JP2005091186A - Method of measuring viscosity of liquid, and measuring instrument for index for indicating viscosity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure a correct viscosity, based on a relative velocity v of a liquid to a laser converging position (or particle position). <P>SOLUTION: A laser beam 4 emitted from a laser beam source 2 is converged by a condenser lens 8 via a galvano-mirror 6. The galvano-mirror 6 is scanned to trap a particle 16 in a convergence position 10, and it is displaced to draw a circle as shown by an arrow mark 12. A velocity of circular motion is increased to observe by a microscope 30 that the particle 16 is separated from the convergence position 10, so as to specify a separation time by a specifying switch 32. The motion of particles 14, 18 not trapped therein is observed by a microscope 26 connected to a video camera 28, and an image is analyzed by a computer 34 to measure a flow velocity and a flow direction of the liquid 20. The motion in the separation of the trapped particle is corrected based on the measured flow velocity and flow direction of the liquid 20 to measure the accurate viscosity. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a technique for measuring the viscosity of a liquid using a laser.

A technique for measuring the viscosity of a liquid using a laser has been developed. According to this technique, it is possible to measure the viscosity of a minute region (local) compared to a method of measuring the viscosity of a liquid without using a laser.
Non-Patent Document 1 discloses a viscosity measurement method using a laser trapping method. In this method, the particles suspended in the liquid are irradiated with a laser, the particles are trapped at the condensing position, and the trapped particles are moved by relatively moving the liquid support and the laser irradiation device in the trapped state. Is moved relative to the liquid to cause the viscous resistance force of the liquid to act on the particles, and the time when the particles trapped at the condensing position are separated from the condensing position by the viscous resistance force is observed. Viscosity can be determined based on Stokes' law from the trapping force (viscous resistance force) acting on the particles when separated from the focusing position, the velocity of the particles, and the radius of the particles.

Iwashita Masataka, Master's thesis, University of Tokyo, 2000, p. 7-8

In the laser trapping method, the viscosity of the liquid is obtained based on Stokes' law. According to Stokes' law, when a particle having a radius R moves in a liquid having a viscosity η at a relative speed v, the viscous resistance force F acting on the particle is given by equation (1).
F = 6πηRv (1)

  In the laser trapping method, it is considered that the viscous resistance force F when the particles are detached from the laser focusing position is equal to the laser trapping force. In one method, the laser trapping force is reduced by gradually decreasing the laser output while maintaining the relative velocity v of the particles trapped by the laser with respect to the liquid constant. In this method, a laser trap force (identified from a laser output) when particles are detached from the laser condensing position is measured.

Equation (2) for viscosity η is derived from equation (1).
η = (1 / 6πR) (F / v) (2)

  Substituting into equation 2 the particle radius R, the laser trapping force F when the particle is released from the laser focusing position, and the relative velocity v when the particle is released from the laser focusing position, the viscosity of the liquid η can be obtained.

In another method of the laser trapping method, the relative velocity v of the particles trapped by the laser with respect to the liquid is increased while maintaining the laser trapping force constant by maintaining the laser output constant. In this method, the relative velocity v when the particles are detached from the laser focusing position is measured.
Substituting into equation 2 the particle radius R, the constant laser trapping force F, and the relative velocity v when the particle leaves the condensing position of the laser, the viscosity η of the liquid can be determined. .

In Non-Patent Document 1, it is assumed that the liquid set in the viscosity measuring device is stationary. For example, a low-viscosity liquid, such as water, can be regarded as stationary during measurement because it will flow quickly after being set in the viscosity measurement device and spread over a flat surface of water. it can. Therefore, the value of the measured relative velocity v (more precisely, the relative velocity v between the liquid support and the laser focusing position) can be used as it is for the calculation of the viscosity η.
However, when the viscosity of the liquid is high, the liquid set on the liquid support does not settle down easily and often continues to flow. For example, high viscosity oil continues to flow slowly for a long time. If the liquid whose viscosity is being measured continues to flow, the measured relative velocity v is not the relative velocity of the liquid at the particle and the particle location, even if it is the relative velocity between the liquid support and the laser focusing position. Therefore, an inaccurate viscosity is calculated due to the flow phenomenon of the liquid during the viscosity measurement.

The flow velocity of the liquid is generally expressed in three dimensions, but the thickness of the liquid set on the liquid support is smaller than the spread in the surface direction, so it approximates the flow in a two-dimensional plane parallel to the liquid support surface. can do. Hereinafter, this plane is referred to as an xy plane.
The relative velocity of the laser focusing position with respect to the liquid support is u (x direction component u _x , y direction component u _y ), and the flow velocity of the liquid with respect to the liquid support is w (x direction component w _x , y direction component w _y). ), and comes to the relative velocity of the liquid to the laser light converging position v (x direction component _v x, and y-direction component _{v y), v x = u} x -w x _becomes, the v _{y =} u y -w _y . Therefore, the following three formulas are derived.
v = {u ² + w ² −2 (u _x w _x + u _y w _y )} ^1/2 (3)
If the liquid does not flow with respect to the liquid support, w _x = w _y = w = 0 and v = u holds, but if the liquid flows and w ≠ 0, v ≠ u.
When measuring the viscosity with a laser, the relative velocity v of the liquid with respect to the laser focusing position (or particle position) is important. If v ≠ u, the laser focusing position (or particle position) and the liquid support are used. If the viscosity is calculated from the relative velocity u, an inaccurate viscosity is calculated.

  In the present invention, taking into account that a high-viscosity liquid continues to flow during viscosity measurement, the correct viscosity is measured based on the relative velocity v of the liquid with respect to the laser focusing position (or particle position), and the laser focusing position A technique is provided in which an inaccurate viscosity is not measured from the relative velocity u of a liquid support.

