JPH0237977B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a particle size measuring device for measuring the diameter of minute particles.

[Background technology of the invention and its problems]

BACKGROUND ART Devices that measure particle size using light scattering are conventionally known. This particle size measuring device is constructed, for example, as shown in FIG. That is, the laser beam emitted from the laser device 1 is passed through the collimator lens 3 to be converted into a parallel beam, and then irradiated onto the particle group 4 to be measured. Behind the particle group 4 to be measured, a plurality of optical fibers 5-1, 5-2, ... 5-n introduce light within a scattering angle at which the laser beam 2 is scattered by the particle group 4 to be measured. The ends 6 are positioned on a circle centered on a point P set within the particle group 4 to be measured, with the optical axis directed toward the point P, and an equal angular difference maintained between them, and the light of these optical fibers is guided. Photodetectors 8-1, 8-2, . . . detect the light guided by each optical fiber at the end 7.
...8-n is provided. Then, the outputs of the photodetectors 8-1, 8-2, . , the output of this conversion device 10 is displayed on a display 11. In other words, this device:
The scattered light intensity distribution I(θ) in the direction of the scattering angle (θ) of the light scattered by the particle group 4 to be measured is measured, and from this scattered light intensity distribution I(θ), using the relationship of equation (1), It is converted into a particle size distribution n(D).

I(θ)=∫i(D, θ)n(D)dD (1) Here, i(D, θ) is the scattered light by one particle calculated based on scattering theory.

However, in the device configured in this way, for example, the optical fibers 5-1, 5-2, . . .
...For example, when the light introduction ends 6 of 5-n are set at 1° intervals, the scattered light intensity distribution for each particle size becomes as shown in Figure 2. There was a problem in which the intensity distribution of scattered light due to the above particles could not be measured correctly. In addition, the particle size
In the case of particles with a diameter of 1 μm or less, the scattered light intensity distribution becomes as shown in Figure 3. Therefore, in order to reliably distinguish between the cases of particles with a diameter of 0.5 μm and those with a diameter of 1.0 μm, it is necessary to change the measurement scattering angle range. For example, it is necessary to set the angle widely, such as 0 to 30 degrees. Measuring scattered light over such a wide range and with high resolution inevitably requires a large number of optical fibers, and the processing system that processes the obtained optical signals is extremely large-scale. It was hot.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and its purpose is to provide a method for measuring a wide particle size range using only a few optical fibers, without increasing the size of the entire device. The objective is to provide a particle size measuring device that can

[Summary of the invention]

As shown in FIG. 4, in a small scattering angle range, the angle Δθ ₁ between the light introduction ends of the optical fiber Q is small, and in a large scattering angle range, the angles Δθ ₂ and Δθ ₃ between the light introduction ends are small. It is characterized in that the light introduction ends of each optical fiber Q are arranged in a distributed manner so as not to be large.

〔Effect of the invention〕

By setting the angle between the light introduction ends of each optical fiber as described above, it is possible to measure a wide range of particle sizes without increasing the number of optical fibers, that is, without increasing the size of the entire device. . That is, there is a relationship between the particle size and the period of change of the scattered light intensity distribution curve as shown in FIGS. 2 and 3. Therefore, for example, in the case of a particle size of 10 μm or more, it is only necessary to accurately measure the above-mentioned characteristic change period, and there is no need to measure the scattered light intensity distribution over a wide scattering angle. On the other hand, in the case of a particle size of 1.0 μm or less, it is sufficient if the slope of the entire scattered light intensity distribution can be measured over a range of scattering angles wider than the above-mentioned change period. Therefore, if the light introduction ends of each optical fiber are arranged in the above-mentioned relationship as in the present invention,
In particular, without increasing the number of optical fibers, it is possible to measure the particle size in a relatively large particle size range from the scattered light intensity distribution measured in a range where the angle between the light introduction ends is small, and the angle between the light introduction ends can be measured. The particle size in a small particle size range can be measured from the scattered light intensity distribution measured in a large range.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 5 shows a particle size measuring device according to an embodiment of the present invention, and the same parts as in FIG. 1 are designated by the same reference numerals. Therefore, the explanation of the overlapping parts will be omitted.

