Soil granularity analysis device based on multi-mode laser scattering and imaging technology

Abstract

The invention discloses a soil particle size analysis device based on a multi-mode laser scattering and imaging technology, and relates to the technical field of soil particle size analysis, an automatic sample injection module is used for preparing a test sample, and the test sample is respectively introduced into a static particle size measurement module and a dynamic particle size measurement module; the static particle size measurement module is used for carrying out particle size analysis on the soil particles with the first particle size, and the dynamic particle size measurement module is used for carrying out particle size analysis on the soil particles with the second particle size. The static particle size measurement module and the dynamic particle size measurement module are electrically connected with the data acquisition and analysis module, and are used for receiving and analyzing data obtained by the static particle size measurement module and the dynamic particle size measurement module. According to the invention, wide-dynamic-range particle granularity measurement and large-concentration-range measurement of soil samples can be realized, particle morphology information can be obtained while soil particle granularity data is obtained, and full-automatic measurement and analysis are realized.

Description

Technical Field

[0001] This invention relates to the field of soil particle size analysis technology, and in particular to a soil particle size analysis device based on multimodal laser scattering and imaging technology. Background Technology

[0002] The determination of soil particle composition is the foundation of soil science research. It plays a supporting role in establishing soil type systems, understanding regional soil differences, evaluating soil fertility and quality, improving soil resource utilization, and guiding agricultural production.

[0003] Laser diffraction, as a novel particle size determination method, is finding increasingly widespread application in particle size analysis. The principle of laser diffraction for particle size distribution determination is as follows: when a beam of light shines on a particle, the beam is blocked by the particle, and a portion of the light is scattered. The propagation direction of the scattered light forms an angle θ with the propagation direction of the main beam. The size of the scattering angle θ is related to the particle size; the larger the particle, the smaller the scattering angle θ; the smaller the particle, the larger the scattering angle θ. Simultaneously, the intensity of the scattered light represents the number of particles of that size. Therefore, by measuring the intensity of the scattered light at different angles, the particle size distribution of the sample can be obtained. Compared to the traditional pipette method, laser diffraction for soil particle size determination has advantages such as high speed, wide measurement range, high automation, small relative error, and high reproducibility, providing more detailed soil classification information. Thus, laser diffraction provides a rapid means of determining the particle size distribution of large batches of soil, leading to its increasing use in determining soil particle composition.

[0004] Laser particle size analyzers are instruments used to determine particle size distribution based on the principle of laser diffraction. They mainly consist of a first laser, a sample cell, an optical system, a detection system, and a data processing and control system. With the deepening of soil research, some bottlenecks in this instrument urgently need to be improved.

[0005] (1) Expansion of the testing range. Soil is a complex mixture of particles with a wide range of particle sizes. The development of soil science has led to increasing interest in the distribution of small-diameter particles, especially soil colloids smaller than 2 micrometers. Currently, laser particle size analyzers for determining soil particle composition are mainly divided into two categories. One type is developed based on the principle of static light scattering, and its particle size range for measuring soil samples is generally 0.1 μm-3000 μm, with its lower limit of measurement difficult to reach the nanometer level. The other type is developed based on the principle of dynamic light scattering, and its measurement range can reach 0.1 nm-10 μm, with its upper limit of measurement difficult to improve further. At present, no instrument can simultaneously meet the needs of soil particle detection in terms of both the upper and lower limits of measurement.

[0006] (2) Soil particle morphology. Soil particles exist in different shapes. As soil research deepens and becomes more microscopic, scientists are no longer satisfied with simply obtaining results on the size distribution of single soil particles. They are increasingly focused on obtaining more additional particle information (such as morphology and structure). Optical imaging analysis, or image-based analysis, is the only analytical method that can directly observe particle morphology and achieve individual particle measurement. Optical imaging analysis has high sensitivity and accuracy, and can obtain more particle information. Therefore, it is particularly necessary to combine morphology-based optical imaging technology with laser diffraction analysis, but such instruments and equipment are currently scarce on the market.

[0007] (3) Representativeness of soil samples. Due to the limitations of light saturation in optical systems, the sample loading of laser particle size analyzers on the market is relatively small, approximately 0.1g-2g, with nanoscale particle size analyzers requiring even less. Soil is a complex system, and during soil collection, transportation, drying, and sieving, soil particles often exhibit a non-uniform distribution. Therefore, insufficient sample loading often affects the representativeness of the sample and easily leads to poor repeatability of results. Currently available instruments rarely consider this aspect.

[0008] (4) Large sample size of soil samples. In soil research, from nationwide soil surveys to the collection of samples from a single farmland system, a large number of soil samples are often obtained in a single sampling. Therefore, equipping the soil with an automatic continuous sampling device suitable for soil analysis will effectively improve the efficiency of particle size analysis and reduce human error. However, most laser particle size analyzers, because they are mainly used for material samples with relatively simple composition, often use manual sampling or are equipped with small-volume automatic sampling devices, which undoubtedly cannot meet the needs of soil particle analysis. Summary of the Invention

[0009] The purpose of this invention is to provide a soil particle size analysis device based on multimodal laser scattering and imaging technology to solve the problems existing in the prior art, realize particle size measurement with a wide dynamic range and determination of soil sample concentration range, obtain particle morphology information while acquiring soil particle size data, and realize fully automatic measurement and analysis.

