Dispersion liquid concentration measurement system

Abstract

In order to perform accurate concentration measurement even for a dispersion liquid with a low concentration, the dispersion liquid concentration measurement system according to the present invention comprises a container 20 for storing the dispersion liquid, a laser light source 10, an imaging device 30 for capturing an image of the area where laser light 11 is incident on the dispersion liquid to generate an image, and a processing device 40, wherein the processing device 40 determines the concentration of the dispersion liquid containing standard particles by dividing the number of bright spots included in the captured image of the dispersion liquid containing standard particles by the volume of the dispersion liquid determined by multiplying the imaging range by the depth of field, and the settings of the imaging device 30 and / or the laser light source 10 are set so that the determined concentration of the dispersion liquid containing standard particles is within a predetermined range with respect to the actual concentration.

Description

[Technical Field]

[0001] The present invention relates to a system for measuring the concentration of a dispersion liquid. [Background technology]

[0002] Conventionally, it is known to measure the concentration of a dispersion liquid by irradiating the dispersion liquid containing minute substances such as nanoparticles or ultrafine bubbles with light and capturing and analyzing the scattered light. For example, Patent Document 1 describes a method of irradiating a dispersion liquid containing standard particles with laser light and measuring the concentration based on the number of bright spots contained in an image of the scattered light captured by a camera. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2024-061147 Summary of the Invention [Problem to be solved by the invention]

[0004] When measuring concentration based on an image, it is possible to use an objective lens to detect scattered light from minute substances, but this narrows the imaging range of an imaging device such as a camera, and the number of minute substances that can be observed is reduced, particularly when the concentration of the dispersion liquid is low, which creates the problem of not being able to accurately measure the concentration of the dispersion liquid. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems, the system for measuring the concentration of a dispersion liquid according to the present invention includes a container for storing the dispersion liquid, a laser light source, an imaging device for capturing an image of an area where the laser light is incident on the dispersion liquid to generate an image, and a processing device, wherein the processing device determines the concentration of the dispersion liquid containing standard particles by dividing the number of bright spots included in the captured image of the dispersion liquid containing standard particles by the volume of the dispersion liquid determined by multiplying the imaging range by the depth of field, and the imaging device and / or the laser light source are set so that the determined concentration of the dispersion liquid containing standard particles is within a predetermined range with respect to the actual concentration. [Effects of the Invention]

[0006] The present invention solves the above-mentioned problems, and enables more accurate concentration measurement even for low-concentration dispersion liquids by expanding the imaging range of an imaging device. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram showing a dispersion concentration measurement system according to a first embodiment. [Figure 2] FIG. 3 is a flowchart showing a calibration procedure of the dispersion concentration measurement system according to the first embodiment. [Figure 3] 3 is an example of a captured image according to the first embodiment. [Figure 4] 10 is an example of a captured image for explaining the process of counting the number of standard particles according to the first embodiment. [Figure 5] FIG. 10 is a diagram schematically illustrating a captured image according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the components described are merely examples and are not intended to limit the technical scope of the present invention.

[0009] First Embodiment 1 is a diagram showing a dispersion concentration measurement system 100 according to the present invention. The dispersion concentration measurement system 100 includes a laser light source 10, a container 20, an imaging device 30, a processing device 40, and a display device 50.

[0010] A semiconductor laser can be used as the laser light source 10. The laser light source 10 emits laser light 11 into a container 20 containing a dispersion liquid, and outputs light of a wavelength that can cause Rayleigh scattering light to be emitted from the particles contained in the dispersion liquid. For example, a semiconductor laser with a wavelength of 405 nm can be used. As shown in FIG. 1, the irradiation direction of the laser light 11 is the X direction when the XYZ directions are set as shown in FIG. 1. Note that the laser light 11 may be formed into a sheet by adding a lens or the like to the optical path. This widens the irradiation area, thereby expanding the imaging range. For example, the sheet shape can be achieved by using a GRIN lens or a cylindrical lens.

