JPS6225236A - Particles detecting device using light - Google Patents

Abstract

PURPOSE:To catch scattered light in its natural state without converging it on one point through an optical system and to shorten an adjustment time by providing a stray light removing member between a flow cell and a light receiver. CONSTITUTION:The focus P of a condenser lens 8 for a light beam (a) is positioned at a particle array in the flow cell 2. Then, a stray light removing member 5 and the light receiver 4 are arranged at a specific angle theta at a specific position from the center of the flow cell 2 to catch the focus P of the particle array 1 in a light passing hole 6, thus adjusting the optical axis. Part of the scattered light (b) generated by irradiating particles in the particle array 1 in the flow cell 2 with the light beam (a) passes through the light passing hole 6 of the stray light removing member 5 and is detected by the light receiver 4. At this time, reflection on the internal surface is prevented and stray light and straight traveling light (c) are removed securely because the internal surface of the light passing hole 6 is a twisted surface.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention is directed to the use of particles in a liquid, such as blood cells in blood.
The present invention relates to a light-based particle detection device that detects light scattered from particles irradiated with light.

Conventional Technology When a high-speed fluid is passed around a fiA liquid containing fine particles in a sheath shape, the central flow becomes a rivulet in which the particles flow in a single line. Particles in the suspension can be detected by irradiating the particles with light and detecting the scattered light of the particles.

The principle structure of a conventional particle detection device of this type is shown in Figure 5.
In the figure, reference numeral 20 denotes a rectangular pipe-shaped flow cell, through which a high-speed fluid is passed around a suspension liquid containing particles, and particle arrays 21 are formed in the central flow. A light beam a from a light source 22 consisting of a laser emitting device is converged by a condenser lens 23 so as to have a focal point P on the particle array 21, and the particles of the particle array 21 generate scattered light. The scattered light is collected by the collector lens 24, and the pinhole plate 2
5 and enters the light receiver 26. The light receiver 26 generates electric pulses by photoelectric conversion. The straight light of the light ray a from the light source 22, that is, the light that does not hit the particles, is blocked by the dark field disk 27 in front of the collector lens 24 and by the surrounding stray light Hahinhole plate 25. As a result, only the scattered light from the particles is transmitted to the light receiver 26.
can be detected and particle measurements can be performed.

Problems to be Solved by the Invention Since the particles to be measured have a small diameter of about 0.5 μm, a high-magnification, high-sensitivity optical system is required to detect the scattered light from the particles. Therefore, in this conventional structure, the collector lens 2
4 and a pinhole plate 25 are used, but this makes the adjustment work complicated. That is, the focal point P of the condenser lens 23, the position of the particle array 21 of the flow cell 20, and the object point position of the collector lens 24 must be aligned, and the focus must be placed at a position conjugate with the object point position of the collector lens 24. A pinhole in the hole plate 25 must be placed. Therefore, it is necessary to adjust the axis of the condenser lens 23 and the axis of the collector lens 24 to match at the center of the flow cell 20, and this adjustment takes a long time (3 to 4 hours).

In addition, the collector lens 24, pinhole plate 25, and dark field desk 27 require precision and marginal high performance, so their cost as parts is high. It is necessary to include an x-y-z fine movement stage, and including these will increase the cost of the optical system.

Furthermore, the distance between the flow cell 20 and the pinhole plate 25 is
Even if a commercially available or custom-made collector lens 24 with the limit performance that can be stably handled manually is used, the distance will be 150 to 160 m. Therefore, the entire detection device requires more than 300 dragons, making it impossible to downsize the device.

The present invention has been made in view of these drawbacks, and an object of the present invention is to provide a small-sized, low-cost light-based particle detection device that can significantly shorten adjustment time.

Means for Solving the Problems The present invention provides a stray light removing member between the flow cell and the light receiver instead of the conventional optical system. The stray light removing member has a light passage hole through which scattered light passes.

Effects According to this configuration, the following effects can be obtained. Scattered light generated by irradiating light beams onto the particles in the particle array of the flow cell is around the solid angle of the straight light that travels without hitting the particles, but some of this scattered light passes through the light passage hole of the stray light removal member. through,
Detected by a photoreceiver.

Straight light and surrounding stray light cannot pass through the light passage hole of the stray light removing member and are blocked.

In this invention, the scattered light that becomes the particle detection signal is captured in its natural state without using an optical system to collect it at one point as in the past, so there is no need for highly accurate positioning as in the past. , the position of the stray light removing member, etc. can be easily adjusted.

