CN212301218U - Nano-particle analyzer based on back scattering cross-correlation technology - Google Patents

Abstract

The utility model discloses a nanometer particle analyzer based on backscattering cross-correlation technique, which comprises a sample cell, detectors, a laser, a lens group, a first data acquisition card, a second data acquisition card, a control unit, wherein laser emitted by the laser irradiates on a sample in the sample cell through the lens group, the two detectors receive scattered light of the sample simultaneously and transmit signals to the control unit through the first data acquisition card and the second data acquisition card respectively; the motor control circuit also comprises a microprocessor, wherein the signal input end of the microprocessor receives the instruction of the control unit, and the output end of the microprocessor outputs a control signal to be connected into the motor control loop. The utility model discloses the real realization of backscatter cross-correlation nanometer particle analyzer that has combined the backscattering technique of portable sample check point and cross-correlation to calculate has accurately detected to high concentration high turbidity sample to the fast correlation computing power has further been promoted. The device has good popularization and practical value, and can produce good economic and social benefits after wide popularization and application.

Description

Nano-particle analyzer based on back scattering cross-correlation technology

Technical Field

The utility model relates to a nanometer particle analyzer specifically is a nanometer particle analyzer based on backscattering cross correlation technique.

Background

The nano-particle size meter is based on a dynamic light scattering technique, and uses a beam of laser to illuminate a sample, and a photodetector to detect fluctuations in scattered light caused by brownian motion of particles suspended in a liquid. The fluctuation signal of the original scattered light intensity along with time is subjected to correlation calculation to obtain a correlation curve of the system, and then the particle size and the particle size distribution of the particles are obtained through different mathematical models, such as an accumulation method or a multi-index method.

Generally speaking, the nanometer particle size analyzer can effectively detect a particle system with a particle size range of about 1 nanometer to 1000 nanometers, and has the characteristics of high test speed, wide range, good repeatability and accuracy and the like, so that the nanometer particle size analyzer is widely applied.

The existing nanometer particle size analyzer widely adopts an autocorrelation technology, and cannot effectively eliminate the multiple light scattering effect of a high-concentration high-turbidity sample. The multiple light scattering effect causes the detected particle size results to be small compared to the true values and the particle size distribution to be broadened compared to the true values, which is especially serious in the widely used 90-degree angle nanometer particle sizers. Although the non-invasive backscatter technique NIBS developed in recent years can avoid multiple light scattering techniques to some extent, and thus has the fundamental ability to detect high-concentration and high-turbidity samples, such passive avoidance still cannot essentially eliminate the multiple light scattering effect.

SUMMERY OF THE UTILITY MODEL

The problem to be solved by the utility model is to provide a nanometer particle analyzer based on backscattering cross-correlation technique, which aims at the defects of insufficient detection capability, low detection accuracy and electronic delay noise within the range of 25ns-1 mus for high-concentration and high-turbidity samples in the prior art.

In order to solve the technical problem, the utility model discloses a technical scheme is:

the utility model provides a nanometer particle analyzer based on backscattering cross correlation technique, including sample cell, detector, laser instrument, battery of lens, first ~ two data acquisition card and the control unit, wherein the laser of laser instrument transmission shines the sample in the sample cell through the battery of lens on, and the scattered light of sample is received simultaneously to two detectors to respectively through first ~ two data acquisition card with signal transmission to the control unit.

The utility model discloses still have microprocessor, its signal input part receives the control unit's instruction, and output control signal connects to in the motor control circuit.

The two detectors are symmetrically arranged on two sides of an incident laser beam of the laser and respectively receive sample scattered light captured by the lens group through optical fibers.

The lens group is arranged on the motor through the lens group bracket.

The utility model discloses still have the switching separation blade, install between fiber support and battery of lens, switch separation blade one end and motor output shaft.

The utility model has the following beneficial effects and advantages:

1. the utility model discloses the real realization of backscatter cross-correlation nanometer particle analyzer that has combined the backscattering technique of portable sample check point and cross-correlation to calculate has accurately detected to high concentration high turbidity sample to the fast correlation computing power has further been promoted. The device has good popularization and practical value, and can produce good economic and social benefits after wide popularization and application.

2. The utility model adopts the nanometer particle analyzer which combines the backscattering cross-correlation technology of collecting backscattering signals, movable sample detection points and cross-correlation calculation logic to collect the backscattering light and move the position of the detection points, thus realizing the collection of high-concentration sample signals; the cross-correlation calculation can eliminate not only the interference of multiple light scattering, but also the electronic delay noise in the range of 25ns-1 mus of the detector.

