JP6818281B2 - Measuring device - Google Patents

Description

The techniques disclosed herein relate to measuring devices.

Conventionally, a laser Doppler type measuring device for measuring the speed of an object to be measured has been known. The laser Doppler type measuring device includes a laser light irradiation device, a light receiving device, and a processing device. The laser light irradiation device irradiates a moving measurement object with a laser beam. The laser light emitted from the laser light irradiating device is scattered when it hits a moving measurement object, and scattered light is generated. The light receiving device receives the scattered light generated at that time. When the light receiving device receives the scattered light, the processing device calculates the velocity of the object to be measured based on the frequency of the scattered light. The processing device calculates the speed of the measurement object by a calculation method based on a known Doppler shift.

Patent Document 1 (Japanese Unexamined Patent Publication No. 5-66226) discloses a measuring device including a laser light irradiating device that irradiates a moving measurement object with laser light from two different directions. The measuring device of Patent Document 1 includes a laser light irradiation device, a light receiving device, and a processing device. The laser light irradiating device irradiates the moving measurement object with the first laser light and the second laser light. The first laser beam and the second laser beam are emitted from different directions toward the object to be measured. The first laser beam and the second laser beam emitted from the laser light irradiating device are scattered when they hit a moving measurement object, and the scattered light is generated. The light receiving device receives each scattered light generated at that time. Further, in the measuring device of Patent Document 1, the light receiving device includes a condensing lens, and the condensing lens collects and receives various scattered lights. When the light receiving device receives the scattered light of the first laser light and the second laser light, the processing device calculates the speed of the measurement object based on the frequency of each scattered light. The processing device calculates the speed of the measurement object by a calculation method based on a known Doppler shift.

A measuring device that measures the velocity of an object to be measured may measure the velocity of particles in a fluid flowing through a flow path. That is, the object to be measured may be particles in a fluid. As the particles in the fluid, for example, red blood cells in blood and the like can be considered. The measuring device will measure the speed of red blood cells in the blood flowing through the flow path. This makes it possible to know the flow velocity of blood.

In general, innumerable particles exist in the fluid flowing through the flow path. For example, there are innumerable red blood cells in the blood. Innumerable particles are diffused in the fluid. Therefore, among the innumerable particles, for example, some particles pass through the central portion of the flow path and some particles pass through the peripheral portion of the flow path. Also, the velocities of innumerable particles in fluids vary. Some particles have a high velocity, while others have a slow velocity.

When measuring the velocity of particles in a fluid flowing through a flow path using the measuring device of Patent Document 1, a first laser beam and a second laser beam are used from the laser light irradiation device toward an arbitrary measurement point in the flow path. Irradiate with laser light. The first laser beam and the second laser beam are emitted from different directions toward the measurement point in the flow path. The first laser beam and the second laser beam emitted from the laser light irradiating device are scattered when they hit the particles passing through the measurement point, and the scattered light is generated. The light receiving device receives each scattered light generated at that time. The light receiving device collects and receives various scattered lights by a condensing lens. Then, the processing device calculates the velocity of the particles passing through the measurement point based on the frequency of each scattered light received by the light receiving device.

In order to accurately measure the velocity of the particles passing through the measurement point, it is preferable that the light receiving device sufficiently receives the scattered light generated by the particles passing through the measurement point. Further, in order to accurately measure the velocity of particles, when irradiating the first laser beam and the second laser beam from the laser light irradiation device toward the measurement point, each laser beam is irradiated only to the measurement point. do it. Then, the first laser beam and the second laser beam hit only the particles passing through the measurement point, and only the scattered light generated when each laser beam hits the particles can be extracted. Therefore, ideally, when irradiating the first laser beam and the second laser beam, it is preferable to irradiate the first laser beam and the second laser beam so that they overlap only at the measurement point. However, in reality, it is difficult to irradiate only the measurement point with the first laser beam and the second laser beam, and the first laser beam and the second laser beam are also present around the measurement point due to light diffusion or the like. The laser light is irradiated. That is, the first laser beam and the second laser beam are irradiated so as to overlap each other at the measurement point and its periphery due to light diffusion or the like. Then, when the first laser beam and the second laser beam emitted from the laser light irradiation device hit the particles and scatter, they not only hit the particles passing through the measurement point and scatter, but also the particles passing around the measurement point. Also, the first laser beam and the second laser beam hit and scatter. Therefore, not only the scattered light generated by the particles passing through the measurement point but also the scattered light generated by the particles passing around the measurement point are taken out. Then, since the velocities of the innumerable particles in the fluid are various, the light receiving device receives various scattered light generated by the particles having various velocities. As a result, the processing device calculates the velocity of the particles based on the frequencies of various scattered lights, and it becomes difficult to accurately measure the velocity of the particles in the fluid flowing through the flow path. Further, in the measuring device of Patent Document 1, since the light receiving device collects and receives various scattered light by the condenser lens, the processing device calculates the velocity of the particles based on the frequencies of the various scattered light. It will be. As a result, it becomes difficult to accurately measure the velocity of particles in the fluid flowing through the flow path. As described above, in the measuring device of Patent Document 1, not only the scattered light generated by the particles passing through the measurement point but also the extra scattered light is received, so that it is difficult to accurately measure the velocity of the particles. Become. The measuring device of Patent Document 1 has no problem when the speed of the object to be measured is uniform, but causes a problem when the speed varies like particles in a liquid flowing in a pipe. Therefore, the present specification provides a technique capable of sufficiently receiving the necessary scattered light while suppressing the reception of the excess scattered light.

