Particle observation system and cell unit

Abstract

In a particle observation system that irradiates a dispersion with a laser and observes particles using scattered light, a cell that is easy to handle and suitable for continuous observation when observing multiple dispersions of different types is required. The particle observation system of the present invention therefore includes a cell unit, a laser light source, and an imaging device, wherein the cell unit includes a cell with an opening that contains the dispersion, an observation window that covers the opening, and a holder that fixes the cell and the observation window in predetermined positions, the laser light source outputs laser light toward the cell unit, and the imaging device captures an image of the area where the laser light is incident on the dispersion to generate a captured image.

Description

[Technical Field]

[0001] The present invention relates to a particle observation system and a cell unit thereof that observes particles by capturing images of scattered light from particles in a dispersion liquid by irradiating a cell unit containing the dispersion liquid with laser light. [Background technology]

[0002] It is known that particles can be observed by irradiating a dispersion with laser light and capturing an image of the scattered light from the particles in the dispersion. It is also known that the particle concentration and particle diameter in a dispersion can be determined based on the captured image. For example, Patent Document 1 describes a method of irradiating a container containing nanobubble water with a laser to capture an image, and then calculating the concentration of the nanobubble water based on the average brightness. Furthermore, for example, Patent Document 2 describes a method of calculating particle diameter based on the displacement of particles due to Brownian motion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-030579 [Patent Document 2] Japanese Patent Application Publication No. 2020-109419 Summary of the Invention [Problem to be solved by the invention]

[0004] In particle observation systems that use a laser to irradiate a cell or container containing a dispersion liquid for observation, when observing multiple different types of dispersion liquid continuously, cells or containers that are easy to handle and suitable for continuous observation are required.

[0005] Furthermore, if there is a difference in temperature between the dispersion liquid and the ambient temperature around the cell or container, convection will occur in the dispersion liquid, making it difficult to capture the Brownian motion of particles in the captured image. Therefore, there is a need for a particle observation system that can suppress convection when convection is not desired. [Means for solving the problem]

[0006] In order to solve the above problem, the particle observation system of the present invention comprises a cell unit, a laser light source, and an imaging device, wherein the cell unit comprises a cell having an opening and containing a dispersion liquid, an observation window covering the opening, and a holder for fixing the cell and the observation window in a predetermined position, the laser light source outputs laser light toward the cell unit, and the imaging device captures an image of the area where the laser light is incident on the dispersion liquid to generate an image. [Effects of the Invention]

[0007] By using the cell unit according to the present invention, it is possible to easily replace the cell, allowing for successive observation of different dispersions, and it is also possible to easily control the temperature of the dispersions and suppress convection. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a particle observation system according to an embodiment of the present invention. [Figure 2] 1 is an external view of each member constituting a cell unit according to an embodiment of the present invention. [Figure 3] FIG. 2 is a diagram showing a state in which a cell is incorporated into a holder according to an embodiment of the present invention. [Figure 4] 1 is a diagram showing a state in which an observation window is incorporated into a holder according to an embodiment of the present invention. FIG. [Figure 5] 1 is an external view showing a holder according to an embodiment of the present invention. [Figure 6] FIG. 2 is a cross-sectional view of a cell unit according to an embodiment of the present invention. [Figure 7] FIG. 2 is a diagram for explaining an imaging range according to an embodiment of the present invention. [Figure 8] FIG. 10 is a diagram showing an example of a captured image of a dispersion liquid. DETAILED DESCRIPTION OF THE INVENTION

[0009] 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.

[0010] First Embodiment 1 is a diagram showing a particle observation system 100 according to the first embodiment. The particle observation system 100 includes a laser light source 10, a cell unit 20, an imaging device 30, an image processing device 40, and a display device 50.

[0011] 1, the imaging device 30 is directed toward the observation window 210 of the cell unit 20 that contains the dispersion liquid to be observed, and captures an image from a direction perpendicular to the X direction, which is the irradiation direction of the laser light 11 (Z direction). The imaging range of the imaging device 30 can be set to, for example, 5 mm × 1.4 mm, but is not limited to this. The imaging range can be calculated using the distance to the object to be imaged, the focal length of the lens, and the sensor size.

[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 by setting an imaging range within the irradiation area where the cell unit 20 is irradiated with the laser light 11. The imaging device 30 generates captured images by continuously capturing images of the imaging area at predetermined intervals. The imaging device 30 is connected to an image processing device 40, and can transmit the captured images to the image processing device 40. Figure 8 shows an example of an image captured by the imaging device 30. As shown in Figure 8, scattered light from particles appears as bright spots. Note that Figure 8 shows an image of pure water containing ultrafine bubbles (UFB) with a particle size of approximately 100 nm.