In this way, since there is no need for highly accurate adjustment at all on the light receiving side of the scattered light, there is no need to use an xyz fine movement stage, etc., and costs are reduced. Furthermore, since there is no need for expensive components such as a dark field disk, collector lens, or pinhole plate, costs are also reduced. Furthermore, as mentioned above, since the light receiver can be brought close to the flow cell, the entire device can be made compact.

The reduction in sensitivity due to the removal of the conventional collector lens can be compensated for by placing the light receiver close to the particle array that serves as the light source of the scattered light. Since no collector lens is used on the light receiving side, there is no focal length problem and the light receiver can be placed close to the flow cell.

Since the received light intensity decreases in inverse proportion to the square of the distance, the effect of improving sensitivity by moving the receiver closer to the light source is large.
Furthermore, since the light reception sensitivity of scattered light is improved in this way, the signal-to-noise ratio becomes large, and accurate particle detection can be performed.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention is shown in FIGS. 1 to 3. This particle detection device includes a flow cell 2 through which a fluid flows in a state where a particle column 1 is formed, and a particle column 1 in the flow cell 2. In an optical particle detection device comprising a light irradiation means 3 for irradiating a light beam a to a particle array 1, and a light receiver 4 for detecting scattered light reflected by the light beam a, the flow cell 2 and the light receiving device are provided. A stray light removing member 5 having a light passage hole 6 through which the scattered light passes is provided between the stray light removing member 5 and the vessel 4.

The flow cell 2 is similar to the example shown in FIG. Light irradiation means 3
consists of a light source 7 consisting of a 20 mW semiconductor laser and a condenser lens 8. It is sufficient for the photoreceiver 4 to have a light-receiving surface with a diameter of about 1fi, but in this example, a 2.4fl square silicon square diode is used, which has the ability to detect latex with a diameter of 0.6μm. The light receiver 4 has an exit 6 of the light passage hole 6 of the stray light removing member 5.
Place it close to a.

The continuous hole removing member 5 has a thick cylindrical shape and is made of black polyacetal resin.

The light passage hole 6 is tunnel-shaped, has a sufficiently long depth relative to its inner diameter, and is slightly inclined with respect to the optical axis A. The light passage hole 6 has an inner diameter of 1 m, and the inner surface is formed into a tapered surface with a pitch of 0.5 tm. The inclination angle θ of the light passage hole 6 is, for example, 5 to 7 degrees, and the distance between the stray light removing member 5 and the center of the flow cell 2 is 12 to 13 degrees. As a result, the focal point P of the light ray a hitting the particle array 1 is shifted to the light passing hole 6.
Adjust so that it can be captured inside.

The stray light removing member 5 and the light receiver 4 are aligned in advance and fixed integrally with each other. Attach to. Further, the condenser lens 8 has an optical axis A
The flow cell 2 is installed on a support stand so that it can move back and forth in the direction (X direction), and the flow cell 2 is moved in the direction perpendicular to its longitudinal direction and the optical axis A (
It is installed on a support stand that is movable in the Y direction.

According to this configuration, the following effects can be obtained. flow cell 2
The scattered light generated by the light beam a irradiated on the particles of the particle row (■) is located around the straight light C that travels without hitting the particles, but a part of this scattered light passes through the light passage hole of the stray light removing member 5. 6 and is detected by the light receiver 4. Although the straight light C becomes stray light, the stray light cannot pass through the light passage hole 6 of the stray light removing member 5 and is blocked. At this time, since the inner surface of the light passage hole 6 is a threaded surface, reflection on the inner surface can be prevented, and stray light and straight light C can be removed more reliably.

The decrease in sensitivity due to the removal of the conventional collector lens can be compensated for by placing the light receiver 4 close to the particle array 1 that is the light source of the scattered light. Since no collector lens is used on the light receiving side, there is no problem with the image point distance, and the light receiver 4 can be placed close to the flow cell 2. The received light intensity is 2 of the distance
Since the sensitivity decreases in inverse proportion to the power of Become. As a result, detection performance equivalent to or higher than that of conventional detection devices can be obtained.

The optical axis adjustment is performed as follows. That is, by moving the condenser lens 8 in the X direction and moving the flow cell 2 in the Y direction, the focal point P of the light ray a by the condenser lens 8 is located at the particle row 1 in the flow cell 2. Do it like this. After this,
Stray light removing member 5 and light receiver 4 whose axes are aligned with each other in advance
is arranged at a predetermined inclination angle θ at a predetermined position from the center of the flow cell 2, and the adjustment is completed by capturing the focal point P of the particle array 2 within the light passage hole 6.

