JP3530078B2 - Flow cell and particle measuring apparatus using the flow cell - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention obtains particle information such as a particle diameter of particles contained in a sample fluid passing through an irradiation region, using a flow cell having an irradiation region as a particle detection unit formed therein, and the flow cell. The present invention relates to a particle measuring device.

[0002]

2. Description of the Related Art As shown in FIG.
00 is made of a transparent member and has a rectangular cross section and a linear flow path of a predetermined length. And
The outer wall surface 101a and the inner wall surface 101b of the wall portion 101 that constitutes the flow cell 100 through which the laser light La is transmitted are formed in parallel.

When the flow cell 100 is irradiated with laser light La from a laser light source, as shown in FIG.
The laser light La is incident on the boundary surface between the air and the outer wall surface 101a at a predetermined incident angle θ ₁₁ (θ ₁₁ ≠ 0 °) and refracted at a refraction angle θ ₁₂ . This is the incident angle θ ₁₁ = of the laser light La.
When 0 ° is made to enter the outer wall surface 101a of the flow cell 100 vertically, it is prevented that the laser light La is reflected by the outer wall surface 101a and a part of the reflected light returns to the laser light source and is superimposed on the laser light La as feedback noise. This is because

[0004]

However, the flow cell 1
Since the refraction angle of the laser light La at the boundary surface between the inner wall surface 101b and the sample fluid 102 is different depending on the refractive index of the sample fluid (solvent of the sample) 102 flowing in 00, the laser light traveling in the sample fluid 102 is La1 ( The refractive index of the sample fluid is n ₂ ) or La ₂ (when the refractive index of the sample fluid is n ₃ ), and the irradiation region M as the particle detection unit provided at the center of the flow path is displaced. That is, according to Snell's law, the incident angle θ ₁₃ of the laser beam La on the boundary surface between the inner wall surface 101b and the sample fluid 102 (since the outer wall surface 101a and the inner wall surface 101b are formed in parallel, θ ₁₃ = θ
_Twelve . ), The sample fluid 102 has a refraction angle θ ₁₄ when the refractive index is n ₂ , and the sample fluid 102 has a refraction angle θ ₁₅ when the sample fluid 102 has a refractive index n ₃ .

Then, the condensing means set in accordance with the position of the irradiation region M corresponding to the sample fluid having the refractive index n ₂ is
In the case of the sample fluid having the refractive index n _3, the irradiation area M is displaced, and scattered light by particles passing through the irradiation area M cannot be detected. Therefore, due to the difference in sample fluid,
There is a problem that the particle information such as the particle diameter cannot be detected accurately.

The wall portion 1 which constitutes the flow cell 100
Depending on the shape of 01, the laser light La that has passed through the irradiation region M may have a boundary surface between the sample fluid 102 and the inner wall surface 101c,
Alternatively, the problem that a part of the reflected light is reflected by the boundary surface between the outer wall surface 101d and the air and returns to the laser light source and is superimposed on the laser light La as feedback noise, and a part of the reflected light passes through the irradiation area M again. There is a problem of increasing noise.

The present invention has been made in view of the above problems of the prior art. The object of the present invention is that the light incident on the sample fluid and passing through the irradiation region is the inner wall surface of the flow cell. And then return to the light source,
An object of the present invention is to provide a flow cell that does not pass through the irradiation region again and a particle measuring device using this flow cell.

[0008]

In order to solve the above-mentioned problems, the invention according to claim 1 irradiates light to form an irradiation region as a particle detection portion inside, and a sample fluid passing through this irradiation region is used. In a flow cell for obtaining particle information such as the particle size of particles contained, the light is incident on a boundary surface between air and an outer wall surface of the flow cell at a predetermined incident angle θ (θ ≠ 0 °), and The shape of the wall of the flow cell is formed so as to be incident on the boundary surface between the wall surface and the sample fluid at an incident angle of 0 °, and after the light passes through the irradiation region, the sample fluid and the inner wall surface of the flow cell are separated from each other. The shape of the wall portion of the flow cell is formed so as to be incident on the boundary surface at a predetermined incident angle α (α ≠ 0 °).

