Foam measuring device and foam measuring method

Abstract

The film thickness and size of the foam are measured simultaneously. [Solution] The foam measurement device 1 comprises a light source device 2 that outputs measurement light containing multiple light components having different wavelengths, an optical fiber probe 3 that receives measurement light from the light source device 2 and is capable of moving relative to the foam 9, an optical measurement device 5 that obtains optical information regarding the reflected light obtained as a result of inputting the measurement light to the optical fiber probe 3, and a computer 6 that uses the optical information to obtain foam information including the film thickness 9T and the size 9Z of the foam 9. The optical fiber probe 3 includes a fiber tip 32 that is inserted into the foam 9. The fiber tip 32 includes an optical input / output surface 32s whose angle with respect to the optical axis A3 of the optical fiber probe 3 is 60 degrees or more and 90 degrees or less.

Description

[Technical Field]

[0001] The present invention relates to a foam measuring device and a foam measuring method. [Background Art]

[0002] At the interface between a liquid phase and a gas phase, foam including so-called bubbles and air bubbles is formed. Foam is a form of fluid, and is utilized in various fields such as fire extinguishing technology, food, and beauty and hygiene. Patent Document 1 discloses a bubble measuring method using an optical fiber probe. In this measuring method, the translation velocity of bubbles, interface velocity, bubble chord length, and bubble volume fraction are targeted for measurement. Patent Document 2 discloses a technique for simultaneously measuring the thickness of a thin liquid film and the velocity of a liquid film using an optical fiber probe sensor. [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent No. 3018178 [Patent Document 2] Japanese Unexamined Patent Publication No. 2022-77303 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] Several parameters can be cited as numerical values for evaluating foam. The thickness of the film forming the foam is one example of a numerical value for evaluating foam. Additionally, the size of the foam is another numerical value for evaluating foam. Since the shape of foam is not constant, the size of foam can also be defined as the distance from one liquid film to another liquid film.

[0005] To date, one known technique for measuring the thickness of the film forming foam is a method using optical interference. Similarly, one known technique for measuring foam size is a method that utilizes changes in light intensity based on changes in refractive index at the optical input / output surface of an optical fiber probe. However, these techniques measure film thickness and foam size individually; in other words, they could not measure film thickness and foam size simultaneously.

[0006] Therefore, the present invention provides a foam measuring device and foam measuring method that can simultaneously measure the film thickness and size of foam. [Means for solving the problem]

[0007] A foam measuring device according to one embodiment of the present invention comprises: a light source unit that outputs measurement light containing multiple optical components having different wavelengths; an optical fiber probe that receives the measurement light from the light source unit and is capable of relative movement with respect to the foam to be measured; an optical measurement unit that obtains optical information regarding the reflected light obtained as a result of inputting the measurement light to the optical fiber probe; and a processing unit that uses the optical information to obtain foam information including the film thickness and size of the foam to be measured. The optical fiber probe includes a fiber tip that is inserted into the foam to be measured. The fiber tip includes an optical input / output surface at an angle of 60 degrees or more and 90 degrees or less with respect to the optical axis of the optical fiber probe. This foam measuring device is equipped with an optical fiber probe that includes an optical input / output surface with an angle between 60 and 90 degrees. This optical fiber probe allows for both obtaining reflected light from the optical input / output surface, which can be used to calculate the size of the foam being measured, and obtaining emitted and reflected light from the optical input / output surface, which can be used to calculate the film thickness of the foam being measured. Therefore, the foam measuring device can simultaneously measure both the film thickness and size of the foam.

[0008] In the foam measuring device described above, the tip of the fiber may have an apex angle of 3 degrees or more and 10 degrees or less. This configuration makes it possible to increase the intensity of the light emitted from the optical input / output surface.

[0009] In the foam measurement device described above, the angle of the optical input / output surface with respect to the optical axis of the optical fiber probe may be between 65 degrees and 75 degrees. This configuration suppresses the reflection of measurement light at the optical input / output surface and increases the light intensity of the measurement light emitted from the optical input / output surface and the reflected light incident from the optical input / output surface.

