JPWO2018173294A1 - Measuring device - Google Patents

Abstract

The light receiving device includes a light receiving element, a light transmissive support member disposed between the light receiving element and the flow path, and a light shielding film disposed on a surface of the support member. A hollow light passage hole penetrating the support member and the coating is formed along a direction from the measurement point toward the light receiving element. A part of the inner peripheral surface of the light passage hole is configured by the light-transmitting support member, and another part of the inner peripheral surface is configured by the light-shielding film, and passes through the measurement point. Scattered light generated by the particles passes through the light passage hole and enters the light receiving element.

Description

  The technology disclosed in this specification relates to a measurement device.

  Conventionally, a laser Doppler type measuring device for measuring the speed of an object to be measured is known. The laser Doppler type measuring device includes a laser light irradiation device, a light receiving device, and a processing device. The laser beam irradiation apparatus irradiates laser light toward a moving measurement object. The laser light emitted from the laser light irradiation device is scattered when it hits a moving measurement object to generate scattered light. 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 measurement object based on the frequency of the scattered light. The processing device calculates the speed of the measurement object by a known calculation method based on a Doppler shift.

  Patent Document 1 (Japanese Patent Laid-Open No. 5-66226) discloses a measuring device including a laser light irradiation device that irradiates laser light from two different directions toward a moving measurement object. The measuring device of Patent Document 1 includes a laser light irradiation device, a light receiving device, and a processing device. The laser beam irradiation apparatus irradiates the first laser beam and the second laser beam toward the moving measurement object. The first laser light and the second laser light are emitted from different directions toward the measurement object. The first laser light and the second laser light irradiated from the laser light irradiation device are scattered when they hit the moving measurement object, and each scattered light is generated. The light receiving device receives each scattered light generated at that time. Moreover, in the measuring apparatus of patent document 1, the light-receiving device is provided with a condensing lens, and various scattered light is condensed and received by this condensing lens. When the light receiving device receives the scattered light of the first laser light and the second laser light, the processing device calculates the velocity of the measurement object based on the frequency of each scattered light. The processing device calculates the speed of the measurement object by a known calculation method based on a Doppler shift.

  In a measuring device that measures the velocity of a measurement object, the velocity of particles in a fluid flowing through a flow path may be measured. That is, the measurement object may be particles in the fluid. As the particles in the fluid, for example, red blood cells in blood can be considered. The measuring device measures the velocity of red blood cells in the blood flowing through the flow path. Thereby, the blood flow rate can be known.

  Innumerable particles generally exist in the fluid flowing through the flow path. For example, there are countless red blood cells in the blood. Innumerable particles are diffused in the fluid. Therefore, innumerable particles include, for example, particles that pass through the central portion of the flow channel and particles that pass through the peripheral portion of the flow channel. Also, the speed of countless particles in the fluid varies. Some particles are fast, others are slow.

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

  In order to accurately measure the velocity of the particles passing through the measurement point, it is preferable that the light receiving device sufficiently receive the scattered light generated by the particles passing through the measurement point. Moreover, in order to accurately measure the velocity of particles, each laser beam is irradiated only on the measurement point when the first laser beam and the second laser beam are irradiated from the laser beam irradiation device toward the measurement point. do it. Then, only the scattered light generated when the first laser light and the second laser light hit only the particles passing through the measurement point and each laser light hits the particles can be taken out. Therefore, ideally, when the first laser beam and the second laser beam are irradiated, it is preferable to irradiate the first laser beam and the second laser beam so as to 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 distributed around the measurement point by light diffusion or the like. Laser light will be irradiated. That is, the first laser beam and the second laser beam are irradiated so as to overlap each other around the measurement point due to light diffusion or the like. Then, when the first laser light and the second laser light irradiated from the laser light irradiation device hit the particles and scatter, the particles pass not only the particles passing through the measurement point but also passing around the measurement point. In addition, the first laser beam and the second laser beam hit and scatter. Therefore, not only scattered light generated by particles passing through the measurement point but also scattered light generated by particles passing around the measurement point are extracted. Then, since the speed of countless particles in the fluid is various, the light receiving device receives various scattered lights generated by the particles having various speeds. As a result, the processing apparatus calculates the velocity of the particles based on various scattered light frequencies, and it becomes difficult to accurately measure the velocity of the particles in the fluid flowing through the flow path. Moreover, in the measuring apparatus of patent document 1, since the light receiving device collects and receives various scattered light by the condensing lens, the processing device calculates the velocity of the particles based on the frequency of the various scattered light. It will be. As a result, it becomes difficult to accurately measure the velocity of the particles in the fluid flowing through the flow path. As described above, in the measuring apparatus of Patent Document 1, not only scattered light generated by particles passing through the measurement point but also excess scattered light is received, making it 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 measurement object is uniform, but a problem arises when the speed is various, such as particles in the liquid flowing in the pipe. Therefore, the present specification provides a technique capable of suppressing the reception of excess scattered light.

