JPH08178830A - Detector - Google Patents

Abstract

PURPOSE: To determine the size of a particle using a simple optical detection means by determining the ratio of intensity of light scattering in a plurality of different directions. CONSTITUTION: A semiconductor laser (light source) 2 emits laser light (irradiation light) for irradiating a solution or a gas. A first photodetector element 3 comprises photodiodes, or the like, arranged on a line connecting the emitting part of the laser 2 and a quartz container 1. A second photodetector element 4 comprises photodiodes, or the like, receiving the light backscattering at an angle θY. arranged at the angle θY with respect to the central optical axis of laser light emitted from the laser 2 on the same side as the laser 2 with respect to the container 1. An arithmetic unit calculates the ratio of intensity of signals outputted from the elements 3, 4 and determines the particle size based on the ratio of intensity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection device capable of detecting the size of particles by using light.

[0002]

2. Description of the Related Art Conventionally, as a method for identifying the size of particles, Japanese Patent Laid-Open No. 62-100637 (G01N 15/0) has been used.
2) and JP-A-2-203246 (G01N 15/0)
2) discloses a method for measuring the particle size distribution of particle groups using Fraunhofer diffraction.

[0003]

However, in the method described in the above publication, it is necessary to use a ring detector arranged concentrically or a fan-shaped detector composed of a plurality of photodiodes having a large light receiving area in the radial direction.
The device could be expensive.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a detection device capable of discriminating the size of particles by using a simple light detecting means.

[0005]

The detection device of the present invention comprises a light source means and a scattered light generated when the irradiation light output from the light source means is applied to the irradiation object to the irradiation object. Light detecting means for detecting light intensities in a plurality of directions having angles different from each other with respect to the incident direction, and the irradiation target is determined based on a ratio of light intensities in the plurality of directions detected by the light detecting means. It is characterized by detecting the size of an object.

In particular, the light detecting means is characterized by comprising a light detecting element for forward scattered light and a light detecting element for back scattered light.

In particular, the photodetector element for the forward scattered light is
It is characterized in that the forward scattered light is received through the slit.

[0008]

The scattered light generated by irradiating the irradiation object with the irradiation light is concentrated on the front side as the size of the irradiation object is larger, and so-called forward scattering becomes stronger. On the contrary, as the size of the irradiation object is smaller, the forward scattered light spreads (the scattering angle of the forward scattered light becomes larger), and the so-called backscattering also spreads toward the rear side.

According to the present invention, the size of the object to be irradiated is detected from the light intensity ratio (that is, the identification of the intensity distribution of the scattered light) of the scattered light in a plurality of different directions based on the above-mentioned principle. The light detecting means is unnecessary, and the device can be provided at a low cost.

In particular, when the light detecting means is composed of a light detecting element for forward scattered light and a light detecting element for back scattered light, the light intensity ratio of the forward scattered light and the back scattered light is the object to be irradiated. Since it remarkably changes depending on the size, the size of the irradiation target can be accurately detected from the light intensity ratio of the forward scattered light and the back scattered light.

Particularly, when the photodetection element for the forward scattered light receives the forward scattered light through the slit, it is possible to prevent the irradiation light from directly entering the photodetection element for the forward scattered light. The scattered light having a predetermined scattering angle can be made incident on the light detecting element for the forward scattered light. As a result, the sensitivity of detecting the size of the object to be irradiated is increased.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle of the particle detecting device of the present invention will be described with reference to the drawings. FIG. 1 is an intensity distribution diagram of scattered light for explaining the principle of the present invention.

In FIG. 1, (a) to (f) are 5,
The intensity distribution of scattered light when a laser beam is irradiated to particles having particle diameters of 1, 0.5, 0.3, 0.2, and 0.1 μm is shown.

From this figure, as the size of the scattered light is larger, the scattered light is concentrated on the front side, so-called forward scattering becomes stronger, and conversely, as the size of the particle is smaller, the forward scattered light is larger. It can be seen that as it spreads, so-called backscattering spreads to the rear side as well. Therefore, from this, it can be understood that the particle size can be detected from the light intensity ratios of the scattered light in a plurality of different directions.

The present invention uses this principle to detect the size of an object to be irradiated, and FIG. 2 is a schematic configuration diagram of a detection apparatus according to an embodiment of the present invention.

In FIG. 2, 1 is a quartz container for containing a predetermined solution or gas, and 2 is a wavelength 6 for irradiating the solution or gas.
A semiconductor laser (light source) that outputs a laser beam (irradiation light) of 80 nm, 3 is an emission part of the semiconductor laser 2 and the quartz container 1.
The first photodetector element 4 composed of a photodiode or the like arranged on a straight line formed by and is on the same side as the semiconductor laser 2 with respect to the container 1 and the central optical axis of the laser light output by the semiconductor laser 2. The second photodetector element 5 is a photodiode or the like which is arranged at an angle θ _{Y with} respect to Z and receives the backscattering of the spread angle θ _Y. The laser light output from the semiconductor laser 2 is the first light. A width 50 for preventing direct incidence on the detection element 3 and for transmitting forward scattering with a divergence angle θ _X.
A slit having a substantially circular opening 5a having a diameter of 0 μm and a diameter of 6.5 mm, and 6 is arranged between the first photodetector 3 and the slit 5 and is a condenser for condensing light to the first photodetector 3. It is a lens.

