Particle measuring device, method, and program

Abstract

To provide a particle measuring device that can be achieved at a low price and that can measure particles with easy operations.SOLUTION: According to an embodiment, a particle measuring device comprises: a light source that supplies illumination light for illuminating a particle in liquid; an imaging unit that picks up an image of the illumination light passing through the particle; and a measuring unit that measures the distance between the particle and the imaging unit, on the basis of the transmitted light intensity of the illumination light imaged by the imaging unit and the known particle diameter and refractive index of the particle.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a particle measuring apparatus, method, and program for measuring particles contained in treated water in organic wastewater treatment.

Background Art

[0002] In the treatment of organic wastewater such as municipal sewage, the activated sludge method is generally used. In the activated sludge method, air is supplied to the treated water, and the organic matter in the treated water is decomposed by the action of organic matter.

[0003] A typical useful microorganism in activated sludge is Bacillus bacteria (hereinafter simply referred to as "Bacillus"). Since the enzymes and antibiotics produced by Bacillus have a bacteriolytic effect, the amount of excess sludge generated is small in treatment facilities where Bacillus is dominant. In addition, Bacillus also plays a role in stopping the action of sulfate-reducing bacteria, and the amount of odor generated is also small.

[0004] Therefore, it is important to grasp the number of Bacillus in order to determine whether sufficient Bacillus is contained in the treated water.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Non-Patent Documents

[0006]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] The problem to be solved by the present invention is to provide a particle measuring device, method, and program that can be realized at low cost and can measure particles with easy operation.

Means for Solving the Problem

[0008] The particle measuring device according to the embodiment includes a light source that supplies illumination light for illuminating particles in a liquid, an imaging unit that images the illumination light transmitted through the particles, and a measurement unit that measures the distance between the particles and the imaging unit based on the transmitted light intensity of the illumination light imaged by the imaging unit, the known particle size and refractive index of the particles.

Brief Description of the Drawings

[0009]

Figure 1

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Best Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments and examples of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationships between the thickness and width of each part, the ratio of the sizes between parts, etc. are not necessarily the same as those in reality. Also, even when representing the same part, there are cases where the dimensions and ratios are represented differently in the drawings. In the specification of this application and each figure, the same reference numerals are given to the same elements as those described above with respect to the previously shown figures, and detailed descriptions and overlapping descriptions are omitted as appropriate.

[0011] FIG. 1 is a block diagram showing a configuration example of a particle measurement apparatus to which the particle measurement method according to an embodiment of the present invention is applied.

[0012] FIG. 2 is a flowchart showing a measurement flow by a particle measurement apparatus to which the particle measurement method according to an embodiment of the present invention is applied.

[0013] That is, the particle measurement apparatus 10 of the present embodiment includes a light source 12, an imaging unit 16, a particle determination unit 18, a measurement unit 20, a contact determination unit 22, a count unit 24, a database 26, and a machine learning unit 26.

[0014] The particle measurement apparatus 10 is used to measure particles to be measured, such as Bacillus bacteria, contained in treated water such as organic wastewater such as municipal sewage. For this purpose, a sample aqueous solution S measured in a predetermined amount (for example, about 1 cc) is supplied from the treated water to the particle measurement apparatus 10 (S1).

[0015] As described in FIG. 3 to be described later, the imaging unit 16 includes a surface 16a of an image sensor such as a CCD or a CMOS and a light receiving unit 16b inside.

[0016] The sample aqueous solution S measured in step S1 is dropped onto the surface 16a of the image sensor (S2). After dropping the sample aqueous solution S, wait for a certain period of time (for example, about 10 minutes) until the particles contained in the sample aqueous solution S float or settle and the influence due to convection or the like stabilizes (S3).

[0017] The light source 12 is provided above the imaging unit 16, and after the elapse of the aforementioned certain period of time (for example, about 10 minutes), illuminates the illumination light H in the vertical direction toward the imaging unit 16. The illumination light H illuminates the sample aqueous solution S. As a result, the particles to be measured contained in the sample aqueous solution S are illuminated by the illumination light H.

[0018] The imaging unit 16 condenses the illumination light H that has passed through the particles via the surface 16a of the image sensor, receives the condensed illumination light H by the light receiving unit 16b, and performs imaging (S4).

[0019] The particle determination unit 18 determines that in the image G captured by the imaging unit 16, the portion where the transmitted light intensity is equal to or greater than a preset threshold corresponds to particles. The threshold can be determined from, for example, the background light intensity of the image G, but is not limited thereto.

