JPH0537238Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a sample cell of a particle size distribution measuring device using a laser diffraction method (light scattering method).

<Prior art> In a method of measuring the particle size distribution of particles in a sample suspension (or suspended liquid, hereinafter simply referred to as suspension) using Fraunhofer diffraction, it is generally known that Laser light is irradiated, and a lens receives the light that is diffracted according to the size of each particle in the liquid, forming a concentric diffraction image on the focal plane of this lens. Then, the particle size distribution of the particles present in the sample suspension is calculated from the measured value of the light intensity distribution of this diffraction image.

The sample suspension is usually housed in a container having an optical path length (inner width dimension in the optical path direction of the irradiated laser beam) of about 2 to 10 mm, and placed on the optical path of the laser beam.

In such a measurement method, when the sample suspension concentration is high, light scattered by one particle is further scattered by other particles, as shown in FIG. Multiple scattering increases and its intensity increases for light with large scattering angles. A larger scattering angle means that there are apparently more small particles, and the obtained particle size distribution measurement result deviates to a smaller particle size than the true particle size distribution, making accurate measurement impossible.

Therefore, in order to reduce errors caused by such multiple scattering, measurement has been conventionally carried out by reducing the concentration of the sample suspension.

<Problems that the invention aims to solve> Dilution of sample suspensions causes sampling errors, and some samples are stable only within a certain concentration range, and dilution may change the particle size itself. There are some things that can happen. Furthermore, the laser diffraction method has the advantage of being able to perform measurements in a shorter time than other measurement methods, but this also makes the dilution operation extremely troublesome for the measurer.

In view of these points, the present applicant has already developed a highly concentrated sample by storing a sample suspension in a microscopic gap between two transparent flat plates and irradiating the sample with laser light. We have proposed a method that can accurately measure particle size distribution without diluting a suspension and without causing multiple scattering (Japanese Patent Application No. 104977/1982).

This invention was made to improve the workability when putting the above-mentioned proposal into practical use, and it is possible to measure the particle size distribution of a highly concentrated sample suspension using extremely simple operations. It is intended to provide cells.

<Means for solving the problem> In order to achieve the above object, the sample cell in the particle size distribution measuring device using laser light diffraction of the present invention is as shown in FIGS. 1 to 4 corresponding to the embodiment. As shown in FIG.
It is characterized by having a transparent spacer 2 having a thickness t that is shorter by a predetermined minute dimension.

<Operation> After injecting an appropriate amount of the sample suspension into the container 1 with the spacer 2 removed, by inserting the spacer 2 into the container 1, the sample suspension is poured into the inner width of the container 1. and the difference between the thickness t of spacer 2 (lt)
It easily penetrates into the gap having a very small thickness in the direction of the optical path A. When the thickness of the suspension in the direction of the optical path A of the laser beam becomes smaller, the number of particles present in the direction of the optical path A decreases even in a highly concentrated sample, and the probability of occurrence of multiple scattering decreases.

<Example> An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of the embodiment of the present invention, with the spacer 2 removed from the container 1, FIG. 2 is a central vertical sectional view showing the spacer 2 inserted into the container 1, and FIG. 3 is a perspective view of the embodiment of the present invention. 1 is a cross-sectional view with a horizontal plane including an optical path A of a laser beam to be irradiated as a cutting surface. Also,
FIG. 4 is a plan view of the spacer 2.

Both the container 1 and the spacer 2 are made of transparent material such as pyrex.

The container 1 includes a measurement chamber 11 having a predetermined uniform internal width l in the direction of the optical path A of the laser beam to be irradiated.
and a liquid reservoir section 12 located above the measurement chamber section 11 and having an internal width dimension larger than the dimension l.

The spacer 2 is provided with fitting parts 21, 21 at both left and right ends thereof, each having a thickness l' with a small fitting clearance relative to the internal width l of the measurement chamber 11 of the container 1. It can be inserted and removed freely. The intermediate portion 22 that connects the fitting portions 21 and 21 has a minute dimension, for example, several tens to several hundred μm, than the internal width l of the measurement chamber portion 11 of the container 1, on the optical path A of the laser beam to be irradiated. A protrusion 23 is provided with a uniform thickness t that is small by -t)/2 parallel microgaps are formed at two locations.

