CN218067553U - Particle size different-axis scanning light scattering measuring device for water body small-particle-size suspended matters - Google Patents
Particle size different-axis scanning light scattering measuring device for water body small-particle-size suspended matters Download PDFInfo
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- CN218067553U CN218067553U CN202222175440.3U CN202222175440U CN218067553U CN 218067553 U CN218067553 U CN 218067553U CN 202222175440 U CN202222175440 U CN 202222175440U CN 218067553 U CN218067553 U CN 218067553U
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Abstract
The utility model provides a water small-particle diameter suspended solid granularity anisometric scanning light scattering measuring device, include: the device comprises a laser, a beam expander, a small hole, a Fourier lens, a sample cell, a rotating platform and a photomultiplier; the beam expander, the small hole, the Fourier lens, the diaphragm, the rotary table and the sample pool are sequentially arranged behind the laser; a photomultiplier is arranged on the rotating arm of the rotating table; a laser emits a single beam of light which serves as an excitation light source of the device and irradiates the beam expander; the beam expander is used for changing the beam diameter and the divergence angle of the single laser; a small hole and a Fourier lens are arranged behind the beam expander, and the small hole is arranged at the common focus of the beam expander and the Fourier lens; the Fourier lens converges the light beams filtered by the small holes; a diaphragm is arranged behind the Fourier lens and used for filtering the edge of the converged light beam, so that the laser beam is more uniform; and a rotating platform and a sample pool are arranged behind the diaphragm.
Description
Technical Field
The utility model belongs to ecological environment science field, especially a water small-diameter suspended solid granularity anisometric scanning light scattering measuring device.
Background
In the face of increasing demands for detecting the particle size of suspended matters in water, the traditional methods such as a screening method, a sedimentation method, an electron microscope method and the like have large measurement limitation, are only suitable for laboratory measurement, and are not good enough for real-time detection of complex sampling sites. The static light scattering method is used as a light scattering detection method, has the advantages of real-time measurement, high measurement precision and the like, can effectively break through the limitation that the traditional measurement method cannot carry out on-site real-time measurement, and can rapidly measure the particle size distribution of the particle group to be measured, thereby analyzing the source, the physicochemical property and the like of the particles, predicting the influence of the particles on the water body, preparing a solution in advance, and playing an important role in lake water quality management and drinking water safety control.
A scattered light measuring blind area exists in a light path structure of a classical static light scattering method. Because the refractive index difference exists between the air and the liquid medium, when laser beams vertically irradiate on the sample cell after being expanded and filtered, and particle scattered light is transmitted into the air from the liquid medium, the particle scattered light is interfered by the total reflection of the sample cell, so that a part of the particle scattered light cannot be normally transmitted into the air and cannot be collected by a detector. When pure water is used as a liquid medium, the measurement blind area is 48.8-131.2 degrees, the propagation direction of the laser main shaft is taken as the 0-degree direction, and the measurement blind area is shown in figure 1. However, the scattered light in this angular range contains important characteristic information of small-particle-size particles, and is very important for realizing the measurement of the particle size distribution of the small-particle-size particles. In order to realize the scattered light collection in the range, british Mark company provides a double-light-source technology, but the data splicing problem in the technology is still difficult to solve; the american beckmann coulter proposed the PIDS technique (differential scattering intensity of polarized light), but this technique has a narrow measurement range and cannot be applied to a particle system having a wide particle size distribution range.
The forward, lateral and backward scattered light of the small-particle size particles contains particle size related characteristic information, so that the acquisition of the scattered light in forward, lateral and backward wide-angle ranges plays an important role in the particle size measurement of the small-particle size particles.
For forward light scattering signals, an annular detector or a CMOS is usually used for acquisition, but the forward light scattering signals are limited by the size of the annular photodetector and the CMOS range, and only forward small-angle (0-15 degrees) scattered light can be detected, so that the forward large-angle and lateral light scattering signals are difficult to detect. If the annular photodetector size and CMOS footprint are increased, there are two limiting factors: (1) the annular photoelectric detector is processed without a molding flow production line, so that the cost for processing the common annular photoelectric detector is very high, and if the area is continuously increased, the cost is multiplied; (2) the measurement lower limit of the maximum surface amplitude COMS on the market can only be expanded to 10 mu m, and the detection of particle scattered light signals in a small particle size interval cannot be realized.