The measuring device disclosed in the present specification is a measuring device for measuring the velocity of particles in a fluid flowing through a flow path. This measuring device includes a laser light irradiation device and a light receiving device. The laser light irradiation device has a first laser beam traveling toward the measurement point in the flow path and a first laser light traveling toward the measurement point in the flow path from a direction different from the first laser light. Irradiate the laser beam of 2. The light receiving device receives scattered light generated when the first laser light and the second laser light emitted from the laser light irradiating device hit the particles passing through the measurement point. The light receiving device includes a light receiving element and a hollow light passing hole formed between the light receiving surface of the light receiving element and the measurement point. The light passing hole extends in a direction from the measuring point toward the light receiving element, and scattered light generated by particles passing through the measuring point passes through the light passing hole and reaches the light receiving surface of the light receiving element. It is configured to be incident. This measuring device is characterized in that it satisfies the following relational expressions (1) and (2).
2YH / (X + Y) ≤ D <H ... (1)
Y ≤ A <X ... (2)

However, in the above relational expression, D is the distance between the incident port of the light passing hole and the light receiving surface of the light receiving element. H is the distance between the light receiving surface of the light receiving element and the measuring point. X is a width in a range in which the intensity of the laser beam formed by overlapping the first laser beam and the second laser beam traveling toward the measurement point is equal to or higher than a predetermined intensity. Y is the width of the light receiving surface of the light receiving element. A is the width of the incident port of the light passing hole.

According to such a configuration, the scattered light generated by the particles passing through the measurement point passes through the light passing hole and is incident on the light receiving element. However, when the first laser beam and the second laser beam are irradiated from the laser light irradiation device, not only the measurement point but also the periphery of the measurement point is irradiated with the first laser beam and the second laser beam. It may be done. Then, scattered light is generated not only by the particles passing through the measurement point but also by the particles passing around the measurement point. At this time, according to the above configuration, since the light passing hole is provided, it is possible to suppress the scattered light generated by the particles passing around the measurement point from entering the light receiving element. That is, according to the above configuration, since the light passing hole extends in the direction from the measuring point to the light receiving element between the measuring point and the light receiving element, the scattered light generated by the particles passing through the measuring point is the light passing hole. However, the scattered light generated by the particles passing around the measurement point is less likely to be incident on the light receiving element due to the presence of the light passing hole. As a result, it is possible to suppress receiving excess scattered light.

Further, in a configuration provided with a light passing hole, if the position of the incident port of the light passing hole is far from the measurement point, the incident range to the light passing hole is widened, so that scattered light generated around the measurement point is generated. It becomes easy to enter the light passage hole. However, according to the above configuration, the position of the incident port of the light passing hole can be brought closer to the measurement point by satisfying the relational expression (1). As a result, it is possible to suppress the expansion of the incident range to the light passing hole, so that the scattered light generated around the measurement point is less likely to be incident on the light passing hole. Further, according to the above configuration, by satisfying the relational expression (2), it is possible to prevent the width A of the incident port of the light passing hole from becoming too narrow. As a result, the scattered light from the measurement point toward the light receiving element can be sufficiently received. Therefore, it is possible to sufficiently receive the necessary scattered light while suppressing the reception of the excess scattered light. As a result, the velocity of particles in the fluid flowing through the flow path can be accurately measured.

In the above measuring device, the following relational expression (3) may be satisfied.
D = H (A + Y) / (X + Y) ... (3)

According to such a configuration, by satisfying the relational expression (3), the light receiving element receives the scattered light generated by the particles passing through the measurement point while suppressing the reception of the scattered light generated around the measurement point. It is possible to receive light by using the entire light receiving surface of.

Further, the above-mentioned measuring device may satisfy the following relational expression (4).
A = Y ... (4)

According to such a configuration, by aligning the width of the incident port of the light passing hole with the width of the light receiving surface of the light receiving element, the scattered light passing from the measurement point through the light passing hole and directed to the light receiving element is efficiently received. be able to.

Further, in the above measuring device, the surface roughness of the inner peripheral surface of the light passing hole may be equal to or higher than the wavelength of the first laser beam and equal to or higher than the wavelength of the second laser beam.

As described above, the first laser beam and the second laser beam are also irradiated around the measurement point, and scattered light may be generated around the measurement point. Then, various scattered lights traveling in various directions are generated around the measurement point. In addition, scattered light generated around the measurement point may enter the light passing hole and hit the inner peripheral surface of the light passing hole and be reflected. At this time, according to the above configuration, various scattered light reflected on the inner peripheral surface of the light passing hole can be diffusely reflected. As a result, the scattered light reflected on the inner peripheral surface of the light passing hole travels in various directions, so that the scattered light traveling toward the light receiving element can be reduced. Therefore, it is possible to suppress the scattered light generated around the measurement point from entering the light receiving element. The wavelength of the first laser beam, the wavelength of the second laser beam, and the wavelength of the scattered light are approximate values.

Further, the inner peripheral surface of the light passing hole may be inclined with respect to the light receiving surface of the light receiving element.

According to such a configuration, even if the scattered light generated around the measurement point is reflected by the inner peripheral surface of the light passing hole, the inner peripheral surface is inclined with respect to the light receiving surface of the light receiving element. It is possible to suppress the reflected scattered light from traveling toward the light receiving surface of the light receiving element. Therefore, it is possible to prevent the scattered light generated around the measurement point from being incident on the light receiving surface of the light receiving element. The fact that the inner peripheral surface of the light passing hole is inclined with respect to the light receiving surface of the light receiving element is a concept that does not include a configuration in which the inner peripheral surface of the light passing hole is perpendicular to the light receiving surface of the light receiving element. is there.

Further, the color of the inner peripheral surface of the light passing hole may be black.

According to such a configuration, it is possible to suppress the scattered light generated around the measurement point from being reflected by the inner peripheral surface of the light passing hole. Therefore, it is possible to suppress the scattered light generated around the measurement point from entering the light receiving element.

Further, the inner peripheral surface of the light passing hole may be made of a low-reflecting material.

According to such a configuration, it is possible to suppress the scattered light generated around the measurement point from being reflected by the inner peripheral surface of the light passing hole. Therefore, it is possible to suppress the scattered light generated around the measurement point from entering the light receiving element.

