated measurements of known particle size standard samples under different polarization states.

[0098] After the polarization state switching is completed, keeping the target measurement position, reference light attenuation, detector gain, and acquisition time unchanged, the detected signal after the switch is acquired, and at least two quality parameters among the correlation function baseline, correlation function intercept, detected signal intensity, and correlation function fitting residual are calculated to verify whether the detected signal under the current polarization state meets the preset validity conditions. If it does, the target polarization state is maintained and formal acquisition begins; if it does not, the estimated particle size can be reacquired, the calibration mapping between the preset particle size range and the polarization state can be adjusted, or the target measurement position neighborhood can be returned for local verification.

[0099] therefore, Figure 8 The phrase "automatically switch between circular polarization and orthogonal linear polarization modes based on estimated particle size" corresponds to using the estimated particle size as the pre-input for polarization switching, while the relevant quality parameters are mainly used to verify the effectiveness of the detection state after switching.

[0100] S700: Formal data acquisition, determination of relevant attenuation information, and particle size calculation After locking the target measurement position and target polarization state, the focusing position, polarization state, reference light state, and detector gain remain unchanged. In embodiments employing a ring-shaped high-reflectivity element, if the ring-shaped high-reflectivity element uses an electrically driven insertion structure, the controller initiates its operation at this stage; if a fixed installation structure is used, it is already in the working optical path. Subsequently, the acquisition time is extended to obtain the formal dynamic light scattering detection signal. Figure 8 The term "stable heterodyne interference correlation signal" refers to the reference light-assisted hybrid detection signal obtained after the reference light and backscattered light form an optical field superposition at the photodetector. Without a frequency shifter, this statement does not require the formation of a fixed beat frequency. However, when the reference optical path is further set with a known frequency shift, heterodyne detection with a definite beat frequency can be formed.

[0101] For monodisperse or narrowly distributed samples, the field-correlated attenuation rate is obtained by fitting it into the current correlation model. Scattering vector magnitude Calculate according to the following formula: in, The refractive index of the dispersed medium at the measured temperature is a dimensionless quantity. The laser vacuum wavelength is expressed in meters (m). The scattering angle; The dimension of is per meter.

[0102] Particle translational diffusion coefficient Determined by the following formula: ,in, The dimension is per second, therefore The dimension of is square meters per second.

[0103] For approximately spherical particles, the hydrodynamic diameter Determined based on the Stokes-Einstein relation: ,in, Boltzmann's constant, in J / K; This is the absolute temperature of the sample, in K. The dynamic viscosity used for particle size conversion under the current measurement conditions is expressed in Pa·s. The dimension is square meters per second, and the calculation yields... The unit is m.

[0104] Temperature can be acquired in real time by a temperature sensor located near the sample cell; dynamic viscosity can be measured by a viscometer or obtained by looking up a table based on temperature when the dispersion medium formulation is known and the concentration effect is negligible. For high-concentration systems, if interparticle interactions or system viscosity changes significantly with concentration, the effective dynamic viscosity measured under the current operating conditions or calibrated is preferred; when concentration interactions cannot be ruled out, the result can be recorded as the apparent hydrodynamic particle size under that operating condition, and the sample concentration, temperature, and viscosity conditions can be saved simultaneously.

[0105] As an example of the rationality of formula dimensions and numerical values, the following is adopted: nm , , K, mPa·s, if the standard sample is fitted to obtain Every second, there are per meter square meters per second, further obtained nm. This value is only used to illustrate the dimensional and order-of-magnitude correspondence between formulas and does not indicate that high-concentration samples will necessarily obtain the same results.

[0106] For samples with a distinct particle size distribution, the particle size distribution can be inverted using the decay distribution of the field correlation function. The field correlation function can be expressed as: in, The decay rate distribution is non-negative. After discretization, it can be obtained using non-negative least squares, Tikhonov regularization, or other existing inverse Laplace methods. Then according to The Stokes-Einstein relationship is then converted to particle size distribution. Regularization parameters can be determined using known standard samples, L-curves, cross-validation, or preset noise levels.

[0107] It should be noted that the Stokes-Einstein relation itself is used to convert the hydrodynamic particle size from the translational diffusion coefficient and does not directly perform multiple scattering correction. This embodiment first reduces the impact of multiple scattering on the effective correlation signal through backward short optical path, measurement position selection, reference light-assisted detection, and correlation quality verification. When the device is not equipped with an experimentally validated multiple scattering correction model, the particle size is forcibly output after introducing a correction term without justification; when the device is equipped with a multiple scattering correction model validated through standard sample testing or historical calibration, the correlation processing results can be further corrected according to the implementation method described later.