(One way to solve the problem)
In one viscosity measurement method according to the present invention, a step of moving a particle suspended in a liquid by irradiating a laser with respect to the liquid support and a relative velocity of the particles moving with respect to the liquid support are specified. Correcting the flow velocity of the liquid flowing relative to the liquid support to the specified relative velocity, calculating the relative velocity of the liquid at the particle and the particle location, and the calculated particle And calculating the viscosity of the liquid using the relative velocity of the liquid at the particle location.
(The action)
In this method, the viscosity of the liquid is not calculated from the relative velocity between the liquid support and the particles. The flow velocity of the liquid flowing with respect to the liquid support is corrected to the relative velocity between the liquid support and the particle, and the relative velocity of the liquid at the particle and particle existence site is calculated. Then, the viscosity of the liquid is calculated using the relative velocity of the liquid at the particle and the particle existence site.
According to this method, the correct viscosity can be measured even if the liquid whose viscosity is being measured continues to flow.

(One preferred means for solving the problem)
The particles can be moved relative to the liquid support by irradiating the laser to trap the particles at the laser focusing position and moving the focusing position relative to the liquid support.
To move the particles with respect to the liquid support, the liquid support is fixed and the condensing position where the particles are trapped is moved, or the liquid support is moved while the condensing position is fixed while the particles are trapped. Is done.
According to this method, the viscosity is measured by a laser trapping method. Even if the liquid whose viscosity is being measured continues to flow, the correct viscosity can be measured.

(One preferred means for solving the problem)
The particles can also be moved relative to the liquid support by irradiating the laser with light pressure acting on the particles.
In this method, particles are moved relative to the liquid support by the light pressure of the laser. In this case as well, it is useful to correct the flow rate of the liquid flowing with respect to the liquid support, and the viscosity is calculated by correcting the flow rate and calculating the relative velocity of the liquid at the particle-existing site. Even if the liquid being measured continues to flow, the correct viscosity can be measured.

(One preferred means for solving the problem)
The flow velocity of the liquid at the particle existence site may be directly measured. In this case, the relative velocity of the particles moving relative to the liquid support and the flow velocity of the liquid flowing relative to the liquid support are specified, and the influence of the flow velocity is eliminated by calculating the difference between the two. The relative velocity of the particles and the liquid at the particle location can be calculated.

(One preferred means for solving the problem)
By moving particles in multiple directions with respect to the liquid support, the flow rate of the liquid flowing with respect to the liquid support is potentially identified from the movement speed of the particles in each direction, and the relative liquids at the site where the particles are present The speed may be calculated.
When the particles are moved in a plurality of directions with respect to the liquid support, the flow rate of the liquid is added to the moving speed of the particles in each direction. From this, it becomes possible to mathematically calculate the flow velocity of the liquid flowing with respect to the liquid support, and it is possible to calculate the relative velocity of the liquid at the particle and the particle existence site. In this mathematical process, it is not necessary to explicitly calculate the flow velocity of the liquid, and the relative velocity of the particles and the liquid can be calculated directly. Even when the relative velocity of the particle and the liquid is directly calculated, it is calculated with a logic that can be calculated if the flow velocity of the liquid is calculated. Rather, it is also possible to implicitly calculate the flow velocity of the liquid and use it to calculate the relative velocity of the particles and the liquid. To explicitly calculate the quantity that exists ahead without explicitly solving it is said to be potentially specified here.

(One preferred means for solving the problem)
When the present invention is applied to the laser trapping method, the step of trapping particles suspended in the liquid by irradiating the laser at the condensing position of the laser and increasing the moving speed of the condensing position with respect to the liquid support And / or while moving the light collection position with respect to the liquid support while reducing the laser output trapping the particles, the particles trapped at the light collection position are detached from the light collection position. The relative velocity between the liquid support and the condensing position at the time and the laser output, and the relative velocity between the liquid support and the condensing position when leaving the condensing position. And the process of calculating the "relative velocity of the particle and the liquid at the particle location when leaving the condensing position" and the calculated "relative of the liquid at the particle and the particle existing site when leaving the focusing position"speed" Implementing a step of calculating the viscosity of the liquid from the laser output identified.
In the laser trapping method, the time when the trap is broken by the viscous resistance force applied to the particles by the relative movement of the particles and the liquid is specified. In order to obtain a phenomenon that the trap is broken, the light collection position is moved with respect to the liquid support. During movement, the trapping rate is increased by increasing the moving speed of the focusing position relative to the liquid support, or by reducing the laser power trapping the particles, so that the trapped particles are trapped at the focusing position. Move away from the focusing position.
Conventionally, the viscosity is calculated from the relative velocity between the liquid support and the light collection position when the liquid support is separated from the light collection position. The relative velocity of the position does not match the relative velocity of the particles and the liquid, and the wrong viscosity is calculated. In this method, in order to calculate the viscosity from the relative velocity by correcting the flow velocity of the liquid with respect to the condensing position, specifying the “relative velocity of the particle and the liquid at the particle existence site when leaving the condensing position”. The correct viscosity can be calculated.

(One preferred means for solving the problem)
In the measurement method in which light pressure is applied to particles by a laser, a step of moving the particles by irradiating the laser and applying light pressure to the particles suspended in the liquid, and a step of specifying the speed of the particles moving by the light pressure Correcting the flow velocity of the liquid at the particle location to the specified particle velocity, calculating the relative velocity of the liquid at the particle and the particle location, and calculating the relative velocity of the liquid at the particle and the particle location. And calculating the viscosity of the liquid.
Also in this method, since the viscosity of the liquid is calculated using the relative velocity of the liquid at the particle and the particle existence site, the accurate viscosity can be calculated even if the liquid under measurement is flowing.