  The measuring device disclosed in this 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 beam irradiation device and a light receiving device. The laser beam irradiation device has a first laser beam traveling toward the measurement point in the flow path, and a second laser beam traveling toward the measurement point in the flow path from a direction different from the first laser beam. Irradiate the laser beam. The light receiving device receives scattered light respectively generated when the first laser light and the second laser light irradiated from the laser light irradiation device hit the particles passing through the measurement point. The light receiving device includes a light receiving element, a light-transmitting support member disposed between the light receiving element and the flow path, and a light-shielding coating disposed on the surface of the support member. A hollow light passage hole penetrating the support member and the coating is formed along the direction from the measurement point toward the light receiving element. A part of the inner peripheral surface of the light passage hole is configured by the light-transmitting support member, and another part of the inner peripheral surface is configured by the light-shielding film, and passes through the measurement point. Scattered light generated by the particles passes through the light passage hole and enters the light receiving element.

  According to such a configuration, scattered light generated by particles passing through the measurement point passes through the light passage hole and enters the light receiving element. However, when the first laser beam and the second laser beam are irradiated from the laser beam irradiation apparatus, the first laser beam and the second laser beam are irradiated not only at the measurement point but also around the measurement point. It may be done. Then, scattered light is generated not only by the particles passing through the measurement point but also by particles passing around the measurement point. At this time, according to the above configuration, since the light passage 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 passage hole extends in the direction from the measurement point to the light receiving element between the measurement point and the light receiving element, the scattered light generated by the particles passing through the measurement point is reflected in the light passage hole. However, the scattered light generated by the particles passing around the measurement point is less likely to enter the light receiving element due to the presence of the light passage hole. Accordingly, it is possible to suppress receiving excessive scattered light.

  In addition, scattered light generated by particles passing around the measurement point may enter the light passage hole and hit the inner peripheral surface of the light passage hole. At this time, according to the above configuration, a part of the inner peripheral surface of the light passage hole is configured by a light-transmitting support member, and the other part of the inner peripheral surface is configured by a light-shielding film. Only a part of the scattered light impinging on the inner peripheral surface of the light passage hole is reflected by the inner peripheral surface. Specifically, some of the scattered light striking the inner peripheral surface of the light passage hole is reflected by the light-shielding coating, and the other part is not reflected by the light-transmitting support member but inside the support member. Incident. By combining the light-transmitting support member and the light-shielding film, the range in which the scattered light is reflected on the inner peripheral surface of the light passage hole can be relatively reduced. When scattered light is reflected on the inner peripheral surface of the light passage hole, the reflected light travels in various directions. If it does so, possibility that a light receiving element will receive light from various directions becomes high. However, according to the above configuration, the range in which the scattered light is reflected by the inner peripheral surface of the light passage hole becomes relatively small, so that the possibility that the light receiving element receives light from various directions is reduced. Accordingly, it is possible to suppress receiving excessive scattered light. Moreover, according to said structure, since the intensity | strength of a film can be maintained with a supporting member by combining a supporting member and a film, the thickness of a film can be made thin. If the thickness of the light-shielding film is reduced, the range in which the scattered light is reflected on the inner peripheral surface of the light passage hole can be reduced, so that it is possible to further suppress the light receiving element from receiving excess scattered light.