[0020] The counting unit 24 counts the portions determined by the particle determination unit 18 to correspond to the particles W (S5). To perform this counting, the counting unit 24, for example, in the image G, causes the portions determined by the particle determination unit 18 to correspond to the particles to be displayed in a color different from the background, and counts the portions displayed in a different color, whereby the portions determined to correspond to the particles can be counted.

[0021] The database 26 accumulates the light intensity distribution information of the portions determined by the particle determination unit 18 to correspond to the particles in the image G.

[0022] The machine learning unit 28 performs image analysis by machine learning on the light intensity distribution information stored in the database 26.

[0023] As a result, when a new image G is captured by the imaging unit 16, the particle determination unit 18 can also determine a portion corresponding to a particle in the new image G based on the analysis result by the machine learning unit 28 without using the above-described threshold value.

[0024] The measurement unit 20 measures the distance between the particle determined by the particle determination unit 18 and the surface 16a of the image sensor. This measurement is performed based on the transmitted light intensity of the illumination light H captured by the imaging unit 16 and the known particle size and refractive index n2 of the particle W for the particle determined by the particle determination unit 18. For example, since the particles of Bacillus bacteria are spherical, when the particle is Bacillus bacteria, the known particle size of the particle can be the diameter of the spherical Bacillus bacteria.

[0025] The contact determination unit 22 determines whether or not the particle is in contact with the surface 16a of the image sensor based on the distance measured by the measurement unit 20.

[0026] Next, in each of the following examples, the verification results of the validity of the measurement by the particle measurement device of the present embodiment will be described.

[0027] (Example 1) In Example 1, the verification result by calculation of the measurement validity by the particle measurement device of the present embodiment will be described.

[0028] FIG. 3 is a ray tracing diagram until the illumination light, which is parallel light incident on the particles in the sample aqueous solution, passes through the particles and reaches the light receiving portion of the image sensor.

[0029] The illumination light H from the light source 12 becomes parallel light directed in the vertical direction and illuminates the sample aqueous solution S.

[0030] The illumination light H is bent like a lens by the spherical particles W to be measured, such as Bacillus bacteria, in the sample aqueous solution S, and is further condensed on the light receiving portion 16b through the surface 16a of the image sensor.

[0031] The following formula is the ray tracing determinant for parallel light passing through a spherical particle W.

[0032] [Number]

[0033] Substituting the radius r of the spherical particle W and the relative refractive index n = n2 / n1 between the refractive index n1 of the particle W and the refractive index n2 of the aqueous solution S into the known ray tracing determinant shown above, for the particle W, the illumination light H, which is parallel light (u = 0) incident on the position x0 (-r ≤ x0 ≤ r) on the x-axis coordinate, passes through the particle W, and the position x1 on the x-axis coordinate and its angle u1, which are separated by a distance l between the center of the particle W and the light receiving part 16b, are calculated. For simplicity, it is assumed that the light emerging from the particle travels the same distance l without considering the distance traveled inside the particle W.

[0034] At this time, if x0 > x1, it indicates that the illumination light H passing through the particle W is converged. If the position x1 at the light receiving part 16b is known from the experimentally obtained image, the distance l can be calculated.

[0035] Therefore, by subtracting the distance L between the surface 16a of the image sensor on which the sample aqueous solution S is dropped and the light receiving part 16b from the distance l, it is possible to determine whether the particle W is in contact with the surface of the image sensor 16a or is floating at a position (l - L) away.

[0036] Also, by using this principle, for example, it is possible to distinguish between particles that have settled and particles that have not settled with the same particle size.

[0037] Thus, according to Example 1, the validity of the measurement by the particle measuring apparatus of the present embodiment was verified using the calculation shown in the above-described ray tracing determinant.

[0038] (Example 2) In Example 2, the experimental verification results of the measurement validity by the particle measuring apparatus of the present embodiment will be described.

[0039] Figure 4 is an image captured when a pure aqueous solution (refractive index n2 = 1.33) containing spherical acrylic standard particles with a radius r = 15 μm and a refractive index n1 = 1.49 was dropped onto an image sensor as a sample aqueous solution.

[0040] Figure 5 is an enlarged image including three types of acrylic standard particles (hereinafter referred to as "particle A", "particle B", and "particle C") that appear in three different ways in the image shown in Figure 4.

[0041] Figure 5(a) shows an enlarged image of particle A and particle B, and Figure 5(b) shows an enlarged image of particle C.

[0042] Figure 6 is a diagram of the transmitted light intensity distribution measured for three types of acrylic standard particles.