(One way to solve the problem)
The present invention has also realized an apparatus for measuring an index indicating the viscosity of a liquid. The device identifies the liquid support that supports the liquid, the laser irradiation device that moves the particles suspended in the liquid by irradiating the laser to the liquid support, and the moving speed of the particles relative to the liquid support. Means for correcting the flow velocity of the liquid at the particle existence site relative to the liquid support, and calculating the relative velocity of the liquid at the particle and particle existence site.
The relative velocity of the particle and the liquid at the particle location calculated by this apparatus is an index indicating the viscosity of the liquid, and when this index is obtained, the correct viscosity can be known.

(One preferred means for solving the problem)
In the case of an apparatus used for the laser trapping method, a liquid support for supporting a liquid, a laser irradiation device for trapping particles suspended in the liquid at a light collection position, and a means for relatively moving the liquid support and the light collection position And means for identifying the moving speed of the particles relative to the liquid support; means for at least potentially identifying the flow speed of the liquid flowing with respect to the liquid support; Means are provided for identifying the relative velocity of the liquid at the site.
When we at least potentially specify the flow rate of a liquid relative to a liquid support, it is calculated not only explicitly but also by means of directly measuring the flow rate, calculating and explicitly calculating it. A means for directly calculating the relative velocity of the particles and liquid that matches the flow velocity is included.
According to this apparatus, an index necessary for accurately calculating the viscosity of the liquid that continues to flow during the measurement can be obtained, and the viscosity of the liquid that continues to flow can be accurately known.

(One preferred means for solving the problem)
When light pressure is applied to particles by a laser, a liquid support that supports the liquid, a laser irradiation device that moves the particles by applying light pressure to the particles suspended in the liquid, and a particle support for the liquid support Means for specifying the moving speed, means for at least potentially specifying the flow speed of the liquid flowing with respect to the liquid support, and means for specifying the relative speed of the liquid at the particle and the particle existing site are provided.
According to this apparatus, an index necessary for accurately calculating the viscosity of the liquid that continues to flow during the measurement can be obtained, and the viscosity of the liquid that continues to flow can be accurately known.

The main features of the embodiments described below are listed first.
(Form 1)
A step of irradiating particles suspended in the liquid with a laser to trap the particles at the laser condensing position, and moving the particles trapped at the condensing position relative to the liquid support to Measured in both steps, the process of measuring the relative velocity when trapped particles leave the focusing position, the process of measuring the "fluid velocity of the trapped particles at the site of the trapped particles" relative to the liquid support. Calculating the "relative speed of the liquid at the site where the particles and the particles are present when leaving the condensing position" from the "relative speed when leaving the condensing position" and "flow velocity", and the calculated " The step of calculating the viscosity of the liquid from the “relative velocity of the liquid at the site where the particle and the particle are present when the light is separated from the light collecting position” is performed.
In this case, the laser support position may be moved while the liquid support is fixed, or the liquid support may be moved while the laser focus position is fixed.
(Form 2)
A step of irradiating a particle floating in the liquid with a laser to trap the particle at the condensing position of the laser, and moving the particle trapped at the condensing position relative to the flow direction of the liquid and trapping at the condensing position Measuring the relative speed (relative speed between the liquid support and the condensing position) when the collected particles leave the condensing position, and the particles trapped at the condensing position are relative to the direction opposite to the liquid flow direction. A step of measuring the relative speed (relative speed between the liquid support and the condensing position) when the particles trapped at the condensing position are moved away from the condensing position, The step of calculating the average value of the “relative speed at the time of separation” and the step of calculating the viscosity of the liquid from the calculated average value are performed.
In this method, the trapped particles are moved in the flow direction, and the relative speed when they are separated from the condensing position is measured. Measure the speed and calculate the average of these. When the average value is calculated, the influence of the liquid flow is canceled, and the moving speed of the particles relative to the liquid is calculated.

(Form 3)
Irradiating a particle floating in the liquid with a laser to move the particle by light pressure, measuring the velocity of the particle moving by the light pressure, and measuring the flow velocity of the liquid at the particle location A step of calculating a “relative velocity of liquid at the particle and particle existence site” from the “particle velocity” and the “flow velocity” measured in both steps; The step of calculating the viscosity of the liquid from the “relative speed” is carried out.
In this method, instead of trapping the particles and applying the liquid viscous resistance force to the particles, the liquid viscous resistance force is applied to the particles by moving the particles by the optical pressure of the laser. In order to trap particles, it is necessary to irradiate the laser continuously, and a high-power laser is necessary. However, since a low-power laser is sufficient, the temperature of the liquid or particles rises and changes quality. Can be avoided.
(Form 4)
A step of irradiating a particle floating in the liquid with a laser to move the particle in the flow direction of the liquid by light pressure, a step of measuring the speed of the particle moving in the flow direction by the light pressure, and a suspension in the liquid A step of irradiating a particle to a laser to move the particle in the opposite direction by the light pressure, a step of measuring the velocity of the particle moving in the opposite direction by the light pressure, and the two “ A step of calculating an average value of “particle velocity” and a step of calculating the viscosity of the liquid from the calculated average value are performed.
In this method, after measuring the velocity of the particles when the particles are moved in the liquid flow direction by light pressure, the velocity of the particles is measured when the particles are moved in the opposite direction by light pressure. Calculate the average value of. When the average value is calculated, the influence of the flow of the liquid is canceled, and the viscosity can be calculated based on “the relative velocity of the liquid at the particle and the site where the particle exists”.

(Form 5)
The liquids to be measured are various liquids such as paints and polymer materials. The form of the liquid is not particularly limited, and a liquid having a thin film or a laminated film or a floating system composed of two or more phases may be used. Viscosity can be measured for each film or each phase having only a minute volume.
(Form 6)
Means for changing the temperature of the liquid to be measured. Viscosity can be measured at any suitable temperature.