  In the measurement apparatus, the coating film may be disposed on a surface of the support member on the light receiving element side.

  According to such a structure, it is suppressed that a film is exposed to the opposite side (flow path side) with respect to a light receiving element. Thereby, the coating is suppressed from being exposed to the outside, and the coating can be protected.

  In addition, the measurement device may further include a processing device that can calculate the velocity of particles in the fluid. The processing apparatus includes a first arithmetic expression that calculates the velocity of particles in the fluid without being influenced by the concentration of the fluid, and a second arithmetic expression that calculates a relative velocity that changes in accordance with the concentration in a mathematical configuration that does not use an angle. Based on the above, the concentration of the fluid may be calculated.

  According to such a configuration, the velocity of the particles in the fluid and the concentration of the fluid can be obtained together.

It is a figure which shows schematic structure of the measuring device which concerns on an Example. It is a figure which shows schematic structure of the light-receiving device based on an Example. It is an enlarged view of the principal part III of FIG. It is a side view which shows schematic structure of the light receiving element which concerns on an Example. It is a top view which shows schematic structure of the light receiving element which concerns on an Example. It is a block diagram of a measuring device concerning an example. It is a graph which shows an example of the result of spectrum analysis. It is a graph which shows the relationship between D defined by Formula 8, and the density | concentration d of a fluid. It is a top view which shows an example of a light passage hole. It is a top view which shows another example of a light passage hole. It is a top view which shows another example of a light passage hole. It is a figure corresponding to FIG. 3 which concerns on another Example. It is a figure which shows schematic structure of the measuring device which concerns on another Example.

  Embodiments will be described below with reference to the accompanying drawings. As shown in FIG. 1, the measuring apparatus 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 tube 61. The measuring device 1 is a device that measures the velocity v of the particle R in the fluid F flowing through the flow path 60. Thereby, the flow rate of the fluid F can be known.

  Innumerable particles R exist in the fluid F flowing through the flow path 60. Innumerable particles R are diffused in the fluid F. Therefore, among the countless particles R, for example, there are particles R that pass through the central portion of the flow channel 60 and particles R that pass through the peripheral portion of the flow channel 60. In addition, the speed of the countless particles R varies. Some particles R have a high speed and some particles R have a low speed. When measuring the velocity v of the particle R in the fluid F flowing through the flow channel 60, the velocity v of the particle R may be measured by focusing on a specific measurement point 10 in the flow channel 60. The position of the measurement point 10 in the flow channel 60 is not particularly limited. For example, the velocity v of the particle R passing through the central portion of the flow channel 60 is measured using the central portion of the flow channel 60 as the measurement point 10. can do. In general, in the case of laminar flow, it is known that the flow velocity of the fluid F flowing through the center of the flow channel 60 corresponds to twice the average flow velocity of the fluid F flowing through the entire flow channel 60.

  An example of the fluid F flowing through the flow path 60 is blood. Examples of the particles R in the fluid F include red blood cells. The measuring device 1 can measure the velocity of red blood cells in the blood. Thereby, the blood flow rate can be known. In the medical field, extracorporeal circulation may be performed in which blood flowing through the patient's body is sent out of the body and the blood sent out of the body is sent back into the body again. 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. It is. 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 disposed so as to face the collimator lens 22. The light emitting element 21 emits laser light L toward the collimator lens 22. Laser light L emitted from the light emitting element 21 enters the collimator lens 22. The light emitting element 21 emits the laser light 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 disposed between the diffraction grating 23 and the first mirror 241 and the second mirror 242.