[0010] To achieve the above objectives, the present invention provides the following solution: This invention provides a soil particle size analysis device based on multimodal laser scattering and imaging technology, comprising a housing, an automatic sample introduction module, a static particle size measurement module, and a dynamic particle size measurement module disposed inside the housing, and a data acquisition and analysis module disposed outside the housing. The automatic sample introduction module is used to prepare test samples and introduce the test samples into the static particle size measurement module and the dynamic particle size measurement module respectively. The static particle size measurement module is used to perform particle size analysis on soil particles of a first particle size, and the dynamic particle size measurement module is used to perform particle size analysis on soil particles of a second particle size, wherein the first particle size is larger than the second particle size. Both the static particle size measurement module and the dynamic particle size measurement module are electrically connected to the data acquisition and analysis module and are used to receive and analyze the data obtained by the static particle size measurement module and the dynamic particle size measurement module.

[0011] Preferably, the automatic sample feeding module includes a sample mixing tank, a sample stirring assembly, a liquid level sensor, a circulation pump, and a filter separator. The upper end of the sample mixing tank is open and located near the upper end of the housing. The sample stirring assembly is used to mix and stir the liquid medium and solid sample in the sample mixing tank to form a test sample. The inlet of the filter separator is connected to the outlet of the sample mixing tank. The first outlet of the filter separator is connected to the inlet of the static particle size measurement module, and the second outlet of the filter separator is connected to the inlet of the dynamic particle size measurement module. The first outlet is used to discharge test samples with particle sizes greater than 1 micrometer, and the second outlet is used to discharge test samples with particle sizes less than 1 micrometer. The outlets of the static particle size measurement module and the dynamic particle size measurement module are both connected to a discharge port. The circulation pump is located on the liquid circulation pipeline between the discharge port and the mixing tank.

[0012] Preferably, the sample mixing assembly includes a sample stirrer and an ultrasonic oscillator. The stirring end of the sample stirrer extends into the sample mixing pool and stirs the test sample in the sample mixing pool. The ultrasonic oscillator is positioned close to the sample mixing pool and oscillates the test sample in the sample mixing pool.

[0013] Preferably, the static particle size measurement module has a first sample pool at the position corresponding to the first outlet, and the dynamic particle size measurement module has a second sample pool at the position corresponding to the second outlet. The outlets of the first sample pool and the second sample pool are both connected to the discharge port, and the sidewalls of the first sample pool and the second sample pool are both made of transparent material.

[0014] Preferably, the static particle size measurement module includes a laser channel and a video channel, wherein the laser channel and the video channel are arranged in parallel and share the first sample pool; The laser channel includes a first laser, an emitting optical system, a focal plane detector, a backscatter detector, and a large-angle detector. The first laser, the emitting optical system, and the backscatter detector are located on one side of the first sample pool, and the focal plane detector and the large-angle detector are located on the other side of the first sample pool. The outlet of the first laser is arranged facing the first sample pool. The emitting optical system is arranged close to the light-emitting end of the first laser, and the backscatter detector is arranged close to the emitting optical system. The video channel includes an illumination element, a first beam expander and homogenizer element, and a video imaging detector. The illumination element and the video imaging detector are located on opposite sides of the first sample pool, and the first beam expander and homogenizer element is located between the illumination element and the first sample pool.

[0015] Preferably, narrowband filters are provided between the backscatter detector and the first sample cell, and on the side of the sample cell away from the first laser; recessed filters are provided at the imaging lens of the video imaging detector and at the first beam expanding and homogenizing element; both the backscatter detector and the large-angle detector are single-point silicon APD detectors, and the backscatter detector and the large-angle detector are respectively distributed on two arc surfaces centered on the first sample cell.

[0016] Preferably, the dynamic particle size measurement module includes a second laser, a second beam expander and homogenizer, two backward high-sensitivity PMT detectors, and two lateral high-sensitivity PMT detectors. The second laser is located on one side of the second sample cell, and the second beam expander and homogenizer is provided between the second laser and the second sample cell. The two lateral high-sensitivity PMT detectors are arranged opposite each other on both sides of the second sample cell, and the two lateral high-sensitivity PMT detectors and the second laser are respectively located on different sides of the second sample cell. The two backward high-sensitivity PMT detectors are located on the same side of the second sample cell and on both sides of the second laser.