It is a figure which shows the schematic structure of the measuring apparatus which concerns on Example. It is a figure which shows the schematic structure of the light receiving device which concerns on Example. It is a side view which shows the schematic structure of the light receiving element which concerns on Example. It is a top view which shows the schematic structure of the light receiving element which concerns on Example. It is a block diagram of the measuring apparatus which concerns on Example. It is a figure which shows the positional relationship of a light passing hole, a measuring point, and a light receiving element. It is a figure which shows the distribution of the intensity of the laser beam formed by overlapping the 1st laser beam and the 2nd laser beam. It is a figure which shows typically the positional relationship in FIG. It is a top view which shows an example of a light passing hole. It is a top view which shows another example of a light passing hole. It is a top view which shows still another example of a light passing hole. It is sectional drawing which shows still another example of a light passing hole. It is a figure which shows the schematic structure of the measuring apparatus which concerns on another Example.

Examples will be described below with reference to the accompanying drawings. As shown in FIG. 1, the measuring device 1 according to the embodiment is used by being fixed to a transparent tube 61 by a fixture 62. A flow path 60 is formed in the pipe 61. The measuring device 1 is a device that measures the velocity v of the particles R in the fluid F flowing through the flow path 60. This makes it possible to know the flow velocity of the fluid F.

Innumerable particles R are present in the fluid F flowing through the flow path 60. Innumerable particles R are diffused and exist in the fluid F. Therefore, among the innumerable particles R, for example, some particles R pass through the central portion of the flow path 60, and some particles R pass through the peripheral portion of the flow path 60. Also, the velocities of the innumerable particles R vary. Some particles R have a high velocity, and some particles R have a low velocity. When measuring the velocity v of the particles R in the fluid F flowing through the flow path 60, the velocity v of the particles R may be measured by focusing on a specific measurement point 10 in the flow path 60. The position of the measurement point 10 in the flow path 60 is not particularly limited, but for example, the velocity v of the particles R passing through the center of the flow path 60 is measured with the center of the flow path 60 as the measurement point 10. can do. Generally, in the case of laminar flow, it is known that the flow velocity of the fluid F flowing through the central portion of the flow path 60 corresponds to twice the average flow velocity of the fluid F flowing through the entire flow path 60.

Examples of the fluid F flowing through the flow path 60 include blood. Examples of the particles R in the fluid F include red blood cells. The speed of red blood cells in blood can be measured by the measuring device 1. This makes it possible to know the flow velocity of blood. In the medical field, extracorporeal circulation may be performed in which the blood flowing in the patient's body is sent out of the body and the blood sent out of the body is sent back into the body. In this extracorporeal circulation, the extracorporeal circulation tube is connected to the patient's blood vessel, the blood flowing through the patient's blood vessel flows into the extracorporeal circulation tube, and the blood flowing through the extracorporeal circulation tube is returned to the patient's blood vessel again. Is done. The velocity v of red blood cells (particles R) in blood (fluid F) flowing through the extracorporeal circulation tube 61 can be measured by the measuring device 1 shown in FIG.

As shown in FIG. 1, the measuring device 1 includes a laser light irradiation device 2, a light receiving device 3, and a processing device 9. The laser light irradiation device 2 includes a light emitting element 21, a collimator lens 22, a diffraction grating 23, a first mirror 241 and a second mirror 242. The light emitting element 21 is, for example, a laser diode (LD). The light emitting element 21 is arranged so as to face the collimator lens 22. The light emitting element 21 emits the laser beam L toward the collimator lens 22. The laser beam L emitted by the light emitting element 21 is incident on the collimator lens 22. The light emitting element 21 emits the laser beam L on the side opposite to the direction in which the first mirror 241 and the second mirror 242 are arranged. The light emitting element 21 is arranged between the diffraction grating 23 and the first mirror 241 and the second mirror 242.

The collimator lens 22 is arranged between the light emitting element 21 and the diffraction grating 23. The collimator lens 22 emits the laser light L emitted by the light emitting element 21 as parallel light. The laser light L (parallel light) emitted from the collimator lens 22 is incident on the diffraction grating 23.

The diffraction grating 23 is arranged so as to face the collimator lens 22. The diffraction grating 23 is movable, and the diffraction grating 23 can be moved by the moving device 25. The moving device 25 can change the distance between the diffraction grating 23 and the first mirror 241 and the second mirror 242. The moving device 25 is, for example, a mechanical device, and the diffraction grating 23 can be moved up and down by turning a bolt. By changing the position of the diffraction grating 23, the position of the measurement point 10 in the flow path 60 can be changed. The diffraction grating 23 divides the laser light L incident on the diffraction grating 23 into a first laser light L1 and a second laser light L2 by utilizing the diffraction of light. The diffraction grating 23 is a reflection type diffraction grating. When the laser light L incident on the diffraction grating 23 is reflected by the diffraction grating 23, it is divided into a first laser light L1 and a second laser light L2. The laser light L emitted by the light emitting element 21 is reflected by the diffraction grating 23, so that the laser light L is divided into a first laser light L1 and a second laser light L2.

The first laser beam L1 and the second laser beam L2 generated by the diffraction grating 23 travel in different directions. The first laser beam L1 and the second laser beam L2 travel so as to be line-symmetric with respect to the line connecting the light emitting element 21 and the collimator lens 22. In the example shown in FIG. 1, the first laser beam L1 travels diagonally upward to the right, and the second laser beam L2 travels diagonally upward to the left. The first laser beam L1 travels toward the first mirror 241 and the second laser light L2 travels toward the second mirror 242. The wavelength of the first laser beam L1 and the wavelength of the second laser beam L2 are the same wavelength. Further, the frequency of the first laser beam L1 and the frequency of the second laser beam L2 are the same frequency.

The first mirror 241 and the second mirror 242 are arranged between the diffraction grating 23 and the tube 61. The first mirror 241 and the second mirror 242 face each other. The first laser beam L1 generated by the diffraction grating 23 is incident on the first mirror 241 and the second laser beam L2 is incident on the second mirror 242. The first mirror 241 includes a first reflecting surface 43. The second mirror 242 includes a second reflecting surface 44. The first reflecting surface 43 and the second reflecting surface 44 face each other. On the first reflecting surface 43, the first laser beam L1 incident on the first mirror 241 is reflected. On the second reflecting surface 44, the second laser beam L2 incident on the second mirror 242 is reflected.