At this time, the scattered light is captured in its natural state without using an optical system to focus it on one point as in the past, so there is no need for highly accurate position adjustment. Only rough adjustment is required, that is, the light passing hole 6 is the exit 6
Since the hole is inclined so that the a side is away from the optical axis A II+, and it is a tunnel-shaped hole with a long depth relative to the inner diameter, the straight light C cannot pass through the light passage hole 6 at all.
Furthermore, even if the stray light can pass through, the position of the stray light removing member 5 that allows the stray light to pass through is limited to a very small range.

On the other hand, since the direction in which the scattered light travels is inclined with respect to the optical axis A and is close to the inclination angle of the light passage hole 6, the position of the central axis B of the stray light removing member 5 is as shown in FIG. Scattered light can pass through even if it is slightly deviated from the focal point P. Therefore, high precision is not required for positioning the stray light removing member 5.

In this way, the digit 2 of the stray light removing member 5! Adjustment does not require precision, and whereas conventional systems require adjustment of two components, the collector lens and pinhole plate, on the light receiving side, this device only requires adjustment of the stray light removal member 5. The time required for optical axis adjustment has been significantly shortened, compared to 3
What used to take ~4 hours can now be completed in about 30 seconds.

Furthermore, since there is no need for highly accurate adjustment at all on the light receiving side of the scattered light, there is no need to use an x-y-z fine movement stage, etc., and costs are reduced. Also,
This also reduces costs because there is no need for expensive components such as a dark field disk, collector lens, or pinhole plate. Furthermore, as mentioned above, since the light receiver 4 can be brought close to the flow cell 2, the entire device can be made compact.
The distance can be set to 10 to 15fi, and the length of the entire detection device can be set to about 120 fl.

In the above embodiment, the stray light removing member 5 is cylindrical, but the light passing hole 6' of the stray light removing member 5' may be formed into a thin rectangular slit shape as shown in FIG.

Further, the inner surface of the light passage hole 6.6' may be a rough surface with unevenness instead of a threaded surface, or may be a flat surface.

Effects of the Invention The light-based particle detection device of this invention does not use an optical system to collect the scattered light that serves as a particle detection signal at one point, but simply passes it through the light passage hole of the stray light removal member, allowing it to be detected in its natural state. Because it captures the information, highly accurate adjustment is not required, which greatly reduces adjustment time.

The decrease in sensitivity caused by omitting the lens on the light receiving side can be compensated for by placing the light receiver close to the particle array that serves as the light source of the scattered light.

Furthermore, since high precision is not required as described above, a fine positioning device is not required, and expensive parts such as lenses are not used on the light receiving side, so component costs are also reduced. Furthermore, since no lens is used on the light-receiving side, there is no need to set a focal length, resulting in an effect of miniaturization.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is an enlarged sectional view of the stray light removing member, FIG. 3 is an explanatory diagram of its operation, and FIG. 4 is a perspective view of a modified example of the stray light removing member. , FIG. 5 is a principle diagram of a conventional optical particle detection device. DESCRIPTION OF SYMBOLS 1... Particle row, 2... Flow cell, 3... Light irradiation means, 4... Light receiver, 5... Stray light removal member, 6...
・Light passing hole, a...light beam, b...scattered light, C...
Straight light E, 1Ji ('-: medium 1- particle array 2 = -70-destruction
3. Fan Teruwanite “E4- Complete set of UtXS and fl J]
薊4 people 6...Sientoshi-ALa-E, line
b-・-Cooked fertilizer c-Direct 1-Yu Figure 1 Figure 2 Figure 3

Claims (3)

[Claims] (1) A flow cell that allows a fluid to flow through a particle array, a light irradiation means that irradiates a light beam onto the particle array in the flow cell, and detects scattered light that is reflected by the light beam hitting the particles in the particle array. An optical particle detection device comprising a light receiver, further comprising a stray light removing member having a light passage hole through which the scattered light passes between the flow cell and the light receiver. Device. (2) The light passage hole according to claim 1, wherein the light passage hole has a sufficiently long depth relative to the inner diameter, and is tilted so that the exit side is away from the optical axis of the light beam. particle detection device. (3) The light-based particle detection device according to claim (2), wherein the inner surface of the light passage hole is formed into an uneven surface.