[0011] The container 20 is made of glass, transparent plastic, or the like, and can contain a dispersion liquid. For example, the container 20 can hold up to 500 mL of dispersion liquid, but is not limited to this. The dispersion liquid contains standard particles, such as polystyrene standard particles (manufactured by Thermo Fisher). In an embodiment of the present invention, particles with a particle size of 100 nm are used, but the particle size is not limited to this as long as they are uniform and allow Rayleigh scattered light to be observed. Pure water is used as the dispersion medium, but city water may also be used.

[0012] The imaging device 30 is an imaging device such as a camera equipped with a lens such as a telecentric lens, and captures an image of a predetermined area of ​​the container 20 irradiated with the laser light 11. The imaging device 30 is connected to a processing device 40 and can transmit the captured image to the processing device 40. As shown in FIG. 1, the imaging device 30 is positioned so as to capture scattered light from a direction (Y direction) perpendicular to the X direction, which is the irradiation direction of the laser light 11. The imaging range can be set to, for example, 5 [mm] × 1.4 [mm], but is not limited to this.

[0013] The processing device 40 is, for example, a personal computer, and performs various image processing on the captured image sent from the imaging device 30. It also has various calculation functions, such as calculating density based on the processed image.

[0014] The display device 50 is, for example, a liquid crystal monitor. The display device 50 is connected to the processing device 40 and can display images captured by the imaging device 30, images processed by the processing device 40, etc.

[0015] Next, the calibration procedure of the dispersion concentration measurement system 100 will be described according to the flow in Fig. 2. The dispersion concentration measurement system 100 is calibrated by the calibration procedure in Fig. 2 using standard particles, and can accurately measure the concentration of the dispersion even if the imaging range of the captured image 30 is widened.

[0016] First, a plurality of dispersion liquids with different concentrations are prepared (S210). The dispersion liquids are prepared by diluting a sample containing standard particles with a particle diameter of 100 nm with pure water, and uniformly dispersing the standard particles. The concentrations are, for example, 10 4 , 10 5 , 10 6 , 10 7 , 10 8 , 10 9 At least two types of dispersion liquids are prepared, each of which is placed in a container 20 individually.

[0017] Next, the user selects one of the dispersions prepared in S210 and sets it in a predetermined position. While the laser light source 10 irradiates the container 20 with laser light 11, the imaging device 30 captures an image of the irradiated area, and the processing device 40 acquires the generated image (S220). At this time, the imaging device 30 captures a video, and the processing device 40 acquires a series of images. An example of the captured image is shown in Figure 3. As shown in Figure 3, pixels that receive scattered light due to the presence of standard particles exhibit high brightness values.

[0018] Next, the processing device 40 performs image processing on the acquired captured image to identify standard particles in the captured image (S230). For example, a group of pixels having a brightness value equal to or greater than a predetermined value is treated as a single standard particle, and the standard particles are identified by associating the pixel group with its position information. Furthermore, by associating the pixel group with the distribution of brightness values, size, and features of circular bright and dark regions, the standard particles can be identified with greater accuracy.

[0019] Next, the number of standard particles contained in the captured images is counted (S240). Specifically, this counting involves counting the number of standard particles at a certain time t in consecutive captured images. However, for example, if standard particles overlap in the captured images, they will be counted as one particle, making it impossible to count the number accurately. Therefore, in this counting, at least three captured images, namely, an image captured at a certain time t, an image captured at t+Δt, and an image captured at t−Δt, are used to more accurately count the number of standard particles in the captured images at time t. Note that Δt is preferably 200 [ms], but may be a value within the range of approximately 200±50 [ms].

[0020] 4A shows a captured image 450 at time t, and FIG. 4B shows a captured image 460 at time t+Δt. First, it is determined whether each of the standard particles identified in S230 for the captured image 450 has a one-to-one correspondence with any of the standard particles identified in S230 for the captured image 460. For example, taking into account the movement of the standard particles due to Brownian motion during time Δt, standard particles within a predetermined range from the position of the standard particle at time t and having matching feature amounts are determined to have a one-to-one correspondence.