The first laser beam L1 reflected by the first reflecting surface 43 of the first mirror 241 is incident on the flow path 60 in the tube 61. Further, the second laser beam L2 reflected by the second reflecting surface 44 of the second mirror 242 also enters the flow path 60 in the tube 61. The first laser beam L1 and the second laser beam L2 travel toward the measurement point 10 in the flow path 60.

The first laser beam L1 and the second laser beam L2 travel from different directions toward the measurement point 10. That is, the first laser beam L1 and the second laser beam L2 are irradiated from the laser beam irradiation device 2 toward the measurement point 10 in the flow path 60 from different directions. The first laser beam L1 travels from the downstream side of the flow path 60 toward the measurement point 10. The second laser beam L2 travels from the upstream side of the flow path 60 toward the measurement point 10. The first laser beam L1 and the second laser beam L2 interfere with each other at the measurement point 10 in the flow path 60 and overlap each other.

A fluid F (for example, blood) flows through the flow path 60, and innumerable particles R (for example, red blood cells) are present in the fluid F. Among the innumerable particles R, there are particles R that pass through the measurement point 10 in the flow path 60. When the first laser light L1 and the second laser light L2 hit the particles R passing through the measurement point 10, the first laser light L1 and the second laser light L2 are scattered. The first laser beam L1 and the second laser beam L2 hit the particles R from different directions. The first laser beam L1 hits the particles R from the downstream side of the flow path 60. That is, the first laser beam L1 hits the particle R from the traveling direction side of the particle R. On the other hand, the second laser beam L2 hits the particles R from the upstream side of the flow path 60. That is, the second laser beam L2 hits the particle R from the side opposite to the traveling direction of the particle R. Scattered light is generated when the first laser light L1 and the second laser light L2 hit the particles R and are scattered. The first scattered light P1 is generated by the first laser light L1 hitting the particles R and being scattered. Further, the second scattered light P2 is generated by the second laser light L2 hitting the particles R and being scattered. The first scattered light P1 and the second scattered light P2 generated by the scattering travel in various directions around the measurement point 10. Among them, there are a first scattered light P1 and a second scattered light P2 traveling from the measurement point 10 toward the light receiving device 3. The light receiving device 3 receives the first scattered light P1 and the second scattered light P2.

When the first laser beam L1 and the second laser beam L2 hit the particles R and scatter, their respective frequencies change. The frequency changes due to the Doppler shift. The frequency f1 of the first scattered light P1 generated by the scattering of the first laser light L1 is a frequency different from the frequency of the first laser light L1. Further, the frequency f2 of the second scattered light P2 generated by the scattering of the second laser light L2 is a frequency different from the frequency of the second laser light L2. Further, the frequency f1 of the first scattered light P1 and the frequency f2 of the second scattered light P2 are different frequencies from each other.

The light receiving device 3 is arranged between the tube 61 and the laser light irradiation device 2. The light receiving device 3 is arranged so as to face the flow path 60. The light receiving device 3 is fixed to the first mirror 241 and the second mirror 242 of the laser light irradiation device 2 by a fixture (not shown). As shown in FIG. 2, the light receiving device 3 includes a light receiving element 31 and a light-shielding box body 38. The light receiving element 31 is arranged in the box body 38.

The box body 38 includes a front wall 38a, a rear wall 38b, and a pair of side walls 38c and 38c. The front wall 38a is arranged between the tube 61 (not shown in FIG. 2) and the light receiving element 31. The rear wall 38b is arranged between the light receiving element 31 and the laser light irradiation device 2 (not shown in FIG. 2). The pair of side walls 38c, 38c are arranged between the front wall 38a and the rear wall 38b. The light receiving element 31 is fixed to the rear wall 38b of the box body 38. The front wall 38a of the box body 38 is arranged at a position away from the light receiving element 31. A hollow light passing hole 35 is formed in the front wall 38a.

The light passing hole 35 is formed between the measuring point 10 and the light receiving element 31. The light passage hole 35 extends in the direction from the measurement point 10 toward the light receiving element 31. It is preferable that the light passing hole 35, the measuring point 10, and the light receiving element 31 are located coaxially with each other. The light passage hole 35 includes an entrance port 36 and an exit port 37. The first scattered light P1 and the second scattered light P2 generated by the particles R passing through the measurement point 10 are incident on the light passing hole 35 from the incident port 36 of the light passing hole 35. The first scattered light P1 and the second scattered light P2 traveling from the measurement point 10 toward the light receiving element 31 are incident on the light passing hole 35. The first scattered light P1 and the second scattered light P2 incident on the light passing hole 35 pass through the light passing hole 35 and are emitted from the exit port 37 of the light passing hole 35. The first scattered light P1 and the second scattered light P2 emitted from the exit port 37 of the light passing hole 35 are incident on the light receiving element 31.

The light receiving element 31 receives the first scattered light P1 and the second scattered light P2 that have passed through the light passing hole 35. The light receiving element 31 is, for example, a photodiode (PD). The light receiving element 31 faces the exit port 37 of the light passing hole 35. The scattered lights P1 and P2 emitted from the exit port 37 are incident on the light receiving element 31.

As shown in FIGS. 3 and 4, the light receiving element 31 includes an effective light receiving region 312 and a light receiving surface 313. The light receiving element 31 can effectively receive the scattered lights P1 and P2 incident on the effective light receiving region 312. On the other hand, the light receiving element 31 cannot effectively receive the scattered light P1 and P2 incident on the portion other than the effective light receiving region 312. The effective light receiving region 312 is a region in which incident light can be converted into an electric signal. The effective light receiving region 312 is formed in the central portion of the light receiving element 31. The effective light receiving region 312 of the light receiving element 31 can be known from, for example, the product specifications of the light receiving element 31. The light receiving surface 313 is the surface of the effective light receiving region 312. The light receiving element 31 can receive the scattered light P1 and P2 incident on the light receiving surface 313. Let Y be the width of the light receiving surface 313 (the width of the effective light receiving region 312). The width Y of the light receiving surface 313 (width of the effective light receiving region 312) Y is the width in the longitudinal direction of the flow path 60 shown in FIG.