[0017] Preferably, the system further includes an automatic continuous sampler for replenishing soil samples into the automatic sampling module. The automatic continuous sampler includes a robotic arm, an ultrasonic tank, a test tube rack, a recovery box, and a control box. The robotic arm is a six-axis robotic arm, and under the control of the control box, it can grasp the sample tube and move the sample tube. The test tube rack is used to hold soil particles. Under the control of the control box, the robotic arm can grasp the sample tube and transfer it to the ultrasonic tank for ultrasonic treatment. Under the control of the control box, the robotic arm can also pour the ultrasonically treated soil particles into the automatic sampling module and transfer the sample tube to the recovery box.

[0018] Preferably, the data acquisition and analysis module includes a data acquisition unit and a data processing unit; The data acquisition unit is electrically connected to the focal plane detector, backscatter detector, large angle detector, and video imaging detector of the static particle size measurement module, as well as the lateral high-sensitivity PMT detector and the back high-sensitivity PMT detector of the dynamic particle size measurement module, and is used to synchronously or asynchronously acquire the electrical signals output by each detector. The data processing unit is configured as follows: Using Mie scattering theory or mode-free algorithms, the electrical signals collected by the static particle size measurement module are inverted and calculated to obtain soil particle size distribution data within the first particle size range. Based on the electrical signals collected by the dynamic particle size measurement module, the soil particle size distribution data within the second particle size range is obtained by performing autocorrelation function analysis on the scattered light intensity fluctuations and inverting calculation. By integrating soil particle size distribution data within the first particle size range and soil particle size distribution data within the second particle size range, a comprehensive soil particle size analysis report with a wide dynamic range from nanometer to millimeter is obtained.

[0019] Preferably, it also includes a central controller electrically connected to the automatic sample injection module, the static particle size measurement module and the dynamic particle size measurement module; The central controller is configured as follows: The automatic sample injection module controls the circulation pump, sample stirring assembly, and filter separator to complete the preparation, stirring, ultrasonic dispersion, and particle size separation of the test sample according to a preset program. The start-stop timing of the first laser and the illumination element in the static particle size measurement module is controlled, and the optical path state of the narrowband filter and the recessed filter is controlled in a coordinated manner. Control the data acquisition timing of the second laser, the lateral high-sensitivity PMT detector, and the backward high-sensitivity PMT detector in the dynamic particle size measurement module.

[0020] The present invention achieves the following technical effects compared to the prior art: The soil particle size analysis device based on multimodal laser scattering and imaging technology provided by this invention includes a housing, an automatic sample introduction module, a static particle size measurement module, and a dynamic particle size measurement module disposed inside the housing, and a data acquisition and analysis module disposed outside the housing. The automatic sample introduction module is used to prepare test samples and introduce the test samples into the static particle size measurement module and the dynamic particle size measurement module respectively, enabling the determination of a large concentration range of soil samples and solving the problem of poor representativeness of soil samples. The static particle size measurement module is used to perform particle size analysis on soil particles of a first size, and the dynamic particle size measurement module is used to perform particle size analysis on soil particles of a second size. Analysis shows that the first particle size is larger than the second particle size. By combining static and dynamic laser scattering analysis, a wide dynamic range of particle size measurement can be achieved, enabling a wide range of soil particle size measurement. Both the static and dynamic particle size measurement modules are electrically connected to the data acquisition and analysis module, which receives and analyzes the data obtained from both modules, facilitating fully automated measurement and analysis. Furthermore, this invention couples optical imaging with laser diffraction, acquiring more particle morphology information in addition to particle size data, solving the problem of insufficient particle morphology information when using laser particle size analyzers to determine soil particle composition. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the soil particle size analysis device based on multimodal laser scattering and imaging technology in this invention; Figure 2 This is a schematic diagram of the internal structure of the soil particle size analysis device based on multimodal laser scattering and imaging technology in this invention; Figure 3 This is a schematic diagram of the automatic sample delivery module in this invention; Figure 4 This is a schematic diagram of the static particle size measurement module in this invention; Figure 5This is a schematic diagram of the laser channel measurement in this invention; Figure 6 This is a schematic diagram of the internal structure of the beam-uniforming and beam-expanding lens of the emitting optical system at the first laser in this invention; Figure 7 This is a schematic diagram of the internal structure of the video channel in this invention; Figure 8 This is a schematic diagram of the measurement of the video channel in this invention; Figure 9 This is a schematic diagram of the dynamic particle size measurement module in this invention; Figure 10 This is a schematic diagram of the dynamic particle size measurement module in this invention; Figure 11 This is a schematic diagram of the automatic continuous sampler in this invention; Figure 12 This is a simplified structural diagram of the soil particle size analysis device based on multimodal laser scattering and imaging technology in this invention; In the diagram: 1-Box, 11-Robotic arm, 12-Robotic gripper, 13-Ultrasonic chamber, 14-Recovery frame, 15-Test tube rack, 16-Control box, 17-Sample tube; 2-Automatic sample feeding module, 21-Sample stirrer, 22-Sample mixing chamber, 23-Ultrasonic oscillator, 24-Filter dispenser, 25-Circulation pump, 26-Inlet, 27-Outlet; 3-Static particle size measurement module, 31-Video imaging detector, 311-Imaging lens, 32-Illumination element, 321-Light source lens, 33-First... Laser, 331-Lens, 34-First beam expander and homogenizer, 35-Backscatter detector, 36-Narrow band filter, 37-Focal plane detector, 38-Concave filter, 39-Large angle detector; 4-Dynamic particle size measurement module, 41-Second laser, 42-Backscatter high-sensitivity PMT detector, 43-Side high-sensitivity PMT detector, 44-Laser lens; 5-Upper cover, 6-First sample cell, 7-Second sample cell, 8-Processing circuit, 9-Base, 10-Data acquisition and analysis module. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The purpose of this invention is to provide a soil particle size analysis device based on multimodal laser scattering and imaging technology to solve the problems existing in the prior art, realize particle size measurement with a wide dynamic range and determination of soil sample concentration range, obtain particle morphology information while acquiring soil particle size data, and realize fully automatic measurement and analysis.