[0021] For example, the position of a standard particle 411 in an image 450 captured at time t is within a predetermined range relative to a standard particle 412 in an image 460 captured at time t+Δt, and the feature amounts also match, so it is determined that the standard particle 411 and the standard particle 412 have a one-to-one correspondence. On the other hand, the standard particle 410 in the captured image 450 is determined to have a correspondence with the standard particles 420 and 421 in the captured image 460 based on the moving distance and the feature amount, so it is not determined that they have a one-to-one correspondence. In this way, for all standard particles identified in the image captured at time t, it is determined whether or not they have a one-to-one correspondence with the standard particles identified in the image captured at time t+Δt based on the moving distance and the feature amount.

[0022] Similarly, for all standard particles identified in the captured image at time t, it is determined whether there is a one-to-one correspondence between them and the standard particles identified in the captured image at time t-Δt based on the moving distance and feature amount. For example, the standard particle 411 in the captured image 450 at time t is within a predetermined range and the feature amount of the standard particle 413 in the captured image 470 ( FIG. 4(C)) at time t-Δt are the same. Therefore, it is determined that there is a one-to-one correspondence between the standard particle 411 and the standard particle 413. On the other hand, the standard particle 410 in the captured image 450 is determined to have a correspondence with the standard particles 430 and 431 in the captured image 470 based on the moving distance and feature amount. Therefore, it is not determined that there is a one-to-one correspondence between the standard particle 410 and the standard particles 430 and 431 in the captured image 470.

[0023] 4 as an example, the standard particle 410 in the captured image 450 does not have a one-to-one correspondence with the standard particles present in either the captured image 460 at time t+Δt or the captured image 470 at time t−Δt. That is, although the standard particle 410 in the captured image 450 appears to be a single particle, by referring to the captured images before and after it, it can be considered that the standard particles are overlapping. Therefore, in such a case, the number of standard particles is counted as two.

[0024] In this way, standard particles are identified for the image captured at a certain time t, the image captured at t+Δt, and the image captured at t-Δt, and it is determined whether the standard particles identified in the image captured at time t have a one-to-one relationship with the standard particles identified in the image captured at t+Δt and the image captured at t-Δt, such that the feature amounts are within a predetermined range and match. If there is no one-to-one relationship between the image captured at t+Δt and the image captured at t-Δt, it is assumed that there is overlap of standard particles, and the number of standard particles included in the image captured at time t is calculated by adding the number of particles that do not have a one-to-one relationship to the number of identified standard particles.

[0025] In the embodiment of the present invention, ±Δt at equal intervals before and after are processed, but it is also possible to use an image captured at a certain time t as the starting point and images captured before and after that.

[0026] If the entire imaging area is treated as the target of processing, standard particles at the edge may be affected by Brownian motion as they move in and out of the imaging area. Therefore, it is possible to count only bright spots within an area shifted inward by several pixels to the left, right, top, or bottom, rather than the entire area of ​​the captured image.

[0027] Next, in S250, the concentration of the dispersion liquid is calculated. The concentration of the dispersion liquid is found by dividing the number of standard particles contained in the captured image at time t counted in S240 by the volume of the dispersion liquid found by multiplying the area of ​​the imaging range of the imaging device 30 by the depth of field of the imaging device 30. The area of ​​the imaging range is found from the measured distance from the imaging device 30 to the imaging target (the area inside the container 20 that is irradiated with the laser light 11) and the angle of view. For example, if the depth of field of the imaging device 30 is 44 [μm], the imaging range is set to 5 [mm] × 1.4 [mm], and therefore the found volume of the dispersion liquid is 0.308 mm 3 This becomes:

[0028] Next, in S260, it is determined whether the concentration of the dispersion calculated in S250 is within a predetermined range (appropriate concentration) with respect to the actual concentration of the dispersion prepared in S210. For example, the predetermined range can be set to ±10%. If it is the appropriate concentration (S260; YES), proceed to S280; if it is not the appropriate concentration (S260; NO), proceed to S270.

[0029] In S270, the device settings are changed. The device settings are at least one of the gain of the imaging device 30, the exposure time, and the output value of the laser light source 10, but other settings may also be used. Next, the process returns to S220, and an image is captured based on the changed device settings. After performing the same processes in S230 to S250, it is determined whether the density is appropriate (S260). In other words, the device settings are repeatedly changed until the density is appropriate. Note that even if the density is appropriate (S260; YES), the process may proceed to S270 and the device settings may be changed in order to determine the range of the device settings.