As shown in FIG. 5, the processing device 9 is electrically connected to the light emitting element 21 and the light receiving element 31. The processing device 9 is based on the laser light L emitted by the light emitting element 21 and the first scattered light P1 and the second scattered light P2 received by the light receiving element 31, and the velocity v of the particles R passing through the measurement point 10. Is calculated. The processing device 9 calculates the velocity v of the particle R by a calculation method based on the Doppler shift. The velocity v of the particle R passing through the measurement point 10 can be calculated by, for example, the following equation (1). In the following equation, fd is the Doppler frequency of the light received by the light receiving device 3 (light in which the first scattered light P1 and the second scattered light P2 interfere with each other). θ is the angle formed by the first laser beam L1 traveling toward the measurement point 10 and the line connecting the measurement point 10 and the light receiving device 3 (or the second laser beam traveling toward the measurement point 10). The angle formed by L2 and the line connecting the measurement point 10 and the light receiving device 3). λ is the wavelength of the laser light (first laser light L1 and second laser light L2). Since the method of calculating the velocity v of the particle R is known, detailed description thereof will be omitted.

(First Example)
Next, the relational expression in the measuring device will be described with reference to FIGS. 6 to 8. First, the first embodiment will be described. The measuring device 1 according to the first embodiment satisfies the following relational expressions (1) and (2).

As shown in FIG. 6, in the above relational expression, D is the distance between the incident port 36 of the light passing hole 35 and the light receiving surface 313 of the light receiving element 31. H is the distance between the light receiving surface 313 of the light receiving element 31 and the measurement point 10. X is the width of a range in which the intensity of the laser beam formed by overlapping the first laser beam L1 and the second laser beam L2 traveling toward the measurement point 10 is equal to or higher than a predetermined intensity. More specifically, when the first laser beam L1 and the second laser beam L2 interfere with each other at the measurement point 10 and overlap each other, the intensity distribution of the overlapping laser beams is obtained as shown in FIG. Here, the maximum value of the intensity of the overlapping laser beams is defined as Max. Further, the intensity at a predetermined ratio with respect to the maximum value Max is defined as Min. The predetermined ratio to the maximum value Max is, for example, 13.5-10% to 13.5 + 10%. That is, any value in the range of 13.5 ± 10% of the maximum value Max is defined as Min. Then, in the portion where the first laser beam L1 and the second laser beam L2 overlap, if the range in which the intensity of the overlapping laser light is Min or more is S (shaded portion in FIG. 7), the range S The width is X. Further, as shown in FIG. 6, in the above relational expression, Y is the width of the light receiving surface 313 of the light receiving element 31 (the width of the effective light receiving region 312). A is the width of the incident port 36 of the light passing hole 35.

In the above relational expression, D and H are values in the lateral direction of the flow path 60 shown in FIG. That is, it is a value in the direction from the measurement point 10 toward the light receiving element 31. Further, X, Y, and A are values in the longitudinal direction of the flow path 60. That is, it is a value in the flow direction of the fluid F.

Next, a method for deriving the above relational expression (1) will be described. FIG. 8 is a diagram schematically showing the positional relationship in FIG. In FIG. 8, the line segment corresponding to the width X in FIG. 6 is defined as XL. Further, the line segment corresponding to the width Y in FIG. 6 is defined as YL. The distance between the line segment XL and the line segment YL is H.

In FIG. 8, first, an auxiliary line k1 is drawn from the left end of the line segment XL to the right end of the line segment YL. Further, an auxiliary line k2 is drawn from the right end of the line segment XL to the left end of the line segment YL. Let c be the intersection of the auxiliary line k1 and the auxiliary line k2.

Next, on the line segment XL side from the intersection c, an auxiliary line k3 having a width equal to the width Y of the line segment YL is drawn between the auxiliary line k1 and the auxiliary line k2. The left end of the auxiliary line k3 is in contact with the auxiliary line k1, and the right end of the auxiliary line k3 is in contact with the auxiliary line k2. Further, the auxiliary line k3 is parallel to the line segment YL. Let h be the distance between the auxiliary line k3 and the line segment YL. Note that h is a value in the lateral direction of the flow path 60. That is, it is a value in the direction from the measurement point 10 toward the light receiving element 31.

Next, let T1 be the triangle formed by the auxiliary line k1, the auxiliary line k2, and the line segment XL with the intersection c as the apex. Further, the triangle formed by the auxiliary line k1, the auxiliary line k2, and the line segment YL is defined as T2 with the intersection c as the apex. Triangle T1 and triangle T2 are similar triangles. The similarity ratio of the triangle T1 and the triangle T2 is X: Y = (H-h / 2): h / 2. Based on this similarity ratio, solving for h yields h = 2YH / (X + Y).

The distance D between the incident port 36 of the light passing hole 35 and the light receiving surface 313 of the light receiving element 31 is h or more and less than H. That is, h ≦ D <H. The incident port 36 of the light passing hole 35 is located between the auxiliary line k3 and the line segment XL.

From the above, 2YH / (X + Y) ≦ D <H. In this way, the above relational expression (1) is derived. Further, the width A of the incident port 36 of the light passing hole 35 is in a range of Y or more and less than X. That is, Y ≦ A <X. This is the above relational expression (2).