According to a second aspect of the present invention, in the flow cell according to the first aspect, the light is incident on a boundary surface between the outer wall surface of the flow cell and air at a predetermined incident angle α '(α' ≠ 0 °). Thus, the shape of the wall of the flow cell is formed.

According to a third aspect of the present invention, light is irradiated to form an irradiation region as a particle detection unit inside, and particle information such as the particle size of particles contained in the sample fluid passing through this irradiation region is obtained. In the flow cell for the following, after the light is incident on the sample fluid and passes through the irradiation region, the light is incident on the boundary surface between the sample fluid and the inner wall surface of the flow cell at an incident angle of 0 °, and then the light is emitted. The shape of the wall portion of the flow cell is formed so as to be incident on the boundary surface between the outer wall surface of the flow cell and air at a predetermined incident angle α ″ (α ″ ≠ 0 °).

The invention according to claim 4 is the flow cell according to any one of claims 1 to 3, a light source for irradiating the flow path of the flow cell with light to form an irradiation region, and the irradiation region. An optical detection processing means for detecting scattered light, transmitted light or diffracted light of particles is provided.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a configuration diagram of a particle measuring apparatus according to the present invention, FIG. 2 is a cross-sectional view of a flow cell according to the present invention, and FIG. 3 is an explanatory diagram of a light transmission path in a wall portion of the flow cell.

As shown in FIG. 1, the particle measuring apparatus according to the present invention comprises a flow cell 1, a laser light source 2, a condensing optical system 3,
The photoelectric conversion element 4 and the like are provided. The flow cell 1 is made of a transparent member, has a linear flow path 1a of a predetermined length, and is bent into an L-shaped tubular shape as a whole.

Further, as shown in FIG. 2, the flow cell 1 is composed of a wall 5 having a quadrangular cross section, the inner cross section having a trapezoidal shape, and the outer cross section having a trapezoidal shape. The outer wall surface 5a on which the laser light La is incident and the laser light La
Is not parallel to the inner wall surface 5b from which the
Are formed with a predetermined angle (inclination) with respect to the inner wall surface 5b. Furthermore, the inner wall surface 5b from which the laser light La is emitted
The inner wall surface 5c on which the laser light La is incident is not parallel to each other, and the inner wall surface 5c is formed with a predetermined angle (inclination) with respect to the inner wall surface 5b.

The reason why the linear flow path 1a having a predetermined length is provided is to make the flow of the sample fluid 6 laminar when the sample fluid 6 is flown into the flow cell 1. The conditions for obtaining the laminar flow include the viscosity of the sample fluid 6, the length of the linear flow channel, the cross-sectional shape of the flow channel and the flow velocity, and the length of the linear flow channel 1a and the cross-sectional shape of the flow channel are as follows. , And is determined in consideration of the viscosity and flow velocity of the sample fluid 6.

The laser light source 2 irradiates a predetermined portion of the linear flow path 1a of the flow cell 1 with the laser light La to form an irradiation area M. Here, the optical axis of the laser light La is the linear flow path 1
Within a, it is substantially orthogonal to the central axis of the linear flow path 1a.

Further, as shown in FIG. 2, laser light La
Is incident on the boundary surface between the air and the outer wall surface 5a at an incident angle θ. This is to prevent the laser light La from being reflected at the boundary surface between the air and the outer wall surface 5a and returning part of the reflected light to the laser light source 2 as described above. This is because, when a part of the reflected light returns to the laser light source 2, the feedback noise is superimposed on the laser light La, which is not preferable.

Further, the laser beam La which has passed through the irradiation area M
Is a predetermined incident angle α at the boundary surface between the sample fluid 6 and the inner wall surface 5c.
The light enters at (α ≠ 0 °) and also enters at the boundary surface between the outer wall surface 5d and the air at a predetermined incident angle α ′ (α ′ ≠ 0 °).