[0013] The display device 50 is, for example, a liquid crystal monitor, and is connected to the image processing device 40 so as to be able to display images captured by the imaging device 30, images processed by the image processing device 40, and the like.

[0014] The laser light source 10 is a semiconductor laser that outputs laser light 11 toward the cell unit 20 containing the dispersion liquid, emitting light with a wavelength of 405 nm that causes Rayleigh scattering light to be emitted from the particles and ultrafine bubbles contained in the dispersion liquid. The irradiation direction of the laser light 11 is the X direction, when the bottom surface is set as the XY plane and the XYZ directions are set as shown in Figure 1.

[0015] To expand the imaging range, a lens or the like may be added to the optical path to form the laser beam 11 into a sheet, thereby expanding the irradiation range. For example, the laser beam 11 can be formed into a sheet by using a GRIN lens or a cylindrical lens. When a GRIN lens is used, the laser beam 11 can be formed into a sheet by reducing the laser spot diameter in the Z-axis direction shown in FIG. 1 with a first GRIN lens and expanding the laser spot diameter in the Y-axis direction with a second GRIN lens. After forming the laser beam 11 into a sheet, an aperture may be placed to cut off portions of the laser with weak intensity, or the laser beam may be transmitted through a diffraction grating to uniformly shape the beam intensity distribution before entering the cell unit 20. Preferably, in the particle observation system 100 according to the present invention, the irradiation range is expanded in the Y direction.

[0016] The cell unit 20 is composed of an observation window 210, a cell 220, and a holder 230. The cell 220 filled with a dispersion liquid is placed in the holder 230, and the observation window 210 covers the cell 220. Figure 2 is an external view of the observation window 210, the cell 220, and the holder 230 that make up the cell unit 20.

[0017] The cell 220 is made of quartz glass, transparent plastic, or the like, and contains the dispersion liquid to be observed. For example, it has a three-dimensional shape of 3 mm x 3 mm x 5 mm, and has an opening on the top surface. The thickness may be approximately 0.7 mm, but is not limited to this. By making the cell 220 out of quartz glass, it is possible to contain an alkaline dispersion liquid. As shown in the external view of FIG. 3, the cell 220 is incorporated into a holder 230. Note that the cell 220 is shaded in FIG. 3.

[0018] A metal film such as platinum or copper may be vapor-deposited on the bottom surface of cell 220. These metals, with a film thickness of about 50 to 100 nm, have a reflectivity of 60% or less for light with a wavelength of 405 nm, which is the wavelength of laser light 11, and can suppress reflection of scattered light from the particles at the bottom surface to some extent, while their thermal conductivity can improve the responsiveness of temperature control of the dispersion liquid in cell 220 when controlling the temperature of holder 230.

[0019] Observation window 210 is made of transparent quartz glass or the like, and is attached to the upper surface of holder 230 so as to completely cover the opening of cell 220 (see FIG. 4). Observation window 210 has a planar shape that is larger than the horizontal and vertical widths of cell 220, for example, 5 mm × 5 mm and 0.7 mm thick. The XYZ directions shown in FIG. 4 correspond to the XYZ directions shown in FIG. 1, and the upper surface of observation window 210 is perpendicular to the imaging direction (-Z direction) of imaging device 30.

[0020] When observing particles in a dispersion liquid using the cell unit 20, first, the cell 220 filled with the dispersion liquid is assembled into the holder 230 (see FIG. 3), and then the observation window 210 is assembled so as to cover the cell 220 (see FIG. 4). Alternatively, the cell 220 may be sufficiently filled with the dispersion liquid, and the observation window 210 may be brought into close contact with the opening of the cell 220 by the surface tension of the dispersion liquid, and then these may be assembled into the holder 230 as a single unit.

[0021] Holder 230 is made of metal or resin, and as shown in Fig. 5, has a laser light input section 231, a laser light output section 232, a cell housing section 233, and an observation window housing section 234. Laser light input section 231 and laser light output section 232 are openings, which are passage areas provided to allow laser light 11 input in the X direction to pass through. Laser light input section 231 and laser light output section 232 are preferably made slightly larger than the spot size of laser light 11, thereby preventing light other than laser light 11 from entering cell 220.