[0043] The image shown in Figure 4 indicates that the proportion of particle A among the three types of particles A, B, and C is the highest. Particle A enlarged and shown in Figure 5(a) has settled in the sample aqueous solution S and is in contact with the surface 16a of the image sensor according to the specific gravity of the acrylic particles.

[0044] Particle A is shown as a part having a significantly larger transmitted light intensity compared to the background as shown in Figure 6(a). The length of this part was 17.1 μm as an experimental value as shown in Figure 6(a).

[0045] Also, assuming that the distance l when particle A has settled and is in contact with the surface 16a of the image sensor is l = r = 15 μm, from the above-mentioned ray-tracing determinant, the position x1 = 11.4 μm, and the length of the part where the transmitted light intensity becomes significantly larger compared to the background is calculated as x1 × 2 = 22.8 μm.

[0046] Actually, there is a distance L between the surface 16a of the image sensor and the light-receiving part 16b, and this distance L causes a deviation between the calculated value and the experimental value.

[0047] Therefore, it is estimated from the approximation between the calculated value (22.8 μm) and the experimental value (17.1 μm) that particle A, which has an experimental value of 17.1 μm for the length with a significantly larger transmitted light intensity compared to the background, has settled and is in contact with the surface 16a of the image sensor.

[0048] As shown in FIG. 6(b), for particle B, the experimental value of the length with a transmitted light intensity significantly larger than the background was 9.1 μm.

[0049] Since this value is different from the experimental value (17.1 μm) of particle A, it can be seen that particle B is not in contact with the surface 16a of the image sensor. When particle B is not in contact with the surface 16a of the image sensor, there are two cases for the image formed by the light receiving unit 16b: one where the image is not inverted and one where the image is inverted. Therefore, when the two values of x1, x1 = 9.1 / 2 = 4.55 μm and x1 = -9.1 / 2 = -4.55 μm, were substituted into the above-described ray tracing determinant to calculate the distance l, distances l = 43.43 μm and l = 81.25 μm were obtained.

[0050] Therefore, it is determined that particle B is either at a distance l = 43.43 μm from the light receiving unit 16b or at a distance l = 81.25 μm from it.

[0051] As shown in FIG. 6(b), for particle C, the transmitted light intensity is lower than the background. Therefore, it can be seen that particle C is away from the light receiving unit 16b, x0 < x1, and the light is diverging. When the particle is away from the light receiving unit 16b like particle C and, as shown in FIG. 6(c), the transmitted light intensity is smaller than the background, distance measurement cannot be performed.

[0052] Thus, according to Example 2, the validity of the measurement by the particle measuring device of the present embodiment was verified based on the experimental results.

[0053] (Example 3) In Example 3, an application example of the particle measuring device of the present embodiment for detecting Bacillus spores will be described.

[0054] Figure 7 is an image captured when an aqueous sample solution containing Bacillus spores is dropped onto an image sensor.

[0055] Figure 7(a) is an image obtained from a certain field of view, and Figure 7(b) is an image in which a part of Figure 7(a) is enlarged.

[0056] Bacillus spores have the property of sedimenting. Therefore, in this example, an experiment was conducted assuming that the Bacillus spores would sediment and come into contact with the surface 16a of the image sensor. However, due to the influence of heat convection caused by the heat of the surface 16a of the image sensor, sedimentation was hindered, and a large number of convecting Bacillus spores were observed. For this reason, the sample aqueous solution S was dropped onto the surface 16a of the image sensor, and the images shown in Figures 7(a) and 7(b) were acquired with a cover glass placed thereon.

[0057] Figure 8 is a diagram showing the transmitted light intensity distribution of Bacillus spores extracted from the images shown in Figures 7(a) and 7(b).

[0058] As shown in Figure 8, the experimental value of the length at which the transmitted light intensity of Bacillus spores becomes significantly larger than the background light was 2.9 μm.

[0059] Next, assuming l = r = 0.5 μm and refractive index n1 = 1.52, the position x1 when the Bacillus spores sediment and come into contact with the surface 16a of the image sensor is calculated from the above-described ray tracing determinant, and x1 = 0.4 μm is obtained. The calculated value of the length of the portion where the transmitted light intensity becomes significantly larger than the background is x1 × 2 = 0.8 μm.

[0060] Thus, although there is a deviation between the experimental value (2.9 μm) and the calculated value (0.8 μm), actually, there is a distance L between the surface 16a of the image sensor and the light receiving portion 16b, and this distance L causes the deviation between the experimental value and the calculated value. Also, since the particle size of the Bacillus spores is small, the influence of light diffraction is also a factor contributing to the deviation.