In this way, the incident angle α of the laser light La,
The reason why α ′ is not set to 0 ° is that the laser light La is reflected by the boundary surface between the sample fluid 6 and the inner wall surface 5c and the boundary surface between the outer wall surface 5d and the air as described above, and a part of the reflected light is laser light. This is to prevent the light from returning to the light source 2 and a part of the reflected light from passing through the irradiation region M again. This is because, when a part of the reflected light returns to the laser light source 2, the feedback noise is superimposed on the laser light La, which is not preferable. Further, when a part of the reflected light passes through the irradiation area M again, noise is increased, which is also undesirable.

The condensing optical system 3 has an optical axis that coincides with the central axis of the linear flow path 1a of the flow cell 1, and has a function of condensing the scattered light Ls emitted by the particles that have received the laser light La in the irradiation region M. Equipped with. The condensing optical system 3 does not necessarily have to be provided on the central axis of the linear flow path 1a of the flow cell 1.

The photoelectric conversion element 4 is provided on the optical axis of the condensing optical system 3. The photoelectric conversion element 4 converts the scattered light Ls emitted while the particles pass through the irradiation region M into a voltage.
In addition, the means after the condensing optical system 3 is referred to as an optical detection processing means.

The operation of the flow cell according to the present invention constructed as above and the particle measuring apparatus using the flow cell will be described. Here, the refractive index of air is n ₀ , the wall 5 of the flow cell 1 is n ₁ , and the sample fluid 6 is n ₂ or n ₃ .

As shown in FIG. 3, the light is emitted from the laser light source 2.
The generated laser light La is applied to the boundary surface between the air and the outer wall surface 5a.
When incident and refracted, according to Snell's law, incident
Angle θ ₁And refraction angle θ₂The following formula (1) is established between
Stand up.

N ₀ · sin θ ₁ = n ₁ · sin θ ₂ (1)

Next, the laser light La goes straight on the wall portion 5. Then, at the boundary surface between the inner wall surface 5b and the sample fluid 6,
Similarly, according to Snell's law, the refraction angle θ _{4 in} the case of the sample fluid 6 having the incident angle θ ₃ and the refractive index n ₂ or the incident angle θ ₃ and the refractive index n
_In the case of the sample fluid 6 of ₃ and the refraction angle θ ₅ , the following formula (2) is established.

N ₁ · sin θ ₃ = n ₂ · sin θ ₄ = n ₃ · sin θ ₅ (2)

Therefore, in order to make the position of the irradiation region M constant without being affected by the value (n ₂ or n ₃ ) of the refractive index of the sample fluid 6, the refraction angles may be made substantially equal. From Expression (2), to satisfy the condition, sin θ ₃ = sin θ ₄
= Sin θ ₅ = 0, that is, the laser beam La may be incident on the boundary surface between the inner wall surface 5b and the sample fluid 6 at an incident angle θ ₃ = 0 °.

When the laser light La is incident on the boundary surface between the inner wall surface 5b and the sample fluid 6 at the incident angle θ ₃ = 0 °, the refraction angle θ ₄
= Refraction angle θ ₅ = 0 °, always equal refraction angle (0 °)
Thus, the laser light La travels in the sample fluid 6. Note that θ ₃ does not have to be exactly 0 °, and may be within a range in which the displacement of the irradiation region M can be tolerated. Therefore, θ
₃ may be approximately 0 °.

Therefore, in order to cause the laser beam La to enter the boundary surface between the inner wall surface 5b and the sample fluid 6 at the incident angle θ ₃ = 0 °, as shown in FIG. 3, the outer wall surface 5a and the inner wall surface 5b are connected to each other. Letting θ ₆ be the angle formed by, the refraction angle θ _{2 at} the boundary surface between the air and the outer wall surface 5 a should be equal to θ ₆ (θ ₂ = θ ₆ ).

Further, in equation (1), assuming θ ₂ = θ ₆ , what angle of incidence θ ₁ should be used to make the laser beam La incident on the boundary surface between the air and the outer wall surface 5a is determined.
The incident angle θ ₁ is the refractive index n _{0 of} air and the wall portion 5 of the flow cell 1.
Is determined by the refractive index n ₁ and the angle θ ₆ formed by the outer wall surface 5a and the inner wall surface 5b, and can be obtained by the following mathematical expression (3).