Next, we will discuss its effects along with how to use it.

First, with the spacer 2 removed, a sample suspension is injected into the container 1 until the liquid level reaches the position shown in FIG. 2, for example, x. Next, spacer 2 is inserted. As a result, the surface of the sample suspension rises and reaches the liquid reservoir 12, and also reliably enters the two gaps between the measurement chamber 11 and the protrusion 23.

In this state, as shown in Fig. 5, inside the optical system,
The protrusion 23 is arranged so as to be located on the optical path A of the laser beam. In the figure, 3 is a condenser lens, and 4 is a detector. Further, W indicates a sample suspension. The laser beam is diffracted by the particles in the two gaps, and a diffraction image is formed on the detector 4 by the condenser lens 3. From the light intensity distribution of this diffraction image, the particle size distribution of the particles in the sample suspension can be determined by a known algorithm.

Here, the thickness of the suspension in the direction of the optical path A of the laser beam, that is, the optical path length in the suspension is the sum of the widths of the two gaps, that is, (lt).
By preparing multiple types of spacers with different thicknesses t, the optical path length (l-
t) can be changed arbitrarily, depending on the concentration of the sample suspension to be measured, and by using a spacer with a larger thickness t as the concentration increases, even high concentration suspensions can be measured without dilution. Accurate particle size distribution measurement that is not affected by multiple scattering becomes possible.

Note that the shapes of the container 1 and the spacer 2 are not limited to the above embodiments, and it is sufficient that the spacer 2 is inserted into the container 1 to form a gap with a minute thickness that makes it difficult for multiple scattering to occur. For example, the shape may be as shown in the cross-sectional view in FIG. In this example, a protrusion 623 is formed on one side of the spacer 62, and elastic bodies 65, 65 such as compression springs are interposed between one inner surface of the container 61 and the spacer 62, and the protrusion 623 is formed on the other side of the spacer 62. By bringing the protruding portion 623 into close contact with the other inner surface of the container 61, a gap is formed between the protruding portion 623 and one inner surface of the container 61. Optically, this example is more convenient.

<Effects of the invention> As explained above, according to the invention, by simply injecting the sample suspension into a container and inserting a spacer, it is possible to form a suspension layer of minute thickness in the optical path direction of the laser beam. This enables accurate particle size distribution measurements with extremely simple operations without diluting highly concentrated sample suspensions. Moreover, by simply preparing a plurality of types of spacers with different thicknesses t, the thickness of the suspension layer can be easily changed as necessary even if the concentration changes.

[Brief explanation of the drawing]

1 to 4 are structural explanatory diagrams of an embodiment of the present invention. FIG. 1 is a perspective view showing the spacer 2 removed from the container 1, and FIG. 2 is a perspective view showing the spacer 2 inside the container 1.
FIG. 3 is a sectional view taken along a horizontal plane including the laser beam path A, and FIG. 4 is a plan view of the spacer 2. FIG. 5 is a diagram for explaining the use of an embodiment of the present invention, and FIG. 6 is a cross-sectional view of another embodiment of the present invention. FIG. 7 is an explanatory diagram of multiple scattering. DESCRIPTION OF SYMBOLS 1... Container, 11... Measurement chamber part, 12... Liquid reservoir part, 2... Spacer, 21... Fitting part, 2
2... Middle part, 23... Projection part, 3... Condensing lens, 4... Detector, A... Laser beam optical path.

Claims (1)

[Scope of utility model registration request] The sample liquid is irradiated with laser light to a sample liquid in which particles are suspended or suspended in a medium, and the sample liquid is measured in a device that measures the particle size distribution of the particle groups in the sample liquid based on the intensity distribution of the diffracted light. A cell for accommodating and disposing on the optical path of a laser beam, which includes a transparent container having a predetermined inner width dimension in the optical path direction of the laser beam to be irradiated, and a cell that is removably inserted into the container. . A sample cell in a particle size distribution measuring device using laser light diffraction, comprising a transparent spacer having a thickness shorter by a predetermined minute dimension than the inner width dimension.