(Form 7)
The particles may be any particles that float in the liquid without sedimentation. In order to prevent precipitation, the surface of the particles may be treated. Particles may be added to the liquid for viscosity measurement, but particles previously contained in the liquid can be used.
(Form 8)
The shape of the particles is not particularly limited, but is preferably spherical. In the case of spherical particles, the above equation (1) is established, so that measurement is easy and measurement accuracy is high. The particle diameter is required to be sufficiently smaller than the three-dimensional dimension of the liquid mass to be measured. This is because the formula (1) is established when the value is sufficiently small. The particle size distribution is preferably as small as possible. The particle size is indispensable for calculating the viscosity. If the distribution range is sufficiently small, the average particle size can be used as the particle size for viscosity calculation, and it is not necessary to measure the particle size every time the viscosity is measured. On the other hand, if the distribution range is large, the particle diameter must be measured every time the viscosity is measured.
(Form 9)
The particles trapped by the laser are preferably transparent to the laser. The material of the particles is small in absorption, scattering, and reflection, and it is desirable that the refractive index is higher than that of the liquid. Therefore, it is necessary to select the material in relation to the liquid. Particles that move with the laser light pressure are preferably highly reflective.
(Form 10)
The concentration of the particles in the liquid is preferably as low as possible within a range that does not take more time than necessary to find the particles to be irradiated with the laser. This is because if the concentration is high, the influence of the concentration of the particles on the viscosity of the liquid cannot be ignored.
(Form 11)
It is desirable that the other particles to be compared and contrasted with the laser-irradiated particles are particles as close to the irradiation position as possible within a range not affected by the laser. This is because if the particles are close to each other, the flow velocity of the particles can be regarded as the flow velocity of the liquid at the site where the particles to be irradiated with the laser are present.
(Form 12)
It is preferable that the number of other particles to be compared with the particles irradiated with the laser is as large as possible. This is because the error is reduced by taking the average of many particles.

(Form 13)
A laser irradiation apparatus used for the laser trapping method has a laser light source and a condensing optical system. The laser irradiation apparatus used to repel particles by light pressure may only have a laser light source with good directivity, but more preferably has a condensing optical system.
(Form 14)
As the laser light source, various lasers such as a solid laser, a gas laser, and a semiconductor laser can be used. The wavelength of the laser is desirably one that does not affect the liquid and particles, and specifically, it is desirable that the absorption by the liquid and particles be as small as possible. The laser preferably uses a Gaussian beam having an intensity gradient. It is desirable that the laser power be as large as possible without adversely affecting the liquid and particles. This is because the magnitude of the force with which the laser traps the particles and the magnitude of the light pressure that moves the particles are proportional to the laser power, and the higher the trapping force and the light pressure, the more accurate measurement becomes possible. The laser power is preferably variable.
(Form 15)
The condensing optical system condenses the laser from the laser light source so as to focus on the liquid to be measured.
(Form 16)
The distance between the condensing optical system and the liquid is preferably short. This is because the spot diameter at the condensing position is proportional to the focal length, so that the shorter the distance, the smaller the spot diameter, the higher the power density at the condensing position, and the greater the trapping force and light pressure. The direction of irradiation is preferably perpendicular to the liquid level in the case of the laser trapping method, and is preferably as parallel as possible to the liquid level in the case of the laser light pressure method. This is because it becomes easy to correct the flow of the liquid.

(Form 17)
The relative movement device may be one that causes the viscous resistance force of the liquid to act on the trapped particles by moving the light collection position, or may be one that causes the viscous resistance force to act on the trapped particles by moving the liquid. In the former case, a galvanometer mirror can be used, and in the latter case, fine movement means such as a piezo element can be used. The latter is preferable because it can be manufactured easily and at low cost.
(Form 18)
The relative movement device is preferably a device that linearly moves trapped particles or liquid at a constant speed. This is because Stokes' law of the formula (1) is used for calculating the viscosity. When the inertial force is negligible compared with the viscous resistance force of the above formula (1), a constant acceleration linear motion, a constant velocity circular motion, or a simple vibration may be used. The direction of motion is not limited, but it is preferable to be in a two-dimensional plane perpendicular to the incident surface of the laser in order to easily calculate the viscosity.

(Form 19)
As the particle measuring device, a microscope, a video camera, an image analysis device, or the like can be used. When the particle measuring apparatus performs automatic measurement, it is preferable to have a photodetector and detect the interaction light between the laser and the particles irradiated with the laser with the photodetector. When measuring particles moving with light pressure, the photodetector may detect light from a light source different from the laser and interaction light between the particles irradiated with the laser. As the photodetector, for example, a semiconductor photodetector such as a photodiode, a photomultiplier tube, or the like can be used. By using a small photodetector, not only can the size of the entire viscosity measuring apparatus be reduced, but also the cost can be simplified and reduced. In addition, an electrical device such as an electrostatic capacity type motion meter, a magnetic device using particles as magnetic particles and using a magnetic sensor, a sound device such as an ultrasonic motion meter, or the like may be used.
(Form 20)
Light (reflection light, transmitted light, scattered light, fluorescence, etc.) due to the interaction of reflection, absorption, scattering, fluorescence, and the like by the particles is generated when the particles are irradiated with light, but is not generated when the particles are not irradiated. Therefore, in the case where the motion is detected based on whether or not the particle remains at the light irradiation position with the particle measuring device having the photodetector, the motion can be detected by detecting the presence or absence of the interaction light due to the particle. .
(Form 21)
As the flow measurement device, a microscope, a video camera, an image analysis device, or the like can be used. When the flow measuring device performs automatic measurement, it is preferable to have a photodetector.
(Form 22)
The flow measuring device is not necessarily provided separately from the particle measuring device. It can also be used as a particle measuring device.