[0108] Reference Figure 8In another embodiment, to address the issue of residual multiple scattering effects still existing in some high-concentration nanoparticle samples, an experimentally validated multiple scattering correction model can be used to correct the relevant processing results, and the nanoparticle size distribution can be inverted based on the corrected attenuation information. This embodiment corresponds to... Figure 8 The step of "inverting the particle size distribution of nanoparticles using a multiple scattering correction model" in the text.

[0109] The multiple scattering correction model is used to correct the correlation attenuation information based on the sample state parameters and correlation function characteristic parameters during the dynamic light scattering detection process. The sample state parameters may include at least one of sample concentration, optical path length, and scattering intensity; the correlation function characteristic parameters may include at least one of correlation function baseline, correlation function intercept, correlation function attenuation rate, and fitting residual.

[0110] The multiple scattering correction model can be obtained through experimental calibration of standard nanoparticle samples. Specifically, the dynamic light scattering signals corresponding to standard samples at different concentration gradients are obtained, and the characteristic parameters of the correlation function obtained experimentally are correlated with the standard particle size results to establish a mapping relationship between input parameters and correction parameters.

[0111] In the actual measurement process, the sample state parameters and related function characteristic parameters corresponding to the current sample to be tested are input into the multiple scattering correction model to obtain the corresponding correction parameters. The relevant attenuation information is corrected according to the correction parameters, the diffusion coefficient is determined according to the corrected relevant attenuation information, and the nanoparticle size distribution is further calculated.

[0112] S800: Result Verification, Anomaly Handling, and Historical Templates Before outputting the final particle size results, recheck whether the baseline, effective intercept, probe signal intensity, and fitting residual of the correlation function from the formal acquisition stage meet the validity conditions. If the formal acquisition results deteriorate beyond the calibration allowable range compared to the location selection stage, the effective particle size will not be output temporarily, and the acquisition will be re-acquired in the neighborhood of the target location or a fine scan will be re-executed.

[0113] If no valid measurement position exists within the entire preset measurement range, at least one of the following processes can be performed sequentially: adjust the measurement position towards the incident side of the pool wall to shorten the propagation optical path; adjust the reference light attenuation; adjust the detector gain; redetermine and switch the polarization state based on the currently estimated particle size; extend the pre-acquisition time. If an effective correlation function still cannot be formed after the above processes, output "No valid measurement position for the current sample under the current optical configuration" or equivalent state information to avoid forcibly calculating the particle size based on an invalid correlation curve.

[0114] For samples of the same type, the target measurement location, target polarization state, reference light attenuation, detector gain, and acquisition duration of the last valid measurement can be used as a historical template. When measuring similar samples subsequently, a local scan can be performed near the historical target location first; before the actual particle size is output, at least one validity check should still be performed to avoid the historical template becoming invalid due to changes in sample batch, temperature, concentration, or optical window state.

[0115] Although preferred embodiments of the invention 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 both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0116] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from the scope of the invention. The spirit and scope of the invention are as follows: Thus, if these modifications and variations of the invention fall within the scope of the claims of the invention and their equivalents, the invention is also intended to include these modifications and variations.

Claims

1. A high-concentration nanoparticle backscattering enhancement measurement device, characterized in that, It includes a light source, a sample cell, a beam splitter, a focusing adjustment component, a backscatter receiver, a photodetector, and a controller; The beam splitter is disposed between the light source and the sample cell, and is used to form the laser output from the light source into a measurement light incident on the sample cell, and a reference light of the same origin as the measurement light; The focusing adjustment component is disposed on the propagation path of the measuring light and is used to change the measurement position of the measuring light in the sample to be tested; The backscatter receiving component is used to receive the backscattered light generated at the measurement position and to make the backscattered light coincide with the reference light within the effective detection area of ​​the photodetector; The controller is connected to the focusing adjustment component and the photodetector respectively, and is used to control the focusing adjustment component to change the measurement position, and determine the target measurement position according to the detection signal quality corresponding to different measurement positions.

2. The high-concentration nanoparticle backscattering enhancement measurement device according to claim 1, characterized in that, The beam splitting component includes a central transmission area and a peripheral beam splitting area surrounding the central transmission area, and the light source output beam simultaneously covers the central transmission area and the peripheral beam splitting area; The central transmission region is used to transmit the central portion of the light beam output from the light source to form the measurement light, and the peripheral beam splitting region is used to split the reference light from the peripheral portion of the light beam output from the light source.