For side and back scattered signals, detection is usually achieved by a photodetector array, and currently, the following two arrangements are commonly used for the detector array: (1) placing a detector on an arc which takes a sample pool as a circle center and takes the linear distance from the sample pool to the focus of the Fourier mirror as a radius; (2) and placing the detector on an arc with the diameter of the straight-line distance from the sample pool to the focus of the Fourier mirror. The first placing mode needs to occupy larger space, so that the device is larger in size, more side scattering light is obtained by the mode through sacrificing the system size, the whole system is guaranteed to have high measurement precision, and the mode is difficult to realize backward weak signal measurement. Compared with the first placement mode, the second placement mode occupies smaller volume, but reduces the measurement accuracy, and the measurement accuracy is related to the number of detectors, so that the structural design of the system is complex, and the cost is high.
SUMMERY OF THE UTILITY MODEL
In order to solve the technical problem, the utility model discloses to sample cell total reflection, wide-angle range light energy distribution detection problem develop the research, provide a water small-size suspended solid granularity heteroaxial scanning light scattering measurement device, adopt oblique incidence single detector heteroaxial multi-angle scanning measurement mode, can satisfy small-size suspended solid particle's particle size measurement demand. The rotating table is utilized to drive the photomultiplier to rotate and detect scattered light signals in a large angle by taking the sample pool as a center; the detection sensitivity of lateral and backward scattering signals is improved by shortening the distance between the detector and the sample cell; an off-axis measurement mode is designed, namely, the photomultiplier is placed 30mm below a laser main shaft, forward light spot interference is avoided, and the problem of forward measurement blind areas is effectively solved; the sample cell is obliquely arranged, so that the included angle between the laser main shaft and the incident glass surface of the sample cell is kept to be 45 degrees, and the problem of total reflection caused by total reflection of the sample cell is effectively solved. The device can detect effective scattered light signals within the angle ranges of 0-90 degrees and 145-157 degrees with high sensitivity, and can realize accurate measurement of the particle size distribution of small-particle-size particles between 350nm and 2 mu m by combining with a Mie scattering theoretical model. The device has the advantages of simple structure, low cost, wide measurement angle range and adjustable measurement precision as required, can effectively solve the problems of measurement blind areas and side-backward weak light scattering signal detection of total reflection of the sample cell, and is a new means for rapidly measuring the granularity of suspended substances with small particle sizes in water.
The technical scheme of the utility model is that: a water body small particle size suspended solid granularity anisotropism scanning light scattering measuring device includes: the device comprises a laser, a beam expander, a small hole, a Fourier lens, a sample cell, a rotating platform and a photomultiplier; the beam expander, the small hole, the Fourier lens, the diaphragm, the rotary table and the sample pool are sequentially arranged behind the laser;
a photomultiplier is arranged on the rotating arm of the rotating table; the method comprises the following steps of placing a photomultiplier at a preset distance below a laser main shaft by adopting an off-axis measurement mode, avoiding forward light spot interference, and carrying out blind area measurement, wherein a laser emits a single beam of light serving as an excitation light source of the device to irradiate a beam expander;
the beam expander is used for changing the beam diameter and the divergence angle of the single laser;
a small hole and a Fourier lens are arranged behind the beam expander, and the small hole is arranged at the common focus of the beam expander and the Fourier lens;
the Fourier lens converges the light beams filtered by the small holes;
a diaphragm is arranged behind the Fourier lens and used for filtering the converged beam edge to enable the laser beam to be more uniform;
a rotating platform and a sample pool are arranged behind the diaphragm; the revolving stage is coaxial with the sample cell in vertical direction for it is further that drive photomultiplier realization wide-angle scanning, the aperture be used for the filtering by the beam expander on dust etc. by the produced high frequency noise signal of laser irradiation, only through the low frequency laser signal in the space, improve the detection precision of system to the granule scattered light that awaits measuring, and be used for controlling laser spot size.
Further, the sample cell is used for depositing the granule crowd sample that awaits measuring, and the material is quartz glass, and the sample cell is the cuboid structure, and the sample cell major axis is 45 with the main optical axis contained angle.
Furthermore, the photomultiplier is arranged on a rotating arm taking the sample cell as the center, and scattered light signals of the particles to be detected at different angles are collected in a rotating mode.
Furthermore, the detector is placed on an arc which takes the sample pool as the center of a circle and takes the 1/2 linear distance from the sample pool to the focus of the Fourier lens as the radius.