As is clear from the above description, the measuring device 1 of the embodiment is a device that measures the velocity v of the particles R in the fluid F flowing through the flow path 60, and includes a laser light irradiation device 2 and a light receiving device 3. ing. The laser light irradiation device 2 advances toward the measurement point 10 in the flow path 60 from a direction different from that of the first laser light L1 traveling toward the measurement point 10 in the flow path 60 and the first laser light L1. The second laser beam L2 is irradiated. The light receiving device 3 receives scattered light P1 and P2 generated when the first laser light L1 and the second laser light L2 emitted from the laser light irradiating device 2 hit the particles R passing through the measurement point 10, respectively. To do. The light receiving device 3 includes a light receiving element 31, and a hollow light passing hole 35 formed between the light receiving surface 313 of the light receiving element 31 and the measurement point 10. The light passing hole 35 extends from the measurement point 10 toward the light receiving element 31, and scattered light P1 and P2 generated by the particles R passing through the measurement point 10 pass through the light passing hole 36 from the incident port 36 of the light passing hole 35. It is configured to be incident on 35, and the scattered lights P1 and P2 pass through the light passing hole 35 and be incident on the light receiving surface 313 of the light receiving element 31. The measuring device 1 of the first embodiment satisfies the above relational expressions (1) (2YH / (X + Y) ≦ D <H) and the relational expressions (2) (Y ≦ A <X).

According to the above configuration, the light receiving device 3 receives the scattered light P1 and P2 generated by the particles R passing through the measurement point 10. The velocity v of the particles R passing through the measurement point 10 can be calculated based on the frequencies of the scattered lights P1 and P2 received by the light receiving device 3. In order to measure the velocity v of the particles R passing through the measurement point 10, when the laser light irradiation device 2 irradiates the first laser light L1 and the second laser light L2, only the measurement point 10 is first. It is preferable to irradiate the laser beam L1 and the second laser beam L2. However, in reality, it is difficult to irradiate the first laser beam L1 and the second laser beam L2 only to the measurement point 10, and the first laser is also applied to the periphery of the measurement point 10 due to light diffusion or the like. The light L1 and the second laser light L2 are irradiated. Then, when the first laser light L1 and the second laser light L2 emitted from the laser light irradiation device 2 hit the particles R in the fluid F and scatter, they only hit the particles R passing through the measurement point 10 and scatter. Instead, it also hits the particles R passing around the measurement point 10 and scatters. As a result, not only the particles R passing through the measurement point 10 generate scattered light, but also the particles R passing around the measurement point 10 also generate scattered light. However, in the above configuration, since the light passing hole 35 is provided, the scattered light generated by the particles R passing through the measurement point 10 is received, and the scattered light generated by the particles R passing around the measurement point 10 is received. It is possible to suppress light reception. That is, according to the above configuration, since the light passing hole 35 extends in the direction from the measuring point 10 toward the light receiving element 31 between the measuring point 10 and the light receiving element 31, it is generated by the particles R passing through the measuring point 10. The scattered light passes through the light passing hole 35 and enters the light receiving element 31, but the scattered light generated by the particles R passing around the measurement point 10 enters the light receiving element 31 due to the presence of the light passing hole 35. It becomes difficult. As a result, it is possible to suppress receiving excess scattered light.

Further, in the configuration provided with the light passing hole 35, if the position of the incident port 36 of the light passing hole 35 is far from the measurement point 10, the incident range to the light passing hole 35 is widened, so that the measurement point 10 Scattered light generated in the vicinity is likely to enter the light passing hole 35. However, according to the above configuration, the position of the incident port 36 of the light passing hole 35 can be brought closer to the measurement point 10 by satisfying the relational expression (1). That is, since the position of the incident port 36 of the light passing hole 35 is located on the line segment XL side from the position of the auxiliary line k3 shown in FIG. 8, the position is close to the measurement point 10. As a result, it is possible to suppress the expansion of the incident range to the light passing hole 35, so that the scattered light generated around the measurement point 10 is less likely to be incident on the light passing hole 35. Further, according to the above configuration, by satisfying the relational expression (2), it is possible to prevent the width A of the incident port 36 of the light passing hole 35 from becoming too narrow. As a result, the scattered light P1 and P2 from the measurement point 10 toward the light receiving element 31 can be sufficiently received. Therefore, it is possible to sufficiently receive the necessary scattered light while suppressing the reception of the excess scattered light.

Innumerable particles R exist in the fluid F flowing through the flow path 60, and the velocities of the innumerable particles R vary. Therefore, when the light receiving device 3 receives the scattered light generated by the particles R having various velocities, the processing device 9 cannot accurately calculate the velocity v of the particles R. However, according to the above configuration, it is possible to sufficiently receive the necessary scattered light while suppressing the reception of the excess scattered light, so that the velocity v of the particle R can be calculated accurately.

Although one embodiment has been described above, the specific embodiment is not limited to the above embodiment. In the following description, the same reference numerals will be given to the same configurations as those in the above description, and the description thereof will be omitted.

(Second Example)
Next, the second embodiment will be described. The measuring device 1 according to the second embodiment satisfies the following relational expression (3).

Next, a method for deriving the above relational expression (3) will be described. When deriving the relational expression (3), first, the width A of the incident port 36 of the light passing hole 35 is determined. Then, as shown in FIG. 8, the line segment corresponding to the width A of the incident port 36 is defined as AL. The width A of the incident port 36 shall be in the range of Y or more and less than X. That is, Y ≦ A <X.

Next, a line segment AL is drawn between the auxiliary line k1 and the auxiliary line k2 on the line segment XL side from the intersection c. The left end of the line segment AL is in contact with the auxiliary line k1, and the right end of the line segment AL is in contact with the auxiliary line k2. Further, the line segment AL is parallel to the line segment XL and the line segment YL. Let D be the distance between the line segment AL and the line segment YL.

Next, let T1 be the triangle formed by the auxiliary line k1, the auxiliary line k2, and the line segment XL with the intersection c as the apex. Further, the triangle formed by the auxiliary line k1, the auxiliary line k2, and the line segment YL is defined as T2 with the intersection c as the apex. Further, the triangle formed by the auxiliary line k1, the auxiliary line k2, and the line segment AL is defined as T3 with the intersection c as the apex. The triangle T1, the triangle T2, and the triangle T3 are similar triangles. The similarity ratio of the triangle T1, the triangle T2, and the triangle T3 is X: Y: A = (H-h / 2): h / 2: (D-h / 2). Based on this similarity ratio, solving for D yields D = H (A + Y) / (X + Y). In this way, the above relational expression (3) is derived.