Θ ₁ = sin ⁻¹ {(n ₁ / n ₀ ) sin θ ₆ } (3)

Therefore, at the angle θ ₁ which satisfies the equation (3),
When the laser light La is incident on the boundary surface between the air and the outer wall surface 5a, the irradiation area M is irrelevant to the value of the refractive index of the sample fluid 6.
The position of can be maintained constant.

When the sample fluid 6 is caused to flow through such a flow cell 1, the particles passing through the irradiation region M are irradiated with the laser light La, and the scattered light Ls emitted from the particles receiving the laser light La is collected by the condensing optical system 3. Collected.

Next, the scattered light Ls condensed by the condensing optical system 3 is converted into a voltage by the photoelectric conversion element 4. Then, the number of particles is measured by the number of peaks of the voltage converted by the photoelectric conversion element 4, and the particle size of the particles is measured by the value of the voltage.

Then, the laser light L which has passed through the irradiation area M
When a is incident on the boundary surface between the sample fluid 6 having the refractive index n ₂ and the inner wall surface 5c and is refracted, according to Snell's law, it is between the incident angle α ₁ (α ₁ ≠ 0 °) and the refraction angle β _1. , The following formula (4) is established.

N ₂ · sin α ₁ = n ₁ · sin β ₁ (4)

Further, the laser beam La that has passed through the irradiation area M
When incident on the boundary surface between the sample fluid 6 having the refractive index n ₃ and the inner wall surface 5c and refracting, the angle of incidence α ₁ (α ₁ ≠ 0 °) and the angle of refraction β ₂ follow the Snell's law. The following formula (5) is established during the period.

N ₃ · sin α ₁ = n ₁ · sin β ₂ (5)

As described above, the incident angle α ₁ is not 0 ° because the boundary between the sample fluid 6 on which the laser beam La is incident and the inner wall surface 5c has the refraction angles θ ₄ and θ _{5 of the} laser beam La of 0 °. This is because it is not parallel to the boundary surface between the inner wall surface 5b and the sample fluid 6. That is, the wall portion 5 of the flow cell 1 is formed so that the inner wall surface 5c and the inner wall surface 5b have a predetermined angle so that the incident angle α ₁ does not become 0 °.

Further, the laser beam La refracted at the refraction angle β ₁
When 3 is incident on the boundary surface between the outer wall surface 5d and air and is refracted, according to Snell's law, between the incident angle α ₂ (α ₂ ≠ 0 °) and the refraction angle β ₃ , the following mathematical formula (6) is established.

N ₁ · sin α ₂ = n ₀ · sin β ₃ (6)

Further, the laser beam La refracted at the refraction angle β ₂
Even when 4 is incident on the boundary surface between the outer wall surface 5d and air and is refracted, the incident angle α ₃ (α ₃ ≠ 0 °) is similarly obeyed by Snell's law.
And the refraction angle β ₄ between the following equation (7)
Holds.

N ₁ · sin α ₃ = n ₀ · sin β ₄ (7)

[0044] Incidentally, the incident angle alpha ₂ and the incident angle alpha _3, the critical angle determined by the refractive index n ₁ and the refractive index n ₀ (sin ^-1 (n ₀
/ N ₁ )) is preferable. When the incident angles α ₂ and α ₃ are larger than the critical angle, the laser beams La3 and La3 are
This is because 4 is totally reflected at the boundary surface between the outer wall surface 5d and the air, which is not preferable.

Here, the incident angles α ₂ and α ₃ become 0 ° when the angle β ₅ formed by the inner wall surface 5c and the outer wall surface 5d is equal to the refraction angles β ₁ and β ₂ , respectively (β ₅ = Β ₁ , β ₅ = β ₂ ). The refraction angles β ₁ and β ₂ can be calculated by the following equations (8) and (9), respectively.