(First Embodiment) FIG. 1 schematically shows a schematic configuration of a viscosity measuring apparatus according to a first embodiment embodying the present invention. The viscosity measuring apparatus includes a laser light source 2, a galvanometer mirror 6, a condenser lens 8, a particle measurement microscope 30, a flow measurement microscope 26, a video camera 28 connected thereto, a computer 34, and a table. The glass plate 22 is set on the table 24 and used. A liquid 20 whose viscosity is to be measured is applied to the upper surface of the glass plate 22. Although the glass plate 22 is set horizontally on the table 22, if the liquid 20 has a high viscosity, the liquid 20 applied to the upper surface of the glass plate 22 continues to flow for a long time.

About 10 ⁻³ wt% of spherical silica having a radius of 1 μm and a very small particle size distribution range is added to the liquid 20. The liquid 20 is applied on the glass plate 22 so as to have a film thickness of 50 μm. In FIG. 1, only three spherical silicas 14, 16, and 18 are shown for convenience of explanation, but actually, many spherical silicas are included. These spherical silicas 14, 16, and 18 exist in a minute range in which the liquid 20 can be regarded as flowing at the same speed in the same direction. The liquid 20 has a high viscosity and continues to flow for a long time after being applied to the upper surface of the glass plate 22.

  The laser light source 2 is a YAG laser having a wavelength of 523 nm. The condensing lens 8 condenses the laser 4 at one point in the liquid 20 having a film thickness of 50 μm. If particles are present at the collection position, the particles are trapped at the collection position.

  The galvanometer mirror 6 displaces the condensing position 10 so that the condensing position draws a circle in a plane parallel to the upper surface of the glass plate 22. The particles 16 trapped at the condensing position 10 move in the liquid 20 following the condensing position 10 drawing a circle. When the particles 16 trapped at the condensing position 10 move in the liquid 20, a viscous resistance force acts on the particles 16 from the liquid 20. The viscous resistance force tries to overcome the trapping of the particles 16 at the condensing position 10.

By using the microscope 30, the observer can observe the movement of the trapped particles 16. The observer presses the specific switch 32 when the trapped particles 16 are separated from the condensing position 10 due to the viscous resistance force of the liquid. It is input to the computer 34 that the specific switch 32 has been pressed, and it is possible to specify when the trapped particles 26 have left the condensing position 10.
The video of the microscope 26 is captured and recorded by the video camera 28 and image analysis is performed by the computer 34. The computer 34 analyzes the images of the untrapped particles 14 and 18 (hereinafter referred to as free particles 14 and 18) photographed by the video camera 28, so that the liquid 20 at the site where the trapped particles 16 are present. Flow velocity and flow direction can be measured.

The viscosity measuring method according to the first embodiment will be described. Prior to the measurement, a calibration curve illustrated in FIG. 3 is obtained.
In order to obtain a calibration curve, particles having a known radius are suspended in a liquid having a known viscosity by an existing method that does not use a laser, and the particles are trapped at a condensing position by a laser. In this state, the condensing position is displaced with respect to the table 24, and the condensing position with respect to the table 24 when the particles cannot be trapped in the condensing position due to the viscous resistance acting on the trapped particles. The moving speed and the output of the laser trapping the particles are detected. The relationship between "viscosity, speed, and laser output" when it is no longer possible to trap particles against various liquids with different viscosities by changing the laser output, changing the moving speed By arranging, the calibration curve of FIG. 3 can be obtained.
However, when obtaining a calibration curve, it is important not to use a flowing liquid. Even if it is a high viscosity liquid, if a considerable amount of time is taken, the flow is completed. If measurement is performed using the liquid that has finished flowing, the moving speed of the light collecting position with respect to the table 24 becomes equal to the relative speed of the liquid at the particle and the particle existing site. The calibration curve in FIG. 3 illustrates the relationship between “viscosity, the relative velocity of particles and the liquid at the particle location, and laser output”.

After obtaining the calibration curve, the viscosity measurement process for the liquid 20 with unknown viscosity is started. First, the movements of the free particles 14 and 18 are observed by the microscope 26, the video camera 28, and the computer 34. The arrows 36 and 38 in FIG. 2 exemplify the moving direction and moving speed of the observed free particles 14 and 18, and it was measured that constant velocity linear flow was performed at a speed of 2 μm / s in the illustrated direction. An example is shown.
Next, the condensing position 10 of the laser light source 2 is adjusted by the galvanometer mirror 6 to trap the particles 16. In a state where the particles 16 are trapped, the converging position is moved by the galvanometer mirror 6 so as to have a circular motion with a radius of 5 μm and a period of 10 s. It was observed that the trapped particles 16 moved circularly as indicated by an arrow 12 following the converging position 10. When the period was decreased while maintaining the laser output constant, it was observed that the trapped particles 16 were detached from the condensing position 10 in the direction of the arrow 40 as shown in FIG. 2 when the period was 4.5 s. . The speed of the trapped particles 16 with respect to the table 24 at the critical time was calculated to be 7 μm / s.

Since the directions of the arrows 36 and 38 in FIG. 2 and the direction of the arrow 40 are opposite directions, it can be seen that the relative velocity v of the trapped particles 16 with respect to the liquid 20 at the critical time is 9 μm / s. That is, it can be seen that the relative velocity of the liquid between the particle and the particle existing site is 9 μm / s. Therefore, from the calibration curve of FIG. 3, it is found that the viscosity of the liquid 20 whose viscosity is unknown is 1 Pa · s.
From the above, it can be seen that the viscosity (1 Pa · s) measured by the first example is in good agreement with the viscosity (1 Pa · s) measured by an existing method not using a laser, and the viscosity was measured with high accuracy. .

(Comparative Example 1) Using the 7 μm / s velocity of the particles 16 with respect to the glass plate 22 when the trap observed in the first example is broken, and referring to the calibration curve of FIG. It is required to be 3 Pa · s.
It can be seen that the viscosity (1.3 Pa · s) measured by Comparative Example 1 does not match the viscosity (1 Pa · s) measured by an existing method without using a laser, and a measurement error occurs.
It is necessary to measure the flow velocity of the liquid at the particle existence site and to measure the relative velocity between the particle and the liquid at the particle existence site. By measuring this, it can be seen that an accurate viscosity can be measured.

