JPS6258139A - Method and apparatus for measuring particle - Google Patents

Abstract

PURPOSE:To accurately perform measurement even when the density of particles is low, in a method for measuring particles to be measured by irradiating the particles to be measured with coherent beam, by forming luminous flux so as to run to the same direction in parallel in a measuring region. CONSTITUTION:Water containing fine particles 20 is made to flow in a flow cell 2 and laser beam is brought to be incident on the side surface 3 of the flow cell 2 from a laser beam source 1. The incident beam is refracted on the wall surface of the flow cell 2 and transmitted through water to be scattered by the fine particles 20 while the greater part of the remainder reaches the side wall 4 to be emitted to the outside while refracted. The beam emitted to the outside is successively reflected by a first reflective mirror 5, a second reflective mirror 6, a third reflective mirror 7 and a fourth reflective mirror 8 and formed into parallel beam which in turn again reaches the side surface 3. The beam transmits through water several times in the same direction. At this time, scattered light by the fine particles 20 is detected by a photomultiplier tube 12. Because the beam is allowed to run in parallel to the same direction to cover a measuring region, low density fine particles can be measured with high accuracy.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a particle measuring method and an apparatus thereof, and more particularly, to a particle measuring method and a device for measuring particles, and more particularly, to a method for measuring particles by irradiating the particles to be measured with a light beam from a coherent light source such as a laser light source. The present invention relates to a particle measurement method and apparatus for measuring particle characteristics such as particle size and number of particles by measuring scattered light.

[Prior Art] Conventionally, the scattered light flux from a laser light source has been measured based on the principle of the photon correlation method, and particle characteristics such as the particle diameter and number of particles have been measured. For example, when measuring impurities in pure water, the particle size of the particles being measured is small;
Moreover, it is difficult because the particles exist only sparsely. Conventionally, in order to increase the scattering intensity from fine particles, a method has been used in which the incident light beam is focused on a small area, a high-intensity 11111 constant area is provided, and the scattered light from particles passing through this area is received. . For example, such a method is used in ultrafine particle counters that detect impurities in pure water.

[Problems to be solved by the invention] As described above, since the conventional method targets a group of particles with a high particle number density, it is difficult to measure particles with f17 capability, which can sufficiently measure the properties of 81 groups of particles in a small All constant area. However, -1 For example, when measuring impurity fine particles in pure water, the fine particle density is in a thin state, and therefore it becomes necessary to increase the amount of purified water to be measured.

For this reason, in the past, the cross-sectional area of pure water passing through was several hundred times larger than the cross-sectional area of the measurement area, and the particles being measured were only a small fraction of the particles that actually passed through. There is a problem in that it is not possible to measure a sufficient number of particles to reflect the quality of the product itself. In particular, when measuring fine particles in pure water with a low particle a density and inspecting the quality of the pure water, it is desirable to be able to inspect all the fine particles in the pure water.

Therefore, the present invention has been made in view of these points, and provides a particle allll method and an apparatus therefor that can accurately measure the particle size and number of particles even if the particle number density is low. The purpose is to provide

[Means for Solving the Problems] In order to solve these problems, the present invention reflects the coherent light beam multiple times in the M1 constant region where the fl11 constant particle exists, so that the coherent light beam is reflected in the same direction in the measurement region. A configuration was adopted in which a running substantially parallel coherent light beam is formed and scattered light from the coherent light beam is determined one by one.

[Function] In such a configuration, the light beam from one coherent light source becomes several parallel coherent light beams with approximately the same intensity in the measurement area, and it is possible to cover a wide range of the measurement area with the coherent light beam, Accurate particle measurements are possible.

[Example] The present invention will be described in detail below according to embodiments shown in the drawings.

FIG. 1 shows a schematic configuration of a measuring device for measuring the characteristics of fine particles such as impurity particles in pure water. In the figure, the reference numeral 1 indicates a coherent light source, for example a laser light source, and this laser light source 1 emits a coherent laser beam 1a from its front surface. A light beam 1a emitted from this laser light source 1 passes through the air and enters a first side surface 3 of a glassy flow cell 2. As shown by arrow A, pure water flows into the flow cell 2 from the cloth and flows out to the lower part thereof. This pure water contains impurity fine particles 20 to be determined as Al11. The laser beam incident on the first side surface 3 of the flow cell 2 is refracted by the wall surface and transmitted into the pure water. If there are scattering particles, part of the laser beam transmitted through pure water is scattered, and most of the remaining light is transmitted to the second side facing the first side 3 of the flow cell.
It reaches side 4 of the wall, is bent and exits the flow cell. A first reflecting mirror 5 is disposed close to the second side surface 4 of the flow cell 2, and a fourth reflecting mirror 8 is disposed on the ml side surface 3 of the flow cell 2, that is, on the laser light source l side. The upper part of the fourth reflector 5.8 has second and first mirrors, respectively. Third reflecting mirrors 6, 7 are arranged.