Further, a rotating platform and a sample pool are arranged behind the diaphragm; the rotating platform and the sample pool are strictly coaxial in the vertical direction and are used for driving the photomultiplier to realize rotary scanning.
Has the beneficial effects that:
1. the device provided by the utility model has the advantages of simple system structure, wide measurement angle range and adjustable measurement precision as required, thereby not only controlling the cost, but also effectively solving the problems of measurement blind areas of the total reflection of the sample cell and the detection of side-to-back weak light scattering signals;
2. the utility model designs a single detector multi-angle scanning measurement mode, selects the photomultiplier as the detector, puts the detector in the circular arc that uses the sample cell as the centre of a circle, and the 1/2 straight-line distance from the sample cell to the focus of the Fourier mirror is the radius, shortens the distance between the detector and the sample cell, improves the detection sensitivity of lateral and backward scattering signals, and drives the photomultiplier to use the sample cell as the center through the rotating platform, and the scattered light signals on the large angle of rotary detection are detected;
3. the utility model designs a photomultiplier tube different-axis measuring mode, the photomultiplier tube is placed at the position 30mm below the laser main shaft or at a lower position, as shown in figure 3, forward facula interference is avoided, the problem of forward measuring blind area is effectively solved, and forward and lateral complete light energy distribution can be obtained;
4. the utility model designs a sample cell slope mode of placing, the contained angle of laser main shaft and sample cell incident glass face is 45, makes smooth outgoing of 48.8 ~ 131.2 scope scattered light, has effectively solved the total reflection problem that the sample cell total reflection leads to.
Drawings
FIG. 1: a schematic diagram of a light path structure scattering light measurement blind area of a classical static light scattering method;
FIG. 2 is a schematic diagram: the utility model discloses a schematic diagram of a water body small-particle-size suspended matter particle size different-axis scanning light scattering measuring device;
FIG. 3: a schematic diagram of an anisometric measurement mode of a photomultiplier;
FIG. 4 is a schematic view of: schematic diagram of effective scattering angle.
Detailed Description
The technical solution in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by a person of ordinary skill in the art without any inventive work belong to the protection scope of the present invention based on the embodiments of the present invention.
According to the embodiment of the utility model, a water small-particle diameter suspended solid granularity anisometric axis scanning light scattering measurement device is proposed, according to water small-particle diameter suspended solid particle granularity on-line measuring demand, adopts anisometric multi-angle scanning light scattering measurement device structure, and the device overall structure is as shown in figure 2.
The device includes laser instrument, beam expanding lens, aperture, fourier lens, sample cell, revolving stage, photomultiplier (PMT) etc. through the cooperation between 8 parts, realizes the measurement of the small-particle diameter suspended particles particle diameter of water.
Wherein, a beam expander, a small hole, a Fourier lens, a diaphragm, a rotary table and a sample cell are sequentially arranged behind the laser; a photomultiplier is arranged on the rotating arm of the rotating table;
a single beam of light with the wavelength of 635nm emitted by a laser is used as an excitation light source of the device and irradiates the beam expander;
the beam expander is used for changing the beam diameter and the divergence angle of the single laser;
a small hole and a Fourier lens are arranged behind the beam expander, the diameter of the small hole is 5 micrometers, and the small hole is arranged at the common focus of the beam expander and the Fourier lens. The function of the pores is twofold: firstly, high-frequency noise signals generated by laser irradiation of dust and the like on the beam expander are filtered, and only low-frequency laser signals in the space are passed, so that the detection precision of the system on the scattered light of particles to be detected is improved; secondly, controlling the size of laser facula;
the Fourier lens converges (focuses) the light beams after the small-hole filtering;
a diaphragm is arranged behind the Fourier lens and used for filtering the edge of the converged light beam, so that the laser beam is more uniform;
a rotating platform and a sample pool are arranged behind the diaphragm; the rotating platform and the sample pool are strictly coaxial in the vertical direction and are used for driving the photomultiplier to realize large-angle scanning.
The sample cell is used for storing a particle group sample to be detected, is made of quartz glass, is of a cuboid structure and has the size of 40 multiplied by 10 multiplied by 60mm, the included angle between the long axis of the sample cell and the main optical axis is 45 degrees, the initial position with the laser propagation direction of 0 degree is selected, and scattered light in the range of 48.8 degrees to 131.2 degrees can be smoothly emitted; the utility model designs a sample cell slope mode of placing, the contained angle of laser main shaft and sample cell incident glass face is 45, makes 48.8 ~ 131.2 scope scattered light emergent smoothly, has effectively solved the total reflection problem that the sample cell total reflection leads to, as shown in figure 4, owing to have mechanical structure to shelter from, the influence of specular reflection light interference, effective angle is 0 ~ 90 and 203 ~ 214.