Β ₁ = sin ⁻¹ {(n ₂ / n ₁ ) sin α ₁ } (8)

Β ₂ = sin ⁻¹ {(n ₃ / n ₁ ) sin α ₁ } (9)

Therefore, in order not to set the incident angles α ₂ and α ₃ to 0 °, the angle β ₅ formed by the inner wall surface 5c and the outer wall surface 5d of the flow cell 1 should not be equal to the refraction angles β ₁ and β _2. Then, the wall portion 5 may be formed.

Here, regardless of the refractive indexes of the flow cell 1 and the sample fluid 6, the conditions under which the incident angles α ₂ , α ₃ of the laser light La on the boundary surface between the outer wall surface 5d and the air do not become 0 ° are obtained. From Equations (4) and (5), β ₁ ≠ 0 °, β ₂ ≠
It becomes 0 °. Therefore, in order to satisfy the conditions that the incident angles α ₂ and α ₃ do not become 0 °, β ₅ ≠ β ₁ and β ₅ ≠ β ₂ , β ₅ = 0 °.

Β ₅ = 0 ° means the inner wall surface 5 of the flow cell 1.
This means that c and the outer wall surface 5d are parallel to each other. That is,
If the inner wall surface 5c and the outer wall surface 5d are formed in parallel, the incident angle of the laser light La on the boundary surface between the outer wall surface 5d and the air will not be 0 ° regardless of the refractive index of the flow cell 1 and the sample fluid 6. .

By the way, the form such as the angle between the inner wall surface 5c and the outer wall surface 5d of the flow cell 1 from which the laser light La is emitted from the flow cell 1 is not limited to the embodiment of the present invention. That is, in the present invention, the laser light La surely passes through the irradiation region M of the flow cell 1 without being influenced by the refractive index of the sample fluid 6 flowing in the flow cell 1.
Further, the light is incident on the boundary surface between the sample fluid 6 and the inner wall surface 5c at a predetermined incident angle α (α ≠ 0 °), and also at the boundary surface between the outer wall surface 5d and the air at a predetermined incident angle α ′ (α ′ ≠. It suffices that the shape of the wall portion 5 of the flow cell 1 is formed so as to be incident at 0 °.

Therefore, the form such as the angle between the inner wall surface 5c and the outer wall surface 5d of the flow cell 1 is determined by the inner wall surface 5c and the outer wall surface 5d.
As shown in FIG. 2 or FIG. 3, it is not necessary to form the entire surface in the same shape, and it is also possible to form only the portion through which the laser light La passes so that the incident angle does not become 0 °.

Up to now, the laser light La is supplied to the sample fluid 6
Incident angle α (α ≠ 0 °) on the boundary surface between the inner wall surface 5c and
The description has been made on the premise that the light is incident on the laser light source and the reflected light here is prevented from returning to the laser light source or the irradiation region M. However, if the reflected light returning to the laser light source or the irradiation region M can be reduced as much as possible, it is obvious that the corresponding effect can be obtained.

Therefore, even when the laser light La is incident on the boundary surface between the sample fluid 6 and the inner wall surface 5c at an incident angle α of 0 °, the laser light La is at the boundary surface between the outer wall surface 5d and the air. If the shape of the wall portion 5 of the flow cell 1 is formed so as to be incident at a predetermined incident angle α ″ (α ″ ≠ 0 °) on the laser beam La,
Can be prevented from being reflected at the boundary surface between the outer wall surface 5d and the air, and it is possible to prevent feedback noise from being superposed on the laser light La by returning a part of the reflected light to the laser light source.

In the embodiment of the present invention, the light scattering type particle measuring device has been described.
Light-blocking type particle measuring device for measuring the number of particles or the particle size by detecting the amount of reduction of the amount of transmitted light due to the presence of particles passing through, and detecting the diffracted light generated by the presence of particles passing through the irradiation area M. It can also be applied to a light diffraction type particle measuring device.

