JPH0786454B2 - Scattered light detector of particle size distribution measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention irradiates a particle group dispersed in a medium with light, detects scattered light (diffracted light) from the particle group, and detects the particle group. The present invention relates to a scattered light detector suitable for an apparatus for measuring particle size distribution.

(Prior Art) A light scattering method is often used for measuring the particle size distribution. In the light scattering method, the particle group to be measured is irradiated with monochromatic light (laser light),
The intensity of scattered light from the particles was measured for several scattering angles, and the measured values were used for statistics by the Fraunhofer diffraction method (coarse particles with an average particle size of several μm to several tens of μm) or the Mie scattering method (fine particles). The particle size distribution is obtained by performing a mathematical calculation process.

As a detector for measuring the intensity of this scattered light at several scattering angles, there is a ring detector in which a plurality of light receiving elements such as photodiodes are combined in a ring shape (JP-A-62-100637). This ring detector has a feature that the angular distribution of scattered light intensity can be instantaneously detected with high sensitivity and high accuracy.

(Problems to be solved by the invention) However, in the ring detector, each photodetector is arranged with an appropriate gap (insensitive body) due to the problem of crosstalk. On the other hand, if the width of the photodetector is made extremely small, the sensitivity decreases. In addition, since the lead wires cannot be attached, the number of ring-shaped light receiving elements that can be arranged is necessarily limited, especially in the central portion. This causes a decrease in detection accuracy and sensitivity in the central portion, and causes a measurement error in the measurement of the particle size distribution when the particle size is relatively large. This is because the angle of the diffracted light from the particles is related to the particle diameter, and the larger the particle diameter, the smaller the diffraction angle.

(Means for Solving Problems) The present invention has been improved in order to solve the above problems, in which a ring detector is divided into at least two,
It is a scattered light detector of a particle size distribution measuring device in which the gaps on the other side are shifted and combined so that the light receiving elements on the one side cover each other.

(Operation) According to the scattered light detector of the particle size distribution measuring device of the present invention,
Since the number of light receiving elements arranged at each angle is substantially increased, the intensity of scattered light scattered from each angle direction can be detected with high accuracy.

(Example) Hereinafter, the scattered light detector of the particle size distribution measuring apparatus of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows a basic configuration of a scattered light detector of a particle size distribution measuring device of the present invention, in which a ring detector 5 has arc-shaped photodiodes P ₁ to P ₁ ... having different curvatures on the same wafer.
A plurality of Pn are arranged concentrically with gaps G _{1 to} Gn having an appropriate width. These are divided and each gap G on the other side (usually several tens of μm) and each photodiode P on the one side (usually Slide several tens of μm) so that they overlap. By doing so, the light scattered in each gap G on the other side is also detected by each photodiode P on the one side,
The number of measurement points will be doubled.

FIG. 2 shows the configuration of an embodiment in which the scattered light detector of the particle size distribution measuring device of the present invention is applied to a particle size distribution measuring device utilizing laser light diffraction. The output beam from the laser light source 1 is a collimator 2 The flow cell 3 is irradiated with light. In the flow cell 3, particles are present in a state of being dispersed and dispersed in the diluting solution, and the irradiated laser light is diffracted at an angle according to the size of each particle. This diffracted light forms a diffracted image on the ring detector 5 placed at the focal position of the lens 4 by the condenser lens 4.

The output from each photodiode P of the ring detector 5 is led via a multiplexer 6 to an amplifier 7 ... 7 provided corresponding to each photodiode, and an A-D converter 8
It is digitized by and then incorporated into a microcomputer.

The microcomputer includes a CPU 9, ROM 10, RAM 11, etc., and is connected with a keyboard 12 and a CRT 13. CPU9
Can calculate the particle size distribution of the particle group in the flow cell 3 based on the intensity of light incident on each photodiode P of the ring detector 5 stored in the RAM 11 by a program written in the ROM 10 by a known method. Yes, the result is displayed on CRT12.

(Effect of the Invention) According to the scattered light detector of the particle size distribution measuring apparatus of the present invention,
Has a gap that can eliminate the effects of crosstalk,
Moreover, the number of light-receiving elements that can be arranged can be increased substantially without making the width of the light-receiving element extremely small enough to make it difficult to attach a lead wire. In the case of, it is possible to measure with high accuracy and high sensitivity.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic structure of a scattered light detector of a particle size distribution measuring device of the present invention, and FIG. 2 is a diagram showing a scattered light detector of the particle size distribution measuring device of the present invention applied to a laser light diffraction particle size distribution measuring device. It is a figure which shows an Example. In the figure, 1 is a laser light source, 3 is a flow cell, 5 is a ring detector, P is a photodiode, and G is a gap.

Claims (1)

[Claims] 1. A ring detector comprising a group of particles to be measured irradiated with monochromatic light, and a plurality of light receiving elements arranged concentrically with an appropriate gap for the intensity of scattered light from the particles at several scattering angles. In the scattered light detector of the particle size measuring device, the ring detector is divided into at least two parts, and the gaps on the other side and the light receiving elements on the one side are shifted so that they are overlapped with each other. A scattered light detector for a particle size analyzer.