In the embodiment of the utility model, a Photomultiplier (PMT) is arranged on a rotating arm which takes a sample cell as a center, and scattered light signals of particles to be detected at different angles are collected in a rotating way; the position and the inclination angle of the sample cell are kept fixed, and the photomultiplier is driven by the rotating arm to realize multi-angle measurement. According to the embodiment of the utility model, the photomultiplier is placed 30mm below the laser main shaft by designing the different-axis measuring mode of the photomultiplier, as shown in fig. 3, the forward facula interference is avoided, the forward measuring blind area problem is effectively solved, and the complete light energy distribution in the forward and lateral directions can be obtained; according to other embodiments of the present invention, the device can be placed at a lower position below 30 mm; alternatively, the distance may be in a range of 20-40mm, etc., as long as forward spot interference can be avoided;
while the foregoing has been with reference to illustrative embodiments of the invention in order to facilitate a person skilled in the art in understanding the invention, it is to be understood that the invention is not limited to the specific embodiments disclosed and that modifications and variations will be apparent to those skilled in the art, except as may be made within the spirit and scope of the invention as defined and limited by the appended claims.
Claims (6)
1. The utility model provides a water small-particle size suspended solid granularity heteroaxial scanning light scattering measuring device which characterized in that includes: the device comprises a laser, a beam expander, a small hole, a Fourier lens, a sample cell, a rotating platform and a photomultiplier; the beam expander, the small hole, the Fourier lens, the diaphragm, the rotating platform and the sample cell are sequentially arranged behind the laser;
a photomultiplier is arranged on the rotating arm of the rotating table; the method comprises the following steps of placing a photomultiplier at a preset distance below a laser main shaft by adopting an off-axis measurement mode, avoiding forward light spot interference, and carrying out blind area measurement, wherein a laser emits a single beam of light serving as an excitation light source of the device to irradiate a beam expander;
the beam expander is used for changing the beam diameter and the divergence angle of the single laser;
a small hole and a Fourier lens are arranged behind the beam expander, and the small hole is arranged at the common focus of the beam expander and the Fourier lens;
the Fourier lens converges the light beams filtered by the small holes;
a diaphragm is arranged behind the Fourier lens and used for filtering the edge of the converged light beam, so that the laser beam is more uniform;
a rotating platform and a sample pool are arranged behind the diaphragm; the rotating platform is coaxial with the sample pool in the vertical direction and is used for driving the photomultiplier to realize large-angle scanning.
2. The device for measuring the scattering of light by scanning the particle size of the small-particle-size suspended matter in the water body in an anisometric manner according to claim 1, wherein the sample cell is used for storing a sample of the particle group to be measured and is made of quartz glass.
3. The water body small particle size suspended matter particle size anisometric scanning light scattering measurement device of claim 2, characterized in that:
the sample cell is the cuboid structure, and sample cell major axis is 45 with the primary optical axis contained angle.
4. The water body small particle size suspended matter particle size anisometric scanning light scattering measurement device of claim 1, characterized in that:
the photomultiplier is arranged on a rotating arm taking the sample cell as a center and is used for rotationally collecting scattered light signals of particles to be detected at different angles.
5. The water body small particle size suspended matter particle size anisometric scanning light scattering measurement device of claim 1, characterized in that:
and placing the detector on an arc taking the sample cell as the center of a circle and taking 1/2 of the linear distance from the sample cell to the focus of the Fourier mirror as the radius.
6. The water body small particle size suspended matter particle size anisometric scanning light scattering measurement device of claim 1, characterized in that:
the preset distance is 30mm, namely the photomultiplier is placed at the position 30mm below the laser main shaft or at the position below 30 mm.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116242252A (en) * | 2023-05-11 | 2023-06-09 | 之江实验室 | Scattering imaging method with positioning and size measuring functions |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116242252A (en) * | 2023-05-11 | 2023-06-09 | 之江实验室 | Scattering imaging method with positioning and size measuring functions |
| CN116242252B (en) * | 2023-05-11 | 2023-08-15 | 之江实验室 | Scattering imaging method with positioning and size measuring functions |
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