  The collimator lens 22 is disposed between the light emitting element 21 and the diffraction grating 23. The collimator lens 22 emits the laser light L emitted from the light emitting element 21 as parallel light. Laser light L (parallel light) emitted from the collimator lens 22 enters the diffraction grating 23.

  The diffraction grating 23 is disposed 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 can move the diffraction grating 23 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 the first laser light L1 and the second laser light L2 using light diffraction. The diffraction grating 23 is a reflection type diffraction grating. When the laser beam L incident on the diffraction grating 23 is reflected by the diffraction grating 23, it is divided into a first laser beam L1 and a second laser beam L2. The laser beam L emitted from the light emitting element 21 is reflected by the diffraction grating 23 to be divided into a first laser beam L1 and a second laser beam 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 a line connecting the light emitting element 21 and the collimator lens 22. In the example shown in FIG. 1, the first laser light L1 travels diagonally upward to the right, and the second laser light L2 travels diagonally upward to the left. The first laser light 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 light L1 and the wavelength of the second laser light L2 are the same wavelength. Further, the frequency of the first laser light L1 and the frequency of the second laser light L2 are the same frequency.

  The first mirror 241 and the second mirror 242 are disposed between the diffraction grating 23 and the tube 61. The first mirror 241 and the second mirror 242 face each other. The first laser light L 1 generated by the diffraction grating 23 is incident on the first mirror 241, and the second laser light L 2 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. At the first reflecting surface 43, the first laser light L1 incident on the first mirror 241 is reflected. On the second reflecting surface 44, the second laser light L2 incident on the second mirror 242 is reflected.

  The first laser light L 1 reflected by the first reflecting surface 43 of the first mirror 241 enters the flow path 60 in the tube 61. Further, the second laser light L <b> 2 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 light L1 and the second laser light L2 travel toward the measurement point 10 in the flow path 60.

  The first laser beam L1 and the second laser beam L2 travel toward the measurement point 10 from different directions. 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 channel 60 from different directions. The first laser light L1 travels from the downstream side of the flow path 60 toward the measurement point 10. The second laser light 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 are interfered and overlapped at the measurement point 10 in the flow path 60.

  A fluid F (for example, blood) flows through the flow path 60, and innumerable particles R (for example, red blood cells) exist in the fluid F. Among the countless 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 strike the particle 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 strike the particle R from different directions. The first laser light L1 hits the particle R from the downstream side of the flow path 60. That is, the first laser light L1 strikes the particle R from the traveling direction side of the particle R. On the other hand, the second laser light L2 hits the particle R from the upstream side of the flow path 60. That is, the second laser light L2 strikes 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 strike the particle R and are scattered. The first scattered light P1 is generated when the first laser light L1 strikes the particle R and is scattered. Further, the second scattered light P2 is generated when the second laser light L2 hits the particle R and is scattered. The first scattered light P <b> 1 and the second scattered light P <b> 2 generated by scattering travel in various directions around the measurement point 10. Among them, there are first scattered light P1 and second scattered light P2 that travel 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 strike the particle R and scatter, the 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. The frequency f1 of the first scattered light P1 and the frequency f2 of the second scattered light P2 are different from each other.

  The light receiving device 3 is disposed between the tube 61 and the laser light irradiation device 2. The light receiving device 3 is disposed 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 38. The light receiving element 31 is disposed in the box 38.

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

  The light passage hole 35 is formed between the measurement point 10 and the light receiving element 31. The light passage hole 35 extends in a direction from the measurement point 10 toward the light receiving element 31. It is preferable that the light passage hole 35, the measurement point 10, and the light receiving element 31 are in a coaxial position. The light passage hole 35 includes an entrance port 36 and an exit port 37. The first scattered light P <b> 1 and the second scattered light P <b> 2 generated by the particles R passing through the measurement point 10 are incident on the light passage hole 35 from the entrance 36 of the light passage hole 35. The first scattered light P 1 and the second scattered light P 2 traveling from the measurement point 10 toward the light receiving element 31 are incident on the light passage hole 35. The first scattered light P1 and the second scattered light P2 incident on the light passage hole 35 pass through the light passage hole 35 and are emitted from the emission port 37 of the light passage hole 35. The first scattered light P <b> 1 and the second scattered light P <b> 2 emitted from the emission port 37 of the light passage hole 35 enter the light receiving element 31.