3. The utility model discloses the wide application is in accurate electrician, electron, instrument and meter and other products, mainly is applied to research application such as medical health, bio-pharmaceuticals, agricultural scientific research, environmental protection.

Drawings

FIG. 1 is an electrical schematic diagram of a nanometer particle analyzer based on the back scattering cross-correlation technique of the present invention;

fig. 2 is a schematic view of the optical path structure of the present invention;

FIG. 3 is a schematic diagram illustrating the position definition of the detection point in the present invention;

FIG. 4A is a schematic diagram of the focusing point of the moving lens of the low/medium concentration (low shading rate) sample motor of the present invention receiving scattered light in the middle of the sample cell;

FIG. 4B is a schematic diagram of the high concentration (high shading rate) sample motor moving lens focusing point receiving scattered light at the sample cell edge;

FIG. 5 is a flow chart of a dynamic light scattering test performed by selecting a position of a detection point according to the method of the present invention;

FIG. 6 is a schematic diagram of a correlation curve involved in the method of the present invention;

FIG. 7 is a graph of a correlation curve for electron delay noise and a correlation curve for canceling electron delay noise.

Fig. 8 shows the state where the shutter is in the light path blocking state or the light path opening state.

The device comprises a laser 1, a sample cell 2, a laser 3, an optical fiber support 4, a scattered light 5, a detection point 6, a first optical fiber 7, a second optical fiber 8, a motor bearing 9, a lens group 10, a sample 11, a switching baffle plate 12, a motor 13, first to second photodiodes 14 to 15 and first to second data acquisition cards 16 to 17.

Detailed Description

The invention will be further explained with reference to the drawings attached to the specification.

As shown in FIG. 1, the utility model provides a nanometer particle analyzer based on backscattering cross-correlation technique, including sample cell 2, detector, laser instrument, battery of lenses 10, first ~ two data acquisition card 16 ~ 17 and the control unit, wherein laser 1 of laser instrument transmission shines on the sample in the sample cell through the battery of lenses, and two detectors receive the reverberation of sample simultaneously to respectively through first ~ two data acquisition card with signal transmission to the control unit.

The utility model discloses still have microprocessor, its signal input part receives the instruction of the control unit (PC), and output control signal connects to in the motor control circuit.

The two detectors are symmetrically arranged on two sides of an incident laser beam of the laser and respectively receive sample scattered light captured by the lens group through optical fibers. In the present embodiment, the detectors include first to second avalanche photodiodes APD1 to APD 2.

As shown in fig. 2, the lens group is mounted on the motor by a lens group holder. The utility model discloses still have switching separation blade 12, install between fiber support 4 and battery of lens, switch separation blade and motor output shaft, rotate through motor drive, hinder and keep off one side light path between fiber support 4 and the battery of lens, realize the switching of auto-correlation detection light path or cross correlation detection light path. In this embodiment, the switching separation blade is rectangular shaped plate, and one end and a micro motor's output shaft fixed connection use the output shaft fixed position as the centre of a circle rotatory under the drive of motor, and the other end of rectangular shaped plate can shelter from the incident light side at the battery of lens just after rotating to the position. When the light shading rate or turbidity of the sample is high, the switching baffle plate 12 is opened, two detection lights are received simultaneously, cross-correlation operation is carried out, and when the light shading rate or turbidity of the sample is low, the switching baffle plate 12 is closed, and one receiving scattered light is used for carrying out self-correlation operation.

The utility model discloses a control unit control high accuracy motor removes the sample check point (laser light path and optic fibre observation light path focus promptly), can use the sample cell wall to remove to the sample cell center as 0 point benchmark, and the migration range is 0 ~ 5mm, the best curve efficiency point of automatic seeking cross correlation curve signal or autocorrelation curve signal, as shown in fig. 4A ~ 4B.

The detection point position is shown in fig. 3 as the convergence point of the laser and detector directions.

The laser emitted by the laser irradiates on the sample in the sample cell 2 through a lens group 10 arranged on a motor bearing 9 of the motor, and the emitting direction of the laser is 0 degree. The scattered light signals are synchronously collected in two paths through a first optical fiber 7 and a second optical fiber 8 which are symmetrically arranged in the back direction, are respectively transmitted to a first detector APD 1-APD 2, and are in communication connection with a computer through a data acquisition card 1 and a data acquisition card 2. And performing cross-correlation operation on the scattered light signals synchronously obtained by the two detectors in the control unit to finally obtain a cross-correlation curve. As shown in fig. 8, the motor may be used to drive the switching flap 11 to block one side of the optical path to collect scattered light signals in a single path, and the scattered light signals obtained by the first (or second) detector (using the first photodiode APD1 (or second photodiode APD2) may be subjected to autocorrelation calculation in the control unit to obtain an autocorrelation curve.