[0010] Another embodiment of the present invention is a foam measurement method comprising the steps of: obtaining optical information based on reflected light obtained as a result of applying measurement light containing multiple optical components of different wavelengths to an optical fiber probe during a period in which relative movement of the optical fiber probe with respect to the foam to be measured occurs; and obtaining foam information including the film thickness and size of the foam to be measured using the optical information. The step of obtaining information includes the step of acquiring an optical intensity history, which is the change in the optical intensity of the reflected light over time, and the step of acquiring an optical spectrum showing the distribution of optical intensity for each wavelength in the reflected light. The step of obtaining foam information includes the step of obtaining the size of the foam to be measured using the optical intensity history, and the step of obtaining the film thickness of the foam to be measured using the optical spectrum. In the step of obtaining the film thickness of the foam to be measured, the optical intensity history is used to select an optical spectrum to be used to obtain the film thickness of the foam to be measured. This method allows for easy selection of the optical spectrum used to obtain the film thickness of the foam being measured by utilizing the light intensity history. Therefore, the foam measurement method can simultaneously measure both the foam thickness and the foam size.

[0011] In the foam measurement method described above, in the step of obtaining the film thickness of the foam to be measured, the period during which the light intensity history satisfies predetermined conditions may be acquired, and the light spectrum acquired during the period satisfying the conditions may be selected to be used to obtain the film thickness of the foam to be measured. According to this method, the light spectrum to be used to obtain the film thickness of the foam to be measured can be selected with a simple process. [Effects of the Invention]

[0012] According to the present invention, a foam measuring device and a foam measuring method are provided that can simultaneously measure the film thickness and size of foam. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a block diagram showing the components of the foam measuring device according to the embodiment. [Figure 2] Figure 2(a) is a magnified perspective view of the tip of the optical fiber probe. Figure 2(b) is a plan view illustrating the shape of the tip of the optical fiber probe. [Figure 3] Figure 3 is a graph illustrating the reasoning behind the design of the tip shape of the optical fiber probe. [Figure 4] Figure 4 shows an example of a light spectrum. [Figure 5] Figure 5 is a flowchart showing the main steps of the foam measurement method according to the embodiment. [Figure 6] Figure 6 is a flowchart that shows in detail the steps to obtain the intermembrane distance shown in Figure 5. [Figure 7] Figure 7 is a flowchart that shows in detail the steps to obtain the film thickness shown in Figure 5. [Figure 8] Figure 8(a) shows the state before the optical fiber probe is inserted into the foam. Figure 8(b) shows the state when the optical fiber probe is close to the first layer of the foam. Figure 8(c) shows the state when the optical fiber probe has been inserted into the first layer of the foam. [Figure 9] Figure 9(a) shows the optical fiber probe after it has penetrated the first layer of the foam. Figure 9(b) shows the optical fiber probe moving within the foam region. Figure 9(c) shows the optical fiber probe approaching the second layer of the foam. [Figure 10] Figure 10(a) shows the optical fiber probe inserted into the second layer of the foam. Figure 10(b) shows the optical fiber probe having penetrated the second layer of the foam. [Figure 11]FIG. 11 is an example of a light intensity history. MODE FOR CARRYING OUT THE INVENTION

[0014] Hereinafter, modes for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and overlapping descriptions are omitted.

[0015] <Foam measuring device> The foam measuring device 1 shown in FIG. 1 acquires information related to foam. The information related to foam acquired by the foam measuring device 1 is the film thickness 9T of bubbles 9 constituting the foam and the size 9Z of the bubbles 9. In the following description, the information related to foam may be referred to as "foam information".

[0016] Although FIG. 1 shows a state where bubbles 9 contained in a container 8 are measured, measurement of bubbles 9 by the foam measuring device 1 does not require sampling of the bubbles 9 to be measured. That is, information related to bubbles 9 can be acquired by collecting bubbles 9 from a place where the bubbles 9 to be measured such as a bioreactor exist, or information related to bubbles 9 can be directly acquired by the foam measuring device 1 without collecting the bubbles 9. Furthermore, the foam measuring device 1 can simultaneously measure the film thickness 9T of bubbles 9 and the size 9Z of the bubbles 9. The "simultaneous measurement" mentioned herein means that numerical values of the film thickness 9T and the size 9Z can be obtained for one bubble 9.

[0017] The foam measuring device 1 includes a light source device 2 (light source unit), an optical fiber probe 3, a probe moving device 4, an optical measuring device 5 (optical measuring unit), and a computer 6 (processing unit).

[0018] The light source device 2 outputs measurement light L1 supplied to the optical fiber probe 3. The light source device 2 may operate independently or may operate in response to a control signal C2 from the computer 6. The measurement light L1 output by the light source device 2 contains multiple light components with different wavelengths. For example, the light source device 2 may be a halogen lamp, and the measurement light L1 may be so-called white light.

