JP6908245B2 - 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 irradiating device irradiates a moving measurement object with a laser light. 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 speed of the object to be measured based on the frequency of the scattered light. The processing apparatus calculates the speed of the measurement object by a calculation method based on a known Doppler shift.

Patent Document 1 (Japanese Patent Laid-Open 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 irradiation 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 light and the second laser light emitted from the laser light irradiating device are scattered when they hit a moving measurement object, and the respective scattered lights are 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 apparatus 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, the first laser beam and the second laser beam 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 emitted from different directions toward the measurement point in the flow path. The first laser light and the second laser light emitted from the laser light irradiating device are scattered when they hit the particles passing through the measurement point, and the respective scattered lights are 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 measure the speed of particles passing through the measurement point, when irradiating the first laser light and the second laser light from the laser light irradiation device toward the measurement point, each laser light is applied only to the measurement point. You just have to irradiate. 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 provided 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 surroundings due to light diffusion or the like. Then, when the first laser beam and the second laser beam emitted from the laser light irradiating 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 is 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 condensing 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 is various like particles in a fluid. Therefore, the present specification provides a technique capable of suppressing the reception of excess scattered light.

The measuring device disclosed in the present specification is a 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 emits a first laser beam traveling toward a measurement point in the flow path and a second laser light traveling toward the measurement point in the flow path from a direction different from the first laser light. Irradiate. 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 element and the measurement point. The light passing hole extends in the direction from the measurement point toward the light receiving element, and the scattered light generated by the particles passing through the measuring point passes through the light passing hole and is incident on the light receiving element.

According to such a configuration, only 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. 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 end up. 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. However, 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. Therefore, the velocity of particles in the fluid flowing through the flow path can be accurately measured.

It is a figure which shows the schematic structure of the measuring apparatus which concerns on Example. It is an enlarged view of the main part II of FIG. It is a figure which shows the schematic structure of the light receiving device which concerns on Example. It is a block diagram of the measuring apparatus which concerns on Example. It is a figure which shows the schematic structure of the measuring apparatus which concerns on another Example. It is sectional drawing which shows an example of a light passing hole. It is sectional drawing which shows 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 light receiving device which concerns on another Example.

The main features of the examples described below are listed. The technical elements described below are independent technical elements, and exhibit their technical usefulness alone or in various combinations.

(Feature 1) The laser light irradiation device includes a light emitting element that emits laser light, and a second laser light that causes the laser light emitted by the light emitting element to travel in a direction different from that of the first laser light and the first laser light. It may be provided with a diffraction grating divided into. Further, the laser light irradiation device is a first transmission reflection surface on which the first laser light divided by the diffraction grating is incident, and a part of the incident first laser light is transmitted and the other part is transmitted. May include a first transmissive reflective surface that reflects and causes the reflected first laser beam to travel toward the measurement point. Further, the laser light irradiation device is a second transmission reflection surface on which the second laser light divided by the diffraction grating is incident, and transmits a part of the incident second laser light and a part of the other. It may be provided with a second transmission reflecting surface that reflects the reflected second laser light and travels toward the measurement point.

According to such a configuration, a part of the first laser beam (a component transmitted by the first transmitted reflecting surface) can be removed, and another part (a component reflected by the first transmitted reflecting surface) can be removed. ) Only travels toward the measurement point, so that the spread of the strong light of the first laser beam traveling toward the measurement point can be narrowed down. Similarly, a part of the second laser beam (the component transmitted by the second transmitted reflecting surface) can be removed, and only the other part (the component reflected by the second transmitted reflecting surface) is a measurement point. Since it travels toward the measurement point, it is possible to narrow down the spread of the strong light of the second laser light that travels toward the measurement point. By weakening the intensity, when the first laser beam and the second laser beam are irradiated toward the measurement point, the first laser beam and the second laser beam spread around the measurement point. It can be suppressed. Therefore, it is possible to suppress the generation of scattered light by the particles passing around the measurement point. Therefore, it is possible to suppress receiving extra scattered light.

