CN201622228U - Dynamic polarized light scattered grain measuring device - Google Patents

Abstract

The utility model relates to a dynamic polarized light scattered grain measuring device. The laser which is transmitted from a laser device sequentially enters into a polarizer, a half wave plate and a lens to form an incident light path; the light which is outputted by lens focus is irradiated on a grain sample in a sample pond; and the scattered light which is vertical to the direction of the incident laser and is generated by the sample grain which is irritated by the laser beam sequentially enters into an aperture diaphragm, a detector and the aperture diaphragm to form into a receiving light path, and finally enters into a photomultiplier, so that a light signal is converted into an electric signal, the electric signal is outputted to enter into a digital correlator for counting, and finally data is transmitted into a microcomputer for processing. The device improves the concentration of the sample to be measured, has a measuring system with simple structure, has strong applicability, is convenient for later maintenance, and has low cost.

Description

The scattering particles by using dynamic polarized light measurement mechanism

Technical field

The utility model relates to a kind of nano particle diameter measurement mechanism, particularly a kind of device and method of directly measuring nano particle diameter under middle and high concentration.

Background technology

Dynamic light scattering (Dynamic Light Scattering, DLS) technology is to survey the important means of particle movement character, it is mainly used is the translation coefficient of diffusion that can measure in the solution big molecule or particle rapidly and accurately, thereby learns its size or hydrodynamic radius.The DLS technology has been widely used in the nano particles measurement in fields such as medicine, space flight, environment, chemical industry at present, and becomes the standard approach that ultra-fine grain characterizes in the lean solution.

But because the restriction of design concept, present DLS method only is applicable to the measurement in the lean solution scope, depends on the sampling dilution when measuring the middle and high concentration particle, to avoid multiple scattering effect between particle more.But this also may cause sample to form and change, and signal to noise ratio (S/N ratio) reduces, and is subject to the interference problems such as (as dusts, light) of external environment factor, has limited it further applying aspect the online in real time measurement.Thereby the research in this field in recent years mainly concentrates on: how to solve the difficult problem that the dynamic light scattering technology can't directly be measured grain diameter under the middle and high concentration, the most representative in the present method have simple crosscorrelation spectroscopic methodology and a dilatation wave spectrometry.But the former can only use it owing to too high to the accuracy requirement of device under laboratory condition; And the latter's algorithm is also too complicated, and only is applicable to the grain graininess measurement of ultrahigh concentration solution, therefore still is in the experimental study stage.In addition, also have additive method as: the scattering spot is analyzed, delustring pulsation method, ultrasonic attenuation method, and low-coherence measuring method etc., but also has indivedual technological difficulties on specific implementation, and cost is relatively also higher.

Summary of the invention

The utility model is the problem that has difficulties at existing measurement middle and high concentration particle, a kind of scattering particles by using dynamic polarized light measurement mechanism has been proposed, being used to solve the measurement volumes percent concentration is 0.1%～10%, and particle diameter is the technical matters of the grain diameter between 10～1000nm.

The technical solution of the utility model is: a kind of scattering particles by using dynamic polarized light measurement mechanism, comprise that sample cell also comprises laser instrument, the polarizer, / 2nd wave plates, lens, aperture diaphragm, analyzer, photomultiplier, digital correlator, microcomputer, the laser that laser instrument is launched enters the polarizer successively, / 2nd wave plates, the input path that lens are formed, on the particulate samples of rayed in sample cell by lens focus output, the scattered light perpendicular to incident laser direction that is produced by the sample particle of laser beam irradiation enters aperture diaphragm successively, analyzer, aperture diaphragm is formed receiving light path, enter photomultiplier at last and convert light signal to electric signal output and enter digital correlator and count, final data is sent in the microcomputer and is handled.

Utilizing above-mentioned scattering particles by using dynamic polarized light measurement mechanism to carry out the particle sizing method comprises the steps:

1) with laser instrument as light source, by the polarizer and 1/2nd wave plates, by lens focus in the sample cell that fills particle; 2) use photomultiplier as the scattering angle continuous coverage scattered light signals of photo-detector with 90 degree;

3) photodetector converts the light signal that records to the TTL pulse voltage signal, the light-intensity variation of the frequency change reflection scattered light of this pulse signal; Digital correlator calculates autocorrelation function according to pulse signal, and its expression formula is: in G (τ)=1+exp (the 2 Γ τ) formula, Γ is the Rayleigh live width, it and the translation diffusion coefficient D of describing Brownian movement intensity _TAnd Scattering of Vector q has following relational expression:

Γ=D _Tq ²

K wherein _BBe the Boltzman constant; T is an absolute temperature; η is a solution viscosity; D is a particle diameter, calculates autocorrelation function and sends into microcomputer;

4) autocorrelation function that calculates according to step of microcomputer is tried to achieve particle grain size.

The beneficial effects of the utility model are: use the utility model scattering particles by using dynamic polarized light measurement mechanism, but improve the concentration of test sample product, and simple in measurement system structure, application is strong, and the convenient later maintenance cost is low.

Description of drawings

Fig. 1 is the utility model scattering particles by using dynamic polarized light measuring principle block diagram.