[0056]

As described above, according to the first aspect of the invention, after the light passes through the irradiation area as the particle detecting section, the sample fluid is not affected by the magnitude of the refractive index of the sample fluid. It is possible to prevent reflection in the direction of returning to the light source at the boundary surface between the inner wall surface and the inner wall surface, part of the reflected light is returned to the light source, and feedback noise is superimposed on the light, and part of the reflected light is the irradiation area. It is possible to avoid passing through again to increase the noise.

According to the second aspect of the present invention, after the light passes through the irradiation area as the particle detecting portion, the light is not affected by the magnitude of the refractive index of the sample fluid, and the light is passed through the boundary surface between the sample fluid and the inner wall surface. In addition to being able to prevent reflection in the direction returning to the light source, it is also possible to prevent light from being reflected in the direction returning to the light source at the boundary surface between the outer wall surface and air, thus By returning the part to the light source, it is possible to avoid that feedback noise is superposed on the light and that part of the reflected light again passes through the irradiation area to increase the noise.

According to the third aspect of the invention, it is possible to prevent light from being reflected in the direction of returning to the light source at the boundary surface between the outer wall surface and the air, and a part of the reflected light is returned to the light source. It is possible to avoid that the feedback noise is superimposed on the light and that part of the reflected light passes through the irradiation area again and increases the noise.

According to the fourth aspect of the present invention, the number of particles contained in the sample fluid and the particle size of the particles can be measured without being affected by the magnitude of the refractive index of the sample fluid.

[Brief description of drawings]

FIG. 1 is a block diagram of a particle measuring apparatus according to the present invention.

FIG. 2 is a sectional view of a flow cell according to the present invention.

FIG. 3 is an explanatory diagram of a light transmission path in a wall portion of a flow cell.

FIG. 4 is a sectional view of a conventional flow cell.

FIG. 5 is an explanatory diagram of a light transmission path in a wall portion of a conventional flow cell.

[Explanation of symbols]

1 ... Flow cell, 2 ... Laser light source, 3 ... Condensing optical system, 4
... photoelectric conversion element, 5 ... wall portion, 5a, 5d ... outer wall surface, 5
b, 5c ... inner wall surface, 6 ... sample fluid, La ... laser light, M
… Irradiated area.

Claims (4)

(57) [Claims] 1. A flow cell for irradiating light to form an irradiation region as a particle detection unit therein and obtaining particle information such as a particle size of particles contained in a sample fluid passing through the irradiation region, Light is incident on the boundary surface between the air and the outer wall surface of the flow cell at a predetermined incident angle θ (θ ≠ 0 °), and
The wall of the flow cell is shaped so as to be incident on the boundary surface between the inner wall surface of the flow cell and the sample fluid at an incident angle of 0 °, and after the light passes through the irradiation region, the inside of the sample fluid and the flow cell is Predetermined incident angle α on the boundary surface with the wall surface
A flow cell in which the shape of the wall of the flow cell is formed so as to be incident at (α ≠ 0 °). 2. The flow cell according to claim 1 , wherein
The flow cell is characterized in that the shape of the wall portion of the flow cell is formed so that the light is incident on a boundary surface between the outer wall surface of the flow cell and air at a predetermined incident angle α '(α' ≠ 0 °). 3. A flow cell for irradiating light to form an irradiation region as a particle detection unit therein and obtaining particle information such as a particle size of particles contained in a sample fluid passing through the irradiation region, After the light is incident on the sample fluid and passes through the irradiation region, it is incident on the boundary surface between the sample fluid and the inner wall surface of the flow cell at an incident angle of 0 °, and then the light is incident on the outer wall surface of the flow cell and the air. A flow cell in which the shape of the wall portion of the flow cell is formed so as to be incident at a predetermined incident angle α ″ (α ″ ≠ 0 °) on the boundary surface with. Flow cell according to any one of claims 4] claims 1 to 3, a light source for forming the irradiation region is irradiated with light in the flow path of the flow cell, the scattered light of the particles of the irradiation region, transmission A particle measuring apparatus comprising an optical detection processing means for detecting light or diffracted light.