  As shown in FIG. 3, the front wall 38 a of the box 38 includes a support member 71 and a coating film 72 disposed on the surface of the support member 71. The support member 71 and the coating 72 are disposed between the light receiving element 31 and the flow path 60 (not shown in FIG. 4). The support member 71 is a member having optical transparency. The support member 71 supports the coating film 72. The film 72 is a light-shielding film. The thickness of the coating 72 is thinner than the thickness of the support member 71. The coating 72 covers the surface of the support member 71. The coating 72 is disposed on the surface of the support member 71 opposite to the light receiving element 31 (on the flow path 60 side).

  A through hole is formed in the support member 71 and the coating 72, and the light passage hole 35 is formed by the through hole. The support member 71 and the coating film 72 are exposed on the inner peripheral surface 351 of the light passage hole 35. A part of the inner peripheral surface 351 of the light passage hole 35 is constituted by a support member 71. Another part of the inner peripheral surface 351 of the light passage hole 35 is constituted by a coating 72. The light passage hole 35 is formed after the coating 72 is attached to the surface of the support member 71.

  As shown in FIG. 2, the light receiving element 31 receives the first scattered light P <b> 1 and the second scattered light P <b> 2 that have passed through the light passage hole 35. The light receiving element 31 is, for example, a photodiode (PD). The light receiving element 31 faces the emission port 37 of the light passage hole 35. Scattered light P <b> 1 and P <b> 2 emitted from the emission port 37 enter the light receiving element 31.

  As shown in FIGS. 4 and 5, 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 light P <b> 1 and P <b> 2 incident on the effective light receiving region 312. On the other hand, the light receiving element 31 cannot effectively receive the scattered lights P <b> 1 and P <b> 2 incident on portions other than the effective light receiving region 312. The effective light receiving region 312 is a region where incident light can be converted into an electric signal. The effective light receiving region 312 is formed at the center of the light receiving element 31. The effective light receiving region 312 of the light receiving element 31 can be known from the product specification of the light receiving element 31, for example. The light receiving surface 313 is the surface of the effective light receiving region 312. The light receiving element 31 can receive the scattered lights P1 and P2 incident on the light receiving surface 313.

  As shown in FIG. 6, the processing apparatus 9 is electrically connected to the light emitting element 21 and the light receiving element 31. Based on the laser light L emitted from the light emitting element 21 and the first scattered light P1 and the second scattered light P2 received by the light receiving element 31, the processing device 9 uses the velocity v of the particle 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. Further, the processing device 9 calculates the concentration d of the fluid F flowing through the flow path 60.

  Next, an example of a method in which the processing device 9 calculates the velocity v of the particle R will be described. The processing device 9 first performs a spectrum analysis on the light received by the light receiving element 31 (the light in which the first scattered light P1 and the second scattered light P2 interfere). The spectrum analysis can be performed using, for example, an FFT analyzer. Since spectrum analysis is a known analysis method, a detailed description thereof will be omitted. FIG. 7 is a graph showing an example of the result of spectrum analysis. The horizontal axis in the graph of FIG. 7 is the frequency, and the vertical axis is the intensity of each frequency component. In FIG. 7, a graph corresponding to the concentration d of the fluid F flowing through the flow path 60 is drawn. In the present embodiment, three graphs corresponding to the first density da, the second density db, and the third density dc are drawn.