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] like Figures 1-12 As shown, this embodiment provides a soil particle size analysis device based on multimodal laser scattering and imaging technology, including a housing 1, an automatic sample introduction module 2, a static particle size measurement module 3, and a dynamic particle size measurement module 4 disposed inside the housing 1, and a data acquisition and analysis module 10 disposed outside the housing 1. The automatic sample introduction module 2 is used to prepare test samples and pass the test samples into the static particle size measurement module 3 and the dynamic particle size measurement module 4 respectively, which can realize the determination of a large concentration range of soil samples and solve the problem of poor representativeness of soil samples. The static particle size measurement module 3 is used to perform particle size analysis on soil particles of the first size, and the dynamic particle size measurement module 4 is used to perform particle size analysis on soil particles of the second size. Particle size analysis is performed, with the first particle size being larger than the second. By combining static and dynamic laser scattering analysis, a wide dynamic range of particle size measurement can be achieved, enabling a broad range of soil particle size measurement. Both the static particle size measurement module 3 and the dynamic particle size measurement module 4 are electrically connected to the data acquisition and analysis module 10, and are used to receive and analyze the data obtained from the static particle size measurement module 3 and the dynamic particle size measurement module 4, thereby facilitating fully automated measurement and analysis. At the same time, this embodiment couples optical imaging with laser diffraction, which can obtain more particle morphology information in addition to particle size data, solving the problem of lack of particle morphology information when laser particle size analyzers determine soil particle composition.

[0027] Specifically, the automatic sample introduction module 2 includes a sample mixing tank 22, a sample stirring assembly, a liquid level sensor, a circulation pump 25, and a filter separator 24. The upper end of the sample mixing tank 22 is open and located near the upper end of the housing 1 to facilitate the addition of solid samples. The liquid medium can be transported to the sample mixing tank 22 through the liquid inlet 26 via the liquid delivery pipeline and the circulation pump 25. The sample stirring assembly is used to mix and stir the liquid medium and solid sample in the sample mixing tank 22 to form a test sample. The inlet of the filter separator 24 is connected to the outlet of the sample mixing tank 22, and the first outlet of the filter separator 24 is connected to the inlet of the static particle size measurement module 3. The second outlet of the device 24 is connected to the inlet of the dynamic particle size measurement module 4, and the first outlet is used to discharge test samples with particle sizes greater than 1 micrometer, while the second outlet is used to discharge test samples with particle sizes less than 1 micrometer. The outlets of both the static particle size measurement module 3 and the dynamic particle size measurement module 4 are connected to a discharge port 27. A circulation pump 25 is installed on the liquid circulation pipeline between the discharge port 27 and the mixing tank. After the test, the waste liquid can be discharged from the discharge port 27. Simultaneously, the liquid inlet 26 can be connected to pure water, which circulates and cleans the pipeline in the automatic sample feeding module 2. The sample mixing tank 22 is approximately a cuboid (270 mm²). 180mm A combination of a 20mm diameter cuboid and a cylinder (100mm diameter, 80mm height), with the cylinder positioned on top of the cuboid, forms a single structure. Its volume is calculated to be 2.7. 1.8 0.2 + 3.14 0.5 0.5 0.8 ≈ 1.6 liters.

[0028] The sample mixing assembly includes a sample stirrer 21 and an ultrasonic oscillator 23. The stirring end of the sample stirrer 21 extends into the sample mixing pool 22 and stirs the test sample in the sample mixing pool 22. The ultrasonic oscillator 23 is positioned close to the sample mixing pool 22 and oscillates the test sample in the sample mixing pool 22.

[0029] Box 1 is a cuboid with an external dimension of approximately 360mm. 510mm The chamber is 740mm thick and internally divided into three layers: a dynamic particle size measurement module 4 in the lower layer, a static particle size measurement module 3 in the middle layer, and an automatic sample feeding module 2 in the upper layer. Additionally, a power supply module and an electromechanical control module are also located within the chamber. All modules are electrically connected and integrated with the liquid circulation system. The upper cover 5 can be opened at a 90° angle, and the sample stirrer 21, liquid level sensor, and feed expansion tank of the automatic sample feeding module 2 are all integrated into the upper cover 5. A power interface, a liquid inlet / outlet 27, and a USB / Ethernet communication interface are located on the side of the chamber.