[0030] Next, in S280, the device settings are determined. That is, the device settings that allow the captured image to appropriately represent the concentration of the dispersion liquid are set as the device settings for the dispersion liquid of that concentration. Note that if the device settings have been changed several times in S270 and there is a range of settings that can accommodate the concentration, that range may be set as the device settings.

[0031] Next, in S290, it is determined whether the device settings have been determined for all dispersions of different concentrations prepared in S210, as was done in S280 after S220 to S270 have been performed. If there are dispersions that have not been processed (S290; NO), the process returns to S220 and performs each process on the dispersions that have not been processed. If there are no dispersions that have not been processed (S290; YES), the process proceeds to S295.

[0032] In S295, the apparatus settings determined in S280 for each dispersion liquid of a different concentration are referenced, and apparatus settings that satisfy all of these conditions are determined. For example, assume that the apparatus settings determined for the dispersion liquid of concentration A are (imaging device 30: exposure time 10-20 [ms], gain 10-15 [dB], laser light source 10: output 1.0 [W]) and the apparatus settings determined for the dispersion liquid of concentration B are (imaging device 30: exposure time 10-25 [ms], gain 15 [dB], laser light source 10: output 1.0 [W]). In this case, in S295, the apparatus settings corresponding to all concentrations can be determined as those that satisfy the apparatus settings for concentrations A and B, such as (imaging device 30: exposure time 15 [ms], gain 15 [dB], laser light source 10: output 1.0 [W]).

[0033] As described above, proper calibration of the dispersion liquid concentration measurement system 100 enables accurate concentration measurement even when the imaging range is expanded. Thus, using multiple dispersion liquids with different concentrations, device settings are required to accommodate dispersion liquids of different concentrations. For example, in images captured at high concentrations, if the device settings are inappropriate, the bright spots may become large and counting may not be possible. Therefore, device settings that minimize overlapping of bright spots are preferable, but if these settings are used, there is a risk that the error will be large when determining the concentration in images captured at low concentrations without capturing the dispersed light. Therefore, calibration according to an embodiment of the present invention is performed to set the device settings so that the concentration can be measured appropriately for dispersion liquids of different concentrations.

[0034] <Second embodiment> In the second embodiment, when a captured image contains bright spots due to particles other than standard particles, these can be excluded to identify the standard particles.

[0035] A dispersion concentration measurement system 300 according to the second embodiment includes, in addition to the configuration of the dispersion concentration measurement system 100 shown in FIG. 1, a polarizer 310 and a half-wave plate 330 attached to a rotation mechanism 320 between the laser device 10 and the container 20 (not shown). Furthermore, a lens or the like may be added to form light into a sheet and irradiate the container 20. The polarizer 310 is used to obtain linearly polarized light with a higher extinction ratio. The half-wave plate 330 is used to rotate the vibration axis of the linearly polarized light. The rotation mechanism 320 rotates the half-wave plate 330 by 45 degrees.

[0036] Next, a description will be given of a procedure for calibrating the dispersion liquid concentration measurement system 300. This calibration procedure follows the calibration procedure shown in FIG.

[0037] First, in S210, a plurality of dispersion liquids containing standard particles and having different concentrations are prepared, which is the same as in the first embodiment. 4 , 10 5 , 10 6 , 10 7 , 10 8 , 10 9 The dispersion medium contains impurities, for example, city water.

[0038] Next, in S220, captured images are acquired, including multiple captured images with horizontally polarized incident light and multiple captured images with vertically polarized incident light. Specifically, captured images are acquired while vertically polarized laser light is irradiated onto container 20, and then the rotation mechanism 320 is used to switch to vertically polarized light incidence, and captured images are acquired while horizontally polarized laser light is irradiated. Note that this order may be reversed.

[0039] Fig. 5 shows examples of captured images according to the second embodiment. In Fig. 5, circles indicate areas with high brightness. Fig. 5(A) shows an image 510 captured with vertically polarized incident light, and Fig. 5(B) shows an image 520 captured with horizontally polarized incident light.

