JPH0656358B2 - Light scattering type particle measuring device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particle measuring device for examining physical properties of contained particles such as size and concentration of particles in a fluid by utilizing light scattering.

(Technical Background of the Invention) FIG. 4 is a system diagram of a conventional apparatus, in which (a) is a side scatter measurement method and (b) is a forward scatter measurement method.
6-10579 and JP-A-59-160744.

In the figure, 1 is a light irradiation device that forms coherent measurement light such as laser light, 2 is a condenser lens, and 3 is a flow path section having a portion through which a fluid of a constant velocity passes and which is transparent to the measurement light. Reference numeral 4 is a condenser lens, 5 is a photoelectric converter which makes measurement light incident, and 9 is a direct light removing means.

In either method, scattered light is still observed, but in the side-scattering measurement method (a), the observation direction B is approximately 90 degrees with respect to the irradiation direction A of the measurement light, and the forward-scattering measurement method is used.
In (b), it is 180 degrees.

Regardless of the method, in consideration of light transmission, the flow path portion is entirely made of a transparent material such as glass, or at least two places of a light incident portion and a light emitting portion are made of a transparent material.
Therefore, the light from the light irradiation device 1 inevitably generates reflected light and scattered light based on the transparent body itself.

A particular problem is that when dirt adheres to the wall of a transparent body such as glass, which is the light transmitting part, scattered light is generated by this dirt, and this scattered light becomes stray light that cannot be separated from scattered light by the fine particles to be measured. As a result, the measurement ability was deteriorated.

That is, in the fine particle measuring apparatus of the side scatter measurement method of FIG. 4 (a) and the forward scatter measurement method of FIG. 4 (b), a fluid containing a very small number of fine particles, for example, an ultra pure material used in a semiconductor manufacturing process. When water is caused to flow through the flow path part 3 to inspect the number of fine particles per unit flow rate, not only the fine particles flowing in the central part of the flow path but also the flow path can be obtained by irradiating the entire fluid flowing through the flow path with measurement light. It is necessary to introduce the scattered light from the fine particles flowing near the inner wall surface of the road portion 3 into the measurement system so that it can be separated from the scattered light generated from the inner wall surface.

By the way, in the case of such a fluid containing very few fine particles,
If you can not count the number of particles flowing in the flow channel one by one,
Since the measurement error becomes large, it cannot be practically used as an inspection device.

(Object of the Invention) The present invention has been made based on the above circumstances.
Provided is a light-scattering type fine particle measuring device capable of measuring fine particles with high accuracy by separating and observing only scattered light of fine particles to be measured from scattered light generated on the inner wall surface of a flow channel. The purpose is to

(Summary of the Invention) In order to achieve this object, in the present invention, the measurement light is incident on the flow path portion from an oblique direction so that the light transmission part of the flow path portion and the flow path are obliquely transmitted, thereby performing measurement. In the system, the scattered light generated from the surface of the light transmitting portion in the oblique optical path is formed as an image separated from the image of the scattered light generated from the fine particles flowing in the flow path.

Embodiments of the Invention Embodiments of the present invention will be described below with reference to the accompanying drawings.
In addition, in each figure, the same reference numerals indicate similar objects.

FIG. 1 is a systematic diagram of a light scattering type fine particle measuring apparatus according to an embodiment of the present invention.

In the figure, each component 1-5 is the same as that of FIG. However, in the flow path portion 3, the fluid flows in the direction of the arrow FL. In addition, a slit 1 is provided in front of the photoelectric converter 5.
0 is set.

The flow path part 3 is, for example, a rectangular parallelepiped as shown in FIG.
It has six sides 31-36.

The side surfaces 31 and 32 are made of, for example, a glass plate or the like, and form an entrance surface and an exit surface of the measurement light, respectively. Therefore, generally speaking, the surfaces 31 and 32 are transparent to the measurement light and are flat over the entire surface. Of course, only the portion through which the measurement light passes may be light-transmissive, and only that portion may be the flat region.

The side surfaces 33, 34 are frame means for holding the side surfaces 31, 32 at a constant interval, and may be made of a light-transmissive material as in the case of the side surfaces 31, 32, or may not be so.

The side surfaces 35 and 36 are respectively upstream and downstream surfaces of the fluid flow FL, and are connected to pipes, nozzles, cocks and the like (not shown) for injecting or outflowing the fluid.

The measurement light 11 for measurement is incident on the first side surface 31 of the flow passage portion 3 which is transparent and has a flat area.
In the light irradiation system including the laser light source 1 and the like, the optical axis of the measurement light 11 is an angle with respect to an imaginary perpendicular line 12 perpendicular to the flat area of the side surface 31, as shown in FIGS. 1 and 3 (a). Arrange so that α (≠ 0) is formed. As will be apparent from the following description, the angle α is arbitrary so that the optical path of the measurement light does not coincide with the observation axis and the scattered light / reflected light of each of the boundary surfaces in the optical path are separated from each other. Can be selected. The measuring light 11 has a sufficiently small thickness in the flow direction of the fluid, and has a lateral width larger than the lateral width of the flow path and smaller than the lateral width of the incident surface 31, and thus is converged into a flat shape as a whole. The measuring light 11 intersects the fluid flowing in the flow path as a whole in an optical path that obliquely passes through the flow path portion 3. Thus, no matter where one particle passes through any part of the flow path (that is, wherever it passes through the center part of the flow path or any part close to the four inner surfaces of the flow path), one particle crosses the measurement light 11. In addition, scattered light is generated by the fine particles.