(Second Embodiment) FIG. 4 is a view schematically showing a schematic configuration of a viscosity measuring apparatus according to a second embodiment embodying the present invention. Here, about the structure similar to the viscosity measuring apparatus of 1st Example, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.
The viscosity measuring apparatus mainly includes a laser light source 12, a mirror 7, a condenser lens 8, a particle measuring microscope 30, a video camera 46 connected thereto, a flow measuring microscope 26 and a video connected thereto. The camera 28, the computer 34, a relative movement device 42, a table 24, and the like, and the relative movement device 42 is installed on the table 24. A glass plate 22 coated with the liquid 20 is set horizontally on the relative movement device 42.

About 10 ⁻³ wt% of borosilicate glass having a radius of 1 μm and a very small particle size distribution range is added to the liquid 20. The liquid 20 is applied on the glass plate 22 so as to have a film thickness of 50 μm. In FIG. 4, only three borosilicate glasses 114, 116, and 118 are shown for convenience of explanation, but actually, more borosilicate glasses are included. These borosilicate glasses 116, 114, and 118 exist in a minute range in which the liquid 20 can be regarded as flowing at the same speed in the same direction.

  The laser light source 12 is a semiconductor laser having a wavelength of 680 nm. The mirror 7 is supported at a predetermined height by a stand (not shown) that is movably installed on the table 24 so that the laser beam is emitted from the laser light source 12 from above the liquid 20 vertically. The condensing lens 8 condenses the laser at one point in the liquid 20 having a film thickness of 50 μm and traps the particles.

  The relative movement device 42 incorporates an epizo element 44. The relative movement device 42 reciprocally moves in the direction of the arrow 48 to move the glass plate 22. While the liquid 20 moves with the fine movement of the glass plate 22, the particles 116 are fixed while being trapped at the condensing position. For this reason, a viscous resistance force acts on the particles 116 from the liquid 20. The viscous resistance force tries to overcome the trapping of the particles 16 at the condensing position 10.

The video of the microscope 30 is photographed and recorded by the video camera 46 and image analysis is performed by the computer 34. By analyzing the image of the trapped particles 116 photographed by the video camera 46 with the computer 34, the moving speed and moving direction of the trapped particles 116 can be measured.
The video of the microscope 26 is captured and recorded by the video camera 28 and image analysis is performed by the computer 34. By analyzing the images of the free particles 114 and 118 photographed by the video camera 28 by the computer 34, the flow velocity and the flow direction of the liquid 20 at the site where the trap particles 116 are present can be measured.

Next, the viscosity measuring method according to the second embodiment will be described. First, a calibration curve as shown in FIG. 3 is obtained in advance.
Subsequently, while observing the particles in the liquid 20 with the microscope 30, the mirror 7 is moved to move the condensing position 10, and the particles 116 are trapped from vertically above.
In a state where the particles 116 are trapped, the glass plate 22 is moved by the relative movement device 44 at a speed of 1 μm / s. It was observed that the trapped particles 116 remained at the condensing position 10. When the moving speed is exponentially increased to 1.5 μm / s and 2.3 μm / s while keeping the laser output constant, the trapped particles 116 are detached from the converging position 10 when the speed is 7.5 μm / s. Was observed. The movement of the glass plate 22 at the critical time is shown in FIG. 5, and when the glass plate 22 moves in the direction of the arrow 48, the trapped particles 116 are detached from the condensing position 10.
On the other hand, the free particles 114 and 118 were observed to move in the direction of the arrow 52 in FIG. Considering the movement of the glass plate 22 indicated by the arrow 48, the liquid flow can be measured as an arrow 50.

If the movement of the arrow 48, which can be regarded as the relative movement of the trapped particles 116, is corrected by the flow of the arrow 50, the relative movement of the trapped particles 116 is considered to be a uniform linear motion at a speed of 9 μm / s. That is, it can be seen that the relative velocity of the liquid between the particle and the particle existing site is 9 μm / s. Therefore, from the calibration curve as shown in FIG. 3, it is found that the viscosity of the liquid 20 whose viscosity is unknown is 1 Pa · s.
From the above, it can be seen that the viscosity (1 Pa · s) measured by the first example is in good agreement with the viscosity (1 Pa · s) measured by an existing method not using a laser, and the viscosity was measured with high accuracy. .

(Third Embodiment) In the third embodiment, the fluid flow motion is not directly measured. In this embodiment, particles are moved in a plurality of directions with respect to the table. In the third embodiment, the same viscosity measuring apparatus as in the first embodiment or the second embodiment is used.
For example, as shown in FIG. 6, the particles are moved relative to the table 24 in three directions. Here, each moving direction is deviated by 120 degrees. The moving speeds u1, u2, u3 in these directions are measured.
The measured moving speeds u1, u2, and u3 include the liquid flow speed F. The flow rate F is unknown, but each flow rate F should be constant. Also, the magnitude of | TB |, which is the relative velocity between the particles and the liquid, should be constant. Therefore, if the moving speeds u1, u2, and u3 are measured, the flow speed F can be calculated mathematically, and the relative speed of the liquid at the particle and the particle existing site can be calculated.

Furthermore, as shown in FIG. 7, if the relative movement is performed in a total of four directions, ie, two directions opposite to the x direction and two directions opposite to the y direction, the calculation is further facilitated. In this case, the magnitude of | TB |, which is the relative velocity between the particles and the liquid, can be obtained by the equation shown in the lower part of FIG. Therefore, if the moving speeds u1, u2, u3, u4 are known, the flow speed F can be mathematically calculated.
In these processes, it is not necessary to explicitly calculate the flow velocity of the liquid, and the relative velocity of the particles and the liquid can be calculated directly. The flow velocity of the liquid is calculated implicitly, and the relative velocity between the particle and the liquid is calculated using this.