In the above relational expression (3), the incident port 36 of the light passing hole 35 and the light receiving element when the width A of the incident port 36 of the light passing hole 35 and the width between the auxiliary line k1 and the auxiliary line k2 are equal. The distance D between the light receiving surfaces 313 of 31 is shown.

As is clear from the above description, the measuring device 1 of the second embodiment satisfies the relational expression (3) (D = H (A + Y) / (X + Y)). According to such a configuration, the scattered light P1 and P2 generated by the particles passing through the measurement point 10 are transmitted to the light receiving surface 313 of the light receiving element 31 while suppressing the reception of the scattered light generated around the measurement point 10. It is possible to receive light by using the whole of. That is, when the above relational expression (3) is satisfied, as shown in FIG. 8, the auxiliary line k1 connecting the left end of the line segment XL and the right end of the line segment YL passes through the left end of the line segment AL. .. Further, the auxiliary line k2 connecting the right end of the line segment XL and the left end of the line segment YL passes through the right end of the line segment AL. This indicates that the scattered lights P1 and P2 generated at the left end of the measurement point 10 pass through the left end of the incident port 36 of the light passing hole 35 and are incident on the right end of the light receiving surface 313 of the light receiving element 31. .. Further, it is shown that the scattered lights P1 and P2 generated at the right end of the measurement point 10 pass through the right end of the incident port 36 of the light passing hole 35 and are incident on the left end of the light receiving surface 313 of the light receiving element 31. Therefore, the scattered light P1 and P2 generated at the measurement point 10 can be received by the entire light receiving surface 313 of the light receiving element 31. On the other hand, the scattered light generated around the measurement point 10 can be suppressed from being incident on the light receiving surface 313 of the light receiving element 31 even if it passes through the light passing hole 35.

(Third Example)
Next, a third embodiment will be described. The measuring device 1 according to the third embodiment satisfies the following relational expression (4).

According to such a configuration, by aligning the width A of the incident port 36 of the light passing hole 35 and the width Y of the light receiving surface 313 of the light receiving element 31, the light receiving element 31 passes through the light passing hole 35 from the measurement point 10. It is possible to efficiently receive the scattered light P1 and P2 toward.

When the relational expression (3) according to the second embodiment is satisfied, and the relational expression (4) according to the third embodiment is satisfied, D = h = 2YH / (X + Y). Become.

(Other Examples)
Next, other examples will be described. The shape of the light passing hole 35 described above is not particularly limited. For example, as shown in FIG. 9, the shape of the light passing hole 35 may be circular in a plan view. Alternatively, as shown in FIG. 10, the shape of the light passing hole 35 may be a polygonal shape in a plan view. Further, as shown in FIG. 11, a plurality of light passing holes 35 may be formed in a slit shape in a plan view.

Further, the configuration of the inner peripheral surface of the light passing hole 35 is not particularly limited. For example, in another embodiment, as shown in FIG. 12, the inner peripheral surface 351 of the light passing hole 35 may be formed in a tapered shape in a cross-sectional view. The inner peripheral surface 351 of the light passing hole 35 is inclined with respect to the direction from the measurement point 10 toward the light receiving element 31. Further, the inner peripheral surface 351 of the light passing hole 35 is inclined with respect to the light receiving surface 313 of the light receiving element 31. The width w37 of the exit port 37 of the light passing hole 35 is smaller than the width w36 of the incident port 36 of the light passing hole 35. Further, the width w37 of the exit port 37 of the light passing hole 35 is equal to the width Y of the light receiving surface 313 of the light receiving element 31. w37 = Y.

When extra scattered light is generated around the measurement point 10, the scattered light P3 may enter the light passing hole 35 and be reflected by the inner peripheral surface 351 as shown in FIG. At this time, according to the above configuration, since the inner peripheral surface 351 of the light passing hole 35 is inclined, it is possible to suppress the extra scattered light P3 reflected by the inner peripheral surface 351 from traveling toward the light receiving element 31. it can. Therefore, it is possible to suppress receiving the extra scattered light P3.

Further, in still another embodiment, a plurality of irregularities (not shown) may be formed on the inner peripheral surface of the light passing hole 35. The surface roughness of the inner peripheral surface of the light passing hole 35 is equal to or higher than the wavelength of the laser light L emitted by the light emitting element 21. The surface roughness of the inner peripheral surface of the light passing hole 35 is equal to or greater than the wavelength of the first laser beam L1 and equal to or greater than the wavelength of the second laser beam L2. The surface roughness of the inner peripheral surface of the light passing hole 35 is equal to or greater than the wavelength of the first scattered light P1 and equal to or greater than the wavelength of the second scattered light P2. The surface roughness of the inner peripheral surface of the light passing hole 35 can be expressed by, for example, the arithmetic mean roughness (Ra).

According to such a configuration, the extra scattered light reflected on the inner peripheral surface of the light passing hole 35 can be diffusely reflected on the uneven surface. As a result, it is possible to suppress the extra scattered light from traveling toward the light receiving element 31. Therefore, it is possible to suppress receiving excess scattered light.

Further, in still another embodiment, the color of the inner peripheral surface of the light passing hole 35 may be black. For example, the inner peripheral surface of the light passing hole 35 can be made black by painting with black or the like.

According to such a configuration, the reflectance of the inner peripheral surface of the light passing hole 35 is lowered. Therefore, it is possible to suppress the extra scattered light generated around the measurement point 10 from being reflected by the inner peripheral surface of the light passing hole 35. As a result, it is possible to suppress the extra scattered light from traveling toward the light receiving element 31.