In this example, the semiconductor laser 2 and the container 1 are
Is 100 mm, the distance between the container 1 and the slit 5 is 24 mm, and the distance between the slit 5 and the condenser lens 6 is 20 mm.
mm, the distance between the condenser lens 6 and the first photo-detecting element 3 is 56
mm, the distance between the center of the container 1 and the second photodetector 4 is 10
The setting was 0 mm, θ _X = 7.7 degrees, and θ _Y = 170 degrees.

In such a device, the intensity ratio of the signal intensities obtained by the first and second photo-detecting elements 3 and 4 is calculated by an arithmetic unit (not shown), and the particle size is calculated from the intensity ratio according to the above-mentioned principle. Obtainable.

For example, particles of diatomaceous earth and liquid detergent in a mixed solution of diatomaceous earth, liquid detergent and water shown in Table 1 (sample 1), a mixed solution of gelatin (protein), liquid detergent and water (sample) The micelle-like particles consisting of gelatin and the liquid detergent in 2) were examined. These samples 1
The average particle diameters in Sample 2 and Sample 2 were 6 to 7 μm and 0.7 to 0.8 μm, respectively, as measured by a laser diffraction type particle size distribution meter and a dynamic scattering type particle size distribution meter.

[0020]

[Table 1]

Table 2 shows the signals obtained by the first and second photodetector elements 3 and 4 in the above apparatus and their intensity ratios.

[0022]

[Table 2]

From the strength ratio shown in Table 2, it is possible to distinguish between particles composed of diatomaceous earth and a liquid detergent and particles, which are particles in a micellar state where it is difficult to distinguish between the particles and particles composed of a liquid detergent. I understand.

Further, the above devices are at least 2 to each other.
It was also confirmed that particles can be reliably discriminated if there is a difference in size of about 3 times.

Therefore, the device of the present invention can be used as a pollen sensor for detecting pollen having a size different from that of dust in the air, smoke of cigarettes, etc., and a water quality inspection device for detecting suspended matter in water.

In the above description, the wavelength 68 is used as the light source means.
Although the semiconductor laser of 0 nm is used, it is of course applicable to other wavelengths, and other light sources such as light emitting diodes may be used.

Further, in the above description, the forward scattering and the back scattering are detected. However, one of the forward scattering and the back scattering which is different in at least two directions (divergence angle) is detected, and the particle size is determined by using the intensity ratio. You can also ask.

[0028]

According to the present invention, based on the above principle, the light intensity ratios of scattered light in a plurality of different directions are obtained,
Since the size of the object to be irradiated can be detected from this intensity ratio, a complicated photo-detecting means is unnecessary and the apparatus can be provided at low cost.

In particular, when the light detecting means is composed of a light detecting element for the forward scattered light and a light detecting element for the back scattered light, the light intensity ratio of the forward scattered light and the back scattered light is the object to be irradiated. The size of the object to be irradiated can be detected more accurately based on the light intensity ratio of the forward scattered light and the back scattered light, because the size significantly changes depending on the size.

Particularly, when the photodetection element for the forward scattered light receives the forward scattered light through the slit, it is possible to prevent the irradiation light from directly entering the photodetection element for the forward scattered light. The scattered light having a predetermined scattering angle can be made incident on the light detecting element for the forward scattered light. As a result, the sensitivity of detecting the size of the object to be irradiated is increased.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating the principle of the present invention.

FIG. 2 is a schematic schematic configuration diagram showing an example of a detection device according to the present invention.

[Explanation of symbols]

 2 Semiconductor Laser (Light Source Means) 3 First Photo Detector (Photo Detector) 4 Second Photo Detector (Photo Detector) 5 Slit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenichi Shibata 2-5-5 Keihan Hondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (3)

[Claims] 1. A plurality of light source means and a plurality of different angles formed between the irradiation light output from the light source means and the incident direction of the irradiation light of the irradiation light on the irradiation object. A light detecting unit for detecting the light intensity in each direction, and detecting the size of the irradiation target from the ratio of the light intensities in the plurality of directions detected by the light detecting unit. Detector. 2. The detection device according to claim 1, wherein the light detecting means includes a light detecting element for forward scattered light and a light detecting element for back scattered light. 3. The detection device according to claim 2, wherein the photodetector element for the forward scattered light receives the forward scattered light through a slit.