[0019] <Optical fiber probe> The optical fiber probe 3 has a fiber body portion 31 and a fiber tip portion 32, as shown in Figure 2(a). The fiber body portion 31 is the part with a constant diameter. The fiber tip portion 32 is the part that is inserted into the bubble 9, which is the object of measurement. While the fiber body portion 31 has a constant diameter, the outer diameter of the fiber tip portion 32 decreases towards the tip. In other words, the shape of the fiber tip portion 32 can be said to be tapered. Furthermore, an optical input / output surface 32s is formed on the fiber tip portion 32.

[0020] The optical input / output surface 32s emits a portion of the measurement light L1 to the outside. The optical input / output surface 32s also receives the reflected light L2 generated by the measurement light L1 into the optical fiber probe 3. Furthermore, the optical input / output surface 32s reflects the measurement light L1 according to the relationship between the refractive index of the optical fiber probe 3 and the refractive index of the liquid or gas phase in contact with the optical input / output surface 32s. In other words, the optical input / output surface 32s has three functions: emission of measurement light L1, incidence of reflected light L2, and reflection of measurement light L1.

[0021] These three functions are related to the measurement of the film thickness 9T of bubble 9 and the measurement of the size 9Z of bubble 9, which will be described later. First, the measurement of the film thickness 9T of bubble 9 involves the emission of measurement light L1 and the incidence of reflected light L2. Furthermore, the measurement of the size 9Z of bubble 9 involves the reflection of measurement light L1.

[0022] Here, it is important to note that the functions of emitting measurement light L1 and reflecting measurement light L1 are contradictory. For example, an optical input / output surface 32s that emits measurement light L1 well does not reflect measurement light L1 well. Such an optical input / output surface 32s seems suitable for measuring the film thickness 9T of the bubble 9, but does not seem suitable for measuring the size 9Z of the bubble 9. Conversely, an optical input / output surface 32s that reflects measurement light L1 well does not emit measurement light L1 well. Such an optical input / output surface 32s seems suitable for measuring the size 9Z of the bubble 9, but does not seem suitable for measuring the film thickness 9T of the bubble 9.

[0023] As a result of diligent research by the inventors, the physical shape of the fiber tip 32 and optical input / output surface 32s of the optical fiber probe 3 has been determined to enable both the measurement of the film thickness 9T of the bubble 9 and the measurement of the size 9Z of the bubble 9. Specifically, as shown in Figure 2(b), the surface angle G32 of the optical input / output surface 32s of the optical fiber probe 3 is set to 60 degrees or more and 90 degrees or less with respect to the optical axis A3. Furthermore, the surface angle G32 of the optical input / output surface 32s of the optical fiber probe 3 may be set to 65 degrees or more and 70 degrees or less with respect to the optical axis A3. In addition, the apex angle V32 of the tapered fiber tip 32 is set to 3 degrees or more and 10 degrees or less.

[0024] The reason for setting the surface angle G32 of the optical input / output surface 32s within the range described above can be easily understood using the graph G3 shown in Figure 3. The graph G3 shown in Figure 3 shows the surface angle G32 of the optical input / output surface 32s (horizontal axis) and the light intensity of the light reflected back from the optical input / output surface 32s (vertical axis). For example, when the surface angle G32 of the optical input / output surface 32s is 45 degrees, the light intensity of the light reflected back from the optical input / output surface 32s is the strongest. This surface angle G32 is suitable for measuring the size 9Z of the bubble 9 using the reflection of the measurement light L1 at the optical input / output surface 32s. For example, when the surface angle G32 of the optical input / output surface 32s is 65 degrees, the light intensity of the light reflected back from the optical input / output surface 32s is the weakest. This surface angle G32 is suitable for measuring the film thickness 9T of the bubble 9 based on the light emitted from the optical input / output surface 32s.