[0030] The static particle size measurement module 3 has a first sample pool 6 set at the position corresponding to the first outlet, and the dynamic particle size measurement module 4 has a second sample pool 7 set at the position corresponding to the second outlet. The outlets of the first sample pool 6 and the second sample pool 7 are both connected to the discharge port 27, and the sidewalls of the first sample pool 6 and the second sample pool 7 are both made of transparent material.

[0031] Static laser scattering, also known as laser diffraction, works by passing a laser beam through a suspension of dispersed soil particles. The particles scatter the laser light, with larger particles scattering at smaller angles and smaller particles scattering at larger angles. By measuring the intensity distribution of scattered light at different angles and inverting the Mie scattering theory, the particle size distribution can be calculated.

[0032] The static particle size measurement module 3 includes a laser channel and a video channel, which are arranged in parallel and share the first sample pool 6. The laser channel includes a first laser 33, an emission optical system, a focal plane detector 37, a backscatter detector 35, and a large-angle detector 39. The first laser 33, the emission optical system, and the backscatter detector 35 are located on one side of the first sample cell 6, while the focal plane detector 37 and the large-angle detector 39 are located on the other side of the first sample cell 6. The outlet of the first laser 33 faces the first sample cell 6, the emission optical system is located near the light-emitting end of the first laser 33, and the backscatter detector 35 is located near the emission optical system. The laser channel uses the Mie scattering principle to measure the energy distribution of scattered light. Through the combination of the focal plane detector 37, the backscatter detector 35, and the large-angle detector 39, the forward and backscattered energy of the laser can be measured from multiple angles, and the particle size can be inverted through a modeless algorithm. In application, the first laser 33 emits laser light, which is expanded and homogenized by the emission optical system. When the laser light shines on the first sample cell 6, it will be scattered. The scattered energy is received by the focal plane detector 37 set at the front end of the first sample cell 6, the multi-point large-angle detector 39, and the backscattering detector 35 set at the rear end of the sample cell.

[0033] For the structure of the beam-uniforming and beam-expanding lens of the emitting optical system at the first laser 33, lens 331 is fixed in the lens barrel by metal spacers and retaining rings, and narrow-band filter 36 is fixed with optical adhesive. Precision optical adjustment ensures that the optical lenses are in their theoretical positions. The beam-uniforming and beam-expanding lens is fixed at the light-emitting port of the first laser 33 through the mounting interface. The focal plane detector 37 consists of two 4-element elements. The silicon APD array (model: S8550-02) of 8 is directly soldered onto the circuit board, which is fixed to the base 9 by 4 support pillars, and the processing circuit 8 is connected to the circuit board.

[0034] The video channel includes an illumination element 32, a first beam expander and homogenizer element 34, and a video imaging detector 31. The illumination element 32 and the video imaging detector 31 are located on both sides of the first sample cell 6, and the first beam expander and homogenizer element 34 is located between the illumination element 32 and the first sample cell 6. The illumination element 32 is preferably an LED light source, and a light source lens 321 is provided at the LED light source.

[0035] The video imaging detector 31 is preferably a high-resolution microscope or camera, which directly captures and images the particles in the first sample pool 6 in real time. Through digital image processing algorithms, the morphology of individual particles can be analyzed. The soil particle morphology results obtained through optical imaging analysis via the video channel are used to correct the particle size information obtained by laser diffraction, overcoming the uncertainties caused by the diversity of soil particle morphology and making the soil particle size analysis results more accurate.

[0036] Narrow-band filters 36 are provided between the backscattering detector 35 and the first sample cell 6, and on the side of the sample cell away from the first laser 33. By setting the narrow-band filters 36, it is ensured that the detector of the scattering measurement channel can only receive 532 nm scattering energy, which can avoid mutual interference between the video channel and the laser channel, and thus make the structure more compact. The imaging lens 311 of the video imaging detector 31 and the first beam expanding and homogenizing element 34 are both provided with recessed filters 38 to filter out the 532 nm light in the white light. This can ensure that the light emitted by the imaging channel does not contain 532 nm light, effectively avoiding interference with the scattering measurement channel. At the same time, the receiving end cannot receive 532 nm scattering energy, avoiding the non-uniformity of the image received by the imaging channel caused by laser speckle.

[0037] Both the backscattering detector 35 and the large-angle detector 39 are single-point silicon APD detectors (model: S3884). A total of 64 detectors are arranged in the entire space, including 32 backscattering detectors and 32 large-angle detectors, distributed on two arc surfaces centered on the first sample cell 6, in two rows. Eight columns, and those skilled in the art can make adaptive adjustments to the specific number according to actual needs. The transmitting end and the receiving end are respectively arranged with 532nm narrowband filters 36 to eliminate stray light interference.