(Feature 2) The angle of incidence of the optical axis of the first laser beam incident on the first transmission / reflection surface may be smaller than the critical angle of the first transmission / reflection surface. The incident angle of the optical axis of the second laser beam incident on the second transmitted reflecting surface may be smaller than the critical angle on the second transmitted reflecting surface.

According to such a configuration, the transmitted component can be increased (the reflected component can be reduced) in the first laser beam incident on the first transmitted reflecting surface. Similarly, the transmitted component can be increased (the reflected component can be reduced) in the second laser beam incident on the second transmitted reflecting surface. As a result, the intensity of the first laser beam that is reflected by the first transmission and reflection surface and travels toward the measurement point and the second laser that is reflected by the second transmission and reflection surface and travels toward the measurement point. The intensity of light can be weakened. By weakening the intensity, when the first laser beam and the second laser beam are irradiated toward the measurement point, the first laser beam and the second laser beam spread around the measurement point. It can be suppressed.

(Feature 3) The measuring device may further include a moving device that changes the distance between the diffraction grating and the first transmission / reflection surface and the second transmission / reflection surface.

According to such a configuration, the positions where the first laser beam and the second laser beam separated by the diffraction grating are incident on the first transmission reflection surface and the second transmission reflection surface can be changed. Thereby, the positions where the first laser beam and the second laser beam are irradiated can be changed, and the positions of the measurement points in the flow path can be changed.

(Feature 4) The diffraction grating may be a reflection type diffraction grating. The light emitting element may be arranged between the diffraction grating, the first transmission reflection surface, and the second transmission reflection surface. The laser light emitted by the light emitting element may be reflected by the diffraction grating to be separated into a first laser light and a second laser light.

According to such a configuration, the measuring device can be made compact. If the diffraction grating is a transmission type diffraction grating, the light emitting element must be arranged on the opposite side of the first transmission reflection surface and the second transmission reflection surface with respect to the diffraction grating, and the measuring device is large. It will be transformed.

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 the pipe 61 by the 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, 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, and a light guide body 24. 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 laser light toward the collimator lens 22. The laser light emitted by the light emitting element 21 is incident on the collimator lens 22. The light emitting element 21 emits laser light on the side opposite to the light guide body 24. The light emitting element 21 is arranged between the diffraction grating 23 and the light guide body 24.

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 light guide body 24. 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. Both the first laser light L1 and the second laser light L2 travel toward the light guide body 24, but 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 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 light guide body 24 is arranged between the diffraction grating 23 and the tube 61. The first laser beam L1 and the second laser beam L2 generated by the diffraction grating 23 are incident on the light guide body 24. The light guide body 24 is formed of, for example, a rectangular parallelepiped transparent glass block. The light guide body 24 includes an incident surface 41, an exit surface 42, a first side surface 43, and a second side surface 44. The incident surface 41 is arranged so as to face the diffraction grating 23. The first laser beam L1 and the second laser beam L2 are incident from the incident surface 41. The first laser beam L1 incident from the incident surface 41 travels toward the first side surface 43. The first laser beam L1 is incident on the first side surface 43. Further, the second laser beam L2 incident from the incident surface 41 travels toward the second side surface 44. The second laser beam L2 is incident on the second side surface 44.

The first side surface 43 and the second side surface 44 are arranged between the entrance surface 41 and the exit surface 42. On the first side surface 43, a part of the incident first laser beam L1 is transmitted and the other part is reflected. That is, the first side surface 43 is a transmission / reflection surface that transmits and reflects the first laser beam L1. Hereinafter, the first side surface may be referred to as a first transmission reflection surface. Alternatively, the first side surface may be referred to as a first half mirror. The first laser beam L1 reflected by the first transmission reflection surface 43 (first side surface 43 or first half mirror 43) travels toward the emission surface 42 and is emitted from the emission surface 42. Similarly, on the second side surface 44, a part of the incident second laser beam L2 is transmitted and the other part is reflected. That is, the second side surface 44 is a transmission / reflection surface that transmits and reflects the second laser beam L2. Hereinafter, the second side surface may be referred to as a second transmission reflection surface. Alternatively, the second side surface may be referred to as a second half mirror. The second laser beam L2 reflected by the second transmission reflection surface 44 (second side surface 44 or second half mirror 44) travels toward the emission surface 42 and is emitted from the emission surface 42.