Further, in still another embodiment, the inner peripheral surface of the light passing hole 35 may be made of a low-reflecting material. For example, the front wall 38a of the box body 38 may be made of a low-reflection material. Alternatively, a film of a low-reflection material may be formed on the surface of the front wall 38a of the box body 38. The low-reflecting material is a material having low reflectance of scattered light P1 and P2. Low reflective materials include, for example, high transmittance materials and high absorption materials. Examples of the high transmittance material include glass (SiO ₂ ), alumina (Al ₂ O ₃ ), plastic (PE, PC) and the like. High absorption rate materials include, for example, chromium oxide (Cr ₂ O ₃ ) and the like.

According to such a configuration, it is possible to suppress the extra scattered light generated around the measurement point 10 from being reflected by the inner peripheral surface of the light passing hole 35. As a result, it is possible to suppress the extra scattered light from traveling toward the light receiving element 31.

Further, the configuration of the laser light irradiation device 2 in the measuring device 1 is not limited to the above embodiment. For example, the arrangement configuration of the light emitting element 21, the first mirror 241 and the second mirror 242 of the laser light irradiation device 2 is not limited to the above embodiment. FIG. 13 is a diagram showing a schematic configuration of a measuring device according to another embodiment. As shown in FIG. 13, the laser light irradiation device 2 includes a light emitting element 21, a collimator lens 22, a beam splitter 26, a first mirror 241 and a second mirror 242. The light emitting element 21 emits the laser beam L obliquely with respect to the longitudinal direction of the tube 61. The collimator lens 22 emits the laser light L emitted by the light emitting element 21 as parallel light. The laser light L (parallel light) emitted from the collimator lens 22 is incident on the beam splitter 26.

In the beam splitter 26, a part of the incident laser beam L is reflected and the other part is transmitted. The beam splitter 26 transmits and reflects the laser beam L. This beam splitter 26 may be called a half mirror. The laser light L reflected by the beam splitter 26 becomes the first laser light L1, and the laser light L transmitted through the beam splitter 26 becomes the second laser light L2. The laser beam L is transmitted and reflected by the beam splitter 26, and is separated into a first laser beam L1 and a second laser beam L2.

The beam splitter 26 is arranged between the first mirror 241 and the second mirror 242. The laser light L (first laser light L1) reflected by the beam splitter 26 travels toward the first mirror 241. Further, the laser beam L (second laser beam L2) transmitted through the beam splitter 26 travels toward the second mirror 242. The first laser beam L1 is reflected by the first reflecting surface 43 of the first mirror 241 and then incident on the flow path 60 in the tube 61. Further, the second laser beam L2 is reflected by the second reflecting surface 44 of the second mirror 242, and then incident on the flow path 60 in the tube 61. Even with such a configuration, the first laser beam L1 and the second laser beam L2 can be irradiated toward the measurement point 10 in the flow path 60.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples illustrated above. The technical elements described herein or in the drawings exhibit their 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 techniques illustrated in the present specification or drawings can achieve a plurality of purposes at the same time, and achieving one of the purposes itself has technical usefulness.

1: Measuring device 2: Laser light irradiation device 3: Light receiving device 9: Processing device 10: Measuring point 21: Light emitting element 22: Collimator lens 23: Diffraction grating 25: Moving device 26: Beam splitter 31: Light receiving element 35: Light Passage hole 36: Incident port 37: Exit port 38: Box body 43: First reflecting surface 44: Second reflecting surface 60: Flow path 61: Tube 62: Fixture 241: First mirror 242: Second Mirror 312: Effective light receiving region 313: Light receiving surface 351: Inner peripheral surface F: Fluid L1: First laser light L2: Second laser light P1: First scattered light P2: Second scattered light R: Particles

Claims (7)

A measuring device for measuring the velocity of particles in a fluid flowing through a flow path.
Irradiate the first laser beam traveling toward the measurement point in the flow path and the second laser light traveling toward the measurement point in the flow path from a direction different from the first laser light. Laser light irradiation device and
It is provided with a light receiving device that receives scattered light generated when the first laser light and the second laser light emitted from the laser light irradiating device hit particles passing through the measurement point.
The light receiving device includes a light receiving element and a hollow light passing hole formed between the light receiving surface of the light receiving element and the measurement point.
The light passing hole extends in a direction from the measuring point toward the light receiving element, and scattered light generated by particles passing through the measuring point passes through the light passing hole and reaches the light receiving surface of the light receiving element. It is configured to be incident and
A measuring device characterized by satisfying the following relational expressions (1) and (2).
2YH / (X + Y) ≤ D <H ... (1)
Y ≤ A <X ... (2)
However, in the above relational expression,
D is the distance between the incident port of the light passing hole and the light receiving surface of the light receiving element.
H is the distance between the light receiving surface of the light receiving element and the measuring point.
For X, Max is the maximum value of the intensity of the laser light formed by overlapping the first laser light and the second laser light traveling toward the measurement point, and 3.5 with respect to the maximum value Max. When any value in the range of% to 23.5% is Min, and S is the range in which the intensity of the overlapping laser beams is equal to or greater than the Min, the width of the range S ,
Y is the width of the light receiving surface of the light receiving element,
A is the width of the incident port of the light passing hole. The measuring device according to claim 1, wherein the measuring device satisfies the following relational expression (3).
D = H (A + Y) / (X + Y) ... (3) The measuring device according to claim 1 or 2, wherein the measuring device satisfies the following relational expression (4).
A = Y ... (4) Any of claims 1 to 3, wherein the surface roughness of the inner peripheral surface of the light passing hole is equal to or greater than the wavelength of the first laser beam and equal to or greater than the wavelength of the second laser beam. The measuring device according to item 1. The measuring device according to any one of claims 1 to 4, wherein the inner peripheral surface of the light passing hole is inclined with respect to the light receiving surface of the light receiving element. The measuring device according to any one of claims 1 to 5, wherein the color of the inner peripheral surface of the light passing hole is black. The measuring device according to any one of claims 1 to 6, wherein the inner peripheral surface of the light passing hole is made of a low-reflection material.

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