Further, in the detection measurement system including the lens 4, the slit 10 and the photoelectric converter 5, the observation direction 14 (same as the axis of the optical system of this system, hereinafter referred to as the observation axis) has the light transmission of the flow path part 3. Of the measuring light emitted from the second side surface 32 which has a flat characteristic and forms a flat region, and is arranged different from the optical axis direction 13 of the measuring light. That is, the outgoing optical axis 13 and the observation axis 14 form a constant angle β (≠ 0), and the side surface
The 32 flat areas and the observation axis 14 form an angle γ. Here, in order to eliminate the influence of the aberration of the scattered light by the side surface 32, the angle γ is
It is desirable to be near 90 degrees. The side surface 32 of FIG.
The imaginary perpendicular line 19 and the outgoing light 13 form an angle Θ.

As shown in FIG. 3 (c), the slit 10 has a rectangular opening 10A in the center thereof so that only the observed scattered light passes through.

In the photoelectric converter 5, one particle in the fluid is the measurement light 1
Each time it crosses 1, it is sensitive to scattered light and forms an electrical signal OP.

For example, by counting the number of times this electric signal OP is generated,
The concentration of particles in the fluid can be measured. Further, instead of the photoelectric converter 5, a microscope or an image sensor may be arranged to observe the shape of particles.

Next, the operation of this embodiment will be described.

When the light irradiation device 1 emits the measurement light 11, the light 11 is emitted from the lens 2
And is obliquely incident on the side surface 31 of the flow path portion 3 at an angle α,
Emitted from side 32 at angle Θ.

At this time, as shown in FIG. 3 (a), in the optical path of the measurement light 11, in addition to the scattered light by the fine particles 39 in the fluid,
Scattered light is generated by contamination of the boundary portions 31a, 31b, 32b and 32a of 31, 32 and the side surfaces 33, 34 (FIG. 2) of the frame means. However, as shown in FIG. 3 (b), fine particles are not present on the detection measurement system, that is, on the slit 10, for example.
With the scattered light f of 39, each boundary portion 31a, 31b, 32b and
Images g, h, i, and j of the scattered light of 32a are formed separately in the horizontal direction, and at the same time, images m and n of the scattered light on the surfaces of the frame means 33 and 34 are separated and formed in the vertical direction. Will be imaged.

Therefore, since the slit 10 is arranged so as to pass only the scattered light f to be measured, the photoelectric converter 5 is sensitive only to the fine particles 39 in the fluid.

In the above embodiments, it was assumed that the side surfaces 31 and 32 were parallel to each other, but the incident optical axis 11 and the perpendicular 12 form an angle α, and the observation axis
14 forms an angle β with the output optical axis 13, and more preferably the angle γ
The sides 31 and 32 do not have to be parallel to each other, as is required to be 90 degrees. For example, in FIG. 3 (a), the flow path portion 3 may be formed in which only the side surface 32 is rearranged so that the angle γ is 90 degrees.

The slit 10 may not be necessary depending on the observation and measurement conditions.

(Effects of the Invention) As described above, the present invention has the side surface of the flow path portion in the optical path of the measurement light that is obliquely incident on the flow path portion and obliquely passes through the flow path portion as a result. Since the scattered light generated by the above is separated from the image of the scattered light generated by the fine particles to form an image, the light scattering type fine particle measuring device that can accurately measure only the fine particles in the fluid is facilitated. Obtainable.

[Brief description of drawings]

FIG. 1 is a system diagram of an embodiment of the present invention, FIG. 2 is an explanatory view of main parts of the embodiment of the present invention, and FIG. 3 is another main part of the embodiment of the present invention and operation of the embodiment of the present invention. System diagram,
Fig. 4 is a system diagram of a conventional device. 1, 2 ... Light irradiation system, 3 ... Flow path system, 4, 5 ... Detection / measurement system, 10 ... Slit, 11 ... Irradiation light, 12 ... Virtual vertical line, 13 ... Outgoing measurement light, 14 ... Observation axis, 31, 32 ... Light transmission part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-58-165008 (JP, A) JP-A-58-33107 (JP, A) JP-A-57-66342 (JP, A)

Claims (3)

[Claims] 1. A light scattering type fine particle measuring device for measuring fine particles in a fluid by observing scattered light obtained by irradiating the fluid to be measured with the measuring light. A flow passage system having a first light transmission portion for transmitting to the flow passage through which the first flowing light and a second light transmission portion for transmitting the first scattered light generated by the fine particles in the fluid from the flow passage to the outside, A light irradiation system that causes the measurement light to enter obliquely with respect to a virtual perpendicular line that is perpendicular to the first light transmission portion, and the first scattered light that exits from the second light transmission portion.
Detection measurement for observing from a direction different from the emission direction of the transmitted light obtained by the measurement light incident from the first light transmission unit passing through the flow path and being emitted from the second light transmission unit. The detection and measurement system includes a system for measuring the first light transmitting portion in an optical path in which the measuring light sequentially passes through the first light transmitting portion, the flow path, and the second light transmitting portion in an oblique manner. A second surface respectively generated by the surface and the surface of the second light transmitting portion.
And the third scattered light is separated from the image of the first scattered light at a position distant from the position where the first scattered light is imaged, based on that the optical path of the measurement light is oblique. A light-scattering type fine particle measuring device, which is characterized by forming an image. 2. The second direction is different from the emission direction.
The light scattering type fine particle measuring device according to claim 1, wherein the direction is in the vicinity of an imaginary perpendicular line that is perpendicular to the light transmitting portion. 3. The light scattering type fine particle measuring device according to claim 1 or 2, wherein the detection and measurement system has a slit that allows only the first scattered light to pass therethrough.