The exit surface 42 is arranged so as to face the tube 61. The first laser beam L1 and the second laser beam L2 are emitted from the exit surface 42. The first laser beam L1 and the second laser beam L2 emitted from the exit surface 42 are incident on 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 is preferably parallel light, but in reality, it has a certain extent as shown in FIG. Therefore, in the first laser beam L1 incident on the first transmission / reflection surface 43, there is a component having a large incident angle on the first transmission / reflection surface 43 as shown by α1, and the first laser beam L1 as shown by β1. There is also a component in which the angle of incidence on the transmission and reflection surface 43 is small. The optical axis X1 of the first laser beam L1 is incident on the first transmission reflection surface 43 at an incident angle θi. The incident angle θi of the optical axis X1 of the first laser beam L1 is smaller than the critical angle θr of the first transmitted reflection surface 43. Of the first laser beam L1 incident on the first transmission reflection surface 43, a component having an incident angle smaller than the critical angle θr passes through the first transmission reflection surface 43. On the other hand, of the first laser beam L1 incident on the first transmission reflection surface 43, a component having an incident angle larger than the critical angle θr is reflected by the first transmission reflection surface 43. When the incident angle θi of the optical axis X1 of the first laser beam L1 is reduced, the number of components whose incident angle is smaller than the critical angle θr increases, and the number of components transmitted through the first transmitted reflection surface 43 increases (the reflected component increases). It will be less.) When the incident angle θi of the optical axis X1 of the first laser beam L1 is increased, the number of components whose incident angle is larger than the critical angle θr increases, and the number of components reflected by the first transmission reflection surface 43 increases (the transmitted components are). It will be less.)

The second laser beam L2 is the same as the first laser beam L1. The second laser beam L2 is preferably parallel light, but in reality, it has a certain extent as shown in FIG. Therefore, in the second laser beam L2 incident on the second transmission reflection surface 44, there is a component having a large incident angle on the second transmission reflection surface 44 as shown by α2, and a second laser beam L2 as shown by β2. There is also a component in which the angle of incidence on the transmission and reflection surface 44 of The optical axis X2 of the second laser beam L2 is incident on the second transmission reflection surface 44 at an incident angle θi. The incident angle θi of the optical axis X2 of the second laser beam L2 is smaller than the critical angle θr on the second transmitted reflection surface 44. In this embodiment, the incident angle θi of the optical axis X2 of the second laser beam L2 is the same incident angle θi as the incident angle θi of the optical axis X1 of the first laser beam L1. Further, the critical angle θr on the second transmission and reflection surface 44 is the same critical angle as the critical angle θr on the first transmission and reflection surface 43. Of the second laser beam L2 incident on the second transmission reflection surface 44, a component having an incident angle smaller than the critical angle θr passes through the second transmission reflection surface 44. On the other hand, of the second laser beam L2 incident on the second transmission reflection surface 44, a component having an incident angle larger than the critical angle θr is reflected by the second transmission reflection surface 44. When the incident angle θi of the optical axis X2 of the second laser beam L2 is reduced, the number of components whose incident angle is smaller than the critical angle θr increases, and the number of components transmitted through the second transmitted reflection surface 44 increases (the reflected component increases). It will be less.) When the incident angle θi of the optical axis X2 of the second laser beam L2 is increased, the number of components whose incident angle is larger than the critical angle θr increases, and the number of components reflected by the second transmission reflection surface 44 increases (the transmitted component increases). It will be less.)

As shown in FIG. 1, the first laser beam L1 and the second laser beam L2 emitted from the exit surface 42 of the light guide body 24 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 light L1 and the second laser light L2 are irradiated from the laser light 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 is a particle R that passes 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 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 irradiating 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 light guide body 24 of the laser light irradiation device 2. The light receiving device 3 includes a light receiving element 31 and a tubular body 32.