The light flux incident on the first reflecting mirror 5 is reflected according to the reflectance of the mirror surface, is reflected by the second reflecting mirror 6 while propagating in the air, propagates outside the flow cell 2, and is further reflected by the third reflecting mirror 6. It is reflected by the reflecting mirror 7 and reaches the fourth reflecting mirror 8. These four reflecting mirrors are arranged so that the light beam reflected by the four surfaces is parallel to the initial incident light beam, and the light beam incident point array on each reflecting mirror is parallel to the first and second side surfaces of the flow cell. precisely adjusted and placed. Therefore, the light beam reflected by the four reflecting mirrors, rotated, and returned to the fourth reflecting mirror 8 is reflected at a slightly advanced position according to its optical path length, and crosses the cross section of the flow cell. A parallel beam group is formed. The light flux that is repeatedly reflected in this way is: 5
The light is captured by the optical trap 9 through the reflecting mirror 7 of No. 3, and is absorbed so as not to be emitted again.

The laser light scattered by the scattering particles floating in the pure water in the flow cell passes through the third side surface 10 of the flow cell and is directed to the photocathode 12 of the photomultiplier tube 12 by the light receiving lens 11.
The image is focused on a. At this time, the parallel light beams passing through the flow cell are all incident and propagating in the same direction, so the scattering angle of the light scattered in the axial direction of the receiving lens is equal for the scattering particles in all the light beams. This makes it possible to measure scattered light under the same conditions.

Also, the laser beam 1 that is multiple-reflected within the flow cell 2
Since a maintains a coherent state, the scattered light from particles in different light fluxes also becomes coherent and can interfere with each other, so the fluctuation of the scattered light depending on the Brownian motion of each particle is reflected in the photomultiplier tube. is detected by the photocathode 12a. As is well known, this fluctuation in light intensity is photoelectrically converted by the photomultiplier tube 12, processed as an electrical signal by the processing circuit 13, and inputted to the correlator 14 connected to the subsequent stage. The correlator 14 determines a correlation function between the fluctuation of the light intensity and the characteristics of the particles, and the microcomputer 15 calculates this into the diffusion coefficient and particle diameter of the particles.

FIG. 2 shows the specific configuration of the measuring section. In FIG.

The incident and exit surfaces of the laser beam are the narrow surfaces 3.4, and the wide surfaces 10 are the light-receiving surfaces. By using a cell with such a shape, the range in which the acceptance angle can be changed is expanded, and it is possible to receive forward, side scattered light 20 or back scattered light 21 depending on the characteristics of the scatterer particles and the measurement method. .

When receiving scattered light, the light scattered in the direction of the opposing surface 11 is reflected at the flow cell wall surface on the opposing surface side, that is, the interface between pure water and the flow cell, and the outer interface of the flow cell, and becomes noise, so this reflected light is suppressed as much as possible. There is a need. Therefore, in order to reduce the difference in refractive index on the outer surface of the flow cell that causes particularly strong reflected light, a medium having the same or almost the same refractive index as the material of the flow cell, that is, the index matching liquid 22, is applied to the outside of the opposing surface 11 of the flow cell. Deploy.

[Effects of the Invention] As explained above, according to the present invention, several nearly uniform coherent light beams running in the same direction are formed from a laser beam from one light source, and this covers the measurement area. This makes it possible to measure particle groups with high precision using the photon correlation method, making it possible to measure ultra-dense fine particles in a short time and to measure particle groups that reflect the statistics of the population of particle groups. You can get the excellent effect of being able to capture images.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram explaining the present invention in detail, :JSZ
The figure is a sectional view illustrating a more detailed configuration of the measuring section. 1... Laser light source 2... Flow cell 5.6,
7.8...Reflector

Claims (1)

[Scope of Claims] 1) A particle measurement method in which a particle to be measured is irradiated with a light beam from a coherent light source and scattered light from the particle is measured to measure the characteristics of the particle. By reflecting multiple times in the measurement area, a nearly parallel coherent light beam running in the same direction in the measurement area is formed.
A particle measurement method characterized by measuring scattered light from the coherent light beam. 2) The particle measuring method according to claim 1, characterized in that the parallel light beams are prevented from overlapping at least in the measurement area. 3) In a particle measuring device that measures the characteristics of the particles by irradiating the particles to be measured with a light beam from a coherent light source and measuring the scattered light from the particles, the first, second, third, and fourth reflecting means are provided. The light flux from the coherent light source is sequentially multiple-reflected a plurality of times between the first to fourth reflecting means, which are arranged around the measurement area, so that the light beam running approximately in the same direction between the first and second reflecting means is formed. A particle measuring device characterized by forming a parallel coherent light beam and measuring scattered light from the coherent light beam.