[0061] Thus, according to Example 3, the sedimented Bacillus spores act like a lens to collect the illumination light H, and the light intensity transmitted through the Bacillus spores is significantly greater than the light intensity of the background light. Therefore, it was demonstrated that Bacillus spores can be specifically detected from the transmitted light intensity.

[0062] As described above, according to the particle measuring apparatus of the present embodiment, the sample aqueous solution S is directly dropped onto the surface 16a of the image sensor, and the position of particles such as Bacillus bacteria sedimenting in the sample aqueous solution S can be measured based on the particle size and refractive index of the particles W.

[0063] In particular, according to the particle measuring apparatus of the present embodiment, measurement can be performed only with an image sensor without requiring an optical system such as a microscope. Therefore, not only can it be realized at low cost, but also a complicated mechanism for adjusting the distance of the objective lens is unnecessary, so the configuration can be simplified. Moreover, since a complicated preparation operation such as covering the image sensor with a thinly coated film to detect fungi is unnecessary, particle measurement can be performed easily and in a short time.

[0064] And according to the particle measuring apparatus of the present embodiment, for particles with a known particle size, the position from the surface 16a of the image sensor can also be measured, so it is possible to determine whether the particles are floating or adhering to the surface 16a of the image sensor. As a result, in the case of particles having a sedimentation characteristic, such as Bacillus spores in particular, it is also possible to specifically discriminate from the dye information, morphological information, and transmitted light intensity distribution of the acquired image.

[0065] Furthermore, according to the particle measuring apparatus of the present embodiment, it is also possible to determine at which position on the image sensor the particles with a known particle size are floating or adhering from the transmitted light intensity distribution. As a result, it is also possible to acquire depth-of-field information, which could not be acquired by the conventional imaging method of dropping the sample aqueous solution S onto the surface 16a of the image sensor.

[0066] Although some embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, as well as in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0067] 10 Particle measuring device 12 Light source 16 Imaging unit 16a Surface of image sensor 16b Light receiving unit 18 Particle determination unit 20 Measuring unit 22 Contact determination unit 24 Counting unit 26 Database 28 Machine learning unit G Image H Illumination light S Aqueous sample solution W Particle

Claims

1. A light source that supplies illumination light for illuminating particles in a liquid, An imaging unit that images the illumination light transmitted through the particles, A measurement unit that measures the distance between the particles and the imaging unit based on the transmitted light intensity of the illumination light imaged by the imaging unit, the known particle size, and the refractive index of the particles A particle measurement device comprising the above components.

2. The particle measurement device according to claim 1, further comprising a contact determination unit that determines whether the particles are in contact with the imaging unit based on the distance measured by the measurement unit.

3. The particle measurement device according to claim 1, further comprising a particle determination unit that determines that a portion where the transmitted light intensity is equal to or greater than a preset threshold value in the image imaged by the imaging unit corresponds to the particles.

4. The particle measurement device according to claim 3, wherein the threshold value is determined from the background light intensity of the image.

5. The particle measurement device according to claim 3, further comprising a counting unit that counts the portions determined to correspond to the particles by the particle determination unit.

6. The counting unit in the image, the particle determination unit determines that the portion corresponding to the particles is displayed in a color different from the background, and the portions displayed in different colors are counted to count the portions determined to correspond to the particles. The particle measurement device according to claim 5.

7. A database that accumulates light intensity distribution information of the portions determined to correspond to the particles by the particle determination unit, A machine learning unit that performs image analysis by machine learning on the light intensity distribution information accumulated in the database, and further comprising, When a new image is imaged by the imaging unit, the particle determination unit determines the portion corresponding to the particles in the new image based on the analysis result by the machine learning unit without using the threshold value. The particle measurement device according to claim 3.

8. A particle measurement method implemented by a particle measurement device, wherein the particle measurement device Illuminates the particles in the liquid with illumination light from a light source, Images the illumination light transmitted through the particles by an imaging unit, A particle measurement method that measures the distance between the particles and the imaging unit based on the transmitted light intensity of the imaged illumination light, the known particle size, and the refractive index of the particles.

9. A function of illuminating particles in a liquid with illumination light for the light source, A function of imaging the illumination light that has passed through the particles by an imaging unit, A function of measuring the distance between the particles and the imaging unit based on the transmitted light intensity of the imaged illumination light, the known particle size, and the refractive index of the particles A program for causing a processor to implement.

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