CN103308432B - Continuous spectrum scattering type particle measurement method - Google Patents

Abstract

A continuous spectrum scattering particle measurement method. Solve the problem of weak signal received at large scattering angle and few sampling points in light scattering particle size and concentration measurement using a single wavelength or several wavelength light sources. The invention irradiates the light of continuous wavelength on the sample particles to generate scattering signals. Converge the scattered light within a certain range of scattering angles to one point, import it into a spectrometer for analysis, and obtain the distribution of scattering signals at different wavelengths. The distribution of these scattering signals is related to the particle size of the particles, and the particle size and concentration distribution of the particles are obtained through the data algorithm. The invention converges the light signals with a wide range of scattering angles to one point for reception, and improves the signal strength; adopts a continuous spectrum light source and a spectrometer to analyze the signals, increases the number of signal sampling points, and improves the measurement resolution and signal-to-noise ratio.

Description

A Continuous Spectrum Scattering Particle Measurement Method

technical field

The invention relates to a continuous spectrum scattering particle measurement method. Suitable for particle size and concentration measurement.

Background technique

With the acceleration of industrial processes, and in order to meet the requirements of environmental protection work, it is necessary to measure the particle samples in the industrial process and the particles in the environment. For example, particulate matter smaller than 2.5 microns is called PM2.5. They are more harmful to the human body and need to be measured intensively. Because the light scattering measurement method directly obtains the scattering signal of particles, its measurement period is short and its real-time performance is good, so it has been widely studied and applied. The incident light source generally adopted by the light scattering method is a light source of a single wavelength or several wavelengths, and there are some difficulties in the measurement process.

(1) The scattering signal of small particles is weak, and the converging optical path is generally used. There are few particles in the measurement area, and the representativeness is poor. At the same time, the total scattering signal received is small.

(2) There are few photodetectors and sampling points at the receiving end, resulting in poor stability and difficult calibration.

(3) In order to distinguish the characteristics of the particle scattering signal changing with the scattering angle, the receiving area of the photoelectric signal is required to be small, so the signal-to-noise ratio is poor.

Contents of the invention

The purpose of the present invention is to solve the problem of few data sampling points and weak signals affecting the measurement results in the existing light scattering method for measuring particle size and concentration, and to provide a particle measurement method based on continuous spectrum scattering.

The continuous spectrum scattering particle measurement method provided by the present invention (as shown in Figure 1), the specific steps are:

The light of continuous wavelength emitted by the light source (1) passes through the collimating lens (2) and irradiates the particle sample (3) to be measured, and is converged at one point by the focusing mirror after being scattered by the particles to be measured;

The receiving port (or fiber port) of the spectrometer (generally using optical fiber light guide) is placed at the converging point of the focusing mirror, and the scattered light signal of the particle to be measured is introduced into the spectrometer for analysis to obtain the intensity distribution of scattered light at different wavelengths. Through data reflection The particle size and concentration of the particles to be measured can be obtained by derivation.

The laser particle size analyzer involved in the method of the present invention consists of a continuous wavelength light source (1), a collimating lens (2), a focusing mirror (4) and a spectrometer (6). The particles to be measured are located between the collimating lens (2) and the focusing mirror (4). Converge the continuous wavelength particle scattering signal to a point of the focusing mirror, receive and analyze it by the spectrometer.

Advantage and positive effect of the present invention:

The continuous spectrum scattering type particle measurement method provided by the present invention converges the scattering signals of a wide range of scattering angles and then imports them into the spectrometer, the photoelectric signal receiving area is large, and the signal strength is improved; the light source of the continuous wavelength spectrum is used as the incident light, and the corresponding scattering signals Analyzed by a spectrometer, there are many wavelength sampling points and rich data information, which improves the reliability of the measurement results.

Description of drawings

Fig. 1 is a schematic diagram of the continuous spectrum scattering particle measurement method provided by the present invention.

Figure 2 is the calculated scattered light intensity spectrum.

Detailed ways

Example 1

Figure 1 is a schematic diagram of the continuous spectrum scattering particle measurement method provided by the present invention. The laser particle size analyzer involved in the method comprises: a continuous spectrum light source (1), a collimating lens (2), a focusing mirror (4) and a spectrometer (6).

The concrete steps of this method are:

The light of continuous wavelength emitted by the light source (1) becomes parallel light after being collimated by the collimator lens (2), and irradiates in the sample field of the particle sample (3) to be tested. After the particles are scattered, they are converged to one point by the focusing mirror (4);

Place the receiving port (or optical fiber (5) port) of the spectrometer (6) (generally using the optical fiber (5) to guide the light) at the converging point of the focusing mirror (4), after the particles scatter light of different wavelengths, the spectral distribution is different , after converging and analyzed by the spectrometer, the intensity distribution of the scattering spectrum at different wavelengths can be obtained. This distribution corresponds to the particle size and concentration information of the particles to be measured. Through data inversion, the particle size and concentration of the particles to be measured can be obtained.

Figure 2 is an example of the calculated scattered light intensity map. Among them, the particle size is 0.1-2.5μm, the light wavelength is 380-760nm, and the received scattering angle is 140-172 degrees. After the light intensity within the range of the received scattering angle is converged and normalized, the result shown in Figure 2 Light intensity spectrum. It can be seen from the data in Figure 2 that for different particle sizes, the scattered light intensity varies with wavelength in different trends, and the particle size and concentration can be obtained by solving the matrix equation.

Claims (3)

1. a continuous spectrum diffuse transmission type particle sizing method, is characterized in that the concrete steps of the method are:

The light being sent continuous wavelength by light source (1) is radiated in candidate particles sample (3) after collimation lens (2), converges at a bit after candidate particles scattering by focus lamp;

The receiving port of spectrometer or fiber port are placed in the convergent point position of focus lamp, the scattered light signal lead-in light spectrometer of candidate particles is analyzed, and obtains the intensity distributions of different wave length scattered light, obtains candidate particles granularity and concentration by data inversion.

2. method according to claim 1, is characterized in that described light source (1) adopts the light source of continuous wavelength.

3. method according to claim 1 and 2, is received by spectrometer after it is characterized in that the endocorpuscular continuous wavelength scattered signal of scattering angle that 140-172 spend is converged to any of focus lamp and analyzes.