In this embodiment, optical fibers 5-1, 5-2,
...The optical axis of the light introduction end 6 of 5-n is set on a circle centered on the point P set in the particle group 4 to be measured.
They are arranged centripetally toward the following. In other words, when the scattering angle is in the range of 1 to 5.5°, there are 10 wires with an interval of Δθ ₁ = 0.5° between each other, and when the scattering angle is in the range of 6 to 20°, there are 10 wires with an interval of Δθ ₂ = 1° between each other. keep 15
In the scattering angle range of 20~30°, there is a difference between Δθ ₃ =
There are 5 pieces arranged at 2° intervals.

By arranging each optical fiber in this way,
When the scattered light of particles of φ1 μmφ and 0.5 μmφ is measured, the scattered light intensity distribution shown in FIG. 6 is measured. As can be seen from this figure, in the case of large particles (10 μmφ), the characteristic low-order diffracted light (0th and 1st order)
In the case of small particles (0.5, 1 μmφ), it is possible to measure the difference (inclination) in the scattered light intensity distribution between the two over a wide range. Therefore, since it is possible to distinguish and measure the characteristics of the scattered light intensity distribution over a wide particle size range, it is possible to measure particle sizes over a wide particle size range without increasing the size of the device. .

Note that the present invention is not limited to the embodiments described above. That is, in the embodiment described above,
An example of optical fiber arrangement is shown when measuring particles in the range of 0.5 to 50 μmφ, but when measuring particles with a diameter of 0.5 μm or less, a large scattering angle range,
For example, up to around 60°, for example, Δθ=
The light introduction ends of the optical fibers are arranged with an angular difference of 2° or 4°, and when measuring particles larger than 50 μmφ, a Δθ is set between them in a small scattering angle range, for example, in the range of 0 to 10°. If the light introduction ends of the optical fibers are arranged with an angular difference of 0.1 to 0.5 degrees, it is possible to measure particle sizes within these ranges. Also, logarithmic scales, e.g. 0.05°, 0.1°, 0.2°, 0.3°,
0.5°, 0.7°, 1.0°, 2.0°, 3.0°, 5.0°, 7.0°, 1
0.0゜,...
By arranging the light introduction end of the optical fiber at the position of ..., it may be possible to measure the diameter of particles over a wide range of particle diameters. Alternatively, a microlens may be arranged at the light introduction end of the optical fiber to guide only light parallel to the optical axis of the light introduction end into the optical fiber.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram of a typical particle size measuring device of this type, Figures 2 and 3 are diagrams for explaining the relationship between particle size and scattered light intensity distribution, and Figure 4 is a diagram for explaining the relationship between particle size and scattered light intensity distribution. A diagram for explaining the features of the inventive device, FIG. 5 is a schematic configuration diagram of a particle size measuring device according to an embodiment of the present invention, and FIG. 6 is a diagram showing the detection position and scattered light of the scattered light detection system in the same device. FIG. 3 is a diagram for explaining the relationship with intensity distribution. 1...Rege device, 2...Laser beam, 4...
...Particle group to be measured, 5-1, 5-2, ...5-n...
...Optical fiber, 6... Light introduction end, 8-1, 8-
2,...8-n...photodetector, 10...
Conversion device, 11...display.

Claims (1)

[Claims] 1. A light source device that irradiates a parallel laser beam toward a group of particles to be measured, and a scattering angle that is densely arranged in a small scattering angle range within the scattering angle of the laser beam scattered by the group of particles to be measured, and a large scattering angle range. There are a plurality of optical fibers whose light introduction ends are arranged in a roughly distributed manner, a plurality of photodetectors that respectively detect the light guided by these optical fibers, and the scattered light intensity distribution measured by these photodetectors is determined by the particle size. 1. A particle size measuring device comprising: a device for converting into a distribution;