[0038] Dynamic laser scattering, also known as photon correlation spectroscopy, primarily measures the random Brownian motion of tiny particles in a suspension. The smaller the particle, the faster the Brownian motion, which causes the intensity of the scattered light to fluctuate rapidly over time. By analyzing the rate of these intensity fluctuations (autocorrelation function), the diffusion coefficient of the particle can be calculated, thereby obtaining the particle size.

[0039] The dynamic particle size measurement module 4 includes a second laser 41, a second beam expanding and homogenizing element, two backward high-sensitivity PMT detectors 42, and two lateral high-sensitivity PMT detectors 43. The second laser 41 is located on one side of the second sample cell 7, and the second beam expanding and homogenizing element is provided between the second laser 41 and the second sample cell 7. The two lateral high-sensitivity PMT detectors 43 are arranged opposite to each other on both sides of the second sample cell 7, and the two lateral high-sensitivity PMT detectors 43 and the second laser 41 are respectively located on different sides of the second sample cell 7. The two backward high-sensitivity PMT detectors 42 are located on the same side of the second sample cell 7 and on both sides of the second laser 41. A laser lens 44 is provided at the second laser 41.

[0040] The dynamic particle size measurement module is mainly used to measure particles ranging from 1 nm to 1 μm in size. Dynamic light scattering technology primarily measures the fluctuations in the intensity of scattered light from particles over time. The Brownian motion of nanoparticles causes fluctuations in light intensity; statistical analysis reveals a correlation between light intensity and particle diffusion. Since the intensity of Brownian motion is significantly correlated with particle size, a relationship between particle size and the fluctuations in scattered light intensity can be established. In operation, a laser beam is emitted through a second laser 41, collimated, and homogenized before illuminating the second sample cell 7. Lateral and backward high-sensitivity PMT detectors receive the laser scattered energy in real time. Signal analysis is used to invert the light fluctuation intensity information to obtain particle information. Dynamic particle measurement achieves particle measurement over a wide concentration range by combining lateral and backward high-sensitivity PMT detectors.

[0041] This embodiment also includes an automatic continuous sampler for replenishing soil samples into the automatic sample introduction module 2. The automatic continuous sampler includes a robotic arm 11, an ultrasonic tank 13, a test tube rack 15, a recovery frame 14, and a control box 16. The end of the robotic arm 11 is equipped with a mechanical claw 12 for gripping. The control box 16 is mainly used to control the operation of the entire automatic sample introduction module 2 and consists of a PLC controller, a touch screen, and a controller for the robotic arm 11. The robotic arm 11 is a six-axis robotic arm with six degrees of freedom and can carry a maximum of 2kg of objects. The robotic arm 11 can act on 50ml sample tubes 17 and 25ml sample tubes 17 and can perform operations such as gripping, moving, pouring, and rinsing. The robotic arm 11 can grasp the sample tube 17 and move it under the control of the control box 16. The test tube rack 15 is used to place soil particles. The bottom of the ultrasonic pool 13 is equipped with an ultrasonic device that can convert electrical energy into ultrasonic waves for output. The sample in the ultrasonic pool 13 is ultrasonically treated through a carrier (usually water). The working frequency is 20kHz and the output power is 800W. Under the control of the control box 16, the robotic arm 11 can grasp the sample tube 17 and transfer it to the ultrasonic pool 13 for ultrasonic treatment. Under the control of the control box 16, the robotic arm 11 can also pour the ultrasonically treated soil particles into the automatic sample injection module 2 and transfer the sample tube 17 to the recycling box 14. The test tube rack 15 can hold 32 50ml sample tubes 17 and 32 25ml sample tubes 17. The recycling box 14 is mainly used to store and recycle used sample tubes 17.

[0042] The automatic sample introduction module 2 can be parameter-set via the touchscreen on the control box 16. After startup, the robotic arm 11 will follow the set path to grab the sample tube 17 on the test tube rack 15 and then transfer it to the ultrasonic tank 13 for ultrasonic treatment. After treatment, the robotic arm 11 will transfer the sample tube 17 to the sample mixing tank 22 of the soil particle analysis system for sample pouring and rinsing the sample tube 17 to ensure that all samples are completely transferred into the sample mixing tank 22. Finally, the robotic arm 11 will transfer the sample tube 17 to the recovery box 14.

[0043] In this embodiment, the data acquisition and analysis module 10 includes a data acquisition unit and a data processing unit. The data acquisition unit is electrically connected to the focal plane detector 37, backscatter detector 35, large-angle detector 39, and video imaging detector 31 of the static particle size measurement module 3, and the lateral high-sensitivity PMT detector and backscatter high-sensitivity PMT detector of the dynamic particle size measurement module 4, respectively, for synchronously or asynchronously acquiring the electrical signals output by each detector. The data processing unit is configured to: perform inversion calculation on the electrical signals acquired by the static particle size measurement module 3 using Mie scattering theory or mode-free algorithm to obtain soil particle size distribution data within a first particle size range; based on the electrical signals acquired by the dynamic particle size measurement module 4, perform autocorrelation function analysis on the scattered light intensity fluctuations to invert and calculate soil particle size distribution data within a second particle size range; and fuse the soil particle size distribution data within the first and second particle size ranges to obtain a comprehensive soil particle size analysis report with a wide dynamic range from nanometer to millimeter.