[0025] Here, the inventors concluded that the function of the optical input / output surface 32s should prioritize the function of emitting the measurement light L1 and simultaneously receiving the reflected light L2, rather than the function of reflecting the measurement light L1. This is because, as will be described later, the optical spectrum D52 of the reflected light L2 is used to measure the film thickness 9T. To obtain the optical spectrum D52 of the reflected light L2, sufficient light intensity is required. Therefore, in order to obtain reflected light L2 with sufficient light intensity, it is necessary to emit the measurement light L1 with sufficient light intensity from the optical input / output surface 32s. In contrast, to measure the size 9Z of the bubble 9, the intensity of the reflected light generated at the optical input / output surface 32s is used. In other words, the light used to measure the size 9Z of the bubble 9 passes only inside the optical fiber probe 3, so the attenuation of its intensity can be almost ignored. Furthermore, there is no need to obtain the optical spectrum D52 as in the measurement of the film thickness 9T of the bubble 9, and the light intensity itself is used. From this perspective, it can be explained why the function of the optical input / output surface 32s prioritizes the function of emitting the measurement light L1 and inducing the return light L2 over the function of reflecting the measurement light L1. Furthermore, as can be seen from graph G3 in Figure 3, the surface angle G32 of the optical input / output surface 32s is set to a range of 60 degrees to 90 degrees, where the light intensity of the light reflected back from the optical input / output surface 32s can be considered relatively weak. In addition, the surface angle G32 of the optical input / output surface 32s may be set to a range of 65 degrees to 70 degrees.

[0026] <Probe moving device> Measurement using the foam measuring device 1 requires relative movement of the optical fiber probe 3 (more specifically, the optical input / output surface 32s) relative to the foam 9. This relative movement may be achieved by moving the optical fiber probe 3 relative to a stationary foam 9. Conversely, it may be achieved by moving the optical fiber probe 3 relative to a moving foam 9. Furthermore, it may be achieved by moving the optical fiber probe 3 relative to the moving foam 9. In this embodiment, it will be described as being achieved by moving the optical fiber probe 3 relative to a stationary foam 9. The probe moving device 4 moves the optical fiber probe 3 relative to the stationary foam 9.

[0027] <Optical measuring device> The optical measuring device 5 obtains information about the light received from the optical fiber probe 3. Specifically, the optical measuring device 5 includes a photodiode 51 and a spectrometer 52. The photodiode 51 obtains the light intensity of the received light. The photodiode 51 outputs a light intensity history D51 that correlates light intensity with time. The spectrometer 52 obtains the distribution of light intensity for each wavelength of the received light (light spectrum). The spectrometer 52 outputs a light spectrum D52 that correlates the light spectrum D52 with time.

[0028] <Computer> Computer 6 obtains foam information using the light intensity history D51 and light spectrum D52 output by the optical measuring device 5. Computer 6 realizes multiple functional components by executing a foam measurement program read from memory 6m by processor 6p. The functional components realized by processor 6p are the light source control unit 61, the optical information acquisition unit 62, and the foam information acquisition unit 63.

[0029] The light source control unit 61 provides a control signal C2 to the light source device 2. The control signal C2 includes commands to realize various functions of the light source device 2. For example, the control signal C2 may include a command to emit the measurement light L1, or a command to stop the measurement light L1. If the characteristics of the light emitted by the light source device 2 are adjustable, for example, the control signal C2 may include a command to specify the wavelength range of the light components included in the measurement light L1. Also, if the light source device 2 has a function to continuously change the wavelength of the measurement light L1, it may include commands to specify a lower wavelength limit and an upper wavelength limit.

[0030] Furthermore, if the light source device 2 can operate independently without requiring the control signal C2, the light source control unit 61 may be omitted.

[0031] The optical information acquisition unit 62 obtains optical information from the optical measuring device 5. The optical information acquisition unit 62 stores the acquired optical information in memory 6m. The optical information acquisition unit 62 includes an optical intensity history acquisition unit 621 that receives the optical intensity history D51, and an optical spectrum acquisition unit 622 that receives the optical spectrum D52. In the example in Figure 1, the optical information acquisition unit 62 is shown as being implemented by a processor 6p, but the optical information acquisition unit 62 can be implemented by various components. For example, if the computer 6 receives optical information via a communication line, the optical information acquisition unit 62 may be a communication interface. If the computer 6 receives optical information via a recording medium such as a memory card, the optical information acquisition unit 62 may be a reading interface such as a card reader.

[0032] The foam information acquisition unit 63 obtains the size 9Z and the film thickness 9T of the foam 9 using optical information. The foam information acquisition unit 63 includes an interfilm distance calculation unit 631, a film thickness calculation unit 632, and an optical spectrum selection unit 633.

[0033] <Membrane Distance Calculation Unit> The size 9Z of bubble 9 can be expressed by several definitions. In this embodiment, the size 9Z of bubble 9 is defined as the intermembrane distance.