[0022] The cell storage section 233 is a recess provided inside the holder 230, and is the same size as the cell 220, allowing the cell 220 to be stored within the holder 230. The observation window storage section 234 is a recess provided on the upper surface of the holder 230, and is the same size as the observation window 210. The observation window storage section 234 is attached to the upper surface of the holder 230 while contacting the observation window 210 at the edge of the upper surface of the cell 220. In this manner, the holder 230 fixes the observation window 210 and the cell 220 in predetermined positions. The corners of the cell storage section 233 and the observation window storage section 234 may be chamfered. This allows the dispersion liquid to flow into the chamfered portion even if it overflows when the observation window 210 is covered with the cell 220, thereby preventing the observation window 210 from floating, etc.

[0023] FIG. 6 is a cross-sectional view taken along dashed line A in FIG. 4. In FIG. 6, the cross sections of the observation window 210 and the cell 220 are indicated by diagonal lines. The cross section of the holder 230 is also indicated by diagonal lines. The laser light input unit 231 and the laser light output unit 232 are open spaces formed to ensure the optical path of the laser light 11. As shown in FIG. 6, the imaging device 30 is installed above the observation window 210 and captures an image by setting an imaging range within the irradiation range of the laser light 11 within the cell 220 through the observation window 210. The imaging range is set to at least fit within the irradiation range of the laser light 11. This imaging range will be described with reference to FIG. 7. Here, FIG. 7 is a cross-sectional view along the XY plane showing an imaging range 710 set within the irradiation range of the laser light 11 when the laser light 11 shown in FIG. 1 passes through the cell 220 in the cell unit 20.

[0024] As shown in FIG. 7, the height M of the imaging range 710 in the direction perpendicular to the traveling direction of the laser beam 11 (the X direction in FIG. 1) (the Y direction in FIG. 1) is set to be equal to or less than half the width L of the laser beam 11. That is, M ≦ 1 / 2 × L. The center of the imaging range 710 is set to be on the laser optical axis 720. This is because, due to the characteristics of laser light, the intensity in the Y direction attenuates with increasing distance from the optical axis direction. If this setting is not made, the brightness value of the scattered light in the captured image may vary between the edges and the center. Note that by setting the laser optical axis 720 to pass through the center of the cell 220, the influence of convection is small near the center of the cell 220, so even if convection does occur, its influence can be reduced.

[0025] A temperature-controllable member such as a Peltier element is connected to the holder 230 (not shown). When this temperature control member absorbs or generates heat, the temperature of the holder 230 changes, and this thermal effect extends to the cells 220 in contact with the holder 230. As a result, the temperature of the dispersion liquid in the cells 220 also changes. By controlling the temperature control member to maintain the temperature of the dispersion liquid at the same temperature as the surroundings of the holder 230, it is possible to suppress the occurrence of convection in the dispersion liquid. Note that, if it is necessary to intentionally cause convection, the temperature of the dispersion liquid can be controlled to be different from the surroundings of the holder 230.

[0026] The image processing device 40 is, for example, a PC (personal computer), and can perform various image processing and calculation processing on the captured image sent from the imaging device 30 to determine the number concentration of the dispersion and the particle diameter of the particles contained in the dispersion. For example, in the case of the number concentration, the number of bright spots, which are scattered light from particles contained in the entire captured image, is counted, and the number of bright spots is divided by the volume of the dispersion determined from the captured image to determine the number concentration of the dispersion. If the imaging range of the imaging device 30 (for example, the imaging range 710 in FIG. 7) is set to 5 [mm] × 1.4 [mm] as described above, and the depth of field of the imaging device 30 is 44 [μm], then the volume of the dispersion is calculated as 5 [mm] × 1.4 [mm] × 44 [μm] = 0.308 mm 3 is the volume of the dispersion liquid obtained from the captured image.

[0027] The image processing device 40 can also calculate particle diameters based on captured images. Specifically, it can continuously capture particle motions based on multiple captured images and calculate particle diameters individually from the Brownian motion of the particles using the Stokes-Einstein equation.

[0028] As explained above, the observation window 210 and the cell 220 can be freely attached to the holder 230 through which the laser light 11 passes. Therefore, after observing a certain dispersion, the observation window 210 and the cell 220 can be removed from the holder 230, and the cell 220 can be filled with another dispersion and set back in the holder 230 together with the observation window 210, thereby enabling continuous observation.

[0029] Furthermore, by heating or absorbing heat from the holder 230 and adjusting the temperature of the dispersion liquid in the cell 220, convection can be suppressed.

[0030] <Second embodiment> The particle observation system according to the second embodiment has the same configuration as the particle observation system 100 shown in Fig. 1, but differs in that some elements are added to the cell unit 20. In the second embodiment, the temperature of the dispersion liquid can be kept more constant by being less susceptible to the influence of the atmosphere.