Embodiment

Scattering particles by using dynamic polarized light measuring principle block diagram as shown in Figure 1, middle and high concentration particle measurer based on the dynamic polarization light scattering of the present utility model comprises laser instrument 1, the polarizer 2, / 2nd wave plates 3, lens 4, sample cell 5, aperture diaphragm 6,8, analyzer 7, photomultiplier 9, digital correlator 10, microcomputer 11.

The light that laser instrument 1 is launched enters the input path of the polarizer 2,1/2nd wave plates 3, lens 4 compositions successively.Wherein the polarizer 2 is used to improve the degree of polarization of laser, is the altitude line polarized light to guarantee incident light./ 2nd wave plates 3 are used to change the polarization of incident light direction, and the polarization direction here is perpendicular to scattering surface (being surface level).Lens 4 are used for incident laser is focused in sample cell 5 sample solutions a bit.

Formed receiving light path through aperture diaphragm 6, analyzer 7, aperture diaphragm 8 successively by the scattered light that the particle in the sample cell 5 of laser beam irradiation produces perpendicular to incident laser direction.Receiving light path output light signal enters collection and the processing unit that photomultiplier 9, digital correlator 10 and microcomputer 11 are formed scattered signal.Photomultiplier 9 is installed on the light path of 90 degree scattering angle, makes scattered light successively by aperture diaphragm 6, analyzer 7, aperture diaphragm 8, laggardly goes into photoelectricity multiplier tube 9.Wherein aperture diaphragm 6 is used to limit the scatterer volume to improve scattered light intensity and to determine coherent area, and the polarization direction of analyzer 7 is used for filtering multiple scattering light for being parallel to the incident light polarization direction, and the bonding scattered light accounts for leading.Aperture diaphragm 7 is used to limit the photosensitive area of photodetector to guarantee that it is smaller or equal to coherent area.

Using concrete measuring process of the present utility model is:

1) with laser instrument 1 as light source, by the polarizer and 1/2nd wave plates, by convex lens focus in the sample cell that fills particle;

2) use photomultiplier as the scattering angle continuous coverage scattered light signals of photo-detector 9 with 90 degree;

3) photodetector 9 converts the light signal that records to the TTL pulse voltage signal, the light-intensity variation of the frequency change reflection scattered light of this pulse signal; Digital correlator 10 calculates autocorrelation function according to pulse signal, and its expression formula is: in G (τ)=1+exp (the 2 Γ τ) formula, Γ is the Rayleigh live width, it and the translation diffusion coefficient D of Brownian movement intensity is described _TAnd Scattering of Vector q has following relational expression:

Γ＝D _Tq ²

$D_T=\frac{k_{B}T}{3\mathrm{\π\ηd}}$

K wherein _BBe the Boltzman constant; T is an absolute temperature; η is a solution viscosity; D is a particle diameter.Calculate autocorrelation function and send into computing machine 15;

4) microcomputer 11 is tried to achieve particle grain size according to the autocorrelation function that is calculated.

Example: adopt the resulting light intensity autocorrelator trace of digital correlator computing, its exponential damping law is: ln[G (τ)]=-1693 τ, pulse signal according to 14 pairs of photomultiplier outputs of digital correlator by expression formula is: G (τ)=1+exp (2 Γ τ), the live width that can obtain decaying is: Γ=846s ^-1

The He-Ne Lasers wavelength that test is adopted is λ ₀=632.8nm, the refractive index of water is m=1.33, scattering angle is 180 degree, according to the computing formula of Scattering of Vector q $q=\frac{4\mathrm{\πm}}{{\mathrm{\λ}}_0}\sin \left(\frac{\mathrm{\θ}}{2}\right),$ Can obtain Scattering of Vector q=2.64 * 10 ⁵Cm ^-1

Translation diffusion coefficient D according to decay live width Γ and description Brownian movement intensity _TAnd the relational expression of Scattering of Vector q: Γ=D _Tq ², can be in the hope of the translation diffusion coefficient D _TFor: 3.2 * 10 ^-8Cm ²S ^-1

Laboratory temperature is 25 ℃, and the viscosity coefficient η of water is 0.00943dynscm ^-2, according to Stokes-Einste in formula $D_T=\frac{k_{B}T}{3\mathrm{\π\ηd}},$ Obtain grain diameter d=145nm.

Claims (1)

1. scattering particles by using dynamic polarized light measurement mechanism, comprise sample cell (5), it is characterized in that, also comprise laser instrument (1), the polarizer (2), / 2nd wave plates (3), lens (4), aperture diaphragm (6,8), analyzer (7), photomultiplier (9), digital correlator (10), microcomputer (11), the laser that laser instrument (1) is launched enters the polarizer (2) successively, / 2nd wave plates (3), the input path that lens (4) are formed, focus on by lens (4) on the particulate samples of rayed in sample cell (5) of output, the scattered light perpendicular to incident laser direction that is produced by the sample particle of laser beam irradiation enters aperture diaphragm (6) successively, analyzer (7), aperture diaphragm (8) is formed receiving light path, enter photomultiplier (9) at last and convert light signal to electric signal output and enter digital correlator (10) and count, final data is sent in the microcomputer (11) and is handled.