[0044] This embodiment also includes a central controller electrically connected to the automatic sample injection module 2, the static particle size measurement module 3, and the dynamic particle size measurement module 4. The central controller is configured to: control the circulation pump 25, sample stirring assembly, and filter separator 24 in the automatic sample injection module 2 to complete the preparation, stirring, ultrasonic dispersion, and separation of test samples according to a preset program; control the start-stop timing of the first laser 33 and illumination element 32 in the static particle size measurement module 3, and coordinately control the optical path state of the narrow band filter 36 and the recessed filter 38; and control the data acquisition timing of the second laser 41, the lateral high-sensitivity PMT detector 43, and the rearward high-sensitivity PMT detector 42 in the dynamic particle size measurement module 4.

[0045] This embodiment is based on the principle of determining particle size using laser diffraction, and combines optical imaging technology with laser static light scattering analysis, laser dynamic light scattering analysis, and morphological analysis, which has the following advantages: (1) By combining laser static scattering analysis and dynamic scattering analysis, and by automatically separating the particle samples, large-diameter particles (10μm~2000μm) enter the static particle size measurement module 3, and small particles (1nm~10μm) enter the dynamic scattering light measurement module, thus enabling one-click measurement of particle size in the range of 1nm - 2000μm in soil samples.

[0046] (2) By introducing optical imaging analysis into laser particle size analysis, optical imaging and laser diffraction are perfectly coupled. Through morphological analysis, high-resolution synchronous short exposure imaging technology is used to obtain instantaneous particle color images. Image processing algorithms are used to analyze the particles. This not only obtains more particle information such as equivalent diameter, perimeter, bending index, Fret diameter, aspect ratio, shape factor and other parameters. (3) In order to overcome the shortcomings of existing instruments that require a small amount of test samples and cannot guarantee the representativeness of the samples, this embodiment uses dynamic adjustment of laser energy, high dynamic range detector and combination of multiple detectors, and adopts a large-volume sample mixing cell 22 to achieve the determination of a large concentration range of soil samples, thus solving the problem of poor representativeness of soil samples. (4) This embodiment uses an automated sample introduction device, which can realize fully automated measurement and analysis.

[0047] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A soil particle size analysis device based on multimodal laser scattering and imaging technology, characterized in that: The system includes a housing, an automatic sample introduction module, a static particle size measurement module, and a dynamic particle size measurement module disposed inside the housing, and a data acquisition and analysis module disposed outside the housing. The automatic sample introduction module is used to prepare test samples and introduce the test samples into the static particle size measurement module and the dynamic particle size measurement module, respectively. The static particle size measurement module is used to perform particle size analysis on soil particles of a first particle size, and the dynamic particle size measurement module is used to perform particle size analysis on soil particles of a second particle size, wherein the first particle size is larger than the second particle size. Both the static particle size measurement module and the dynamic particle size measurement module are electrically connected to the data acquisition and analysis module and are used to receive and analyze the data obtained by the static particle size measurement module and the dynamic particle size measurement module.

2. The soil particle size analysis device based on multimodal laser scattering and imaging technology according to claim 1, characterized in that: The automatic sample feeding module includes a sample mixing tank, a sample stirring assembly, a liquid level sensor, a circulation pump, and a filter separator. The sample mixing tank is open at the top and located near the top of the housing. The sample stirring assembly is used to mix and stir the liquid medium and solid sample in the sample mixing tank to form a test sample. The inlet of the filter separator is connected to the outlet of the sample mixing tank. The first outlet of the filter separator is connected to the inlet of the static particle size measurement module, and the second outlet of the filter separator is connected to the inlet of the dynamic particle size measurement module. The first outlet is used to discharge test samples with particle sizes greater than 1 micrometer, and the second outlet is used to discharge test samples with particle sizes less than 1 micrometer. The outlets of the static particle size measurement module and the dynamic particle size measurement module are both connected to a discharge port. The circulation pump is located on the liquid circulation pipeline between the discharge port and the mixing tank.

3. The soil particle size analysis device based on multimodal laser scattering and imaging technology according to claim 2, characterized in that: The sample mixing assembly includes a sample stirrer and an ultrasonic oscillator. The stirring end of the sample stirrer extends into the sample mixing pool and stirs the test sample in the sample mixing pool. The ultrasonic oscillator is positioned close to the sample mixing pool and oscillates the test sample in the sample mixing pool.