The processing device 9 can calculate the velocity v _{A of the} particle R based on the following first calculation formula (1). The processing unit 9 can calculate the velocity v _B of the particles R based on the second calculation formula (2). The first arithmetic expression (1) is an expression for calculating the velocity of the particles R in the fluid F without being affected by the concentration d of the fluid F. The velocity v _A calculated by the first arithmetic expression (1) is not affected by the concentration d of the fluid F. The second arithmetic expression (2) is an arithmetic expression for calculating a relative speed that changes in accordance with the density with a simple mathematical configuration that does not use the angle θ. The velocity v _B calculated by the second arithmetic expression (2) is affected by the concentration d of the fluid F.

  In the first arithmetic expression (1), λ is the wavelength of the laser light L of the light emitting element 21. fd is the Doppler frequency of the light received by the light receiving element 31 (the light in which the first scattered light P1 and the second scattered light P2 interfere). θ is an angle between 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). L2 and an angle formed by a line connecting measurement point 10 and light receiving device 3).

In the second arithmetic expression (2), A is a correction coefficient including a density component. M is a first moment calculated based on the graph of FIG. This M is calculated by the following equation (3). In Expression 3, x is the value of the frequency (horizontal axis) in the graph of FIG. f (x) is the intensity (vertical axis) value at the frequency x in the graph of FIG. The processing device 9 calculates each primary moment M according to the concentration d of the fluid F. The processing device 9 calculates the primary moment M for each of the first density da, the second density db, and the third density dc.

  Next, an example of a method by which the processing device 9 calculates the concentration d of the fluid F will be described. The processing device 9 can calculate the concentration d of the fluid F based on the first calculation formula (1) and the second calculation formula (2). The calculation method will be described in detail below.

First, the first arithmetic expression (1) is modified as shown in Equation 4 below. Further, the second arithmetic expression (2) is modified as shown in the following equation 5. Further, when substituting Equation 4 into Equation 5, the following Equation 6 is obtained.

Next, a constant B is defined as in Equation 7 below. Further, the number D is defined as in the following number 8. Then, when formulas 7 and 8 are substituted into formula 6 and arranged, the following formula 9 is obtained.

A in the above equation 9 is a correction coefficient including a density component. If a component other than the density component in the correction coefficient A is transferred to B on the right side, it can be expressed as the following Expression 10.

  Thus, the concentration d of the fluid F can be calculated. The processing device 9 performs the above calculation for each of the first density da, the second density db, and the third density dc. FIG. 8 is a graph showing the relationship between D defined by Equation 8 above and the concentration d of the fluid F. As shown in FIG. 8, as the value of D increases, the concentration d of the fluid F decreases.

  As is clear from the above description, the measuring device 1 of the embodiment is a device for measuring the velocity v of the particle R in the fluid F flowing through the flow path 60, and includes the laser light irradiation device 2 and the light receiving device 3. It has. The laser light irradiation device 2 travels toward the measurement point 10 in the flow path 60 from a direction different from the first laser light L1 that travels 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 the scattered light P1 and P2 generated when the first laser light L1 and the second laser light L2 irradiated from the laser light irradiation device 2 hit the particle R passing through the measurement point 10, respectively. To do. The light receiving device 3 includes a light receiving element 31, a light-transmitting support member 71 disposed between the light receiving element 31 and the flow path 60, and a light-shielding film 72 disposed on the surface of the support member 71. ing. A hollow light passage hole 35 penetrating the support member 71 and the coating 72 is formed along the direction from the measurement point 10 toward the light receiving element 31. A part of the inner peripheral surface 351 of the light passage hole 35 is constituted by a light transmissive support member 71, and the other part of the inner peripheral surface 351 is constituted by a light shielding film 72. Scattered light P <b> 1 and P <b> 2 generated by the particle R passing through the measurement point 10 passes through the light passage hole 35 and enters the light receiving element 31.