(Fourth Embodiment) FIG. 8 is a view schematically showing a schematic configuration of a viscosity measuring apparatus according to a fourth embodiment embodying the present invention.
The viscosity measuring apparatus mainly includes a laser irradiation device 204, a condenser lens 208, a particle measuring microscope 230, a video camera 228 connected thereto, a computer 234, a table 224, and the like. On the table 224, a glass plate 222 coated with the liquid 220 is set horizontally.

  The liquid 220 includes paint particles having a radius of 1 μm and a very small particle size distribution range. The liquid 220 is applied on the glass plate 222 so as to have a film thickness of 50 μm. In FIG. 8, only one paint particle 216 is shown for convenience of explanation, but actually, more paint particles are included.

  The laser irradiation device 204 is configured such that a laser light source 202 and a condenser lens 208 are fixed to a gantry. The laser light source 202 is a YAG laser having a wavelength of 1064 nm. The laser irradiation device 204 is supported at a predetermined height by a stand (not shown) installed on the table 224 so as to irradiate the laser from the laser light source 202 obliquely from above the liquid 220. The laser irradiation device 204 condenses the laser on the particles contained in the liquid 220 from the upper side by the condensing lens 208, and moves the particles by the light pressure of the laser.

  The video of the microscope 230 is captured and recorded by the video camera 228 and image analysis is performed by the computer 234. By analyzing the image of the particle 216 taken by the video camera 228 with the computer 234, the moving speed and moving direction of the particle 216 can be measured.

Next, the viscosity measuring method according to the fourth embodiment will be described. Prior to the measurement, a calibration curve illustrated in FIG. 11 is obtained.
In order to obtain a calibration curve, particles having a known radius are suspended in a liquid having a known viscosity by an existing method that does not use a laser, and the particles are moved by light pressure using a laser. The moving speed with respect to the table 24 when the particles move and the output of the laser that moved the particles are detected. By organizing the relationship between “viscosity, speed, and laser output” when changing the output of the laser, changing the moving speed, and moving the particles to various liquids with different viscosities, Eleven calibration curves can be obtained. The calibration curve in FIG. 11 illustrates the relationship between “viscosity, the relative velocity of the liquid at the particle and particle location, and the laser output” when the liquid that has finished flowing is used.

  Subsequently, the liquid 220 was observed with the microscope 230 and attention was paid to arbitrary particles 216. The radius of the particle 216 was 1 μm. When the image of the position of the particle 216 was analyzed, it was observed that the particle 216 moved at 1 μm / s in the direction of the arrow 240 in FIG. When the laser irradiation device 204 was moved and the laser was irradiated from the upper left side of FIG. 9, it was observed that the particles 216 moved in the direction of the arrow 242 due to the light pressure of the laser. The motion of the particles 216 at this time was a constant velocity linear motion with a speed of 10 μm / s with respect to the table 224.

Since the direction of the arrow 240 in FIG. 9 and the direction of the arrow 242 are the same direction on a straight line, the velocity of the particles 216 after irradiation with the laser is considered to be a uniform linear motion of 9 μm / s. That is, it can be seen that the relative velocity of the liquid between the particle and the particle existing site is 9 μm / s. Therefore, it is found from the calibration curve shown in FIG. 11 that the viscosity of the liquid 220 whose viscosity is unknown is 1 Pa · s.
From the above, it can be seen that the viscosity (1 Pa · s) measured by the fourth example coincides with the viscosity (1 Pa · s) measured by an existing method not using a laser, and the measurement was performed with high accuracy.

(Fifth Embodiment) FIG. 10 is a view showing the movement of particles observed by the viscosity measuring method of the fifth embodiment embodying the present invention. In the fifth embodiment, the same viscosity measuring apparatus as in the fourth embodiment is used.
The viscosity measuring method according to the fifth embodiment will be described. Prior to the measurement, a calibration curve as illustrated in FIG. 11 is obtained.
Subsequently, when the laser irradiation device 204 is moved to move the particle 216 to the laser irradiation position and the laser is irradiated from the upper left side of FIG. 10, the particle 216 is moved in the direction of the arrow 242 by the light pressure of the laser. Observed. The movement of the particles 216 at this time was a constant-velocity linear movement at a speed of 10 μm / s with respect to the table 224. Slightly, when the laser irradiation device 204 was moved and the laser was irradiated from the upper right side of FIG. 10, it was observed that the particles 216 moved in the direction of the arrow 244 (opposite to the arrow 242) by the optical pressure of the laser. The movement of the particles 216 at this time was a constant-velocity linear movement at a speed of 8 μm / s with respect to the table 224.

The direction of the arrow 242 in FIG. 10 and the direction of the arrow 244 are opposite to each other on a straight line. Therefore, it can be seen that the flowing direction of the liquid is parallel to the moving direction of the particles 216 as indicated by an arrow 240. From this, it can be calculated that the velocity in the direction of the arrow 242 and the average velocity of the velocity in the direction of the arrow 244 are 9 μm / s, which is the relative velocity of the liquid in the particle and the particle existence site. In this process, it is not necessary to measure the flow velocity of the liquid, and the relative velocity between the particles and the liquid can be calculated directly.
From the calibration curve shown in FIG. 11, it is found that the viscosity of the liquid 220 whose viscosity is unknown is 1 Pa · s.
From the above, it can be seen that the viscosity (1 Pa · s) measured by the fifth example coincides with the viscosity (1 Pa · s) measured by an existing method not using a laser, and the measurement was performed with high accuracy.