[0031] The additional elements are a second holder made of metal or the like that can accommodate the cell unit 20, three second window members attached to the second holder, and a vacuum device. The configuration of the cell unit 20 is the same as in the first embodiment and accommodates a dispersion liquid. The second holder is, for example, a three-dimensional container that has an imaging opening, two laser passage openings, and a hollow portion, and accommodates the cell unit 20 in the hollow portion. The hollow portion is slightly larger than the cell unit 20. An imaging opening is provided on the top surface of the second holder, a laser passage opening is provided on the side, and another laser passage opening is provided on the opposite surface.

[0032] After the cell unit 20 is housed, the opening is covered with a second window member. The second window member is made of metal and two pieces of glass, and has a multi-layer structure in which the two pieces of glass are fixed with the metal and there is a vacuum between the pieces of glass. An imaging device 30 is installed above the imaging opening (in the Z direction shown in FIG. 1), and the dispersion in the cell 220 can be observed through the second window member and the observation window 210.

[0033] Second window members are similarly attached to the two laser passage openings. Laser light 11 enters through one of the second window members, passes through the cell unit 20, and exits through the other second window member. As the laser light 11 passes through the cell unit 220, it is irradiated onto the dispersion liquid, allowing particles to be observed by the imaging device 30. In this way, the cell unit 20 is housed in the hollow portion and enclosed by the second holder, with the three openings of the second holder covered by the second window members.

[0034] The vacuum device is used to evacuate the hollow space. For actual observation, the cell unit 20 is assembled into the second holder, and the three second window members are then assembled into the second holder, after which the hollow space is evacuated. After the hollow space is evacuated, the temperature of the dispersion liquid in the cell 220 can be adjusted to a predetermined temperature using the temperature control member connected to the cell unit 20. Because the area around the cell unit 20 is evacuated, the temperature influence on the dispersion liquid in the cell 220 is limited to the temperature control member, thereby suppressing convection. When observing a highly viscous dispersion liquid, the temperature of the dispersion liquid can be increased to increase particle movement and make observation easier, while convection can also be suppressed by blocking the temperature influence outside the second holder. [Explanation of symbols]

[0035] 10 Laser light source 20 cell units 30 Imaging device 40 Image processing device 50 Display device 100 Particle Observation System 210 Observation window 220 cells 230 Holder

Claims

1. a cell unit, a laser light source that outputs laser light toward the cell unit, and an imaging device; the cell unit includes a cell having an opening at an upper portion and containing a dispersion liquid, an observation window covering the opening, and a holder for fixing the cell and the observation window in predetermined positions; the holder has two open spaces for passing the laser light, and is in contact with a surface other than the opening when the cell is housed therein; The imaging device captures an image of a region where the laser light is incident on the dispersion liquid through the observation window to generate a captured image.

2. 2. The particle observation system according to claim 1, wherein a metal having a reflectance of 60% or less with respect to the wavelength of the laser light is formed on the bottom surface of the cell.

3. The particle observation system according to claim 1 or 2, wherein a temperature-controllable member is connected to the holder.

4. 4. The particle observation system according to claim 3, wherein the temperature of the dispersion liquid is controlled to be the same as the temperature of the atmosphere around the cell unit, thereby suppressing convection in the dispersion liquid.

5. 3. The particle observation system according to claim 1, wherein the imaging range in the vertical direction of the imaging device is equal to or smaller than half the width of the laser light, and the center of the imaging range is on the optical axis of the laser light.

6. 3. The particle observation system according to claim 1, further comprising a processing device that calculates a particle concentration by dividing the number of bright points included in the captured image by the volume of the dispersion liquid calculated by multiplying the area of ​​an imaging region of the imaging device by a depth of field.

7. a second holder that encases the cell unit; 3. The particle observation system according to claim 1, wherein the second holder is provided with a window member that allows the laser light to enter the dispersion liquid and a window member that enables the imaging device to capture the image, and the inside of the second holder is vacuum.

8. A cell unit used in a particle observation system that captures an image of a dispersion liquid irradiated with laser light using an imaging device, a cell having an opening at the top and containing a dispersion; an observation window covering the opening; a holder for fixing the cell and the observation window in place; the holder has two open spaces for passing the laser light, and is in contact with a surface other than the opening when the cell is housed therein; the imaging device captures an image of a region where the laser light is incident on the dispersion liquid through the observation window to generate a captured image. Cell unit.

9. 9. The cell unit according to claim 8, wherein a metal having a reflectance of 60% or less with respect to the wavelength of the laser light is formed on the bottom surface of the cell.

10. The cell unit according to claim 8 or 9, wherein a temperature-controllable member is connected to the holder.

Images