The tubular body 32 is arranged between the tube 61 and the light receiving element 31. The tubular body 32 is fixed to the light receiving element 31. The tubular body 32 has a cylindrical shape. As shown in FIG. 3, the inside of the cylinder 32 is hollow. A light passing hole 35 is formed in the cylinder 32. The light passage hole 35 includes an entrance port 36 and an exit port 37. The light passing hole 35 extends in the direction from the measurement point 10 toward the light receiving element 31. The light passing hole 35 is formed between the measuring point 10 and the light receiving element 31. 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. The first scattered light P1 and the second scattered light P2 traveling from the measurement point 10 toward the light receiving element 31 pass through the light passing hole 35. The first scattered light P1 and the second scattered light P2 that have passed through the light passing hole 35 are emitted from the exit port 37 and incident on the light receiving element 31. The outer peripheral surface of the tubular body 32 is covered with a light-shielding cover 312. No light is incident on the light passing hole 35 from the outer peripheral surface of the tubular body 32. The light P3 traveling from the side of the tubular body 32 in the direction intersecting the axial direction of the light passing hole 35 is blocked by the cover 312 and does not enter the light passing hole 35. Scattered lights P1 and P2 traveling in the axial direction of the light passing hole 35 are incident on the light passing hole 35. The axial length of the light passing hole 35 is more than twice the diameter of the incident port 36.

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 other part is covered with the cover 312. The scattered lights P1 and P2 emitted from the exit port 37 are incident on the light receiving element 31. The light P4 traveling from the side of the light receiving element 31 toward the light receiving element 31 is blocked by the cover 312 and does not enter the light receiving element 31.

As shown in FIG. 4, 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 the following equation (1). In the formula (1), F is the Doppler frequency of the light received by the light receiving device 3 (the 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.

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 is the first laser light L1 and the second laser. It includes a laser light irradiating device 2 that irradiates the light L2, and a light receiving device 3 that receives the first scattered light P1 and the second scattered light P2. The first laser beam L1 and the second laser beam L2 travel from different directions toward the measurement point 10 in the flow path 60. When the first laser beam L1 hits the particles R passing through the measurement point 10, the first scattered light P1 is generated. When the second laser beam L2 hits the particle R passing through the measurement point 10, the second scattered light P2 is generated. The light receiving device 3 receives the first scattered light P1 and the second scattered light P2. The light receiving device 3 includes a light receiving element 31 and a hollow light passing hole 35 formed between the light receiving element 31 and the measurement point 10. The light passing hole 35 extends in the direction from the measurement point 10 toward the light receiving element 31. The first scattered light P1 and the second scattered light P2 generated by the particles R passing through the measurement point 10 pass through the light passing hole 35 and enter the light receiving element 31.

According to the above configuration, the light receiving device 3 receives the first scattered light P1 and the second scattered light 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 frequency f1 of the first scattered light P1 and the frequency f2 of the second scattered light 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 generate scattered light. However, in the above configuration, since the light passing hole 35 is provided, only the scattered light generated by the particles R passing through the measurement point 10 can be received, and the scattered light generated by the particles R passing around the measurement point 10 can be received. It is possible to suppress receiving scattered light. 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 is incident on the light receiving element 31, but the scattered light generated by the particles R passing around the measurement point 10 is incident on 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.

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 speed of the particles R. However, according to the above configuration, it is possible to suppress the reception of excess scattered light, so that the velocity of the particle R can be calculated accurately.

Further, in the above-mentioned measuring device 1, the laser light irradiating device 2 uses the light emitting element 21 that emits the laser light L and the laser light L emitted by the light emitting element 21 as the first laser light L1 and the second laser light L2. The diffraction grating 23 is divided into two parts. The first laser beam L1 and the second laser beam L2 separated by the diffraction grating 23 travel in different directions. Further, the laser light irradiation device 2 includes a first transmission reflection surface 43 on which the first laser light L1 separated by the diffraction grating 23 is incident, and a second transmission reflection surface 44 on which the second laser light L2 is incident. It has. In the first transmission reflection surface 43, a part of the incident first laser light L1 is transmitted, the other part is reflected, and the reflected first laser light L1 travels toward the measurement point 10. In the second transmission reflection surface 44, a part of the incident second laser light L2 is transmitted, the other part is reflected, and the reflected second laser light L2 travels toward the measurement point 10. .. The first transmission / reflection surface 43 is composed of the first side surface 43 of the light guide body 24, and may be referred to as a first half mirror 43 that transmits and reflects the first laser beam L1. Further, the second transmission / reflection surface 44 is composed of the second side surface 44 of the light guide body 24, and may be referred to as a second half mirror 44 that transmits and reflects the second laser beam L2.