[0034] When the optical fiber probe 3 moves toward the bubble 9, the optical fiber probe 3 passes through the membrane of each bubble 9 twice. The membrane-to-membrane distance calculation unit 631 first obtains the time when it comes into contact with the first membrane portion 91 of the bubble 9 (see Figure 8(a), etc.) as the first membrane penetration time. Next, it obtains the time when it comes into contact with the second membrane portion 92 of the bubble 9 (see Figure 10(a), etc.) as the second membrane penetration time. Then, based on the difference between the first membrane penetration time and the second membrane penetration time, and the moving speed of the optical fiber probe 3 by the probe moving device 4, it obtains the distance from the first membrane portion 91 to the second membrane portion 92 as the membrane-to-membrane distance.

[0035] Whether the optical input / output surface 32s of the optical fiber probe 3 has penetrated the first film portion 91 or the second film portion 92 can be determined by the intensity of the light produced by reflection at the optical input / output surface 32s. When the optical input / output surface 32s has not penetrated the first film portion 91 or the second film portion 92, the optical input / output surface 32s can be considered to be in contact with the gas phase (air). In this case, the difference between the refractive index of the material constituting the optical input / output surface 32s (1.44) and the gas phase (air: 1) is large, so the intensity of the light produced by reflection is strong. On the other hand, when the optical input / output surface 32s has penetrated the first film portion 91 or the second film portion 92, the optical input / output surface 32s can be considered to be in contact with the liquid phase. In this case, the difference between the refractive index of the material constituting the optical input / output surface 32s (1.44) and the liquid phase (water: 1.33) is small, so the intensity of the light produced by reflection is weak. Therefore, in the light intensity history D51, the time when the light intensity changes from the gas phase intensity to the liquid phase intensity is the time when the light input / output surface 32s penetrates the first film portion 91 or the second film portion 92. Conversely, in the light intensity history D51, the time when the light intensity returns from the liquid phase intensity to the gas phase intensity is the time when the light input / output surface 32s leaves the first film portion 91 or the second film portion 92.

[0036] <Film Thickness Calculation Unit> The film thickness calculation unit 632 obtains the film thickness 9T using the optical spectrum D52 as illustrated in Figure 4. The film thickness 9T is obtained by applying the value obtained from the optical spectrum D52 to the following formula, based on the principle known as spectral interferometry.

number

[0037] <Optical Spectrum Selection Section> As mentioned earlier, the optical spectrum D52 is used to obtain a film thickness of 9T. The key point here is which of the multiple optical spectra D52 acquired over time is used to obtain a film thickness of 9T. The optical spectrum selection unit 633 addresses this by selecting the optical spectrum D52 necessary to obtain a film thickness of 9T.

[0038] According to the optical intensity history D51 (see Figure 11), when the optical input / output surface 32s of the optical fiber probe 3 is in contact with the gas phase, the optical intensity falls within the range of the gas phase intensity P11. Here, it can be seen that the optical intensity increases during the time period T11a (see state T2 in Figure 8(b)) when the optical input / output surface 32s of the optical fiber probe 3 is close to the first film portion 91 (see Figure 11). When the optical input / output surface 32s is sufficiently far from the first film portion 91, the photodiode 51 receives light reflected from the optical input / output surface 32s. Then, when the optical input / output surface 32s is close to the first film portion 91, the photodiode 51 receives not only the light reflected from the optical input / output surface 32s, but also the reflected light L2 that is emitted from the optical input / output surface 32s toward the first film portion 91 and reflected back from the first film portion 91. As a result, the optical intensity increases during the time period T11a when the optical input / output surface 32s of the optical fiber probe 3 is close to the first film portion 91. In other words, by using the optical spectrum D52 acquired during the period when the light intensity increases in the region of gas phase intensity P11, a film thickness of 9T can be obtained.

[0039] The optical spectrum selection unit 633 extracts the period in the region of gas phase intensity P11 in the optical intensity history D51 during which the optical intensity increases. Then, it selects the optical spectrum D52 acquired during the extracted period as the optical spectrum D52 for obtaining the film thickness 9T. The optical spectrum selection unit 633 may, for example, select the optical spectrum D52 acquired when the optical input / output surface 32s is in proximity to the first film portion 91, provided that the proximity intensity P11a has been exceeded. Alternatively, the optical spectrum selection unit 633 may, for example, select the optical spectrum D52 acquired when the optical input / output surface 32s is in proximity to the first film portion 91, provided that the optical intensity history D51 has reached its peak.