(Sixth Embodiment) FIG. 12 is a diagram showing the movement of particles observed by the viscosity measurement method of the sixth embodiment embodying the present invention. In the sixth embodiment, the same viscosity measuring apparatus as in the fourth embodiment is used.
As shown in FIG. 12, the light pressures at the speeds v1 and v2 with respect to the table are applied to the particles. The moving speeds u1 and u2 in each direction in which the particles have moved by these light pressures are measured.
The light pressure velocities v1 and v2 applied to the particles include only the x-direction component and do not include the y-direction component. Therefore, the measured y-direction components of the moving velocities u1 and u2 all originate from the y-direction component of the flow velocity F. The x-direction component of the particle moving velocity u1 is the sum of the x-direction component of the flow velocity F and the x-direction component of the light pressure velocity v1, and the x-direction component of the particle moving velocity u2 The x direction component of the velocity F is subtracted from the velocity v2 of the light pressure. Accordingly, by obtaining the average of the velocities u1 and u2 as in the equation shown in the lower part of FIG. 12, the magnitudes of v1 and v2 that are the relative velocities of the particles and the liquid can be calculated.
In this process, it is not necessary to measure the flow velocity of the liquid, and the relative velocity between the particles and the liquid can be calculated directly.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

It is a figure which shows schematic structure of the viscosity measuring apparatus of 1st Example. It is a figure which shows the motion of the particle | grains observed by the viscosity measuring method of 1st Example. It is a figure which shows the example of a calibration curve. It is a figure which shows schematic structure of the viscosity measuring apparatus of 2nd Example. It is a figure which shows the motion of the particle | grains observed by the viscosity measuring method of 2nd Example. It is a figure explaining the viscosity measuring method of 3rd Example. It is a figure explaining the other viscosity measuring method of 3rd Example. It is a figure which shows schematic structure of the viscosity measuring apparatus of 4th Example. It is a figure which shows the motion of the particle | grains observed by the viscosity measuring method of 4th Example. It is a figure which shows the motion of the particle | grains observed by the viscosity measuring method of 5th Example. It is a figure which shows the example of a calibration curve. It is a figure which shows the motion of the particle | grains observed by the viscosity measuring method of 6th Example.

Explanation of symbols

2: Laser light source,
4: Laser light,
6: Galvano mirror,
7: Mirror,
8: Condensing lens,
10: Condensing position,
14, 18: free particles,
16: trap particles,
20: liquid,
22: Glass plate,
24: Table
26: Flow measurement microscope,
28: Video camera,
30: Particle measurement microscope,
32: Specific switch,
34: Computer

Claims (10)

Irradiating a laser to move particles suspended in the liquid relative to the liquid support;
Identifying a relative velocity of particles moving relative to the liquid support relative to the liquid support;
Correcting the flow velocity of the liquid flowing relative to the liquid support to the specified relative velocity, and calculating the relative velocity of the liquid at the particle and the particle location site;
Calculating the viscosity of the liquid using the calculated particle and the relative velocity of the liquid at the particle location;
Method for measuring viscosity of liquid containing   The particle is moved with respect to the liquid support by irradiating a laser to trap the particle at a laser condensing position and moving the condensing position with respect to the liquid support. Viscosity measurement method.   The viscosity measuring method according to claim 1, wherein the particles are moved relative to the liquid support by irradiating a laser to apply light pressure to the particles.   4. The viscosity measuring method according to claim 1, wherein the flow rate of the liquid at the particle existing site is directly measured.   By moving particles in multiple directions with respect to the liquid support, the flow rate of the liquid flowing with respect to the liquid support is potentially identified from the movement speed of the particles in each direction, and the relative liquids at the site where the particles are present 4. The method for measuring viscosity according to claim 1, wherein a speed is calculated. A step of trapping particles floating in the liquid by irradiating a laser at the condensing position of the laser;
While moving the collection position relative to the liquid support while increasing the moving speed of the collection position relative to the liquid support and / or decreasing the laser power trapping particles, Identifying the relative velocity and laser power of the liquid support and the collection position when the particles trapped at the light position are detached from the collection position;
The relative velocity between the liquid support and the condensing position at the time of separation from the condensing position is corrected for the flow velocity of the liquid relative to the condensing position. Calculating the "speed",
Calculating the viscosity of the liquid from the calculated laser output relative to the calculated “relative velocity of the particle and the liquid at the site where the particle exists”
Method for measuring viscosity of liquid containing A process of irradiating a laser and moving the particles suspended in the liquid by applying light pressure;
Identifying the speed of particles moving by light pressure,
Correcting the flow rate of the liquid at the particle location to the specified particle velocity and calculating the relative velocity of the liquid at the particle location;
Calculating the viscosity of the liquid using the calculated particle and the relative velocity of the liquid at the particle location;
Method for measuring viscosity of liquid containing A liquid support for supporting the liquid,
A laser irradiation apparatus for moving particles suspended in a liquid by irradiating a laser with respect to a liquid support;
Means for determining the moving speed of the particles relative to the liquid support;
Means for correcting the flow velocity of the liquid at the particle existence site relative to the liquid support to the moving speed, and calculating the relative velocity of the liquid at the particle and the particle existence site;
An apparatus for measuring an index indicating the viscosity of a liquid. A liquid support for supporting the liquid,
A laser irradiation device that traps particles floating in the liquid at the focusing position;
Means for relatively moving the liquid support and the light collecting position;
Means for determining the moving speed of the particles relative to the liquid support;
Means for at least potentially identifying the flow rate of the liquid flowing relative to the liquid support;
Means for identifying the relative velocity of the liquid at the particle-existing site when the particle leaves the condensing position;
An apparatus for measuring an index indicating the viscosity of a liquid. A liquid support for supporting the liquid,
A laser irradiation device that moves the particles by applying light pressure to the particles floating in the liquid;
Means for determining the moving speed of the particles relative to the liquid support;
Means for at least potentially identifying the flow rate of the liquid flowing relative to the liquid support;
Means for identifying the relative velocity of the liquid at the particle and the particle location,
An apparatus for measuring an index indicating the viscosity of a liquid.

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