According to such a configuration, the transmitted component of the first laser beam L1 incident on the first transmitted reflecting surface 43 can be removed, and only the reflected component advances toward the measurement point 10. Therefore, the intensity of the first laser beam L1 traveling toward the measurement point 10 can be weakened. Similarly, of the second laser beam L2 incident on the second transmission reflecting surface 44, the transmitted component can be removed, and only the reflected component travels toward the measurement point 10, so that the measurement point 10 The intensity of the second laser beam L2 traveling toward is weakened. By weakening the intensity, when the first laser light L1 and the second laser light L2 are irradiated toward the measurement point 10, the first laser light L1 and the second laser light L2 become the measurement point 10. It is possible to suppress the spread to the periphery of. Therefore, it is possible to suppress the generation of scattered light by the particles passing around the measurement point 10. Therefore, it is possible to suppress receiving extra scattered light. In the measuring device disclosed in Patent Document 1, since the laser light incident on the side surface of the light guide is totally reflected, there is no transmitted component. Therefore, the intensity of the laser beam cannot be weakened.

Further, in the above-mentioned measuring device 1, the incident angle θi of the optical axis X1 of the first laser beam L1 incident on the first transmitted reflecting surface 43 is smaller than the critical angle θr on the first transmitted reflecting surface 43. Further, the incident angle θi of the optical axis X2 of the second laser beam L2 incident on the second transmissive reflection surface 44 is smaller than the critical angle θr on the second transmissive reflection surface 44. According to such a configuration, the transmitted component can be increased (the reflected component can be reduced) in the first laser beam L1 incident on the first transmitted reflecting surface 43. Similarly, the transmitted component can be increased (the reflected component can be reduced) in the second laser beam L2 incident on the second transmitted reflecting surface 44. As a result, the intensities of the first laser beam L1 and the second laser beam L2 traveling toward the measurement point 10 can be weakened. Therefore, when the first laser light L1 and the second laser light L2 are irradiated toward the measurement point 10, the first laser light L1 and the second laser light L2 spread around the measurement point 10. Can be suppressed.

Further, the above-mentioned measuring device 1 includes a moving device 25 that changes the distance between the diffraction grating 23 and the first transmission / reflection surface 43 and the second transmission / reflection surface 44. According to such a configuration, the positions where the first laser light L1 and the second laser light L2 separated by the diffraction grating 23 are incident on the first transmission reflection surface 43 and the second transmission reflection surface 44 are changed. be able to. Thereby, the position where the first laser beam L1 and the second laser beam L2 are irradiated can be changed, and the position of the measurement point 10 in the flow path 60 can be changed.

Further, in the above-mentioned measuring device 1, the diffraction grating 23 is a reflection type diffraction grating. Further, the light emitting element 21 is arranged between the diffraction grating 23, the first transmission reflecting surface 43, and the second transmission reflection surface 44, and the laser light L emitted by the light emitting element 21 is reflected by the diffraction grating 23. As a result, the first laser beam L1 and the second laser beam L2 are separated. According to such a configuration, the light emitting element 21 can be accommodated between the diffraction grating 23 and the light guide body 24, so that the measuring device 1 can be made compact.

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.

In the above embodiment, the first transmission reflection surface 43 and the second transmission reflection surface 44 are formed on the single light guide body 24, but the present invention is not limited to this configuration. In another embodiment, as shown in FIG. 5, the laser light irradiation device 2 may include a first light guide body 241 and a second light guide body 242 that are separated from each other. The first light guide body 241 is formed with a first transmission reflection surface 43, and the second light guide body 242 is formed with a second transmission reflection surface 44. Even with such a configuration, a part of the first laser beam L1 incident on the first transmission reflection surface 43 is transmitted, and the other part is reflected. Further, a part of the second laser beam L2 incident on the second transmission reflection surface 44 is transmitted, and the other part is reflected.