[0040] <Method for measuring foam> Next, the foam measurement method performed by the foam measurement device 1 will be explained with reference to the flowcharts shown in Figures 5, 6, and 7.

[0041] First, the movement of the optical fiber probe 3 is initiated (S1). This operation is performed by the probe moving device 4.

[0042] Next, optical information is obtained (S2). Specifically, first, the output of the measurement light L1 is started (S21). This operation is performed by the computer 6 and the light source device 2. Subsequently, the acquisition of the light intensity history D51 is started (S22). This operation is performed by the photodiode 51 and the computer 6. Also, the acquisition of the optical spectrum D52 is started (S23). This operation is performed by the spectrometer 52 and the computer 6. The acquisition of the light intensity history D51 and the optical spectrum D52 continues until a predetermined period has elapsed. Subsequently, the acquisition of the light intensity information is stopped (S24) and the acquisition of the optical spectrum D52 is stopped (S25). Then, the output of the measurement light L1 is stopped (S26).

[0043] Next, foam information is obtained (S3). This step S3 includes a step S31 to obtain the interlayer distance and a step S32 to obtain the film thickness 9T. The step S31 to obtain the interlayer distance may be performed first, followed by the step S32 to obtain the film thickness 9T. Alternatively, the step S32 to obtain the film thickness 9T may be performed first, followed by the step S31 to obtain the interlayer distance. The step S31 to obtain the interlayer distance is performed by the interlayer distance calculation unit 631. The step S32 to obtain the film thickness 9T is performed by the optical spectrum selection unit 633 and the film thickness calculation unit 632.

[0044] Step S31, which is used to obtain the intermembrane distance, will be explained in detail with reference to Figure 6.

[0045] First, it is determined whether the light intensity has changed from gas phase intensity P11 to liquid phase intensity P12 (S31a). This determination (S31a) is repeated until it is determined that the light intensity has changed from gas phase intensity P11 to liquid phase intensity P12. If the light intensity does not change from gas phase intensity P11 to liquid phase intensity P12 (S31a: NO), the tip of the optical fiber probe 3 (optical input / output surface 32s) is not yet in contact with the first film portion 91 of the bubble 9 (see state T1 in Figure 8(a)). If the light intensity has changed from gas phase intensity P11 to liquid phase intensity P12 (S31a: YES), it is determined that the tip of the optical fiber probe 3 has penetrated the first film portion 91 (S31b: see state T3 in Figure 8(c)). The time of penetration is then obtained as the first penetration time (S31c).

[0046] Next, it is determined whether the light intensity has returned from liquid phase intensity P12 to gas phase intensity P11 (S31d). The determination of whether the light intensity has returned from liquid phase intensity P12 to gas phase intensity P11 (S31d) is repeated until it is determined that the light intensity has returned from liquid phase intensity P12 to gas phase intensity P11. If the light intensity does not return from liquid phase intensity P12 to gas phase intensity P11 (S31d: NO), the tip of the optical fiber probe 3 (optical input / output surface 32s) may still be embedded in the first film portion 91 of the bubble 9 (see state T3 in Figure 8(c)). Alternatively, the tip of the optical fiber probe 3 (optical input / output surface 32s) may still be outside the first film portion 91 of the bubble 9, but the optical input / output surface 32s may still be wet (see state T4 in Figure 9(a)). When the light intensity returns from liquid phase intensity P12 to gas phase intensity P11 (S31d: YES), it is determined that the tip of the optical fiber probe 3 has detached from the first film portion 91 and the tip is not wet (S31e: see state T5 in Figure 9(b)). In this state, the tip of the optical fiber probe 3 is located inside the bubble 9.

[0047] Next, it is determined whether the light intensity has changed from the gas phase intensity P11 to the liquid phase intensity P12 (S31f). This determination of whether the light intensity has changed from the gas phase intensity P11 to the liquid phase intensity P12 (S31f) is repeated until it is determined that the light intensity has changed from the gas phase intensity P11 to the liquid phase intensity P12. If the light intensity does not change from the gas phase intensity P11 to the liquid phase intensity P12 (S31f: NO), the tip of the optical fiber probe 3 (optical input / output surface 32s) is not yet in contact with the second film portion 92 of the bubble 9 (see state T6 in Figure 9(c)). If the light intensity has changed from the gas phase intensity P11 to the liquid phase intensity P12 (S31f: YES), it is determined that the tip of the optical fiber probe 3 has penetrated the second film portion 92 (S31g: see state T7 in Figure 10(a)). The time of penetration is then obtained as the second penetration time (S31h).