  According to the above configuration, the light receiving device 3 receives the scattered lights P <b> 1 and P <b> 2 generated by the particles R passing through the measurement point 10. Based on the frequencies of the scattered lights P1 and P2 received by the light receiving device 3, the velocity v of the particles R passing through the measurement point 10 can be calculated. In order to measure the velocity v of the particle R passing through the measurement point 10, when the first laser beam L 1 and the second laser beam L 2 are irradiated from the laser beam irradiation device 2, the first measurement point 10 only is measured. It is preferable to irradiate the laser beam L1 and the second laser beam L2. However, in reality, it is difficult to irradiate only the measurement point 10 with the first laser light L1 and the second laser light L2, 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 irradiated 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. In other words, the light hits the particle R passing around the measurement point 10 and is scattered. As a result, not only scattered light is generated by the particles R passing through the measurement point 10 but also scattered light is generated by the particles R passing around the measurement point 10. However, in the above configuration, since the light passage 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 can suppress receiving light. That is, according to the above configuration, the light passage hole 35 extends between the measurement point 10 and the light receiving element 31 in the direction from the measurement point 10 toward the light receiving element 31, and thus is generated by the particles R passing through the measurement point 10. The scattered light passes through the light passage hole 35 and enters the light receiving element 31. However, 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 passage hole 35. It becomes difficult. Accordingly, it is possible to suppress receiving excessive scattered light.

  In addition, scattered light generated by the particles R passing around the measurement point 10 may enter the light passage hole 35 and hit the inner peripheral surface 351 of the light passage hole 35. At this time, according to the above configuration, a part of the inner peripheral surface 351 of the light passage hole 35 is configured by the light-transmitting support member 71 and the other part of the inner peripheral surface 351 is the light-shielding film 72. Since it is configured, only a part of the scattered light impinging on the inner peripheral surface 351 of the light passage hole 35 is reflected by the inner peripheral surface 351. Specifically, as shown in FIG. 3, of the scattered light P3 and P4 hitting the inner peripheral surface 351 of the light passage hole 35, some of the scattered light P3 is reflected by the light-shielding film 72 and the other part. The scattered light P <b> 4 enters the inside of the support member 71 without being reflected by the light-transmissive support member 71. By combining the light-transmissive support member 71 and the light-shielding film 72, the range of the scattered light reflected on the inner peripheral surface 351 of the light passage hole 35 can be made relatively small. When the scattered light is reflected by the inner peripheral surface 351 of the light passage hole 35 as in the scattered light P3 of FIG. 3, the reflected light travels in various directions. If it does so, possibility that the light receiving element 31 will receive light from various directions becomes high. However, according to the above configuration, the range in which the scattered light is reflected by the inner peripheral surface 351 of the light passage hole 35 becomes relatively small, so that the light receiving element 31 is less likely to receive light from various directions. . As a result, the light receiving element 31 can be prevented from receiving excess scattered light. Moreover, according to said structure, since the intensity | strength of the film 72 can be maintained by the support member 71 by combining the support member 71 and the film 72, the thickness of the film 72 can be made thin. If the thickness of the light-shielding film 72 is reduced, the range in which the scattered light is reflected by the inner peripheral surface 351 of the light passage hole 35 can be reduced, so that the light receiving element 31 can receive extra scattered light. Can be suppressed.

  When the light receiving element 31 receives various scattered lights, the processing device 9 cannot accurately calculate the velocity v of the particles R. However, according to the above configuration, it is possible to prevent the light receiving element 31 from receiving extra scattered light, so that the processing device 9 can accurately calculate the velocity v of the particles R.

  In addition, the processing device 9 changes according to the concentration with a first arithmetic expression that calculates the velocity of the particle R in the fluid F without being affected by the concentration d of the fluid F, and a simple mathematical configuration that does not use the angle θ. The concentration d of the fluid F can be calculated based on the second calculation formula for calculating the relative velocity. Therefore, the velocity v of the particle R and the concentration d of the fluid F can be calculated together.

  Although one embodiment has been described above, the specific mode is not limited to the above embodiment. In the following description, the same components as those described above are denoted by the same reference numerals, and the description thereof is omitted.

  The shape of the light passage hole 35 described above is not particularly limited. For example, as shown in FIG. 9, the shape of the light passage hole 35 may be a circular shape in plan view. Alternatively, as shown in FIG. 10, the shape of the light passage hole 35 may be a polygonal shape in plan view. Moreover, as shown in FIG. 11, the several light passage hole 35 may be formed in slit shape in planar view.