[0040] Here, Equation 1 represents the scattered light intensity I1 due to Rayleigh scattering for vertically polarized incident light, and Equation 2 represents the scattered light intensity I2 due to Rayleigh scattering for horizontally polarized incident light. In Equations 1 and 2, I0 represents instrument constants such as gain, exposure time, and laser output value, a represents the particle diameter, k represents the wavenumber, r represents the observation distance from the particle to the imaging device, m represents the relative refractive index between the particle and the solvent, and θ represents the scattering angle.

[0041]

number

[0042]

number

[0043] As can be seen from Equation 2, when θ = 90 degrees and the incident polarization state is horizontal, the scattered light intensity due to Rayleigh scattering is 0. Therefore, the bright spots present in the image captured with horizontally polarized incident light are due to scattered light caused by Mie scattering, etc., and since the particle size of these particles is significantly larger than that of standard particles, it is assumed that foreign matter has been mixed in.

[0044] In the next step S230, this feature is used to identify standard particles by excluding foreign particles from the bright spots. First, bright spots are identified in the image 510 captured when horizontally polarized incident light is used. Using FIG. 5B as an example, bright spots 502 and 503 are identified based on their luminance values ​​and feature amounts. For these, their position information and feature amounts are associated and stored. Since the bright spots in the captured image 510 are due to Mie scattering, they are assumed to be due to foreign particles rather than standard particles.

[0045] Next, the captured image 500 captured with vertically polarized incident light is referenced. Then, bright spots 502 and 503 in the captured image 500 are identified and removed from the image based on the position information and feature values. The result of this processing is the "new" captured image 520 shown in FIG. 5(C). In this way, even if bright spots due to foreign matter are included in the captured image, if they are due to Mie scattering, they can be removed from the captured image 500 captured with vertically polarized incident light using the captured image 510 captured with horizontally polarized incident light. Then, using the "new" captured image 520, a standard particle 501 exhibiting scattered light due to Rayleigh scattering can be identified. Note that the "new" captured image 520 is generated based on at least the images captured with vertically polarized incident light at time t, time t-Δt, and time t+Δt. Note that, as with the first embodiment, captured images just before and after time t may be used, and do not have to be at equal intervals.

[0046] The subsequent processing is the same as in the first embodiment, and the number of standard particles is counted using the "new" captured image. Then, in the same manner, the apparatus settings are calculated for each different concentration, and the final apparatus settings that can accommodate each concentration within the range of the apparatus settings are determined.

[0047] <Modification> The concentration of an ultra-fine bubble dispersion can also be accurately measured using the calibrated dispersion concentration measurement system 100 or 300. For example, an ultra-fine bubble dispersion generated by passing pure water through a Venturi nozzle is poured into a container 20, an image is taken, and the number of scattered light rays (bright spots on the image) caused by the ultra-fine bubbles is counted to calculate the concentration in the same way as in S250. Here, the count can be accurately calculated by correcting the count number using successive captured images as in S240.

[0048] The procedure for measuring the concentration of an ultra-fine bubble dispersion will now be described. The dispersion concentration measurement system is the same as that in the first embodiment, and calibration is performed using standard particles according to the procedure in Figure 2. Here, an ultra-fine bubble dispersion using city water as the medium is used.

[0049] When city water is used as the medium, impurities are contained, so first, only city water is placed in the container 20, and the scattered light from the impurities is counted using an image of the area irradiated with the laser light 11. The counting can be performed in the same manner as in the first embodiment. Next, the ultra-fine bubble dispersion is placed in the container 20, the laser light 11 is irradiated, an image is taken, and the scattered light is counted. The counting can be performed in the same manner as in the first embodiment.