[0048] Next, it is determined whether the light intensity has returned from liquid phase intensity P12 to gas phase intensity P11 (S31i). This determination of whether the light intensity has returned from liquid phase intensity P12 to gas phase intensity P11 (S31i) is repeated until it is determined that the light intensity has returned from liquid phase intensity P12 to gas phase intensity P11. If the light intensity does not return from liquid phase intensity P12 to gas phase intensity P11 (S31i: NO), the tip of the optical fiber probe 3 (optical input / output surface 32s) may still be embedded in the second film portion 92 of the bubble 9 (see state T7 in Figure 10(a)). Alternatively, the tip of the optical fiber probe 3 (optical input / output surface 32s) may have left the second film portion 92 of the bubble 9, but the optical input / output surface 32s may still be wet. When the light intensity returns from liquid phase intensity P12 to gas phase intensity P11 (S31i: YES), it is determined that the tip of the optical fiber probe 3 has detached from the second film portion 92 and the tip is not wet (S31j: see state T8 in Figure 10(b)). In this state, the tip of the optical fiber probe 3 is located outside the bubble 9.

[0049] Then, the interlayer distance (size 9Z) is obtained (S31k). By obtaining the difference between the first penetration time and the second penetration time, the time required for the optical input / output surface 32s to travel from the first layer 91 to the second layer 92 can be determined. Using this transit time and the movement speed of the optical fiber probe 3, the interlayer distance (size 9Z) from the first layer 91 to the second layer 92 can be obtained.

[0050] Next, with reference to Figure 7, step S32 for obtaining the film thickness 9T will be described in detail. First, the period during which the light intensity exceeds the proximity intensity within the range of the gas phase intensity P11 is extracted as the proximity period T11a (S32a). Next, the light spectrum D52 acquired during the proximity period T11a is selected (S32b). Steps S32a and S32b are performed by the light spectrum selection unit 633. Then, the film thickness 9T is obtained using the selected light spectrum D52 (S32c). Step S32c is performed by the film thickness calculation unit 632.

[0051] <Effects and Effects> The foam measurement device 1 comprises a light source device 2 that outputs measurement light L1 containing multiple light components of different wavelengths, an optical fiber probe 3 that receives the measurement light L1 from the light source device 2 and is capable of moving relative to the foam 9, an optical measurement device 5 that obtains optical information regarding the reflected light L2 obtained as a result of inputting the measurement light L1 to the optical fiber probe 3, and a computer 6 that uses the optical information to obtain foam information including the film thickness 9T and the size 9Z of the foam 9. The optical fiber probe 3 includes a fiber tip 32 that is inserted into the foam 9. The fiber tip 32 includes an optical input / output surface 32s whose angle with respect to the optical axis A3 of the optical fiber probe 3 is 60 degrees or more and 90 degrees or less.

[0052] This foam measuring device 1 is equipped with an optical fiber probe 3 that includes an optical input / output surface 32s with an angle between 60 and 90 degrees. This optical fiber probe 3 makes it possible to obtain reflected light from the optical input / output surface 32s that can be used to calculate the size 9Z of the foam 9, and to obtain emitted light and reflected light L2 from the optical input / output surface 32s that can be used to calculate the film thickness 9T of the foam 9. Therefore, the foam measuring device 1 can simultaneously measure the film thickness 9T and the size 9Z of the foam 9.

[0053] The fiber tip 32 has an apex angle of 3 degrees or more and 10 degrees or less. This configuration makes it possible to increase the intensity of the measurement light L1 emitted from the optical input / output surface 32s.

[0054] The plane angle G32 of the optical input / output surface 32s with respect to the optical axis A3 of the optical fiber probe 3 is between 65 degrees and 75 degrees. This configuration suppresses the reflection of measurement light L1 at the optical input / output surface 32s and increases the light intensity of the measurement light L1 emitted from the optical input / output surface 32s and the reflected light L2 incident from the optical input / output surface 32s.