3. The high-concentration nanoparticle backscattering enhancement measurement device according to claim 2, characterized in that, The reference light is provided with a reference reflector and an optical path adjustment component along its propagation path. The reference reflector is used to guide the reference light to the backscatter receiving component, and the optical path adjustment component is used to adjust the optical path difference between the reference light and the backscattered light, so that the reference light and the backscattered light form a superposition of light fields within the effective detection area of ​​the photodetector.

4. The high-concentration nanoparticle backscattering enhancement measurement device according to claim 1, characterized in that, The focusing adjustment assembly includes a linear displacement mechanism and a focusing lens group disposed on the linear displacement mechanism; The linear displacement mechanism is used to move the focusing lens group along the incident optical axis of the measurement light, so that the measurement position can be adjusted between a position close to the incident side wall of the sample cell and a position far away from the incident side wall.

5. The high-concentration nanoparticle backscattering enhancement measurement device according to claim 1, characterized in that, The controller is configured to acquire at least two quality parameters from the following: the intercept of the correlation function, the baseline of the correlation function, the intensity of the probe signal, and the residual of the correlation function fitting, corresponding to different measurement locations; to eliminate measurement locations that do not meet the preset validity conditions based on the quality parameters; and to determine the target measurement location from the remaining measurement locations.

6. The high-concentration nanoparticle backscattering enhancement measurement device according to claim 1, characterized in that, A polarization adjustment component is provided on the propagation path of the measurement light. The controller is used to obtain the estimated particle size of the sample to be tested, determine the target polarization state corresponding to the estimated particle size according to the correspondence between the preset particle size range and the polarization state, and control the polarization adjustment component to switch the measurement light to the target polarization state.

7. A method for measuring backscattering enhancement of high-concentration nanoparticles, characterized in that, The apparatus according to any one of claims 1-6 comprises: Laser light from the same light source is used to form a measurement light incident on the sample to be tested, and a reference light of the same source as the measurement light is used. The backscattered light generated at the measurement position of the measurement light coincides with the reference light in the same detection area to obtain a detection signal. By changing the measurement position of the measuring light in the sample to be tested, the detection signals corresponding to multiple candidate measurement positions are obtained, and the measurement quality parameters corresponding to each candidate measurement position are determined. The target measurement location is determined based on the measured quality parameters, and a dynamic light scattering detection signal is acquired at the target measurement location. The dynamic light scattering detection signal is subjected to correlation processing to obtain relevant attenuation information. The diffusion coefficient of the nanoparticles is determined based on the relevant attenuation information, and the hydrodynamic particle size of the nanoparticles is determined based on the diffusion coefficient.

8. The high-concentration nanoparticle backscattering enhancement measurement method according to claim 7, characterized in that, The process of determining the target measurement location based on the measurement quality parameters includes initial screening of the candidate measurement locations; The measurement quality parameters include at least two of the following: correlation function intercept, correlation function baseline, probe signal strength, and correlation function fitting residual; According to the first position interval, the measurement quality parameters corresponding to multiple candidate measurement positions are obtained within the preset measurement range. Based on the measurement quality parameters, it is determined whether each candidate measurement position meets the preset validity conditions. The measurement quality parameters corresponding to the candidate measurement positions that meet the preset validity conditions are normalized and weighted to obtain the measurement quality score. Candidate measurement areas are determined based on the measurement quality score.

9. The high-concentration nanoparticle backscattering enhancement measurement method according to claim 8, characterized in that, The determination of the target measurement location also includes: According to a second position interval less than the first position interval, the detection signals corresponding to multiple subdivided measurement positions are acquired within the candidate measurement area, and the relevant attenuation information corresponding to each subdivided measurement position is determined; The stable measurement region is determined based on the changes in correlation attenuation information between adjacent subdivided measurement locations; The target measurement location is determined from the stable measurement area based on the measurement quality score corresponding to each subdivided measurement location within the stable measurement area.

10. The high-concentration nanoparticle backscattering enhancement measurement method according to claim 7, characterized in that, After determining the target measurement position, the target polarization state is determined based on the estimated particle size of the sample to be tested. Based on the correspondence between the preset particle size range and the polarization state, the polarization adjustment component is controlled to adjust the polarization state of the measurement light, and the dynamic light scattering detection signal is acquired at the target measurement position and under the target polarization state.

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