As shown in fig. 5, the present invention relates to a detection method for a nanometer particle analyzer based on the backscattering cross-correlation technique, which comprises the following steps:

1) the control unit controls the motor to move, so that the focusing point of the lens group is positioned at the middle position of the sample cell;

2) collecting raw scattered light signals by a detector;

3) calculating a cross-correlation curve to obtain curve efficiency and recording the curve efficiency;

4) judging whether the position of the focus point is a specified distance away from the wall of the sample pool;

5) if the distance is the specified distance, comparing the efficiency of the cross-correlation curves of different focusing positions, and finding out a position point corresponding to the highest efficiency of the curves;

6) the control unit controls the motor to move the lens to a position point corresponding to the highest curve efficiency;

7) collecting the original scattered light signal again by the detector;

8) performing cross-correlation calculation to obtain a cross-correlation curve;

9) and obtaining the diffusion coefficient of the sample particles through a cross-correlation curve, and further obtaining the particle size of the particles through a Stokes Einstein equation.

Further comprising step 10): in the step 4), if the position of the focus point is judged to be not a specified distance from the wall of the sample pool; the control unit sends a command to make the motor drive the lens group to move to a specified distance from the wall of the sample cell.

The specified distance in step 3) is: and moving the sample cell to the center of the sample cell by taking the wall of the sample cell as a 0-point reference, wherein the moving distance can be selectively adjusted within the range of 0.1-1.0 mm each time so as to find the optimal efficiency point of the related curve signal.

In the step 2), original scattered light signals are collected through a detector, an autocorrelation detection light path or a cross-correlation detection light path is selected according to the light shading rate or turbidity of the sample, and for a transparent sample with the light shading rate or turbidity lower than a threshold value (for example, the light shading rate is not higher than 10%), a baffle is arranged in the light path to block the other detector to collect single-detector light path signals and perform autocorrelation operation;

and (2) carrying out double-detector light path signal acquisition on a sample with the light shading rate or turbidity higher than a threshold value (for example, the light shading rate exceeds 10%), carrying out cross-correlation operation on the obtained scattered light signals, avoiding multiple light scattering phenomena, effectively inhibiting fast attenuation electronic noise of a correlation curve signal within the range of 25ns-1 mu s, and obtaining accurate correlation curve information within wider correlation calculation time. In fig. 7, □ is a correlation curve containing electron delay noise, and o is a correlation curve for eliminating electron delay noise by the cross-correlation technique.

According to the turbidity of the visual sample, the switch of the self-correlation detection light path and the cross-correlation detection light path is realized by manual operation and a motor-driven switch baffle 12.

As shown in fig. 6, the normalized correlation curve diagram implemented by the detection method of the present invention is shown, and the corresponding value of the first channel is the correlation curve efficiency.

Claims (5)

1. A nanometer particle analyzer based on backscattering cross-correlation technology is characterized in that: the device comprises a sample cell, detectors, a laser, a lens group, a first data acquisition card, a second data acquisition card and a control unit, wherein laser emitted by the laser irradiates a sample in the sample cell through the lens group, and the two detectors simultaneously receive scattered light of the sample and respectively transmit signals to the control unit through the first data acquisition card and the second data acquisition card.

2. The nanometer particle analyzer based on the backscatter cross-correlation technique of claim 1, wherein: the motor control circuit also comprises a microprocessor, wherein the signal input end of the microprocessor receives the instruction of the control unit, and the output end of the microprocessor outputs a control signal to be connected into the motor control loop.

3. The nanometer particle analyzer based on the backscatter cross-correlation technique of claim 1, wherein: the two detectors are symmetrically arranged on two sides of an incident laser beam of the laser and respectively receive sample scattered light captured by the lens group through optical fibers.

4. The nanometer particle analyzer based on the backscatter cross-correlation technique of claim 1, wherein: the lens group is arranged on the motor through the lens group bracket.

5. The nanometer particle analyzer based on the backscatter cross-correlation technique of claim 1, wherein: the switching separation blade is arranged between the optical fiber support and the lens group, and one end of the switching separation blade is connected with the output shaft of the motor.

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