  In the above embodiment, the coating 72 is disposed on the surface of the support member 71 opposite to the light receiving element 31. However, the present invention is not limited to this configuration. In another embodiment, as shown in FIG. 12, a film 72 may be disposed on the surface of the support member 71 on the light receiving element 31 side. That is, the coating film 72 may be disposed on the surface of the support member 71 opposite to the flow path 60.

  According to such a configuration, the coating 72 is disposed on the side opposite to the flow path 60, and the coating 72 is suppressed from being exposed to the outside of the box 38. Therefore, the coating film 72 can be protected.

  In still another embodiment, the coating 72 may be disposed on both surfaces of the support member 71 (both the surface of the support member 71 on the light receiving element 31 side and the surface opposite to the light receiving element 31).

  Moreover, the structure of the laser beam irradiation apparatus 2 in the measuring apparatus 1 is not limited to said Example. For example, the arrangement configuration of the light emitting element 21, the first mirror 241, the second mirror 242, and the like of the laser light irradiation device 2 is not limited to the above-described embodiment. FIG. 13 is a diagram illustrating a schematic configuration of a measurement apparatus 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 laser light L obliquely with respect to the longitudinal direction of the tube 61. The collimator lens 22 emits the laser light L emitted from the light emitting element 21 as parallel light. Laser light L (parallel light) emitted from the collimator lens 22 enters the beam splitter 26.

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

  The beam splitter 26 is disposed between the first mirror 241 and the second mirror 242. The laser beam L (first laser beam L1) reflected by the beam splitter 26 travels toward the first mirror 241. Further, the laser light L (second laser light L 2) transmitted through the beam splitter 26 travels toward the second mirror 242. The first laser light L 1 is reflected by the first reflecting surface 43 of the first mirror 241 and then enters the flow path 60 in the tube 61. Further, the second laser light L <b> 2 is reflected by the second reflecting surface 44 of the second mirror 242 and then enters the flow path 60 in the tube 61. Also with such a configuration, the first laser light L1 and the second laser light L2 can be irradiated toward the measurement point 10 in the flow path 60.

  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. The technical elements described in this 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 exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

1: Measuring device 2: Laser beam 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 Passing hole 36: entrance 37: exit 38: box 43: first reflecting surface 44: second reflecting surface 60: flow path 61: tube 62: fixture 71: support member 72: coating 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 (3)

A measuring device for measuring the velocity of particles in a fluid flowing through a flow path,
A laser that irradiates a first laser beam traveling toward the measurement point in the flow path and a second laser beam traveling toward the measurement point in the flow path from a direction different from the first laser light. A light irradiation device;
A light receiving device that receives scattered light generated when the first laser light and the second laser light irradiated from the laser light irradiation device hit the particles passing through the measurement point, respectively;
The light receiving device includes a light receiving element, a light transmissive support member disposed between the light receiving element and the flow path, and a light shielding film disposed on a surface of the support member,
A hollow light passage hole penetrating the support member and the coating along the direction from the measurement point toward the light receiving element is formed,
A part of the inner peripheral surface of the light passage hole is configured by the light-transmitting support member, and another part of the inner peripheral surface is configured by the light-shielding film, and passes through the measurement point. Scattered light generated by the particles passes through the light passage hole and enters the light receiving element.   The measuring apparatus according to claim 1, wherein the coating is disposed on a surface of the support member on the light receiving element side. A processing device capable of calculating the velocity of particles in the fluid;
The processing device calculates a first calculation formula that calculates the velocity of particles in the fluid without being influenced by the concentration of the fluid, and a second calculation formula that calculates a relative velocity that changes according to the concentration in a mathematical configuration that does not use an angle. The measuring apparatus according to claim 1, wherein the concentration of the fluid is calculated based on an arithmetic expression.

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