[0050] The bright spots at this time will include both impurities contained in the dispersion and ultrafine bubbles. Therefore, the number of ultrafine bubbles can be regarded as the number of ultrafine bubbles obtained by subtracting the previously calculated number of counts when city water was used from this count, and by dividing this number by the volume of the ultrafine bubble dispersion calculated by multiplying the imaging range by the depth of field, the concentration of the ultrafine bubble dispersion excluding impurities can be calculated even when city water is used. [Explanation of symbols]

[0051] 10 Laser light source 20 containers 30 Imaging device 40 Processing equipment 50 Display device 100 Dispersion liquid concentration measurement system 300 Dispersion Liquid Concentration Measurement System

Claims

1. a container for containing the dispersion; A laser light source; an imaging device that captures an image of a region where the laser light from the laser light source is incident on the dispersion liquid and generates a captured image; a processing device; Equipped with the processing device calculates the concentration of the dispersion liquid containing the standard particles by dividing the number of bright points included in the captured image of the dispersion liquid containing the standard particles by the volume of the dispersion liquid containing the standard particles, which is calculated by multiplying the imaging range of the imaging device by the depth of field; the imaging device and / or the laser light source are set so that the determined concentration of the dispersion liquid containing the standard particles is within a predetermined range with respect to the actual concentration of the dispersion liquid containing the standard particles. Dispersion liquid concentration measurement system.

2. The processing device determines whether or not there is overlap of the bright spots in the captured image at a certain time by comparing them with bright spots in the captured images before and after the time, and if it determines that there is overlap, increases the number of bright spots in the captured image at the certain time to determine the concentration of the dispersion liquid.

3. The dispersion concentration measurement system according to claim 1 , wherein the settings are a gain of the imaging device, an exposure time, and an output value of the laser light source.

4. The dispersion concentration measurement system according to claim 2 , wherein the processing device performs the comparison on only the bright points that are within a predetermined range of the captured image.

5. The dispersion concentration measurement system according to claim 1 , wherein the laser light is in the form of a sheet.

6. a container for containing a dispersion liquid containing particles; a laser light source that emits horizontally polarized incident light and vertically polarized incident light; an imaging device that is installed in a direction perpendicular to the direction of incidence and that captures images of regions where the horizontally polarized incident light and the vertically polarized incident light are incident on the dispersion liquid, respectively, to generate captured images; a processing device; Equipped with the processing device identifies bright spots in the captured image of the horizontally polarized incident light, generates a new image by removing bright spots corresponding to the identified bright spots from the captured image of the vertically polarized incident light, and calculates the concentration of the dispersion by dividing the number of bright spots included in the new image by the volume of the dispersion calculated by multiplying the imaging range of the imaging device by the depth of field. Dispersion liquid concentration measurement system.

7. The processing device determines whether or not there is overlap of the bright spots in the captured image at a certain time by comparing them with bright spots in the captured images before and after the time, and if it determines that there is overlap, increases the number of bright spots in the captured image at the certain time to determine the concentration of the dispersion liquid.

8. 8. The dispersion concentration measurement system according to claim 6, wherein the imaging device and / or the laser light source are set so that the determined concentration is within a predetermined range with respect to the actual concentration of the dispersion.

9. The dispersion concentration measurement system according to claim 8 , wherein the settings are a gain of the imaging device, an exposure time, and an output value of the laser light source.

10. A dispersion liquid concentration measurement system as described in Claim 6, wherein the laser light from the laser light source is sheet-shaped.

11. a container for storing a dispersion liquid containing ultrafine bubbles; A laser light source; an imaging device that captures an image of a region where the laser light from the laser light source is incident on the dispersion liquid and generates a captured image; a processing device; Equipped with the processing device calculates the concentration of the dispersion by dividing the number of bright points included in the captured image by the volume of the dispersion calculated by multiplying the imaging range of the imaging device by the depth of field. Dispersion liquid concentration measurement system.

12. 12. The dispersion concentration measurement system according to claim 11, wherein the imaging device and / or the laser light source are set so that the concentration determined for the dispersion containing the standard particles is within a predetermined range with respect to the actual concentration of the dispersion containing the standard particles.

13. The processing device determines whether or not there is overlap of the bright spots in the captured image at a certain time by comparing them with bright spots in the captured images before and after the time, and if it determines that there is overlap, increases the number of bright spots in the captured image at the certain time to determine the concentration of the dispersion liquid.

Images