4. The soil particle size analysis device based on multimodal laser scattering and imaging technology according to claim 2, characterized in that: The static particle size measurement module has a first sample pool at the position corresponding to the first outlet, and the dynamic particle size measurement module has a second sample pool at the position corresponding to the second outlet. The outlets of the first sample pool and the second sample pool are both connected to the discharge port, and the sidewalls of the first sample pool and the second sample pool are both made of transparent material.

5. The soil particle size analysis device based on multimodal laser scattering and imaging technology according to claim 4, characterized in that: The static particle size measurement module includes a laser channel and a video channel, which are arranged in parallel and share the first sample pool. The laser channel includes a first laser, an emitting optical system, a focal plane detector, a backscatter detector, and a large-angle detector. The first laser, the emitting optical system, and the backscatter detector are located on one side of the first sample pool, and the focal plane detector and the large-angle detector are located on the other side of the first sample pool. The outlet of the first laser is arranged facing the first sample pool. The emitting optical system is arranged close to the light-emitting end of the first laser, and the backscatter detector is arranged close to the emitting optical system. The video channel includes an illumination element, a first beam expander and homogenizer element, and a video imaging detector. The illumination element and the video imaging detector are located on opposite sides of the first sample pool, and the first beam expander and homogenizer element is located between the illumination element and the first sample pool.

6. The soil particle size analysis device based on multimodal laser scattering and imaging technology according to claim 5, characterized in that: Narrow-band filters are provided between the backscatter detector and the first sample cell, and on the side of the sample cell away from the first laser. Recessed filters are provided at the imaging lens of the video imaging detector and at the first beam expanding and homogenizing element. Both the backscatter detector and the large-angle detector are single-point silicon APD detectors, and the backscatter detector and the large-angle detector are respectively distributed on two arc surfaces centered on the first sample cell.

7. The soil particle size analysis device based on multimodal laser scattering and imaging technology according to claim 6, characterized in that: The dynamic particle size measurement module includes a second laser, a second beam expander and homogenizer, two backward high-sensitivity PMT detectors, and two lateral high-sensitivity PMT detectors. The second laser is located on one side of the second sample cell, and the second beam expander and homogenizer is provided between the second laser and the second sample cell. The two lateral high-sensitivity PMT detectors are arranged opposite each other on both sides of the second sample cell, and the two lateral high-sensitivity PMT detectors and the laser are respectively located on different sides of the second sample cell. The two backward high-sensitivity PMT detectors are located on the same side of the second sample cell and on both sides of the laser.

8. The soil particle size analysis device based on multimodal laser scattering and imaging technology according to claim 1, characterized in that: It also includes an automatic continuous sampler for replenishing soil samples into the automatic sampling module. The automatic continuous sampler includes a robotic arm, an ultrasonic tank, a test tube rack, a recovery box, and a control box. The robotic arm is a six-axis robotic arm, and under the control of the control box, it can grasp the sample tube and move the sample tube. The test tube rack is used to place soil particles. Under the control of the control box, the robotic arm can grasp the sample tube and transfer it to the ultrasonic tank for ultrasonic treatment. Under the control of the control box, the robotic arm can also pour the ultrasonically treated soil particles into the automatic sampling module and transfer the sample tube to the recovery box.

9. The soil particle size analysis device based on multimodal laser scattering and imaging technology according to claim 7, characterized in that: The data acquisition and analysis module includes a data acquisition unit and a data processing unit; The data acquisition unit is electrically connected to the focal plane detector, backscatter detector, large angle detector, and video imaging detector of the static particle size measurement module, as well as the lateral high-sensitivity PMT detector and the back high-sensitivity PMT detector of the dynamic particle size measurement module, and is used to synchronously or asynchronously acquire the electrical signals output by each detector. The data processing unit is configured as follows: Using Mie scattering theory or mode-free algorithms, the electrical signals collected by the static particle size measurement module are inverted and calculated to obtain soil particle size distribution data within the first particle size range. Based on the electrical signals collected by the dynamic particle size measurement module, the soil particle size distribution data within the second particle size range is obtained by performing autocorrelation function analysis on the scattered light intensity fluctuations and inverting calculation. By integrating soil particle size distribution data within the first particle size range and soil particle size distribution data within the second particle size range, a comprehensive soil particle size analysis report with a wide dynamic range from nanometer to millimeter is obtained.

10. The soil particle size analysis device based on multimodal laser scattering and imaging technology according to claim 7, characterized in that: It also includes a central controller electrically connected to the automatic sample injection module, the static particle size measurement module and the dynamic particle size measurement module; The central controller is configured as follows: The automatic sample injection module controls the circulation pump, sample stirring assembly, and filter separator to complete the preparation, stirring, ultrasonic dispersion, and particle size separation of the test sample according to a preset program. The start-stop timing of the first laser and the illumination element in the static particle size measurement module is controlled, and the optical path state of the narrowband filter and the recessed filter is controlled in a coordinated manner. Control the data acquisition timing of the second laser, the lateral high-sensitivity PMT detector, and the backward high-sensitivity PMT detector in the dynamic particle size measurement module.

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