[0055] The foam measurement method includes the steps of obtaining optical information based on reflected light L2 obtained as a result of applying measurement light L1 containing multiple optical components of different wavelengths to the optical fiber probe 3 during the period in which relative movement of the optical fiber probe with respect to the foam to be measured occurs (S2), and obtaining foam information including the film thickness 9T and the size 9Z of the foam 9 using the optical information (S3). The step of obtaining optical information (S3) includes the step of acquiring optical intensity history D51, which is the change in optical intensity of the reflected light L2 over time (S21), and the step of acquiring optical spectrum D52, which shows the distribution of optical intensity for each wavelength in the reflected light L2 (S22). The step of obtaining foam information (S3) includes the step of obtaining the size 9Z of the foam 9 using the optical intensity history D51 (S31), and the step of obtaining the film thickness 9T of the foam 9 using the optical spectrum D52 (S32). In the step (S32) of obtaining the film thickness 9T of the bubble 9, the optical spectrum D52 to be used to obtain the film thickness 9T of the bubble 9 is selected using the optical intensity history D51.

[0056] This method allows for easy selection of the optical spectrum D52 used to obtain the film thickness 9T of the bubble 9 by using the optical intensity history D51. Therefore, the bubble measurement method can simultaneously measure the film thickness 9T and the size 9Z of the bubble 9.

[0057] In the step (S32) of obtaining the film thickness 9T of the bubble 9, the time when the light intensity history D51 satisfies a predetermined condition may be obtained, and the light spectrum D52 obtained at the time when the condition is satisfied may be selected to be used to obtain the film thickness 9T of the bubble 9. According to this method, the light spectrum D52 to be used to obtain the film thickness 9T of the bubble 9 can be selected by a simple process.

[0058] The present invention can be implemented in various forms, including the embodiments described above, with various modifications and improvements based on the knowledge of those skilled in the art. Furthermore, it is also possible to construct modified versions by utilizing the technical matters described in the embodiments described above. [Explanation of Symbols]

[0059] 1... Foam measurement device, 2... Light source device (light source unit), 3... Optical fiber probe, 31... Fiber body unit, 32... Fiber tip unit, 32s... Optical input / output surface, A3... Optical axis, 5... Optical measurement device (optical measurement unit), 51... Photodiode, 52... Spectrometer, 6... Computer (processing unit), 61... Light source control unit, 62... Optical information acquisition unit, 63... Foam information acquisition unit, 9... Foam (foam to be measured), 9T... Film thickness, D51... Optical intensity history, D52... Optical spectrum, G32... Surface angle, V32... Apex angle.

Claims

1. A light source unit that outputs measurement light containing multiple light components with different wavelengths, A fiber optic probe that receives the measurement light from the light source and is capable of moving relative to the foam to be measured, An optical measurement unit that obtains optical information regarding the reflected light obtained as a result of inputting the measurement light to the optical fiber probe, The system includes a processing unit that uses the aforementioned optical information to obtain foam information including the film thickness and size of the foam to be measured, The optical fiber probe includes a fiber tip that is inserted into the foam to be measured, The foam measuring device includes an optical input / output surface in which the fiber tip is at an angle of 60 degrees or more and 90 degrees or less with respect to the optical axis of the optical fiber probe.

2. The foam measuring device according to claim 1, wherein the tip of the fiber has an apex angle of 3 degrees or more and 10 degrees or less.

3. The foam measuring device according to claim 1 or 2, wherein the angle of the optical input / output surface with respect to the optical axis of the optical fiber probe is 65 degrees or more and 75 degrees or less.

4. The steps include obtaining optical information based on the reflected light obtained as a result of applying measurement light containing multiple optical components of different wavelengths to the optical fiber probe during the period in which the optical fiber probe is moving relative to the foam to be measured, The process includes the step of obtaining foam information, including the film thickness and size of the foam to be measured, using the aforementioned optical information. The step of obtaining the aforementioned optical information is: The steps include acquiring a light intensity history, which is the change in the light intensity of the reflected light over time, The step of obtaining an optical spectrum showing the distribution of light intensity for each wavelength in the reflected light, The step of obtaining the aforementioned foam information is: A step of obtaining the size of the foam to be measured using the light intensity history, The step includes obtaining the film thickness of the foam to be measured using the aforementioned optical spectrum, A foam measurement method comprising the step of obtaining the film thickness of the foam to be measured, wherein the optical spectrum to be used to obtain the film thickness of the foam to be measured is selected using the optical intensity history.

5. In the step of obtaining the film thickness of the foam to be measured, The period during which the aforementioned light intensity history satisfies predetermined conditions is obtained. The foam measurement method according to claim 4, wherein the optical spectrum acquired during the period in which the above conditions are met is selected to be used to obtain the film thickness of the foam to be measured.

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