Further, the shape of the light passing hole 35 is not particularly limited. For example, as shown in FIG. 6, the cross-sectional shape of the light passing hole 35 may be circular. Alternatively, as shown in FIG. 7, the cross-sectional shape of the light passing hole 35 may be polygonal. Further, as shown in FIG. 8, a plurality of light passing holes 35 may be formed in a slit shape.

Further, the configuration of the light receiving device 3 is not limited to the above embodiment. In another embodiment, as shown in FIG. 9, the light receiving device 3 may include 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 and the light receiving element 31. The rear wall 38b is arranged between the light receiving element 31 and the laser light irradiating device 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 light passing hole 35 is formed in the front wall 38a. The light passage hole 35 includes an entrance port 36 and an exit port 37. The light passing hole 35 extends in the direction from the measurement point 10 toward the light receiving element 31. The first scattered light P1 and the second scattered light P2 generated by the particles R passing through the measurement point 10 pass through the light passing hole 35 and enter the light receiving element 31. The light P4 traveling from the side of the box body 38 toward the light receiving element 31 is blocked by the box body 38 and does not enter the light receiving element 31. Further, even if the light P5 traveling toward the light passing hole 35 in a direction intersecting the axial direction of the light passing hole 35 passes through the light passing hole 35 and enters the box body 38, the side wall of the box body 38 Since it travels toward 38c, it is unlikely to enter the light receiving element 31. Therefore, it is possible to prevent the light receiving element 31 from receiving excess light.

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 this 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: Corimeter lens 23: Diffraction grating 24: Light guide body 25: Moving device 31: Light receiving element 32: Cylinder 35: Light passage hole 36: Incident port 37: Exit port 38: Box body 41: Incident surface 42: Exit surface 43: First side surface (first transmission reflection surface)
44: Second side surface (second transmission reflection surface)
60: Flow path 61: Tube 62: Fixture 241: First light guide body 242: Second light guide body 312: Cover F: Fluid L: Laser light L1: First laser light L2: Second laser Light P1: First scattered light P2: Second scattered light R: Particle X1: Optical axis of first laser light X2: Optical axis of second laser light

Claims (5)

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 a measurement point in the flow path and a second laser light traveling toward the measurement point in the flow path from a direction different from the first laser light. 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 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 element and the measuring point.
A measurement in which 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 is incident on the light receiving element. It ’s a device ,
The laser light irradiation device is
A light emitting element that emits laser light and
A diffraction grating that divides the laser light emitted by the light emitting element into a first laser light and a second laser light traveling in a direction different from that of the first laser light.
A first transmitted reflection surface on which the first laser beam separated by the diffraction grating is incident, and a part of the incident first laser beam is transmitted and the other part is reflected and reflected. The first transmitted reflection surface on which the laser light of 1 travels toward the measurement point, and
It is a second transmission reflection surface on which the second laser light separated by the diffraction grating is incident, and a part of the incident second laser light is transmitted, and the other part is reflected and reflected. A measuring device including the second transmitted reflecting surface in which a second laser beam travels toward the measuring point. The light receiving device includes a hollow cylinder arranged between the light receiving element and the measurement point, and a light-shielding cover that covers the outer peripheral surface of the cylinder.
The measuring device according to claim 1, wherein a light passing hole is formed in the cylinder. The angle of incidence of the optical axis of the first laser beam incident on the first transmission / reflection surface is smaller than the critical angle on the first transmission / reflection surface.
The measuring device according to claim 1 or 2 , wherein the incident angle of the optical axis of the second laser beam incident on the second transmitted reflecting surface is smaller than the critical angle on the second transmitted reflecting surface. The measuring device according to any one of claims 1 to 3 , further comprising a moving device for changing the distance between the diffraction grating and the first transmission / reflection surface and the second transmission / reflection surface. The diffraction grating is a reflection type diffraction grating,
The light emitting element is arranged between the diffraction grating and the first transmission reflection surface and the second transmission reflection surface, and the laser light emitted by the light emitting element is reflected by the diffraction grating to cause a first. The measuring device according to any one of claims 1 to 4 , which is divided into a laser beam of the above and a second laser beam.

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